DE102019217684A1 - High pressure fuel pump for a fuel system of an internal combustion engine - Google Patents

Abstract

High-pressure fuel pump for a fuel system of an internal combustion engine, with a pump housing, an outlet check valve (20) arranged in the pump housing, the outlet check valve (20) having a valve seat element (30), a valve element (32), a stop element (34) for the valve element (32) and a plurality of guide webs (56) which extend in an axial direction and are spaced apart from one another as seen in the circumferential direction, which guide the valve element (32) in the radial direction and which are either in one piece with the valve seat element (30) or in one piece are formed with the stop element (34), characterized in that adjacent guide webs (56) are connected to one another by a connecting section (60) at the end protruding from the valve seat element (30) or from the stop element (34).

Description

State of the art

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

For example from the DE 10 2014 207 194 A1 a high-pressure fuel pump for a fuel system of an internal combustion engine is known. The high pressure fuel pump is a piston pump. When a pump piston moves, fuel is expelled through an outlet check valve into a high pressure area. The function of the outlet check valve is to prevent fuel from flowing back into the delivery chamber from the high pressure area. At the same time, the outlet check valve must allow fuel to flow from the delivery chamber into the high-pressure area. The valve element of the outlet check valve is usually a valve ball which, in the closed state, rests against a valve seat of a valve seat element. An opening movement of the valve ball is limited by a stop element. A radial guidance of the valve element is achieved by axially extending guide webs.

Disclosure of the invention

The problem on which the invention is based is solved by a high-pressure fuel pump having the features of claim 1. Advantageous further developments of the invention are specified in the subclaims.

According to the invention, it was recognized that when the outlet valve is pressed into an outlet channel, the guide webs with the protruding end are pressed axially onto the opposite part. However, due to manufacturing-related dimensional deviations in the length of the guide bars, it can happen that individual guide bars have no contact with the opposite part. This makes it possible for these guide webs to “swing freely”, which affects their fatigue strength. In addition, radial movements of the valve element can lead to further loads that can impair the fatigue strength of the guide webs. According to the invention, this is countered by increasing the rigidity of the guide webs in a very simple manner.

Specifically, a high-pressure fuel pump for a fuel system of an internal combustion engine is proposed. This can be either a diesel fuel system or a gasoline fuel system. The high pressure fuel pump is used to compress the fuel to a very high pressure and to deliver it to a high pressure area, from where it is injected directly into the combustion chambers of the internal combustion engine by means of injectors. The high-pressure fuel pump is usually a piston pump. The high-pressure fuel pump comprises a pump housing and an outlet check valve arranged in the pump housing. The pump housing can be generally cylindrical in shape and the outlet check valve can 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 the valve element. A valve seat is provided on the valve seat element, against which the valve element is acted upon in the closed state. The stop element can be arranged “behind” the valve element as seen in the opening direction of the valve seat element, so that it limits the opening path of the valve element. The outlet check valve can be inserted into or pressed into an outlet channel of the high-pressure fuel pump. For this purpose, the valve seat element and / or the stop element can have a circular cylindrical outer contour, at least in sections. The valve seat element and / or the stop element can be produced by means of metal injection molding.

The outlet check valve also includes a plurality of guide webs extending in an axial direction and spaced apart from one another in the circumferential direction, which guide the valve element in the radial direction and which are either formed in one piece with the valve seat element or in one piece with the stop element. The above-mentioned increase in rigidity is achieved in that adjacent guide webs are connected to one another by a connecting section at the end protruding from the valve seat element or from the stop element. The location specification “at the protruding end” is to be understood broadly in the sense that it also includes an arrangement of a connecting section which is at a certain distance from an end face of the protruding end of a guide web. As a result of the measure according to the invention, loads no longer act on individual guide webs, but on the composite of the interconnected guide webs, which increases the load capacity.

In a further development, it is proposed that the connecting section be formed in one piece on the adjacent guide webs. This makes production easier and leads to optimum fatigue strength.

In a further development, it is proposed that the connecting sections form a continuous, closed ring. This is structurally optimal and ensures maximum strength. It should be noted that the ring can also consist of individual straight segments, as long as these do not hinder the movement of the valve element in the axial direction.

