KR20180029891A - High pressure fuel pump - Google Patents

Abstract

The present invention relates to a high pressure fuel pump (10) provided with a fixing flange (50) that can be fixed to a support body (38) by a fixing means (52) in an installation location. According to the present invention, the high pressure fuel pump (10) includes a distance section (47), wherein the distance section (47) separates the support body from a fixing section (48) of the fixing flange (40) in the installation location.

Description

[0001] HIGH PRESSURE FUEL PUMP [0002]

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

The high pressure fuel pump includes a pump housing, which includes a fixed flange fixed thereto. The fixing flange includes a fixing section, and the fixing section is fixed at a mounting position with a fixing element for fixing to the supporting body. Due to the construction, the connection between the flange and the housing is exposed to severe mechanical loads due to compressive forces, vibrations and, in particular, clamping forces when the stationary element is a screw. The support may be, for example, a camshaft box, cylinder head or other housing. The stationary element may in particular be a screw. Screwing must ensure the fixation of the pump and thus ensure the continuous function of the pump. In this case, overload or failure of the threaded joint shall be prevented. As the operating pressure of the high-pressure pump increases, the reaction force of the pressure generation also increases, so the requirements for the screwing also increase. At the same time, the space available for threading becomes smaller and smaller.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-pressure fuel pump in which the connection between the high-pressure pump and the support is stable.

The above problem is solved by the high-pressure fuel pump according to claim 1. Preferred improvements are set forth in the dependent claims. Features important to the present invention are set forth in the following description and drawings, which may be important to the present invention, alone or in various combinations.

The present invention has the advantage that the high pressure pump is held down against the support under pre-stress by the distance between the support and the fastening section of the fastening flange at the installation location. This can provide a stable connection between the high pressure pump and the support, which can withstand the load, especially due to the vibration, temperature fluctuations and temperature gradients, and reaction forces due to pressure generation within the high pressure pump, over time. Especially when the fixing element is formed as a screw or a screw bolt, by this measure, the fixing element can be prevented from being loosened by the setting process. In addition, the proposed fixed design permits the use of a relatively inexpensive, limited elastic flange structure because of the reduced material, and the flange structure is made of, for example, a molded sheet.

In one embodiment of the high pressure pump, the distance section includes a collar projecting radially in the housing of the high pressure fuel pump. This allows for simple and inexpensive manufacture.

In another embodiment of the high-pressure pump, the securing means comprises a first working surface. The fixation flange also includes a second working surface in the securing section. In the installed position, the first working surface and the second working surface are pressed against each other. The first working surface and the second working surface are complementary to each other so that the securing means is exposed to a substantially pure tensile load when the securing section is displaced from the installed position to the tilted position. In this context, the securing section may be constructed such that the high-pressure pump is fixed on the support by means of securing means from a first position, which is a pre-installation position, in which the high-pressure pump is not yet secured on the support by means of a securing means, Position and is preferably at least partially elastic to a second position that is inclined relative to the first position. In particular, it is possible for the fixation flange to include a flange region that radially projects a radially projecting collar of the housing and has a fixed section. The flange area is spaced from the support at the pre-installed position. In the installed position, the flange region may be bent around the edge region of the collar so that the flange region and hence the stationary section are turned into the angled position. The free end of the flange region in the mounting position can be supported on the support. Nevertheless, the securing means is exposed to a substantially pure tensile load due to the design of the first and second working surfaces. The lifetime of the fixing means is prolonged because the bending moment does not act or hardly acts and only the tensile load or only the tensile load acts. Also, since relatively small fastening means can be used, the material of the fastening means can be saved. That is, the bending moment can be smaller, and thus weaker, fixing means can be used compared to the design of the fixing means, which is expected to act on the fixing means.

The first working surface and the second working surface may be formed flat or spherical or conical. In particular, it has been shown that a spherical design is desirable because a substantially pure tensile load of the fastening means is possible at different angled positions of the fastening section.

It is also possible that the fastening means comprise a washer and a first working surface is formed on the washer. Thus, the washer can ensure that the fastening means is exposed to a substantially pure load. Conventional fastening means, in particular screws, can be used, in particular without the need for special adjustments to be made for the practice of the present invention.

