CN218882498U

CN218882498U - High-pressure fuel pump

Info

Publication number: CN218882498U
Application number: CN202221972666.XU
Authority: CN
Inventors: G·布雷登费尔德; R·科恩哈斯; S·韦尔; T·弗洛伊霍费尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2021-07-28
Filing date: 2022-07-28
Publication date: 2023-04-18
Anticipated expiration: 2032-07-28
Also published as: CN115681127A; EP4124745A1; DE102021208122A1; KR20230017741A

Abstract

The utility model relates to a fuel high-pressure pump (10), include: an outlet valve (37) and a pressure-limiting valve (22), wherein the outlet valve (37) is fixed in an outlet valve opening (37 a) of the pump housing (12), wherein the pressure-limiting valve (22) is fixed in a pressure-limiting valve opening (22 a) of the pump housing (12), and wherein the outlet valve opening (37 a) and the pressure-limiting valve opening (22 a) extend in planes which are geometrically parallel to one another perpendicular to a longitudinal direction (LA) of the high-pressure fuel pump (10).

Description

High-pressure fuel pump

Technical Field

The utility model relates to a fuel high-pressure pump.

Background

From the prior art, for example from document EP 2 344 749 B1 by the applicant, a high-pressure fuel pump is known, which comprises an inlet for supplying fuel; an outlet for outputting compressed fuel; a pump housing; a delivery chamber disposed in the pump housing; a pump piston which is movable in the pump housing in the longitudinal direction and which delimits the delivery chamber; an inlet valve arranged between the inlet and the delivery chamber, the inlet valve being open towards the delivery chamber; an outlet valve disposed between the delivery chamber and the outlet, the outlet valve opening away from the delivery chamber; a high pressure region fluidly extending between the outlet valve and the outlet; a low pressure region fluidly extending between the inlet and the inlet valve; and a pressure limiting valve fluidly connecting the high pressure region with the low pressure region and opening toward the low pressure region such that fuel flows from the high pressure region into the low pressure region when a pressure difference of fuel in the high pressure region and fuel in the low pressure region exceeds an opening pressure.

In the pump disclosed in the initially cited prior art, it is furthermore provided that the pump housing comprises a pump body and a pump cover which are connected to one another, wherein a damping region belonging to the low-pressure region, in which a diaphragm damper is arranged, is delimited by the pump body and the pump cover, wherein the pressure relief valve fluidically connects the high-pressure region to the damping region and opens out into the damping region, so that fuel flows out of the high-pressure region into the damping region when the pressure difference between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds an opening pressure.

In the pumps known from the prior art mentioned at the outset, it is furthermore provided that the outlet valve is fixed in an outlet valve opening of the pump housing and the pressure limiting valve is fixed in a pressure limiting valve opening of the pump housing.

Disclosure of Invention

The present invention is based on the expectation that the design of the high-pressure fuel pump with the above-mentioned features ensures that the pump can be manufactured simply.

For this purpose, it is provided according to the invention that the outlet valve opening and the pressure-limiting valve opening extend in planes which are geometrically parallel to one another perpendicular to the longitudinal direction.

On the one hand, the machining, for example the cutting, of the pump housing for producing the outlet valve opening and the pressure limiting valve opening is thereby simplified, since this machining can take place in mutually parallel planes, in particular in the same plane, and thus, for example, even with the aid of the same tool and/or, for example, simultaneously.

On the other hand, the assembly of the fuel high-pressure pump is thereby simplified, since the bores belonging to the pressure-limiting valve and the outlet valve are located in mutually parallel or identical planes, and the pressure-limiting valve and the outlet valve can thus be introduced in the same manner, for example by means of the same tool, and/or for example simultaneously.

Overall, the pump according to the invention can be produced more simply than pumps known from the prior art.

To a particular extent, this advantage occurs if the outlet valve opening and the pressure-limiting valve opening are oriented geometrically parallel to one another.

In one embodiment, it is provided that the outlet is designed as an outlet connection piece which is fastened to the pump housing. The outlet connection in particular has a tubular basic shape and can be welded or screwed, for example, to the pump housing and, in addition, itself comprises means, such as threads or the like, by means of which the high-pressure line can be fixed in a sealing manner to the pump housing.

Furthermore, it can be provided that an outlet connection chamber is formed between the pump housing and the outlet connection. The outlet connection chamber may on the one hand be formed by or comprise the part of the connection piece inner chamber which is directed toward the pump housing. The outlet nipple chamber may additionally also comprise a recess in the pump body, which is covered by the outlet nipple, in particular consisting of the two sub-chambers. Alternatively, the outlet nipple chamber can be formed by a recess in the pump body which is covered by the outlet nipple.

