Fuel high-pressure pump

Abstract

A high pressure fuel pump (10), comprising a pressure limiting valve (22) fluidly connecting a high pressure region (29) to a low pressure region (28) and opening towards the low pressure region (28), the pressure limiting valve (22) being arranged in a pressure limiting valve bore (22a) formed as a through bore through a pump body (12b), the pressure limiting valve bore extending from a damping region (28a) to a stepped chamber (28d) and closed on the side facing the damping region (28a) by a pressed-in closing body (56, 57), the pressure limiting valve bore (22) being formed as a stepped bore and comprising a first section (22. 1. A high-pressure fuel pump (10), comprising a first section (22.1) and a second section (22.3) having a relatively small diameter, with a ring-shaped step (22.2) formed between the first section (22.1) and the second section (22.3), the pressure limiting valve (22) having a valve seat body (38) pressed into the pressure limiting valve bore (22), the pressure limiting valve (22) having a valve element (44), the valve element being pressed in a closing direction by a retaining element (46), the retaining element being pressed in a closing direction by a coil spring (52), the coil spring being supported on the ring-shaped step (22.2).

Description

Technical Field

[0001] Background Art According to the prior art, for example, based on the German Patent Application Publication No. 102018221702 of the applicant, there is a fuel high-pressure pump, which has an inlet for supplying fuel, an outlet for discharging the compressed fuel, a pump casing, a pumping chamber disposed in the pump casing, a pump piston that defines this pumping chamber and is slidable longitudinally in the pump casing, an inlet valve disposed between the inlet and the pumping chamber and opening towards the pumping chamber, an outlet valve disposed between the pumping chamber and the outlet and opening in a direction away from the pumping 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 that fluidly connects the high-pressure region to the low-pressure region and opens towards the low-pressure region to allow fuel to flow out from the high-pressure region to the low-pressure region when the differential pressure between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds the opening pressure. Such a fuel high-pressure pump is already known.

[0002] In the pump disclosed in the prior art described at the beginning, further, the pump piston is formed as a stepped piston and has a first section facing the pumping chamber and having a relatively large diameter and a second section having a relatively small diameter and directed in a direction away from the pumping chamber. A high-pressure seal that separates the pumping chamber from the low-pressure region is disposed between the first section and the pump casing. The pump piston is slidable within this high-pressure seal. A low-pressure seal that separates the low-pressure region from the space outside the fuel high-pressure pump is disposed between the second section and a seal support fixed to the pump casing. A stepped chamber of the low-pressure region is located between the seal support and the pump casing. The pressure limiting valve fluidly connects the high-pressure region to the stepped chamber of the low-pressure region and opens toward the stepped chamber when the differential pressure between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds the opening pressure, allowing the fuel to flow out from the high-pressure region to the stepped chamber. The pump casing has a pump body and a pump cover connected to each other. The pump body and the pump cover define a damping region belonging to the low-pressure region, and it is assumed that at least one diaphragm damper is disposed within the damping region.

[0003] In the pump disclosed in the prior art described at the beginning, further, the pressure limiting valve has a valve seat body press-fitted into the pressure limiting valve hole, and a conical valve seat is formed on the valve seat body. The pressure limiting valve has a valve element having the shape of a ball and closely abutting against the valve seat. The valve element is pushed in the closing direction by a holding element, and it is assumed that the holding element is pushed in the closing direction by a coil spring.

[0004] In the pump disclosed in the prior art described at the beginning, further, it is assumed that the pressure limiting valve is disposed within a pressure limiting valve hole formed as a blind hole of the pump body starting from the stepped chamber, and that the coil spring is supported by a separate portion press-fitted into the pressure limiting valve hole.

[0005] Disclosure of the Invention The present invention is based on the desire to configure a fuel high-pressure pump so that it can be manufactured simply and efficiently.

[0006] In this case, when the pressure limiting valve hole is realized as a blind hole in the pump body starting from the stepped chamber, as a drawback, a separate flow-through portion for supporting the coil spring is required, and this separate portion has to be press-fitted into the pressure limiting valve hole in a separate assembly step during the assembly of the pressure limiting valve. In this case, it has been clarified that the closing force acting on the valve element or valve seat in the coil spring defines the opening pressure of the pressure limiting valve, that is, this closing force must be accurately adjustable.

[0007] In contrast, the solution according to the present invention is that the pressure limiting valve is arranged in a pressure limiting valve hole formed as a through hole penetrating the pump body, the pressure limiting valve hole extends from the damping region to the stepped chamber, and on the side facing the damping region, it is closed by a ball press-fitted into the pressure limiting valve hole or a plug press-fitted into the pressure limiting valve hole. The pressure limiting valve hole is formed as a stepped hole and has a first section with a relatively large diameter facing the damping region and a second section with a relatively small diameter facing the stepped chamber, and has a ring-shaped step formed between the first section and the second section, and a coil spring is supported on this ring-shaped step, which is different from the known solutions.

[0008] The pressure limiting valve of the pump according to the present invention can be assembled in a simple and efficient manner, preferably together with the coil spring from the side of the pump casing facing the damping chamber, so that the coil spring abuts against the ring-shaped step. After the pressure limiting valve is assembled in the pressure limiting valve hole, the pressure limiting valve hole can be easily closed on the side facing the damping region by press-fitting the ball or the plug.

[0009] In a further configuration, the outlet valve is arranged within the outlet valve bore of the pump casing, and it is assumed that the outlet valve bore and the pressure limiting valve bore intersect, particularly at a right angle. Thereby, the pressure limiting valve is incorporated into the high-pressure region in a form that reduces the structural space without other high-pressure seal locations.

