JP2011169349A - Actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lower-cost actuator having simple construction converting the rotary motion of a rotation driving source into the linear motions of rods. <P>SOLUTION: The electric actuator 11 includes a conversion mechanism for converting the rotary motion of a motor into the linear motions of the first and second rods 24, 26 supported on an actuator body 12 in a sinking/rising manner. The conversion mechanism has first and second coil springs 19, 22 rotated with the rotating force of the motor transmitted thereto, having elastic force, and externally mounted on the first and second rods 24, 26. The conversion mechanism also has a rotation preventing roller 29 protruded from the first and second rods 24, 26 to contact spiral wire rods 19a, 22a of the first and second coil springs 19, 22, and inserted into a guide groove 12a formed in the inner peripheral face of the actuator body 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an actuator including a conversion mechanism that converts a rotary motion of a rotary drive source into a linear motion of a rod supported so as to be able to appear and retract in an actuator body.

  2. Description of the Related Art Conventionally, for example, an electric actuator that causes a rod to protrude and retract from an actuator body by a driving force of a motor is disclosed in Patent Document 1, for example. As shown in FIG. 6, a rod 82 is provided in the actuator body 81 of the electric actuator 80, and a small diameter compression coil spring 83 is inserted into the rod 82. A rotating shaft 84a of a motor 84 is connected to the small diameter compression coil spring 83. A large-diameter compression coil spring 85 is inserted outside the small-diameter compression coil spring 83, and the outer periphery of the large-diameter compression coil spring 85 is fixed to the inner peripheral surface of the rod 82.

  A retainer 86 is accommodated inside the small diameter compression coil spring 83 so as to be movable in the axial direction of the small diameter compression coil spring 83. The retainer 86 is formed of a retainer main body 86a and a regulation pin 86b protruding from the outer peripheral surfaces of both ends along the radial direction of the small diameter compression coil spring 83. The restricting pin 86 b is located in the space 87 between the small diameter compression coil spring 83 and the large diameter compression coil spring 85. A plurality of rolling balls 88 that are in contact with the spiral wires 83 a and 85 a of both compression coil springs 83 and 85 are interposed in the space 87. These rolling balls 88 are spirally arranged along the two spiral wires 83a and 85a, and are held by the restricting pins 86b so as not to be dispersed.

  An annular piston 90 is fixed to the inner end of the rod 82, and the piston 90 is supported by the actuator body 81. A guide bar 89 extending in the axial direction of the actuator body 81 is penetrated through the outer edge of the piston 90, and both ends of the guide bar 89 are fixed to the actuator body 81. The piston 90 and the guide rod 89 prevent the small diameter compression coil spring 83 and the large diameter compression coil spring 85 from rotating together to prevent the large diameter compression coil spring 85 from rotating.

  Then, according to the electric actuator 80, when the motor 84 rotates, the rotational motion is transmitted to the small diameter compression coil spring 83 via the rotation shaft 84a, and the small diameter compression coil spring 83 rotates. Then, along with the rotation of the small diameter compression coil spring 83, the retainer 86 moves in the axial direction of the small diameter compression coil spring 83 while rotating, and the large diameter compression coil spring 85 moves linearly without rotating. As a result, the rod 82 fixed to the large diameter compression coil spring 85 moves linearly.

  In the electric actuator 80, when the tip of the rod 82 hits the object, the movement of the rod 82 is restricted. At this time, the small diameter compression coil spring 83 and the large diameter compression coil spring 85 are compressed and elastically deformed, and the elastic force accumulated in both the compression coil springs 83 and 83 presses the rod 82 against the object after the motor 84 is stopped. The necessary thrust is ensured.

Japanese Patent Laid-Open No. 2004-217725

  However, the electric actuator 80 of Patent Document 1 includes a small-diameter compression coil spring 83, a large-diameter compression coil spring 85, a retainer 86, and a plurality of rolling balls 88 in order to convert the rotational motion of the motor 84 into the linear motion of the rod 82. This requires a conversion mechanism, which complicates the structure of the conversion mechanism and increases the cost. Furthermore, in order to convert the rotational motion of the motor 84 into the linear motion of the rod 82, in addition to the conversion mechanism, the piston 90 and the guide rod 89 are required as a detent mechanism, and the internal structure of the electric actuator 80 is complicated. At the same time, the cost increased.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to convert the rotational motion of the rotary drive source into the linear motion of the rod with a simple configuration, thereby reducing the cost. It is to provide an actuator that can be used.

