Indian Patents. 271898:FUEL-INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

Title of Invention	FUEL-INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE
Abstract	The invention relates to a high-pressure fuel pump (1) comprising a drive shaft. According to the invention, fuel flows through the bearings (39) and (41) of the drive shaft (35) in a forced manner in such a way that the mechanical and thermal load-carrying capacity of the bearings, and thus the entire high-pressure fuel pump (1), is significantly increased.

Full Text	FUEL-INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE PRIOR ART The invention emanates from a fuel high-pressure pump for a fuel-injection system of an internal combustion engine, with a pump casing in which a drive shaft is supported by a first bearing and a second bearing, with at least one pump element located in a radial manner with reference to the drive shaft, with a fuel inlet, whereby a pusher pump discharges fuel into the fuel inlet, with a fuel reflux, with a measuring device with which to regulate the discharge flow of the pump element/s and with a pressure control valve. In the case of these fuel high-pressure pumps established in prior art, the pressure control valve serves to regulate pressure in the low-pressure circuit. Pusher pump discharge flow is, thus, usually divided into three split streams. A first split stream flows through the measuring device towards the intake side of the pump element/s. The second split stream usually flows via a lubricating throttle through the pump casing and serves to cool and lubricate the pump there. This second split stream reaches the fuel reflux of the fuel injection system from the pump casing. A third split stream flows through the pressure control valve, which can also be designed as an overflow valve and also reaches the fuel reflux. The mechanical and thermal loads of the drive shaft as well as of the bearings I of the drive shaft in the pump casing increase along with the increasing injection pressures. Conventional fuel injection pumps are not able to cope with these increasing loads. To provide a fuel high-pressure pump for a fuel injection system that uses the same installation space as the conventional fuel high-pressure pumps and is, yet, superior to the fuel high-pressure pumps established in prior art with regard to thermal and mechanical load capacity, forms the basis of this invention. The fuel injection high-pressure pump in accordance with the invention should, in addition, be easy to assemble and cost-effective to manufacture. This objective is met in the case of a fuel high-pressure pump for a fuel injection system of an internal combustion engine, with a pump casing, with a drive shaft, whereby the drive shaft is supported in the pump casing by a first bearing and a second bearing, with at least one pump element that is located in a radial manner with regard to the drive shaft, whereby a pusher pump discharges fuel into the fuel inlet, with a fuel reflux, with a measuring device with which to regulate the discharge flow of the pump element/s and with a pressure control valve, in such a manner that the pressure control valve is located in the fuel reflux. ADVANTAGES OF THE INVENTION Locating the pressure control valve in the fuel reflux, in accordance with the invention, achieves, among other things, the flow of the bulk of the fuel discharged by the pusher pump through the pump casing, thus contributing to improved cooling of the pump casing and of the drive shaft. Moreover, pressure in the pump casing is raised when compared to the conventional construction, which reduces the cavitation tendency in the interior of the pump casing. Formation of vapour bubbles and localised overheating (so-called hot spots) are effectively eliminated. A lubricating throttle between the pusher pump and the pump casing can be done away with in the case of the fuel high-pressure pump, in accordance with the invention, so that the latter can be constructed in a simpler manner when compared to the conventional fuel high-pressure pumps despite the advantages mentioned. An advantageous design of the invention provides for the first bearing being lubricated by pressurised fuel and that the first bearing be connected to the fuel inlet as well as to the fuel reflux. This means that approximately the same pressure prevails on one side of the first bearing as on the pressure side of the pusher pump while the other side of the first bearing is in a state of pressure equilibrium with the almost depressurised fuel reflux. The first bearing is, thus, mandatorily streamed by fuel, consequently, ensuring sufficient lubrication and cooling of the first bearing at all operating points. A first flow-restricting device connected in series to the first bearing, is provided in another advantageous design of the invention. The first flow-restricting device serves to keep the fuel stream that flows through the first bearing, within pre-determined limits. In the case of series production of fuel high-pressure pumps, it could come to pass that due to manufacturing tolerances and to wear and tear of the first bearing, the thickness of the lubricating gap and, therewith, the fuel flow through the bearing and its bearing capacity are spread across very wide limits. This means that the bearing capacity of the first bearing and its cooling and lubrication by the fuel stream is not sufficient at all operating points in the case of an unfavourable tolerance position. If the first flow-restricting device, in accordance with the invention, is now connected in series to the first bearing, the fuel stream can be set by the first bearing due to the very marginal manufacturing tolerance with which the first flow-restricting device can be manufactured. The above mentioned manufacturing tolerances, consequently, have only a small-scale impact upon the bearing capacity, so that the loading capacity of the first bearing is ensured even in the case of unfavourable tolerance positions at all operating points of the fuel high-pressure pump. The flow-restricting device restricts the fuel flowing through the bearing. Demands on the pusher pump are, thereby, reduced in unfavourable tolerance positions of the bearing. The initially mentioned objective is met in the case of a fuel high-pressure pump for a fuel injection system of an internal combustion engine, with a pump casing, with a drive shaft, whereby the drive shaft is supported in the pump casing by a first bearing and a second bearing, with at least one pump element that is located in a radial manner with regard to the drive shaft, with a fuel inlet, whereby a pusher pump discharges fuel into the fuel inlet, with a fuel reflux, with a measuring device with which to regulate the discharge flow of the pump element/s, and with a pressure control valve located in the inlet in such a manner that the first bearing is lubricated by pressurised fuel and that the first bearing is hydraulically connected to the fuel inlet as well as to the fuel reflux, that a first flow-restricting device is provided, that the first flow restrictor is connected in series to the first bearing and that a bypass throttle is located between the pump casing and the fuel reflux. An appropriate calibration of the flow-restricting device and of the bypass throttle in this embodiment of a fuel high-pressure pump, in accordance with the invention, ensures, in a simple and effective manner, that a sufficient fuel quantity flows through the first bearing, consequently guaranteeing its cooling and lubrication at all operating points. In the case of fuel high-pressure pumps, in accordance with the invention, the measuring device can alternatively be located between the pusher pump and the fuel high-pressure pump in the fuel inlet or between the pressure regulating valve and the fuel high-pressure pump in the fuel reflux. Both configurations have specific advantages that are to be weighed against each other in individual cases. In favour of the configuration in which the measuring device is located between the pusher pump