WO2018100953A1

WO2018100953A1 - Rotary drive source for electric actuator, and electric actuator

Info

Publication number: WO2018100953A1
Application number: PCT/JP2017/039256
Authority: WO
Inventors: 卓志松任; 公人牛田; 川合　正浩; 加藤　晃央
Original assignee: Ntn株式会社
Priority date: 2016-11-30
Filing date: 2017-10-31
Publication date: 2018-06-07
Also published as: JP2018093590A; JP6815852B2

Abstract

A position detection structure is provided with: a rotation side pulser ring having a magnetizing part for which N and S poles are arranged alternating along the circumference direction on the inner peripheral surface side; and a fixed side detection sensor that approaches and faces the magnetizing part of this pulser ring in the radial direction. The pulser ring of the position detection structure is overlapped in the axial direction at the inner diameter side of one of the axial direction end parts of the coil of the stator.

Description

Rotation drive source for electric actuator and electric actuator

The present invention relates to a rotary drive source for an electric actuator and an electric actuator.

An electric motor device (electric actuator) using a brushless DC motor generally includes a motor unit having a stator and a rotor, a rotation sensor for detecting the position of a magnetic pole of the rotor, and the like (Patent Document 1). That is, the motor unit of the electric motor device detects the position of the magnetic pole of the rotor with a rotation sensor, and based on the detected position, a portion (tooth portion) where the coil of the stator core is wound in the controller unit having a control function Is driven to generate a driving force by attracting and repelling magnetic force generated between the rotor and the stator core.

Generally, a target member (pulsar ring) is provided on the rotation side, and a Hall IC or the like constituting the rotation sensor is disposed on the fixed side facing the pulsar ring. The pulsar ring is provided with a support ring made of a torus, and a magnetized portion in which N and S poles of magnetic poles are alternately arranged along the circumferential direction on one end face of the support ring. ing. The Hall IC is disposed so as to face and oppose the magnetized portion.

JP 2008-109757 A

The target member (pulsar ring) is disposed such that its magnetized portion faces the axial direction, and the target member and the Hall IC are disposed at a predetermined interval along the axial direction. For this reason, the length in the axial direction of the electric motor device (electric actuator) is large, and disposing such a target member and the Hall IC hinders downsizing in the axial direction.

Therefore, in view of the above problems, the present invention provides a rotation drive source for an electric actuator and an electric actuator that can be made compact in the axial direction and can perform stable rotation control.

The rotational drive source for an electric actuator according to the present invention includes a motor unit having a stator and a rotor, and a drive source output shaft that is disposed on the inner diameter side of the rotor and outputs the rotation of the rotor. And a position detecting structure for the electric actuator, wherein the position detecting structure includes a magnetized portion in which N and S poles are alternately arranged along the circumferential direction on the inner peripheral surface side. A rotation-side pulsar ring, and a fixed-side detection sensor that opposes the magnetized portion of the pulsar ring in the radial direction. The pulsar ring of the position detection structure is connected to one axial end of the stator coil. It is overlapped in the axial direction on the inner diameter side of the part.

According to the rotary drive source for the electric actuator of the present invention, since it is overlapped in the axial direction on the inner diameter side of one axial end portion of the stator coil, the magnetized portion of the pulsar ring and the adjacent counter coil The detecting sensor to be arranged can be arranged along the radial direction. For this reason, it is possible to prevent the axial length from being increased due to the provision of the position detection structure, compared with the case where the magnetized portion and the detection sensor close to the magnetized portion are disposed along the axial direction. Can do.

The pulsar ring is composed of a support ring having a short cylindrical main body portion and the magnetized portion provided on the inner diameter surface of the main body portion of the support ring. The sensor can be set to have a hall sensor as a sensor. By setting in this way, the position detection structure can be stably arranged.

Also, it can be set such that at least the axial half of the support ring overlaps with one axial end of the stator coil in the axial direction. By setting in this way, the axial length can be reliably shortened.

The rotary motion type electric actuator can be configured by connecting a speed reducer to the drive source output shaft of the rotational drive source described above and connecting a final output shaft to the output side of the speed reducer.

Also, the linear motion type electric actuator can be configured by connecting a reduction gear to the drive source output shaft of the rotary drive source described above and connecting a motion conversion mechanism to the output side of the reduction gear.

According to the present invention, it is possible to reduce the size of the rotational drive source for the electric actuator and the electric actuator, and it is possible to perform stable rotation control.

