JP2020094606A - Actuator - Google Patents

Abstract

To provide an actuator which enables downsizing while preventing entry of foreign objects into a casing.SOLUTION: In an actuator 1, a motor unit 20 is attached to an exterior part of a casing 50. The actuator 1 includes: a motor unit 20 having a rotary shaft 21; a ball screw nut 30; a ball screw shaft 40; a slide part 10 which rotatably supports the ball screw nut 30 and linearly moves with the motor unit 20 based on linear motion of the ball screw nut 30; a casing 50 to which the ball screw shaft 40 is fixed; and a belt 80 which transmits rotational motion of the rotary shaft 21 to the ball screw nut 30. The casing 50 has: a casing body 51 formed with an opening 51a from which the belt 80 is pulled out to the exterior; and a cover 60 which covers the opening 51a in a state that the cover 60 does not interfere with the belt 80.SELECTED DRAWING: Figure 3

Description

The present invention relates to an actuator.

Patent Document 1 discloses an actuator in which a motor is attached to the outside of a casing of an actuator body, and a slide portion moves back and forth based on the rotation of a rotation shaft of the motor. This actuator includes a ball screw having a ball screw shaft and a ball screw nut, and a timing belt that is hung on the rotary shaft of the motor and the ball screw nut to transmit the rotational movement of the rotary shaft to the ball screw nut. The casing has an opening through which the timing belt is pulled out from the casing. The timing belt has its width reduced by an idler and is pulled out from the opening.

JP-A-8-216070

Since the device described in Patent Document 1 uses an idler, the idler must be housed in the casing, and it is difficult to downsize the entire actuator. However, when the idler is not used, the belt width becomes wide, and accordingly, the opening becomes large, and foreign matter may enter the inside of the casing.

The present invention has been made under the above circumstances, and it is an object of the present invention to provide an actuator that enables miniaturization while preventing foreign matter from entering the inside of a casing.

In order to achieve the above object, an actuator according to the present invention comprises
An actuator in which a motor is arranged outside the casing, and a sliding portion linearly moves,
A motor having a rotating shaft,
A ball screw nut that rotates by the rotation of the rotating shaft,
A ball screw shaft that is provided in a state in which the ball screw nut is screwed, and that linearly moves the rotating ball screw nut based on screwing with the ball screw nut,
While rotatably supporting the ball screw nut, the motor is fixed, based on the linear movement of the ball screw nut, a slide portion that linearly moves with the motor,
With the ball screw shaft fixed, a part of the slide portion, the ball screw shaft, and a casing that houses the ball screw nut,
A belt for transmitting the rotational movement of the rotary shaft to the ball screw nut,
Equipped with
The casing includes a casing body having an opening through which the belt is pulled out, and a cover that covers at least a part of the opening without interfering with the belt.

The cover is extended in a direction parallel to a linear movement direction, which is a direction in which the slide portion linearly moves,
Both ends of the cover may be supported by the casing body.

A support member that is provided on the slide portion and supports the cover may be provided.

The support member may support the cover in a first bending direction orthogonal to the parallel direction.

A first supported surface orthogonal to the first bending direction and a second supported surface facing the first supported surface are formed on the cover,
The support member may be formed with a first support surface in contact with the first supported surface and a second support surface in contact with the second supported surface.

The support member may support the cover in a second bending direction that is orthogonal to the parallel direction and is orthogonal to the first bending direction.

A third supported surface orthogonal to the second bending direction and a fourth supported surface facing the third supported surface are formed on the cover,
The support member may be provided with a third support surface in contact with the third supported surface and a fourth support surface in contact with the fourth supported surface.

A cross section of the support member orthogonal to the linear movement direction may be L-shaped or T-shaped.

According to the invention, the casing has a cover that covers the opening. No idler is used for the belt. Therefore, the present invention can provide an actuator that can be downsized while preventing foreign matter from entering the inside of the casing.

