WO2022137862A1 - This semiconductor device comprises: a semiconductor layer having a main surface; a first conductive-type well region formed on a surface layer portion of the main surface of the semiconductor layer; a first conductive-type first impurity region formed on a surface layer portion of the well region and having an inner wall portion; and a second conductive-type annular second impurity region formed on the surface layer portion of the well region inside the inner wall part so as to form a pn junction with the well region. - Google Patents

Abstract

The present invention comprises: a stator core (2X) around which a plurality of coils (2Z) are wound; a stator case (2W) that supports the stator core (2X); a rotor core (4X) disposed to be rotatable relative to the stator core (2X) with a gap (7) therebetween; a rotor case (4W) that supports the rotor core (4X); and a first bearing (11A) and a second bearing (11B) that connect the stator case (2W) and the rotor case (4W). Rolling elements (10) of the first bearing (11A) and the second bearing (11B) and coil end parts of the coils (2Z) are arranged in a liquid refrigerant path (15) in which a liquid refrigerant is accommodated. The gap (7) serves as a first flow path through which the liquid refrigerant flows in an axial direction. The first bearing (11A) is disposed on the upstream side of the first flow path. The second bearing (11B) is disposed on the downstream side of the first flow path. The inner diameter of the second bearing (11B) is greater than the inner diameter of the first bearing (11A).

Description

Rotating electric machine and vehicle

The present invention relates to a rotary electric machine and a vehicle.

An in-wheel motor built into a wheel is known for a rotary electric machine equipped with a stator fixed to a stator case and a rotor fixed to a rotor case rotatably joined to the stator case via bearings. (See Patent Document 1). Patent Document 1 describes an in-wheel motor system in which a reservoir tank containing a coolant is arranged outside the in-wheel motor, and the reservoir tank and the gap between the stator and the rotor are communicated by a pipe. It has been disclosed.

JP-A-2005-333706

In the system described in Patent Document 1, when the motor is continuously driven, the temperature of the coolant rises due to the heat generated by the stator, and the bearing becomes hot, so that the life thereof is shortened. There is a risk.

The present invention aims to extend the life of bearings of rotary electric machines.

In order to solve the above problems, the rotary electric machine according to one aspect of the present invention can rotate the stator core in which a plurality of coils are wound, the stator case that supports the stator core, and the stator core through a gap. A rotor core arranged in, a rotor case that supports the rotor core, and a first bearing and a second bearing that connect the stator case and the rotor case are provided, and the first bearing and the second bearing are rolled. The moving body and the coil end portion of the coil are arranged in a liquid refrigerant path in which the liquid refrigerant is housed, the gap is a first flow path through which the liquid refrigerant flows in the axial direction, and the first bearing is the first bearing. The second bearing is arranged on the liquid refrigerant inlet side of the first flow path, the second bearing is arranged on the liquid refrigerant outlet side of the first flow path, and the inner diameter of the second bearing is larger than the inner diameter of the first bearing. It is a rotary electric machine.

According to the present invention, the bearing of a rotary electric machine can be extended in life.

The schematic diagram which shows the structure of the vehicle which concerns on 1st Embodiment. The exploded perspective view which shows the structure of the electric wheel which concerns on 1st Embodiment. The schematic cross-sectional view which shows the structure of the in-wheel motor which concerns on 1st Embodiment. Partial sectional perspective view which shows the structure of the in-wheel motor which concerns on 2nd Embodiment. The perspective view of the annular flow path of the liquid refrigerant passage which concerns on 2nd Embodiment. A partial cross-sectional perspective view of an annular flow path inlet near the first coil end portion of the liquid refrigerant path according to the second embodiment as viewed from the side surface. A partial cross-sectional perspective view of an annular flow path inlet near the first coil end portion of the liquid refrigerant path according to the second embodiment as viewed from above. The partial sectional view which shows the structure of the bearing which concerns on 2nd Embodiment. A graph showing the relationship between bearing operating clearance and fatigue life. The graph which shows the relationship between the inner diameter of a bearing and a bearing clearance. A partial cross-sectional perspective view showing a configuration of an in-wheel motor according to a third embodiment. FIG. 6 is a partial cross-sectional view showing the configuration of an in-wheel motor according to a fourth embodiment. Explanatory drawing of thrust force in comparative example. The explanatory view of the thrust force in the in-wheel motor which concerns on 4th Embodiment. FIG. 6 is a partial cross-sectional view showing the configuration of an in-wheel motor according to a fifth embodiment.

[First Embodiment]
Hereinafter, the vehicle 1000 according to the first embodiment of the present invention and the in-wheel motor 50 mounted on the vehicle 1000 will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic view showing the configuration of a vehicle 1000 according to the first embodiment of the present invention. As shown in FIG. 1, the vehicle 1000 of the present embodiment includes a vehicle body frame 1010, a battery base 1020 arranged inside the vehicle body frame 1010, a battery 1030 mounted on the battery base 1020, and wheels (front wheels). And rear wheels). Each wheel (left and right front wheels and left and right rear wheels) has an electric wheel 200 and a tire 800 attached to the outer periphery of the electric wheel 200. The inverter 150 is mounted on the electric wheel 200.

Each electric wheel 200 is connected to the battery 1030 by the power cable PL. The inverter 150 converts the DC power supplied from the battery 1030 into AC power and supplies it to the in-wheel motor 50 mounted on the electric wheel 200.

The in-wheel motor 50 mounted on the electric wheel 200 of the present embodiment has a high torque density. Therefore, the in-wheel motor 50 can directly drive the wheels of the vehicle 1000. That is, in the present embodiment, it is possible to make the vehicle 1000 gearless, that is, to directly drive the wheels.

The vehicle 1000 according to this embodiment has the same running performance as a vehicle equipped with a gasoline engine. For example, the vehicle 1000 can operate at a constant speed of 50 km in an urban area. In addition, the acceleration performance is equal to or better than that of a vehicle equipped with a gasoline engine.

Next, the size of the electric wheel 200 of this embodiment will be described. Currently, the size of wheels used in automobiles is standardized. Wheel size is usually expressed in terms of rim diameter. The rim diameter is shown in inches. The electric wheel 200 has, for example, a rim diameter of 14 inches (355.6 mm), 15 inches (381 mm), 16 inches (406.4 mm), 17 inches (431.8 mm), 18 inches (457.2 mm), and 19 inches. It can be mounted on a (482.6 mm) or 20 inch (508 mm) wheel.

Below, the electric wheel 200 having a wheel having a rim diameter of 19 inches (482.6 mm) and a rim width of 8.5 inches (21.6 mm) will be described.

FIG. 2 shows an exploded perspective view of the electric wheel 200. As shown in FIG. 2, the electric wheel 200 of the present embodiment includes a wheel 100 to which a tire is attached and an in-wheel motor 50 attached to the wheel 100. A disc brake 106 that generates a braking force for braking the wheel is attached to the electric wheel 200. The electric wheel 200 is attached to the vehicle body frame 1010 via the suspension device 110. The suspension device 110 has a knuckle 107 fixed to the in-wheel motor 50 and a lower arm 108 rotatably attached to the knuckle 107. Further, the suspension device 110 includes a shock absorber 109a rotatably connected to the knuckle 107, and a spring 109b attached between the shock absorber 109a and the support member provided on the vehicle body frame 1010.

A hub bearing HUB that supports the wheel is arranged near the wheel axle AX of the wheel 100. The stator 2 is joined to the wheel via the hub bearing HUB. Part of the weight of the vehicle body is supported by the suspension device 110 including the knuckle 107 via the wheel 100, the hub bearing HUB, and the stator 2. Inside the wheel 100, main parts for driving the electric wheel 200 are housed.