It is a longitudinal cross-sectional view of the electric actuator concerning 1st Embodiment. FIG. 2 is a cross-sectional view of the electric actuator taken along the line BB in FIG. 1. FIG. 2 is a cross-sectional view of the electric actuator taken along the line CC in FIG. 1. It is an expanded sectional view of the area | region X in FIG. It is an expanded sectional view of the area | region Y in FIG. It is an expanded sectional view of the area | region Z in FIG. It is a front view of the pulsar ring used for the electric actuator which concerns on 1st Embodiment. It is sectional drawing of the pulsar ring used for the electric actuator which concerns on 1st Embodiment. It is sectional drawing which shows the electric actuator which concerns on the 2nd Embodiment of this invention. FIG. 9 is a cross-sectional view showing an electric actuator according to a second embodiment of the present invention, cut in a direction different from FIG. 8. It is an end view of the motor part of the electric actuator which concerns on the 2nd Embodiment of this invention. FIG. 11 is a cross-sectional view taken along line EE in FIG. 10. FIG. 12 is a transverse sectional view taken along the line FF in FIG. 11. It is a perspective view of the motor part of the electric actuator which concerns on the 2nd Embodiment of this invention. It is a front view of the pulsar ring used for the electric actuator which concerns on 2nd Embodiment. It is sectional drawing of the pulsar ring used for the electric actuator which concerns on 2nd Embodiment.

Embodiments of an electric actuator rotation drive source and an electric actuator including the rotation drive source according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a rotary motion type electric actuator as a first embodiment of the electric actuator. 2 is a cross-sectional view taken along line BB in FIG. 1, and FIG. 3 is a cross-sectional view taken along line CC in FIG. This rotary motion type electric actuator can be used, for example, for driving a robot arm or for electric power steering in a vehicle such as an automobile.

As shown in FIG. 1, an electric actuator according to the present invention includes a rotary drive source 1, a speed reducer 2 disposed on one axial side of the rotary drive source 1, and connected to the output side of the rotary drive source 1. The final output shaft 3 connected to the output side of the speed reducer 2 is a main component. Of the above components, the structure of the rotary drive source 1 will be described first.

Rotational drive source 1 includes a motor unit 5, a drive source output shaft 6, and a torque limiter 7. 1 and 2, the motor unit 5 includes an electric motor including a stator 51 fixed to the casing 8 and a rotor 52 disposed so as to face the inner side in the radial direction of the stator 51 with a gap. Consists of a motor. In this embodiment, a radial gap type is illustrated as an example of the electric motor.

The stator 51 includes a stator core 51a formed of a plurality of electromagnetic steel plates laminated in the axial direction, a bobbin 51b made of an insulating material attached to the stator core 51a, and a stator coil 51c wound around the bobbin 51b.

The rotor 52 includes an annular rotor core 52a, a plurality of magnets 52b attached to the outer periphery of the rotor core 52a, and an annular rotor inner 52c fixed to the inner periphery of the rotor core 52a. The rotor core 52a is formed of, for example, a plurality of electromagnetic steel plates stacked in the axial direction. The axial length of the rotor inner 52c is longer than the axial length of the rotor core 52a, and the rotor inner 52c protrudes on both axial sides of the rotor core 52a.

Bearings

53 and 54 arranged on both sides in the axial direction of the rotor core 52a are fixed to the outer peripheral surfaces of both ends in the axial direction of the rotor inner 52c, and the rotor inner 52c is rotatably supported by the casing 8 by the

bearings

53 and 54. Has been. As the

bearings

53 and 54, a rolling bearing capable of supporting both a radial load and a thrust load, for example, a deep groove ball bearing can be used.

An annular recess 521 having an inner diameter larger than that of the other part is formed on the inner peripheral surface of the rotor inner 52c. As shown in FIG. 1, the annular recess 521 is formed, for example, at an end portion on the other axial side of the rotor inner 52 c (opposite side from the reduction gear 2 side). A female serration 522 extending in the axial direction is formed on the inner peripheral surface of the annular recess 521.

As shown in FIG. 1, the drive source output shaft 6 is formed in a hollow cylindrical shape having both ends opened. Thus, by making the drive source output shaft 6 hollow, the rotary drive source 1 has a structure as a hollow motor. The outer peripheral surface of the drive source output shaft 6 is fitted to the inner peripheral surface (excluding the annular recess 521) of the rotor inner 52c with a clearance fit. Therefore, the drive source output shaft 6 can rotate independently of the rotor inner 52c. A male serration 6 a extending in the axial direction is formed on the outer peripheral surface of the end portion on the other axial side of the drive source output shaft 6.

An annular gap is formed between the inner peripheral surface of the annular recess 521 of the rotor inner 52c and the outer peripheral surface of the drive source output shaft 6 facing this. In the present embodiment, the torque limiter 7 is disposed in the annular gap.

