JP2018050439A - Motor and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor and an electric power steering device capable of suppressing vibration generated at a motor from being propagated to a decelerator housing.SOLUTION: A motor 20 has a rotation shaft 20a, a rotor 30, and a stator 40. The motor 20 has a motor housing 50 for housing the rotation shaft 20a, the rotor 30, and the stator 40. The motor housing 50 has a first motor housing 60 that houses the rotor 30 and the stator 40 therein; and a second motor housing 70 that surrounds an outer peripheral surface of the first motor housing 60. The first motor housing 60 and the second motor housing 70 are connected with each other at an opposite end part to a decelerator housing 24 for housing a decelerator 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor and an electric power steering apparatus including the motor.

  2. Description of the Related Art Conventionally, an electric power steering device (EPS) that assists a driver's steering operation by applying a rotational force of a motor as an assist force to a steering mechanism is known. For example, the motor is fixed to the vehicle by being attached to a speed reducer housing in which the speed reducer is accommodated (see, for example, Patent Document 1). The motor has a stator and a rotor, and a motor housing that houses the stator and the rotor is attached to the reduction gear housing.

JP 2012-90496 A

  By the way, when the motor is driven, the stator may be deformed in the form of expanding and contracting in the radial direction due to the attractive force and the repulsive force generated between the stator and the rotor. Vibration is generated due to such deformation of the stator, and the vibration is propagated to the vehicle through a reduction gear housing to which the motor is fixed. For this reason, there exists a possibility that the characteristic with respect to the sound and vibration of a vehicle may deteriorate.

  An object of the present invention is to provide a motor and an electric power steering device that can further suppress the vibration generated from the motor from being transmitted to the reduction gear housing.

A motor that can achieve the above object includes a stator having a coil,
A rotor having a magnet and disposed with a gap in a radial direction between the stator and an inner peripheral surface of the stator; and a motor housing that houses the stator and the rotor, wherein the motor housing includes the stator A first motor housing that fits on the outer peripheral surface of the first motor housing, and a second motor housing that surrounds the outer peripheral surface of the first motor housing with a gap in the radial direction. The first motor housing and the second motor housing are connected to each other at an end opposite to the speed reducer housing.

  According to this configuration, when the motor is driven, the stator expands and contracts in the radial direction by the attractive force and the repulsive force generated between the stator and the rotor. The vibration generated by the expansion / contraction is transmitted to the end portion of the first motor housing opposite to the speed reducer housing that houses the speed reducer, and the speed reducer housing in the second motor housing connected to the end portion. After being transmitted to the opposite end, it is transmitted to the end of the second motor housing on the reduction gear housing side. That is, since a gap is provided between the outer peripheral surface of the portion of the first motor housing that contacts the stator and the second motor housing, vibration due to the expansion and contraction of the stator is not directly transmitted to the second motor housing. The first motor housing and the second motor housing are detoured to the connecting portion and transmitted to the second motor housing. For this reason, it is suppressed that the vibration generated from the motor is transmitted to the reduction gear housing.

  In the motor described above, an end of the first motor housing on the side of the speed reducer housing is located inside the speed reducer housing beyond the mating surface of the second motor housing and the speed reducer housing, and It is preferable not to contact either the second motor housing or the reduction gear housing.

  According to this configuration, the first motor housing extends beyond the mating surface between the second motor housing and the housing that houses the speed reducer to the housing side that houses the speed reducer. It is provided at a position close to the speed reducer. For this reason, since the whole motor can be brought closer to a reduction gear, it can control that a motor is shaken.

  The motor may include a rotation shaft that is attached so as to penetrate the rotor, and the second motor housing may include a bearing holding portion that holds a bearing that rotatably supports the rotation shaft.

According to this structure, the 2nd motor housing can hold | maintain the bearing which supports a rotating shaft rotatably via a bearing holding | maintenance part.
The above motor is suitable for an electric power steering apparatus.

  According to the motor and the electric power steering apparatus of the present invention, it is possible to further suppress the vibration generated from the motor from being transmitted to the reduction gear housing.

