JP2010065718A - Load-sensitive continuously variable transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small load-sensitive continuously variable transmission mechanism having a simple structure. <P>SOLUTION: The mechanism includes a main shaft 11 having a spiral thread with a predetermined pitch, and a vibration transmission body 12 having a screw hole 13 with a spiral screw groove having the same pitch as the screw thread of the main shaft 11, to receive the vibration from a vibration generating device such as a motor 14, etc. The diameter of the screw thread of the main shaft 11 is configured to be smaller than the diameter of the screw groove of the screw hole 13. The main shaft 11 is eccentrically screwed into the screw hole 13 with a clearance. The vibration transmission body 12 is moved in a circle by the vibration supplied from the vibration generating device such as the motor 14, etc., and is linearly moved in the axial direction by rotating the main shaft 11 at a rotational speed corresponding to the load applied to the main shaft 11, and by screwing the screw thread into the screw groove. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a load-sensitive continuously variable transmission mechanism that can be used in various fields such as industrial robots and medical robots.

  Screws or ball screws are widely used as a conversion mechanism for converting rotational motion of an electric motor or the like into linear motion in all fields of industry. However, since the gear ratios are fixed, it is usually necessary to select a large reduction gear ratio so that the operation is possible even under the conditions that generate the maximum thrust among the usage conditions. Therefore, there is a big problem that even when the load is light, it can be driven only at a low speed. Therefore, there is a need for a drive system having a load-sensitive speed change function that can change the speed ratio according to the load.

  Under such circumstances, Patent Literature 1 and Patent Literature 2 disclose a load-sensitive continuously variable transmission having the following configuration. In the screw shaft and the nut configured by screwing of the helical screw portion having a predetermined pitch, the diameter of the screw portion of the nut is slightly larger than the diameter of the screw portion of the screw shaft screwed into the nut, and the nut The support member is rotatably supported, and the support member is biased by a predetermined spring load in the screw shaft diameter direction so that the nut is eccentrically contacted with the screw shaft.

JP 2000-193061 A Japanese Patent Laid-Open No. 10-122323

  In Patent Documents 1 and 2, the screw shaft is directly rotated, and a gear, a pulley, and the like are required. In addition, a power source for rotating the screw shaft must be directly connected. For this reason, there is a problem that the structure becomes complicated, miniaturization is difficult, and remote control cannot be performed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a small load-sensitive continuously variable transmission mechanism with a simple structure.

  In order to achieve the above object, a load-sensitive continuously variable transmission mechanism according to a first aspect of the present invention includes a main shaft having a helical thread having a predetermined pitch, and a helical screw having the same pitch as the screw thread of the main shaft. A vibration transmission body having a screw hole in which a groove is formed and receiving vibration from a vibration generator, wherein the diameter of the thread of the main shaft is smaller than the diameter of the screw groove of the screw hole, Is screwed with a clearance in the screw hole so that it can be eccentrically moved, and the vibration transmitting body is moved circularly by vibration supplied directly or indirectly from the vibration generating device, and the rotational speed according to the load applied to the main shaft The main shaft is rotated and the shaft is linearly moved by screwing the screw thread and the screw groove.

  The load-sensitive continuously variable transmission mechanism according to the second aspect of the present invention has a helical thread having a predetermined pitch, a main shaft that receives vibration from a vibration generator, and a screw thread having the same pitch as the screw thread of the main shaft. A movable body having a screw hole in which a spiral screw groove is formed, and the diameter of the screw thread of the main shaft is configured to be smaller than the diameter of the screw groove of the screw hole, and the main shaft has a gap in the screw hole. The main shaft is circularly moved by vibration supplied directly or indirectly from the vibration generator, and the movable body is rotated at a rotational speed corresponding to a load applied to the movable body. Then, the screw thread and the screw groove are screwed together to move linearly in the axial direction of the main shaft.

  Furthermore, a vibration generating device that supplies vibration directly or indirectly to the vibration transmitting body or the main shaft is provided.

  Furthermore, the vibration generating device is a motor.

  Furthermore, a weight is provided on the shaft of the motor.

Furthermore, the vibration generator is a piezoelectric element.
Furthermore, a first piezoelectric plate and a second piezoelectric plate constituted by the piezoelectric elements are respectively disposed in parallel with the main axis, and the first piezoelectric plate has the main axis with respect to the second piezoelectric plate. It is characterized by being positioned substantially perpendicular to the center.

  According to the present invention, the main shaft or the movable body can be moved at a rotational speed corresponding to the load by supplying vibration. For this reason, a mechanism for transmitting rotational motion is not required, and a small and lightweight load-sensitive continuously variable transmission mechanism can be realized with a simple structure.

