drive device

Abstract

In a drive device (101, 104) in which a motor portion (50) and an ECU (60) are integrally configured, a motor housing (201) is formed of a non-metallic molding material, and a cylindrical portion (22) extending in the axial direction of the motor portion (50) is integrally formed with a front bottom portion (23) of a front bearing (56) held to a front support shaft (55) of the motor portion (50). A rear frame (40) is a separate member from the motor housing (201), and holds a rear bearing (57) of a rear support shaft (55) of the motor portion (50). An ECU cover (70, 704) is formed of a resin material in a container shape covering a substrate (65) of the ECU (60), and an end portion of a side plate (72) is engaged with an end portion of the cylindrical portion (22) of the motor housing (201). A stator (53) is molded of a non-metallic molding material. A stator molding portion (25) molding the stator (53) is integrally formed with the cylindrical portion (22) of the motor housing (201).

Description

[0001] Cross-referencing of related applications

[0002] This application is based on Japanese Application No. 2024-002979, filed on January 12, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a drive device. Background Technology

[0004] Previously, a drive device was known in which an ECU (control unit) was integrally mounted on one axial end of the motor section. In, for example, the drive device disclosed in Patent Document 1, a stator was fixed inside the cylindrical portion of a metal motor housing. The cylindrical portion of the motor housing and the resin ECU cover were sealed with adhesive.

[0005] Prior technology documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-072996 Summary of the Invention

[0008] In the drive device of Patent Document 1, because the motor housing is made of metal, there is a concern that the exposed metal may corrode upon contact with moisture in the air or rainwater containing salt water, leading to a deterioration in the seal at the joint between the motor housing and the ECU cover. Furthermore, if the motor housing is metal, the weight of the motor unit increases. Additionally, there is a problem that the stator, which is fixed to the motor housing, is susceptible to vibration from the motor.

[0009] The purpose of this disclosure is to provide a drive device that improves corrosion resistance, reduces weight, and suppresses vibration.

[0010] The drive unit disclosed herein integrates a motor unit and an ECU. The rotor of the motor unit, which is located radially inside the annular stator, rotates integrally with the shaft. The ECU is located on one side of the motor unit along its axial direction and controls the drive of the motor unit.

[0011] The drive unit of the first embodiment includes a motor housing, a rear frame, and an ECU cover. The drive unit of the second embodiment includes a motor housing, a front frame, and an ECU cover.

[0012] The motor housing is formed from a non-metallic molding material. Preferably, the motor housing is formed from a resin material in which carbon fiber reinforced polymer (CFRP) or glass fiber (GF) accounts for more than 35%.

[0013] In the first embodiment, the motor housing is integrally formed with a cylindrical portion and a front bottom portion, the cylindrical portion extending axially along the motor portion, the front bottom portion holding a front bearing, and the front bearing supporting a shaft on the front side of the motor portion. In the second embodiment, the motor housing is integrally formed with a cylindrical portion and a rear bottom portion, the cylindrical portion extending axially along the motor portion, the rear bottom portion holding a rear bearing, and the rear bearing supporting a shaft on the rear side of the motor portion.

[0014] In the first embodiment, the rear frame is a component distinct from the motor housing and houses the rear bearing, which supports the shaft on the rear side of the motor section. In the second embodiment, the front frame is a component distinct from the motor housing and houses the front bearing, which supports the shaft on the front side of the motor section.

[0015] In both the first and second embodiments, the ECU cover is formed from a resin material into a container shape covering the substrate of the ECU, and the end of the side plate of the ECU cover is joined to the end of the cylindrical portion of the motor housing. Preferably, the ECU cover and the motor housing are formed from different resin materials.

[0016] In both the first and second embodiments, the stator is molded from a non-metallic molding material. Furthermore, the stator molding portion is integrally formed with the cylindrical portion of the motor housing.

