JP2008196566A - Twisted cord type actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost, twisted cord type actuator embodied in a lightweight, space-saving construction by the use of a small-sized motor, assuring low noise, and unlikely to cause the rotational driving output to drop even if the tensile force in the thrust direction increases. <P>SOLUTION: The twisted cord type actuator is equipped with the motor 2, two mutually different output shafts 41 and 42 of a power transmitting mechanism connected with the rotary shaft of the motor 2, and two twisted cords connected with the output shafts, wherein each twisted cord has such a structure that two cord elements are twined together, while the other ends are connected with the object to be driven. A thrust bearing to receive a thrust force applied to the output shafts 41 and 42 in their axial direction as the reaction of the object driven is composed of an annular member 51 made of an oil-impregnated sintered alloy and annular sliding surfaces 442 and 452 of rotation side members 441 and 451 slidable in abutting to the member 51. A still more preferable structure is such that three or more hemispherical projections 511 are provided apart circumferentially on the annular surface on the side confronting the annular sliding surface of the annular member 51. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an actuator applicable to a motor-driven artificial hand, a robot hand, and the like, and more particularly to a twisted string actuator using a twisted string having a structure in which two strings are twisted together and a motor.

  Conventionally, as an actuator using a wire and a motor (hereinafter referred to as a wire actuator), for example, one described in Patent Document 1 or 2 is known. FIG. 8 shows a basic concept of a configuration that is considered to be a related art close to the present invention among various wire actuators for a finger joint using a wire or string (hereinafter simply referred to as a string) and a motor.

  In FIG. 8, a rotating body 102 such as a pulley is connected to a rotating shaft 101a of a motor 101 via a speed reducer. Alternatively, the rotating body 102 is directly connected to the rotating shaft 101a of the motor 101 with a built-in reducer. One string 103, 104 is connected to each of two locations facing the radial direction of the rotating body 102, and the other end of each string 103, 104 is connected to the finger joint 105.

  When the rotating shaft 101a of the motor 101 rotates, the rotating body 102 rotates slowly and the two strings 103 and 104 are driven in opposite directions. That is, one is pulled and the other is loosened. As a result, the finger joint 105 is driven to rotate about the axis AX.

  When using a wire actuator as described above for a motor-driven prosthetic hand or robot hand having many joints, one motor is required for each joint. It is necessary to use a motor. On the other hand, in order to ensure a certain level of gripping force required for a motor-driven artificial hand, a robot hand, or the like, a minimum output torque is required for a drive system including a motor and a speed reducer.

  Even with a small motor, it is possible to obtain a large torque by using a speed reducer. However, since the speed reducer itself increases the weight of the device, for example, the tip of the prosthesis (hand) becomes heavy. Problems arise. Furthermore, since a space for incorporating a reduction gear is required, it is difficult to realize a small and lightweight motor-driven artificial hand or robot hand.

  In addition, when using a gear type speed reducer incorporating a plurality of speed reduction gears, there is a problem of noise generated at the meshing portion of the gears when the gears rotate in addition to the weight and space problems. .

As a wire actuator capable of solving such a problem, the present applicant has previously filed a patent application for an invention related to a twisted string actuator. This twisted string actuator connects one end of a twisted string having a structure in which two strings are twisted together to an object to be driven, and connects the other end of the twisted string directly to the rotating shaft of the motor or a power transmission mechanism. When the rotation shaft of the motor rotates, the length of the twisted cord is shortened by strengthening or loosening the twist of the two cords constituting the twisted cord according to the rotation direction, or As a result, the object to be driven is driven.
Japanese Patent Laid-Open No. 06-008178 Japanese Patent Application Laid-Open No. 07-096485

  In the above-described twisted string actuator, when the twist of the two strings is strengthened and the length of the twisted string is driven in the direction of shortening, the rotating shaft or power transmission of the motor connected to the twisted string The force applied to the axial direction of the output shaft of the mechanism (that is, the thrust direction) increases. That is, as a reaction of the driving force that pulls the driving object toward the motor or the power transmission mechanism, a force that pulls the rotating shaft of the motor or the output shaft of the power transmission mechanism toward the driving object increases.

