JP2006105186A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear actuator capable of performing highly accurate feed operation. <P>SOLUTION: In this linear actuator, a transmission means for transmitting the rotating force of a rotating means to a spindle is a drive shaft with one end connected and fixed to a rotating shaft of the rotating means through a connecting means and with the other end fixed in the rotating direction of a connection part and slidable in the axial direction of the connection part. The connecting means is composed of a first fixed part fixed to the rotating shaft; a second fixed part fixed to the one end of the drive shaft; and a position absorbing part located between the first fixed part and the second fixed part. The connection part of the drive shaft and spindle is connected by a connecting means fixed in the rotating direction and slidable in the axial direction, through a connecting ball. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a linear actuator used for an optical fiber alignment device, a manipulator used for gene, cell manipulation, and the like.

The linear actuator disclosed in Patent Literature 1 is screwed into the main body and is movable in the axial direction, displacement detection means for detecting the amount of displacement of the spindle, and one end of the spindle on the same axis as the spindle. A motor that is provided; and a transmission mechanism that transmits the rotational force of the motor to the spindle. The transmission mechanism is attached to one end of the spindle and rotates integrally with the spindle; and the rotation of the motor. The second rotating member and the spindle axis are parallel to the child and arranged on an axis different from the spindle axis, and fixed to either the first rotating member or the second rotating member. And a connecting rod that is slidably engaged with the other of the first rotating member and the second rotating member and transmits the rotation of the second rotating member to the first rotating member. What to have A.
JP 2003-166615 A

  In the conventional structure as described above, friction loss occurs when the connecting rod and the through-hole slide in the axial direction, so that it is difficult to reduce the size of the motor itself, and the friction between the connecting rod and the through-hole. In order to suppress loss and slide smoothly, it is necessary to provide a slight gap between the connecting rod and the through-hole, but this causes a backlash problem. For smooth sliding in the axial direction, it is necessary to maintain the parallelism in the axial direction of the connecting rod itself, but the two connecting rods have a cantilever structure. This makes it difficult to maintain a long stroke, resulting in problems such as difficulty in obtaining a long stroke.

  Accordingly, it is an object of the present invention to provide a linear actuator that can perform a highly accurate feeding operation.

  Therefore, this invention is provided on the other end side of the main body case having a hollow portion, a rotating means provided on one end side of the main body case and having a rotation shaft extending to the hollow portion, A female screw portion having a female screw formed on the inner peripheral surface, a spindle having a male screw threadedly engaged with the female screw portion formed on the outer peripheral surface and having a connecting portion extending to the hollow portion; and the rotating means In the linear actuator comprising at least a transmission means for operatively connecting the rotary shaft of the spindle and the connecting portion of the spindle and transmitting the rotational force of the rotary means to the spindle, the transmission means is connected to the rotary shaft. A driving shaft having one end connected and fixed via a connecting portion and the other end fixed in the rotation direction of the connecting portion and slidable in the axial direction of the connecting portion; A first fixing portion fixed to the rotating shaft, a second fixing portion fixed to one end of the drive shaft, and a position absorption located between the first fixing portion and the second fixing portion. Is composed of parts. The rotating means is preferably an electric motor, particularly a stepping motor.

  The connecting means is a metal cylindrical member including the first fixing portion, the position absorbing portion, and the second fixing portion, and the position absorbing portion is alternately arranged in a radial direction at a predetermined interval. It is desirable that a slit is formed.

  As described above, by providing the connecting means, the position absorbing portion of the connecting means can absorb the eccentricity / deflection angle between the drive shaft and the rotating shaft, so that the mounting work of the electric motor can be simplified. Become. Moreover, since the torsional rigidity is high, the occurrence of backlash in the rotational direction can be prevented.

  Further, the connecting portion of the spindle is formed in an axial direction, and includes a through hole into which the other end side of the drive shaft is slidably inserted, and at least one inner ball groove formed along the through hole. The drive shaft has at least one outer ball groove formed in an axial direction, and at least one connecting ball is interposed between the inner ball groove and the outer ball groove, It is desirable that the shaft and the connecting portion are fixed in the rotational direction and slidable in the axial direction. Furthermore, it is desirable that the connecting ball is held by a resin retainer.

  The connecting portion of the spindle has a through hole formed in the axial direction and a slide unit fixed to the through hole, and the drive shaft has a plurality of splines formed in the axial direction. The slide unit may have a circulation groove structure in which a plurality of balls can continuously mesh with the spline.

