JP4678723B2 - Actuator - Google Patents

Description

  The present invention generally relates to an actuator capable of low-speed rotation using a pair of oblique bevel gears, and more particularly to an actuator using an elastic film member as an input portion.

2. Description of the Related Art Conventionally, an actuator that uses a pair of oblique bevel gears, rotates stepwise in synchronism with fluid pressure such as air, and has a built-in speed reducer and can achieve ultra-low speed rotation (for example, patents). Reference 1).
An actuator using an elastic membrane member for an input portion and a cylindrical internal gear is known (see, for example, Patent Documents 2 and 3).

  Further, the present applicant has developed an actuator using a pair of oblique bevel gears that use an elastic film member for the input portion and are relatively rotatable and have different numbers of teeth, as shown in FIGS. The basic structure of the actuator has been announced to academic societies (for example, see Non-Patent Document 1). The prior art of FIGS. 8-14 is demonstrated below. 8 to 10, reference numeral 2 denotes a casing, to which the support portion 4 a of the first oblique bevel gear 4 and each outer peripheral surface of the columnar support 6 are fixed, and the first oblique umbrella A shaft-shaped output member 8 is rotatably supported on the bearing portion of the gear 4.

The structure in which the support portion 4a of the first oblique bevel gear 4 is fixed to the casing 2 constitutes rotation prevention means. An elastic membrane member 10 made of silicon rubber, an elastomer or other similar effect material is engaged and fixed to a partitioning portion 6a on one side of the support 6 and is supported by the elastic membrane member 10. Four fluid chambers 12 are formed on one end surface of the body 6 with an interval of approximately 90 degrees in the circumferential direction. The elastic membrane member 10 is pressure-bonded to a locking groove 14 formed in the support 6, and the periphery of each fluid chamber 12 is firmly sealed by the elastic membrane member 10.

A lid 15 is bonded to the other end of the support 6, and a fluid passage 16 is formed in the lid 15 and the support 6 for each fluid chamber 12. The fluid passage 16 is connected to fluid pressure drive control means (not shown) for supplying a pressure fluid such as an air pulse to the fluid chambers 12 in order. Reference numeral 18 denotes a second oblique bevel gear, teeth 18b are formed on the support portion 18a, and the pressure receiving surface 18c of the support portion 18a faces the surface of the elastic membrane member 10. A bevel gear 20 for transmitting rotational force is integrally formed inside the support portion 18 a of the second oblique bevel gear 18, and the bevel gear 20 is fixed to the output member 8. The number of teeth of the bevel gear 20 and the number of teeth of the bevel gear 24 are the same.

Further, a second portion of the support portion 18a of the second oblique bevel gear 18 has a second central portion on the side opposite to the pressure receiving surface 18c, due to the interaction with the ball 8a at the rear end of the output member 8. A hemispherical concave spherical bearing 22 is integrally formed to support the oblique bevel gear 18 so as to freely swing around (branch motion). The teeth 4b of the first oblique bevel gear 4 and the teeth 18b of the second oblique bevel gear 18 are different in number of teeth, and the teeth 18b of the second oblique bevel gear 18 are It faces the teeth 4b of the oblique bevel gear 4 and meshes with part of the circumference. A flange portion formed integrally with the output member 8 is disposed in contact with an inner end face of the support portion 4 a of the first oblique bevel gear 4 via a thrust bearing 26. The apex of the surface constituting the conical angle of each oblique bevel gear 4, 18, the apex of the surface constituting the conical angle of each bevel gear 20, 24, and the spherical center of the spherical bearing 22, that is, the second oblique intersection. The center of the whirling movement of the bevel gear 18 coincides with the center.

