JP2022553723A - fuel high pressure pump - Google Patents

Abstract

A high pressure fuel pump (10) for a fuel injection system of an internal combustion engine, comprising a pump housing (12) and a bore (26) disposed within the pump housing (12), the bore (26) ), a pressure limiting valve (22) is arranged in the valve body (34), a valve member (40), a retaining member (42) and at least one valve spring (50). and wherein the retaining member (42) is disposed between the valve member (40) and the valve spring (50). ) is proposed to be guided straight into.

Description

BACKGROUND OF THE INVENTION The present invention relates to a high-pressure fuel pump for a fuel injection system of an internal combustion engine.

High-pressure fuel pumps are known from the known prior art. Such high-pressure fuel pumps have a pressure relief valve which, in the open state, connects the high-pressure area on the outflow side to the delivery chamber of the high-pressure fuel pump. The pressure limiting valve opens when the pressure difference between the high-pressure region on the outflow side and the delivery chamber of the high-pressure fuel pump exceeds a pregiven limit value. In other words, the pressure limiting valve prevents an unacceptably high pressure in the high-pressure region on the outflow side.

DISCLOSURE OF THE INVENTION The problem underlying the present invention is solved by a high-pressure fuel pump having the features of claim 1 . Advantageous refinements of the invention are described in the respective dependent claims. Further features important to the invention are disclosed in the following description and drawings. In this case, these features can be important to the invention either individually or in various combinations.

A high pressure fuel pump according to the invention for a fuel injection system of an internal combustion engine compresses fuel to a high pressure and pumps it to the injectors. The injectors inject this fuel directly into respective combustion chambers provided in the internal combustion engine. The high pressure fuel pump has a pump housing and a bore disposed in the pump housing in which a pressure limiting valve is disposed, the pressure limiting valve compressing the valve body, the valve member and the retainer. The retaining member includes a member and at least one valve spring, the retaining member being disposed between the valve member and the valve spring and configured to be guided straight into the bore.

This pressure limiting valve limits the pressure in the high pressure region on the outflow side of the high pressure fuel pump to the maximum permissible value. When the pressure induced in this high pressure area on the outflow side exceeds the opening pressure of the pressure limiting valve, the valve member is moved against the force of the valve spring so that the fuel flows out of the high pressure area into the pumping chamber and/or the high fuel pressure. It can flow back into the low pressure area within the pump.

Undesirable wear and cavitation erosion can occur on the surfaces between the valve member and the valve body as well as between the valve member and the retaining member. According to the current state of knowledge, wear is caused inter alia by axial and radial movements of the holding member. Cavitation erosion is caused by the movement of the holding member when the pressure limiting valve is opened and by the steam generated during the suction phase of the high pressure fuel pump. Movement of the holding member is caused by pressure pulsations in the delivery chamber of the high-pressure fuel pump and by axial and radial vibrations of the valve spring. Due to the straight guidance of the holding member according to the invention, the holding member is reliably held straight especially when opening and closing, which reduces both wear and cavitation erosion and thus extends the service life of the pressure limiting valve. , and thus the life of the high pressure fuel pump as well as the pressure limiting valve.

"Straight guidance" means that the holding member moves linearly in a generally cylindrical, straight bore, i.e. relative to the longitudinal axis of the bore, for example. It means that it is guided so that it cannot tip over or move laterally with respect to the longitudinal axis. That is, the straight guidance of the retaining member within the bore reduces the radial movement of the retaining member. This is because the holding member is arranged and guided (sliding-fit) in the hole in a form-fitting manner. In other words, the outer diameter of the retaining member is made minimally smaller than the inner diameter of the bore, so that diametrical movement of the retaining member within the bore is prevented or at least minimized. It is from.

