JP2013255344A - Electrically-driven rotary actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely remove a backlash even when gear precision is inferior.SOLUTION: A pair of driving-side spur gears 2, 3 are rotated by stepping motors 4, 5, and rotor shafts 4a, 5a of the pair of stepping motors 4, 5 are mutually set so that tooth faces thereof come into contact with tooth faces of a driven-side spur gear 1 mutually on the opposite side in a no-load state. The stepping motors 4, 5 are synchronously driven and the driven-side spur gear 1 is driven by the driving-side spur gears 2, 3 to mutually removes backlashes between the driving-side spur gears 2, 3 and the driven-side spur gear 1. In-phase coils 4A, 5a and 4B, 5B of the stepping motors 4, 5 are connected in series, and motor driving circuits 7A, 8A synchronously drive and rotate the rotor shafts 4a, 5a of the stepping motors 4, 5 while giving a predetermined phase difference. A rotary encoder 6 which detects rotations of only one of the stepping motors 4, 5 is attached to the stepping motor and then the driving-side spur gears 2, 3 have the mutual tooth faces brought into contact at the same place in a peripheral direction of the driven-side spur gear 1.

Description

  The present invention is suitable for application to, for example, an electric rotary actuator that meshes a driving side rotating tooth body and a driven side rotating tooth body that are rotated by a motor, and transmits the rotation of the motor to the driven side for output. is there.

  Conventionally, an electric rotary actuator intended to prevent backlash between the driving side rotating tooth body and the driven side rotating tooth body has been proposed (for example, see Patent Document 1).

  In this electric rotary actuator, as shown in FIG. 12, the meshing contact relationship between the tooth surface 1 b on the outer side of the tooth 1 a of the driven side spur gear 1 and the tooth surface 2 c of the driving side spur gear 2, and the driven side spur gear 1. Since the meshing contact relationship in which the tooth surface 1c on the outside of the tooth 1a and the tooth surface 3b of the drive side spur gear 3 are in contact with each other in the opposite direction in the circumferential direction when no load is applied, The backlash of the driven side spur gear 1 and the driving side spur gears 2 and 3 can be removed.

Japanese Patent No. 4743874

  However, in the electric rotary actuator of Patent Document 1, since the tooth surfaces 1b and 1c outside the teeth 1a of the driven side spur gear 1 and the tooth surfaces 2c and 3b of the drive side spur gears 2 and 3 are in contact with each other, When the axial deviation of the driven side spur gear 1 occurs, the meshing amount of the tooth surface 1b of the driven side spur gear 1 and the tooth surface 2c of the driving side spur gear 2 and the outer tooth surface 1c of the driven side spur gear 1 are as follows. And the amount of meshing of the drive side spur gear 3 with the 3b of the drive side spur gear 3, and an angular accuracy error with respect to the driven side spur gear 1 between the drive side spur gear 2 and the drive side spur gear 3 occurs. There was a problem that it could not be removed.

  The present invention has been made to solve such a problem, and even when the gear accuracy is inferior, the backlash is reliably removed without causing different angular accuracy errors between the pair of drive side rotating tooth bodies. The electric rotary actuator to be obtained is to be proposed.

  In order to solve such a problem, in the present invention, an electric rotary that meshes a driving side rotating tooth body and a driven side rotating tooth body that are rotated by a motor, transmits the rotation of the motor to the driven side, and outputs the rotation. The actuator includes a pair of stepping motors as the motor and a pair of driving side rotating tooth bodies as the driving side rotating tooth body, and the pair of driving side rotating tooth bodies are rotated by the respective stepping motors. The rotor shafts of the pair of stepping motors are set mutually so that the tooth surfaces of the pair of stepping motors are in contact with the tooth surfaces of the driven-side rotating tooth body on the opposite side when no load is applied. The pair of drive-side rotating teeth is driven synchronously by a circuit, and the driven-side rotating tooth body is driven by a pair of driving-side rotating tooth bodies. And the driven side rotating tooth bodies are removed from each other, the same phase coils of the pair of stepping motors are connected in series, and the motor drive circuit connects the pair of stepping motors to their rotor shafts in a predetermined manner. A phase difference is given, synchronously driven and rotated, and an encoder for detecting the rotation is attached to only one of the pair of stepping motors, and then the pair of drive side rotating tooth bodies is in the circumferential direction of the driven side rotating tooth body Each tooth surface is made to contact in the same location.