The fixed section of the fixed flange may also include a recess or protrusion, and the recess or protrusion may comprise a second functional surface. This provides a particularly simple high pressure pump. In particular, conventional fastening means, in particular screws, can be used here, too, without any special adjustment being required for the practice of the present invention.

In this context, recesses can be formed in the fastening section by molding or cutting. Thus, the recess can be formed in the fastening section in a very simple and inexpensive manner.

Further, the fixing element is formed as a screw having a screw head and a screw shaft, and the second operation surface is formed as a screw head supporting portion, and the lower surface of the screw head is perpendicular to a screw shaft extending through the screw shaft at the mounting position . Thus, a pure or nearly pure tensile force acts on the screw. As a result, relatively small screws can be used.

It is also possible for the lower surface of the screw head to be parallel to the upper surface of the support in the installation position. Thereby, a particularly simple and stable connection between the high-pressure pump and the support can be provided.

Alternatively, a screw bolt may protrude from the support instead of a screw which is screwed into the screw hole in the support, and a screw nut may be screwed onto the screw bolt as a fixing means. The stand stud is formed such that its longitudinal axis extends perpendicularly to the lower surface of the nut at the mounting location.

In another embodiment, it is possible to provide a support side thread for the screw, the thread being formed such that its longitudinal axis extends perpendicularly to the lower surface of the screw head at the installation location. Thus, the formation of the recess or protrusion on the fixed section can be omitted. The use of washers may also be omitted.

Finally, the lower surface of the screw head can form a maximum angle of +/- 1 DEG, preferably +/- 0.5 DEG, with the vertical line to the screw axis at the mounting position. Thus, certain flexibility is possible. Nevertheless, a nearly pure tensile load acts on the securing means.

Other features, applicability, and advantages of the present invention are set forth in the following description of the embodiments of the invention with reference to the drawings.

1 is a longitudinal cross-sectional view of a high-pressure fuel pump provided on a support with a pump housing and a fixing flange in a pre-installed position;
2 is a schematic view of the high pressure pump according to FIG. 1 according to the first embodiment and fixed to a support at the installation location;
Figure 3 is a schematic cross-sectional view of a portion of Figure 2;
Figure 4 is a view of Figure 2 according to an alternative second embodiment;

Functionally identical elements and regions are denoted by the same reference numerals in the drawings and are not described in detail again.

1, an entirety of a high-pressure fuel pump for an internal combustion engine, not shown, is indicated by 10. The high-pressure fuel pump 10 includes a substantially cylindrical pump housing 12 in which essential components of the high-pressure fuel pump 10 are disposed. The high-pressure fuel pump 10 includes an inlet / outlet control valve 14, a delivery piston 18 disposed in the delivery chamber 16 and reciprocating by a drive shaft (not shown), a discharge valve 20, 22).

A first channel 24 is disposed within the housing 12 and the channel extends coaxially with respect to the delivery chamber 16 and against the delivery piston 18 and extends from the delivery chamber 16 to the second channel 26 The second channel 26 is disposed at an angle of 90 degrees with respect to the first channel 24 and the pressure limiting valve 22 is received within the second channel 26. [ The longitudinal axis of the pump housing 12 is indicated generally at 28 in FIG. In the upper part of Fig. 1, a pressure damper 30 is disposed in the pump housing 12.

During operation, fuel is sucked into the delivery chamber 16 through the inlet and the positive control valve 14 during the intake stroke by the delivery piston 18. During the dispensing stroke, the fuel in the delivery chamber 16 is compressed and discharged through a discharge valve 20, for example into a high pressure zone (not shown), for example into a fuel manifold ("rail"), Is stored at a high pressure. The amount of fuel to be discharged during the delivery stroke is regulated by the electronically actuated inlet and outlet valves 14. If an unacceptable overpressure appears in the high pressure region, the pressure limiting valve 22 is opened, thereby allowing fuel to flow from the high pressure region into the delivery chamber 16. [

In the lower region 32 towards the support 38, the pump housing 12 has a circular outer contour. A centering section 34 is formed in the lower region 32 and the centering section 34 can be inserted into the receiving opening 36 of the support 38 formed as a cylinder head shown here only schematically. Thus, the high pressure pump is a "plug pump ".

An annular fastening flange 40 is secured to the lower region 32 of the pump housing 12. According to the present embodiment, the fixing flange 40 is secured to the pump housing 12 by welding 42. [ Of course, other known fixation possibilities are possible. In addition, the fixing flange 40 is manufactured by stamping as a sheet formed product made of special steel in this embodiment.

