KR20220097507A - High-pressure fuel pumps for fuel systems in internal combustion engines - Google Patents

Abstract

A high pressure fuel pump for a fuel system of an internal combustion engine, comprising a pump housing and an outlet check valve (20) disposed in the pump housing, the outlet check valve (20) comprising a valve seat element (30), a valve element (32) . In the high pressure fuel pump, which radially guides (32) and is integral with the valve seat element (30) or integrally with the stop element (34), adjacent guide webs (56) are connected to the valve seat element ( 30) or connected to each other via a connecting section (60) at the end projecting from the stop element (34).

Description

High-pressure fuel pumps for fuel systems in internal combustion engines

The present invention relates to a high-pressure fuel pump for a fuel system of an internal combustion engine according to the preamble of claim 1 .

A high-pressure fuel pump for a fuel system of an internal combustion engine is known, for example, from DE 10 2014 207 194 A1. The high pressure fuel pump is a piston pump. As the pump piston moves, the fuel is discharged through the outlet check valve into the high-pressure area. The function of the outlet check valve is to prevent backflow of fuel from the high pressure region into the delivery chamber. At the same time, the outlet check valve must allow fuel to flow from the delivery chamber to the high-pressure region. The valve element of the outlet check valve is a valve ball that contacts the valve seat of the valve seat element in the normally closed state. The opening motion of the valve ball is limited by the stop element. Radial guidance of the valve element is achieved by means of an axially extending guide web.

The problem of the invention is solved by a high-pressure fuel pump having the features of claim 1 . Preferred refinements of the invention are presented in the dependent claims.

According to the present invention, it has been recognized that when the outlet valve is pressed into the outlet channel, the guide webs with the projecting ends are actually pressed axially against the opposite part. However, individual guide webs may not contact opposite portions due to manufacturing-related dimensional variations in guide web length. As a result, these guide webs can "freely oscillate" and reduce fatigue strength. In addition, radial movement of the valve element can cause additional loads that can lower the fatigue strength of the guide web. This is counterbalanced according to the invention in that the stiffness of the guide web is increased in a very simple manner.

Specifically, a high-pressure fuel pump for a fuel system of an internal combustion engine is proposed. The fuel system may be a diesel fuel system and a gasoline fuel system. A high-pressure fuel pump is used to compress the fuel to a very high pressure and pump it to the high-pressure region, from which the fuel is directly injected by means of an injector into the combustion chamber of the internal combustion engine. High pressure fuel pumps are generally piston pumps. A high pressure fuel pump includes a pump housing and an outlet check valve disposed in the pump housing. The pump housing may have an overall substantially cylindrical shape and the outlet check valve may be a spring loaded ball valve.

For this purpose, the outlet check valve has a valve seat element, a valve element and a stop element for said valve element. The valve seat element has a valve seat, the valve element acting on the valve seat in a closed state. The stop element may be disposed "behind" the valve element when viewed from the valve seat element in an opening direction to limit the opening movement of the valve element. The outlet check valve may be inserted or press fit into the outlet channel of the high pressure fuel pump. To this end, the valve seat element and/or the stop element may at least partially have an outer contour of a circular cylinder. The valve seat element and/or the stop element may be manufactured by metal injection molding.

The outlet check valve includes a plurality of guide webs extending axially and spaced apart from each other when viewed in the circumferential direction, the guide webs guiding the valve element radially and integrally with the valve seat element or integrally with the stop element. do. The aforementioned increase in stiffness is achieved in that adjacent guide webs are connected to one another by means of a connecting section at the end projecting from the valve seat element or stop element. The positional indication "at the protruding end" is to be understood broadly in the sense that it also includes the arrangement of the connecting section at a certain distance from the end face of the protruding end of one guide web. As a result of the measures according to the invention, the load-bearing capacity is increased, since the load no longer acts on individual guide webs but rather on the combination of interconnected guide webs.

In one refinement it is proposed that the connecting section is formed integrally with the adjacent guide web. This simplifies manufacturing and leads to optimum fatigue strength.

In one refinement it is proposed that the connecting section forms a peripheral closure ring. It is structurally optimal and guarantees maximum strength. The ring may consist of individual straight segments as long as they do not impede axial movement of the valve element.

