JP2019129649A - Gear motor with torque detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear motor with torque detection capable of performing torque control with high accuracy without particularly improving component accuracy and assembly accuracy. A gear motor with torque detection having a motor unit 10, a speed reducer unit 20, a torque detection unit 30, and a casing 60, wherein a motor rotary shaft 11 and an output shaft 31 are a first rolling bearing 14 and 38. A first regulating means supported by the casing 60 by the second rolling bearings 15 and 39 to regulate the axial positions of the first rolling bearing inner rings 14b and 38b, and the first rolling bearing outer rings 14a and 38a. The first elastic members 41M and 41T urging to the side of one end surface in the axial direction, the second regulating means for regulating the positions of both the inner ring 15b and the outer ring 15a of the second rolling bearing, and the outer ring of the first rolling bearing. A second elastic member 42M, 42T that urges the first rolling bearings 14, 38 toward the axis center is provided between the outer peripheral cylindrical surfaces of the 14a, 38a and the casings 60e, 60a. [Selection diagram] Fig. 2

Description

  The present invention relates to a gear motor with a torque detection function, which is used for industrial robots, cargo handling machines, and the like.

  Conventionally, as a means for detecting a rotational torque while transmitting the power of the motor to a load device and performing a torque control circuit, a reduction gear is connected to the motor rotation shaft via a coupling such as a coupling to reduce the rotation. At the same time, it is common to increase the torque and connect a torque detector that can measure the torque to the output of the reducer via a shaft coupling, and connect the output shaft that is the output of this torque detector to the load device. It was. However, since the length is increased in the axial direction, there has been disclosed a gear motor with torque detection in which a motor, a speed reducer, and a torque detector are integrally formed.

JP, 2016-77121, A

  For example, in a gear motor with a torque detection as disclosed in Patent Document 1, in order to perform torque control more precisely, a rigid connection in which the connection between the motor and the reduction gear and the reduction gear and the torque detector is backlashless It was desired to carry out the binding. However, in order to realize the gear motor with torque detection with high accuracy by making each connection point rigid, it is necessary to improve the part accuracy and assembly accuracy, and there is a problem that the cost becomes high and the assembly adjustment time becomes long. .

  In view of such a problem, the present invention aims to provide a gear motor with torque detection that can perform torque control with high accuracy without particularly improving component accuracy and assembly accuracy.

The gear motor with torque detection according to claim 1 achieves the above object by:
Motor part,
A speed reducer portion having a gear for reducing the rotation of the motor rotation shaft of the motor portion;
A torque detection unit for detecting torque applied to the output shaft of the reduction gear unit;
A casing that houses the motor unit, the reduction gear unit, and the torque detection unit;
A gear motor with torque detection having
The motor rotating shaft and the output shaft are supported by the casing via first and second rolling bearings, respectively, which are spaced apart in the axial direction.
First regulating means for latching an axial direction end surface of an inner ring of the first rolling bearing to regulate an axial position of the first rolling bearing;
A first elastic member which locks the other axial end surface of the outer ring of the first rolling bearing to bias the first rolling bearing toward the one axial end surface;
Second regulating means for latching the axially opposite end faces of the inner ring and the outer ring of the second rolling bearing to respectively regulate the positions on both axial sides of the second rolling bearing;
A second elastic member provided between the outer circumferential cylindrical surface of the outer race of the first rolling bearing and the facing portion of the casing facing the outer circumferential cylindrical surface to bias the outer race of the first rolling bearing in the axial center direction; And.

  In the gear motor with torque detection according to claim 2, the first rolling bearing is disposed closer to the speed reducer portion than the second rolling bearing in the axial direction in order to achieve the above object.

  According to a third aspect of the present invention, in order to achieve the above object, the groove is provided on the entire periphery of the facing portion of the casing, and the second elastic member is disposed in the groove.

  In the gear motor with a torque detection according to claim 4, in order to achieve the above object, at least one of a motor rotation shaft and a reduction gear unit, or a reduction gear unit and an output shaft is connected to a rigid.

  According to the gear motor with torque detection of the present invention, it is possible to realize rotational driving by high-accuracy torque control without particularly increasing the component accuracy and assembly accuracy.

