JP2000188845A - Motor-driven actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excessively heavy load from being applied to a specific spot of a nut through a driving rod, by connecting a threaded shaft to a driving shaft in such a way that the nut is screwed on the threaded shaft by its inside thread part and in the driving rod by its outside thread part. SOLUTION: A thread part 21 which is meshed with the trapezoidal screw thread 10 of a threaded shaft 11 is provided on the inner peripheral surface of a nut 19 made of a synthetic resin and a thread part 23 which is meshed with a thread part 22 provided on the inside of the opened end of a driving rod 13 is provided on the outer peripheral surface of the nut 19. When the nut 19 is screwed in the driving shaft 13 in a state such that the recessed fitting section 25 of the nut 19 meets the fitting section 26 of the rod 13, a turning inhibition member 20 is evenly brought into contact with the outer periphery of the rod 13 and pressed against the rod 13. When an engaging section 20a reaches the position at which the section 20a meets a locking section Y composed of the recessed fitting section 25 and fitting section 26, the turning inhibition member 20 returns to its original shape due to the elasticity of a connecting member 20b, and the section 20a is engaged with the locking section Y. Therefore, the nut 19 can be easily attached firmly to the rod 13 without turning (slipping).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electric actuator used as a drive source for driving a bed or the like used in a medical institution to move up and down or up and down.

[0002]

2. Description of the Related Art Conventionally, for example, a hydraulic cylinder or an air cylinder has been generally used as a device for linearly reciprocating a drive rod. The former hydraulic cylinder requires a large-scale hydraulic unit when used, and the latter air cylinder requires not only air piping but also a large exhaust noise and may be a source of noise. It is difficult to use two cylinders as a drive source for raising and lowering or raising and lowering a bed or the like used in a medical institution, etc. in consideration of the installation space and other problems such as leakage of pressure oil and noise. Met.

For this reason, in recent years, electric actuators have been used which convert the rotational motion of a motor into a linear reciprocating motion and linearly reciprocately drive a driving rod connected to an operation target. This electric actuator is convenient because the driving source is an electric motor, so that it can be miniaturized and can be used in a narrow place. The electric actuator connects a drive rod to a screw shaft that is drivably connected to a drive unit including an electric motor and a deceleration unit and that rotates at a reduced speed, for example, via a nut made of a thermoplastic synthetic resin such as polyacetal resin. By rotating the screw shaft rightward or leftward, the drive rod is configured to linearly reciprocate.

[0004] Next, the structure of a nut for drivingably connecting the screw shaft and the drive rod will be described. FIG.
As shown by reference numerals 6 and 17, the nut 105 is provided with a threaded portion 101 on the inner peripheral surface, into which the trapezoidal screw of the screw shaft is screwed, and a flange on the outer peripheral surface for setting the mounting position of the drive rod 102. A peripheral groove 103 is provided, and a concave groove 10 for locking the drive rod 102 is provided at a predetermined distance from the flange 103.
4 is recessed.

Next, the nut 105 is connected to the drive rod 10.
2, as shown in FIG.
5 is inserted into the drive rod 102 from the direction of the arrow in FIG. 16, and a key 106 projecting from the outer periphery of the nut 105 at right angles to the flange 103 is inserted into the drive rod 102 as shown in FIG. Is engaged with the key groove 107 provided in the above.

[0006] Subsequently, as shown in FIG.
The screw shaft 108 having the same structure as the screw shaft is screwed into the screw portion 101 of the nut 105 in this state.
By press-fitting the peripheral portion of the drive rod 102 corresponding to 4 into the concave groove 104 by, for example, rolling means such as a roll press, and forming a fixed portion X to which the nut 105 and the drive rod 102 are fixed, The attachment of the nut 105 to the drive rod 102 is completed.

[0007] Thereafter, a trapezoidal screw of a screw shaft (not shown) of the electric actuator is screwed into the screw portion 101 of the nut 105 attached to the drive rod 102, and the tip of the drive rod 102 is operated not shown. When the motor is started and the screw shaft is rotated to the right or left in a state of being fixed to the object, the drive rod 102 is linearly reciprocated through the nut 105.