  As a result, the loss due to the friction of the thrust bearing portion of the motor rotation shaft or the power transmission mechanism output shaft increases, and the rotational drive output decreases from the output that should originally be obtained. In order to avoid such a phenomenon, it is conceivable to use a ball bearing (ball bearing) for the thrust bearing portion of the motor rotation shaft or the power transmission mechanism output shaft to reduce the friction of the thrust bearing portion.

  However, in applications where it is necessary to mount many actuators including motors in a small space, such as articulated motor-driven artificial hands and robot hands, ball bearings are incorporated as thrust bearings due to restrictions on shape, size, cost, etc. It is often difficult.

  In view of the conventional problems as described above, the present invention is a low-cost twist using a small motor that is lightweight, space-saving, low-noise, and less likely to reduce the rotational drive output even if the tensile force in the thrust direction increases. It aims at realizing a string type actuator.

  The twisted string actuator according to the present invention is configured such that one end of a twisted string having a structure in which two strings are twisted together is connected to an object to be driven, the other end of the twisted string is connected to a drive unit rotating shaft, The length of the twisted cord is shortened or extended by strengthening or loosening the twist of the two cords constituting the twisted cord in accordance with the rotation direction of the drive unit rotation shaft. An annular member made of an oil-impregnated sintered alloy is used as a thrust bearing configured to drive a driven object and restricts and holds movement of the drive unit rotation shaft in the axial direction. An annular sliding surface arranged coaxially and fixed to the drive unit fixed side and slidable in contact with the annular member is provided on the drive unit rotation side member fixed to the drive unit rotation shaft. It is characterized by being Claim 1).

  According to such a configuration, the twisted string converts rotational motion (rotational force) in the twist direction into linear motion (tension) in the length direction, and functions as power transmission means including a speed reduction mechanism. Therefore, a speed reducer using a multi-stage gear or the like is not necessary, which can greatly contribute to reducing the size and weight of the entire apparatus. Further, there is no noise generated by a reduction gear using a multistage gear or the like, and a silent actuator can be realized. In addition, since there is a certain degree of flexibility and elasticity between the rotational movement in the torsional direction and the linear movement in the longitudinal direction of the twisted string, an elastic biasing means such as a spring or an air cylinder must be used. However, it is possible to realize a so-called soft actuator. Thereby, for example, a compliance function like a human hand can be easily realized. Furthermore, since the thrust bearing with a simple structure using oil-impregnated sintered alloy restricts and holds the drive unit in the axial direction, the rotational drive output decreases even if the tensile force in the thrust direction increases. It is possible to realize an inexpensive twisted string actuator that is difficult to perform.

  In a preferred embodiment of the present invention, among the annular surfaces of the annular member made of an oil-impregnated sintered alloy fixed to the drive unit fixing side, three on the surface facing the drive unit rotation side member The hemispherical protrusions described above are provided apart from each other in the circumferential direction, and the tip of the hemispherical protrusion is configured to be slidable in contact with the annular sliding surface of the drive unit rotation side member ( Claim 2).

  According to such a configuration, the contact area between the annular member made of the oil-impregnated sintered alloy and the annular sliding surface of the driving unit rotating side member is larger than that in the case where the opposing surfaces slide in surface contact with each other. The output loss due to the sliding friction between them is reduced. As a result, it is possible to realize an inexpensive twisted string actuator in which the rotational drive output is less likely to be lowered even when the tensile force in the thrust direction is increased.

In another preferred embodiment of the present invention, the twisted string actuator includes one motor and the drive unit rotary shaft that is two different output shafts of the power transmission mechanism connected to the rotary shaft, Two twisted strings connected to two drive unit rotating shafts, and when the rotating shaft of the motor rotates, the length of one of the two twisted strings is shortened and the other length Is configured to be stretched,
A thrust bearing including the annular member is provided on each of the two drive unit rotating shafts.

