EP2399031A1

EP2399031A1 - Fuel pump

Info

Publication number: EP2399031A1
Application number: EP09801210A
Authority: EP
Inventors: Marcus Kristen; Armin Merz; Markus Grieb
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2009-02-18
Filing date: 2009-12-22
Publication date: 2011-12-28
Anticipated expiration: 2029-12-22
Also published as: CN102325997A; WO2010094366A1; DE102009000945A1; EP2399031B1; CN102325997B

Abstract

The invention relates to a fuel pump (1) serving in particular as a vacuum pump for a pump arrangement having a vacuum pump and a high-pressure pump for fuel injection systems of turbocharged compression-ignition internal combustion engines, comprising an inlet channel (15) and a connecting channel (19) on the suction side thereof. The connecting channel (19) thereby runs in a direction (22) deviating from a direction (16) of the inlet channel (15). A throttle (30) is further provided, wherein the throttle (30) connects to the inlet channel (15) in the direction (16) of the inlet channel (15) and opens into the connecting channel (19) on the side. A reliable throttle effect is thus provided, in order to allow vacuum-throttled operation of the fuel pump.

Description

description

title

fuel pump

State of the art

The invention relates to a fuel pump, in particular a low-pressure pump of a pump arrangement with a low-pressure pump and a high-pressure pump. Specifically, the invention relates to the field of fuel injection systems of air compressing, self-igniting internal combustion engines.

From DE 197 36 160 Al a pump arrangement for high-pressure fuel supply in fuel injection systems of internal combustion engines is known. The known pump arrangement is particularly suitable for a common rail injection system. The known pump arrangement comprises a radial piston pump with a drive shaft mounted in a pump housing and a low pressure pump upstream of the radial piston pump. The supply of a fuel from the low pressure pump to the high pressure pump via a hole in the pump housing (monoblock). The intake is located on the pump housing.

It is conceivable that in a pump arrangement, a throttle is provided in the inlet of the low-pressure pump in order to allow a suction-throttled operation of the low-pressure pump with a limited flow rate. However, this results in the Problem that on the one hand a compact design is desirable and on the other unfavorable flow conditions can occur.

Disclosure of the invention

The fuel pump according to the invention with the features of claim 1 and the fuel pump according to the invention with the features of claim 12 have the advantage that an operation is improved. Specifically, a fuel pump can be created, which has a throttle for limiting flow, with an advantageous mode of operation of the throttle and at the same time a deflection for a fuel is realized.

The measures listed in the dependent claims advantageous refinements of the claim 1 fuel pump and the fuel pump specified in claim 12 are possible.

In general, a throttle may be designed as a diaphragm or nozzle. Especially with a laminar throttle, the length is much larger than a throttle diameter. Preferably, the throttle is not configured as such a laminar throttle. In particular, it is advantageous that a ratio of a length of the throttle to a diameter of the throttle is less than about 1.5. However, the ratio of the length of the throttle to the diameter of the throttle may also be greater than 1.5, in particular slightly greater than 1.5. Advantageously, the throttle may be arranged in the extension of the inlet channel. This allows the design of the inlet channel together with the throttle by means of a step tool. Furthermore, in Advantageously, a configuration can be realized in which a flow separation in the region of the throttle is prevented or at least reduced, whereby the full throttle diameter is effective. Together with a subsequent large connection channel or the like. This can be achieved a good throttle effect.

It is advantageous that the connecting channel is designed as a blind bore and that the throttle opens laterally into a cylindrical portion of the connecting channel. As a result, an advantageous throttle behavior of the throttle is ensured. It is also advantageous that a cross section of the connecting channel is greater than a cross section of the throttle, so that a nearly ideal throttle behavior can be achieved. It is also advantageous that the inlet channel has a conical end section and that the throttle adjoins the conical end section.

Advantageously, the throttle is at least approximately aligned with an axis of the inlet channel. Here, it is also advantageous that the throttle is designed as a throttle bore. As a result, an advantageous positioning of the throttle is given. In addition, a simple configuration by means of a step tool is possible.

