JP2005114016A - Actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a long stroke, while simplifying structure. <P>SOLUTION: Three ball screws 2, 3 and 4 are arranged on the same shaft. A shaft 32(42) of one ball screw 3(4) of adjacent ball screws 2 and 3(3 and 4) is provided with a hollow part 32a (42a) capable of housing a shaft 22(32) of the other ball screw 2(3) like an insert die. An end of the shaft 32(42) of the one ball screw 3(4) and a nut 21(31) of the other ball screw 2(3) are fixed to each other, and each of the three ball screws 2, 3 and 4 is provided with a bush 12 and a damper 13 for stopping rotation in the condition wherein the shaft 22(32)is housed in the hollow part 32a(42a) to continuously extend and shrink and in the condition wherein the shaft 22(32) is extended from the hollow part 32a(42a). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an actuator suitable for moving an article for a relatively long distance, for example.

  Conventional actuators such as those described above include ball screws, double-acting hydraulic cylinders, telescopic hydraulic cylinders, etc., as well as combinations of these. Ball screws have a shaft and nut relative to each other. And the shaft or nut is operated.

On the other hand, double-acting hydraulic cylinders allow the piston rods to expand and contract by switching the direction of pressure oil through the oil flow holes provided at both ends, and telescopic hydraulic cylinders are nested. A plurality of fitted cylinders are sequentially extended by hydraulic pressure.
JP-A-8-159382

  However, in the conventional actuator described above, the ball screw has a problem that, as is apparent from the above description, a stroke longer than the length of the shaft, that is, a stroke longer than the length of the ball screw itself cannot be produced. This was also the case with a double-acting hydraulic cylinder that could produce a stroke only by the length of the piston rod.

  In addition, the combination of a ball screw and a hydraulic cylinder has a problem that the structure cannot be denied even if a stroke longer than its own length can be produced. It has been a conventional problem to be solved.

  The present invention has been made paying attention to the above-described conventional problems, and has an object to provide an actuator capable of achieving a much longer stroke than the conventional one while realizing a simplified structure. It is said.

  The actuator according to claim 1 of the present invention includes a plurality of ball screws arranged coaxially, and the shaft of one of the ball screws adjacent to each other can be accommodated in a nested manner. The end of the shaft of one ball screw and the nut of the other ball screw are fixed, and the plurality of ball screws have a shaft in the hollow portion in order to perform expansion and contraction of each ball screw. And a stopper for stopping rotation in a state where the shaft is extended from the hollow portion, and the configuration of this actuator is a means for solving the above-described conventional problems. It is said.

  In the actuator according to claim 2 of the present invention, the plurality of ball screws are provided with restraining means capable of adjusting the order of extension and storage of the respective shafts.

  According to a third aspect of the present invention, there is provided an actuator according to a third aspect of the present invention, wherein the shaft and the nut are integrated until the torque value transmitted from the shaft screwed with the nut exceeds a predetermined value. By using the plunger that releases the nut from the shaft as a restraining means when the transmitted torque value exceeds a predetermined value, the order of extension and storage of the shafts of the plurality of ball screws can be adjusted, and the present invention According to the fourth aspect of the present invention, the stopper for stopping the rotation in a state where the shaft is housed in the hollow portion has a function of preventing the collision between the nuts.

  In the actuator of the present invention, the ball screw located closest to the drive source connection side among the plurality of ball screws is supported by a bearing and then connected to a drive source such as a motor. In addition, the ball screw located at a position farthest from the drive source among the plurality of ball screws is connected to an article to be moved directly or via a connecting member while restricting rotation.

  In this case, it is desirable to provide an auxiliary roller or the like for each ball screw in order to smoothly move the nut of the ball screw located at a position farthest from the drive source among the plurality of ball screws. In order to obtain a long stroke, it is desirable to employ a support means that can allow deformation of the actuator. Moreover, in order to perform expansion / contraction of each of the plurality of ball screws, stoppers for stopping the rotation are provided at both ends of movement (extension / contraction) of each of the plurality of ball screws.

  Since the actuator of the present invention has the above-described configuration, it is possible to obtain a very excellent effect that it is possible to obtain a very long stroke as compared with the prior art while avoiding the complicated structure.

  In the actuators according to the first and second aspects of the present invention, for example, when the ball screw located closest to the drive source connected to the drive source rotates, the ball screw and the ball screw located farthest from the drive source One of the ball screw shafts moves between and the number of rotations multiplied by the lead of the screw. That is, a long stroke can be obtained without complicating the structure.