It is a perspective view of an actuator concerning an embodiment of the present invention. (A) is a plan view of the actuator. (B) is a BB sectional view of (A). It is CC sectional drawing of FIG. 2(B). It is a perspective view of an actuator from which a cable unit, a motor housing, and a pulley cover are removed. It is a perspective view in the DD cross section of FIG. (A) is a sectional view for explaining a casing, a cover, and the like. (B) is a perspective view of the cover. (A) is a side view of a casing before attaching a cover. (B) is a side view of the casing after the cover is attached. FIG. 3A is a sectional view (1) for explaining the installation state of the actuator. FIG. 6B is a sectional view (No. 2) for explaining the installation state of the actuator. It is sectional drawing for demonstrating a cover, a support member, etc. It is a perspective view of a slide part, a ball screw nut, and the like. It is a sectional view (1) for explaining the operation of the actuator, and is an XZ sectional view. FIG. 7B is a cross-sectional view (No. 2) for explaining the operation of the actuator and is a YZ cross-sectional view. It is a perspective view for explaining the operation of the actuator. FIG. 3A is a sectional view (1) for explaining the effect of the support member. FIG. 6B is a sectional view (No. 2) for explaining the effect of the support member. It is sectional drawing of the actuator which concerns on a comparative example. FIG. 6 is a cross-sectional view of an actuator for explaining the effect of a support member. It is sectional drawing of the cover, a supporting member, etc. which concern on a modification.

Hereinafter, the actuator 1 according to the embodiment of the present invention will be described with reference to the drawings. Note that the Y-axis direction in the drawing is a direction parallel to the linear movement direction D1 in which the slide portion 10 moves forward and backward, and the X-axis direction and the Z-axis direction are directions orthogonal to the linear movement direction D1.

As shown in FIGS. 1 to 4, the actuator 1 includes a motor unit 20 (motor), a ball screw nut 30, a ball screw shaft 40, a casing 50, a belt 80, in addition to the above-described slide portion 10. And a support member 90.

The motor unit 20 includes an output shaft 21 (rotating shaft), a motor body 23, a motor housing 22 that houses the motor body 23, a motor bracket 24 that supports the motor body 23, and a pulley cover that is supported by the motor bracket 24. 26 and.

The motor body 23 is, for example, a stepping motor, and has a rotor, a stator, an encoder, and the like. Electric power is supplied to the motor main body 23 from a commercial power supply via the cable of the cable unit 25. The cable unit 25 includes a cable for supplying power to the motor main body 23 from the outside and inputting/outputting control signals, and a cable guide for protecting the cable. One end of the cable guide is fixed to the pulley cover 26 of the motor unit 20 and the other end. Is fixed to the casing 50. By supplying electric power to the motor body 23, the rotor of the motor body 23 rotates. The rotational movement of the rotor is output to the output shaft 21. As a result, the output shaft 21 rotates.

The motor main body 23 is arranged outside the casing 50, specifically, on the side surface on the +X side of the casing 50, and is attached and fixed to the slide portion 10 via the motor bracket 24. As a result, the motor unit 20 reciprocates on the side surface of the casing 50 on the +X side in the linear movement direction D1 together with the slide portion 10. As shown in FIG. 4, the output shaft 21 projects from the motor bracket 24. A pulley 21a is fixed to the tip of the output shaft 21. A belt 80 is attached to the pulley 21a.

As shown in FIG. 2B, the ball screw nut 30 is housed in the casing 50 while being screwed onto the ball screw shaft 40. The ball screw nut 30 is fitted on the ball screw shaft 40 through a plurality of ball screw balls having rigidity. A pulley 30a is fixed to the ball screw nut 30. A belt 80 is attached to the pulley 30a (see FIG. 4).

The ball screw shaft 40 linearly moves the rotating ball screw nut 30 based on the engagement with the ball screw nut 30. The ball screw shaft 40 is accommodated in the casing 50 in a state of being fixed so as not to rotate or move linearly.

As shown in FIGS. 2 and 4, the casing 50 is a substantially rectangular parallelepiped member whose longitudinal direction is the linear movement direction D1, and accommodates the slide portion 10 in addition to the ball screw nut 30 and the ball screw shaft 40. In the present embodiment, the casing 50 includes a casing body 51, a cover 60, a front end side support end portion 71, and a rear end side support end portion 72.

The casing body 51 is formed with an opening 51a through which the belt 80 is pulled out. As shown in FIG. 5, the casing main body 51 includes a base 52 that supports the slide portion 10, a top plate portion 53, a side wall portion 54, and two cover fixing portions 55 in the present embodiment. Has been done.

The base 52 is formed by, for example, extruding aluminum. As shown in FIG. 3, recesses 52a and 52b are formed on the opposite surfaces of the pair of side walls of the base 52, respectively. A guide rail 56 made of iron and having a groove is attached to the recesses 52a and 52b. The slide portion 10 is supported on the base 52 via a plurality of rigid linear guide spheres. When the linear guide sphere rolls in the groove of the guide rail 56, the slide portion 10 smoothly reciprocates on the base 52.

The top plate portion 53 and the side wall portion 54 protect the ball screw nut 30 and the ball screw shaft 40, which are mechanical structure portions.