Furthermore, the axial movement of the retaining member, ie the longitudinal movement of the bore, is also damped. This takes place on the basis of the friction between the bore and the retaining member guided therein. In order to be able to achieve the desired stabilizing function, it is clear that the outer side of the retaining member in contact with the inner side of the hole must have a certain minimum extension length in the axial direction. is. In other words, the retaining member has a cylindrical section extending axially and having the largest diameter of the retaining member. Straight guidance can thus be ensured without tilting of the holding member inside the bore.

In one refinement, it is proposed that the holding member has a receptacle for the valve member, which receptacle has a bearing surface and at least one wall. That is, the receiving portion is formed as a kind of recess. Such abutment surfaces are preferably oriented perpendicularly to the axial direction of the holding member, i.e. also perpendicularly to the longitudinal extent of the bore of the pressure-limiting valve. . A receiving part with such a bearing surface constitutes structurally simplest possible means for receiving the valve member in the axial direction of the holding member, for holding it in the radial direction and for applying a uniform surface pressure.

In a related refinement, the abutment surface and the wall are arranged with respect to each other so as to form a cylindrical or at least partially spherical receiving chamber for the valve member. proposed. The wall preferably limits movement of the valve member in the radial direction of the retaining member or fixes the position of the valve member in the radial direction of the retaining member. Nevertheless, the valve member may have a certain amount of play within the fixing by the wall. By fixing or limiting the position of the valve member in the radial direction, the valve member is prevented from detaching from the valve seat (i.e. the surface between the valve member and the valve body or the surface between the valve member and the retaining member) and thus It is also possible to prevent the valve member from being caught between the valve body and the retaining member.

In the case of a receptacle with a cylindrical receptacle, the contact surface and the wall are arranged at least partially perpendicular to each other. As a result, the valve member can be accommodated both radially and axially in the retaining member in a very simple manner. Such a receptacle can be realized, for example, by a blind hole in the holding member.

In another refinement, it is proposed that the holding member has at least one fluid connection between the side facing the valve body and the side facing away from the valve body. In this case, the fluid connections are in particular arranged in such a way that as much fuel (fluid/liquid) as possible can flow through the holding member. If a defined amount of fuel is to flow through the retaining member, the flow velocity of the fuel can be controlled by as large a fluid connection as possible, i.e. a fluid connection with a flow cross section as large as possible, or as a whole through a flow cross section as large as possible. It is reduced and kept relatively low by as many fluid connections as possible, which produce a surface. Due to the low flow velocity, the movements of the retaining member are reduced and the cavitation effects that occur during rapid liquid flow are reduced or even completely eliminated. This improves the "communication" from the valve seat, i.e. the surface between the valve member and the valve body or the surface between the valve member and the retaining member, to the pumping chamber of the high pressure fuel pump, which is responsible for cavitation erosion. result in further reduction.

In a related refinement it is proposed that the fluid connection comprises at least one hole through the holding member. This makes it possible, for example, to manufacture the holding member as a turned part on a lathe. Such fabrication methods may be advantageous, eg, less expensive, than other fabrication methods.

In an alternative or additional refinement in this connection, it is proposed that the fluid connection comprises an overall substantially annular passage with a plurality of connecting ribs. . Preferably radially extending connecting ribs connect the radially inner material section and the radially outer material section. These connecting ribs are preferably uniformly distributed in the circumferential direction. Preferably such connecting ribs all have the same geometry and size, each have the same radial spacing from the longitudinal axis of the retaining member and are e.g. symmetrical with respect to the longitudinal axis of the retaining member. or, as already mentioned, evenly distributed in the circumferential direction. This can ensure that the valve member receives maximum radial retention or maximum positional fixation with minimal material usage. Due to the fact that only a relatively small amount of material is used to realize the retaining member, the "communication" from the valve seat to the delivery chamber of the high-pressure fuel pump is also improved. In other words, since the flow cross-section of the fluid connection is relatively large, the flow velocity of the fuel (fluid) is relatively low and thus the cavitation effect is also small.

