WO2018201442A1 - Outer rotor-type electric motor - Google Patents

Abstract

Disclosed is an outer rotor-type electric motor, comprising: a shaft (10); a stator (20) fixedly disposed on the shaft (10), the stator (20) comprising a yoke (21) and a support portion (23) fixedly supporting the yoke (21) on the shaft (10); a rotor (30) radially outside the stator (20); and a first end cap (50) and a second end cap (60) rotatably supported on the shaft (10) and fixedly connected to the rotor (30). The first end cap (50) and the second end cap (60) comprise outer edge portions on the radially outer side of a through hole inside a disc-shaped body, and annular flanges extending toward the support portion (23) between the radially outer side of the through hole and the radially inner side of the outer edge portions. The outer edge portion is in contact with the rotor (30) and is connected to the rotor (30). The rotor (30), a portion of the first end cap (50) that is located at the radially outer side of the annular flange, the annular flange of the first end cap (50), a portion of the second end cap (60) that is located at the radially outer side of the annular flange, and the annular flange of the second end cap (60) together define an annular cavity (80) having an annular slot (81). The yoke (21) is located in the annular cavity (80), the support portion (23) passes through the annular slot (81), and the annular cavity (80) is at least partially filled with a coolant. The outer rotor-type electric motor can significantly improve the heat dissipation effect of the electric motor.

Description

Outer rotor motor Technical field

This invention relates to electric machines, and more particularly to outer rotor type electric machines.

Background technique

The outer rotor type motor has a wide range of uses due to its compact structure. In particular, with the emphasis on environmental protection, outer rotor type motors such as hub motors are increasingly used in electric vehicles such as electric scooters, electric bicycles, electric motorcycles or electric vehicles. The biggest feature of the hub motor is that the power, transmission and braking devices can be integrated into the hub, thus greatly simplifying the mechanical structure of the electric vehicle. However, due to the compact structure of the hub motor, the heat dissipation problem of the hub motor becomes very important. The cooling performance of the hub motor often becomes a bottleneck that limits its rated power. If the cooling performance of the hub motor can be effectively increased, the hub motor can be allowed to have a larger rated power.

Conventional cooling methods for hub motors include forced liquid cooling and natural air cooling. For forced liquid cooling, pumps and radiators are often required to dissipate the heat generated by the hub motor. For natural air cooling, heat is typically dissipated into the air by natural convection between the air and the surfaces of the two end caps. When an outer rotor type hub motor is used, since the winding is supported on a stator located inside the hub motor, a heat transfer path for winding heat dissipation needs to pass through the shaft and through an air gap formed between the stator and the end cover, which results in winding There is a high thermal resistance between the external environment and the external environment. Therefore, it is desirable to reduce the aforementioned thermal resistance to improve the performance of the hub motor.

Therefore, there is a need to improve the existing outer rotor type motor.

Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to overcome at least one of the above-mentioned deficiencies of the prior art and to provide an improved outer rotor type motor which can significantly reduce the thermal resistance from the winding to the end cap and improve the outer rotor The heat dissipation efficiency of the motor, so that the external rotor type motor ruler can be In the case of inches, the power density of the outer rotor type motor is increased.

To this end, according to an aspect of the present invention, an outer rotor type motor is provided, comprising:

axis;

a stator fixedly disposed on the shaft about the shaft, wherein the stator includes a yoke portion formed by stacking a plurality of stator core pieces together and located radially inward of the yoke portion for a yoke fixedly supporting a support portion on the shaft, the yoke portion is formed with a plurality of winding teeth radially outward, and a winding is wound around each of the winding teeth;

a rotor disposed radially outward of the stator about the shaft;

a first end cap rotatably supported on the shaft by a first bearing and fixedly coupled to the rotor;

a second end cap rotatably supported on the shaft by a second bearing and fixedly coupled to the rotor, the first end cap and the second end cap co-defining with at least a portion of the rotor The internal space of the outer rotor type motor;