and the fuel high-pressure pump in the fuel inlet is that fuel flowing in the high-pressure region of the fuel high-pressure pump in this configuration does not flow beforehand through the pump casing so that chips possibly present there, or other particles, cannot reach the fuel high-pressure region. The advantage of the configuration in which the measuring device is located in the fuel reflux is that the entire fuel quantity discharged by the pusher pump is available at each operating point for cooling and lubricating the pump casing and/or the drive shaft of the fuel high-pressure pump as well as the associated bearing. The bearing capacity of the low-pressure region of the fuel high-pressure pump, in accordance with the invention, is thus increased further. It is, alternatively possible to locate the first flow-restricting device before or after the first bearing in the direction of the flov\/. Which configuration is to be given precedence in an individual case depends upon the situations and basic conditions of the individual case. In a further extension of fuel high-pressure pumps, in accordance with the invention, it can also be provided that the second bearing be lubricated by pressurised fuel and that the second bearing be connected hydraulically to the fuel inlet as well as to the fuel reflux. A second flow-restricting device which is located in the direction of the flow before or after the second bearing can, furthermore, be provided. The advantage of mandatory lubrication of the second bearing and of the second flow-restricting device essentially correspond to the previously mentioned advantages that have been mentioned in connection with the first bearing and the first flow-restricting device. The first flow-restricting device and/or the second flow-restricting device can be designed as a throttle, trigger wheel vane or as a current regulating valve. Which of these alternatives has the advantage in an individual case depends upon the tolerance zones of the various components, the loads and, naturally, economic reasons, and is to be decided individually in each case. An especially beneficial configuration of the invention provides for the second bearing being supplied with pressurised fuel by a leakage pipe of the pusher pump. This is particularly advantageous if the pusher pump is designed e.g.as a vane pump, external gear pump or internal gear pump. In the case of vane pumps or gear pumps, leakage, which must be conducted away by a leakage pipe, occurs at the intersection point towards the drive shaft in the gap between the wheel and the gear wheel respectively and the casing. If the leakage pipe is now employed for lubricating and cooling the se€x>nd bearing, the lubrication and cooling of the second bearing can, firstly, be ensured under all operating conditions and, secondly, the leakage quantity of the pusher pump can be reduced due to counter pressure. This results in improved hydraulic efficiency of the pusher pump. It is of particular advantage if the first bearing and/or the second bearing are/is designed as a slide bearing. A stable hydrostatic lubricating film, which ensures a very high loading capacity of the bearing at the most varied speed ranges, can then be designed by supplying the bearing with pressurised fuel, in accordance with the invention. The fuel connector advantageously ends in the interior of the pump casing, whereby the drive shaft is located in the interior of the pump casing. The advantages, in accordance with the invention, are achieved in the case of a fuel injection system for an internal combustion engine with a pusher pump, with a tank, with a fuel high-pressure pump, with a common-rail and with at least one injector, if the fuel high-pressure pump is a fuel high-pressure pump in accordance with one of the preceding claims. The pusher pump can, alternatively, be driven by the internal combustion engine or by an electromotor. other advantages and beneficial configurations of the invention can be gathered from the following drawings, their descriptions and from the patent claims. All features disclosed in the drawings, their descriptions and in the patent claims can be used individually as well as in any combination, in accordance with the invention. DRAWING Figures 1 to 7 present exemplary embodiments of the fuel high-pressure pump, in accordance with the invention, and their integration in a fuel injection system. DESCRIPTION OF THE EXEMPLARY EMBODIMENTS Figure 1 presents a first exemplary embodiment of a fuel high-pressure pump 1, in accordance with the invention, in a block diagram presentation. The fuel high-pressure pump 1 is a part of a fuel injection system that essentially consists of a tank 3, of a pusher pump 5, of a filter 7, of a rail 9 and a pressure-limiting valve 11. Injectors that are connected to the rail 9 are not illustrated in Figure 1. The pressure-limiting valve 11 ends in a return pipe 13 through which the leakage quantities of the injectors that are not illustrated can also be conducted. The return pipe 13 in this first exemplary embodiment ends in tank 3 and drives the jet pump (without reference sign) there. A temperature sensor T is located in the interior of the fuel high-pressure pump 1, which is hydraulically connected to the tank 3 via a fuel inlet 15, the filter 7 and the pusher pump 5. A first branch pipe 17 in which a measuring device 19 is located, branches off from the fuel inlet 15 within the fuel high-pressure pump 1. The measuring device 19 serves to control fuel quantities drawn by pump elements 21 of the fuel high-pressure pump and, therewith, their discharge flows. The intake sides of the pump elements 21 are hydraulically connected by a distribution pipeline to the exit of the measuring device 19 for this purpose. The pump elements 21 essentially consist of suction valves 25, high-pressure sided check valves 27 and a piston 29 that oscillates in a cylindrical bore (without reference sign). Pistons 29 of the pump elements 21 are driven via a roller plunger 31 by tappets 33 of a drive shaft 35. Pump elements 21 convey pressurised fuel via a high-pressure pipe 27 to the rail 9. Tappets 33 are a part of a drive shaft 35 that pivots at both sides of the tappets 33 at a first bearing and at a second bearing in a pump casing (not illustrated). The drive shaft 35 is located in the interior 39 of the pump casing. The bearings of the drive shaft 35 are illustrated as a constriction in the block diagram according to Figure 1. The first bearing has reference sign 39 in Figure 1 while the second bearing has been furnished with reference sign 41. A fuel reflux 43 establishes a hydraulic connection between the interior 38 of the pump casing and the return pipe 13. A pressure control valve 45 is located in the fuel reflux 43. Different types of throttles (not illustrated) can be integrated with the pressure control valve 45. The pressure control valve 45 is located downstream fronn the interior 38 of the fuel high-pressure pump 1 in the first exemplary embodiment of a fuel high-pressure pump, in accordance with the invention, presented In Figure 1. This means that almost the same pressure prevails at the pressure side of the pusher pump 5 as in the interior 38. As a rule, the pressure at the pressure side of the pusher pump 5 and, therewith, the interior 38, is in the range of approximately 3 bar to approximately 6 bar. This pressure prevailing in the interior 38 results in a reduction of the cavitation tendency and, therewith, to suppression of vapour bubbles, especially at high speeds. Apart from this, the increased interior pressure in the interior 38 of the pump casing results in fuel being compressed by the first bearing 39 and the second bearing 41. As a result, a defined fuel quantity is compressed by bearings 39 and 41, subject to the pressure prevailing in the interior 38, fuel viscosity and the flow resistance of the first bearing 39 and of the second bearing 41. This produces a significant increase in the loading capacity of the first bearing 39 as well as of the second bearing 41. Since the first bearing 