JP2014161222A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to highly accurately control the rotation angle of an actuator even when brake is applied by a brake.SOLUTION: An actuator 100 comprises: three motors 106; three crank shafts 132 rotated integrally with the motor shafts 108 of the three motors 106; an eccentric body 136 provided on each of the three crank shafts 132 in the same phase; an external teeth gear 144 integrated in the periphery of the eccentric body 136 so as to be able to swing and rotate; and an internal teeth gear 150 that engages the inside of the external teeth gear 144. In the actuator 100, all the three motor shafts 108 are provided with brakes 126 for braking the three crank shafts. Further, one crank shaft 132A is provided with an encoder 160A for detecting the rotation angle of the crank shaft 132A.

Description

  The present invention relates to an actuator.

  Patent Document 1 discloses four motors, four crankshafts that rotate integrally with the motor shafts of the four motors, eccentric bodies provided on the four crankshafts in the same phase, and the eccentric bodies. An actuator having an external gear incorporated on the outer periphery of the external gear so as to be able to swing and rotate, and an internal gear internally engaged with the external gear is disclosed. In this actuator, when the motor shafts of the four motors rotate, the external gears oscillate and rotate via the four crank shafts, and an output can be obtained from the internal gears. A brake is provided on the motor shaft, and the rotation of the crankshaft is braked by the brake. This actuator further includes an encoder.

WO2009 / 081840

  However, in Patent Document 1, the brakes that brake the rotation of the crankshaft are provided not in all of the four motor shafts but in only a part thereof. For this reason, a crankshaft without a brake is braked by a brake provided on another motor shaft. For this reason, a crankshaft not provided with a brake is subjected to a load opposite to that of the crankshaft provided with a brake and is braked. That is, when the brake is braked, the crankshaft without the brake may be out of phase with the crankshaft with the brake due to backlash or the like, and stable brake braking cannot be expected. In Patent Document 1, an encoder is provided only on a crankshaft that is not provided with a brake. For this reason, the rotation angle detected by the encoder may be different from the rotation angle of the crankshaft provided with the brake. That is, even if it is attempted to precisely control the actuator with the encoder, the configuration disclosed in Patent Document 1 may not be able to achieve sufficient precision control of the actuator.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an actuator that enables highly accurate rotation angle control even when braking is performed by a brake.

  The present invention relates to a plurality of motors, a plurality of crankshafts that rotate integrally with the motor shafts of the plurality of motors, an eccentric body provided in the same phase on each of the plurality of crankshafts, In an actuator having an external gear incorporated in an outer periphery so as to be able to swing and rotate, and an internal gear internally engaged with the external gear, each of the plurality of crankshafts or the plurality of motor shafts is provided with each crank. A brake for braking the shaft is provided, and an encoder for detecting a rotation angle of the crankshaft is provided on at least one of the crankshaft or the motor shaft, thereby solving the above-mentioned problem. .

  In the present invention, brakes are provided on all of the plurality of crankshafts or motor shafts. For this reason, since all the crankshafts are braked by the brake, for example, it is possible to prevent a reverse load from being applied to only a part of the crankshafts and to prevent a rotational angle shift only from the crankshafts. An encoder is provided on at least one crankshaft or motor shaft. Since the encoder is provided on the crankshaft or the motor shaft provided with the brake, the error of the rotation angle detected by the encoder can be minimized even when the brake is applied.

  At the same time, in the present invention, since brakes are provided on all the crankshafts, the load applied to each crankshaft is equalized by the braking of the brakes, and the load applied to each crankshaft can be further reduced. For this reason, it is possible to prevent only a part of the crankshaft from being fatigued, and to extend the life of the actuator.

  The encoder may be provided only on one crankshaft or motor shaft, but may be provided on another crankshaft or all crankshafts or motor shafts. In this case, even if a slight deviation occurs in the braking timing of each crankshaft, the rotation angle of the actuator can be obtained with higher accuracy from the detection result of each encoder.

  According to the present invention, it is possible to perform highly accurate rotation angle control of an actuator even when braking is performed by a brake.

Sectional drawing of the actuator to which an example of embodiment of this invention was applied Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view of an actuator to which an example of an embodiment of the present invention is applied. FIG. 1 is a cross-sectional view so that the difference between the two motors 106A and 106B can be seen. 2 and 3 are a cross-sectional view taken along line II-II in FIG. 1 and a cross-sectional view taken along line III-III in FIG. A schematic configuration will be described below.

  As shown in FIG. 1, the actuator 100 includes three (plural) motors 106A to 106C (hereinafter referred to as motor 106), brakes 126A to 126C (hereinafter referred to as brake 126), a speed reduction mechanism 130, an encoder 160A (the motor 106C and the brake 126C are not shown). Here, the speed reduction mechanism 130 includes three crankshafts 132A to 132C (hereinafter referred to as crankshafts 132) rotated by motor shafts 108A to 108C (hereinafter referred to as motor shafts 108) of the three motors 106, respectively. Eccentric bodies 136A to 136C (hereinafter referred to as eccentric bodies 136) provided on the three crankshafts 132 in the same phase (the motor shaft 108C, the crankshaft 132C, and the eccentric body 136C are not shown). . Furthermore, the speed reduction mechanism 130 has an external gear 144 that is incorporated on the outer periphery of the eccentric body 136 so as to be able to swing and rotate, and an internal gear 150 that is in mesh with the external gear 144. The brake 126 is provided on all three motor shafts 108 so as to brake the three crankshafts 132. The encoder 160A is provided on the crankshaft 132A so as to detect the rotation angle of the crankshaft 132A.