The torque limiter 7 transmits the rotational power output from the motor unit 5 to the drive source output shaft 6. On the other hand, the torque limiter 7 interrupts torque transmission when an overload is applied, and the motor unit 5 and the drive source output shaft 6 are relative to each other. Rotation is allowed. As long as it has this function, the torque limiter 7 having an arbitrary configuration can be used. In this embodiment, as an example of the torque limiter 7, a case where a multi-plate clutch which is a kind of a friction clutch is used is illustrated.

FIG. 4 is an enlarged cross-sectional view of the region X in FIG. As shown in FIG. 4, the multi-plate clutch as the torque limiter 7 is disposed between the pair of

first friction plates

71 and 71 and the pair of

first friction plates

71 and 71 that are spaced apart in the axial direction. The second friction plate 72, an elastic member 73 such as a wave spring that press-contacts the first friction plate 71 and the second friction plate 72, and a pressing plate 74 are provided. The pressing plate 74 is positioned in the axial direction by a retaining ring 75 fitted in an annular groove on the inner peripheral surface of the rotor inner 52 c, and applies a predetermined pressing force (axial load) to the elastic member 73.

A female serration 522 extending in the axial direction is formed on the inner peripheral surface of the annular recess 521 provided in the rotor inner 52c, and the first friction plate 71 and the pressing plate 74 are fitted to the female serration 522. A male serration 6a extending in the axial direction is formed on the outer peripheral surface of the drive source output shaft 6, and a second friction plate 72 is fitted to the male serration 6a. A frictional force is generated between the first friction plate 71 and the second friction plate 72 by the biasing force of the elastic member 73.

When the torque acting between the motor unit 5 and the drive source output shaft 6 is equal to or less than the frictional force acting between the

friction plates

71 and 72, the

friction plates

71 and 72 rotate together. Rotational power is transmitted to the drive source output shaft 6 via both

friction plates

71 and 72. As a result, the speed reducer 2 connected to the drive source output shaft 6 and the final output shaft 3 connected to the output side of the speed reducer 2 are driven. On the other hand, if the torque acting between the motor unit 5 and the drive source output shaft 6 exceeds the friction force acting between the

friction plates

71 and 72, one friction plate slides with respect to the other friction plate. Torque transmission between the unit 5 and the drive source output shaft 6 is interrupted. Thereby, the relative rotation of the drive source output shaft 6 and the rotor inner 52c is allowed.

The casing 8 is divided at one place or a plurality of places in the axial direction for the convenience of assembly. In the present embodiment, the casing 8 is divided into a bottomed cylindrical bottom portion 81, a cylindrical portion 82 that is open at both ends, and a lid portion 83. A lid portion 83 is disposed on one axial side of the cylindrical portion 82, and a bottom portion 81 is disposed on the other axial side of the cylindrical portion 82. The bottom part 81, the cylinder part 82, and the cover part 83 are integrated using fastening means, such as a volt | bolt. Of the

bearings

53, 54 that support the rotor inner 52 c, the bearing 53 on one axial side is fixed to the inner peripheral surface of the cylindrical portion 82, and the bearing 54 on the other axial side is fixed to the inner peripheral surface of the bottom 81. The bottom portion 81 includes a cylindrical barrel portion 81a and a lid portion 81b that closes the opening portion of the barrel portion 81a on the side opposite to the final output shaft.

Next, the configuration of the speed reducer 2 which is a main component of the electric actuator will be described. In the present embodiment, a traction drive type planetary speed reducer is used as the speed reducer 2. The planetary speed reducer 2 includes a sun roller 21, an outer ring 22, a plurality of planetary rollers 23, and a carrier 24. As the sun roller 21, in this embodiment, an end portion on one side in the axial direction of the drive source output shaft 6 is used. Further, as the planetary roller 23, an outer ring of a rolling bearing 25 (for example, a deep groove ball bearing) is used. The inner ring of each rolling bearing 25 is press-fitted and fixed to the hollow shaft 26, and each hollow shaft 25 is supported by the carrier 24 so as to be able to rotate. The carrier 24 is rotatably supported with respect to the lid portion 83 of the casing 8 by a rolling bearing 27 (for example, a deep groove ball bearing) fixed to the outer peripheral surface thereof.