(Embodiment 1)
The configuration of the first embodiment of the load-sensitive continuously variable transmission mechanism according to the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the load-sensitive continuously variable transmission mechanism mainly includes a vibration transmission body 12 having a main shaft 11 and a screw hole 13, and a motor 14 that is a vibration generating device.

  The main shaft 11 is a rod having a circular cross section, and a helical thread is formed on the outer peripheral surface thereof.

  The vibration transmitting body 12 is formed with a through screw hole 13 having a thread groove formed therein, and the main shaft 11 is inserted into the screw hole 13. When the vibration transmitting body 12 is installed and used on another member such as a support member, the vibration absorbing member 17 may be installed so as not to transmit vibration to the other member. An elastic body such as a spring or rubber or various shock absorbing materials may be appropriately installed.

  As shown in FIG. 3, the pitch P of the thread of the main shaft 11 and the thread of the vibration transmitting body 12 have the same width. Further, the diameter r of the thread of the main shaft 11 is configured to be smaller than the diameter R1 of the thread groove of the vibration transmitting body 12. For this reason, the main shaft 11 is in a state of being screwed into the screw hole 13 with a gap. That is, the central axis of the main shaft 11 can be eccentric with respect to the central axis of the screw hole 13. The diameter r of the thread of the main shaft 11 is configured to be larger than the diameter R2 of the thread of the vibration transmitting body 12. That is, the diameter r of the thread of the main shaft 11 has a relationship of R2 <r <R1. This is to prevent the main shaft from coming off when the central axis of the main shaft 11 becomes zero with respect to the central axis of the screw hole 13.

  The motor 14 is installed so as to penetrate the motor rotation shaft 16 through the vibration transmitting body 12. A weight 15 is installed at the tip of the motor rotating shaft 16. When the motor 14 is energized from a power source (not shown), the motor rotating shaft 14 rotates to supply vibration to the vibration transmitting body 12. Since the motor rotating shaft 14 is provided with the weight 15 whose center axis is shifted, eccentricity occurs, and vibration that causes the vibration transmitting body 12 to move circularly is supplied. The weight 15 is for circularly moving the vibration transmitting body 12 with a larger radius, and may be installed according to the application using the load-sensitive continuously variable transmission mechanism.

  Further, as shown in FIG. 4, the main body of the motor 14 may be directly fixed to the vibration transmitting body 12. Thus, even if the motor 14 is installed, it is possible to supply vibration that can cause the vibration transmitting body 12 to move circularly.

  Next, with reference to FIG. 5, the principle of rotating the main shaft 11 by applying a circular motion to the vibration transmitting body 12 will be described. Here, a simple circle will be described without considering the screw holes 13 and the threads of the main shaft 11.

  Consider a case where a screw hole 13 having a radius R is in contact with a main shaft 11 having a radius r (<R). At this time, the center of the screw hole 13 and the main shaft 11 is eccentric by e. The vibration transmitting body 12 is vibrated so as to draw a counterclockwise circle in the order of (A), (B), (C), (D), and (E). This is one cycle. In addition, since the vibration transmission body 12 is supported by two points, the motor 14 and the main shaft 11, it does not rotate. Also, the black circles shown in FIGS. 5A to 5E indicate contact points between the main shaft 11 and the vibration transmitting body 12 in the initial state (the state of FIG. 5A).

When the vibration transmitting body 12 is vibrated so as to draw a circle, since the circumference l (2πr) of the main shaft 11 is smaller than the circumference L (2πR) of the screw hole 13, the main shaft 11 rotates due to frictional force or the like. That is, since the contact point in FIG. 5A is shifted by L−1 in (E) after one cycle, the spindle 11 rotates by an angle θ of the following equation.

  Therefore, the greater the amount of eccentricity e, the greater the rotation angle θ of the main shaft 11, and the rotation speed in one cycle of vibration increases. On the other hand, if the amount of eccentricity e is small, the rotational speed of the main shaft decreases. When the amount of eccentricity e is 0, the main shaft 11 moves circularly integrally with the vibration transmitting body 12 and does not rotate.

  Next, the case of screws will be considered with reference to FIGS. For simplicity of explanation, the main shaft 11 will be described as a male screw 21 and the vibration transmitting body 12 will be described as a female screw 22. As shown in FIG. 6A, it is assumed that the distances from the contact point between the male screw 21 and the female screw 22 to the respective centers are r and R, and the respective centers are decentered by e.

  As shown in FIG. 6B, the trajectory when the screw is rotated can be developed in a hatched line. The lengths of the oblique lines when the screw makes one turn are L and l shown in FIG. 6C, respectively. When the female screw 22 is vibrated so as to make a circular motion, the male screw 21 rotates by (Equation 1). When the amount of eccentricity e decreases, L−1 also decreases, so the angle θ that rotates in one cycle also decreases. Therefore, the reduction ratio is increased.

