An outer-rotor direct-drive in-wheel motor with a stator oil-immersion cooling structure

Abstract

An outer-rotor direct-drive in-wheel motor with a stator oil-immersed cooling structure belongs to the field of in-wheel motor cooling. The present invention aims to solve the problem of difficult heat dissipation of existing in-wheel motors. The present invention includes a stator support, a stator oil sleeve, a stator assembly, an oil separation sleeve, a rotor assembly, and an outer-rotor housing; the rotor assembly is fixed inside the outer-rotor housing, and the stator assembly is arranged inside the rotor assembly with a radial air gap therebetween; a spiral cooling oil passage is arranged inside the stator assembly; the spiral cooling oil passage is formed by nesting the stator support and the stator oil sleeve fixed on its inner surface; an oil separation sleeve is arranged on the outer side and one annular end of the stator assembly, and the oil separation sleeve is used to prevent the cooling oil from entering the radial air gap between the stator and the rotor. The oil separation sleeve and the stator support enclose the stator assembly outside and form a cooling cavity.

Description

Technical Field

[0001] The present invention relates to an oil cooling technology for a direct drive hub motor, belonging to the field of hub motor cooling. Background Art

[0002] Nowadays, in the context of the era of green development, new energy vehicles are developing rapidly. Among them, the motor as the power source is the key to the manufacturing of new energy vehicles. Among various drive motors, the permanent magnet synchronous motor has been widely used in the design and manufacturing of new energy vehicles due to its high operating efficiency, large torque density, and relatively stable characteristics under high-speed operation. According to statistics, the usage rate of permanent magnet synchronous motors in new energy vehicles exceeds 90%, and it will still occupy a dominant position in the future. New energy vehicles driven by hub motors install the hub motor inside the electric vehicle wheels to drive the wheels to rotate coaxially, eliminating complex devices such as mechanical clutches, gearboxes, reducers, and drive shafts, simplifying the structure of the vehicle, and improving the power transmission efficiency of the drive system. Therefore, it has high research value.

[0003] In order to meet the actual needs of electric vehicle operation, hub motors need to meet requirements such as high power density, high torque density, and compact structure. Traditional air cooling, water cooling, and oil cooling methods can no longer meet the requirements. Moreover, for the structure of an in-line stator and outer-rotor direct drive hub motor, the heat generated by the losses in the stator is more difficult to transfer to the housing and dissipate, resulting in a higher internal temperature rise of the hub motor. An excessive temperature rise will affect the motor performance. Overheating of the motor is likely to cause operating failures and affect the service life of the motor. Therefore, adopting a reasonable motor cooling method is crucial for outer-rotor hub motors.

[0004] Currently, most motor oil cooling solutions adopt setting oil guide grooves or oil distribution holes in the yoke or teeth of the stator core, segmenting the motor using various punching sheet shapes, and setting stator oil channels at the segmented parts. Since it directly changes the shape of the stator punching sheet, it will more or less have a certain impact on the electromagnetic performance of the motor. Moreover, due to the adoption of various punching sheet structures, the manufacturing of the motor will become complex. However, this method is not suitable for outer-rotor direct drive hub motors and cannot achieve the same cooling effect as in-line motors.

[0005] Another oil cooling structure for fractional-slot concentrated winding motors is to set an oil channel in the slot between two concentrated windings. The cooling oil directly contacts the winding bars through the oil channel in the slot, thereby achieving a better cooling effect. However, this cooling structure requires a larger stator slot size and sufficient space for the cooling oil to flow. Therefore, the slot fill factor is low, which will prevent the efficiency and power density of the motor from being further improved.

[0006] Generally speaking, how to achieve efficient cooling of outer-rotor hub motors is a relatively difficult problem. Summary of the Invention

[0007] In view of the problem of difficult heat dissipation of existing in-wheel motors, the present invention provides an outer-rotor direct-drive in-wheel motor with a stator oil-immersion cooling structure.