In one embodiment, it can be provided that both the outlet valve opening and the pressure-limiting valve opening issue from the outlet connection chamber. This reduces the number of parts that constitute the high-pressure fuel pump and the number of seal portions required in the high-pressure fuel pump.

Alternatively, it can be provided that only the outlet valve opening, but not the pressure-limiting valve opening, starts from the outlet connection chamber. This has the following advantages: the flow cross section of the outlet nipple chamber and thus also the cross section for fastening the outlet nipple to the pump body can be reduced considerably. This improves the reliability or compressive strength with which the outlet connection can be fastened to the pump housing, since the cross section for fastening the outlet connection to the pump body is proportional to the force acting on the connection (when delivering fuel at high pressure). In contrast, the attachment length along which the nozzle can be fixed on the pump housing along its periphery is only proportional to the square root of the cross section of the outlet nozzle fixed on the pump body. The reduction in the cross-section of the outlet connection fixed to the pump body, which is brought about by the measure that only the outlet valve opening, but not the pressure-limiting valve opening, starts from the outlet connection chamber, therefore increases the ratio between the attachment length along which the connection piece can be fixed to the pump housing along its periphery and the cross-section of the outlet connection fixed to the pump body. The fixing of the outlet connection can therefore take up the higher pressure of the fuel being delivered.

For example, in one embodiment, it can be provided that the pressure-limiting valve opening is closed on its outlet side by means of a ball or a plug, wherein the outlet valve opening is connected to the pressure-limiting valve opening via a high-pressure connection opening in the high-pressure region. The fluid communication between the outlet and the pressure-limiting valve is then effected through a high-pressure connection bore only in the interior of the pump housing. At the same time, a simple and reliable sealing is achieved in that the pressure-limiting valve opening is closed by a ball or a plug.

For example, in one embodiment, it can be provided that the high-pressure connection opening starts from the damping region and is closed off on its outlet side by a ball or a plug. This results in a relatively short longitudinal extent of the high-pressure connection opening and a further simple and reliable sealing point.

The increase in spatial flexibility is caused by the following measures: the outlet valve opening is connected to the pressure-limiting valve opening via two high-pressure connection openings in the high-pressure region, wherein the first high-pressure connection opening starts from the damping region and is closed on its outlet side by means of a ball or a plug and opens into a second high-pressure connection opening which itself opens into the outlet valve opening. The first and second high pressure connection holes may be oriented at an angle of, for example, 90 ° or between 45 ° and 135 ° with respect to each other.

In particular, the pressure-limiting valve opening is connected to the damping region via a low-pressure connecting opening in the low-pressure region. The pressure-limiting valve opening and the low-pressure connection opening can be arranged, for example, at right angles to one another; the low-pressure connection holes may be oriented, for example, in the longitudinal direction or at an angle of 0 ° to 60 ° with respect to the longitudinal direction. This measure results in an efficient utilization of the space available for the inner contour in the pump housing or pump body.

The improved damping of pressure surges which potentially occur in the damping space via the pressure-limiting valve can be brought about by the following measures: the pump body has a recess on the side facing the damping region, wherein the low-pressure connection opening opens into the recess in such a way that the flow cross section of the recess is wider than the flow cross section of the low-pressure connection opening.

In the case of a plug which closes the pressure-limiting valve opening and/or a plug which closes the high-pressure connection opening, an advantageous embodiment provides that one or both components of the plugs are realized identically by a valve seat body of the pressure-limiting valve, on which a valve seat of the pressure-limiting valve is formed, which valve seat interacts sealingly with a movable valve element of the pressure-limiting valve. This reduces the number of components that constitute the high-pressure fuel pump.

In the context of the present invention, a bore (in particular outlet valve opening, pressure limiting valve opening, low-pressure connection bore, high-pressure connection bore, etc.) is to be understood as meaning, in particular, an inner contour of a pump housing or pump body, which can be introduced into the pump housing or pump body by means of a rotary auger bit by cutting from the outside. The bore thus has, in particular, an axial symmetry, the axis of symmetry of which corresponds to the axis of rotation of the helical drill. The axis of symmetry illustrates the direction of the orientation of the holes. The bore can in principle be a through-bore through the pump housing or the pump body or a blind bore which ends at a bore bottom arranged in the pump housing or in the pump body. In the context of the present invention, the outlet of the bore is the side of the bore which is first formed by cutting when the bore is introduced into the pump housing or pump body. In the case of a blind hole, this side is always the side opposite the hole bottom. The mouth of the bore is thus the side of the bore opposite the bore outlet, if the bore there reaches on or emerges from another inner contour of the pump housing or pump body. The hole of the invention is free of undercuts (hinderschnitten), in particular when viewed from its outlet.