  At this time, for example, by extending from the shaft of the thickest ball screw at the time of extension by using a stopper or restraining means, and adjusting it so as to be pulled in from the shaft of the thinnest ball screw at the time of storage, high-speed expansion and contraction is possible. .

  Since the actuator according to claim 3 of the present invention has the above-described configuration, the structure can be further simplified.

  Hereinafter, the present invention will be described with reference to the drawings.

  1 and 2 show an embodiment of an actuator according to the present invention. As shown in FIG. 1, this actuator 1 has a plurality (three) of ball screws 2, 3, and 4 arranged coaxially. The configuration is made.

  A hollow portion in which a shaft 22 of the ball screw 2 can be accommodated in a nut 21 of a ball screw 2 (the other ball screw) 2 positioned on the right side of the ball screws 2 and 3 adjacent to each other on the right side of FIG. The shaft 32 of the ball screw (one ball screw) 3 located on the left side having 32a is fixed by the set screw 10, and in the same manner, of the ball screws 3 and 4 adjacent to each other in the center of FIG. The shaft 42 of the left ball screw 4 having a hollow portion 42a capable of accommodating the shaft 32 of the ball screw 3 in a nested manner is also fixed to the nut 31 of the ball screw 3 positioned on the right side by the set screw 10.

  An outer cylinder 5 having a hollow portion 5a capable of receiving a shaft 42 of the ball screw 4 in a nested manner is fixed to the nut 41 of the ball screw 4 located on the left side of FIG. The shaft 22 of the ball screw 2 located on the right side is fixed to a pedestal of a drive unit (not shown) via a bearing 6 that rotatably supports the ball screw 2 so as to prevent it from coming off, and is connected to a drive source such as a motor. On the other hand, the outer cylinder 5 is connected to an article (not shown) to be moved via a spherical bearing 7 or directly.

  In this case, each nut 21, 21, 41 of the three ball screws 2, 3, 4 has a plunger 8 as a restraining means capable of adjusting the order of extension and storage of the shafts 22, 32, 42. It is provided. The plunger 8 integrates the shafts 22, 32, 42 and the nuts 21, 31, 41 until the torque values transmitted from the shafts 22, 32, 42 screwed with the nuts 21, 31, 41 respectively exceed a predetermined value. The nuts 21, 31, 41 are released from the shafts 22, 32, 42 when the torque value transmitted from the shafts 22, 32, 42 exceeds a predetermined value.

  In this embodiment, the plungers are sequentially fed out from the shaft 42 of the ball screw 4 located at the position farthest from the drive source during extension, and sequentially pulled from the shaft 22 of the ball screw 2 located closest to the drive source connection side during storage. The pressing force of 8 is adjusted. At this time, the support 9 of the bearing 6 fixed to the base of the drive unit (not shown) and the nut 21 of the ball screw 2 located on the right side are provided with locking grooves 9a and 21a with the plunger 8, The nuts 31 and 41 of the ball screws 3 and 4 are respectively provided with pads 11 that come into contact with the shafts 32 and 42 so as to generate a predetermined frictional force. The locking grooves 9a and 21a and the pads 11 The shafts 22, 32, 42 are surely brought out and drawn in in order.

  In addition, the code | symbol 12 in FIG. 1 is a bush which functions as a stopper which makes rotation of the shaft 22,32,42 smooth, and stops rotation in the state which extended the shaft22,32,42, Reference numeral 13 in FIG. 1 denotes a damper made of urethane rubber that functions as a stopper for stopping rotation in a state in which the shafts 22, 32, and 42 are housed, and that serves to avoid collision between the nuts 21, 31, and 41. is there.

  In this actuator 1, in the state shown in FIG. 2 (a), the ball screw 2, with respect to the locking grooves 9 a and 21 a provided in the nut 21 of the ball screw 2 connected to the support 9 of the bearing 6 and the drive source, 3, when the shaft 22 of the ball screw 2 is rotated, this rotation is transmitted to the shaft 42 of the ball screw 4 located at a position farthest from the drive source, Therefore, the nut 41 of the ball screw 4 moves in the feeding direction together with the outer cylinder 5.

  Next, when the nut 41 of the ball screw 4 reaches the end of the shaft 42, that is, when the shaft 42 of the ball screw 4 is fully extended, the plunger 8 of the ball screw 3 is detached from the locking groove 21 a of the nut 21 of the ball screw 2. Therefore, the nut 31 of the ball screw 3 moves together with the ball screw 4 in the feeding direction.

