Title of Invention	"PUMP CONTROL DEVICE FOR HYDRAULIC WORKING MACHINE, PUMP CONTROL METHOD, AND CONSTRUCTION MACHINE"
Abstract	A pump control apparatus for a hydraulic work machine includes: a rotation speed setting device that sets a target rotation speed for an engine; a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine; a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine outputtorquedeterminedinadvancebaseduponthetargetrotation speed. The pump control device a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and b) regulates the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulicpump and subtracting the intake torque of the second variable hydraulic pump from the engine outputtorquedeterminedinadvancebaseduponthetargetrotation speed.

Title of Invention

"PUMP CONTROL DEVICE FOR HYDRAULIC WORKING MACHINE, PUMP CONTROL METHOD, AND CONSTRUCTION MACHINE"

Abstract

A pump control apparatus for a hydraulic work machine includes: a rotation speed setting device that sets a target rotation speed for an engine; a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine; a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine outputtorquedeterminedinadvancebaseduponthetargetrotation speed. The pump control device a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and b) regulates the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulicpump and subtracting the intake torque of the second variable hydraulic pump from the engine outputtorquedeterminedinadvancebaseduponthetargetrotation speed.

Full Text	DESCRIPTION PUMPCONTROLAPPARATUSFORHYDRAULICWORKMACHINE, PUMP CONTROL METHOD AND CONSTRUCTION MACHINE TECHNICAL FIELD [0001] The present invention relates to a pump control apparatus forahydraulicworkmachinethatcontrolsapluralityofhydraulic pumpsdrivenbyanengine,apumpcontrolmethodandaconstruction machine. BACKGROUND ART [0002] The pump control apparatuses used in similar applications include the apparatus disclosed in patent reference literature 1. The apparatus disclosed in patent reference literature 1 controls an actuator-drive hydraulic pump and a fan-drive hydraulic pump, both driven by an engine, as described below. Namely, it calculates a required rotation speed for a cooling fan based upon the cooling water temperature or the lubricating oi 1 temperature and controls the output flow rate at the fan-drive hydraulic pump in correspondence to the required rot at ion speed. Then, it calculates the intake torque of the fan-drive hydraulic pump based upon the output flow rate and adjusts the intake torque of the actuator-drive hydraulic pump in correspondence totheextenttowhichtheintaketorqueofthe fan-drivehydraulic pump is increased/decreased. The excess intake torque that is not used at the fan-drive hydraulic pump is thus allocated to be used as the intake torque at the actuator-drive hydraulic pump. [0003] Patent reference literature 1: Japanese Laid Open Patent Publication No. 2005-188674 DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0004] There is an issue to be addressed with regard to the apparatus disclosed in patent reference literature 1 in that since the hydraulicpumpsarecontrolledbasedupon the detect ion value indicating the detected engine rotation speed, the pump control is bound to be destabilized when the engine rotation speed fluctuates. MEANS FOR SOLVING THE PROBLEMS [0005] A pump control apparatus for a hydraulic work machine according to a first aspect of the present invention includes: a rotation speed setting device that sets a target rotation speedforanengine;arotationspeedcontroldevicethatcontrols an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by theengine; a second variable hydraulic pump used to drive a cooling fan, drivenbytheengine; andapump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulicpumpdoesnot exceedanengineoutputtorquedetermined in advance based upon the target rotation speed, wherein: the pump control device; a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and b) regulates the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulic pump from the engine outputtorquedeterminedinadvancebaseduponthetargetrotation speed. In the pump control apparatus for a hydraulic work ma chine according to the first aspect, it is preferable to further include at least one of an oil temperature detection device thatdetectsalubricatingoiltemperatureandawatertemperature detectiondevicethatdetectsanenginecoolingwatertemperature, and it is preferable that the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at least one of a target flow rate corresponding to the lubricating oil temperature detected by the lubricating oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device. The pump control apparatus for a hydraulic work machine according to the first aspect may further include at least one of an oil temperature detection device that detects an oil temperature (hereafter referred to as a hydraulic fluid temperature) of oil returning from the work hydraulic actuator and a water temperature detection device that detects an engine cooling water temperature, wherein: the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at least one of a target flow rate corresponding to the hydraulic fluid temperature detected by the oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device. In the pump control apparatus for a hydraulic work machine according to the first aspect, it is preferable to further include: a rotation speed detection device that detects an actual rotation speed of the engine; and a correction torque calculation device that calculates a correction torque correspondingtoadeviationoftheactualrotationspeeddetected by the rotation speed detection device relative to the target rotation speed set by the rotation speed setting device, and it is preferable that the pump control device corrects the intake torque of the first variable hydraulic pump by using the correction torque calculated by the correction torque calculation device. The pump control device may c) calculate a fan rotation speed for the cooling fan based upon the target rotation speed and the target output flow rate of the second variable hydraulic pump; d) calculate an output pressure at the second variable hydraulic pump corresponding to the fan rotation speed based uponpredeterminedcharacteristics; ande) calculatetheintake torque of the second variable hydraulic pump in correspondence to the output pressure having been calculated. A pump control apparatus for a hydraulic work machine according to a third aspect includes: a rotation speed setting device that sets a target rotation speed for an engine; a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine; a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: the pump control device; a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; andb) executes adjustment based upon the intake torque of the second variable hydraulic pump and the target rotation speed so as to stabilize the intake torque of the first variable hydraulic pump irrespective of an actual rotation speed of the engine. A pump control method according to a third aspect of the present invention is adopted in a hydraulic work machine to control a first variable hydraulic pump used to drive a work hydraulic actuator and a second variable hydraulic pump used to drive a cooling fan, both driven by an engine controlled to achieve a target rotation speed, by ensuring that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: an output flow rate of the second variable hydraulic pump is controlled based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and the intake torque of the first variable hydraulic pump is regulated by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulic pump from the engine output torque determined in advance based upon the target rotation speed. A construction machine according to a fourth aspect of thepresentinventionincludesapumpcontrolapparatusaccording to the first aspect. ADVANTAGEOUS EFFECT OF THE INVENTION [0006] According to the present invention, the intake torque ofthefirstvariablehydraulicpumpfordrivingtheworkhydraulic actuator is controlled based upon the intake torque of the second variable hydraulic pump for driving the cooling fan andthetargetenginerotationspeed, andthus, thef irstvariable hydraulic pump can be controlled with a high level of stability even if the actual rotation speed of the engine fluctuates due to a fluctuation of the load on the work hydraulic actuator. BRIEF DESCRIPTION OF THE DRAWINGS [0007] FIG. 1 is a side elevation of a hydraulic excavator which may adopt an embodiment of the present invention; FIG. 2 schematically illustrates the structures assumed in an engine installed in the hydraulic excavator in FIG. 1 and its peripheral components; FIG. 3 is a hydraulic circuit diagramshowing the structure of a pump control device achieved in the embodiment of the present invention; FIG. 4 is a block diagram showing the internal structure of a controller in FIG. 3; FIG. 5 is a block diagram showing specific details of the processing executed in the controller; FIG. 6 presents a diagram of characteristics based upon which speed sensing control may be executed; and FIG. 7 isahydrauliccircuitdiagramshowingthestructure of the pump control device achieved in a variation of the embodiment. BEST MODE FOR CARRYING OUT THE INVENTION [0008] The following is an explanation of an embodiment of a pump control device according to the present invention, given in reference to FIGS,. 1 through 6. FIG. 1 is a side elevation of a large hydraulic excavator 1 that may adopt the embodiment of the present invention. A revolving superstructure 4 is rotatably mounted on a traveling undercarriage 3 equipped with crawler tracks 2. Mounted on the revolving superstructure 4, are an operator's cab 5 and a front work unit 6 capable of articulating up/down freely. The front work unit 6 is constituted with a boom 7, an arm 8 and a bucket 9 which are respectively engaged in operation via a boom cylinder 10, an arm cylinder 11 and a bucket cylinder 12. [0009] FIG. 2 schematically illustrates the structures assumed in an engine 13 installed in the hydraulic excavator 1 and its peripheral components. Air is taken into the engine 13 via an intake manifold 14, a mixed gas constituted with the air and fuel is combusted in cylinders 15 and the exhaust gas is discharged via an exhaust manifold 16. The exhaust gas drives a turbine 17,. and the air taken in through the intake manifold 14 is cooled at an intercooler 18. Cooling water used to cool the engine 13 is cooled at a radiator 20 as it circulates through the radiator 20 via a cooling water pipe 19 . Cooling air is delivered to the intercooler 18, the radiator 20 and an oil cooler 22 as a cooling fan 21a is driven. [0010] A pair of variable-displacement hydraulic pumps 26 and 27 and a fixed-displacement hydraulic pump 28 are connected via a transmission 25 to an output shaft 23 of the engine 13. The rotation of the output shaft 23 at the engine 13 is detected by a rotation speed sensor 24. [0011] The hydraulic pump 26 is an actuator pump through which drive pressure oil is supplied to a plurality of hydraulic actuators (the boom cylinder 10, the arm cylinder 11, thebucket cylinder 12, a travelinghydraulicmotor, a revolving hydraulic motor and the like) . The hydraulic pump 2] is a fan pump through which drive pressure oil is supplied to a hydraulic motor 21 (fan motor) through a hydraulic piping 29. The rotation of the cooling fan 21a is controlled via the fan motor 21, which is driven in correspondence to the quantity of pressure oil supplied thereto. It is to be noted that while an explanation is given by assuming, for purposes of simplification, that the hydraulic excavator includes a single actuator pump 26 and a single fan pump 27, the excavator may include a plurality of actuator pumps and fan pumps. The hydraulic pump 28 is a mission pump through which mission oil 30 stored in a mission casing 31 is supplied to the oil cooler 22. [0012] FIG. 3 is a hydraulic circuit diagram showing the structure adopted in the pump control device in the embodiment. It is to be noted that, for purposes of simplification, FIG. 3 shows a single actuator (hydraulic cylinder 32) representing the plurality of hydraulic actuators including the boom cylinder 10, the arm cylinder 11, the bucket cylinder 12, the driving hydraulic motor and the revolving hydraulic motor. [0013] Pressure oil is supplied to the actuator 32 from the actuator pump 26, with the flow of the pressure oil to the actuator 32 controlled through a control valve 33 . The control valve 33 is switched with a pilot pressure from a pilot pump, the level of which corresponds to an operation of an operation lever 34a. An output pressure Pt with which the pressure oil is output from the actuator pump 26 is detected by a pressure sensor 26a, whereas pilot pressures Pia and Pib generated in response to the operation of the operation lever 34a are detected by pressure sensors 34b and 34c. [0014] The displacement (may also be referred to as the swash plate angle or the displacement angle) of the actuator pump 26 is controlled by a regulator 35, whereas the displacement (mayalsobereferredtoastheswashplateangleorthedisplacement angle) of the fan pump 27 is controlled by a regulator 36. Pilot pressures