1, the flange region 44 of the securing flange 40, which projects radially perpendicularly to the longitudinal axis 28 from the pump housing 12, is spaced from the support 38 by a distance (d). This lies on the ring collar 46 of the pump housing 12 where the radially inner region of the flange region 44 likewise protrudes radially perpendicular to the longitudinal axis 28, (D) of the collar 46 in the direction of the collar 28, as shown in FIG. The ring collar 46 is formed as a distance section. The flange region 44 of the securing flange 40 includes a securing section 48 and the securing section 48 includes a through-hole 48 extending in the direction of the longitudinal axis 28, (50).

2 and 3, in order to fix the high pressure pump 10 to the support 38, the fixing means 52 is guided through the through-hole 50 of the fixing flange 40, 38 into the threaded holes 54 corresponding thereto. The fixing means (52) includes a screw (53). During the thread tightening process, the flange region 44 of the retaining flange 40 is substantially resiliently bent about the free end region of the ring collar 46 of the pump housing 12. In this case, the fixing flange 40 is bent such that the radially outer free end 56 of the fixing flange 40 is supported on the upper surface 58 of the supporting body 38, Respectively. Accordingly, the high-pressure pump 10 is preferably held down against the support 38. [ Because the locking flange 40 is primarily resiliently curved, the locking flange 40 applies the exemplary stress in this case particularly on the collar 46 of the pump housing 12 so that the high- Lt; RTI ID = 0.0 > 58 < / RTI > This allows the fixing flange 40 to apply the resistance force to the fixing means 52 as opposed to the holding force of the fixing means 52, so that it is preferably substantially prevented from being loosened during the setting process.

If the securing section 48 includes only the cylindrical through-hole 50 shown in the right-hand side of Figs. 2 and 3, as in the prior art, this causes the screw head 60 of each securing means 52 to be screw- ([Gamma]) with respect to the base 62. The angle? Corresponds to the bending angle? Of the flange region 44 from the preliminary installation position to the installation position. Thus, the screw head 60 is deflected from the screw shaft 64 extending through the screw shaft 62. This results in an undesirable bending load due to the bending moment on the fixing means 52. Nevertheless, in order to ensure reliable fixation of the high-pressure pump 10 to the support 38, the screw 53 is selected to be large enough to withstand the bending load permanently.

In order to prevent this undesirable bending load on the screw 53, a recess 66 is provided in the fastening section 48 according to the illustration on the left side of FIG. 2 (and according to the enlarged view of FIG. 3). The bottom surface 68 of the recess 66 defines a flat second working surface 72 formed as a screw head support. The working surface 72 interacts with the first working surface 70 formed complementary to the working surface 72 on the lower surface 73 of the screw head 60 of the screw 62, (52) is exposed only to pure tensile loads or only to a substantially pure tensile load at the installation location shown. This is because the working surface 72 forms an angle? With the main extension of the fixed flange 40, in particular. That is, it is inclined with respect to the main extension. The angle (?) Corresponds to the inclined position of the flange region (44) at the installation position. Thus, the working surface 72 compensates for the inclined position of the flange region 44 and hence the fixed section 48 at the mounting position, so that at the mounting position, the working surface 70 on the lower surface 73 of the screw head 60 Extends perpendicularly to the screw shaft 64 passing through the screw shaft 62. As shown in Fig.

3, the through-hole 50 is formed such that an undesirable bending load does not act on the fastening means 52. As shown in Fig. The diameter D ₅₀ of the through-hole 50 is larger than the diameter D ₆₂ of the screw shaft 62 in the region of the through-hole 50. There is a clearance or a gap between the screw shaft 62 and the through-hole 50. Therefore, the specific non-coaxiality between the longitudinal axis of the through-hole 50 and the longitudinal axis of the screw shaft 62 does not cause an undesirable bending load on the screw 53. [ 3, the longitudinal axis of the through-hole 50 forms an angle of inclination, that is, an angle a, with respect to the plane of the flange region 44. As shown in Fig.

