JP2006121818A - Motor, and electric power steering device mounting motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor that is suitable, for example, for an electric power steering device, high in the rigidity of an outer core, and can suppress the generation of noise, and the electric power steering device mounting the motor. <P>SOLUTION: The motor 19 comprises a stator 54 having a ring shape formed by combining a plurality of cores 54a to 54i, and the shape of each core 54a to 54i is formed into a substantial T shape at its cross section formed of a connecting part having a prescribed width with respect to the radial direction when formed into the ring shape, and a salient part. When the stator having the ring shape formed by combining the plurality of cores is accommodated in a motor housing, the cores come into contact with one another at the inside diameter of the connecting part, and do not come into contact with one another at the outside diameter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor suitable for an electric power steering apparatus and an electric power steering apparatus equipped with the motor.

  The electric power steering device is a support device that assists a steering force by interlocking a motor when a driver operates a steering wheel (steering handle) while driving an automobile. In the electric power steering apparatus, motor control is performed using a steering torque signal from a steering torque detection unit that detects a steering torque generated in a steering shaft by a steering wheel of a driver and a vehicle speed signal from a vehicle speed detection unit that detects a vehicle speed. On the basis of the control operation of the unit, the assisting motor that outputs the auxiliary steering force is driven and controlled to reduce the driver's steering force.

  The steering torque applied to the steering wheel is transmitted to the output shaft of the rack and pinion mechanism, and the auxiliary torque generated by the motor according to the steering torque is transmitted to the pinion shaft via the friction engagement transmission means and the worm gear mechanism. The wheels are steered by a rack and pinion mechanism.

  Patent Document 1 discloses a brushless motor used in an electric power steering device or the like.

  A rotating shaft (rotor) of the motor used in the electric power steering apparatus is coupled to a worm gear rotatably supported by a housing of the steering gear box through an elastic member through a coupling. This worm gear meshes with a worm wheel gear provided integrally with the pinion gear shaft, and boosts the torque generated by the motor. The motor projects in a direction substantially perpendicular to the pinion shaft and is fixed to the housing of the steering gear box. Therefore, the rigidity when the motor and the housing are fixed is lowered, and there is a problem that the operation vibration when the motor is energized is transmitted to the housing and noise is generated.

  In order to solve the above problems, it is necessary to increase the rigidity of the motor.

  FIG. 9 is a cross-sectional view perpendicular to the rotation axis of a conventional motor. In the motor 100, an outer core 102 composed of nine T-shaped split cores 102a to 102i is housed in a motor housing 101, and coils 104a to 104i are placed on salient pole portions 103a to 103i of the cores 102a to 102i. It has been. At the center of the motor 100, a rotor 109 including a rotating shaft 105, an inner core 106, octupole ring magnets 107a to 107h, and a magnet cover 108 is provided. Each of the cores 102a to 102i is configured such that semicircular arc-shaped convex portions 112a to 112i and concave portions 113a to 113i are respectively provided on the connecting portions 110a to 110i and 111a to 111i having a substantially T-shaped cross section. The

As shown in FIG. 9, the outer core 102 of the motor 100 is composed of a plurality (nine) of divided cores 102a to 102i. These split cores 102a to 102i have an inner diameter of the motor housing 101 smaller than an outer diameter of the ring when the T-shaped connecting portions 110a to 110i and 111a to 111i of the split cores 102a to 102i are formed in close contact with each other. It is set and fixed to the inner diameter of the motor housing 101. Therefore, the outer diameter portions 114a to 114i and 115a to 115i of the connecting portions of the cores 102a to 102i are in contact with each other, and the inner diameter portions 116a to 116i and 117a to 117i of the connecting portions of the cores 102a to 102i are not in contact with each other. It is stored in.
Japanese Patent Laid-Open No. 11-234928