FIG. 1 is a perspective external view of a torque detection gear motor according to an embodiment of the present invention. It is a central part sectional view of a gear motor with a torque detection concerning an embodiment of the present invention. It is the perspective view which abbreviate | omitted one part components in 1st rolling bearing vicinity of the motor rotating shaft of the gear motor with a torque detection which concerns on embodiment of this invention. It is the perspective view which abbreviate | omitted one part components in 1st rolling bearing vicinity of the output shaft of the gear motor with a torque detection which concerns on embodiment of invention.

Hereinafter, a gear motor with a torque detection according to an embodiment of the present invention will be described in detail based on the drawings.

  FIG. 1 is a perspective view of a torque detection gear motor according to an embodiment of the present invention. The gear motor 1 with torque detection according to the embodiment of the present invention includes a motor unit 10, a reduction gear unit 20 connected to the load side output of the motor unit 10, and a torque detection unit 30 connected to the output side of the reduction gear unit 20. And a rotational position detection unit 50 connected to the motor unit 10 on the opposite load side of the motor unit 10, and casings 60 (60a to 60h) for connecting and accommodating the same and protecting it from the outside.

  FIG. 2 is a cross-sectional structural view of a torque detection gear motor according to an embodiment of the present invention, cut at its center.

  The motor unit 10 is, for example, an alternating current servomotor, and has a motor rotation shaft 11 for outputting power. A permanent magnet 12 is attached to the motor rotation shaft 11 to function as a rotor. A stator 13 consisting of an iron core and a coil is disposed on the outer periphery of the permanent magnet 12 at a predetermined distance from the permanent magnet 12. The stator 13 is fixed to the casing 60d.

  The rotational position detection unit 50 is connected to the motor rotary shaft end 11 b on the opposite side of the motor rotary shaft 11 to detect the rotational position of the motor rotary shaft 11. The rotational position detection unit 50 is a so-called encoder, which is a reflective optical type in the present embodiment, but may be a transmissive type, and may be an optical type or may be a magnetic type or other type. .

  The reduction gear unit 20 is disposed on the load side of the motor rotation shaft 11, that is, on the opposite side to the rotation position detection unit 50, and decelerates the rotation of the motor unit 10.

  The motor rotating shaft 11 is rotatably supported by casings 60c and 60e via the first rolling bearing 14 and the second rolling bearing 15. The first rolling bearing 14 and the second rolling bearing 15 are, for example, deep groove ball rolling bearings having an outer ring and an inner ring, and are spaced apart from each other in the axial direction.

  The outer peripheral cylindrical surface of the first rolling bearing outer ring 14a faces the inner peripheral cylindrical surface of the casing 60c with a predetermined gap. A groove 40M is provided over the entire circumference on the inner circumferential cylindrical surface, ie, the facing portion, of the casing 60c that the outer circumferential cylindrical surface of the first rolling bearing outer ring 14a faces. The second elastic member 42M is disposed in the groove 40M. The second elastic member 42M biases the outer circumferential cylindrical surface of the first rolling bearing outer ring 14a in the axial center direction. The second elastic member 42M is, for example, an O-ring, but is not limited to this. In addition to the O-ring, the second elastic member 42M injects a liquid gasket or the like into a predetermined gap between the outer circumferential cylindrical surface of the first rolling bearing outer ring 14a and the facing portion of the casing 60c and hardens it to form an elastic member. The groove 40M may or may not be present at this time.

  The first rolling bearing inner ring 14b and the motor rotating shaft 11 are, for example, in a state of being fitted with a tight fit. The shaft of the first rolling bearing inner ring 14b is engaged by the first rotation bearing 11c engaging the first end surface (rotational position detecting unit 50 side) of the first rolling bearing inner ring 14b in the axial direction. The position of the direction is regulated. On the other hand, the other axial end face (the reduction gear portion 20 side) of the first rolling bearing inner ring 14b is not restricted. Further, the other axial end surface (the reduction gear unit 20 side) of the first rolling bearing outer ring 14a is urged in the axial direction A by the first elastic member 41M. On the other hand, the axial direction one end surface (rotational position detection unit 50 side) of the first rolling bearing outer ring 14a is not restricted.