The cover 60 is a member that extends in a direction parallel to the linear movement direction D1 as a longitudinal direction. As shown in FIGS. 3 and 4, the cover 60 protects the ball screw nut 30 and the ball screw shaft 40 by covering a part of the opening 51a of the casing body 51 without interfering with the belt 80. The cover 60 is formed by extruding aluminum, for example. As shown in FIG. 6, the cover 60 has a groove 60a formed along the linear movement direction D1. Then, the cover 60 is formed with first to fourth supported surfaces 61 to 64 configured as inner surfaces of the groove 60a. The first supported surface 61 is a surface facing the second supported surface 62, and the first supported surface 61 and the second supported surface 62 are surfaces orthogonal to the Z-axis direction. The third supported surface 63 is a surface facing the fourth supported surface 64, and the third supported surface 63 and the fourth supported surface 64 are surfaces orthogonal to the X-axis direction. The first to fourth supported surfaces 61 to 64 are all parallel to the linear movement direction D1. Further, as shown in FIGS. 7A and 7B, the −Y side end and the +Y side end of the cover 60 are supported by the two cover fixing portions 55. As a result, the cover 60 is supported by the casing body 51 in a doubly supported beam shape. The cover 60 is fixed to the cover fixing portion 55 and the base 52 with bolts. The cover 60 covers a part of the opening 51a, so that the cover 60 divides the opening 51a into two gaps 51a-1 and 51a-2. The gaps 51a-1 and 51a-2 function as gaps in which the belt 80 moves when the slide portion 10 linearly moves. The gaps 51a-1 and 51a-2 are configured to have a size that does not interfere with the belt 80 when the slide portion 10 linearly moves.

Since the cover 60 is supported by the casing body 51 in a doubly supported beam shape, depending on how the actuator 1 is installed, the cover 60 is bent in the first bending direction D2 parallel to the Z-axis direction, as shown in FIG. 8A. Alternatively, as shown in FIG. 8(B), it bends in the second bending direction D3 parallel to the X-axis direction. The first bending direction D2 in FIG. 8 is a direction orthogonal to the second bending direction D3.

The leading end side supporting end portion 71 is a portion that constitutes the leading end portion of the casing 50, as shown in FIG. 1. The tip side support end 71 is fixed to the tip side (−Y side) of the casing body 51 by a fastener such as a bolt.

The rear end side support end portion 72 is a portion that constitutes the rear end portion of the casing 50, as shown in FIG. 4. The rear end side support end portion 72 is fixed to the rear end portion (+Y side) of the casing body 51 by a fastener such as a bolt. As shown in FIG. 2, the rear end side support end portion 72, together with the front end side support end portion 71, fixes the ball screw shaft 40 so that the ball screw shaft 40 does not rotate or move linearly.

As shown in FIG. 3, the belt 80 is attached to the pulley 21a of the output shaft 21 and the pulley 30a of the ball screw nut 30 in a tensioned state, thereby transmitting the rotational movement of the pulley 21a to the pulley 30a. Here, the tension of the belt 80 is adjusted by moving the motor main body 23 in the X-axis direction with respect to the motor bracket 24. The belt 80 is, for example, a timing belt formed with a plurality of teeth that engage with the teeth formed on the pulleys 21a and 30a.

The support member 90 is provided on the side surface of the slide portion 10 on the +X side. The support member 90 is used to support the cover 60 so that the cover 60 does not bend due to its own weight. The support member 90 is formed of, for example, resin, and more preferably formed of polyacetal resin. As shown in FIG. 9, the support member 90 is formed with first to fourth support surfaces 91 to 94 which are in contact with the first to fourth supported surfaces 61 to 64 when the slide portion 10 moves linearly. Has been done. The support member 90 is formed such that its XZ cross section has the same shape as the XZ cross section of the groove 60 a of the cover 60. Specifically, the support member 90 is formed so that the XZ section has an L shape.

As shown in FIG. 10, the slide part 10 includes a slide part body 11, a return cap 12 fixed to the slide part body, and a bearing 13.

The slide portion main body 11 is a member in which a through hole 11a penetrating in the Y direction is formed. The slide part body 11 is formed of, for example, a metal such as iron. A ball screw nut 30 is rotatably fitted and supported in the through hole 11 a via a bearing 13. On the +X side surface and the −X side surface of the slide portion main body 11, grooves 11c for rolling the linear guide spheres are formed parallel to the penetrating direction (Y axis direction) of the through hole 11a. .. Further, the slide body 11 is formed with a pair of moving object attachment portions 11b to which a moving object such as a table is attached. As shown in FIG. 1, the moving object attachment portion 11b is a portion exposed to the outside from the casing 50, extends in the Y-axis direction, and has a screw hole formed in the upper surface thereof. The motor unit 20 fixed to the slide portion 10 is preferably arranged on a surface other than the surface of the slide portion 10 on which the moving object attachment portion 11b is arranged.