[0010] Particularly for reducing the structural space, the outlet valve has a movable valve element and a seal seat arranged upstream of the valve element. The seal seat is attached to the pump fixture in the seal seat fixing section, and a seal seat that cooperates with the valve element is formed on the seal seat. The outlet valve has a corresponding plate of the pump fixture arranged downstream of the valve element, and the corresponding plate is attached to the pump fixture in the corresponding plate fixing section, restricting the movability of the valve element in the downstream direction. It may be assumed that the pressure limiting valve bore intersects the outlet valve bore between the seal seat fixing section and the corresponding plate fixing section. In this case, since the pressure limiting valve bore intersects the space where the components belonging to the outlet valve are assembled, this space is utilized, so to speak, doubly.

[0011] Furthermore, it may be assumed that an outlet pipe section chamber is formed between the pump casing and the outlet pipe section. The outlet pipe section chamber may, on the one hand, consist of or include the portion of the inner chamber of the pipe section facing the pump casing. The outlet pipe section chamber may additionally include a recess within the pump body covered by the outlet pipe section, particularly consisting of these two partial chambers. Alternatively, the outlet pipe section chamber may consist of a recess within the pump body covered by the outlet pipe section.

[0012] The outlet is formed as an outlet pipe piece fixed to the pump casing, and an outlet pipe piece chamber is formed between the pump casing and the outlet pipe piece. The outlet valve is fixed to the outlet valve hole of the pump casing. The outlet valve hole starts from the outlet pipe piece chamber, and the pressure limiting valve hole is assumed to be connected to the outlet pipe piece chamber via a high-pressure connection hole located in the high-pressure region starting from the outlet pipe piece chamber. In this case, compared with the above-described solution means, the flexibility of the arrangement of the pressure limiting valve hole in the pump body is increased.

[0013] If the outlet valve hole and the high-pressure connection hole are arranged parallel to each other and, for example, perpendicular to the longitudinal direction, these holes can be easily manufactured, for example, with the same tool or together.

[0014] If the outlet valve hole and the high-pressure connection hole are arranged at an angle other than 0° to each other and, for example, perpendicular to the longitudinal direction respectively, the structural space available for the inner contour in the pump body can be optimally utilized, or potentially the pump body can be further miniaturized.

[0015] It can always be assumed that the virtual (optionally extended) central axis of the outlet valve hole intersects the virtual (optionally extended) central axis of the pump piston, i.e., the longitudinal axis. In this case, the outflow of fuel from the pumping chamber through the outlet valve is possible without further redirection and thus particularly with low friction.

[0016] On the other hand, the case where the virtual (optionally extended) central axis of the outlet valve hole does not intersect the virtual (optionally extended) central axis of the pump piston, i.e., the longitudinal axis, can also be advantageous for the reason of optimal utilization of the structural space provided in the pump body.

[0017] In this case, a first further object claimed in parallel is a fuel high-pressure pump for a fuel system of an internal combustion engine, having an inlet for supplying fuel, an outlet for discharging compressed fuel, a pump casing, a pumping chamber arranged in the pump casing, a pump piston defining the pumping chamber and slidable longitudinally in the pump casing, an inlet valve arranged between the inlet and the pumping chamber and opening towards the pumping chamber, an outlet valve arranged between the pumping chamber and the outlet and opening in a direction away from the pumping 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 that fluidly connects the high-pressure region to the low-pressure region and opens towards the low-pressure region to allow fuel to flow out from the high-pressure region to the low-pressure region when the differential pressure between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds the opening pressure. The pump piston is formed as a stepped piston and has a first section facing the pumping chamber and having a relatively large diameter, and a second section having a relatively small diameter and directed away from the pumping chamber. A high-pressure seal separating the pumping chamber from the low-pressure region is arranged between the first section and the pump casing, and the pump piston is slidable within this high-pressure seal. A low-pressure seal separating the low-pressure region from the space outside the fuel high-pressure pump is arranged between the second section and a seal support fixed to the pump casing. A stepped chamber of the low-pressure region is located between the seal support and the pump casing. The pressure-limiting valve fluidly connects the high-pressure region to the stepped chamber of the low-pressure region and opens towards the stepped chamber to allow fuel to flow out from the high-pressure region to the stepped chamber when the differential pressure between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds the opening pressure. The outlet valve is arranged in an outlet valve hole of the pump casing, has a movable valve element, and has a seal seat arranged upstream of the valve element. The seal seat is attached to the pump fixing in a seal seat fixing section, and a seal seat cooperating with the valve element is formed on the seal seat. The outlet valve has a corresponding plate of the pump fixing arranged downstream of the valve element, and the corresponding plate is attached to the pump fixing in a corresponding plate fixing section and limits the movability of the valve element in the downstream direction. The pressure-limiting valve is arranged in a pressure-limiting valve hole in the pump casing.This pressure limiting valve hole is assumed to be a fuel high-pressure pump that extends in the longitudinal direction and opens from the stepped chamber to the outlet valve hole, that is, between the seal seat fixing section and the corresponding plate fixing section.

[0018] Compared with the prior art cited at the beginning, in particular, due to the arrangement in which the pressure limiting valve hole opens into the outlet valve hole between the seal seat fixing section and the corresponding plate fixing section, there is an advantage that the pressure limiting valve can be incorporated into the high-pressure region in a form that reduces the construction space without other high-pressure seal points. The space where the components belonging to the outlet valve are assembled is at the same time the opening area of the pressure limiting valve hole, and thus this space is utilized, so to speak, doubly.

[0019] The first further object can advantageously be improved, that is, preferably by the features of dependent claims 2, 3, 7 and / or 8 and / or by the features disclosed in the description relating to FIG. 6 and / or FIG. 6.