  The first restricting means is a motor rotating shaft rod 11c formed by a step provided on the motor rotating shaft 11. However, the first restricting means is not limited to this, and may be a collar or the like fitted on the motor rotating shaft 11. . The first elastic member 41M is an elastic member such as a leaf spring that is deformed in the compression direction so as to separate and repel the casing 60b and the first rolling bearing outer ring 14a in both axial directions. FIG. 3 shows an example of the first elastic member 41M. The first elastic member 41M is formed by bending an annular flat plate, and is in contact with the first rolling bearing outer ring 14a to form the first rolling bearing outer ring 14a. An axially biasing portion and a portion abutting the casing 60c are alternately provided in the circumferential direction.

  The second rolling bearing 15 is inserted into the inner circumferential cylindrical surface of the casing 60e with, for example, an extremely small gap. On the other hand, the second rolling bearing inner ring 15b and the motor rotating shaft 11 are in a state of being fitted with, for example, a tight fit.

  The positions of the second rolling bearing 15 on both axial sides of the second rolling bearing outer ring 15a and the second rolling bearing inner ring 15b are restricted by the second restricting means on both axial end surfaces. That is, the second rolling bearing outer ring 15a is locked by the step portion of the casing 60e and the annular pressing member 43M. The second rolling bearing inner ring 15b is restricted in axial position by the motor shaft 11d and the snap ring 44M. The retaining ring 44M is inserted into a groove provided in the vicinity of a step portion in which the second rolling bearing 15 of the motor rotating shaft end portion 11b is fitted. The second restricting means refers to the step portion of the pressing member 43M, the retaining ring 44M and the casing 60e.

  The casing 60c and the casing 60e are axially fixedly connected by bolts via an intermediate casing 60d. Therefore, by appropriately defining the axial dimension of the casing 60d, the axial position of the first rolling bearing 14 and the second rolling bearing 15 and the urging force by the first elastic member 41M can be defined.

  The reduction gear unit 20 is connected to the motor rotation shaft end 11 a on the load side of the motor rotation shaft 11. The reduction gear unit 20 is, for example, a wave gear reduction gear. The reduction gear unit 20 has a wave generator 21 whose outer periphery is elliptical and a large number of external teeth formed on the outer periphery and is externally fitted to the wave generator 21 so that the position bent in the circumferential direction changes by the rotation of the wave generator 21 The elastically deformable bottomed cylindrical flexspline 22 and the circular spline 23 provided with inner teeth on the outer peripheral side of the flexspline 22 and fitted to the outer teeth of the flexspline 22. The power is taken out and transmitted to the output shaft 31 connected to the flexspline 22 as a rotational output. High precision torque control can be performed by using a reduction gear such as a wave gear reduction with a minimal backlash as the reduction gear of this device.

  The wave generator 21 is connected, for example, by close fitting with the motor rotating shaft end 11 b via a cylindrical sleeve 24 having a ridge. Therefore, the motor rotation shaft 11 and the reduction gear unit 20 are rigidly connected without the shaft coupling. The wave generator 21 has an axial position defined by the wedge of the sleeve 24 and a retaining ring 44G inserted in the cylindrical surface. Further, the sleeve 24 is fastened to the motor rotation shaft 11 so as not to slip in the rotation direction with respect to the motor rotation shaft end 11 b by, for example, a key.

  Since the circular splines 23 are bolted to the casing 60 b, the decelerated output of the reduction gear portion 20 is transmitted from the bottom portion of the flex spline 22.

  An oil seal is disposed at an axially intermediate portion between the first rolling bearing 14 and the wave generator 21 along the outer circumferential cylindrical surface of the motor rotating shaft 11 to prevent the oil from scattering.

  The output shaft 31 has a substantially cylindrical shape, and one end connected to the reduction gear portion 20 is accommodated in the casing 60b, and the other end protrudes from the casing 60a so that a load can be attached. The output shaft 31 is bolted to the bottom of the flexspline 22 via a connecting member 45.

