CN114109680A

CN114109680A - High-pressure fuel pump

Info

Publication number: CN114109680A
Application number: CN202110995383.0A
Authority: CN
Inventors: C·比勒; S·韦尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-08-27
Filing date: 2021-08-27
Publication date: 2022-03-01
Also published as: DE102020210846A1

Abstract

The invention relates to a high-pressure fuel pump having a valve receptacle (27) formed in a pump housing (52) and having a valve device (24), the valve seat (68) of which has a groove (81) running around the circumference of the valve seat in the region of a radially outer contact surface that is in contact with the pump housing (52), and/or the pump housing (52) has a groove (80) in the valve receptacle (27) that is directed radially outward and runs around in the circumferential direction.

Description

High-pressure fuel pump

Technical Field

The present invention relates to a high-pressure fuel pump.

Background

In a fuel system of an internal combustion engine, a high-pressure fuel pump is used in order to compress fuel from a pre-pressure existing in a low-pressure region to an injection pressure required for fuel injection. Such high-pressure fuel pumps usually have at least one piston which can be moved axially by means of a drive, which is formed, for example, by a cam or an eccentric disk. Due to the axial movement of the piston, fuel is sucked in the suction stroke from the low-pressure region into the delivery chamber through a quantity control valve, which represents the valve arrangement and is sometimes referred to as the inlet valve. During the delivery stroke, fuel is compressed in the piston chamber and supplied through an outlet valve to a high-pressure region, which is usually designed as a rail. The amount of fuel supplied to the high-pressure region through the outlet valve can thus be controlled if the quantity control valve is not closed at the beginning of the delivery stroke or is open during the delivery stroke.

Such high-pressure fuel pumps usually comprise an electromagnetic actuating device for influencing the position of a valve element of the quantity control valve. In general, the valve element can be forcibly opened or held open by means of an electromagnetic actuating device, for example by a tappet. A typical inlet valve or volume control valve comprises a valve canister, the already mentioned valve element and a valve seat. The valve element is usually tensioned in the closed position by means of a spring bearing against the valve pot and the valve element. In the closed position, the valve element rests against the valve seat and separates the delivery chamber side from the intake side. The valve cup and the valve seat are usually arranged in such a way that they contact the housing of the high-pressure fuel pump and are fixed therein by means of a caulking joint (Verstemmung). Modern engine designs and operating types require increasingly higher pressures that build and drop periodically. Thereby, the components of the inlet valve and the caulking are periodically heavily loaded.

Disclosure of Invention

The object of the present invention is to provide a high-pressure fuel pump which is easy to manufacture, meets the requirements for a high delivery pressure and operates or is constructed in a robust and reliable manner.

This object is achieved by the high-pressure fuel pump according to the invention. Other advantageous embodiments can be found in the following description and in the preferred embodiments.

The invention relates to a high-pressure fuel pump for an internal combustion engine. The high-pressure fuel pump has a pump housing. A delivery lumen is disposed in the pump housing. Usually, the cylinder delimiting the delivery chamber is realized by a hole in the pump housing, however, the use of a cylinder liner is also conceivable. The high-pressure fuel pump further comprises an inlet region with a connection for connection to a low-pressure region of a fuel system in which the high-pressure fuel pump is used. In general, the connection is configured as a separately configured nipple which is attached to the housing, which may provide advantages in terms of manufacturing technology. For example, the nipple can be configured as a deep-drawn part. However, it is also conceivable for the connection to be formed by the material of the pump housing. The high-pressure fuel pump further comprises a valve arrangement which, in an open state, fluidly connects the inlet region with the delivery chamber and, in a closed state, separates them from one another. The valve device is also referred to as an inlet valve or a quantity control valve. The valve device comprises a valve pot, a valve element and a valve seat and in particular a spring. The valve pot is arranged on the delivery chamber side or high-pressure side and the valve seat is arranged on the low-pressure side. A valve element is arranged between the valve pot and the valve seat. The valve element is loaded in the axial direction into the closed position just mentioned. For this purpose, the valve element is usually clamped in the valve device by means of the above-mentioned spring, which in particular bears against the valve element and the valve pot. In the closed position, the valve element rests sealingly against the valve seat. The valve seat is secured relative to the pump housing by caulking (Verstemmung). The valve device is arranged in a valve receptacle formed in the pump housing. In this case, the valve cup is axially clamped between the valve seat and an axial contact surface of the pump housing. According to a first embodiment of the invention, it is now provided that the valve seat has a groove running around the circumference of the valve seat in the region of the radially outer contact surface which is in contact with the pump housing. According to an additional or alternative embodiment of the invention, the pump housing has a groove in the valve receptacle, which groove is directed radially outward and circumferentially around, at an axial level between an axial contact surface of the pump housing and the valve seat. In this way, the stiffness can be reduced in a targeted manner and the load on the pump housing and/or the inlet valve, in particular the valve seat, can therefore be controlled in a targeted manner. Therefore, weak spots can be reduced. The arrangement of one or both of the grooves mentioned makes the construction more flexible, so that pressure fluctuations, pulsations or pressure peaks due to yielding of the material (Nachgeben) represent a lower load at the connection points of the individual components to one another. The probability of leakage is reduced.

