JP2017015183A - Straight line actuation machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a straight line actuation machine of which the size can be made compact and which enables a screw shaft and a nut and the like to be selected.SOLUTION: A straight line actuation machine of this invention comprises a driving source, a screw shaft, a nut part engaged in thread with the screw shaft through a rolling element and a rod connected to the nut part, a movable unit for moving an item under power force got from the driving source and a speed reducer for transmitting the power force of the driving source to the movable unit. The speed reducer includes a worm connected to the driving source, a worm wheel engaged with the worm and connected to one end part of the screw shaft, a thrust bearing for supporting the worm wheel and a female thread part arranged at the worm wheel, one end part of the screw shaft is provided with a male thread part engaged with the female thread part in thread, either a second movable unit having a size different from the movable unit or the movable unit is selected and the male thread part of the selected movable unit or the second movable unit is engaged in thread with the female thread part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a linear actuator that moves an object back and forth.

  Linear actuators have been used to move objects. Patent Document 1 discloses a linear actuator having a screw shaft and a nut screwed to a screw shaft via a ball, and a motor is connected to one end of the screw shaft via a speed reducer.

  The speed reducer includes a plurality of gears arranged in the radial direction. One end of the screw shaft extends to the speed reducer, and the one end is supported by a thrust bearing. The thrust bearing is arranged in parallel in the axial direction of the screw shaft.

  Further, Patent Document 2 discloses a linear actuator using a speed reducer having a worm and a worm wheel. This linear actuator is a so-called jack-type linear actuator in which a worm wheel is provided in the middle of the screw shaft.

JP 2013-160328 A Japanese Patent Laid-Open No. 2000-257689

  In the linear actuator described in Patent Document 1, since a plurality of gears are arranged in the radial direction, the reduction gear tends to be large, and one end of the screw shaft is extended to align the thrust bearing in the axial direction. Since it is provided, it tends to be long in the axial direction. The linear actuator described in Patent Document 2 uses a worm and a worm wheel to reduce the size of the speed reducer. However, since the worm wheel is provided in the middle of the screw shaft, the linear actuator is applied to the object. After installing the screw shaft, the screw shaft, the nut and the like cannot be changed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a linear actuator that can be miniaturized and can select a screw shaft, a nut, and the like at the time of assembly.

  A linear actuator according to the present invention includes a drive source, a screw shaft, a nut portion that is screwed to the screw shaft via a rolling element, and a rod connected to the nut portion. In a linear actuator comprising a moving unit that performs the above movement and a speed reducer that transmits the power of the drive source to the moving unit, the speed reducer meshes with the worm connected to the drive source, A worm wheel coupled to one end portion of the screw shaft; a thrust bearing that supports the worm wheel; and a female screw portion provided on the worm wheel, wherein the female screw portion is provided at one end portion of the screw shaft. The second moving unit or the moving unit having a male screw portion screwed to the moving unit and having a dimension different from that of the moving unit is selected, and the selected moving unit or the second moving unit is selected. The male screw portion is characterized in that screwed into the female screw portion.

  In the present invention, the worm and the worm wheel are used to promote the downsizing of the linear actuator in the radial direction. Also, a worm wheel is connected to one end of the screw shaft, and a thrust bearing is provided on the worm wheel to facilitate shortening of the linear actuator in the axial direction. Further, the worm wheel and the screw shaft are connected through a male screw portion provided at one end of the screw shaft and a female screw portion provided in the worm wheel. The male screw portion of each of the moving unit and the second moving unit is screwed into the female screw portion of the common worm wheel.

  In the linear actuator according to the present invention, the moving unit is provided at a housing cylinder that houses the screw shaft, a nut portion, and a rod, and an end portion of the nut portion, and slides on an inner surface of the housing cylinder. And a sliding portion.

  In the present invention, even when the rod extends, the sliding portion contacts the housing cylinder and supports the rod.

  The linear actuator according to the present invention is provided on each of the tip of the rod and the opposite side of the rod in the moving unit, and is provided on each of the connecting tool for connecting an object and the connecting tool, It is characterized by comprising a through hole penetrating in the same direction perpendicular to the screw shaft and a plain bearing provided in each of the through holes.

  In the present invention, sliding bearings are provided in the through holes to prevent seizure when the linear actuator rotates around the through holes.

  In the linear actuator according to the present invention, the moving unit includes a housing cylinder that houses the screw shaft, a nut portion, and a rod, and a sliding portion that is provided in the nut portion and slides on the inner surface of the housing cylinder. And provided at each of the tip of the rod and the opposite side of the rod in the moving unit, and a connector for connecting an object and each of the connectors, and orthogonal to the screw shaft. A through-hole penetrating in the same direction and a slide bearing provided in each of the through-holes, the rod and the housing cylinder being arranged coaxially, and the tip of the rod on the axis of the rod The sliding bearing, the sliding portion, the thrust bearing, and the sliding bearing on the opposite side of the rod are arranged in this order.

