KR20190140406A - High-pressure fuel pump - Google Patents

Abstract

The present invention relates to a high pressure fuel pump (10) for a fuel injection system of an internal combustion engine, which comprises a pressure relief valve (22). The pressure relief valve (22) comprises a valve element (44) actuated by a valve spring (54). A support element (46) is disposed between the valve spring (54) and the valve element (44). There is a central through opening (48) in the support element (46), The central through opening (48) forms an annular contact area (60) for the valve element (44) towards the valve element (44). According to the present invention, the contact area (60) is penetrated by at least one fluid connection unit (62).

Description

High Pressure Fuel Pump {HIGH-PRESSURE FUEL PUMP}

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.

Such a high pressure fuel pump is disclosed in DE 10 2005 007 806 A1 and comprises a pump housing and a pressure relief valve. The pressure relief valve is received in a recess in the pump housing. An end section of the valve spring of the pressure relief valve is disposed in the cylindrical region of the recess, the end region comprising a cylindrical inner wall and a front end wall. The end section of the valve spring is supported on the end wall of the recess.

The pressure relief valve connects the outlet side high pressure region to the delivery chamber of the high pressure fuel pump in the open state. In this case, the pressure relief valve opens when the pressure difference between the outlet high pressure region and the delivery chamber of the high pressure fuel pump exceeds the limit. That is, by the pressure relief valve, the pressure in the outlet high pressure region is prevented from becoming unacceptably high.

It is an object of the present invention to provide a high pressure fuel pump, which improves the sealing between the valve element and the valve seat and the stability of the opening pressure of the pressure relief valve over its lifetime.

The problem of the present invention is solved by a high pressure fuel pump having the features of claim 1. Preferred embodiments of the invention are set forth in the dependent claims. In addition, features important to the present invention are shown in the following description and the drawings. Features may be important to the invention alone and in different combinations.

The high pressure fuel pump according to the present invention serves to deliver fuel in the fuel injection system of the internal combustion engine. As fuel, gasoline is preferably used. The high pressure fuel pump compresses the fuel to high pressure and delivers it to the injector, which injects the fuel directly into the associated combustion chamber of the internal combustion engine. The high pressure fuel pump comprises a pressure relief valve comprising a valve element actuated by a valve spring. The pressure relief valve limits the pressure in the high pressure region on the outlet side of the high pressure fuel pump to the maximum allowable value. If the pressure there exceeds the opening pressure of the pressure relief valve, the valve element separates from the valve seat against the force of the valve spring, so that fuel may flow back from the high pressure region into the delivery chamber of the high pressure fuel pump and / or into the low pressure region. Can be.

Between the valve spring and the valve element, a support element with a central through opening is arranged, which through the opening forms an annular contact area for the valve element. By this supporting element, the valve element is reliably supported against the valve spring, which is usually a coil spring. According to the invention, the contact area is penetrated by at least one fluid connection. This fluid connection allows the fuel to flow from one side of the contact area to the other side of the contact area, even when the valve element is in full contact with the contact area, when viewed in the axial direction of the support element.

By means of the measures according to the invention, since the cavitation is reduced in the contact area, the damage of the valve element is reduced and thus the reduction of the seal of the pressure relief valve during its lifetime is prevented. In addition, cavitation in the area on the valve body between the valve element and the valve seat assigned to the valve element is also reduced. This prevents or at least reduces damage to the valve element and valve seat. The reason is that the pressure wave can be discharged through the fluid connection between the valve element and the support element and thus weakened, so that the pressure wave coming out of the delivery chamber of the fuel injection pump is less reflected between the support element and the valve body. As a result, the risk of low pressure in the area of the valve seat, ie where the valve element contacts the valve body, is reduced, which in turn reduces the tendency of cavitation. Thus, the sealability between the valve element and the valve seat and the stability of the opening pressure of the pressure relief valve are improved over the lifetime.

An improvement of the invention is characterized in that the contact area comprises a conical ring face. In particular, with respect to a valve element having at least approximately a corresponding corresponding face, this can provide a reliable centering of the valve element with respect to the valve spring in a simple manner.

An improvement of the invention is characterized in that the fluid connection comprises at least one through channel. This type of fluid connection can be implemented very easily and provides a reliable connection from one side of the contact area to the other when viewed in the axial direction of the support element.