  That is, if the amount of eccentricity e decreases according to the load F, the gear can be shifted according to the load F. A cross-sectional view of the screw is shown in FIG. The thread shape is a triangular screw, and the thread angle is φ. Consider the case where the female screw 22 is stationary and a load is applied to the male screw 21 as shown in FIG.

  At this time, the component force f of the load F works due to the inclination of the thread. On the other hand, a frictional force fμ is generated between the male screw 21 and the female screw 22. If the friction angle is equal to or less than φ, the male screw 21 slides to the position shown in FIG. At this time, the eccentricity e becomes zero.

  Here, as shown in FIG. 9, it is considered to vibrate the female screw 22 in the X-axis direction. At this time, when the component force fm of the inertial force in the inclination direction of the thread acting on the male screw 21 becomes larger than the sum of the frictional force fμ and the component force f, the male screw 21 can move. The amount of eccentricity is | e |> 0. While the frictional force fμ and the component force f increase in proportion to the load F, the maximum value of the component force fm of the inertial force depends on the input vibration. Therefore, when the load F increases, the eccentricity e decreases. Become. That is, it can be seen that the reduction ratio increases as the load F increases.

  When the vibration is supplied from the motor 14 as in the above principle, the vibration transmitting body 12 performs a circular motion. The spindle 11 rotates at a speed corresponding to the amount of eccentricity. Since the screw shaft 13 is screwed into the screw hole 13 by the thread applied to the outer peripheral surface of the main shaft 11, the main shaft 11 linearly moves in the axial direction when the main shaft 11 rotates. Since the rotation speed of the main shaft 11 changes according to the load applied to the main shaft 11, the moving speed of the main shaft 11 in the axial direction changes.

  When a reverse current is passed through the motor 14, the vibration transmission body 12 performs a circular motion in the reverse direction. Thereby, since the autorotation direction of the main shaft 11 is reversed, the main shaft 11 moves in the reverse direction.

  In the load-sensitive continuously variable transmission mechanism of the present embodiment, no shaft or gear is used to convert the moving speed of the main shaft 11. For this reason, it is a simple structure and can be configured to be small and light. Only the amount of eccentricity between the main shaft 11 and the screw hole 13 changes according to the load, and a smooth speed change can be performed. For this reason, there is an advantage that the shift can be performed without difficulty even when the load is working, and the load can be continuously supported even during the shift process.

  In the above description, the motor 14 is used as the vibration generator. However, the present invention is not limited to this, and various vibration generators that can circularly move the vibration transmitting body 12 can be used. As an example, a mode using a piezoelectric element is shown in FIG. A piezoelectric element is an element that converts a force applied to a piezoelectric body using a piezoelectric effect into a voltage, or converts an applied voltage into a force.

  One end of the piezoelectric plates 31 and 32 is connected to the L-shaped support portion 33, and the other is connected to the vibration transmitting body 12. The piezoelectric plates 31 and 32 have a structure in which a plate-like piezoelectric element is sandwiched between two plate-like electrodes. When an AC voltage is applied between the electrodes, continuous warping occurs and vibrations occur. Vibration is supplied to the transmission body 12.

  As the piezoelectric plates 31 and 32, monomorph type or bimorph type piezoelectric plates may be used. The monomorph type has a structure in which a piezoelectric element and a metal plate are bonded together and sandwiched between two electrodes. When a voltage is applied between the electrodes, the piezoelectric element expands and contracts in the plane. Since the dimensions of the bonded metal plates remain the same, the piezoelectric plates 31 and 32 are warped.

  The bimorph type has a structure in which two piezoelectric elements are bonded between electrodes. When a voltage is applied, one piezoelectric element expands and the other piezoelectric element contracts. As a result, the piezoelectric plates 31 and 32 are warped.

  The piezoelectric plates 31 and 32 are arranged in parallel to the main shaft 11, respectively. The piezoelectric body 31 is installed at an angle substantially perpendicular to the piezoelectric body 32 with the main shaft 11 as the center. By arranging in this way, the piezoelectric plates 31 and 32 supply vibrations that cause the vibration transmitting body 12 to move circularly as follows.

  FIG. 11 shows a state in which the movements of the piezoelectric plates 31 and 32 and the vibration transmitting body 12 are viewed from the axial direction. In the figure, the broken lines indicate the positions of the vibration transmission plate 12 and the screw holes 13 in the initial state (the state of FIG. 11A), and the one-dot broken lines indicate the positions of the vibration transmission plate 12 and the screw holes 13 in each state. Show. First, from the state of FIG. 11A, a switch (not shown) is turned on to apply a voltage to each of the piezoelectric plates 31 and 32. AC voltages having different phases are applied to the piezoelectric plates 31 and 32, respectively. As shown in FIG. 11B, first, the piezoelectric plate 32 warps in the X-axis (+) direction, and the vibration transmitting body 12 moves in the X-axis (+) direction. As a result, the vibration transmitting body 12 moves in the X-axis (+) direction.

