SYSTEM COMPRISING AN ELECTRIC MACHINE AND A HYDRAULIC UNIT, AS WELL AS ELECTRIC MACHINE AND HYDRAULIC UNIT

Abstract

The invention relates to a system comprising an electric machine, where in the electric machine has a first shaft and a hydraulic unit, wherein the hydraulic unit has a second shaft, wherein the first shaft and the second shaft are connected to one another to form a shaft-hub connection, the shaft-hub connection has a central recess and the shaft-hub connection is connected fluidically to the interior of the hydraulic unit for lubrication.

Claims

1. A system comprising an electric machine, wherein the electric machine comprises a first shaft, and a hydraulic unit, wherein the hydraulic unit comprises a second shaft, wherein the first shaft and the second shaft are connected to one another to form a shaft-hub connection, the shaft-hub connection comprises a central recess and the shaft-hub connection is fluidically connected to an interior of the hydraulic unit for lubrication, wherein the central recess adjoins at least one transverse channel, wherein the at least one transverse channel extends from the central recess to an external circumference of the shaft-hub connection.

2. The system according to claim 1, wherein the first shaft and the second shaft are inserted into one another to form the shaft-hub connection.

3. The system according to claim 2, wherein the first shaft and/or the second shaft comprises the central recess, wherein the at least one transverse channel extends from the central recess to an external circumference of the shaft.

4. The system according to claim 2, wherein the central recess and the at least one transverse channel are disposed in the second shaft.

5. The system according to claim 1, wherein the shaft-hub connection comprises an intermediate shaft for connecting the first shaft and the second shaft, wherein the central recess and the at least one transverse channel are formed in the intermediate shaft.

6. The system according to claim 1, wherein the hydraulic unit comprises a leakage oil chamber and wherein the at least one transverse channel extends from the central recess to the leakage oil chamber.

7. The system according to claim 6, wherein the central recess extends as an axial channel from the at least one transverse channel through the second shaft to the shaft-hub connection.

8. The system according to claim 1, wherein the central recess extends as an axial channel from the at least one transverse channel through the second shaft or through the intermediate shaft to a front-side end of the second shaft or of the intermediate shaft facing the first shaft.

9. The system according to claim 1, wherein the first shaft has a receptacle for the second shaft or for the intermediate shaft and wherein the central recess formed in the first shaft adjoins the receptacle and wherein the at least one transverse channel is formed in the first shaft.

10. The system according to claim 9, wherein a front-side end face of the first shaft is sealed with respect to the hydraulic unit.

11. The system according to claim 1, wherein the at least one transverse channel ends at a point on the external circumference of the shaft which does not overlap with another shaft in the connected state.

12. The system according to claim 1, wherein the shaft-hub connection is connected fluidically outside the second shaft via at least one passage to a leakage oil chamber of the hydraulic unit.

13. The system according to claim 12, wherein the second shaft is mounted without a shaft seal in a housing of the hydraulic unit to form a passage in the direction towards the shaft-hub connection.

14. The system according to claim 12, wherein the hydraulic unit has a housing surrounding the second shaft in which at least one opening is formed to form a passage, and wherein the at least one opening can be closed and has an internal thread for this purpose.

15. The system according to claim 1, wherein the hydraulic unit is a swash plate unit, angled piston unit, gear pump unit, rotary vane unit or screw spindle unit.

16. A hydraulic unit for a system according to claim 1, wherein a shaft of the hydraulic unit has a central recess and at least one transverse channel, wherein the at least one transverse channel extends from the central recess to an external circumference of the shaft.

17. The hydraulic unit according to claim 16, wherein the hydraulic unit has a leakage oil chamber and the at least one transverse channel extends from the recess to the leakage oil chamber, and wherein the recess extends as an axial channel from the at least one transverse channel through the shaft to a front side of the shaft accessible outside a housing.

18. An electric machine for a system according to claim 1, wherein a shaft of the electric machine has a central recess and at least one transverse channel, wherein the at least one transverse channel extends from the central recess to an external circumference of the shaft, wherein the shaft has a receptacle for a shaft and the recess adjoins the receptacle.

