Title of Invention

HIGH-PRESSURE FUEL PUMP COMPRISING A BALL VALVE IN THE LOW-PRESSURE INLET

Abstract

1. Fuel high-pressure pump (10) for a fuel injection system (56) with a casing (17, 47), with a low-pressure inlet (45), with a delivery chamber (31) in which fuel is compressed, with a suction valve (35) between the delivery chamber (31) and the low-pressure inlet (45), whereby a valve element of the suction valve (35) supports itself through a pressure spring (41) located in the delivery chamber (31) against a plunger (13), and with a high-pressure outlet characterised in that, the valve element of the suction valve (35) is designed as a ball (39).

Full Text

Fuel HiIgh-Pressure Pump with Balll Valve in Low-Pressure Inlet Prior Art The invention emanates from the fuel high-pressure pump established in the German patent DE 101 17 600 for a fuel injection system with a casing, with a low-pressure inlet, with a delivery chamber in which fuel is compressed, with a suction valve between the delivery chamber and the low-pressure inlet, whereby a valve element of the suction valve supports itself against a pressure spring located in the delivery chamber. The valve element of the suction valve in this fuel high-pressure pump is designed as a ball valve. Advantages of the Invention According to the present invention in the case of the fuel high-pressure pump for a fuel injection system with a casing, with a low-pressure inlet, with a delivery chamber in which fuel is compressed, with a suction valve between the delivery chamber and the low-pressure inlet, whereby the valve element of the suction valve supports itself against a pressure spring located in the delivery chamber, the valve element of the suction valve is designed as a ball The manufacture of the fuel high-pressure pump is thereby simplified since a ball is cheaper to manufacture when compared to a valve element with a conical nipple and with a shank, as is established in prior art. Apart from this, the degree of efficiency of the fuel high-pressure pump according to the present invention is improved since a ball together with the seat forms a precisely defined circle-shaped vacuum sealed line, which despite the unavoidable manufacturing tolerance when manufacturing the valve seat, seals very well with respect to the valve seat. If the valve seat that functions together with the ball is round then the suction valve according to the invention will seal well even if the angle or the location of the valve seat is not manufactured with the greatest precision. Furthermore, the suction valve according to the present invention ensures that all suction valves of mass-produced fuel high-pressure pumps have almost identical hydraulic properties and thus simplifies the optimisation of mass-produced fuel high- pressure pumps. A variation of the invention provides locating a spring plate between the pressure spring and the ball so that fixing the ball relative to the seat is improved apart from which buckling of the pressure spring is avoided. Over and above this, insertion of a spring plate allows for the diameter of the pressure spring and that of the ball to be different. It is of particular advantage when the diameter of the ball is smaller than that of the pressure spring since, in this case, the buckling of the pressure spring can be effectively avoided and the diameter of the ball corresponds to the hydraulic requirements of the fuel high-pressure pump in an optimal manner. In another design of the invention, the valve seat that works together with the ball, is incorporated in the casing so that the number of sealing surfaces that are loaded with high pressure and the number of components vis-a-vis the fuel high-pressure pump established in prior art are reduced. This increases the reliability of the fuel high- pressure pump according to the invention and reduces manufacturing and assembly costs. It has proved to be of advantage when the valve seat displays a seat angle of between 30° and 150°, particularly between 80° and 100°. As an alternative to the seat that is located directly in the casing, the casing can also encompass a bolt that closes a delivery chamber bore outwards and in which the front surface of the valve seat facing the delivery chamber is designed. The advantage of this variation is that the suction valve, for example, can be assembled or replaced in the event of a repair without having to completely dismember the fuel high-pressure pump since the suction valve can be reached from the outside through the bolt Another design of this exemplary variation provides for the bolt displaying an area with a reduced diameter and that the area where the diameter is reduced as well as the casing border an annulus collector and that the annulus collector is in hydraulic contact with the low-pressure inlet. This, in a very simple manner, thus guarantees that a hydraulic connection to the low-pressure inlet always exists irrespective of how deep the bolt