Wherein the first end cover and the second end cover respectively comprise a disc-shaped body, and a center of the disc-shaped body is formed with a through hole for receiving the first bearing or the second bearing, the first The end cap and the second end cap further respectively include an outer edge portion on a radially outer side of the through hole inside the disc body, and a radially outer side and the outer edge portion of the through hole An annular flange extending radially inwardly toward the support portion, the outer edge portion for contacting the rotor and coupled to the rotor, the rotor, the first end cap being located in the ring a radially outer portion of the flange, the annular flange of the first end cap, a portion of the second end cap located radially outward of the annular flange, and an annular flange of the second end cap An annular chamber is defined having an annular slit, the yoke being located in the annular chamber, the support passing through the annular slit, the annular chamber being at least partially filled with a coolant.

According to the present invention, since the coolant can move in the annular chamber relative to the stator and is dispersed in the annular chamber, and the thermal conductivity of the coolant is significantly greater than the thermal conductivity of the air, the coolant located in the annular chamber will be significantly reduced from the winding Increase the heat dissipation efficiency of the outer rotor type motor to the thermal resistance of the outer cover type motor, thereby increasing the outer rotor type without increasing the size of the outer rotor type motor The power density of the motor.

DRAWINGS

Figure 1 is a front elevational view of a hub motor in accordance with a preferred embodiment of the present invention;

Figure 2 is a side elevational view of a hub motor in accordance with a preferred embodiment of the present invention;

Figure 3 is an exploded view of a hub motor in accordance with a preferred embodiment of the present invention;

4 is a schematic perspective view of an end cap of an in-wheel motor in accordance with a preferred embodiment of the present invention;

Figure 5 is a schematic perspective view of the other side of the end cap shown in Figure 4;

Figure 6 is an axial cross-sectional view of a hub motor in accordance with a preferred embodiment of the present invention.

detailed description

Preferred embodiments of the present invention are described in detail below with reference to examples. It should be understood by those skilled in the art that these exemplary embodiments are not intended to limit the invention.

1 is a front view of a hub motor in accordance with a preferred embodiment of the present invention, FIG. 2 is a side view of a hub motor in accordance with a preferred embodiment of the present invention, and FIG. 3 is an exploded view of the hub motor in accordance with a preferred embodiment of the present invention, and 6 is an axial cross-sectional view of a hub motor in accordance with a preferred embodiment of the present invention. As shown in FIGS. 1-3 and 6, an in-wheel motor 1 according to a preferred embodiment of the present invention includes a shaft 10, a stator 20 surrounding the shaft 10 and fixedly disposed on the shaft 10, and a surrounding shaft 10 disposed radially outward of the stator 20. The rotor 30, the first end cap 50 located axially to the left of the stator 20 and fixedly connected to the rotor 30, for example by bolts 40, and the axially right side of the stator 20 and fixedly connected to the rotor 30, for example by bolts 40 The second end cap 60. There is a gap between the inner surface of the first end cap 50 and the stator 20 and between the inner surface of the second end cap 60 and the stator 20. Both ends of the shaft 10 can be supported on, for example, a frame (not shown). The first end cover 50 and the second end cover 60 are rotatably supported on the shaft 10 by first and second bearings 11 and 12, respectively, provided on the shaft 10 on both sides of the stator 20. The first end cap 50 and the second end cap 60 together with at least a portion of the rotor 30 define an interior space of the hub motor 1 in which the stator 20 is located.