[0020] In this case, a second further object claimed in parallel is a fuel high-pressure pump for a fuel system of an internal combustion engine, having an inlet for supplying fuel, an outlet for discharging compressed fuel, a pump casing, a pumping chamber arranged within the pump casing, a pump piston defining the pumping chamber and slidable longitudinally within the pump casing, an inlet valve arranged between the inlet and the pumping chamber and opening towards the pumping chamber, an outlet valve arranged between the pumping chamber and the outlet and opening in a direction away from the pumping chamber, a high-pressure region fluidically extending between the outlet valve and the outlet, a low-pressure region fluidically extending between the inlet and the inlet valve, and a pressure-limiting valve that fluidically connects the high-pressure region to the low-pressure region and opens towards the low-pressure region to allow fuel to flow out of the high-pressure region into the low-pressure region when the differential pressure between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds the opening pressure. The pump piston is formed as a stepped piston and has a first section facing the pumping chamber and having a relatively large diameter, and a second section having a relatively small diameter and directed in a direction away from the pumping chamber. A high-pressure seal separating the pumping chamber from the low-pressure region is arranged between the first section and the pump casing, and the pump piston is slidable within this high-pressure seal. A low-pressure seal separating the low-pressure region from the space outside the fuel high-pressure pump is arranged between the second section and a seal support fixed to the pump casing. A stepped chamber of the low-pressure region is located between the seal support and the pump casing. The pressure-limiting valve fluidically connects the high-pressure region to the stepped chamber of the low-pressure region and opens towards the stepped chamber to allow fuel to flow out of the high-pressure region into the stepped chamber when the differential pressure between the fuel in the high-pressure region and the fuel in the low-pressure region exceeds the opening pressure. The outlet valve is arranged within an outlet valve bore of the pump casing, the pressure-limiting valve is arranged within a pressure-limiting valve bore in the pump casing, the pressure-limiting valve bore extends longitudinally and opens into a high-pressure connection bore within the pump casing starting from the stepped chamber, the high-pressure connection bore is arranged in the high-pressure region, and is oriented at an angle other than 0° with respect to the outlet valve bore. In particular, the outlet is formed as an outlet pipe piece fixed to the pump casing, and in particular an outlet pipe piece chamber is formed between the pump casing and the outlet pipe piece. In particular, both the outlet valve bore and the high-pressure connection bore originate from the outlet pipe piece chamber.A fuel high-pressure pump is assumed.

[0021] Compared with the prior art cited at the beginning, in particular, due to the arrangement in which the high-pressure connection hole is oriented at an angle other than 0° with respect to the outlet valve hole, it is achieved that the structural space available for the inner contour within the pump body can be optimally utilized, or potentially the pump body can be further miniaturized.

[0022] A second further object can advantageously be improved, i.e., preferably, due to the feature that both the outlet valve hole and the high-pressure connection hole originate from the outlet pipe segment chamber, it can be improved. These holes can in this case be easily manufactured, for example, with the same tool.

[0023] A second further object can furthermore be advantageously improved by the features of claim 7 or 8 and / or by the features disclosed in FIG. 7 and / or the description related to FIG. 7.

[0024] Within the scope of the present invention, holes (in particular, outlet valve holes, pressure limiting valve holes, low-pressure connection holes, high-pressure connection holes, etc.) are understood to be the inner contours of the pump casing or the pump body that can be machined from the outside by cutting, particularly by a rotating spiral drill, into the pump casing or the pump body. Thus, the holes particularly have axial symmetry, and the axis of symmetry corresponds to the axis of rotation of the spiral drill. This axis of symmetry defines, in this case, the direction in which the hole is oriented. In this case, the hole may basically be a through-hole penetrating the pump casing or the pump body, or a blind hole terminating at a hole bottom arranged within the pump casing or the pump body. The starting point of the hole is, within the scope of the present invention, the side of the hole that is first formed by cutting when the drill enters the pump casing or the pump body. In the case of a blind hole, the starting point of the hole is always on the side opposite to the hole bottom. Thus, when the hole reaches another inner contour of the pump casing or the pump body or exits the pump casing or the pump body, the opening of the hole is on the side opposite to the starting point of the hole. The holes of the present invention particularly do not have an undercut when viewed from their starting point.

[0025] Within the scope of the present invention, in the case of a through-hole, the hole wall is the 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 that is not the hole bottom.

[0026] Within the scope of the present invention, the high-pressure region particularly means all spaces that communicate directly with the outlet without any other intervening valve, whereby a uniform pressure of, for example, 500 bar occurs in the high-pressure region during pump operation.

[0027] Within the scope of the present invention, the low-pressure region particularly means all spaces that communicate directly with the inlet without any other intervening valve, whereby a uniform pressure of, for example, 5 bar occurs in the low-pressure region during pump operation when a low-pressure pump is connected to the inlet.

[0028] In particular, the inner contour of the fuel high-pressure pump through which fuel flows ultimately consists of a low-pressure region, a pumping chamber, and a high-pressure region. These regions are separated from each other by an inlet valve, an outlet valve, and a pressure limiting valve.

[0029] The fuel may be a fuel such as gasoline, for example.

[0030] Within the scope of the present invention, when adjusted to an angle other than 0°, this angle may be an angle clearly different from 0°, that is, for example, an angle of at least 2° or at least 5°. For example, this angle may be an angle between 2° and 90°.

[0031] Exemplary embodiments of the present invention will be described below with reference to the drawings.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4a

Figure 4b

Figure 5a

Figure 5b

Figure 6

Figure 7a

Figure 7b

[0033] Figure 1 shows a simplified schematic view of a fuel system 1 for an internal combustion engine, with other parts not shown. During operation of the fuel system 1, fuel is supplied from the fuel tank 2 via the suction line 4, through the feed pump 6 and the low-pressure line 8, to the inlet pipe section 20 of the fuel high-pressure pump 10 formed as a piston pump. Fluidically following the inlet pipe section 20, an inlet valve 14 is arranged. Between the inlet pipe section 20 and the inlet valve 14 fluidically, there is a low-pressure region 28 of the fuel high-pressure pump 10. Downstream of the inlet valve 14, there is a pumping chamber 16 of the fuel high-pressure pump 10. The pressure pulsations in the low-pressure region 28 can be attenuated by a pressure attenuation device. The inlet valve 14 can in this case be forced to open via an operating device formed as an electromagnetic actuator 30. The operating device, and thus the inlet valve 14, can be controlled via a control unit 32.