  The conventional motor shown in FIG. 9 has the following problems. As shown in FIG. 9, the outer core 102 of the motor 100 is composed of a plurality (nine) of divided cores 102 a to 102 i, and is an outer assembly that is an aggregate of the divided cores 102 a to 102 i compared to the inner diameter of the motor housing 101. Since the outer diameter of the core 102 is set large, as shown in FIG. 10, forces R1 and R2 are generated by the scissors (FIG. 10 shows one divided core 102a as an example). The shape of the split core 102a is configured such that a semicircular arc-shaped convex portion 112a and a concave portion 113a are provided and fitted to the connecting portions 110a and 111a having a substantially T-shaped cross section, respectively. Therefore, these forces R1 and R2 act as shown in FIG. 10, for example, from the contact between the convex portion 112a and the concave portion 113a. At this time, the force P acting in the inner diameter direction of the motor housing 101 becomes zero, so that it does not become a tension force. In addition, a bending moment M is generated, causing a tilt and causing an unstable problem. As a result, insufficient rigidity occurs, causing the outer core 102 to vibrate when the motor is energized, and this vibration is transmitted to the housing 101 due to insufficient rigidity to generate noise. Therefore, it has been desired to increase the rigidity of the outer core, which is an assembly of divided cores. In particular, when used in an electric power steering apparatus, there is a problem in that the vibration of the motor is directly transmitted to the steering wheel and the steering feeling is lowered.

  An object of the present invention is to provide a motor and an electric power steering apparatus equipped with the motor, which are suitable for an electric power steering apparatus, for example, and have a high rigidity outer core and can suppress the generation of noise.

  In order to achieve the above object, the motor according to the present invention and the electric power steering device equipped with the motor are configured as follows.

  A first motor according to the present invention (corresponding to claim 1) is a motor including a stator that is formed into a ring shape by combining a plurality of cores, and the shape of each core is a radial direction when the ring shape is formed. When the stator having a ring shape formed by combining a plurality of cores is placed in the motor housing, each core is It is characterized by being in contact at the inner diameter part of the connecting part and non-contacting at the outer diameter part.

  In a second motor according to the present invention (corresponding to claim 2), the motor housing preferably has an inner diameter formed by contacting the entire connecting portion having a plurality of core widths without any gaps. It is characterized by being set smaller than the outer diameter of the ring.

  A third motor according to the present invention (corresponding to claim 3) is a brushless motor having the above-mentioned configuration, preferably a motor including an inner rotor provided with a plurality of magnets and driven by a plurality of AC waveforms. It is characterized by being.

  A first electric power steering apparatus according to the present invention (corresponding to claim 4) is an electric power steering apparatus that generates a steering force by a motor and steers the vehicle, and the first or second motor is used as the motor. It is characterized by using.

  The motor according to the present invention can impart high rigidity, and has an effect that vibration of the outer core is suppressed when the motor is energized and this vibration is hardly transmitted to the housing. In addition, an electric power steering apparatus equipped with this motor can be made to have a smooth steering feeling with low vibration transmission and low noise.

  Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

  The configurations, shapes, sizes, and arrangement relationships described in the embodiments are merely schematically shown to the extent that the present invention can be understood and implemented, and the composition of each configuration is merely an example. Therefore, the present invention is not limited to the embodiments described below, and can be modified in various forms without departing from the scope of the technical idea shown in the claims.

  The overall configuration of the electric power steering apparatus including the motor according to the present invention, the main configuration of the mechanical mechanism, and the layout of the electronic circuit unit will be described with reference to FIGS.

  FIG. 1 shows an overall configuration of an electric power steering apparatus 10 including a motor according to the present invention. The electric power steering device 10 is installed in, for example, a passenger vehicle. The electric power steering device 10 is configured to give auxiliary steering force (steering torque) to the steering shaft 12 and the like connected to the steering wheel 11. An upper end of the steering shaft 12 is connected to the steering wheel 11, and a pinion gear 13 is attached to the lower end. A rack shaft 14 provided with a rack gear 14a meshing with the pinion gear 13 is disposed. A rack and pinion mechanism 15 is formed by the pinion gear 13 and the rack gear 14a. Tie rods 16 are provided at both ends of the rack shaft 14, and front wheels 17 are attached to the outer ends of the tie rods 16. A motor 19 is provided for the steering shaft 12 via a power transmission mechanism 18.

  The motor 19 outputs a rotational force (torque) that assists the steering torque, and applies this rotational force to the steering shaft 12 via the power transmission mechanism 18. The steering shaft 12 is provided with a steering torque detector 20. The steering torque detector 20 detects the steering torque applied to the steering shaft 12 and its direction of action when the steering torque generated by the driver operating the steering wheel 11 is applied to the steering shaft 12. Reference numeral 21 denotes a vehicle speed detection unit that detects the traveling speed of the vehicle, and reference numeral 22 denotes a control device constituted by a computer. The control device 22 takes in the steering torque signal T output from the steering torque detection unit 20 and the vehicle speed signal V output from the vehicle speed detection unit 21, and based on the information on the steering torque and the information on the vehicle speed, A drive control signal SG1 for controlling the rotation operation is output. Further, the motor 19 is provided with a motor rotation angle detector 23 constituted by a resolver or the like. The rotation angle signal SG2 of the motor rotation angle detector 23 is fed back to the control device 22. The rack and pinion mechanism 15 and the like are housed in a gear box 24 not shown in FIG.