The in-wheel motor 50 mounted on the electric wheel 200 is supplied with a liquid refrigerant for cooling each component constituting the in-wheel motor 50. The liquid refrigerant is supplied into the in-wheel motor 50 by a pump (not shown) provided outside the electric wheel 200. The pipe through which the liquid refrigerant flows is taken out from the side surface of the electric wheel 200 on the vehicle body side, and is connected to a heat exchanger (not shown) arranged at the front portion of the vehicle body. The liquid refrigerant is cooled by an air-cooled or water-cooled heat exchanger.

FIG. 3 shows a schematic cross-sectional view of the in-wheel motor 50. FIG. 3 shows the arrangement relationship of the main structural parts of the in-wheel motor 50, for example, the stator core 2X, the rotor core 4X, the gap 7, the first bearing 11A, and the second bearing 11B. The periphery of the hub bearing HUB of the in-wheel motor 50 and the structure of the oil seal are not shown.

As shown in FIG. 3, the in-wheel motor 50 includes a stator 2 and a rotor 4. The stator 2 includes a cylindrical stator core 2X, a plurality of coils 2Z wound around the stator core 2X, and a main body 2C that supports the stator core 2X. The rotor 4 includes a rotor core 4X rotatably arranged with respect to the stator core 2X via a gap 7, and a rotor case 4W that supports the rotor core 4X.

A plurality of slots (not shown) parallel to the central axis direction of the stator core 2X are formed on the outer peripheral portion of the stator core 2X. The plurality of slots are formed at equal intervals in the circumferential direction of the stator core 2X. The coil 2Z is accommodated in the slot. Teeth 2T is formed between the slots (see FIGS. 6 and 7). In this embodiment, the plurality of teeth 2T are integrated with the annular core back 2Q (see FIG. 6). That is, the stator core 2X is a core in which a plurality of teeth 2T and a core back 2Q are integrally molded. A split core is used in the circumferential direction. The teeth 2T guides the rotating magnetic field generated by the coil 2Z to the rotor core 4X, and generates a rotational torque in the rotor core 4X.

Coil 2Z is formed by connecting a plurality of conductor pieces. The conductor piece is formed by punching a plate of a low resistance conductor such as copper. The coil 2Z may be formed by a flat wire having a rectangular cross section. The coil 2Z is accommodated in the slot of the stator core 2X in a layered manner in the radial direction. In the present embodiment, the radial direction refers to the radial direction of a cylindrical rotary electric machine. The axial direction refers to the rotating shaft on which the rotor 4 of the rotary electric machine rotates. The circumferential direction refers to the circumferential direction of the stator 2 or the rotor 4 having a cylindrical shape. In the following embodiments, the rotary electric machine refers to an in-wheel motor that can be incorporated in a wheel.

The coil 2Z has an in-slot conductor arranged in the slot of the stator core 2X, and a coil end portion protruding from both ends of the stator core 2X to the outside of the slot. The coil end portion arranged on one end side (outside the vehicle) of the stator core 2X is referred to as the first coil end portion 2ZA, and the coil end portion arranged on the other end side (vehicle body side) of the stator core 2X is referred to as the second coil end portion 2ZB. It is written as. The first coil end portion 2ZA and the second coil end portion 2ZB generate heat during the operation of the in-wheel motor 50 and become hot. As will be described later, the first coil end portion 2ZA and the second coil end portion 2ZB are arranged in the liquid refrigerant passage 15 in which the liquid refrigerant is housed, and are cooled by the liquid refrigerant.

The stator 2 includes a cylindrical main body 2C, a first end bracket 2A fixed to an opening on one end side of the main body 2C, and a second end bracket 2B fixed to an opening on the other end side of the main body 2C. To prepare for. The stator core 2X is shrink-fitted to the outer peripheral portion of the main body 2C, and is fitted and fixed by press fitting or the like.

The main body 2C is formed by a die casting method using a light metal such as aluminum or magnesium alloy, for example. The main body 2C may be formed by a layered manufacturing method such as a 3D printer molding method. By adopting the additive manufacturing method, the degree of freedom in the shape of the main body 2C is improved. The inside of the main body 2C is a space, and the inverter 150 is accommodated. As a result, a motor unit having an integrated mechanical and electrical structure is formed in which the in-wheel motor 50 and the inverter (power conversion device) are integrated. Hereinafter, the main body 2C, the first end bracket 2A, and the second end bracket 2B are also referred to as a stator case 2W.

A plurality of permanent magnets are fixed to the rotor core 4X. The permanent magnet forms the field pole of the rotor 4. The rotor 4 rotates about the wheel shaft by guiding the rotating magnetic field generated by the coil 2Z.

The rotor case 4W has a bottomed cylindrical case body 4C and an end bracket 4B fixed to the opening of the case body 4C. The case body 4C has a cylindrical portion 4CH and a disk-shaped bottom portion 4CD provided on one end side of the tubular portion. The rotor core 4X is shrink-fitted into the inner peripheral portion of the case body 4C, and is fitted and fixed by press fitting or the like. That is, the case body 4C rotates together with the rotor core 4X.

The case body 4C is formed of, for example, a light metal such as aluminum die-cast and a lightweight structural material such as carbon fiber reinforced plastic (CFRP). In order to form a narrow gap 7 between the rotor core 4X and the stator core 2X, it is preferable that the case body 4C is formed by an integral molding method having high processing accuracy such as a tub-shaped die casting method.

By integrally molding the fixed portion 4MA of the first bearing 11A to the fixed portion 4MB of the second bearing 11B, it is easier to secure the dimensional accuracy between the fixed portions of the bearing 11 as compared with the assembled product. This makes it possible to realize a narrow gap. It is preferable that the parts are manufactured by die-casting aluminum without bolting or gluing. Alternatively, it may be manufactured by carving from one material.

However, the bottom 4CD of the case body 4C can be formed in a split type in relation to the allowable dimensional accuracy and rigidity, and the ease of assembling the parts to be used.

The first bearing 11A and the second bearing 11B connecting the outer peripheral portion of the main body 2C and the case main body 4C are arranged between the outer peripheral portion of the main body 2C and the inner peripheral portion of the case main body 4C. Since the first bearing 11A and the second bearing 11B have different diameter sizes but the same configuration, the first bearing 11A and the second bearing 11B are collectively referred to as the bearing 11 below. Further, the rolling element 10A of the first bearing 11A and the rolling element 10B of the second bearing 11B are collectively referred to as a rolling element 10.

The first bearing 11A is arranged on one end side in the axial direction of the stator core 2X (right side in the drawing), and the second bearing 11B is arranged on the other end side in the axial direction of the stator core 2X (left side in the drawing).

As shown in FIG. 3, a fixed portion 2LA into which the inner ring of the first bearing 11A is gap-fitted is formed on one end side in the axial direction of the main body 2C, and a second axial end side of the outer peripheral portion of the main body 2C is formed. A fixed portion 2LB is formed in which the inner ring of the two bearings 11B is gap-fitted.

A fixing portion 4MA to which the outer ring of the first bearing 11A is press-fitted and fixed is formed on one end side in the axial direction of the case body 4C, and the outer ring of the second bearing 11B is press-fitted and fixed to the other end side in the axial direction of the case body 4C. The fixed portion 4MB to be formed is formed.

Therefore, the weight of the rotor 4 itself is not applied. This is because, as described above, the weight of the vehicle body is transmitted to the wheel axle AX via the hub bearing HUB and is finally supported by the suspension device 110.

Therefore, the rotor 4 may have rigidity that is not deformed by the rotational torque.

A first oil seal (not shown) is placed between the first end bracket 2A and the bottom 4CD, and a second oil seal (not shown) is placed between the second end bracket 2B and the end bracket 4B.

The in-wheel motor 50 according to this embodiment is assembled, for example, as follows. First, the first bearing 11A is press-fitted and fixed to the fixing portion 4MA of the case body 4C of the rotor case 4W. After that, the stator 2 is inserted into the case main body 4C, and the fixing portion 2LA on the outer peripheral portion of the main body 2C is fitted to the inner ring of the first bearing 11A.