[0034] The pump piston 18 of the fuel high-pressure pump 10 can in this case move up and down along the longitudinal axis forming the axis of symmetry of the pump piston 18, which extends in the longitudinal direction LA, as indicated by the double arrow 40 in Figure 1, by means of a drive device 36 formed as a cam disk. Fluidically between the pumping chamber 16 of the fuel high-pressure pump 10 and the outlet pipe section 35, there is an outlet valve 37 arranged which can open towards the outlet pipe section 35 and further downstream towards a high-pressure accumulator 45 ("rail"). Thus, fluidically between the outlet valve 37 and the outlet pipe section 35, there is a high-pressure region 29 of the fuel high-pressure pump 10 extending.

[0035] The high-pressure region 29 and the low-pressure region 28 are directly connected to each other via a pressure limiting valve 22 which opens when the boundary pressure in the high-pressure region 29 of the fuel high-pressure pump 10 or in the high-pressure accumulator 45 communicating with the high-pressure region is exceeded. The pressure limiting valve 22 is formed as a spring-loaded check valve and can open towards the low-pressure region 28 of the fuel high-pressure pump 10. In this way, the pressure that can be generated in the high-pressure accumulator 45 by the fuel high-pressure pump 10 is limited.

[0036] FIG. 2 is a cross-sectional view showing a fuel high-pressure pump 10 as a first embodiment of the present invention.

[0037] The fuel high-pressure pump 10 has an inlet 11 formed as an inlet pipe piece 20. The inlet 11 communicates with the entire low-pressure region 28 of the fuel high-pressure pump 10 without interposing a valve.

[0038] The fuel high-pressure pump 10 has an outlet 34 formed as an outlet pipe piece 35. The outlet 34 communicates with the entire high-pressure region 29 of the fuel high-pressure pump 10 without interposing a valve.

[0039] The outlet pipe piece 35 and the inlet pipe piece 20 are fixed to the pump casing 12, and a pumping chamber 16 defined by a pump piston 18 slidable along the longitudinal direction LA is also arranged in the pump casing.

[0040] The low-pressure region 28 includes a damping chamber 28a connected to the inlet 11 via a fluid connection part not visible in this cross-sectional view. This damping chamber is formed between the pump main body 12a of the pump casing 12 and the pump cover 12b of the pump casing 12. A diaphragm damper 55 is arranged in the damping chamber 28a, and the diaphragm damper may have a flat and compressible can shape formed by two metal diaphragms.

[0041] The invisible fluid connection part between the inlet 11 and the damping chamber 28a may have, for example, filter holes, and a filter element for removing entrained solid particles larger than the minimum size is arranged in the filter holes from the fuel flowing through the filter holes.

[0042] In the lower section of the pump main body 12a in FIG. 2, a seal support 60 is attached, and a stepped chamber 28d is formed between the pump main body 12a and the seal support 60. The stepped chamber 28d communicates with the damping chamber 28a through a through hole not visible in this cross-sectional view and penetrating the pump main body 12a. Therefore, the stepped chamber is a part of the low-pressure region 28.

[0043] The pressure chamber 16 is defined with respect to the low-pressure region 28 by an inlet valve 14 that opens toward the pressure chamber 16 under a corresponding differential pressure.

[0044] To control the delivery volume of the fuel high-pressure pump 10, the inlet valve 14 can be forcibly opened by a plunger 31 driven by an actuator 30. For this purpose, the actuator 30 has an actuator casing 30a fixed to the pump casing 12, in which an electromagnetic coil 30b is disposed, and power can be supplied to this electromagnetic coil via an electrical terminal 30c of the fuel high-pressure pump 10 that is accessible from the outside.

[0045] In the pump casing, 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 communicates with the attenuation region 28a via a hole 28f visible in this cross-sectional view.

[0046] The pressure chamber 16 is defined with respect to the high-pressure region 29 by an outlet valve 37 that opens away from the pressure chamber 16 under a corresponding differential pressure. In this example, the outlet valve is disposed in an outlet valve hole 37a of the pump casing 12 or the pump body 12a. The outlet valve has a movable valve element 37.1, which cooperates with a seal seat 37.4 formed on a seal seat portion 37.2 disposed for pump fixing upstream of the valve element 37.1. The movability of the valve element 37.1 is restricted in the downstream direction via a corresponding plate 37.5 disposed for pump fixing. The outlet valve hole 37a starts from an outlet pipe piece chamber 35a located between the outlet pipe piece 35 and the pump casing 12 or the pump body 12a.

[0047] The pump piston 18 is formed as a stepped piston. The pump piston has a first section 18.1 facing the pumping chamber 16, which has a relatively large diameter, and a second section 18.2 facing away from the pumping chamber and having a relatively small diameter (relative to the diameter of the first section 18.1). Between the first section 18.1 and the second section 18.2, a ring-shaped step 18.3 directed vertically downward in Figure 2 is formed.

[0048] A high-pressure seal 80 is arranged between the first section 18.1 and the pump casing 12, and within this high-pressure seal, the pump piston 18 is slidable. The high-pressure seal 80 seals and separates the pumping chamber 16 from the low-pressure region 28.

[0049] The high-pressure seal 80 may be, for example, a separate seal ring made of, for example, metal or plastic, as described in detail in the applicant's International Publication No. 19015862. On the other hand, the high-pressure seal 80 may be, for example, a narrow gap extending over a predetermined length between the pump piston 18 and the bush, or between the pump piston 18 and the pump casing 12, as described in detail in the applicant's International Publication No. 06069819.

