FI20205596A1

FI20205596A1 - Fuel pump

Info

Publication number: FI20205596A1
Application number: FI20205596A
Authority: FI
Inventors: Robert Meier; Markus König
Original assignee: Man Energy Solutions Se
Priority date: 2019-06-17
Filing date: 2020-06-09
Publication date: 2020-12-18
Also published as: KR20200144059A; CN112096551A; JP2020204327A; DE102019116353A1; JP7479950B2; DE102019116353B4; CN112096551B

Abstract

A fuel pump (20), in particular high-pressure fuel pump of a common-rail fuel system, having a pump cylinder (21), having a pump plunger (22) that is moveably mounted in a recess (23) of the pump cylinder (21), which is moveable up and down by a cam (24) in a controlled manner, and having grooves introduced into the pump cylinder (21) in the region of the recess (23). A first groove (25), which is the greatest distance away from the cam (24), is coupled to a fuel return (28). A second groove (26), which is the shortest distance away from the cam (24) is coupled to a leakage line (29). A third groove (27), which is positioned between the first groove (25) and the second groove (26) is coupled to a fuel inlet (30).

Description

1/9 PB06046 MAN Energy Solutions SE Fuel pump The invention relates to a fuel pump, in particular a high-pressure fuel pump of a common-rail fuel system according to the preamble of Claim 1. Fuel pumps known from practice comprise a pump cylinder, wherein in the pump cylinder a pump plunger is moveably mounted. The pump plunger is moved up and down by way of one or more cams in the pump cylinder, as a result of which fuel is drawn in and supplied to consumers, such as for example injection valves of a fuel system, by the fuel pump. Fig. 1 shows a schematised cross section through a fuel pump 10 known from the — prior art, wherein the fuel pump 10 comprises a pump cylinder 11 and a pump plunger 12. The pump plunger 12 is moveably guided up and down in a recess 13 of the pump cylinder 11, wherein the up and down movement of the pump plunger 12 in the pump cylinder 11 is controlled by a cam 14. In particular when in Fig. 1 the pump plunger 12 is moved upwards in the recess 13 by the cam 14, a compression of the fuel occurs. In the opposite movement direction of the pump plunger 12, the fuel pump 10 is in a suction phase.

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S © In the shown prior art, grooves 15 and 16 are introduced into the pump cylinder 2 11. A first, upper groove 15 is coupled according to the prior art with a fuel inlet 17, - 25 in which a fuel inlet pressure is present. A second, lower groove 16 is coupled via N a leakage line 18 to a leakage tank in which ambient pressure is typically present. o 8 O During the compression of the fuel, i.e. while the cylinder plunger 12 is moved upwards in the recess 13, a part of the compressed fuel reaches the upper, first

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2/9 PB06046 groove 15 as loss, which is referred to as internal leakage, and thus pushed into the fuel inlet 17. During the suction phase of the fuel pump 10, fuel is drawn in from the first, upper groove 15, wherein in the process that fuel which was previously pushed into the fuel inlet 17 as internal leakage during the compression is then also partly drawn in. With increasingly higher pressures of fuel pumps 10, the temperature of the fuel of the internal leakage increases, so that accordingly during the suction phase, relative hot fuel is drawn in. Under certain conditions, the fuel pump 10 can overheat causing damage to the fuel pump 10.

There is a need for a fuel pump which is exposed to a lower risk of overheat- induced damage, namely even in particular when the same provides high fuel pressures. Starting out from this, the invention is based on the object of creating a new type of fuel pump. This object is solved through a fuel pump according to Claim 1. A first groove, which is the greatest distance away from the cam, is coupled to a fuel return. A second groove, which is the shortest distance away from the cam, is coupled to a leakage line. A third groove, which is positioned between the first groove and the second groove, is coupled to a fuel inlet. With the fuel pump according to the invention, the first, upper groove is not coupled to the fuel inlet but rather to the flow return. Between the first, upper groove and the second, lower groove the third groove is provided, which is coupled to the fuel inlet. During the compression, a part of the compressed fuel is o now pushed as internal leakage into the fuel return and discharged. During the O suction phase, fuel is drawn in from the third groove and also flushed into the first O 25 groove, sothat a continuous heat removal from the fuel pump is possible. Even at 2 high fuel pressures, there is thus no longer any risk that the pump overheats. j > Preferentially, the third groove is a shorter distance away from the first groove than S from the second groove. This is particularly preferred for the continuous heat S 30 removal.

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3/9 PB06046 According to an advantageous further development, a fourth groove together with the first groove is coupled to a fuel return, wherein the fourth groove is positioned between the third groove and the second groove. With this advantageous further development, the heat removal from the fuel pump can be further improved. In the suction phase of the fuel pump, fuel can be flushed from the third groove into the fourth groove. It is possible to configure a radial gap between the third groove and the fourth groove relatively large, as a result of which the flushing and cooling quantity of fuel in the suction phase can be increased. Preferred further developments of the invention are obtained from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail by way of the drawing without being restricted to this. There it shows: Fig. 1: a schematic cross section through a fuel pump according to the prior art, Fig. 2: a schematic cross section through a first fuel pump according to the invention, Fig. 3: a schematic cross section through a second fuel pump according to the invention. o The invention relates to a fuel pump, in particular a high-pressure fuel pump of a N common-rail fuel system of an internal combustion engine such as a ship's internal S combustion engine. S 25

T + Fig. 2 shows a schematised cross section through a first exemplary embodiment 2 of a fuel pump 20 according to the invention. The fuel pump 20 of Fig. 2 in turn S comprises a pump cylinder 21 and a pump plunger 22, wherein the pump plunger N 22 is moveably guided up and down in a recess 23 of the pump cylinder 21 by way ofacam 24.