39 and the second bearing 41 are usually designed as slide bearings, a hydrostatic lubricating cotter pin is formed in bearings 39 and/or 41 as a result of the mandatory flow of fuel through the bearings 39 and 41. The loading capacity of the first bearing 39 and of the second bearing 41, thus, increases considerably and the heat dissipation from the first bearing 39 and from the second bearing 42 is improved simultaneously. In order to reduce the dispersion of fuel quantities that flow through the first bearing 39 and, therewith, also the dispersion of the loading capacity of the first bearing, a first optional flow-restricting device 47 is located in line with the first bearing 39. This first flow-restricting device can, as indicated in Figure 1, be designed as a throttle. It can, alternatively, also be designed as a trigger wheel vane or as a current control valve. It has emerged from several experiments that fuel quantities that flow through the first bearing 39, can be dispersed considerably within a series of fuel high-pressure pumps 1 due to the manufacturing tolerances at, for example, the diameter of the bearing pins (not illustrated) of the drive shaft 35 for the first bearing 39 and for the associated bearing shell (not illustrated) in the pump casing in the case of unfavourable tolerance positions. This undesired effect is, if necessary, reduced by the first flow-restricting device 47, in accordance with the invention, to an uncritical quantity. Series connection of the first bearing 39 and of the first flow-restricting device can ensure that the fuel quantity flowing through the first bearing 39 is kept within a relatively small range. This is, above all, attributed to calibrating the flow resistance of the first flow-restricting device 47 with great precision. Due to the specific calibration of the flow resistance of the first flow-restricting device 47 and pressure prevailing in the interior 38, fuel quantities that flow through the first bearing 39 at all tolerance positions that occur in the case of series manufacture, can be held within a pre-determined range in the case of the fuel high-pressure pump 1, in accordance with the invention. An appropriate second flow-restricting device (not illustrated) can also be provided for the second bearing 41, if required. A filter is provided in the fuel inlet 15 in Figure 1 that also acts as a damping device 49. Compressional vibrations that could possibly occur in the low- pressure area can be attenuated therewith. The damping device 49 could, alternatively, also be designed as a damper with a gas cushion or be omitted. The fuel high-pressure pump 1, in accordance with the invention, has the following advantages, among others: By locating the pressure control valve 45 in the fuel reflux 43, the pressure level prevailing in the interior 38 of the pump casing is raised, which reduces the danger of cavitation as well as the danger of vapour bubble formation. In addition, the first bearing 39 as well as the second bearing 41, thus, have a mandatory stream of fuel flowing through, which significantly increases their loading capacity with regard to mechanical as well as thermal loads. Possibly occurring variations in the flow rate quantities between various exemplars of series manufactured fuel high-pressure pumps 1, in accordance with the invention, can be reduced by a first flow-restricting device 47 and/or a second flow-restricting device that are serially connected. Fuel quantities streaming through the pump casing and bearings 39 and 41 for lubricating and cooling purposes are greatly increased. A lubricating throttle for setting a defined lubricating quantity can be done away with. Possibly existing particles can be washed away from the interior by the large lubricating quantities. The delivery heights of the pusher pump can often be reduced, which improves efficiency of the injection system. Other exemplary embodiments of the fuel high-pressure pumps, in accordance with the invention, and of the fuel injection systems, in accordance with the invention, are also illustrated in a block diagram presentation in the subsequent figures. At the same time, however, only the essential differences are explained. Same components are furnished with the same reference signs and what has been said with regard to the preceding exemplary embodiments is correspondingly valid. For reasons of clarity, not all components in Figures 2 to 7 are provided with reference signs according to Figure 1 and what has been said in connection with the first exemplary embodiment is referred to with regard to these components. The basic difference between the first exemplary embodiment according to Figure 1 and the second exemplary embodiment according to Figure 2 is that the first branch pipe 17 branches off from the fuel reflux 43 in the second exemplary embodiment. This means that the entire fuel discharged by the pusher pump 5 through the fuel inlet 15 reaches the interior 38 of the fuel high-pressure pump first and only branches off there. An even more improved through-flow and cooling of the fuel high-pressure pump 1 is achieved in this manner. A damping device 49 is provided in the fuel reflux 43, in order to attenuate possibly occurring pressure variations in the low-pressure region. The damping device 49 is located before the pressure control valve 45 and the measuring device 19, when seen in the direction of the flow. The damping device 49 is designed as a filter in Figure 2 with increased flow resistance (not illustrated), if required. The damping device 49 can, alternatively, also be designed as a damper with a gas cushion. The third exemplary embodiment according to Figure 3 by and large corresponds to the second exemplary embodiment according to Figure 2. The essential difference is that the pusher pump 5, unlike the preceding exemplary embodiments, is not driven by an electromotor (not illustrated) but directly by the internal combustion engine. The details of this actuation are not illustrated in Figure 3. A drainage coil 51 is provided in the direction of the stream before the pusher pump 5 viz. between the filter 7 and the pusher pump 5, which restricts the discharge flow of the pusher pump 5, particularly at high speeds. The pusher pump 5 can be designed as a vane pump, as an external gear pump or an internal gear pump, particularly as a Gerotor pump. A gap that causes leakage losses is present between the gyratory components and the pump casing in these pumps. This gap is represented in Figure 3 by a symbol of a throttle (reference sign 53). The leakage quantity that flows through the gap is conducted away by a leakage pipe 55, which supplies the first bearing 39 with fuel in the case of this exemplary embodiment. A shutoff pipe 56, which is outward bound from the pressure control valve 45 and ends upstream from the drainage coil 51 in the fuel inlet 15, is provided in the third exemplary embodiment. The surplus fuel quantities resulting from the pressure regulation are conducted away into the inlet 15 via the shutoff pipe 56. The first bearing 39 is supplied with fuel from the interior 38. A second branch pipe 57, which ends in the fuel reflux 43, is outward bound from the leakage pipe 55. The lubricating quantities of the first bearing 39 are also conducted away through the second branch pipe 57. A bypass throttle 59 can be provided in the second branch pipe 57. Another exemplary embodiment of a fuel high-pressure pump, In accordance with the invention, is illustrated in Figure 4, this embodiment having many things in common with the third exemplary embodiment. A leakage pipe 55 is located at the pusher pump 5 in this embodiment also. The first bearing 39 is also fed with fuel from the interior 38 in the case of this exemplary embodiment. A second branch pipe 57, which ends in the fuel reflux 43, is outward-bound from the leakage pipe 55. Lubricating quantities of the first bearing 39 are also conducted away through the second branch pipe 57. A bypass throttle 59 can be provided in the second branch pipe 57. The measuring device 19 is