Rotor shaft, rotor assembly and motor

Abstract

The utility model relates to a rotor shaft, which is provided with a hollow inner cavity and a shaft wall for limiting the inner cavity, a coolant can flow through the inner cavity, and a bearing cooling passage is arranged on a first length section, matched with a bearing, of the rotor shaft. The bearing cooling passage comprises a plurality of bearing cooling through holes arranged in the circumferential direction of the rotor shaft and extending radially through the shaft wall, each bearing cooling through hole having an inlet on the inner surface of the shaft wall leading to the inner cavity and an outlet on the outer surface of the shaft wall, the bearing cooling passage also includes at least one cooling slot disposed on an outer surface of the shaft wall in fluid communication with an outlet of a corresponding bearing cooling through hole. The utility model also relates to a rotor assembly and a motor comprising the rotor shaft. By adopting the rotor shaft provided by the utility model, the bearing can be cooled more efficiently through the bearing cooling passage on the rotor shaft, and the service lives of the bearing and a motor are prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to motor technical field especially relates to a rotor shaft and including the rotor assembly and motor of the rotor shaft. BACKGROUND

[0002] With the development of new energy automobile industry, the market requires higher and higher power density of motor and cooling of motor. When the motor operates, the motor side rear end bearing will generate heat due to friction, etc. If the heat at the bearing cannot be dissipated in time, the bearing temperature will continue to rise, and the high temperature will change the fit clearance inside the bearing, affect the performance of the lubricating grease, etc., thereby causing the bearing running resistance to increase, abnormal vibration and noise to occur, and even possibly causing the bearing to seize, so that the motor cannot operate normally. Therefore, a scheme capable of effectively cooling the rear end bearing is needed.

[0003] In a cooling scheme for oil-cooled motor known in the prior art, the motor side rear end bearing is cooled by the cooling return oil of the stator winding and the rotor. However, this cooling method limits the cooling effect of the bearing, and the bearing temperature undesirably rises, thereby affecting the service life of the bearing and the motor. In addition, other cooling schemes are also known in the prior art. For example, a cooling liquid passage can be arranged on the motor housing to cool the bearing. However, due to the relatively long and thin cooling liquid passage on the housing, the casting / machining difficulty of the motor housing is increased, thereby increasing the manufacturing cost of the motor housing.

[0004] Therefore, an improved cooling scheme for the bearing assembly of the motor is needed to overcome the above or other disadvantages in the prior art. SUMMARY

[0005] The utility model is based on the above background, and an improved rotor shaft is proposed, which can optimize the cooling effect of the bearing assembly on the rotor shaft to further improve the service life of the bearing and the motor.

[0006] According to a first aspect of the present application, a rotor shaft is provided, having a hollow inner cavity and a shaft wall defining the inner cavity, characterized in that the rotor shaft is provided with a bearing cooling passage on a first length section thereof cooperating with a bearing assembly, coolant is flowable through the inner cavity and from the inner cavity into the bearing cooling passage to cool the bearing assembly; wherein the bearing cooling passage comprises a plurality of bearing cooling through holes extending radially through the shaft wall on the first length section in a circumferential direction of the rotor shaft, each bearing cooling through hole has an inlet on an inner surface of the shaft wall opening into the inner cavity and an outlet on an outer surface of the shaft wall in communication with the inlet; the bearing cooling passage further comprises at least one cooling groove arranged on the outer surface of the shaft wall in fluid communication with the outlet of the corresponding bearing cooling through hole.

[0007] As an advantageous implementation, the cooling groove extends past the outlet of the bearing cooling through hole, so that coolant flowing out of the outlet is flowable into the cooling groove.

[0008] As an advantageous implementation, at least one annular groove is arranged on the outer surface of the shaft wall of the rotor shaft, the annular groove is in fluid communication with the cooling groove.

[0009] As an advantageous implementation, the extension direction of the cooling groove is set to be non-parallel to the axial direction of the rotor shaft and at an angle to the axial direction of the rotor shaft.

[0010] As an advantageous implementation, the angle is 20° to 30°.

[0011] As an advantageous implementation, the angle is 25°.

[0012] As an advantageous implementation, the rotor shaft is provided with a rotor lamination cooling passage on a second length section thereof cooperating with a rotor lamination, the rotor lamination cooling passage comprises a plurality of rotor lamination cooling through holes extending radially through the shaft wall in a circumferential direction of the rotor shaft.

[0013] According to a second aspect of the present application, a rotor assembly is provided, comprising the rotor shaft as described above.

[0014] According to a third aspect of the present application, an electric machine is provided, comprising the rotor shaft or the rotor assembly as described above.