In the context of the present invention, in the case of a through hole, the hole wall is an inner contour formed by the through hole; in the case of a blind hole, the hole wall is the part of the inner contour formed by the through-hole, not the bottom of the hole.

In the context of the present invention, a high-pressure region is understood to be the entire space which communicates easily with the outlet, in particular without a further interposed valve, so that a uniform pressure, for example 500bar, occurs in the high-pressure region when the pump is in operation.

In the context of the present invention, a low-pressure region is understood to be an entire space which communicates easily with the inlet, in particular without further interposed valves, so that a uniform pressure prevails in the low-pressure region, for example 5bar when the pump is in operation and when the low-pressure pump is connected to the inlet.

In particular, the inner contour of the high-pressure fuel pump, through which the fuel flows, is formed in a closed manner by a low-pressure region, a delivery chamber and a high-pressure region. These zones are separated from each other by inlet, outlet and pressure limiting valves.

The fuel may be, for example, a fuel such as gasoline.

Within the scope of the present invention, the region set at an angle different from 0 ° may be an angle significantly different from 0 °, i.e. for example at least 2 ° or at least 5 °. For example, an angle between 2 ° and 90 °.

Drawings

Exemplary embodiments of the present invention are explained below with reference to the drawings.

FIG. 1: a simplified schematic of a fuel system for an internal combustion engine;

FIG. 2: a first embodiment of the present invention;

FIG. 3: exemplary detailed pressure limiting valves, as they may be used in various embodiments;

FIG. 4: a second embodiment of the present invention;

fig. 5 a) and 5 b): a third embodiment of the present invention;

FIG. 6: a fourth embodiment of the present invention;

FIG. 7: the fifth embodiment of the present invention;

FIG. 8: the sixth embodiment of the present invention.

Detailed Description

Fig. 1 shows a fuel system 1 for an internal combustion engine, not shown in detail, in a simplified schematic representation. In operation of the fuel system 1, fuel is supplied from a fuel tank 2 via a suction line 4 by means of a prefeed pump 6 and a low-pressure line 8 via an inlet connection 20 to a high-pressure fuel pump 10, which is embodied as a piston pump. An inlet valve 14 is fluidically connected downstream of the inlet connection 20. A low-pressure region 28 of high-pressure fuel pump 10 is situated fluidically between intake nipple 20 and intake valve 14. A delivery chamber 16 of the high-pressure fuel pump 10 is located downstream of the inlet valve 14. The pressure pulsations in the low-pressure region 28 can be damped by means of a pressure damping device. The inlet valve 14 can be opened forcibly by an actuating device, which is designed here as an electromagnetic actuator 30. The actuating device and thus the inlet valve 14 can be actuated by the control unit 32.

The pump pistons 18 of the high-pressure fuel pump 10 can be moved up and down by means of the drive 36, which is currently embodied as a cam disk, along a longitudinal axis (about which the pump pistons 18 are axially symmetrical) extending in the longitudinal direction LA, which is indicated in fig. 1 by a double arrow 40. An outlet valve 37 is arranged fluidically between the delivery chamber 16 and an outlet connection 35 of the high-pressure fuel pump 10, which outlet valve can be opened toward the outlet connection 35 and a high-pressure accumulator 45 ("rail") located further downstream. A high-pressure region 29 of the high-pressure fuel pump 10 thus extends fluidically between the outlet valve 37 and the outlet connection 35.

The high-pressure region 29 and the low-pressure region 28 are directly connected to one another by means of a pressure-limiting valve 22, which opens when a limit pressure is exceeded in the high-pressure region 29 of the high-pressure fuel pump 10 or in a high-pressure accumulator 45 communicating with this high-pressure region 29. The pressure-limiting valve 22 is designed as a spring-loaded non-return valve and can be opened toward a low-pressure region 28 of the high-pressure fuel pump 10. In this way, the pressure that can be generated in the high-pressure accumulator 45 by the high-pressure fuel pump 10 is limited.

Fig. 2 shows a cross-sectional view of a high-pressure fuel pump 10 as a first embodiment of the present invention.

The high-pressure fuel pump 10 has an inlet 11 in the form of an inlet connection 20. Without a connecting valve in between, the inlet 11 communicates with the entire low-pressure region 28 of the high-pressure fuel pump 10.

The high-pressure fuel pump 10 has an outlet 34 in the form of an outlet connection 35. Without a connecting valve in between, the outlet 34 communicates with the entire high-pressure region 29 of the high-pressure fuel pump 10.

The outlet connection 35 and the inlet connection 20 are fastened to a pump housing 12, in which a delivery chamber 16 is also arranged, which is delimited by a pump piston 18 that is movable in the longitudinal direction LA.

