Wheel drive system

Abstract

To provide a wheel driving device having an in-wheel motor structure, which enables a rotation detecting device to detect rotation properly.SOLUTION: A rotary electric machine 12 is stored inside in a radial direction of a cylindrical wheel 11. The rotary electric machine 12 has a rotator 30 that rotates together with a rotating shaft 36, and a stator 40 arranged to oppose to inside in a radial direction of the rotator 30. The stator 40 has a stator winding 41, and a cylindrical stator core 42 assembled to the inside in a radial direction of the stator winding 41 to hold the stator winding 41 and a stator holder 43. A rotation sensor 80 that detects rotation of the rotating shaft 36 is mounted on the stator holder 43. A refrigerant passage 48 through which refrigerants are passed is provided at a part to be mounted on which the rotation sensor 80 is mounted in a holder end plate part 45.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The disclosure in this specification relates to a wheel drive device.

Background Art

[0002] Conventionally, as a wheel drive device, one having a so-called in-wheel motor structure in which a rotating electrical machine is housed radially inside a wheel is known. Further, various technologies for detecting rotation of a rotating shaft in an in-wheel motor have been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In a wheel drive device used as an in-wheel motor for a vehicle, a brake device for rotational braking is provided integrally or separately. In such a configuration, it is conceivable that heat generated in the brake device is transmitted to the rotation detection device. In this case, there is a concern that the temperature of members such as circuits and coils constituting the rotation detection device may rise excessively, causing abnormalities such as malfunction and failure due to thermal deterioration.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to enable appropriate rotation detection by a rotation detection device in a wheel drive device having an in-wheel motor structure.

Means for Solving the Problem

[0006] The present invention A wheel drive device comprising a rotating electric machine housed radially inside a cylindrical wheel and rotating the wheel, wherein the rotating electric machine has a rotor that rotates integrally with the rotating shaft and a stator that is positioned opposite to the rotor radially inside, The stator comprises a stator winding and a cylindrical retaining member that holds the stator winding while being assembled radially inward of the stator winding. The holding member is equipped with a rotation detection device for detecting the rotation of the rotating shaft, and a refrigerant passage for circulating refrigerant is provided in the mounting portion of the holding member to which the rotation detection device is attached.

[0007] In wheel drive systems used as in-wheel motors in vehicles, there is a concern that the heat generated by the braking system for rotational braking may affect the rotation detection device. In this regard, in a rotating electric machine where the rotation detection device is attached to the stator's holding member, a refrigerant passage is provided in the mounting portion of the holding member to which the rotation detection device is attached. This reduces the impact of heat generated by the braking system on the rotation detection device. As a result, rotation detection by the rotation detection device can be properly performed in wheel drive systems with an in-wheel motor structure. [Brief explanation of the drawing]

[0008] [Figure 1] A perspective view showing the entire wheel unit. [Figure 2] A longitudinal cross-sectional view of the wheel unit. [Figure 3] Front view of a rotating electric machine equipped with a braking device. [Figure 4] Longitudinal cross-sectional view of a rotating electric machine. [Figure 5] Perspective view of the stator. [Figure 6] Perspective view of the stator holder. [Figure 7] Diagram of the rotor carrier configuration. [Figure 8] A diagram showing the positional relationship between the sensor body and the refrigerant passage. [Figure 9]Front view of a rotating electric machine equipped with a braking device in another configuration. [Figure 10] A longitudinal cross-sectional view of a rotating electric machine in a different configuration. [Figure 11] A longitudinal cross-sectional view of a rotating electric machine in a different configuration. [Figure 12] A longitudinal cross-sectional view of a rotating electric machine in a different configuration. [Figure 13] Front view of a rotor carrier in another configuration. [Figure 14] A diagram showing the configuration of the refrigerant passage in a different form. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the wheel drive device according to the present invention, implemented as a wheel unit, will be described with reference to the drawings. The wheel unit is used as a drive wheel in vehicles such as four-wheeled vehicles and two-wheeled vehicles, and comprises a wheel to which a tire is attached, and a rotating electric machine (in-wheel motor) housed in the inner space of the wheel.

[0010] Figure 1 is a perspective view showing the entire wheel unit 10, and Figure 2 is a longitudinal cross-sectional view of the wheel unit 10. Figure 1 shows the configuration of the wheel unit 10, which is located on the side of the vehicle, as seen from the inside of the vehicle. Note that the configuration of the suspension mechanism, such as the knuckle arm, is omitted in Figure 1.

[0011] As shown in FIGS. 1 and 2, the wheel unit 10 is roughly divided into a cylindrical wheel 11, a rotating electric machine 12 that rotates the wheel 11, and a brake device 13 that brakes the wheel 11. The rotating electric machine 12 is fixed to the inner peripheral side of the wheel 11. The rotating electric machine 12 has a fixed portion which is a portion including a stator 40 and a rotating portion which is a portion including a rotor 30. The fixed portion is fixed to a vehicle body side (not shown), the rotating portion is fixed to the wheel 11, and the wheel 11 is rotated by the rotation of the rotating portion. In the following description, the direction in which the rotation axis of the rotating electric machine 12 (the wheel 11) extends is defined as the axial direction, the direction extending radially from the center of the rotation axis is defined as the radial direction, and the direction extending circumferentially around the rotation axis is defined as the circumferential direction. The detailed configuration of the rotating electric machine 12 including the fixed portion and the rotating portion will be described later. In the present embodiment, the rotating electric machine 12 and the brake device 13 correspond to a "wheel drive device".

[0012] The wheel 11 includes a tire 21 and a wheel 22 fixed to the inner peripheral side of the tire 21. The wheel 22 has a hub 23 serving as the rotation center of the wheel 11, a cylindrical rim 24 provided to surround the hub 23, and a spoke portion 25 connecting the hub 23 and the rim 24. The tire 21 is attached to the outer peripheral side of the rim 24. The hub 23 and the spoke portion 25 are provided on one axial end side of the rim 24, and the rotating electric machine 12 is accommodated in the inner space of the rim 24 (the inner space of the wheel 22). The rotating electric machine 12 is provided in a state of being fixed to the hub 23 of the wheel 22.