As shown in FIG. 10, the return cap 12 is a member in which a circulation path through which the linear guide sphere circulates is formed.

The operation of the actuator 1 configured as described above will be described with reference to FIGS. 11 to 13.

First, by supplying electric power to the motor main body 23 of the motor unit 20, the output shaft 21 of the motor main body 23 rotates in the rotation direction R1 as shown in FIG. When the output shaft 21 rotates in the rotation direction R1, the rotational force is transmitted by the belt 80, and the ball screw nut 30 connected to the output shaft 21 also rotates in the rotation direction R2.

When the ball screw nut 30 rotates, the ball screw nut 30 rotates and linearly moves in the linear movement direction D1 based on the engagement with the ball screw shaft 40. When the ball screw nut 30 makes a linear movement in the linear movement direction D1, as shown in FIGS. 12 and 13, the slide portion 10 that rotatably supports the ball screw nut 30 also makes a linear movement together with the ball screw nut 30. The motor unit 20 linearly moves in the direction D1, and the motor unit 20 also linearly moves in the linear motion direction D1 together with the slide portion 10. Here, in FIG. 13, the cable unit 25 is in a removed state, but one end of the cable unit 25 moves in the linear movement direction D1 together with the motor unit 20, and the cable and the cable guide included in the cable unit 25 are respectively the motor. The cables are protected by supplying power to the main body 23 and inputting/outputting control signals.

At this time, as shown in FIG. 3, the linear guide sphere arranged between the groove of the guide rail 56 arranged in the base 52 and the groove 11c of the slide portion main body 11 rolls while rolling contact. .. As a result, the slide portion 10 smoothly moves in a straight line while being guided by the guide rail 56.

When the slide portion 10 moves linearly, the support member 90 fixed to the slide portion 10 moves in the first bending direction caused by the weight of the cover 60, as shown in FIGS. 14(A) and 14(B). Sliding in the groove 60a of the cover 60 while correcting the bending of D2. With the above, the movement of the slide portion 10 is completed.

As described above, in the actuator 1 according to the present embodiment, the casing 50 has the cover 60 that covers the opening 51a, and the belt 80 does not use an idler. Therefore, as shown in FIG. 3, it is not necessary to accommodate the idler in the casing 50, and the width W1 of the casing 50 can be reduced.

For example, when the idler 81 is used for the belt 80 like the actuator 1A according to the comparative example shown in FIG. 15, the width W2 of the casing 50 becomes large. As a result, the entire actuator 1A becomes large. On the other hand, in the actuator 1 according to the present embodiment, as shown in FIG. 3, since it is not necessary to accommodate the idler in the casing 50, the width W1 of the casing 50 can be reduced. As a result, it is possible to reduce the size of the actuator 1 as a whole while preventing foreign matter from entering the inside of the casing 50 by the cover 60.

Further, the actuator 1 according to the present embodiment includes a support member 90 that supports the cover 60, as shown in FIG. Therefore, the support member 90 can slide in the groove 60a of the cover 60 while correcting the bending caused by the weight of the cover 60 due to the forward/backward movement of the slide portion 10 in the linear movement direction D1. Therefore, in the actuator 1, it is possible to prevent the cover 60 from interfering with the belt 80 and peripheral members due to the bending of the cover 60. As a result, it is possible to suppress the obstruction of the movement of the slide portion 10 in the linear movement direction D1 due to the interference of the cover 60 with the belt 80 and the like. Further, it becomes possible to configure the actuator 1 in which the moving distance of the slide portion 10 is long.

Further, as shown in FIGS. 8A and 8B, the support member 90 supports the cover 60 in a first bending direction D2 and a second bending direction D3 which are orthogonal to each other. That is, the support member 90 supports the cover 60 in four directions of −Z direction, +Z direction, −X direction, and +X direction. Therefore, regardless of the installation state of the actuator 1, the support member 90 can correct the bending caused by the weight of the cover 60 due to the forward and backward movement of the slide portion 10 in the linear movement direction D1. As shown in FIG. 16, even if the bending occurs in the direction D4 other than the first bending direction D2 and the second bending direction D3, the support member 90 can correct the bending caused by the weight of the cover 60. it can.

