Fuel pump

Abstract

The fuel pump comprises a pump housing (16) and an inlet valve (12), which has a valve element (30) and an annular valve body (34), which has an annular valve seat (32) and which is fastened in the pump housing (16). It is proposed that the quotient of the total axial length (42) of the valve body (34) divided by the outer diameter (44) of the valve body (34) is at least 0.3.

Description

Technical Field

[0001] The invention relates to a fuel pump, in particular a high-pressure fuel pump, according to the preamble of claim 1. Background Art

[0002] DE 10 2015 219 537 A1 discloses a fuel system for an internal combustion engine having a high-pressure fuel pump. The high-pressure fuel pump is implemented with a spring-loaded inlet valve and a spring-loaded outlet valve. The inlet valve is constructed as a quantity control valve and has a tappet, which can load the valve element of the inlet valve to a forced open position by a spring during the delivery stroke of the fuel pump. By energizing the electromagnetic actuator of the quantity control valve, the tappet is pulled away from the valve element against the spring force, so that the valve element can be closed. In this way, the amount of fuel delivered by the fuel pump can be influenced. The inlet valve also includes a loading device in the form of a spiral spring, which loads the valve element of the inlet valve in the direction of the valve seat. The valve seat is constructed on an annular valve body, which is pressed (verstemmen) into the pump housing. Summary of the invention

[0003] The problem on which the invention is based is achieved by a fuel pump having the features of claim 1. Advantageous developments are mentioned in the dependent claims.

[0004] The fuel pump according to the invention has the following advantages: Compared with previous fuel pumps of this type, the fuel pump according to the invention can be operated continuously at a significantly higher system pressure. Compared with the typical system pressure of about 350 bar, the typical system pressure that can be continuously achieved with the fuel pump according to the invention is about 500 bar. In this case, the other elements of the previous fuel pump can remain completely unchanged. The fuel pump according to the invention does not cause any installation space restrictions. In addition, it is further possible to achieve a flow cross section with low throttling, and the wear characteristics of the contact with the valve element are also not affected.

[0005] Specifically, this is achieved by a fuel pump, in particular a high-pressure fuel pump for an internal combustion engine. Such fuel pumps are used not only in diesel internal combustion engines, but also in gasoline internal combustion engines. Usually, the fuel pump compresses the fuel to a very high pressure and delivers it to a fuel collecting line (rail), from which the fuel is injected directly into the associated combustion chamber of the internal combustion engine by means of an injector. The fuel pump according to the invention comprises a pump housing and a pump piston. The pump piston is guided in the pump housing. The fuel pump is therefore a piston pump.

[0006] The fuel pump comprises an inlet valve, which can be connected to an electric pre-feed pump, for example, via a fuel line. The inlet valve is usually designed in the manner of a non-return valve and has a valve element, which can be designed, for example, in the form of a plate. Usually, the inlet valve opens during the suction stroke of the fuel pump and is at least temporarily closed during the delivery stroke of the fuel pump. The inlet valve comprises an annular valve body, which has an annular valve seat, against which the valve element rests in a fluid-tight manner when the inlet valve is closed. A loading device, usually a spring, loads the valve element in the direction of the valve seat and, for example, presses the valve element onto or against the valve seat when the inlet valve is closed.

[0007] According to the invention, the quotient of the total axial length of the valve body divided by the outer diameter of the valve body is at least 0.3. The quotient proposed according to the invention is here within a particularly advantageous range which has proven to be optimal in terms of technology and economy.

[0008] In one embodiment, it is provided that the quotient of the total axial length of the valve body divided by the outer diameter of the valve body is in the range of 0.34. In this case, the above advantages are particularly significant.

[0009] In one embodiment, the valve body has an overall axial length of at least 4.6 mm. Such a valve body can also be fitted very easily into existing pump housings.

[0010] In one embodiment, the axial total length of the valve body is in the range of about 5.5 mm. Such a valve body can also be easily adapted to existing pump housings and is very stable.