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4/9 PB06046 In the pump cylinder 21, multiple grooves are introduced in the region of the recess 23. Thus, three grooves 25, 26 and 27 are introduced into the pump cylinder 21 in the region of the recess 23 in the exemplary embodiment of Fig. 2. A first upper groove 25, which is the greatest distance away from the cam 24, is coupled to a fuel return 28. A second, lower groove 26, which the shortest distance away from the cam 24, is coupled to a leakage tank via a leakage line 29. A third groove 27, which is positioned between the first groove 25 and the second groove 26, is coupled to a fuel inlet 30. In the fuel return 28 a fuel return pressure is present that is lower than a fuel inlet pressure that is present in the fuel inlet 30.

The fuel return pressure can be of the order of magnitude of 6 bar and the fuel inlet pressure of the order of magnitude of 11 bar. These values are purely exemplary in nature. Accordingly, the first, upper groove 25 is coupled to a lower pressure level than the third groove 27. The second, lower groove 26 is coupled to the lowest pressure level, namely to the pressure level of the leakage tank, in which preferentially ambient pressure is present. During a compression of fuel, a part of the compressed fuel is pushed as loss or so-called internal leakage into the first, upper groove 25 and thus into the fuel return 28. Because of the high compression pressure which can amount to more than 2,000 bar, this fuel is relatively hot. N In a following suction phase of the fuel pump 20, fuel is drawn in from the third > groove 37 and also flushed into the first groove 25, so that a continuous heat = 25 removal of the hot fuel from the fuel pump 20 into the fuel return 28 is ensured.

O z © An effective heat removal from the fuel pump 20 is possible. A lubrication, flushing 3 and cooling of the pump plunger 22 is also possible.

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5/9 PB06046 As can be seen from Fig. 2, the third groove 27 is a shorter distance away from the first, upper groove 25 than from the second, lower groove 26. An advantageous further development of the fuel pump of Fig. 2 is shown in Fig. 3. To avoid unnecessary repetitions, same reference numbers are used for same assemblies and in the following only such details are discussed by which the fuel pump 20 of Fig. 3 differs from the fuel pump 20 of Fig. 2. In addition to the abovementioned first, second and third grooves 25, 26 and 27, the fuel pump 20 of Fig. 3 comprises an additional fourth groove 31, which together with the first groove 25 is coupled to the fuel return 28. Here, this fourth groove 31 is positioned between the second groove 26 and the third groove 27. During the compression of the fuel, a part of the compressed fuel is pushed as loss or internal leakage into the first groove 25 and thus into the fuel return 28 in the fuel pump 20 of Fig. 3. In the suction phase of the pump 20 of Fig. 3, fuel is drawn in from the third groove 27 and accordingly from the fuel inlet 30 and in turn also pushed into the first groove 25, so that in turn a continuous heat removal from the pump is possible.

At the same time, fuel in the suction phase of the fuel pump 20 of Fig. 3, which is o drawn in from the fuel inlet 30 via the third groove 27, is also flushed into the fourth N groove 31 and thus via the fourth groove 31 in turn into the fuel return. Here, a S radial gap between the pump plunger 22 and the pump cylinder 21 between the 3 25 third groove 27 and the fourth groove 31 can be enlarged, as a result of which an E effective lubrication, flushing and cooling of the pump plunger 22 during the O suction phase is possible. 3

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6/9 PB06046 List of reference numbers 10 Fuel pump 11 Pump cylinder 12 Pump plunger 13 Hollow space 14 Cam 15 Groove 16 Groove 17 Fuel inlet 18 Leakage line 20 Fuel pump 21 Pump cylinder 22 Pump plunger 23 Hollow space 24 Cam 25 Groove 26 Groove 27 Groove 27 Fuel return 29 Leakage line Fuel inlet o 31 Groove

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Claims

7/9 PB06046 Claims

1. A fuel pump (20), in particular high-pressure fuel pump of a common-rail fuel system, having a pump cylinder (21), having a pump plunger (22) that is moveably mounted in a recess (23) of the pump cylinder (21), which is moveable up and down by a cam (24) in a controlled manner, having grooves introduced into the pump cylinder (21) in the region of the recess (23), characterized in that a first groove (25), which is the greatest distance away from the cam (24), is coupled to a fuel return (28), a second groove (26), which is the shortest distance away from the cam (24), is coupled to a leakage line (29), a third groove (27), which is positioned between the first groove (25) and the second groove (26), is coupled to a fuel inlet (30).

2. The fuel pump according to Claim 1, characterized in that the third groove (27) is a shorter distance away from the first groove (25) than from the second groove (26).

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3. Thefuel pump according to Claim 1 or 2, characterized in that in the fuel = return (28) a fuel return pressure is present, and in that in the fuel inlet (30) a z 25 fuel inlet pressure is present, which is greater than the fuel return pressure.

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4. Thefuel pump according to any one of the Claims 1 to 3, characterized in N that a fourth groove (31) together with the first groove (25) is coupled to the fuel return (28).

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8/9 PB06046

5. The fuel pump according to Claim 4, characterized in that the fourth groove (31) is positioned between the third groove (27) and the second groove (26).

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