CN110594063B - fuel high pressure pump - Google Patents

Abstract

The invention relates to a high-pressure fuel pump (10) for a fuel injection system of an internal combustion engine, comprising a pump housing (12) which comprises a housing cover (26), and an inlet connection (30) which is fastened to the housing cover (26) and in which a filter device (32) is arranged. It is proposed that the filter device (32) is held in the inlet connection (30) with a radial play (72) in the axial direction.

Description

fuel high pressure pump

technical field

The invention relates to a high-pressure fuel pump for a fuel system of an internal combustion engine.

Background technique

High-pressure fuel pumps are known on the market which belong to the fuel injection system of an internal combustion engine. These high-pressure fuel pumps comprise a mostly approximately cylindrical housing body in which a delivery piston is movably guided. A bell-shaped housing cover is fastened to the end faces of the housing body, beneath which a pressure damper, in most cases a diaphragm damper, is arranged. The housing cover can be designed as a thin-walled sheet metal profile. The fuel is supplied to the high-pressure fuel pump via an inlet connection, which is fastened to the housing, for example by welding. A filter device is arranged in the inlet socket and holds a force fit in the inlet socket.

Contents of the invention

The object of the present invention is to realize a high-pressure fuel pump which is durable and can be produced cost-effectively.

This task is solved by the high-pressure fuel pump according to the invention. Advantageous refinements of the invention are given in a preferred embodiment. Furthermore, the features that are essential to the invention are found in the following description and drawings.

The high-pressure fuel pump according to the invention for a fuel injection system of an internal combustion engine comprises a pump housing which in turn comprises a housing cover. The housing cover can be configured as a cap-shaped and thin-walled sheet metal profile and is usually located on the end side of an essentially cylindrical housing in which the delivery piston is movable. way is guided. A pressure damper, which is intended to damp pressure pulsations on the low-pressure side, can be arranged in the space enclosed between the housing and the housing cover.

Also associated with the high-pressure fuel pump is an inlet connection, which is attached to the housing cover. For example, the inlet connection can be made of metal and protrude from the housing cover in the radial or axial direction of the high-pressure fuel pump. During operation of the high-pressure fuel pump, the inlet connection is connected to a fuel supply on the low-pressure side, for example to an outlet of a preferably electric pre-feed pump. Fuel is supplied to the fuel high pressure pump via the inlet connection. In order to protect the high-pressure fuel pump against contamination present in the fuel, a filter device is arranged in the inlet connection. According to the invention it is proposed that the filter device is held axially in the inlet connection with radial play.

According to the invention, for fastening the filter device in the inlet connection, the previously used radial pressure connection of the filter device in the inlet connection is dispensed with, instead the filter device is held in a generally very small radial play. Entrance taking over. This has the advantage that temperature-dependent warping of the inlet connection, which is caused in particular when connecting the inlet connection to the housing cover by means of thermal methods, does not affect the holding of the filter device in the inlet connection. Since the outer diameter of the filter device no longer has a sealing and fixing function, the corresponding outer tolerances of at least that section of the filter device by which it is held in the inlet connection can be selected to be very large, thereby reducing manufacturing costs. It is still possible to achieve a sufficient holding force of the filter device in the inlet connection piece and to ensure that the filter cloth of the filter device is not damaged. It is advantageous here if the axial retaining device of the filter device is capable of compensating changes in the axial length of the filter device within a certain range.

A refinement of the invention is characterized in that the filter device rests at least on the first axial side against a first annular holding element which is fixed relative to the inlet connection at least in the first axial direction. The course of the inner wall of the inlet connection can thus be configured relatively simply, whereby the manufacturing costs are kept low.

A refinement of the invention is characterized in that the filter device additionally rests on a second axial side opposite the first axial side on a second holding element which is annular and at least along the A second, opposite axial direction is fixed relative to the inlet nozzle. The filter device is thus held in the axial direction between the two holding elements, whereby the inner wall of the inlet connection piece can be constructed particularly simply, whereby the manufacturing costs are kept low.

A refinement of the invention is characterized in that at least one of the retaining elements is formed by a locking ring which is held in a circumferential groove in the inner wall of the inlet connection. Such grooves can be introduced very cost-effectively into the inner wall of the inlet connection. Even in the case of strongly fluctuating inner diameters of the inlet connection, the proposed locking ring enables a secure fixation due to its split shape.

A refinement of the invention is characterized in that at least one of the retaining elements is formed by a compression sleeve which is pressed against the inner wall of the inlet connection. Instead of or in addition to the retaining element designed as a locking ring, the retaining element can thus be fixed without a groove in the inner wall of the inlet connection, thereby again reducing the manufacturing costs.

A refinement of the invention is characterized in that at least one of the retaining elements comprises an annular sealing element, preferably is formed of such an annular sealing element. In this way, a reliable seal is achieved between the filter device and the inlet connection, so that it is ensured that contamination in the fuel cannot pass through the filter device into the interior of the high-pressure fuel pump. Advantageously, in this case the sealing element is designed as an axially acting sealing element.