It is advantageous that the direction of the inlet channel and the direction of the connecting channel form an angle of approximately 90 °. As a result, a deflection of the fuel is realized, wherein an advantageous intersection between the throttle and the connecting channel is realized, in particular, the throttle length is defined defined. Of the Connecting channel is designed as at least substantially unthrottled connection channel, so that the throttling effect of the inlet to the inlet channel, the connecting channel and the throttle is determined at least substantially by the throttle.

The inlet channel can be configured in an advantageous manner as an inlet bore, which extends at least in sections through an inlet connection. Here, the inlet channel can be configured in a housing part of the high-pressure pump, wherein the inlet nozzle can be an integral part of the housing part.

However, the throttle and the connecting channel can be integrated in an advantageous manner in a housing part of an external gear pump. For example, an integration into a designed as a housing of the external gear pump housing part of the external gear pump.

Specifically, in a configuration in which the connection channel extends in a direction that deviates from a direction of the inlet channel, and the direction of the inlet channel with the direction of the connecting channel forms an acute angle, it is advantageous that the inlet channel has a conical end portion and that an inner angle of the conical end portion is at least approximately equal to twice the acute angle included by the direction of the inflow channel with the direction of the connection channel. As a result, an advantageous transition between the inlet channel and the connecting channel is made possible. In this case, in particular, flow separation can be prevented or at least reduced. Here, it is also advantageous that the connecting channel opens at the conical end portion of the inlet channel into the inlet channel and that the connecting channel is designed as throttling connecting channel. Further, it is advantageous that a suction chamber is provided, that the connecting channel opens into the suction chamber and that a cross section of the suction chamber in an opening region in which the connecting channel opens into the suction chamber, is substantially larger than a cross section of the connecting channel. The suction chamber can be designed in particular in a low-pressure pump, in particular an external gear pump. This results in the advantage that a good throttle effect can be achieved.

Brief description of the drawings

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

Fig. 1 is a side view of a fuel pump according to an embodiment of the invention;

FIG. 2 shows a partial section through the fuel pump shown in FIG. 1 along the section line designated II according to a conventional embodiment; FIG.

Fig. 3 shows the section shown in Fig. 2 by the fuel pump according to the embodiment of the invention and Fig. 4 shows the section shown in Fig. 2 by the fuel pump according to a further embodiment of the invention.

Embodiments of the invention

Fig. 1 shows a fuel pump 1 in a side view according to an embodiment of the invention. The fuel pump 1 can in particular be configured as a pump arrangement with a low-pressure pump, for example an external gear pump 2, and a high-pressure pump 3 for fuel injection systems of air-compressing, self-igniting internal combustion engines. The fuel pump 1 can also be designed as another gear pump, in particular internal gear pump, or as a vane pump. A preferred use of the fuel pump 1 is for a fuel injection system having a fuel rail which stores diesel fuel under high pressure. However, the fuel pump 1 according to the invention is also suitable for other applications.

The fuel pump 1 of the exemplary embodiment has a first pump part 2, which is designed as an external gear pump 2, and a second pump part 3, which is designed as a high-pressure pump 3, on. In the illustrated side view, the second pump part 3 lies behind the first pump part 2 and is partially covered by the first pump part 2. On a housing of the second pump part 3, a feed or intake 4 is provided, can be supplied via the fuel from a tank or the like. From the inlet nozzle 4, the fuel passes through the housing of the second pump part 3 to the gear pump forming the first pump part 2, that of the second pump part 3 forming high-pressure pump is connected upstream. The first pump part 2 therefore has the function of a low-pressure pump, while the second pump part 3 has the function of a high-pressure pump. The high-pressure pump of the second pump part 3 can be designed in particular as a radial piston pump.

The first pump part 2 has gears 5, 6, the position of which is shown in FIG. 1 by broken lines. The gears 5, 6 are covered by a housing part 7 of the external gear pump 2, which is designed as a housing 7 of the external gear pump 2. The housing part 7 is connected to fixed points 8A, 8B, 8C, 8D with a housing part 9 of the second pump part 3. The housing part 9 is designed as a high-pressure pump housing 9. The inlet nozzle 4 is part of the housing part 9. In this embodiment, the housing part 7 at four fixed points 8 A, 8 B, 8 C, 8 D is connected to the housing part 9 of the second pump part 3. Here, different arrangements for the fixed points 8A, 8B, 8C, 8D are possible. In addition, a different number of fixed points may be provided, in particular, three fixed points may be provided to connect the housing parts 7, 9 with each other.

