CN112368474A

CN112368474A - Fuel pump

Info

Publication number: CN112368474A
Application number: CN201980045674.4A
Authority: CN
Inventors: S·科尔布; F·梅尔廷
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-07-07
Filing date: 2019-05-17
Publication date: 2021-02-12
Also published as: EP3818261A1; KR20210028642A; WO2020011429A1; DE102018211237A1

Abstract

The invention relates to a fuel pump (28) for a fuel system (10) of an internal combustion engine, wherein the fuel pump (28) has a delivery chamber (44) which is arranged in a pump housing (40) and is delimited by a pump piston (30) which is movable in an axial direction, wherein the fuel pump (28) has an inlet valve (46) which opens out from a low-pressure chamber (43) into the delivery chamber (44), wherein the fuel pump (28) has an outlet valve (48) which opens away from the delivery chamber (44) in the direction of an outlet (90), wherein a first low-pressure connection (20) is provided on the pump housing (40) through which fuel can pass into the low-pressure chamber (43) and/or flow out of the low-pressure chamber (43), wherein a second low-pressure connection (21) is also provided on the pump housing (40), through which fuel can flow into the low-pressure chamber (43) and/or out of the low-pressure chamber (43), wherein the first low-pressure connection (20) is designed as a first connection piece (80) which is arranged on the pump housing (40), wherein the second low-pressure connection (21) is designed as a second connection piece (81) which is arranged on the pump housing (40), characterized in that the first connection piece (80) and the second connection piece (81) are designed as structurally identical parts to one another, which are fastened to the pump housing (40), and in that a throttle element (75) is pressed into the second connection piece (81).

Description

Fuel pump

Technical Field

The invention is based on a fuel pump according to the preamble of claim 1.

Background

Such a fuel pump is also known, for example, from EP 2541039 a 1.

Disclosure of Invention

The present invention is based on the following recognition by the inventors: in the case of pumps having at least two low-pressure connections, different functional requirements are placed on these low-pressure connections, for example, depending on the application, it is desirable for the low-pressure connections to have different flow cross sections.

According to the invention, the first and second connection pieces are provided as structurally identical parts to one another, which are fastened to the pump housing, and the throttle member is pressed into the second connection piece.

In this way, the deformation of the nozzle is minimized, thereby simplifying the production of the fuel pump. In addition, the second low-pressure port can be adapted specifically to the application by its modular design with low outlay.

In a further embodiment of the invention, the outlet is designed as a third connecting piece, which is of the same design as the first and second connecting pieces.

For example, the throttle element can be designed as a sleeve and can, for example, reduce the flow cross section of the second low-pressure connection by at least half, i.e. by a value which is less than half of the initial value.

In some embodiments, the pump housing may include a pump body and a pump cover fitted over the pump body. In this embodiment, the first and second connecting pieces can be fastened to the pump body in the radial direction. Alternatively, it is possible for the first connection piece to be fastened radially to the pump body and for the second connection piece to be fastened to the pump cover; or the second connection piece is fastened to the pump body in the radial direction and the first connection piece is fastened to the pump cover.

Advantageously, it can be provided that further components, such as filters, valves and/or flaps, are pressed into the first and/or second connection piece.

Drawings

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

FIG. 1 shows a schematic diagram of a fuel system of an internal combustion engine;

FIG. 2 illustrates an overall view of a fuel pump according to the present invention;

FIG. 3 shows a longitudinal section of the pump of FIG. 2;

FIG. 4 shows a longitudinal section of the pump of FIG. 2 perpendicular to FIG. 3;

fig. 5 shows a detail view of a second low-pressure connection of the pump of fig. 2.

Detailed Description

Fig. 1 shows a fuel system 10 of an internal combustion engine in a simplified schematic representation. Fuel is supplied from the fuel tank 12 via the suction line 14, by means of the prefeed pump 16, via the low-pressure line 18, via the first low-pressure connection 20 to the high-pressure fuel pump 28.

Fuel, for example gasoline, is compressed to a high pressure in a high-pressure fuel pump 28 and is supplied via a high-pressure rail 32 and a high-pressure injector 34 to a combustion chamber 36 of the internal combustion engine, where it is mixed with air supplied via an intake pipe 38 and is subsequently ignited, for example by means of a spark generated by a spark plug.

On the other hand, if required, a portion of the fuel supplied to the high-pressure fuel pump 28 via the first low-pressure connection 20, after flowing through the high-pressure fuel pump 28 without being compressed, flows out of the high-pressure fuel pump 28 again via the second low-pressure connection 21 and then via the low-pressure injectors 37 into the previously mentioned intake manifold 38, where it is already mixed with the supplied air before it reaches the combustion chambers 36 of the internal combustion engine.

Since the portion of the fuel is supplied to the high-pressure fuel pump 28 via the first low-pressure connection 20 and flows out of the high-pressure fuel pump 28 again via the second low-pressure connection 21 after flowing through the high-pressure fuel pump 28 without being compressed, the fuel flow through the high-pressure fuel pump 28 is ensured even if no compressed fuel is output via the outlet 90 of the high-pressure fuel pump. The second low-pressure port 21 can therefore also be referred to as a scavenging port (Splupascluss) of the high-pressure fuel pump 28.