[0008] The outer-rotor direct-drive in-wheel motor with a stator oil-immersion cooling structure according to the present invention includes a stator support member 1, a stator oil sleeve 2, a stator assembly 3, an oil separation sleeve 4, a rotor assembly 5, and an outer rotor housing 6;

[0009] The rotor assembly 5 is fixed inside the outer rotor housing 6, and the stator assembly 3 is arranged inside the rotor assembly 5 with a radial air gap therebetween;

[0010] A spiral cooling oil passage is arranged on the inner side of the stator assembly 3; the spiral cooling oil passage is formed by nesting the stator support member 1 and the stator oil sleeve 2 fixed to its inner surface; an oil separation sleeve 4 is arranged on the outer side and one annular end of the stator assembly 3, and the oil separation sleeve 4 is used to prevent the cooling oil from entering the radial air gap between the stator and the rotor. The oil separation sleeve 4 and the stator support member 1 enclose the stator assembly 3 externally and form a cooling cavity.

[0011] Preferably, the stator support member 1 includes an oil outlet 11, a plurality of end part oil distribution holes 12, a main body cylinder 13, an outer side fixing edge 14, and an end ring 15. The main body cylinder 13 and the outer side fixing edge 14 are coaxially fixedly connected through the end ring 15. The oil outlet 11 is opened on the end ring 15. A plurality of end part oil distribution holes 12 are opened outside the oil passage on the side close to the wheel spoke of the main body cylinder 13, and the plurality of end part oil distribution holes 12 are evenly distributed in the circumferential direction;

[0012] The main body cylinder 13 and the outer side fixing edge 14 are respectively arranged on the inner and outer circular surfaces of the stator assembly 3, and the end ring 15 is buckled on the other annular end of the stator assembly 3.

[0013] Preferably, the stator oil sleeve 2 is of a cylindrical structure. The stator oil sleeve 2 is arranged inside the main body cylinder 13 of the stator support member 1. A spiral cooling oil passage 22 is arranged on the barrel wall of the stator oil sleeve 2 on the side of the stator support member. An oil inlet 21 is arranged at the end of the first oil pipe of the spiral cooling oil passage 22, and the last oil pipe of the spiral cooling oil passage 22 is communicated with all the end part oil distribution holes 12.

[0014] Preferably, the stator assembly 3 includes a stator core 31, a stator winding 32, and a slot mouth oil passage 33. The stator slots of the stator core 31 adopt a semi-closed non-slot wedge structure. The stator winding 32 is arranged in the stator slots. The stator tooth part is in close contact with the oil separation sleeve 4. The oil separation sleeve 4 and the slot mouth at one annular end together form the slot mouth oil passage 33;

[0015] All the notch oil channels 33 and the spiral cooling oil channels 22 form the inner stator cooling oil passage. The cooling oil enters the spiral cooling oil channels 22 from the oil inlet 21, then enters the notch oil channels 33 of the stator assembly 3 through the end part oil distribution holes 12 to cool down the stator winding 32, and finally flows out through the oil outlet 11 located at the bottom of the cooling cavity for the next cycle.

[0016] Preferably, both ends of the oil separation sleeve 4 are closely attached to the end part of the stator support 1 and the end part of the stator oil sleeve 2 respectively through the inner sealing rubber rings 41, and are fixed on the outside through the oil separation sleeve seal 42.

[0017] Advantages of the present invention: The present invention provides an outer rotor direct drive hub motor with a stator oil immersion cooling structure. This cooling structure enables the direct contact between the cooling oil and the winding and the stator, shortens the heat transfer path, and allows the winding and the stator to be fully cooled.

[0018] Only a single punching sheet is required, without changing the stator structure, which has strong applicability. And due to the existence of the stator-rotor oil separation sleeve, it avoids the cooling oil from entering the air gap and prevents the stirring oil loss caused by the rotation of the rotor driving the cooling oil.

[0019] Adopting a slot wedge-free design and cooperating with the oil separation sleeve to use the notch as the flow path of the cooling oil. Compared with the traditional in-slot oil cooling scheme, it is not necessary to design a larger stator slot size, improves the slot filling rate, and enables the motor to achieve higher efficiency and power density.