1 is a schematic configuration diagram of an electric power steering apparatus according to an embodiment. Sectional drawing which shows schematic structure of the EPS actuator in the electric power steering apparatus of one Embodiment. The schematic diagram which exaggerates and shows the positional relationship of the periphery of a 1st motor housing and a 2nd motor housing. Sectional drawing which shows schematic structure of the EPS actuator in the electric power steering apparatus of other embodiment. Sectional drawing which shows schematic structure of the EPS actuator in the electric power steering apparatus of other embodiment.

Hereinafter, an embodiment in which a motor is embodied in a steering device will be described.
As shown in FIG. 1, the EPS 1 (electric power steering device) includes a steering mechanism 2 that steers the steered wheels 18 based on an operation of the driver's steering wheel 10, and an EPS actuator 3 that assists the driver's steering operation. I have.

  The steering mechanism 2 includes a steering wheel 10 and a steering shaft 11 that rotates integrally with the steering wheel 10. The steering shaft 11 includes a column shaft 12 connected to the steering wheel 10, an intermediate shaft 13 connected to the lower end portion of the column shaft 12, and a pinion shaft 14 connected to the lower end portion of the intermediate shaft 13. Yes. A lower end portion of the pinion shaft 14 is connected to a rack shaft 15 that is a steered shaft via a rack and pinion mechanism 16. Therefore, in the steering mechanism 2, the rotational movement of the steering shaft 11 is performed by the axis of the rack shaft 15 via the rack and pinion mechanism 16 including a pinion provided at the tip of the pinion shaft 14 and a rack provided on the rack shaft 15. It is converted into a reciprocating linear motion in the direction (left-right direction in FIG. 1). The reciprocating linear motion is transmitted to the left and right steered wheels 18 via the tie rods 17 respectively connected to both ends of the rack shaft 15, whereby the steered angle of the steered wheels 18 changes and the traveling direction of the vehicle changes. Be changed.

  The EPS actuator 3 includes a motor 20 that applies assist force to the steering shaft 11. A rotation shaft of the motor 20 is connected to the column shaft 12 via a speed reducer 21. The speed reducer 21 transmits the output torque (rotational force) of the motor 20 to the column shaft 12. The reduction gear 21 has a wheel gear 22 connected to the column shaft 12 and a worm gear 23 connected to the motor 20 and meshing with the wheel gear 22. The rotation of the motor 20 is decelerated by the speed reducer 21, and the rotational force of the decelerated motor 20 is transmitted as an assist force to the steering shaft 11, thereby assisting the driver's steering operation.

Next, the configuration of the EPS actuator 3 will be described.
As shown in FIG. 2, the EPS actuator 3 includes a reduction gear housing 24 that houses the reduction gear 21. In the reduction gear housing 24, the steering shaft 11 (column shaft 12) is disposed in a state of penetrating the inside. The motor 20 is fixed to the speed reducer housing 24 in a state where the axis of the rotary shaft 20 a is orthogonal to the axis of the steering shaft 11. A worm gear 23 is fixed to the rotating shaft 20a of the motor 20 so as to be integrally rotatable. Both ends of the worm gear 23 are rotatably supported with respect to the reduction gear housing 24 via bearings 25 and 26. The worm gear 23 is meshed with a wheel gear 22 fixed to the steering shaft 11 so as to be integrally rotatable.

  The motor 20 includes a rotor 30 that is fixed to the outer periphery of the rotating shaft 20a so as to be integrally rotatable, and a stator 40 that is disposed on the outer periphery of the rotor 30 with a gap. The motor 20 has a motor housing 50 that houses the rotating shaft 20 a, the rotor 30, and the stator 40.

The stator 40 includes a cylindrical stator core 41 and a coil 42 wound around a plurality of teeth of the stator core 41 via an insulator such as resin.
The rotor 30 includes a cylindrical rotor core 31 attached to the outer periphery of the rotating shaft 20a so as to be integrally rotatable, and a cylindrical magnet 32 attached to the outer periphery of the rotor core 31 so as to be integrally rotatable. The rotor 30 is supported to be rotatable with respect to the motor housing 50 by supporting both ends of the rotating shaft 20 a so as to be rotatable with respect to the motor housing 50 via bearings 51 and 52. The magnet 32 is configured, for example, by arranging a plurality of magnets side by side in the circumferential direction of the rotor core 31. These magnets are arranged such that their magnetic poles alternate between the N pole and the S pole in the circumferential direction of the rotor core 31.