  In the above, the electric power steering device 10 is configured by adding a steering torque detection unit 20, a vehicle speed detection unit 21, a control device 22, a motor 19, and a power transmission mechanism 18 to a normal steering system configuration. . In addition, the electric motor 19 is comprised from a brushless motor, for example.

  In the above configuration, when the driver operates the steering wheel 11 to steer in the traveling direction during the traveling operation of the automobile, the rotational force based on the steering torque applied to the steering shaft 12 is transmitted via the rack and pinion mechanism 15. It is converted into a linear motion in the axial direction of the rack shaft 14, and further, the traveling direction of the front wheel 17 is changed via the tie rod 16. At this time, at the same time, the steering torque detector 20 attached to the steering shaft 12 detects the steering torque corresponding to the steering by the driver at the steering wheel 11 and converts it into an electrical steering torque signal T. A steering torque signal T is output to the control device 22. The vehicle speed detector 21 detects the vehicle speed of the vehicle, converts it into a vehicle speed signal V, and outputs the vehicle speed signal V to the control device 22.

  The control device 22 generates motor currents (Iu, Iv, Iw) for driving the electric motor 19 based on the steering torque signal T and the vehicle speed signal V. The electric motor 19 is a three-phase electric motor, and its motor current is a three-phase alternating current Iu, Iv, Iw composed of a U phase, a V phase, and a W phase. The drive control signal SG1 is motor currents Iu, Iv, and Iw that are three-phase alternating current. The electric motor 19 driven by the motor current causes an auxiliary steering force to act on the steering shaft 12 via the power transmission mechanism 18. By driving the motor 19 as described above, the steering force applied by the driver to the steering wheel 11 is reduced.

  FIG. 2 shows a specific configuration of a main part of the mechanical mechanism of the electric power steering apparatus 10 and an electric system. A part of the left end portion and the right end portion of the rack shaft 14 is shown in cross section. The rack shaft 14 is housed in a cylindrical housing 31 arranged in the vehicle width direction (left-right direction in FIG. 2) so as to be slidable in the axial direction. Ball joints 32 are screwed to both ends of the rack shaft 14 protruding from the housing 31, and left and right tie rods 16 are connected to these ball joints 32. The housing 31 includes a bracket 33 for attaching to a vehicle body (not shown), and includes stoppers 34 at both ends.

  In FIG. 2, 35 is an ignition switch, 36 is an in-vehicle battery, and 37 is an AC generator (ACG) attached to the vehicle engine. The AC generator 37 starts power generation by the operation of the vehicle engine. Necessary electric power is supplied from the battery 36 or the AC generator 37 to the control device 22. The control device 22 is attached to the motor 19.

  FIG. 3 is a cross-sectional view taken along line AA in FIG. In FIG. 3, the specific structure of the support structure of the steering shaft 12, the steering torque detection unit 20, the power transmission mechanism 18, the rack and pinion mechanism 15, and the layout of the electric motor 19 and the control device 22 are clearly shown.

  In FIG. 3, the steering shaft 12 is rotatably supported by two bearing portions 41 and 42 in a housing 24 a forming the gear box 24. A rack and pinion mechanism 15 and a power transmission mechanism 18 are housed inside the housing 24a, and a steering torque detector 20 is additionally provided at the top. The pinion 13 provided at the lower end portion of the steering shaft 12 is located between the bearing portions 41 and 42. The rack shaft 14 is pressed against the pinion 13 by a contact member 47 guided by a rack guide 45 and biased by a compressed spring 46. The power transmission mechanism 18 is formed by a worm gear 49 fixed to a transmission shaft 48 coupled to an output shaft of the electric motor 19 and a worm wheel 50 fixed to the steering shaft 12. The steering torque detection unit 20 includes a steering torque detection sensor 20a disposed around the steering shaft 12, and an electronic circuit unit 20b that electrically processes a detection signal output from the steering torque detection sensor 20a. .

  4 is a cross-sectional view taken along line BB in FIG. In FIG. 4, specific configurations inside the motor 19 and the control device 22 are clearly shown.