FIG. 2 shows a partial cut through the housing part 9 of the fuel pump 1 shown in FIG. 1 along the section line designated II according to a conventional embodiment. In the housing part 9, an inlet channel 15 is formed, which is designed as a blind hole. The inlet channel 15 extends in sections through the inlet nozzle 4, wherein the inlet channel 15, in particular in the region of the inlet nozzle 4, can be configured as a stepped bore. The inlet channel 15 extends in a direction 16 through the housing part 9. The inlet channel 15 has an axis 17 along which the inlet channel 15 extends in the direction 16. The inlet channel 15 has a bore bottom 18, on which the inlet channel 15 designed as a blind hole ends. The bore bottom 18 is designed conical.

In the housing part 9, a connecting channel 19 is also formed, which is configured by a bore. On the one hand, the connecting channel 19 opens into the inlet channel 15 at the bore bottom 18. The connecting channel 19 has an axis 21 along which the connecting channel 19 extends in one direction 22.

During operation of the fuel pump 1, fuel is fed via the inlet channel 15 and the connecting channel 19 to the external gear pump 2. In this case, the fuel flows in the direction 16 through the inlet channel 15 and in the direction 22 through the connecting channel 19. The direction 16 of the inlet channel 15 includes with the direction 22 of the connecting channel 19 an angle 23 of about 90 °. That is, the axis 17 of the inlet channel 15 closes with the axis 21 of the connecting channel 19, the angle 23 of about 90 °.

During operation of the fuel pump 1, the external gear pump 2 is preferably operated in suction-throttled operation in order to limit a flow rate. The throttle effect required for this purpose is achieved through the connecting channel 19. For this purpose, a cross section of the connecting channel 19 is set relatively small, so that the connecting channel 19 as a throttle acts. This means that acting as a throttle connection channel 19 is seated at an angle of approximately 90 ° to the inlet channel 15. As a result of this strong deflection of the flow from the inlet channel 15 into the connecting channel 19, the flow from the wall of the connecting channel 19 comes off in a region 24 of the connecting channel 19. In this way, the full cross section of the connecting channel 19 no longer acts as a throttle. The effect of the throttle is thereby changed and possibly undetermined.

In addition, the throttling action of the connecting channel 19 is dependent on the transition of the inlet channel 15 in the connecting channel 19 at the bottom of the hole 18. Here, the transition depending on the configuration of the intersection between the channels 15, 19 vary. Possible reasons for varying transitions between the inlet channel 15 and the connecting channel 19 are, for example:

First, the connecting channel 19 meets in the bore bottom 18 or in a cylindrical part 25 of the inlet channel 15. Second, the angle 23 between the inlet channel 15 and the connecting channel 19 may vary, for example due to interference contours. Third, the diameter or cross section of the inlet channel 15 at the transition to the connecting channel 19 may vary due to interference contours.

Due to these influences, among other things, the throttle effect of the throttle formed by the connecting channel 19 can vary. As a result, the throttle behavior of the connection channel 19 is not determined, so that no ideal throttle behavior is present. The above points may also result in that for each variant of the high-pressure pump, in particular for legal and Linkslaufvarianten, a separate throttle diameter for the connecting channel 19 must be specified and votes are required.