[0020] The structure is relatively simple, easy to manufacture and install, avoiding the increase in the unsprung mass of the hub motor caused by overly complex structure and the reduction in reliability during operation under complex working conditions. Description of the Drawings

[0021] Figure 1 is an exploded view of the outer rotor direct drive hub motor with a stator oil immersion cooling structure provided by an embodiment of the present invention;

[0022] Figure 2 is an axial sectional view of the outer rotor direct drive hub motor with a stator oil immersion cooling structure provided by an embodiment of the present invention;

[0023] Figure 3 is a structural schematic diagram of the stator support;

[0024] Figure 4 is a schematic diagram of the oil passage formed by the cooperation of the stator support and the oil sleeve;

[0025] Figure 5 is a schematic diagram of the cooling oil flow path of the outer rotor direct drive hub motor with a stator oil immersion cooling structure provided by an embodiment of the present invention;

[0026] Figure 6It is a partial enlarged schematic diagram of the oil path without slot wedges of the stator of an outer-rotor direct-drive hub motor with a stator oil-immersion cooling structure provided by an embodiment of the present invention.

[0027] In all the drawings, the components or structures represented by the respective reference numerals are as follows:

[0028] 1 - Stator support, 11 - Oil outlet, 12 - End part oil hole, 13 - Main body cylinder, 14 - Outer fixed edge, 15 - End ring 15;

[0029] 2 - Stator oil sleeve, 21 - Oil inlet, 22 - Spiral cooling oil channel;

[0030] 3 - Stator assembly, 31 - Stator core, 32 - Winding, 33 - Notch oil channel;

[0031] 4 - Oil separation sleeve, 41 - Sealing rubber ring, 42 - Oil separation sleeve seal;

[0032] 5 - Rotor assembly;

[0033] 6 - Outer rotor housing. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] Next, the present invention will be further described in conjunction with the drawings and specific embodiments, but it is not a limitation of the present invention.

[0037] Detailed implementation manner one: Next, in conjunction with Figures 1 to 6 This implementation manner will be described. The outer-rotor direct-drive hub motor with a stator oil-immersion cooling structure described in this implementation manner includes a stator support 1, a stator oil sleeve 2, a stator assembly 3, an oil separation sleeve 4, a rotor assembly 5, and an outer rotor housing 6;

[0038] The rotor assembly 5 is fixed inside the outer rotor housing 6, and the stator assembly 3 is arranged inside the rotor assembly 5 with a radial air gap therebetween;

[0039] A spiral cooling oil passage is arranged inside the stator assembly 3; the spiral cooling oil passage is formed by nesting the stator support 1 and the stator oil sleeve 2 that fixes its inner surface; an oil separation sleeve 4 is arranged on the outer side and one annular end of the stator assembly 3, and the oil separation sleeve 4 is used to prevent the cooling oil from entering the radial air gap between the stator and the rotor. The oil separation sleeve 4 and the stator support 1 enclose the outside of the stator assembly 3 and form a cooling cavity.

[0040] The stator support 1 includes an oil outlet 11, a plurality of end part oil distribution holes 12, a main body cylinder 13, an outer fixed edge 14 and an end ring 15. The main body cylinder 13 and the outer fixed edge 14 are coaxially and fixedly connected through the end ring 15. The oil outlet 11 is arranged on the end ring 15. A plurality of end part oil distribution holes 12 are arranged outside the oil passage on the side of the main body cylinder 13 close to the spoke, and the plurality of end part oil distribution holes 12 are evenly distributed in the circumferential direction;

[0041] The main body cylinder 13 and the outer fixed edge 14 are respectively arranged on the inner and outer circular surfaces of the stator assembly 3, and the end ring 15 is buckled on the other annular end of the stator assembly 3.

[0042] The stator oil sleeve 2 is of a cylindrical structure. The stator oil sleeve 2 is arranged inside the main body cylinder 13 of the stator support 1. A spiral cooling oil passage 22 is arranged on the cylinder wall of the stator oil sleeve 2 on the side of the stator support. An oil inlet 21 is arranged at the end of the first oil pipe of the spiral cooling oil passage 22, and the last oil pipe of the spiral cooling oil passage 22 is communicated with all the end part oil distribution holes 12.