[0050] A low-pressure seal 78 that separates the stepped chamber 28d of the low-pressure region 28 from the space 100 located outside the fuel high-pressure pump 10 is arranged between the second section 18.2 and the seal support 60 already described above. The pump piston 18 is slidable within the low-pressure seal 78.

[0051] The pump piston 18 is preloaded in the longitudinal direction LA directed downward in Figure 2 via a spring receiver 19.1 fixed to the pump piston 18 and a pump spring 19.2 clamped between the spring receiver 19.1 and the seal support 60.

[0052] The fuel high-pressure pump 10 according to the present invention has a pressure limiting valve 22 that fluidly connects the high-pressure region 29 to the low-pressure region 28 and opens toward the low-pressure region 28 when the differential pressure between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure, allowing fuel to flow out from the high-pressure region 29 to the low-pressure region 28.

[0053] In FIG. 3, the pressure limiting valve is illustrated in detail. This pressure limiting valve has a valve seat body 38 press-fitted into the pressure limiting valve hole 22a or into the casing of the pressure limiting valve 22, and a conical valve seat 42 is formed on this valve seat body. The pressure limiting valve 22 further has a valve element 44 having the shape of a ball, and this valve element abuts tightly against the valve seat 42. The valve element 44 is pushed in the closing direction by a holding element 46, and the holding element 46 is pushed in the closing direction by a coil spring 52. The coil spring 52 is supported directly on the casing of the pressure limiting valve 22 or on the pump casing 12. In this case, the coil spring 52 abuts against the radially outer region 464 of the holding element 46. The radially inner region 465 of the holding element 46 is accommodated by the coil spring 52. The opening pressure of the pressure limiting valve 22 is defined via the stiffness of the coil spring 52 and via the area acting on the pressure limiting valve 22, and thus, simultaneously, the maximum differential pressure that the fuel high-pressure pump 10 can generate between the inlet 11 and the outlet 34 is defined.

[0054] The arrangement of the pressure limiting valve 22 in the fuel high-pressure pump 10 according to the present invention will be further illustratively described below.

[0055] In this case, within the scope of the present invention (independent claim 1), when the differential pressure between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure, the pressure limiting valve 22 fluidly connects the high-pressure region 29 to the stepped chamber 28d of the low-pressure region 28 and opens towards the stepped chamber 28d to allow the fuel to flow out from the high-pressure region 29 to the stepped chamber 28d. And this pressure limiting valve 22 is arranged in a pressure limiting valve hole 22a formed as a through hole penetrating the pump body 12b. The pressure limiting valve hole 22a extends from the damping region 28a to the stepped chamber 28d. On the side facing the damping region 28a, it is closed by a ball 56 press-fitted into the pressure limiting valve hole 22a or a plug body 57 press-fitted into the pressure limiting valve hole 22a. The pressure limiting valve hole 22a is formed as a stepped hole and has a first section 22.1 with a relatively large diameter facing the damping region 28a and a second section 22.3 with a relatively small diameter facing the stepped chamber 28d, and has a ring-shaped step portion 22.2 formed between the first section 22.1 and the second section 22.3. It is assumed that the above-described coil spring 52 of the pressure limiting valve 22 is supported by the ring-shaped step portion 22.2 of the pressure limiting valve hole 22a.

[0056] According to the first embodiment of the present invention (Figs. 2 and 3), further, it is assumed that the outlet valve hole 37a and the pressure limiting valve hole 22a intersect particularly at a right angle. In this case, the intersection is performed inside the high-pressure region 29 in this example.

[0057] More specifically, according to the first embodiment of the present invention, this intersection is such that the seal seat portion 37.2 is attached to the pump fixing at the seal seat fixing section 37.3, the corresponding plate 37.5 is attached to the pump fixing at the corresponding plate fixing section 37.6, and the pressure limiting valve hole 22a intersects the outlet valve hole 37a between the seal seat fixing section 37.3 and the corresponding plate fixing section 37.6.

[0058] For example, it is assumed that the virtual central axis of the outlet valve hole 37a intersects the virtual central axis of the pump piston 18, and thus the longitudinal axis of the gasoline high-pressure pump.

[0059] Figure 4 shows a second embodiment of the present invention, partially in a sectional view in Figure 4a and in a plan view of the pump body 12a shown in a semi-transparent view in Figure 4b. The second embodiment is different from the first embodiment in that it is not assumed that the outlet valve hole 37a and the pressure limiting valve hole 22a intersect. Instead, in the second embodiment, it is assumed that the pressure limiting valve hole 22a is connected to the outlet pipe section chamber 35a via a high-pressure connection hole 29a starting from the outlet pipe section chamber 35a, which is located in the high-pressure region 29.

[0060] In this case, the outlet valve hole 37a and the high-pressure connection hole 29a are arranged at an angle other than 0° with respect to each other, in particular at an angle of at least 20°, and are each arranged perpendicular to the longitudinal direction LA.

[0061] The virtual central axis of the outlet valve hole 37a, in particular, intersects the virtual central axis of the pump piston 18.

[0062] Figure 5 shows a third embodiment of the present invention, partially in a sectional view in Figure 5a and in a plan view of the pump body 12a shown in a semi-transparent view in Figure 5b. The third embodiment is different from the second embodiment in that the outlet valve hole 37a and the high-pressure connection hole 29a are arranged parallel to each other.

[0063] For example, both of these holes 22a, 37a are arranged perpendicular to the longitudinal direction LA. The virtual central axis of the outlet valve hole 37a does not intersect or necessarily intersect the virtual central axis of the pump piston 18.