In one refinement the ring is proposed as a circle. As a result, fuel flow and movement of the valve element in the axial direction are least affected.

In one refinement it is proposed that the inner diameter of the ring is larger than the inner diameter of the guide web. An unobstructed movement of the valve element is ensured by this refinement.

A refinement proposes that the cross-section of the at least one connecting section is trapezoidal. This simplifies manufacturing, for example through the injection molding process, and ensures optimum stiffness in the radial direction with a slight extension in the axial direction.

In one refinement, it is proposed to round the edges of the trapezoid. In this way, stress peaks are avoided, thus increasing the fatigue strength.

In one refinement it is proposed that the at least one connection section forms a stop towards the valve seat element (if the guide web is formed on the stop element) or the stop element (if the guide web is formed on the valve seat element). The connecting section thus contributes to an increase in the stopping surface for the opposite element, resulting in a further increase in rigidity.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described below with reference to the accompanying drawings.

1 is a partial cross-sectional view of a high-pressure fuel pump with an outlet check valve;
Figure 2 is an exploded perspective view of the outlet check valve of Figure 1;
3 is an exploded perspective view of a stop element of the outlet check valve of FIG. 1 ;
Fig. 4 is a cross-sectional view of the outlet check valve of Fig. 1;

The high-pressure fuel pump is generally designated 10 in FIG. 1 . The high-pressure fuel pump 10 includes a substantially cylindrical pump housing 12 , in which a pump piston 14 is accommodated in its longitudinal direction. The high-pressure fuel pump 10 is a piston pump. The pump piston 14 and the pump housing 12 define a delivery chamber 16 . Fuel enters this chamber through an inlet valve 18 designed as an electromagnetically controlled positive control valve. The compressed fuel is delivered from the delivery chamber 16 through the outlet check valve 20 to the high pressure outlet 22 and further to the high pressure region 24 . The high-pressure region comprises, for example, a fuel collection line (“rail”) to which a plurality of injectors are connected, which inject fuel directly into the associated combustion chamber. Both diesel and gasoline can be used as fuel.

Hydraulically parallel to the outlet check valve 20 , a pressure relief valve 26 is arranged, said pressure relief valve 26 allowing fuel backflow from the high pressure outlet 22 to the delivery chamber 16 under certain operating conditions. make it possible The outlet check valve 20 is arranged in a stepped outlet channel 28 which is formed in the pump housing 14 and whose longitudinal axis 29 extends here for example in the radial direction of the pump housing 12 . The longitudinal axis 29 also forms the longitudinal axis of the outlet check valve 20 .

The design of the outlet check valve 20 will now be described in detail with reference to FIGS. 2 to 4 : the outlet check valve 20 is a valve seat element 30 , here embodied as a valve ball by way of example 32 ), here for example a generally cylindrical and port-shaped stop element 34 , and a valve spring 36 secured between the stop element 34 and the valve element 32 in the assembled state. The valve spring 36 is designed here, for example as a coil spring.

The valve seat element 30 has a cylindrical socket-shaped insertion section 38 disposed at the right end of FIGS. 2 and 4 . The insertion section 38 is press-fitted into the section 28a of the outlet channel 28 in a fluid-tight manner. A base section 40 , which is likewise cylindrical, continues with the cylindrical insert section 38 . It has a larger outer diameter than the insert section 38 , whereby a shoulder 42 is formed between the insert section 38 and the base section 40 . The shoulder 42 abuts the corresponding shoulder 28b of the outlet channel 28 . In this way, the valve seat element 30 of the outlet check valve 20 is positioned exactly in the outlet channel 28 in the axial direction.

The central flow channel 44 passes through both the insertion section 38 and the base section 40 . 2 and 4 the left edge of the flow channel 44 forms an annular valve seat 46 for the valve element 32 . The stop element 34 has a casing section 48 and a base section 50 . A central passage opening 52 is present in the base section 50 . The valve seat element 30 and the stop element 34 are produced here, for example by metal injection molding. However, in principle other manufacturing methods are possible.