[0015] As an advantageous implementation, the electric machine comprises a bearing assembly arranged on the first length section of the rotor shaft, the bearing assembly is cooled by the bearing cooling passage provided on the first length section.

[0016] The rotor shaft or rotor assembly according to the utility model, through the bearing cooling passage arranged on the rotor shaft, specifically through the bearing cooling through hole communicated with the inner cavity of the rotor shaft and the cooling groove extending through the bearing cooling through hole, and the extension direction of the cooling groove is at a certain angle with the axial direction of the rotor, which not only increases the cooling liquid volume, but also reduces the damage to the strength of the rotor shaft, and also enables the cooling to be realized through multiple flow paths, thereby realizing the cooling of the bearing more efficiently and improving the service life of the bearing and the motor. BRIEF DESCRIPTION OF DRAWINGS

[0017] The features and advantages of the present utility model will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. It is to be understood that the following drawings are diagrammatic and schematic representations of the utility model and are not necessarily drawn to scale, and therefore should not be used to construe the limitations of the present utility model, in which:

[0018] Figure 1 showing a perspective view of a rotor shaft of a motor according to an embodiment of the present utility model;

[0019] Figure 2 showing a cross-sectional view of the rotor shaft in Figure 1 ; and

[0020] Figure 3 showing a cross-sectional perspective view of the rotor shaft in Figure 1 . DETAILED DESCRIPTION

[0021] Embodiments of the present utility model will be described below with reference to the drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present utility model. It will be apparent, however, to one skilled in the art that the present utility model can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present utility model. In addition, it is to be understood that the present utility model is not limited in its application to the specific details of construction and the arrangement of components set forth in the description and illustrated in the drawings. Rather, the present utility model is capable of implementation using any combination of the features and elements set forth below, whether or not they are considered to be part of the same embodiment.

[0022] In the following description, terms such as "first", "second", etc. are used to describe elements of the present application, and these terms are only used to distinguish the respective elements, and are not used to limit the nature, order or number of the elements. The terms "include" and "have" are used to mean an open-ended inclusion, and refer to the presence of additional elements / components in addition to the listed elements / components.

[0023] The motor rotor shaft is a key component of the motor, which is used to bear the weight of the rotor and the centrifugal force generated during rotation, etc., to ensure that the rotor maintains the correct position and stable rotation axis in the stator inner cavity. As mentioned in the background section, the motor side rear end bearing mounted on the rotor shaft needs to be effectively cooled to prevent the service life of the motor from being affected by premature failure of the bearing. To this end, the utility model provides an improved rotor shaft, which can more reliably and efficiently cool the bearing mounted on the rotor shaft.

[0024] In particular, Figure 1 and Figure 2 respectively show the perspective view and sectional view of the rotor shaft of the motor according to an embodiment of the utility model. Referring to Figure 1 and Figure 2 , the rotor shaft 1 has a hollow inner cavity 2 and a shaft wall 3 defining the inner cavity 2, wherein a bearing assembly (not specifically shown in the figure) can be arranged on the first length section L1 of the rotor shaft 1. In order to achieve effective cooling of the bearing assembly, a bearing cooling passage is provided on the first length section L1 of the rotor shaft 1, through which the coolant can flow through the inner cavity 2 and flow from the inner cavity 2 into the bearing cooling passage to cool the bearing assembly.

[0025] As Figure 1 shown, the bearing cooling passage can include a plurality of bearing cooling through holes 4 radially extending through the shaft wall 3 arranged on the first length section L1 along the circumferential direction of the rotor shaft 1. Each bearing cooling through hole 4 has an inlet on the inner surface 31 of the shaft wall 3 communicating with the inner cavity 2 and an outlet on the outer surface 32 of the shaft wall 3 communicating with the inlet. In order to provide a plurality of flow paths for the coolant, the bearing cooling passage further includes at least one cooling groove 5 (see Figure 1 ) arranged on the outer surface 32 of the shaft wall 3 in fluid communication with the outlet of the corresponding bearing cooling through hole 4. Advantageously, the cooling groove 5 extends through the outlet of the bearing cooling through hole 4, so that the coolant flowing out of the outlet can directly flow into the cooling groove 5. Therefore, the coolant guided by the cooling groove 5 can achieve cooling of the bearing inner ring, and the falling process of the coolant in the cooling groove 5 will inevitably pass through the rolling balls and the bearing outer ring, so that the cooling of the rolling balls and the bearing outer ring can be achieved during the flow of the coolant.

