WO2019185435A1

WO2019185435A1 - High-pressure fuel pump for a fuel injection system

Info

Publication number: WO2019185435A1
Application number: PCT/EP2019/057034
Authority: WO
Inventors: Yury Mikhaylov; Thomas Fuchs
Original assignee: Cpt Group Gmbh
Priority date: 2018-03-26
Filing date: 2019-03-21
Publication date: 2019-10-03
Also published as: DE102018204555A1

Abstract

The invention relates to a high-pressure fuel pump (10) comprising a pump piston (26) which, during operation, moves translationally between a pressure space (20) and a leakage space (24), the leakage space (24) having a leakage collection area (34) and a compensation area (40), and a low-pressure damper (58) being arranged in the compensation area (40), said damper being formed from a gas-filled tube (44) which is closed at both ends and is arranged helically in the compensation area (40)

Description

description

High-pressure fuel pump for a fuel injection system

The invention relates to a high-pressure fuel pump for loading aufschlag a fuel in a Kraftstoffein injection system with high pressure.

Such high-pressure fuel pumps are used in fuel injection systems to compress a fuel and thus to apply a high pressure. The fuel under high pressure is then injected by means of a fuel injection device in combustion chambers of an internal combustion engine. The pressure in gasoline internal combustion engines is in a range of 150 bar to 400 bar and in the selbrennkraftmaschinen in a range of 1500 bar to 3000 bar. The more fuel is compressed, the lower the emissions generated during the combustion process. This is particularly against the background of increasingly desired and legally required emission reduction of advantage.

Usually, these high-pressure fuel pumps are designed as piston pumps Kol, wherein the fuel is compressed by a Penk penkolben in a pressure chamber by a translational movement of the pump piston. Due to the uneven promotion of such piston pumps fluctuations in the volume flow can occur on a low pressure side of the high-pressure fuel pump, which are connected to pressure fluctuations in the overall system. For example, actively controlled intake valves cause during operation pressure pulsations on the low pressure side of the high-pressure fuel pump. As a result of these fluctuations or pressure pulsations can lead to filling losses in the high-pressure fuel pump, so that a correct dosage of can not be guaranteed in the internal combustion engine required amount of fuel. In addition, these pressure pulsations stimulate components of the high-pressure fuel pump to vibrate, which can cause unwanted noise and even damage to the individual components.

To damp these pressure pulsations low-pressure dampers are therefore used on the low pressure side, which work as hyd raulische memory which compensate for the fluctuations in Vo lumenstrom and thus reduce the resulting pressure pulsations. For this purpose, these low pressure damper usually deformable elements. If the pressure on the low pressure side rises, these elements deform, which creates space for the superfluous fuel in the volume flow. If the pressure drops again at a later time, the deformable element returns to its original shape, and the stored fuel is thus released again.

For example, low-pressure damper are known, which are mounted on a head portion of the high-pressure fuel pump. In addition to the highest possible volume intake, however, a further requirement for a low-pressure damper is that it occupies the smallest possible installation space. In addition, it should be as inexpensive and inexpensive as possible in the production.

The object of the invention is therefore to propose an improved in this respect high-pressure fuel pump.

This object is achieved with a high-pressure fuel pump with the feature combination of claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims. A high-pressure fuel pump for applying a fuel in a fuel injection system with high pressure has a housing with a housing bore, which forms a pressure chamber in which the fuel is subjected to high pressure at a first end region and at a second end region a Leückageraum. Further, the high-pressure fuel pump comprises a pump piston which is guided in one of a Pumpenkolbenfü approximately section of the housing formed Pumpenkolbenführungs area of the housing bore, and moves translationally during operation of the high-pressure fuel pump between the pressure chamber and the leakage chamber along a movement axis. The leakage chamber has a leakage catchment area and a compensation area, wherein the compensation area is arranged in a circle around the pump piston guide section of the housing and extends parallel to the movement axis starting from the leakage catch area in the direction of the pressure space. Furthermore, the high-pressure fuel pump comprises a low-pressure damper, which is arranged in the compensation area. The low-pressure damper is formed from a gas-filled, sealed on both sides tube which is arranged helically around the pump piston guide portion of the housing and extends from the leakage collecting area in the direction of the pressure chamber he stretches.