In the above-described configuration, when the fluid pressure drive control means operates in a preset sequence, fluid pulses such as air pulses are sequentially supplied to each fluid chamber 12. The fluid chamber 12 swells when pressurized with fluid, and as shown in FIG. 8 at this swelled portion, the eccentric portion of the circular pressure receiving surface 18c of the second oblique bevel gear 18 is axially, that is, The second oblique bevel gear 18 is pressurized in a direction approaching the first oblique bevel gear 4, and the second oblique bevel gear 18 is inclined with the ball body 8a as a fulcrum, A part of the tooth 18b meshes deeply with the tooth 4b of the first oblique bevel gear 4. The second oblique bevel gear 18 is always sequentially pressed by the four fluid chambers 12 so that it always meshes with the first oblique bevel gear 4 in a part of its circumferential direction. However, the rotation of the first oblique bevel gear 4 is fixed to the casing 2 to prevent its rotation, and the number of teeth of the teeth 4b of the first oblique bevel gear 4 Since the number of teeth 18b of the second oblique bevel gear 18 is different from that of the second oblique bevel gear 18, the second oblique bevel gear 18 rotates by its swinging motion.

The rotation motion of the second oblique bevel gear 18 is transmitted to the output member 8 through the rotational force transmitting means including the bevel gears 20 and 24 having the same number of teeth, and the output member 8 rotates. In the actuator shown in FIG. 11, a frictional force reducing member 28 made of a thrust bearing or other equivalent material is interposed between the elastic membrane member 10 and the second oblique bevel gear 18. In FIG. 11, the frictional force reducing member 28 is attached to a convex portion 30 protruding from the center of the support portion 18 a of the second oblique bevel gear 18. 11 is the same as that of the actuator shown in FIG.
Next, an actuator in which the pressing position on the oblique bevel gear is in the vicinity of the outer peripheral portion of the pressure receiving surface will be described with reference to FIGS.

Reference numeral 32 denotes a piston in which a pressing rod 32 a and a guide shaft 32 b are integrally formed. The piston 32 is arranged for each fluid chamber 12, and a guide plate 34 in which the guide shaft 32 b and the pressing rod 32 a are fixed to the casing 2. A corresponding guide hole is inserted and slidable in the axial direction. The pressing rods 32a of the pistons 32 are arranged at intervals of 90 degrees in the circumferential direction, and face the vicinity of the outer periphery of the pressure receiving surface 18c of the second oblique bevel gear 18, respectively. The other configuration is the same as that of the actuator shown in FIG.

In the configuration described above, when one of the fluid chambers 12 expands, the piston 32 facing it is pressed by the surface of the expanded fluid chamber 12, the piston 32 moves in the axial direction, and the pressing rod 32a is The outer periphery of the pressure receiving surface 18c of the oblique bevel gear 18 is pushed in the axial direction. As this movement is performed sequentially, the second oblique bevel gear 18 swings around (brute movement).
FIG. 14 shows an actuator using a universal joint as a rotational force transmitting means.
In FIG. 14, 58 is a cross shaft of the universal joint, and a shaft portion 58a in one direction is rotatably engaged with bearing portions 60 and 62 formed on the support portion 18a of the second oblique bevel gear 18. The other right-angled shaft portion 58 b is rotatably engaged with bearing portions 64 and 66 formed on the flange portion of the output member 8. The other configuration is the same as that of the actuator shown in FIG.
JP 2002-317858 A JP-A-10-78010 Japanese Patent Laid-Open No. 11-93612 Proceedings of the 4th Machine Lubrication Design Division Lecture Meeting