A further refinement proposes that the valve member is of spherical design. Such a valve member is very simple to manufacture and easy to handle, whereby manufacturing costs can be kept low. Furthermore, in combination with a receiving part having a cylindrical receiving chamber, it is obtained that the spherical valve member contacts the abutting surface at only one point and at most linearly contacts the wall at its peripheral surface. . This minimizes the contact surface between the retaining member and the valve member. Preferably, the spherical valve member does not contact the wall in the closed state of the pressure limiting valve. In the closed state of the pressure limiting valve, radial centering of the spherical valve member takes place via a valve seat provided in the valve body. The wall acts to prevent the ball from falling off in the open state of the pressure limiting valve or when the pressure limiting valve opens and closes.

In a further refinement, it is proposed that the holding member has at least one projection, which is formed at least partially as a spring guide for the valve spring. This projection is formed, for example, in the form of a raised cylindrical projection extending into the interior of the spring. The projection may extend, preferably axially, over the length of about two spring turns of the valve spring. A particularly good and reliable seating of the valve spring on the retaining member can thereby be ensured. Furthermore, this at least partial spring guide avoids or at least reduces axial and radial oscillations of the valve spring. This again reduces the axial and radial movements of the holding member and thus the wear mentioned at the outset.

In a further refinement, it is proposed that the pressure limiting valve has a valve spring guide member. The valve spring guide element is arranged at least partially in the region of the end of the valve spring facing away from the retaining element. The valve spring guide is constructed in such a way that the region of the end of the valve spring facing away from the retaining member is guided by this valve spring guide. Preferably, the projection extends in the direction of the retaining member to such an extent that the retaining member can still perform a sufficient opening movement reliably.

Axial and radial vibrations of the valve spring can be avoided or at least reduced by such a spring guide member. This again results in reduced axial and radial movement of the retaining member.

In a further refinement it is proposed that the holding member is a component manufactured by powder injection molding. However, the retaining member can also be manufactured as a turned part. Relatively complex shapes, in particular curved channels and the like, can also be produced by powder injection molding. In contrast, production as a turned part is relatively inexpensive.

Embodiments of the invention are described below with reference to the drawings.

1 is a sectional view of a high-pressure fuel pump according to the invention with a pressure limiting valve; FIG. 2 is a longitudinal section through the pressure limiting valve shown in FIG. 1; FIG. 2 is a perspective view of a section in the area of the pressure limiting valve shown in FIG. 1; FIG. 2 is a cross-sectional view of a holding member of the pressure limiting valve shown in FIG. 1; FIG. It is the figure which looked at the holding member shown in FIG. 1 from the side, the upper part, and the lower part. 3A and 3B are views of the holding member and the valve member shown in FIG. 1 as viewed obliquely, from above, and from below; FIG. 3 is a longitudinal section similar to FIG. 2 showing another embodiment of a pressure limiting valve; Figure 8 shows two perspective views of a retaining member of the pressure limiting valve shown in Figure 7; FIG. 8 is a top view of the holding member and valve member shown in FIG. 7; FIG. 3 is a longitudinal cross-sectional view similar to FIG. 2 showing yet another embodiment of a pressure limiting valve; Figure 11 shows two perspective views of the retaining member of the pressure limiting valve shown in Figure 10; FIG. 11 is a top view of the holding member and valve member shown in FIG. 10; FIG. 3 is a longitudinal cross-sectional view similar to FIG. 2 showing yet another embodiment of a pressure limiting valve; Figure 14 shows two perspective views of a retaining member of the pressure limiting valve shown in Figure 13; FIG. 14 is a top view of the holding member and valve member shown in FIG. 13;

In the figures listed below, functionally equivalent components and regions are denoted by the same reference numerals even in different embodiments.