imparted from a pilot pump 48 in correspondence to the extents to which electromagnetic proportional pressure-reducing valves 4 5 and 4 6 are driven are respectively applied to the regulators 35 and 36. The electromagnetic proportional pressure-reducing valves 45 and 46 are controlled as detailed later based upon control signals provided by a controller 38. [0015] Thepressuresensors26a, 34band34candanoiltemperature sensor 38a that detects the temperature Toil of the lubricating oil at the oil cooler 22 (see FIG. 2) are connected to the controller 38 and an engine control device 39 is also connected to the controller 38 via a network 40. A water temperature sensor 37a that detects the temperature Tw of the cooling water at the radiator 20 (see FIG- 2) and a rotation speed setting unit 39a that sets a target rotation speed Nr for the engine 13 (more specifically for the output shaft 23) are connected to the engine control device 39. As a dial, for instance, is operated, the target rotation speed Nr is set at the rotation speed setting unit 39a. It is to be noted that the target rotation speed Nr may instead be set by operating a lever, an accelerator pedal or the like. The engine control device 39 outputs a control signal to a pulse motor used to drive a governor lever (not shown) and controls the actual rotation speed of the engine 13 (i.e., the rotation speed detected by the rotation speed sensor 24) so as to adjust it to the target rotation speed Nr. [0016] FIG. 4 is a block diagram showing the internal structure ofthecontroller38. Thecontroller38 includesanA/Dconverter 41thatexecutesA/Dconversionofthedetectionsignalsprovided from the pressure sensors 2 6a, 3 4b and 34 c and the oil temperature sensor 38a, a ROM 42 in which a control program and various constants are stored, a RAM 42a, a CPU 43 that executes specific arithmetic processing based upon a control program stored in the ROM 42, a network interface circuit 4 4 that exchanges signals via the network 40 and an output circuit 47 that amplifies a drive signal generated at the CPU 43 and outputs the amplified signal to the solenoids at the electromagnetic proportional pressure-reducing valves 45 and 46 to be used as a pulse width modulation output signal. [0017] FIG. 5 is ablockdiagramshowingdetails of theprocessing executed in the controller 38 (in the CPU 43 in particular) . The lubricating oil temperature Toil detected by the oil temperature sensor 38a is input to a signal generation unit 43a. Characteristics whereby the flow rate Qoil at which oil is delivered to the fan motor 21 increases as the lubricating oil temperature Toil becomes higher, as shown in the figure, i.e., characteristics whereby the rotation speed of the cooling fan 21a increases as the lubricating oil temperature rises, are stored in advance at the signal generation unit 43a. The signal generation unit 4 3a calculates the flow rate Qoil corresponding to the lubricating oil temperature Toil based upon the characteristics. [0018] The cooling water temperature Tw detected by the water temperature sensor 37a is input to a signal generation unit 43b via the network 40. Characteristics whereby the flow rate Qw at which oil is delivered to the fan motor 21 increases as the cooling water temperature Tw becomes higher, as shown inthefigure, i.e., characteristics whereby the rotation speed of the cooling fan 2 la increases as the cooling water temperature rises, are stored in advance at the signal generation unit 43b. The signal generation unit 43b calculates the flow rate Qw corresponding to the cooling water temperature Tw based upon the characteristics. A MAX selection unit 43c selects either of the flow rates Qoil and Qw output from the signal generation units 4 3a and 4 3b, whichever is indicating the greater value, and outputs the selected flow rate as a target flow rate Qp2. [0019] A displacement calculation unit 43d divides the target flow rate Qp2 output from the MAX selection unit 43c by the target rotation speed Nr set at the rotation speed setting unit 39a. It then selects either the quotient (Qp2/Nr) or a maximum value Dp2max of the displacement of the fan pump 27, whicheverindicatesthesmallervalueandoutputstheselected value as a target displacement D2. A relationship between the target displacement D2 and a control current 12 such as that shown in the figure is stored in advance at a signal generation unit 43q, which calculates the control current 12 corresponding to the target displacement D2 based upon the relationship and outputs the control current 12 thus determined to the output circuit 47. As a result, the displacement of the fan pump 27 is controlled to match the target displacement D2. [0020] A rotation speed calculation unit 4 3e executes a specific arithmetic operation (D2 x Nr x r\|v/Dm) by using the target rotation speed Nr set at the rotation speed setting unit 39a and the target displacement D2 calculated by the displacement calculation unit 43d and thus determines a rotation speed Nf for the cooling fan 21a - r\|v represents the product of the volumetric efficiency of the fan pump 27 and the volumetric efficiency of the fan motor 21, whereas Dm represents the displacement of the fan motor 27. [0021] Based upon the characteristics shown in the figure, stored therein in advance, an output pressure calculation unit 43f converts the rotation speed Nf calculated at the rotation speed calculation unit 43e to an output pressure Pfp of the fan pump 27. The characteristics stored in the output pressure calculation unit 4 3f are determined through testing, simulation or the like conducted in advance. In other words, the characteristics can be set at the output pressure calculation unit 43f based upon the relationship between the pump output pressure Pfp and the fan rotation speed Nf, the drive flow rate at the fan motor 21 or the output flow rate at the pump 27 determined by varying the output flow rate of the fan pump 27. [0022] A torque calculation unit 4 3g executes a specific arithmetic operation (D2 x Pfp/2n) to calculate a torque by usingthepumpoutputpressurePfpoutputfromtheoutputpressure calculation unit 43f and the target displacement D2 for the fan pump 27 output from the displacement calculation unit 43d. It then selects either the calculated value or a maximum intake torque Tp2max of the pump 27 controlled by the regulator 36, whichever indicates the smaller value and outputs the selected value as an intake torque Tp2 of the fan pump 27. Thus, the intake torque Tp2 of the fan pump 27 can be determined without having to detect the output pressure Pfp via a pressure sensor or the like. [0023] Characteristics of a reference torque Ta corresponding to the target rotation speed Nr of the engine 13 such as those shown in the figure are stored in advance at a reference torque calculation unit 4 3h. These characteristics are set based upon the output characteristics of the engine 13, along the full load performance curve of the engine 13 without deviating from full load performance curve. Based upon the characteristics, the reference torque calculation unit 43h calculates the reference torque Ta corresponding to the target rotation speed Nr set at the rotation speed setting unit 39a. A subtraction unit 43i subtracts the pump intake torque Tp2 output from the torque calculation unit 43g from the reference torque Ta output from the reference torque calculation unit 43h (Ta - Tp2), thereby determining a control value (control torque Tpl) for the intake torque at the actuator pump 26. [0024] Characteristics of a target displacement Dt of the pump 26, which correspond to the output pressure Pt and the control torque Tpl at the actuator pump 26, such as those shown in the figure, are stored in advance at a displacement calculation unit 43j . The target displacement Dt assuming these characteristics decreases as the output pressure Pt increases and the target displacement Dt increases relative to the output pressure Pt as the control torque Tpl increases. Based upon the characteristics, the displacement calculation unit 43j calculates the target displacement Dt corresponding to the output pressure Pt detected by the pressure sensor 26a and the control torque Tpl output from the subtraction unit 43i. [0025] AMAXselectionunit 43kselects eitherthepilotpressure Pia detected by the pressure sensor 34b or the pilot pressure Pib detected by the pressure sensor 34c, whichever indicates the greater value and outputs the selected pilot pressure as a representativepressure Pi. Characteristicswherebyatarget displacement Di increases as the pilot pressure Pi increases, as shown in the figure, are stored in advance at a displacement calculation unit 43m, Based upon the characteristics, the displacement calculation unit 43m calculates the target displacement Di corresponding to the pilot pressure Pi output from the MAX selection unit 43k. [0026] A MIN selection unit 43n selects either the target displacement Dt output from the displacement calculation unit 43j or the target displacement Di output from the displacement calculation unit 43m, whichever indicates the smaller value, and outputs the selected value as a target displacement DI to be used to control the actuator pump 26. A relationship between the target displacement DI and a control current II such as that shown in the figure is stored in advance at a signal generation unit 4 3p, which calculates the control current II corresponding to the target displacement D1 based upon the relationship and outputs the control current I1 thus determined to the output circuit 47. As a result, the displacement of theactuatorpump26iscontrolledtomatchthetargetdisplacement DI and the intake torque at the hydraulic pump 26 is regulated so as not to exceed the control torque Tpl. [0027] The operations of the pump control device achieved in the embodiment are summarized below. When the hydraulic excavator is to be engaged in work, the opera tor per forms a dial operation to set the target rotation speed Nr for the engine 13. Accordingly, the engine control device 39 controls the engine rotation speed so as to match the target rotation speed Nr. As the operator operates the operation lever 34a in this state, the control valve 33 is switched in correspondence to the extent to which the operation lever is operated, and the actuator 32 becomes driven. Subsequently, the cooling water temperature Tw of the cooling waterusedtocooltheenginel3andthelubricatingoiltemperature Toil change in correspondence to the work load and the like applied to the hydraulic excavator. [0028] Thecontroller38determinesthrougharithmeticoperation the output flow rates Qoil and Qw for the fan pump 27 in correspondence to the cooling water temperature Tw and the lubricating oil temperature Toil respectively and the flow rate indicating the greater value is selected as the target flow rate Qp2 (43a through 43c) . Then, the target rotation speed Nr is used to calculate the target displacement D2 of the pump 27 corresponding to the target flow rate Qp2 (43d) , the control signal 12 corresponding to the target displacement D2 is output to the solenoid at the electromagnetic proportional pressure-reducing valve 46 and thus, the displacement of the hydraulic pump 27 is controlled so as to match the target displacement Qp2. As a result, the cooling fan 21a rotates at the target speed, thereby disallowing any excessive increase in either the cooling water temperature Tw or the lubricating oil temperature Toil. [0029] In addition, the controller 38 calculates the rotation speed Nf of the cooling fan 21a by using the target displacement D2 of the fan pump 27, the target rotation speed Nr of the enginel3andthevolumetricefficiencyri (43e)andalsocalculates the output pressure Pfp of the pump 27 corresponding to the fan rotation speed Nf based upon preset characteristics (4 3f) . It then calculates the intake torque Tp2 of the pump 27 by using the pump output pressure Pfp and the target displacement D2 (43g), subtracts the intake torque Tp2 from the reference torque Ta of the engine 13 and thus, determines the control value Tpl for the intake torque at the actuator pump 2 6 (43i) . Either the displacement Dt of the pump 26 determined based upon the control torque Tpl and the output pressure Pt at the pump 2 6 or the displacement Di of the pump 2 6 corresponding to the extent to which the operation lever 34a is operated, whichever indicates the smaller value, is then set as the target displacement Dl (43j, 43m and 43n) . The control signal II corresponding to the target displacement Dl is output to the solenoidattheelectromagneticproportionalpressure-reducing valve 45 so as to control the displacement of the hydraulic pump 26 to match the target displacement Dl. As a result, the intake torque at the hydraulic pump 26 is controlled so as to not exceed the control torque Tpl. [0030] For instance, when the Dt [0031] The f ol lowing operational effect scan be achieved through the embodiment described above. (1) Based upon the target rotation speed Nr selected for the engine 13 through a dial operation, the intake torque Tp2 of the fan pump 27 is calculated and then based upon the intake torque Tp2 and the target rotation speed Nr, the intake torque at the actuator pump 26 is adjusted. As a result, even when the actual rotation speed of the engine 13 fluctuates, the