ARRANGEMENT COMPRISING AN ELECTRIC MACHINE AND A GEARBOX AND VEHICLE

Abstract

Arrangement (1) comprising an electric machine (2), a gearbox (3), a shaft (9) coupling the electric machine (2) with the gearbox (3) and having an axial blind bore (18) extending from a machine-side end (19) of the shaft (9) into the gearbox (3), a coolant insertion element (21) configured to supply a coolant into the bore (18) and a coolant conduction element (22) extending inside the bore (18) from the machine-side end (19) into the gearbox (3) and defining a flow path (23) for the inserted coolant.

Claims

1. Arrangement (1) comprising an electric machine (2), a gearbox (3), a shaft (9) coupling the electric machine (2) with the gearbox (3) and having an axial blind bore (18) extending from a machine-side end (19) of the shaft (9) into the gearbox (3), a coolant insertion element (21) configured to supply a coolant into the bore (18) and a coolant conduction element (22) extending inside the bore (18) from the machine-side end (19) into the gearbox (3) and defining a flow path (23) for the inserted coolant.

2. Arrangement according to claim 1, wherein the bore (18) is realized by the shaft (9) having a through hole, which is axially closed by means of a closing element (20), particularly comprising a plug, a stud or a nut.

3. Arrangement according to claim 2, wherein the closing element (20) mounts a bearing (14) supporting the shaft (9) and/or mounts a gear (11) of the gearbox (3).

4. Arrangement according to claim 1, wherein a blind end portion (24) of the shaft (9) has a deflection means (27) configured to swirl the coolant.

5. Arrangement according to claim 2, wherein a deflection means (27) is realized by the closing element (20).

6. Arrangement according to claim 4, wherein the deflection means (27) has a bore-side surface (28) being non-perpendicular to a rotation axis (29) of the shaft (9).

7. Arrangement according to claim 1, wherein the coolant conduction element (22) is arranged such that the shaft (9) rotates around it.

8. Arrangement according to claim 1, wherein the coolant conduction element (22) is configured to separate the bore (18) into an inner section (25) and into an outer section (26), wherein one section (25, 26), particularly the inner section (25), realizes the flowing path (23).

9. Arrangement according to claim 8, wherein the coolant conduction element (22) comprises an open circumferential contour (30), particularly a helical contour, extending in axial direction of the shaft (9) and protruding into the outer section (26).

10. Arrangement according to claim 9, wherein the contour (30) is realized by a contour element (31) arranged around the coolant conduction element (22).

11. Arrangement according to claim 10, wherein the contour element (31) is a wire or a ribbon and/or made of a polymer, particularly by molding it, and/or a metal.

12. Arrangement according to claim 1, wherein the arrangement comprises a radial shaft seal (32) arranged between a rotor (10) and a gear (11) attached to the shaft (9), wherein the radial shaft seal (32) is coolable by the coolant.

13. Vehicle (34), comprising an arrangement (1) according to claim 1, wherein the arrangement (1) is configured to drive the vehicle (34).

Description

[0022] Further details and advantages of the invention are disclosed in the following, wherein reference is made to the schematic drawings showing:

[0023] FIG. 1 a perspective view of an embodiment of an inventive arrangement comprising an electric machine and a gearbox;

[0024] FIG. 2 a cross-sectional view of the arrangement along a sectional plane II shown in FIG. 1;

[0025] FIG. 3 a cross-sectional view of a coolant conduction element; and

[0026] FIG. 4 a block diagram of an embodiment of an inventive vehicle.

[0027] FIG. 1 is a perspective view of an embodiment of an arrangement 1 comprising an electric machine 2 and a gearbox 3. The arrangement 1 is an integrated drive system for a vehicle with high power density, wherein the electric machine 2 is capable of providing rotation rates up to 22.000 min.sup.−1 within a non-overloaded operation range.

[0028] The arrangement 1 further comprises an inverter 4 configured to supply the electric machine 2 electrically. The electric machine 2, the gearbox 3 and the inverter 4 have a common housing 5 with a machine housing 6 and with a gearbox housing 7. The housing 5 may be realized by a one-part housing, wherein the machine housing 6 and the gearbox housing 7 are corresponding housing sections, or by a two-part or multi-part housing.

[0029] The gearbox 3 comprises two side shafts 8, wherein one side shaft is hidden in FIG. 1. The side shafts 8 are coupled by means of the differential gear of the gearbox 3 and are attachable to wheel hubs of the vehicle.

[0030] FIG. 2 is a cross-sectional view of the arrangement 1 along a sectional plane II shown in FIG. 1. The arrangement 1 comprises a shaft 9 attached to a rotor 10 of the electric machine 2 and to a gear 11 of the gearbox 3. Thus, the shaft 9 couples the rotor 9 and the gear 11 directly and can be considered as the main shaft of the arrangement 1.