Furthermore, the stress in the strength critical region can be reduced to the point where a durable design can be achieved. Thereby, an improvement of the strength of the respective member is obtained. The wall thickness can be minimized by the improved strength, which is necessary to maintain the required pump housing installation space. This reduces the installation space for the pump housing, the valve seat and other components provided with corresponding grooves.

Advantageously, the circumferential groove has a substantially triangular cross section in the region of the radially outer contact surface of the valve seat. This shaping facilitates manufacture and has positive properties with regard to the final flexibility of the valve seat.

Advantageously, the circumferential groove has a substantially rectangular cross section in the valve receptacle. Such a shape can be simply manufactured and provides advantageous flexibility characteristics.

A plurality of circumferential grooves may also be provided in the valve receptacle and/or in the valve seat. It is conceivable that the corresponding cross-section may also have a shape other than rectangular and/or triangular, for example circular, elliptical, wavy, etc. The cross-sections of the individual grooves may differ in shape and/or size, respectively. It is conceivable, however, that the cross-sections of the individual grooves are identical in terms of size and/or shape. These surrounding grooves serve as relief grooves and reduce the rigidity of the component in which they are arranged.

Advantageously, the circumferential groove in the valve receptacle abuts against an axial contact surface of the pump housing.

Advantageously, the valve receptacle is formed with a constant diameter from the caulking bead formed by caulking as far as the axial contact surface, except in the region of the radially outwardly extending groove. The valve receptacle can be produced in a simple drilling process, and the corresponding groove can then be introduced, the valve device inserted, and the valve seat can then be fixed by structural caulking. The respective high-pressure fuel pump is therefore cost-effective and can be produced on a large scale in a short cycle time. The valve seat with the corresponding groove can be provided separately as a finished component.

Advantageously, the valve seat tapers in the radially outward direction in the axial extension of the valve seat towards the radially outer contact surface. In other words, the axial thickness of the valve seat decreases in the radial direction such that the axial thickness of the valve seat is minimal at the radially outer edge. The tapering of the valve seat can have an arcuate, linear or tapering course. Obviously, other tapering shapes and different kinds of course are also conceivable. This has a positive effect on the stress profile in a tight and loaded valve seat.

Drawings

Further features, application possibilities and advantages of the invention emerge from the following description of exemplary embodiments of the invention which are illustrated on the basis of the drawings, wherein these features are not only relevant individually but also in various combinations for the invention, without this having to be explicitly indicated again.

The figures show:

FIG. 1 shows a simplified schematic diagram of a fuel system of an internal combustion engine;

FIG. 2 shows a cross-sectional view of a high pressure fuel pump;

FIG. 3 shows a part of the region of FIG. 2;

fig. 4 shows a schematic clamping stress diagram (Verspannungsdiagramm); and is

Fig. 5 shows a partial region of a sectional view of a high-pressure fuel pump according to a further exemplary embodiment.

Detailed Description

Fig. 1 shows a fuel system 10 for an internal combustion engine, not shown in detail, in a simplified schematic representation. Fuel is supplied from the fuel tank 12 via the intake line 14, via the prefeed pump 16 and the low-pressure line 18, through an inlet region 20 to a high-pressure fuel pump 22. Next to the inlet region 20, a valve arrangement 24 is arranged, which forms a quantity control valve 25 of the high-pressure fuel pump 22 and by means of which a piston chamber 26 can be connected to a low-pressure region 28, which comprises the prefeed pump 16, the intake line 14 and the fuel tank 12.