An improvement of the invention is characterized by the presence of a plurality of through channels in the contact area. In this case, the through channels may be uniformly distributed in the circumferential direction. This has the advantage that the abovementioned advantages are particularly implicit, as the cross section of the individual through channels can be kept relatively small, with the result that a fluid connection with a relatively large overall cross section is formed.

An improvement of the invention is characterized in that the through channel has a generally rectangular or semicircular cross section. This cross section can be implemented very easily, so the manufacturing cost is kept low.

An improvement of the invention is characterized in that the valve element is spherical. Such a valve element is very easy to manufacture and the manufacturing cost is kept low, and the advantages mentioned above are particularly evident in this spherical valve element. That is, if cavitation occurs and the spherical valve element is locally damaged, and the spherical valve element is rotated due to asymmetrical flow or other effects, the damaged point of the valve element is placed on the valve seat, reducing the sealability of the pressure relief valve. will be. As a result, the overall efficiency and the efficiency of the high pressure fuel pump will be reduced. All of this is avoided by the measures according to the invention.

Possible embodiments of the present invention are described below with reference to the drawings.

1 is a partial cross-sectional view of a high pressure fuel pump with a pressure relief valve,
2 is an enlarged view of a high pressure fuel pump region with a pressure relief valve,
3 is a cross-sectional view of the support element of the pressure relief valve,
4 is a perspective view of the support element of FIG. 3.

In FIG. 1, a high pressure fuel pump for an internal combustion engine, which is not shown in detail, is indicated by reference numeral 10. The high pressure fuel pump 10 includes a pump housing 12 that is generally cylindrical in shape, with substantial parts of the high pressure fuel pump 10 disposed in or on the pump housing 12. The high pressure fuel pump 10 is an inlet / amount control valve 14, a delivery piston 18, an outlet valve 20, and a pressure relief valve disposed within the delivery chamber 16 and capable of reciprocating by a drive shaft, not shown. (22).

A first channel 24 is disposed in the housing 12, the first channel 24 extending coaxially with the delivery chamber 16 and the delivery piston 18 and from the delivery chamber 16 to the second channel 26. ) Into a substantially cylindrical recess, wherein the second channel 26 is disposed at an angle of 90 ° with respect to the first channel 24, and within the second channel 26 a pressure relief valve ( 22 is accepted. The longitudinal axis of the pump housing 12 is indicated at 28 in FIG. 1 and the longitudinal axis of the recess 26 is indicated at 29. In the upper part of FIG. 1, the pressure damper 30 is disposed in the pump housing 12.

During operation, fuel (in this case gasoline for example) is sucked into the delivery chamber 16 via the inlet and both control valves 14 in the intake stroke by the delivery piston 18. During the delivery stroke, the fuel in the delivery chamber 16 is compressed and discharged through the outlet valve 20 into the high pressure region 32, for example, towards the fuel rail "rail", where the fuel is stored under high pressure. . The high pressure region 32 is connected to the high pressure fuel pump 10 via an outlet connection 34. The amount of fuel discharged during the delivery stroke is controlled by the electromagnetic inlet and volume control valve 14. If an unacceptable overpressure is given in the high pressure region 32, the pressure relief valve 22 is opened, so that fuel can flow from the high pressure region into the delivery chamber 16.

The pressure relief valve 22 connects the high pressure region 32 to the delivery chamber 16 of the high pressure fuel pump 10 in the open state, as described above. The pressure relief valve 22 opens when the pressure difference between the delivery chamber 16 of the high pressure fuel pump 10 and the outlet side high pressure region 32 exceeds the limit. By the pressure relief valve 22, the pressure in the outlet-side high pressure region 32 is prevented from being unacceptably high.

The parts of the pressure relief valve 22 will be described in more detail in particular with reference to FIG. 2. The pressure relief valve 22 first comprises a sleeved valve seat body 38, which is pressurized into the recess 26 and extends in the longitudinal direction 29 of the valve seat body 38. In channel 40. At the right end of the channel 40 in FIG. 2, a valve seat 42 is formed on the valve seat body 38, which valve seat 42 interacts with a valve element 44 in the form of a valve ball. A support element 46 is arranged on the side of the valve element 44 away from the valve seat 42, in the support element 46 in the longitudinal direction of the support element 46, ie in the longitudinal axis 29. There is a through opening 48 extending in parallel to.