The actuators using the elastic membrane member for the input part and the cylindrical internal gear shown in Patent Documents 2 and 3 press the outer peripheral part of the internal gear in the direction approaching the external gear by the elastic film member. is doing. Therefore, in order to apply this pressing force to the internal gear, there is a problem that depends only on the pressing area.
An actuator using a conventional pair of oblique bevel gears and using an elastic membrane member for the input portion is arranged in the thrust direction with the pressure receiving surface of the oblique bevel gear facing the elastic membrane member as a plane, and the pressure receiving surface The fluid pressure acts in the thrust direction (direction parallel to the output member). Therefore, the fluid pressure does not efficiently act on the pressure receiving surface of the oblique bevel gear, and a large force cannot be applied to the pressure receiving surface. Then, if a large force is to be applied to the pressure receiving surface, the diameter of the oblique bevel gear facing the elastic membrane member is increased and the outer edge of the pressure receiving surface away from the center of the oblique bevel gear is pressed, The area of the elastic membrane member that is in contact with the oblique bevel gear must be increased and pressed against the oblique bevel gear with a large area. In any of these methods, the oblique bevel gear and the elastic membrane member become large in the radial direction, and there is a problem that the apparatus becomes large. The present invention aims to solve the above problems.

In order to achieve the above object, the present invention provides a pair of oblique bevel gears that are relatively rotatable and have different numbers of teeth, and one of the pair of oblique bevel gears can swing around the other. Supporting means for supporting, pressing force applying means provided at three or more locations on the support for swinging the one oblique bevel gear, and rotation of any one of the pair of oblique bevel gears. An anti-rotation means for preventing rotation, an output member rotatably supported, and a rotation transmission means for transmitting only the rotational force of the oblique bevel gear on the side without the anti-rotation means to the output member. An elastic film member attached to the support; and an elastic film member formed such that a vertex of a surface constituting a conical angle of the bevel gear coincides with a center of the whirling motion. At least part of which is sealed around the support An actuator comprising three or more fluid chambers, a passage for feeding fluid into each fluid chamber, and fluid pressure drive control means for sequentially supplying fluid to each fluid chamber, facing the elastic membrane member A radial pressure receiving surface is provided on the side of the oblique bevel gear, and the fluid is disposed in a direction having an angle with respect to a direction in which the oblique bevel gear contacts and separates from the other oblique bevel gear. The pressing force is applied.
Further, the present invention provides a direction substantially parallel to a direction in which the oblique bevel gear contacts and separates from the other oblique bevel gear on the oblique bevel gear side facing the elastic film member in addition to the radial pressure receiving surface. A thrust pressure receiving surface for receiving a pressing force of the fluid, and a direction in which the pressing force of the fluid presses against the other oblique bevel gear with respect to the oblique bevel gear opposed to the elastic membrane member, and an angle with respect to the direction It is intended to act in both directions having
In the present invention, of the pair of oblique bevel gears, the oblique bevel gear on the side pressed by the pressing force applying means rotates.
In the present invention, a frictional force reducing member is interposed between the elastic film member and a pressure receiving surface in contact therewith.

  In the present invention, the oblique bevel gear can be pressed by the fluid pressure by effectively utilizing this principle, and the pressure receiving area can be increased, so that the output torque can be increased without enlarging the radial direction of the apparatus. Large actuators can be provided.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
1 and 2 show a first embodiment of the present invention. Reference numeral 2 denotes a casing, to which the outer peripheral surface of the support portion 4a of the first oblique bevel gear 4 and the cylindrical support body 6 is fixed, and the shaft is attached to the bearing portion of the first oblique bevel gear 4 A shaped output member 8 is rotatably supported. The structure in which the support portion 4a of the first oblique bevel gear 4 is fixed to the casing 2 constitutes rotation prevention means.

A shaft hole 36 is formed in the center of the columnar support 6. An elastic membrane member 10 made of rubber, elastomer, or other similar material is engaged and fixed to the support 6, and four chambers are sealed around the peripheral surface of the shaft hole 36 of the support 6 with the elastic membrane member 10. As shown in FIG. 2, the fluid chambers 12 are formed at intervals of approximately 90 degrees in the circumferential direction. A pressure receiving shaft 38 protrudes in the axial direction at the center of the back surface of the support portion 18a of the second oblique bevel gear 18, and a wheel 40 is rotatably supported by the pressure receiving shaft 38.