displacements of the pumps 2 6 and 27 remain unchanged, enabling stable control. Since the rotation speed Nf of the cooling fan 21a is determined through arithmetic operation executed by using the target rotation speed Nr and the target displacement D2 of the fan pump 27 (43e) , no rotation sensor needs to be installed specifically to detect the fan rotation speed Nf. The fan rotation speed Nf is calculated by taking into consideration the volumetric efficiencies r\| of the fan pump 27 and the fan motor 21 (43e) , which improves the rotation speed calculation accuracy. Based upon the relationship between the fan rotation speed Nf and the output pressure Pfp of the pump 27 set in advance, the pump output pressure Pfp corresponding to the fan rotation speed Nf is determined (43f). Since this allows the pump output pressure Pfp to be determined without having to use a pressure sensor, the control device can be configured at low cost. [0032] It is to be noted that the present invention is not limited to the embodiment described above and allows for numerous variations . For instance, in addition to the control executed in the embodiment, the following speed sensing control may be executed. FIG.. 6 is a characteristics diagram of characteristics whereby a correction torque AT increases as a deviation AN of the actual rotation speed of the engine 13 relative to the target rotation speed increases, based upon which speed sensing control may be executed. Such characteristics should be stored in advance in the controller 38 . It is to be noted that speed sensing characteristics other than those shown in FIG. 6 may be used. [0033] The controller 38 executing speed sensing control determines the deviation AN of the actual rotation speed of the engine 13 detected via the rotation speed sensor 2 4 relative to the target rotation speed Nr and determines the correction torque AT corresponding to the deviation AN based upon the characteristics shown in FIG. 6. It then executes torque correction by adding the correction torque AT to the control torque Tpl determined at the subtraction unit 43i (Tpl + AT) andoutput st he corrected tor que to the displacement calculation unit 43j . Thus, if there is sufficient margin with regard to the torque at the engine 13, the correction torque AT assumes a positive value to increase the control torque Tpl, whereas in the event of a torque over, the correction torque assumes a negative value resulting in a decrease in the control torque Tpl. Consequently, since the sum of the intake torques at the pumps 26 and 27 is allowed to assume a value close to the rated torque, efficient utilization of the engine output is enabled. [0034] Since the control torque Tpl, to which the correction torque AT is subsequently added is calculated without using the actual rotation speed of the engine 13, successful execution of speed sensing control is assured. Namely, if the control torque Tpl is calculated by using the actual rotation speed a fluctuation in the engine rotation speed will result in fluctuations in both the control torque Tpl and the correction torque AT and thus, Tpl + AT will fluctuate to a greater extent, destabilizing the operation significantly. If, on the other hand, the control torque Tpl is calculated by using the target rotation speed Nr, a fluctuation in the engine rotation speed will only result in a fluctuation in the correction torque AT and thus, Tpl + AT will fluctuate to a smaller extent, assuring more stable operation. [0035] It is to be noted that the extent of fluctuation in the intake torque Tp2 may be lessened by, for instance, restricting the rate at which the target flow rate Qp2 of the fan pump 27 changes. While the target rotation speed Nr for the engine 13 is set via the rotation speed setting unit 39a, any other rotation speed setting means may be used. While the engine control device 39 controls the engine rotation speed so as to adjust it to the target rotation speed Nr, any other rotation speed control means may be used- In addition, the structures of the actuator pump 2 6 constituting the f irstvariablehydraulic pumpandthefanpump27constitutingthesecondvariablehydraulic pump are not limited to those described above. [0036] The processing executed in the controller 38 constituting the pump control means is not limited to that described above, as long as the output flow rates of the pumps 26 and 27 are controlled so as to ensure that the sum of the intake torques of the actuator pump 2 6 and the fan pump 27 does not exceed the reference torque Ta which is set in advance based upon the target rotation speed Nr for the engine 13. Namely, the controller 38 constituting the pump control means may execute processing other than that described above as long as it controls the output flow rate of the pump 27 and calculates the intake torque Tp2 of the pump based upon the target rotation speed Nr and the target output f low rate Qp2 of the pump 27 and regulates the intake torque Tpl of the pump 26 by subtracting the intake torque Tp2 from the reference torque Ta. In addition, while the lubricating oil temperature Toil is detected via the oil temperature sensor 38a and the cooling water temperature Tw isdetectedbythewatertemperaturesensor37a,anoiltemperature detectionmeansandawatertemperaturedetectionmeansadopting different structures may be used instead. [0037] As shown in FIG. 7, in place of the oil temperature sensor 38a that detects the lubricating oil temperature Toil, an oil temperature sensor 38b that detects the temperature of the hydraulic fluid (hydraulic fluid temperature) Tfluid at the actuator 32 may be installed to function as the oil temperature detectionmeans. Theoi1temperaturesensor38bmaybeinstailed in, for instance, a pipeline through which the oil returning from the actuator 32 is guided to a reservoir via the control valve 33. Theoiltemperaturesensor38bdetectsthetemperature Tfluid of the oil returning from the actuator 32 and outputs a detection signal to the controller 38. The controller 38, in turn, determines the flow rate Qoil at which oil is to be supplied to the fan motor 21 based upon the hydraulic fluid temperature Tfluid. The relationship between the hydraulic fluid temperature Tfluid and the flow rate Qoil is similar to the relationship between the lubricating oil temperature Toil and the flow rate Qoil stored in the signal generation unit43a(seeFIG.5). Baseduponthehydraulicfluidtemperature Tfluid, the controller 38 calculates the target output flow rate Qp2, the target displacements Dl and D2 and the like in a manner similar to that with which it calculates them based upon the lubricating oil temperature Toil. [0038] In addition, the controller 38 functioning as the pump control means may execute processing other than that described above when calculating the target output flow rate Qp2, which assures the cooling air volume required at the cooling fan 21a, based upon the target flow rate Qoil corresponding to the lubricating oil temper at ure Toil or the determinedhydraulic fluidtemperatureTfluidandthetargetflowrateQwcorresponding to the detected engine cooling water temperature Tw. Furthermore, as long as the target output flow rate Qp2 assuring the cooling air volume required at the cooling fan 21a can be calculated accurately, the calculation may be executed by using either the lubricating oil temperature Toil or the engine coolingwatertemperatureTwalone. Likewise,thetargetoutput flow rate Qp2 may be calculated based upon either the hydraulic f luidtemperatureTf luid or the engine cooling water temperature Tw alone- If the target output flow rate Qp2 is calculated by using at least one of the lubricating oil temperature Toil, the hydraulic fluid temperature Tfluid and the engine cooling water temperature Tw, the control device does not need to include the sensors that are not used for purposes of the calculation among the oil temperature sensors 38a and 38b and the water temperature sensor 37a. [0039] While the pump control device achieved in the embodiment is installed in a hydraulic excavator, the present invention maybeequallyeffeetivelyadoptedinotherconstructionmachines equipped with an actuator-drive hydraulic pump 2 6 and a cooling fan-drive hydraulic pump 27, both driven by an engine 13, as well as in hydraulic work machines other than construction machines. Such a hydraulic work machine may include, for instance, a fork lift. In addition, the hydraulic excavator does not need to be a crawler-type excavator and may be, for instance, a wheel hydraulic excavator. Namely, as long as thefeaturesandfunctionsofthepresentinventionarefulfilied, the present invention is not limited to the pump control device in the embodiment.. It is to be noted that the embodiment described above is simply provided as an example and that the invention should be interpreted without being restricted or limited in any way whatsoever by the correspondence between the description of the embodiment and the description included in the scope of patent claims. The disclosure of the following priority application is herein incorporated by reference: Japanese Patent Application No. 2005-374120 filed December 27, 2005 CLAIMS 1. A pump control apparatus for a hydraulic work machine, comprising: a rot at ion speed set ting device that sets a target rotation speed for an engine; a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine; a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: the pump control device; a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and b) regulates the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulicpump from the engine output torque determined in advance based upon the target rotation speed. 2. A pump control apparatus for a hydraulic work machine according to claim 1 further comprising: at least one of an oil temperature detection device that detects a lubricating oil temperature and a water temperature detectiondevicethatdetectsanenginecoolingwatertemperature, wherein: the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at leastoneofatargetflowratecorrespondingtothelubricating oil temperature detected by the lubricating oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device. 3. A pump control apparatus for a hydraulic work machine according to claim 1, further comprising: at least one of an oil temperature detection device that detects an oil temperature (hereafter referred to as a hydraulic fluid temperature) of oil returning from the work hydraulic actuator and a water temperature detection device that detects an engine cooling water temperature, wherein: the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at least one of a target flow rate corresponding to the hydraulic fluid temperature detected by the oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device. 4 . A pump control apparatus for a hydraulic work machine according to any one of claims 1 through 3, further comprising: a rotation speed detection device that detects an actual rotation speed of the engine; and a correction torque calculation device that calculates a correction torque corresponding to a deviation of the actual rotation speed detected by the rotation speed detection device relative to the target rotation speed set by the rotation speed setting device, wherein: the pump control device corrects the intake torque of the first variable hydraulic pump by using the correction torque calculated by the correction torque calculation device. 5. A pump control apparatus for a hydraulic work machine according to any one of claims 1 through 4, wherein: the pump control device; calculates a fan rotation speed for the cooling fan based upon the target rotation speed and the target output flow rate of the second variable hydraulic pump; calculates an output pressure at the second variable hydraulic pump corresponding to the fan rotation speed based upon predetermined characteristics; and calculates the intake torque of the second variable hydraulic pump in correspondence to the output pressure having been calculated. 6. A pump control apparatus for a hydraulic work machine, comprising: a rotationspeedsettingdevicethat sets atarget rotation speed for an engine; a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine; a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: the pump control device; controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and executes adjustment based upon the intake torque of the second variable hydraulic pump and the target rotation speed so as to stabilize the intake torque of the first variable hydraulic pump irrespective of an actual rotation speed of the engine. 7 . A pump control method adopted in a hydraulic work machine to control a first variable hydraulic pump used to drive a work hydraulic actuator and a second variable hydraulic pump used to drive a cooling fan, both driven by an engine controlled to achieve a target rotation speed, by ensuring that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, comprising: controlling an output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and regulating the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulicpump f romthe engine output torque determined in advance based upon the target rotation speed. 8. A construction machine, comprising: a pump control apparatus according to any one of claims 1 through 6.