is screwed into the casing. The advantages, according to the present invention naturally are of a fuel system with a fuel tank, with an injection valve that injects fuel directly into the combustion chamber of an internal combustion engine, with a high-pressure fuel pump and with a fuel manifold to which at least one injection valve is connected, for carrying if the fuel high-pressure pump is designed according to one of the aforementioned claims. Other advantages and beneficial designs can be gathered from the following drawing, it's description and the patent claims. Drawing Figure 1 A first exemplary embodiment of a radial plunger pump according to the present invention Figure 2 A second embodiment of a radial plunger pump according to the present invention Figure 3 A magnified illustration of the suction valve according to the present invention and Figure 4 A schematic illustration of an internal combustion engine equipped with a fuel high-pressure pump according to the present invention. Description of the Exemplary Embodiment Figure 1 displays a first exemplary embodiment of a fuel high-pressure pump 10 according to the present invention in cross-section. The fuel high-pressure pump 10 is designed as a radial plunger pump with three pump elements 11. The pump elements 11 encompass a plunger 13 that is led in to a cylinder bore 15. The cylinder bore 15 is completed as a blind hole bore in a casing 17 of the fuel high-pressure pump 10. The cylinder bore 15 can be manufactured through the production and assembly bores 19. After assembly of the fuel high-pressure pump according to the present invention, the assembly pipes 19 are sealed off with plugs 21. The plungers 13 are driven by a drive shaft with an eccentric cam 22 through a polygon ring 23 with flat portions 25. A plunger outer shroud 27 lies against the flat portions 25 and moves the plungers 13 in an oscillating manner when the drive shaft is activated, as a result of which the polygon ring 23 executes a circle-shaped movement. A double arrow 29 in one of the pump elements 11 indicates the oscillating movement of the plunger 13. The cylinder bore 15 and the plunger 13 border a delivery chamber 31 for each pump element 11r whereby the volume of the delivery chamber 31 is dependent on the position of the drive shaft. In the case of the pump element 11 in Figure 1 that is positioned vertically upwards and whose plunger 13 is located close to the top dead centre (OT), the volume of the delivery chamber 31 is minimal whereas it is almost at maximum in the case of the other pump elements 11. With the help of a pressure spring 33, the plunger outer shroud 27 and the plunger 13 along with it are always held in contact with the flat portions of the polygon ring 23. On grounds of clarity, all components of all pump elements 11 have not been furnished with reference signs. All three pump elements 11 are, however, identically designed and have the same components. The cylinder bore 15 is, as already mentioned, designed as a blind hole bore. A suction valve 35 with a seat 37 is provided at the end of the cylinder bore 15 and a ball 39 is provided that works together with the seat 37. The bail 39 is pressed by a pressure spring 43 that supports itself at its other end at the plunger 13, on to a spring plate 41 against the valve seat 37. The pressure spring 43 is thereby dimensioned in such a manner that fuel cannot be automatically sucked in at the bottom dead centre. When a measuring unit located at the suction side of the fuel high-pressure pump 10 is closed, the fuel high-pressure pumps 10 will not discharge any fuel. If the measuring unit is partially or completely opened, excess pressure created by a pusher pump (not illustrated) is built up before the suction valve 35 through which the fuel is pressed against the pressure spring 43 in the delivery chamber 31. The job of the measuring unit is to set the excess pressure before the intake chamber in such a manner that the fuel high-pressure pump 10 discharges the desired discharge flow. When the plunger 13 has moved in the direction of the top dead centre, the initial load of the pressure spring 33 increases greatly, so much so that the ball 39 is pressed against the seat 37 and the connection between the delivery chamber 31 and the tow-pressure inlet 45 is thus interrupted. This effect is considerably intensified through the increasingly higher pressure in the delivery chamber 31. Alternatively, the pressure spring 43 can also be dimensioned in such a manner that the ball 39 still presses lightly against the seat 37 at the bottom dead centre (UT) of the plunger 13. Only if a sufficient excess pressure exists at the low-pressure side of the fuel high-pressure pump 10, riot displayed in Figure 1, vis-4-vis the pressure in the delivery chamber 31 does the fuel flow into the delivery chamber 31. The pressure at the low-pressure side of the fuel high-pressure pump 10 and at the suction side of the delivery chamber 