The outer peripheral surface of the wheel 40 forms a gentle conical surface, and the outer peripheral surface pushes fluid in a direction having an angle with respect to the direction in which the oblique bevel gear contacts and separates from the other oblique bevel gear. It constitutes a radial pressure receiving surface on which pressure acts. The outer peripheral surface of the wheel 40 is loosely fitted in the shaft hole 36 of the support 6. Reference numeral 42 denotes a partition plate supported by the casing 2. A hole is formed in the central portion, and the side surface locks the side surface of the elastic membrane member 10. The elastic membrane member 10 is pressed into a locking groove formed in the support 6, and the periphery of each fluid chamber 12 is firmly sealed by the elastic membrane member 10.

The present invention is not limited to the elastic membrane member 10 constituting a seal, and the fluid chamber 12 is constituted by a member partially constituting the elastic membrane member 10, and the portion other than the elastic membrane of this member The structure which seals may be sufficient. A lid 15 is bonded to the other end of the support 6, and a fluid passage 16 is formed in each of the fluid chambers 12 in the lid 15 and the support 6. is doing. The fluid passage 16 is connected to fluid pressure drive control means (not shown) for supplying a pressure fluid such as an air pulse to the fluid chambers 12 in order.

Teeth 18 b are formed on the support portion 18 a of the second oblique bevel gear 18. A bevel gear 20 for transmitting rotational force is integrally formed inside the support portion 18 a of the second oblique bevel gear 18, and the bevel gear 20 is fixed to the output member 8. The number of teeth of the bevel gear 20 and the number of teeth of the bevel gear 24 are the same.

Further, a second portion of the support portion 18a of the second oblique bevel gear 18 has a second central portion on the surface opposite to the pressure receiving shaft 38 due to the interaction with the ball body 8a at the rear end of the output member 8. A hemispherical concave spherical bearing 22 is integrally formed to support the oblique bevel gear 18 so as to freely swing around (branch motion). A hemispherical ball body 8 a formed at the rear end of the output member 8 is fitted to the spherical bearing 22, and the second oblique bevel gear 18 is formed by the ball body 8 a and the spherical bearing 22. The support means for supporting the swaying movement freely is configured.

The teeth 4b of the first oblique bevel gear 4 and the teeth 18b of the second oblique bevel gear 18 are different in number of teeth, and the teeth 18b of the second oblique bevel gear 18 are It faces the teeth 4b of the oblique bevel gear 4 and meshes with part of the circumference. The teeth 4b and 18b of the first and second oblique bevel gears 4 and 18 are arranged facing each other at positions where the teeth 4b and 18b do not mesh in the neutral state where the fluid chamber 12 is not expanded. However, it may be in a slightly engaged state in the neutral state.

A flange portion formed integrally with the output member 8 is disposed in contact with an inner end face of the support portion 4 a of the first oblique bevel gear 4 via a thrust bearing 26. In the first embodiment shown in FIG. 1, the apex of the surface constituting the cone angle of each of the oblique bevel gears 4 and 18, the apex of the surface constituting the cone angle of each of the bevel gears 20 and 24, and the spherical bearing The center of 22 spheres, that is, the center of the whirling movement of the second oblique bevel gear 18 coincides.

In the above-described configuration, when the fluid pressure drive control means operates in a preset sequence, fluid pulses such as air pulses are sequentially supplied to each fluid chamber 12.
Each fluid chamber 12 swells in a direction perpendicular to the axial direction in the shaft hole 36 when a pressure fluid such as an air pulse is sequentially supplied, and a radial pressure receiving surface formed by the outer peripheral surface of the wheel 40 is used as a lever. To press more efficiently. Thereby, a pressing force acts on the second oblique bevel gear 18 in a direction perpendicular to the axial direction. With this pressing force, the second oblique bevel gear 18 has the ball body 8a as a fulcrum. It inclines, and a part of its teeth 18b meshes deeply with the teeth 4b of the first oblique bevel gear 4.