Fig. 3 shows the detail shown in Fig. 2 of the housing part 9 of the fuel pump 1 according to the embodiment of the invention. The connecting channel 19 extends in a direction 22 which deviates from a direction 16 of the inlet channel 15. However, adjoining the inlet channel 15 in the direction 16, a throttle 30, which is aligned in this embodiment on the axis 17 of the inlet channel 15. The connecting channel 19 is designed in this case in the form of a blind bore having a bore bottom 31. Furthermore, the connecting channel 19 has a cylindrical portion 32. The throttle 30 opens laterally into the connecting channel 19 and indeed into the cylindrical portion 32 of the connecting channel 19. Further, the inlet channel 15 has a conical end portion 33. The conical end portion 33 connects in the direction 16 to the cylindrical part 25 of the inlet channel 15. At the conical end portion 33, then the throttle 30 connects. As a result, a transition from the cylindrical part 25 of the inlet channel 15 is formed in the throttle 30. This has a favorable effect on the flow behavior in the region of the transition from the inlet channel 15 into the throttle 30. The connecting channel 19 has a diameter or cross section which is relatively large compared to a diameter or cross section of the throttle 30. This results in a favorable intersection between the throttle 30 and the connecting channel 19, wherein a reproducible in the production of the intersection line 34, which preferably deviates only slightly from a circular intersection line. Both the Inlet channel 15 and the connecting channel 19 have essentially no throttle effect.

Due to the design of the inlet channel 15, the throttle 30 and the connecting channel 19 according to the embodiment, a specific throttle effect of the throttle 30 is predetermined. In addition, there is an advantageous flow pattern of the fuel flowing initially in the direction 16 and then in the direction 22, in particular in the deflection in the throttle 30 and the throttle 30 in the connecting channel 19. Flow separation within the throttle 30 are prevented. The effective length of the throttle 30 is therefore obtained uniformly along the circumference of the throttle 30. Thereby, a defined throttle effect of the throttle 30 is given.

In addition, the effect of the throttle 30 can be specified in a simple manner. In this case, in particular, the diameter or cross section of the throttle 30 can be specified. Since the throttle 30 directly adjoins the inlet channel 15 in the direction 16, the inlet channel 15 can be produced together with the throttle 30 by means of a stepping tool.

The throttle 30 can also be integrated into the housing part 7 of the external gear pump 2. In this case, defined ratios for the throttle 30 can also be created.

The angle 23 between the inlet channel 15 and the connecting channel 19 is preferably equal to 90 °. This is production technology advantageous. However, a beneficial throttling effect can also be applied to other angles 23 not equal to 90 ° are reached. It is particularly advantageous if the angle 23 is equal to or greater than 90 °, for example equal to 110 °. This is fluidly advantageous.

Fig. 4 shows the section shown in Fig. 2 by a fuel pump 1 according to another

Embodiment. In this exemplary embodiment, the inlet channel 15 has the cylindrical part 25 and the conical end section 33. The conical end portion 33 in this case has an internal angle 40. The conical end portion 33 is formed symmetrically to the axis 17 of the inlet channel 15. With respect to the axis 17 of the inlet channel 15, an angle 41 of the conical end portion 33 is determined as a half of the inner angle 40. The angle 41 represents an angle of inclination of the conical end portion 33 with respect to the axis 17 of the inlet channel 15.

The connecting channel 19 opens in this embodiment at the conical end portion 33 in the inlet channel 15. In this case, the connecting channel 19 is preferably designed as throttling connecting channel 19. The connecting channel 19 can have along its axis 21 a constant cross section 42. This has a favorable effect on the flow conditions in the connecting channel 19, whereby a detachment of the flow is prevented. However, the cross-section 42 of the connecting channel 19 may also vary if necessary.

The first pump part 2, which may be configured as a low-pressure pump 2, has a suction chamber 43. The connecting channel 19 opens into an outlet region 43 in the suction chamber 43. The suction chamber 43 has in the mouth region 44 has a cross section 45 which is substantially larger than the cross section 42 of the connecting channel 19.

In this embodiment, the connecting channel 19 is arranged obliquely to the inlet channel 15. In this case, the direction 16 of the inlet channel 15 with the direction 22 of the inlet channel 15 includes an angle 45, which is between 0 ° and 90 °. The angle 45 is an acute angle 45. Here, the acute angle 45 between the direction 16 of the inlet channel 15 and the direction 22 of the connecting channel 19 at least approximately the same size as the angle 41 between the axis 17 of the inlet channel 15 and the conical end portion 33rd Thus, the inner angle 40 is at least approximately equal to twice the acute angle 45. This results in favorable flow conditions in the transition from the inlet channel 15 to the connecting channel 19. Further, the suction chamber 43 is significantly larger than the cross section 42 of the connecting channel 19. This can be a good Throttling action of the connecting channel 19 can be achieved. Specifically, flow separation can be prevented or at least reduced. The suction chamber 43 may be configured, for example, as part of an interior of the low-pressure pump 2.