[0008]

However, the nut 105 for connecting the screw shaft and the drive rod 102 has a very low rigidity due to the formation of the synthetic resin. When a large load is applied to the drive rod 102 by an operation target having a fixed distal end, the drive rod 1
The load concentrates on the fixed portion X between the nut 02 and the nut 105. As a result, the portion near the fixed portion X of the screw portion 101 screwed on the inner periphery of the nut 105 is deformed by the concentration of the stress accompanying the load. When the frictional force between the screw portion 101 and the trapezoidal screw of the screw shaft (not shown) increases, the screw portion 101 is overheated and thermally deformed, causing a sticking phenomenon (seizure phenomenon). There was a problem that

In particular, if the above-mentioned hugging phenomenon occurs during the operation of the electric actuator, the electric motor cannot rotate the screw shaft satisfactorily, and as a result, the electric motor may be in a locked state, causing a fire accident. there were. Further, when the phenomenon of clinging by the screw portion 101 of the nut 105 occurs, the nut 105 is stressed in the circumferential direction due to the fact that the tip of the drive rod 102 is fixed to the operation target (the screw shaft is When the key 106 formed on the nut 105 is broken by this stress, the nut 105 and the drive rod 102 are disengaged from each other in the circumferential direction. And the drive rod 102 cannot be driven in a good linear reciprocating manner.

Further, the nut 105 is connected to the drive rod 10
2, the screw shaft 108 is screwed into the screw portion 101 of the nut 105, and in this state, the driving rod of the portion corresponding to the concave groove 104 of the nut 105 is formed by using a rolling means such as a roll press. Since the 102 is press-fitted into the groove 104 and fixed, a special device is required for the work, and there is a problem that it takes time and effort. Also, as described above, the concave groove 10 of the nut 105
When the peripheral portion of the drive rod 102 is press-fitted and fixed in 4, it is difficult to easily disassemble the electric actuator during maintenance, and as a result, there is also a problem that the maintenance work cannot be performed quickly. Was.

In view of the above-mentioned various problems, the present invention avoids applying an excessive load intensively to a specific portion of a nut via a drive rod, and mounts / removes the nut to / from the drive rod. An object of the present invention is to provide an electric actuator that can be quickly and easily performed.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a driving means for generating a rotary motion, a motion converting means for converting the rotary motion into a linear motion, and a conversion means for converting the rotary motion into a linear motion. An output means for outputting the linear motion, and a driving force connecting means for drivably connecting the output means and the motion converting means, wherein the driving force connecting means includes the motion conversion inside. A nut formed with a first screw portion to be screwed with the screw shaft of the means, and a second screw portion formed on the outside with a whole screw portion provided inside the open end of the output means. A pair of recesses are provided on the base end side of the nut at an angle of 180 ° to form a pair of recesses, and a pair of fitting portions are formed on the opening end side of the output means corresponding to the recesses; The concave portion and the fitting portion Constitute an engagement portion whereby Itasa, characterized in that the locking portion nut and the output means and detachably engaged to pivot restraining member for connecting to disable idle to.

[0013] Further, the fitting portion is characterized in that a portion of an opening end of the output means corresponding to the concave portion is formed by cutting out in a U-shape along a length direction thereof.

Further, the fitting portion is formed by perforating a window hole at a position on the opening end side of the output means corresponding to the recessed portion with a size capable of fitting the rotation suppressing member. It is characterized by the following.

[0015] The rotation restraining member includes a pair of engaging portions that straddle over the recessed portion and the fitting portion constituting the locking portion to prevent the nut and the output means from idling. And a thin and elastic connecting plate for connecting the pair of engaging portions.