  The motor housing 50 has a bottomed cylindrical shape with one end (upper end in FIG. 2) opened. The motor housing 50 is a double cylindrical body including a first motor housing 60 and a second motor housing 70. The first motor housing 60 accommodates the rotor 30 and the stator 40. The second motor housing 70 is provided so as to surround the outer periphery of the first motor housing 60. The motor housing 50 is made of aluminum, for example.

  The first motor housing 60 has a first end (lower end in FIG. 2) that is the end on the reduction gear housing 24 side closed, and a second end that is the end opposite to the reduction gear housing 24. It is a bottomed cylindrical body with an open end (upper end in FIG. 2). The first motor housing 60 has a tubular portion 61 and a substantially annular bottom portion 62 that closes the first end of the tubular portion 61. The outer peripheral surface of the stator 40 is fixed to the inner peripheral surface of the cylindrical portion 61. A bearing holding portion 64 for supporting the bearing 52 is formed on the bottom portion 62. A flange portion 63 is provided on the outer peripheral surface of the second end portion of the cylindrical portion 61 over the entire circumference.

  The second motor housing 70 has a cylindrical portion 71 that covers the first motor housing 60. A cylindrical inner wall 72 fitted to the reduction gear housing 24 is provided at a first end portion (lower end portion in FIG. 2) that is an end portion of the second motor housing 70 on the reduction gear housing 24 side. The outer diameter of the inner wall portion 72 is smaller than the outer diameter of the second motor housing 70. Further, a flange portion 73 is provided on the outer peripheral surface of the second end portion (upper end portion in FIG. 2) that is the end portion of the second motor housing 70 opposite to the speed reducer housing 24 over the entire periphery. . A fixing portion 74 for connecting (connecting) the first motor housing 60 and the second motor housing 70 is recessed in the end surface of the flange portion 73 on the side of a control device (substrate 27 or the like) described later. The first motor housing 60 is inserted into the second motor housing 70 up to a position where the flange portion 63 contacts the fixed portion 74. The first motor housing 60 and the second motor housing 70 are only in contact with each other at the fixing portion 74 and the flange portion 63. Between the outer peripheral surface of the cylindrical part 61 and the inner peripheral surface of the cylindrical part 71, the clearance gap is formed over those perimeters.

  The motor housing 50 includes a cylindrical lid member 80 that closes the second end of the cylindrical portion 61. For example, iron is used for the lid member 80. The lid member 80 is provided with a bearing holding portion 80 a for supporting the bearing 51. A flange portion 81 is provided on the outer peripheral surface of the second end portion (upper end portion in FIG. 2) of the lid member 80 over the entire periphery. The lid member 80 is inserted into the tubular portion 61 until the flange portion 81 contacts the flange portion 63 of the first motor housing 60. The first motor housing 60 and the second motor housing 70 are fixed to each other by being screwed into a bolt hole 75 provided in the fixing portion 74 in a state where the bolt 76 passes through the flange portion 63 and the flange portion 81. Has been. The rotary shaft 20 a is supported so as to be rotatable with respect to the motor housing 50 via bearings 51 and 52.

  A plurality of fixing portions 77 are provided on the outer peripheral surface of the first end portion of the second motor housing 70. The motor 20 is attached to the speed reducer housing 24 by screwing the bolts 79 into the bolt holes 24 a formed in the speed reducer housing 24 through the through holes 78 formed in the fixing portion 77. A substrate 27 is provided on the end surface of the motor housing 50 opposite to the speed reducer 21. The substrate 27 is provided with a control device that controls the operation of the motor 20. A cover 28 that covers the substrate 27 is attached to a portion of the motor housing 50 opposite to the speed reducer 21. In addition, the plate 29 is fixed to a portion of the reduction gear housing 24 facing the bottom portion 62 of the first motor housing 60 so that a slight gap is formed between the bottom portion 62.

Next, the structure of the first motor housing 60 will be described in detail.
As shown in FIG. 3, a gap S is formed between the outer peripheral surface of the first motor housing 60 and the inner peripheral surface of the second motor housing 70. The first motor housing 60 has a stepped cylindrical shape whose outer diameter gradually decreases from the second end (upper end in FIG. 3) toward the first end (lower end in FIG. 3). doing. The cylindrical part 61 of the first motor housing 60 has a first cylindrical part 90, a second cylindrical part 91, a third cylindrical part 92, a fourth cylindrical part 93, and a fifth cylinder in order of increasing outer diameter. A shaped portion 94 is provided.