  Subsequently, as shown in FIG. 11C, the piezoelectric plate 32 is restored in the X-axis (−) direction, and the piezoelectric plate 31 is warped in the Y-axis (−) direction. For this reason, the vibration transmitting body 12 moves in the Y-axis (−) direction. Since the vibration transmitting body 12 receives the action of both the piezoelectric plates 31 and 32, the vibration transmitting body 12 moves not by linear movement but by circular movement in the clockwise direction.

  Further, as shown in FIG. 11D, the piezoelectric plate 32 is warped in the X-axis (−) direction, the piezoelectric plate 31 is restored in the Y-axis (+) direction, and the vibration transmitting body 12 is in the X-axis (−) direction. Move to. Further, as shown in FIG. 11E, the piezoelectric plate 32 is restored in the X-axis (+) direction, and the piezoelectric plate 31 is warped in the Y-axis (+) direction. Move in the +) direction.

  In each process, since the piezoelectric plates 31 and 32 are repeatedly warped, the vibration transmitting body 12 moves in a clockwise curve instead of linear movement. Thus, since the piezoelectric plate 32 supplies vibration in the X-axis direction and the one piezoelectric plate 31 supplies vibration in the Y-axis direction, it is possible to supply vibration that causes the vibration transmitting body 12 to continuously move circularly. .

  If a voltage is applied in the opposite direction, the piezoelectric plates 31 and 32 repeat displacement in the opposite direction to the above, so that the vibration transmitting body 12 can be moved in a counterclockwise direction. The main shaft 11 can be rotated and moved back and forth by the circular motion of the vibration transmitting body 12.

  The longer the piezoelectric plates 31 and 32, the larger the warp, and the larger vibration can be supplied. Conversely, the shorter the piezoelectric plates 31 and 32, the smaller the vibration, so that a small vibration can be supplied. In addition, by changing the frequency of the applied voltage, the speed at which the vibration transmitting body 12 moves circularly can be changed. What is necessary is just to change the magnitude | size of the piezoelectric plates 31 and 32, and the frequency of the voltage to apply, and to utilize according to various uses. Other configurations are the same as described above, and thus the description thereof is omitted.

(Embodiment 2)
In the first embodiment, the main shaft 11 is rotated to move the main shaft 11 back and forth. However, as shown in FIG. 12, vibration is supplied to the main shaft and the movable body attached to the main shaft is moved back and forth according to the load. You can also.

  One end of the main shaft 11 is connected to the support member 41, and the other end is connected to the support member 42. The main shaft 11 is fixed to the support members 41 and 42 so as not to rotate. A movable plate 44 is disposed on the main shaft 11.

  A motor 14 is attached to the support member 41, and a weight 15 is installed on the motor rotation shaft 16. When the motor 14 is driven, vibration is supplied by the weight 15 so that the main shaft 11 moves circularly.

  The movable plate 44 is slidably connected to a rail 43 disposed in parallel with the main shaft 11. As shown in FIG. 13, the movable plate 44 incorporates a movable body 47 in which the screw hole 13 is formed, such as a nut. The thread grooves formed in the movable body 47 have the same pitch as the thread pitch of the main shaft 11. The diameter of the thread of the main shaft 11 is larger than the diameter of the thread of the screw hole and smaller than the diameter of the thread groove of the screw hole. For this reason, the main shaft 11 is screwed in a state having a gap with respect to the screw hole 13, that is, in a state where it can be eccentric. A bearing 46 is disposed between the movable body 47 and the movable plate 44, and only the movable body 47 is configured to be able to rotate.

  When the motor 14 is driven, the main shaft 11 moves circularly due to vibration, so that the movable body 47 rotates. As a result, the movable body 47 moves in the direction of the main shaft 11, so that the movable plate 44 moves along the rail 43 together with the movement of the movable body 47. Since other configurations and operations are the same as described above, the description thereof is omitted.

(Embodiment 3)
In the first and second embodiments, a vibration generator such as a motor or a piezoelectric element is attached and direct vibration is supplied. However, the main shaft and the like are moved back and forth at a speed corresponding to the load by supplying vibration indirectly. You can also. One example thereof will be described with reference to FIG.

  A disc-shaped vibration transmission body 12 is arranged inside the cylindrical cylinder 51. The vibration transmission body 12 is fixed to the cylinder body 51. The vibration transmitting body 12 is provided with a screw hole 13, and the main shaft 11 formed with a screw thread is screwed into the screw hole 13 so as to be eccentric.