According to the present invention, the load of the operation target is dispersed over the entire nut by the screw portion formed on the outer periphery of the nut, and the screw portion screwed with the screw shaft screwed on the inner periphery of the nut may be damaged. In addition, it is possible to reliably prevent the phenomenon of clinging the screw portion and the screw shaft from occurring. Further, by screwing the nut to the drive rod to match the recessed portion with the fitting portion, and then fitting the rotation suppressing member to the locking portion formed by the recessed portion and the fitting portion in one operation. The nut can be quickly, easily and easily mounted on the drive rod while avoiding idling. Further, since the rotation suppressing member is formed so as to be detachable from the locking portion, the drive rod and the nut are easily disassembled at the time of maintenance of the electric actuator or the like, so that inspection and repair can be performed. It is convenient because it can be performed.

[0017]

FIG. 1 is a block diagram showing an embodiment of the present invention.
12 through FIG. FIG. 1 shows a vertical sectional side view of an electric actuator A of the present invention. In FIG.
An electric motor 1 as a driving source and a lower side of the electric motor 1 (FIG. 1)
Below), a speed reduction means 3 for converting the rotational output of the electric motor 1 from the vertical direction to the horizontal direction, for example, to reduce the rotational output. As shown in FIG. 4, for example, the deceleration means 3 includes a worm 4 formed at the tip of the rotor shaft 1a of the electric motor 1 and a worm wheel 5 meshed with the worm 4, and controls the rotation of the electric motor 1 to a predetermined speed. Decelerate to speed.

Reference numeral 7 denotes a hollow cylindrical casing in which the speed reducing means 3 and the motion converting means 9 connected to the speed reducing means 3 and driven to reduce the speed are arranged linearly (in a horizontal direction) and accommodated. On one end (left side in FIG. 1), an electric motor 1 constituting a main part of the driving means 6 is mounted in a vertically upright state as shown in FIG.

Next, the configuration of the motion converting means 9 will be described. The motion converting means 9 is, as shown in FIG.
A trapezoidal screw 10 of the same lead is screwed into a portion protruding from a cylindrical opening 8 formed at the other end (right side in FIG. 1) of the casing 7, and a base end side not having the trapezoidal screw 10 The hollow cylindrical drive rod 13 (output) is connected to a screw shaft 11 which is axially attached to the worm wheel 5 of the speed reduction means 3 via a driving force connecting means 12 which is screwed with the trapezoidal screw 10 of the screw shaft 11. Means).

Reference numeral 16 denotes a thrust bearing mounted on a terminal end (left side in FIG. 1) of the trapezoidal screw 10 threadedly mounted on the screw shaft 11 via a collar 15 which is fastened using a locking pin or the like. Reference numeral 18 denotes a radial bearing mounted on the base end side of the screw shaft 11 having no trapezoidal screw 10 in close proximity to the worm wheel 5 of the reduction means 3.
Is supported by being inserted and fixed in a bearing housing 17 fitted in the casing 7. And the screw shaft 11
Is rotatably supported by a radial bearing 18 and a bearing portion 14a provided on a cover 14 attached to an opening end of the casing 7 which opens to the speed reduction means 3 side.

Further, in the opening 8 of the casing 7,
As shown in FIG. 1, the base end of the fixed cylinder 8a into which the drive rod 13 is inserted so as to be able to move forward and backward is detachably screwed. Then, the drive rod 1 loosely fitted to the fixed cylinder 8a
3 is a screw shaft 11 of the motion converting means 9 as shown in FIG.
When the screw shaft 11 is rotated in a predetermined direction, the screw shaft 11 is moved forward and backward in a linear direction by the screw action of the driving force connecting means 12, and is fixed to the tip of the driving rod 13. The operation target can be pushed or pulled.

Next, the structure of the driving force connecting means 12 will be described. The driving force connecting means 12 is shown in FIGS.
As shown in the figure, a first screw portion 21 screwed with the trapezoidal screw 10 of the screw shaft 11 on the inner peripheral surface and a screw portion 22 screwed on the outer peripheral surface inside the open end of the drive rod 13. And a synthetic resin nut 19 having a second screw portion 23 screwed therein.
It consists of.

