Driving device

Abstract

To provide a driving device which improves corrosion resistance, reduces weight and suppresses vibration.SOLUTION: In a driving device 101 in which a motor part 50 and ECU 60 are integrally constructed, a motor case 201 is formed of a non-metallic molding material, and a cylinder part 22 extending in an axial direction of the motor part 50 and a front base 23 for holding a front bearing 56 which supports a shaft 55 on a front side of the motor part 50 are integrally formed. A rear frame 40 is a component different from the motor case 201 and holds a rear bearing 57 for supporting the shaft 55 on a rear side of the motor part 50. An ECU cover 70 is formed in a container shape for covering a substrate 65 of the ECU 60 with a resin material, and an end of a side plate 72 is joined to an end of the cylinder part 22 in the motor case 201. A stator 53 is molded by the non-metallic molding material. A stator mold part 25 which molds the stator 53 is integrally molded with the cylinder part 22 of the motor case 201.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a drive device.

Background Art

[0002] Conventionally, a drive device in which an ECU (control unit) is integrally provided at one axial end of a motor unit is known.

[0003] For example, in the drive device disclosed in Patent Document 1, a stator is fixed inside a cylindrical portion of a metal motor case. The space between the cylindrical portion of the motor case and a resin ECU cover is sealed with an adhesive.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the drive device of Patent Document 1, since the motor case is made of metal, the exposed metal may come into contact with moisture in the air or rainwater containing salt water and corrode, and the sealing performance of the adhesive portion between the motor case and the ECU cover may deteriorate. Further, if the motor case is made of metal, the weight of the motor unit increases. Furthermore, there is a problem that the stator fixed to the motor case is liable to receive vibrations of the motor.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a drive device that improves corrosion resistance, reduces weight, and suppresses vibrations.

Means for Solving the Problems

[0007] The drive device of the present invention is integrally configured with a motor unit (50) in which a rotor (54) disposed radially inside an annular stator (53) rotates integrally with a shaft (55), and an ECU (60) provided on one axial side of the motor unit to control the drive of the motor unit.

[0008] Regarding the motor unit, the side opposite to the ECU is defined as the front side, and the ECU side with respect to the motor unit is defined as the rear side. The drive device of the first aspect includes a motor case (201), a rear frame (40), and an ECU cover (70, 704). The drive device of the second aspect includes a motor case (202), a front frame (30), and an ECU cover.

[0009] The motor case is formed of a non-metallic molding material. Preferably, the motor case is formed of a carbon fiber composite material (CFRP) or a resin material having a glass fiber (GF) blending ratio of 35% or more.

[0010] The motor case in the first aspect is integrally formed with a cylindrical portion (22) extending in the axial direction of the motor unit and a front bottom portion (23) that holds a front bearing (56) that supports the shaft on the front side of the motor unit. The motor case in the second aspect is integrally formed with a cylindrical portion (22) extending in the axial direction of the motor unit and a rear bottom portion (24) that holds a rear bearing (57) that supports the shaft on the rear side of the motor unit.

[0011] The rear frame in the first aspect is a separate part from the motor case and holds a rear bearing (57) that supports the shaft on the rear side of the motor unit. The front frame in the second aspect is a separate part from the motor case and holds a front bearing (56) that supports the shaft on the front side of the motor unit.

[0012] In common to the first and second aspects, the ECU cover is formed in a container shape that covers the substrate (65) of the ECU with a resin material, and the end of the side plate (72) is joined to the end of the cylindrical portion of the motor case. Preferably, the ECU cover is formed of a resin material different from that of the motor case.

[0013] In common with the first and second aspects, the stator is molded from a non-metallic molding material. Further, a stator molding portion (25) that molds the stator is integrally formed with a cylindrical portion of the motor case.

