FUEL PUMP WITH IMPROVED DELIVERY PROPERTIES

Abstract

The present invention relates to a fuel pump (1) which comprises a pump housing (2), a delivery element (3) for delivering fuel, a heat-generating actuator (4) for actuating the delivery element (3), a first fuel path (5) which leads from an inlet (20) to a delivery space (7), and a second fuel path (6) which leads from the inlet (20) past the heat-generating actuator (4) to a first housing opening (21), wherein the first housing opening (21) is arranged above the inlet (20) in the vertical direction (V). The present invention also relates to a fuel pump arrangement which comprises a fuel pump (1) according to the invention and a fuel tank (10) in which the fuel pump (1) is at least partially and preferably entirely arranged. The present invention also relates to a method for operating a fuel pump (1).

Claims

1. A fuel pump comprising: a pump housing (2), a delivery element (3) for delivering fuel, a heat-generating actuator (4) for actuating the delivery element (3), a first fuel path (5) which leads from an inlet (20) to a first delivery space (7), and a second fuel path (6) which leads from the inlet (20) past the heat-generating actuator (4) to a first housing opening (21), wherein the first housing opening (21) is arranged above the inlet (20) in the vertical direction (V).

2. The fuel pump as claimed in claim 1, wherein a flow direction in the second fuel path (6) substantially corresponds to a longitudinal axis (L) of the fuel pump (1).

3. The fuel pump as claimed in claim 1, wherein a deflector element (8) is arranged on the pump housing (2) and deflects fuel after the inlet (20) in the direction of the second fuel path (6).

4. The fuel pump as claimed in claim 3, wherein the deflector element (8) has a tilt angle (a) from 0 to 90 degrees relative to the longitudinal axis (L) of the fuel pump (1).

5. The fuel pump as claimed in claim 3, wherein the deflector element (8) has a cone filter, wherein the first fuel path (5) runs through the cone filter via a first fuel path opening (23).

6. The fuel pump as claimed in claim 5, wherein the pump housing (2) has a second fuel path opening (24) through which the second fuel path (6) runs, and wherein the cone filter terminates directly at the second fuel path opening (24).

7. The fuel pump as claimed in claim 1, wherein the second fuel path (6) leads past an inside (40) and an outside (41) of the heat-generating actuator (4).

8. The fuel pump as claimed in claim 1, wherein the heat-generating actuator (4) is a magnetic coil.

9. The fuel pump as claimed in claim 1, furthermore comprising a recirculation line (17) which connects the first housing opening (21) of the pump housing (2) to a second housing opening (18) of a housing component (12), wherein the second housing opening (18) stands in flow connection with the inlet (20) of the fuel pump

10. The fuel pump as claimed in claim 9, wherein the recirculation line (17) has a branch line (19) downstream of the first housing opening (21).

11. The fuel pump as claimed in claim 10, wherein the branch line (19) is formed rectilinear in the vertical direction (V).

12. The fuel pump as claimed in claim 9, wherein a filter element (16), which is arranged on the housing component (12), is provided between the recirculation line (17) and the second housing opening (18).

13. The fuel pump as claimed in claim 9, wherein the recirculation line (17) has a cover region (50) via which the recirculation line (17) is arranged on the second housing opening (18) of the housing component (12), and which has at least one first cover opening (51) and at least one second cover opening (52), wherein the at least one second cover opening (52) is arranged above the at least one first cover opening (51) in the vertical direction (V).

14. A fuel pump arrangement comprising a fuel pump (1) as claimed in claim 1, and a fuel tank (10) in which the fuel pump (1) is at least partially, arranged.

15. The fuel pump arrangement as claimed in claim 14, wherein the second fuel path (6) opens into the fuel tank (10).

16. A method for operating a fuel pump, comprising the steps: supplying fuel from a fuel tank (10) via a first fuel path (5) into a delivery space (7), wherein the first fuel path (5) leads from an inlet (20) of the fuel pump (1) to the delivery space (7), and conducting fuel from the fuel tank (10) via a second fuel path (6) past a heat-generating actuator (4), wherein the second fuel path (5) leads from the inlet (20) to a first housing opening (21), and wherein the fuel is heated by the heat-generating actuator (4) for gasification of highly volatile parts of the fuel, wherein the first housing opening (21) is arranged above the inlet (20) in the vertical direction.

17. The method for operating a fuel pump as claimed in claim 16, wherein after the inlet (20), fuel is deflected in the direction of the second fuel path (6).

18. The method for operating a fuel pump as claimed in claim 16, wherein the heated fuel enters the fuel tank (10) via the first housing opening (21) and is cooled in the fuel tank (10), and wherein the cooled fuel is returned to the inlet (20) of the fuel pump (1).