19. An intermediate shaft for a system according to claim 1, wherein the intermediate shaft has a central recess and at least one transverse channel, wherein the at least one transverse channel extends from the central recess to an external circumference of the intermediate shaft.

20. The intermediate shaft according to claim 19, wherein the intermediate shaft has an external toothed structure at both its ends to form a shaft-hub connection with the second shaft of the hydraulic unit and with the first shaft of the electric machine.

Description

[0041] The invention and the technical background are explained hereinafter by reference to the figures as an example. In the figures schematically

[0042] FIG. 1: shows a perspective view of a hydraulic unit,

[0043] FIG. 2: shows a connecting region of an electrical unit,

[0044] FIG. 3: shows a second shaft of the hydraulic unit,

[0045] FIG. 4: shows a sectional view through a region of an exemplary embodiment of a system,

[0046] FIG. 5: shows a sectional view through a region of a further exemplary embodiment of a system and

[0047] FIG. 6: shows a sectional view through a region of an even further exemplary embodiment of a system.

[0048] The hydraulic unit 20 shown in FIG. 1 and configured as a swash plate pump comprises a housing 26 which has a cover cap 27. Mounted in the housing 26 is a shaft 21 which projects with a pin 22 beyond the cover cap 27. The pin 22 has an external toothed structure 23 with an external toothed structure length 24 and a pitch circle diameter 25. The shaft 21 with the pin 22 is also shown as a single component in FIG. 3.

[0049] FIG. 2 shows an electric machine 10 with its connecting region to the hydraulic element 20. A shaft 11 of the electric machine 10 has a receptacle 12 with an internal toothed structure 13.

[0050] The pin 22 of the shaft 21 of the hydraulic unit 20 is inserted in the receptacle 12 of the electric machine 10 to form a system. The shaft 11 of the electric machine 10 is thus connected directly to the shaft 21 of the electric hydraulic unit 20 forming a positive locking shaft-hub connection. Thus, no additional components are required to connect the shafts 21, 22 of the electric machine 10 and of the hydraulic unit 20 to one another.

[0051] In order that a tolerance deviation of the bearings of the shafts 11 and 21 can be compensated, the ratio of the pitch circle diameter 25 to external toothed structure length 24 is between 0.8 and 1.2 and preferably between 0.95 and 1.05. For the same reason the internal toothed structure 13 has a tolerance in class 07.

[0052] FIGS. 4 and 5 each show a region of a system consisting of an electric machine 10 and a hydraulic unit 20. Thus, the end of the hydraulic unit 20 facing the electric machine 10 and that of the hydraulic unit 20 facing the electric machine 10 are shown. In all the exemplary embodiments, it can be seen that the hydraulic unit 20 has a housing 26 which can comprise a cover cap 27 as a component. A leakage oil chamber 28 is formed inside the housing 26 into which hydraulic fluid can flow from the conveying chamber of the hydraulic unit along corresponding bearings (not shown) of the pump head. In addition, a leakage oil outlet 32 can be provided from which the leakage oil can emerge from the leakage oil chamber 28.

[0053] In addition, the receptacle 12 already described above can be seen at one end of the first shaft 11 in which the pin 22 of the second shaft 21 of the hydraulic unit 20 is inserted.

[0054] In the exemplary embodiment of FIG. 4, a central recess 29 configured as an axial channel is formed in the second shaft 21 of the hydraulic unit 20. This recess 29 configured as an axial channel is adjoined by two transverse channels 30 extending in the radial direction to an external circumference 31. The transverse channels 30 thus run from the end of the recess 29 into the leakage oil chamber 28. The recess 29 ends on the side facing the electric machine 10 on an end face of the second shaft 21.

[0055] In the exemplary embodiments shown in FIG. 5 a recess 29 is formed in the first shaft 11 of the electric machine 10 which adjoins the receptacle 12 for the pin 22. Starting from the recess 29 two transverse channels 30 extend to an external circumference 31 of the first shaft 11.

[0056] In both exemplary embodiments a passage 33 is formed along the external circumferential surface or through a bearing of the second shaft 21 of the hydraulic unit 20 through which leakage oil can flow from the leakage oil chamber 28 under appropriate pressure conditions. The exemplary embodiment of FIG. 5 provides a separate leakage oil outlet 32 in the electric machine 10 which is fluidically connected via the transverse channels 30 to the recess 29 in the first shaft 11.

