KR102288011B1 - high pressure fuel pump - Google Patents

Abstract

The present invention provides a piston (30) having a piston longitudinal axis (33), and a sealing device (54) radially surrounding the piston (30) and sealing the fuel side (50) against the oil side (52). A high pressure fuel pump (28) comprising: a seal (56), a seal carrier (58) in contact with the oil side end of the seal (56), and the fuel of the seal (56) a fastening element (60) in contact with a lateral end, wherein the seal carrier (58) extends at least as far as the fastening element (60) as viewed from the fuel side in the direction of the piston longitudinal axis (33), or The seal carrier 58 extends further than the lower face 83 of the fixing element side collar 64 , which faces the oil side 52 when viewed in the direction of the piston longitudinal axis 33 from the fuel side. 64 forms the fuel side end 65 of the fastening element 60 .

Description

high pressure fuel pump

The invention relates to a high-pressure fuel pump according to the preamble of claim 1 .

In fuel systems, a high-pressure fuel pump is used to compress fuel from a reserve pressure to the injection pressure required for fuel injection. Such high-pressure fuel pumps usually comprise at least one piston, which can be moved axially by means of a drive device formed by a cam or an eccentric disc. A seal disposed radially outward of the piston is supported by a seal carrier and a stationary element, usually embodied as a deep drawn element, and by separating the fuel side from the oil side, mixing of fuel and oil is minimized. The seal seals statically to the seal carrier and dynamically to the piston.

The prior art discloses a seal carrier in which a fastening element with a collar resting on the seal carrier on the fuel side is inserted.

The object of the present invention is to provide a high-pressure fuel pump which has more compact dimensions and which reliably seals the fuel side to the oil side.

The above problem is solved by a high-pressure fuel pump according to claim 1 . Due to this, the height of the high-pressure fuel pump is reduced, and the reliability of the sealing of the fuel side to the oil side is ensured.

Preferably, the seal carrier is formed in the form of a port and circumferentially surrounds the fastening element, which guarantees a secure fixation of the seal and an accurate positioning ability.

Preferably, the fastening element is formed in the form of a port. Due to this, the seal is reliably protected from the action of the piston against the stationary element during operation of the high-pressure pump. Thus, damage to the seal is prevented, and consequently the operational safety and life of the high-pressure pump are increased.

In a preferred embodiment, the fastening element comprises a connection with the seal carrier. This connection ensures that the fastening element cannot be displaced in the direction of the oil side along the piston longitudinal axis relative to the seal carrier by forces acting on the fastening element in the operating state of the pump. This ensures that the seal is reliably supported by the seal carrier and the fastening element during operation of the pump, without damage to the seal due to displacement of the fastening element.

The securing element may, but may not include, a collar defining the fuel side end of the securing element. By collar is meant a radially outwardly extending section of material that forms the fuel-side end of the fastening element, ie the part of the fastening element extending furthest in the direction of the fuel side. If the fastening element comprises such a collar, it is preferred that the connection is at least partially formed by the collar of the fastening element, in which case the collar of the fastening element is supported in a form-fitting manner on the stationary section of the seal carrier. This is a reliable embodiment of the connection. Said collar can also preferably absorb and transmit to the seal carrier an impact force exerted by the piston on the fastening element.

In particular, the extension of the collar of the fastening element in the radial direction should be no more than 3 mm, preferably no more than 2 mm, in particular no more than 1 mm, in particular no more than 0.5 mm. This allows the collar to sink into the seal carrier with little or no shaping. It is also preferred that the extension of the collar of the fastening element in the radial direction is not more than 2 times the material thickness of the collar, preferably not more than 1.5 times, in particular not more than 1 times. In the case of a compact design of the fastening element, an appropriately dimensioned collar can be easily manufactured.

In a preferred embodiment, the stationary section of the seal carrier comprises a chamfer on the seal carrier. Such a chamfer can desirably absorb the force exerted by the collar onto the seal carrier without, for example, exhibiting material removal that could compromise the functionality of the high pressure pump.

In this case, the chamfer on the seal carrier preferably extends at an angle between 35° and 55°, preferably between 40° and 50°, in particular 45° with respect to the longitudinal axis of the piston. The chamfer extending in this way enables the absorption of large forces exerted on the seal carrier by the collar of the fastening element and in some cases provides sufficient space for the collar present on the fastening element. A very high resistance to displacement of the fastening element and thus a particularly high operational safety is ensured.