[0014] In the drive device of the present invention, since the motor case formed of a non-metallic molding material and the ECU cover formed of a resin material cover the inside of the motor portion and the ECU, the corrosion resistance is improved. Further, since the non-metallic molding material is generally a resin-based composite material and has a smaller specific gravity than metal, the weight of the motor portion is reduced. Furthermore, since the stator molding portion that molds the stator is integrally formed with the cylindrical portion of the motor case from a non-metallic molding material, the rigidity of the stator is increased and vibration is suppressed.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0016] A plurality of embodiments of the drive device according to the present invention will be described with reference to the drawings. The same reference numerals are given to substantially the same configurations in the plurality of embodiments, and the description thereof is omitted. The "present embodiment" includes the first to fourth embodiments. The drive device of the present embodiment is applied, for example, as a steering assist motor of an electric power steering device, and is integrally configured with a motor portion and an ECU that controls the drive of the motor portion.

[0017] Referring to FIG. 1, the schematic configuration of the electric power steering device 99 will be described. A rack assist type electric power steering device is exemplified, but the drive device 10 of the present embodiment can be similarly applied to a column assist type electric power steering device. The steering system 90 including the electric power steering device 99 includes a steering wheel 91, a steering shaft 92, a pinion gear 96, a rack shaft 97, wheels 98, and the electric power steering device 99, etc.

[0018] A torque sensor 93 for detecting the steering torque is provided on the steering shaft 92 to which the steering wheel 91 is connected. A pinion gear 96 that meshes with the rack shaft 97 is provided at the tip of the steering shaft 92. When the driver rotates the steering wheel 91, the rotational motion of the steering shaft 92 is converted into a linear motion of the rack shaft 97 by the pinion gear 96. A pair of wheels 98 connected to both ends of the rack shaft 97 are steered at an angle corresponding to the displacement amount of the rack shaft 97.

[0019] The electric power steering device 99 includes a drive device 10 and a gearbox 80, etc. The drive device 10 has a so-called "mechatronic" configuration in which a motor unit 50 and an ECU 60 that controls the drive of the motor unit 50 are integrally formed. The motor unit 50 is fixed to the end face of the gearbox 80 with bolts using a mounting hole 285 (see FIG. 3) provided in the flange portion 28. The gearbox 80 houses a reduction gear that reduces the rotation of the motor unit 50 and transmits it to the rack shaft 97.

[0020] The drive device 10 of the present embodiment, similar to the device described in Patent Document 1, has a motor unit 50 that is a two-system three-phase brushless motor having two sets of three-phase windings. The ECU 60 supplies power to the two sets of three-phase windings through two-system inverter circuits. DC power is supplied to the connector 74 of the ECU 60 from a battery, and communication signals with a vehicle communication network (CAN) are input and output. Also, a sensor signal is input from the torque sensor 93. By supplying three-phase AC power converted from DC power by the inverter circuit of the ECU 60, the motor unit 50 outputs a steering assist torque.

[0021] Incidentally, as described in paragraph

[0020] of Patent Document 1, in a rack assist type electric power steering device, there is a situation where moisture such as rainwater and dew condensation easily enters the drive device, and particularly waterproof performance is required. Therefore, the space between the motor case and the ECU cover is sealed with an adhesive. However, if the metal motor case is exposed, there is a risk that the sealing performance may deteriorate due to corrosion of the metal caused by contact with moisture (including salt water). Also, if the motor case is made of metal, the weight of the motor unit increases. Furthermore, there is a problem that the stator fixed to the motor case is likely to receive vibrations of the motor.

[0022] Therefore, in order to improve corrosion resistance and reduce weight, in the drive device 10 of the present embodiment, all exposed portions covering the interiors of the motor unit 50 and the ECU 60 are formed of a non-metallic material. Also, in order to suppress vibrations, the stator is molded with a non-metallic molding material, and the stator molding portion that molds the stator is integrally molded with the motor case. Subsequently, the configuration of the drive device 10 of each embodiment will be described in order. The reference numerals of the drive devices of the first to fourth embodiments are assigned the embodiment number in the third digit following "10".

[0023] (First Embodiment) Referring to FIGS. 2 and 3, the drive device 101 of the first embodiment will be described. In FIG. 2, the direction parallel to the rotation axis O of the motor unit 50 is defined as the "axial direction", and the direction orthogonal to the axial direction is defined as the "radial direction". The stator 53, the rotor 54, and the shaft 55 are coaxially arranged with the rotation axis O. In the motor unit 50, the rotor 54 disposed inside the stator 53 in the radial direction rotates integrally with the shaft 55. The ECU 60 is provided on one side in the axial direction of the motor unit 50. The side opposite to the ECU 60 with respect to the motor unit 50 is defined as the "front side", and the side of the ECU 60 with respect to the motor unit 50 is defined as the "rear side".