[0013] The configurations of the rotating electric machine 12 and the brake device 13 will be described below. FIG. 3 is a front view of the rotating electric machine 12 provided with the brake device 13, FIG. 4(a) is a cross-sectional view taken along line 4A-4A in FIG. 3, and FIG. 4(b) is a cross-sectional view taken along line 4B-4B in FIG. 3.

[0014] The rotating electric machine 12 is an outer-rotor type surface-mounted permanent magnet motor, and includes a rotor 30 and a stator 40 arranged radially inward of the rotor 30. The rotor 30 and the stator 40 are each formed in a cylindrical shape, and are arranged to face each other with an annularly extending air gap interposed therebetween.

[0015] The rotor 30 includes a substantially cylindrical rotor carrier 31 and an annular magnet unit 32 fixed to the rotor carrier 31. The rotor carrier 31 is made of, for example, a metallic material such as iron or aluminum, and includes a cylindrical cylindrical portion 33 and an end plate portion 34 provided on one axial end side of the cylindrical portion 33. The rotor carrier 31 is preferably made of a non-magnetic material. The magnet unit 32 is fixed to the inner circumferential surface of the cylindrical portion 33. The rotor carrier 31 functions as a magnet holding member. The other axial end side of the rotor carrier 31 is open. In the cylindrical portion 33, the diameter of the distal end portion on the open side is increased, and the distal end side relative to a magnet holding portion 33a that is a portion holding the magnet unit 32 serves as an increased diameter portion 33b.

[0016] The magnet unit 32 includes a plurality of magnets fixed to the inner circumferential surface of the cylindrical portion 33 of the rotor carrier 31. In the magnet unit 32, the magnets are arranged such that their polarities alternate along the circumferential direction of the rotor 30. Accordingly, the rotor 30 has a plurality of magnetic poles in the circumferential direction, and generates magnetic flux from magnets for each magnetic pole. The magnets are, for example, polar anisotropic permanent magnets, which are sintered neodymium magnets having an intrinsic coercive force of 400 [kA / m] or more and a residual magnetic flux density Br of 1.0 [T] or more. Incidentally, the rotating electric machine 12 may be an interior permanent magnet synchronous machine (IPMSM). The magnet unit 32 corresponds to a "magnetic flux generating portion".

[0017] In the rotor carrier 31, a hub bearing 35 is fixed at the radial center position of the rotor 30 on the inner side surface that is on the cylindrical portion 33 side among both axial side surfaces of the end plate portion 34, and a rotation shaft 36 extending in the axial direction is fixed to the hub bearing 35. The hub bearing 35 includes an outer ring 35a that is a stationary portion, an inner ring 35b that is a rotating portion, and a plurality of rolling elements 35c (for example, balls) provided between the outer ring 35a and the inner ring 35b. The inner ring 35b of the hub bearing 35 is fixed to the end plate portion 34. Further, the rotation shaft 36 is fixed to the inner ring 35b in a state of being capable of rotating integrally therewith. The rotation shaft 36 is provided coaxially with the hub 23 at the radial center of the rotating electric machine 12.

[0018] The rotor 30 is assembled to the wheel 11 by fixing the end plate portion 34 of the rotor carrier 31 to the hub 23 of the wheel 22 with fasteners such as bolts.

[0019] Next, the configuration of the stator 40 will be explained using Figures 4 to 6. Figure 5 is a perspective view showing the configuration of the stator 40, of which Figure 5(a) is a perspective view of the stator 40 seen from one side in the axial direction, and Figure 5(b) is a perspective view of the stator 40 seen from the other side in the axial direction. Figure 6 is a perspective view of the stator holder 43.

[0020] As shown in Figure 4, the stator 40 includes stator windings 41, a stator core 42, and a stator holder 43. The stator core 42 and the stator holder 43 are integrated with the stator core 42 facing radially outward, and the stator windings 41 are assembled to its radially outward side. The stator core 42 and the stator holder 43 correspond to the "holding members".

[0021] The stator winding 41 has multiple phase windings, and is formed in a cylindrical shape by arranging the phase windings of each phase in a predetermined order in the circumferential direction. In this embodiment, the stator winding 41 is composed of three phase windings of U, V, and W phases. The stator core 42 is cylindrical and is provided as a back yoke.

[0022] In this embodiment, the stator 40 has a teethless structure that does not have teeth for forming slots. This structure may be any of the following (A) to (C). (A) In the stator 40, interconductor members are provided between each conductor section (intermediate conductor section 52 described later) in the circumferential direction, and the interconductor members are made of a magnetic material such that Wt × Bs ≤ Wm × Br, where Wt is the circumferential width dimension of the interconductor member at one magnetic pole, Bs is the saturation magnetic flux density of the interconductor member, Wm is the circumferential width dimension of the magnet at one magnetic pole, and Br is the residual magnetic flux density of the magnet constituting the magnet unit 32. (B) A structure in which, in the stator 40, interconductor members are provided between each conductor portion in the circumferential direction, and a non-magnetic material is used as the interconductor member. (C) In the stator 40, there is no structure in which inter-conductor members are provided between each conductor portion in the circumferential direction.

[0023] Furthermore, as shown in Figure 5, the stator winding 41 has a plurality of partial windings 51 which are unit coils, and these partial windings 51 are arranged in a circumferential direction. In the stator winding 41, each phase winding is composed of a plurality of partial windings 51. The partial windings 51 are made by winding a conductor material in multiple layers and have a pair of intermediate conductor sections 52 that are parallel to each other and extend in the axial direction, and a pair of connecting sections 53, 54 that connect the pair of intermediate conductor sections 52 at their respective axial ends. These pair of intermediate conductor sections 52 and the pair of connecting sections 53, 54 form an annular shape.

[0024] Each of the connecting portions 53 and 54 on both sides of the axial direction is provided as a portion corresponding to the coil end, and of the connecting portions 53 and 54, one connecting portion 53 is formed by bending in the radial direction, while the other connecting portion 54 is formed without bending in the radial direction. Each partial winding 51 includes a partial winding 51 in which the connecting portion 53 is bent radially inward, and a partial winding 51 in which the connecting portion 53 is bent radially outward. In the stator 40, at the coil end CE1 on one end of the axial direction, the connecting portion 53 of the partial winding 51 is bent radially inward, and at the coil end CE2 on the other end of the axial direction, the connecting portion 53 of the partial winding 51 is bent radially outward.