  According to such a configuration, one of the two twisted strings can be shortened while the other is extended by the rotation of one motor. Therefore, for example, a finger joint that can rotate around the axis can be easily and quickly driven as a driving object. In other words, one of the two locations facing each other across the rotation axis of the finger joint is driven by one of the two twisted strings, and the other is driven by the other of the two twisted strings. That's fine. In such a string actuator, the thrust bearing including the annular member is provided on each of the two drive unit rotation shafts, so that the rotational drive output is reduced even if the tensile force in the thrust direction is increased. It is possible to provide an inexpensive and compact twisted string actuator that is difficult.

  As described above, according to the twisted string actuator of the present invention, a small motor is used for light weight, space saving, low noise, and the rotational drive output is less likely to decrease even when the tensile force in the thrust direction increases. A twisted string actuator can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, when describing the positional relationship and direction of each member vertically and horizontally, it means the positional relationship and direction in the drawings to the last, and it means the positional relationship and direction when incorporated in an actual device. is not.

  FIG. 1 is a schematic diagram showing the concept of a twisted string actuator according to the present invention. As shown in FIG. 1, the twisted string actuator according to the present invention uses a twisted string 1 and a motor 2 having a structure in which two strings or wires (hereinafter simply referred to as strings) 11 and 12 are loosely twisted together. Composed. FIG. 1A schematically shows a state in which the twisting of the two cords 11 and 12 is loosened to form two parallel cords, and FIG. 12 schematically shows a state in which 12 are twisted together. One end side of the twisted string 1, that is, the two strings 11, 12 is connected (fixed) to the driving object OB, and the other end side is connected (fixed) to the rotating shaft 21 of the motor 2.

  The length of the twisted cord 1 in the state shown in FIG. 1 (a) is L, and the rotating shaft 21 of the motor 2 rotates from this state to constitute the twisted cord 1 as shown in FIG. 1 (b). When the two cords 11 and 12 are twisted together, the length of the twisted cord 1 is L−ΔL. That is, when the two cords 11 and 12 are twisted together, the length of the twisted cord 1 is shortened by ΔL. As a result, the driving force F in the direction (right direction) attracted to the motor 2 by the tension of the twisted string 1 acts on the driving object OB. Therefore, the twisted string 1 has a function of converting the rotational motion in the twisted direction (the rotational force of the motor 2) into the linear motion (tension) in the lengthwise direction.

  When the rotating shaft 21 of the motor 2 rotates in the direction opposite to the above from the state of FIG. 1B, the twist of the two cords 11 and 12 constituting the twisted cord 1 is loosened. At this time, although not shown in FIG. 1, if it is assumed that the object OB is urged leftward by an urging means such as a tension spring, the object OB moves away from the motor 2 by the urging force (left Direction) and the length of the twisted string 1 is extended. It can be seen that the length of the twisted cord 1 is the longest value (L) in the state of FIG. 1A in which the twisting of the two cords 11 and 12 is loosened to form two parallel cords. .

  Therefore, according to the twisted string actuator of the present invention using the twisted string 1 and the motor 2 having a structure in which the two strings 11 and 12 are loosely twisted together, according to the rotation direction of the rotating shaft 21 of the motor 2. The twist of the two cords 11 and 12 constituting the twisted cord 1 is strengthened or loosened, so that the length of the twisted cord 1 is shortened or extended, and as a result, the drive object OB is set within a predetermined range. It is possible to drive within.

  Since the twisted string 1 functions as power transmission means including a speed reduction mechanism, a speed reducer using a multi-stage gear or the like is not required, and can greatly contribute to reduction in size and weight of the entire apparatus. In addition, there is no noise generated by a reduction gear using a multistage gear or the like, and a silent actuator can be realized. In general, a twisted string is less expensive than a speed reducer using a multistage gear or the like, so that the cost of the actuator can be reduced.