In a further development of this, it is proposed that the ring be circular. As a result, both the fuel flow and the movement of the valve element in the axial direction are least affected.

In a further development of this, it is proposed that an inner diameter of the ring is greater than an inner diameter of the guide webs. This development ensures an unimpeded movement of the valve element.

In a further development, it is proposed that a cross section of at least one connecting section is trapezoidal. This facilitates production, for example by means of an injection molding process, and ensures optimum rigidity in the radial direction with, at the same time, a small extension in the axial direction.

In a further development of this, it is proposed that the edges of the trapezoid be rounded. In this way, the fatigue strength is increased again, since voltage peaks are avoided.

In a further development, it is proposed that at least one connecting section forms a stop to the valve seat element (if the guide webs are molded onto the stop element) or to the stop element (if the guide webs are molded onto the valve seat element). The connecting section thus contributes to increasing the stop surface to the opposite element, whereby the rigidity is increased again.

• 1 einen teilweisen Schnitt durch eine Kraftstoff-Hochdruckpumpe mit einem Auslass-Rückschlagventil;
• 2 eine perspektivische explodierte Darstellung des Auslass-Rückschlagventils von 1;
• 3 eine perspektivische explodierte Darstellung eines Anschlagelements des Auslass-Rückschlagventils von 1; und
• 4 eine Schnittdarstellung des Auslass-Rückschlagventils von 1.

The invention is explained below with reference to the accompanying drawing. In the drawing show:

• 1 a partial section through a high-pressure fuel pump with an outlet check valve;
• 2 FIG. 13 is a perspective exploded view of the outlet check valve of FIG 1 ;
• 3 FIG. 8 is a perspective exploded view of a stop element of the outlet check valve of FIG 1 ; and
• 4th FIG. 3 is a cross-sectional view of the outlet check valve of FIG 1 .

A high pressure fuel pump carries in 1 overall the reference number 10 . It comprises a generally essentially cylindrical pump housing 12th , in the longitudinal direction of which a pump piston 14th is recorded. With the high-pressure fuel pump 10 it is therefore a piston pump. The pump piston 14th and the pump housing 12th limit a funding area 16 . Fuel enters this via an inlet valve 18th , which is designed as an electromagnetically controlled quantity control valve. From the delivery room 16 the compressed fuel arrives via an outlet check valve 20th to a high pressure outlet 22nd and further into a high pressure area 24 . This includes, for example, a fuel collecting line (“rail”) to which a plurality of injectors are connected, which inject the fuel directly into the respectively assigned combustion chambers. Both diesel and gasoline can be used as fuel.

Hydraulically in parallel with the outlet check valve 20th is a pressure relief valve 26th arranged through which fuel from the high pressure outlet 22nd into the conveying chamber under certain operating conditions 16 can flow back. The outlet check valve 20th is in a stepped outlet channel 28 arranged in the pump housing 14th is formed and its longitudinal axis 29 in the present example in the radial direction of the pump housing 12th runs. The longitudinal axis 29 also forms the longitudinal axis of the outlet check valve 20th .

Now is the design of the outlet check valve 20th with reference to the 2-4 explained in detail: the outlet check valve 20th comprises a valve seat element 30th , a valve element embodied here as a valve ball by way of example 32 , an example of a cylindrical and cup-shaped stop element 34 and one in the assembled state between the stop element 34 and the valve element 32 strained valve spring 36 . The valve spring 36 is in the present example designed as a helical spring.

The valve seat element 30th directs you to the 2 and 4th arranged at the right end cylindrical and nozzle-like insertion section 38 on. The lead-in section 38 is in a section 28a of the exhaust duct 28 pressed in fluid-tight. To the cylindrical insertion section 38 closes a likewise cylindrical base section 40 at. This has a larger outer diameter than the insertion section 38 , whereby between the insertion section 38 and the base section 40 a paragraph 42 is formed. This is due to a corresponding paragraph 28b of the exhaust duct 28 at. This is how the valve seat element is 30th of the outlet check valve 20th in the outlet duct 28 exactly positioned in the axial direction.