[0064] The fourth embodiment of the present invention is formed by the first parallel independent claim and is shown in the cross-sectional view of FIG. 6. This embodiment is a fuel high-pressure pump 10 for a fuel system of an internal combustion engine, having an inlet 11 for supplying fuel, an outlet 34 for discharging the compressed fuel, a pump casing 12, a pumping chamber 16 disposed within the pump casing, a pump piston 18 defining the pumping chamber and slidable along the longitudinal direction LA within the pump casing 12, an inlet valve 14 disposed between the inlet 11 and the pumping chamber 16 and opening towards the pumping chamber 16, an outlet valve 37 disposed between the pumping chamber 16 and the outlet 34 and opening in a direction away from the pumping chamber 16, a high-pressure region 29 fluidly extending between the outlet valve 20 and the outlet 34, a low-pressure region 28 fluidly extending between the inlet 11 and the inlet valve 14, and a pressure-limiting valve 22 that fluidly connects the high-pressure region 29 to the low-pressure region 28 and opens towards the low-pressure region 28 to allow fuel to flow out from the high-pressure region 29 to the low-pressure region 28 when the differential pressure between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure. The pump piston 18 is formed as a stepped piston and has a first section 18.1 facing the pumping chamber 16 and having a relatively large diameter, and a second section 18.2 having a relatively small diameter and directed in a direction away from the pumping chamber 16. A high-pressure seal 80 that separates the pumping chamber 16 from the low-pressure region 28 is disposed between the first section 18.1 and the pump casing 12, and the pump piston 18 is slidable within this high-pressure seal. A low-pressure seal 78 that separates the low-pressure region 28 from the space 100 outside the fuel high-pressure pump 10 is disposed between the second section 18.2 and a seal support 60 fixed to the pump casing 12. A stepped chamber 28d of the low-pressure region 28 is located between the seal support 60 and the pump casing 12. The pressure-limiting valve 22 fluidly connects the high-pressure region 29 to the stepped chamber 28d of the low-pressure region and opens towards the stepped chamber 28d to allow fuel to flow out from the high-pressure region 29 to the stepped chamber 28d when the differential pressure between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure. The outlet valve 37 is disposed within an outlet valve hole 37a of the pump casing 12, has a movable valve element 37.1, and has a seal seat 37.2 disposed upstream of the valve element 37.1. The seal seat is a seal seat fixing section 37.It is attached to the pump fixing at 3, and a seal seat 37.4 that cooperates with the valve element 37.1 is formed on the seal seat portion. The outlet valve 37 has a corresponding plate 37.5 of the pump fixing arranged downstream of the valve element 37.1. The corresponding plate is attached to the pump fixing at the corresponding plate fixing section 37.5 and restricts the mobility of the valve element 37.1 in the downstream direction. The pressure limiting valve 37 is arranged in the pressure limiting valve hole 37 in the pump casing 12. This pressure limiting valve hole extends in the longitudinal direction LA and opens into the outlet valve hole 22a starting from the stepped chamber 28d, that is, between the seal seat portion fixing section 37.3 and the corresponding plate fixing section 37.6. It is a fuel high-pressure pump.

[0065] A fifth embodiment of the present invention is formed by a second parallel independent claim and is shown in a sectional view partially in FIG. 7a and in a plan view of the pump body 12a shown in a semi-transparent view in FIG. 7b. This embodiment is a fuel high-pressure pump 10 for a fuel system for an internal combustion engine, having an inlet 11 for supplying fuel, an outlet 34 for discharging the compressed fuel, a pump casing 12, a pumping chamber 16 disposed within the pump casing, a pump piston 18 defining the pumping chamber and slidable along the longitudinal direction LA within the pump casing 12, an inlet valve 14 disposed between the inlet 11 and the pumping chamber 16 and opening toward the pumping chamber 16, an outlet valve 37 disposed between the pumping chamber 16 and the outlet 34 and opening in a direction away from the pumping chamber 16, a high-pressure region 29 fluidly extending between the outlet valve 20 and the outlet 34, a low-pressure region 28 fluidly extending between the inlet 11 and the inlet valve 14, and a pressure-limiting valve 22 that fluidly connects the high-pressure region 29 to the low-pressure region 28 and opens toward the low-pressure region 28 to allow fuel to flow out from the high-pressure region 29 to the low-pressure region 28 when the differential pressure between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure. The pump piston 18 is formed as a stepped piston and has a first section 18.1 facing the pumping chamber 16 and having a relatively large diameter and a second section 18.2 having a relatively small diameter and directed in a direction away from the pumping chamber 16. A high-pressure seal 80 separating the pumping chamber 16 from the low-pressure region 28 is disposed between the first section 18.1 and the pump casing 12, and the pump piston 18 is slidable within this high-pressure seal. The second section 18.Between 2 and the seal support 60 fixed to the pump casing 12, a low-pressure seal 78 that separates the low-pressure region 28 from the space 100 outside the fuel high-pressure pump 10 is arranged. Between the seal support 60 and the pump casing 12, the stepped chamber 28d of the low-pressure region 28 is located. When the differential pressure between the fuel in the high-pressure region 29 and the fuel in the low-pressure region 28 exceeds the opening pressure, the pressure-limiting valve 22 fluidly connects the high-pressure region 29 to the stepped chamber 28d of the low-pressure region and opens toward the stepped chamber 28d, allowing the fuel to flow out from the high-pressure region 29 to the stepped chamber 28d. The outlet valve 37 is arranged in the outlet valve hole 37a of the pump casing 12, and the pressure-limiting valve 22 is arranged in the pressure-limiting valve hole 22a in the pump casing 12. This pressure-limiting valve hole extends in the longitudinal direction LA and opens to the high-pressure connection hole 29a in the pump casing 12 starting from the stepped chamber 28d. The high-pressure connection hole is arranged in the high-pressure region 29 and is oriented at an angle other than 0°, for example, an angle of 5° to 15° with respect to the outlet valve hole 37a. In particular, the outlet 34 is formed as an outlet pipe piece 35 fixed to the pump casing 12. In particular, an outlet pipe piece chamber 35a is formed between the pump casing 12 and the outlet pipe piece 35. In particular, both the outlet valve hole 37a and the high-pressure connection hole 29a start from the outlet pipe piece chamber 35a. It is a fuel high-pressure pump.