FIG. 5 is an enlarged cross-sectional view of the region Y in FIG. As shown in FIG. 5, the outer ring 22 integrally includes a main body portion 22a having a U-shaped cross section and flange portions 22b protruding on both sides in the axial direction of the main body portion 22a. In a state before the cylindrical portion 82 and the lid portion 83 of the casing 8 are joined, as shown by a solid line in the drawing, the outer ring 22 accommodated in the inner periphery of the cylindrical portion 82 has a flange portion 22b on one axial side. Projecting from the end face of the cylindrical portion 82. Thereafter, when the lid 83 is pushed in until it comes into contact with the end face of the cylindrical portion 82 and the both are coupled using a bolt or the like, the outer ring 22 pressed against the lid 83 is elastically deformed as indicated by a two-dot chain line, The portion 22a swells toward the inner diameter side (FIG. 4 shows the degree of elastic deformation exaggerated). Due to the elastic deformation of the outer ring 22, traction (preload) is applied to the contact portion between the outer ring 22 and the planetary roller 23, and further to the contact portion between the planetary roller 23 and the sun roller 21.

In the outer ring 22, a ring-shaped adjusting member 28 is disposed between the flange portion 22 b on the other axial side and the cylindrical portion 82. By selecting and using the adjusting member 28 having an appropriate thickness so that the protruding amount t of the flange portion 22b of the outer ring 22 from the end face of the cylindrical portion 82 is within a specified range before the lid portion 83 is assembled ( Matching), the degree of deformation of the outer ring 22 can be made uniform, and the traction applied to the inside of the speed reducer 2 can be made uniform.

The final output shaft 3 is fixed to the inner peripheral surface of the carrier 24 on the output side of the speed reducer 2 by means such as press fitting. The end portion on the other axial side of the final output shaft 3 is supported by the rolling bearing 31 so as to be rotatable with respect to the drive source output shaft 6.

In the electric actuator according to the first embodiment described above, the torque limiter 7 is disposed in the torque transmission path between the motor unit 5 and the drive source output shaft 6. During normal times, torque generated in the motor unit 5 is transmitted to the final output shaft 3 via the torque limiter 7, the drive source output shaft 6, and the speed reducer 2. As a result, the drive target connected to the final output shaft 3 is rotationally driven. On the other hand, even when the drive target collides with an obstacle, for example, and the rotation of the final output shaft 3 is locked, slippage occurs between the rotor inner 52c and the drive source output shaft 6 to interrupt the torque transmission path. Therefore, it is possible to prevent an excessive load from acting on the speed reducer 2 even in a situation where the motor unit 5 continues to rotate due to inertia. Therefore, damage to the speed reducer 2 can be prevented. On the contrary, even if the rotational torque on the motor side becomes extremely large for some reason, it is possible to prevent an excessive load from acting on the speed reducer 2 or the like.

Further, in the present invention, the torque limiter 7 is disposed between the inner peripheral surface of the rotor 52 (the inner peripheral surface of the rotor inner 52c) and the outer peripheral surface of the drive source output shaft 6 facing this. Therefore, compared with the case where the torque limiter 7 is disposed at the position adjacent to the motor unit 5 in the axial direction, the axial dimension of the rotary drive source 1 and further the electric actuator can be reduced. In order to effectively obtain the above effects, the torque limiter 7 (including the retaining ring 75) is preferably disposed between the two

bearings

53 and 54 that support the rotor inner 52c. More specifically, the torque limiter 7 is preferably disposed between the outer end faces P of the both bearings 53 and 54 (end faces that do not face the end faces of the mating bearings).

Incidentally, the motor portion of this electric actuator has a position detection structure 150 for rotation control on the side opposite to the final output shaft. As shown in FIG. 6, the position detection structure 150 includes a pulsar ring 151 (151 </ b> A) and a hall sensor (in this case, a hall IC 152 </ b> A) as the position detection sensor 152. Here, the Hall sensor is, for example, a semiconductor that detects the direction of a magnetic field and outputs a pulse signal corresponding to the direction. The Hall IC is a magnetic sensor in which a Hall element and a signal conversion circuit are incorporated in one package. The Hall element is an element that detects a magnetic field using the Hall effect.

As shown in FIGS. 7A and 7B, the pulsar ring 151A includes a support ring 153 (153A) and a magnetized portion (magnetic encoder) 154 (154A). That is, the support ring 153 (153A) is composed of a short cylindrical main body 153a and a flat ring-shaped inner flange 153b provided at the opening on the side opposite to the final output shaft of the main body 153a. A magnetized portion (magnetic encoder) 154 (154A) is formed on the inner peripheral surface of the main body 153a of 153A. The support ring 153 (153A) in this case includes a small diameter portion 155 on the inner flange portion side, a large diameter portion 156 on the opposite inner flange portion side, and a tapered portion 157 that connects the small diameter portion 155 and the large diameter portion 156. The magnetized portion (magnetic encoder) 154A is provided on the inner peripheral surface of the large diameter portion 156.