Both the lead-in section 38 as well as the base section 40 are of a centric flow channel 44 interspersed. Whose in the 2 and 4th left edge forms an annular valve seat 46 for the valve element 32 . The stop element 34 has a jacket section 48 and a bottom section 50 on. In the bottom section 50 is a central through opening 52 available. Both the valve seat element 30th as well as the stop element 34 are produced here by way of example by metal injection molding. In principle, however, other manufacturing processes are also conceivable.

Radially outside are on the shell section 48 of the stop element 34 several, in the present case namely three, for example, arranged evenly distributed in the circumferential direction and protruding radially outward, wing-like press-in sections 54 present with which the stop element 34 into a section 28c of the exhaust duct 28 is pressed in. A press-in section extends in the axial direction as an extension 54 a guide bar 56 from the stop element 34 in the direction of the valve seat element 30th . The guide bars 56 are integral with the jacket section 48 of the stop element 34 educated. The radial outside of the guide bars 56 lies on a diameter which is smaller than the diameter of the outer sides of the press-in sections 54 .

The radial inside of the guide bars 56 lies on a diameter which is larger than an inner diameter of the jacket section 48 . The diameter of the spherical valve element 32 again is slightly smaller than the diameter of the inside of the guide webs 56 , but larger than the inner diameter of the jacket section 48 . Between the valve element 32 and the guide bars 56 there is therefore a certain radial play on the one hand. In this way, on the other hand, between the guide webs 56 and the jacket section 48 an attack 58 formed by an opening movement of the valve element 32 in the axial direction 29 is limited.

In particular from 3 you can see that adjacent guide bars 56 through connecting sections 60 are connected to each other. The connecting sections 60 are in one piece with the adjacent guide webs 56 molded. Furthermore, the connecting sections form 60 In the present case, for example, a total of a circumferential circular ring 62 . In particular from the 3 and 4th one can see that an inner diameter D1 of the ring 62 is larger than the diameter D2 on which the inner sides of the guide webs 56 lie. The connecting sections 60 are on that of the stop element 34 protruding end of the guide webs 56 arranged. You train how 4th can be seen, to the valve seat element 30th towards a stop through which the stop element 34 in the axial direction 29 exactly to the valve seat element 30th is positioned. Out 4th it can also be seen that the cross-section of the connecting sections 60 is trapezoidal, the outer edges of the trapezoid being rounded.

In the figures, that embodiment is shown in which the guide webs 56 to the stop element 34 are molded. In principle, however, an embodiment is also conceivable, but not shown, in which the guide webs are molded onto the valve seat element and extend therefrom in the direction of the stop element. It is also understood that more or fewer guide webs 56 and press-fit sections 54 can be provided. They also do not necessarily have to be arranged evenly distributed in the circumferential direction. The guide bars 56 also do not necessarily have to be an extension of the press-in sections 54 be arranged. There can be different numbers of guide bars 56 and press-fit sections 54 be provided. The cross section of the connecting sections can also be non-trapezoidal, for example circular or elliptical.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102014207194 A1 [0002]

Claims (8)

High-pressure fuel pump (10) for a fuel system of an internal combustion engine, with a pump housing (12), an outlet check valve (20) arranged in the pump housing (12), the outlet check valve (20) being a valve seat element (30), a valve element (32), a stop element (34) for the valve element (32) and a plurality of guide webs (56) extending in an axial direction and spaced apart from one another as seen in the circumferential direction, which guide the valve element (32) in the radial direction and which either are formed in one piece with the valve seat element (30) or in one piece with the stop element (34), characterized in that adjacent guide webs (56) are connected to one another by a connecting section (60) at the end protruding from the valve seat element (30) or from the stop element (34) . High pressure fuel pump (10) Claim 1 , characterized in that the connecting section (60) is integrally formed on the adjacent guide webs (56). High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that the connecting sections (60) form a circumferential ring (62). High pressure fuel pump (10) Claim 3 , characterized in that the ring (62) is circular. High pressure fuel pump (10) Claim 4 , characterized in that an inner diameter of the ring (62) is greater than an inner diameter of the guide webs (56). High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that a cross section of at least one connecting section (60) is trapezoidal. High pressure fuel pump (10) Claim 6 , characterized in that the edges of the trapezoid are rounded. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that at least one connecting section (60) forms a stop towards the valve seat element (30) or towards the stop element (34).

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