[0025] Returning to the explanation of Figure 4, the stator holder 43 has a cylindrical portion 44 assembled radially inward of the stator core 42, an end plate portion 45 provided radially inward of the cylindrical portion 44 at one axial end of the cylindrical portion 44, and a flange portion 46 provided radially outward from the cylindrical portion 44 at the other axial end. The stator holder 43 has an end plate portion 45 on the same side as the end plate portion 34 of the rotor carrier 31 on both axial sides. The end plate portion 45 corresponds to the inner plate portion that extends radially inward in the stator holder 43. As a result, the rotor carrier 31 and the stator holder 43 are configured such that the end plate portions 34 and 45 face each other on one side of the axial direction, and are open on the other side. In the following description, in order to clarify the distinction between the end plate portions 34 and 45, the end plate portion 34 of the rotor carrier 31 will also be referred to as "carrier end plate portion 34," and the end plate portion 45 of the stator holder 43 will also be referred to as "holder end plate portion 45."

[0026] A refrigerant passage 47 is formed in the cylindrical portion 44 for circulating a refrigerant such as cooling water. The refrigerant passage 47 extends in a flattened shape in the axial direction and is provided in an annular shape along the cylindrical portion 44, and circulates the refrigerant in the circumferential direction between an inlet and an outlet (not shown). Although not shown, a circulation path for circulating the refrigerant is connected to the inlet and outlet of the refrigerant passage 47. The circulation path is provided with, for example, an electric pump and a heat dissipation device such as a radiator, and the refrigerant is circulated through the circulation path and the refrigerant passage 47 of the rotating electric machine 12 when the pump is driven.

[0027] The holder end plate portion 45 extends radially inward from the cylindrical portion 44 to the hub bearing 35, and serves as a partition plate portion that axially partitions the inner space of the cylindrical portion 44. The holder end plate portion 45 is formed in two steps in the axial direction. The base end plate portion 45a, which is the first step portion, extends radially inward from the axial end of the cylindrical portion 44, and the distal end plate portion 45b, which is the second step portion, is provided so as to extend radially inward to the hub bearing 35 via an intermediate cylindrical portion 45c extending in the axial direction (see FIG. 6). A plurality of holes 45d are provided in the center of the distal end plate portion 45b, and the hub bearing 35 (specifically, the outer ring 35a of the hub bearing 35) is fitted into the holes 45d. Thereby, the rotor carrier 31 (rotor 30) and the rotating shaft 36 are rotatably supported with respect to the stator holder 43 (stator 40).

[0028] The flange portion 46 is provided so as to be located outside the stator winding 41 in the axial direction, that is, outside the crossover portions 53 and 54 on one axial end side. The flange portion 46 is provided so as to project radially outward beyond the distal end of the crossover portion 53 (the crossover portion bent in the radial direction) of the partial winding 51, and more specifically, is provided so as to project radially outward beyond the magnet holding portion 33a in the cylindrical portion 33 of the rotor carrier 31. That is, the diameter of the flange portion 46 is larger than the outer diameter of the magnet holding portion 33a of the rotor carrier 31. If the outer diameter of the magnet holding portion 33a of the rotor carrier 31 is D1 and the outer diameter of the flange portion 46 is D2, they satisfy the relationship D1 < D2 (see FIG. 4(a)).

[0029] Furthermore, as shown in Figure 4, a wiring module 55 is provided at the axial end of the stator 40 as a winding connection member that is electrically connected to each partial winding 51 of the stator winding 41. The wiring module 55 is formed in an annular shape and has wiring members such as busbars for each phase. The wiring module 55 connects the partial windings 51 of each phase in parallel or in series for each phase, and the phase windings of each phase are interconnected. The wiring module 55 is provided on the coil end CE2 side, which is the open side of the stator holder 43, of the coil ends CE1 and CE2 on both axial sides of the stator 40. Coil end CE2 is the coil end on the side where the connecting portion 53 of the partial winding 51 is bent radially outward, and the wiring module 55 is provided between each connecting portion 53 and the flange portion 46 of the stator holder 43.

[0030] A power connector 71 is provided as a terminal on the flange portion 46 of the stator holder 43, and the wiring module 55 is electrically connected to the power connector 71. The power connector 71 is connected to each of the three phase power lines in the wiring module 55, and connection to an external connector is possible. In this embodiment, since the wiring module 55 is provided on the open side of the stator holder 43, that is, on the flange portion 46 side of both axial sides, the connection of the wiring module 55 to the power connector 71 is simplified. Note that the wiring module 55 may also be integrally provided with current sensors for detecting the phase current of each phase.

[0031] The power connector 71 is preferably positioned vertically upward when the rotating electric motor 12 is assembled to the wheel 11. This helps to prevent damage to the power cable connected to the power connector 71 when the rotating electric motor 12 is assembled to the vehicle as an in-wheel motor. For example, if the wheel 11 gets stuck in a ditch or the like while the vehicle is in motion, damage to the power cable connected to the power connector 71 is less likely to occur.

[0032] The configuration for installing the power connector 71 is described below. As shown in Figure 5(b), the flange portion 46 of the stator holder 43 is provided with a base portion 46a, which serves as a terminal mounting portion to which the power connector 71 is attached. This base portion 46a is a part of the flange portion 46 that is locally thicker than other parts. The base portion 46a is provided with a through hole 46b that penetrates in the axial direction, and the power connector 71 is attached by inserting it through the through hole 46b. This configuration increases the strength at the connector mounting location. Furthermore, as described above, the flange portion 46 is provided so as to protrude radially outward from the tip of the connecting portion 53 of the partial winding 51 and the magnet holding portion 33a of the rotor carrier 31, thereby expanding the axial end face of the flange portion 46. This ensures that a suitable area for attaching the power connector 71 is secured on the flange portion 46.

[0033] When the rotor 30 is assembled to the stator 40, as shown in Figure 4, the flange portion 46 of the stator holder 43 fits radially inward into the enlarged diameter portion 33b of the rotor carrier 31, and an annular seal 72 is attached as a sealing member between the radial outer surface of the flange portion 46 and the enlarged diameter portion 33b. This ensures airtightness of the parts constituting the magnetic circuit.