  When vibration is supplied to the cylindrical body 51, the cylindrical body 51 and the built-in vibration transmission body 12 are fixed, so that the vibration is transmitted to the vibration transmission body 12. When the vibration transmission body 12 receives vibration that can make a circular motion, the main shaft 11 rotates and moves back and forth at a speed corresponding to the load. For example, it can be used by supplying vibration by sandwiching it with a tool that can be sandwiched with a vibration generator such as a motor.

  In the third embodiment, the example using the circular cylindrical body 51 has been described. However, a polygonal cylindrical body may be used. Further, the cylinder body 51 is not necessarily provided. If the vibration transmitting body 12 is in an exposed state, vibration can be directly supplied by contacting an instrument or the like with a vibration generator attached thereto. Other configurations, operations, and the like are the same as described above, and thus description thereof is omitted.

  Then, the specific example which applied the above-mentioned load sensitive type continuously variable transmission mechanism is demonstrated.

(Embodiment 4)
15 to 18 are examples in which the above-described load-sensitive continuously variable transmission mechanism is applied to a robot hand. An arm 64 is connected to the base 65, and a vibration generator housing portion 63 is connected to an end of the arm 64. The vibration generator housing portion 63 is provided with a motor (not shown) or the like.

  The fixed gripper 61 is connected to the vibration generator housing portion 63. A movable gripper 62 is slidably disposed on the fixed gripper 61. As shown in FIG. 15, the fixed gripper 61 is provided with a screw hole 13, and one end of the main shaft 11 is screwed into the screw hole 13 so as to be eccentric. On the other hand, the other end of the main shaft 11 is connected to the movable gripper 62 so that it can rotate. When the main shaft 11 moves in the axial direction, the movable gripper 62 follows and moves, and the fixed gripper 61 and the movable gripper 62 hold the object.

  The fixed gripper 61 acts as the vibration transmission body described above. When vibration is supplied from a vibration generator (not shown), the main shaft 11 moves as shown in FIG. Since the movable gripper 62 moves as the main shaft 11 moves, the object can be gripped. If the motor or the like is rotated in the reverse direction, the movable gripper 62 moves in the reverse direction along with the movement of the main shaft 11, and the object can be released.

  As described above, when the load is not applied, that is, when the object is not gripped, the eccentric amount between the screw hole 13 and the main shaft 11 is large. For this reason, since the rotation speed of the main shaft 11 is fast, the movable gripper 62 can be moved in a short time. On the other hand, when a load is applied, that is, when the object is gripped, the moving speed of the movable gripper 62 becomes slow.

  The conventional robot hand is controlled at a constant speed in consideration of the maximum load, so the speed is limited even in a no-load state, and the work takes a long time. In the robot hand of the fourth embodiment, the movable gripper 62 can be driven at a high speed when there is no load, so that a robot hand with high work efficiency can be realized.

  Furthermore, the vibration generator housing part 63 and the fixed gripper 61 can be detachable rather than fixed. FIG. 17 is a detachable type by fitting and coupling, in which a convex portion 67 is formed in the fixed gripper 61, while a corresponding concave portion 66 is formed in the vibration generator housing portion 63. FIG. 18 is a detachable type using a magnetic force in which magnets 68 and 69 are installed in the fixed gripper 61 and the vibration generating device housing 63, respectively. There is an advantage that different grippers and the like can be used by appropriately replacing them.

  Since the mechanism can operate the movable gripper 62 if vibration can be supplied to the fixed gripper 61, it is not necessary to arrange wiring or the like in the fixed gripper 61 and the movable gripper 62. Since wiring or the like is unnecessary, even when used in a liquid, since a failure due to a short circuit does not occur, durability is high.

  In the fourth embodiment, the case where the main shaft 11 rotates is described. However, as described in the second embodiment, a movable body is built in the fixed gripper 61, and the main shaft 11 is moved by rotating the movable body. Also good.

(Embodiment 5)
FIG. 19 shows an example in which a load-sensitive continuously variable transmission mechanism is applied to an arm portion of a prosthetic hand. A load-sensitive continuously variable transmission mechanism similar to that of the first embodiment is included in a case 83 or the like, and the upper arm portion 82 and the forearm portion 81 are connected. The main shaft 11 and the forearm 81 are connected via a wire 85 or the like. The case 83 and the upper arm portion 82 are connected via a wire 84 or the like.

  As described in the first embodiment, by driving the motor 14, the main shaft 11 moves back and forth. As a result, the forearm 81 moves up and down as indicated by the arrows with the elbow joint as a fulcrum.