In a preferred embodiment, the collar of the fastening element comprises on its lower face a collar-side chamfer, said chamfer at an angle of 35° to 55°, preferably 40° to 50°, in particular 45° relative to the longitudinal axis of the piston. is extended The collar-side chamfer extending in this way enables absorption of large forces exerted on the seal carrier by the collar of the fastening element and provides sufficient space, since the collar can similarly be applied to the seal carrier.

It is particularly preferred that the collars of the seal carrier and the fastening element each comprise the aforementioned chamfer. Due to this, the seal carrier and the collar of the fastening element can preferably contact each other, and the force can be transmitted in a particularly efficient and material-protective manner.

In an embodiment of the high-pressure pump according to the invention, the connection between the fixing element and the seal carrier is exclusively a pressure-fit connection. This can be realized in particular by means of a suitably strong press fit between the seal carrier and the fastening element. This has the advantage that the form-fitting elements do not have to be provided in the manufacturing process of the seal carrier and the fastening element, which enables cost-effective manufacturing.

Other features, applicability and advantages of the invention are set forth in the following description of an embodiment of the invention described with reference to the drawings, which features may be important to the invention alone and in different combinations.

1 is a schematic diagram of a fuel system for an internal combustion engine;
2 is an enlarged view of a part of a high-pressure fuel pump according to the present invention;
Fig. 3 is an enlarged view of a part of Fig. 2;
FIG. 4 is a view corresponding to FIG. 2 , of a further embodiment of a high-pressure fuel pump according to the invention;
FIG. 5 is a view corresponding to FIG. 2 of a further embodiment of a high-pressure fuel pump according to the invention;
6 is a view corresponding to FIG. 2 of another embodiment of a high-pressure fuel pump according to the invention;

1 shows in schematic diagram a fuel system 10 for an internal combustion engine, not shown. From the fuel tank 12 , fuel is drawn from the intake line 14 , the pre-delivery pump 16 , the low pressure line 18 , and the inlet 20 of the quantity control valve 24 operable by means of an electromagnetic actuation device 22 . ) to the delivery chamber 26 of the high-pressure fuel pump 28 . For example, both control valve 24 may be a force-openable inlet valve of high pressure fuel pump 28 .

The high-pressure fuel pump 28 is designed as a piston pump, the piston 30 being movable up and down along the piston longitudinal axis 33 by means of a drive device 32 designed as a cam, which is indicated by an arrow with reference numeral 34 . is schematically shown. Between the delivery chamber 26 and the discharge part 36 of the high-pressure fuel pump 28 is arranged hydraulically a discharge valve 40 designed as a spring-loaded check valve in FIG. can be opened with

The outlet 36 is connected to a high pressure line 44 and via said high pressure line 44 to a high pressure accumulator 46 (“common rail”). Also arranged hydraulically between the discharge part 36 and the delivery chamber 26 is a pressure limiting valve 42 , shown as a spring loaded check valve, said pressure limiting valve being able to open into the delivery chamber 26 . .

During operation of the fuel system 10 , a pre-delivery pump 16 delivers fuel from the fuel tank 12 to the low pressure line 18 . Both control valves 24 can be closed and opened depending on the respective fuel requirements. For this reason, the amount of fuel delivered to the high-pressure accumulator 46 is affected. The electromagnetic actuation device 22 is controlled by a control and/or regulation device 48 .

2 shows a lower part 49 of an embodiment of a fuel high-pressure pump 28 according to the invention. The piston 30 extends from the fuel side 50 to the oil side 52 . The fuel side 50 is sealed against the oil side 52 by a sealing device 54 . The sealing device 54 surrounds the piston 30 in the circumferential direction U. The radial direction 55 is indicated by a corresponding arrow. The sealing device 54 includes a seal 56 , a seal carrier 58 and a fastening element 60 .

The seal carrier 58 contacts the seal 56 at the lower end of the oil side as viewed in FIG. 2 of the seal 56 , in the operative position shown. The U-shaped portion 61 of the fastening element 60 is, in the operative position shown, slightly spaced from the fuel side upper end as viewed in FIG. 2 of the seal 56 . The seal carrier 58 extends further than the fastening element 60 when viewed from the fuel side in the direction of the piston longitudinal axis 33 . In other words, the fastening element 60 sinks into the seal carrier 58 .

The seal carrier 35 comprises a circumferential wall W extending substantially in the direction of the piston longitudinal axis 33 . Following the circumferential wall W on the oil side and perpendicular to the piston longitudinal axis 33 , a bottom B with a central opening O extends radially inward, through which opening O The piston 30 is extended. On the fuel side, the circumferential wall W projects from the piston, ie extends radially outwardly and leads to an upper section A extending perpendicular to the piston longitudinal axis 33 . From the radially outer edge of the upper section A, a connection region V extends in the direction of the oil side 52 and along the direction of the piston longitudinal axis. Accordingly, the seal carrier 58 is partially port-shaped with an opening O in the lower region of the port-shaped section TA.