[0011] In one embodiment, the quotient of the total axial length of the valve body divided by the inner diameter of the valve body is at least 0.6. It should be noted that the large inner diameter of the valve seat supports a favorable flow pressure drop. However, due to the increasing pressure load in the closed state of the inlet valve, this can be disadvantageous in terms of the wear of the valve seat in contact with the valve element. In this case, under unfavorable dimensional conditions, relative movements between the valve element and the valve seat can occur, and corresponding friction work can occur. Therefore, the goal is to produce as little relative movement as possible between the valve seat and the valve element when the pressure changes, but at the same time ensure high valve dynamics. The proposed minimum ratio between the axial total length of the valve body and the inner diameter of the valve body is an optimized value that allows high valve dynamics with low wear.

[0012] In one embodiment, it is provided that the quotient of the total axial length of the valve body divided by the inner diameter of the valve body is in the range of 0.82. In the case of such values, the above-mentioned advantages are particularly significant.

[0013] In one embodiment, the pump housing is made of 1.4418 steel or 1.4057 steel. In the case of such steel, the above advantages are particularly significant.

[0014] In one embodiment, it is provided that the valve body preferably has an at least substantially constant outer diameter and is screwed into the pump housing. This simplifies the processing of the outer contour and enables a releasable fastening of the valve body in the pump housing.

[0015] In one embodiment, the valve body is pressed into the pump housing. For this purpose, the valve body preferably has a circumferential step, ie a shoulder, on its outer circumference. This fastening of the valve body in the pump body is very reliable and cost-effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The accompanying drawings show:

[0017] Figure 1 shows a longitudinal section through a fuel pump having a pump housing and an inlet valve having a valve body and a valve element;

[0018] Figure 2 Show Figure 1 An enlarged detail of a fuel pump of FIG. 1 , the enlarged detail particularly showing the inlet valve; and

[0019] Figure 3 Show Figure 1 and Figure 2 Exploded view of the inlet valve in longitudinal section. DETAILED DESCRIPTION

[0020] The high-pressure fuel pump is designed as a piston pump. Figure 1 1 and 2. The fuel pump 10 is generally designated by the reference numeral 10. The fuel pump 10 belongs to a fuel system (not shown in detail) of an internal combustion engine. During operation, the fuel pump usually compresses the fuel to a system pressure of at least 500 bar and delivers the fuel to a fuel rail, to which a plurality of injectors are attached, which inject the fuel into the combustion chambers of the internal combustion engine.

[0021] The fuel pump 10 comprises an inlet valve 12 and an outlet valve 14 designed as a non-return valve, as well as a pump housing 16. The inlet valve 12 will be discussed in more detail below. In the pump housing 16, there is a receiving opening 18 for a pump piston 20. The pump piston 20 can move in the receiving opening 18 parallel to the longitudinal axis 22 of the receiving opening 18. For this purpose, a drive device (not shown in the figure) is used. For example, the drive device can be a camshaft or an eccentric shaft of an internal combustion engine.

[0022] In the present case, the pump piston 20 is designed as a stepped piston by way of example and comprises a section 24 with a smaller diameter and a section 26 with a larger diameter. The section 26 with a larger diameter of the pump piston 20 delimits a delivery chamber 28 together with the pump housing 16. The delivery chamber is fluidically connected to the inlet valve 12 and the outlet valve 14 via a passage not further labeled. The pump housing 16 can be designed as a generally rotationally symmetrical or polygonal component. The pump piston 20 is received in the pump housing 16 in a receiving opening 18, which is designed as a stepped blind hole and has the following sections, each of which has a different diameter.

[0023] In the present case, the inlet valve 12 is designed as a quantity control valve. Figure 2 and Figure 3 1 , it can be seen in detail that the inlet valve 12 has a valve element 30, which is plate-shaped in the present example, and an annular valve seat 32, which is formed on an annular valve body 34. The valve body 34 has a longitudinal axis 35, and the valve seat 32 extends coaxially with the longitudinal axis 35 in the axial direction. A spring 36 loads the valve element 30 toward the annular valve seat 32. For this purpose, the spring 36 is supported on a so-called valve pot 38. The load device is designated by 40, which can forcibly keep the inlet valve in the open position by means of a tappet 41 for controlling the amount of fuel delivered by the fuel pump 10.