Full Text

DESCRIPTION
PUMPCONTROLAPPARATUSFORHYDRAULICWORKMACHINE, PUMP CONTROL METHOD AND CONSTRUCTION MACHINE
TECHNICAL FIELD [0001]
The present invention relates to a pump control apparatus forahydraulicworkmachinethatcontrolsapluralityofhydraulic pumpsdrivenbyanengine,apumpcontrolmethodandaconstruction machine.
BACKGROUND ART [0002]
The pump control apparatuses used in similar applications include the apparatus disclosed in patent reference literature 1. The apparatus disclosed in patent reference literature 1 controls an actuator-drive hydraulic pump and a fan-drive hydraulic pump, both driven by an engine, as described below. Namely, it calculates a required rotation speed for a cooling fan based upon the cooling water temperature or the lubricating oi 1 temperature and controls the output flow rate at the fan-drive hydraulic pump in correspondence to the required rot at ion speed. Then, it calculates the intake torque of the fan-drive hydraulic pump based upon the output flow rate and adjusts the intake torque of the actuator-drive hydraulic pump in correspondence totheextenttowhichtheintaketorqueofthe fan-drivehydraulic
pump is increased/decreased. The excess intake torque that is not used at the fan-drive hydraulic pump is thus allocated to be used as the intake torque at the actuator-drive hydraulic pump. [0003]
Patent reference literature 1: Japanese Laid Open Patent Publication No. 2005-188674 DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0004]
There is an issue to be addressed with regard to the apparatus disclosed in patent reference literature 1 in that since the hydraulicpumpsarecontrolledbasedupon the detect ion value indicating the detected engine rotation speed, the pump control is bound to be destabilized when the engine rotation speed fluctuates.
MEANS FOR SOLVING THE PROBLEMS [0005]
A pump control apparatus for a hydraulic work machine according to a first aspect of the present invention includes: a rotation speed setting device that sets a target rotation speedforanengine;arotationspeedcontroldevicethatcontrols an engine rotation speed so as to adjust the engine rotation
speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by theengine; a second variable hydraulic pump used to drive a cooling fan, drivenbytheengine; andapump control device that controls
an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulicpumpdoesnot exceedanengineoutputtorquedetermined in advance based upon the target rotation speed, wherein: the pump control device; a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and b) regulates the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulic pump from the engine outputtorquedeterminedinadvancebaseduponthetargetrotation speed.
In the pump control apparatus for a hydraulic work ma chine according to the first aspect, it is preferable to further include at least one of an oil temperature detection device thatdetectsalubricatingoiltemperatureandawatertemperature detectiondevicethatdetectsanenginecoolingwatertemperature,
and it is preferable that the pump control device calculates the target output flow rate of the second variable hydraulic
pump based upon at least one of a target flow rate corresponding to the lubricating oil temperature detected by the lubricating oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device.
The pump control apparatus for a hydraulic work machine according to the first aspect may further include at least one of an oil temperature detection device that detects an oil temperature (hereafter referred to as a hydraulic fluid temperature) of oil returning from the work hydraulic actuator and a water temperature detection device that detects an engine cooling water temperature, wherein: the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at least one of a target flow rate corresponding to the hydraulic fluid temperature detected by the oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device.
In the pump control apparatus for a hydraulic work machine according to the first aspect, it is preferable to further include: a rotation speed detection device that detects an actual rotation speed of the engine; and a correction torque calculation device that calculates a correction torque correspondingtoadeviationoftheactualrotationspeeddetected by the rotation speed detection device relative to the target
rotation speed set by the rotation speed setting device, and it is preferable that the pump control device corrects the intake torque of the first variable hydraulic pump by using the correction torque calculated by the correction torque calculation device.
The pump control device may c) calculate a fan rotation speed for the cooling fan based upon the target rotation speed and the target output flow rate of the second variable hydraulic pump; d) calculate an output pressure at the second variable hydraulic pump corresponding to the fan rotation speed based uponpredeterminedcharacteristics; ande) calculatetheintake torque of the second variable hydraulic pump in correspondence to the output pressure having been calculated.
A pump control apparatus for a hydraulic work machine according to a third aspect includes: a rotation speed setting device that sets a target rotation speed for an engine; a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed; a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine; a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump
and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: the pump control device; a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; andb) executes adjustment based upon the intake torque of the second variable hydraulic pump and the target rotation speed so as to stabilize the intake torque of the first variable hydraulic pump irrespective of an actual rotation speed of the engine.
A pump control method according to a third aspect of the present invention is adopted in a hydraulic work machine to control a first variable hydraulic pump used to drive a work hydraulic actuator and a second variable hydraulic pump used to drive a cooling fan, both driven by an engine controlled to achieve a target rotation speed, by ensuring that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does
not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: an output flow rate of the second variable hydraulic pump is controlled based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and the intake torque of the
first variable hydraulic pump is regulated by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulic pump from the engine output torque determined in advance based upon the target rotation speed.
A construction machine according to a fourth aspect of thepresentinventionincludesapumpcontrolapparatusaccording to the first aspect.
ADVANTAGEOUS EFFECT OF THE INVENTION [0006]
According to the present invention, the intake torque ofthefirstvariablehydraulicpumpfordrivingtheworkhydraulic actuator is controlled based upon the intake torque of the second variable hydraulic pump for driving the cooling fan andthetargetenginerotationspeed, andthus, thef irstvariable hydraulic pump can be controlled with a high level of stability even if the actual rotation speed of the engine fluctuates due to a fluctuation of the load on the work hydraulic actuator.
BRIEF DESCRIPTION OF THE DRAWINGS [0007]
FIG. 1 is a side elevation of a hydraulic excavator which may adopt an embodiment of the present invention;
FIG. 2 schematically illustrates the structures assumed in an engine installed in the hydraulic excavator in FIG. 1 and its peripheral components;
FIG. 3 is a hydraulic circuit diagramshowing the structure of a pump control device achieved in the embodiment of the present invention;
FIG. 4 is a block diagram showing the internal structure
of a controller in FIG. 3;
FIG. 5 is a block diagram showing specific details of the processing executed in the controller;
FIG. 6 presents a diagram of characteristics based upon which speed sensing control may be executed; and
FIG. 7 isahydrauliccircuitdiagramshowingthestructure of the pump control device achieved in a variation of the embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION [0008]
The following is an explanation of an embodiment of a pump control device according to the present invention, given in reference to FIGS,. 1 through 6.
FIG. 1 is a side elevation of a large hydraulic excavator 1 that may adopt the embodiment of the present invention. A revolving superstructure 4 is rotatably mounted on a traveling undercarriage 3 equipped with crawler tracks 2. Mounted on the revolving superstructure 4, are an operator's cab 5 and a front work unit 6 capable of articulating up/down freely. The front work unit 6 is constituted with a boom 7, an arm 8 and a bucket 9 which are respectively engaged in operation
via a boom cylinder 10, an arm cylinder 11 and a bucket cylinder
12.
[0009]
FIG. 2 schematically illustrates the structures assumed in an engine 13 installed in the hydraulic excavator 1 and its peripheral components. Air is taken into the engine 13 via an intake manifold 14, a mixed gas constituted with the air and fuel is combusted in cylinders 15 and the exhaust gas is discharged via an exhaust manifold 16. The exhaust gas drives a turbine 17,. and the air taken in through the intake manifold 14 is cooled at an intercooler 18. Cooling water used to cool the engine 13 is cooled at a radiator 20 as it circulates through the radiator 20 via a cooling water pipe
19 . Cooling air is delivered to the intercooler 18, the radiator
20 and an oil cooler 22 as a cooling fan 21a is driven.
[0010]
A pair of variable-displacement hydraulic pumps 26 and 27 and a fixed-displacement hydraulic pump 28 are connected via a transmission 25 to an output shaft 23 of the engine 13. The rotation of the output shaft 23 at the engine 13 is detected by a rotation speed sensor 24. [0011]
The hydraulic pump 26 is an actuator pump through which drive pressure oil is supplied to a plurality of hydraulic actuators (the boom cylinder 10, the arm cylinder 11, thebucket
cylinder 12, a travelinghydraulicmotor, a revolving hydraulic motor and the like) . The hydraulic pump 2] is a fan pump through which drive pressure oil is supplied to a hydraulic motor 21 (fan motor) through a hydraulic piping 29. The rotation of the cooling fan 21a is controlled via the fan motor 21, which is driven in correspondence to the quantity of pressure oil supplied thereto. It is to be noted that while an explanation is given by assuming, for purposes of simplification, that the hydraulic excavator includes a single actuator pump 26 and a single fan pump 27, the excavator may include a plurality of actuator pumps and fan pumps. The hydraulic pump 28 is a mission pump through which mission oil 30 stored in a mission casing 31 is supplied to the oil cooler 22. [0012]
FIG. 3 is a hydraulic circuit diagram showing the structure adopted in the pump control device in the embodiment. It is to be noted that, for purposes of simplification, FIG. 3 shows a single actuator (hydraulic cylinder 32) representing the plurality of hydraulic actuators including the boom cylinder 10, the arm cylinder 11, the bucket cylinder 12, the driving hydraulic motor and the revolving hydraulic motor. [0013]
Pressure oil is supplied to the actuator 32 from the actuator pump 26, with the flow of the pressure oil to the actuator 32 controlled through a control valve 33 . The control
valve 33 is switched with a pilot pressure from a pilot pump, the level of which corresponds to an operation of an operation