  As shown in FIG. 1, a cylindrical member 102 is incorporated in the actuator 100 along the axial direction O. For this reason, the actuator 100 can pass piping or wiring through the through-hole 104 of the cylindrical member 102. That is, all the components are arranged outside the inner diameter d1 of the cylindrical member 102.

  Hereinafter, each component will be described in detail.

  First, the motor 106A and the brake 126A will be mainly described. In the present embodiment, the motor 106A and the brake 126A are the same as the motor 106B (106C) and the brake 126B (126C), respectively, and therefore description thereof is omitted.

  The motor 106A includes a motor shaft 108A, a rotor 116A, and a stator 118A. A rotor 116A is integrally supported and fixed to the rotor shaft portion 110A of the motor shaft 108A. A permanent magnet is formed on the surface of the rotor 116A.

  On the other hand, the stator 118A is attached and fixed to the inner side of the main body casing 120 at a predetermined interval from the outer periphery of the rotor 116A supported and fixed to the rotor shaft portion 110A. An intermediate cover 122 is fixed to the main body casing 120 with bolts 182 so as to cover at least the side surface of the stator 118A (the right side in FIG. 1 and FIG. 2). The fixed portion 125A constituting a brake 126A described later is attached to the middle cover 122. The bearing 166A is supported by the fixed portion 125A. Further, a brake cover 128 for covering the brake 126A is attached to the middle cover 122 by bolts 184. The main body casing 120 is provided with a bolt hole 186 for attaching to the counterpart machine.

  The brake 126A includes a movable part 124A and a fixed part 125A. The movable portion 124A is a brake disk or the like, is attached to the shaft tip portion 114A of the motor shaft 108A, and rotates integrally with the motor shaft 108A. The fixed portion 125A is provided with an electromagnetic coil or a movable iron core that imparts a frictional force to the brake disk by being given displacement by an electromagnetic coil, and is fixed to a main body casing 120 described later. For this reason, the rotation of the motor shaft 108A can be freely braked by controlling the voltage applied to the electromagnetic coil.

  Thus, the motor 106A and the brake 126A are small in size and are arranged in a width d3 between the inner diameter d1 of the cylindrical member 102 and the outer diameter d2 of the brake cover 128. However, even if the motor 106A and the brake 126A are small in size, three motors 106A and three brakes 126A are arranged at equal intervals in the circumferential direction between the widths d3. For this reason, the rotational torque and braking torque transmitted to the speed reduction mechanism 130 can be increased.

  Next, the speed reduction mechanism 130 and the encoder 160A will be mainly described. The crankshaft 132A is the same as the other crankshafts 132B and 132C except for the shaft tip portion 140A of the crankshaft 132A where the encoder 160A is provided. For this reason, the description of the crankshafts 132B and 132C and the members with the lower-order alphabetic characters related to the crankshafts 132B and 132C are omitted.

  The speed reduction mechanism 130 includes an eccentric body 136, an external gear 144, and an internal gear 150. When attention is paid to one crankshaft 132A, a pair of eccentric bodies 136A are integrally formed in a state of being shifted from each other by 180 degrees. The pair of eccentric bodies 136 are provided on the three crankshafts 132 in the same phase. That is, by controlling the rotation of the three motor shafts 108, the eccentric bodies 136 on the three crankshafts 132 can be rotated in the same direction and the same speed in the same phase. The external gear 144 includes eccentric body holes 148A to 148C (hereinafter referred to as eccentric body holes 148) (see FIG. 3). Roller bearings 142 </ b> A to 142 </ b> C (hereinafter referred to as roller bearings 142) are disposed between the eccentric hole 148 and the eccentric body 136. For this reason, the external gear 144 is fitted to the outer periphery of the eccentric body 136 via the roller bearing 142.

  The external gear 144 is inscribed in the internal gear 150. The internal gear 150 is integrated with the output member 152. Specifically, the internal teeth 151 of the internal gear 150 are configured by pins (see FIG. 3), and the number calculated from the minimum interval P in the circumferential direction (the number of teeth of the internal gear 150) is an external tooth. More than the number of teeth of the gear 144 is set. The reduction ratio of the reduction mechanism 130 is determined from the difference in the number of teeth between the number of teeth of the internal gear 150 and the number of teeth of the external gear 144 and the number of teeth of the external gear 144. A plurality (six in this embodiment) of column holes 145 are formed in the external gear 144 at regular intervals in the circumferential direction (see FIG. 3). A column portion 155 that is integrally projected from the carrier plate 156 is loosely fitted in the column hole 145. The carrier plate 156 is fixed to the main body casing 120 by being connected to the extending portion 154 formed integrally extending from the main body casing 120 in the axial direction O with a bolt 190. Note that a carrier 158 is constituted by the extending portion 154 and the carrier plate 156. The external gear 144 is formed with a central shaft hole 146 in which the cylindrical member 102 is loosely fitted.

  The output member 152 is rotatably supported on the outer periphery of the carrier 158 by a pair of bearings 170 and 172. In the present embodiment, the output of the actuator 100 is transmitted from the output member 152 to the counterpart machine by fixing the main body casing 120 to the casing of the counterpart machine using the bolt holes 186. However, the output member 152 may be fixed to the casing of the counterpart machine using the bolt hole 188, and the output of the actuator 100 may be transmitted from the main body casing 120 to the counterpart machine. The outer diameter d4 of the output member 152 is made larger than the outer diameter d3 of the brake cover, so that a large torque can be output.