  In order to solve the above problems, an invention according to claim 1 is an actuator provided with a conversion mechanism for converting the rotational motion of the rotational drive source into the linear motion of a rod supported so as to be able to appear and retract in the actuator body. The conversion mechanism is rotated by receiving the rotational force of the rotational drive source and has an elastic force, and protrudes from the rod so as to be in contact with the coil spring sheathed on the rod and the helical wire of the coil spring. In addition, the gist of the present invention is that it comprises a detent portion inserted into a guide groove formed in the inner peripheral surface of the actuator body.

  According to a second aspect of the present invention, in the actuator according to the first aspect, the detent portion includes a support shaft projecting from the rod, and is rotatably supported by the support shaft so as to contact the spiral wire. A rotating first rotating body, and a second rotating body that is rotatably supported by the support shaft and rotates in contact with the guide groove and can rotate independently of the first rotating body. This is the gist.

  A third aspect of the present invention is the actuator according to the first or second aspect, wherein the rod is a first rod and is movable in the axial direction of the first rod with respect to the first rod. And a second coil member inserted into the first rod, a hand member is integrated at the tips of the first and second rods, and a first coil spring sheathed on the first rod, and the second rod The second coil spring is mounted on the rod, and the winding directions of the spiral wire rods of the first coil spring and the second coil spring are reversed.

  According to the present invention, the rotational motion of the rotational drive source can be converted into the linear motion of the rod with a simple configuration, and the cost can be reduced.

Sectional drawing which shows the electric actuator arrange | positioned in a clamp position. The perspective view which shows the electric actuator of 1st Embodiment. FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2 showing the electric actuator of the first embodiment. Sectional drawing which shows the electric actuator arrange | positioned in an unclamp position. Sectional drawing which shows the electric actuator of 2nd Embodiment. Sectional drawing which shows the electric actuator of background art.

(First embodiment)
A first embodiment in which the actuator of the present invention is embodied as an electric actuator will be described below with reference to FIGS.

  As shown in FIG. 1, the electric actuator 11 includes a cylindrical actuator body 12 having openings on both sides, and both ends of the actuator body 12 are closed by covers 13a and 13b. As shown in FIG. 2, a motor 14 as a rotational drive source is fixed on the outer surface of the central portion in the axial direction of the actuator body 12. As shown in FIG. 1, the drive shaft 14a driven by the motor 14 is composed of a worm gear. The drive shaft 14 a passes through the actuator body 12 and is drawn into the actuator body 12.

  A worm wheel 15 is rotatably supported by the actuator main body 12 via a bearing 16 at the axial central portion in the actuator main body 12. The worm wheel 15 is meshed with the drive shaft 14a. The worm wheel 15 is rotated by the rotation of the drive shaft 14a.

  A first rotating member 17 is rotatably supported by the actuator body 12 via a bearing 18 at one end portion in the axial direction in the actuator body 12. One end of the first coil spring 19 is fixed to one end of the worm wheel 15 in the axial direction, and the other end of the first coil spring 19 is fixed to the first rotating member 17. A second rotating member 20 is rotatably supported by the actuator body 12 via a bearing 21 at the other axial end of the actuator body 12. One end of the second coil spring 22 is fixed to the other end portion of the worm wheel 15 in the axial direction, and the other end of the second coil spring 22 is fixed to the second rotating member 20. The first and second coil springs 19 and 22 are formed at an equal pitch.

  The spiral wire 19a of the first coil spring 19 and the spiral wire 22a of the second coil spring 22 are a direction in which the spiral of the spiral wire 19a extends (winding direction), and a direction in which the spiral of the spiral wire 22a extends (winding direction). Is reversed. When the drive shaft 14a is rotated by the motor 14 and the worm wheel 15 is rotated, the first coil spring 19 and the second coil spring 22 are rotated simultaneously.