[0034] As shown in Figure 4, in the stator 40, the inner circumference of the cylindrical portion 44 of the stator holder 43 is a hollow portion 49. This hollow portion 49 is the inner cavity space of the magnetic circuit section consisting of the rotor 30 and the stator 40. In this embodiment, because the stator 40 has a teethless structure, the radial thickness of the stator 40 can be reduced, and the radial hollow portion 49 can be expanded. The brake device 13 is housed in the hollow portion 49.

[0035] Next, the brake device 13 will be explained using Figure 4(b).

[0036] The brake system 13 is a disc-type friction brake system and includes a disc-shaped brake disc 61 and a brake caliper 62. Since the configuration of the brake system 13 is arbitrary, a detailed explanation with illustrations is omitted, but the brake disc 61 can be a solid disc consisting of a single disc, or a ventilated disc having a cavity for ventilation inside. The brake caliper 62 is operated by hydraulic pressure or an electrical signal and includes a pair of brake pads that contact the brake disc 61 to generate braking force, a piston that presses the brake pads against the brake disc 61, and a caliper body that supports these brake pads and piston.

[0037] The brake disc 61 is fixed to the tip of the rotating shaft 36, which rotates integrally with the rotor 30, by fasteners 63 such as bolts. In this case, the brake disc 61 is coupled to the rotor carrier 31 via the rotating shaft 36 and the hub bearing 35. Therefore, compared to a configuration in which the brake disc 61 is directly coupled to the rotor carrier 31, the effect of braking torque on the rotor 30 can be reduced. In other words, deformation of the rotor carrier 31 due to braking torque is suppressed. Also, compared to a configuration in which the brake disc 61 is directly coupled to the rotor carrier 31, heat generated when the brake device 13 is in operation is less likely to be transmitted to the rotor 30.

[0038] The brake disc 61 is housed entirely within the hollow portion 49. In terms of its positional relationship with the wheel 22, it is preferable that the entire brake disc 61 is housed on the inner circumference side of the rim 24 (see Figure 2). However, it is also acceptable for only a portion of the brake disc 61 to be housed within the hollow portion 49, or for only a portion of the brake disc 61 to be housed on the inner circumference side of the rim 24.

[0039] The brake caliper 62 has an arm portion 64 that extends laterally from its main body, and this arm portion 64 is fixed to a boss portion 46c provided on the flange portion 46 of the stator holder 43 by a fastener 65 such as a bolt. The shape of the boss portion 46c is also shown in Figure 5(b). In other words, the main body portion of the brake caliper 62, excluding the arm portion 64, is housed inside the cylindrical portion 44, i.e., the hollow portion 49, of the stator holder 43. In this case, the arm portion 64 can be fixed to the axial end face of the stator holder 43 from the outside of the wheel. In addition, the brake caliper 62 can be cooled by heat being transferred to the stator holder 43 side via the arm portion 64.

[0040] The brake device 13 is installed in a state where it is housed in the hollow part 49 of the rotating electric machine 12, that is, in the hollow part within the magnetic circuit section of the rotating electric machine 12. In this case, when the brake device 13 is assembled to the rotating electric machine 12, the radial arrangement, viewed from the central axis side, is in the order of brake caliper 62, stator 40, air gap, and rotor 30. In this configuration, there is a heat dissipation section (coolant passage 47) of the stator holder 43 and an air gap between the heat-generating brake caliper 62 and the rotor 30 (magnet), so that the heat from the brake caliper 62 is not easily transferred to the rotor 30 (magnet), and thus demagnetization of the magnet is suppressed.

[0041] Furthermore, the rotating electric machine 12 is equipped with a rotation sensor 80 as a rotation detection device for detecting the rotation of the rotating shaft 36. The rotation sensor 80 is an inductive proximity sensor, and more specifically, an inductive eddy current sensor. As shown in Figure 4(a), the rotation sensor 80 has a sensor body 81 as a detection unit and a detected unit 82 that is the object of rotation detection. In this embodiment, the rotation sensor 80 is provided between the holder end plate 45 and the carrier end plate 34, and more specifically, the sensor body 81 is provided on the holder end plate 45, while the detected unit 82 is provided on the carrier end plate 34. In addition, the brake device 13 is arranged on one side of the holder end plate 45, and the rotation sensor 80 is arranged on the other side.

[0042] The rotation sensor 80 will now be described in detail. As shown in Figure 5(a), the sensor body 81 is attached to the base end plate portion 45a of the holder end plate portion 45. The sensor body 81 has a planar excitation coil and a receiving coil, and is in the shape of a long arc extending in an arc around the axis of rotation. The sensor body 81 is attached to the base end plate portion 45a of the holder end plate portion 45 so as to extend in an arc around the axis of rotation. More specifically regarding the attachment, the axial outer surface of the tip plate portion 45b of the holder end plate portion 45 is formed in a stepped shape with the inner side recessed relative to the radial outer circumference (see Figure 6), and the sensor body 81 is fixed to the recessed portion with the stepped shape relative to the radial outer circumference. In this case, the mounting surface to which the sensor body 81 is attached is provided at a position offset in the axial direction from the axial end face of the stator core 42. In other words, the sensor body 81 is provided at a position that overlaps with the stator core 42 in the axial direction.

[0043] On the other hand, the carrier end plate portion 34 on which the detection unit 82 is provided has the following configuration. Figures 7(a) and 7(b) are configuration diagrams of the rotor carrier 31.

[0044] As shown in Figure 7(a), the carrier end plate portion 34 can be broadly divided into areas in the radial direction, from the radially outermost to the right, as follows: coil end housing area A1, detection area A2, and shaft fixing area A3. These areas A1 to A3 are arranged concentrically in the radial direction. As shown in Figure 7(b), the coil end housing area A1 is provided with an annular housing portion 34a that protrudes in the axial direction toward the side opposite the stator (towards the back of the figure) and houses the coil end CE1 of the stator winding 41.