  The crankshaft 132A is integrally formed with the motor shaft 108A. That is, the motor shaft 108A is also used as the crank shaft 132A. The motor shaft 108A is rotatably supported with respect to the main body casing 120 by a bearing 166A at the shaft end portion 112A. In other words, the motor shaft 108A is supported by the bearing 166A at the end on the side opposite to the eccentric body of the motor 106A. On the other hand, the crankshaft 132A is rotatably supported at its shaft end 138A by a bearing 168A. In other words, the crankshaft 132A is supported by the bearing 168A at the non-motor side end of the eccentric body 136A. The bearing 168A is supported by the carrier plate 156 described above. Since the motor shaft 108A and the crankshaft 132A are integrally formed, the motor shaft 108A and the crankshaft 132A are supported by the main body casing 120 and the carrier plate 156 with only two bearings 166A and 168A. For this reason, in this embodiment, the span L1 between the two bearings 166A and 168A can be made longer than in the case where the bearing is arranged at the shaft center 134A of the crankshaft 132A instead of the bearing 166A and supported by the bearing. . That is, even if an inexpensive bearing such as a ball bearing is used for both the bearings 166A and 168A, the shaft runout of the crankshaft 132A (motor shaft 108A) that can occur if the span is short can be reduced. For this reason, the crankshaft 132B (132C) using the bearings 166B (166C) and 168B (168C) can similarly reduce the shaft runout. Hereinafter, the bearings 166A to 166C and 168A to 168C are referred to as bearings 166 and 168, respectively.

  The encoder 160A includes a movable part 161A and a fixed part 162A. The movable portion 161A is a slit plate or the like, is attached to the shaft tip portion 140A of the crankshaft 132A, and rotates integrally with the crankshaft 132A. The fixing portion 162A includes a light emitting element and a light receiving element that receives light that has passed through the slit of the slit plate, and the fixing portion 162A is fixed to the carrier plate 156. For this reason, the encoder 160A can detect the rotation angle of the crankshaft 132A. Note that an encoder cover 164A is attached to the carrier plate 156 so as to cover the encoder 160A.

  The thickness t1 in the axial direction O necessary for the encoder 160A is considered to be from the shaft tip portion 140A of the crankshaft 132A to the encoder cover 164A. Here, the carrier plate 156 supports an output member 152 that outputs the actuator 100 via a bearing 172. That is, since it is necessary to support a large output torque (including braking torque) by the carrier plate 156, the carrier plate 156 needs to have a corresponding thickness t2 in order to have high rigidity. For this reason, as shown in FIG. 1, by incorporating the encoder 160A into the carrier plate 156, the thickness t1 is offset in terms of arrangement with the thickness t2, and the protruding length in the axial direction O can be set to t3. That is, for example, the protrusion length t3 can be shortened and the increase in the length of the actuator 100 in the axial direction O can be minimized as compared with the case where the encoder is provided outside the brake (right side in FIG. 1).

  Reference numerals 174A, 176A, 178, 180 are oil seals for sealing the lubricant used in the speed reduction mechanism 130.

  Next, the operation of the actuator 100 will be described.

  The motor shafts 108 of the three motors 106 are simultaneously rotated by an electric signal from a motor driver (not shown). At this time, the three motors 106 may be controlled by one motor driver, or may be controlled by separate motor drivers. As a result, the three crankshafts 132 integrally formed with the motor shaft 108 rotate, and the eccentric bodies 136 respectively provided on the crankshafts 132 have the same phase and the same speed in the same direction. Rotate with.

  As a result, the external gear 144 fitted to each eccentric body 136 via the roller bearing 142 is swung, and the external gear 144 and the internal gear 150 are engaged with each other. Here, the column portion 155 of the carrier plate 156 that is loosely fitted in the column hole 145 of the external gear 144 is fixed to the main body casing 120 (attached and fixed to the counterpart machine). For this reason, each time the eccentric body 136 rotates, the internal gear 150 rotates by a difference in the number of teeth from the external gear 144. That is, the output member 152 integrated with the internal gear 150 rotates with respect to the main body casing 120. The rotation angle of the output member 152 at this time can be obtained by multiplying the rotation angle of the crankshaft 132A detected by the encoder 160A by the reduction ratio of the reduction mechanism 130. The swing component of the external gear 144 is absorbed by loose fitting between the column portion 155 of the carrier plate 156 and the column hole 145.

  Here, brakes 126 are provided on all three motor shafts 108. For this reason, all the three crankshafts 132 are braked by the brake 126 by applying all the brakes 126. In other words, it is possible to prevent a reverse load from being applied to only a part of the crankshaft and a rotational angle shift to occur only on the crankshaft. An encoder 160A is provided on one crankshaft 132A. Since the encoder 160A is provided on the crankshaft 132A provided with the brake 126A, an error in the rotation angle detected by the encoder 160A can be minimized even when braking is performed by the brake 160A.

  At the same time, in this embodiment, since the brakes 126 are provided on all the crankshafts 132, the load applied to each crankshaft 132 is equalized by the braking of the brake 126, and the load applied to each crankshaft 132 is further reduced. Can do. For this reason, only a part of the crankshaft can be prevented from being fatigued, and the actuator 100 can have a long life.