  Further, since there is a certain degree of flexibility and elasticity between the rotational movement in the twist direction and the linear movement in the length direction of the twisted string 1, it is not necessary to use an elastic biasing means such as a spring or an air cylinder. However, it is possible to realize a so-called soft actuator. Thereby, for example, a compliance function like a human hand can be easily realized.

  FIG. 2 is a schematic diagram showing an application example in which a finger joint is driven using a twisted string actuator according to the present invention. In this schematic diagram, a finger joint FJ that can rotate about an axis AX corresponds to a drive object. As shown in FIG. 2, in order to regulate the driving direction and driving range of the finger joint FJ as a driving object, a slide member 32 that is movable within a predetermined range along the slide guide 31 is provided, and the twisted string 11 is provided. Is connected to the finger joint FJ through the slide member 32.

  In addition, two sets of actuator kits including the twisted string 1 and the slide member 32 are provided, and one end side of the twisted string 1 of the two sets of actuator kits is connected to two locations P1 and P2 facing each other across the axis AX of the finger joint FJ. Each is connected via a slide member 32.

  In the configuration of FIG. 2, the driving direction and driving range of the finger joint FJ that is a driving target can be easily regulated by the slide guide 31 and the slide member 32. In addition, since design flexibility regarding the distance and direction between the motor 2 and the finger joint FJ can be secured, it becomes easy to cope with the limitation of the space where the actuator is mounted, and the effective use of the space is facilitated. It becomes possible. In FIG. 2, the driving direction of the finger joint FJ and the axial center direction of the rotating shaft 21 of the motor 2 are substantially the same. However, by bending the flexible twisted string 1 using, for example, a pulley or the like, both directions are changed. It is also possible to configure it to be 90 degrees different. It is also possible to bring the finger joint FJ and the motor 2 closer to or away from each other.

  Further, by driving the twisted cords 1 of the two sets of actuators in opposite directions, for example, as shown in FIG. 2, the upper twisted cord 1 is driven in a shortening direction, and the lower twisted cord 1 is driven. Is driven in the direction of stretching. Thereby, the finger joint FJ can be driven easily and accurately. In the configuration shown in FIG. 2, two motors 2 are used to individually drive the twisted strings 1 of two sets of actuator kits. In this configuration, it is necessary to control driving of the two motors 2 in synchronization. It is also preferable to provide an interlock circuit that prevents only one motor 2 from operating. In order to simplify such control and circuit, as will be described later, a single motor may be used to simultaneously drive the twisted strings 1 of two sets of actuator kits.

  FIG. 3 is a schematic diagram showing an application example of the twisted string actuator shown in FIG. 2 to a plurality of finger joints. A state in which two finger joints FJ1 and FJ2 are pivotally connected by an axis AX1 is shown. The finger joint FJ1 can rotate about the axis AX1, and the finger joint FJ2 can rotate about the axis AX2. Although omitted in FIG. 3, the finger joint FJ2 is also provided with two sets of actuator kits including the twisted string 1 and the slide member 32 in two positions opposite to each other with the axis AX2 interposed therebetween, similarly to the finger joint FJ1. One end side of the twisted string 1 of the two sets of actuator kits is configured to be connected via a slide member 32. In this way, two twisted strings 1 are used for one joint, and in the case of n joints, 2n twisted strings 1 are used.

  FIG. 4 is a schematic diagram showing a configuration example in which two twisted strings are simultaneously driven by one motor. This configuration example is configured to drive the twisted strings 1 of two sets of actuator kits simultaneously using one motor in the configuration shown in FIG. 2 or FIG. That is, the other end side (motor side) of the twisted string 1 of the two sets of actuator kits corresponds to two different output shafts (drive unit rotary shafts) of the power transmission mechanism 4 connected to the rotary shaft 21 of the motor 2. ) 41 and 42. When the rotating shaft 21 of the motor 2 rotates, the upper first output shaft 41 rotates in a direction to increase the twist of the twisted string 1 connected thereto, and the lower second output shaft 42 twists connected thereto. It is comprised so that it may rotate in the direction which loosens the twist of a string.