lever 34a. An output pressure Pt with which the pressure oil is output from the actuator pump 26 is detected by a pressure sensor 26a, whereas pilot pressures Pia and Pib generated in response to the operation of the operation lever 34a are detected by pressure sensors 34b and 34c. [0014]
The displacement (may also be referred to as the swash plate angle or the displacement angle) of the actuator pump 26 is controlled by a regulator 35, whereas the displacement (mayalsobereferredtoastheswashplateangleorthedisplacement angle) of the fan pump 27 is controlled by a regulator 36. Pilot pressures imparted from a pilot pump 48 in correspondence to the extents to which electromagnetic proportional pressure-reducing valves 4 5 and 4 6 are driven are respectively applied to the regulators 35 and 36. The electromagnetic proportional pressure-reducing valves 45 and 46 are controlled as detailed later based upon control signals provided by a controller 38. [0015]
Thepressuresensors26a, 34band34candanoiltemperature sensor 38a that detects the temperature Toil of the lubricating oil at the oil cooler 22 (see FIG. 2) are connected to the controller 38 and an engine control device 39 is also connected
to the controller 38 via a network 40. A water temperature sensor 37a that detects the temperature Tw of the cooling water at the radiator 20 (see FIG- 2) and a rotation speed setting unit 39a that sets a target rotation speed Nr for the engine 13 (more specifically for the output shaft 23) are connected to the engine control device 39. As a dial, for instance, is operated, the target rotation speed Nr is set at the rotation speed setting unit 39a. It is to be noted that the target rotation speed Nr may instead be set by operating a lever, an accelerator pedal or the like. The engine control device 39 outputs a control signal to a pulse motor used to drive a governor lever (not shown) and controls the actual rotation speed of the engine 13 (i.e., the rotation speed detected by the rotation speed sensor 24) so as to adjust it to the target rotation speed Nr. [0016]
FIG. 4 is a block diagram showing the internal structure ofthecontroller38. Thecontroller38 includesanA/Dconverter 41thatexecutesA/Dconversionofthedetectionsignalsprovided from the pressure sensors 2 6a, 3 4b and 34 c and the oil temperature sensor 38a, a ROM 42 in which a control program and various constants are stored, a RAM 42a, a CPU 43 that executes specific arithmetic processing based upon a control program stored in the ROM 42, a network interface circuit 4 4 that exchanges signals via the network 40 and an output circuit 47 that amplifies
a drive signal generated at the CPU 43 and outputs the amplified signal to the solenoids at the electromagnetic proportional pressure-reducing valves 45 and 46 to be used as a pulse width modulation output signal. [0017]
FIG. 5 is ablockdiagramshowingdetails of theprocessing executed in the controller 38 (in the CPU 43 in particular) . The lubricating oil temperature Toil detected by the oil temperature sensor 38a is input to a signal generation unit 43a. Characteristics whereby the flow rate Qoil at which oil is delivered to the fan motor 21 increases as the lubricating
oil temperature Toil becomes higher, as shown in the figure, i.e., characteristics whereby the rotation speed of the cooling fan 21a increases as the lubricating oil temperature rises, are stored in advance at the signal generation unit 43a. The signal generation unit 4 3a calculates the flow rate Qoil corresponding to the lubricating oil temperature Toil based upon the characteristics. [0018]
The cooling water temperature Tw detected by the water temperature sensor 37a is input to a signal generation unit 43b via the network 40. Characteristics whereby the flow rate Qw at which oil is delivered to the fan motor 21 increases as the cooling water temperature Tw becomes higher, as shown inthefigure, i.e., characteristics whereby the rotation speed
of the cooling fan 2 la increases as the cooling water temperature rises, are stored in advance at the signal generation unit 43b. The signal generation unit 43b calculates the flow rate Qw corresponding to the cooling water temperature Tw based upon the characteristics. A MAX selection unit 43c selects either of the flow rates Qoil and Qw output from the signal generation units 4 3a and 4 3b, whichever is indicating the greater value, and outputs the selected flow rate as a target flow rate Qp2. [0019]
A displacement calculation unit 43d divides the target flow rate Qp2 output from the MAX selection unit 43c by the target rotation speed Nr set at the rotation speed setting unit 39a. It then selects either the quotient (Qp2/Nr) or a maximum value Dp2max of the displacement of the fan pump 27, whicheverindicatesthesmallervalueandoutputstheselected value as a target displacement D2. A relationship between the target displacement D2 and a control current 12 such as that shown in the figure is stored in advance at a signal generation unit 43q, which calculates the control current 12 corresponding to the target displacement D2 based upon the relationship and outputs the control current 12 thus determined to the output circuit 47. As a result, the displacement of the fan pump 27 is controlled to match the target displacement D2. [0020]
A rotation speed calculation unit 4 3e executes a specific arithmetic operation (D2 x Nr x r|v/Dm) by using the target rotation speed Nr set at the rotation speed setting unit 39a and the target displacement D2 calculated by the displacement calculation unit 43d and thus determines a rotation speed Nf for the cooling fan 21a - r|v represents the product of the volumetric efficiency of the fan pump 27 and the volumetric efficiency of the fan motor 21, whereas Dm represents the displacement of the fan motor 27. [0021]
Based upon the characteristics shown in the figure, stored therein in advance, an output pressure calculation unit 43f converts the rotation speed Nf calculated at the rotation speed calculation unit 43e to an output pressure Pfp of the fan pump 27. The characteristics stored in the output pressure calculation unit 4 3f are determined through testing, simulation or the like conducted in advance. In other words, the characteristics can be set at the output pressure calculation unit 43f based upon the relationship between the pump output pressure Pfp and the fan rotation speed Nf, the drive flow rate at the fan motor 21 or the output flow rate at the pump 27 determined by varying the output flow rate of the fan pump 27. [0022]
A torque calculation unit 4 3g executes a specific
arithmetic operation (D2 x Pfp/2n) to calculate a torque by usingthepumpoutputpressurePfpoutputfromtheoutputpressure calculation unit 43f and the target displacement D2 for the fan pump 27 output from the displacement calculation unit 43d. It then selects either the calculated value or a maximum intake torque Tp2max of the pump 27 controlled by the regulator 36, whichever indicates the smaller value and outputs the selected value as an intake torque Tp2 of the fan pump 27. Thus, the intake torque Tp2 of the fan pump 27 can be determined without having to detect the output pressure Pfp via a pressure sensor or the like. [0023]
Characteristics of a reference torque Ta corresponding to the target rotation speed Nr of the engine 13 such as those shown in the figure are stored in advance at a reference torque calculation unit 4 3h. These characteristics are set based upon the output characteristics of the engine 13, along the full load performance curve of the engine 13 without deviating from full load performance curve. Based upon the characteristics, the reference torque calculation unit 43h calculates the reference torque Ta corresponding to the target rotation speed Nr set at the rotation speed setting unit 39a. A subtraction unit 43i subtracts the pump intake torque Tp2 output from the torque calculation unit 43g from the reference torque Ta output from the reference torque calculation unit
43h (Ta - Tp2), thereby determining a control value (control torque Tpl) for the intake torque at the actuator pump 26. [0024]
Characteristics of a target displacement Dt of the pump 26, which correspond to the output pressure Pt and the control torque Tpl at the actuator pump 26, such as those shown in the figure, are stored in advance at a displacement calculation unit 43j . The target displacement Dt assuming these characteristics decreases as the output pressure Pt increases and the target displacement Dt increases relative to the output pressure Pt as the control torque Tpl increases. Based upon the characteristics, the displacement calculation unit 43j calculates the target displacement Dt corresponding to the output pressure Pt detected by the pressure sensor 26a and the control torque Tpl output from the subtraction unit 43i. [0025]
AMAXselectionunit 43kselects eitherthepilotpressure Pia detected by the pressure sensor 34b or the pilot pressure Pib detected by the pressure sensor 34c, whichever indicates the greater value and outputs the selected pilot pressure as a representativepressure Pi. Characteristicswherebyatarget displacement Di increases as the pilot pressure Pi increases, as shown in the figure, are stored in advance at a displacement calculation unit 43m, Based upon the characteristics, the displacement calculation unit 43m calculates the target
displacement Di corresponding to the pilot pressure Pi output
from the MAX selection unit 43k.
[0026]
A MIN selection unit 43n selects either the target displacement Dt output from the displacement calculation unit 43j or the target displacement Di output from the displacement calculation unit 43m, whichever indicates the smaller value, and outputs the selected value as a target displacement DI to be used to control the actuator pump 26. A relationship between the target displacement DI and a control current II such as that shown in the figure is stored in advance at a signal generation unit 4 3p, which calculates the control current II corresponding to the target displacement D1 based upon the relationship and outputs the control current I1 thus determined to the output circuit 47. As a result, the displacement of theactuatorpump26iscontrolledtomatchthetargetdisplacement DI and the intake torque at the hydraulic pump 26 is regulated so as not to exceed the control torque Tpl. [0027]
The operations of the pump control device achieved in the embodiment are summarized below.
When the hydraulic excavator is to be engaged in work, the opera tor per forms a dial operation to set the target rotation speed Nr for the engine 13. Accordingly, the engine control device 39 controls the engine rotation speed so as to match
the target rotation speed Nr. As the operator operates the operation lever 34a in this state, the control valve 33 is switched in correspondence to the extent to which the operation lever is operated, and the actuator 32 becomes driven. Subsequently, the cooling water temperature Tw of the cooling
waterusedtocooltheenginel3andthelubricatingoiltemperature Toil change in correspondence to the work load and the like applied to the hydraulic excavator. [0028]