On the radially outward side of the casing section 48 of the stop element 34 , there are a number of, here for example three winged press-in sections 54 , uniformly distributed in the circumferential direction and projecting radially outwardly, , the stop element 34 is press-fitted into the section 28c of the outlet channel 28 into the press-fit sections. In the axial direction, the guide web 56 extends in the direction of the valve seat element 30 from the stop element 34 as an extension of the press-in section 54 . The guide webs 56 are integrally formed with the casing section 48 of the stop element 34 . The radially outer side of the guide web 56 lies at a diameter smaller than the outer diameter of the press-in section 54 .

The radially inner side of the guide web 56 lies at a diameter greater than the inner diameter of the casing section 48 . The diameter of the spherical valve element 32 is slightly smaller than the inner diameter of the guide web 56 , but greater than the inner diameter of the casing section 48 . Accordingly, there is, on the one hand, a certain radial play between the valve element 32 and the guide web 56 . In this way, on the other hand, a stop 58 is formed between the guide web 56 and the casing section 48 , by means of which the valve element 32 in the axial direction 29 . of the opening movement is limited.

As can be seen in particular in FIG. 3 , adjacent guide webs 56 are connected to one another via a connecting section 60 . The connecting sections 60 are integrally formed with the adjacent guide web 56 . Furthermore, the connecting sections 60 here form for example a generally peripheral circular ring 62 . As particularly shown in FIGS. 3 and 4 , the inner diameter D1 of the ring 62 is greater than the diameter D2 on which the insides of the guide web 56 lie. The connecting sections 60 are arranged at the end of the guide web 56 protruding from the stop element 34 . They form a stop towards the valve seat element 30 , as can be seen in FIG. 4 , by means of which the stop element 34 is precisely positioned relative to the valve seat element 30 in the axial direction 29 . do. As can be seen in FIG. 4 , the cross section of the connecting section 60 is trapezoidal, and the outer edges of the trapezoid are rounded.

The figures show an embodiment in which guide webs 56 are formed on a stop element 34 . An embodiment in which guide webs are formed on the valve seat element and extend therefrom in the direction of the stop element is also basically possible, but not shown. It goes without saying that more or fewer guide webs 56 and press-in sections 54 may be provided. Further, they are not necessarily uniformly distributed in the circumferential direction. The guide webs 56 also need not necessarily be arranged as extensions of the press-in section 54 . A different number of guide webs 56 and press-in sections 54 may be provided. Furthermore, the cross-section of the connecting section may not be trapezoidal, for example circular or elliptical.

10: high pressure fuel pump
12: pump housing
20: outlet check valve
30: valve seat element
32: valve element
34: stop element
56: guide web
60: connection section
62: ring

Claims (8)

A high-pressure fuel pump (10) for a fuel system of an internal combustion engine, comprising a pump housing (12) and an outlet check valve (20) disposed in the pump housing (12), the outlet check valve (20) comprising a valve seat element (30) a valve element (32), a stop element (34) for said valve element (32), and a plurality of guide webs (56) extending in the axial direction and spaced apart from each other when viewed in the circumferential direction; The guide webs (56) guide the valve element (32) radially and are configured integrally with the valve seat element (30) or integrally with the stop element (34). In
A high-pressure fuel pump (10), characterized in that adjacent guide webs (56) are connected to one another by a connecting section (60) at the end projecting from the valve seat element (30) or the stop element (34). The high-pressure fuel pump (10) according to claim 1, characterized in that the connecting section (60) is integrally formed on the adjacent guide web (56). 3. High-pressure fuel pump (10) according to claim 1 or 2, characterized in that the connecting section (60) forms a peripheral ring (62). 4. High-pressure fuel pump (10) according to claim 3, characterized in that the ring (62) is circular. 5. The high-pressure fuel pump (10) according to claim 4, characterized in that the inner diameter of the ring (62) is greater than the inner diameter of the guide web (56). 6. High-pressure fuel pump (10) according to any one of the preceding claims, characterized in that the cross-section of the at least one connecting section (60) is trapezoidal. 7. The high-pressure fuel pump (10) according to claim 6, characterized in that the edges of the trapezoid are rounded. 8. High-pressure fuel pump according to any one of the preceding claims, characterized in that at least one connecting section (60) forms a stop towards the valve seat element (30) or the stop element (34). (10).

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