  In the actuator body 12, a first rod 24 is provided that extends along the axial direction and has a cylindrical shape whose outer end opening is closed by a cap 23a. A first hand member Ha is fixed to the cap 23a. The first rod 24 is slidably supported by a cover 13a that closes one end opening of the actuator body 12 through a sliding bearing 25a. Further, one end of the first rod 24 is inserted into the first rotating member 17 and the other end is inserted into the worm wheel 15.

  In the actuator body 12, a second rod 26 is provided that extends along the axial direction and has a cylindrical shape whose outer end opening is closed by a cap 23b. A second hand member Hb is fixed to the cap 23b. The second rod 26 is slidably supported by a cover 13b that closes the other end opening of the actuator body 12 through a sliding bearing 25b. The second rod 26 has one end side inserted into the second rotating member 20 and the other end side inserted into the first rod 24.

  The inner diameter of the first rod 24 is formed larger than the outer diameter of the second rod 26. The first rod 24 is inserted with the inner end side of the second rod 26, and the first rod 24 and the second rod 26 are relatively movable in the axial direction of the rods 24, 26. It has become.

  Each of the first and second rods 24 and 26 has a pair of support shafts 27 protruding from the circumferential direction of the first and second rods 24 and 26 along the outer diameter direction. It is inserted between the pitches of the spiral wires 19a and 22a. A feed roller 28 as a first rotating body is rotatably supported on each support shaft 27. Further, on each support shaft 27, a rotation preventing portion and a rotation preventing roller 29 as a second rotating body are rotatably supported. The feed roller 28 and the non-rotating roller 29 are supported by the support shaft 27 so as to be rotatable independently of each other. In the pair of support shafts 27, a part of the peripheral surface of one feed roller 28 is always in contact with the spiral wire members 19a and 22a, and a part of the peripheral surface of the other feed roller 28 is always in contact with the spiral wire members 19a and 22a. It protrudes at the contact position. In other words, the pair of feed rollers 28 are always in contact with the positions (front and rear) between which the feed rollers 28 are sandwiched in the axial direction of the spiral wires 19a and 22a, and the shafts of the first and second coil springs 19 and 22 are brought into contact with each other. Movement in the direction is restricted.

  In addition, guide grooves 12 a are formed in the opposing positions on the inner surface of the actuator body 12 so as to extend linearly over the entire axial direction of the actuator body 12. In each guide groove 12a, an anti-rotation roller 29 is disposed, and the anti-rotation roller 29 rotates by contacting the inner surface of the guide groove 12a.

  The rotation prevention roller 29 rotates in the guide groove 12a, thereby preventing the first rod 24 and the second rod 26 from rotating together with the rotation of the first coil spring 19 and the second coil spring 22. It is like that. Thereby, the rotational motions of the first coil spring 19 and the second coil spring 22 are transmitted to the feed roller 28, and the feed roller 28 rotates. Then, the rotational motions of the first and second coil springs 19 and 22 are smoothly converted into linear motions of the first rod 24 and the second rod 26. In the present embodiment, a conversion mechanism that converts the rotational motion of the motor 14 into the linear motion of the first and second rods 24 and 26 from the first and second coil springs 19 and 22 and the anti-rotation roller 29 is configured. Has been.

  In the electric actuator 11, when the motor 14 is rotated in the forward direction, the first and second rods 24 and 26 are projected from the actuator body 12 as shown in FIG. It is arranged at an unclamping position for unclamping W. On the other hand, when the motor 14 is rotated in the reverse direction, the first and second rods 24 and 26 are immersed in the actuator body 12 as shown in FIG. .

  As shown in FIG. 1, when the motor 14 is driven in the forward direction with the first and second rods 24 and 26 being immersed, the worm wheel 15 rotates with the rotation of the drive shaft 14a. As the worm wheel 15 rotates, the first and second coil springs 19 and 22 rotate in the positive direction. Then, the first and second rods 24 and 26 are linearly moved along the axial direction of the first and second coil springs 19 and 22, and as shown in FIG. , 26 are arranged at the unclamping position.

  When the motor 14 is driven in the reverse direction with the first and second rods 24 and 26 protruding, the worm wheel 15 rotates with the rotation of the drive shaft 14a, and the worm wheel 15 rotates. Accordingly, the first and second coil springs 19 and 22 rotate in the opposite directions. Then, the first and second rods 24 and 26 are linearly moved along the axial direction of the first and second coil springs 19 and 22, and as shown in FIG. , 26 are arranged in the clamping position.