Thecontroller38determinesthrougharithmeticoperation the output flow rates Qoil and Qw for the fan pump 27 in correspondence to the cooling water temperature Tw and the lubricating oil temperature Toil respectively and the flow rate indicating the greater value is selected as the target flow rate Qp2 (43a through 43c) . Then, the target rotation speed Nr is used to calculate the target displacement D2 of the pump 27 corresponding to the target flow rate Qp2 (43d) , the control signal 12 corresponding to the target displacement D2 is output to the solenoid at the electromagnetic proportional pressure-reducing valve 46 and thus, the displacement of the hydraulic pump 27 is controlled so as to match the target displacement Qp2. As a result, the cooling fan 21a rotates at the target speed, thereby disallowing any excessive increase in either the cooling water temperature Tw or the lubricating oil temperature Toil.
[0029]
In addition, the controller 38 calculates the rotation speed Nf of the cooling fan 21a by using the target displacement D2 of the fan pump 27, the target rotation speed Nr of the enginel3andthevolumetricefficiencyri (43e)andalsocalculates the output pressure Pfp of the pump 27 corresponding to the fan rotation speed Nf based upon preset characteristics (4 3f) . It then calculates the intake torque Tp2 of the pump 27 by using the pump output pressure Pfp and the target displacement D2 (43g), subtracts the intake torque Tp2 from the reference torque Ta of the engine 13 and thus, determines the control value Tpl for the intake torque at the actuator pump 2 6 (43i) . Either the displacement Dt of the pump 26 determined based upon the control torque Tpl and the output pressure Pt at the pump 2 6 or the displacement Di of the pump 2 6 corresponding to the extent to which the operation lever 34a is operated, whichever indicates the smaller value, is then set as the target displacement Dl (43j, 43m and 43n) . The control signal II corresponding to the target displacement Dl is output to the solenoidattheelectromagneticproportionalpressure-reducing valve 45 so as to control the displacement of the hydraulic pump 26 to match the target displacement Dl. As a result, the intake torque at the hydraulic pump 26 is controlled so
as to not exceed the control torque Tpl. [0030]
For instance, when the Dt [0031]
The f ol lowing operational effect scan be achieved through the embodiment described above.
(1) Based upon the target rotation speed Nr selected for
the engine 13 through a dial operation, the intake torque Tp2
of the fan pump 27 is calculated and then based upon the intake torque Tp2 and the target rotation speed Nr, the intake torque
at the actuator pump 26 is adjusted. As a result, even when the actual rotation speed of the engine 13 fluctuates, the displacements of the pumps 2 6 and 27 remain unchanged, enabling stable control.
Since the rotation speed Nf of the cooling fan 21a is determined through arithmetic operation executed by using the target rotation speed Nr and the target displacement D2 of the fan pump 27 (43e) , no rotation sensor needs to be installed specifically to detect the fan rotation speed Nf.
The fan rotation speed Nf is calculated by taking into consideration the volumetric efficiencies r| of the fan pump 27 and the fan motor 21 (43e) , which improves the rotation speed calculation accuracy.
Based upon the relationship between the fan rotation speed Nf and the output pressure Pfp of the pump 27 set in advance, the pump output pressure Pfp corresponding to the fan rotation speed Nf is determined (43f). Since this allows the pump output pressure Pfp to be determined without having to use a pressure sensor, the control device can be configured at low cost.
[0032]
It is to be noted that the present invention is not limited to the embodiment described above and allows for numerous variations . For instance, in addition to the control executed in the embodiment, the following speed sensing control may
be executed. FIG.. 6 is a characteristics diagram of characteristics whereby a correction torque AT increases as a deviation AN of the actual rotation speed of the engine 13 relative to the target rotation speed increases, based upon which speed sensing control may be executed. Such characteristics should be stored in advance in the controller 38 . It is to be noted that speed sensing characteristics other than those shown in FIG. 6 may be used. [0033]
The controller 38 executing speed sensing control determines the deviation AN of the actual rotation speed of
the engine 13 detected via the rotation speed sensor 2 4 relative to the target rotation speed Nr and determines the correction torque AT corresponding to the deviation AN based upon the characteristics shown in FIG. 6. It then executes torque correction by adding the correction torque AT to the control torque Tpl determined at the subtraction unit 43i (Tpl + AT) andoutput st he corrected tor que to the displacement calculation unit 43j . Thus, if there is sufficient margin with regard
to the torque at the engine 13, the correction torque AT assumes a positive value to increase the control torque Tpl, whereas in the event of a torque over, the correction torque assumes a negative value resulting in a decrease in the control torque Tpl. Consequently, since the sum of the intake torques at the pumps 26 and 27 is allowed to assume a value close to the
rated torque, efficient utilization of the engine output is
enabled.
[0034]
Since the control torque Tpl, to which the correction torque AT is subsequently added is calculated without using the actual rotation speed of the engine 13, successful execution of speed sensing control is assured. Namely, if the control torque Tpl is calculated by using the actual rotation speed a fluctuation in the engine rotation speed will result in fluctuations in both the control torque Tpl and the correction torque AT and thus, Tpl + AT will fluctuate to a greater extent, destabilizing the operation significantly. If, on the other hand, the control torque Tpl is calculated by using the target rotation speed Nr, a fluctuation in the engine rotation speed will only result in a fluctuation in the correction torque AT and thus, Tpl + AT will fluctuate to a smaller extent, assuring more stable operation. [0035]
It is to be noted that the extent of fluctuation in the
intake torque Tp2 may be lessened by, for instance, restricting the rate at which the target flow rate Qp2 of the fan pump
27 changes. While the target rotation speed Nr for the engine 13 is set via the rotation speed setting unit 39a, any other rotation speed setting means may be used. While the engine control device 39 controls the engine rotation speed so as
to adjust it to the target rotation speed Nr, any other rotation speed control means may be used- In addition, the structures of the actuator pump 2 6 constituting the f irstvariablehydraulic pumpandthefanpump27constitutingthesecondvariablehydraulic pump are not limited to those described above. [0036]
The processing executed in the controller 38 constituting the pump control means is not limited to that described above, as long as the output flow rates of the pumps 26 and 27 are controlled so as to ensure that the sum of the intake torques of the actuator pump 2 6 and the fan pump 27 does not exceed the reference torque Ta which is set in advance based upon the target rotation speed Nr for the engine 13. Namely, the controller 38 constituting the pump control means may execute processing other than that described above as long as it controls the output flow rate of the pump 27 and calculates the intake torque Tp2 of the pump based upon the target rotation speed Nr and the target output f low rate Qp2 of the pump 27 and regulates the intake torque Tpl of the pump 26 by subtracting the intake torque Tp2 from the reference torque Ta. In addition, while the lubricating oil temperature Toil is detected via the oil temperature sensor 38a and the cooling water temperature Tw isdetectedbythewatertemperaturesensor37a,anoiltemperature detectionmeansandawatertemperaturedetectionmeansadopting different structures may be used instead.
[0037]
As shown in FIG. 7, in place of the oil temperature sensor 38a that detects the lubricating oil temperature Toil, an oil temperature sensor 38b that detects the temperature of the hydraulic fluid (hydraulic fluid temperature) Tfluid at the actuator 32 may be installed to function as the oil temperature detectionmeans. Theoi1temperaturesensor38bmaybeinstailed in, for instance, a pipeline through which the oil returning from the actuator 32 is guided to a reservoir via the control valve 33. Theoiltemperaturesensor38bdetectsthetemperature Tfluid of the oil returning from the actuator 32 and outputs a detection signal to the controller 38. The controller 38, in turn, determines the flow rate Qoil at which oil is to be supplied to the fan motor 21 based upon the hydraulic fluid temperature Tfluid. The relationship between the hydraulic fluid temperature Tfluid and the flow rate Qoil is similar to the relationship between the lubricating oil temperature Toil and the flow rate Qoil stored in the signal generation unit43a(seeFIG.5). Baseduponthehydraulicfluidtemperature
Tfluid, the controller 38 calculates the target output flow rate Qp2, the target displacements Dl and D2 and the like in a manner similar to that with which it calculates them based upon the lubricating oil temperature Toil. [0038]
In addition, the controller 38 functioning as the pump
control means may execute processing other than that described above when calculating the target output flow rate Qp2, which assures the cooling air volume required at the cooling fan 21a, based upon the target flow rate Qoil corresponding to the lubricating oil temper at ure Toil or the determinedhydraulic fluidtemperatureTfluidandthetargetflowrateQwcorresponding to the detected engine cooling water temperature Tw. Furthermore, as long as the target output flow rate Qp2 assuring the cooling air volume required at the cooling fan 21a can be calculated accurately, the calculation may be executed by using either the lubricating oil temperature Toil or the engine coolingwatertemperatureTwalone. Likewise,thetargetoutput flow rate Qp2 may be calculated based upon either the hydraulic f luidtemperatureTf luid or the engine cooling water temperature Tw alone- If the target output flow rate Qp2 is calculated by using at least one of the lubricating oil temperature Toil, the hydraulic fluid temperature Tfluid and the engine cooling water temperature Tw, the control device does not need to include the sensors that are not used for purposes of the calculation among the oil temperature sensors 38a and 38b and the water temperature sensor 37a. [0039]
While the pump control device achieved in the embodiment is installed in a hydraulic excavator, the present invention maybeequallyeffeetivelyadoptedinotherconstructionmachines
equipped with an actuator-drive hydraulic pump 2 6 and a cooling fan-drive hydraulic pump 27, both driven by an engine 13, as well as in hydraulic work machines other than construction machines. Such a hydraulic work machine may include, for instance, a fork lift. In addition, the hydraulic excavator does not need to be a crawler-type excavator and may be, for instance, a wheel hydraulic excavator. Namely, as long as thefeaturesandfunctionsofthepresentinventionarefulfilied, the present invention is not limited to the pump control device in the embodiment..
It is to be noted that the embodiment described above is simply provided as an example and that the invention should be interpreted without being restricted or limited in any way whatsoever by the correspondence between the description of the embodiment and the description included in the scope of patent claims.
The disclosure of the following priority application is herein incorporated by reference:
Japanese Patent Application No. 2005-374120 filed December 27, 2005