  In the present invention, the pair of driving side rotating tooth bodies are complementary to each other.

  Further, in the present invention, the pair of stepping motors are arranged so that the output shafts are directed in the same direction with respect to the pair of driving side rotating tooth bodies.

  According to the present invention, according to the present invention, the tooth surfaces of the pair of drive-side rotating tooth bodies are in contact with the tooth surfaces of the driven-side rotating tooth bodies on the opposite sides at no load. The rotor shafts of the pair of stepping motors are mutually set, and the pair of stepping motors are driven synchronously so that the driven side rotating tooth body is rotated by the pair of driving side rotating tooth bodies. The backlash can be easily removed by cooperating with the side rotating tooth body, and at the same time, the pair of driving side rotating tooth bodies contact each other at the same circumferential position of the driven side rotating tooth body. Thus, it is possible to prevent the occurrence of different angular accuracy errors between the pair of drive side rotating tooth bodies. In addition, when the in-phase coils of a pair of stepping motors are connected in series, and these stepping motors are given a predetermined phase difference to their rotor shafts and driven synchronously, the pair of stepping motors can be controlled without separate control. Since the kite can be driven by exactly the same control as driving one stepping motor, the drive control is simplified. In addition, if an encoder that detects the rotation is attached to only one of the pair of stepping motors, the pair of stepping motors can be controlled in a closed loop as if only one stepping motor is being controlled, thus simplifying the circuit configuration and control. it can.

  In addition, according to the present invention, the pair of driving side rotating tooth bodies are complementary to each other, and therefore, the angle accuracy error generated between the pair of driving side rotating tooth bodies is common, and the deterioration of the gear accuracy can be absorbed. .

  Further, according to the present invention, since the pair of stepping motors are arranged so that the output shafts are directed in the same direction with respect to the pair of driving side rotating tooth bodies, the motor excitation angle error with respect to the pair of driving side rotating tooth bodies Can be common.

It is a rough-line perspective view which shows the meshing contact state of a pair of drive side spur gear and a driven side spur gear. It is a rough-line perspective view which shows the arrangement | positioning relationship of a pair of stepping motors. It is a top view which shows the attachment state of a pair of stepping motor and a pair of drive side spur gears. It is a graph which shows the angle error by the axial center shift | offset | difference of a driven side spur gear. It is a side view which shows the 1st meshing contact relationship of one drive side spur gear and a driven side spur gear. It is a side view which shows the 1st meshing contact relationship of the other drive side spur gear and a driven side spur gear. It is a side view which shows the 2nd meshing contact relationship of one drive side spur gear and a driven side spur gear. It is a side view which shows the 2nd meshing contact relationship of the other drive side spur gear and a driven side spur gear. It is a circuit diagram which shows a pair of stepping motor and its motor drive circuit. It is a torque curve figure in case a pair of stepping motors have the same torque characteristic. It is a torque curve figure in case the torque of one stepping motor 4 is 1/2. It is a side view which shows the meshing contact state of a pair of conventional drive side spur gear and driven side spur gear.

  Next, an embodiment of the present invention will be described with reference to the drawings.

(1) Configuration of Electric Rotary Actuator FIG. 1 shows a gear mechanism that constitutes an electric rotary actuator according to the present invention, and a driven-side large-diameter spur gear (hereinafter referred to as a driven-side flat gear) for outputting rotation. A pair of small spur gears on the drive side rotated by a pair of stepping motors 4 and 5 shown in FIGS. 2 and 3 (hereinafter referred to as drive side spur gears) 2, 3 Are arranged in parallel at the same place on the peripheral surface of the driven side spur gear 1, and the tooth surfaces of the drive side spur gears 2 and 3 as drive side rotating tooth bodies are opposite to each other in the circumferential direction when no load is applied to eliminate backlash. And the tooth surface of the driven side spur gear 1 as the driven side rotating tooth body are in contact with each other.

  As shown in FIGS. 2 and 3, in this gear mechanism, a pair of stepping motors 4, 5 is directly connected to a pair of drive side spur gears 2, 3, and a rotor shaft 4 a of the pair of stepping motors 4, 5. 5a is synchronously rotated in the same direction.

  The pair of stepping motors 4 and 5 is provided with an encoder (rotary encoder) 6 that detects the rotation of only one of the stepping motors 4, but the stepping motors 4 and 5 have substantially the same structure as a single motor. is there.