  The encoder 160A is disposed in the vicinity of the eccentric body 136A and at the tip portion 140A of the crankshaft 132A. That is, the encoder 160A is arranged on the crankshaft 132A on the side opposite to the axial direction O of the eccentric body 136A. For this reason, the encoder 160A can be easily attached regardless of the motor 106A. Further, since the bearing 168A supports the vicinity of the encoder 160A of the crankshaft 132A, the rotation angle of the crankshaft 132A can be detected more accurately.

  Further, as shown in FIG. 1, the encoder 160 </ b> A is disposed on the carrier plate 156 on the inner side of the output member 152 at the shaft tip portion 140 </ b> A of the crankshaft 132 </ b> A opposite to the brake 126 </ b> A in the axial direction O. Therefore, while the rotation angle can be detected with high accuracy, the protruding length t3 of the encoder 160A to the outside of the actuator 100 in the axial direction O can be reduced. That is, an increase in the length of the actuator 100 in the axial direction O can be minimized.

  Note that the protrusion length t3 can be eliminated by increasing the axial length of the output member 152. In that case, the span L2 between the bearings 170 and 172 supporting the output member 152 can be lengthened. For this reason, the rotational runout of the output member can be further reduced.

  Further, the crankshaft 132 and the motor shaft 108 are integrally formed, and the motor shaft 108 is supported by the bearing 166 at the end portion on the side opposite to the eccentric body of the motor 106. For this reason, shaft runout of the motor shaft 108 can be reduced. In addition, the load on the motor shaft 108 from the brake 126 on the side opposite to the eccentric body of the motor 106 can be supported by the main body casing 120. That is, the rotation of the motor 106 can be stabilized and the life of the motor 106 can be extended.

  Further, the motor shaft 108A is supported by a bearing 166A at the opposite end of the motor 106A, and the crankshaft 132A is supported by the bearing 168A at the opposite end of the eccentric 136A. That is, the crankshaft 132A and the motor shaft 108A are supported by only the two bearings 166A and 168A. That is, the span L1 between the bearings 166A and 168A can be increased. For this reason, for example, it is possible to prevent the occurrence of an encoder error due to a shaft runout at the encoder due to a short span between the bearings. That is, the shaft runout of the crankshaft 132A can be reduced to the minimum, and the rotation angle can be detected with high accuracy by the encoder 160A. At the same time, since the bearings 166A and 168A are ball bearings and no other bearings are provided, it is possible to reduce the shaft runout of the crankshaft 132A at a low cost.

  That is, according to the present embodiment, even when braking by the brake 126 is performed, it is possible to control the rotation angle of the actuator 100 with high accuracy. The actuator includes a through-hole 104 in the direction of the central axis O, and can be high in output while being compact in outer dimensions such as an outer diameter size and an axial length.

  Although the present invention has been described with reference to the present embodiment, the present invention is not limited to the present embodiment. That is, it goes without saying that improvements and design changes can be made without departing from the scope of the present invention.

  In the above embodiment, there are three motors 106, and accordingly, there are three motor shafts 108, crank shafts 132, eccentric bodies 136, etc., but the present invention is not limited to this, and two or more of them are included. It suffices if there is a plurality.

  In the above embodiment, the encoder 160A is provided on one crankshaft 132A, but the present invention is not limited to this. For example, it may be provided on another crankshaft or all crankshafts or motor shafts. In this case, even if a slight deviation occurs in the braking timing of each crankshaft, the rotation angle of the actuator can be obtained with higher accuracy from the detection result of each encoder.

  Moreover, in the said embodiment, although the motor shaft 108 and the crankshaft 132 were integrally formed, this invention is not limited to this. For example, the motor shaft and the crankshaft may rotate together via a joint.

  In the above embodiment, the brake 126 is provided at the shaft tip 114 of the motor shaft 108 and the encoder 160A is provided at the shaft tip 140A of the crankshaft 132A. However, the present invention is not limited to this. For example, the encoder and the brake may be reversely arranged, or both the encoder and the brake may be provided at one shaft end. Alternatively, a brake and / or an encoder may be disposed between the motor shaft and the crankshaft, that is, between the eccentric body and the motor.

  In the above embodiment, the motor shaft 108A and the crankshaft 132A are supported by the two bearings 166A and 168A, and the brake 126A and the encoder 160A are provided on the outer sides thereof. However, the present invention is not limited to this. Not. For example, a bearing may be further arranged between the motor and the eccentric body to support three points, or a bearing may be arranged outside the brake and encoder in the axial direction O. Furthermore, bearings may be arranged at the tip of the crankshaft and between the motor and the eccentric body to provide two-point support.

  The actuator of the present invention has a through hole in the central axis O direction, can be compact with external dimensions such as the outer diameter size and axial length, and can control the rotation angle with high output and high accuracy. . For this reason, the applicability can be further expanded in various applications such as a robot apparatus and a transfer apparatus that are small, require high output, and require precise control.