Next, the second bearing 11B is fitted between the fixing portion 4MB of the case main body 4C and the fixing portion 2LB of the main body 2C. By fixing the end bracket 4B to the case body 4C, the stator 2 is assembled to the case body 4C.

-Liquid refrigerant path-
The liquid refrigerant passage 15 of this embodiment will be described. When the stator 2 and the outer rotor type rotor 4 are fitted together, a liquid refrigerant passage 15 is formed between the stator 2 and the rotor 4. The liquid refrigerant passage 15 has an outer internal passage 15A formed between the gap 7 between the stator core 2X and the rotor core 4X, the bottom portion 4CD of the case body 4C of the rotor case 4W, and the axial end portion of the main body 2C. Have. Further, the liquid refrigerant passage 15 includes an inner internal passage 15B formed between the end bracket 4B of the rotor case 4W and the stator case 2W, the bearing internal 11AS of the first bearing 11A, and the bearing internal 11BS of the second bearing 11B. And have. This is because the rotor case 4W is rotatably arranged with respect to the stator 2. Therefore, the rolling elements 10 of the first bearing 11A and the second bearing 11B and the coil end portion of the coil 2Z are arranged in the liquid refrigerant passage 15 in which the liquid refrigerant is housed. The liquid refrigerant passage 15 corresponds to the above-mentioned first flow path.

(1) Gap The gap 7 is a narrow space where the stator core 2X and the rotor core 4X face each other. The rotating magnetic field generated by the stator core 2X acts electromagnetically on the rotor core 4X through the gap 7, and generates torque in the rotor 4. In the present embodiment, liquid refrigerant, not air, is accommodated in the gap 7 of the in-wheel motor 50 to cool the periphery of the gap 7.

When the liquid refrigerant is accommodated in the gap 7, at least a part of the rotor core 4X rotating around the wheel shaft AX comes into direct contact with the liquid refrigerant. Further, since the liquid refrigerant is accommodated in the gap 7, a part of the rotor core 4X, the stator core 2X, and the coil 2Z comes into contact with the liquid refrigerant.

When the case body 4C rotates, at least a part of the liquid refrigerant in contact with the bottom 4CD and the end bracket 4B rotates in the circumferential direction inside the rotary electric machine. In the present embodiment, since the liquid refrigerant receives pressure from the outside, a flow of the liquid refrigerant in the axial direction of the in-wheel motor 50 is generated from the liquid refrigerant inlet 14A toward the liquid refrigerant outlet 14B. Then, a liquid refrigerant flow 15R having a gap 7 as a flow path is formed inside the in-wheel motor 50.

(2) Outer Inner Passage and Inner Inner Passage The outer inner passage 15A is arranged between the bottom 4CD on the outside (outside of the vehicle) of the case body 4C and the first end bracket 2A. A first oil seal is arranged between the bottom 4CD and the first end bracket 2A (not shown). The inner internal passage 15B is a space between the bottom 4CD of the rotor case 4W and the stator case 2W located inside the rotor case 4W (on the vehicle body side). A second oil seal is arranged between the bottom 4CD and the second end bracket 2B (not shown). The outer inner passage 15A and the inner inner passage 15B have a thin donut-shaped structure centered on the wheel shaft of the in-wheel motor 51. The liquid refrigerant is housed inside the outer inner passage 15A and the inner inner passage 15B.

(3) Inside the bearing As described above, the bearing 11 is arranged between the stator 2 and the case body 4C. The bearing inner 11AS and 11BS are spaces formed between the inner ring and the outer ring of the bearing (see FIG. 8). The rolling element 10 is arranged inside the bearing inner 11AS and 11BS. The bearing inner 11AS, the gap 7, and the outer inner passage 15A of the first bearing 11A communicate with each other. The bearing internal 11BS, the gap 7, and the inner internal passage 15B of the second bearing 11B communicate with each other. In this way, the outer inner passage 15A, the gap 7, and the inner inner passage 15B are all communicated with each other through the bearing inner 11AS and 11BS of the bearing 11.

Further, the rolling elements 10 of the bearing 11 and the outer rings 10A _OR and 10B _OR rotate with respect to the stator 2 fixed to the vehicle body frame 1010 as the case body 4C rotates (see FIG. 8). Since the bearing internal 11AS and 11BS of the bearing 11 communicate with the liquid refrigerant passage 15, the rolling elements 10 of the bearing internal 11AS and 11BS are in contact with the liquid refrigerant. Therefore, the rolling element 10 is directly cooled by the liquid refrigerant. Some liquid refrigerants rotate in the circumferential direction as the bearing 11 rotates. As described above, the bearing internal 11AS and 11BS are configured as a part of the liquid refrigerant passage 15. In this way, the liquid refrigerant is accommodated in the plurality of spaces, that is, the liquid refrigerant passage 15 including the gap 7, the outer inner passage 15A, the inner inner passage 15B, the bearing inner 11AS, and 11BS.

As described above, a steady circulating flow is formed between the liquid refrigerant inlet 14A, the gap 7, the liquid refrigerant outlet 14B, an external pump, and the like. However, the bearing interiors 11AS and 11BS of the bearing 11 and the rolling element 10 are in contact with the liquid refrigerant in the liquid refrigerant passage 15, and are not arranged in the flow path of the liquid refrigerant. Therefore, the flow of the liquid refrigerant in the axial direction is not so much generated in the internal space in the axial direction of the two bearings 11. As described above, since the first bearing 11A and the second bearing 11B are installed outside the liquid refrigerant passage 15, the amount of liquid refrigerant that passes axially through the bearing internal 11AS and 11BS is small. That is, the bearing interiors 11AS and 11BS are only filled with the liquid refrigerant. However, the liquid refrigerant at least lubricates and cools the rolling elements 10. At the same time, since the flow of the liquid refrigerant is small, the possibility of foreign matter being mixed is reduced, which is preferable. In the present embodiment, the space filled with the above liquid refrigerant is referred to as a liquid refrigerant passage 15.

(4) Liquid Refrigerant Inlet and Liquid Refrigerant Outlet In the present embodiment, a supply through hole for supplying the liquid refrigerant to the inside of the in-wheel motor 50 is provided at one place directly under the first coil end portion 2ZA. .. The outside of the supply through hole is the external intake 13A, and the inside is the liquid refrigerant inlet 14A. The liquid refrigerant inlet 14A is connected to the liquid refrigerant passage 15 near the first coil end portion 2ZA.

Further, a discharge through hole for discharging the liquid refrigerant supplied from the liquid refrigerant inlet 14A to the inside of the in-wheel motor 50 to the outside is provided at one place directly under the second coil end portion 2ZB. The outside of the discharge through hole is the external outlet 13B, and the inside is the liquid refrigerant outlet 14B.

In the present embodiment, the distance between the first bearing 11A and the first coil end portion 2ZA is longer than the distance between the liquid refrigerant inlet 14A and the first coil end portion 2ZA, and the distance between the second bearing 11B and the second coil end portion 2ZB is longer. The distance between them is set to be longer than the distance between the liquid refrigerant outlet 14B and the second coil end portion 2ZB. In the case of the configuration of the present embodiment, it is preferable because the possibility that unnecessary foreign matter is mixed from the outside into the bearing 11 in contact with the liquid refrigerant is reduced.

Further, in the present embodiment, the external intake 13A and the external outlet 13B are provided at positions shifted by about 180 degrees in the circumferential direction. The external intake 13A and the external outlet 13B may be arranged in reverse. Depending on the state of the flow of the liquid refrigerant near the coil 2Z, there may be a plurality of outlets of the liquid refrigerant in the circumferential direction. A modified example of the arrangement configuration can be considered, such as the positional relationship between the liquid refrigerant outlet 14B and the liquid refrigerant inlet 14A being substantially the same position (about 0 degrees) in the circumferential direction or substantially opposite positions (about 180 degrees).