Claims

Claim 1 A fuel high-pressure pump (10) for a fuel system of an internal combustion engine, comprising: An inlet (11) for supplying fuel; An outlet (34) for discharging compressed fuel; A pump casing (12); A pumping chamber (16) disposed within the pump casing (12); A pump piston (18) defining the pumping chamber (16) and slidable along a longitudinal direction (LA) within the pump casing (12); An inlet valve (14) disposed between the inlet (11) and the pumping chamber (16) and opening towards the pumping chamber (16); An outlet valve (37) disposed between the pumping chamber (16) and the outlet (34) and opening in a direction away from the pumping chamber (16); A high-pressure region (29) fluidly extending between the outlet valve (37) and the outlet (34); A low-pressure region (28) fluidly extending between the inlet (11) and the inlet valve (14); A pressure-limiting valve (22) fluidly connecting the high-pressure region (29) to the low-pressure region (28) and opening towards the low-pressure region (28) to allow fuel to flow from the high-pressure region (29) to the low-pressure region (28) when a differential pressure between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds an opening pressure; The pump piston (18) is formed as a stepped piston and has a first section (18.1) facing the pumping chamber (16) and having a relatively large diameter, and a second section (18.2) having a relatively small diameter and directed away from the pumping chamber (16); A high-pressure seal (80) separating the pumping chamber (16) from the low-pressure region (28) is disposed between the first section (18.1) and the pump casing (12), and the pump piston (18) is slidable within the high-pressure seal; A low-pressure seal (78) separating the low-pressure region (28) from a space (100) outside the fuel high-pressure pump (10) is disposed between the second section (18.2) and a seal support (60) fixed to the pump casing (12); A stepped chamber (28d) of the low-pressure region (28) is located between the seal support (60) and the pump casing (12). ​ When the differential pressure between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds the opening pressure, the pressure limiting valve (22) fluidly connects the high-pressure region (29) to the stepped chamber (28d) of the low-pressure region and opens towards the stepped chamber (28d), allowing fuel to flow out from the high-pressure region (29) to the stepped chamber (28d). The pump casing (12) has a pump body (12a) and a pump cover (12b) connected to each other. The pump body (12a) and the pump cover (12b) define a damping region (28a) belonging to the low-pressure region (28), and at least one diaphragm damper (55) is arranged in the damping region. The pressure limiting valve (22) is arranged in a pressure limiting valve hole (22a) formed as a through hole penetrating the pump body (12a). The pressure limiting valve hole (22a) extends from the damping region (28a) to the stepped chamber (28d). On the side facing the damping region (28a), it is closed by a ball (56) press-fitted into the pressure limiting valve hole (22a) or a plug body (57) press-fitted into the pressure limiting valve hole (22a). The pressure limiting valve hole (22a) is formed as a stepped hole, having a first section (22.1) with a relatively large diameter facing the damping region (28a) and a second section (22.3) with a relatively small diameter facing the stepped chamber (28d), and having a ring-shaped step (22.2) formed between the first section (22.1) and the second section (22.3). The pressure limiting valve (22) has a valve seat body (38) press-fitted into the pressure limiting valve hole (22a). A conical valve seat (42) is formed on the valve seat body. The pressure limiting valve (22) has a valve element (44) that closely abuts against the valve seat (42). The valve element (44) is pushed in the closing direction by a holding element (46), the holding element (46) is pushed in the closing direction by a coil spring (52), and the coil spring (52) is supported by the ring-shaped step (22.2). Fuel high-pressure pump (10).

2. The outlet valve (37) is arranged in an outlet valve hole (37a) of the pump casing (12), and the outlet valve hole (37a) and the pressure limiting valve hole (22a) intersect. The fuel high-pressure pump (10) according to claim 1.

3. The outlet valve (37) has a movable valve element (37.1) and has a seal seat portion (37.2) arranged upstream of the valve element (37.1). The seal seat portion is attached to the pump fixture at a seal seat fixing section (37.3). A seal seat (37.4) that cooperates with the valve element (37.1) is formed on the seal seat portion. The outlet valve (37) has a corresponding plate (37.5) of the pump fixture arranged downstream of the valve element (37.1). The corresponding plate is attached to the pump fixture at a corresponding plate fixing section (37.6) and restricts the movability of the valve element (37.1) in the downstream direction. The pressure limiting valve hole (22a) intersects the outlet valve hole (37a) between the seal seat fixing section (37.3) and the corresponding plate fixing section (37.6). The fuel high-pressure pump (10) according to claim 2.

4. The outlet (34) is formed as an outlet pipe piece (35) fixed to the pump casing (12). An outlet pipe piece chamber (35a) is formed between the pump casing (12) and the outlet pipe piece (35). The outlet valve (37) is fixed to an outlet valve hole (37a) of the pump casing (12). The outlet valve hole (37a) starts from the outlet pipe piece chamber (35a). The pressure limiting valve hole (22a) is connected to the outlet pipe piece chamber (35a) via a high-pressure connection hole (29a) located in the high-pressure region (29) starting from the outlet pipe piece chamber (35a). The fuel high-pressure pump (10) according to claim 1.

5. The outlet valve hole (37a) and the high-pressure connection hole (29a) are arranged parallel to each other and perpendicular to the longitudinal direction (LA). The fuel high-pressure pump (10) according to claim 4.

6. The outlet valve hole (37a) and the high-pressure connection hole (29a) are arranged at an angle other than 0° to each other and are each arranged perpendicular to the longitudinal direction (LA). The fuel high-pressure pump (10) according to claim 4.

7. The fuel high-pressure pump (10) according to any one of claims 2 to 6, wherein the virtual central axis of the outlet valve hole (37a) intersects the virtual central axis of the pump piston (18).