  At an axially intermediate portion of the output shaft 31, there is a strained portion 31c having a diameter smaller than that of the other portions. For example, a strain gauge 46 is attached to the strain generating portion 31 c in order to measure the twisting torque of the output shaft 31. The strained portion 31c has strength in the axial direction of the output shaft 31 and does not deform, but since the diameter is formed smaller than the other portions, it deforms in the twisting direction. Therefore, the strain gauge 46 is distorted by a twist (shear strain) generated in the strain generating portion 31c, and the strain gauge 46 changes in resistance according to the amount of shear strain.

  The strain gauge 46 is incorporated in a Wheatstone bridge circuit that converts strain generated in the strain generating portion 31c into an electric signal in accordance with torsional torque applied to the output shaft 31, and constitutes a part of the torque detection circuit. The torque detection circuit is mounted on the rotary substrate 32.

  The rotating substrate 32 is an annular disk, and is fixed to the output shaft rod 31b with a screw via a fixing support member such as a support, and rotates together with the output shaft 31. The rotary substrate 32 includes a resistance change detection circuit including a Wheatstone bridge circuit that detects a resistance change of the strain gauge 46, an AD converter that converts the output of the resistance change detection circuit into a digital signal, and a CPU that processes the digital signal. , A rectifier circuit, a stabilization circuit, and the like. The torsion torque measurement value signal sent from the torque detection circuit is converted into an optical signal by the light emitting element 37 and sent to the light receiving element mounted on the fixed substrate 51a by wireless communication.

  The fixed substrate 51a is mechanically and electrically connected to the fixed substrate 51b by, for example, an inter-board connector, and the fixed substrate 51b is fixed to the casing 60g. The fixed substrate 51a and the fixed substrate 51b digitally demodulate a signal of a measured value of torsion torque from a light receiving element such as a photodiode that converts an optical signal emitted from the light emitting element 37 into an electric signal, and a digital modulation signal converted into the electric signal. And a digital demodulation circuit for The fixed substrate 51 b is connected to a control device (not shown) that controls the torque detection gear motor 1 by a wiring cable.

  In addition, a magnetic sheet such as a ferrite sheet is wound around a cylindrical surface of the output shaft 31 to form a secondary core 35. Further, a secondary coil 36 is formed on the outer peripheral cylindrical surface of the secondary core 35 by winding a conductive wire such as a copper wire.

  The primary core 33 is fixed to the fixed substrate 51 a at a position facing the secondary core 35 and the secondary coil 36. The primary core 33 has a pillar shape having a U-shaped protrusion in cross section, and is made of, for example, a magnetic material such as ferrite. The primary coil 34 is a conductive wire such as a copper wire, for example, and is formed by being wound between two protrusions of the primary core 33.

  The fixed substrate 51a and the fixed substrate 51b are provided with a switching circuit connected to a control device (not shown). The switching circuit converts the direct current supplied from the control device into an alternating current. The switching circuit is connected to the primary coil 34 and outputs the converted alternating current to the primary coil 34. However, when an alternating current is supplied by the control device, the switching circuit is unnecessary. The converted alternating current generates an alternating magnetic field in the primary side coil 34 and induces a current in the secondary side coil 36. Therefore, the secondary coil 36 can receive power from the primary coil 34 without contact. The alternating current induced in the secondary side coil 36 is converted into a direct current voltage by the rectification circuit and the stabilization circuit in the rotary substrate 32, and the direct current voltage is supplied to a resistance change detection circuit and the like.

  The output shaft 31 is rotatably supported by casings 60b and 60a via a first rolling bearing 38 and a second rolling bearing 39. The first rolling bearing 38 and the second rolling bearing 39 are, for example, deep groove ball rolling bearings having an outer ring and an inner ring, and they are disposed axially separated from each other.

  The outer peripheral cylindrical surface of the first rolling bearing outer ring 38a faces the inner peripheral cylindrical surface of the casing 60b with a predetermined gap therebetween. A groove 40T is provided over the entire circumference of the inner peripheral cylindrical surface, ie, the facing portion, of the casing 60b. The second elastic member 42T is disposed in the groove 40T. The second elastic member 42T urges the outer circumferential cylindrical surface of the first rolling bearing outer ring 38a in the axial center direction. The second elastic member 42T is, for example, an O-ring, but is not limited to this. Alternatively, a liquid gasket or the like may be injected into a predetermined gap between the outer circumferential cylindrical surface of the first rolling bearing outer ring 38a and the facing portion of the casing 60b and hardened to form an elastic member. Absent.