-Injection of liquid refrigerant-
After assembling the in-wheel motor 50, the liquid refrigerant is accommodated in the gap 7 communicating inside the in-wheel motor 50, the bearing inner 11AS, 11BS (see FIG. 8), the outer inner passage 15A, the inner inner passage 15B, and the like.

Inside the outer inner passage 15A, a first oil seal (not shown) for separating the inner and outer spaces and sealing the liquid refrigerant is provided between the bottom 4CD on the rotor side and the first end bracket 2A on the stator side. It is placed in between. Further, inside the inner inner passage 15B, a second oil seal (not shown) for separating the inner and outer spaces and sealing the liquid refrigerant is provided in the end bracket 4B on the rotor side and the second end bracket on the stator side. It is placed between 2B.

In order to accommodate the liquid refrigerant in the liquid refrigerant passage 15, a pipe may be connected to the external intake 13A, the external outlet 13B may be opened, and the liquid refrigerant may be supplied until the inside is filled. After that, a pipe or a hose is connected to the external outlet 13B to form a circulation path with a heat exchanger or the like. Pressure is applied to the liquid refrigerant by the pump and supplied to the liquid refrigerant passage 15. As a result, the liquid refrigerant flows through the liquid refrigerant passage 15, further exits from the liquid refrigerant outlet 14B and the external outlet 13B, and circulates with the external heat exchanger. The liquid refrigerant supplied from the liquid refrigerant inlet 14A to the inside of the in-wheel motor 50 becomes a liquid refrigerant flow 15R from the first coil end portion 2ZA toward the second coil end portion 2ZB and flows inside the gap 7. The space of the gap 7 through which the liquid refrigerant flows in the axial direction is the liquid refrigerant passage 15.

In the present embodiment, the external inlet 13A and the external outlet 13B are provided near the first coil end portion 2ZA and the second coil end portion 2ZB, respectively, with respect to the liquid refrigerant passage 15. That is, the external inlet 13A and the external outlet 13B are provided in the space on the inner peripheral side of the main body 2C. The external heat exchanger (not shown) and the external connection port 13 are connected by a pipe or a hose.

-Circulation of liquid refrigerant-
In the present embodiment, the liquid refrigerant passage 15 is formed so that each rolling element (ball) 10 of the two bearings 11 arranged between the stator 2 and the rotor case 4W is in contact with the liquid refrigerant. The rolling element 10 of the bearing 11 moves in the circumferential direction while rotating at the bearing inner portions 11AS and 11BS along the rotation direction of the case body 4C. Therefore, the liquid refrigerant in the vicinity of the rolling element 10 in the bearing inner portions 11AS and 11BS moves in the circumferential direction in the same manner as the rolling element 10. The liquid refrigerant in the bearing inner 11AS and 11BS absorbs frictional heat and the like generated by the rolling element 10 itself.

In the present embodiment, the liquid refrigerant contained in the outer inner passage 15A and the inner inner passage 15B hardly moves significantly in the axial direction inside the in-wheel motor 50. However, with the rotational operation of the in-wheel motor 50, the liquid refrigerant is drawn to the end bracket 4B or the bottom 4CD in contact with the liquid refrigerant. As a result, the liquid refrigerant contained in the outer inner passage 15A and the inner inner passage 15B rotates to some extent in the circumferential direction. In that case, heat is dissipated from the liquid refrigerant to the outside via the bottom 4CD and the end bracket 4B. As described above, the liquid refrigerant passage 15 has a function of efficiently cooling the in-wheel motor 50 having a high output.

Further, in the present embodiment, the liquid refrigerant flows in a fixed direction from the first coil end portion 2ZA to the second coil end portion 2ZB through the thin cylindrical gap 7. The liquid refrigerant cools the stator core 2X, the rotor core 4X, and the like. The in-wheel motor 50 of the present embodiment outputs a high torque by passing a large current through the coil 2Z. Therefore, since the coil 2Z generates heat due to the Joule loss, the temperatures of the coil 2Z and the stator core 2X tend to rise as compared with the rotor core 4X. In the present embodiment, the liquid refrigerant is continuously flowed in the gap 7 between the stator core 2X and the rotor core 4X. The liquid refrigerant is taken in from the external intake 13A and supplied to the inside of the liquid refrigerant passage 15 from the liquid refrigerant inlet 14A. Since the liquid refrigerant is sent by a pump placed outside, the liquid refrigerant has a relatively higher pressure at the position of the liquid refrigerant inlet 14A than the liquid refrigerant outlet 14B side.

Therefore, the liquid refrigerant continuously flows in the cylindrical gap 7 in the axial direction. By adopting such a configuration, the liquid refrigerant can continuously absorb the heat generated in the vicinity of the stator core 2X and the coil 2Z and exhaust the heat to the outside. In the present embodiment, the liquid refrigerant flows through the cylindrical gap 7 from the first coil end portion 2ZA to the second coil end portion 2ZB. Due to this flow of the liquid refrigerant, the liquid refrigerant absorbs the heat generated by the stator core 2X and the like, the temperature of the liquid refrigerant rises, and the temperature of the liquid refrigerant near the second bearing 11B rises, whereby the temperature of the second bearing 11B rises. It becomes higher than the temperature of the first bearing 11A.

When the diameter of the second bearing 11B is the same as the diameter of the first bearing 11A as in the prior art, the internal gap of the second bearing 11B becomes relatively smaller than the internal gap of the first bearing 11A due to thermal expansion. ..

Then, the life of the second bearing 11B may be shorter than the life of the first bearing 11A due to the narrowing of the internal gap of the second bearing 11B due to thermal expansion. In the present embodiment, the diameter of the second bearing 11B is set to be larger than the diameter of the first bearing 11A. As a result, the life of the second bearing 11B is improved. As described above, in the present embodiment, the gap 7 is a first flow path through which the liquid refrigerant flows in the axial direction, and the first bearing 11A is arranged on the liquid refrigerant inlet 14A side of the first flow path and is the second bearing. 11B is arranged on the liquid refrigerant outlet 14B side of the first flow path, and the inner diameter of the second bearing 11B is set to be larger than the inner diameter of the first bearing 11A.

-bearing-
In the present embodiment, it is preferable to use radial type bearings for the first bearing 11A and the second bearing 11B arranged between the case main body 4C and the main body 2C. Further, it is preferable to use large diameter and thin bearings for the first bearing 11A and the second bearing 11B. Thin bearings have the advantages of smaller bearing width and lighter weight than general bearings. Generally, the larger the diameter of a bearing, the larger the cross section of the rolling element 10.

However, the thin bearing is designed to have a larger bearing diameter while maintaining a small cross-sectional area of the rolling element. Therefore, since the cross section of the rolling element of the thin bearing is smaller than the diameter of the rolling element, the allowable load and the allowable peripheral speed are also smaller than those of a general bearing. However, the thin bearing has an advantage that the entire bearing is small and lightweight. The thin bearing applicable to this embodiment has an inner diameter of about 20 cm or more and a rolling element having a diameter of about several mm.

In this embodiment, the weight of the vehicle body is separately supported by the hub bearing HUB (see FIG. 2). That is, the vehicle weight is not directly applied to the first bearing 11A and the second bearing 11B used in the present embodiment. These two bearings 11 support the weight of the case body 4C of the rotor case 4W to which the bearings 11 are connected. It is preferable to select a deep groove ball bearing as the bearing of the present embodiment on the premise that the axial load is not applied to the first bearing 11A and the second bearing 11B. The deep groove ball bearing cannot receive the thrust load, but has a small coefficient of friction and a low rotational torque, so that a low-loss in-wheel motor can be configured. The structure and characteristics of the bearing 11 will be described later.

Further, if the bearing 11 is not subjected to a radial load or a thrust load, or even if a radial load or a thrust load is applied, if the load is within a small range, a bearing 11 having a small cross-sectional area of the rolling element 10 is selected. Can be used. In the in-wheel motor 50 of the present embodiment, miniaturization and weight reduction are important technical elements, so it is important to select a bearing 11 having the smallest possible cross-sectional area of the rolling element 10.