The low-pressure region 28 comprises a damping chamber 28a, which is connected to the inlet 11 via a fluid connection that is not visible in this cross section and is formed between the pump body 12a of the pump housing 12 and the pump cover 12b of the pump housing 12. In the damping chamber 28a diaphragm damper 55 is arranged, which may have the configuration of a flat and compressible tank formed by two metal diaphragms.

The invisible fluid connection between the inlet 11 and the damping chamber 28a may, for example, comprise a filter bore in which a filter element is arranged, which filter element removes entrained solid particles above a minimum size from the fuel flowing through the filter bore.

A seal carrier 60 is fixed to the lower section of the pump body 12a in fig. 2, and a step chamber 28d is formed between the pump body 12a and the seal carrier 60. The step chamber 28d communicates with the damping chamber 28a via a through-opening through the pump body 12a, which is not visible in this cross section, and is therefore part of the low-pressure region 28.

The delivery chamber 16 is delimited towards the low-pressure region 28 by an inlet valve 14, which inlet valve 14 opens towards the delivery chamber 16 with a corresponding pressure difference.

In order to control the delivery quantity of the high-pressure fuel pump 10, the inlet valve 14 can be forcibly opened by a tappet 31 driven by an actuator 30. For this purpose, the actuator 30 has an actuator housing 30a, which is fastened to the pump housing 12 and in which an electromagnetic coil 30b is arranged, which can be energized via an electrical connection 30c of the high-pressure fuel pump 10 that is accessible from the outside.

In the pump housing, an inlet valve region 28c of the low-pressure region 28 is geometrically formed between the inlet valve 14 and the actuator 30. The inlet valve region 28c communicates with the damping region 28a via a bore 28f visible in this cross section.

The delivery chamber 16 is delimited toward the high-pressure region 29 by an outlet valve 37, which opens away from the delivery chamber 16 with a corresponding pressure difference. In this example, the outlet valve 37 is arranged in an outlet valve opening 37a of the pump housing 12 or pump body 12 a. The outlet valve 37 has a movable valve element 37.1 which interacts with a sealing seat 37.4 which is formed on a sealing seat 37.2 which is arranged fixedly with the pump upstream of the valve element 37.1. The mobility of the valve element 37.1 in the downstream direction is limited by a counter plate 37.5 which is arranged fixedly with the pump. The outlet valve opening 37a originates from an outlet connection chamber 35a between the outlet connection 35 and the pump housing 12 or pump body 12 a.

The pump piston 18 is designed as a stepped piston. The pump piston 18 has a first section 18.1 pointing towards the delivery chamber 16 and having a larger diameter and a second section 18.2 pointing away from the delivery chamber and having a smaller diameter (relative to the diameter of the first section 18.1). An annular step 18.3, which is directed vertically downward in fig. 2, is formed between the first and second portions 18.1, 18.2.

Between the first section 18.1 and the pump housing 12, a high-pressure seal 80 is arranged, in which the pump piston 18 is movable. High pressure seal 80 sealingly separates transfer chamber 16 from low pressure region 28.

The high-pressure seal 80 may be, for example, a separate sealing ring, for example made of metal or plastic, as is further described, for example, in document WO 19 862 015 A1 of the applicant. The high-pressure seal can on the other hand also be a narrow gap extending over a certain length between the pump piston 18 and the sleeve or between the pump piston 18 and the pump housing 12, as is further described, for example, in the document WO 06069 819A1 of the applicant.

Between the second section 18.2 and the above-mentioned seal carrier 60, a low-pressure seal 78 is arranged, which separates a stepped chamber 28d of the low-pressure region 28 from a chamber 100, which chamber 100 is located outside the high-pressure fuel pump 10. The pump piston 18 is movable in a low pressure seal 78.

The pump piston 18 is prestressed in the longitudinal direction LA, which is oriented downward in fig. 2, by a spring disk 19.1 which is fastened to the pump piston 18 and a pump spring 19.2 which is clamped between the spring disk 19.1 and the seal carrier 60.

The high-pressure fuel pump 10 according to the invention has a pressure-limiting valve 22 which fluidically connects the high-pressure region 29 to the low-pressure region 28 and opens toward the low-pressure region 28, so that fuel flows out of the high-pressure region 29 into the low-pressure region 28 when the pressure difference between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure. The arrangement of the pressure-limiting valve 22 in the high-pressure fuel pump 10 according to the invention will now be further discussed by way of example.

In the context of the present invention, it is provided that the pressure-limiting valve 22 is fixed in a pressure-limiting valve opening 22a of the pump housing 12; and the outlet valve opening 37a and the pressure-limiting valve opening 22a extend in planes which are geometrically parallel relative to one another perpendicular to the longitudinal direction LA.

