GEAR PUMP AND DRIVE MACHINE

Abstract

A gear pump having a drive shaft and at least two gear wheel pairs which each include a drive gear wheel and a driven gear wheel. The two gear wheels of a gear wheel pair are in meshing engagement with one another, and the drive gear wheels are arranged on the drive shaft and in torque-transmissive engagement with the drive shaft. The gear pump has a freely rotatably mounted shaft on which the driven gear wheels of the gear wheel pair are arranged in torque-transmissive engagement, wherein the driven gear wheels are mounted on the freely rotatably mounted shaft by means of a clearance fit.

Claims

1. Gear pump having a drive shaft and at least two gear wheel pairs which each comprise a drive gear wheel and a driven gear wheel, wherein the two gear wheels of a gear wheel pair are in meshing engagement with one another, and wherein the drive gear wheels are arranged on the drive shaft and in torque-transmissive engagement with the drive shaft, and having a freely rotatably mounted shaft on which the driven gear wheels of the gear wheel pair are arranged in torque-transmissive engagement, wherein the driven gear wheels are mounted on the freely rotatably mounted shaft by means of a clearance fit.

2. Gear pump according to claim 1, wherein the drive gear wheels are mounted on the drive shaft also by means of a clearance fit, wherein the driven gear wheels on the freely rotatably mounted shaft have a greater twist play than the drive gear wheels on the drive shaft.

3. Gear pump according to claim 2, wherein the drive shaft (24) and/or the freely rotatably mounted shaft (26) has at least one flattening (52) which extends in the longitudinal direction of the respective shaft (24, 26).

4. Gear pump according to claim 2, wherein a step is formed on the drive shaft, wherein a drive gear wheel lies against the step in the axial direction.

5. Gear pump according to claim 2, wherein a notch is formed in the drive shaft, wherein a locking ring is arranged in the notch and axially fixes a drive gear wheel on the drive shaft.

6. Gear pump according to claim 2, wherein an end face of a drive gear wheel serves as a stop for axial positioning of the drive shaft.

7. Gear pump according to claim 2, wherein the gear pump is electrically driven by means of an electric motor.

8. Gear pump according to claim 6, wherein the electric motor is accommodated in a housing and the end face of a drive gear wheel lies against a flange of the housing.

9. Gear pump according to claim 2, wherein all drive gear wheels and/or all driven gear wheels have the same profile, wherein the profile is not axially symmetrical.

10. Gear pump according to claim 2, wherein the gear wheel pairs are accommodated in a housing, wherein the housing has at least one partition wall which separates the two gear wheel pairs from one another in the axial direction and serves as an axial stop for at least one of the two gear wheel pairs.

11. Drive machine for a motor vehicle having a gear pump according to claim 2 and having an oil reservoir, wherein the gear pump is configured to convey oil from the oil reservoir to lubrication points in the drive machine and to return the lubricating oil, dripping from the lubrication points, to the oil reservoir.

12. Gear pump according to claim 3, characterized in that a step is formed on the drive shaft, wherein a drive gear wheel lies against the step in the axial direction.

13. Gear pump according to claim 3, characterized in that a notch is formed in the drive shaft, wherein a locking ring is arranged in the notch and axially fixes a drive gear wheel on the drive shaft.

14. Gear pump according to claim 3, characterized in that an end face of a drive gear wheel serves as a stop for axial positioning of the drive shaft

15. Gear pump according to claim 3, characterized in that the gear pump is electrically driven by means of an electric motor.

16. Gear pump according to claim 7, characterized in that the electric motor is accommodated in a housing and the end face of a drive gear wheel lies against a flange of the housing.

17. Gear pump according to claim 3, characterized in that all drive gear wheels and/or all driven gear wheels have the same profile, wherein the profile is not axially symmetrical.

18. Gear pump according to claim 3, characterized in that the gear wheel pairs are accommodated in a housing, wherein the housing has at least one partition wall which separates the two gear wheel pairs from one another in the axial direction and serves as an axial stop for at least one of the two gear wheel pairs.

19. Drive machine for a motor vehicle having a gear pump according to claim 3 and having an oil reservoir, wherein the gear pump is configured to convey oil from the oil reservoir to lubrication points in the drive machine and to return the lubricating oil, dripping from the lubrication points, to the oil reservoir.

20. Gear pump according to claim 4, characterized in that a notch is formed in the drive shaft, wherein a locking ring is arranged in the notch and axially fixes a drive gear wheel on the drive shaft.

Description

[0031] Further advantages and features of the invention will emerge from the following description and from the appended drawings, to which reference is made. In the drawings:

[0032] FIG. 1 shows a gear pump according to the invention in an exploded view,

[0033] FIG. 2 shows a perspective illustration of the gear pump from FIG. 1,

[0034] FIG. 3 shows a longitudinal section through the gear pump from FIG. 1,

[0035] FIG. 4 shows a cross-section through the gear pump from FIG. 1,

[0036] FIG. 5 shows a cross-section through a gear wheel,

[0037] FIG. 6 shows the gear wheels of the gear pump according to the invention, and

[0038] FIG. 7 shows schematically a drive machine according to the invention with a gear pump.

[0039] FIG. 1 shows a gear pump 10 for dry sump lubrication of a drive machine.