DESCRIPTION OF SYMBOLS 100 ... Actuator 102 ... Cylindrical member 104 ... Through-hole 106, 106A, 106B, 106C ... Motor 108, 108A, 108B, 108C ... Motor shaft 110A, 110B ... Rotor shaft part 112A, 112B, 138A, 138B ... Shaft end part 114A, 114B, 140A, 140B ... shaft tip 116A, 116B ... rotor 118A, 118B ... stator 120 ... main body casing 122 ... middle cover 124A, 161A ... movable part 125A, 162A ... fixed part 126, 126A, 126B, 126C ... brake 128 ... Brake cover 130 ... Deceleration mechanism 132, 132A, 132B, 132C ... Crankshaft 134A, 134B ... Shaft center 136, 136A, 136B, 136C ... Eccentric body 142, 142A, 142B, 142C Roller bearing 144 ... External gear 145 ... Column hole 146 ... Center shaft hole 148, 148A, 148B, 148C ... Eccentric body hole 150 ... Internal gear 151 ... Internal tooth 152 ... Output member 154 ... Extension part 155 ... Column part 156 ... Carrier plate 158 ... Carrier 160A ... Encoder 164A ... Encoder cover 166, 166A, 166B, 166C, 168, 168A, 168B, 168C, 170, 172 ... Bearings 174A, 174B, 176A, 176B, 178, 180 ... Oil seal 182, 184, 186, 188, 190 ... bolts or bolt holes

  The present invention relates to an actuator.

  Patent Document 1 discloses four motors, four crankshafts that rotate integrally with the motor shafts of the four motors, eccentric bodies provided on the four crankshafts in the same phase, and the eccentric bodies. An actuator having an external gear incorporated on the outer periphery of the external gear so as to be able to swing and rotate, and an internal gear internally engaged with the external gear is disclosed. In this actuator, when the motor shafts of the four motors rotate, the external gears oscillate and rotate via the four crank shafts, and an output can be obtained from the internal gears. A brake is provided on the motor shaft, and the rotation of the crankshaft is braked by the brake. This actuator further includes an encoder.

WO2009 / 081840

It is an object of the present invention to provide an actuator that suppresses an increase in axial length .

The present invention includes a several crankshaft double, a plurality of motors connected to the crank shaft each several plurality, an eccentric body provided on each crankshaft, the swing rotatably on the outer periphery of the eccentric body an external gear incorporated, the internal gear inscribed meshing with external gear, the actuator having a carrier for supporting the crankshaft in the crankshaft of a single even without low, the eccentric body On the other hand, the encoder is provided on the side opposite to the motor in the axial direction , and the encoder is incorporated inside the carrier to solve the above problem.

According to the present invention, it is possible to suppress an increase in axial length .

Sectional drawing of the actuator to which an example of embodiment of this invention was applied Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view of an actuator to which an example of an embodiment of the present invention is applied. FIG. 1 is a cross-sectional view so that the difference between the two motors 106A and 106B can be seen. 2 and 3 are a cross-sectional view taken along line II-II in FIG. 1 and a cross-sectional view taken along line III-III in FIG. A schematic configuration will be described below.

  As shown in FIG. 1, the actuator 100 includes three (plural) motors 106A to 106C (hereinafter referred to as motor 106), brakes 126A to 126C (hereinafter referred to as brake 126), a speed reduction mechanism 130, an encoder 160A (the motor 106C and the brake 126C are not shown). Here, the speed reduction mechanism 130 includes three crankshafts 132A to 132C (hereinafter referred to as crankshafts 132) rotated by motor shafts 108A to 108C (hereinafter referred to as motor shafts 108) of the three motors 106, respectively. Eccentric bodies 136A to 136C (hereinafter referred to as eccentric bodies 136) provided on the three crankshafts 132 in the same phase (the motor shaft 108C, the crankshaft 132C, and the eccentric body 136C are not shown). . Furthermore, the speed reduction mechanism 130 has an external gear 144 that is incorporated on the outer periphery of the eccentric body 136 so as to be able to swing and rotate, and an internal gear 150 that is in mesh with the external gear 144. The brake 126 is provided on all three motor shafts 108 so as to brake the three crankshafts 132. The encoder 160A is provided on the crankshaft 132A so as to detect the rotation angle of the crankshaft 132A.

  As shown in FIG. 1, a cylindrical member 102 is incorporated in the actuator 100 along the axial direction O. For this reason, the actuator 100 can pass piping or wiring through the through-hole 104 of the cylindrical member 102. That is, all the components are arranged outside the inner diameter d1 of the cylindrical member 102.

  Hereinafter, each component will be described in detail.

  First, the motor 106A and the brake 126A will be mainly described. In the present embodiment, the motor 106A and the brake 126A are the same as the motor 106B (106C) and the brake 126B (126C), respectively, and therefore description thereof is omitted.

  The motor 106A includes a motor shaft 108A, a rotor 116A, and a stator 118A. A rotor 116A is integrally supported and fixed to the rotor shaft portion 110A of the motor shaft 108A. A permanent magnet is formed on the surface of the rotor 116A.

  On the other hand, the stator 118A is attached and fixed to the inner side of the main body casing 120 at a predetermined interval from the outer periphery of the rotor 116A supported and fixed to the rotor shaft portion 110A. An intermediate cover 122 is fixed to the main body casing 120 with bolts 182 so as to cover at least the side surface of the stator 118A (the right side in FIG. 1 and FIG. 2). The fixed portion 125A constituting a brake 126A described later is attached to the middle cover 122. The bearing 166A is supported by the fixed portion 125A. Further, a brake cover 128 for covering the brake 126A is attached to the middle cover 122 by bolts 184. The main body casing 120 is provided with a bolt hole 186 for attaching to the counterpart machine.

  The brake 126A includes a movable part 124A and a fixed part 125A. The movable portion 124A is a brake disk or the like, is attached to the shaft tip portion 114A of the motor shaft 108A, and rotates integrally with the motor shaft 108A. The fixed portion 125A is provided with an electromagnetic coil or a movable iron core that imparts a frictional force to the brake disk by being given displacement by an electromagnetic coil, and is fixed to a main body casing 120 described later. For this reason, the rotation of the motor shaft 108A can be freely braked by controlling the voltage applied to the electromagnetic coil.