[0024] The stator 53 has motor windings 51 wound around an annular stator core. The lead wires 52 of the motor windings 51 are connected to the substrate 65 of the ECU 60. By controlling the energization of the motor windings 51 by the ECU 60, a rotating magnetic field is formed in the stator 53. The rotor 54 is provided with a plurality of permanent magnets 545 along the outer periphery of the rotor core. The rotor 54 rotates about the shaft 55 due to the rotating magnetic field formed in the stator 53.

[0025] The shaft 55 is fixed to the center of the rotor 54. The front bearing 56 rotatably supports the shaft 55 on the front side of the motor unit 50. The rear bearing 57 rotatably supports the shaft 55 on the rear side of the motor unit 50. A wave washer 58 is interposed on the seating surface of the rear bearing 57.

[0026] The drive device 101 of the first embodiment includes a motor case 201, a rear frame 40, and an ECU cover 70. The motor case 201 is formed of a non-metallic molding material, and the cylindrical portion 22, the front bottom portion 23, and the motor flange portion 28 are integrally formed. The cylindrical portion 22 extends in the axial direction of the motor unit 50 outside the stator 53 in the radial direction. The front bottom portion 23 forms the bottom on the front side of the motor unit 50 and holds the front bearing 56. Specifically, a metal holding collar 236 into which the front bearing 56 is press-fitted is insert-molded at the center of the front bottom portion 23.

[0027] As shown in FIG. 3, the motor flange portion 28 is provided so as to project outward in the radial direction at two locations in the circumferential direction that are opposite to each other with the rotation axis O interposed therebetween. A metal fastening collar 286 having a mounting hole 285 is insert-molded in the motor flange portion 28. By fastening a bolt through the mounting hole 285 to the screw hole of the gearbox 80, the drive device 101 is fixed to the gearbox 80.

[0028] The motor case 201 of the first embodiment has a bottomed cylindrical shape with an open rear side. Therefore, for example, the parting line of the molding die is set near the opening surface on the rear side, and a space up to the front bottom 23 is formed by a core protruding from the parting line.

[0029] As the "non-metallic molding material" which is the material of the motor case 201, preferably, a carbon fiber composite material (CFRP) or a resin material with a glass fiber (GF) blending ratio of 35% or more is used. Therefore, the strength of the motor case 201 forming the outer shell of the motor portion 50 is enhanced.

[0030] The stator 53 is molded with a non-metallic molding material (that is, a resin-based material). The non-metallic material portion molding the stator 53 is referred to as a stator mold portion 25. The stator mold portion 25 is integrally molded with the cylindrical portion 22 of the motor case 201. In FIG. 2, the motor case 201 and the stator mold portion 25 are provided with a common resin hatching, and a broken line is drawn at the boundary surface. This broken line illustration suggests that although the boundary surface is melted and merged in the appearance of the finished product and the motor case 201 and the stator mold portion 25 cannot be distinguished, there is a possibility that the two are manufactured in different processes during the manufacturing process. Specifically, the following two manufacturing methods are possible.

[0031] [1] The stator 53 is inserted into the mold, and the motor case 201 and the stator mold part 25 are simultaneously molded in one step. In this case, the stator mold part 25 is made of the same material as the motor case 201 and is integrally molded with the cylindrical part 22 of the motor case 201. That is, it can be simply expressed as "The stator 53 is integrally molded with the cylindrical part 22 of the motor case 201." With this configuration, the mold structure can be made relatively simple, and it can be molded with a general injection molding machine.

[0032] [2] First, the stator 53 is molded with a primary molding material in a primary molding mold. Next, the semi-finished product after primary molding, which consists of the stator 53 and the stator mold part 25, is inserted into a secondary molding mold and molded with a secondary molding material integrally with the cylindrical part 22 of the motor case 201. In this case, the primary molding material and the secondary molding material may be the same material or different materials. However, if the same material is used, the method of [1] can be adopted, and there is no merit in deliberately adopting the time-consuming method of [2]. Therefore, when the method of [2] is adopted, it is substantially expressed as "The stator mold part 25 is made of a material different from that of the motor case 201 and is integrally molded with the cylindrical part 22 of the motor case 201."