So far, it has been known to provide low-pressure damper at a head end of the housing of the high-pressure fuel pump. In contrast, it is now proposed to provide such a low-pressure damper within the housing of the high-pressure fuel pump, below the pump piston in the leakage chamber, the leakage fuel, which flows out along the pump piston from the pressure chamber, receives. At a head end of the high-pressure fuel pump so space for other elements is free. In addition, an external interface to be sealed eliminates the need since the low-pressure damper within the housing of the High-pressure fuel pump is arranged. In addition, the radiation of pump noise is no longer done outside, but in a downwardly adjoining engine block. As a result, the high-pressure fuel pump is quieter overall.

The leakage chamber of the high-pressure fuel pump is composed of two areas, namely a leakage collecting area and a compensation area. In this case, the leakage collecting area is arranged only just where the leakage fuel from the pump piston guide portion of the housing emerges. The compensation area provides the actual volume of the leaking space. The compensation area is particularly advantageous arranged annularly around the Pumpenkolbenführungsab section, which is advantageous in terms of Gesamtar architecture of the high-pressure fuel pump. In particular, the compensation area can therefore absorb and divert forces which, when the housing is attached to further elements of the housing

Fuel injection system occur in the housing. The low-pressure damper is now not only generally located in the leakage chamber, but also in this equalization area. It is particularly advantageous from finally in this compensation area of the leakage chamber, since the compensation area provides the largest volume for a low-pressure damper available, which can thus also be formed as large as possible. Therefore, it is possible to provide a Never derdruckdämpfer with a large volume capacity, yet requires no additional space of the high-pressure fuel pump, but the space used ver, which is available anyway.

In order to achieve a particularly good damper effect, the low-pressure damper is formed from a helical tube which extends along the axis of movement around the pump piston. winding around. A deformation of this tube and thus the damper function is parallel to a BEWE supply axis of the pump piston. To be as good as possible

To provide damper effect, it is therefore advantageous if as many turns of the pipe to the Pumpenkolbenfüh tion section are present in order to accommodate the largest possible Ar beitsfläche by a plurality of turns in the given space.

For this purpose, the tube is advantageously also designed as a flat tube with four side surfaces, wherein two first side surfaces are arranged perpendicular to the pump piston guide portion and two second side surfaces parallel to the pump piston guide portion, wherein the second side surfaces are formed parallel to the pump piston guide portion shorter than the first side surfaces perpendicular to the Pump piston guide section. That is, the tube has a flat and a high side in a cross-section along the axis of movement, the flat side providing a large working surface in a direction of deformation of the tube which is likely to be visible.

This allows the low-pressure damper dampen particularly well pressure pulsations.

The Leckageauffangbereich is advantageously limited by a log you processing shell, which is mounted pressed hole on a housing wall of the housing. Due to the compression of the sealing shell on the housing wall of the housing bore, the leakage area is sealed to the outside. The seal is further improved by the sealing shell is welded or screwed in addition to the compression.

Alternatively, the low-pressure damper is clamped between the housing wall and the pump piston guide section. Further alternatively, it is possible that the low-pressure damper is held by brackets which are provided on the housing wall and / or on the pump piston guide section and / or on the sealing shell, and which are clamped axially or radially.

Preferably, the low-pressure damper is fixed only at its respective end pieces, for example, on the device tray and / or on the housing wall.

Preferably, the tube is formed as a thin-walled tube having tube walls with a wall thickness that allows deformation of the tube walls at a predefined pressurization.

Advantageously, the tube is formed of a fuel-resistant and in particular a fuel-tight material. As a result, a functional performance of the low-pressure damper over its entire service life can be guaranteed.

Alternatively, however, it is also possible for the tube to be encased or coated on its outer surfaces facing the housing with a fuel-resistant and, in particular, fuel-tight material.

An advantageous embodiment of the invention will be explained in more detail with reference to the accompanying drawings. It shows:

Fig. 1 is a longitudinal sectional view of a high fuel

pressure pump with a low pressure damper; and Fig. 2 shows the low pressure damper of Fig. 1 in an enlarged

Presentation .