A refinement of the invention is characterized in that the annular sealing element comprises an axial seal and is partially received in a groove formed on an axial shoulder of the inner wall of the inlet connection. This also reduces the manufacturing costs, since a simple O-ring can be used as the sealing element, which due to its spring elasticity acts against the other holding element to load the filter device so that the filter device is secure and unreliable in the axial direction. is kept in motion. In this case, the sealing of the filter device relative to the inlet connection is independent of, for example, temperature-dependent warping of the inlet connection due to the axial seal.

A refinement of the invention is characterized in that the filter device has a cylindrical base section and a filter section extending from the base section, wherein the above-mentioned first axial side and/or the above-mentioned second axial side exists on the base segment. In this filter device, therefore, the holding function is separated from the filter function, so that damage to the filter section and thus a restriction of the filter function is avoided by holding the filter device in the inlet connection. Usually, the base section is designed as a rigid and solid ring, whereas the filter section is designed as a pot-shaped section extending axially from the base section, the peripheral wall of which is made at least in sections of filter fabric.

A refinement of the invention is characterized in that a radial seal is arranged between the inner wall of the inlet connection and the outer wall of the filter device. In addition or as an alternative to the above-described axial seal, a simple seal between the filter device and the inner wall of the inlet connection can be achieved in this way, for example using two retaining elements formed by locking rings or compression sleeves.

A refinement of the invention is characterized in that the inlet connection is welded, soldered or pressed to the housing cover. These connection methods are cost-effective and ensure a reliable and permanent fluid-tight connection between the inlet connection and the housing cover.

Description of drawings

Embodiments of the present invention will be described below with reference to the drawings. Shown in the accompanying drawings:

FIG. 1 is a partial section through a first embodiment of a high-pressure fuel pump with an inlet connection and a filter device arranged therein,

Figure 2 Sectional view of the area of the inlet connection and filter unit of Figure 1,

FIG. 3 is a view similar to FIG. 2 of a second embodiment of the inlet connection and the filter device arranged therein, and

FIG. 4 is a view similar to FIG. 2 of a third embodiment of the inlet connection and the filter device arranged therein.

In the figures, functionally equivalent elements and regions have the same reference symbols in different embodiments.

Detailed ways

In FIG. 1 , a high-pressure fuel pump for an internal combustion engine, not shown in any further detail, has the reference numeral 10 as a whole. The high-pressure fuel pump 10 has a generally substantially cylindrical pump housing 12 in or on which the main components of the high-pressure fuel pump 10 are arranged. The high-pressure fuel pump 10 thus has an inlet/flow control valve 14 , a delivery piston 18 which is arranged partly in a delivery chamber 16 and can be set in reciprocating motion by a drive shaft (not shown), an outlet valve 20 and a pressure limiting valve 22 .

The pump housing 12 comprises a substantially cylindrical housing body 24 and a housing cover 26 which is attached to the end face of the housing body and connected thereto in a fluid-tight manner. The housing body 24 and the housing cover 26 are made of metal, the housing body 24 here being made of a thin-walled sheet metal material. A pressure damper 28 , which is configured in the present example as a diaphragm damper, is arranged in a space (no reference number) formed between housing cover 26 and housing body 24 , on which a cylindrical And a tubular inlet socket 30 , which now projects radially laterally by way of example. A filter device 32 is arranged in the inlet connection 30 . This is discussed in more detail below with reference to FIG. 2 . The inlet connection 30 is connected to a low-pressure area 34 , for example to an outlet of an electric pre-infusion pump.

During operation, the delivery piston 18 draws fuel (in the present example gasoline) into the delivery chamber 16 via the inlet connection 30 and the inlet and flow control valve 14 during the suction stroke. During the delivery stroke, the fuel present in the delivery chamber 16 is compressed and discharged via the outlet valve 20, for example into the high-pressure region 36, for example to the fuel collecting line (“rail”), where the fuel is stored under high pressure . The high-pressure area 32 is connected to the high-pressure fuel pump 10 via an outlet connection 38 . In this case, the quantity of fuel discharged during the delivery stroke is regulated by a solenoid-actuated inlet and flow control valve 14 .

Reference is now made to FIG. 2 , in which a section of the inlet connection 30 and the filter device 32 is enlarged and shown in more detail. First, the filter device 32 will be described: it comprises a cylindrical base section 40 and a cylindrical and pot-shaped filter section 42 protruding from the base section. The base section 40 is designed as a solid plastic or metal part, while the filter section 42 is at least partially produced, for example in the region of its peripheral wall, by a filter fabric made of plastic or metal. In this case, the filter device 32 can be produced as a one-piece part. The base section 40 has a larger outer diameter than the filter section 42 . In this way, an end-side annular surface 48 pointing in the first axial direction 46 is formed on the first axial side 44 of the base section 40 pointing in the first axial direction 46 . The base section 40 has a second axial side 50 which is opposite the first axial side 44 and points in a second axial direction 52 . The second axial direction 52 is opposite the first axial direction 46 . On the second axial side 50 , a circular end face 54 pointing in the second direction 52 is formed on the base section 40 .