In FIG. 1, reference numeral 10 generally designates a high-pressure fuel pump for an internal combustion engine (not shown in detail). The high pressure fuel pump 10 has a generally substantially cylindrical pump housing 12 in which the major components of the high pressure fuel pump 10 are housed or mounted. That is, the high pressure fuel pump 10 includes an inflow/volume control valve 14, a pumping piston 18 arranged in a pumping chamber 16 and brought to reciprocating motion by a drive shaft (not shown), an outflow valve 20 and a pressure limiting valve. 22.

A first passageway 24 is provided within the housing 12 and extends coaxially with respect to the pumping chamber 16 and the pumping piston 18 . A first passageway 24 leads from the pumping chamber 16 to a second passageway which is generally formed in the shape of a substantially cylindrical bore 26 . This hole 26 is arranged at an angle of 90° to the first passage 24 and the pressure limiting valve 22 is housed in this hole 26 . The longitudinal axis of the pump housing 12 is indicated generally at 28 and the longitudinal axis of the bore 26 is indicated at 29 in FIG.

In operation, the pumping piston 18 reciprocating parallel to the longitudinal axis 28 causes fuel, for example gasoline or diesel fuel, to enter the pumping chamber 16 via the inlet/volume control valve 14 during the intake stroke. sucked in. During the pumping stroke, the fuel present in the pumping chamber 16 is compressed and discharged via the outlet valve 20, for example into a high pressure region 30, for example into a fuel collecting line ("rail"), where this fuel is Fuel is stored under high pressure in the collecting line. The high-pressure region 30 is connected to the high-pressure fuel pump 10 via an outlet pipe piece 32 . In this case, the amount of fuel delivered during the pumping stroke is regulated by an electromagnetically actuated intake/volume control valve 14 . If an impermissible overpressure occurs in the high-pressure region 30 , the pressure limiting valve 22 opens so that fuel can flow from the high-pressure region into the pumping chamber 16 .

The pressure limiting valve 22 connects the high pressure region 30 to the delivery chamber 16 of the high pressure fuel pump 10 in the open state, as described above. In this case, the pressure limiting valve 22 opens when the pressure difference between the outflow-side high-pressure region 30 and the delivery chamber 16 of the high-pressure fuel pump 10 exceeds a pregiven limit value. In other words, the pressure limiting valve 22 prevents the pressure in the high-pressure region 30 on the outflow side from becoming unacceptably high.

FIG. 2 shows a cross-sectional view of the pressure limiting valve 22 shown in FIG. A sleeve-like valve body 34 , which is pressed into the bore 26 , belongs first to the pressure limiting valve 22 . A stepped passageway 36 extending in the longitudinal direction 29 of the valve body 34 is provided in the valve body 34 . 2, the valve body 34 is formed with a valve seat 38 which cooperates with a valve member 40 in the form of a valve ball. A retaining member 42 is arranged on the side of the valve member 40 facing away from the valve seat 38 .

The holding member 42 is of substantially cylindrical shape and in this embodiment has three fluid connections 44, one abutment surface 46 and three walls 48 (see also FIGS. 5 and 6). reference). The wall 48 is formed by each radially inward inner side of three projections which are arranged on the side of the retaining member 42 facing the valve body 34, which is on the left in FIG. Due to the cylindrical shape of the holding member 42, the holding member 42 is guided straight in the bore 26 in a slip-fit manner. That is, the retaining member 42 moves linearly parallel to the longitudinal axis 29 within the bore 26 . Such guidance of the retaining member 42 within the bore 26 may prevent, or at least reduce, radial movement of the retaining member. Due to the tight-fitting cylindrical shape of the retaining member 42, during an axial reciprocating movement, i.e. parallel to the longitudinal axis 29, when the pressure limiting valve 22 is opened or closed. Tilting and snagging of the retaining member 42 on the rim is avoided or at least reduced. The holding member 42 is held straight even when the pressure limiting valve 22 is closed.