[0017] In the drive unit disclosed herein, corrosion resistance is improved because the motor housing, formed of a non-metallic molding material, and the ECU cover, formed of a resin material, cover the motor section and the interior of the ECU. Furthermore, the non-metallic molding material is generally a resin-based composite material, which, because it has a lower specific gravity than metal, achieves weight reduction in the motor section. Moreover, since the stator molding section of the stator is integrally formed with the cylindrical portion of the motor housing using a non-metallic molding material, the rigidity of the stator is increased, and vibration is suppressed. Attached Figure Description

[0018] Regarding the foregoing purposes and other purposes, features or advantages of this disclosure, please refer to the appendix. Figure 1 The following detailed description makes this clearer. An attached diagram is shown below:

[0019] Figure 1 This is an overall structural diagram of the electric power steering system applicable to the drive unit.

[0020] Figure 2 This is a schematic cross-sectional view of the drive device according to the first embodiment.

[0021] Figure 3 yes Figure 2 View in direction III,

[0022] Figure 4 This is a schematic cross-sectional view of the drive device according to the second embodiment.

[0023] Figure 5 This is a schematic cross-sectional view of the drive device according to the third embodiment.

[0024] Figure 6 This is a schematic cross-sectional view of the drive device according to the fourth embodiment. Detailed Implementation

[0025] Several embodiments of the drive device according to this disclosure are described based on the accompanying drawings. In the various embodiments, substantially the same structures are given the same reference numerals and descriptions are omitted. The first to fourth embodiments are collectively referred to as "this embodiment". The drive device of this embodiment is used, for example, as a steering assist motor of an electric power steering system, and the motor unit and the ECU that controls the drive of the motor unit are integrally constructed.

[0026] Reference Figure 1 The general structure of the electric power steering device 99 is explained below. Although a rack-assisted electric power steering device is exemplified, the drive unit 10 of this embodiment can also be applied to a column-assisted 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 96, a rack shaft 97, wheels 98, and the electric power steering device 99.

[0027] A torque sensor 93 for detecting steering torque is installed on the steering shaft 92, which is connected to the steering wheel 91. A pinion 96 that meshes with the rack shaft 97 is located at the front end of the steering shaft 92. When the driver rotates the steering wheel 91, the rotational motion of the steering shaft 92 is converted into linear motion of the rack shaft 97 by the pinion 96. The pair of wheels 98 connected to both ends of the rack shaft 97 are steered at an angle corresponding to the displacement of the rack shaft 97.

[0028] The electric power steering system 99 includes a drive unit 10 and a gearbox 80. The drive unit 10 is a so-called "mechatronic" structure, where the motor unit 501 and the ECU 60 that controls the drive of the motor unit 50 are integrally formed. The motor unit 50 uses mounting holes 285 provided in the motor flange portion 28 (see reference). Figure 3 It is fixed to the end face of the gearbox 80 by bolts. The gearbox 80 houses a reduction gear that reduces the rotation of the motor 50 and transmits it to the rack shaft 97.

[0029] In the drive unit 10 of this embodiment, the motor unit 50 is a dual-system three-phase brushless motor with two sets of three-phase windings. The ECU 60 supplies power to the two sets of three-phase windings via a dual-system inverter circuit. DC power is supplied from the battery to the connector 74 of the ECU 60, and communication signals with the Vehicle Communication Network (CAN) are input and output relative to the connector 74 of the ECU 60. In addition, sensor signals are 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 steering assist torque.

[0030] However, in rack-and-pinion-assisted electric power steering systems, moisture such as rainwater and condensation can easily penetrate the drive mechanism, making waterproofing particularly important. Therefore, the motor housing and ECU cover are sealed with adhesive. However, if the metal motor housing is exposed, there is a concern that the seal may deteriorate due to corrosion caused by contact with moisture (including salt water). Furthermore, if the motor housing is metal, the weight of the motor unit increases. Additionally, the stator, which is fixed to the motor housing, is susceptible to vibration from the motor.

[0031] Therefore, in order to improve corrosion resistance and reduce weight, all exposed portions of the drive device 10 covering the interior of the motor section 50 and the ECU 60 in this embodiment are made of non-metallic material. Furthermore, in order to suppress vibration, the stator is molded from a non-metallic molding material, and the stator molding portion of the stator is integrally formed with the motor housing. The structure of the drive device 10 in each embodiment will now be described sequentially. The symbol for the drive device in the first to fourth embodiments is indicated by the embodiment number following the third digit of "10".