In the first embodiment according to fig. 2, both the outlet valve opening 37a and the pressure-limiting valve opening 22a are even oriented in a common plane, which is parallel to the longitudinal direction LA, i.e. in the drawing plane of fig. 2.

In the first embodiment according to fig. 2, the outlet valve opening 37a and the pressure-limiting valve opening 22a are even oriented geometrically parallel relative to one another, i.e. in the horizontal direction in fig. 2.

In the illustration according to fig. 2, the outlet valve opening 37a is arranged on the side of the pressure-limiting valve opening 22a facing away from the damping region 28 a. In this way, the length of the flow path and thus the flow resistance between the pressure-limiting valve 22 and the damping region 28a is minimized.

In addition, it is provided here, for example, that, in addition to the outlet valve opening 37a, a pressure-limiting valve opening 22a also extends from the outlet connection chamber 35a, and that the pressure-limiting valve opening 22a is connected to the damping region 28a via a low-pressure connection opening 28b, which is located in the low-pressure region 28 and is oriented in the longitudinal direction LA. The low-pressure connection bore 28b can be coaxial, for example, with the longitudinal axis of the high-pressure fuel pump 10 and/or with the axis of symmetry of the pump piston 18 and/or of the diaphragm damper 55.

The outlet connection 35 extends in particular transversely to the flow direction beyond the outlet of the pressure-limiting valve opening 22a and the outlet of the outlet valve opening 37a, so that the pressure-limiting valve opening 22a and the outlet valve opening 37a communicate with one another via an outlet connection chamber 35a arranged between the pump housing 12 and the outlet connection 35.

The (outer) diameter of the outlet connection 35, which is fixed to the pump housing 12 in this arrangement, is relatively large here, for example at least as large as the sum of the diameter of the pressure-limiting valve bore 22a (always: its maximum diameter in the case of a stepped bore) and the diameter of the outlet valve bore 37a (always: its maximum diameter in the case of a stepped bore), in particular even at least as large as 1.2 times this sum.

The cross-section of the pressure limiting valve bore 22a may be smaller than the cross-section of the outlet valve bore 37 a.

The cross section of the low pressure connection hole 28b may be smaller than the cross section of the pressure limiting valve hole 22a, for example, 5% to 35% of the cross section of the small pressure limiting valve hole 22 a.

The pressure-limiting valve opening 22a can be embodied as a blind hole into which the low-pressure connection opening 28b opens, i.e. preferably opens into the wall of the bore at a point spaced apart from the bore bottom of the pressure-limiting valve opening 22 a.

In this case, it can be provided that the axis of the pressure-limiting valve bore 22a intersects the axis of the low-pressure connection bore 28b, in particular at right angles, at an intersection point which is spaced apart from the bore bottom of the pressure-limiting valve bore 22a by at least a dimension which is given by 0.6 times the diameter of the low-pressure connection bore 28b, in particular by 0.75 times the diameter of the low-pressure connection bore 28 b. The coil spring 52 of the pressure-limiting valve 22 can then abut against the bottom of the pressure-limiting valve hole 22a without intersecting the mouth of the low-pressure connection hole 28 b.

The pressure-limiting valve 22 of fig. 2 (and at the same time the pressure-limiting valve 22 shown in fig. 4 to 8) is shown enlarged and schematically in fig. 3. The pressure relief valve has a valve seat body 38, which is pressed into the pressure relief valve opening 22a or into the housing of the pressure relief valve 22 and on which a conical valve seat 42 is formed. Furthermore, the pressure-limiting valve 22 has a valve element 44 which has the shape of a ball and bears sealingly against the valve seat 42. The valve element 44 is pressed in the closing direction by the holding element 46, and the holding element 46 is pressed in the closing direction by the coil spring 52. The coil spring 52 is supported on the housing of the pressure-limiting valve 22 or directly on the pump housing 12. The helical spring 52 bears against a radially outer region 464 of the retaining element 46. The radially inner region 465 of the retaining element 46 is received by the coil spring 52. The stiffness of the helical spring 52 and the surface area available on the pressure-limiting valve 22 define the opening pressure of the pressure-limiting valve 22 and thus at the same time the maximum pressure difference which the high-pressure fuel pump 10 can generate between its inlet 11 and its outlet 34.

Fig. 4 shows a second embodiment of the invention partially in a sectional view. The difference from the first embodiment is that only the outlet valve hole 37a, not the pressure limiting valve hole 22a, starts from the outlet nipple chamber 35 a. Instead, in this exemplary embodiment, it is provided that the pressure-limiting valve opening 22a is closed on the side of its outlet 22aa by means of a ball 56, which is pressed in particular into the pressure-limiting valve opening 22a, or a plug 57, which is pressed in particular into the pressure-limiting valve opening 22a, wherein the outlet valve opening 37a is connected to the pressure-limiting valve opening 22a via a high-pressure connection opening 29a in the high-pressure region 29.