located in the fuel inlet 15 in this exemplary embodiment, as is also the case in the first exemplary embodiment in accordance with Figure 1. In the case of the exemplary embodiment according to Figure 4, the fuel reflux 43 is not lead back to tank 3 as in the exemplary embodiments 1 and 2 but to the fuel inlet 15 instead in the third exemplary embodiment and, in fact, upstream from the drainage coil 51. The basic difference in the fifth exemplary embodiment according to Figure 5 when compared to the fourth embodiment according to Figure 4 is that the measuring device 19 and the optional damping device 49 are located in the fuel reflux 43 in the fifth exemplary embodiment. Decompression for piston movement of the pressure control valve 45 can, thus, be optionally associated with the fuel inlet 15 or with the fuel reflux 43. Apart from this, the pressure control valve 45 has a separate shutoff pipe 56 which, similar to that in the third exemplary embodiment, ends in the fuel inlet 15 before the drainage coil 51. The fuel reflux 43 is guided back to tank 3 via reflux pipe 13 in this exemplary embodiment. A second bypass throttle 61 is located in a third branch pipe 63, this third branch pipe 63 connecting the interior 38 of the fuel high-pressure pump 1 to the fuel reflux 43. One more pressure-limiting valve 65 is provided in the third branch pipe 63 in line with the second bypass throttle 61. The pressure-limiting valve 65 ensures that the third branch pipe 63 is opened so that surplus fuel can flow out from the interior 38 in the event of a predetermined pressure difference between the pressure in the interior 38 of the fuel high-pressure pump 1 and the fuel reflux 43 being exceeded. In the case of a sixth exemplary embodiment according to Figure 6, the leakage pipe 55 ends in the interior 38 of the pump casing. The first bearing 39 is supplied with pressurised fuel from the interior 38 of the pump casing, which subsequently flows through the first flow-restricting device 47 and then reaches the fuel reflux 63. In this exemplary embodiment too, the fuel measuring device 19 is located at the same side as the fuel reflux 43, resulting in the advantages already mentioned several times; the device can, however, also be located at the same side as the fuel inlet 15. In the case of the exemplary embodiment according to Figure 7, the pusher pump 5 is designed as a fuel pump that is operated by an electromotor and is located in the vicinity of tank 3. Measuring unit 19 is located at the fuel inlet side 15 of the fuel high-pressure pump 1. The pressure control valve 45 is connected to the fuel inlet 15 at the entrance side. The exit side of the pressure control valve 45 ends in the fuel reflux 43. The third branch pipe 63 in which a second bypass throttle is located as well as a damping device 49 such as e.g. a filter, also ends in the fuel reflux 43. Apart from this, fuel that flows through the first bearing 39 and the first flow-restricting device 47 is also conducted away to the fuel reflux 43. The same applies to the second bearing 41 that is provided with a second flow-restricting device 67 in the embodiment according to Figure 7, whose mode of operation corresponds to the first flow-restricting device 47. I CLAIMS 1. Fuel high-pressure pump for a fuel injection system of an internal combustion engine, with a pump casing, with a drive shaft (35), whereby the drive shaft (35) is supported in the pump casing by a first bearing (39) and by a second bearing (41), with at least one pump element (21) located in a radial manner with regard to the drive shaft (35), whereby a pusher pump (5) conveys fuel to the fuel inlet (15), with one fuel reflux (43), with a measuring device (19) with which to control the discharge quantities of the pump element(s) (21) and with a pressure control valve (45), characterised in that, the pressure control valve (45) is located in the fuel reflux (43). (Figures 1 to 6). 2. Fuel high-pressure pump in accordance with Claim 1, characterised in that, the first bearing (39) is lubricated by pressurised fuel and that the first bearing (39) is hydraulically connected to both the fuel inlet (15) as well as to the fuel reflux (43). 3. Fuel high-pressure pump in accordance with Claim 3, characterised in that, a first flow-restricting device (47) is provided and that the first flow-restricting device (47) is serially connected to the first bearing (39). 4. Fuel high-pressure pump for a fuel high-pressure system of an internal combustion engine, with a pump casing, with a drive shaft (35), whereby the drive shaft (35) is supported in the pump casing by a first bearing (39) and by a second bearing (41), with at least one pump element (21) located in a radial manner with regard to the drive shaft (35), whereby a pusher pump (5) conveys fuel to the fuel inlet (14), with a fuel reflux (43) and with a measuring device (19) with which to control the discharge quantities of the pump element(s) (21) and with a pressure control valve (45) located in the fuel inlet (15), characterised in that, the first bearing r I (39) is lubricated by pressurised fuel, that the first bearing (39) is hydraulically connected to the fuel inlet (15) as well as to the fuel reflux (43), that a first flow-restricting device (47) is provided and that the first flow-restricting device (47) is serially connected to the first bearing (39). (Figure 7). 5. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the measuring device (19) is located in the fuel inlet (15) between the pusher pump (5) and the fuel high-pressure pump (1). 6. Fuel high-pressure pump in accordance with one of Claim 1 to 4, characterised in that, the measuring device (19) is located in the fuel reflux (43) between the pressure control valve (45) and the fuel high-pressure pump (1). 7. Fuel high-pressure pump in accordance with one of Claims 3 to 6, characterised in that, the first flow-restricting device (47) is located before or after the first bearing (39) in the direction of the flow. 8. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the second bearing (41) is lubricated by pressurised fuel and that the second bearing is hydraulically connected to the fuel inlet (15) as well as to the fuel reflux (43). 9. Fuel high-pressure pump in accordance with Claim 8, characterised in that, a second flow-restricting device (67) is provided and that the second flow-restricting device (67) is located in flow direction before or after the second bearing (41). 10. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first pressure-limiting device (47) and/or the second pressure-limiting device (67) are/is designed as a throttle or a trigger wheel vane. 11. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first pressure-limiting device (47) and/or the second pressure-limiting device (67) are/is designed as a current control valve. 12. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first bearing (39) is lubricated by pressurised fuel and that the first bearing (39) is supplied with pressurised fuel from a leakage pipe (55) of the pusher pump (5). (Figure 7) 13. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first bearing (39) and/or the second bearing (41) are/is designed as a slide bearing. 14. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the fuel connection (15) ends in the interior (38) of the pump casing. 15. Fuel injection system for an internal combustion engine with a pusher pump (5), with a tank (3), with a fuel high-pressure pump (1), with a common rail (9) and with at least one injector, characterised in that, the fuel high-pressure pump (1) is a fuel high-pressure pump in accordance with one of the preceding Claims. 16. Fuel injection system in accordance with Claim 15, characterised in that, the pusher pump (5) is operated by an internal combustion engine. 17. Fuel injection system in accordance with Claim 15, characterised in that, the pusher pump (5) is operated by an electromotor. 18. Fuel injection system in accordance with one of Claims 15 to 17, characterised in that, the pusher pump (5) is designed as a sliding vane