  In a state where no load is applied, that is, in a state where nothing is held in the hand, the eccentric amount of the main shaft 11 is large, so that the rotational speed is fast, and the linear motion of the main shaft 11 is quickly performed. On the other hand, when the load is large, such as holding something in the hand, the amount of eccentricity of the main shaft 11 becomes small, so the rotation speed becomes slow. Thereby, there is no unnatural movement at a constant speed, and a natural movement according to the load is possible.

(Embodiment 6)
Embodiment 6 is an example applied to the finger of a prosthetic hand. As shown in FIG. 20, it has four main shafts 11a, 11b, 11c, and 11d, and one vibration transmitting body 12. The main shafts 11a, 11b, 11c, and 11d are connected to corresponding fingers 91a, 91b, 91c, and 91d through wires 92, respectively.

  A motor 14 is installed in the vibration transmitting body 12, and the main shafts 11a, 11b, 11c, and 11d are moved back and forth by the vibration from the motor 14 as described above. The fingers 91a, 91b, 91c, 91d are gripped or opened by the longitudinal movement of the main shafts 11a, 11b, 11c, 11d.

  As shown in FIG. 21, when gripping a bottle 93 with a non-constant diameter, if all fingers 91a, 91b, 91c, 91d are driven at a constant speed, the force is concentrated on the finger that hits the largest diameter part of the bottle 93. I can't hold it well. In the sixth embodiment, the fingers 91a, 91b, 91c, and 91d move independently with speed and force according to their loads. For this reason, even when the bottle 93 having a non-constant diameter is gripped, the forces applied to the fingers 91a, 91b, 91c, 91d are averaged and can be gripped well. Such a so-called familiar mechanism can be effectively applied.

(Embodiment 7)
This is an example applied to an end effector for excising a tumor or the like used in a medical field. FIG. 22 shows the structure of the end effector 101. A hole 103 is provided on one bottom surface of the hollow cylindrical body 102. A vibration transmitting body 12 is fixed inside the cylindrical body 102. The vibration transmitting body 12 is formed with a threaded hole, and the main shaft 11 is screwed into the threaded hole with a gap. A single filament 104 formed by bending in a substantially rhombus shape passes through the hole 103 and is coupled to the tip of the main shaft 11. The filament 104 is made of a high-strength metal or resin.

  When the main shaft 11 moves inward of the cylinder 102 as indicated by an arrow in FIG. 22B (to the right in the drawing), the filament 104 becomes a cylinder as shown in FIG. 22C. 102 is a structure that is pulled inward.

  Since the end effector 101 is not directly attached with a vibration generating device, as shown in FIG. 23, the end effector 101 is used with a forceps 105 provided with the vibration generating device. The forceps 105 is provided with a vibration generating device accommodating portion 108, in which a vibration generating device such as a motor (not shown) is accommodated. The grip 110 is provided with a switch 109 that drives the vibration generator.

  By operating the grips 110 and 111 and sandwiching the end effector 101, the switch 109 is turned on to drive a vibration generator such as a motor. The generated vibration is transmitted through the pipe 107 and the grip 106 and supplied to the end effector 101.

  FIG. 24 shows how the end effector 101 is used to remove an organ tumor. The end effector 101 is inserted from a port in which the body skin is incised or from a hole communicating with the body such as the mouth. As shown in FIG. 24A, the operation is performed so that the tumor 113 to be extracted enters the diamond 104 of the filament 104. When the switch 109 is turned on after the position is determined, the main shaft 11 moves inward of the cylindrical body 102 by the vibration transmitted to the vibration transmitting body 12. As the main shaft 11 moves, the filament 104 passes through the hole 103 and is drawn into the cylinder 102 as shown in FIG. As the line 104 passes through the hole 103, the gap between the rhombus portions of the line 104 is narrowed, so that the tumor 113 can be removed.

  The filament 104 of the end effector 101 can be applied to various forms. For example, as shown in FIG. 25, the end effector 114 can be changed to a gripping portion 115 at a tip portion of a so-called forceps. When the vibration is supplied, the spindle 11 moves inward (on the right side in the drawing) of the cylindrical body 102 as shown by an arrow in FIG.

  In addition, as shown in FIG. 26, the gripper 115 may be an end effector 116 provided at both ends of the cylindrical body 102. When the vibration is supplied, each main shaft 11 moves inward of the cylindrical body 102 as indicated by an arrow in FIG. 26A, and each gripping portion 115 is closed.

  FIG. 27 schematically shows how the end effectors 114 and 116 are used. It can be effectively used to secure an operation space by temporarily fixing the organ 112, body skin, etc. in a narrow body cavity.

  In addition, it can also be applied to end effectors such as forceps, staplers and retractors.

  Conventionally, only the end effector portion cannot be separated and driven. For this reason, application in NOTES (Natural Office Transluminal Endoscopic Surgical) is difficult. NOTES is a method in which a surgical instrument is inserted into a hole that is open in a natural state such as the mouth, anus, or vagina without incising the body skin. In this case, access to the affected area and directions in which surgery is possible are limited. In addition, it is difficult to secure a space for surgery (a space for operating instruments).