  Thus, the motor 106A and the brake 126A are small in size and are arranged in a width d3 between the inner diameter d1 of the cylindrical member 102 and the outer diameter d2 of the brake cover 128. However, even if the motor 106A and the brake 126A are small in size, three motors 106A and three brakes 126A are arranged at equal intervals in the circumferential direction between the widths d3. For this reason, the rotational torque and braking torque transmitted to the speed reduction mechanism 130 can be increased.

  Next, the speed reduction mechanism 130 and the encoder 160A will be mainly described. The crankshaft 132A is the same as the other crankshafts 132B and 132C except for the shaft tip portion 140A of the crankshaft 132A where the encoder 160A is provided. For this reason, the description of the crankshafts 132B and 132C and the members with the lower-order alphabetic characters related to the crankshafts 132B and 132C are omitted.

  The speed reduction mechanism 130 includes an eccentric body 136, an external gear 144, and an internal gear 150. When attention is paid to one crankshaft 132A, a pair of eccentric bodies 136A are integrally formed in a state of being shifted from each other by 180 degrees. The pair of eccentric bodies 136 are provided on the three crankshafts 132 in the same phase. That is, by controlling the rotation of the three motor shafts 108, the eccentric bodies 136 on the three crankshafts 132 can be rotated in the same direction and the same speed in the same phase. The external gear 144 includes eccentric body holes 148A to 148C (hereinafter referred to as eccentric body holes 148) (see FIG. 3). Roller bearings 142 </ b> A to 142 </ b> C (hereinafter referred to as roller bearings 142) are disposed between the eccentric hole 148 and the eccentric body 136. For this reason, the external gear 144 is fitted to the outer periphery of the eccentric body 136 via the roller bearing 142.

  The external gear 144 is inscribed in the internal gear 150. The internal gear 150 is integrated with the output member 152. Specifically, the internal teeth 151 of the internal gear 150 are configured by pins (see FIG. 3), and the number calculated from the minimum interval P in the circumferential direction (the number of teeth of the internal gear 150) is an external tooth. More than the number of teeth of the gear 144 is set. The reduction ratio of the reduction mechanism 130 is determined from the difference in the number of teeth between the number of teeth of the internal gear 150 and the number of teeth of the external gear 144 and the number of teeth of the external gear 144. A plurality (six in this embodiment) of column holes 145 are formed in the external gear 144 at regular intervals in the circumferential direction (see FIG. 3). A column portion 155 that is integrally projected from the carrier plate 156 is loosely fitted in the column hole 145. The carrier plate 156 is fixed to the main body casing 120 by being connected to the extending portion 154 formed integrally extending from the main body casing 120 in the axial direction O with a bolt 190. Note that a carrier 158 is constituted by the extending portion 154 and the carrier plate 156. The external gear 144 is formed with a central shaft hole 146 in which the cylindrical member 102 is loosely fitted.

The output member 152 is rotatably supported on the outer periphery of the carrier 158 by a pair of bearings 170 and 172. In the present embodiment, the output of the actuator 100 is transmitted from the output member 152 to the counterpart machine by fixing the main body casing 120 to the casing of the counterpart machine using the bolt holes 186. However, the output member 152 may be fixed to the casing of the counterpart machine using the bolt hole 188, and the output of the actuator 100 may be transmitted from the main body casing 120 to the counterpart machine. The outer diameter d4 of the output member 152 can be made larger than the outer diameter d 2 of the brake cover, and outputs a large torque.

The crankshaft 132A is integrally formed with the motor shaft 108A. That is, the motor shaft 108A is also used as the crank shaft 132A. The motor shaft 108A is rotatably supported with respect to the main body casing 120 by a bearing 166A at the shaft end portion 112A. In other words, the motor shaft 108A is supported by the bearing 166A at the end on the side opposite to the eccentric body of the motor 106A. On the other hand, the crankshaft 132A is rotatably supported at its shaft end 138A by a bearing 168A. In other words, the crankshaft 132A is supported by the bearing 168A at the non-motor side end of the eccentric body 136A. The bearing 168A is supported by the carrier plate 156 described above. Since the motor shaft 108A and the crankshaft 132A are integrally formed, the motor shaft 108A and the crankshaft 132A are supported by the main body casing 120 and the carrier plate 156 with only two bearings 166A and 168A. For this reason, in this embodiment, the span L1 between the two bearings 166A and 168A can be made longer than in the case where the bearing is arranged at the shaft central portion 134A of the crankshaft 132A instead of the bearing 166A and supported by the bearing. it can. That is, even if an inexpensive bearing such as a ball bearing is used for both the bearings 166A and 168A, the shaft runout of the crankshaft 132A (motor shaft 108A) that can occur if the span is short can be reduced. For this reason, the crankshaft 132B (132C) using the bearings 166B (166C) and 168B (168C) can similarly reduce the shaft runout. Hereinafter, the bearings 166A to 166C and 168A to 168C are referred to as bearings 166 and 168, respectively.

  The encoder 160A includes a movable part 161A and a fixed part 162A. The movable portion 161A is a slit plate or the like, is attached to the shaft tip portion 140A of the crankshaft 132A, and rotates integrally with the crankshaft 132A. The fixing portion 162A includes a light emitting element and a light receiving element that receives light that has passed through the slit of the slit plate, and the fixing portion 162A is fixed to the carrier plate 156. For this reason, the encoder 160A can detect the rotation angle of the crankshaft 132A. Note that an encoder cover 164A is attached to the carrier plate 156 so as to cover the encoder 160A.