Here, the definition regarding the gap between bearings will be explained. The internal gap of a radial bearing refers to the amount of movement when one of the inner ring and the outer ring is fixed and the other is moved. The amount of movement when the inner ring or outer ring is moved in the radial direction is called the radial internal gap. The effective gap of the bearing is the amount of reduction of the gap due to the fitting of the bearing and the amount of reduction of the gap due to the temperature difference between the inner ring and the outer ring from the gap (true gap) before mounting the bearing. It is a thing. The operating gap is the effective gap plus the amount of increase in the gap due to the load applied to the bearing.

The first bearing 11A of the present embodiment is arranged at a position closer to the liquid refrigerant inlet 14A than the second bearing 11B. The approximate size of the rolling element 10A of the first bearing 11A is a cross section of 1.27 cm (1/2 inch) square and an inner diameter of 35.6 cm (14 inches). Then, the bearing internal 11AS and 11BS including the rolling element 10 of the bearing 11 are cooled by the liquid refrigerant (see FIG. 8). The rolling elements 10 of the two bearings 11 are arranged so as to be in contact with the liquid refrigerant in the liquid refrigerant passage 15. A forced liquid refrigerant lubrication method for passing the liquid refrigerant in the axial direction of the bearing 11 will be described later.

In the present embodiment, the first bearing 11A and the second bearing 11B are provided with a cooling oil seal portion separately, but a seal type bearing may be used. Further, in order to narrow the gap 7 between the stator 2 and the rotor 4, it is preferable that the first bearing 11A and the second bearing 11B are arranged at positions as close as possible to the stator core 2X and the rotor core 4X. If a seal type bearing is adopted, it is not necessary to separately install a seal in addition to the bearing, so that the number of parts can be reduced.

However, the seal type bearing has a longer shaft length, and its withstand pressure is lower than that of the seal-separated type bearing. Further, since heat generation due to the rotation of the rolling element 10 of the bearing 11 and heat generation due to friction of the seal portion are generated at the same location, it is preferable to combine the bearing with a separate seal and the seal when comparing the whole. Grease lubrication is also used as a cooling method for the bearing 11, but in the present embodiment, grease lubrication is not positively used.

As the material of the bearing used in this embodiment, it is preferable to use the bearing steel SUJ2. SUS may be used instead of SUJ2. A metal such as SUS is used for the rolling element 10. Since the coefficient of thermal expansion of a ceramic rolling element is smaller than that of a metal, it is not easily affected by a temperature rise, but it is not unapplicable.

Since the first bearing 11A is arranged near the wheel of the outer rotor type in-wheel motor, the diameter of the first bearing 11A is close to the rim diameter of the wheel. The true clearance inside the radial before assembling the bearing 11 can be selected from the range of about 80 to 130 μm. However, depending on the material of the main body 2C and the temperature setting of the liquid refrigerant, it is possible to select another series of bearings having different inner diameter sizes.

When the in-wheel motor 50 is continuously used, the rolling element 10 undergoes thermal expansion due to the temperature rise of the liquid refrigerant in contact with the rolling element 10 and the heat generated by the rolling element 10 itself, and the internal gap becomes smaller. The second bearing 11B used in the present embodiment has a large diameter and a large bearing gap (true gap before mounting) is set in advance. Therefore, it is easy to absorb the thermal expansion of the rolling element 10B of the second bearing 11B based on the local heat generation generated in the second bearing 11B.

The setting of the operating gap will be described with reference to FIG. Generally, as in the fatigue life-operating gap curve shown in FIG. 9, the condition at which the fatigue life curve peaks is when the operating gap is negative. That is, it is often used by setting the operating gap slightly narrower than 0. The curves (a) and (b) in FIG. 9 are for the case where the load conditions for the same bearing are different by about 6 times, but the life shows the maximum value when the operating gap is about -3 to -8 μm. ..

However, if the operating clearance is set to the maximum value of the fatigue life curve in the region of 0 or less with the aim of extending the life of the bearing, the fatigue life curve will be maximized due to the dimensional variation of parts and assembly accuracy. The actual operating gap may shift to the minus side from the value. Then, the life of the bearing deteriorates sharply. In the present embodiment, the second bearing 11B is set in advance so that the operating gap is 0 or more, as shown in the range of the arrow in (c).

Next, the bearing tolerance will be described with reference to FIG. As shown in FIG. 10, the larger the outer and inner diameters of the bearing, the larger the tolerance width. In the present embodiment, the setting of the operating clearance of the bearing is not a plus or minus tolerance, but the lower limit of the setting of the operating clearance is set to 0. Set the operating clearance in consideration of the tolerance of the bearing to be used. As a result, the target value for setting the operating clearance of the bearing is larger than the general value.

Further, in the present embodiment, the bearing inner portions 11AS and 11BS including the rolling elements 10 of the two bearings 11 are arranged in the liquid refrigerant passage 15 and are in contact with the liquid refrigerant. The liquid refrigerant absorbs heat generated in the vicinity of the stator core 2X where the temperature rises remarkably inside the in-wheel motor 50, passes through the liquid refrigerant outlet 14B, and exits from the external outlet 13B. At that time, the liquid refrigerant that absorbs the heat generated in the vicinity of the stator core 2X becomes relatively hot as it passes through the gap 7 and progresses toward the outlet side rather than the inlet side.

The second bearing 11B in contact with the liquid refrigerant having a relatively higher temperature than the liquid refrigerant inlet 14A side is exposed to the temperature of the liquid refrigerant in contact with the second bearing 11B in addition to the heat generated by the rotational operation of the second bearing 11B itself. Will be. That is, in the present embodiment, the temperature of the second bearing 11B tends to be higher than that of the first bearing 11A during operation.

As shown in FIG. 8, since the second bearing 11B is gap-fitted to the main body 2C, the inner ring 10B _IR of the second bearing 11B is in direct contact with the main body 2C. That is, the inner ring 10B _IR of the second bearing 11B is directly affected by the heat conduction from the main body 2C. As a result, the inner diameter of the second bearing 11B becomes larger than the inner diameter of the first bearing 11A when the in-wheel motor 50 is operated due to the temperature rise.

In the present embodiment, in order to block the influence of heat conduction from the main body 2C of the stator 2, several to 30 holes 2H are concentrically provided in the circumferential direction of the second end bracket 2B from the stator core 2X. It makes it difficult to receive heat conduction. The hole 2H is located between the stator core 2X and the second bearing 11B in the radial direction. The hole 2H is provided as a hole penetrating in the axial direction on the side surface of the second end bracket 2B within a range that does not affect the strength and rigidity of the component.

Since the heat conduction area of the main body 2C is reduced by the hole 2H, the heat of the coil 2Z is less likely to be transferred to the second bearing 11B. Further, by providing a plurality of holes 2H, the inner internal passage 15B and the gap 7 side are communicated with each other, and convection of the liquid refrigerant occurs inside. Since the liquid refrigerant is more in contact with the second bearing 11B due to this convection, the second bearing 11B is easily cooled. In this way, the inside of the hole 2H becomes a part of the liquid refrigerant passage 15. The shape of the hole 2H may be a round hole or a long hole. Further, if a hole is provided at a position where the gap 7 can be seen, it can be used as a hole for inserting a protective plate into the gap 7 when assembling the stator / rotor.

In the present embodiment, the temperature rise of the second bearing 11B is predicted in the operating state, and the bearing gap of the second bearing 11B is set large in advance. The second bearing 11B is a product of the same series as the first bearing 11A (the cross-sectional area of the rolling element is the same size) and has a diameter at least one size larger. For example, a component having an inner diameter of 40.6 cm (16 inches) is used as the second bearing 11B with respect to the first bearing 11A having an inner diameter of 35.6 cm (14 inches).