  Then, when the inner surfaces of the first and second hand members Ha and Hb abut against the object W, the movement of the first and second rods 24 and 26 is restricted. At this time, the first and second coil springs 19 and 22 are compressed by the pressure contact of the feed roller 28 and are elastically deformed together. When the spiral wire rods 19a and 22a of the first and second coil springs 19 and 22 are elastically deformed by the pressure contact of the feed roller 28, the spiral wire rods 19a and 22a to which the feed roller 28 is pressed are compared with those before the pressure contact with the feed roller 28. The inclination angle is not maintained (becomes smaller), and the component force becomes smaller. As a result, a clamp thrust is applied to the first and second rods 24 and 26. Since this component force is based on the spring constants of the first and second coil springs 19 and 22, a desired clamp thrust can be obtained by appropriately setting the spring constants of the first and second coil springs 19 and 22. be able to.

  The motor 14 continues to rotate until the clamping thrust applied to the first and second rods 24 and 26 reaches a necessary and sufficient value. When the necessary and sufficient clamping thrust is obtained, the motor 14 is energized. Blocked. Therefore, the first and second hand members Ha and Hb are pressed against the object W without providing a holding mechanism such as a motor brake separately from the electric actuator 11 in a state where the driving of the motor 14 is stopped. It is possible to keep the state as it is.

  Further, even when the energization to the motor 14 is interrupted, the motor 14 and the first and second coil springs 19 and 22 have inertia energy (inertial force). Therefore, although the movement of the first and second rods 24 and 26 is restricted, the motor 14 and the first and second coil springs 19 and 22 have a rotational force in the clamping direction. However, since the first and second coil springs 19 and 22 are elastically compressed, the inertia energy of the motor 14 and the first and second coil springs 19 and 22 is absorbed.

According to the above embodiment, the following effects can be obtained.
(1) The electric actuator 11 includes a conversion mechanism that converts the rotational motion of the motor 14 into linear motion of the first and second rods 24 and 26. And this conversion mechanism is applied to the first and second coil springs 19 and 22 that are sheathed by the first and second rods 24 and 26 and the spiral wire rods 19 a and 22 a of the first and second coil springs 19 and 22. The rods 24 and 26 protrude from the rods 24 and 26 so as to be in contact with each other, and are formed with a rotation prevention roller 29 inserted into the guide groove 12a of the actuator body 12. Therefore, the configuration of the conversion mechanism can be simplified as compared to the case where the conversion mechanism includes the small diameter compression coil spring 83, the large diameter compression coil spring 85, the retainer 86, and the plurality of rolling balls 88 as in the background art. In addition, the cost of the electric actuator 11 can be reduced.

  (2) The conversion mechanism of the electric actuator 11 protrudes from the first and second coil springs 19 and 22 and the first and second rods 24 and 26 and is inserted into the guide groove 12a of the actuator body 12. And a rotation prevention roller 29. And by this conversion mechanism, the rotational motion of the motor 14 can be converted into the linear motion of the first and second rods 24 and 26, and at the same time, the first and second rods 24 and 26 are prevented from rotating. be able to. Therefore, as compared with the case where the piston 90 and the guide rod 89 are required as a rotation preventing mechanism in addition to the conversion mechanism as in the background art, the internal structure of the electric actuator 11 is simplified and the cost of the electric actuator 11 is reduced. Can be achieved.

  (3) In the conversion mechanism of the electric actuator 11, the rotational motions of the first and second coil springs 19 and 22 are converted into linear motions of the first and second rods 24 and 26 through the rotation of the feed roller 28. . Therefore, the first and second coil springs 19 and 22 can be smoothly rotated, and the rotational motion of the first and second coil springs 19 and 22 is linearly moved by the first and second rods 24 and 26. Can be converted efficiently.