[0045] Furthermore, the detection area A2 and the shaft fixing area A3 are recessed axially toward the carrier center relative to the coil end housing area A1. The detection area A2 has a plurality of protrusions 34b provided at predetermined intervals in the circumferential direction, and the plurality of protrusions 34b arranged in the circumferential direction correspond to the detection area 82. In other words, the detection area A2 of the carrier end plate portion 34 has a detection area 82 consisting of a plurality of protrusions 34b integrally molded into it. Each protrusion 34b is substantially rectangular in shape when viewed from the front and is molded to protrude to a certain height. In addition, the shaft fixing area A3 has an insertion hole 34c for inserting a fastener that fixes the carrier end plate portion 34 to the hub 23. In this configuration, the detection area 82 is integrally molded in the carrier end plate portion 34 to the portion surrounding the shaft fixing portion. The rotor carrier 31 can be manufactured by methods such as casting, forging, or machining.

[0046] Furthermore, in this embodiment, a refrigerant passage 48 for cooling the rotation sensor 80 is provided in the base end plate portion 45a of the holder end plate portion 45. This refrigerant passage 48 is a passage continuous with the refrigerant passage 47 provided in the cylindrical portion 44, and when refrigerant flows through the annular refrigerant passage 47 by pump drive, the refrigerant flows into the refrigerant passage 48, thereby cooling the sensor body 81. For the sake of explanation, the refrigerant passage 47 provided in the cylindrical portion 44 will also be referred to as the "coil refrigerant passage 47," and the refrigerant passage 48 provided in the holder end plate portion 45 will also be referred to as the "sensor refrigerant passage 48."

[0047] Figure 8 shows the positional relationship between the sensor body 81 and the refrigerant passage 48. Figure 8(a) is a front view of the stator 40, and Figure 8(b) is a cross-sectional view showing the refrigerant passages 47 and 48 formed in the stator holder 43. In Figures 8(a) and (b), the vertical direction is the vertical direction, and the top side is the upper side in the vertical direction.

[0048] The coil refrigerant passage 47 is provided in an annular shape, and the sensor refrigerant passage 48 is formed so as to extend radially inward from the coil refrigerant passage 47. In the coil refrigerant passage 47, for example, an inlet and an outlet are provided at the positions shown in the figure, and the refrigerant flowing in from the inlet flows through each refrigerant passage 47, 48. The sensor refrigerant passage 48 is preferably provided so that its upstream part corresponds to the inlet of the coil refrigerant passage 47 in the circumferential direction. Furthermore, the sensor refrigerant passage 48 is preferably provided in a position that is vertically above, more specifically, in the area that includes the vertically uppermost position of the coil refrigerant passage 47. However, the positions of the inlet and outlet of the coil refrigerant passage 47, the position of the sensor refrigerant passage 48 relative to these inlets and outlets, and the circumferential position of the sensor refrigerant passage 48 are all changeable.

[0049] As can be seen from the comparison in Figures 8(a) and (b), the sensor refrigerant passage 48 is provided at a position opposite the sensor body 81 in the axial direction (i.e., a position where they overlap in the axial direction). The circumferential length of the sensor refrigerant passage 48 should be the same as or longer than the circumferential length of the sensor body 81. Also, the radial width of the sensor refrigerant passage 48 should be the same as or wider than the radial width of the sensor body 81. In this case, the axial projected area of ​​the sensor refrigerant passage 48 should be the same as or greater than the frontal area (area when viewed from the front) of the sensor body 81. Furthermore, the sensor refrigerant passage 48 should satisfy at least one of the following conditions: its circumferential length is longer than the circumferential length of the sensor body 81, and its radial width is wider than the radial width of the sensor body 81.

[0050] The sensor body 81 may also be provided over the entire circumference of the holder end plate portion 45. In this case, it is preferable that the sensor refrigerant passage 48 is also provided over the entire circumference.

[0051] Here, we will provide a supplementary explanation of the relationship between the brake device 13 and the sensor refrigerant passage 48 using Figure 4(a).

[0052] On one of the axial sides of the holder end plate portion 45, the sensor body 81 is attached to the mounting surface of the base end plate portion 45a, while the other side faces the brake device 13. In this case, since the brake device 13 is in close proximity to the holder end plate portion 45 in the hollow portion 49 within the stator holder 43, it is conceivable that heat generated by the brake device 13 is transferred to the holder end plate portion 45 by radiation. In particular, it is thought that the wider the area where the holder end plate portion 45 and the brake disc 61 are facing each other in a generally parallel manner, the easier it is for radiant heat to be transferred. In this configuration, a sensor refrigerant passage 48 is provided in the holder end plate portion 45 between the brake device 13 and the sensor body 81. As a result, the radiant heat transmitted from the brake device 13 is transferred to the refrigerant flowing through the sensor refrigerant passage 48 and moves to the outside of the rotating electric machine 12 along with the movement of the refrigerant. This suppresses the transfer of radiant heat from the brake device 13 to the sensor body 81 in the holder end plate portion 45.

[0053] Furthermore, since the holder end plate portion 45 is configured to actively absorb the radiant heat of the brake device 13, radiant cooling of the brake device 13 is promoted, making it possible to suppress the temperature rise of the brake device 13. Therefore, it is possible to expect the brake device 13 to become overheated and the brakes to become less effective, thus preventing such problems.

[0054] Regarding the assembly of the rotating electric machine 12 and the brake device 13, as shown in Figure 2, the stator 40 is assembled with the coil end CE1 closer to the hub 23 and the coil end CE2 further away from the hub 23 in the axial direction. In this configuration, the rotor 30 is positioned radially outward of the stator 40, and the brake device 13 is fixed radially inward of the stator 40, inserted from the coil end CE2 side. In this case, the brake device 13 can be assembled to the stator 40 from the coil end CE2 side.

[0055] According to the embodiment described in detail above, the following excellent effects can be obtained.

[0056] In the rotating electric machine 12, a sensor refrigerant passage 48 for circulating refrigerant is provided at the end plate portion 45 of the stator holder 43 to which the rotation sensor 80 is attached. This makes it possible to reduce the effect of heat generated by the brake device 13 on the rotation sensor 80. As a result, rotation detection by the rotation sensor 80 can be properly performed in a wheel drive system with an in-wheel motor structure.