The support ring 153A is formed by pressing a ferromagnetic steel plate, for example, a ferritic stainless steel plate (JIS standard SUS430 system or the like) or a rust-proof cold-rolled steel sheet (JIS standard SPCC system or the like). It is formed. Further, the magnetized portion (magnetic encoder) 154A is made by mixing ferromagnetic powder made of ferrite or the like into an elastomer made of rubber or the like, so that the magnetic poles N and S are alternately arranged at predetermined equal intervals (equal pitch) in the circumferential direction. It is magnetized to become.

As shown in FIGS. 1, 2, and 6, the pulsar ring 151 (151A) is formed on the circumferential notch 158 of the rotor 52 in which the bearing 54 on the counter-final output shaft side is housed. The small diameter part 155 is inserted or press-fitted. For this reason, the pulsar ring 151 (151A) rotates integrally with the rotor 52.

Further, a circuit board 160 is attached to the lid 81b of the bottom 81, and three Hall ICs 152A arranged at a predetermined equal pitch are connected to the circuit board 160 along the circumferential direction. The Hall IC 152A is in close proximity to the magnetized portion (magnetic encoder) 154 of the pulsar ring 151A.

For this reason, in this position detection structure 150, the position of the magnetic pole of the rotor 52 is detected by a rotation sensor (detection sensor), and the controller core (not shown) having a control function is used for the stator core 51a based on the detected position. The driving force is generated by the attractive / repulsive force of the magnetic force generated between the rotor 52 and the stator core 51a while controlling the portion (tooth portion) around which the coil 51c is wound to be excited at an optimal timing. is there.

The pulsar ring 151 (151A) of the position detection structure 150 overlaps in the axial direction on the inner diameter side of one axial end of the coil 51c of the stator 51. That is, on the inner diameter side of the support ring 153 (153A) of the pulsar ring 151 (151A), three Hall ICs 152A as the detection sensors are arranged at a predetermined pitch along the circumferential direction, and at least the support ring 153 The axial half portion (in this case, the small diameter portion 155 of the support ring 153) overlaps one axial end of the coil of the stator in the axial direction.

As described above, in the first embodiment, the magnetized portion 154 (154A) of the pulsar ring 151 (151A) and the Hall IC 152A facing and close to the magnetized portion 154 can be arranged along the radial direction. For this reason, the axial direction length by providing the position detection structure 150 becomes larger than the case where the magnetized part 154 (154A) and the Hall IC 152A close to the magnetized part 154 are disposed along the axial direction. Thus, the axial length can be reliably shortened, and the position detection structure 150 can be stably disposed.

8 and 9 are sectional views of a linear motion type electric actuator as a second embodiment of the present invention. This linear motion type electric actuator can be used, for example, in an electric brake equipped in a vehicle such as an automobile. In the electric actuator of the second embodiment, the configuration from the motor unit 5 to the speed reducer 2 is common to the first embodiment. The second embodiment is different from the first embodiment in that a motion conversion mechanism 9 is used instead of the final output shaft 3.

The motion conversion mechanism 9 is constituted by a ball screw 91, for example. The ball screw 91 includes a ball screw nut 92, a ball screw shaft 93, a large number of balls 94, and a top (not shown) as a circulation member as main components. A spiral groove is formed on the inner peripheral surface of the ball screw nut 92, and a spiral groove is formed on the outer peripheral surface of the ball screw shaft 93. A ball 94 is loaded between the spiral grooves. A carrier 24 on the output side of the speed reducer 2 is fixed to the outer peripheral surface of the ball screw nut 92 by means such as press fitting.

A hollow cylindrical guide member 95 fixed to the bottom 81 of the casing 8 is disposed on the inner diameter side of the hollow drive source output shaft 6. A guide groove (not shown) extending in the axial direction is formed on the inner periphery of the guide member 95. Although not shown in detail, a protrusion protruding in the radial direction is provided on the ball screw shaft 93 by, for example, pressing a pin into a hole 93a provided at the other axial end of the ball screw shaft 93, and this protrusion is used as a guide member. By fitting in the 95 guide grooves, the ball screw shaft 93 can be prevented from rotating.

The casing 8 in the second embodiment includes a bottom portion 81, a cylindrical portion 82, a lid portion 83, and a pressurizing portion 84. The configurations and functions of the bottom 81 and the cylinder 82 are the same as those of the bottom 81 and the cylinder 82 described in the first embodiment. The pressurizing part 84 is sandwiched between the cylinder part 82 and the lid part 83. As in the first embodiment, the bottom 81, the cylinder 82, the lid 83, and the pressurizing part 84 are joined together by the bolt member 86 so that the end surface of the pressurizing part 84 is in pressure contact with the end surface of the cylindrical part 82. Then, the outer ring 22 pressed by the pressing portion 84 is elastically deformed toward the inner diameter side. Therefore, traction is given to the traction drive type planetary speed reducer 2.

