Bearing assembly
View Patent ↗A bearing assembly for an electrical motor, including a shaft, a housing, and a main bearing between the shaft and the housing, the shaft being surrounded by a rigid sleeve for functioning as an auxiliary bearing in case of a breakdown of the main bearing and as a grease sealing under normal operation.
1. A bearing assembly for an electrical motor, the bearing assembly comprising:
a shaft, a housing, and a main bearing between the shaft and the housing,
a rigid sleeve surrounding the shaft and being configured to function as an auxiliary bearing in case of a breakdown of the main bearing, and
a clearance between the sleeve and the shaft, the clearance being smaller than an air-gap between a stator and a rotor of the motor,
wherein the sleeve has a portion of a conical inner surface facing the shaft and having an increasing diameter towards the main bearing, the sleeve together with a centrifugal effect of the rotating shaft providing a pumping action that directs grease from a region of the conical inner surface towards the main bearing.
2. The bearing assembly of claim 1 , wherein the clearance between the sleeve and the shaft is at most 0.6 mm.
3. The bearing assembly of claim 1 , wherein the width of the sleeve portion functioning as the auxiliary bearing is at least 10 mm.
4. The bearing assembly of claim 1 , wherein the clearance between the sleeve and the shaft functions as a grease sealing under normal operation conditions.
5. The bearing assembly of claim 1 , wherein the sleeve is an integral part of the housing.
6. The bearing assembly of claim 1 , wherein the housing includes a motor end shield and wherein the sleeve is a part of the motor end shield.
7. The bearing assembly of claim 1 , wherein the sleeve is positioned between the main bearing and the interior of the housing.
8. The bearing assembly of claim 1 , wherein the material of the sleeve contains a lubricating agent.
9. The bearing assembly of claim 8 , wherein the lubricating agent is graphite.
10. An electrical motor comprising a bearing assembly comprising:
a shaft, a housing, and a main bearing between the shaft and the housing,
a rigid sleeve surrounding the shaft and being configured to function as an auxiliary bearing in case of a breakdown of the main bearing, and
a clearance between the sleeve and the shaft, the clearance being smaller than an air-gap between a stator and a rotor of the motor,
wherein the sleeve has a portion of a conical inner surface facing the shaft and having an increasing diameter towards the main bearing, the sleeve together with a centrifugal effect of the rotating shaft providing a pumping action that directs grease from a region of the conical inner surface towards the main bearing.
11. The electrical motor according to claim 10 , wherein the electrical motor is a traction motor.