31 respectively and therewith the discharge flow of the fuel high- pressure pump 10 is set through a measuring unit not illustrated in Figure 1 by a control device (not illustrated) subject to the operating condition of the internal combustion engine. These measures ensure that even when the fuel inflow through the low-pressure inlet 45 into the pump element 11 is curtailed by the measuring device that is not illustrated, each of the pump elements 11 sucks in approximately the same fuel quantity and results in a uniform torque and energy requirement of the fuel high-pressure pump 10. This improves the quietness of the internal combustion engine particularly when idling. Since the plunger 13 is not pushed into the cylinder tore 15 to its full extent even at its top dead centre, a sufficient "overflow" is available for the honing tool or as the case may be. This overflow facilitates the manufacture of the cylinder bore 15 that is designed as a blind hole. A high-pressure outlet as well as the associated seat are not illustrated in Figure 1 since the high-pressure outlet and the associated seat are housed behind the pump elements 11 perpendicular to the layer. The location of this component can be derived from DE- PS 101 17 600, which is hereby referred to. By using a spring plate 41 between the ball 39 and the pressure spring 43, guiding of the ball 39 is improved. Apart from this, as a result of improved contact surface of the pressure spring 43 on the spring plate 41, buckling of the pressure spring 43 can be avoided. Finally, the diameter of the ball 39 can be selected independent of the diameter of the pressure spring 43, which can be an advantage in the case of optimisation of the fuel high-pressure pump 10. It is, however, also absolutely conceivable and possible to do away (not illustrated) with the spring plate 43, so that the pressure spring 43 rests directly on the ball 39. In the first exemplary embodiment illustrated in Figure 1 of the fuel high-pressure pump 10 according to the present invention, there are only a very small number of high- pressure sealed locations. This is, in particular, the seat 37 in connection to the ball 39 as well as the annular gap between the plunger 13 and the cylinder bore 15. In many cases these small numbers of high-pressure sealed locations warrant the somewhat higher manufacturing costs when manufacturing the cylinder bore 15, if the same is executed as a blind hole. Specific advantages of a ball valve designed as a suction valve 35 are described in further detail as follows in connection with Figure 3. Figure 2 represents in section a second exemplary embodiment of a high-pressure pump 10 according to the present invention. Same components are provided with the same reference signs and what has been said with regard to Figure 1 is valid here too. The essential difference with regard to the first exemplary embodiment is that the cylinder bore 15 is not executed as a blind hole bore but as a through hole. In this exemplary embodiment, a bolt 47 closes the cylinder bore 15. The seat 37 of the suction valve 35 is incorporated in the bolt 47. The function of the suction valve 35 is explained in greater detail below with the help of Figure 3, which displays an enlarged cut-out A of Figure 2. The plunger 13 in Figure 2 is in the top dead centre. As a result, the delivery chamber 31 has a minimal volume and the ball 39 seals up the delivery chamber 31 against the low-pressure inlet 45 of the fuel high-pressure pump 10. This sealing up takes place along a circle-shaped sealing line (not marked), which results from the contact line between the ball 39 and the seat 37. The pressure tightness of this suction valve 35 designed as a ball valve is very high since there is only a line-shaped contact between the ball 39 and the seat 37, which in turn results in a correspondingly high surface pressure on the sealing line. Apart from this, requirements of precision in the case of manufacturing a sealing ball valve are lower than in the case of ball valves. Depending on how the angle a of the seat 37 is selected, the diameter of the sealing line between the ball 39 and the seat 37 can be varied in the case of a constant ball diameter. It has emerged that seat angles a between 30 0 and 150° are possible and that, as a rule, a seat angle a of 90° leads to very good results. An axial bore 48 as well as a cross bore 49 are attached at the seat 37. Alternatively, several cross bores 49 (not illustrated) can be provided. The cross bore 49 ends in an annulus collector 50, which is bordered by the casing 17 and an area reduced in diameter 50 of the bolt 47. At the front side 52 of the bolt 47 is a biting flange 53 that seals up the annulus collector 51 from the delivery chamber 31. The annulus collector 51 is in hydraulic contact with the low-pressure inlet 45, not illustrated here, of the fuel high-pressure pump 10. Since the annulus collector surrounds the bolt 47 on all sides, fuel can be