The stator 20 located radially inward of the rotor 30 includes a yoke portion 21 formed by stacking a plurality of stator core pieces, and a radially inner side of the yoke portion 21 for fixedly supporting the yoke portion 21 on the shaft 10. Support portion 23. The yoke portion 21 includes a plurality of winding teeth 25 formed radially outward, and windings 27 are wound around each of the winding teeth 25, respectively. The support portion 23 is disk-shaped, and it can be fixedly coupled to the yoke portion 21 by a connection such as welding or a close fitting. The support portion 23 may be hollowed out to form a plurality of openings 23b between adjacent spokes 23a. Preferably, the plurality of openings 23b are evenly distributed along the circumferential direction. The support portion 23 having the spokes 23a can not only reliably support the yoke portion 21 but also allow the airflow or the coolant to smoothly pass. It should be understood that the plurality of openings 23b may also be a plurality of circular or other shaped holes formed in the support portion 23. Thus, after the motor is energized, the rotor 30 and the first end cap 50 and the second end cap 60 fixedly coupled to the rotor 30 are rotatable about the stator 20 and the shaft 10.

The hub motor 1 also typically includes a hub 70 that is radially outward of the rotor 30 and that rotates with the rotor. Although the hub 70 is shown as being integrally formed with the rotor 30 in the figures, the hub 70 may be formed separately from the rotor 30 and fixedly coupled together by welding or a close fit or the like.

In the present application, "first" and "second" in "first end cap" and "second end cap" are used for convenience of description only, and do not constitute a special limitation of the end cap itself. For example, the first end cap may also be an end cap located on the axially right side of the stator. In this case, the second end cap may be an end cap located on the axial left side of the stator, that is, the first end. The position of the cover and the second end cap can be interchanged.

4 is a schematic perspective view of one end cap of an in-wheel motor according to a preferred embodiment of the present invention, and FIG. 5 is a schematic perspective view of the other side of the end cap shown in FIG. Since the structures of the first end cap 50 and the second end cap 60 are identical, it is assumed that the end caps shown in Figures 4 and 5 are the first end caps 50. As shown in Fig. 4, the first end cap 50 includes a disc-shaped body 51 which is preferably curved in a domed shape toward the inner side of the end cap and has a through hole 53 in which a bearing is formed at the center. The first end cover 50 further includes an outer edge portion 55 which is inside the disk-shaped body 51 (here, the inner side refers to the side toward the inside of the motor in the assembled state) and is located radially outward of the through hole 53. Outer edge portion 55 when assembled It is used in contact with the rotor 30 and is connected to the rotor 30. The first end cap 50 further includes an annular flange 57 extending between the radially outer side of the through hole 53 and the radially inner side of the outer edge portion 55 toward the inner side of the end cap (for example, toward the support portion 23). Thus, in the assembled state, the rotor 30, the first end cap 50 is located radially outward of the annular flange 57, the annular flange 57 of the first end cap 50, and the second end cap 60 are located radially outward of the annular flange 57. The portion and the annular flange of the second end cap 60 together define an annular chamber 80 in which the yoke 21 of the stator 20 is located. An annular slit 81 through which the support portion 23 of the stator 20 extends is formed between the annular flange 57 of the first end cap 50 and the annular flange 57 of the second end cap 60. There is a gap 83 between the annular flange 57 of the first end cap 50 and the annular flange 57 of the second end cap 60 and the support portion 23 of the stator 20 such that the first end cap 50 and the first end cap 50 having the annular flange 57 The two end caps 60 rotate with the rotor 30 with respect to the stator 20. Preferably, the annular flange 57 is disposed substantially in the radially inner side of the yoke portion 21 of the stator 20.

Although it is feasible to fill the entire internal space of the hub motor 1 in which the first end cap 50 and the second end cap 60 are co-defined with at least a portion of the rotor 30, such as oil, this not only adds significant cost, but also Increase the resistance of the end cap and rotor rotation and increase the weight of the entire motor. According to the present invention, it is only necessary to fill the inner space of the hub motor 1 with the coolant which fills the annular chamber 80 at most. When the motor is stopped, the coolant flows to the lower portion of the inner space of the motor through the gap 83 between the first end cover 50 and the annular flange 57 of the second end cover 60 and the support portion 23. When the motor is in operation, the first end cap 50 and the second end cap 60 rotate with the rotor 30 relative to the stator 20, between the first end cap 50 and the second end cap 60 between the outer edge portion 55 and the annular flange 57. The cooling liquid phase is partially moved by the frictional force to the stator 20 within the annular chamber 80 and dispersed within the annular chamber 80. Thus, the yoke portion 21 of the stator 20 having the winding 27 located in the annular chamber 80 is in contact with the coolant, and the coolant transfers the heat generated by the winding 27 of the yoke portion 21 to the first end cover 50 and the second end cover 60, And in turn, it is dissipated into the surrounding environment by the first end cap 50 and the second end cap 60.