[0033] With this configuration, two molds, a primary molding mold and a secondary molding mold, are used, and it is necessary to use a special molding machine such as a multi-color molding machine. However, different materials can be properly selected according to their respective characteristics, such that the motor case 201 uses a high-strength material, and the stator mold part 25 uses a material that is advantageous for heat generation suppression, magnetic transmission, cost reduction, etc.

[0034] In addition, to investigate whether the material of the stator mold part 25 and the material of the motor case 201 are the same or different for the finished product of the drive device, for example, the product can be cut to cut out samples of each part and chemical analysis can be performed for determination.

[0035] The rear frame 40 is a separate component from the motor case 201 and is formed of a metal such as an aluminum alloy. The rear frame 40 is fixed to the motor case 201 by fitting the fitting outer wall 42 into the fitting inner wall 222 of the cylindrical portion 22 of the motor case 201. The rear frame 40 holds the rear bearing 57 and also supports the substrate 65 of the ECU 60. The heat generated by the electronic element 66 (mainly the switching element of the inverter circuit) mounted on the substrate 65 is dissipated to the rear frame 40. That is, the rear frame 40 functions as a heat sink.

[0036] The ECU cover 70 is formed of a resin material such as PBT, which is different from the material of the motor case 201. The ECU cover 70 is formed in a container shape having a top plate 71 and side plates 72, and covers the substrate 65 of the ECU 60. Since the ECU cover 70 is not required to have the same strength as the motor case 201, by using a resin material that does not contain carbon fiber or glass fiber, wear of the mold can be suppressed and the mold life can be extended.

[0037] On the top plate 71, a connector 74 whose width faces the side opposite to the motor part 50 is integrally formed. The connector 74 is connected to the substrate 65 via a connector terminal 67. In the example shown in FIG. 3, a vehicle system connector 74p having a power supply terminal and a CAN communication terminal and a signal system connector 74s having a sensor signal terminal are provided. However, the number of widths and the arrangement of the connectors 74 are not limited to this example. For example, in a drive device in which power and signals are redundantly input, two sets of vehicle system connectors and signal system connectors may be provided. Also, a configuration in which the directions of the connectors are different will be described later as a fourth embodiment.

[0038] The end portion 721 of the side plate 72 of the ECU cover 70 is joined to the end portion 221 of the cylindrical portion 22 of the motor case 201 with an adhesive S. Although the detailed shape of the portion filled with the adhesive S is not shown, as disclosed in Patent Document 1, an adhesive groove may be formed. Thereby, the space between the ECU cover 70 and the motor case 201 is sealed, and intrusion of rainwater or the like is prevented.

[0039] As described above, in the drive device 101 of the first embodiment, the motor case 201 formed of a non-metallic molding material and the ECU cover 70 formed of a resin material cover the inside of the motor unit 50 and the ECU 60, thereby improving the corrosion resistance. In addition, since the non-metallic molding material is generally a resin-based composite material and has a smaller specific gravity than metal, the weight of the motor unit 50 is reduced.

[0040] Furthermore, since the stator mold part 25 that molds the stator 53 is integrally formed with the cylindrical part 22 of the motor case 201 from a non-metallic molding material, the rigidity of the stator 53 is increased and vibration is suppressed. In addition, since the stator 53 and the motor case 201 are integrated into one part, the number of parts in the assembly process is reduced.

[0041] Next, referring to FIGS. 4 to 6, the second to fourth embodiments, which are partially different in configuration from the first embodiment, will be described in order. In any of the embodiments, the motor cases 201 and 202 are formed of a non-metallic molding material, specifically, a carbon fiber composite material or a resin material in which the blending ratio of glass fiber is 35% or more. The ECU covers 70 and 704 are formed of a resin material different from the motor cases 201 and 202.

[0042] The stator 53 is molded with the same or different "non-metallic molding material" as the motor cases 201 and 202. The stator mold part 25 that molds the stator 53 is integrally formed with the cylindrical part 22 of the motor cases 201 and 202.