  In the present invention, the rod and the housing cylinder are arranged coaxially, and on the axis of the rod, a slide bearing at the tip of the rod, a sliding part, a thrust bearing, and a slide bearing on the opposite side of the rod are arranged in order. In the case where the linear actuator rotates around the through hole, both prevention of burning and smooth expansion and contraction of the rod are achieved.

  In the linear actuator according to the present invention, the linear actuator can be reduced in size in the radial direction by using the worm and the worm wheel, and the worm wheel is connected to one end of the screw shaft, and the worm By providing the wheel with a thrust bearing, it can be shortened in the axial direction. Further, the worm wheel and the screw shaft are connected through a male screw portion provided at one end of the screw shaft and a female screw portion provided in the worm wheel. Since the male screw portion of each of the moving unit and the second moving unit is screwed into the female screw portion of the common worm wheel, the moving unit or the second moving unit is selected according to the user's needs when assembling the linear actuator. Can be selected.

It is a top view which outlines a linear actuator. It is sectional drawing which made the II-II line shown in FIG. 1 the cutting line. It is explanatory drawing explaining operation | movement of a linear actuator. It is explanatory drawing explaining selection of a mobile unit.

  Hereinafter, the present invention will be described based on the drawings showing a linear actuator according to an embodiment. FIG. 1 is a plan view schematically showing a linear actuator, and FIG. 2 is a sectional view taken along line II-II shown in FIG.

  The linear actuator includes an accommodation cylinder 1 in which a screw shaft 2 is accommodated coaxially. One end of the screw shaft 2 is provided with a male screw portion 2a that is screwed into a female screw portion 12c described later. The male screw portion 2 a protrudes from the one end portion of the housing cylinder 1 in the axial direction. The other end of the screw shaft 2 is located in the housing cylinder 1.

  A nut portion 3 is engaged with the screw shaft 2 via a rolling element (not shown), for example, a ball. The screw shaft 2 is inserted into a cylindrical rod 4, and one end portion of the rod 4 is fitted on one end portion of the nut portion 3. The rod 4 is arranged coaxially with respect to the housing cylinder 1 and the screw shaft 2.

  A sliding ring 8 that slides on the inner peripheral surface of the housing cylinder 1 is fitted on the other end of the nut portion 3 (the end opposite to the rod 4).

  A support cylinder 5 that supports the rod 4 is fitted into the other end of the housing cylinder 1. The other end of the rod 4 protrudes from the other end of the housing cylinder 1 through the support cylinder 5. The other end of the rod 4 is provided with a first connector 6 that is connected to an object, and the first connector 6 is provided with a first through hole 6a. A slide bearing 7 is fitted in the first through hole 6a.

  The male screw portion 2 a is connected to a drive source, for example, a motor 20 via a speed reducer 10. The speed reducer 10 includes a casing 11, and a worm wheel 12 is provided in the casing 11. The worm wheel 12 includes a cylindrical boss portion 12a and a gear portion 12b provided at an axially central portion of the boss portion 12a. A female screw portion 12c is provided inside one end of the boss portion 12a. Thrust bearings 13 are provided at both ends of the boss 12a, and the thrust bearing 13 supports the worm wheel 12 in a rotatable manner.

  The thrust bearing 13 also supports the screw shaft 2 and is therefore designed to be larger than the conventional thrust bearing 13 and has a higher rigidity, thereby realizing a longer life of the thrust bearing 13 and an allowable thrust. The load is also increasing.

  The casing 11 has an opening 11a, and the worm wheel 12 is arranged so that the male screw portion 2a is positioned in the opening 11a. An attachment plate 9 is provided in the opening 11 a, and one end of the housing cylinder 1 is attached to the speed reducer 10 via the attachment plate 9. The male screw portion 2a provided at one end of the housing cylinder 1 is detachably screwed with the female screw portion 12c.

  On the axis of the rod 4, there are a slide bearing 7 fitted in the first through hole 6 a, a nut portion 3, a sliding ring 8, two thrust bearings 13 and 13, and a slide bearing 15 fitted in the second through hole 14 a. Arranged in order.

  The motor 20 is connected to the speed reducer 10 so that the rotating shaft (not shown) of the motor 20 is orthogonal to the housing cylinder 1. A worm 16 is provided on the rotating shaft of the motor 20, and the worm 16 meshes with the gear portion 12 b of the worm wheel 12. The casing 11 is provided with a plurality of mounting portions (not shown) for mounting the worm 16 in the circumferential direction of the worm wheel 12, and the mounting position of the motor 20 with respect to the speed reducer 10 is changed according to the space of the installation location. can do.

