Outer rotor direct drive hub motor with stator oil immersion cooling structure

Abstract

The invention discloses an outer rotor direct-drive hub motor with a stator oil immersion cooling structure, belongs to the field of hub motor cooling, and aims to solve the problem of difficulty in heat dissipation of an existing hub motor. The motor comprises a stator support member, a stator oil sleeve, a stator assembly, an oil separation sleeve, a rotor assembly and an outer rotor casing. A rotor assembly is fixed in the outer rotor casing, a stator assembly is arranged in the rotor assembly, and a radial air gap exists between the rotor assembly and the stator assembly; a spiral cooling oil duct is arranged on the inner side of the stator assembly; the spiral cooling oil duct is formed by nesting a stator supporting piece and a stator oil sleeve fixed on the inner surface of the stator supporting piece; an oil separation sleeve is arranged on the outer side and the annular end portion of one side of the stator assembly, the oil separation sleeve is used for preventing cooling oil from entering a radial air gap between the stator and the rotor, and the oil separation sleeve and the stator supporting piece are enclosed outside the stator assembly and form a cooling cavity.

Description

Technical Field

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

[0002] Nowadays, in the context of green development, new energy vehicles are developing rapidly. Among them, the motor as a power source is the key to the manufacturing of new energy vehicles. Among various types of drive motors, permanent magnet synchronous motors have been widely used in the design and manufacture of new energy vehicles due to their high operating efficiency, large torque density and relatively stable characteristics under high-speed operation. According to statistics, the utilization 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 wheel hub motors install the wheel hub motor inside the wheels of electric vehicles 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 a high research value.

[0003] In order to meet the actual needs of electric vehicle operation, the hub motor needs to meet the requirements of high power density, high torque density and compact structure. Traditional air cooling, water cooling and oil cooling methods can no longer meet the requirements. In addition, for the direct-drive hub motor structure with inner stator and outer rotor, the heat generated by the loss in the stator is more difficult to transfer to the casing and dissipate, resulting in a higher internal temperature rise of the hub motor. Excessive temperature rise will affect the performance of the motor, and overheating of the motor can easily cause operating failures and affect the service life of the motor. Therefore, it is very important to adopt a reasonable motor cooling method for the outer rotor hub motor.

[0004] At present, most motor oil cooling solutions use oil guide grooves or oil distribution holes on the stator core yoke or tooth part, use a variety of punching sheet shapes to segment the motor, and set stator oil channels at the segments. 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. In addition, due to the use of a variety of punching sheet structures, the manufacture of the motor will also become complicated. However, this method is not suitable for outer rotor direct-drive hub motors and cannot achieve the same cooling effect as inner rotor motors.

[0005] Another oil cooling structure for fractional-slot concentrated winding motors is to set an in-slot oil channel between the two concentrated windings in the slot. The cooling oil directly contacts the winding bars through the in-slot oil channel, 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 rate is low, which will prevent the efficiency and power density of the motor from being further improved.

[0006] In general, 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 heat dissipation difficulty in existing hub motors, the present invention provides an outer rotor direct-drive hub motor with a stator oil-immersion cooling structure.

[0008] The outer rotor direct-drive hub motor with a stator oil-immersion cooling structure described in the present invention comprises a stator support 1, a stator oil jacket 2, a stator assembly 3, an oil separator 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 between the two;

[0010] A spiral cooling oil channel is arranged on the inner side of the stator assembly 3; the spiral cooling oil channel is formed by the stator support 1 and the stator oil jacket 2 fixed on its inner surface being nested; an oil separator 4 is arranged on the outer side of the stator assembly 3 and on one side of the annular end, and the oil separator 4 is used to prevent cooling oil from entering the radial air gap between the stator and the rotor, and the oil separator 4 and the stator support 1 are enclosed outside the stator assembly 3 to form a cooling cavity.

[0011] Preferably, the stator support 1 comprises an oil outlet 11, a plurality of end oil 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 fixedly connected through the end ring 15, the end ring 15 is provided with the oil outlet 11, a plurality of end oil holes 12 are provided outside the oil passage near the spoke side of the main body cylinder 13, and the plurality of end oil holes 12 are evenly distributed along the circumferential direction;

[0012] The main cylinder 13 and the outer 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 annular end of the other side of the stator assembly 3 .