8. The fuel high-pressure pump (10) according to any one of claims 2 to 6, wherein the virtual central axis of the outlet valve hole (37a) does not intersect the virtual central axis of the pump piston (18).

9. A fuel high-pressure pump (10) for a fuel system for an internal combustion engine, comprising: an inlet (11) for supplying fuel; an outlet (34) for discharging the compressed fuel; a pump casing (12); a pumping chamber (16) disposed within the pump casing (12); a pump piston (18) defining the pumping chamber (16) and slidable along a longitudinal direction (LA) within the pump casing (12); an inlet valve (14) disposed between the inlet (11) and the pumping chamber (16) and opening toward the pumping chamber (16); an outlet valve (37) disposed between the pumping chamber (16) and the outlet (34) and opening in a direction away from the pumping chamber (16); a high-pressure region (29) fluidly extending between the outlet valve (37) and the outlet (34); a low-pressure region (28) fluidly extending between the inlet (11) and the inlet valve (14); a pressure-limiting valve (22) that fluidly connects the high-pressure region (29) to the low-pressure region (28) and opens toward the low-pressure region (28) to allow fuel to flow out of the high-pressure region (29) into the low-pressure region (28) when the differential pressure between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds the opening pressure; comprising: The pump piston (18) is formed as a stepped piston and has a first section (18.1) facing the pumping chamber (16) and having a relatively large diameter, and a second section (18.2) having a relatively small diameter and directed away from the pumping chamber (16). A high-pressure seal (80) that separates the pumping chamber (16) from the low-pressure region (28) is disposed between the first section (18.1) and the pump casing (12), and the pump piston (18) is slidable within the high-pressure seal. Between the second section (18.2) and a seal support (60) fixed to the pump casing (12), a low-pressure seal (78) is arranged to separate the low-pressure region (28) from a space (100) outside the fuel high-pressure pump (10). Between the seal support (60) and the pump casing (12), a stepped chamber (28d) of the low-pressure region (28) is located. When the differential pressure between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds the opening pressure, the pressure limiting valve (22) fluidly connects the high-pressure region (29) to the stepped chamber (28d) of the low-pressure region (28) and opens towards the stepped chamber (28d), allowing fuel to flow out from the high-pressure region (29) to the stepped chamber (28d). The outlet valve (37) is arranged in an outlet valve hole (37a) of the pump casing (12) and has a movable valve element (37.1). It also has a seal seat portion (37.2) arranged upstream of the valve element (37.1). The seal seat is attached to the pump fixing at a seal seat fixing section (37.3). A seal seat (37.4) that cooperates with the valve element (37.1) is formed on the seal seat. The outlet valve (37) has a pump-fixed corresponding plate (37.5) arranged downstream of the valve element (37.1). The corresponding plate is attached to the pump fixing at a corresponding plate fixing section (37.6), restricting the movability of the valve element (37.1) in the downstream direction. The pressure limiting valve (22) is arranged in a pressure limiting valve hole (22a) in the pump casing (12). The pressure limiting valve hole extends in the longitudinal direction (LA) and opens from the stepped chamber (28d) to the outlet valve hole (37a), that is, between the seal seat fixing section (37.3) and the corresponding plate fixing section (37.6), for the fuel high-pressure pump (10).

10. A fuel high-pressure pump (10) for a fuel system for an internal combustion engine, an inlet (11) for supplying fuel, an outlet (34) for discharging compressed fuel, a pump casing (12), a pumping chamber (16) arranged in the pump casing (12), A pump piston (18) that defines the pressure chamber (16) and is slidable along the longitudinal direction (LA) within the pump casing (12); An inlet valve (14) disposed between the inlet (11) and the pressure chamber (16) and opening toward the pressure chamber (16); An outlet valve (37) disposed between the pressure chamber (16) and the outlet (34) and opening in a direction away from the pressure chamber (16); A high-pressure region (29) that extends fluidly between the outlet valve (37) and the outlet (34); A low-pressure region (28) that extends fluidly between the inlet (11) and the inlet valve (14); A pressure-limiting valve (22) that fluidly connects the high-pressure region (29) to the low-pressure region (28) and opens toward the low-pressure region (28) to allow fuel to flow out from the high-pressure region (29) to the low-pressure region (28) when the differential pressure between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds the opening pressure; Comprising; The pump piston (18) is formed as a stepped piston and has a first section (18.1) that faces the pressure chamber (16) and has a relatively large diameter, and a second section (18.2) that has a relatively small diameter and is directed away from the pressure chamber (16); A high-pressure seal (80) that separates the pressure chamber (16) from the low-pressure region (28) is disposed between the first section (18.1) and the pump casing (12), and the pump piston (18) is slidable within the high-pressure seal; A low-pressure seal (78) that separates the low-pressure region (28) from the space (100) outside the fuel high-pressure pump (10) is disposed between the second section (18.2) and a seal support (60) fixed to the pump casing (12); A stepped chamber (28d) of the low-pressure region (28) is located between the seal support (60) and the pump casing (12); When the differential pressure between the fuel in the high-pressure region (29) and the fuel in the low-pressure region (28) exceeds the opening pressure, the pressure-limiting valve (22) fluidly connects the high-pressure region (29) to the stepped chamber (28d) of the low-pressure region and opens toward the stepped chamber (28d) to allow fuel to flow out from the high-pressure region (29) to the stepped chamber (28d); The outlet valve (37) is disposed within an outlet valve hole (37a) of the pump casing (12); The pressure limiting valve (22) is disposed within a pressure limiting valve bore (22a) in the pump casing (12), the pressure limiting valve bore extending in the longitudinal direction (LA) and opening at a high-pressure connection bore (29a) within the pump casing (12) starting from the stepped chamber (28d), the high-pressure connection bore being disposed in the high-pressure region (29) and being oriented at an angle other than 0° with respect to the outlet valve bore (37a), fuel high-pressure pump (10).

Images