[0024] exist Figure 1 When the pump piston 20 in the pump moves downward (suction stroke), the valve element 30 is lifted from the valve seat 32 against the force of the spring 36, so that the fuel can flow through the inlet valve 12 into the delivery chamber 28. Figure 1 When the pump piston 20 in the delivery chamber 28 moves upward (delivery stroke), the valve element 30 is pressed against the valve seat 32 by the force of the spring 36 and the gradually increasing pressure in the delivery chamber 28 (if the valve element 30 is not forcibly pressed into the open position by the loading device with the tappet 41). After reaching a certain pressure, for example, after reaching a system pressure of approximately 500 bar in the present case, the outlet valve 14 opens, so that fuel with the system pressure can flow out of the outlet valve 14, for example, toward the fuel rail.

[0025] As from Figure 2 and Figure 3 As can be seen, the valve body 34 is designed in an annular shape. The total axial length of the valve body 34 is denoted by 42, and the maximum outer diameter of the valve body 34 is denoted by 44. The valve body 34 has an inner through-opening 46 extending in the axial direction of the valve body 34 and having an inner diameter 48. The radial outer circumference 50 of the valve body 34 has a stepped shoulder 52. Thus, the outer circumference 50 has a section with a maximum outer diameter 44 adjacent to the valve seat 32 in the installed position and a section with a minimum outer diameter 54 arranged away from the valve seat 32.

[0026] The quotient of the total axial length 42 of the valve body 34 divided by the maximum outer diameter 44 of the valve body 34 is currently at least 0.3, and is currently exemplarily approximately 0.34. The total axial length 42 of the valve body 34 is currently at least 4.6 mm, and is typically approximately 5.5 mm. The quotient of the total axial length 42 of the valve body 34 divided by the inner diameter 48 of the inner through opening 46 of the valve body 34 is at least 0.6, and is currently exemplarily approximately 0.82.

[0027] In the present case, the pump housing 16 is produced, for example, from 1.4418 steel or 1.4057 steel. In addition, the valve body 34 is pressed into the opening 56 of the pump housing 16 by means of a press fit 58 , wherein the press fit 58 acts on the shoulder 52 of the valve body 34 .

[0028] In an embodiment not shown, the valve body has a substantially constant outer diameter, i.e. has no shoulder. In this embodiment not shown, a thread can also be present on the radial outer peripheral surface of the valve body, by means of which the valve body is screwed into the opening of the pump housing. In addition to the threaded connection, the valve body can also be press-fitted.

Claims

1. A fuel pump (10) comprising a pump housing (16) and an inlet valve (12), wherein the inlet valve has a valve element (30) and an annular valve body (34), the valve body having an annular valve seat (32) and being fastened in the pump housing (16), characterized in that: A quotient of a total axial length (42) of the valve body (34) divided by an outer diameter (44) of the valve body (34) is at least 0.

3.

2. The fuel pump (10) according to claim 1, characterized in that A quotient of a total axial length (42) of the valve body (34) divided by an outer diameter (44) of the valve body (34) is in the range of 0.

34.

3. The fuel pump (10) according to at least one of the preceding claims, characterized in that The total axial length (42) is at least 4.6 mm.

4. The fuel pump (10) according to claim 3, characterized in that The total axial length (42) is in the range of about 5.5 mm.

5. The fuel pump (10) according to at least one of the preceding claims, characterized in that A quotient of a total axial length (42) of the valve body (34) divided by an inner diameter (48) of the valve body (34) is at least 0.

6.

6. The fuel pump (10) according to claim 5, characterized in that A quotient of a total axial length (42) of the valve body (34) divided by an inner diameter (48) of the valve body (34) is in the range of 0.

82.

7. The fuel pump (10) according to at least one of the preceding claims, characterized in that The pump housing (16) is made of 1.4418 steel or 1.4057 steel.

8. The fuel pump according to at least one of the preceding claims, characterized in that The valve body preferably has an at least substantially constant outer diameter and is screwed into the pump housing.

9. The fuel pump (10) according to at least one of the preceding claims, characterized in that The valve body (34) is press-fitted (58) into the pump housing (16).

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