[0032] (First Implementation)

[0033] Reference Figure 2 , Figure 3 The driving device 101 of the first embodiment will be described. Figure 2 In this design, 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, rotor 54, and shaft 55 are arranged coaxially with the rotation axis O. The rotor 54, which is located radially inside the annular stator 53 of the motor unit 50, rotates integrally with the shaft 55. The ECU 60 is located on one side of the axial direction of the motor unit 50. The side opposite to the ECU 60 relative to the motor unit 50 is defined as the "front side," and the side opposite to the ECU 60 is defined as the "rear side."

[0034] The stator 53 has a motor winding 51 wound around a ring-shaped stator core. The leads 52 of the motor winding 51 are connected to the base plate 65 of the ECU 60. By controlling the energization of the motor winding 51 by the ECU 60, a rotating magnetic field is formed in the stator 53. The rotor 54 has a plurality of permanent magnets 545 arranged along the outer periphery of the rotor core. The rotor 54 rotates about the axis 55 by the rotating magnetic field formed in the stator 53.

[0035] Shaft 55 is fixed to the center of rotor 54. Front bearing 56 supports shaft 55 at the front of motor unit 50, enabling it to rotate. Rear bearing 57 supports shaft 55 at the rear of motor unit 50, enabling it to rotate. Wave-shaped washer 58 is clamped in the seat surface of rear bearing 57.

[0036] The drive unit 101 of the first embodiment includes a motor housing 201, a rear frame 40, and an ECU cover 70. The motor housing 201 is formed of a non-metallic molded material, and a cylindrical portion 22, a front bottom portion 23, and a motor flange portion 28 are integrally formed. The cylindrical portion 22 extends radially outward from the stator 53 along the axial direction of the motor portion 50. The front bottom portion 23 forms the bottom of the front side of the motor portion 50 and holds the front bearing 56. Specifically, a metal retaining ring 236 is inserted into the center of the front bottom portion 23, and the retaining ring 236 is pressed into the front bearing 56.

[0037] like Figure 3 As shown, the motor flange 28 is configured to protrude radially outward at two circumferentially opposite locations sandwiching the rotating shaft O. A metal fastening ring 286 with a mounting hole 285 is embedded in the motor flange 28. The drive unit 101 is fixed to the gearbox 80 by fastening a bolt through the mounting hole 285 and into the threaded hole of the gearbox 80.

[0038] In the first embodiment, the motor housing 201 is a bottomed cylindrical shape with an opening at the rear. Therefore, for example, the parting line of the molding die is set near the opening surface at the rear, and a space to the front bottom 23 is formed by using a core protruding from the parting line.

[0039] As the material for the motor housing 201, i.e., the "non-metallic molding material," it is preferable to use a resin material with a carbon fiber reinforced polymer (CFRP) or glass fiber (GF) content of 35% or more. Therefore, the strength of the motor housing 201, which forms the outer shell of the motor section 50, is enhanced.

[0040] The stator 53 is molded from a non-metallic molding material (i.e., a resin-based material). The non-metallic material portion used to mold the stator 53 is designated as the stator molding portion 25. The stator molding portion 25 is integrally molded with the cylindrical portion 22 of the motor housing 201. Figure 2In the diagram, the motor housing 201 and the stator molding portion 25 are marked with a common resin cross-sectional line, and the boundary surface is marked with a dashed line. In the finished product, the boundary surfaces merge, making it impossible to distinguish between the motor housing 201 and the stator molding portion 25. However, the dashed line illustration suggests that they may have been manufactured through different processes. Specifically, the following two manufacturing methods can be used.

[0041] [1] The motor housing 201 and the stator molding portion 25 are formed simultaneously in one process using a mold with the stator 53 inserted. In this case, the stator molding portion 25 is integrally formed with the cylindrical portion 22 of the motor housing 201 using the same material as the motor housing 201. That is, it can be simply described as "the stator 53 and the cylindrical portion 22 of the motor housing 201 are integrally molded". With this structure, the mold structure can be relatively simple, and it can be formed using a general injection molding machine.