  The motor 19 includes a rotor 52 made of a permanent magnet fixed to the rotating shaft 51, and an outer core 54 composed of a plurality of cores having windings 53 arranged around the rotor 52. The rotating shaft 51 is rotatably supported by two bearing portions 56 and 57. The tip of the rotating shaft 51 is an output shaft 19 a of the motor 19. The output shaft 19a of the motor 19 is coupled to the transmission shaft 48 through the torque limiter 58 so that rotational power is transmitted.

  As described above, the worm gear 49 is fixed to the transmission shaft 48, and the worm wheel 50 meshing with the worm gear 49 is disposed. The rear end portion of the rotation shaft 51 is provided with the above-described motor rotation angle detection unit (position detection unit) 23 that detects the rotation angle (rotation position) of the rotor 52 of the motor 19. The motor rotation angle detection unit 23 includes a rotor 23a fixed to the rotation shaft 51 and a detection element 23b that detects the rotation angle of the rotor 23a using a magnetic action. For example, a resolver is used for the motor rotation angle detector 23. Motor currents Iu, Iv, and Iw that are three-phase alternating current are supplied to the windings 53 of the stators 54 and 55. The above components of the motor 19 are arranged inside the motor housing 59.

  FIG. 5 is a cross-sectional view taken along the line CC of FIG. 4 and shows a cross-sectional structure of the motor 19. The control device 22 is omitted. The outer core 54 includes nine cores 54a to 54i, and teeth (saliency poles) 62a to 62i are radially extended from the cores 54a to 54i. The windings 53a to 53i are wound around these nine teeth 62a to 62i arranged in a radial manner to constitute a U phase, a V phase, and a W phase.

  The rotor 52 is a rotating body having eight (eight poles) permanent magnets 52a to 52h in the circumferential direction. The eight permanent magnets 52a to 52h are arc-shaped members magnetized in the radial direction (inner / outer surface direction), and are arranged so that N poles and S poles are alternately arranged in the circumferential direction.

  A first embodiment of an electric motor according to the present invention will be described.

  As shown in FIG. 5, in the motor 19, an outer core 54 composed of nine T-shaped split cores 54a to 54i is housed in a motor housing 59, and a coil 53a is placed on the salient pole portions 62a to 62i of these cores. ~ 53i is sown. A rotor 52 including a rotating shaft 51, an inner core 63, octupole ring magnets 52 a to 52 h, and a magnet cover 64 is provided at the center of the motor 19. Each of the cores 54a to 54i is configured such that semicircular arc-shaped convex portions 72a to 72i and concave portions 73a to 73i are respectively provided on the connecting portions 70a to 70i and 71a to 71i having a substantially T-shaped cross section. The

  The motor 19 includes a ring-shaped stator 54 in which a plurality of cores 54a to 54i are combined, and each core 54a to 54i has a predetermined width with respect to the radial direction when the ring 54 is formed. When the stator 54 having a substantially T-shaped cross section composed of the portions 70a to 70i, 71a to 71i and the salient pole portions 62a to 62i and combining the plurality of cores 54a to 54i into a ring shape is placed in the motor housing 59 In addition, each of the cores 54a to 54i is a motor that is in contact with the inner diameter portion of the connecting portions 70a to 70i and 71a to 71i and is not in contact with the outer diameter portion. Further, the inner diameter of the motor housing 59 was set smaller than the outer diameter of the ring when the entire connecting portions having the widths of the plurality of cores 54a to 54i were contacted with no gap.

  FIG. 6 is a conceptual diagram showing a comparison between the conventional motor and the housing and core of the motor of the present invention. FIG. 6A shows a case of a conventional type, which is formed when the inner diameter of the housing 80 and the cores 54a to 54i are brought into close contact with each other at the connecting portion, but the cores 54a to 54i have manufacturing tolerances. Therefore, there is no close contact as shown in FIG. Actually, for example, as shown in FIG. 6B, the inner diameter of the conventional housing 81 and the outer diameter of the ring formed when the cores 54a to 54i are brought into close contact with each other at the connecting portion are large. There are gaps in 90a to 90i and 91a to 91i. At this time, since the distance 1 between the contact points A, B and C is small, the pressing force is small and the rigidity is low. FIG. 6C shows a case where the inner diameter of the motor housing 82 of the present invention is set smaller than the outer diameter of the ring formed by contacting the entire connecting portions having a predetermined width of the plurality of cores 54a to 54i. . In this case, contact is made at the inner diameter portions 90a to 90i and 91a to 91i of the connecting portion.