19. The fuel pump as claimed in claim 3, wherein the deflector element (8) has a tilt angle (a) from 30 degrees to 60 degrees relative to the longitudinal axis (L) of the fuel pump (1).

20. The fuel pump as claimed in claim 3, wherein the deflector element (8) has a tilt angle (a) of 45 degrees relative to the longitudinal axis (L) of the fuel pump (1).

21. A fuel pump arrangement comprising a fuel pump (1) as claimed in claim 1, and a fuel tank (10) in which the fuel pump (1) is completely arranged.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawing, wherein the same parts or those of equivalent function carry the same reference numerals. The drawings show:

[0029] FIG. 1 a simplified, diagrammatic cross-section view of a fuel pump arrangement with a fuel pump according to a first exemplary embodiment of the present invention,

[0030] FIG. 2 an enlarged region of the fuel pump arrangement shown in FIG. 1, and

[0031] FIG. 3 a simplified, diagrammatic cross-section view of a fuel pump arrangement with a fuel pump according to a second exemplary embodiment of the present invention.

DETAILED DESCRIPTION

[0032] With reference to FIGS. 1 and 2, a fuel pump 1 and fuel pump arrangement 9 according to a first exemplary embodiment of the present invention are described in detail below.

[0033] As evident from FIGS. 1 and 2, the fuel pump 1 according to the invention is partially arranged in a fuel tank 10 of the fuel pump arrangement 9.

[0034] Furthermore, the fuel pump 1 comprises a pump housing 2, a delivery element 3 for delivering fuel, and a heat-generating actuator 4 formed as a magnetic coil for actuating the delivery element 3. The delivery element 3 is formed as a piston. Furthermore, the fuel pump 1 has a first fuel path 5 which leads from an inlet 20 to a delivery space 7, and a second fuel path 6 which leads from the inlet 20 past the heat-generating actuator 4 to a first housing opening 21.

[0035] According to the invention, the first housing opening 21 is arranged above the inlet 20 in a vertical direction V. In operation of the fuel pump 1, this arrangement causes a stack effect which will be explained in more detail in the description of the function of the fuel pump 1. A flow direction of the fuel in the second fuel path 6 substantially corresponds to a longitudinal axis L of the fuel pump 1.

[0036] Furthermore, the fuel pump has a pre-chamber 22 which is arranged downstream of the inlet 20. The pre-chamber is formed as a recess by removal of material from the pump housing 2 of the fuel pump 1. Furthermore, a first fuel path opening 23 and a second fuel path opening 24 are provided in the pump housing 2. The first fuel path 5 runs through the first fuel path opening 23, and the second fuel path 6 runs through the second fuel path opening 24. The second fuel path 6 leads past an inside 40 and an outside 41 of the heat-generating actuator 4, and then opens into the fuel tank 10.

[0037] To improve the delivery behavior of the fuel pump 1, a deflector element 8 is arranged on the pump housing 2 and deflects fuel after the inlet 20 in the direction of the second fuel path 6 or the second fuel path opening 24. For this, the deflector element 8 has a tilt angle a of 60 degrees relative to the longitudinal axis L of the fuel pump 1. This ensures a low-loss transition between the inlet 20 and the second fuel path opening 24.

[0038] In particular, the deflector element 8 comprises a cone filter, wherein the first fuel path 5 runs through the cone filter via a first fuel path opening 23. The cone filter terminates directly at the second fuel path opening 24. This allows a flow-favorable design of the second fuel path.

[0039] As well as deflecting fuel after the inlet 20 in the direction of the second fuel path 6, the cone filter ensures that any vapor bubbles 11 occurring are kept away from the first fuel path 5. The cone filter serves to guide the vapor bubbles 11 in the direction of the second fuel path 6 to the second fuel path opening 24.

[0040] The pump housing 2 has a base body 200 and a platform-like holder 201. Furthermore, the fuel pump 1 preferably has a housing component 12 which, in this exemplary embodiment, is configured as separate component. Alternatively, the housing component 12 may be configured integrally with the pump housing 2 of the fuel pump 1. The housing component 12 comprises a return channel 13 which at a first end 14 stands in flow connection with the first housing opening 21 via a second housing opening 18, and at a second end 15 stands in flow connection with the inlet 20 of the fuel pump 1. Fuel may be returned to the inlet 20 through the return channel 13.

[0041] A method for operating the fuel pump 1 according to the present invention is described below in detail with reference to FIG. 2.