  However, in the end effector of the present embodiment, as long as vibration is transmitted, only the end effector part can be separated and driven, so that it is impossible to access the affected part with conventional medical instruments or to secure a surgical space. There is an advantage that it can be easily performed even when it cannot be performed easily.

  In addition to the medical instrument, as shown in FIG. 28, an end effector 117 that can pick up a small object such as a screw can be configured. Three curved filaments 115 are coupled to the main shaft 11 through the holes 103. The tips of the respective filaments 115 are spaced apart at a predetermined pitch, but as described above, the main shaft 11 moves as indicated by the arrow in FIG. Be drawn into. Thereby, since the front-end | tip of each filament 115 adjoins, a target object can be grasped.

  Objects that are narrow and cannot be reached, especially objects that are bent and cannot be reached by a straight instrument, can be easily picked up.

  Using the apparatus shown in FIG. 29, it was verified whether or not the rotational speed of the main shaft changed according to the load. A hook 122 was attached to the tip of the main shaft 11, and weights 124 of various weights were hung on the hook 122 via a string 123. Then, the weight 124 was lifted by a certain distance, the time required for lifting was measured, and the average speed was calculated.

  A stainless steel M4 mesh is used as the main shaft 11, and the maximum eccentricity e of the main shaft 11 is about 0.04 mm. The hook 122 and the main shaft 11 are connected via a bearing (not shown) so that the hook 122 does not rotate.

  A weight 15 was attached to the motor rotating shaft 16 to give vibration to cause the vibration transmitting body 12 to move circularly. The rotational speed of the motor 14 is about 20000 rpm.

  The measurement mark 121 was installed in the middle part of the main shaft 11, and this was monitored with a laser displacement meter, and the time for which the measurement mark 121 passed was measured. A weight 124 was attached to the hook 122 at intervals of 0.5 kg from 0 g to 5 kg, and measurement was performed.

  The results are shown in FIG. It can be seen that when the load is small, the weight is pulled up at a high speed, and as the load increases, the pulling speed becomes slower. When the load is 0 kg and 5.0 kg, the current value of the motor 14 is about 3.3 A, and the rotational speeds of the motors are all equal. Therefore, the vibration that causes the vibration transmitting body 12 to move circularly is constant.

  From this, when the load is small, the eccentric amount e of the main shaft 11 is large, so the rotational speed of the main shaft 11 is large. On the other hand, as the load increases, the eccentric amount e of the main shaft 11 decreases and the rotational speed of the main shaft 11 increases. It was confirmed that it became smaller.

  As described above, the load-sensitive continuously variable transmission mechanism can move the main shaft or the movable body at a rotational speed corresponding to the load by supplying vibration. It can be configured to be small and lightweight with a simple structure, and can be expected to be used in various fields such as industrial robots and medical robots.