[0043] The basic operational effects of this configuration are the same as those of the first embodiment. That is, the drive device of each embodiment has improved corrosion resistance and the weight of the motor unit 50 is reduced. In addition, the vibration of the stator 53 is suppressed. Hereinafter, mainly the differences in other configurations and operational effects will be described.

[0044] (Second Embodiment) Referring to FIG. 4, the drive device 102 of the second embodiment will be described. In the second embodiment, the configurations of the motor case and the frame that constitute the housing of the motor unit 50 are different from those of the drive device 101 of the first embodiment. The motor case 202 of the drive device 102 has a cylindrical portion 22, a rear bottom portion 24, and a motor flange portion 28 integrally formed. The ECU cover 70 is the same as that of the first embodiment.

[0045] The rear bottom portion 24 holds the rear bearing 57 instead of the rear frame 40 of the first embodiment and supports the substrate 65. A metal holding collar 246 into which the rear bearing 57 is press-fitted is insert-molded at the central portion of the rear bottom portion 24.

[0046] The motor case 202 of the second embodiment has a bottomed cylindrical shape with an open front side. Therefore, for example, the parting line of the molding die is set near the opening surface on the front side, and a space up to the rear bottom portion 24 is formed by a core protruding from the parting line.

[0047] The drive device 102 also includes a front frame 30. The front frame 30 is a separate part from the motor case 202 and holds the front bearing 56. The front frame 30 is formed of a non-metallic material like the motor case 202, and the outer peripheral wall fits inside the motor flange portion 28 of the motor case 202. A metal holding collar 36 into which the front bearing 56 is press-fitted is insert-molded at the central portion of the front frame 30.

[0048] Since the front frame 30 is also formed of a non-metallic material in addition to the motor case 202, the effect of improving the corrosion resistance of the motor unit 50 is maintained. Further, in the second embodiment, since the motor case 202 and the rear bottom portion 24 have an integral structure, the strength in the rear direction can be ensured in an environment where the stress in the rear direction is high.

[0049] (Third Embodiment) Referring to FIG. 5, the drive device 103 of the third embodiment will be described. The drive device 103 includes a metal plate 64 between the substrate 65 of the ECU 60 and the rear bottom 24 in addition to the configuration of the drive device 102 of the second embodiment. The metal plate 64 is formed of an aluminum alloy or the like. Heat generated by the electronic element 66 (mainly the switching element of the inverter circuit) mounted on the substrate 65 is dissipated to the metal plate 64. That is, the metal plate 64 functions as a heat sink in the same manner as the rear frame 40 of the first embodiment. Further, the metal plate 64 supports the substrate 65.

[0050] By dissipating the heat of the electronic element 66 to the metal plate 64 provided between the substrate 65 and the non-metallic rear bottom 24, it is possible to prevent a decrease in function or a failure due to a temperature rise of the ECU 60 during motor driving.

[0051] (Fourth Embodiment) Referring to FIG. 6, the drive device 104 of the fourth embodiment will be described. The drive device 104 has the same configuration of the motor unit 50 as that of the drive device 101 of the first embodiment, and the shape of the ECU cover is different in relation to the arrangement of the connector 74. The ECU cover 704 of the drive device 104 is formed so as to protrude in one direction in the radial direction of the motor unit 50. A connector 74 that opens from the protruding portion toward the front side (downward in the figure) is provided.

[0052] The ECU cover 704 includes an upper cover 71 including a top plate 71 and side plates 72, and a lower cover 77 at the protruding portion, which are formed separately and joined with an adhesive. As shown by a broken line for the boundary portion in FIG. 6, the lower cover 77 and the motor case 201 may be formed separately or integrally. By forming them integrally, the number of parts can be reduced. Note that, similarly to the drive devices 102 and 103 of the second and third embodiments, an ECU cover 704 protruding in one direction in the radial direction of the motor unit 50 may be applied.