When the high pressure pump 10 is fixed to the support 38, the longitudinal axis of the through-hole 50 is first inclined with respect to the longitudinal axis of the screw shaft 62 (when the screw 53 is not yet tightened) , The first working surface 70 also tilts with respect to the second working surface 72. The undesirable bending load on the screw shaft 62 is prevented or at least reduced by the clearance existing between the screw shaft 62 and the through-hole 50 before the mounting position. When the screw 53 is tightened, the fixed section 48 of the flange region 44 is elastically warped. The second working surface 72 is at least substantially parallel to the first working surface 70 and the longitudinal axis of the throughhole 50 is at least substantially coaxial with respect to the longitudinal axis of the screw shaft 62, to be. In the state where the high-pressure pump 10 is fixed to the support 38, that is, at the mounting position, there is no bending load on the screw shaft 62 or there is no substantial bending load.

In the embodiment according to FIG. 4, a recess 66 is formed in the stationary section 48. In this case, the recess 66 includes a spherical or conical working surface 72. The fixing means 52 includes a screw 53 and a washer 74. A washer 74 is inserted into the recess 66 and the lower surface of the washer 74 forms a complementary working surface 70 in this case. The screw head 60 is disposed on the washer 74 so that the screw 53 is also exposed to a pure bending load or a substantially pure bending load. The spherical design of the complementary function surfaces 68 and 72 has the advantage that the different inclined positions of the securing section 48 can be compensated so that the screw 53 receives a pure tensile load.

Overall, relatively small screws can be used because the screw 53 in the left portion of Figs. 2 and 3 is not subjected to a bending moment or is not subjected to a bending moment. In addition, the durability of the screw connection between the high-pressure pump 10 and the support 38 is remarkably increased.

In the embodiments shown in the drawings, a screw 53 is used as the fixing means and the screw 53 is screwed into the screw hole 54 in the support 38. [ In an embodiment not shown, screw bolts project from the support. A flange section having a through-hole is stuck on the screw bolt, and then the screw nut is screwed on the screw bolt, so that the fixed section is elastically bent in the above-described manner.

10 High-pressure fuel pump
38 support
40 Fixed Flange
47 Distance Section
48 stationary section
52 fixing means
66 recess
70 first working surface
72 second working face
74 washer

Claims (10)

A high-pressure fuel pump (10) having a fixing flange (40) that can be fixed to a support (38) by means of a fixing means (52)
The high pressure fuel pump 10 includes a distance section 47 which causes a distance between the support and the stationary section 48 of the stationary flange 40 at the installation location High pressure fuel pump. The high-pressure fuel pump according to claim 1, wherein the distance section includes a collar projecting in a radial direction on a housing of the high-pressure fuel pump (10). 3. A device according to claim 1 or 2, wherein said means for fixing (52) comprises a first working surface (70), said fixing flange (40) Wherein the first working surface (70) and the second working surface (72) are pressed against each other, wherein the first working surface (70) and the second working surface (72) So that the fixing means (52) is exposed to a substantially pure tensile load when the fixing section (48) is displaced from the installation position to the inclined position. The high-pressure fuel pump according to claim 3, wherein the first working surface (70) and the second working surface (72) are formed flat or spherical or conical. 5. A method according to claim 3 or 4, characterized in that said fastening means (52) comprises a washer (74), said first working surface (70) being formed on said washer . 6. A method according to any one of claims 3 to 5, wherein the securing section (48) of the securing flange (40) comprises a recess (66) or protrusion, the recess (66) (72). ≪ / RTI > 7. The high-pressure fuel pump according to claim 6, wherein the recess (66) is formed in the fixed section by molding or cutting. 8. A method according to any one of claims 3 to 7, wherein the securing means (52) comprises a screw (53) with a screw head (60) and a screw shaft (62) Wherein the lower surface 73 of the screw head 60 is perpendicular to the screw shaft 64 extending through the screw shaft 62 at the mounting position and / Is formed to be parallel to the upper surface (58) of the support (38) at the installation position. 9. The screw head according to claim 8, characterized in that a support-side thread for the screw (53) is provided, the screw being such that the longitudinal axis of the thread extends perpendicularly to the lower surface (73) Pressure fuel pump. 10. The screw head according to claim 8 or 9, characterized in that the lower surface (73) of the screw head (60) has a maximum angle of +/- 1 DEG, preferably +/- 0.5 DEG with the vertical line to the screw shaft (64) Pressure fuel pump.

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