Since the internal clearance of the radial bearing before assembly of the second bearing 11B is set to about 90 to 140 μm, a bearing having a dimension corresponding to the numerical value of this internal clearance is selected from the product numbers of commercially available products and used. The bearing used in this embodiment is not a custom-made product, but is preferably selected from parts produced as a general standard product and supplied to the market. That is, it is preferable that the internal clearance of the radial bearing is selected from the numerical range recommended as the catalog value.

Then, it is preferable to select parts having different diameters in the same series of bearings of general commercial products in combination as the first bearing 11A and the second bearing 11B. Table 1 shows examples of bearing dimensional values that are generally available on the market.

As described above, the in-wheel motor (rotary electric machine) 50 of the present embodiment has the rolling elements 10 of the first bearing 11A and the second bearing 11B and the coil end portions of the coil 2Z, that is, the first coil end portions 2ZA and the second. The coil end portion 2ZB is arranged in the liquid refrigerant passage in which the liquid refrigerant is housed. The gap 7 is a first flow path through which the liquid refrigerant flows in the axial direction, the first bearing 11A is arranged on the liquid refrigerant inlet 14A side of the first flow path, and the second bearing 11B is the liquid in the first flow path. It is arranged on the refrigerant outlet 14B side, and has a configuration in which the inner diameter of the second bearing 11B is larger than the inner diameter of the first bearing 11A.

Even with the minimum configuration, the components such as the bearing 11, rolling element 10, and stator core 2X can be efficiently cooled. It is unlikely that foreign matter will enter the bearing 11, and this will extend the life of the bearing 11.

[Second Embodiment]
FIG. 4 shows a partial cross-sectional perspective view of the present embodiment.

-Circular flow path-
FIGS. 4 to 7 show the structure of this embodiment. First, as shown in FIG. 4, in addition to the liquid refrigerant flow 15R, an annular flow path 18 surrounded by a cylindrical space between the inner peripheral side surface of the stator core 2X and the outer peripheral side surface of the main body 2C is provided. .. The liquid refrigerant flow 15R is arranged in the gap 7 on the outer peripheral side of the stator core 2X, and the annular flow path 18 is arranged below the stator core 2X.

As shown in FIG. 5, the annular flow path 18 is composed of circumferential passages 17a, 17b, 17c arranged in three stages in the axial direction, and oblique traffic passages 17ab, 17bc connecting each circumferential passage in series. Will be done. The annular flow path 18 is formed by dividing the flow path by a plurality of walls having heights in the radial direction on the surface of the main body 2C. The upstream end of the first-stage circumferential passage 17a of the annular passage 18 is connected to the annular passage inlet 16A, and the downstream end is connected to the oblique traffic passage 17ab. The oblique traffic passage 17ab is continuously connected to the middle-stage circumferential passage 17b, the second-stage oblique traffic passage 17bc, the third-stage circumferential passage 17c, and the annular flow path exit 16B.

The annular flow path 18 in the present embodiment includes one or more oblique traffic paths 17ab and 17bc on the way from the annular flow path inlet 16A to the annular flow path outlet 16B. When the liquid refrigerant passes through the circumferential passages 17a, 17b, 17c and the oblique traffic passages 17ab, 17bc, the passage cross-sectional area in the traveling direction of each passage is set to be substantially the same in order to reduce the passage loss. Further, in order to reduce the passage resistance of the liquid refrigerant, it is preferable that the intersection angle between the oblique traffic path and the circumferential passage is not so large.

Since the liquid refrigerant travels through the annular flow path 18 having such a structure, the liquid refrigerant flows a plurality of times in the circumferential direction while being in contact with the inner surface of the stator core 2X. Therefore, when the liquid refrigerant passes through the annular flow path 18, the contact time with the stator core 2X becomes longer, and it becomes easier to absorb heat in the vicinity of the stator core 2X. When the heat absorption efficiency by the liquid refrigerant passing through the annular flow path 18 is increased, the difference between the temperature of the liquid refrigerant near the liquid refrigerant inlet 14A and the temperature of the liquid refrigerant near the liquid refrigerant outlet 14B becomes larger. The annular flow path 18 corresponds to a second flow path that can coexist with the liquid refrigerant flow 15R, which is the first flow path passing through the gap 7.

The passage path of the liquid refrigerant in this embodiment is as follows. The pipe connected to the heat exchanger (not shown) is attached to the external intake 13A located on the inner peripheral side of the main body 2C. The liquid refrigerant is supplied to the inside of the in-wheel motor 50 from the external intake 13A. The liquid refrigerant enters the space immediately below the first coil end portion 2ZA of the liquid refrigerant passage 15 from the liquid refrigerant inlet 14A. At that time, since the liquid refrigerant is sent by the pump, the liquid refrigerant at the time of being supplied to the liquid refrigerant inlet 14A has a higher pressure than the other parts of the liquid refrigerant passage 15.

After that, in the present embodiment, the liquid refrigerant supplied to the inside of the in-wheel motor 51 is roughly divided into two flow paths. First, the first flow path is the liquid refrigerant flow 15R as in the case of the first embodiment. The liquid refrigerant enters the first coil end space 9A from the liquid refrigerant inlet 14A near the first coil end portion 2ZA. Since the outermost peripheral side of the first coil end space 9A is directly connected to the gap 7, the liquid refrigerant flows in the circumferential direction in the first coil end space 9A and is second so as to cross the gap 7 which is a cylindrical space. It flows toward the coil end portion 2ZB.

Next, FIGS. 6 and 7 schematically show the structure near the first coil end space 9A and the flow of the liquid refrigerant. The liquid refrigerant enters the first coil end space 9A from the vicinity of the first coil end portion 2ZA, and is further divided into two directions on the left and right with respect to the circumferential direction. One of them is the first rotating flow 9F1 flowing in the first direction in the first coil end space 9A. The other is the second rotating flow 9F2 flowing in the opposite direction through the first coil end space 9A. It shows how the first rotary flow 9F1 and the second rotary flow 9F2, which are separated near the liquid refrigerant inlet 14A, each half-circle the first coil end space 9A and merge at a position 180 degrees facing the liquid refrigerant inlet 14A. ing.

A ring road entrance 16A is provided near the confluence. The annular flow path inlet 16A is a portion of the stator core 2X processed into a concave shape. The first coil end space 9A communicates with the annular flow path 18 on the back surface side of the stator core 2X. Therefore, the liquid refrigerant can enter the annular flow path 18 from the annular flow path inlet 16A.

The first rotating flow 9F1 and the second rotating flow 9F2 make a half turn in the circumferential direction and then merge to form a downward flow 9F3. The downward flow 9F3 is the inlet bottom of the annular flow path inlet 16A, and the flow direction is changed from the downward direction to the axial direction to become the introduction flow 9F4 toward the annular flow path 18.

When the liquid refrigerant that has become the introduction flow 9F4 enters the annular flow path 18, it enters the first-stage circumferential passage 17a. FIG. 5 shows the configuration of the liquid refrigerant passage in the annular flow path 18. The liquid refrigerant enters the first-stage circumferential passage 17a, and after about one round, enters the oblique traffic passage 17ab. Further, the liquid refrigerant passes through the circumferential passage 17b, the oblique traffic passage 17bc, and the circumferential passage 17c in this order, and reaches the annular passage outlet 16B.

The liquid refrigerant is a lead flow 9F5 from the circumferential flow to the axial direction near the annular flow path outlet 16B. The lead flow 9F5 becomes an upward flow 9F6 inside the annular flow path outlet 16B. Finally, the liquid refrigerant enters the second coil end space 9B near the second coil end portion 2ZB. The liquid refrigerant is again split in two directions in the second coil end space 9B. It is the same as the first diversion in the case of the first coil end space 9A described above, and is divided into the third rotary flow 9F7 and the fourth rotary flow 9F8 flowing through the second coil end space 9B.