[0042] [2] First, the stator 53 is molded in a primary molding mold using a primary molding material. Next, the semi-finished insert, consisting of the stator 53 and the stator molding part 25, is placed into a secondary molding mold and integrally molded with the cylindrical part 22 of the motor housing 201 using a secondary molding material. In this case, the primary molding material and the secondary molding material can be the same material or different materials. However, the method of [1] can be used when the same material is used, and the more labor-intensive method of [2] has no advantage. Therefore, when the method of [2] is used, it is essentially that "the stator molding part 25 is integrally molded with the cylindrical part 22 of the motor housing 201 using a material different from that of the motor housing 201."

[0043] In this structure, two molds are required: a primary forming mold and a secondary forming mold, and a special forming machine such as a multi-color forming machine is used. However, as can be done by using a high-strength material for the motor housing 201 and a material that is advantageous for heat suppression, magnetic transmission, and cost reduction for the stator molding part 25, materials corresponding to their respective characteristics can be used separately.

[0044] In addition, regarding the finished product of the drive unit, in order to investigate whether the material of the stator molding part 25 is the same as or different from the material of the motor housing 201, for example, the product can be cut and samples of each part can be cut out for chemical analysis and determination.

[0045] The rear frame 40 is a component distinct from the motor housing 201 and is made of a metal such as aluminum alloy. The rear frame 40 is fixed to the motor housing 201 by fitting its outer wall 42 into the inner wall 222 of the cylindrical portion 22 of the motor housing 201. The rear frame 40 holds the rear bearing 57 and supports the base plate 65 of the ECU 60. Heat generated by the electronic components 66 (primarily switching elements of the inverter circuit) mounted on the base plate 65 is dissipated to the rear frame 40. In other words, the rear frame 40 functions as a heat sink.

[0046] The ECU cover 70 is formed of a resin material such as PBT, which is different from the material of the motor housing 201. The ECU cover 70 is formed in the shape of a container with a top plate 71 and a side plate 72, covering the substrate 65 of the ECU 60. Since the ECU cover 70 is not required to have the same strength as the motor housing 201, by using a resin material that does not contain carbon fiber and glass fiber, mold wear can be suppressed and mold life can be extended.

[0047] A connector 74 is integrally formed on the top plate 71, with its interface facing the side opposite to the motor section 50. The connector 74 is connected to the base plate 65 via connector terminals 67. Figure 3 In the example shown, a vehicle system connector 74p with power supply terminals and CAN communication terminals, and a signal system connector 74s with sensor signal terminals are provided. However, the number and configuration of the connector 74 interfaces are not limited to this example. For example, in a drive unit that redundantly inputs power and signals, two sets of vehicle system connectors and two sets of signal system connectors may each be provided. Furthermore, structures with different connector orientations will be described later as a fourth embodiment.

[0048] The end 721 of the side plate 72 of the ECU cover 70 is joined to the end 221 of the cylindrical portion 22 of the motor housing 201 by an adhesive S. Furthermore, although the detailed shape of the portion filled with adhesive S is not shown in the figure, an adhesive groove may be formed. Thus, the ECU cover 70 and the motor housing 201 are sealed, preventing the intrusion of rainwater, etc.

[0049] In the drive unit 101 of the first embodiment as described above, the interiors of the motor section 50 and ECU 60 are covered by a motor housing 201 made of a non-metallic molding material and an ECU cover 70 made of a resin material, thus improving corrosion resistance. Furthermore, the non-metallic molding material is generally a resin-based composite material, which has a lower specific gravity than metal, thus achieving weight reduction in the motor section 50.

[0050] Furthermore, because the stator molding portion 25 of the stator 53 is integrally formed with the cylindrical portion 22 of the motor housing 201 using 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 housing 201 are integrated into one component, the number of parts in the assembly process is reduced.

[0051] Next refer to Figures 4-6 The second to fourth embodiments, which differ in some structural features from the first embodiment, will be described sequentially. In any embodiment, the motor housings 201 and 202 are formed of a non-metallic molding material, specifically a carbon fiber composite material, or a resin material with a glass fiber content of 35% or more. The ECU covers 70 and 704 are formed of a resin material different from that of the motor housings 201 and 202.