[0057] When a brake device 13 is integrated with the rotating electric machine 12, it is desirable to position the brake device 13 radially inward of the stator holder 43 in order to miniaturize the entire device. However, in this case, there is a concern that the heat from the brake device 13 will be transferred to the rotation sensor 80 via the stator holder 43, potentially negatively affecting the rotation sensor 80. To address this, a holder end plate portion 45 is provided in the stator holder 43 that extends radially and faces the brake device 13 in the axial direction, and the rotation sensor 80 is attached to the holder end plate portion 45 on the opposite side of the brake device 13. This allows for effective cooling of the stator holder 43 before the heat generated by the brake device 13 is transferred to the rotation sensor 80.

[0058] The holder end plate portion 45 extending radially inward in the stator holder 43 partitions the space housing the brake device 13 radially inward, suppressing the direct transfer of heat generated by the brake device 13 to the opposite side of the holder end plate portion 45. Furthermore, the provision of a sensor refrigerant passage 48 in the mounting portion, which is part of the holder end plate portion 45, enhances the heat shielding effect on the rotation sensor 80.

[0059] A sensor body 81, which includes a planar coil, of the rotation sensor 80 is attached to the holder end plate portion 45, and the sensor body 81 is cooled by the refrigerant flowing through the sensor refrigerant passage 48. The sensor body 81 is attached to the holder end plate portion 45 that extends radially inward in the stator holder 43, and the detected part 82 (the object to be detected) is positioned axially opposite to the sensor body 81. In this case, the sensor body 81 and the detected part 82 face each other, so that the planar coil of the sensor body 81 is properly cooled.

[0060] The sensor refrigerant passage 48 is provided at a position axially opposite to the sensor body 81, and satisfies at least one of the following conditions: its circumferential length is longer than the circumferential length of the sensor body 81, and its radial width is wider than the radial width of the sensor body 81. This ensures that the size of the sensor refrigerant passage 48 is appropriately determined in relation to the size of the sensor body 81, allowing for proper cooling of the sensor body 81.

[0061] Since the refrigerant is configured to flow from the coil refrigerant passage 47 (second refrigerant passage) to the sensor refrigerant passage 48 (first refrigerant passage), the refrigerant can be efficiently supplied to each of the refrigerant passages 47 and 48 using a single refrigerant distribution system.

[0062] The coil refrigerant passage 47 is positioned radially between the brake device 13 and the power connector 71, and overlaps with the power connector 71 in the axial direction. This reduces the impact of heat from the brake device 13 on the power connector 71.

[0063] (Other embodiments) The above embodiment may be modified as follows, for example.

[0064] In the above embodiment, the flange portion 46 of the stator holder 43 is configured such that its entire circumferential direction extends radially outward beyond the outer diameter of the magnet holding portion 33a of the rotor carrier 31. However, this configuration may be changed. For example, as shown in Figure 9, the flange portion 46 of the stator holder 43 may be configured such that a radially outward-extending extension portion 46d (more specifically, an extension portion 46d that extends beyond the outer diameter of the magnet holding portion 33a of the rotor carrier 31) is provided in a part of the circumferential direction. In this case, the outer diameter of the flange portion 46 is reduced in the part excluding the extension portion 46d, resulting in weight reduction. The power connector 71 is attached to the extension portion 46d.

[0065] Furthermore, Figure 10 shows the cross-sectional structure of the rotating electric machine 12 when it is configured as shown in Figure 9. In Figure 10, the enlarged diameter portion 33b of the rotor carrier 31 is a plate portion that extends radially, and the flange portion 46 faces the enlarged diameter portion 33b in the axial direction. An annular seal 72 is attached between the enlarged diameter portion 33b and the flange portion 46 of the rotor carrier 31, which face each other in the axial direction.

[0066] As shown in Figure 11, a power connector 71 may be provided on the flange portion 46 of the stator holder 43 in an oblique direction with respect to the axial direction. For example, the power connector 71 may be provided on the side of the rotating electric machine 12 facing obliquely upward. In this case, a through hole 46b may be provided in the base portion 46a of the flange portion 46 in an oblique direction with respect to the axial direction, and the power connector 71 may be fixed to the through hole 46b. This allows the power cable (external cable) to be connected to the power connector 71 from an oblique direction with respect to the axial direction, making wiring connection work easier. Furthermore, considering that a suspension mechanism or the like may be provided on the side of the rotating electric machine 12, connecting the power cable obliquely with respect to the axial direction makes it easier to avoid interference with the suspension mechanism or the like, making it possible to simplify the wiring layout on the axial side of the rotating electric machine 12.

[0067] In the configuration shown in Figure 12, the holder end plate portion 45 is provided at an acute angle from the axial end of the cylindrical portion 44 toward the axial inward side, and the sensor body 81 is attached to the holder end plate portion 45. In other words, the end plate portion 45 has an inclined portion that extends diagonally from the axial end of the cylindrical portion 44 in a direction perpendicular to the axial direction, and the sensor body 81 is attached to this inclined portion. Furthermore, in the carrier end plate portion 34, the detection portion 82 is integrally molded on the opposing surface parallel to the inclined portion of the holder end plate portion 45. In this configuration, by inclining the holder end plate portion 45, it becomes easier to secure a fixing surface for fixing the sensor body 81, and even if the rotating electric machine has a small diameter, the rotation sensor 80 can be suitably installed.

[0068] As shown in Figure 13, the rotor carrier 31 may be configured such that the protrusions 34b of the detected portion 82 are provided as ribs of a predetermined height that extend radially from the rotation center side of the rotor 30. Specifically, each protrusion 34b is provided as a ridge with the radial direction as the elongated direction. This suppresses in-plane deflection at the end plate portion 34 of the rotor carrier 31, and maintains the detection accuracy of the rotation sensor 80.

[0069] In the rotor carrier 31 shown in Figure 13, the detection portion 82 is integrally molded on one of the two surfaces of the end plate portion 34 (the surface on the holder end plate portion 45 side), while the other surface (the surface opposite the holder end plate portion) serves as a shaft fixing portion to which the rotating shaft 36 is fixed. In other words, the rotating shaft 36 is fixed axially outward by passing through the central hole of the end plate portion 34, and the detection portion 82 is integrally molded on the back side of the shaft fixing portion. The rotating shaft 36 may extend in any direction from the end plate portion 34 in a direction perpendicular to the end plate portion 34.