The second oblique bevel gear 18 is always sequentially pressed by the four fluid chambers 12 so that it always meshes with the first oblique bevel gear 4 in a part of its circumferential direction. However, the rotation of the first oblique bevel gear 4 is fixed to the casing 2 to prevent its rotation, and the number of teeth of the teeth 4b of the first oblique bevel gear 4 Since the number of teeth 18b of the second oblique bevel gear 18 is different from that of the second oblique bevel gear 18, the second oblique bevel gear 18 rotates by its swinging motion.

The rotation motion of the second oblique bevel gear 18 is transmitted to the output member 8 through the rotational force transmitting means including the bevel gears 20 and 24 having the same number of teeth, and the output member 8 rotates. In the present embodiment, the second oblique bevel gear 18 on the side pressed by the fluid of the pair of oblique bevel gears 4 and 18 is configured to rotate. On the other hand, the side pressed by the pressing force applying means can be the non-rotating side. In this case, the other first oblique bevel gear 4 side is rotatable with respect to the casing 2. In order to prevent the second oblique bevel gear 18 from rotating, it is necessary to provide a rotation preventing means.

The rotation preventing means is configured by providing a rotation preventing projection on the outer periphery of the oblique bevel gear and fitting the projection into a rotation preventing groove formed in the casing. Therefore, since the structure of the projections and grooves is formed in the outer circumferential direction of the oblique bevel gear, it must be large. Of the pair of oblique bevel gears, the above-described increase in size can be prevented and the size can be reduced as a whole by adopting a configuration in which the side pressed by the pressing force applying means rotates. However, the present invention is not particularly limited to this configuration, and any of the pair of oblique bevel gears 4 and 18 may be on the fixed side.

  In the first embodiment, the wheel 40 is rotatably supported on the pressure receiving surface 38 of the second oblique bevel gear 18, and the outer peripheral surface forms a radial pressure receiving surface. However, even if it comes into contact with the surface of one swelled fluid chamber 12, the wheel 40 does not slide and rotate with the surface of one swelled fluid chamber 12, and a frictional force is generated between them. There is no. However, when one of the fluid chambers 12 swells and thereby presses the wheel 40, there is a slight shift in the contact between the surface of the elastic membrane member and the wheel 40. A frictional force is generated between the two oblique bevel gears 18. For this reason, the elastic membrane member 10 is worn out and consumed, resulting in poor durability, and the rotational torque transmission efficiency between the second oblique bevel gear 18 and the output member 8 is deteriorated.

In that case, grease or oil is interposed between the elastic membrane member 10 and the radial pressure receiving surface on the second oblique bevel gear 18 side, or the surface of the radial pressure receiving surface is coated with a low friction coefficient material, for example, DLC coating, coating of solid lubricant containing PTFE, or surface treatment such as nickel-based electroless plating, or coating of the elastic film member 10 with a material having a low friction coefficient, for example, fluorine rubber coating Etc. can be improved. This countermeasure is effective for all the embodiments described later.

  3 and 4 show a second embodiment of the present invention, in which a support body 6 is fixed to a lid body 15 fixed to the casing 2, and the support body 6 spans its outer peripheral portion and end face. Four fluid chambers 12 are formed by the elastic membrane member 10. Each fluid chamber 12 has a passage 16 to which a pressure fluid is supplied. When one of the fluid chambers 12 is inflated by the supplied pressurized fluid, the applied pressure is perpendicular to the inner diameter surface 44 of the recessed portion formed in the support portion of the second oblique bevel gear 18 and perpendicular to the axial direction. It acts on the thrust pressure receiving surface 46.

As a result, the second oblique bevel gear 18 receives a pressing force from the surface of the swelled fluid chamber 12 in the direction perpendicular to the axial direction by this principle, and the axial pressure on the thrust pressure receiving surface 46. Receive at the same time. The inner surface 44 of the recessed portion formed in the support portion of the second oblique bevel gear 18 has an angle with respect to the direction in which the oblique bevel gear 18 contacts and separates from the other oblique bevel gear 4. A radial pressure receiving surface that receives the pressing force of the fluid in the direction is configured. Other configurations are the same as those of the first embodiment shown in FIG.