[0052] The stator 53 is molded from a non-metallic molding material that is the same as or different from the motor housings 201 and 202. The stator molding part 25 of the stator 53 is integrally formed with the cylindrical part 22 of the motor housings 201 and 202.

[0053] The basic effects of this structure are the same as those of the first embodiment. That is, the corrosion resistance of the drive unit in each embodiment is improved, and the motor section 50 is lightweight. Furthermore, the vibration of the stator 53 is suppressed. Hereinafter, we will mainly explain the differences in structure and effects other than these.

[0054] (Second Implementation)

[0055] Reference Figure 4 The drive device 102 of the second embodiment will now be described. In the second embodiment, the motor housing constituting the frame of the motor section 50 differs in structure from the drive device 101 of the first embodiment. The motor housing 202 of the drive device 102 integrally forms a cylindrical portion 22, a rear bottom portion 24, and a motor flange portion 28. The ECU cover 70 is the same as in the first embodiment.

[0056] Instead of the rear frame 40 in the first embodiment, the rear bottom 24 holds the rear bearing 57 and supports the base plate 65. A metal retaining ring 246 is inserted into the center of the rear bottom 24, and the rear bearing 57 is pressed into the retaining ring 246.

[0057] In the second embodiment, the motor housing 202 is a bottomed cylindrical shape with an opening at the front. Therefore, for example, the parting line of the forming mold is set near the opening surface at the front, and a space to the rear bottom 24 is formed by using a core protruding from the parting line.

[0058] Additionally, the drive unit 102 includes a front frame 30. The front frame 30 is a separate component from the motor housing 202 and houses the front bearing 56. The front frame 30, like the motor housing 202, is made of a non-metallic material, and its outer peripheral wall fits into the inner side of the motor flange 28 of the motor housing 202. At the center of the front frame 30, a metal retaining ring 36 is formed as an insert, and the front bearing 56 is pressed into this retaining ring 36.

[0059] In addition to the motor housing 202, the front frame 30 is also made of a non-metallic material, thus maintaining the improved corrosion resistance of the motor section 50. Furthermore, in the second embodiment, the motor housing 202 and the rear bottom 24 are integrated into a single structure, thus ensuring rearward strength even under high rearward stress conditions.

[0060] (Third Implementation)

[0061] Reference Figure 5 The drive unit 103 of the third embodiment will now be described. In addition to the structure of the drive unit 102 of the second embodiment, the drive unit 103 also includes a metal plate 64 between the base plate 65 and the rear bottom 24 of the ECU 60. The metal plate 64 is made of aluminum alloy or the like. Heat generated by the electronic components 66 (mainly switching elements of the inverter circuit) mounted on the base plate 65 is dissipated to the metal plate 64. That is, the metal plate 64 functions as a heat sink, similar to the rear frame 40 of the first embodiment. Furthermore, the metal plate 64 supports the base plate 65.

[0062] By directing the heat of the electronic component 66 to the metal plate 64 located between the substrate 65 and the non-metallic rear bottom 24, it is possible to prevent the function reduction and malfunction caused by the temperature rise of the ECU 60 during motor drive.

[0063] (Fourth Implementation)

[0064] Reference Figure 6 The drive device 104 according to the fourth embodiment will now be described. Compared to the drive device 101 of the first embodiment, the structure of the motor section 50 of the drive device 104 is the same, but the shape of the ECU cover and the configuration of the connector 74 are different. The ECU cover 704 of the drive device 104 is formed to protrude radially toward the motor section 50. A connector 74 is provided that opens forward (towards the lower part of the figure) from the protruding portion of the ECU cover 704.

[0065] In the ECU cover 704, the upper cover, including the top plate 71 and the side plate 72, and the lower cover 77 in the protrusion are separately formed and joined by adhesive. Figure 6As shown by the dashed line indicating the boundary, the lower cover 77 and the motor housing 201 can be formed separately or integrally. By forming them integrally, the number of parts can be reduced. Furthermore, the same applies to the drive devices 102 and 103 in the second and third embodiments; an ECU cover 704 that protrudes radially toward the motor unit 50 can be used.