[0057] During operation the first shaft 11 and the second shaft 21 rotate about their longitudinal axes. This has the result that leakage oil located in the transverse channels 30 is conveyed outwards as a result of centrifugal forces and a negative pressure is formed in the recess 29.

[0058] In the exemplary embodiment shown in FIG. 4 this again has the result that a negative pressure is also formed in the region of the receptacle 12 so that leakage oil flows from the leakage oil chamber 28 through the passage 33 and along the coupling point between the pin 22 and the receptacle 12. Thus, the coupling point between the pin 22 and the receptacle 12 is permanently lubricated. The leakage oil then enters into the recess 29 formed as an axial channel and passes from the transverse channels 31 back into the leakage oil chamber 28.

[0059] In the exemplary embodiments shown in FIG. 5, the rotation of the shafts 11, 21 also has the result that as a result of the centrifugal forces acting on the leakage oil in the transverse channels 30, a negative pressure is formed in the recess 29 with the result that leakage oil (hydraulic fluid) flows along the outer side of the second shaft 21 through the first passage 33 and along the coupling point between the receptacle 12 and the pin 22, with the result that the coupling point is lubricated. The fluid conveyed through the transverse channels 30 flows to the separate leakage oil outlet 32 of the electric machine 10.

[0060] FIG. 6 shows a region of a further embodiment of a system consisting of an electric machine 10 and a hydraulic unit 20, which hydraulic unit 20 might be embodied as gear pump, for example. In the following mainly the differences with regard to the above described embodiments will be described.

[0061] In this embodiment the first shaft 11 of the electric machine 10 is indirectly connected to the second shaft 21 of the hydraulic unit 20. The first shaft 11 is connected to the second shaft 21 via an intermediate shaft 40, which is inserted with its one end having an external toothed structure into a receptacle 12 of the first shaft 11 and with its other end having also an external toothed structure into a receptacle formed within the second shaft 21. Accordingly, the intermediate shaft 40 connects the first shaft 11 and the second shaft 21 in a torque proof manner, so that a rotational movement of the first shaft 11 is transferred into a rotational movement of the second shaft 21. Thereby, a shaft-hub connection is formed between the first shaft 11 and the second shaft 21.

[0062] The intermediate shaft 40 has a central recess 29 which extends from and end face of the intermediate shaft 40 facing the first shaft 11 to transverse channels 30, the transverse channels 30 extending radially outwards towards an external circumference of the intermediate shaft 40. Within the housing 26 of the hydraulic unit 20 a leakage oil chamber 28 is formed, which surrounds the external circumference of the intermediate shaft 40 in an area, in which the transverse channels 30 exit.

[0063] During operation centrifugal forces acting on the leakage oil in the transverse channels 30 produce a negative pressure in the central recess 29, so that leakage oil from the leakage oil chamber 28 flows along the outer circumference of the intermediate shaft 40 into the receptacle 12 of the first shaft 11 and enters from there into the central recess 29. The leakage oil within the central recess 29 is expelled through the transverse channels 30 back into the leakage oil chamber 28. Accordingly, the positive locking connection between the first shaft 11 and the intermediate shaft 40 is lubricated by the leakage oil.

[0064] In order to enhance the leakage oil flow along the external circumference of a shaft a tooth of the external or internal toothed structure may within the shaft-hub connection may be omitted.

[0065] Thus, a compact system comprising electric machine and hydraulic unit is provided which can be operated with low maintenance.

REFERENCE LIST

[0066] 10 Electric machine [0067] 11 First shaft [0068] 12 Receptacle [0069] 13 Internal toothed structure [0070] 20 Hydraulic unit [0071] 21 Second shaft [0072] 22 Pin [0073] 23 External toothed structure [0074] 24 External toothed structure length [0075] 25 Pitch circle diameter [0076] 26 Housing [0077] 27 Cover cap [0078] 28 Leakage oil chamber [0079] 29 Recess [0080] 30 Transverse channel [0081] 31 External circumference [0082] 32 Leakage oil outlet [0083] 33 Passage [0084] 40 Intermediate shaft