The high-pressure fuel pump 28 is embodied as a piston pump, wherein, in the figure, the pistons 30 can be moved vertically by means of a cam disk 31.

A first connecting piece 80 is fastened to the high-pressure fuel pump 28, which first connecting piece forms the first low-pressure connection 20. A second connecting piece 81, on which the second low-pressure port 21 is based, is also fastened to the high-pressure fuel pump 28.

The high-pressure fuel pump 28, which is only schematically illustrated in fig. 1, is illustrated in fig. 2 to 4 in a plurality of views in detail.

The exemplary high-pressure fuel pump 28 has a pump housing 40, which comprises a pump body 41 and a pump cover 42, which is attached thereto, for example, in a non-detachable manner. The pump body 41 and the pump cover 42 may be connected to each other by a weld, for example.

On the side of the pump body 41, for example, a first connector 80, a second connector 81, an outlet 90 in the form of a third connector 82 and the flow control valve 46 are fastened in a non-detachable manner. The flow control valve 46 has the function of a controllable inlet valve of the high-pressure fuel pump 28.

The fluid connection between the low-pressure chamber 43 arranged below the pump cover 42 and the nipple 80 is established by a first connection hole 51 extending in the axial direction in the pump body 41.

A second connection hole, not shown, also extending in the axial direction in the pump body 41 connects the low pressure chamber 43 with the inlet side of the flow control valve 46.

In response to the hydraulic pressure conditions and to the actuation, the flow control valve 46 is opened into the delivery chamber 44 or closed in the opposite direction.

By the upward movement of the piston 30, the medium located in the delivery chamber 44 is compressed and delivered, for example, to the high-pressure rail 32 via the outlet valve 48 and the outlet 90, which open away from the delivery chamber 44. The pressure-limiting valve 49 is connected in anti-parallel to the outlet valve 48 in order to prevent inadmissible high pressures in the high-pressure region of the fuel system 10.

The stepped chamber bore 53 connects the low-pressure chamber 43 with a compensation chamber 57 arranged below the pump body 41, which is delimited on its underside by a seal carrier 25 fastened to the pump body 41.

The first, second and third connecting

pieces

80, 81, 82 are configured as identical parts, i.e. they are produced in the same manner.

As can be seen from fig. 5, the sleeve-shaped throttle element 75 is pressed into the second socket 81, i.e. the outer diameter 75A of the throttle element 75, which is embodied as a sleeve, has an interference fit in comparison with the inner diameter 81l of the second socket 81, is inserted into the second socket 81 and is fixed there at least in a friction-locking manner.

The inner diameter 75I of the throttle element 75 can be, for example, half the inner diameter of the second connecting piece 81l or even smaller.

Claims

1. Fuel pump (28) for a fuel system (10) of an internal combustion engine, wherein the fuel pump (28) has a delivery chamber (44) which is arranged in a pump housing (40) and is bounded by a pump piston (30) which is movable in an axial direction, wherein the fuel pump (28) has an inlet valve (46) which opens out from a low-pressure chamber (43) into the delivery chamber (44), wherein the fuel pump (28) has an outlet valve (48) which opens out away from the delivery chamber (44) in the direction of an outlet (90), wherein a first low-pressure connection (20) is provided on the pump housing (40) through which fuel can pass into the low-pressure chamber (43) and/or flow out of the low-pressure chamber (43), wherein a second low-pressure connection (21) is also provided on the pump housing (40), the fuel can flow into the low-pressure chamber (43) and/or out of the low-pressure chamber (43) via the second low-pressure connection, wherein the first low-pressure connection (20) is designed as a first connection piece (80) arranged on the pump housing (40), wherein the second low-pressure connection (21) is designed as a second connection piece (81) arranged on the pump housing (40), characterized in that the first connection piece (80) and the second connection piece (81) are designed as structurally identical components to one another, which are fastened to the pump housing (40), and in that a throttle element (75) is pressed into the second connection piece (81).

2. The fuel pump according to claim 1, characterized in that the pump housing (40) has a pump body (41) and a pump cover (42) fitted on the pump body (41) such that the low-pressure chamber (43) is formed between the pump body (41) and the pump cover (42), and the first nipple (80) and the second nipple (81) are fastened on the pump body (41) in a radial direction.

3. The fuel pump according to claim 1, characterized in that the pump housing (40) has a pump body (41) and a pump cover (42) fitted on the pump body (41) such that the low-pressure chamber (43) is formed between the pump body (41) and the pump cover (42), and in that the first nipple (80) is fastened radially on the pump body (41) and the second nipple (81) is fastened on the pump cover (42), or in that the second nipple (81) is fastened radially on the pump body (41) and the first nipple (80) is fastened on the pump cover (42).

4. Fuel pump according to any one of the preceding claims, characterized in that the outlet (90) is configured as a third nipple (82) which is of identical construction to the first nipple (80) and the second nipple (81).

5. Fuel pump according to any of the preceding claims, characterized in that the nipple (80, 81, 82) is welded on the pump housing (40).

6. Fuel pump according to any of the preceding claims, characterized in that the throttle member (75) reduces the flow cross section (81l) of the second joint (81) by 50% or more.

7. A fuel pump according to any one of the preceding claims, characterized in that the throttle member (75) is configured as a sleeve.

8. Fuel pump according to one of the preceding claims, characterized in that a further component is pressed into the second nipple (81).