  In this configuration, while using an actuator kit including two sets of twisted cords 1 for one finger joint FJ1, the twisted cords 1 are simultaneously driven by one motor 2, so that the two motors individually Drive control is simpler than in the case of driving. In addition, the finger joint FJ1 can be driven quickly.

  In the configuration shown in FIG. 4, as the power transmission mechanism 4, a speed reduction / reversal mechanism using one pinion gear 43 and two flat gears 44 and 45 is used. The pinion gear 43 is fixed to the rotating shaft 21 of the motor 2, the upper flat gear 44 is fixed to the first output shaft 41 to which the upper twisted string 1 is connected, and the lower flat gear 45 is connected to the lower twisted gear 45. It is fixed to the second output shaft 42 to which the string 1 is connected. Since the upper flat gear 44 and the lower flat gear 45 rotate in the same direction (both directions opposite to the pinion gear 43), the twist directions of the twisted cords 1 of the two sets of actuator kits must be opposite to each other. There is.

  That is, when the rotating shaft 21 of the motor 2 rotates, the first output shaft 41 and the second output shaft 42 rotate in the same direction (both directions opposite to the rotating shaft 21 of the motor 2). Since the twisting directions are opposite to each other, for example, as shown in FIG. 4, the upper twisted string 1 is driven in a direction to increase the twist (the direction in which the length is shortened), and the lower twisted string 1 is twisted. Driven in the loosening direction (the direction in which the length extends).

  By changing the number and combination of the gears constituting the power transmission mechanism 4, the power transmission mechanism 4 is configured so that the rotation directions of the two output shafts 41 and 42 are opposite to each other, and two upper and lower twisted strings One twist direction may be the same as each other. In short, when the rotating shaft 21 of the motor 2 rotates, one of the first output shaft 41 and the second output shaft 42 rotates in a direction to increase the twist of the twisted string 1, and the other in a direction to loosen the twist of the twisted string. What is necessary is just to comprise the power transmission mechanism 4 and the twisted string 1 so that it may rotate. However, it is desirable to configure the power transmission mechanism 4 so that the output torques of the first output shaft 41 and the second output shaft 42 are equal to each other, or so that both are balanced.

  Further, in order to avoid the generation of noise at the meshing portion between the gears, the power transmission mechanism 4 is configured by using a plurality of rollers or rollers and belts that transmit power by the frictional force of the contact surface instead of the gears. May be. It is also desirable to reduce noise generated from the motor 2 by using a DC brushless motor as the motor 2.

  Next, the structure of the thrust bearing in the twisted string actuator as described above will be described.

  FIG. 5 is a cross-sectional view showing the structure of the motor and gear box of the twisted string actuator according to the first embodiment of the present invention. In the structural example shown in FIG. 5, the gear box corresponding to the power transmission mechanism 4 and the motor 2 are integrally coupled. The gear box 4 has a box shape surrounded by a base end side plate 46, a front end side plate 47, and a side plate 48, and the above-described pinion gear 43, flat gears 44, 45, and the like are accommodated in the internal space thereof. Yes.

  A through hole through which the rotating shaft 21 of the motor 2 and the pinion gear 43 fixed thereto is inserted is formed in the central portion of the base end side plate 46 of the gear box 4, and the motor is formed on the outer side surface (lower surface) around it. A stepped recess for receiving the tip of the two cases is formed. The stepped recess of the base end plate 46 and the case tip of the motor 2 are fixed to each other by means such as fitting, bonding, and screwing.

  Further, on the inner side surface (upper surface) of the base end side plate 46, two fixed shaft members 49 for rotatably supporting the flat gears 44 and 45 are provided on both sides at a predetermined distance from the central through hole. It is installed. Cylindrical portions 441 and 451 are integrally provided above and below the spur gears 44 and 45, and sleeve bearings that are externally fitted to the fixed shaft member 49 are provided at the center thereof. Thereby, the spur gears 44 and 45 can be supported by the fixed shaft member 49 and can idle. Further, the spur gears 44 and 45 are screwed into the pinion gear 43 and are driven to rotate as the rotating shaft 21 of the motor 2 rotates.