  The thickness t1 in the axial direction O necessary for the encoder 160A is considered to be from the shaft tip portion 140A of the crankshaft 132A to the encoder cover 164A. Here, the carrier plate 156 supports an output member 152 that outputs the actuator 100 via a bearing 172. That is, since it is necessary to support a large output torque (including braking torque) by the carrier plate 156, the carrier plate 156 needs to have a corresponding thickness t2 in order to have high rigidity. For this reason, as shown in FIG. 1, by incorporating the encoder 160A into the carrier plate 156, the thickness t1 is offset in terms of arrangement with the thickness t2, and the protruding length in the axial direction O can be set to t3. That is, for example, the protrusion length t3 can be shortened and the increase in the length of the actuator 100 in the axial direction O can be minimized as compared with the case where the encoder is provided outside the brake (right side in FIG. 1).

  Reference numerals 174A, 176A, 178, 180 are oil seals for sealing the lubricant used in the speed reduction mechanism 130.

  Next, the operation of the actuator 100 will be described.

  The motor shafts 108 of the three motors 106 are simultaneously rotated by an electric signal from a motor driver (not shown). At this time, the three motors 106 may be controlled by one motor driver, or may be controlled by separate motor drivers. As a result, the three crankshafts 132 integrally formed with the motor shaft 108 rotate, and the eccentric bodies 136 respectively provided on the crankshafts 132 have the same phase and the same speed in the same direction. Rotate with.

  As a result, the external gear 144 fitted to each eccentric body 136 via the roller bearing 142 is swung, and the external gear 144 and the internal gear 150 are engaged with each other. Here, the column portion 155 of the carrier plate 156 that is loosely fitted in the column hole 145 of the external gear 144 is fixed to the main body casing 120 (attached and fixed to the counterpart machine). For this reason, each time the eccentric body 136 rotates, the internal gear 150 rotates by a difference in the number of teeth from the external gear 144. That is, the output member 152 integrated with the internal gear 150 rotates with respect to the main body casing 120. The rotation angle of the output member 152 at this time can be obtained by multiplying the rotation angle of the crankshaft 132A detected by the encoder 160A by the reduction ratio of the reduction mechanism 130. The swing component of the external gear 144 is absorbed by loose fitting between the column portion 155 of the carrier plate 156 and the column hole 145.

Here, brakes 126 are provided on all three motor shafts 108. For this reason, all the three crankshafts 132 are braked by the brake 126 by applying all the brakes 126. In other words, it is possible to prevent a reverse load from being applied to only a part of the crankshaft and a rotational angle shift to occur only on the crankshaft. An encoder 160A is provided on one crankshaft 132A. The brake 126A is provided an encoder 160A to the crankshaft 132A provided, even if the braking by the brake 126 A, it is possible to minimize the error of the rotation angle detected by the encoder 160A.

  At the same time, in this embodiment, since the brakes 126 are provided on all the crankshafts 132, the load applied to each crankshaft 132 is equalized by the braking of the brake 126, and the load applied to each crankshaft 132 is further reduced. Can do. For this reason, only a part of the crankshaft can be prevented from being fatigued, and the actuator 100 can have a long life.

The encoder 160A is disposed in the vicinity of the eccentric body 136A and at the shaft tip portion 140A of the crankshaft 132A. That is, the encoder 160A is arranged on the crankshaft 132A on the side opposite to the axial direction O of the eccentric body 136A. For this reason, the encoder 160A can be easily attached regardless of the motor 106A. Further, since the bearing 168A supports the vicinity of the encoder 160A of the crankshaft 132A, the rotation angle of the crankshaft 132A can be detected more accurately.

  Further, as shown in FIG. 1, the encoder 160 </ b> A is disposed on the carrier plate 156 on the inner side of the output member 152 at the shaft tip portion 140 </ b> A of the crankshaft 132 </ b> A opposite to the brake 126 </ b> A in the axial direction O. Therefore, while the rotation angle can be detected with high accuracy, the protruding length t3 of the encoder 160A to the outside of the actuator 100 in the axial direction O can be reduced. That is, an increase in the length of the actuator 100 in the axial direction O can be minimized.

Note that the protrusion length t3 can be eliminated by increasing the axial length of the output member 152. In that case, the span L2 between the bearings 170 and 172 supporting the output member 152 can be lengthened. For this reason, the rotational shake of the output member 152 can be further reduced.

  Further, the crankshaft 132 and the motor shaft 108 are integrally formed, and the motor shaft 108 is supported by the bearing 166 at the end portion on the side opposite to the eccentric body of the motor 106. For this reason, shaft runout of the motor shaft 108 can be reduced. In addition, the load on the motor shaft 108 from the brake 126 on the side opposite to the eccentric body of the motor 106 can be supported by the main body casing 120. That is, the rotation of the motor 106 can be stabilized and the life of the motor 106 can be extended.