CLAIMS
1. A pump control apparatus for a hydraulic work machine, comprising:
a rot at ion speed set ting device that sets a target rotation speed for an engine;
a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed;
a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine;
a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and
a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein:
the pump control device;
a) controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and
b) regulates the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulicpump from the engine output torque determined in advance based upon the target rotation speed.
2. A pump control apparatus for a hydraulic work machine
according to claim 1 further comprising:
at least one of an oil temperature detection device that detects a lubricating oil temperature and a water temperature detectiondevicethatdetectsanenginecoolingwatertemperature, wherein:
the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at leastoneofatargetflowratecorrespondingtothelubricating oil temperature detected by the lubricating oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device.
3. A pump control apparatus for a hydraulic work machine
according to claim 1, further comprising:
at least one of an oil temperature detection device that detects an oil temperature (hereafter referred to as a hydraulic fluid temperature) of oil returning from the work hydraulic
actuator and a water temperature detection device that detects an engine cooling water temperature, wherein:
the pump control device calculates the target output flow rate of the second variable hydraulic pump based upon at least one of a target flow rate corresponding to the hydraulic fluid temperature detected by the oil temperature detection device and a target flow rate corresponding to the engine cooling water temperature detected by the water temperature detection device.
4 . A pump control apparatus for a hydraulic work machine according to any one of claims 1 through 3, further comprising:
a rotation speed detection device that detects an actual rotation speed of the engine; and
a correction torque calculation device that calculates a correction torque corresponding to a deviation of the actual rotation speed detected by the rotation speed detection device relative to the target rotation speed set by the rotation speed setting device, wherein:
the pump control device corrects the intake torque of the first variable hydraulic pump by using the correction torque calculated by the correction torque calculation device.
5. A pump control apparatus for a hydraulic work machine according to any one of claims 1 through 4, wherein:
the pump control device;
calculates a fan rotation speed for the cooling fan based upon the target rotation speed and the target output flow rate of the second variable hydraulic pump;
calculates an output pressure at the second variable hydraulic pump corresponding to the fan rotation speed based upon predetermined characteristics; and
calculates the intake torque of the second variable hydraulic pump in correspondence to the output pressure having been calculated.
6. A pump control apparatus for a hydraulic work machine, comprising:
a rotationspeedsettingdevicethat sets atarget rotation speed for an engine;
a rotation speed control device that controls an engine rotation speed so as to adjust the engine rotation speed to the target rotation speed;
a first variable hydraulic pump used to drive a work hydraulic actuator, driven by the engine;
a second variable hydraulic pump used to drive a cooling fan, driven by the engine; and
a pump control device that controls an output flow rate of the first variable hydraulic pump and an output flow rate of the second variable hydraulic pump so as to ensure that
a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, wherein: the pump control device;
controls the output flow rate of the second variable hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and
executes adjustment based upon the intake torque of the second variable hydraulic pump and the target rotation speed so as to stabilize the intake torque of the first variable hydraulic pump irrespective of an actual rotation speed of the engine.
7 . A pump control method adopted in a hydraulic work machine to control a first variable hydraulic pump used to drive a work hydraulic actuator and a second variable hydraulic pump used to drive a cooling fan, both driven by an engine controlled to achieve a target rotation speed, by ensuring that a sum of an intake torque of the first variable hydraulic pump and an intake torque of the second variable hydraulic pump does not exceed an engine output torque determined in advance based upon the target rotation speed, comprising:
controlling an output flow rate of the second variable
hydraulic pump based upon the target rotation speed and a target output flow rate of the second variable hydraulic pump assuring a required cooling air volume at the cooling fan; and
regulating the intake torque of the first variable hydraulic pump by calculating the intake torque of the second variable hydraulic pump and subtracting the intake torque of the second variable hydraulicpump f romthe engine output torque determined in advance based upon the target rotation speed.
8. A construction machine, comprising:
a pump control apparatus according to any one of claims 1 through 6.