In order to make the coolant more evenly distributed in the annular chamber 80 during operation of the motor, it may be provided on the portion between the outer end portion 55 and the annular flange 57 of the first end cover 50 and the second end cover 60 for agitation Agitating device 90 for the coolant. The agitation device 90 is only disposed at the first end cap 50 and One of the second end caps 60 is also possible. In a preferred embodiment, the agitation means 90 are shown as a plurality of agitating ribs 91 disposed between the outer edge portion 55 and the annular flange 57 spaced apart from one another in the circumferential direction. Preferably, the agitating rib extends from the outer edge portion 55 to the annular flange 57. Thus, the agitating ribs not only serve to agitate the coolant, but also enhance the strength of the end cap and also function as a heat transfer. It should be understood that the agitation device 90 can be in any other suitable form as long as it is capable of distributing the coolant as evenly as possible within the annular chamber 80 as the end cap rotates. For example, in the preferred embodiment, the agitation device 90 is a straight agitating rib, it being understood that the agitation device 90 can be an arcuate or wavy agitating rib.

By employing the agitation means 90, the coolant can be distributed as evenly as possible within the annular chamber 80, even completely filling the annular chamber 80, and uniformly transferring heat. Preferably, the amount of coolant filled is substantially equal to the volume of the annular chamber 80. Thus, the yoke 21 of the stator 20 with the windings 27 can be completely submerged in the coolant at least partially or even completely, and the heat generated by the windings 27 of the yoke 21 can be quickly transferred to the coolant and passed through the coolant. The first end cap 50 and the second end cap 60 are ultimately dispensed into the surrounding environment by the first end cap 50 and the second end cap 60.

To further enhance the heat transfer effect, a plurality of conductive ribs 93 extending from the annular flange 57 toward the center of the end cap and spaced apart from one another may be disposed on the first end cap 50 and the second end cap 60. The conductive ribs not only increase the heat transfer surface area, but also enhance the strength of the end cap. Similarly, heat dissipating means such as heat dissipating ribs 95 may be disposed on the outer surfaces of the first end cover 50 and the second end cover 60, so that the first end cover and the second end cover may be more fully integrated with the external environment. Heat exchange and strengthen the strength of the end cap. Further, in order to prevent the coolant from oozing out through the bearing, a rotary seal 97 is usually mounted between the shaft 10 on the outer side of the bearing and the end cap.

According to the invention, by providing the annular chamber 80 in which the yoke 21 of the stator 20 is located and at least partially filling the coolant in the annular chamber 80, the cooling liquid phase is in the annular chamber 80 for the stator 20 during operation of the motor. The interior moves and is dispersed within the annular chamber 80. Thus, the yoke portion 21 of the stator 20 having the winding 27 located in the annular chamber 80 is in contact with the coolant, and the coolant transfers the heat generated by the winding 27 of the yoke portion 21 to the first end cover 50 and the second end cover 60. And, in turn, is dissipated into the surrounding environment by the first end cap 50 and the second end cap 60. Heat transfer due to coolant The rate is significantly greater than the thermal conductivity of the air. The coolant located in the annular chamber 80 will significantly reduce the thermal resistance from the winding to the end cap, improving the heat dissipation efficiency of the outer rotor type motor, thereby enabling the size of the outer rotor motor not to be increased. The power density of the outer rotor type motor is increased.