[0066] (Other implementation methods)

[0067] (a) In the above embodiment, the motor flange 28, which mounts the drive device 10 to the end face of the gearbox 80, is integrally formed with the motor housing 201, 202. However, the object to which the drive device 10 is mounted is not limited to the gearbox 80, and the mounting method is not limited to a flange. In structures that do not use flanges, the motor flange may not be formed in the motor housing.

[0068] (b) The structure of the substrate 65 and connector 74 of the ECU60 is not limited to the structure illustrated in the above embodiments. For example, multiple substrates may be stacked.

[0069] (c) The drive device 10 of this disclosure is not limited to the steering auxiliary motor of an electric power steering system, but can also be used as a reaction force motor or steering motor of a steer-by-wire system, or as a drive device for any other motor.

[0070] The present disclosure is not limited to the above-described embodiments and can be implemented in various ways without departing from its spirit.

[0071] This disclosure is based on embodiments. However, this disclosure is not limited to these embodiments and structures. This disclosure also includes various modifications and equivalent variations. In addition, various combinations and methods, and further combinations and methods containing only one element, or more than one element, also fall within the scope and spirit of this disclosure.

Claims

1. A driving device, characterized in that, The drive unit integrally comprises a motor unit (50) and an ECU (60). The rotor (54) of the motor unit, located radially inside the annular stator (53), rotates integrally with the shaft (55). The ECU is located on one side of the axial direction of the motor unit and controls the drive of the motor unit. When the side opposite to the ECU relative to the motor unit is designated as the front side, and the side opposite to the ECU relative to the motor unit is designated as the rear side, The drive device includes: The motor housing (201) is formed of a non-metallic molded material and integrally forms a cylindrical portion (22) and a front bottom portion (23) extending axially along the motor portion. The front bottom portion holds a front bearing (56) that supports the shaft on the front side of the motor portion. The rear frame (40), which is a component distinct from the motor housing, and holds the rear bearing (57), which supports the shaft on the rear side of the motor section; and ECU cover (70, 704), which is formed of resin material into a container shape covering the substrate (65) of the ECU, and the end of the side plate (72) of the ECU cover is engaged with the end of the cylindrical part of the motor housing. The stator is molded from a non-metallic forming material, and The stator molding part (25) of the stator is integrally formed with the cylindrical part of the motor housing.

2. A driving device, characterized in that, The drive unit integrally comprises a motor unit (50) and an ECU (60). The rotor (54) of the motor unit, located radially inside the annular stator (53), rotates integrally with the shaft (55). The ECU is located on one side of the axial direction of the motor unit and controls the drive of the motor unit. When the side opposite to the ECU relative to the motor unit is designated as the front side, and the side opposite to the ECU relative to the motor unit is designated as the rear side, The drive device includes: The motor housing (202) is formed of a non-metallic molded material and integrally forms a cylindrical portion (22) and a rear bottom (24) extending axially along the motor portion, and the rear bottom holds a rear bearing (57) that supports the shaft on the rear side of the motor portion; The front frame (30), which is a component distinct from the motor housing, and holds the front bearing (56), which supports the shaft on the front side of the motor section; and ECU cover (70, 704), which is formed of resin material into a container shape covering the substrate (65) of the ECU, and the end of the side plate (72) of the ECU cover is engaged with the end of the cylindrical part of the motor housing. The stator is molded from a non-metallic forming material, and, The stator molding part (25) of the stator is integrally formed with the cylindrical part of the motor housing.

3. The driving device as described in claim 2, characterized in that, It also includes a metal plate (64) disposed between the base plate of the ECU and the rear bottom of the motor housing, which dissipates heat from the electronic components (66) mounted on the base plate.

4. The driving device according to any one of claims 1 to 3, characterized in that, The motor housing is made of carbon fiber composite material or resin material with a glass fiber content of 35% or more. The ECU cover is made of a resin material that is different from the material of the motor housing.

5. The driving device as described in claim 4, characterized in that, The stator molding section is integrally formed with the cylindrical portion of the motor housing using the same material as the motor housing.

6. The driving device as described in claim 4, characterized in that, The stator molding section is integrally formed with the cylindrical portion of the motor housing using a different material than the motor housing.

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