[0070] The stator holder 43 may be configured as follows: In Figure 14(a), the sensor refrigerant passage 48 has different axial passage opening areas on the radially outer and radially inner sides, with the passage opening area being larger on the radially outer side, i.e., on the coil refrigerant passage 47 side. This promotes the inflow of refrigerant from the coil refrigerant passage 47 to the sensor refrigerant passage 48, thereby effectively cooling the sensor body 81.

[0071] In particular, in the configuration shown in Figure 14(a), the sensor refrigerant passage 48 is provided so as to extend radially inward from the coil refrigerant passage 47. In this configuration, the inflow of refrigerant from the coil refrigerant passage 47 to the sensor refrigerant passage 48 is effectively facilitated.

[0072] Furthermore, in Figure 14(b), the refrigerant is configured to flow in series through the coil refrigerant passage 47 and the sensor refrigerant passage 48. In Figure 14(b), the refrigerant passages 47 and 48 extending in the circumferential direction in the stator holder 43 are shown in a plan view. In this case, the refrigerant flowing in from the inlet first flows circumferentially through the coil refrigerant passage 47, and then flows out from the outlet via the sensor refrigerant passage 48. This ensures that the refrigerant flows reliably through the sensor refrigerant passage 48, improving the cooling performance of the sensor body 81. In Figure 14(b), the direction of refrigerant flow in the coil refrigerant passage 47 and the sensor refrigerant passage 48 is opposite in the circumferential direction, but it is also possible to have them flow in the same direction in the circumferential direction.

[0073] It is also possible to provide a coil refrigerant passage 47 and a sensor refrigerant passage 48 separately, and to provide an inlet and an outlet for each of these refrigerant passages 47 and 48. In this case, the refrigerant for cooling the stator winding 41 and the refrigerant for cooling the sensor body 81 are supplied separately, and the refrigerant supply pattern to each of the refrigerant passages 47 and 48 can be individually adjusted.

[0074] In the above embodiment, a power connector 71 is provided as a terminal on the flange portion 46 of the stator holder 43, but this can be changed. For example, a terminal device having a relay board may be attached to the flange portion 46 as a terminal. The relay board may be provided with a connector to which an external power line can be connected.

[0075] In the rotor carrier 31, a cylindrical portion 33 and a disc-shaped end plate portion 34 may be formed separately, and these cylindrical portion 33 and end plate portion 34 may be joined to each other by joining means such as welding or adhesive. In this case, it is preferable that at least the end plate portion 34 is made of a non-magnetic material. It is also possible to form convex detection portions 82 (multiple convex portions 34b) on the end plate portion 34 by press working.

[0076] In the rotor carrier 31, it is also possible to form the end plate portion 34 and the detected portion 82 of the rotation sensor 80 separately, and to fix the end plate portion 34 and the detected portion 82 to each other with fasteners such as bolts.

[0077] It is also possible to use rotation sensors other than inductive proximity sensors as rotation detection devices. For example, a resolver can be used as a rotation detection device.

[0078] The brake system 13 may be configured such that multiple brake calipers 62 are provided for a single brake disc 61. Alternatively, multiple brake discs 61 may be provided on the rotating shaft 36. By using multiple brake discs 61 or brake calipers 62 in the brake system 13, the braking force in the in-wheel motor can be increased.

[0079] The rotating electric machine 12 may not have a brake device 13 integrated into it. In this case, the hollow portion 49 on the radially inner side of the stator holder 43 may house, for example, electrical components that constitute an inverter.

[0080] The stator winding 41 is not limited to one using multiple partial windings 51, and may be a configuration in which a conductor is wound by wave winding. In this case, it is preferable that the stator winding 41, which is formed into a cylindrical shape by wave winding, is assembled to the cylindrical stator core 42. The stator 40 may also have a toothed structure. In this case, multiple teeth are provided on the stator core, and the stator winding is wound in the slots formed between each tooth.

[0081] The stator 40 may be configured without a stator core 42. In this case, the stator windings 41 may be assembled to the stator holder 43.

[0082] In the embodiments described above, a surface-mounted magnet type rotor was used as the rotor 30, but instead, a recessed magnet type rotor or a field coil type rotor may be used.

[0083] In the embodiments described above, the rotating electric machine is of an outer rotor structure, but this may be changed to an inner rotor structure. In an inner rotor structure, the stator is provided on the radially outer side and the rotor is provided on the radially inner side. In this case, the flange portion 46 of the stator holder 43 extends radially inward, and a power connector 71 or the like may be provided on the flange portion 46.

[0084] The disclosures in this specification are not limited to the exemplary embodiments. The disclosures encompass the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosures are not limited to combinations of parts and / or elements shown in the embodiments. The disclosures are implementable in a variety of combinations. The disclosures may have additional parts that can be added to the embodiments. The disclosures encompass embodiments in which parts and / or elements are omitted. The disclosures encompass substitutions or combinations of parts and / or elements between one embodiment and another. The scope of the disclosed technical areas is not limited to the descriptions of the embodiments. Some of the scope of the disclosed technical areas are indicated by the claims and should be understood to include all modifications within the meaning and scope equivalent to the claims.