  (4) A support shaft 27 protrudes from a position facing the circumferential direction of the first and second rods 24, 26, and the peripheral surface of the feed roller 28 supported by one support shaft 27 is the first and second rods. The circumferential surfaces of the feed rollers 28 supported by the other support shaft 27 are always in contact with the spiral wire members 19a and 22a. For this reason, the pair of feed rollers 28 are in contact with the spiral wire members 19 a and 22 a at positions that are line-symmetric with respect to the axes of the first and second coil springs 19 and 22. Therefore, a load from the first and second coil springs 19 and 22 is applied to the pair of feed rollers 28 in a well-balanced manner, and the first and second rods 24 and 26 can be linearly moved in a stable state.

  (5) A support shaft 27 protrudes from a position facing the circumferential direction of the first and second rods 24, 26, and the peripheral surface of the feed roller 28 supported by one support shaft 27 is the first and second rods. The circumferential surfaces of the feed rollers 28 supported by the other support shaft 27 are always in contact with the spiral wire members 19a and 22a. That is, the feed roller 28 is always in contact with the positions (front and rear) between which the feed rollers 28 are sandwiched in the axial direction of the spiral wire rods 19a and 22a, and this contact causes the first and second coil springs 19 and 22 to move in the axial direction. Movement is regulated. For this reason, it can suppress that the 1st and 2nd coil springs 19 and 22 rattle with respect to the feed roller 28.

  (6) In order to prevent the first and second rods 24, 26 from rotating, the rotation-preventing roller 29 is rotatably supported by the support shaft 27 protruding from the first and second rods 24, 26. The anti-rotation roller 29 is disposed in the guide groove 12a formed in the actuator body. When the rotational motions of the first and second coil springs 19 and 22 are converted into linear motions of the first and second rods 24 and 26, the rotation prevention roller 29 rotates in the guide groove 12a. Therefore, the sliding resistance of the mechanism for preventing rotation can be reduced, and the first and second rods 24 and 26 can be moved smoothly.

  (7) The first and second rods 24 and 26 are inserted inside the first and second coil springs 19 and 22, and the feed roller 28 and the non-rotating roller are inserted into the first and second rods 24 and 26. The rotational motion of the motor 14 can be converted into the linear motion of the first and second rods 24 and 26 only by providing 29. Therefore, for example, the cost of the electric actuator can be reduced and the weight can be reduced as compared with the case where the member rotated by the motor 14 is formed by a ball screw or a sliding screw.

  (8) In the electric actuator 11, the rotational motion of the motor 14 is converted into the rotational motion of the first and second coil springs 19 and 22 via the drive shaft 14 a and the worm wheel 15. The first coil spring 19 and the second coil spring 22 are arranged on the same axis, but the spiral extending direction (winding direction) is reversed. For this reason, when the worm wheel 15 rotates, the first rod 24 and the second rod 26 that linearly move by the first coil spring 19 and the second coil spring 22 can approach or separate from each other. Therefore, according to the electric actuator 11, the object W can be clamped or unclamped by driving the motor 14 so that the first hand member Ha and the second hand member Hb approach or separate from each other.

(Second Embodiment)
Next, a second embodiment in which the actuator of the present invention is embodied as an electric actuator will be described with reference to FIG. In the following description, the same reference numerals are given to the same configurations as those of the already described embodiments, and the overlapping description is omitted or simplified.

  As shown in FIG. 5, the electric actuator 41 includes a cylindrical actuator body 42 having openings on both sides, and one end opening of the actuator body 42 is closed by a cover 43. A motor 44 as a rotational drive source is attached to the other end side of the actuator body 42. One end of a coil spring 46 is fixed to the drive shaft 44 a of the motor 44 via a connecting member 45, and the other end of the coil spring 46 is in contact with and supported by the inner end surface of the cover 43 via a slide bearing 53. .

  In the actuator main body 42, a cylindrical rod 48 is provided that extends along the axial direction and has an outer end opening closed by a cap 47. The rod 48 is slidably supported by the cover 43 of the actuator body 42 via a slide bearing 49. The rod 48 is inserted into the coil spring 46. The rod 48 is provided with a pair of support shafts 50 protruding from the position facing the circumferential direction of the rod 48 along the outer diameter direction. A feed roller 51 as a first rotating body and a rotation preventing roller 52 as a rotation preventing portion and a second rotating body are rotatably supported on each spindle 50. The feed roller 51 and the non-rotating roller 52 are supported by the support shaft 50 so as to be rotatable independently of each other. The pair of support shafts 50 are provided so that the rear end face of one feed roller 51 is always in contact with the spiral wire 46a of the coil spring 46, and the front end face of the other feed roller 51 is always in contact with the spiral wire 46a. ing.