The description now concerns the inlet socket 30 : it has a now stepped inner wall 56 . A circumferential circumferential groove 58 is introduced into this inner wall, in which a locking ring 60 is seated. Furthermore, an annular shoulder 62 pointing in the second axial direction 52 is formed by the stepped inner wall 56 , in which shoulder there is an axial groove 64 . An annular elastic sealing element 66 in the form of an axial seal, ie in the form of an O-ring, is seated in the axial groove.

It can be seen from FIG. 2 that the base section rests on the first axial side 44 with its annular surface 48 present there against the sealing element 66 , so that it forms the first retaining element 68 . It can also be seen from FIG. 2 that the base section bears against the locking ring 60 on the second axial side 50 , so that this locking ring forms a second holding element 70 for the filter device 32 . Due to the elasticity of the sealing element 66 , it presses the base section 40 against the locking ring 60 . In this way, the filter device 32 is held fixedly, ie substantially immovable, in the inlet connector 30 between the two holding elements 68 and 70 . Here, too, it can be seen from FIG. 2 that, viewed in the radial direction, there is a radial gap 72 between the inner wall 56 of the inlet connection 30 and the outer wall (without reference numerals) of the base section 40 .

The embodiment of FIG. 3 differs from the embodiment of FIG. 2 in that the second retaining element 70 is not formed by a locking ring but by an extrusion sleeve 74 which bears against the inner wall in a press fit in radial direction 56 are pressed in.

In the embodiment of FIG. 4 , the stepped inner wall 56 is again omitted. Instead, the two retaining elements 68 and 60 are formed by locking rings 60a and 60b which are arranged in circumferential grooves 58a and 58b. The sealing between the filter device 32 and the inlet connection piece 30 takes place in that in the inner wall 56 there is a further circumferential groove 76 in which the radial sealing device 66 in the form of an O-ring is placed . The radial seal 66 is arranged between the inner wall 56 of the inlet connection 30 and the outer wall (no reference number) of the base section 40 of the filter device 32 .

In all embodiments, the inlet connection 30 can be fastened to the housing cover 26 by welding, soldering or pressing.

Claims (11)

1. A fuel high-pressure pump (10) for a fuel injection system of an internal combustion engine, having a pump housing (12) and an inlet connection (30), the pump housing including a housing cover (26), the inlet connection being fixed on A filter device ( 32 ) is arranged on the housing cover ( 26 ) and in the inlet connection, characterized in that the filter device ( 32 ) is held axially on the In the inlet joint (30), wherein the filter device (32) has a cylindrical base section (40) and a filter section (42) extending from the base section, wherein the radial gap (72 ) is located between the inlet connection ( 30 ) and the cylindrical base section ( 40 ). 2 . The high-pressure fuel pump ( 10 ) according to claim 1 , characterized in that the filter device ( 32 ) rests against the ring at least on the first axial side ( 44 ) and at least in the first axial direction. ( 46 ) on a first holding element ( 68 ) fixed relative to the inlet connection ( 30 ). 3. The high-pressure fuel pump (10) according to claim 2, characterized in that the filter device (32) is additionally located on a second axial side (50) opposite to the first axial side (44) ) rests against an annular second retaining element ( 70 ) that is fixed relative to the inlet socket ( 30 ) at least in a second axial direction ( 52 ) opposite to the first axial direction ( 46 ). 4. The high-pressure fuel pump (10) according to claim 2 or 3, characterized in that at least one of the retaining elements (70) is constituted by a locking ring (60) held on the inlet connection (30) in the circumferential groove (58) in the inner wall (56). 5. The high-pressure fuel pump (10) according to claim 2 or 3, characterized in that at least one of the retaining elements (70) is formed by an extrusion sleeve (74) which bears against The inner wall (56) of the inlet connection (30) is compressed. 6. The high-pressure fuel pump (10) according to claim 2 or 3, characterized in that at least one of the retaining elements (68) comprises an annular sealing element (66). 7 . The fuel high pressure pump ( 10 ) according to claim 6 , characterized in that the annular sealing element ( 66 ) comprises an axial seal and is partially received in a groove ( 64 ), which is formed in the On the axial shoulder (62) of the inner wall (56) of the inlet joint (30). 8. The high-pressure fuel pump (10) according to claim 3, characterized in that the first axial side (44) and/or the second axial side (50) exist in the base section (40) on. 9. The high-pressure fuel pump (10) according to any one of claims 1 to 3, 7 and 8, characterized in that, between the inner wall (56) of the inlet joint (30) and the filter device (32 ) is arranged with a radial sealing device between the outer walls. 10. The high-pressure fuel pump (10) according to any one of claims 1 to 3, 7 and 8, characterized in that the inlet connecting pipe (30) is welded or brazed to the housing cover (26) welded or pressed. 11 . The high-pressure fuel pump ( 10 ) according to claim 6 , characterized in that at least one of the holding elements ( 68 ) is formed by the annular sealing element ( 66 ).

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