[0085] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A wheel drive device comprising a rotating electric machine (12) housed radially inside a cylindrical wheel (11) and for rotating the wheel, wherein the rotating electric machine has a rotor (30) that rotates integrally with a rotating shaft (36) and a stator (40) that is positioned opposite to the rotor radially inside, The stator comprises a stator winding (41) and cylindrical holding members (42, 43) that are assembled radially inward of the stator winding and hold the stator winding. A wheel drive device is provided in which a rotation detection device (80) for detecting the rotation of the rotating shaft is attached to the holding member, and a refrigerant passage (48) for circulating refrigerant is provided in the mounting portion of the holding member to which the rotation detection device is attached. [Configuration 2] A wheel drive system comprising a brake device (13) that generates frictional braking force on the wheel, The brake device is positioned radially inward of the retaining member. The mounting portion is provided in the holding member so as to extend radially inward and is facing the brake device in the axial direction. The wheel drive device according to configuration 1, wherein the rotation detection device is attached to the opposite side of the brake device at the mounting portion. [Configuration 3] The holding member has an inner plate portion (45) extending radially inward, and a bearing (35) that rotatably supports the rotor is fixed to the radially inward tip of the inner plate portion. The space in which the brake device is housed is partitioned by the inner plate portion, on the radially inner side of the retaining member. The wheel drive device according to configuration 2, wherein the refrigerant passage is provided in the mounting portion which is part of the inner plate portion. [Structure 4] The rotation detection device is an inductive proximity sensor having a detected part (82) which is the object of rotation detection, and a detection part (81) which includes a planar coil and detects the rotation of the detected part. The mounting portion is provided in the holding member so as to extend radially inward, A wheel drive device according to any one of configurations 1 to 3, wherein the detection unit is attached to the mounting unit, and the detection unit is provided at a position facing the detection unit in the axial direction. [Composition 5] The detection unit has a long arc shape that extends in an arc shape around the rotation axis, The wheel drive device according to configuration 4, wherein the refrigerant passage is provided at a position facing the detection unit in the axial direction, and satisfies at least one of the following conditions: its circumferential length is longer than the circumferential length of the detection unit, and its radial width is wider than the radial width of the detection unit. [Composition 6] The aforementioned refrigerant passage is the first refrigerant passage (48), The holding member is provided with a second refrigerant passage (47) extending in the circumferential direction in the cylindrical portion. The wheel drive device according to any one of configurations 1 to 5, wherein the first refrigerant passage is in communication with the second refrigerant passage and is provided so that refrigerant flows in from the second refrigerant passage. [Composition 7] A wheel drive system comprising a brake device (13) that generates frictional braking force on the wheel, The brake device is positioned radially inward of the retaining member. A terminal portion (71) for inputting and outputting power to the stator winding is attached to the axial end of the holding member. The wheel drive device according to configuration 6, wherein the second refrigerant passage is positioned radially between the brake device and the terminal portion and is provided so as to overlap the terminal portion in the axial direction. [Explanation of Symbols]

[0086] 10...Wheel unit, 11...Wheel, 12...Rotating electric machine, 30...Rotor, 36...Rotating shaft, 40...Stator, 41...Stator winding, 42...Stator core, 43...Stator holder, 48...Sensor refrigerant passage, 80...Rotating sensor.

Claims

1. A wheel drive device comprising a rotating electric machine (12) housed radially inside a cylindrical wheel (11) for rotating the wheel, and a brake device (13) for generating frictional braking force on the wheel, wherein the rotating electric machine has a rotor (30) that rotates integrally with a rotating shaft (36), and a stator (40) that is positioned opposite to the rotor radially inside, The stator comprises a stator winding (41) and cylindrical holding members (42, 43) that are assembled radially inward of the stator winding and hold the stator winding. The brake device is positioned radially inward of the retaining member. A rotation detection device (80) for detecting the rotation of the rotating shaft is attached to the holding member, and a refrigerant passage (48) for circulating refrigerant is provided in the mounting portion of the holding member to which the rotation detection device is attached. The mounting portion is provided in the holding member so as to extend radially inward and is facing the brake device in the axial direction. A wheel drive system in which the rotation detection device is attached to the opposite side of the brake device at the mounting portion.

2. The holding member has an inner plate portion (45) extending radially inward, and a bearing (35) that rotatably supports the rotor is fixed to the radially inward tip of the inner plate portion. The space in which the brake device is housed is partitioned by the inner plate portion, on the radially inner side of the retaining member. The wheel drive device according to claim 1, wherein the refrigerant passage is provided in the mounting portion which is part of the inner plate portion.

3. A wheel drive device comprising a rotating electric machine (12) housed radially inside a cylindrical wheel (11) and rotating the wheel, wherein the rotating electric machine has a rotor (30) that rotates integrally with a rotating shaft (36) and a stator (40) that is positioned opposite to the rotor radially inside, The stator comprises a stator winding (41) and cylindrical holding members (42, 43) that are assembled radially inward of the stator winding and hold the stator winding. A rotation detection device (80) for detecting the rotation of the rotating shaft is attached to the holding member, and a refrigerant passage (48) for circulating refrigerant is provided in the mounting portion of the holding member to which the rotation detection device is attached. The rotation detection device is an inductive proximity sensor having a detected part (82) which is the object of rotation detection, and a detection part (81) which includes a planar coil and detects the rotation of the detected part. The mounting portion is provided in the holding member so as to extend radially inward, A wheel drive device in which the detection unit is attached to the mounting unit, and the detection unit is provided at a position facing the detection unit in the axial direction.

4. The detection unit has a long arc shape that extends in an arc shape with respect to the rotation axis, The wheel drive device according to claim 3, wherein the refrigerant passage is provided at a position facing the detection unit in the axial direction, and satisfies at least one of the following: its circumferential length is longer than the circumferential length of the detection unit, and its radial width is wider than the radial width of the detection unit.

5. A wheel drive device comprising a rotating electric machine (12) housed radially inside a cylindrical wheel (11) and rotating the wheel, wherein the rotating electric machine has a rotor (30) that rotates integrally with a rotating shaft (36) and a stator (40) that is positioned opposite to the rotor radially inside, The stator comprises a stator winding (41) and cylindrical holding members (42, 43) that are assembled radially inward of the stator winding and hold the stator winding. A rotation detection device (80) for detecting the rotation of the rotating shaft is attached to the holding member, and a refrigerant passage (48) for circulating refrigerant is provided in the mounting portion of the holding member to which the rotation detection device is attached. The aforementioned refrigerant passage is the first refrigerant passage (48), The holding member is provided with a second refrigerant passage (47) extending in the circumferential direction in the cylindrical portion. A wheel drive device in which the first refrigerant passage is connected to the second refrigerant passage, and is configured so that refrigerant flows in from the second refrigerant passage.

6. A wheel drive system comprising a brake device (13) that generates frictional braking force on the wheel, The brake device is positioned radially inward of the retaining member. A terminal portion (71) for inputting and outputting power to the stator winding is attached to the axial end of the holding member. The wheel drive device according to claim 5, wherein the second refrigerant passage is positioned radially between the brake device and the terminal portion and is provided so as to overlap the terminal portion in the axial direction.

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