On the side of the support element 46 away from the valve element 44, the support element 46 comprises a fin-like extension 50. On the left side of FIG. 2, the first end section 52 of the valve spring 54 designed as a helical spring is pushed on the extension 50. In the right side of FIG. 2, the second end section 56 of the valve spring 54 of the pressure relief valve 22 is disposed in the cylindrical end region 58 of the recess 26. On the side of the support element 46 towards the valve element 44, in particular as shown in FIGS. 3 and 4, the through opening 48 has an annular contact area for the valve element 44 towards the valve element 44. Form 60. If the annular contact area 60 is formed by a conical ring face, the annular contact area 60 comprises a conical ring face. As can be seen from FIG. 2, the valve element 44 is partially received within the annular contact region 60, so that the valve element 44 is defined by the longitudinal axis of the support element 46 by the annular contact region. 29).

The contact region 60 is penetrated by three through channels 62 uniformly distributed in the circumferential direction of the annular contact region 60 when viewed in the direction of the longitudinal axis 29 of the support element 46. The through channels can be contacted from one side of the contact region 60 when viewed in the direction of the longitudinal axis 29 of the support element 46, even when the valve element 44 contacts the contact region 60. Form a fluid connection to the other side of 60). In principle, other numbers and different arrangements of the through channels 62 are possible. It is also possible that the fluid connection is not caused by the through channels 62, but is caused by, for example, the roughness or roughness of the contact area 60. It can be seen from FIG. 4 that the through channels 62 have an overall rectangular cross section. In principle, however, other cross sections are possible, for example semi-circular cross sections.

During operation, pressure waves and / or flow may occur at different points at different points in different operating situations within the region of the pressure relief valve 22. By means of the through channels 62, even when the valve element 44 contacts the contact region 60, the fuel is in the support element 46 from the region in which the fuel lies between the valve seat body 38 and the support element 46. It can flow into the through opening 48, preventing extreme low pressure and the resulting cavitation.

This operating situation is, for example, a pressure wave from the delivery chamber 16 through the first channel 24 in a state where the pressure relief valve 22 is closed, and the second channel (where the pressure relief valve 22 is accommodated) 26) may occur when entering. This pressure wave is indicated by arrow 64 in FIG. The pressure wave 64 also propagates into the area between the valve seat body 38 and the support element 46 according to arrow 66 in the second channel 26. Due to the through channel 62, pressure waves can be emitted into the through opening 48, indicated by arrow 68 in FIG. 2. In this way, the reflection of the pressure waves 64, 66 in the valve element 44 and the valve seat body 38 becomes small, so that the valve seat 42 between the valve element 44 and the valve seat body 38 is reduced. The risk of developing strong low pressure in the zone is reduced. This reduces the tendency of cavitation in this area, preventing damage to the valve element 44 and the valve seat 42.

Another operating situation is given when the fuel flows in the direction of the first channel 24 past the outside of the support element 46 with the pressure relief valve 22 open. Because of this, a strong low pressure appears in the through opening 48 in the support element 46 and there is a risk of cavitation in the contact region 60 if there is no through channel 62 in the contact region 60. This may damage the valve element 44. This is also prevented by the through channels 62, because the through channels allow for (some degree of) pressure compensation over the contact area 60.

10 high pressure fuel pump
22 pressure relief valve
44 valve element
46 support elements
48 through opening
54 valve spring
62 Fluid Connection

Claims (7)

A high pressure fuel pump 10 for a fuel injection system of an internal combustion engine, comprising a pressure relief valve 22, the pressure relief valve 22 comprising a valve element 44 actuated by a valve spring 54. A support element 46 is disposed between the valve spring 54 and the valve element 44, a central through opening 48 is present in the support element 46, the central through opening 48 being In the high pressure fuel pump 10, which forms an annular contact area 60 for the valve element 44 towards the valve element 44.
High pressure fuel pump, characterized in that the contact area (60) is penetrated by at least one fluid connection (62). 2. The high pressure fuel pump of claim 1, wherein the contact region comprises a conical ring face (60). 3. The high pressure fuel pump of claim 1 or 2, wherein the fluid connection comprises at least one through channel (62). 4. The high pressure fuel according to claim 3, wherein a plurality of through channels 62 exist in the contact region 60, and the through channels 62 are preferably uniformly distributed in the circumferential direction. Pump. 5. The high pressure fuel pump according to claim 3 or 4, wherein the through channel (62) has a generally rectangular or semicircular cross section. 6. The high pressure fuel pump as claimed in claim 1, wherein the valve element is spherical. 7. 7. The high pressure fuel pump according to any one of claims 1 to 6, wherein the fuel is gasoline.

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