As shown in FIGS. 6 to 8, a base edge side (left side in FIG. 6) of the nut 19 has a flange 24 (left side in FIG. 6) for setting a mounting position of the drive rod 13. Two flat concave portions 25 are provided adjacent to each other, for example, with an interval of 180 °. In addition, the drive rod 13
As shown in FIG. 6, two U-shaped fitting portions 26 are formed at the opening ends of the nuts at intervals of 180 ° so as to correspond to the concave portions 25 of the nut 19. Then, a pair of locking portions Y, Y are formed by matching the concave portion 25 with the fitting portion 26 (see FIGS. 7 and 8).

In FIGS. 1, 5, and 12, reference numeral 20 denotes a rotation restraining member made of synthetic resin for preventing the nut 19 from rotating (spinning) with respect to the drive rod 13. 25 and a pair of engaging portions 20a, 20a releasably engaging with a locking portion Y formed by a fitting portion 26 of the drive rod 13, and the pair of engaging portions 20a, 2
And a connecting plate 20b having a thin plate-like elasticity (spring property) for connecting Oa.

The fitting portion 26 is formed, for example, as shown in FIGS. 14A and 14B, instead of forming the opening end of the drive rod 13 in a U-shape as shown in FIG. ,
A rectangular or circular window is pierced into the opening end of the drive rod 13 in such a size that the engaging portion 20a of the rotation suppressing member 20 can be fitted. 26b may be formed. Further, as shown in FIG. 5, the shape of the engaging portion 20a of the rotation suppressing member 20 is not limited to a rectangular shape (a rectangular parallelepiped shape).
The shape may be changed as appropriate according to the shape of 26b (FIG. 15 shows an example in which a cylindrical engaging portion 20c is formed).

Next, the case where the nut 19 and the drive rod 13 are connected will be described. First, as shown in FIG. 6, the distal end side (right side in FIG. 6) of the nut 19 is inserted into the opening end (left side in FIG. 6) of the drive rod 13 from the direction of the arrow in FIG. The screwed second screw part 23 and the screw part 22 screwed on the inner periphery of the drive rod 13 are screwed together. The nut 19 is connected to the drive rod 13 as described above.
When the flange edge 24 comes into contact with the open end of the drive rod 13, the screwing of the nut 19 is temporarily stopped.
By adjusting the screwing state of the nut 19 as necessary, the concave portion 25 of the nut 19 and the fitting portion 26 of the drive rod 13 are matched with each other, as shown in FIGS. Form.

Subsequently, when the nut 19 is screwed into the drive rod 13 in a state where the nut 19 is aligned with the concave portion 25 and the fitting portion 26 of the drive rod 13 as described above, as shown in FIGS. The rotation suppressing member 20 is brought into contact with the outer peripheral surface of the drive rod 13 from the direction of the arrow in FIGS. 7 and 8, and in this state, the rotation suppressing member 20 is further pressed toward the drive rod 13. At this time, as shown in FIG. 9, the rotation suppressing member 20 uses the elasticity of the connecting plate 20b to
The opening end side can be satisfactorily expanded.

Then, the pressing is continued while the opening end side of the rotation suppressing member 20 is expanded, and the engaging portion 20 a is engaged with the concave portion 25 of the nut 19 and the fitting portion 26 of the driving rod 13.
When it reaches a position that matches the locking portion Y consisting of
As shown by 12, the rotation suppressing member 20 returns to the original shape by utilizing the elasticity of the connecting plate 20b, and the engaging portion 20a is engaged with the locking portion Y. As a result, the nut 19 is simply and firmly attached to the drive rod 13 without rotating (idling) due to the presence of the engaging portion 20a of the rotation suppressing member 20 that engages with the locking portion Y. be able to.