Full Text

FUEL-INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE
PRIOR ART
The invention emanates from a fuel high-pressure pump for a fuel-injection system of an internal combustion engine, with a pump casing in which a drive shaft is supported by a first bearing and a second bearing, with at least one pump element located in a radial manner with reference to the drive shaft, with a fuel inlet, whereby a pusher pump discharges fuel into the fuel inlet, with a fuel reflux, with a measuring device with which to regulate the discharge flow of the pump element/s and with a pressure control valve.
In the case of these fuel high-pressure pumps established in prior art, the pressure control valve serves to regulate pressure in the low-pressure circuit. Pusher pump discharge flow is, thus, usually divided into three split streams. A first split stream flows through the measuring device towards the intake side of the pump element/s. The second split stream usually flows via a lubricating throttle through the pump casing and serves to cool and lubricate the pump there. This second split stream reaches the fuel reflux of the fuel injection system from the pump casing.
A third split stream flows through the pressure control valve, which can also be designed as an overflow valve and also reaches the fuel reflux.
The mechanical and thermal loads of the drive shaft as well as of the bearings I of the drive shaft in the pump casing increase along with the increasing

injection pressures. Conventional fuel injection pumps are not able to cope with these increasing loads.
To provide a fuel high-pressure pump for a fuel injection system that uses the same installation space as the conventional fuel high-pressure pumps and is, yet, superior to the fuel high-pressure pumps established in prior art with regard to thermal and mechanical load capacity, forms the basis of this invention. The fuel injection high-pressure pump in accordance with the invention should, in addition, be easy to assemble and cost-effective to manufacture.
This objective is met in the case of a fuel high-pressure pump for a fuel injection system of an internal combustion engine, with a pump casing, with a drive shaft, whereby the drive shaft is supported in the pump casing by a first bearing and a second bearing, with at least one pump element that is located in a radial manner with regard to the drive shaft, whereby a pusher pump discharges fuel into the fuel inlet, with a fuel reflux, with a measuring device with which to regulate the discharge flow of the pump element/s and with a pressure control valve, in such a manner that the pressure control valve is located in the fuel reflux.
ADVANTAGES OF THE INVENTION
Locating the pressure control valve in the fuel reflux, in accordance with the invention, achieves, among other things, the flow of the bulk of the fuel discharged by the pusher pump through the pump casing, thus contributing to improved cooling of the pump casing and of the drive shaft. Moreover, pressure in the pump casing is raised when compared to the conventional

construction, which reduces the cavitation tendency in the interior of the pump casing. Formation of vapour bubbles and localised overheating (so-called hot spots) are effectively eliminated.
A lubricating throttle between the pusher pump and the pump casing can be done away with in the case of the fuel high-pressure pump, in accordance with the invention, so that the latter can be constructed in a simpler manner when compared to the conventional fuel high-pressure pumps despite the advantages mentioned.
An advantageous design of the invention provides for the first bearing being lubricated by pressurised fuel and that the first bearing be connected to the fuel inlet as well as to the fuel reflux. This means that approximately the same pressure prevails on one side of the first bearing as on the pressure side of the pusher pump while the other side of the first bearing is in a state of pressure equilibrium with the almost depressurised fuel reflux. The first bearing is, thus, mandatorily streamed by fuel, consequently, ensuring sufficient lubrication and cooling of the first bearing at all operating points.
A first flow-restricting device connected in series to the first bearing, is provided in another advantageous design of the invention.
The first flow-restricting device serves to keep the fuel stream that flows through the first bearing, within pre-determined limits. In the case of series production of fuel high-pressure pumps, it could come to pass that due to manufacturing tolerances and to wear and tear of the first bearing, the thickness of the lubricating gap and, therewith, the fuel flow through the bearing and its bearing capacity are spread across very wide limits. This

means that the bearing capacity of the first bearing and its cooling and lubrication by the fuel stream is not sufficient at all operating points in the case of an unfavourable tolerance position. If the first flow-restricting device, in accordance with the invention, is now connected in series to the first bearing, the fuel stream can be set by the first bearing due to the very marginal manufacturing tolerance with which the first flow-restricting device can be manufactured. The above mentioned manufacturing tolerances, consequently, have only a small-scale impact upon the bearing capacity, so that the loading capacity of the first bearing is ensured even in the case of unfavourable tolerance positions at all operating points of the fuel high-pressure pump.
The flow-restricting device restricts the fuel flowing through the bearing. Demands on the pusher pump are, thereby, reduced in unfavourable tolerance positions of the bearing.
The initially mentioned objective is met in the case of a fuel high-pressure pump for a fuel injection system of an internal combustion engine, with a pump casing, with a drive shaft, whereby the drive shaft is supported in the pump casing by a first bearing and a second bearing, with at least one pump element that is located in a radial manner with regard to the drive shaft, with a fuel inlet, whereby a pusher pump discharges fuel into the fuel inlet, with a fuel reflux, with a measuring device with which to regulate the discharge flow of the pump element/s, and with a pressure control valve located in the inlet in such a manner that the first bearing is lubricated by pressurised fuel and that the first bearing is hydraulically connected to the fuel inlet as well as to the fuel reflux, that a first flow-restricting device is provided, that the first flow restrictor is connected in series to the first bearing and that a bypass throttle is located between the pump casing and the fuel reflux.

An appropriate calibration of the flow-restricting device and of the bypass throttle in this embodiment of a fuel high-pressure pump, in accordance with the invention, ensures, in a simple and effective manner, that a sufficient fuel quantity flows through the first bearing, consequently guaranteeing its cooling and lubrication at all operating points.
In the case of fuel high-pressure pumps, in accordance with the invention, the measuring device can alternatively be located between the pusher pump and the fuel high-pressure pump in the fuel inlet or between the pressure regulating valve and the fuel high-pressure pump in the fuel reflux. Both configurations have specific advantages that are to be weighed against each other in individual cases.
In favour of the configuration in which the measuring device is located between the pusher pump and the fuel high-pressure pump in the fuel inlet is that fuel flowing in the high-pressure region of the fuel high-pressure pump in this configuration does not flow beforehand through the pump casing so that chips possibly present there, or other particles, cannot reach the fuel high-pressure region.
The advantage of the configuration in which the measuring device is located in the fuel reflux is that the entire fuel quantity discharged by the pusher pump is available at each operating point for cooling and lubricating the pump casing and/or the drive shaft of the fuel high-pressure pump as well as the associated bearing. The bearing capacity of the low-pressure region of the fuel high-pressure pump, in accordance with the invention, is thus increased further.

It is, alternatively possible to locate the first flow-restricting device before or after the first bearing in the direction of the flov\/. Which configuration is to be given precedence in an individual case depends upon the situations and basic conditions of the individual case.
In a further extension of fuel high-pressure pumps, in accordance with the invention, it can also be provided that the second bearing be lubricated by pressurised fuel and that the second bearing be connected hydraulically to the fuel inlet as well as to the fuel reflux.
A second flow-restricting device which is located in the direction of the flow before or after the second bearing can, furthermore, be provided. The advantage of mandatory lubrication of the second bearing and of the second flow-restricting device essentially correspond to the previously mentioned advantages that have been mentioned in connection with the first bearing and the first flow-restricting device.
The first flow-restricting device and/or the second flow-restricting device can be designed as a throttle, trigger wheel vane or as a current regulating valve. Which of these alternatives has the advantage in an individual case depends upon the tolerance zones of the various components, the loads and, naturally, economic reasons, and is to be decided individually in each case.
An especially beneficial configuration of the invention provides for the second bearing being supplied with pressurised fuel by a leakage pipe of the pusher pump. This is particularly advantageous if the pusher pump is designed e.g.as a vane pump, external gear pump or internal gear pump. In the case of vane pumps or gear pumps, leakage, which must be conducted away by a leakage