Fig. 1 shows a longitudinal sectional view of a fuel high-pressure pump 10, with the fuel 12 can be aufschlagt be high pressure. The high-pressure fuel pump 10 has a housing 14 with a housing bore 16. The housing bore 16 forms at a first end portion 18 a pressure chamber 20 in which the fuel 12 is subjected to high pressure during operation by the volume of the pressure chamber 20 is periodically reduced and enlarged. Furthermore, the housing bore 16 forms a leakage space 24 at a second end region 22.

The high-pressure fuel pump 10 has a pump piston 26 which is guided in the housing bore 16. For this purpose, the Ge häusebohrung 16 a special pump piston guide portion 28 which is formed by a pump piston guide portion 30 on the housing 14, which projects into the leakage chamber 24. The pump piston 26 moves during operation along a BEWE movement axis 32 translationally between the pressure chamber 20 and return space 24 up and down. By this movement of the pump piston 26 in the pressure chamber 20, fuel 12, which is located in this pressure chamber 20, compressed and thus subjected to high pressure. In this case, a small proportion of the fuel 12 flows down the pump piston guide region 28 between the pump piston 26 and the pump piston guide section 30 of the housing 14 down into the leakage chamber 24.

The leakage space 24 forms in the area which is formed along the movement axis 32 below the pump piston guide portion 30, a leakage collecting area 34, in which the fuel leakage from the pressure chamber 20 can be collected. So that no mixing of this leakage fuel with, for example, lubricating oil in the drive range of the pump piston 26, the leakage chamber 24 is fluid-tight with a log you seal shell 36 sealed, which is pressed onto a housing wall 38 of the housing bore 16 and possibly, additionally welded or screwed attached. Thus, the sealing shell 36 and the housing wall 38 each form a boundary for the leakage collecting area 34. The leakage chamber 24 has, in addition to the leakage collecting region 34, a compensation region 40, which realizes a plurality of functions. On the one hand, it serves to cushion a pressure change below the pump piston 26, which results from the movement of the pump piston 26. On the other hand, this compensation area 40 is designed so that it also forces that act on the housing 14 from outside the housing 14, for example, by attachment of the housing 14 to other elements of a fuel injection system, can derive.

For this purpose, the compensation area 40 is arranged annularly around the pump piston guide section 30. It extends parallel to the movement axis 32, starting from the leakage collecting area 34 in the direction of the pressure chamber 20.

In the leakage chamber 24, a low-pressure damper 42 is arranged, in such a way that it is located in the compensation region 40 of the leakage chamber 24. The low-pressure damper 42 is formed from a closed tube 44 on both sides, which is filled with gas and thus limits a damper volume 46. The tube 44 is helically arranged around the pump piston guide portion 30 of the housing 14 and extends from the leakage collecting area 34 to the pressure chamber 20 to. Thus, the low-pressure damper 42 largely fills the compensation area 40 and thus uses the available installation space below the pump piston 26 as efficiently as possible.

By providing the low-pressure damper 42 in the leakage chamber 24 of the high-pressure fuel pump 10, a maximum flexibility of the interfaces at the top of the high-pressure fuel pump 10 can be provided. For example, then an easy to measure valve at the upper end of the housing 16 are arranged axially to the pump piston 26, and thus a direct Supply suction from a reservoir, for example from a tank. Thus, the volumetric efficiency of the high-pressure fuel pump 10 can be increased.

Fig. 2 shows an enlarged view of the low-pressure damper 42 of FIG. 1.

The low-pressure damper 42, which is designed as a tube 44, is designed in particular as a flat tube 48 and has four side surfaces 50, 52. In this case, two first side surfaces 50 are arranged perpendicular to the pump piston guide portion 30 and two second side surfaces 52 are arranged parallel to the Pumpenkol benführungsabschnitt 30. The two second side surfaces 52 are formed shorter than the first two side surfaces 50. Since deformation of a cross section of the flat tube 48 is mainly axial to a winding direction of the helical tube 44, the ratio of the first side surfaces 50 to the second side surfaces 52 is preferably high chosen to accommodate the largest possible work surface by a large number of turns in the given space can.