[0026] Still referring to Figure 1The extension direction of the cooling groove 5 is arranged to be non-parallel to the axial direction O of the rotor shaft 1 and to form an angle a with the axial direction of the rotor shaft 1. This arrangement is advantageous in that, compared to a cooling groove parallel to the axial direction O of the rotor shaft 1, the non-parallel arrangement of the cooling groove 5 can increase the volume of the cooling liquid stored in the groove and reduce the damage to the strength of the rotor shaft 1. Preferably, the angle a is 20° to 30°, in particular 25°. Of course, other suitable angle arrangements are possible depending on the actual design requirements.

[0027] In addition, at least one annular groove 6 can be arranged on the outer surface 32 of the shaft wall 3 of the rotor shaft 1, and the annular groove 6 is in fluid communication with the cooling groove 5. In this way, a certain volume of coolant can be stored in the annular groove 6, so that during rotation of the rotor shaft 1, the stored coolant can be sent to each component of the bearing assembly by centrifugal force to carry away heat, thereby greatly improving the cooling effect of the bearing assembly.

[0028] In actual motor design, the rotor shaft can be arranged with rotor laminations (not shown in the figure) on the second length section L2 thereof to form a rotor assembly, and a stator assembly is arranged on the outer periphery of the rotor laminations to ultimately form a motor. In order to achieve cooling of the rotor laminations, rotor lamination cooling passages can be arranged on the second length section L2 of the rotor shaft, and the rotor lamination cooling passages can include a plurality of rotor lamination cooling holes 7 arranged in the circumferential direction of the rotor shaft 1 and extending radially through the shaft wall 3. Figure 2 For example, as shown in FIG. 1, a plurality of rotor lamination cooling holes 7 are arranged at different axial positions of the rotor shaft 1, such as at both ends of the second length section L2. Figure 2 In this way, the coolant can flow through the hollow inner cavity 2 of the rotor shaft 1 and flow from the inner cavity 2 into the rotor lamination cooling passages to cool the rotor laminations, so as to avoid heat from being unable to be timely dissipated at the rotor laminations, ultimately leading to premature failure of the motor.

[0029] Various modifications and variations to the disclosed embodiments can be carried out by those skilled in the art without departing from the scope or spirit of the present application. Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are considered exemplary only, and the true scope of the application is indicated by the appended claims and their equivalents.

Claims

1. A rotor shaft having a hollow inner cavity (2) and a shaft wall (3) delimiting the inner cavity, characterized in that The rotor shaft (1) is provided with a bearing cooling passage on a first length section (L1) thereof cooperating with a bearing assembly, coolant being flowable through the inner cavity (2) and from the inner cavity into the bearing cooling passage for cooling the bearing assembly; The bearing cooling passage comprises a plurality of bearing cooling through holes (4) extending radially through the shaft wall (3) arranged in a circumferential direction of the rotor shaft (1) on the first length section (L1), each bearing cooling through hole (4) having an inlet on an inner surface (31) of the shaft wall opening into the inner cavity (2) and an outlet on an outer surface (32) of the shaft wall in communication with the inlet; the bearing cooling passage further comprises at least one cooling groove (5) arranged on the outer surface (32) of the shaft wall in fluid communication with the outlet of a respective bearing cooling through hole (4).

2. The rotor shaft of claim 1, wherein The cooling groove (5) extends past the outlet of the bearing cooling through hole (4) so that coolant flowing out of the outlet can flow into the cooling groove (5).

3. The rotor shaft of claim 2, wherein At least one annular groove (6) is provided on the outer surface (32) of the shaft wall (3) of the rotor shaft (1), the annular groove (6) being in fluid communication with the cooling groove (5).

4. The rotor shaft according to any one of claims 1 to 3, characterized in that The extension direction of the cooling groove (5) is arranged non-parallel to and at an angle to the axial direction of the rotor shaft (1).

5. The rotor shaft of claim 4, wherein The angle is 20° to 30°.

6. The rotor shaft of claim 5, wherein The angle is 25°.

7. The rotor shaft of any one of claims 1 to 3, wherein, The rotor shaft (1) is provided with a rotor lamination cooling passage on a second length section (L2) thereof cooperating with rotor laminations, the rotor lamination cooling passage comprising a plurality of rotor lamination cooling through holes (7) extending radially through the shaft wall (3) arranged in a circumferential direction of the rotor shaft (1).

8. A rotor assembly characterized by, The rotor assembly comprises a rotor shaft (1) according to any one of claims 1 to 7.

9. An electric machine characterized by The electric machine comprises a rotor shaft according to any one of claims 1 to 7 or a rotor assembly according to claim 8.

10. The electric machine of claim 9, wherein, The electric machine comprises a bearing assembly arranged on the first length section (L1) of the rotor shaft, the bearing assembly being cooled by a bearing cooling passage provided on the first length section.

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