  The outer diameter of the first cylindrical portion 90 is slightly smaller than the inner diameter of the inner wall surface 71 a of the second motor housing 70. Thereby, since a slight gap is formed between the inner wall surface 71a and the first cylindrical portion 90, even when the first motor housing 60 is assembled to the second motor housing 70 from the axial direction, The first cylindrical portion 90 is prevented from rubbing against the inner wall surface 71a. The flange portion 63 does not contact the fixed portion 74 over the entire area, but contacts the fixed portion 74 within a certain range of the outer edge portion of the flange portion 63.

  The inner diameter of the third cylindrical portion 92 is set almost equal to the outer diameter of the stator core 41 of the stator 40. The stator core 41 is press-fitted into the third cylindrical portion. Further, the inner diameter of the fourth cylindrical portion 93 is set smaller than the outer diameter of the stator core 41. Therefore, when the stator core 41 is press-fitted into the first motor housing 60 from the second end portion toward the first end portion, the stator core 41 has a boundary portion between the third tubular portion 92 and the fourth tubular portion 93. It is positioned in the axial direction by being caught on the step. Further, since the inner diameter of the second cylindrical portion 91 is set to be larger than the outer diameter of the stator core 41, it is possible to prevent the stator core 41 from rubbing against the first motor housing 60 when the stator core 41 is press-fitted into the first motor housing 60. Is done.

  A gap is also formed between the outer peripheral surface of the fifth cylindrical portion 94 and the inner peripheral surface of the inner wall portion 72 of the second motor housing 70. Further, between the tapered connecting portion 95 connecting the fourth cylindrical portion 93 and the fifth cylindrical portion 94 and the second motor housing 70 (precisely, the connecting portion between the cylindrical portion 71 and the inner wall 72). In addition, a gap is formed.

The operation and effect of this embodiment will be described.
When the motor 20 is driven, the stator 40 is expanded and contracted (hereinafter referred to as expansion / contraction) in the radial direction by the attractive force and the repulsive force generated between the stator 40 and the magnet 32 fixed to the rotor 30. For example, when the motor 20 is configured as a “10 pole 12 slot” motor, the stator 40 expands and contracts into an elliptical shape when viewed from the axial direction due to the attractive force and the repulsive force. The vibration generated by the expansion / contraction of the stator 40 is transmitted to the first motor housing 60 fixed to the outer surface of the stator 40.

  The vibration generated from the stator 40 is first transmitted to the third cylindrical portion 92 of the first motor housing 60 disposed on the outer surface of the stator 40. A portion of the first motor housing 60 that is closer to the speed reducer housing 24 than the third cylindrical portion 92 is not in contact with the second motor housing 70 and is not in contact with the speed reducer housing 24. For this reason, there is no path through which vibration is directly transmitted from the portion on the reduction gear housing 24 side of the third cylindrical portion 92 of the first motor housing 60 to the reduction gear housing 24. Thereby, the vibration transmitted to the third cylindrical portion 92 is transmitted from the third cylindrical portion 92 in the first motor housing 60 toward the opposite direction (second end portion) to the reduction gear housing 24. . That is, the vibration transmitted to the third tubular portion 92 is transmitted to the second tubular portion 91, the first tubular portion 90, and the flange portion 63. Next, the vibration transmitted to the flange portion 63 is transmitted to the cylindrical portion 71 via the fixing portion 74 of the second motor housing 70. Next, this vibration is transmitted from the second end portion of the cylindrical portion 71 toward the first end portion, thereby being transmitted to the fixing portion 77. And this vibration is transmitted to each part of the vehicle including EPS1 by being transmitted to the reduction gear housing 24 via the fixed part 77. That is, in order for this vibration to be transmitted to the reduction gear housing 24, the second motor housing 70 is opposite to the reduction gear housing 24 from the second end portion of the first motor housing 60 opposite to the reduction gear housing 24. It is necessary to transmit to the second end portion on the side, and further to the first end portion on the reduction gear housing 24 side in the second motor housing 70.