  The operation of the core at this time will be described with reference to FIG. Here, the core 54a will be described as an example. The core 54a contacts the inner diameter portions 90a and 91a of the connecting portions 70a and 71a and the portion of the housing 59 at points 83 and 84. At this time, the forces acting on the core 54a are the forces R1, R2 received from the adjacent core and the forces P1, P2 received from the housing. It can be seen that the forces R1 and R2 act in the direction in which the generated forces R1 and R2 press the split core 54a against the inner diameter of the motor housing 59. At this time, since the forces P1 and P2 acting in the inner diameter direction of the motor housing 59 can be increased, a tightening force is generated, and the bending moment M is not generated because the point of action is below. Accordingly, high rigidity can be imparted, and the vibration of the outer core can be suppressed when the motor is energized, and the vibration is hardly transmitted to the housing.

  Next, a second embodiment will be described. In 2nd Embodiment, as shown in FIG. 8, the connection parts 93a-93i and 94a-94i of the cores 92a-92i contact the connection parts 93a-93i and 94a-94i of several cores 92a-92i without gaps. The outer diameter of the ring formed in this way was formed to be larger than the inner diameter of the motor housing 95. Thus, when the ring-shaped stator is assembled by combining the plurality of cores 92a to 92i in the motor housing 95, the cores 92a to 92i come into contact with each other at the inner diameter portions 96a to 96i and 97a to 97i of the connecting portions.

  Thereby, the cores 92a to 92i are connected to the inner diameter portions 96a to 96i, 97a to 97i of the connecting portion, the portion of the housing 95, and the points 98a to 98i, 99a, 99i by the action acting on the core described in the first embodiment. 97, contact. At this time, the forces acting on the core 94a are the forces R1, R2 received from the adjacent core and the forces P1, P2 received from the housing, as shown in FIG. It can be seen that the forces R1 and R2 act in a direction in which the generated forces R1 and R2 press the split core in the inner diameter direction of the motor housing 95. At this time, since the force P acting in the inner diameter direction of the motor housing 95 can be increased, a tightening force is generated, and the bending point M is not generated because the point of application is at the inner diameter portion. Accordingly, high rigidity can be imparted, and the vibration of the outer core can be suppressed when the motor is energized, and the vibration is hardly transmitted to the housing.

  In addition, although the case where the motor in this invention was used for an electric power steering apparatus was demonstrated, it is not restricted to this, It can be used as a motor in a steering-by-wire type steering apparatus.

  The present invention is used for a motor suitable for use in an electric power steering apparatus.

It is a figure showing the whole electric power steering device composition provided with the motor concerning the present invention. It is a figure shown in the concrete structure of the principal part of the mechanical mechanism of an electric power steering device, and an electric system. It is the sectional view on the AA line in FIG. FIG. 5 is a sectional view taken along line BB in FIG. 3. It is CC sectional view taken on the line of FIG. 4, and is a figure which shows the cross-section of a motor. It is a figure explaining the comparison with the past of the core part of the motor concerning a 1st embodiment of the present invention. It is a figure explaining the force which acts on the core part of the motor which concerns on this invention. It is a figure explaining the comparison with the past of the core part of the motor concerning a 2nd embodiment of the present invention. It is a figure which shows the cross-section of the conventional motor. It is a figure which shows the force which acts on each core in the conventional motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power steering apparatus 13 Pinion gear 14 Rack shaft 15 Pinion mechanism 18 Power transmission mechanism 19 Electric motor 19a Output shaft 36 Battery 49 Worm gear 50 Worm wheel 51 Rotating shaft 52 Rotor 52a-52h Permanent magnet 53a-53i Winding 54a-54i Core 62a- 62i Teeth Club

Claims (4)

A motor including a stator having a ring shape by combining a plurality of cores,
The shape of each core has a substantially T-shaped cross section composed of a connecting portion and a salient pole portion having a predetermined width with respect to the radial direction when the ring shape is formed,
When a stator having a ring shape by combining a plurality of the cores is housed in a motor housing,
Each of the cores is in contact with an inner diameter portion of the connecting portion and is not in contact with an outer diameter portion.   2. The motor according to claim 1, wherein an inner diameter of the motor housing is set to be smaller than an outer diameter of a ring when the entire connecting portion having the width of the plurality of cores is formed in contact with no gap. .   3. The motor according to claim 1, wherein the motor is a brushless motor including an inner rotor having a plurality of magnets and driven by a plurality of AC waveforms.   An electric power steering apparatus that generates a steering force by a motor and steers the vehicle, wherein the motor according to any one of claims 1 to 3 is used as the motor.

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