A valve spring 50 in the form of a compression spring is arranged or tensioned between the retaining member 42 and the right-hand end of the bore 26 as seen in FIG. That is, the valve member 40 is biased toward the valve seat 38 via the retaining member 42 by the valve spring 50 . Valve member 40 is centered relative to retaining member 42 and longitudinal axis 29 by abutment surface 46 and valve seat 38 .

FIG. 3 shows a perspective view showing a part of the cross section of the pressure limiting valve 22 shown in FIG. The valve body 34, the valve member 40, the retaining member 42 and a portion of the valve spring 50 can be seen.

FIG. 4 shows a cross-sectional view of the holding member 42 shown in FIG. In this case it can be seen particularly clearly that an angle of 90° is formed between the abutment surface 46 and the wall 48 .

FIG. 5 shows views of the holding member 42 shown in FIG. 1 as seen from the side, above, and below. In this case, it can be clearly seen how the three fluid connections 44 extend. These fluid connections 44, viewed as a whole, form a substantially annular passage, which in this case is provided with three connecting ribs (not numbered), these The connecting rib is designed as a projection in the direction of the valve body 34 . The sides of the projections of the connecting ribs closer to the longitudinal axis 29 , ie the radially inner sides (inside), each form a wall 48 . The wall 48 together with the axial bearing surface 46 forms a receptacle 45 for the valve member 40 .

FIG. 6 shows views of the holding member 42 and the valve member 40 shown in FIG. 1 viewed obliquely, from above, and from below. From the three figures, it can be seen that the valve member 40 is fitted in the retaining member 42 or the receiving portion 45 . The contact between spherical valve member 40 and retaining member 42 is substantially point-like with respect to abutment surface 46 and linear with respect to wall 48 . Line or point contact between the valve member 40 and the retaining member 42 provides relatively direct "communication" from the valve seat to the pumping chamber 16 . Such direct "communication" results in a relatively small pressure differential across the retaining member 42 and a reduction in the forces acting on the retaining member 42, which ultimately results in wear of the retaining member 42. result in a decrease.

Based on the point contact between the valve member 40 and the abutment surface 46 of the retaining member 42, the transmission of lateral forces/moments from the retaining member 42 to the valve member 40 is prevented or at least reduced. This results in an at least substantially lateral force/moment free valve seat and thus uniform surface pressure. As a result, wear reduction is obtained.

Furthermore, due to the sufficient point contact between the valve member 40 and the abutment surface 46 of the holding member 42, the axially pressurized pressure receiving surface of the holding member 42 is kept small. As a result, the hydraulic force acting on the holding member 42 is kept small, and thus the axial movement of the holding member 42 is reduced. This results in reduced wear.

The measures described above also reduce cavitation erosion at the valve seat. That is, the more direct "communication" from the valve seat to the pumping chamber 16 reduces cavitation erosion due to vapor generation during the suction phase of the high pressure fuel pump 10 . The reduced axial movement of the retaining member 42 (see wear) results in less opening of the pressure limiting valve 22, which again results in reduced cavitation erosion. Reducing the radial movement of the retaining member 42 and inhibiting the transmission of lateral forces/moments to the valve member 40 produces a relatively uniform surface pressure and thus less opening of the pressure limiting valve 22; This again results in reduced cavitation erosion.

Retaining member 42 may be manufactured as a component, for example, in a metal powder injection molding (MIM) process.

A cross-sectional view of another embodiment of the pressure limiting valve 22 is shown in FIG. This embodiment differs from the previous embodiment in that the side of the retaining member 42 facing the valve spring 50 has three protrusions 52 . These projections 52 act at least partially as guides for the valve springs 50 . Furthermore, this pressure limiting valve 22 has a valve spring guide member 54 . By means of this valve spring guide member 54 the valve spring 50 is guided at least partially axially, ie parallel to the longitudinal direction 29 . The valve spring 50 is thus guided straight in the axial direction at least partially by the protrusion 52 and the valve spring guide member 54 . Undesired oscillations of the valve spring 50 in the radial direction can hereby be avoided or at least reduced.