pipe, occurs at the intersection point towards the drive shaft in the gap between the wheel and the gear wheel respectively and the casing. If the leakage pipe is now employed for lubricating and cooling the se€x>nd bearing, the lubrication and cooling of the second bearing can, firstly, be ensured under all operating conditions and, secondly, the leakage quantity of the pusher pump can be reduced due to counter pressure. This results in improved hydraulic efficiency of the pusher pump.
It is of particular advantage if the first bearing and/or the second bearing are/is designed as a slide bearing. A stable hydrostatic lubricating film, which ensures a very high loading capacity of the bearing at the most varied speed ranges, can then be designed by supplying the bearing with pressurised fuel, in accordance with the invention.
The fuel connector advantageously ends in the interior of the pump casing, whereby the drive shaft is located in the interior of the pump casing.
The advantages, in accordance with the invention, are achieved in the case of a fuel injection system for an internal combustion engine with a pusher pump, with a tank, with a fuel high-pressure pump, with a common-rail and with at least one injector, if the fuel high-pressure pump is a fuel high-pressure pump in accordance with one of the preceding claims.
The pusher pump can, alternatively, be driven by the internal combustion engine or by an electromotor.

other advantages and beneficial configurations of the invention can be gathered from the following drawings, their descriptions and from the patent claims. All features disclosed in the drawings, their descriptions and in the patent claims can be used individually as well as in any combination, in accordance with the invention.
DRAWING
Figures 1 to 7 present exemplary embodiments of the fuel high-pressure
pump, in accordance with the invention, and their integration in a fuel injection system.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
Figure 1 presents a first exemplary embodiment of a fuel high-pressure pump 1, in accordance with the invention, in a block diagram presentation.
The fuel high-pressure pump 1 is a part of a fuel injection system that essentially consists of a tank 3, of a pusher pump 5, of a filter 7, of a rail 9 and a pressure-limiting valve 11. Injectors that are connected to the rail 9 are not illustrated in Figure 1. The pressure-limiting valve 11 ends in a return pipe 13 through which the leakage quantities of the injectors that are not illustrated can also be conducted. The return pipe 13 in this first exemplary embodiment ends in tank 3 and drives the jet pump (without reference sign) there.

A temperature sensor T is located in the interior of the fuel high-pressure pump 1, which is hydraulically connected to the tank 3 via a fuel inlet 15, the filter 7 and the pusher pump 5.
A first branch pipe 17 in which a measuring device 19 is located, branches off from the fuel inlet 15 within the fuel high-pressure pump 1. The measuring device 19 serves to control fuel quantities drawn by pump elements 21 of the fuel high-pressure pump and, therewith, their discharge flows. The intake sides of the pump elements 21 are hydraulically connected by a distribution pipeline to the exit of the measuring device 19 for this purpose.
The pump elements 21 essentially consist of suction valves 25, high-pressure sided check valves 27 and a piston 29 that oscillates in a cylindrical bore (without reference sign). Pistons 29 of the pump elements 21 are driven via a roller plunger 31 by tappets 33 of a drive shaft 35. Pump elements 21 convey pressurised fuel via a high-pressure pipe 27 to the rail 9.
Tappets 33 are a part of a drive shaft 35 that pivots at both sides of the tappets 33 at a first bearing and at a second bearing in a pump casing (not illustrated). The drive shaft 35 is located in the interior 39 of the pump casing. The bearings of the drive shaft 35 are illustrated as a constriction in the block diagram according to Figure 1. The first bearing has reference sign 39 in Figure 1 while the second bearing has been furnished with reference sign 41.
A fuel reflux 43 establishes a hydraulic connection between the interior 38 of the pump casing and the return pipe 13. A pressure control valve 45 is located in the fuel reflux 43. Different types of throttles (not illustrated) can be integrated with the pressure control valve 45.

The pressure control valve 45 is located downstream fronn the interior 38 of the fuel high-pressure pump 1 in the first exemplary embodiment of a fuel high-pressure pump, in accordance with the invention, presented In Figure 1. This means that almost the same pressure prevails at the pressure side of the pusher pump 5 as in the interior 38. As a rule, the pressure at the pressure side of the pusher pump 5 and, therewith, the interior 38, is in the range of approximately 3 bar to approximately 6 bar.
This pressure prevailing in the interior 38 results in a reduction of the cavitation tendency and, therewith, to suppression of vapour bubbles, especially at high speeds. Apart from this, the increased interior pressure in the interior 38 of the pump casing results in fuel being compressed by the first bearing 39 and the second bearing 41. As a result, a defined fuel quantity is compressed by bearings 39 and 41, subject to the pressure prevailing in the interior 38, fuel viscosity and the flow resistance of the first bearing 39 and of the second bearing 41. This produces a significant increase in the loading capacity of the first bearing 39 as well as of the second bearing 41.
Since the first bearing 39 and the second bearing 41 are usually designed as slide bearings, a hydrostatic lubricating cotter pin is formed in bearings 39 and/or 41 as a result of the mandatory flow of fuel through the bearings 39 and 41. The loading capacity of the first bearing 39 and of the second bearing 41, thus, increases considerably and the heat dissipation from the first bearing 39 and from the second bearing 42 is improved simultaneously.
In order to reduce the dispersion of fuel quantities that flow through the first bearing 39 and, therewith, also the dispersion of the loading capacity of the first bearing, a first optional flow-restricting device 47 is located in line with the first bearing 39. This first flow-restricting device can, as indicated in Figure 1, be

designed as a throttle. It can, alternatively, also be designed as a trigger wheel vane or as a current control valve.
It has emerged from several experiments that fuel quantities that flow through the first bearing 39, can be dispersed considerably within a series of fuel high-pressure pumps 1 due to the manufacturing tolerances at, for example, the diameter of the bearing pins (not illustrated) of the drive shaft 35 for the first bearing 39 and for the associated bearing shell (not illustrated) in the pump casing in the case of unfavourable tolerance positions. This undesired effect is, if necessary, reduced by the first flow-restricting device 47, in accordance with the invention, to an uncritical quantity.
Series connection of the first bearing 39 and of the first flow-restricting device can ensure that the fuel quantity flowing through the first bearing 39 is kept within a relatively small range. This is, above all, attributed to calibrating the flow resistance of the first flow-restricting device 47 with great precision. Due to the specific calibration of the flow resistance of the first flow-restricting device 47 and pressure prevailing in the interior 38, fuel quantities that flow through the first bearing 39 at all tolerance positions that occur in the case of series manufacture, can be held within a pre-determined range in the case of the fuel high-pressure pump 1, in accordance with the invention.
An appropriate second flow-restricting device (not illustrated) can also be provided for the second bearing 41, if required.
A filter is provided in the fuel inlet 15 in Figure 1 that also acts as a damping device 49. Compressional vibrations that could possibly occur in the low-

pressure area can be attenuated therewith. The damping device 49 could, alternatively, also be designed as a damper with a gas cushion or be omitted.
The fuel high-pressure pump 1, in accordance with the invention, has the following advantages, among others:
By locating the pressure control valve 45 in the fuel reflux 43, the pressure level prevailing in the interior 38 of the pump casing is raised, which reduces the danger of cavitation as well as the danger of vapour bubble formation.
In addition, the first bearing 39 as well as the second bearing 41, thus, have a mandatory stream of fuel flowing through, which significantly increases their loading capacity with regard to mechanical as well as thermal loads.
Possibly occurring variations in the flow rate quantities between various exemplars of series manufactured fuel high-pressure pumps 1, in accordance with the invention, can be reduced by a first flow-restricting device 47 and/or a second flow-restricting device that are serially connected.
Fuel quantities streaming through the pump casing and bearings 39 and 41 for lubricating and cooling purposes are greatly increased.
A lubricating throttle for setting a defined lubricating quantity can be done away with. Possibly existing particles can be washed away from the interior by the large lubricating quantities.