  Further, the motor shaft 108A is supported by a bearing 166A at the opposite end of the motor 106A, and the crankshaft 132A is supported by the bearing 168A at the opposite end of the eccentric 136A. That is, the crankshaft 132A and the motor shaft 108A are supported by only the two bearings 166A and 168A. That is, the span L1 between the bearings 166A and 168A can be increased. For this reason, for example, it is possible to prevent the occurrence of an encoder error due to a shaft runout at the encoder due to a short span between the bearings. That is, the shaft runout of the crankshaft 132A can be reduced to the minimum, and the rotation angle can be detected with high accuracy by the encoder 160A. At the same time, since the bearings 166A and 168A are ball bearings and no other bearings are provided, it is possible to reduce the shaft runout of the crankshaft 132A at a low cost.

  That is, according to the present embodiment, even when braking by the brake 126 is performed, it is possible to control the rotation angle of the actuator 100 with high accuracy. The actuator includes a through-hole 104 in the direction of the central axis O, and can be high in output while being compact in outer dimensions such as an outer diameter size and an axial length.

  Although the present invention has been described with reference to the present embodiment, the present invention is not limited to the present embodiment. That is, it goes without saying that improvements and design changes can be made without departing from the scope of the present invention.

  In the above embodiment, there are three motors 106, and accordingly, there are three motor shafts 108, crank shafts 132, eccentric bodies 136, etc., but the present invention is not limited to this, and two or more of them are included. It suffices if there is a plurality.

  In the above embodiment, the encoder 160A is provided on one crankshaft 132A, but the present invention is not limited to this. For example, it may be provided on another crankshaft or all crankshafts or motor shafts. In this case, even if a slight deviation occurs in the braking timing of each crankshaft, the rotation angle of the actuator can be obtained with higher accuracy from the detection result of each encoder.

  Moreover, in the said embodiment, although the motor shaft 108 and the crankshaft 132 were integrally formed, this invention is not limited to this. For example, the motor shaft and the crankshaft may rotate together via a joint.

In the above embodiment, the brake 126 A to the shaft distal end 114 A of the motor shaft 108 A, but the encoder 160A is provided on the shaft tip portion 140A of the crank shaft 132A, the present invention is not limited thereto. For example to an encoder and a brake may be reversed arrangement, both the encoder and the brake may be provided on one shaft destination end. Alternatively, a brake and / or an encoder may be disposed between the motor shaft and the crankshaft, that is, between the eccentric body and the motor.

  In the above embodiment, the motor shaft 108A and the crankshaft 132A are supported by the two bearings 166A and 168A, and the brake 126A and the encoder 160A are provided on the outer sides thereof. However, the present invention is not limited to this. Not. For example, a bearing may be further arranged between the motor and the eccentric body to support three points, or a bearing may be arranged outside the brake and encoder in the axial direction O. Furthermore, bearings may be arranged at the tip of the crankshaft and between the motor and the eccentric body to provide two-point support.

  The actuator of the present invention has a through hole in the central axis O direction, can be compact with external dimensions such as the outer diameter size and axial length, and can control the rotation angle with high output and high accuracy. . For this reason, the applicability can be further expanded in various applications such as a robot apparatus and a transfer apparatus that are small, require high output, and require precise control.

DESCRIPTION OF SYMBOLS 100 ... Actuator 102 ... Cylindrical member 104 ... Through-hole 106, 106A, 106B, 106C ... Motor 108, 108A, 108B, 108C ... Motor shaft 110A, 110B ... Rotor shaft part 112A, 112B, 138A, 138B ... Shaft end part 114A, 114B, 140A, 140B ... shaft tip 116A, 116B ... rotor 118A, 118B ... stator 120 ... main body casing 122 ... middle cover 124A, 161A ... movable part 125A, 162A ... fixed part 126, 126A, 126B, 126C ... brake 128 ... Brake cover 130 ... Deceleration mechanism 132, 132A, 132B, 132C ... Crankshaft 134A, 134B ... Shaft center 136, 136A, 136B, 136C ... Eccentric body 142, 142A, 142B, 142C Roller bearing 144 ... External gear 145 ... Column hole 146 ... Center shaft hole 148, 148A, 148B, 148C ... Eccentric body hole 150 ... Internal gear 151 ... Internal tooth 152 ... Output member 154 ... Extension part 155 ... Column part 156 ... Carrier plate 158 ... Carrier 160A ... Encoder 164A ... Encoder cover 166, 166A, 166B, 166C, 168, 168A, 168B, 168C, 170, 172 ... Bearings 174A, 174B, 176A , 178, 180 ... Oil seals 182, 184 186, 188, 190 ... bolt or bolt hole

Claims (5)

A plurality of motors, a plurality of crankshafts rotating integrally with the motor shafts of the plurality of motors, an eccentric body provided in the same phase on each of the plurality of crankshafts, and swinging on an outer periphery of the eccentric body In an actuator having an external gear rotatably incorporated, and an internal gear internally meshing with the external gear,
Each of the plurality of crankshafts or the plurality of motor shafts is provided with a brake for braking each crankshaft,
An actuator, wherein an encoder for detecting a rotation angle of the crankshaft is provided on at least one of the crankshaft or the motor shaft. In claim 1,
The actuator, wherein the encoder is arranged on the crankshaft on the side opposite to the motor in the axial direction of the eccentric body. In claim 1 or 2,
The crankshaft and the motor shaft are integrally molded,
An actuator, wherein the motor shaft is supported by a bearing at an end portion on the side opposite to the eccentric body of the motor. In claim 3, further:
The actuator, wherein the crankshaft and the motor shaft are supported by only two bearings by supporting the crankshaft by a bearing at the end of the eccentric body on the non-motor side. In any one of Claims 1 thru | or 4,
A bearing that supports the vicinity of the encoder of the crankshaft or motor shaft.

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