These 3rd rotation flow 9F7 and 4th rotation flow 9F8 flow about half a circumference in opposite directions in the circumferential direction of the 2nd coil end space 9B, and then rejoin at positions facing each other by 180 degrees. The liquid refrigerant passes through the liquid refrigerant outlet 14B placed near the confluence, exits from the external outlet 13B to the outside of the in-wheel motor 51, and returns to the liquid refrigerant tank.

In the present embodiment, a small part of the liquid refrigerant may pass so as to cross the rolling element 10 of the bearing 11 in the axial direction. Further, a part of the liquid refrigerant that has crossed the bearing inner portions 11AS and 11BS (see FIG. 8) of the bearing 11 may reach the outer internal passage 15A which is a gap space between the first end bracket 2A and the case body 4C. .. Alternatively, the liquid refrigerant may reach the inner internal passage 15B, which is a gap space between the stator case 2W and the end bracket 4B. As described above, in the in-wheel motor 51 of the present embodiment, the liquid refrigerant is housed in the gap space between the stator case 2W and the rotor case 4W.

In the present embodiment, all of the coil 2Z wound around the stator core 2X, the first coil end portion 2ZA, and the second coil end portion 2ZB are covered with the liquid refrigerant. In the present embodiment, in addition to the liquid refrigerant flow 15R, a first coil end flow through which the liquid refrigerant passes through the first coil end space 9A and a second coil end flow through which the liquid refrigerant passes through the second coil end space 9B are provided. Further, on the back surface of the stator core 2X, an annular flow path 18 through which the liquid refrigerant flows in the circumferential direction and also travels in the axial direction is provided. Therefore, the cooling efficiency of the in-wheel motor 51 is further improved.

-Internal pressure loss-
In the present embodiment, there are two types, a liquid refrigerant flow 15R in which the liquid refrigerant flows in the axial direction and an annular flow path 18. The gap 7 of the in-wheel motor 51 is a narrow space between the stator core 2X and the rotor core 4X. The liquid refrigerant passes through this narrow space. Therefore, if the pressure loss is relatively small with respect to the annular flow path 18, the liquid refrigerant does not flow into the annular flow path 18 but flows toward the gap 7. When a large amount of liquid refrigerant flows through the gap 7, the cooling efficiency of the in-wheel motor as a whole drops. Narrowing the gap 7 also leads to an improvement in torque as an in-wheel motor. Therefore, when the gap 7 is narrowed, the pressure loss in the liquid refrigerant path is sufficiently small, and the required torque can be generated. For example, 0.5 mm is an example of the design value of the gap 7.

Here, the configurations of the first bearing 11A and the second bearing 11B in the present embodiment will be described. FIG. 8 shows a partially enlarged view of the bearing 11 of the in-wheel motor 51.

The first bearing 11A has an outer ring 10A _OR and an inner ring 10A _IR . The space between the outer ring 10A _OR and the inner ring 10A _IR is the bearing inner 11AS. The gap between the outer ring 10A _OR and the rolling element 10A is 10A _GPH . The gap between the inner ring 10A _IR and the rolling element 10A is 10A _GPL .

The outer diameter of the outer ring 10A _OR is D _1-1 , and the inner diameter is L _1-2 . The inner diameter of the inner ring 10A _IR is L _1-1 and the inner diameter is d ₁ . The width of the outer ring 10A _OR is W ₁ .

The second bearing 11B has an outer ring 10B _OR and an inner ring 10B _IR . The space between the outer ring 10B _OR and the inner ring 10B _IR is the bearing inner 11BS. The gap between the outer ring 10B _OR and the rolling element 10B is 10B _GPH . The gap between the inner ring 10B _IR and the rolling element 10B is 10B _GPL .

The outer diameter of the outer ring 10B _OR is D _2-1 and the inner diameter is L _2-2 . The inner diameter of the inner ring 10B _IR is L _2-1 and the inner diameter is d ₂ . The width of the outer ring 10B _OR is W _2. The dimensions of each of the above parts are standardized by the bearing manufacturer, and it is often possible to select a product number of a desired size. Inch and metric parts may be available.

The second bearing 11B is selected from thin flat bearings having a diameter one size larger than that of the first bearing 11A. Similar to the first embodiment described above, in this embodiment as well, the life of the second bearing 11B is extended by using a bearing having a larger diameter than the first bearing 11A for the second bearing 11B. Therefore, in the setting of the second bearing 11B, the condition is set so that the operating gap thereof is 0 or more.

[Third Embodiment]
FIG. 11 shows a partial cross-sectional perspective view of the third embodiment. The first bearing 11A and the second bearing 11B are thin and flat bearings of the same system. The second bearing 11B used has a diameter at least one size larger than that of the first bearing 11A.

In the present embodiment, the external inlet 13A for supplying the liquid refrigerant to the liquid refrigerant passage 15 and the external outlet 13B for discharging the liquid refrigerant are the first ends of the stator 2 on the inner peripheral side of the in-wheel motor 52. It is attached to the bracket 2A and the second end bracket 2B, respectively. The liquid refrigerant inlet 14A is connected to the outer internal passage 15A. The liquid refrigerant outlet 14B is connected to the inner internal passage 15B.

Therefore, the first bearing 11A is arranged in the liquid refrigerant passage 15 between the liquid refrigerant inlet 14A and the first coil end portion 2ZA. Further, the second bearing 11B is arranged in the liquid refrigerant passage 15 between the liquid refrigerant outlet 14B and the second coil end portion 2ZB.

In the present embodiment, the liquid refrigerant supplied from the outside enters the outer internal passage 15A from the liquid refrigerant inlet 14A, further passes through the bearing inner 11AS of the first bearing 11A, and enters the first coil end space 9A. Also in this embodiment, the annular flow path inlet 16A is provided in the first coil end space 9A. Further, the annular flow path outlet 16B is provided in the second coil end space 9B. The configuration of the annular flow path 18 is the same as that of the second embodiment. In the present embodiment, the liquid refrigerant is taken into the outer inner passage 15A, and the first bearing 11A, the gap 7 or the annular flow path 18, the second coil end space 9B, the inner inner passage 15B, the liquid refrigerant outlet 14B, and the outer outlet 13B. And returns to the external liquid refrigerant tank.

Therefore, since the liquid refrigerant constantly flows through the bearing internal 11AS and BS of the bearing 11, the rolling element 10 and the bearing internal 11AS and 11BS are effectively cooled by the liquid refrigerant.

[Fourth Embodiment]
The present embodiment will be described with reference to FIG. The liquid refrigerant in the present embodiment is supplied to the liquid refrigerant passage 15 from the liquid refrigerant inlet 14A on the first bearing 11A side. The pressure of the liquid refrigerant is increased by the pump when it enters the liquid refrigerant passage 15. Further, as the liquid refrigerant advances in the axial direction in the liquid refrigerant flow 15R and the annular flow path 18 inside the in-wheel motor 53, the pressure gradually decreases due to the internal loss. That is, pressure loss occurs in the liquid refrigerant passage 15. When the liquid refrigerant is discharged to the outside from the external outlet 13B, the pressure is the lowest. Comparing the internal pressures on the inlet side and the outlet side, the inlet side is relatively higher. The liquid refrigerant contained in the outer internal passage 15A, which is a part of the liquid refrigerant passage 15, exerts pressure on the bottom 4CD of the rotor case 4W. Further, the liquid refrigerant contained in the inner internal passage 15B exerts pressure on the end bracket 4B. Comparing the magnitudes of both pressures, the inlet side pressure 19A is higher than the outlet side pressure 19B by the amount of the internal pressure loss. FIG. 13 schematically shows how the inside is affected by this pressure difference. Further, Table 2 below will explain a comparative example of internal pressure loss in comparison with the present embodiment.

As shown in FIG. 13, inside the in-wheel motor, a thrust force F1 due to an internal pressure difference in the liquid refrigerant passage 15 acts in the axial direction of the _two bearings 11. The pressure on the first bearing 11A side becomes high, and the pressure on the second bearing 11B side becomes low. In order to cancel this pressure difference, as shown in FIG. 14, the projected area of the support structure that supports the two bearings 11 is set larger on the outlet side than on the inlet side. Therefore, for the second bearing 11B on the liquid refrigerant outlet 14B side, a bearing having a larger diameter than the first bearing 11A on the inlet side is used.