When the rotation suppressing member 20 is attached to the locking portion Y, after the one engaging portion 20a of the rotation suppressing member 20 is engaged with the one locking portion Y, the rotation suppressing member 20 is engaged. Member 20
The other engaging portion 20a side is expanded by utilizing the elasticity of the connecting plate 20b, and in this state, the other engaging portion 20a is engaged with the other engaging portion Y. Good.

Next, in FIG. 1, reference numeral 28 denotes a one-way clutch fixed to a holder 29 attached between the bearing housing 17 of the motion converting means 9 and the thrust bearing 16 while being attached to the screw shaft 11. Reference numeral 30 denotes a brake shoe fixed to an end (the left side in FIG. 1) of the holder 29.
7 is always in sliding contact with a metal brake disc 31 attached to the end (the right side in FIG. 1) of the brake shoe 30 in correspondence with the brake shoe 30.

The one-way clutch 28 is
With respect to a rotating object (in this example, the screw shaft 11), it is configured to rotate integrally with the object in one direction and freely rotate the object in the other direction. When the one-way clutch 28 is mounted on the screw shaft 11 shown in FIG. 1, when the screw shaft 11 is to be rotated in the advance direction of the driving rod 13, the screw shaft 11 is freely rotated, and conversely, the screw shaft 11 is driven. When the rod 13 is to be rotated in the retreating direction, it is attached so as to rotate integrally with the screw shaft 11.

Therefore, when the screw shaft 11 is rotated by the driving means 6 in the direction in which the drive rod 13 is retracted, the holder 29 to which the one-way clutch 28 is fixed is rotated integrally with the screw shaft 11, The screw shaft 11 is rotated while generating a braking force between the brake shoe 30 and the brake disk 31 fixed to the holder 29. In this case, the screw shaft 11 is applied with a large braking force, Rotation is suppressed.

Further, in FIG.
A fixing member such as a snap ring made of a C-shaped ring fitted to the inside of the opening end opened in the direction in which the deceleration means 3 is accommodated and for preventing the bearing housing 17 from being pulled out. In FIG. 2, 33,
Reference numeral 33 denotes a pivot shaft of the electric actuator A, which is formed integrally with and protrudes from the casing 7 in a direction orthogonal to the axial direction of the casing 7, and a screw hole for pivotally supporting the electric actuator A is provided at the center. And the like are provided. In FIG. 1, reference numeral 35 denotes a mounting hole provided at the tip of the driving rod 13.

Next, the operation of the electric actuator A will be described. FIG. 13 shows a usable application example of the electric actuator A. When the electric actuator A is used, the pivot shafts 33 provided on the base end side thereof are used, for example, for example.
The electric actuator A is brought into contact with a support seat 36 provided on a fixed place such as a floor surface, and a pivot pin 37 is inserted into the mounting hole 34 of the pivot shafts 33 provided on the casing 7 from the support seat 36. Is pivotally supported on the support seat 36. The distal end of the drive rod 13 at the distal end of the electric actuator A is connected to the connection fitting 38 at the upper end of the pivotal support f of the operation target (for example, the back plate of the bed) B using the mounting hole 35 at the distal end of the drive rod 13. It is connected drivably by inserting the pivot 39.

When the electric actuator A is set as described above, and the operation target B is vertically raised from the inclined state shown by the solid line in FIG. 13 with the pivot portion f as a fulcrum as shown by a two-dot chain line in FIG. , A nut 19 connecting the drive rod 13 and the screw shaft 11 through the drive rod 13,
A threaded portion between the drive rod 13 and the nut 19 (screw portion 2)
Almost the entire load of the operation target B is applied to (2, 23). Since the threaded portion is formed on the entire periphery of the nut 19 in the axial direction, the driving rod 13
Is evenly distributed at the threaded portion with the nut 19 and can be satisfactorily received without partial concentration of stress.

For this reason, the screw shaft 11 screwed to the first screw portion 21 of the nut 19 via the trapezoidal screw 10 has:
At the threaded portion with the nut 19 (screw portions 10 and 21),
Although the load applied to the drive rod 13 is directly transmitted, as described above, the load is uniformly distributed and applied to the threaded portions (the screw portions 23 and 22) between the nut 19 and the drive rod 13. For this reason, the stress caused by the load is applied to the entire threaded portion of the screw shaft 11 and the nut 19 in a state of being uniformly dispersed.