Documents:

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Patent Number

278413

Indian Patent Application Number

5470/DELNP/2008

PG Journal Number

53/2016

Publication Date

23-Dec-2016

Grant Date

22-Dec-2016

Date of Filing

24-Jun-2008

Name of Patentee

HITACHI CONSTRUCTIONS MACHINERY CO., LTD

Applicant Address

5-1, KOURAKU 2-CHOME, BUNKYOU-KU, TOKYO, 1120004, JAPAN

Inventors:

#	Inventor's Name	Inventor's Address
1	YASUDA GEN	HITACHI CONSTRUCTION MACHINERY CO.,LTD., TSUCHIURA WORKS INTELLECTUAL PROPERTY DEPT.650,KANDATSU-MACHI, TSUCHIURA-SHI, IBARAKI, 3000013, JAPAN
2	YAMAZAKI AKIHIDE	HITACHI CONSTRUCTION MACHINERY CO.,LTD., TSUCHIURA WORKS INTELLECTUAL PROPERTY DEPT.650,KANDATSU-MACHI, TSUCHIURA-SHI, IBARAKI, 3000013, JAPAN

PCT International Classification Number

F15B 11/17

PCT International Application Number

PCT/JP2006/325190

PCT International Filing date

2006-12-18

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2005-374120	2005-12-27	Japan