In this case, it can be provided that the high-pressure connection opening 29a originates from the damping region 28a and is closed on its outlet side 29aa by means of a ball 56, in particular pressed into it, or a plug 57, in particular pressed into it.

The outlet connection 35 can be embodied smaller than in the first exemplary embodiment, for example, the (outer) diameter of the outlet connection 35, which is fixed to the pump housing 12 in this arrangement, can be less than the sum of the diameter of the pressure-limiting valve opening 22a and the diameter of the outlet valve opening 37a, in particular even less than 0.9 times the sum. In this way, the robustness of the attachment of outlet connection 35 to pump housing 12 is increased, since the hydraulic pressure acting on outlet connection 35 is proportional to the cross-sectional area covered by the outlet connection, and the length of the attachment of outlet connection 35 to pump housing 12 is only proportional to the extent of the cross-sectional area covered by the outlet connection, i.e. to the square root of the cross-sectional area covered by the outlet connection.

The relationship between the pressure-limiting valve hole 22a, the outlet valve hole 37a and the low-pressure connecting hole 28b and those described in relation to the first embodiment is also valid in this second embodiment.

The high-pressure connection opening 29a may have a cross section that is smaller than the respective cross sections of the pressure-limiting valve opening 22a, the outlet valve opening 37a and the low-pressure connection opening 28b, for example at most half as large.

The axis of the high-pressure connection bore 29a and the axis of the pressure-limiting valve bore 22a can intersect, in particular at right angles, wherein the intersection of these axes is preferably at a distance from the outlet of the pressure-limiting valve bore 22a of at least half the diameter, in particular the entire diameter, of the pressure-limiting valve bore 22 a; and/or the intersection of these axes is preferably spaced from the outlet of the high-pressure connection bore 29a by at least half the diameter, in particular the entire diameter, of the high-pressure connection bore 29 a. In this way, the pressure-limiting valve opening 22a and/or the high-pressure connection opening 29a can be closed particularly easily on its outlet side 29aa by means of a ball 56 pressed into it or by means of a plug 57 pressed into it.

Fig. 5 shows a perspective view of a semi-transparent pump body 12a of a high-pressure fuel pump 10 according to a third exemplary embodiment of the present invention in part a). The bores explained in detail below can be seen in the pump body interior at all. In part b), fig. 5 shows a sectional view of a third embodiment of the invention in part.

The third embodiment differs from the first two embodiments in that the outlet valve bore 37a and the pressure limiting valve bore 22a are not oriented geometrically parallel with respect to one another. Instead, the outlet valve bore 37a and the pressure-limiting valve bore 22a are oriented at an angle different from 0 ° relative to one another, for example at least 20 °.

Furthermore, in this example, it is provided that the outlet valve opening 37a is connected to the pressure-limiting valve opening 22a via two high-pressure connection openings 29a in the high-pressure region 29, wherein the first high-pressure connection opening 29a1 is closed off from the damping region 28a and on its outlet side 29a1a by means of a ball 56 or a plug 57 and opens into a second high-pressure connection opening 29a2 which opens into the outlet valve opening 37a itself.

The relationship between the pressure-limiting valve hole 22a, the outlet valve hole 37a and the low-pressure connecting hole 28b and these holes in the first embodiment is also valid in this third embodiment.

Both high-pressure connection bores 29a1, 29a2 can each have a cross section (in the case of stepped bores, the maximum diameter of the high-pressure connection bores) which is smaller than the respective cross sections of the pressure-limiting valve bore 22a, the outlet valve bore 37a and the low-pressure connection bore 28b, for example at most half as large.

The two high-pressure connection openings 29a1, 29a2 can be arranged at an angle to one another of at least 20 °, for example 90 °. Here, the first high-voltage connection hole 29a1 may be oriented parallel to the longitudinal direction LA.

The second high-pressure connection hole 29a2 may be arranged at an angle of at least 20 ° and, for example, at most 70 ° with respect to the outlet valve hole 37 a.

Fig. 6 shows a fourth embodiment of the present invention. This differs from the first embodiment explained with reference to fig. 2 and 3 in that the low-pressure connection holes 28b are not oriented in the longitudinal direction LA, but are oriented at an angle different from 0 °, for example at least 20 °, for example up to 60 °.