  Subsequently, in the same manner as described above, when the nut 31 of the ball screw 3 reaches the end of the shaft 32, that is, when the shaft 32 of the ball screw 3 is fully extended, the plunger 8 of the ball screw 2 is engaged with the support 9. Since the nut 21 of the ball screw 2 moves in the feeding direction together with the ball screws 3 and 4 because the nut 21 of the ball screw 2 moves out of the stop groove 9a, and the nut 21 of the ball screw 2 reaches the end of the shaft 22, that is, When the shaft 22 is fully extended, a long stroke is obtained as shown in FIG.

  During this time, the bushes 12 provided on the ball screws 2, 3 and 4 function, respectively, to make the operation of the shafts 22, 32 and 42 smooth, while the shafts 22, 32 and 42 are fully extended. Stop rotation.

  Further, in the state shown in FIG. 2B, the pads 11 and 11 provided on the nuts 31 and 41 are brought into contact with the shafts 32 and 42 of the ball screws 3 and 4 so that a predetermined frictional force is generated. Therefore, when the shaft 22 of the ball screw 2 is rotated, the nut 21 of the ball screw 2 in which no frictional force is generated between the nut 21 and the shaft 22 moves together with the ball screws 3 and 4 in the pull-in direction. Become.

  Next, when the nut 21 of the ball screw 2 reaches the support 9, that is, when the shaft 22 of the ball screw 2 is accommodated in the shaft 32, the nut 31 of the ball screw 3 resists the frictional force by the pad 11. When the nut 31 of the ball screw 3 reaches the nut 21 of the ball screw 2, that is, when the shaft 32 of the ball screw 3 is accommodated in the shaft 42, the rotation starts and moves in the drawing direction together with the ball screw 4. Like the nut 31, the nut 41 of the ball screw 4 starts to rotate against the frictional force of the pad 11 and moves in the retracting direction together with the outer cylinder 5, and the nut 41 of the ball screw 4 is moved to the nut 31 of the ball screw 3. 2, that is, when the shaft 42 of the ball screw 4 is accommodated in the outer cylinder 5, the state before the stroke shown in FIG. The Rukoto.

  During this time, the dampers 13 provided on the ball screws 2, 3, 4 function to stop the rotation reliably in the state where the shafts 22, 32, 42 are housed, and the nuts 21, 31, 41, that is, Prevent metal parts from colliding with each other.

  As described above, with this actuator 1, a much longer stroke can be obtained without complicating the structure. In addition, at the time of extension, the shaft 42 of the ball screw 4 located at the most distant portion from the drive source. Are sequentially drawn out and retracted from the shaft 22 of the ball screw 2 located closest to the drive source coupling side, so that high-speed expansion and contraction is possible.

In the actuator of the present invention, the stroke can be made much longer than before while simplifying the structure, so that it is required to be easy to handle and used in a spacecraft subject to severe restrictions on storage space. Very suitable.
The detailed configuration of the actuator of the present invention is not limited to the above-described embodiments.

It is side explanatory drawing which showed the actuator by one Example of this invention in the cross section partially. (Example 1) It is side surface explanatory drawing (a) of the state which contracted the actuator in FIG. 1, and side surface explanatory drawing (b) of the state which extended the actuator.

Explanation of symbols

1 Actuator 2, 3, 4 Ball screw 8 Plunger (restraint)
12 Bush (stopper)
13 Damper (stopper)
21, 31, 41 Nut 22, 32, 42 Shaft 32a, 42a Hollow part

Claims (4)

  Provided with a plurality of ball screws arranged coaxially, one of the ball screws adjacent to each other is provided with a hollow portion that can accommodate the shaft of the other ball screw in a nested manner, and one ball The end of the shaft of the screw and the nut of the other ball screw are fixed, and the plurality of ball screws are housed in the hollow portion so as to perform expansion and contraction of each of the ball screws and the shaft from the hollow portion. An actuator, characterized in that a stopper is provided to stop the rotation in a state where each is extended.   The actuator according to claim 1, wherein the plurality of ball screws are provided with restraining means capable of adjusting an order of extension and storage of each shaft.   The shaft and the nut are integrated until the torque value transmitted from the shaft screwed with the nut exceeds a predetermined value, and the torque value transmitted from the shaft exceeds the predetermined value. 3. The actuator according to claim 2, wherein a plunger that releases the nut from the shaft at the stage is used as a restraining means.   The actuator according to any one of claims 1 to 3, wherein a stopper that stops rotation in a state where the shaft is housed in the hollow portion has a function of preventing collision between nuts.

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