Therefore, even if the nut 19 itself is formed of a synthetic resin having less rigidity than metal, the first
Since the stress caused by the load is uniformly applied to the entire area of the threaded portion 21, the first threaded portion 21 avoids the concentration of the stress on the trapezoidal screw 10 of the screw shaft 11 and breaks due to the stress concentration. In addition, the screwed state can be favorably maintained in a state in which the clinging phenomenon is suppressed.

When the electric motor A of the driving means 6 is started by the electric actuator A to raise the operation target B vertically from the inclined state shown by the solid line in FIG. 13 as shown by the two-dot chain line in FIG. The rotation of the rotation 1 is transmitted to the screw shaft 11 which is attached to the worm wheel 5 of the speed reducing means 3 in a state where the rotation is reduced to a predetermined speed by the speed reducing means 3, and the direction in which the drive rod 13 advances the screw shaft 11. To rotate.

In this case, that is, before the electric motor 1 is started, the load from the operation object B is applied to the nut 19 connecting the screw shaft 11 and the driving rod 13, and the trapezoidal screw 10 of the screw shaft 11 and the nut 19 The screw portion with the first screw portion 21 is tightly coupled. When the screw shaft 11 is rotated by the activation of the electric motor 1, the nut 19 and the drive rod 1 are rotated.
3 means that the stress of the load applied from the drive rod 13 is evenly distributed at the screwed portions (screw portions 23, 22),
Since the screw is screwed in such a manner that stress is not concentrated on one point of the screwing portion, the output from the electric motor 1 decreases the rotation speed of the rotor, but the screw shaft of the motion converting means 9 remains as it is. 11 is reliably transmitted in the state of low-speed rotation and is rotated, and the nut 19 is moved to the distal end side of the screw shaft 11 to gradually advance the drive rod 13 to move the operation target B to its pivot point f. It is pushed clockwise as the center, and rises from the inclined state shown by the solid line in FIG. 13 to the vertical state as shown by the two-dot chain line in FIG.

When the drive rod 13 is advanced as described above, the nut 19 for drivingly connecting the drive rod 13 and the screw shaft 11 is engaged with the drive rod 13 by a concave portion 25 and a fitting portion 26. The nut 19 is idled even when the drive rod 13 is fixed to the operation target B because the rotation is prevented from being rotated (idle) by the rotation inhibiting member 20 engaged with the stop portion Y. In addition, the rotational motion of the screw shaft 11 can be reliably converted to a linear motion and transmitted to the drive rod 13, so that the drive rod 13 can be advanced properly.

The screw shaft 11 which is rotated by the activation of the electric motor 1 is set so as not to receive a braking force by the function of the one-way clutch 28 when the drive rod 13 advances. Can be smoothly rotated.

Next, when the operation object B is inclined from the vertical state shown by the two-dot chain line in FIG. 13 as shown by the solid line in FIG. 13, the driving means 6 (motor 1) of the electric actuator A is set as described above. Can be rotated in the opposite direction, but also in this case, similarly to the case where the driving rod 13 is advanced, since the load of the operation target B is applied to the driving rod 13, the nut 19 and the screw shaft 11 Are screwed together in a tightly coupled state.

When the motor 1 is started and the screw shaft 11 is rotated, the nut 19 and the drive rod 13 are rotated in the same manner as described above.
Means that the stress applied to the drive rod 13 is applied to the threaded portion (screw portion 2).
3, 22) is screwed so as to effectively disperse the concentration, so that when the motor 1 is started, even if the rotation speed of the motor 1 is temporarily reduced, the output of the motor 1 is The driving rod 13 is transmitted to the screw shaft 11 in a low-speed rotation state and is rotated. The driving rod 13 is retracted toward the electric actuator A as shown by a solid line in FIG. And tilted from the vertical state shown by the two-dot chain line in FIG. 13 to the tilted state shown by the solid line in FIG.