The fastening element 60 is also formed in the form of a port. The circumferential wall BW of the fastening element 60 extends in the direction of the piston longitudinal axis 33 and runs on the oil side, ie at its lower end as viewed in the drawing, into the aforementioned U-shaped part 61 . The U-shaped part 61 forms the bottom BB of the fastening element 60 extending generally perpendicular to the piston longitudinal axis 33 . The U-shaped portion 61 includes a central opening BO, through which the piston 30 extends. The fastening element 60 is surrounded in the radial direction 55 by a seal carrier 58 formed in the shape of a port. In this case, the circumferential wall W of the seal carrier 58 contacts the circumferential wall BW of the fastening element 60 in a press-fit manner. The sealing device 54 is fixed in a press-fit manner to the pump housing 63 via the connection region V of the seal carrier 58 .

The fastening element 60 comprises a very short collar 64 , in the present case, which extends radially outwardly 55 , ie away from the piston, said collar 64 having a lower face 83 . The fuel side end 65 of the fastening element 60 is formed by a collar 64 . This means that the collar 64 represents the portion of the fastening element 60 that extends furthest to the fuel side 50 . The collar 64 of the fastening element 60 supports the fastening element 60 in a form-fitting manner to the stop section 66 of the seal carrier 58 . The stop section 66 includes a chamfer 68 . The chamfer 68 extends at an angle 82 of 45° with respect to the longitudinal axis 33 of the piston.

In the region of the press fit 70 , the fastening element 60 and the seal carrier 58 are connected to each other in a press-fit manner. In the embodiment shown in FIG. 2 , the fastening element 60 comprises a connection with a seal carrier 58 , said connection being on a pressure-fitting part by means of a press fit 70 , and on the stop section 66 . It includes a shape-fitting portion by the support of the collar 64 .

3 shows, in enlarged view, the area around the collar 64 and the stop section 66 . The (short) extension of the collar 64 of the fastening element 60 in the radial direction 55 in FIG. 3 is indicated by the reference numeral 74 . The material thickness of the collar is indicated by the reference numeral 78 . A chamfer 68 on the seal carrier 58 extends at an angle 82 with respect to the piston longitudinal axis 33 . In practice, the angle 82 of the chamfer 68 is, as described above, between 35° and 55°, preferably between 40° and 50°, in particular 45°. The extension 74 of the collar 64 is practically no more than 3 mm, preferably no more than 2 mm, in particular no more than 1 mm, particularly no more than 0.5 mm, or no more than twice the material thickness 78 of the collar 64; Preferably it is 1.5 times or less, Especially preferably, it is 1 times or less.

4 shows another embodiment of the high-pressure fuel pump 28 according to the invention, wherein the connection between the seal carrier 58 and the fastening element 60 is different from the embodiment shown in FIGS. 2 and 3 . .

The fastening element 60 does not include a collar 64 in this embodiment. The fuel side end 65 of the fastening element 60 is formed by the end face of the fastening element 60 . The connection between the seal carrier 58 and the fastening element 60 is exclusively a pressure-fit connection. Nevertheless, in order to ensure reliable operation of the high-pressure fuel pump 28, the fit of the press fit 70 is made stronger than in the embodiment shown in FIG.

FIG. 5 shows another embodiment of a high-pressure fuel pump 28 according to the invention, which differs from the embodiment shown in FIGS. 2 and 3 in that the seal carrier 58 does not have a chamfer 68 . . Thus, the seal carrier 58 extends further than the lower face 83 of the collar 64 facing the oil side 52 when viewed from the fuel side in the direction of the piston longitudinal axis 33 , but the seal carrier 58 . does not extend all the way to the fastening element 60 when viewed from the fuel side in the direction of the piston longitudinal axis 33 . In this embodiment, the collar 64 forms the fuel side end 65 of the fastening element 60 .

FIG. 6 is another embodiment of a high-pressure fuel pump 28 according to the present invention, which differs from the embodiment shown in FIG. 5 in that the collar 64 has a chamfer 84 on its lower face 83 . shows The chamfer 84 extends at an angle 86 of 45° with respect to the piston longitudinal axis 33 . In this embodiment, the seal carrier 58 extends further than the lower face 83 of the collar 64 towards the oil side 52 when viewed in the direction of the piston longitudinal axis 33 from the fuel side, but the seal carrier 58 does not extend all the way to the fastening element 60 when viewed from the fuel side in the direction of the piston longitudinal axis 33 . Again in this embodiment, the collar 64 forms the fuel side end 65 of the fastening element 60 .