  Here, the pair of stepping motors 4 and 5 are arranged so that their output shafts are directed in the same direction with respect to the pair of drive-side spur gears 2 and 3. The output shaft (rotor shaft 4a) is directly connected to the drive side spur gear 2, the counter output shaft (not shown) of the stepping motor 4 is directly connected to the rotary encoder 6, and the counter output shaft (rotor shaft) of the stepping motor 5 is connected. 5b) is directly connected to the drive side spur gear 3.

  That is, the pair of stepping motors 4 and 5 has a pair of drive side spur gears so that the direction of the output shaft (rotor shaft 4a) of the stepping motor 4 and the direction of the output shaft 5a of the stepping motor 5 coincide. 2 and 3 are arranged.

  As a result, in this gear mechanism, the directions of the output shafts 4a and 5a of the pair of stepping motors 4 and 5 having substantially the same structure as a single motor can be made to coincide with each other. The error can be made common, and thus the rotational accuracy of the pair of drive side spur gears 2 and 3 by the pair of stepping motors 4 and 5 can be made uniform.

  By the way, an error generated between an ideal rotation angle of the driven side spur gear 1 and an actual rotation angle in the case where an axial misalignment occurs is generally as shown in FIG. For example, the driven spur gear 1 rotates 90.16 degrees despite the desire to rotate the driven spur gear 1 by 90 degrees, resulting in a rotation angle error of +0.16 degrees. It is known to have a rotation angle error.

  Therefore, in this gear mechanism, the drive-side spur gears 2 and 3 are not arranged on different peripheral surfaces of the driven-side spur gear 1, but the same circumferential direction on the peripheral surface of the driven-side spur gear 1. The pair of drive-side spur gears 2 and 3 are arranged so that the tooth surfaces of each other come into contact with each other.

  As a result, in the gear mechanism, different angular accuracy errors between the driven side spur gear 1 and the pair of drive side spur gears 2 and 3 are prevented, and as a result, the driven side spur gear 1 is misaligned. Even in this case, it is possible to prevent backlash between the drive side spur gears 2 and 3 and the driven side spur gear 1.

  Here, since the pair of drive side spur gears 2 and 3 have a complementary relationship obtained by cutting one spur gear and dividing it into two, the drive side spur gear 2 and the driven side spur gear 1 and the meshing state of the driving side spur gear 3 and the driven side spur gear 1 are the same, and the backlash is caused by the difference in the meshing state between the driving side spur gears 2 and 3 and the driven side spur gear 1. It is possible to prevent the occurrence of the occurrence in advance.

  The arrangement state of the drive side spur gears 2 and 3 with respect to the driven side spur gear 1 for removing backlash in this gear mechanism will be specifically described. Therefore, FIG. 5 shows a model of the first meshing contact relationship between the large-diameter driven spur gear 1 and the small-diameter drive-side spur gear 2 at no load, and FIG. 6 shows a large-diameter driven spur gear. The model of the 1st meshing contact relationship in the time of no load of the gearwheel 1 and the small diameter drive side spur gearwheel 3 is shown. FIG. 7 shows a model of a second meshing contact relationship between the large-diameter driven side spur gear 1 and the small-diameter driving side spur gear 2 at no load, and FIG. 8 shows a large-diameter driven side spur gear. The model of the 2nd meshing contact relationship in the time of no load of the gear 1 and the small diameter drive side spur gear 3 is shown.

  Here, the pair of drive-side spur gears 2 and 3 are exactly the same having a complementary relationship, but since the meshing contact relationship with the driven-side spur gear 1 at no load is different, these three spur gears 1 and 2 In order to distinguish the directions of the tooth surfaces on both sides of the three teeth 1a, 2a, 3a, one is expressed as “one side” and the other as “opposite side”.

  In the case of FIG. 5, when no load is applied, the tooth 2a of one drive side spur gear 2 has its one tooth surface 2c in contact with one tooth surface 1b of the tooth 1a of the driven side spur gear 1, and in the case of FIG. On the contrary, the tooth 3a of the other drive side spur gear 3 has a meshing contact relationship such that the tooth surface 3b on the opposite side contacts the tooth surface 1c on the opposite side of the tooth 1a of the driven side spur gear 1. It has become.