  The output shafts 41 and 42 are integrally provided so as to protrude upward (front end side) from the upper central portion of the spur gears 44 and 45, respectively, and the output shaft 41, Two through holes into which 42 is inserted are formed. The output shaft 41 (42), the cylindrical portion 441 (451), and the spur gear 44 (45) may be integrally formed as individual members, or may be all or part of them. (2 out of 3) may be formed as an integral member from the beginning.

  Further, an annular groove is formed around the through hole through which the output shafts 41 and 42 are inserted on the inner side surface (lower surface) of the tip side plate 47, and an annular member made of oil-impregnated sintered alloy is formed in this groove. 51 is fitted and fixed by means such as adhesion. In addition, annular sliding surfaces 442 and 452 that are slidable in contact with the annular member 51 are formed on the distal ends of the cylindrical portions 441 and 451 (corresponding to the driving portion rotating side member). In addition, the part enclosed with the dashed-two dotted line rectangle in the upper part of FIG. 5 has shown the top view seen from the axial direction of the annular member 51. FIG.

  The annular member 51 has a function of a thrust bearing that restricts and holds the movement of the output shafts (drive unit rotation shafts) 41 and 42 in the axial direction. That is, when the twist of the twisted string connected to the distal end portion of the output shafts 41 and 42 is strengthened and the length of the twisted string is shortened, the output shafts 41 and 42 are counteracted by the driving force that attracts the drive target. Is pulled in the direction of the driven object (hereinafter referred to as thrust force). This thrust force is received when the annular sliding surfaces 442 and 452 on the front end side of the cylindrical portions 441 and 451 which are driving portion rotating side members come into contact with the annular member 51.

  Since the annular member 51 is made of an oil-impregnated sintered alloy and realizes smooth sliding with the annular sliding surfaces 442 and 452 on the rotation side, even if the thrust force increases, the rotational drive output is unlikely to decrease. Moreover, a space-saving and inexpensive thrust bearing can be realized as compared with the case where a ball bearing is used. Thereby, a small and inexpensive twisted string actuator can be realized.

  Next, FIG. 6 is a cross-sectional view showing the structure of the motor and gear box of the twisted string actuator according to the second embodiment of the present invention. This embodiment will be described focusing on differences from the first embodiment.

  In the first embodiment, the contact surface of the annular member 51 constituting the thrust bearing with the rotation-side annular sliding surfaces 442 and 452 is a flat surface, and both slide in surface contact with each other. On the other hand, in the second embodiment, as shown in FIG. 6, there are three or more annular members 51 on the annular surface facing the rotating annular sliding surfaces 442 and 452 (12 in the illustrated example). Of the hemispherical protrusions 511 are provided apart from each other in the circumferential direction, and the tip ends of the hemispherical protrusions 511 are in contact with the annular sliding surfaces 442 and 452. In other words, the thrust bearing is constituted not by surface contact but by three or more point contacts.

  According to the configuration of the present embodiment, the area of the contact surface (sliding surface) is smaller than that in the case where the thrust bearing of Embodiment 1 is configured by surface contact, resulting in sliding friction on the contact surface. Output loss is reduced. As a result, an inexpensive twisted string actuator can be realized in which the rotational drive output is less likely to decrease even when the thrust force increases.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to said embodiment, It is possible to implement with a various form. Several other embodiments are briefly described below.

  In the first and second embodiments, the axial dimension (thickness) of the annular member 51 forming the thrust bearing is increased and the inner diameter is decreased so that the inner peripheral surface thereof can contact the output shafts 41 and 42. Also good. That is, the annular member 51 can be configured to serve as the radial bearing that supports the output shafts 41 and 42 in the radial direction and the thrust bearing.