[0040] The gear pump 10 has several pump stages, in this exemplary embodiment a pressure pump stage and two suction pump stages.

[0041] The stages are each formed by gear wheel pairs 12, 14, 16.

[0042] Each gear wheel pair 12, 14, 16 comprises a drive gear wheel 17, 18, 19 and a driven gear wheel 20, 21, 22.

[0043] The gear wheels 17, 18, 19, 20, 21, 22 may be made of sintered steel or a precisely shaped, chemically and thermally resistant plastic.

[0044] The two gear wheels of a gear wheel pair 12, 14, 16 are in meshing engagement with one another.

[0045] The drive gear wheels 17, 18, 19 are arranged on a drive shaft 24 and in torque-transmissive engagement with the drive shaft 24.

[0046] The driven gear wheels 20, 21, 22 are arranged on a freely rotatably mounted shaft 26.

[0047] The drive shaft 24 is driven by a rotor 27 of an electric motor 28.

[0048] The rotor 27 is accommodated in a housing 30 which comprises a housing part 32 with a stator 33, a cover 34 and a flange 36.

[0049] The gear pump 10 comprises an electronic controller, for example in the form of a circuit board 37, in order to control the electric motor 28 of the gear pump 10 and in some cases further electronic components.

[0050] The gear wheel pairs 12, 14, 16 are accommodated in an additional housing part 38 which adjoins the flange 36.

[0051] The housing part 32, 38, the cover 34 and flange 36 are sealed relative to one another by means of O-rings 40. Alternatively, the cover 34 may be replaced by an electronic casting compound.

[0052] FIG. 2 shows a part of the gear pump 10 from FIG. 1 in a perspective view.

[0053] The housing 38 has been removed in FIG. 2 to allow a better view of the gear wheel pairs 12, 14, 16. In particular, the meshing engagement of the gear wheels 17, 18, 19, 20, 21, 22 can be seen.

[0054] FIG. 3 shows a longitudinal section through the gear pump 10.

[0055] The sectional illustration shows that a step 42 is formed on the drive shaft 24, wherein one of the drive gear wheels, namely the drive gear wheel 17 which is closest to the rotor 27, lies against the step 42.

[0056] Furthermore, a notch 44 is formed in the drive shaft 24, and a locking ring 46 is arranged therein.

[0057] The locking ring 46 and the step 42 axially fix the drive gear wheel 17.

[0058] The axially fixed drive gear wheel 17 lies with one end face against the flange 36 of the housing 30 of the electric motor 28.

[0059] In this way, the end face of the drive gear wheel 17 serves for axial positioning of the drive shaft 24.

[0060] FIG. 3 also shows that the housing 38 has a partition wall 48 which separates the gear wheel pairs 12, 14 axially from one another.

[0061] Also, the partition wall 48 serves as an axial stop for the gear wheel pair 14, so that this is axially positioned on the shaft by the partition wall 48.

[0062] The other gear wheel pair 16 is separated from the gear wheel pair 14 by a spacer 50.

[0063] FIG. 4 shows a cross-section through the gear pump in the region of the gear wheel pair 16 along line D-D in FIG. 3. The regions around the shaft 24, 26 are each shown enlarged in a detail view.

[0064] The gear wheels 19, 22 are in torque-transmissive engagement with the drive shaft 24 or the freely rotatably mounted shaft 26 respectively.

[0065] The torque-transmissive engagement is achieved in that the drive shaft 24 and/or the freely rotatably mounted shaft 26 each have two flattenings 52 which extend in the longitudinal direction of the respective shaft 24, 26.

[0066] In particular, the shafts 24, 26 each have a double-D profile.

[0067] The gear wheels 19, 22 are mounted by means of a clearance fit on both the drive shaft 24 and also on the freely rotatably mounted shaft 26.

[0068] The driven gear wheel 22 on the freely rotatably mounted shaft 26 has however a greater twist play than the drive gear wheel 19 on the drive shaft 24.

[0069] The gear wheels 17, 18, 20, 21 of the other gear wheel pairs 12, 14 are mounted in the same fashion.

[0070] FIG. 5 shows a cross-section through a single gear wheel, for example the gear wheel 17.

[0071] For example, all gear wheels 17, 18, 19, 20, 21, 22 have the same profile.

[0072] The profile of the gear wheels 17, 18, 19, 20, 21, 22 is not axially symmetrical.

[0073] If the gear wheels are mounted alternately forward and backward on a shaft 24, 26, i.e. such that the teeth of adjacent gear wheels do not run in a line, a phase offset is thus achieved between the gear wheels 17, 18, 19, 20, 21, 22 of the adjacent gear wheel pairs 12, 14, 16. This can be seen in FIG. 6.

[0074] FIG. 7 illustrates schematically a drive machine 54 with a gear pump 10.

[0075] The functioning of a dry sump lubrication will be explained below on the basis of FIG. 7.

[0076] The drive machine 54 has an oil reservoir 56.

[0077] The gear pump 10, in particular the gear pair 12 which forms the pressure stage, draws oil out of the oil reservoir 56 and conveys this to at least one lubrication point 58 of the drive machine 54.

[0078] Oil drips into an oil sump 60 from the lubrication point 58.

[0079] By means of the gear wheel pairs 14, 16 which form the suction stages of the gear pump 10, the oil is conveyed back to the oil reservoir 56 from the oil sump.