  That is, when viewed in the middle of the pair of drive side spur gears 2 and 3, the tooth surfaces 2 c and 3 b inside the teeth 2 a and 3 a are connected to the tooth surfaces 1 b and 1 c outside the teeth 1 a of the driven side spur gear 1. It is a meshing contact relationship that comes into contact. The rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 that are directly connected to the pair of drive-side spur gears 2 and 3 so as to be in meshing contact when there is no load are set at predetermined positions by default. The rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 are synchronously driven and rotated in the same direction.

  On the other hand, in the case of FIG. 7, when no load is applied, the tooth 2a of one drive-side spur gear 2 has a tooth surface 2b opposite to the tooth surface 1c opposite to the tooth 1a of the driven-side spur gear 1. In the case of FIG. 8, the tooth 3 a of the other drive side spur gear 3 is in contact with the tooth surface 1 b of one side of the tooth 1 a of the driven side spur gear 1. Such a meshing contact relationship.

  That is, when viewed in the middle of the pair of drive side spur gears 2 and 3, the tooth surfaces 2 b and 3 c outside the teeth 2 a and 3 a are the tooth surfaces 1 c and 1 b inside the teeth 1 a of the driven side spur gear 1. It is a meshing relationship that touches. The rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 that are directly connected to the pair of drive-side spur gears 2 and 3 so as to be in meshing contact when there is no load are set at predetermined positions by default. The rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 are synchronously driven and rotated in the same direction.

  5 and 6, and FIGS. 7 and 8, the contact tooth surfaces at the time of no load are reversed as described above. In either case, the driven spur gear 1 is rotated clockwise. When the pair of driving spur gears 2 and 3 are simultaneously rotated counterclockwise by the pair of stepping motors 4 and 5, the teeth 2a and 3a of the pair of driving spur gears 2 are rotated. Torque in the clockwise direction with respect to the driven spur gear 1 in a state in which the front tooth surfaces 2b and 3b in the direction (counterclockwise) are in contact with the rear tooth surface 1c of the tooth 1a of the driven spur gear 1. Simultaneously, the driven spur gear 1 is rotated clockwise.

  When the pair of stepping motors 4 and 5 stops, the pair of drive side spur gears 2 and 3 also stop rotating, and in the case of the meshing contact relationship shown in FIGS. In the case of the mesh contact state shown in FIGS. 7 and 8, the state shown in FIG. 7 is restored, and in each case, the three spur gears 1, 2, and 3 cooperate to remove backlash. I will be happy.

  On the other hand, when the pair of drive side spur gears 2 and 3 are simultaneously rotated clockwise by the pair of stepping motors 4 and 5 in order to rotate the driven side spur gear 1 counterclockwise, FIGS. 7 and 8, the teeth 2 a and 3 a of the pair of drive side spur gears 2 have front tooth surfaces 2 c and 3 c in the rotational direction (clockwise direction) of the teeth 1 a of the driven side spur gear 1. While in contact with the rear tooth surface 1b, counterclockwise torque is simultaneously applied to the driven spur gear 1 to rotate the driven spur gear 1 counterclockwise.

  Also in this case, when the pair of stepping motors 4 and 5 are stopped, the pair of drive-side spur gears 2 and 3 also stop rotating, and in the case of the meshing relationship shown in FIGS. In the case of the no-load state and the meshing relationship shown in FIGS. 7 and 8, the state returns to the no-load state shown in FIG. We will work together to remove backlash.

  Therefore, even if the three spur gears 1, 2, and 3 rotate in either the clockwise direction or the counterclockwise direction, the backlash is removed in cooperation with each other, and the torque of the two drive side spur gears 2 and 3 Are simultaneously applied to the driven spur gear 1.

  FIG. 9 shows a configuration of a motor drive circuit that drives the pair of stepping motors 4 and 5. The stepping motors 4 and 5 are provided with an encoder (rotary encoder) 6 for detecting the rotation of only one of the stepping motors 4. However, the motor itself has substantially the same structure, and the A phase and B phase 2 The A-phase coils 4A and 5A are connected in series, and the B-phase coils 4B and 5B are also connected in series. The A phase coils 4A and 5A are excited by one common A phase drive unit 7A, and the B phase coils 4B and 5B are excited by one common B phase drive unit 7B. Yes.