  As described above, in the present embodiment, the vibration generated in the stator 40 needs to follow the path R that is detoured in the direction away from the reducer housing 24, and therefore, the vibration is suppressed from being transmitted to the reducer housing 24. Yes. This is because vibration energy is consumed as it travels along the path R. The longer the path R is set, the more vibration energy is consumed.

  The vibration transmitted to the end of the second motor housing 70 on the reduction gear housing 24 side is reduced, and the second motor housing 70 on the mating surface F between the second motor housing 70 and the reduction gear housing 24 is reduced. Collisions with the reducer housing 24 are mitigated. For this reason, the vibration transmitted to the reduction gear housing 24 and the sound resulting from the vibration can be suppressed, and the characteristics (NV characteristics) with respect to the sound and vibration of the vehicle are improved.

  In the present embodiment, the second motor housing 70 is provided via the gap S so as to cover the outer peripheral surface of the first motor housing 60. For this reason, the radiated sound from the motor 20 accompanying the expansion / contraction of the stator 40 is less likely to leak to the outside due to being shielded by the second motor housing 70.

  In the present embodiment, the first motor housing 60 (bottom 62) extends into the reduction gear housing 24 beyond the mating surface F between the second motor housing 70 and the reduction gear housing 24. Thereby, the rotating shaft 20a of the motor 20 is further provided at a position closer to the speed reducer 21. Since the portion on the reduction shaft 21 side of the rotating shaft 20a is fixed to the worm gear 23, it is also conceivable that the motor 20 is swung with the connecting portion between the rotating shaft 20a and the worm gear 23 as a fulcrum. On the other hand, the center of gravity of the motor 20 is in the vicinity of an intermediate position in the axial direction of the rotating shaft 20a. Since the fulcrum of the motor 20 and the center of gravity of the motor 20 are closer to each other, the resonance frequency when the motor 20 is swung can be separated from the frequency when the rotating shaft 20a of the motor 20 rotates. It is possible to improve the vibration characteristics.

In addition, you may change this embodiment as follows. The following other embodiments can be combined with each other within a technically consistent range.
As shown by a two-dot chain line in FIG. 3, a recess 62a may be provided on the outer peripheral surface of the bottom 62, and an elastic member such as an O-ring 96 may be provided in the recess 62a. The inner surface of the concave portion 62 a of the bottom portion 62 and the inner wall portion 72 are in contact via an O-ring 96. Accordingly, the vibration between the bottom 62 and the inner wall 72 is suppressed by elastic deformation of the O-ring 96, but the gap between the bottom 62 and the inner wall 72 is filled with the O-ring 96. It is suppressed that 62 and the inner wall part 72 adjoin each other.

  As shown by a two-dot chain line in FIG. 3, even if an elastic member 100 such as a spring is provided between the cylindrical portion 61 (third cylindrical portion 92) and the inner wall surface 71 a of the cylindrical portion 71. Good. Thereby, the 1st motor housing 60 and the 2nd motor housing 70 contact | abut via the elastic member 100 in those radial directions. For this reason, relative movement of the first motor housing 60 and the second motor housing 70 in their radial direction is suppressed by the elastic force of the elastic member 100. Even when the vibration transmitted to the first motor housing 60 is transmitted to the second motor housing 70 without following the detoured path R, the second motor is in a state where the vibration is attenuated by the elastic force of the elastic member 100. It will be transmitted to the housing 70. For this reason, it can suppress that the vibration characteristic of a vehicle deteriorates.

  The material of the motor housing 50 is not limited to aluminum, and another material such as iron or resin may be employed. Further, the material of the bearing holding portion 80a is not limited to iron, and another material such as aluminum or resin may be employed.

  -In this embodiment, although the 2nd motor housing 70 was provided so that the outer peripheral surface of the 1st motor housing 60 might be covered over the perimeter, it does not restrict to this. For example, the first motor housing 60 may be exposed through the slit of the second motor housing 70 by providing a slit in the second motor housing 70. In this case, the function of shielding the sound emitted from the motor 20 by the second motor housing 70 is suppressed, but the function of transmitting vibration from the first motor housing 60 to the second motor housing 70 can be ensured. . Further, the entire motor 20 can be reduced in weight by providing a slit in the second motor housing 70.