[0053] (Other Embodiments) (a) In the above embodiment, the motor flange portion 28 for attaching the drive device 10 to the end face of the gearbox 80 is integrally formed on the motor cases 201 and 202. However, the object to which the drive device 10 is attached is not limited to the gearbox 80, and the attachment method is not necessarily the flange method. In a configuration that does not use a flange, the motor flange portion may not be formed on the motor case.

[0054] (b) The configurations of the substrate 65 and the connector 74 of the ECU 60 are not limited to the configurations exemplified in the above embodiment. For example, a plurality of substrates may be stacked and arranged.

[0055] (c) The drive device 10 of the present invention is not limited to the steering assist motor of the electric power steering device, and may also be used as a drive device for a reaction force motor or a steering motor of a steer-by-wire system, or any other motor.

[0056] As described above, the present invention is not limited to the above embodiment, and can be implemented in various forms without departing from the spirit thereof.

Explanation of Reference Numerals

[0057] 10(101 - 104) ··· Drive device, 201, 202 ··· Motor cases, 22 ··· Cylindrical portion, 23 ··· Front bottom portion, 24 ··· Rear bottom portion, 25 ··· Stator mold portion, 30 ··· Front frame, 40 ··· Rear frame, 50 ··· Motor portion, 53 ··· Stator, 54 ··· Rotor, 55 ··· Shaft, 56 ··· Front bearing, 57 ··· Rear bearing, 60 ··· ECU, 65 ··· Substrate, 70, 704 ··· ECU cover, 72 ··· Side plate.

Claims

1. A drive device in which a rotor (54) disposed radially inside an annular stator (53) rotates integrally with a shaft (55), and an ECU (60) provided on one axial side of the motor unit and controlling the drive of the motor unit are integrally configured, wherein when the side opposite to the ECU with respect to the motor unit is defined as the front side and the ECU side with respect to the motor unit is defined as the rear side, a motor case (201) formed of a non-metallic molding material and integrally formed with a cylindrical portion (22) extending in the axial direction of the motor unit and a front bottom portion (23) holding a front bearing (56) that supports the shaft on the front side of the motor unit, a rear frame (40) which is a separate component from the motor case and holds a rear bearing (57) that supports the shaft on the rear side of the motor unit, an ECU cover (70, 704) formed in a container shape to cover the substrate (65) of the ECU with a resin material, and an end portion of a side plate (72) is joined to an end portion of the cylindrical portion of the motor case, comprising the stator is molded with a non-metallic molding material, and a stator molding portion (25) that molds the stator is integrally molded with the cylindrical portion of the motor case. The drive device.

2. A drive device in which a rotor (54) disposed radially inside an annular stator (53) rotates integrally with a shaft (55), and an ECU (60) provided on one axial side of the motor unit and controlling the drive of the motor unit are integrally configured, wherein when the side opposite to the ECU with respect to the motor unit is defined as the front side and the ECU side with respect to the motor unit is defined as the rear side, a motor case (202) formed of a non-metallic molding material and integrally formed with a cylindrical portion (22) extending in the axial direction of the motor unit and a rear bottom portion (24) holding a rear bearing (57) that supports the shaft on the rear side of the motor unit, a front frame (30) which is a separate component from the motor case and holds a front bearing (56) that supports the shaft on the front side of the motor unit, an ECU cover (70, 704) formed in a container shape to cover the substrate (65) of the ECU with a resin material, and an end portion of a side plate (72) is joined to an end portion of the cylindrical portion of the motor case, comprising the stator is molded with a non-metallic molding material, and The stator molding part (25) that molds the stator is a drive device integrally formed with the cylindrical part of the motor case.

3. The drive device according to claim 2, further comprising a metal plate (64) provided between the substrate of the ECU and the rear bottom of the motor case, and dissipating heat generated by the electronic element (66) mounted on the substrate.

4. The motor case is formed of a carbon fiber composite material or a resin material having a glass fiber blending ratio of 35% or more. The drive device according to any one of claims 1 to 3, wherein the ECU cover is formed of a resin material different from the material of the motor case.

5. The drive device according to claim 4, wherein the stator molding part is made of the same material as the motor case and is integrally formed with the cylindrical part of the motor case.

6. The drive device according to claim 4, wherein the stator molding part is made of a material different from the motor case and is integrally formed with the cylindrical part of the motor case.

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