During operation of the high-pressure fuel pump 28 , the piston 30 is moved up and down along the piston longitudinal axis 33 , as indicated by arrows 34 in FIGS. 2 and 4 . In this case, the U-shaped portion 61 of the fastening element 60 prevents the step S of the piston 30 from striking the seal 56 . The U-shaped portion 61 of the fastening element 60 is the axial stop of the seal 56 during operation of the high-pressure fuel pump 28 , and the loss of the piston 30 during transport or storage of the high-pressure fuel pump 28 . form a preventive part.

The connection between the seal carrier 58 and the fastening element 60 prevents the fastening element 60 from sliding towards the oil side 52 in the direction of the piston longitudinal axis 33 . In the embodiment according to FIGS. 2 and 3 and in the embodiment according to FIG. 4 , the connection is made in all operating states of the high-pressure fuel pump 28 , ie during operation of the pump, for all forces acting on the fastening element 60 . , are designed to be strong enough to rule out such slippage. The force acting on the stationary element 60 in the operating state of the high-pressure fuel pump 28 is mainly applied by the piston 30 to the stationary element 60 via the seal 56 .

28 high pressure fuel pump
30 piston
33 piston longitudinal axis
50 fuel side
52 oil side
55 radial
56 seal
58 seal carrier
60 fastening elements
64 colors
65 fuel side end
66 stop section
68 chamfer
74 extension
78 material thickness
83 lower side
84 chamfer

Claims (10)

A high-pressure fuel pump (28), a piston (30) having a piston longitudinal axis (33), and a seal radially surrounding the piston (30) and sealing the fuel side (50) to the oil side (52) a device (54) comprising a seal (56), a seal carrier (58) in contact with an oil side end of the seal (56), and a fuel side end of the seal (56) In the high-pressure fuel pump (28) comprising a fastening element (60),
The seal carrier 58 extends from the fuel side to at least the fastening element 60 when viewed in the direction of the piston longitudinal axis 33 , or the seal carrier 58 is connected to the piston longitudinal axis 33 ) extending further than the lower face 83 of the fixing element side collar 64 facing the oil side 52 from the fuel side when viewed in the direction of forming a side end 65;
The fastening element ( 60 ) comprises a connection with the seal carrier ( 58 ), the connection being the force by which the fastening element ( 60 ) acts on the fastening element ( 60 ) in the operating state of the high-pressure fuel pump ( 28 ). designed to be displaceable in the direction of the oil side (52) along the piston longitudinal axis (33) relative to the seal carrier (58) by
The connection is formed at least in part by the collar 64 of the fastening element 60 , the collar 64 of the fastening element 60 is shaped in the stop section 66 of the seal carrier 58 . supported in a fit-and-fit manner,
The stop section (66) of the seal carrier (58) comprises a chamfer (68) on the seal carrier (58), or the collar (64) comprises a chamfer (84) on its lower face (83) High pressure fuel pump (28), characterized in that. 2. High-pressure fuel pump (28) according to claim 1, characterized in that the seal carrier (58) is formed in part in the form of a port and surrounds the fastening element (60) in the circumferential direction (U). 3. High-pressure fuel pump (28) according to claim 1 or 2, characterized in that the fastening element (60) is formed in the form of a port. delete delete The high-pressure fuel pump (28) according to claim 1, characterized in that the extension (74) of the collar (64) of the fastening element (60) in the radial direction (55) is not more than 3 mm. 7. The method according to claim 6, characterized in that the extension (74) of the collar (64) of the fastening element (60) in the radial direction (55) is not more than twice the material thickness (78) of the collar (64). high pressure fuel pump (28). The high-pressure fuel pump according to claim 1, characterized in that the chamfer (68) on the seal carrier (58) extends at an angle (82) of 35° to 55° with respect to the piston longitudinal axis (33). 28). 2. The method according to claim 1, characterized in that the chamfer (84) of the lower face (83) of the collar (64) extends at an angle (86) of 35° to 55° with respect to the piston longitudinal axis (33). high pressure fuel pump (28). The high-pressure fuel pump (28) according to claim 1, characterized in that the connection between the fastening element (60) and the seal carrier (58) is exclusively a pressure-fitting connection (70).

Images