[0043] The stator assembly 3 includes a stator core 31, a stator winding 32 and a slot oil passage 33. The stator slots of the stator core 31 adopt a semi-closed non-slot wedge structure. The stator winding 32 is arranged in the stator slots. The stator tooth portion is in close contact with the oil separation sleeve 4. The oil separation sleeve 4 and the slot at one annular end together form the slot oil passage 33;

[0044] All the slot oil passages 33 and the spiral cooling oil passage 22 form a stator inner side cooling oil passage. The cooling oil enters the spiral cooling oil passage 22 from the oil inlet 21, then enters the slot oil passage 33 of the stator assembly 3 from the end part oil distribution holes 12 to cool the stator winding 32, and finally flows out through the oil outlet 11 at the bottom of the cooling cavity for the next cycle.

[0045] Both ends of the oil separation sleeve 4 are respectively closely attached to the end of the stator support 1 and the end of the stator oil sleeve 2 through the inner sealing rubber ring 41, and are fixed on the outside through the oil separation sleeve seal 42.

[0046] The following is a specific description with reference to the drawings. Refer to Figures 1 to 6Specifically describing this embodiment, the outer-rotor direct-drive hub motor with a stator oil-immersion cooling structure provided in this embodiment includes: an inner stator and an outer rotor arranged coaxially, an oil separation sleeve and an air gap existing between the inner stator and the outer rotor, a stator support member nested inside the stator, a stator oil sleeve nested inside the stator support member, and an outer rotor housing nested outside the outer rotor.

[0047] Referring to Figure 2 and Figure 5 , in this embodiment, an oil separation sleeve 4 is provided outside the stator assembly 3 and is in close contact with the stator tooth portion. Both ends of the oil separation sleeve 4 are respectively in close contact with the end portions of the stator support member 1 and the stator oil sleeve 2 through the inner sealing rubber rings 41, and are fixed by the oil separation sleeve seal 42. This structure can effectively prevent the cooling oil from entering the air gap between the stator and the rotor, and prevent the oil churning loss caused by the rotation of the rotor driving the cooling oil.

[0048] Referring to Figure 6 , in this embodiment, the stator core 31 adopts a semi-closed slot without slot wedge design. The stator tooth portion is in close contact with the oil separation sleeve 4, and together with the slot opening, it forms a slot opening oil passage 33. The windings in the slot and various insulating materials are potted and fixed by potting glue to prevent the stator winding 32 and other insulating materials from shifting and falling off due to vibration, strengthen the integrity of the materials in the slot, and improve the resistance to external impacts and vibrations. For a vehicle hub motor, the potting material used should have excellent high-temperature resistance and electrical insulation ability, strong adhesion to hard materials, strong resistance to cold and heat changes, and a relatively high thermal conductivity. In this embodiment, a composite resin material is used for slot filling.

[0049] Referring to Figure 2 , Figure 3 and Figure 4 , in this embodiment, the stator support member 1 is tightly nested outside the stator oil sleeve 2. The outer surface of the stator oil sleeve 2 is provided with a spiral cooling oil passage 22, which together with the inner surface of the stator support member 1 forms a stator inner cooling oil passage. The cooling oil enters the spiral cooling oil passage 22 through the oil inlet 21. The stator support member 1 is provided with a plurality of end oil distribution holes 12 on the side close to the outer rotor housing 6, and the oil distribution holes are evenly distributed in the circumferential direction. Each oil distribution hole is connected to the last oil passage of the spiral cooling oil passage 22, and the cooling oil can enter the cooling cavity composed of the stator support member 1 and the oil separation sleeve 4 through each oil distribution hole from the spiral cooling oil passage 22.

[0050] Referring to Figure 5 and Figure 6, after the cooling oil enters the cooling cavity formed by the stator support member 1 and the oil separation sleeve 4 through the end partial oil hole 12, based on the oil circuit arrangement in this embodiment, the cooling oil will preferentially fill the cavity on the side far from the oil inlet 21. Due to the semi-closed non-slot wedge design at the slot opening, under the action of pressure, the cooling oil will enter the slot oil passage 33, enter the cavity on the side close to the oil inlet 21 through the slot oil passage 33, and finally flow out through the oil outlet 11 located at the bottom of this cavity for the next cycle. The oil passage design in this embodiment can make the iron cores of the stator winding 32 and the stator core 31 directly contact the cooling oil, increasing the heat dissipation area of the winding, effectively shortening the heat propagation path, effectively solving the problem of excessive motor temperature rise caused by too long heat transfer path and too large thermal resistance, enabling the stator winding 32 and the stator core 31 to be fully cooled, effectively reducing the motor temperature rise, enabling the motor to withstand a higher load under the same conditions, and improving the power density of the outer rotor direct drive hub motor.