  On the opposite side of the opening 11a, the casing 11 is provided with a second connector 14 that is connected to an object, and the second connector 14 is provided with a second through hole 14a. A slide bearing 15 is fitted in the second through hole 14a. The axial directions of the first through hole 6 a and the second through hole 14 a are substantially the same, and both are directions orthogonal to the screw shaft 2.

  As the motor 20 rotates forward and backward, the worm wheel 12 and the screw shaft 2 rotate forward and backward, and the nut portion 3 moves linearly in one direction or the other direction along the screw shaft 2. Or advance into the storage cylinder 1.

  In FIG. 2, the configuration on the left side of the mounting plate 9, that is, the housing cylinder 1, the screw shaft 2, the nut portion 3, the rod 4, the first connector 6, the sliding ring 8, and the support cylinder 5 are the motor 20. The moving unit 31 is configured to move the object by the power from the (see FIG. 4 described later).

  Next, a straight line when a transmission mechanism 40 such as a crank mechanism or a link mechanism is rotatably connected to the first through hole 6a, and a metal fitting such as a trunnion metal fitting or a clevis metal fitting is rotatably connected to the second through hole 14a. The operation of the actuator will be described. The transmission mechanism 40 rotates about the origin O.

  FIG. 3 is an explanatory diagram for explaining the operation of the linear actuator. The initial position of the shaft center of the rod 4 is P1, and the position of the shaft center of the rod 4 when the linear actuator is rotated by an angle θ1 in one direction around the second through hole 14a with P1 as a reference is P2. To do. The initial position of the transmission mechanism 40 is Q1, and the position of the transmission mechanism 40 when the transmission mechanism 40 rotates in one direction by an angle θ2 around the origin O with Q1 as a reference is Q2.

  As shown in FIG. 3A, a transmission mechanism 40 is rotatably connected to the first through hole 6a. A metal fitting (not shown) is rotatably connected to the second through hole 14a. The axis of the rod 4 is located at P1, and the transmission mechanism 40 is located at Q1.

  As shown in FIG. 3B, when the rod 4 advances, the rod 4 rotates the transmission mechanism 40 in one direction. The linear actuator rotates in one direction around the second through hole 14a as the transmission mechanism 40 rotates at a substantially right angle. When the axis of the rod 4 rotates by an angle θ1 from the initial position P1 and moves to the position P2, the transmission mechanism 40 is substantially perpendicular to the initial position P1. That is, the angle θ1 indicates the maximum rotation angle of the rod 4 with respect to the initial position P1.

  As shown in FIG. 3C, when the rod 4 further advances, the linear actuator rotates in the other direction around the second through hole 14a, and the position of the axis of the rod 4 returns from P2 to P1. Further, the transmission mechanism 40 further rotates in one direction, rotates by an angle θ2 from the initial position Q1 in FIG. 3A, and moves to the position Q2. The angle θ2 indicates the maximum rotation angle of the transmission mechanism 40 with the initial position Q1 as a reference. When the rod 4 is retracted, the linear actuator performs the operation opposite to the above operation.

  As shown in the above operation, when the motor 20 rotates forward and backward, the second connecting portion and the metal fitting rotate and slide in the second through hole 14a, but the slide bearing 15 is provided in the second through hole 14a. Therefore, the occurrence of baking can be prevented.

  Also, in the first through hole 6a, the transmission mechanism 40 and the first connector 6 rotate and slide, but since the slide bearing 7 is provided in the first through hole 6a, the occurrence of seizure is prevented. Can do.

  When the rod 4 advances, a moment with the support cylinder 5 as a fulcrum acts on the rod 4 due to the weight of the rod 4 and the first connector 6. For this reason, when the sliding ring 8 is not provided, the nut portion 3 approaches the inner periphery of the housing cylinder 1, the gap between the ball and the screw shaft 2 or the nut portion 3 is reduced, and the nut portion 3 moves smoothly. There is a risk that it cannot be done.

  In the linear actuator according to the embodiment, the sliding ring 8 is provided on the axis of the rod 4 to prevent the gap between the ball and the screw shaft 2 or the nut portion 3 from being reduced. 4 smooth movements can be realized.

  Further, since the thrust bearing 13 supports not only the worm wheel 12 but also the screw shaft 2, the linear actuator can be shortened in the axial direction as compared with a case where a bearing for supporting the screw shaft 2 is separately provided. Can do.