  Further, in each of the A phase and the B phase, currents flowing through the coils are detected by the current sensors 8A and 8B, processed by the common current feedback processing unit 9, and both stepping motors 4 and 5 are feedback-controlled simultaneously. The A phase drive unit 7A, the B phase drive unit 7B, and the current feedback processing unit 9 have the same configuration as when one stepping motor is used, and the rotation is detected by one rotary encoder 6. By configuring, both stepping motors 4 and 5 can be operated in the same manner as a single stepping motor is controlled.

  Therefore, the motor drive circuit (FIG. 9) that constitutes a closed loop system and drives both stepping motors 4 and 5 simply connects the coils of these stepping motors 4 and 5 in series for each of the A phase and the B phase, By attaching the rotary encoder 6 only to the stepping motor 4 on one side, the conventional one that drives one stepping motor can be used as it is. It is also possible to drive the pair of stepping motors 4 and 5 with an open loop motor drive circuit without an encoder.

  The pair of drive side spur gears 2 and 3 is a pair of stepping motors so that the driven side spur gear 1 has a meshing relationship as shown in FIG. 5, FIG. 6 or FIG. 4, 5, a predetermined phase difference is mechanically given to the rotor shafts 4a and 5a, and both the rotor shafts 4a and 5a rotate at the same speed at the same time.

  Since the pair of stepping motors 4 and 5 has the rotary encoder 6 attached only to one stepping motor 4 and not attached to the other stepping motor 5 as described above, the former is “stepping motor with encoder” and the latter Is referred to as “stepping motor without encoder”, the drive-side spur gear 3 rotated by the stepping motor 5 without encoder has a stepping motor 5 without encoder for fine adjustment at the time of initial setting to be in meshing relationship as described above. The rotor shaft 5a is fixed so that it can be finely adjusted in both directions.

  Now, assuming that the two stepping motors 4 and 5 are exactly the same up to the specifications and have the same torque characteristics (sin θ), the rotor shafts 4a and 5a rotate simultaneously at the same speed while maintaining a predetermined phase difference as described above. When the phase difference is φ, as shown in FIG. 10, the torque curve of one stepping motor is expressed as sin θ, the torque curve of the other stepping motor is expressed as sin (θ + φ), and the combined torque curve is expressed as sin θ + sin (θ + φ). Can do.

  If the torque characteristic of one of the stepping motors is ½, as shown in FIG. 11, the torque curve is sin (θ + φ) / 2, so the combined torque curve is expressed as sinθ + sin (θ + φ) / 2. be able to.

  Accordingly, the backlash of the three spur gears 1, 2, and 3 can be removed in cooperation as described above, and at the same time, the torque of the driven spur gear 1 can be increased and the torque can be adjusted by the stepping motors 4 and 5. .

  Incidentally, since the drive side spur gear 2 of the stepping motor 4 with the encoder is fixed in advance to the rotor shaft 4a, by adjusting the stepping motor 5 side without the encoder while checking the number of pulses from the rotary encoder 6, Depending on the number of pulses from the rotary encoder 6, the pair of drive side spur gears 2 and 3 are both engaged with the driven spur gear 4 as shown in FIG. 5, FIG. 6 or FIG. 7 and FIG. The deviation of the mechanical excitation angle of the stepping motors 4 and 5 can be determined.

(4) Operation and Effect In the above configuration, the gear mechanism constituting the electric rotary actuator does not arrange the drive side spur gears 2 and 3 with respect to the different peripheral surfaces of the driven side spur gear 1 but the driven side. The pair of drive-side spur gears 2 and 3 are arranged in parallel so that the tooth surfaces contact each other at the same circumferential position on the peripheral surface of the spur gear 1.

  Thus, in the gear mechanism, even if the driven side gear 1 is misaligned, the pair of drive side spur gears 2 and 3 are arranged in parallel at the same circumferential position on the peripheral surface of the driven side spur gear 1. Therefore, it is possible to prevent in advance the occurrence of different angular accuracy errors between the driven side spur gear 1 and the pair of drive side spur gears 2 and 3 while allowing the axial deviation of the driven side spur gear 1. Backlash can also be prevented in advance between the drive side spur gears 2 and 3 and the driven side spur gear 1.