The ball screw nut 92 is rotatably supported with respect to the lid portion 83 of the casing 8 by a double row rolling bearing 96 (for example, a double row deep groove ball bearing) fixed to the outer peripheral surface thereof. This rolling bearing 96 can support an axial load acting on the ball screw shaft 93. Further, the ball screw nut 92 can be supported at both ends to prevent the ball screw nut 92 from being inclined.

In the second embodiment, the torque of the motor unit 5 is transmitted to the ball screw nut 92 via the torque limiter 7, the drive source output shaft 6, and the speed reducer 2. Accordingly, by driving the motor unit 5 in the forward / reverse direction, the ball screw nut 92 can be rotated in the forward / reverse direction, and the ball screw shaft 93 can be moved back and forth (linear motion) in the axial direction.

In the second embodiment as well, as in the first embodiment, the torque limiter 7 is arranged in the torque transmission path on the downstream side of the motor unit 5, so that the ball screw shaft 93 comes into contact with the obstacle. Even in a situation where the extension is restricted, the torque transmission path can be blocked by causing a slip between the rotor inner 52c and the drive source output shaft 6. Accordingly, it is possible to prevent an excessive load from acting on the speed reducer 2 and the ball screw 91 and to prevent the speed reducer 2 and the ball screw 91 from being damaged.

Further, since the torque limiter 7 is disposed in the gap between the inner peripheral surface of the rotor 52 (rotor inner 52c) of the motor unit 5 and the outer peripheral surface of the drive source output shaft 6 facing the motor limiter 5, the motor unit 5 Compared with the case where the torque limiter 7 is arranged at the adjacent position in the axial direction, the size in the axial direction of the electric actuator can be reduced, and the electric actuator can be downsized.

Also in the second embodiment, the motor section of the electric actuator includes a position detection structure 150 having a pulsar ring 151 (151B) and a Hall IC 152A as the position detection sensor 152, as shown in FIGS. Prepare.

Like the pulsar ring 151 (151A) shown in FIGS. 7A and 7B, the pulsar ring 151 (151B) includes a support ring 153 (153B) and a magnetized portion (magnetic encoder) as shown in FIGS. 14A and 14B. ) 154 (154B). That is, the support ring 153 (153B) includes a short cylindrical main body portion 153a and a flat ring-shaped inner flange portion 153b provided in an opening on the side opposite to the final output shaft of the main body portion 153a. A magnetized portion (magnetic encoder) 154 (154B) is formed on the inner peripheral surface of the main body portion 153a. In this case, the main body portion 153a is a straight cylindrical surface having no stepped portions on the outer peripheral surface and the inner peripheral surface. A magnetized portion (magnetic encoder) 154B is provided on the inner peripheral surface of the main body portion 153a on the side opposite to the inner flange.

In this case, the material of the support ring 153B is the same as that of the support ring 153A, the material of the magnetized portion (magnetic encoder) 154B is the same as the material of the magnetized portion (magnetic encoder) 154B, and the circumferential direction is alternated. The magnetic poles N and S are magnetized so as to have a predetermined equal interval (equal pitch) in the circumferential direction.

As shown in FIGS. 8, 9, and 11 and the like, the pulsar ring 151B also has an inner flange of the support ring 153B in the circumferential cutout portion 158 of the rotor 52 in which the bearing 54 on the side opposite to the final output shaft is housed. The part side is inserted or press-fitted. For this reason, the pulsar ring 151 (151B) rotates integrally with the rotor.

Also in this case, the circuit board 160 is attached to the lid 81b of the bottom 81, and three Hall ICs 152A arranged at a predetermined equal pitch are connected to the circuit board 160 along the circumferential direction. . The Hall IC 152A is in close proximity to the magnetized portion (magnetic encoder) 154 of the pulsar ring 151.

Therefore, the pulsar ring 151B overlaps in the axial direction on the inner diameter side of one axial end of the coil 51c of the stator 51. That is, on the inner diameter side of the support ring 153B of the pulsar ring 151B, the three Hall ICs 152A as the detection sensors are arranged at a predetermined pitch along the circumferential direction, and at least the axial half portion of the support ring 153B That is, it overlaps with one axial end of the coil 51c of the stator 51 in the axial direction.

For this reason, similarly to the first embodiment, the magnetized portion 154B of the pulsar ring 151B and the detection sensor (Hall IC 152A) that faces and opposes the magnetized portion 154B can be disposed along the radial direction. For this reason, the axial direction length by providing the position detection structure 150 is larger than the case where it arrange | positions along the magnetizing part 154B part and the sensor for detection (Hall IC152A) which adjoins this, and an axial direction. The axial length can be reliably shortened, and the position detection structure 150 can be stably disposed.