[0051] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. An outer-rotor direct-drive in-wheel motor with a stator oil-immersed cooling structure, characterized in that It includes a stator support (1), a stator oil sleeve (2), a stator assembly (3), an oil separation sleeve (4), a rotor assembly (5), and an outer rotor housing (6); The rotor assembly (5) is fixed inside the outer rotor housing (6), and the stator assembly (3) is arranged inside the rotor assembly (5) with a radial air gap therebetween; A spiral cooling oil passage is arranged inside the stator assembly (3); the spiral cooling oil passage is formed by nesting the stator support (1) and the stator oil sleeve (2) fixed to its inner surface. The stator support (1) is provided with an oil outlet (11) and a plurality of end part oil distribution holes (12); an oil separation sleeve (4) is arranged on the outer side and one side annular end of the stator assembly (3). The oil separation sleeve (4) is used to prevent the cooling oil from entering the radial air gap between the stator and the rotor. The oil separation sleeve (4) and the stator support (1) enclose the outside of the stator assembly (3) to form a cooling cavity; The stator assembly (3) includes a stator core (31), a stator winding (32), and a slot mouth oil passage (33). The stator slots of the stator core (31) adopt a semi-closed non-slot wedge structure. The stator winding (32) is arranged in the stator slots. The stator tooth part is in close contact with the oil separation sleeve (4), and the oil separation sleeve (4) and the slot mouth at one side annular end together constitute the slot mouth oil passage (33); All the slot mouth oil passages (33) at the annular ends and the spiral cooling oil passage (22) constitute the stator inner side cooling oil passage. The cooling oil enters the spiral cooling oil passage (22) from the oil inlet (21), then enters the slot mouth oil passage (33) of the stator assembly (3) from the end part oil distribution holes (12) to cool the stator winding (32), and finally flows out through the oil outlet (11) located at the bottom of the cooling cavity for the next cycle.

2. The outer-rotor direct-drive hub motor with a stator oil-immersion cooling structure according to claim 1, wherein The stator support (1) includes an oil outlet (11), a plurality of end part oil distribution holes (12), a main body cylinder (13), an outer side fixing edge (14), and an end ring (15). The main body cylinder (13) and the outer side fixing edge (14) are coaxially fixedly connected through the end ring (15). The oil outlet (11) is opened on the end ring (15). A plurality of end part oil distribution holes (12) are opened outside the oil passage on the side of the main body cylinder (13) close to the spoke, and the plurality of end part oil distribution holes (12) are evenly distributed in the circumferential direction; The main body cylinder (13) and the outer side fixing edge (14) are respectively arranged on the inner and outer circular surfaces of the stator assembly (3), and the end ring (15) is buckled on the other side annular end of the stator assembly (3).

3. The outer-rotor direct-drive hub motor with a stator oil-immersion cooling structure according to claim 2, characterized in that, The stator oil sleeve (2) is of a cylindrical structure. The stator oil sleeve (2) is arranged inside the main body cylinder (13) of the stator support (1). A spiral cooling oil passage (22) is arranged on the cylinder wall of the stator oil sleeve (2) on the side of the stator support. An oil inlet (21) is arranged at the end of the first oil pipe of the spiral cooling oil passage (22), and the last oil pipe of the spiral cooling oil passage (22) is communicated with all the end part oil distribution holes (12).

4. The outer-rotor direct-drive hub motor with a stator oil-immersion cooling structure according to claim 1, characterized in that, Both ends of the oil separation sleeve (4) are respectively closely attached to the ends of the stator support (1) and the stator oil sleeve (2) through the inner side sealing rubber rings (41), and are fixed on the outer side through the oil separation sleeve seal (42).

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