  Further, the rod 4 and the housing cylinder 1 are coaxially arranged, and are provided on the slide bearing 7, the sliding ring 8, the thrust bearing 13, and the second through hole 14 a provided in the first through hole 6 a on the axis of the rod 4. By arranging the slide bearings 15 in order, it is possible to achieve both prevention of seizure and smooth expansion and contraction of the rod 4 when the linear actuator rotates around the first through hole 6a and the second through hole 14a.

  FIG. 4 is an explanatory diagram for explaining selection of a mobile unit. When the linear actuator is assembled, the operator can select the moving unit 31 or the second moving unit 32. The second moving unit 32 is different in size from the moving unit 31. In the following description, the second moving unit 32 is assumed to be larger than the moving unit 31, but may be smaller than the moving unit 31.

  Each component constituting the second moving unit 32 is larger in size than each component constituting the moving unit 31 except for the male screw portion 2a. However, since the dimensions of the male screw portion 2a are the same, the male screw portion 2a of the second moving unit 32 can be screwed into the female screw portion 12c of the worm wheel 12, and the second moving unit 32 can be attached to the speed reducer 10. Therefore, at the time of assembly, the operator selects the moving unit 31 or the second moving unit 32, and the male screw portion 2a of the selected moving unit 31 or the second moving unit 32 is screwed to the female screw portion 12c of the worm wheel 12. Can be made.

  In addition, since the motor 20 and the speed reducer 10 are shared, it is not necessary to manufacture the dedicated motor 20 and the speed reducer 10 corresponding to the moving unit 31 and the second moving unit 32, respectively. Therefore, the manufacturing cost can be reduced. Further, when the user desires a linear actuator having a longer life, the second moving unit 32 may be attached to the speed reducer 10, and it is easy to meet the user's request.

  In the second moving unit 32, the first connector 6, the first through hole 6 a, the second connector 14, and the second through hole 14 a are also larger than the moving unit 31. The first connecting tool 6 and the second connecting tool 14 are connected to the user side device by a connecting portion (for example, a connecting pin). In the second moving unit 32, a connecting portion larger than the moving unit 31 is used. Can be linked. That is, the strength of the connecting portion can be increased.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of claims and the scope equivalent to the scope of claims. Is done.

DESCRIPTION OF SYMBOLS 1 Housing cylinder 2 Screw shaft 2a Male screw part 3 Nut part 4 Rod 6 1st connection tool 6a 1st through-hole 7, 15 Slide bearing 8 Sliding ring (sliding part)
DESCRIPTION OF SYMBOLS 10 Reduction gear 12 Worm wheel 12c Female screw part 13 Thrust bearing 14 2nd connection tool 14a 2nd through-hole 16 Worm 20 Motor (drive source)
31 mobile unit 32 second mobile unit

Claims (4)

A drive source, a screw shaft, a nut portion screwed to the screw shaft via a rolling element, and a rod connected to the nut portion, and a moving unit for moving an object by power from the drive source; In a linear actuator comprising a speed reducer that transmits power of a drive source to the moving unit,
The speed reducer is
A worm coupled to the drive source;
A worm wheel meshed with the worm and connected to one end of the screw shaft;
A thrust bearing for supporting the worm wheel;
A female screw portion provided on the worm wheel,
A male screw portion screwed into the female screw portion is provided at one end portion of the screw shaft,
A second moving unit or the moving unit having a dimension different from that of the moving unit is selected, and the male screw portion of the selected moving unit or second moving unit is screwed into the female screw portion. A linear actuator. The mobile unit is
A housing cylinder for housing the screw shaft, nut portion and rod;
The linear actuator according to claim 1, further comprising: a sliding portion that is provided at an end of the nut portion and slides on an inner surface of the housing cylinder. A connecting tool for connecting an object, provided at each of the tip of the rod and the opposite side of the rod in the moving unit;
A through-hole provided in each of the coupling tools and penetrating in the same direction perpendicular to the screw shaft;
The linear actuator according to claim 1, further comprising a slide bearing provided in each of the through holes. The mobile unit is
A housing cylinder for housing the screw shaft, nut portion and rod;
A sliding portion that is provided on the nut portion and slides on the inner surface of the housing cylinder;
A connecting tool for connecting an object, provided at each of the tip of the rod and the opposite side of the rod in the moving unit;
A through-hole provided in each of the coupling tools and penetrating in the same direction perpendicular to the screw shaft;
A plain bearing provided in each of the through holes,
The rod and the receiving cylinder are arranged coaxially,
The linear work according to claim 1, wherein a sliding bearing, a sliding part, a thrust bearing, and a sliding bearing on the opposite side of the rod are arranged in this order on the axis of the rod. Motivation.

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