As a result, the inner ring diameter of either the first bearing 11A or the second bearing 11B is larger than the diameter of the stator 2, and the inner ring diameter of the other is smaller than the diameter of the stator 2. When the gap 7 is narrow and the pressure loss of the flow path from the first coil end portion 2ZA to the second coil end portion 2ZB is large, the refrigerant pressure on the first bearing 11A side is higher than the refrigerant pressure on the second bearing 11B side. Will also grow. When the first bearing 11A and the second bearing 11B have the same diameter, the pressure receiving areas are the same, and as shown in FIG. 13, a pressure difference occurs in the left-right direction of the schematic diagram. Therefore, a thrust force in the axial direction works.

That is, as shown in FIG. 13, when the diameter sizes of the first bearing 11A and the second bearing 11B are the same, the force applied to the bottom 4CD of the rotor case 4W and the end bracket 4B has a relatively high pressure on the inlet side. Therefore, a force acts on the right side of the paper in FIG. Then, since the inner ring of the first bearing 11A is pulled to the right side, the shaft of the bearing is tilted. Similarly, the shaft of the second bearing 11B is also tilted.

Therefore, as shown in FIG. 14, if the diameter of the bearing is increased and the pressure receiving area on the _second bearing 11B side is increased, the thrust force F2 can be offset.

By introducing the liquid refrigerant passage 15, the pressure loss generated inside causes the pressure on the first bearing 11A side to be high and the pressure on the second bearing 11B side to be low, and a thrust force acts on the rotor 4. The contact angle of the bearing 11 is tilted by the force. As a result, abnormal wear occurs in the bearing internal 11AS, 11BS and the rolling element 10, and the life of the bearing is shortened. The generation of this unbalanced internal pressure can be compensated by making the diameter of the bearing 11 different.

In the present embodiment, the pressure of the liquid refrigerant applied to the first bearing 11A is higher than the pressure of the liquid refrigerant applied to the second bearing 11B. In order to compensate for this, the diameter of the second bearing 11B is set to be larger than the diameter of the first bearing 11A. In that case, the relatively small pressure on the second bearing 11B can be compensated for by changing the diameter of the bearing to compensate for the difference in internal pressure between the first bearing 11A and the second bearing 11B due to the large diameter size. can.

FIG. 14 schematically shows the state. The area on the exit side is set relatively larger than the area on the bracket on the entrance side. Therefore, it is considered that the difference in internal pressure between the liquid refrigerant at the inlet and the outlet is comprehensively compensated, and the total internal pressure on the inlet side and the outlet side is balanced. Therefore, the shaft of the bearing 11 is less likely to be tilted.

[Fifth Embodiment]
FIG. 15 shows the structure of the in-wheel motor 54 of the fifth embodiment. In the present embodiment, any one of the bearings 11 is arranged at the same position as the first coil end portion 2ZA and the second coil end portion 2ZB in the vicinity in the axial direction, or the first coil end portion 2ZA and the second coil end portion 2ZA. It is arranged inside the coil end portion 2ZB in the axial direction. In FIG. 15, the component end position 11X of the second bearing 11B is arranged inside the axial position of the second coil end portion 2ZB.

In this way, by arranging the first coil end portion 2ZA, the second coil end portion 2ZB, and the bearing 11 at positions where they are overlapped in the radial direction, it is possible to realize an in-wheel motor 54 having a short axis length configuration as a whole. can. By overlapping the coil end portion and the bearing in the radial direction, the axial length of the in-wheel motor 54 can be shortened.

Although some embodiments and modifications of the present invention have been described above, the present invention is not limited to these examples, and further modifications can be considered. For example, the number of laps of the above-mentioned annular flow path can be deformed, and the positions of the liquid refrigerant inlet and the liquid refrigerant outlet can be freely combined in relation to improvement of cooling efficiency, component size, reduction of internal volume, and the like. Can be configured. Various embodiments can be considered other than using the above-described embodiment and the illustrated parts.

2 ... stator, 2X ... stator core, 2Z ... coil, 2ZA ... 1st coil end, 2ZB ... 2nd coil end, 2W ... stator case, 2A ... 1st end bracket, 2B ... 2nd end bracket, 4 ... rotor , 4X ... rotor core, end bracket 4B, 4C ... case body, 4CD ... bottom, 4CH ... cylindrical part, 4W ... rotor case, 7 ... gap, 9A ... 1st coil end space, 9B ... 2nd coil end space, 10 ... Rolling element, 11A ... 1st bearing, 11B ... 2nd bearing, 13A ... External inlet, 13B ... External outlet, 14A ... Liquid refrigerant inlet, 14B ... Liquid refrigerant outlet, 15 ... Liquid refrigerant passage, 15 ... Liquid refrigerant passage , 15A ... outer inner passage, 15B ... inner inner passage, 15R ... liquid refrigerant flow, 16A ... annular flow path inlet, 16B ... annular flow path outlet, 18 ... annular flow path, 50 ... in-wheel motor (rotary electric machine), 100 ... wheels, 200 ... electric wheels, 1000 ... vehicles

Claims (10)

1. A stator core with multiple coils wound around it,
   A stator case that supports the stator core and
   A rotor core that is rotatably arranged with respect to the stator core through a gap,
   A rotor case that supports the rotor core and
   A first bearing and a second bearing for connecting the stator case and the rotor case are provided.
   The rolling elements of the first bearing and the second bearing and the coil end portion of the coil are arranged in a liquid refrigerant path in which the liquid refrigerant is accommodated.
   The gap is a first flow path through which the liquid refrigerant flows in the axial direction.
   The first bearing is arranged on the liquid refrigerant inlet side of the first flow path, and is arranged.
   The second bearing is arranged on the liquid refrigerant outlet side of the first flow path, and is arranged.
   The inner diameter of the second bearing is larger than the inner diameter of the first bearing.
2. In the rotary electric machine according to claim 1,
   The distance between the first bearing and the first coil end portion is longer than the distance between the liquid refrigerant inlet and the first coil end portion.
   A rotary electric machine in which the distance between the second bearing and the second coil end portion is longer than the distance between the liquid refrigerant outlet and the second coil end portion.
3. In the rotary electric machine according to claim 1,
   The first bearing is arranged in the liquid refrigerant path between the liquid refrigerant inlet and the coil end portion.
   A rotary electric machine in which the second bearing is arranged in the liquid refrigerant path between the liquid refrigerant outlet and the coil end portion.
4. In the rotary electric machine according to claim 1,
   A rotary electric machine in which the pressure of the liquid refrigerant applied to the first bearing is larger than the pressure of the liquid refrigerant applied to the second bearing.
5. In the rotary electric machine according to claim 1,
   A rotary electric machine in which the support portion of the first bearing of the rotor case to the support portion of the second bearing are integrally molded.
6. In the rotary electric machine according to claim 1,
   The second bearing or the first bearing is a rotary electric machine arranged at a position where it radially overlaps with the coil end portion.
7. In the rotary electric machine according to claim 6,
   A rotary electric machine in which a plurality of holes penetrating in the axial direction are provided on the side surface of the stator case between the second bearing and the coil end portion in the circumferential direction.
8. In the rotary electric machine according to claim 1,
   A rotary electric machine in which the first bearing and the second bearing are deep groove ball bearings.
9. In the rotary electric machine according to claim 1,
   A rotary electric machine in which an annular second flow path is arranged between the stator core and the stator case.
10. A vehicle provided with the rotary electric machine according to claim 1.
    Further, a vehicle comprising a battery and a power conversion device that converts the DC power of the battery into AC power and supplies the AC power to the rotary electric machine, and the torque of the rotary electric machine is directly transmitted to the wheels.

Images