[0031] The arrangement 1 further comprises a first bearing 12 arranged between the rotor 10 and the gear 11 in a drive end shield 13 (DE shield) of the machine housing 6, a second bearing 14 arranged in a housing structure 15 of the gearbox housing 7 and a third bearing 16 arranged in a non-drive end shield 17 (NDE shield) of the machine housing 6.

[0032] The shaft 9 comprises an axial blind bore 18 extending from a machine side end 19 of the shaft 9 into the gearbox 3 up to a section of the shaft 9, at which the second bearing 14 is arranged. The bore 18 is realized by the shaft 9 having a through hole, which is axially closed by means of the closing element 20. The closing element 20 is a nut, which also mounts the second bearing 14 and the gear 11 of the gearbox 3. Alternatively, the closing element is a plug or a stud. The shaft may be made of a tube-formed raw part having the through hole. Alternatively, the through hole may be drilled into the shaft 9.

[0033] Furthermore, the arrangement 1 comprises a coolant insertion element 21 being arranged at the machine-side end 19 and being configured to insert and supply a coolant, e. g. a mixture of water and glycol, into the bore 18. The coolant insertion element 21 may be configured according to the one described in document WO 2016/050534 A1. When entering the bore 18, the coolant is conducted by means of a coolant conduction element 22 of the arrangement 1. The coolant conduction element 22 is arranged such that the shaft 9 rotates around it. In other words, the coolant conduction element 22 and the shaft 9 are not connected in a torque-proof manner with each other.

[0034] The coolant conduction element 22 extends inside the bore 18 along a flowing path 23 for the coolant from the machine side end 19 into the gearbox 3. The coolant conduction element 22 extends into the bore 18 up to a free blind end portion 24. The coolant conduction element 22 is tube-shaped and arranged coaxially with the bore 18. Thus, the coolant conduction element 22 separates the bore 18 into an inner section 25 and into an outer section 26, wherein the inner section 25 realizes the flow path 23.

[0035] When the coolant is supplied and inserted into the coolant conduction element 22 by means of the coolant insertion element 21 the coolant leaks the coolant conduction element 22 in the blind end portion 24. There it gets in contact with a deflection means 27 arranged in the blind end portion 24. The deflection means 27 is configured to swirl the coolant, therein generating turbulences for an improved cooling effect. Thereto, a bore-side surface 28 of the deflection means 27 is non-perpendicular to a rotation axis 29 of the shaft. The deflection means 27 is realized by the closing element 20. Thus, the nut forming the closing element has an inclined surface 28 on its bore-side. After being swirled, the coolant flows back to the machine-side end 19. Thereto, the coolant insertion element 21 has an outlet. Furthermore, the arrangement 1 comprises a pump (not shown), which is configured to pump the coolant along a closed cooling circuit.

[0036] Additionally, the coolant conduction element 22 comprises an open circumferential, namely helical, contour 30 extending in axial direction of the shaft 9 and protruding into the outer section 26. The contour 30 is realized by a contour element 31 arranged around the coolant conduction element 22. Thus, when the shaft 9 rotates, the coolant conduction element 22 stands still and by means of the contour 30 the reverse flow of the coolant is enhanced because of the contour having an effect similar to an axial pump.

[0037] FIG. 3 is a cross-sectional view of the coolant conduction element 22. As can be seen, the contour element 31 is a ribbon pushed over or wrapped around the coolant conduction element 22. The contour element 31 is made of a polymer as a molded part. Alternatively, the contour element 31 is made of a metal or a combination of a polymer and a metal. The contour element 31 is press fitted at both ends of the coolant conduction element 22. Although depicted as a ribbon in FIG. 3, the coolant conduction element 22 may be a wire, alternatively.

[0038] Thus, the arrangement 1 allows the coolant to be transported into the bore 18 along the cooling path 23. When leaving the cooling path 23 at the blind end portion 24, the coolant flowing back and cools the shaft 9, which is heated up by the rotor 10. Additionally, the coolant dissipates heat from the gearbox 3 as a lubricant film around the shaft 9 inside the gearbox 3 transports heat from the inside of the gearbox 3 to the shaft 9. Moreover, the coolant cools the bearings 12, 14, 16 and a radial shaft seal 32 arranged between the first bearing 12 and the rotor 11 for preventing the lubricant from getting in an air gap of the electric machine 2. Thus, the radial shaft seal 32 forms a system barrier 33 between the “wet” gearbox 3 and the “dry” electric machine 2.

[0039] According to a further embodiment of the arrangement 1, the flow direction of the coolant is opposite to the previous embodiment. Thus, the coolant flows from the coolant insertion element 21 to the blind end portion 24 through the outer section 26 and flows back through the inner section 25.

[0040] According to a further embodiment of the arrangement 1, the coolant conduction element 22 is configured to rotate with the rotor 10. Thereto, the coolant conduction element 22 is connected to the rotor 10 in a torque-proof manner and rotates relative to the coolant insertion element 21.

[0041] FIG. 4 is a block diagram of an embodiment of a vehicle 34 comprising an arrangement 1 according to one of the aforementioned embodiments, wherein the arrangement 1 is configured to drive the vehicle 34.