  In the first and second embodiments, the torsion string is connected to the output shaft of the gear box 4 that is a power transmission mechanism, that is, the torsion string actuator shown in FIG. 4, but as shown in FIG. In addition, the present invention can be applied to a configuration in which the twisted string 1 is directly connected to the rotating shaft 21 of the motor 2. A configuration example in this case is shown in FIG.

  In FIG. 7, a sleeve 24 made of an oil-impregnated sintered alloy provided at the center of the case tip side 23 of the motor 2 functions as a radial bearing of the rotary shaft 21 and contacts the tip side surface (upper surface) of the rotor 25. It also functions as a thrust bearing that can slide in contact. In the illustrated example, like the thrust bearing of the second embodiment, three or more hemispherical protrusions 241 are provided on the annular surface facing the rotor 25 of the sleeve 24 so as to be spaced apart in the circumferential direction. The tip of the protrusion 241 comes into contact with the upper surface (annular sliding surface) of the rotor 25. In order to further reduce the sliding resistance between the hemispherical protrusion 241 and the upper surface of the rotor 25, a lubricant or the like may be applied between them.

  The above-described twisted string actuator according to the present invention is applicable not only to finger joints such as motor-driven artificial hands and robot hands but also to wrist joints and other various joints. Furthermore, the present invention is not limited to a rotational motion such as a joint, and the twisted string actuator of the present invention can be used as an actuator for a member that reciprocates.

It is a schematic diagram which shows the concept of the twisted string type actuator by this invention. It is a schematic diagram which shows the application example which drives a finger joint using the twisted string type actuator by this invention. It is a schematic diagram which shows the example of application to the multiple finger joint of the twisted string type actuator shown in FIG. It is a schematic diagram which shows the structural example which drives two twisted strings simultaneously with one motor. It is sectional drawing which shows the structure of the motor and gear box of the twisted string type actuator which concern on 1st Embodiment of this invention. It is sectional drawing which shows the structure of the motor and gear box of the twisted string type actuator which concern on 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the motor of the twisted string type actuator which concerns on another embodiment of this invention. It is a schematic diagram which shows the basic concept of the structure of the wire type actuator which concerns on a prior art example.

Explanation of symbols

1 twisted string 2 motor 4 power transmission mechanism (gearbox)
11, 12 Two strings constituting a twisted string 21 Motor rotation shaft 41, 42 Output shaft (drive unit rotation shaft)
51 annular member 442, 452 annular sliding surface of driving unit rotation side member 511 hemispherical protrusion

Claims (3)

One end of a twisted string having a structure in which two strings are twisted together is connected to an object to be driven, the other end of the twisted string is connected to a drive unit rotating shaft, and depending on the rotation direction of the drive unit rotating shaft The twisting of the two strings constituting the twisted string is strengthened or loosened so that the length of the twisted string is shortened or extended, and as a result, the driven object is driven. Configured,
An annular member made of an oil-impregnated sintered alloy is disposed coaxially with the drive unit rotation shaft and fixed to the drive unit fixed side as a thrust bearing that regulates and holds the drive unit rotation shaft in the axial direction. The twisted string actuator is characterized in that an annular sliding surface that is slidable in contact with the annular member is provided on the drive portion rotation side member fixed to the drive portion rotation shaft. . Of the annular surface of the annular member made of an oil-impregnated sintered alloy fixed to the drive unit fixing side, three or more hemispherical protrusions are arranged on the surface facing the drive unit rotation side member. 2. The structure according to claim 1, wherein the hemispherical projecting portion is provided so as to be slidable in a direction, and a tip end portion of the hemispherical projecting portion is in contact with an annular sliding surface of the driving portion rotating side member. Twisted string actuator. One motor, two drive shafts which are two different output shafts of the power transmission mechanism connected to the rotation shaft, and the two twists connected to the two drive portion rotation shafts When the rotation shaft of the motor is rotated, one length of the two twisted strings is shortened and the other length is extended,
The twisted string actuator according to claim 1, wherein a thrust bearing including the annular member is provided on each of the two drive unit rotating shafts.

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