[0042] In operation of the fuel pump 1, fuel is supplied from the fuel tank 10 to the inlet 20 of the fuel pump 1. In the pre-chamber 22, the fuel flow divides into a first flow via the first fuel path 5 and a second flow via the second fuel path 6. The first flow corresponds to the actual delivery volume of the fuel pump 1 which is generated by actuation of the delivery element 3 by the heat-generating actuator 4, and enters the delivery space 7. The heat-generating actuator 4 thus generates waste heat, whereby the second flow via the second fuel path 6 is created by convection. The waste heat of the actuator 4 also causes gasification of highly volatile parts of the fuel.

[0043] The heated fuel in the second fuel path 6 rises in the vertical direction V and enters the fuel tank 10. As well as the heated fuel, the resulting vapor bubbles 11 enter the fuel tank 10, from where they are finally removed in a manner not shown, or are condensed.

[0044] In the fuel tank 10, the heated fuel is cooled by the fuel present in the fuel tank 10 which usually has a lower temperature. Since the heated fuel of the second fuel path 6 rises upward in the vertical direction V, a reduced pressure occurs in the pre-chamber 22, whereby fuel is drawn out of the fuel tank 10 (arrow B). This phenomenon, known as a stack effect, also causes the cooled fuel to be returned to the inlet 20 of the fuel pump 1 via the return channel 13, at the first end 14 of which a filter element 16 is arranged. Thus a circuit is created (arrow K in FIG. 2) which is self-supporting and also self-amplifying.

[0045] The fuel pump 1 according to the invention has an improved delivery behavior, in particular on delivery of hot fuel, wherein better cooling and a reduction in suction losses are also achieved. Also, the present invention allows use of the piston pump principle for hot fuel operation.

[0046] A fuel pump 1 and fuel pump arrangement 9 according to a second exemplary embodiment of the present invention are described in detail below with reference to FIG. 3.

[0047] The second exemplary embodiment differs from the first exemplary embodiment in principle in that a recirculation line 17 is provided. Preferably, the recirculation line 17 is made of plastic. Furthermore, the recirculation line 17 connects the first housing opening 21 of the pump housing 2 to the second housing opening 18 of the housing component 12, wherein the second housing opening 18 stands in flow connection with the inlet 20 of the fuel pump 1. Also, the second housing opening 18 is arranged at the first end 14 of the return channel 13.

[0048] Furthermore, the recirculation line 17 has a branch line 19 downstream of the first housing opening 21. Vapor bubbles occurring can be removed from the fuel pump 1 through the branch line 19 (arrow G). In particular, the branch line 19 is formed rectilinear in the vertical direction V. In addition, the branch line 19 is arranged centrally relative to the longitudinal axis L of the fuel pump 1.

[0049] The recirculation line 17 furthermore has a bell-shaped region 49 which is arranged at the first housing opening 21, in particular centrally relative to the longitudinal axis L of the fuel pump. The bell-shaped region 49 in turn is divided into a lower region 49a of wider cross-section and a pin-shaped protruding lower region 49b. Here, the pin-shaped protruding lower region 49b serves as a branch line 19. Alternatively, a separate line may be attached to the pin-shaped protruding lower region 49b.

[0050] Moreover, the recirculation line 17 has a cover region 50 via which the recirculation line 17 is arranged on the second housing opening 18 of the housing component 12. The cover region 50 has a first cover opening 51 and a second cover opening 52 which is arranged above the first cover opening 51 in the vertical direction V. The cover region 50 defines a mixing zone 53, the function of which will be explained in more detail below. Cool fuel from the fuel tank 10 enters the mixing zone 53 through the first cover opening 51 (arrow M), in which zone the cooler fuel is mixed with the fuel heated by the waste heat of the actuator 4. Vapor bubbles which are still present in the recirculating fuel, or vapor bubbles which occur due to the gasification of the fuel drawn out of the fuel tank because of high ambient temperature or direct sunshine, in conjunction with the mixing with the recirculating warmer fuel, are dissipated through the second cover opening 52 into the fuel tank 10 (arrow N). In this way, the recirculating fuel is cooled and the suction region of the fuel pump 1 is also cooled. Thus the delivery behavior of the fuel pump 1 can be significantly improved.

[0051] To allow simple and secure fixing of the recirculation line, the recirculation line 17 is arranged on the pump housing 2 by means of a first clip connection 54, and on the filter element 16 by means of a second clip connection 55. The first clip connection 54 and the second clip connection 55 each comprise a plurality of clip tabs which are arranged at both ends of the recirculation line 17, and a plurality of clip lugs in which the clip tabs engage. The clip lugs are in particular formed as circular peripheral protrusions.