sucked into the delivery chamber 31 through the cross bore 49 and the axial bore 48 independent of how deep the bolt 47 is screwed into the casing 17. By using a suction valve 35 designed as a ball valve, the degree of efficiency of the fuel high-pressure pump is increased since the ball 39 releases a large flow cross-section as soon as it is lifted from the seat 37, so that the fuel can be quickly sucked up without any great flow loss. In this regard it is also of an advantage if the ring-shaped cross- sectional surface between the seat 37 and the ball 39 is up to about 20 times larger than the cross-section of the cross bore 49 when the suction valve 35 is open. Apart from this, due to the good sealing property of the suction valve 35 designed as a ball valve, no fuel can be pushed back from the delivery chamber 31 in to the low- pressure inlet 45 during the discharge stroke of the plunger 13. Figure 4 is a schematic representation of an internal combustion engine 54, which includes a fuel injection system 56. This in turn, has a fuel tank 58 from which an electrical low-pressure pump 60 discharges fuel. The electrical low-pressure fuel pump 60 discharges fuel to the fuel high-pressure pump 10, which is designed in the manner illustrated in Figures 1 and 2. The high-pressure outlet 18 of the fuel high-pressure pump 10 is connected to a fuel manifold 62. This is generally called "Common-Rair. A total of four injection valves 64 are connected to the fuel manifold 62. These respectively inject fuel directly into the combustion chamber 66 of the internal combustion engine 54. 10 Vie Claim* 1. Fuel high-pressure pump (10) for a fuel injection system (56) with a casing (17, 47), with a low-pressure inlet (45), with a delivery chamber (31) in which fuel is compressed, with a suction valve (35) between the delivery chamber (31) and the low-pressure inlet (45), whereby a valve element of the suction valve (35) supports itself through a pressure spring (41) located in the delivery chamber (31) against a plunger (13), and with a high-pressure outlet characterised in that, the valve element of the suction valve (35) is designed as a ball (39). 2. Fuel high-pressure pump according to Claim 1 characterised in that, a spring plate (41) is provided between the pressure spring (43) and the ball (39). 3. Fuel high-pressure pump according to Claim 1 or 2 characterised in that the diameter of the ball (39) is smaller than the diameter of the pressure spring (43). 4. Fuel high-pressure pump (10) according to one of the preceding Claims characterised in that a seat (37) that works together with the ball (39) is present in the casing (17). 5. Fuel high-pressure pump according to Claim 4 characterised in that, the seat (37) has a seat angle (a) of between 30° and 150°, particularly of 90°. 6. Fuel high-pressure pump according to one of the preceding Claims characterised in that the casing (17, 47) surrounds a bolt (47) which closes a cylinder bore (31) outwards and that the seat (37) is designed at the front side (52) of the bolt (47) that faces the delivery chamber (31). 7. Fuel high-pressure pump (10) according to Claim 6 characterised in that the bolt (47) has an area (50) that is reduced in diameter, that the area (50) that is reduced in diameter together with the casing (17) border an annulus collector (51) and that the annulus collector (51) is in hydraulic contact with the low-pressure inlet (45). 8. Fuel injection system (56) with a fuel tank (58), with at least one injection valve (64), which injects fuel directly in to the combustion chamber (66) of an internal combustion engine (54), with at least one high-pressure fuel pump (10) and with a fuel manifold (62) to which at least one injection valve (64) is attached, characterised in that, the fuel high-pressure pump (10) is designed according to one of Claims 1 to 7 (Figure 4). 9. Internal combustion engine (54) with at least one combustion chamber (66) in to which fuel is directly injected characterised in that, it has a fuel injection system (56) according to Claim 8 (Figure 4). 10. Fuel high-pressure pump, substantially as hereinabove described and illustrated with reference to the accompanying drawings.

Documents:

3087-CHENP-2004 OTHERS 22-01-2013.pdf

3087-CHENP-2004 AMENDED CLAIMS 22-01-2013.pdf

3087-CHENP-2004 AMENDED PAGES OF SPECIFICATION 22-01-2013.pdf

3087-CHENP-2004 CORRESPONDENCE OTHERS 17-01-2012.pdf

3087-CHENP-2004 FORM-3 22-01-2013.pdf

3087-CHENP-2004 OTHER PATENT DOCUMENT 22-01-2013.pdf

3087-CHENP-2004 CORRESPONDENCE OTHERS 01-03-2012.pdf

3087-CHENP-2004 EXAMINATION REPORT REPLY RECEIVED 22-01-2013.pdf

3087-chenp-2004 abstract.pdf

3087-chenp-2004 claims.pdf

3087-chenp-2004 correspondence others.pdf

3087-chenp-2004 correspondence po.pdf

3087-chenp-2004 description (complete).pdf

3087-chenp-2004 drawings.pdf

3087-chenp-2004 form 1.pdf

3087-chenp-2004 form 18.pdf

3087-chenp-2004 form 3.pdf

3087-chenp-2004 form 5.pdf

3087-chenp-2004 pct.pdf