  As described above, since the spindle and the drive shaft are connected via the balls, the rotation direction and the slidability in the axial direction can be simultaneously achieved with a simple structure.

  Preferably, the main body case is provided with a limit sensor for detecting the shortest dead center point of the spindle and a limit sensor for detecting the shortest dead point point of the spindle. This can prevent the spindle from being locked.

  Furthermore, it is desirable that the other end of the rotating shaft of the motor extends outward, and a knob is provided at the tip of the extended portion. Accordingly, since the spindle can be manually operated, fine adjustment of the position of the spindle can be easily performed, and operability is improved.

  As described above, according to the present invention, the rotating shaft of the rotating means and the drive shaft are connected by the connecting means having the absorbing portion that absorbs the eccentricity and declination between them. The work can be simplified. In addition, the connection between the drive shaft and the spindle is fixed by a ball whose rotational direction is fixed and slidable in the axial direction, so that high precision can be achieved without considering the positional relationship and balance of multiple parts. The feed can be achieved, and a reduction in size and weight can be achieved.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, the linear actuator 1 according to the first embodiment of the present invention includes an electric motor 2 such as a stepping motor, a main body case 3 in which the electric motor 2 is arranged on one end side, and the main body case. 3 is provided with a spindle 5 extending from the other end side, and a drive shaft 8 for moving the spindle 5.

  The spindle 5 has a male screw portion 6 that is fixed to the other end side of the main body case 3 and meshes with a female screw cylinder 4 in which a female screw portion 7 is formed on the inner peripheral surface. The case 3 extends and contracts. Further, a connecting portion 51 of the spindle 5 is provided on the inner space 3 a side of the main body case 3, and a through hole 52 is formed in the connecting portion 51. The through hole 52 is formed with at least one inner ball groove 53 extending in the axial direction.

  A metal coupling 10 is provided at one end of the rotating shaft 9 of the electric motor 2 that extends toward the internal space 3a. The metal coupling 10 includes a shaft-side fixing portion 10a in which one end of the drive shaft 8 is fixed by a screw 71, a motor-side fixing portion 10b in which one end of the rotating shaft is fixed by a screw 72, and a front shaft-side fixing. It is a metal cylindrical member comprised by the position absorption part 10c located between the part 10a and the said motor side fixing | fixed part 10b. The position absorbing portion 10c is formed with a plurality of slits alternately cut at a predetermined depth in the radial direction so as to absorb the eccentricity / deflection angle between the rotating shaft 9 and the drive shaft 8. It has become.

  As shown in FIGS. 1 to 3, an outer ball groove 80 is formed along the axial direction on the other end side of the drive shaft 8, particularly the drive shaft 8, and is formed in the through hole 52 of the connecting portion 51. Inserted. Between the outer ball groove 80 of the drive shaft 8 inserted into the through hole 52 and the inner ball groove 53 formed in the through hole 52 of the connecting portion 51, at least one (in this embodiment 1). 3) connecting balls 30 are provided to connect the drive shaft 8 and the spindle 5 together. Further, the interval and position of the connecting ball 30 are held by a resin retainer. Therefore, the connection state between the drive shaft 8 and the spindle 5 is fixed in the rotation direction by the connection ball 30 and can slide in the axial direction.

  Thus, when the rotary shaft 9 of the electric motor 2 rotates, the rotational force is transmitted to the drive shaft 8 through the metal coupling 10, and further transmitted to the spindle 5 through the connecting ball 30, and the spindle 5 rotates. . By this rotation, the spindle 5 can be moved forward or backward by screwing with the female screw portion 7.

  Two limit sensors 20 and 21 are provided at predetermined positions of the main body case 3. The first limit sensor 20 is provided to prevent the spindle 5 from being locked at the longest dead center, and is a ball plunger pushed by the connecting portion 51 at a position before the longest dead center of the spindle 5. 22, the ball plunger 22 is pressed to detect that the spindle 5 is close to the longest dead center, and the drive of the electric motor 2 is stopped. The second limit sensor 21 is provided to prevent the spindle 5 from being locked at the shortest dead center, and is a ball plunger that is pushed by the connecting portion 51 at a position before the shortest dead center of the spindle 5. 23, and when the ball plunger 23 is pressed, it is detected that the spindle 5 is close to the shortest dead center, and the drive of the electric motor 2 is stopped. In addition, as long as this limit sensor can detect a position, such as a proximity sensor and a photoelectric sensor, its structure is not particularly limited. In FIGS. 1 and 2, reference numerals 24 and 25 denote signal cables for transmitting a limit sensor signal to the outside.