[0013] Preferably, the stator oil jacket 2 is a cylindrical structure, and the stator oil jacket 2 is arranged inside the main cylinder 13 of the stator support 1. The stator oil jacket 2 is provided with a spiral cooling oil channel 22 on the cylinder wall on the stator support side, and an oil inlet 21 is provided at the first oil pipe end of the spiral cooling oil channel 22, and the last oil pipe of the spiral cooling oil channel 22 is connected to all end oil holes 12.

[0014] Preferably, the stator assembly 3 includes a stator core 31, a stator winding 32 and a slot oil passage 33. The stator slot of the stator core 31 adopts a semi-closed slot wedge-free structure, the stator winding 32 is arranged in the stator slot, the stator teeth are in close contact with the oil separator 4, and the oil separator 4 and the slot at one side of the annular end together constitute the slot oil passage 33;

[0015] All the slotted oil passages 33 and the spiral cooling oil passages 22 constitute the stator inner cooling oil passage. The cooling oil enters the spiral cooling oil passage 22 from the oil inlet 21, and then enters the slotted oil passage 33 of the stator assembly 3 from the end oil hole 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.

[0016] Preferably, two ends of the oil separator 4 are respectively tightly attached to the end of the stator support 1 and the end of the stator oil jacket 2 through an inner sealing rubber ring 41 , and are fixed on the outside through an oil separator seal 42 .

[0017] Beneficial effects of the present invention: The present invention provides an outer rotor direct-drive hub motor with a stator oil-immersed cooling structure, wherein the cooling structure enables direct contact between the cooling oil and the windings and stator, shortens the heat transfer path, and enables the windings and stator to be fully cooled.

[0018] A single punching sheet is sufficient without changing the stator structure, and the applicability is strong. In addition, due to the existence of the stator-rotor spacing oil sleeve, the cooling oil is prevented from entering the air gap, thereby preventing the oil churning loss caused by the cooling oil driven by the rotor rotation.

[0019] The slot-less wedge design is adopted, and the slot opening is used as the circulation path for the cooling oil in combination with the oil separator. Compared with the traditional in-slot oil cooling solution, there is no need to design a larger stator slot size, which improves the slot fill rate and enables the motor to achieve higher efficiency and power density.

[0020] The structure is relatively simple and easy to manufacture and install, avoiding the increase of the unsprung mass of the hub motor due to an overly complex structure and the reduction of reliability when operating under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0026] Figure 6It is a partially enlarged schematic diagram of the stator wedge-free oil circuit 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 elements or structures represented by the reference numerals are as follows:

[0028] 1-stator support, 11-oil outlet, 12-end oil hole, 13-main cylinder, 14-outer fixed edge, 15-end ring 15;

[0029] 2-stator oil jacket, 21-oil inlet, 22-spiral cooling oil channel;

[0030] 3-stator assembly, 31-stator core, 32-winding, 33-slot oil channel;

[0031] 4-oil separator, 41-sealing rubber ring, 42-oil separator seal;

[0032] 5-Rotor assembly;

[0033] 6-Outer rotor casing. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0036] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0037] Specific implementation method 1: The following is combined Figures 1 to 6 The present embodiment is described. The outer rotor direct-drive hub motor with a stator oil-immersed cooling structure described in the present embodiment comprises a stator support 1, a stator oil jacket 2, a stator assembly 3, an oil separator 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 between the two;

[0039] A spiral cooling oil channel is arranged on the inner side of the stator assembly 3; the spiral cooling oil channel is formed by the stator support 1 and the stator oil jacket 2 fixed on its inner surface being nested; an oil separator 4 is arranged on the outer side of the stator assembly 3 and on one side of the annular end, and the oil separator 4 is used to prevent cooling oil from entering the radial air gap between the stator and the rotor, and the oil separator 4 and the stator support 1 are enclosed outside the stator assembly 3 to form a cooling cavity.