  5 and 6 show a third embodiment of the present invention, in which a tubular body 48 is integrally fixed at the center of the second oblique bevel gear 18, and the second oblique bevel gear 18. A shaft portion 50a of the rotating body 50 is rotatably inserted into a portion protruding in the axial direction from the back surface of the rotating body 50. A spherical bearing 22 is formed at one center of the tubular body 48. On one side of the support 6 fixed to the casing 2, a bowl-shaped recessed portion 52 is formed, and four chambers extending over the inner peripheral surface of the cylindrical portion of the recessed portion 52 and the curved bottom surface portion 54, A fluid chamber 12 having an interval of 90 degrees in the circumferential direction is formed by the elastic membrane member 10.

Each fluid chamber 12 has a passage 16 to which a pressure fluid is supplied. Reference numeral 56 denotes a partition plate supported by the casing 2. The outer peripheral surface 50 b of the rotating body 50 constitutes a radial pressure receiving surface that receives a pressing force of fluid in a direction having an angle with respect to a direction in which the oblique bevel gear 18 contacts and separates from the other oblique bevel gear 4. ing. Other configurations of the present embodiment are the same as those of the first embodiment shown in FIG.

  In the above-described configuration, when one of the fluid chambers 12 expands under the control of the pressure fluid drive control means, the applied pressure is applied to the radial pressure receiving surface formed by the bowl-shaped outer peripheral surface 50b of the rotating body 50. Thus, the second bevel gear 18 acts in the direction in which the oblique bevel gear 18 is inclined efficiently and acts on the thrust pressure receiving surface formed by the bottom surface portion 50c. (Inclination direction) and two axial directions approaching the first oblique bevel gear 4 simultaneously. When the second oblique bevel gear 18 receives a pressing force in a direction approaching the first oblique bevel gear 4, the spherical bearing 22 of the second oblique bevel gear 18 is connected to the output member 8. The effect of preventing separation from the ball body 8a and stabilizing the meshing also occurs. In this embodiment, one of the pair of oblique bevel gears facing each other receives pressure in both the tilt direction and the axial direction due to the pressure of the fluid chamber, so that one of the second oblique bevel gears 18 is The nutation movement with respect to the other first oblique bevel gear 4 is performed reliably.

In the above-described embodiments, the rotational force transmitting means for transmitting the rotation of the second oblique bevel gear 18 to the output member 8 is constituted by the bevel gears 20 and 24, which are particularly limited to this configuration. It is possible to use various rotational force transmitting means as long as the second bevel gear 18 is allowed to be moved in the nutation. Further, the fluid chamber is not particularly limited to four chambers, and may be three or more chambers.
FIG. 7 shows another embodiment of the rotational force transmitting means.

  In FIG. 7, 58 is a cross shaft of a universal joint, and a shaft portion 58a in one direction is rotatably engaged with bearing portions 60 and 62 formed on the support portion 18a of the second oblique bevel gear 18. The other right-angled shaft portion 58 b is rotatably engaged with bearing portions 64 and 66 formed on the flange portion of the output member 8. The rotational force transmitting means using the universal joint shown in FIG. 7 can be used in the first to third embodiments. Also in this embodiment using this universal joint, the apex of the surface constituting the cone angle of each oblique bevel gear 4, 18 is the center of the swinging motion of the second oblique bevel gear 18 with the universal joint as a fulcrum. Match.