The invention has been described in detail above with reference to the specific embodiments. It is apparent that the above description and the embodiments shown in the drawings are intended to be illustrative and not restrictive. For example, although the outer rotor type motor is described as a hub motor in the preferred embodiment, it should be understood that the present invention is also applicable to other outer rotor type motors such as fan motors. It is apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

An outer rotor type motor (1) comprising: Axis (10); a stator (20) fixedly disposed on the shaft (10) around the shaft (10), wherein the stator (20) includes a yoke (21) formed by stacking a plurality of stator core pieces together And a support portion (23) located radially inward of the yoke portion (21) for fixedly supporting the yoke portion (21) on the shaft (10), the yoke portion (21) being radially Forming a plurality of winding teeth (25) outwardly, and windings (27) are respectively wound on each of the winding teeth (25); a rotor (30) disposed radially outward of the stator (20) about the shaft (10); a first end cap (50) rotatably supported on the shaft (10) by a first bearing (11) and fixedly coupled to the rotor (30); a second end cap (60) rotatably supported on the shaft (10) by a second bearing (13) and fixedly coupled to the rotor (30), the first end cap (50) and The second end cap (60) and at least a portion of the rotor (30) together define an interior space of the outer rotor type motor; Wherein, the first end cover (50) and the second end cover (60) respectively comprise a disc-shaped body (51), and a center of the disc-shaped body (51) is formed with the first bearing (11) Or a through hole (53) of the second bearing (13), the first end cover (50) and the second end cover (60) are further included inside the disc-shaped body (51) a radially outer outer edge portion (55) of the through hole (53), and a radially outer side of the through hole (53) and a radially inner side of the outer edge portion (55) toward the An annular flange (57) extending from the support portion (23) for contacting the rotor (30) and connected to the rotor (30), the rotor (30), a portion of the first end cap (50) located radially outward of the annular flange (57), the annular flange (57) of the first end cap (50), and the second end cap ( 60) a portion radially outward of the annular flange (57) and an annular flange of the second end cap (60) together define an annular chamber (80) having an annular slit (81), the yoke Part (21) is located in the ring In the shaped chamber (80), the support portion (23) passes through the annular slit (81), and the annular chamber (80) is at least partially filled with a cooling liquid. The outer rotor type motor (1) according to claim 1, wherein said outer edge portion of at least one of said first end cover (50) and said second end cover (60) An agitation means (90) for agitating the coolant is provided on a portion between the 55) and the annular flange (57). An outer rotor type motor (1) according to claim 2, wherein said agitating means (90) includes said outer peripheral portion (55) and said annular convex portion spaced apart from each other in the circumferential direction. A plurality of agitating ribs (91) between the edges (57). The outer rotor type motor (1) according to claim 3, characterized in that the agitating rib (91) extends from the outer edge portion (55) to the annular flange (57). The outer rotor type motor (1) according to claim 1, wherein said first end cover (50) and/or said second end cover (60) are further provided with said annular projection The rim (57) has a plurality of conductive ribs (93) extending toward the center and spaced apart from each other. The outer rotor type motor (1) according to claim 1, characterized in that a heat dissipating means is provided on the outer surface of the first end cap (50) and/or the second end cap (60). The outer rotor type motor (1) according to claim 1, characterized in that the annular flange (57) is disposed adjacent to a radially inner side of the yoke portion (21). The outer rotor type motor (1) according to claim 1, characterized in that the support portion (23) is formed with a plurality of openings (23b). The outer rotor type motor (1) according to claim 1, characterized in that the filling amount of the cooling liquid is equal to the volume of the annular chamber (80). The outer rotor type motor (1) according to any one of claims 1 to 8, characterized in that the outer rotor type motor is an in-wheel motor, and further comprising a radially outer side of the rotor (30) and A hub (70) that rotates with the rotor.

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