[0040] The stator support 1 comprises an oil outlet 11, a plurality of end oil holes 12, a main cylinder 13, an outer fixed edge 14 and an end ring 15. The main cylinder 13 and the outer fixed edge 14 are coaxially fixedly connected through the end ring 15. The end ring 15 is provided with the oil outlet 11. A plurality of end oil holes 12 are provided outside the oil passage near the spoke side of the main cylinder 13, and the plurality of end oil holes 12 are evenly distributed along the circumferential direction.

[0041] The main cylinder 13 and the outer 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 annular end of the other side of the stator assembly 3 .

[0042] The stator oil jacket 2 is a cylindrical structure. The stator oil jacket 2 is arranged inside the main cylinder 13 of the stator support 1. The stator oil jacket 2 is provided with a spiral cooling oil channel 22 on the cylinder wall on the stator support side, and an oil inlet 21 is provided at the first oil pipe end of the spiral cooling oil channel 22. The last oil pipe of the spiral cooling oil channel 22 is connected to all end oil holes 12.

[0043] The stator assembly 3 includes a stator core 31, a stator winding 32 and a slot oil passage 33. The stator slot of the stator core 31 adopts a semi-closed wedge-free structure. The stator winding 32 is arranged in the stator slot. The stator teeth are in close contact with the oil separator 4. The oil separator 4 and the slot at one side of the annular end together constitute the slot oil passage 33.

[0044] All the slotted oil passages 33 and the spiral cooling oil passages 22 constitute the stator inner cooling oil passage. The cooling oil enters the spiral cooling oil passage 22 from the oil inlet 21, and then enters the slotted oil passage 33 of the stator assembly 3 from the end oil hole 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] The two ends of the oil separator 4 are respectively tightly attached to the end of the stator support 1 and the end of the stator oil jacket 2 through the inner sealing rubber ring 41, and are fixed on the outside by the oil separator seal 42.

[0046] The following is a detailed description with reference to the accompanying drawings. Figures 1 to 6Specifically describing this embodiment, the outer rotor direct-drive hub motor with a stator oil-immersed cooling structure provided in this embodiment includes: an inner stator and an outer rotor arranged coaxially, an oil separator and an air gap between the inner stator and the outer rotor, a stator support member nested on the inner side of the stator, a stator oil jacket nested on the inner side of the stator support member, and an outer rotor casing nested on the outer side of the outer rotor.

[0047] Reference Figure 2 and Figure 5 In this embodiment, an oil separator 4 is provided on the outside of the stator assembly 3 and is close to the stator teeth. The two ends of the oil separator 4 are respectively close to the end of the stator support 1 and the end of the stator oil jacket 2 through the inner sealing rubber ring 41, and are fixed by the oil separator 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 stirring loss caused by the cooling oil driven by the rotation of the rotor.

[0048] Reference Figure 6 In this embodiment, the stator core 31 adopts a semi-closed slot without slot wedge design, and the stator teeth are in close contact with the oil separator 4, and together with the slot, they form a slot oil channel 33. The windings and various insulating materials in the slot are potted and fixed by potting glue to prevent the stator windings 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 impact and vibration. For automotive hub motors, the potting material used should have excellent high temperature resistance and electrical insulation ability, strong adhesion to hard materials, strong resistance to cold and hot changes, and high thermal conductivity. In this embodiment, a composite resin material is used to fill the slot.

[0049] Reference Figure 2 , Figure 3 and Figure 4 In this embodiment, the stator support 1 is closely nested on the outside of the stator oil jacket 2. The outer surface of the stator oil jacket 2 is provided with a spiral cooling oil channel 22, which together with the inner surface of the stator support 1 constitutes the stator inner cooling oil passage, and the cooling oil enters the spiral cooling oil channel 22 through the oil inlet 21. The stator support 1 is provided with a plurality of end oil distribution holes 12 on the side close to the outer rotor housing 6, and each oil distribution hole is evenly distributed on the circumference, and each oil distribution hole is connected with the last oil channel of the spiral cooling oil channel 22. The cooling oil can enter the cooling cavity composed of the stator support 1 and the oil separator 4 through each oil distribution hole from the spiral cooling oil channel 22.