The delivery heights of the pusher pump can often be reduced, which improves efficiency of the injection system.
Other exemplary embodiments of the fuel high-pressure pumps, in accordance with the invention, and of the fuel injection systems, in accordance with the invention, are also illustrated in a block diagram presentation in the subsequent figures. At the same time, however, only the essential differences are explained. Same components are furnished with the same reference signs and what has been said with regard to the preceding exemplary embodiments is correspondingly valid. For reasons of clarity, not all components in Figures 2 to 7 are provided with reference signs according to Figure 1 and what has been said in connection with the first exemplary embodiment is referred to with regard to these components.
The basic difference between the first exemplary embodiment according to Figure 1 and the second exemplary embodiment according to Figure 2 is that the first branch pipe 17 branches off from the fuel reflux 43 in the second exemplary embodiment. This means that the entire fuel discharged by the pusher pump 5 through the fuel inlet 15 reaches the interior 38 of the fuel high-pressure pump first and only branches off there. An even more improved through-flow and cooling of the fuel high-pressure pump 1 is achieved in this manner.
A damping device 49 is provided in the fuel reflux 43, in order to attenuate possibly occurring pressure variations in the low-pressure region. The damping device 49 is located before the pressure control valve 45 and the measuring device 19, when seen in the direction of the flow. The damping device 49 is designed as a filter in Figure 2 with increased flow resistance (not

illustrated), if required. The damping device 49 can, alternatively, also be designed as a damper with a gas cushion.
The third exemplary embodiment according to Figure 3 by and large corresponds to the second exemplary embodiment according to Figure 2. The essential difference is that the pusher pump 5, unlike the preceding exemplary embodiments, is not driven by an electromotor (not illustrated) but directly by the internal combustion engine. The details of this actuation are not illustrated in Figure 3.
A drainage coil 51 is provided in the direction of the stream before the pusher pump 5 viz. between the filter 7 and the pusher pump 5, which restricts the discharge flow of the pusher pump 5, particularly at high speeds.
The pusher pump 5 can be designed as a vane pump, as an external gear pump or an internal gear pump, particularly as a Gerotor pump. A gap that causes leakage losses is present between the gyratory components and the pump casing in these pumps. This gap is represented in Figure 3 by a symbol of a throttle (reference sign 53). The leakage quantity that flows through the gap is conducted away by a leakage pipe 55, which supplies the first bearing 39 with fuel in the case of this exemplary embodiment.
A shutoff pipe 56, which is outward bound from the pressure control valve 45 and ends upstream from the drainage coil 51 in the fuel inlet 15, is provided in the third exemplary embodiment. The surplus fuel quantities resulting from the pressure regulation are conducted away into the inlet 15 via the shutoff pipe 56.

The first bearing 39 is supplied with fuel from the interior 38. A second branch pipe 57, which ends in the fuel reflux 43, is outward bound from the leakage pipe 55. The lubricating quantities of the first bearing 39 are also conducted away through the second branch pipe 57. A bypass throttle 59 can be provided in the second branch pipe 57.
Another exemplary embodiment of a fuel high-pressure pump, In accordance with the invention, is illustrated in Figure 4, this embodiment having many things in common with the third exemplary embodiment. A leakage pipe 55 is located at the pusher pump 5 in this embodiment also.
The first bearing 39 is also fed with fuel from the interior 38 in the case of this exemplary embodiment. A second branch pipe 57, which ends in the fuel reflux 43, is outward-bound from the leakage pipe 55. Lubricating quantities of the first bearing 39 are also conducted away through the second branch pipe 57. A bypass throttle 59 can be provided in the second branch pipe 57. The measuring device 19 is located in the fuel inlet 15 in this exemplary embodiment, as is also the case in the first exemplary embodiment in accordance with Figure 1.
In the case of the exemplary embodiment according to Figure 4, the fuel reflux 43 is not lead back to tank 3 as in the exemplary embodiments 1 and 2 but to the fuel inlet 15 instead in the third exemplary embodiment and, in fact, upstream from the drainage coil 51.
The basic difference in the fifth exemplary embodiment according to Figure 5 when compared to the fourth embodiment according to Figure 4 is that the measuring device 19 and the optional damping device 49 are located in the

fuel reflux 43 in the fifth exemplary embodiment. Decompression for piston movement of the pressure control valve 45 can, thus, be optionally associated with the fuel inlet 15 or with the fuel reflux 43.
Apart from this, the pressure control valve 45 has a separate shutoff pipe 56 which, similar to that in the third exemplary embodiment, ends in the fuel inlet 15 before the drainage coil 51.
The fuel reflux 43 is guided back to tank 3 via reflux pipe 13 in this exemplary embodiment. A second bypass throttle 61 is located in a third branch pipe 63, this third branch pipe 63 connecting the interior 38 of the fuel high-pressure pump 1 to the fuel reflux 43. One more pressure-limiting valve 65 is provided in the third branch pipe 63 in line with the second bypass throttle 61. The pressure-limiting valve 65 ensures that the third branch pipe 63 is opened so that surplus fuel can flow out from the interior 38 in the event of a predetermined pressure difference between the pressure in the interior 38 of the fuel high-pressure pump 1 and the fuel reflux 43 being exceeded.
In the case of a sixth exemplary embodiment according to Figure 6, the leakage pipe 55 ends in the interior 38 of the pump casing. The first bearing 39 is supplied with pressurised fuel from the interior 38 of the pump casing, which subsequently flows through the first flow-restricting device 47 and then reaches the fuel reflux 63. In this exemplary embodiment too, the fuel measuring device 19 is located at the same side as the fuel reflux 43, resulting in the advantages already mentioned several times; the device can, however, also be located at the same side as the fuel inlet 15.