Further, in the second embodiment, the screw shaft 93 of the ball screw 91 is accommodated by effectively utilizing the internal space formed on the inner peripheral surface of the drive source output shaft (hollow output shaft) 6, and the entire shaft Directional dimensions are also downsized. Further, a rotation prevention mechanism M is provided on the other axial side of the screw shaft 93 by effectively using the internal space.

The anti-rotation mechanism M of the screw shaft 93 includes a guide member 95, a pin 96 fitted in a hole penetrating in the radial direction of the screw shaft 93, and a guide collar 97 rotatably fitted on the pin 96. The guide member 95 is fixed to the bottom 81 of the casing 8, and the cylindrical portion 95 a of the guide member 95 is disposed between the inner peripheral surface of the hollow output shaft 6 and the outer peripheral surface of the screw shaft 93. A guide groove 95b is provided inside the cylindrical portion 95a, and a guide collar 97 is fitted therein. The guide collar 95 is made of a resin material such as PPS and enables smooth rotation. As a result, when the nut 92 rotates, the screw shaft 93 smoothly advances and retracts in the left-right direction in FIGS.

In this embodiment, the outer peripheral surface of the guide collar 97 is cylindrical, and the guide surface of the guide groove 95b in which the guide collar 97 is guided is exemplified by two parallel surfaces. However, the present invention is not limited to this. A guide surface composed of two V-shaped surfaces and a cylindrical guide surface may be used, and the outer peripheral surface of the guide collar 97 may have a shape corresponding to each guide surface.

Further, although the guide collar 95 is exemplified by a resin material, it is not limited to this and may be made of metal. Further, the guide collar 97 may be omitted, and the pin 96 may be directly engaged with the guide groove 95b.

As described above, in the direct acting electric actuator in which the motor unit 5 and the motion conversion mechanism 9 are coaxially disposed, the hollow rotor inner 52c and the nut 92 are disposed at positions that do not overlap in the axial direction, and the screw shaft 93 With the configuration in which the non-rotating mechanism M is provided on the radially inner side of the hollow rotor inner 52c, it is possible to reduce the size of the direct acting electric actuator, in particular, to reduce the size in the radial direction, and to improve the mountability.

In particular, in the linear motion type electric actuator as in the second embodiment, a space for the ball screw shaft 93 to move forward and backward is required. Therefore, when the motor unit 5 and the torque limiter 7 are arranged at adjacent positions in the axial direction. The ball screw shaft 93 that moves forward and backward may interfere with the torque limiter 7. In order to avoid this, the ball screw shaft 93 must be eccentrically arranged with respect to the shaft centers of the motor unit 5 and the torque limiter 7, and the size of the electric actuator increases.

On the other hand, in the second embodiment, the torque limiter 7 is arranged so as to overlap the rotor inner 52c and the drive source output shaft 6 in the radial direction, and the hollow drive source output shaft 6 is used. Thus, the rotary drive source 1 has a hollow structure, and a space for accommodating the ball screw shaft 93 is provided on the inner diameter side of the drive source output shaft 6. Therefore, the ball screw shaft 93 can be arranged coaxially with the motor unit 5 and further with the torque limiter 7, so that the linear motion type electric actuator can be miniaturized.

Further, when the electric actuator of the first embodiment (rotary motion type) shown in FIG. 1 is compared with the electric actuator of the second embodiment (linear motion type) shown in FIGS. The speed reducer 2 has a substantially common configuration. Therefore, the rotary drive source 1 and the speed reducer 2 can be shared by both types of electric actuators. That is, in the electric actuator of the first embodiment, the ball screw shaft 93 is used on the inner periphery of the drive source output shaft 6 by using the ball screw 91 without using the final output shaft 3. The electric actuator of the embodiment can be obtained. Thus, by sharing the rotary drive source 1 and the speed reducer 2, the cost of the electric actuator can be reduced. In addition, it is possible to strengthen the product development capabilities by making a series of rotary and linear motion electric actuators.

8 and 9, the motor unit 5 and the motion conversion mechanism 9 are coaxially arranged, but the nut 92 of the ball screw 91 is provided with respect to the hollow rotor inner 52c and the hollow output shaft 6. Since the structure does not overlap in the radial direction, the inner diameter D1 of the hollow rotor inner 52c, and further the inner diameter D2 of the hollow output shaft 6 can be made smaller than the outer diameter D3 of the nut 92 of the ball screw 91. Thereby, a small electric motor 29 can be used, and the direct-acting electric actuator can be reduced in size, particularly in the radial direction.