The electromagnetic actuating device 32 can be actuated by the control unit 30. The quantity control valve 25 can in turn be actuated or influenced in its position by means of a solenoid actuator 32, which will be discussed in more detail later. The high-pressure fuel pump 22 is in the present case embodied as a piston pump, wherein the pistons 34 can be moved up and down along a piston longitudinal axis 38 by means of a drive 36 embodied as a cam disk, which is schematically illustrated by an arrow with reference numeral 40.

An outlet valve 44, which is embodied in fig. 1 as a spring-loaded check valve and which can be opened toward the outlet 42, is arranged in hydraulic connection between the delivery chamber 26 of the high-pressure fuel pump 22 and the outlet 42. The outlet 42 is connected to a high pressure line 46 and through this high pressure line to a high pressure accumulator 48 ("rail"). Furthermore, a pressure-limiting valve 50, which is likewise designed as a spring-loaded check valve and can be opened toward the delivery chamber 26, is arranged in hydraulic connection between the outlet 42 and the delivery chamber 26. In operation of fuel system 10, pre-feed pump 16 delivers fuel from fuel tank 12 into low pressure line 18. The inlet valve 28 may be closed and opened according to the respective fuel demand. Thereby influencing the amount of fuel delivered to the high-pressure accumulator 48. In this case, the solenoid actuator 30 is actuated accordingly by the control unit 32 as described above and influences the position of the quantity control valve 25.

Fig. 2 shows a partial sectional view of the high-pressure fuel pump 22. As can be seen from the illustration in fig. 2, the pressure-limiting valve 50, the outlet valve 44 and the inlet valve 24 are arranged in a pump housing 52. Also disposed in the pump housing 52 is the delivery chamber 26, also referred to as the piston chamber 26, and a portion of the piston 34. The lower end of the piston projecting from the pump housing 52 is connected to a piston disc 54. The piston 34 rests through the piston disk 54 on the drive device 36, which is not shown in fig. 2. This configuration and arrangement of the outlet valve 44, the pressure-limiting valve 50 and the region around them should be understood as an example and can also be configured in other ways. The same applies to the piston 34 or the seal arranged at its lower part and to other configurations in this region.

A damping device 23 is arranged at the end of the high-pressure fuel pump 22 opposite the piston disc 54. The damping device 23 serves to compensate for pressure fluctuations occurring during operation of the high-pressure fuel pump 22.

The valve device 24 and the solenoid operated device 32 are explained in detail below. The solenoid operator 32 includes a solenoid 56. If the electromagnetic coil 56 is energized, a magnetic field is formed, by means of which the valve needle 58 can be adjusted in its position. The valve element 60 of the quantity control valve 25 can be forcibly opened or held open by the valve needle 58. The solenoid 56 can thus influence the position of the quantity control valve 25, i.e. open or hold it open, by means of the valve needle 58.

The area around the valve device 24 is shown in detail in fig. 3. Valve assembly 24 includes a valve canister 66, a valve element 60, and a valve seat 68. The valve element 60 is biased into the closed position by a spring 64. In the closed position, the valve element rests sealingly against the valve seat 68. The valve seat 68 is secured relative to the pump housing 52 by a caulking 70.

The valve element 60 is disposed in the flow passage 62. The flow passage 62 connects the low pressure region 28 with the delivery chamber 26. Depending on the position of valve element 60, flow passage 62 is fluidly through or fluidly interrupted. In other words, depending on the position of valve element 60, low pressure region 28 and delivery lumen 26 are in fluid communication with each other or are fluidly isolated from each other.

The axis of movement of the valve element 60 is indicated by reference numeral 63. The movement axis 63 corresponds to an axial direction a extending orthogonally to the radial direction R.

The valve device 24 is arranged in a valve receptacle 27 in the pump housing 52. The valve receiving portion 27 extends in the axial direction a and has different areas. A first region, indicated by the recess 71, extends in the axial direction a as far as an axial contact surface 72 in the pump housing 52.

In the axial direction a, another region, referred to as the valve-pot receptacle 73, adjoins the cutout 71. A third region, which is currently referred to as a valve seat receiver 74, adjoins the valve pot receiver 73. Currently, the canister receiving portion 73 and the valve seat receiving portion 74 have the same diameter. In particular, the notch 71 has a smaller diameter than the valve-pot receiving portion 73. Thereby, the axial abutment surface 72 can be formed.