In the case of the exemplary embodiment according to Figure 7, the pusher pump 5 is designed as a fuel pump that is operated by an electromotor and is located in the vicinity of tank 3. Measuring unit 19 is located at the fuel inlet side 15 of the fuel high-pressure pump 1. The pressure control valve 45 is connected to the fuel inlet 15 at the entrance side. The exit side of the pressure control valve 45 ends in the fuel reflux 43. The third branch pipe 63 in which a second bypass throttle is located as well as a damping device 49 such as e.g. a filter, also ends in the fuel reflux 43. Apart from this, fuel that flows through the first bearing 39 and the first flow-restricting device 47 is also conducted away to the fuel reflux 43. The same applies to the second bearing 41 that is provided with a second flow-restricting device 67 in the embodiment according to Figure 7, whose mode of operation corresponds to the first flow-restricting device 47.

I
CLAIMS
1. Fuel high-pressure pump for a fuel injection system of an internal combustion engine, with a pump casing, with a drive shaft (35), whereby the drive shaft (35) is supported in the pump casing by a first bearing (39) and by a second bearing (41), with at least one pump element (21) located in a radial manner with regard to the drive shaft (35), whereby a pusher pump (5) conveys fuel to the fuel inlet (15), with one fuel reflux (43), with a measuring device (19) with which to control the discharge quantities of the pump element(s) (21) and with a pressure control valve (45), characterised in that, the pressure control valve (45) is located in the fuel reflux (43). (Figures 1 to 6).
2. Fuel high-pressure pump in accordance with Claim 1, characterised in that, the first bearing (39) is lubricated by pressurised fuel and that the first bearing (39) is hydraulically connected to both the fuel inlet (15) as well as to the fuel reflux (43).
3. Fuel high-pressure pump in accordance with Claim 3, characterised in that, a first flow-restricting device (47) is provided and that the first flow-restricting device (47) is serially connected to the first bearing (39).
4. Fuel high-pressure pump for a fuel high-pressure system of an internal combustion engine, with a pump casing, with a drive shaft (35), whereby the drive shaft (35) is supported in the pump casing by a first bearing (39) and by a second bearing (41), with at least one pump element (21) located in a radial manner with regard to the drive shaft (35), whereby a pusher pump (5) conveys fuel to the fuel inlet (14), with a fuel reflux (43) and with a measuring device (19) with which to control the discharge quantities of the pump element(s) (21) and with a pressure control valve (45) located in the fuel inlet (15), characterised in that, the first bearing

r
I
(39) is lubricated by pressurised fuel, that the first bearing (39) is hydraulically connected to the fuel inlet (15) as well as to the fuel reflux (43), that a first flow-restricting device (47) is provided and that the first flow-restricting device (47) is serially connected to the first bearing (39). (Figure 7).
5. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the measuring device (19) is located in the fuel inlet (15) between the pusher pump (5) and the fuel high-pressure pump (1).
6. Fuel high-pressure pump in accordance with one of Claim 1 to 4, characterised in that, the measuring device (19) is located in the fuel reflux (43) between the pressure control valve (45) and the fuel high-pressure pump (1).
7. Fuel high-pressure pump in accordance with one of Claims 3 to 6, characterised in that, the first flow-restricting device (47) is located before or after the first bearing (39) in the direction of the flow.
8. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the second bearing (41) is lubricated by pressurised fuel and that the second bearing is hydraulically connected to the fuel inlet (15) as well as to the fuel reflux (43).
9. Fuel high-pressure pump in accordance with Claim 8, characterised in that, a second flow-restricting device (67) is provided and that the second flow-restricting device (67) is located in flow direction before or after the second bearing (41).
10. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first pressure-limiting device (47) and/or the second pressure-limiting device (67) are/is designed as a throttle or a trigger wheel vane.

11. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first pressure-limiting device (47) and/or the second pressure-limiting device (67) are/is designed as a current control valve.
12. Fuel high-pressure pump in accordance with one of the preceding Claims, characterised in that, the first bearing (39) is lubricated by pressurised fuel and that the first bearing (39) is supplied with pressurised fuel from a leakage pipe (55) of the pusher pump (5). (Figure 7)
13. Fuel high-pressure pump in accordance with one of the preceding
Claims, characterised in that, the first bearing (39) and/or the second
bearing (41) are/is designed as a slide bearing.
14. Fuel high-pressure pump in accordance with one of the preceding
Claims, characterised in that, the fuel connection (15) ends in the
interior (38) of the pump casing.
15. Fuel injection system for an internal combustion engine with a pusher
pump (5), with a tank (3), with a fuel high-pressure pump (1), with a
common rail (9) and with at least one injector, characterised in that, the
fuel high-pressure pump (1) is a fuel high-pressure pump in accordance
with one of the preceding Claims.
16. Fuel injection system in accordance with Claim 15, characterised in
that, the pusher pump (5) is operated by an internal combustion engine.
17. Fuel injection system in accordance with Claim 15, characterised in that,
the pusher pump (5) is operated by an electromotor.
18. Fuel injection system in accordance with one of Claims 15 to 17,
characterised in that, the pusher pump (5) is designed as a sliding vane

Documents:

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Patent Number

271898

Indian Patent Application Number

5774/CHENP/2007

PG Journal Number

11/2016

Publication Date

11-Mar-2016

Grant Date

09-Mar-2016

Date of Filing

14-Dec-2007

Name of Patentee

ROBERT BOSCH GMBH

Applicant Address

POSTFACH 30 02 20, D-70442 STUTTGART, GERMANY.

Inventors:

#	Inventor's Name	Inventor's Address
1	KRISTEN, MARCUS	SCHLOSSMAUERWEG 12, 71735 EBERDINGEN, GERMANY.
2	KOEHLER, ACHIM	HERTERSTRASSE 1/1, 71254 DITZINGEN, GERMANY.
3	AMBROCK, SASCHA	VIA DELLE ORTENSIE, 70026 MODUGNO, GERMANY.
4	FUCHS, WALTER	BERTASTRASSE 51, 70469 STUTTGART, GERMANY.
5	OTTENBACHER, DIETMAR	GEORG-ELSER-WEG 12, 71088 HOLZGERLINGEN, GERMANY.
6	SCHWEITZER, BERTRAM	MAGDEBRUGER STRASSE 40, 73730 ESSLINGEN, GERMANY.
7	LANGENBACH, CHRISTIAN	IM VOGELSANG 13, 71563 AFFALTERBACH, GERMANY.
8	WUERZ, JOERG	LANDHAUSSTRASSE 37A, 70190 STUTTGART, GERMANY.
9	AKMESE, SABAN	HEGAUSTRASSE 23, 70469 STUTTGART, GERMANY.
10	LAMM, MARCO	VIA DELLE ORTENSIE 19, 70026 STUTTGART, GERMANY.
11	TRAUB, KARL-HEINZ	HOHENSTAUFENSTRASSE 5/1, 73349 WIESENSTEIG, GERMANY.

PCT International Classification Number

F02D 41/38

PCT International Application Number

PCT/EP2006/062119

PCT International Filing date

2006-05-08

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102005027851.5	2005-06-16	Germany