In the above description of the embodiment, a traction drive type planetary reduction gear is illustrated as the reduction gear 2. This is adopted in view of low backlash and low noise. The configuration of the speed reducer 2 is arbitrary, and a planetary gear speed reducer using a gear can be used as the speed reducer 2 when the need for the above-described advantages is scarce. Of course, a speed reducer having a configuration other than the planetary speed reducer can also be used.

Further, as a method for imparting traction to the traction drive type planetary speed reducer 2, the case where the outer ring 22 is deformed to the inner diameter side when the lid 83 is attached has been described, but a mechanism for imparting traction may be arbitrarily adopted. it can. For example, by pressing the outer ring 22 into the inner peripheral surface of the casing 8 with a predetermined tightening allowance, the outer ring 22 can be reduced in diameter toward the inner diameter side to impart traction to the speed reducer 2.

Moreover, although the above embodiment demonstrated the case where the torque limiter 7 was arrange | positioned in the internal peripheral surface of the edge part of the other side of the axial direction of the rotor inner 52c, the arrangement | positioning position of the torque limiter 7 is not specifically limited, The rotor inner 52c It can arrange | position in arbitrary positions in the clearance gap between the inner peripheral surface of this, and the outer peripheral surface of the drive source output shaft 6. FIG. For example, the torque limiter 7 can be disposed on the inner peripheral surface of the end portion on the one axial side of the rotor inner 52c.

In the above description, a radial gap type electric motor is exemplified as the motor unit 5, but a motor having an arbitrary configuration can be adopted. For example, an axial gap type electric motor including a stator fixed to a casing and a rotor arranged so as to face the inner side in the axial direction of the stator with a gap may be used.

As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. In the embodiment, the pulsar ring 151 of the position detection structure 150 is used as the stator 51. The coil 51c was overlapped in the axial direction on the inner diameter side of the axial end of one of the coils 51c (in FIG. 1, the anti-final output shaft side, in FIGS. 8 and 9). The pulsar ring 151 of the position detection structure 150 is moved in the axial direction on the inner diameter side of the axial end of the other coil 51c of the stator 51 (the final output shaft side in FIG. 1 and the motion conversion mechanism side in FIGS. 8 and 9). You may make it overlap.

In each embodiment, the entire pulsar ring 151 is not overlapped with the coil 51c of the stator 51, but the entire pulsar ring 151 may be overlapped. Note that the number of Hall ICs constituting the detection sensor is not limited to three. Even if the position detection structure of the electric actuator of the first embodiment is replaced with the position detection structure of the electric actuator of the second embodiment, the position detection structure of the electric actuator of the second embodiment is You may replace with the position detection structure of the electric actuator of embodiment.

The electric actuator can be a rotary motion type that is optimal for driving a robot arm or an electric power steering in a vehicle such as an automobile, or a linear motion type that is optimal for an electric brake equipped in a vehicle such as an automobile.

1 Rotation drive source 2 Reducer (Planet reducer)
3 Final output shaft 5 Motor unit 6 Drive source output shaft (hollow output shaft)
9 Motion Conversion Mechanism 51 Stator 51c Stator Coil 52 Rotor 150

Position Detection Structures

151, 151A, 151B Pulsar Ring 152

Position Detection Sensors

153, 153A, 153B Support Rings 154.154A, 154B Magnetized Part Hall Sensor (Hall IC) 152A

Claims

An electric actuator comprising: a motor unit having a stator and a rotor; and a drive source output shaft that is disposed on an inner diameter side of the rotor and outputs rotation of the rotor, and the motor unit includes a position detection structure for rotation control. Rotational drive source for
The position detection structure includes a pulsar ring on the rotating side having a magnetized portion in which N and S poles are alternately arranged along the circumferential direction on the inner peripheral surface side, and a radial direction on the magnetized portion of the pulsar ring. An electric actuator comprising: a fixed-side detection sensor that is in close proximity to each other, and the pulsar ring of this position detection structure is overlapped in the axial direction on the inner diameter side of one axial end of the stator coil Rotation drive source.
The pulsar ring is composed of a support ring having a short cylindrical main body portion and the magnetized portion provided on the inner diameter surface of the main body portion of the support ring. The rotary drive source for an electric actuator according to claim 1, wherein a hall sensor as a sensor is disposed.
3. The rotational drive source for an electric actuator according to claim 2, wherein at least a half portion in the axial direction of the support ring overlaps with one axial end of the coil of the stator in the axial direction.
An electric actuator comprising: a reduction gear connected to the drive source output shaft of the rotary drive source according to any one of claims 1 to 3; and a final output shaft connected to the output side of the reduction gear.
An electric actuator characterized in that a speed reducer is connected to the drive source output shaft of the rotary drive source according to any one of claims 1 to 3, and a motion conversion mechanism is connected to the output side of the speed reducer.