1 is a perspective view showing a schematic configuration of a load-sensitive continuously variable transmission mechanism according to Embodiment 1. FIG. 1 is a cross-sectional view illustrating a schematic configuration of a load-sensitive continuously variable transmission mechanism according to a first embodiment. It is a figure which shows the relationship between the main axis | shaft of the load-sensitive continuously variable transmission mechanism which concerns on Embodiment 1, and the diameter of the screw hole of a vibration transmission body. 1 is a perspective view showing a schematic configuration of a load-sensitive continuously variable transmission mechanism according to Embodiment 1. FIG. It is a figure which shows the principle of the load sensitive type continuously variable transmission mechanism which concerns on embodiment. (A)-(C) are figures which show the principle of the load sensitive type continuously variable transmission mechanism which concerns on embodiment of this invention. It is a figure which shows the principle of the load sensitive type continuously variable transmission mechanism which concerns on Embodiment 1. FIG. It is a figure which shows the principle of the load sensitive type continuously variable transmission mechanism which concerns on Embodiment 1. FIG. It is a figure which shows the principle of the load sensitive type continuously variable transmission mechanism which concerns on Embodiment 1. FIG. 1 is a perspective view showing a schematic configuration of a load-sensitive continuously variable transmission mechanism according to Embodiment 1. FIG. It is a figure which shows the principle of the load sensitive type continuously variable transmission mechanism which concerns on Embodiment 1. FIG. FIG. 6 is a perspective view showing a schematic configuration of a load-sensitive continuously variable transmission mechanism according to a second embodiment. FIG. 6 is a cross-sectional view showing a schematic configuration of a load-sensitive continuously variable transmission mechanism according to a second embodiment. FIG. 6 is a partially exploded perspective view showing a schematic configuration of a load-sensitive continuously variable transmission mechanism according to a third embodiment. It is a perspective view which shows schematic structure of the robot hand which concerns on Embodiment 4. FIG. It is a top view which shows the drive condition of the robot hand which concerns on Embodiment 4. FIG. It is a top view which shows the attachment or detachment structure of the robot hand which concerns on Embodiment 4. It is a top view which shows the attachment or detachment structure of the robot hand which concerns on Embodiment 4. 10 is a plan view showing a structure of a prosthetic hand according to Embodiment 5. FIG. 10 is a perspective view showing a structure of a prosthetic hand according to Embodiment 6. FIG. It is a perspective view which shows the operation | movement condition of the prosthetic hand which concerns on Embodiment 6. FIG. (A) is a perspective view of the end effector based on Embodiment 7, (B) and (C) are sectional drawings. It is a figure which shows the use condition of the end effector which concerns on Embodiment 7. FIG. (A) And (B) is a figure which shows the use condition of the end effector which concerns on Embodiment 7. FIG. (A) And (B) is sectional drawing which shows the structure of the end effector which concerns on Embodiment 7. FIG. (A) And (B) is sectional drawing which shows the structure of the end effector which concerns on Embodiment 7. FIG. It is a figure which shows the use condition of the end effector which concerns on Embodiment 7. FIG. (A) is a perspective view of an end effector according to the seventh embodiment, and (B) and (C) are sectional views. It is a side view which shows schematic structure of the apparatus used in the Example. It is a figure which shows the measurement result of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Main axis | shaft 12 Vibration transmission body 13 Screw hole 14 Motor 15 Weight 16 Motor rotating shaft 17 Vibration absorption member 21 Male screw 22 Female screw 31 Piezoelectric plate 32 Piezoelectric plate 33 Support part 41 Support member 42 Support member 43 Rail 44 Movable plate 45 Through-hole 46 Bearing 47 Movable body 51 Cylindrical body 61 Fixed gripper 62 Movable gripper 63 Vibration generating device accommodating portion 64 Arm 65 Base 66 Recessed portion 67 Protruding portion 68 Magnet 69 Magnet 81 Forearm portion 82 Upper arm portion 83 Case 84 Wire 85 Wire 91 Finger portion 92 Wire 93 bottle 101 end effector 102 cylinder 103 hole 104 filament 105 forceps 106 gripping part 107 pipe 108 vibration generator housing part 109 switch 110 grip 111 grip 112 organ 113 tumor 114 end effector 115 filament 116 End effector 117 End effector 121 Measurement mark 122 Hook 123 String 124 Weight

Claims (7)

A main shaft having a helical thread of a predetermined pitch;
A vibration transmission body having a screw hole in which a helical thread groove having the same pitch as the screw thread is formed, and receiving vibration from a vibration generator;
The diameter of the thread of the main shaft is configured to be smaller than the diameter of the thread groove,
The main shaft is screwed in an eccentric manner with a gap in the screw hole,
Circularly moving the vibration transmitting body by vibrations supplied directly or indirectly from the vibration generator;
Rotating the main shaft at a rotation speed according to a load applied to the main shaft, and linearly moving in an axial direction by screwing the screw thread and the screw groove;
A load-sensitive continuously variable transmission mechanism. A main shaft having a helical thread with a predetermined pitch and receiving vibration from the vibration generator;
A movable body having a screw hole in which a spiral thread groove having the same pitch as the thread of the main shaft is formed,
The diameter of the thread is configured to be smaller than the diameter of the thread groove of the screw hole,
The main shaft is screwed in an eccentric manner with a gap in the screw hole,
Circular movement of the main shaft by vibration supplied directly or indirectly from the vibration generator;
Rotating the movable body at a rotation speed according to a load applied to the movable body, and linearly moving in an axial direction of the main shaft by screwing the screw thread and the screw groove;
A load-sensitive continuously variable transmission mechanism.   3. The load-sensitive continuously variable transmission mechanism according to claim 1, further comprising a vibration generator that supplies vibration directly or indirectly to the vibration transmission body or the main shaft.   4. The load-sensitive continuously variable transmission mechanism according to claim 3, wherein the vibration generating device is a motor.   The load-sensitive continuously variable transmission mechanism according to claim 4, wherein a weight is installed on the shaft of the motor.   4. The load-sensitive continuously variable transmission mechanism according to claim 3, wherein the vibration generating device is a piezoelectric element.   A first piezoelectric plate and a second piezoelectric plate each composed of the piezoelectric element are arranged in parallel with the main axis, and the first piezoelectric plate is centered on the main axis with respect to the second piezoelectric plate. The load-sensitive continuously variable transmission mechanism according to claim 6, wherein the load-sensitive continuously variable transmission mechanism is positioned substantially vertically.

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