  Further, a knob 41 is provided on the other end side of the rotating shaft 9 of the electric motor 2 so that the rotating shaft 9 can be manually rotated. Thereby, the position of the spindle 5 can be adjusted manually.

  1 shows a state in which the spindle 5 is most extended, and FIG. 2 shows a state in which the spindle 5 is most retracted.

  In the second embodiment, a plurality of splines 80A are formed on the drive shaft 8A along the axial direction, and a slide unit 81 is fixed to the connecting portion 51. The slide unit 81 is provided with a plurality of continuous ball groups 82 and 83 that mesh with a plurality of splines 80A formed on the drive shaft 8A. This ball group is composed of a load ball group 83 meshing with the spline 80A and a return ball group 82 circulating in the slide unit 81, and the load ball group 83 to the return ball group sequentially as the slide unit 81 moves. Perform infinite movement to 82. For this reason, even when the spindle 5, the through hole 52, and the drive shaft 5 are lengthened, the rotational force can be reliably transmitted, so that a longer stroke can be achieved.

It is the schematic block diagram which showed the state which the spindle of the linear actuator which concerns on Example 1 of this invention extended most. It is the schematic block diagram which showed the state which the spindle of the linear actuator which concerns on Example 1 of this invention retracted most. 3 is a partially enlarged cross-sectional perspective view showing the vicinity of a connecting portion according to Embodiment 1. FIG. 6 is a partially enlarged cross-sectional perspective view showing the vicinity of a connecting portion according to Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear actuator 2 Electric motor 3 Main body case 3a Internal space 4 Female thread cylinder 5 Spindle 6 Male thread part 7 Female thread part 8 Drive shaft 9 Rotating shaft 10 Metal coupling 20, 21 Limit sensor 30 Connecting ball 51 Connecting part 52 Through-hole 53 Inner ball groove 41 Knob 80 Outer ball groove

Claims (7)

A main body case having a hollow portion, a rotating means provided on one end side of the main body case and having a rotating shaft extending to the hollow portion, provided on the other end side of the main body case, and having an internal thread on the inner peripheral surface A spindle having a male screw threadedly engaged with the female screw portion on the outer peripheral surface and a connecting portion extending to the hollow portion; a rotating shaft of the rotating means; and the spindle In the linear actuator constituted by at least a transmission means for operatively connecting the connection portions of the rotation means and a transmission means for transmitting the rotational force of the rotation means to the spindle,
The transmission means is a drive shaft having one end connected and fixed to the rotating shaft via a connecting means and the other end fixed in the rotating direction of the connecting portion and slidable in the axial direction of the connecting portion. Yes,
The connecting means includes a first fixing portion fixed to the rotating shaft, a second fixing portion fixed to one end of the drive shaft, and a space between the first fixing portion and the second fixing portion. A linear actuator characterized by comprising a position absorbing portion located at a position.   The connecting means is a metal cylindrical member including the first fixing portion, the position absorbing portion, and the second fixing portion, and the position absorbing portion is alternately cut in a radial direction at a predetermined interval. The linear actuator according to claim 1, wherein a slit is formed. The connecting portion of the spindle is formed in an axial direction, and has a through hole into which the other end side of the drive shaft is slidably inserted, and at least one inner ball groove formed along the through hole. ,
The drive shaft has at least one outer ball groove formed in an axial direction;
At least one connecting ball is interposed between the inner ball groove and the outer ball groove, the drive shaft and the connecting portion are fixed in the rotational direction and slidable in the axial direction. The linear actuator according to claim 1 or 2.   4. The linear actuator according to claim 3, wherein the connecting ball is held by a resin retainer. The connecting portion of the spindle has a through hole formed in the axial direction, and a slide unit fixed to the through hole.
The drive shaft has a plurality of splines formed in the axial direction;
The linear actuator according to claim 1, wherein the slide unit is formed with a circulation groove structure in which a plurality of balls can continuously mesh with the spline.   A limit sensor for detecting the shortest dead center point of the spindle and a limit sensor for detecting the shortest dead center point of the spindle are provided in the main body case. The linear actuator described.   The linear actuator according to claim 1, wherein the other end of the rotating shaft of the motor extends outward, and a knob is provided at a tip of the extended portion.

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