For attachment, the low-pressure damper 42, for example, between the housing wall 38 and the Pumpenkolbenführungsab section 30 are clamped, preferably areas are used ver, which do not serve the function, for example, the respective end of the low-pressure damper. However, it is also possible that the housing wall 38 and / or the pump piston guide portion 30 and / or the sealing shell 36 ent speaking brackets (not shown), which are braced for example axially or radially and the low pressure damper 42 in the compensation area 40th hold. The tube 44 is advantageously formed as a thin-walled tube 44, wherein tube walls 54 have a wall thickness d, which allows a United deformation of the tube walls 54 aufschlagung at a predefined Druckbe. If, for example, it is known which pressure pulsations are to be expected in the high-pressure fuel pump 10 during operation-for example through the work of the pump piston 26 or through an active inlet valve-the material of the tube 44 can be formed in its wall thickness such that deformation only occurs the unwanted pressure pulsations occurs. Thus, the efficiency of the high-pressure fuel pump 10 can be further increased.

The tube 44 may for example be formed of a fuel-resistant material. It is also advantageous if the material is additionally fuel-tight. However, in an alternative embodiment, it is also possible to coat or coat the tube 44 with its outer surfaces 56 facing the housing 14 with the fuel-resistant or fuel-tight material. As a result, the life of the low-pressure damper 42 and its consistent performance can be ensured.

Claims

claims

A high pressure fuel pump (10) for pressurizing a fuel (12) in a fuel injection system of a high pressure internal combustion engine, comprising:

- A housing (14) having a housing bore (16) at a first end portion (18) has a pressure chamber (20) in which the fuel (12) is subjected to high pressure, and at a second end portion (22) has a leakage space ( 24);

- A pump piston (26) in one of a pump piston guide portion (30) of the housing (14) formed pump piston guide portion (28) of the housing bore (16) GE leads, and in operation of the high-pressure fuel pump (10) between the pressure chamber ( 20) and the leakage space (24) along a movement axis (32) translationally moved;

wherein the leakage space (24) has a Leckageauffangbereich (34) and a compensation area (40), wherein the compensation area (40) annularly around the Pumpenkolbenführungsab section (30) of the housing (14) is arranged and parallel to the axis of movement (32). starting from the leakage collecting area (34) in the direction of the pressure chamber (20) to extend; and

a low-pressure damper (42) arranged in the compensation area (40),

wherein the low-pressure damper (42) is formed from a gas-filled tube (44) closed on both sides, which is arranged in a lixiform manner around the pump piston guide section (30) of the housing (14) and extends from the leakage catch region (34) in the direction of the pressure chamber (20 ).

2. High-pressure fuel pump (10) according to claim 1,

characterized in that the tube (44) is formed as a flat tube (48) with four side surfaces, wherein two first side surfaces (50, 52) perpendicular to the pump piston guide portion (30) and two second side surfaces (52) parallel to the pump penkolbenführungsabschnitt (30) are arranged, wherein the second side surfaces (52) parallel to the Pumpenkolbenfüh approximately section (30) are formed shorter than the first side surfaces (50) perpendicular to the Pumpenkolbenführungsab section (30).

3. high-pressure fuel pump (10) according to any one of claims 1 or 2,

characterized in that the Leckageauffangbereich (34) by a sealing shell (36) is limited, which is pressed against a housing wall (38) of the housing bore (16) fixed.

4. high-pressure fuel pump (10) according to claim 3,

characterized in that the low-pressure damper (42) between the housing wall (38) and the pump piston guide section (30) is fixed clamped.

5. high-pressure fuel pump (10) according to claim 3,

characterized in that the housing wall (38) and / or the pump piston guide section (30) and / or the sealing shell (36) have brackets which are braced axially or radially and hold the low-pressure damper (42).

6. high-pressure fuel pump (10) according to any one of claims 1 to 5,

characterized in that the tube (44) is formed as a thin-walled tube (44) having tube walls (54) with a wall thickness (d) that allows deformation of the tube walls (54) at a predefined pressurization.

7. high-pressure fuel pump (10) according to one of claims 1 to 6 characterized in that the tube (44) is formed of a fuel-resistant and in particular a fuel-tight material.

8. High-pressure fuel pump (10) according to one of claims 1 to 6,

characterized in that the tube (44) is coated or coated on its outer surfaces (56) facing the housing (14) with a fuel-resistant and in particular fuel-tight material.

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