  Further, on the inner surface of the actuator main body 42, guide grooves 42 a are formed at the opposing positions so as to extend linearly in the entire axial direction of the actuator main body 42. A detent roller 52 is disposed in each guide groove 42a.

  In the electric actuator 41 of the second embodiment, when the motor 44 is rotated in the forward direction, the rod 48 protrudes from the actuator body 42 and is disposed at a clamping position for clamping the object W. On the other hand, when the motor 44 is rotated in the reverse direction, the rod 48 is immersed in the actuator body 42 and is disposed at the unclamping position. Further, the sliding bearing 53 receives the load applied to the coil spring 46 and the rotation of the coil spring 46 via the feed roller 51 when the rod 48 protrudes from the actuator body 42.

Therefore, according to the second embodiment, the same effects as (1) to (7) described in the first embodiment can be obtained.
In addition, you may change the said embodiment as follows.

  In each embodiment, the anti-rotation portion may be formed of a resin convex portion that slides relative to the guide grooves 12a and 42a, instead of a rotating body such as the anti-rotation roller 29. Further, the feed roller 28 that rotates in contact with the coil springs 19, 22, 46 may be changed to resin.

In each embodiment, the pitch of each coil spring 19, 22, 46 may be changed to an unequal pitch.
In the first embodiment, when the motor 14 is rotated in the forward direction, the first and second rods 24 and 26 are projected from the actuator body 12, but the motor 14 is rotated in the forward direction. The first and second rods 24 and 26 may be immersed in the actuator body 12.

  In the second embodiment, when the motor 44 is rotated in the forward direction, the rod 48 is projected from the actuator body 42. However, when the motor 44 is rotated in the forward direction, the rod 48 is moved into the actuator body 42. You may be immersed.

The rotation drive source may be changed to an air motor, an internal combustion engine or the like in addition to the motors 14 and 44.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

(A) The actuator according to claim 2, wherein the first rotating body is always in contact with a position sandwiching the first rotating body in the axial direction of the spiral wire rod.
(B) A pair of the support shafts are provided at positions opposed to the circumferential direction of the rod, and the first rotating body supported by each support shaft is disposed at a position that is axisymmetric with respect to the axis of the coil spring. The actuator according to claim 2.

  Ha ... first hand member, Hb ... second hand member, 11, 41 ... electric actuator as actuator, 12, 42 ... actuator body, 12a, 42a ... guide groove, 14, 44 ... motor as rotational drive source , 19, 22, 46 ... coil springs, 19a, 22a, 46a ... spiral wire, 24 ... first rod, 26 ... second rod, 27, 50 ... support shaft, 28, 51 ... feed as first rotating body Roller, 29, 52... Anti-rotation part and anti-rotation roller as second rotating body, 48.

Claims (3)

An actuator having a conversion mechanism for converting the rotational motion of a rotational drive source into linear motion of a rod supported so as to be able to appear and retract in the actuator body,
A coil spring that is rotated by the rotational force of the rotational driving source being transmitted and having an elastic force and is sheathed on the rod;
An actuator comprising a rotation preventing portion that protrudes from the rod so as to be in contact with the helical wire of the coil spring and is inserted into a guide groove formed on an inner peripheral surface of the actuator body.   The rotation preventing portion includes a support shaft protruding from the rod, a first rotating body that is rotatably supported by the support shaft and rotates in contact with the spiral wire, and is rotatably supported by the support shaft. The actuator according to claim 1, wherein the actuator is configured to include a second rotating body that rotates in contact with the guide groove and that can rotate independently of the first rotating body.   The rod includes a first rod, and a second rod inserted in the first rod so as to be movable in the axial direction of the first rod. A hand member is integrated at the tip, and includes a first coil spring sheathed on the first rod and a second coil spring sheathed on the second rod, and the first coil spring and the second coil spring. The actuator according to claim 1, wherein the winding direction of the helical wire of the coil spring is reversed.

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