The invention is not limited to the described embodiments.

Claims

claims

1. fuel pump (1), in particular low-pressure pump for a pump assembly with a low-pressure pump and a high-pressure pump for fuel injection systems of air-compressing, self-igniting internal combustion engines, with an inlet channel (15) and a connecting channel (19) on the suction side of the fuel pump, wherein the connecting channel

(19) in a direction (22) which deviates from a direction (16) of the inlet channel (15), wherein a throttle (30) is provided and wherein the throttle (30) in the direction (16) of the inlet channel ( 15) adjoins the inlet channel (15) and opens laterally into the connecting channel (19).

2. Fuel pump according to claim 1, characterized in that the connecting channel (19) is designed as a blind hole and that the throttle (30) opens laterally into a cylindrical portion (32) of the connecting channel (19).

3. Fuel pump according to claim 1 or 2, characterized in that the inlet channel (15) has a conical end portion (33) and that the throttle (30) adjoins the conical end portion (33).

4. Fuel pump according to one of claims 1 to 3, characterized the inlet channel (15) has an axis (17) and that the throttle (30) is aligned at least approximately on the axis (17) of the inlet channel (15).

5. Fuel pump according to one of claims 1 to 4, characterized in that the throttle (30) is designed as a throttle bore.

6. Fuel pump according to one of claims 1 to 5, characterized in that the direction (16) of the inlet channel (15) and the direction (22) of the connecting channel (19) at least approximately enclose an angle (23) of 90 °.

7. Fuel pump according to one of claims 1 to 6, characterized in that the connecting channel (19) is designed as at least substantially unthrottled connecting channel (19).

8. Fuel pump according to one of claims 1 to 7, characterized in that the inlet channel (15) is designed as an inlet bore, which extends at least partially through an inlet nozzle (4).

9. Fuel pump according to one of claims 1 to 8, characterized in that the inlet channel (15), the throttle (30) and the connecting channel (19) in a housing part (9) of a high-pressure pump (3) are configured.

10. Fuel pump according to one of claims 1 to 7, characterized the throttle (30) and the connecting channel (19) are integrated in a housing part (7) of a low-pressure pump (2) and / or that the housing part (7) of the low-pressure pump (2) is designed as a housing (7) of the external gear pump (2) is.

11. Fuel pump according to one of claims 1 to 10, characterized in that a cross section of the connecting channel (19) is greater than a cross section of the throttle (30).

12. Fuel pump (1), in particular low-pressure pump for a pump assembly with a low-pressure pump and a high-pressure pump for fuel injection systems of air-compressing, auto-ignition internal combustion engine, with an inlet channel (15) and a connecting channel (19) on the suction side of the fuel pump, wherein the connecting channel

(19) in a direction (22) which deviates from a direction (16) of the inlet channel (15), and wherein the direction (16) of the inlet channel (15) with the direction (22) of the connecting channel (19) an acute Includes angle (45).

13. A fuel pump according to claim 12, characterized in that the inlet channel (15) has a conical end portion (33) and that an internal angle (40) of the conical end portion (33) is at least approximately equal to twice the acute angle (45) includes the direction (16) of the inlet channel (15) with the direction (22) of the connecting channel (19).

14. Fuel pump according to claim 12 or 13, characterized in that the connecting channel (19) at the conical end portion (33) of the inlet channel (15) opens into the inlet channel (15) and that the connecting channel (19) is designed as throttling connecting channel (19).

15. Fuel pump according to one of claims 12 to 14, characterized in that a suction chamber (43) is provided, that the connecting channel (19) opens into the suction chamber (43) and that a cross section (45) of the suction chamber (43) at least in an opening region (44), in which the connecting channel (19) opens into the suction chamber (43), is substantially larger than a cross-section (42) of the connecting channel (19).