In this example, it can be provided that the pump body 12a has a recess 13 on the side facing the damping region 28a, and that the low-pressure connection opening 28b opens into the recess 13 or opens out of the recess 13 in such a way that the flow cross section of the recess 13 is wider than the flow cross section of the low-pressure connection opening 28b, for example at least twice as wide or at least three times as wide with respect to the flow cross section.

Fig. 7 shows a fifth embodiment of the present invention. This differs from the second exemplary embodiment explained with reference to fig. 3 and 4 in that the low-pressure connection opening 28b is not oriented in the longitudinal direction LA, but rather at an angle other than 0 °, for example at least 20 °, for example up to 60 °.

In this example, it can be provided that the pump body 12a has a recess 13 on the side facing the damping region 28a, and that the low-pressure connection opening 28b opens into the recess 13 or starts from the recess 13 in such a way that the flow cross section of the recess 13 is wider than the flow cross section of the low-pressure connection opening 28b, for example at least twice as wide or at least three times as wide with respect to the flow cross section.

In this example, it can be provided that the plug 57 which closes the pressure-limiting valve opening 22a and at the same time also closes the high-pressure connection opening 29a is the same component as the plug 57 which closes the high-pressure connection opening 29 a.

In particular, it can be provided that this component is also precisely part of the pressure limiting valve 22, for example the valve seat body 38 of the pressure limiting valve 22.

Fig. 8 shows a sixth embodiment of the present invention. The difference to the second exemplary embodiment of the invention described with reference to fig. 3 and 4 is that the pressure-limiting valve opening 22a is embodied as a stepped bore, which comprises a first section 22.1, which has a larger diameter and is directed toward the outlet 22aa of the pressure-limiting valve opening, i.e., to the left in fig. 8; and a second section 22.3 having a smaller diameter and pointing towards the low-pressure connection hole 28b, i.e. to the right in fig. 8; and an annular step 22.2 formed between the first section 22.1 and the second section 22.3, wherein the helical spring 52 is supported on the annular step 22.2.

The cross section of the first section 22.1 can be at least as large as twice the cross section of the second section 22.3, for example.

In this example, it may also be provided that the pump body 12a has a recess 13 on the side facing the damping region 28a, and that the low-pressure connection opening 28b opens into the recess 13 or opens out of the recess 13 in such a way that the flow cross section of the recess 13 is wider than the flow cross section of the low-pressure connection opening 28b, for example at least twice as wide or at least three times as wide as the flow cross section.

Claims

1. A high-pressure fuel pump (10) for a fuel system of an internal combustion engine, comprising:

an inlet (11) for supplying fuel;

an outlet (34) for outputting compressed fuel;

a pump housing (12);

a delivery chamber (16) disposed in the pump housing (12);

a pump piston (18) which is movable in the pump housing (12) along a longitudinal direction (LA) and delimits the delivery chamber (16);

an inlet valve (14) arranged between the inlet (11) and the delivery chamber (16), which inlet valve is open towards the delivery chamber (16);

an outlet valve (37) arranged between the delivery chamber (16) and the outlet (34), which outlet valve opens away from the delivery chamber (16);

a high pressure region (29) extending fluidly between the outlet valve (37) and the outlet (34);

a low pressure region (28) extending fluidly between the inlet (11) and the inlet valve (14); and

a pressure limiting valve (22) which fluidically connects the high-pressure region (29) to the low-pressure region (28) and which is open toward the low-pressure region (28) in such a way that fuel flows out of the high-pressure region (29) into the low-pressure region (28) when a pressure difference between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds an opening pressure, wherein the pump housing (12) comprises a pump body (12 a) and a pump cover (12 b) which are connected to one another, wherein a damping region (28 a) belonging to the low-pressure region (28) is delimited by the pump body (12 a) and the pump cover (12 b), in which damping region at least one diaphragm damper (55) is arranged, wherein the pressure limiting valve (22) fluidically connects the high-pressure region (29) to the damping region (28 a) and opens toward the damping region (28 a) in such a way that the fuel flows out of the high-pressure region (29) into the pressure limiting region (37) when a pressure difference between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds an opening pressure, wherein the pressure outlet (37 a) is fixed in the pump housing (12), wherein the pressure limiting valve (12) and wherein the outlet (37) is fixed in the pump housing (12) and wherein the damping region (12) fixed in the damping region (37), and wherein the outlet valve opening (37 a) and the pressure-limiting valve opening (22 a) extend in planes which are geometrically parallel relative to one another perpendicular to the longitudinal direction (LA).

2. The high-pressure fuel pump (10) according to claim 1, wherein the outlet valve bore (37 a) and the pressure-limiting valve bore (22 a) are oriented geometrically parallel with respect to one another.