8 and the top view of the holding member 42 and the valve member 40 shown in FIG. 9, the holding member 42 according to the embodiment shown in FIG. 7 can be clearly seen. .

A cross-sectional view of yet another embodiment of the pressure limiting valve 22 is shown in FIG. This embodiment differs from the previous embodiment in that the fluid connection 44 is formed as a hole through the retaining member 42 extending axially, i.e. parallel to the longitudinal direction 29 . . It is therefore possible to manufacture this holding member 42 as a turned part by means of a lathe. Furthermore, the holding member 42 has three projections 52 which are slightly longer than the previous embodiment of the pressure limiting valve 22 . As a result, a better guidance of the valve spring 50 in the region of its left end as seen in FIG. 10 is obtained.

The holding member 42 according to the embodiment shown in FIG. 10 can be clearly seen from both the perspective view of the holding member 42 shown in FIG. 11 and the top view of the holding member 42 and the valve member 40 shown in FIG. .

A cross-sectional view of yet another embodiment of the pressure limiting valve 22 is shown in FIG. This embodiment differs from the previous embodiments in that the retaining member 42 is formed as a turned part with the valve member 40 seated in a recess. In this case, the wall 48 is not realized by a projection, as in the embodiment described above, but by a central spherical recess substantially complementary to the spherical valve member 40. be. Furthermore, this pressure limiting valve 22 does not have a valve spring guide member 54 .

Of course, the retaining member 42, described as a turned part, can also be manufactured in other ways, for example by metal powder injection molding (MIM).

The holding member 42 according to the embodiment shown in FIG. 13 can be clearly seen from both perspective views of the holding member 42 shown in FIG. 14 and from the top view of the holding member 42 and the valve member 40 shown in FIG. .

Claims (10)

A high pressure fuel pump (10) for a fuel injection system of an internal combustion engine, comprising a pump housing (12) and a bore (26) disposed within the pump housing (12), the bore (26) ) in which a pressure limiting valve (22) is arranged, the pressure limiting valve (22) comprising a valve body (34), a valve member (40), a retaining member (42) and at least one valve spring (50), wherein said retaining member (42) is disposed between said valve member (40) and said valve spring (50);
A high-pressure fuel pump (10) for a fuel injection system of an internal combustion engine, characterized in that said retaining member (42) is configured to be guided straight into said bore (26). Said retaining member (42) has a receptacle (45) for said valve member (40), said receptacle (45) comprising an abutment surface (46) and at least one wall (48). A high pressure fuel pump (10) according to claim 1, characterized in that it comprises: Said abutment surface (46) and said wall (48) are arranged relative to each other to form a cylindrical or at least partially spherical receiving chamber for said valve member (40). A high pressure fuel pump (10) according to claim 2, characterized in that there is a Said retaining member (42) is characterized by having at least one fluid connection (44) between the side facing said valve body (34) and the side facing away from said valve body (34). A high-pressure fuel pump (10) according to any one of claims 1 to 3, characterized in that A high pressure fuel pump (10) according to claim 4, characterized in that said fluid connection (44) comprises at least one hole extending through said retaining member (42). 6. A high-pressure fuel pump (10) according to claim 4 or 5, characterized in that the fluid connection (44) comprises an annular passage with connecting ribs. 7. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that the valve member (40) is of spherical design. The retaining member (42) has at least one projection (52), which is at least partially formed as a spring guide for the valve spring (50). A high pressure fuel pump (10) according to at least any one of claims 1 to 7, wherein the high pressure fuel pump (10). Said pressure limiting valve (22) has a valve spring guide member (54) which is at least partly of said valve spring (50), apart from said retaining member (42). Arranged in the region of the opposite end, the end region of the valve spring (50) facing away from the retaining member (42) is guided by the valve spring guide member (54). 9. The high-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that it is configured to . 10. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that the holding member (42) is a component or a turned part manufactured by powder injection molding.

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