  The first rolling bearing inner ring 38b and the output shaft 31 are, for example, in a state of being fitted with a tight fit. The axial position of the first rolling bearing inner ring 38b is restricted by the output shaft rod 31b constituting the first restricting means being engaged with the axial end face (load connection side) of the first rolling bearing inner ring 38b. Is done. On the other hand, the other axial end face (the reduction gear portion 20 side) of the first rolling bearing inner ring 38b is not restricted. Further, the other axial end surface (the reduction gear unit 20 side) of the first rolling bearing outer ring 38a is urged in the axial direction B by the first elastic member 41T. On the other hand, one axial end (load connection side) of the first rolling bearing outer ring 38a is not restricted.

  The first restricting means is the output shaft rod 31b formed by the step provided on the output shaft 31, but is not limited to this, and may be a collar fitted to the output shaft 31, or the like. The first elastic member 41T is an elastic member such as a plate spring, for example, which deforms the casing 60b and the first rolling bearing outer ring 38a in the compression direction so as to repel and reciprocate in both axial directions. FIG. 4 shows an example of the first elastic member 41T. The first elastic member 41T is formed by bending an annular flat plate, and abuts on the first rolling bearing outer ring 38a to form the first rolling bearing outer ring 38a. An axially biased portion and a portion abutting the casing 60b are alternately provided in the circumferential direction.

  The second rolling bearing 39 is inserted into the inner circumferential cylindrical surface of the casing 60a with, for example, an extremely small gap. On the other hand, the second rolling bearing inner ring 39b and the output shaft 31 are, for example, in a state of being fitted with a close fit.

  The positions of the second rolling bearing 39 on both axial sides of the second rolling bearing outer ring 39a and the second rolling bearing inner ring 39b are regulated by the second regulating means on both axial sides. That is, the second rolling bearing outer ring 39a is locked by the step portion of the casing 60a and the annular pressing member 43T. The second rolling bearing inner ring 39b is restricted in axial position by the output shaft 31a and the retaining ring 44T. The retaining ring 44T is inserted into a groove provided in the vicinity of a step portion in which the second rolling bearing 39 of the output shaft 31 is fitted. The second restricting means refers to the stepped portion of the pressing member 43T, the retaining ring 44T, and the casing 60a.

  The casing 60a and the casing 60b are fixedly connected by bolts. Therefore, the axial position of the first rolling bearing 38 and the second rolling bearing 39 and the biasing force by the first elastic member 41T can be defined by appropriately defining the axial dimensions of the casing 60a and the casing 60b. Can do.

  An oil seal is disposed along the outer peripheral cylindrical surface of the output shaft 31 at an axially intermediate portion between the first rolling bearing 38 and the flexspline 22 to prevent oil from scattering.

  According to the present embodiment, the first rolling bearing 14 that supports the motor rotating shaft 11 is disposed closer to the reduction gear unit 20 than the second rolling bearing 15. The first rolling bearing 38 supporting the output shaft 31 is disposed closer to the reduction gear unit 20 than the second rolling bearing 39. Both ends of the second rolling bearing 15 and the second rolling bearing 39 are regulated in the axial direction at the end faces of the inner ring and the outer ring. The first rolling bearing 14 and the first rolling bearing 38 are restricted at one end by the end face of the inner ring and at the axial direction while the other end is by the end face of the outer ring toward the one end. Each is urged by the elastic member 41T. Further, the motor rotating shaft 11 and the reduction gear unit 20, and the reduction gear unit 20 and the output shaft 31 are rigidly connected.

  On the other hand, a second elastic member 42M is provided between the outer circumferential cylindrical surface of the outer ring of the first rolling bearing 14 and the facing portion of the casing 60c facing the outer cylindrical surface, and the outer ring of the first rolling bearing 38 A second elastic member 42T is provided between the outer circumferential cylindrical surface and the facing portion of the casing 60b facing the outer circumferential cylindrical surface.