3. The high-pressure fuel pump (10) according to claim 1, wherein the outlet valve bore (37 a) and the pressure-limiting valve bore (22 a) are oriented at an angle different from 0 ° to each other.

4. The high-pressure fuel pump (10) according to one of claims 1 to 3, wherein the outlet (34) is designed as an outlet connection piece (35) which is fixed to the pump housing (12) and an outlet connection chamber (35 a) is formed between the pump housing (12) and the outlet connection piece (35), wherein the outlet valve opening (37 a) and the pressure-limiting valve opening (22 a) both issue from the outlet connection chamber (35 a).

5. The high-pressure fuel pump (10) according to one of claims 1 to 3, wherein the outlet (34) is designed as an outlet port connector (35) which is fastened to the pump housing (12) and an outlet port chamber (35 a) is formed between the pump housing (12) and the outlet port connector (35), wherein the outlet valve opening (37 a) originates from the outlet port chamber (35 a) and the pressure-limiting valve opening (22 a) does not originate from the outlet port chamber (35 a), wherein the pressure-limiting valve opening (22 a) is closed at its outlet (22 aa) by means of a ball (56) or a plug (57), wherein the outlet valve opening (37 a) and the pressure-limiting valve opening (22 a) are connected via a high-pressure connecting opening (29 a) which is located in the high-pressure region (29).

6. The high-pressure fuel pump (10) as claimed in claim 5, wherein the high-pressure connection opening (29 a) originates from the damping region (28 a) and is closed off on its outlet side (29 aa) by means of a ball (56) or a plug (57).

7. The high-pressure fuel pump (10) according to claim 5, wherein the outlet valve opening (37 a) is connected to the pressure limiting valve opening (22 a) via two high-pressure connection openings (29 a) in the high-pressure region (29), wherein a first high-pressure connection opening (29 a 1) leads from the damping region (28 a) and is closed off on its outlet side (29 a1 a) by means of a ball (56) or a plug (57) and opens into a second high-pressure connection opening (29 a 2), wherein the second high-pressure connection opening opens into the outlet valve opening (37 a).

8. The high-pressure fuel pump (10) according to claim 5, wherein the pressure-limiting valve bore (22 a) is connected to the damping region (28 a) via a low-pressure connection bore (28 b) in the low-pressure region (28).

9. The fuel high-pressure pump (10) according to claim 8, wherein the low-pressure connecting hole (28 b) is oriented in a longitudinal direction (LA) or at an angle of 0 ° to 60 ° with respect to the longitudinal direction (LA).

10. The high-pressure fuel pump (10) according to claim 8 or 9, wherein the pump body (12 a) has a groove (13) on a side directed toward the damping region (28 a), wherein the low-pressure connection bore (28 b) opens into the groove (13) such that the cross section of the groove (13) is wider than the cross section of the low-pressure connection bore (28 b).

11. The high-pressure fuel pump (10) according to claim 8, wherein the pressure-limiting valve (22) has a valve seat body (38) which is pressed into the pressure-limiting valve bore (22 a) or into a housing of the pressure-limiting valve (22) and on which a conical valve seat (42) is formed, wherein the pressure-limiting valve (22) has a valve element (44) which has the shape of a ball and bears sealingly against the valve seat (42), wherein the valve element (44) is pressed by a retaining element (46) in a closing direction, wherein the retaining element (46) is pressed by a coil spring (52) in a closing direction, wherein the coil spring (52) is supported on the housing of the pressure-limiting valve (22) or on the pump housing (12), and wherein the coil spring (52) bears against a radially outer region (464) of the retaining element (46), wherein the coil spring (52) receives a radially inner region (465) of the retaining element (46).

12. The high-pressure fuel pump (10) as claimed in claim 11, wherein the valve seat body (38) simultaneously effects a plug (57) which closes the pressure-limiting valve bore (22 a) and/or simultaneously effects a plug (57) which closes the high-pressure connection bore (29 a).

13. The high-pressure fuel pump (10) according to claim 11 or 12, wherein the pressure-limiting valve bore (22 a) is embodied as a stepped bore, comprising:

a first section (22.1) having a larger diameter and pointing towards an outlet (22 aa) of the pressure-limiting valve bore; and

a second section (22.3) having a smaller diameter and pointing towards the low-pressure connection hole (28 b); and

an annular step (22.2) formed between the first section (22.1) and the second section (22.3), wherein the helical spring (52) is supported on the annular step (22.2).

14. The high-pressure fuel pump (10) according to claim 13, wherein the pump body (12 a) has a groove (13) on a side directed toward the damping region (28 a), wherein the low-pressure connection bore (28 b) opens into the groove (13) such that a flow cross section of the groove (13) is wider than a flow cross section of the low-pressure connection bore (28 b).