  The gear mechanism is arranged so that the directions of the output shafts 4a and 5a of the pair of stepping motors 4 and 5 are aligned with the pair of drive-side spur gears 2 and 3, thereby exciting the stepping motors 4 and 5 with each other. Since the directions are uniform and the in-excitation error can be made the same, and thus the rotational accuracy of the pair of drive side spur gears 2 and 3 by the pair of stepping motors 4 and 5 can be made uniform, the drive side spur gears 2 and 3 Can be prevented from occurring between the driven spur gear 1 and the driven spur gear 1.

  Further, the gear mechanism has a complementary relationship obtained as a result of the pair of drive-side spur gears 2 and 3 cutting one spur gear and dividing it into two, so that the drive-side spur gear 2 and the driven-side spur gear 1 and the meshing state of the driving side spur gear 3 and the driven side spur gear 1 are the same, and the backlash is caused by the difference in the meshing state between the driving side spur gears 2 and 3 and the driven side spur gear 1. Can be prevented.

  Thus, in the gear mechanism, a pair of drive-side spur gears 2 and 3 are arranged in parallel at the same location in the circumferential direction on the peripheral surface of the driven-side spur gear 1, and the pair of drive-side spur gears 2 and 3 are connected to the pair of drive-side spur gears 2 and 3. By using the pair of driving spur gears 2 and 3 that are arranged so that the directions of the output shafts 4a and 5a of the pair of stepping motors 4 and 5 coincide with each other and have a complementary relationship with each other, a driven spur gear is obtained. Even if an axial misalignment occurs in 1, the backlash between the drive side spur gears 2 and 3 and the driven side spur gear 1 can be reliably prevented.

According to the above configuration, even if the gear accuracy is inferior, the driven side spur gears 2 and 3 can be driven with a simple configuration without causing different angular accuracy errors between the pair of driving side spur gears 2 and 3. An electric rotary actuator that can reliably remove backlash between the side spur gear 1 can be realized.
be able to.

(6) Other Embodiments In the above-described embodiments, the drive-side spur gears 2 and 3 are used as a pair of drive-side rotating tooth bodies respectively rotated by the pair of stepping motors 4 and 5. Although the case has been described, the present invention is not limited to this, and a hypoid gear, a toothed pulley, or the like may be used in addition to the bevel gear, the worm, and the pinion.

  In the above-described embodiment, the case where the driven side spur gear 1 is used as the driven side rotating tooth body has been described. However, the present invention is not limited to this, and the bevel gear, worm, pinion, hypoid gear, and tooth are used. An attached pulley or the like may be used.

  DESCRIPTION OF SYMBOLS 1 ... Drive side spur gear (driven side rotation tooth body) 2, 3 ... Drive side spur gear (drive side rotation tooth body) 4, 5 ... Stepping motor, 4A, 5A, 4B, 5B ... Coil, 4a, 5a 5b ... rotor shaft, 6 ... rotary encoder, 7A ... A phase drive unit, 7B ... B phase drive unit, 8A, 8B ... current sensor, 9 ... current feedback unit.

Claims (3)

In the electric rotary actuator that meshes the driving side rotating tooth body rotated by the motor and the driven side rotating tooth body, and transmits the rotation of the motor to the driven side to output the rotation,
A pair of stepping motors as the motor and a pair of driving side rotating teeth as the driving side rotating tooth bodies, the pair of driving side rotating tooth bodies being rotated by the respective stepping motors; The rotor shafts of the pair of stepping motors are mutually set so that the tooth surfaces are in contact with the tooth surfaces of the driven-side rotating tooth body on the opposite side when no load is applied. Drive back synchronously with a drive circuit and drive the driven side rotating tooth body with the pair of driving side rotating tooth bodies, so that the backlash between the pair of driving side rotating tooth bodies and the driven side rotating tooth body is reduced. To be removed from each other,
The in-phase coils of the pair of stepping motors are connected in series, and the motor drive circuit applies a predetermined phase difference to the rotor shafts of the pair of stepping motors, rotates them synchronously, and rotates the pair of stepping motors. After attaching an encoder that detects the rotation of only one of the motors,
The pair of driving-side rotating tooth bodies contact each other at the same circumferential position of the driven-side rotating tooth body. The electric rotary actuator according to claim 1, wherein the pair of driving side rotating tooth bodies are complementary to each other. The electric rotary actuator according to claim 2, wherein the pair of stepping motors are arranged so that output shafts are directed in the same direction with respect to the pair of drive-side rotating tooth bodies.

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