  In the present embodiment, the first motor housing 60 and the second motor housing 70 are provided separately, but the present invention is not limited to this. For example, as shown in FIG. 4, the first motor housing 60 and the second motor housing 70 may be connected by being integrated.

  In the present embodiment, the second motor housing 70 and the lid member 80 are provided separately, but are not limited thereto. For example, as shown in FIG. 5, the second motor housing 70 and the lid member 80 may be integrated to be connected. That is, the second motor housing 70 may have a portion that functions as the lid member 80.

  In the present embodiment, the first motor housing 60 has a plurality of steps, but the present invention is not limited to this. For example, the cylindrical portion 61 of the first motor housing 60 may be a substantially conical body whose outer diameter increases toward the second end portion, except for a portion that accommodates the stator 40. Thereby, you may make it contact the 2nd end part of the 2nd motor housing 70 only in the 2nd end part of the 1st motor housing 60. FIG.

  -EPS1 of this embodiment was what is called column type EPS1 which transmits the rotational force of the rotating shaft 20a of the motor 20 to the column shaft 12, but it is not restricted to this. For example, an EPS that transmits the rotational force of the rotating shaft 20 a to the pinion shaft 14 or an EPS that transmits the rotational force to the rack shaft 15 may be used.

  In the present embodiment, the motor 20 is embodied in the EPS 1 of the vehicle. However, the present invention is not limited to this, and the motor 20 may be embodied in various drive devices.

  DESCRIPTION OF SYMBOLS 1 ... EPS, 2 ... Steering mechanism, 3 ... EPS actuator, 10 ... Steering wheel, 11 ... Steering shaft, 12 ... Column shaft, 13 ... Intermediate shaft, 14 ... Pinion shaft, 15 ... Rack shaft, 16 ... Rack and pinion Mechanism: 17 ... Tie rod, 18 ... Steering wheel, 20 ... Motor, 20a ... Rotating shaft, 21 ... Reduction gear, 22 ... Wheel gear, 23 ... Worm gear, 24 ... Reduction gear housing, 24a ... Bolt hole, 25, 26 ... Bearing 27 ... Substrate, 28 ... Cover, 29 ... Plate, 30 ... Rotor, 31 ... Rotor core, 32 ... Magnet, 40 ... Stator, 41 ... Stator core, 42 ... Coil, 50 ... Motor housing, 51, 52 ... Bearing, 60 ... First motor housing 61 ... cylindrical part 62 ... bottom part 62a ... , 63 ... flange part, 64 ... bearing holding part, 70 ... second motor housing, 71 ... cylindrical part, 71a ... inner wall part, 72 ... extension part, 73 ... flange part, 74 ... fixing part, 75 ... bolt Bore, 76 ... bolt, 77 ... fixed portion, 78 ... through hole, 79 ... bolt, 80 ... lid member, 80a ... bearing holding portion, 81 ... flange portion, 90 ... first tubular portion, 91 ... second tubular shape Part, 92 ... third cylindrical part, 93 ... fourth cylindrical part, 94 ... outer wall surface, 100 ... elastic member, R ... path, S ... gap.

Claims (4)

A stator having a coil;
A rotor having a magnet and disposed with a gap in a radial direction between the inner peripheral surface of the stator;
A motor housing that houses the stator and the rotor,
The motor housing has a first motor housing that fits to the outer peripheral surface of the stator, and a second motor housing that surrounds the outer peripheral surface of the first motor housing with a gap in the radial direction,
The second motor housing is fixed at one end thereof to a speed reducer housing that houses the speed reducer,
The first motor housing and the second motor housing are connected to each other at an end opposite to the reduction gear housing. The motor according to claim 1,
An end of the first motor housing on the side of the speed reducer housing is located inside the speed reducer housing beyond the mating surface of the second motor housing and the speed reducer housing, and the second motor housing and A motor that does not contact any of the reduction gear housings. The motor according to claim 1 or 2,
Having a rotating shaft attached in a form penetrating the rotor;
The second motor housing includes a bearing holding portion that holds a bearing that rotatably supports the rotating shaft.   An electric power steering apparatus comprising the motor according to any one of claims 1 to 3.

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