When the operation object B is tilted by the retreat of the drive rod 13 as shown by a solid line in FIG. 13, the entire load of the operation object B is applied to the drive rod 13 so that the operation rod B is quickly retreated. I do. However, when a large load is applied to the drive rod 13 as described above, the load is transmitted to the screw shaft 11 via the nut 19, which is pushed leftward in FIG. The one-way clutch 28 attached to the screw shaft 11 causes the holder 29 to rotate integrally with the screw shaft 11, and the brake disk 30 between the brake shoe 30 and the brake disk 31 fixed to the holder 29. , The driving rod 13 does not retreat rapidly even when receiving the full load of the operation target B, and retreats in a state in which the braking force is applied to smoothly and safely move the operation target B. Can be tilted.

Also, when the drive rod 13 is retracted as described above, the nut 19 cannot rotate (idle) to the drive rod 13 by using the rotation restraining member 20 in the same manner as when the drive rod 13 is advanced. , The rotational motion of the screw shaft 11 is reliably transmitted as linear motion to the drive rod 13 via the nut 19, so that the drive rod 13 can be properly retracted.

Next, when the connection between the drive rod 13 and the nut 19 is released (disassembled) during maintenance of the electric actuator A, first, the fixed cylinder 8 is to be disassembled.
a, and the fixed cylinder 8a is pulled out of the opening 8 of the casing 7 along the drive rod 13 so that the rotation suppressing member 20 and the locking portion Y ( That is, the base end side of the nut 19) is exposed. In addition,
As shown in FIG. 1, the proximal end side of the nut 19 (left side in FIG. 1)
Is accommodated in the opening 8 of the casing 7,
By adjusting the screwing state between the nut 19 and the screw shaft 11, the base end side of the nut 19 is exposed outside the opening 8 of the casing 7.

Subsequently, the opening end side (engaging portions 20a, 20a side) of the rotation suppressing member 20 is expanded by utilizing the elasticity of the connecting plate 20b, so that the locking portion Y and the engaging portion 20a are expanded.
By disengaging the drive rod 13 and the nut 19 in this state, the drive rod 1
The nut 3 and the nut 19 can be easily and easily disassembled. As described above, in the present invention, the drive rod 13 and the nut 19 can be easily disassembled to perform inspection, repair, and the like, which is very convenient.

[0048]

As described above, according to the present invention, when the screw shaft and the drive rod are drivingly connected to each other by the nut, the nut is screwed with the screw shaft at the screw portion inside the nut, and the drive rod is connected to the drive rod. Since the screw shaft and the drive rod are driven and connected by screwing with the outer screw part, the load of the operation target applied to the drive rod is all over the screw part of the nut and the drive rod. By receiving the stress, it is possible to prevent stress caused by load from being concentrated at a specific portion of the threaded portion and to disperse the stress. As a result, a portion of the nut may be damaged by the concentration of the stress, The problem that the portion clings to the trapezoidal screw of the screw shaft due to the load can be favorably suppressed or avoided. In addition, since it is possible to avoid the occurrence of the squeezing phenomenon as described above, it is possible to reliably solve the problem that the electric motor is locked during the operation of the electric actuator to cause a burnout accident.

In addition, even when the nut and the drive rod are connected by screwing the threaded portions thereof into each other as described above, the nut and the drive rod are rotated by the locking portion formed by the concave portion and the fitting portion. By engaging the restraining member, it is possible to prevent the nut and the drive rod from idling (rotating) satisfactorily, and as a result, the screw engagement between the nut and the drive rod is not released. Therefore, the rotational motion of the screw shaft can be reliably transmitted to the drive rod via the nut, and the drive rod can be linearly reciprocated.

Further, the connection between the nut and the driving rod is made by engaging the nut with the driving rod and aligning the recessed portion with the fitting portion. By engaging the rotation suppressing member in one operation, the operation can be performed quickly and easily without using a special device.