  Since the motor rotation shaft 11 has a higher rotation speed than the output shaft 31, for example, when the motor rotation shaft 11 and the speed reducer unit 20 are rigidly connected, the motor rotation is caused when the component dimensional accuracy and connection assembly accuracy are low. The rotation of the shaft 11 may be disturbed. Since the output shaft 31 has a strain generating portion 31c and the torsion torque of the output shaft 31 is detected by the strain gauge 46, for example, when the output shaft 31 and the speed reducer portion 20 are rigidly connected, the output shaft 31 It may affect the twisting torque detection.

  According to the present invention, even when the motor rotating shaft 11 and the speed reducer unit 20 and the speed reducer unit 20 and the output shaft 31 are rigidly connected, it is necessary to particularly increase the dimensional accuracy and assembly accuracy of these components. The first elastic members 41M and 41T and the second elastic members 42M and 42T absorb these errors, so that it is possible to realize a gear motor with torque detection that performs high-precision torque control.

  As mentioned above, although this invention was demonstrated based on preferable embodiment, this invention is not limited to embodiment mentioned above, A various change and deformation | transformation are possible in the range which does not deviate from the summary.

  As an application example of the present invention, application to industrial robots and the like is possible.

1: Gear motor with torque detection 10: Motor unit 11: Motor rotary shaft 11a, 11b: Motor rotary shaft end 11c: Motor rotary shaft (first regulating means)
11d: Motor rotating shaft rod (second regulating means)
12: permanent magnet 13: stator 14: first rolling bearing 14a: first rolling bearing outer ring 14b: first rolling bearing inner ring 15: second rolling bearing 15a: second rolling bearing outer ring 15b: second Rolling bearing inner ring 20: reduction gear unit 21: wave generator 22: flexspline 23: circular spline 24: sleeve 30: torque detection unit 31: output shaft 31a: output shaft 鍔 (second regulating means)
31b: output shaft rod (first regulating means)
31c: strain generation portion 32: rotating substrate 33: primary side core 34: primary side coil 35: secondary side core 36: secondary side coil 37: light emitting element 38: first rolling bearing 38a: first rolling Bearing outer ring 38b: first rolling bearing inner ring 39: second rolling bearing 39a: second rolling bearing outer ring 39b: second rolling bearing inner ring 40M, 40T: grooves 41M, 41T: first elastic members 42M, 42T : Second elastic member 43M, 43T: presser member (second restricting means)
44M, 44T: Retaining ring (second regulating means)
44G: Retaining ring 45: Connection member 46: Strain gauge 50: Rotational position detecting portion 51a, 51b: Fixed substrate 60: Casing 60a, 60e: Casing (second regulating means)
60b, 60c, 60d, 60f, 60g, 60h: casing

Claims (4)

Motor part,
A reduction gear unit including a gear that decelerates the rotation of a motor rotation shaft of the motor unit;
A torque detector that detects torque applied to the output shaft of the speed reducer;
A casing that houses the motor unit, the speed reducer unit, and the torque detector;
A gear motor with torque detection having
The motor rotation shaft and the output shaft are supported by the casing via a first rolling bearing and a second rolling bearing which are disposed axially separated from each other,
First regulating means for latching an axial direction end surface of an inner ring of the first rolling bearing to regulate an axial position of the first rolling bearing;
A first elastic member which locks the other axial end surface of the outer ring of the first rolling bearing and biases the first rolling bearing toward the one axial end surface;
Second regulating means for latching the axially opposite end faces of the inner ring and the outer ring of the second rolling bearing to respectively regulate the positions on both axial sides of the second rolling bearing;
A second rolling bearing provided between an outer circumferential cylindrical surface of an outer ring of the first rolling bearing and a facing portion of the casing facing the outer circumferential cylindrical surface to urge the outer ring of the first rolling bearing in the axial center direction The elastic member of
A gear motor with torque detection, comprising:   2. The gear motor with torque detection according to claim 1, wherein the first rolling bearing is disposed closer to the speed reducer portion than the second rolling bearing in the axial direction.   The gear motor according to claim 1 or 2, wherein a groove is provided on the entire periphery of the facing portion of the casing, and the second elastic member is disposed in the groove. The torque detection according to any one of claims 1 to 3, wherein at least one of the motor rotation shaft and the reduction gear unit or the reduction gear unit and the output shaft is connected to a rigid. Geared motor.

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