Although the embodiment of the invention has been described above, the invention is not limited to the embodiment.

For example, in the present embodiment, the support member 90 is formed so that the XZ section has an L shape. However, it is not limited to this. As shown in FIG. 17, the support member 90 may be formed so that the XZ section has a T shape. Further, the cover 60 may be formed in a shape other than the L-shape or the T-shape as long as it can support the cover 60 in the first bending direction D2 and the second bending direction D3 which are orthogonal to each other.

Further, in the present embodiment, a cover 60 is attached to the side surface on the +X side of the casing body 51, as shown in FIG. However, it is not limited to this. The cover 60 may be attached to the −X side surface of the casing body 51.

Further, in the present embodiment, as shown in FIG. 9, the first to fourth supported surfaces 61 to 64 and the first to fourth support surfaces 91 to 94 are flat surfaces. However, it is not limited to this. The support member 90 may not be a flat surface as long as it can support the cover 60 in the first bending direction D2 and the second bending direction D3. For example, one of the first to fourth supported surfaces 61 to 64 and the first to fourth support surfaces 91 to 94 is a flat surface, and the first to fourth supported surfaces 61 to 64 and the first The other of the fourth support surfaces 91 to 94 may be a curved surface.

The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the present invention. The embodiments described above are for explaining the present invention, and do not limit the scope of the present invention.

1, 1A: Actuator 10: Sliding part 11: Sliding part body 11a: Through hole 11b: Moving object mounting part 11c: Groove 12: Return cap 13: Bearing 20: Motor unit (motor)
21: Output shaft (rotating shaft)
21a and 30a: Pulley 22: Motor housing 23: Motor body 24: Motor bracket 25: Cable unit 26: Pulley cover 30: Ball screw nut 40: Ball screw shaft 50: Casing 51: Casing body 51a: Opening 51a-1, 51a -2: Gap 52: Bases 52a, 52b: Recessed portion 53: Top plate portion 54: Side wall portion 55: Cover fixing portion 56: Guide rail 60: Cover 60a: Groove 61: First supported surface 62: Second supported surface Supporting surface 63: Third supported surface 64: Fourth supported surface 71: Front end side supporting end portion 72: Rear end side supporting end portion 80: Belt 81: Idler 90: Supporting member 91: First supporting surface 92: 2nd support surface 93: 3rd support surface 94: 4th support surface D1: Linear motion direction D2: 1st bending direction D3: 2nd bending direction D4, R1, R2: Direction W1, W2 : width

Claims (8)

An actuator in which a motor is arranged outside the casing, and a sliding portion linearly moves,
A motor having a rotating shaft,
A ball screw nut that rotates by the rotation of the rotating shaft,
A ball screw shaft that is provided in a state in which the ball screw nut is screwed, and that linearly moves the rotating ball screw nut based on screwing with the ball screw nut,
While rotatably supporting the ball screw nut, the motor is fixed, based on the linear movement of the ball screw nut, a slide portion that linearly moves with the motor,
With the ball screw shaft fixed, a part of the slide portion, the ball screw shaft, and a casing that houses the ball screw nut,
A belt for transmitting the rotational movement of the rotary shaft to the ball screw nut,
Equipped with
The actuator includes a casing main body having an opening through which the belt is pulled out, and a cover that covers at least a part of the opening without interfering with the belt. The cover is extended in a direction parallel to a linear movement direction, which is a direction in which the slide portion linearly moves,
The actuator according to claim 1, wherein both ends of the cover are supported by the casing body. The actuator according to claim 2, further comprising a support member that is provided on the slide portion and supports the cover. The actuator according to claim 3, wherein the support member supports the cover in a first bending direction orthogonal to the parallel direction. A first supported surface orthogonal to the first bending direction and a second supported surface facing the first supported surface are formed on the cover,
The said support member is formed with the 1st support surface which contact|connects the said 1st supported surface, and the 2nd support surface which contacts the said 2nd supported surface. Actuator. The actuator according to claim 4 or 5, wherein the support member supports the cover in a second bending direction orthogonal to the parallel direction and orthogonal to the first bending direction. A third supported surface orthogonal to the second bending direction and a fourth supported surface facing the third supported surface are formed on the cover,
The said support member is formed with the 3rd support surface which contact|connects the said 3rd supported surface, and the 4th support surface which contacts the said 4th supported surface. Actuator. The actuator according to claim 3, wherein a cross section of the support member orthogonal to the linear movement direction is L-shaped or T-shaped.

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