[0050] Reference Figure 5 and Figure 6After the cooling oil enters the cooling cavity composed of the stator support 1 and the oil separator 4 from the end oil hole 12, based on the setting of the oil circuit in this embodiment, the cooling oil will first fill the cavity away from the oil inlet 21. Since the slot adopts a semi-closed slot-free wedge design, under the action of pressure, the cooling oil will enter the slot oil channel 33, enter the cavity near the oil inlet 21 through the slot oil channel 33, and finally flow out through the oil outlet 11 at the bottom of the cavity for the next cycle. The oil channel design in this embodiment can make the stator winding 32 and the stator core 31 directly contact with the cooling oil, increase the heat dissipation area of ​​the winding, effectively shorten the heat transfer path, and effectively solve the problem of excessive motor temperature rise caused by too long heat transfer path and too large thermal resistance, so that the stator winding 32 and the stator core 31 are fully cooled, effectively reducing the motor temperature rise. Under the same conditions, the motor can withstand a higher load, so that the power density of the outer rotor direct drive hub motor is improved.

[0051] Although the present invention is 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. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. An outer rotor direct drive hub motor with a stator oil immersion cooling structure, characterized in that: It comprises a stator support (1), a stator oil jacket (2), a stator assembly (3), an oil separator (4), a rotor assembly (5) and an outer rotor casing (6); A rotor assembly (5) is fixed inside the outer rotor housing (6), and a stator assembly (3) is arranged inside the rotor assembly (5) with a radial air gap between the two. A spiral cooling oil channel is arranged inside the stator assembly (3); the spiral cooling oil channel is formed by the stator support (1) and a stator oil sleeve (2) fixed to the inner surface thereof being nested; an oil separator sleeve (4) is arranged on the outer side of the stator assembly (3) and on one side of the annular end; the oil separator sleeve (4) is used to prevent cooling oil from entering the radial air gap between the stator and the rotor; the oil separator sleeve (4) and the stator support (1) are enclosed outside the stator assembly (3) to form a cooling cavity.

2. The outer rotor direct drive hub motor with stator oil immersion cooling structure according to claim 1, characterized in that: The stator support (1) comprises an oil outlet (11), a plurality of end oil 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 fixedly connected via the end ring (15); the end ring (15) is provided with the oil outlet (11); a plurality of end oil holes (12) are provided outside the oil passage on the spoke side of the main body cylinder (13); and the plurality of end oil holes (12) are evenly distributed along the circumferential direction; 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 annular end of the other side of the stator assembly (3).

3. The outer rotor direct drive hub motor with stator oil immersion cooling structure according to claim 2, characterized in that: The stator oil jacket (2) is a cylindrical structure. The stator oil jacket (2) is arranged inside a main cylinder (13) of a stator support (1). The stator oil jacket (2) is provided with a spiral cooling oil channel (22) on the cylinder wall on the stator support side, and an oil inlet (21) is provided at the end of the first oil pipe of the spiral cooling oil channel (22). The last oil pipe of the spiral cooling oil channel (22) is connected to all end oil holes (12).

4. The outer rotor direct drive hub motor with stator oil immersion cooling structure according to claim 2, characterized in that: The stator assembly (3) comprises a stator core (31), a stator winding (32) and a slot oil passage (33); the stator slot of the stator core (31) adopts a semi-closed slot-free wedge structure; the stator winding (32) is arranged in the stator slot; the stator tooth portion is in close contact with the oil separator (4); the oil separator (4) and the slot at one side of the annular end together form the slot oil passage (33); The slotted oil passages (33) at all the annular ends and the spiral cooling oil passage (22) constitute a stator inner cooling oil passage. The cooling oil enters the spiral cooling oil passage (22) from the oil inlet (21), then enters the slotted oil passage (33) of the stator assembly (3) from the end oil hole (12), cools the stator winding (32), and finally flows out through the oil outlet (11) at the bottom of the cooling cavity for the next cycle.

5. The outer rotor direct drive hub motor with stator oil immersion cooling structure according to claim 1, characterized in that: The two ends of the oil separator (4) are respectively tightly 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 separator seal (42).

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