The valve pot 66 contacts the pump housing 52 in the axial direction on the axial contact surface 72. A circumferential groove 80 is arranged in the valve receptacle 27 in the valve-pot receptacle 73. Depending on the shape and size of the groove 80, the valve pot 66 may or may not have radial contact with the pump housing 52 in the radial direction R within the valve pot receiving portion 73. The cross section of the groove 80 is currently configured in the form of a rectangle. Currently, the valve pot 66 is disposed within the valve pot receptacle 73 and the indentation 71.

The valve canister 66 is sandwiched between the axial abutment surface 72 and the valve seat 68. In the embodiment shown, the valve seat 68 has a groove 81 which surrounds in the region of the radially outer contact surface. Currently, the cross section of the surrounding groove 81 has a triangular shape.

The valve seat 68 contacts the pump housing 52 in the radial direction R within the valve seat receiving portion 74. The valve seat 68 is secured by a caulking 70. During the caulking process, a caulking bead 75 is formed, which fixes the valve seat 68 in the valve receptacle 27 in a form-fitting manner. In addition to this form closure, the valve seat 68 is fixed in a force-fitting manner by a caulking 70. The resulting stress is shown in the schematic clamping stress diagram in fig. 4 and is denoted F_VAnd (4) showing.

Fig. 4 shows a schematic clamping stress diagram. In the present case, stress F_VPlotted in arbitrary units on the X-axis and the length change as is plotted in arbitrary units on the Y-axis.

The characteristic curve of the pump housing 52 is denoted by reference numeral 90 in the illustrated diagram. The characteristic curve of the valve seat 68 is indicated in the diagram shown by the reference numeral 91. The intersection of these two

characteristic curves

90, 91 represents the cumulative stress, which is indicated by the double arrow F_V1Shown.

The cyclic load created by the alternating delivery and intake strokes is distributed to the pump housing 52 and the valve seat 68 according to stiffness. The cyclic load is indicated by the double arrow F in FIG. 4_BShown. Here, double arrow F_BCorresponds to a point on the characteristic curve 90 of the pump housing 52, double arrow F_BCorresponds to a point on the characteristic curve 91 of the valve seat 68. Cyclic loading F_BThe part falling onto the pump housing 52 is indicated by the double arrow F in fig. 4_BGAnd (4) showing. Here, double arrow F_BGCorresponds to a point on the characteristic curve 90 of the pump housing 52, double arrow F_BGCorresponds to the value X of the intersection of the two

characteristic curves

90 and 91. Cyclic loading F_BIs shown in fig. 4 with a double arrow F_BVSShown. Here, double arrow F_BVSCorresponds to the point of the characteristic curve 91 of the valve seat 68, double arrow F_BVSCorresponds to the value X of the intersection of the two

characteristic curves

90 and 91.

The stiffness of the pump housing 52 and valve seat 68 may be affected by the

grooves

80, 81 acting as relief grooves. The rigidity of the valve seat 68 is thus reduced, for example, by the circumferential groove 81 of the valve seat.

In fig. 4, the characteristic curve describing the valve seat 68 with the circumferential groove 81 is shown as a dashed line with the reference number 92. Thus, for example, a double arrow F is obtained_BThe' indicated cyclic loading. Here, double arrow F_BThe first end of the' corresponds to a point on the characteristic curve 90 of the pump housing 52, double arrow F_BThe second end of' corresponds to a point on the characteristic curve 92 of the valve seat 68. Cyclic loading F_B' to the pump housingThe part above 52 is shown in fig. 4 with a double arrow F_BG' show. Here, double arrow F_BGThe first end of the' corresponds to a point on the characteristic curve 90 of the pump housing 52, double arrow F_BGThe second end of' corresponds to the value of X at the intersection of the two

characteristic curves

90 and 92. Cyclic loading F_BThe part of the' that falls onto the valve seat 68 with the surrounding groove 81 is shown in fig. 4 with a double arrow F_BVS' show. Here, double arrow F_BVS' A first end of which is located at a point on the characteristic curve 92 of the valve seat 68, double arrow F_BVSThe second end of' corresponds to the value of X at the intersection of the two

characteristic curves

90 and 92.

By comparing double arrows F_BGAnd F_BG' or F_BVSAnd F_BVSThe length of the' clearly shows that the force loading acting cyclically on the pump housing 52 is increased by the circumferential groove 81 on the valve seat 68 and the force loading acting on the valve seat 68 is reduced. Clearly, the double arrow F_BG' ratio double arrow F_BGBig and double arrow F_BVS' ratio F_BVSIs small.