Further, since the rotation suppressing member of the present invention is formed detachably with respect to the locking portion formed by the concave portion of the nut and the fitting portion of the drive rod, maintenance work of the electric actuator is performed. When disassembling the nut and the drive rod, the nut and the drive rod are separated from each other without causing a problem that it is difficult to easily disassemble the nut and the drive rod. It is convenient because it can be easily disassembled for inspection and repair.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing a state in which a drive rod is retracted in an electric actuator of the present invention.

FIG. 2 is a plan view of the electric actuator.

FIG. 3 is a longitudinal sectional side view showing a state where a drive rod is advanced in the electric actuator of the present invention.

FIG. 4 is a cross-sectional view of a driving unit with a main part cut away.

FIG. 5 is a perspective view of a rotation suppressing member.

FIG. 6 is an exploded view showing a nut and a drive rod constituting the drive force connecting means of the present invention.

FIG. 7 is a perspective view showing a state where a nut is screwed into a drive rod.

FIG. 8 is a longitudinal sectional front view showing a state in which a rotation suppressing member is attached to a locking portion.

FIG. 9 is a vertical sectional front view showing a state in which a rotation suppressing member is being attached to a locking portion.

FIG. 10 is a perspective view showing a state in which a rotation suppressing member is attached to the locking portion.

FIG. 11 is a longitudinal sectional front view showing a state in which a rotation inhibiting member is attached to the locking portion.

FIG. 12 is a cross-sectional plan view showing a state in which a rotation suppressing member is attached to the locking portion.

FIG. 13 is an explanatory diagram showing an application example of an electric actuator.

FIG. 14 is a longitudinal sectional side view showing another example of a fitting portion formed on the opening end side of the drive rod.

FIG. 15 is a perspective view showing another example of the rotation suppressing member.

FIG. 16 is an exploded view showing a nut and a drive rod constituting a conventional drive force connecting means.

FIG. 17 is a cross-sectional view showing a state in which a conventional nut is being attached to a drive rod.

FIG. 18 is a sectional view showing a state in which a conventional nut is attached to a drive rod.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric motor 3 Reduction means 11 Screw shaft 12 Driving force connection means 13 Drive rod 19 Nut 20 Rotation suppression member 20a, 20c Engagement part 20b Connection plate 21 First screw part 22 Screw part 23 Second screw part 25 Depressed part 26, 26a, 26b Fitting part A Electric actuator Y Locking part

Claims (4)

[Claims] 1. A driving means for generating a rotary motion, a motion converting means for converting the rotary motion into a linear motion, an output means for outputting the linear motion converted by the motion converting means, the output means and the motion converting. And a driving force coupling means for drivingably coupling the means, wherein the driving force coupling means forms a first screw portion which is screwed with a screw shaft of the motion converting means inside. And a nut formed with a second threaded portion that is screwed to the entire region of the threaded portion provided inside the open end of the output means on the outside, and a 180 ° angular interval is provided on the base end side of the nut. A pair of recesses are recessed, and a pair of fitting portions are formed on the opening end side of the output means corresponding to the recesses, and the locking portions are formed by matching the recesses and the fitting portions. And the nut Electric actuator being characterized in that detachably engage the rotating restraining member for connecting to disable idle and output means and. 2. The fitting part according to claim 1, wherein a portion of the opening end of the output means corresponding to the recessed part is cut out in a U-shape along a length direction thereof. Electric actuator. 3. The fitting portion is formed by perforating a window hole at a position on the opening end side of the output means corresponding to the recessed portion with a size capable of fitting the rotation suppressing member. The electric actuator according to claim 1, wherein: 4. A pair of engaging portions, wherein the rotation suppressing member is engaged across the recessed portion and the fitting portion constituting the locking portion to prevent the nut and the output means from idling. The electric actuator according to claim 1, further comprising: a thin, elastic connecting plate that connects the pair of engaging portions.