  In the above embodiment, each radial pressure receiving surface is configured to receive a fluid pressing force in a direction having an angle of approximately 90 degrees in the axial direction, but the present invention is particularly limited to an angle of approximately 90 degrees. Instead, the radial pressure receiving surface may be configured so that the oblique bevel gear receives the pressing force of the fluid in a direction having an angle with respect to the axial direction by the lever principle, and does not need to be substantially 90 degrees. For example, when the angle is about 45 degrees, the pressing force of the fluid in the direction of about 45 degrees is the component force that presses the oblique bevel gear 18 in the direction of about 90 degrees with respect to the axial direction by the lever principle. And the oblique bevel gear 18 acting as a combined force with a component force that presses the oblique bevel gear 18 toward the oblique bevel gear 4 in a direction substantially parallel to the axial direction. It acts on the gear 18.

It is sectional drawing which shows the 1st Embodiment of this invention. It is CC sectional view taken on the line of FIG. It is sectional drawing which shows the 2nd Embodiment of this invention. It is the DD sectional view taken on the line of FIG. It is sectional drawing which shows the 3rd Embodiment of this invention. It is the EE sectional view taken on the line of FIG. It is a disassembled perspective view of a rotational force transmission means. It is sectional drawing of a prior art. It is the sectional view on the AA line of FIG. It is a disassembled perspective view of the fluid chamber which shows a prior art. It is sectional drawing of a prior art. It is sectional drawing of a prior art. It is the BB sectional view taken on the line of FIG. It is sectional drawing of a prior art.

Explanation of symbols

2 Casing 4 First oblique bevel gear 6 Support body 8 Output member 10 Elastic film member 12 Fluid chamber 14 Locking groove 15 Lid 16 Fluid passage 18 Second oblique bevel gear 20 Bevel gear 22 Spherical bearing 24 Bevel gear 26 Thrust bearing 28 Friction force reducing member 30 Protruding portion 32 Piston 34 Guide plate 36 Shaft hole 38 Pressure receiving shaft 40 Wheel 42 Partition plate 44 Inner surface 46 Pressure receiving surface 48 Tubular body 50 Rotating body 52 Recessed portion 54 Bottom surface portion 56 Partition plate 58 Cross Shaft 60 Bearing portion 62 Bearing portion

Claims (4)

A pair of oblique bevel gears that are relatively rotatable and have different numbers of teeth; a support means that supports one of the pair of oblique bevel gears so as to swing freely relative to the other; and the one oblique intersection A pressing force applying means provided at three or more locations on the support for swinging the bevel gear, a rotation preventing means for preventing the rotation of one of the pair of oblique bevel gears, and a rotatably supported And a rotation transmitting means for transmitting only the rotational force of the oblique bevel gear on the side without the rotation preventing means to the output member, and the surface constituting the cone angle of each oblique bevel gear An apex is formed so as to coincide with the center of the whirling motion, and the pressing force applying means includes an elastic membrane member attached to the support, and at least part of the elastic membrane member and the periphery is sealed and the support Three or more fluid chambers formed in the body, In an actuator comprising a passage for feeding fluid into the fluid chamber and a fluid pressure drive control means for sequentially supplying fluid to each fluid chamber, a radial pressure receiving surface is provided on the oblique bevel gear side facing the elastic membrane member. And the pressing force of the fluid acts on the radial pressure receiving surface in a direction having an angle with respect to a direction in which the oblique bevel gear contacts and separates from the other oblique bevel gear. Actuator to do. In addition to the radial pressure receiving surface, on the side of the oblique bevel gear that faces the elastic membrane member, the oblique bevel gear receives a pressing force in a direction substantially parallel to the direction in which the oblique bevel gear contacts and separates from the other oblique bevel gear. A thrust pressure receiving surface is provided, and both the direction in which the pressing force of the fluid is pressed against the other bevel gear and the direction having an angle with respect to the other bevel gear are opposed to the elastic membrane member. The actuator according to claim 1, wherein the actuator acts on the actuator. 3. The actuator according to claim 1, wherein, among the pair of oblique bevel gears, an oblique bevel gear on a side pressed by the pressing force applying unit is configured to rotate. 4. The actuator according to any one of claims 1 to 3, wherein a frictional force reducing member is interposed between the elastic film member and a pressure receiving surface in contact with the elastic film member.

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