By varying the size, number and/or shape of the

circumferential grooves

80, 81, the stiffness and thus the corresponding cumulative load (force load) can be controlled.

Fig. 5 shows a partial region of a sectional view of a high-pressure fuel pump 22 according to another embodiment. The area around the valve means 24 is shown in detail. For clarity, the valve arrangement 24 is not shown.

In the present case, the groove 80 adjoins the axial contact surface 72 of the pump housing 52. The illustrated circumferentially encircling groove 80 of the valve receptacle 27 has a different geometry than the previous embodiments. Furthermore, the embodiment shown does not have the notch 71.

The presently shown groove 80 of the valve receptacle 27 has in particular a radial depth of 0.3 mm. In other words, the cross-section of the groove 80 extends in the radial direction R by a maximum of 0.3 mm. The cross section of the groove 80 extends in the axial direction a from the bottom 99 of the valve receptacle 27 initially in a circular section 95, in particular in a quarter-circular section, which in particular has a radius of 0.6mm in the radial direction R. This is followed by a section 96 running parallel to the movement axis 63. In the present case, this section 96 forms the straight and deepest section of the groove 80. The end of the portion 96 facing away from the portion 95 is rounded off counter to the radial direction R, i.e. in the direction of the movement axis 63. In particular, the rounding 97 has a radius corresponding to the radius of the section 95, in particular a radius of 0.6 mm. The section 98, which runs straight against the radial direction R, i.e. in the direction of the movement axis 63, adjoins the rounding 97. The section 98 forms the end of the groove 80, so that a section of the valve receptacle 27 which is flat and runs parallel to the movement axis 63 adjoins the section 98 of the groove 80. The portion 98 runs in particular at an angle of 15 ° relative to the movement axis 63. Thus, the illustrated groove 80 extends in the axial direction a through the

sections

95, 96, 97, and 98. In particular, the axial length of the cross section of the groove 80, i.e. the extension of the groove 80 in the axial direction a, is 2.5 mm.

The above-described geometry of the groove 80 or of the cross section of the groove 80 can be applied to other grooves, in particular to the groove 81.

Claims

1. A high-pressure fuel pump (22) for an internal combustion engine, comprising a pump housing (52) with a delivery chamber (26), wherein the high-pressure fuel pump (22) further comprises an inlet region (20) with a connection for connection with a low-pressure region (28) of a fuel system (10), wherein the high-pressure fuel pump (22) further has a valve device (24) which, in an open state, fluidically connects the inlet region (20) with the delivery chamber (26) and, in a closed state, separates the inlet region and the delivery chamber from one another, wherein the valve device (24) comprises a valve pot (66), a valve element (60) and a valve seat (68) and in particular a spring (64), wherein the valve element (60) is loaded in an axial direction (A), in particular by the spring (64), into a closed state, in the closed position, the valve element rests sealingly against the valve seat (68), wherein the valve seat (68) is fastened relative to the pump housing (52) by caulking (70), and the valve device (24) is arranged in a valve receptacle (27) formed in the pump housing (52), wherein the valve pot (66) is axially clamped between the valve seat (68) and an axial contact surface (72) of the pump housing (52), characterized in that the valve seat (68) has a groove (81) which runs around the periphery of the valve seat in the region of a radially outer contact surface which is in contact with the pump housing (52), and/or the pump housing (52) has a groove (80) in the valve receptacle (27) that is directed radially outward and circumferentially around, at an axial level between an axial contact surface (72) of the pump housing (52) and the valve seat (68).

2. The high-pressure fuel pump (22) as claimed in claim 1, characterized in that the circumferential groove (81) has a substantially triangular cross section in the region of the radially outer contact surface of the valve seat (68).

3. The high-pressure fuel pump (22) according to claim 1 or 2, characterized in that the circumferential groove (80) has a substantially rectangular cross section in the valve receptacle (27).

4. The high-pressure fuel pump (22) according to any one of the preceding claims, characterized in that the circumferential groove (80) adjoins the axial contact surface (72) in the valve receptacle (27).

5. The high-pressure fuel pump (22) according to one of the preceding claims, characterized in that the valve receptacle (27) is constructed with a constant diameter from a caulking projection (75) formed by the caulking (70) up to the axial contact surface (72) with the exception of the region of a radially outwardly extending groove (80).

6. The high-pressure fuel pump (22) according to one of the preceding claims, characterized in that the valve seat (68) tapers in the axial extension thereof in the radially outward direction towards the radially outer contact surface.