JP2001086700A - Electrically-driven actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a screw smoothly movable in the axial line direction when an electric motor becomes not operable and can not rotate from a nut side, in an electrically-driven actuator which rotates a nut on the basis of the operation of the electric motor and moves the screw combined with the nut in the axial line direction. SOLUTION: An electrically-driven actuator 1 is equipped with a nut 11 rotating by the operation of an ultrasonic motor 6, a screw 21 for converting the rotating motion of the nut 11 to a rectilinear motion in the axial line direction, a regulating member 22 which allows or regulates the rotation of the screw 21, and an electromagnetic clutch 26 which allows or regulates the rotation of the regulating member 22. A piston head 29c for pressuring a member 31 to be pressurized by the rectilinear motion of the screw 21 is so linked with the screw 21 by a thrust bearing 29b that relative rotation is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric actuator using an electric motor as a drive source.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 63-266228 and Japanese Patent Application Laid-Open No. 8-284980 disclose a pressurizing / depressurizing device using an electric actuator of this kind, for example, an electric brake device for vehicles.
Is disclosed in Japanese Patent Application Laid-Open Publication No. HEI 9-203 (1995).

As a common feature of the above two publications, an ultrasonic motor is provided as an electric motor, and a nut rotated by the operation of the motor is provided with a screw and a screw supported non-rotatably and axially movable with respect to a housing. Have been combined. When the nut is rotated by the operation of the ultrasonic motor, the screw moves along the axial direction, and the pressure contact force of the brake pad as the object to be pressed is increased or decreased.

[0004]

However, if the power supply line for supplying drive power to the ultrasonic motor is broken, or if the motor becomes inoperable due to a failure of the motor itself, etc.,
Due to the nature of the ultrasonic motor, the holding force when stopping is large,
Even if a reaction force from the brake pad acts, the motor does not rotate (idle).

Therefore, if the ultrasonic motor becomes inoperable as described above while the brake pad is pressed against the brake disk, the pad remains pressed against the disk. Then, the vehicle equipped with such a brake device may not be able to move.

Therefore, in the brake device disclosed in Japanese Patent Application Laid-Open No. Hei 8-284981, a support shaft which can be manually rotated with respect to the housing is provided, and the screw cannot be rotated with respect to the support shaft and can be moved in the axial direction. A proposal has been made to support it. When the ultrasonic motor becomes inoperable, the support shaft is manually rotated to retract the screw. As a result, it is possible to avoid a state in which the pad is kept pressed against the disk, and it is possible to move the vehicle even if the ultrasonic motor becomes inoperable.

However, in this brake device, since the thrust sensor contacting the inner pad is fixed to the tip of the screw via the plate, the screw also rotates when the support shaft is rotated to retract the screw. As a result, the thrust sensor and the inner pad come into sliding contact with each other. Therefore, due to the sliding contact resistance, the rotational torque when the screw is retracted is large, and the screw may not be smoothly retracted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to rotate a nut based on the operation of an electric motor and move a screw combined with the nut in the axial direction. It is an object of the present invention to provide an electric actuator that can smoothly move a screw in an axial direction even when an electric motor becomes inoperable and a motor cannot rotate from a nut side.

[0009]

According to a first aspect of the present invention, there is provided an electric motor as a drive source, a nut rotating by the operation of the electric motor,
A screw combined with the nut, for converting the rotational movement of the nut into a linear movement in the axial direction, a drive transmission unit for transmitting the linear movement of the screw to a driven member, the drive transmission unit and the screw A rotation connecting means for connecting the drive transmission unit and the screw so as to be relatively rotatable, a restricting member connected to the screw and permitting or restricting the rotation of the screw, and permitting the rotation of the restricting member. Or a switching means for regulating.

According to a second aspect of the present invention, in the electric actuator according to the first aspect, the rotation connecting means includes:
It consisted of a thrust bearing. According to a third aspect of the present invention, in the electric actuator according to the first or second aspect, the rotation connection unit further connects the drive transmission unit to be swingable with respect to a center axis of the screw.

According to a fourth aspect of the present invention, in the electric actuator according to the third aspect, the rotation connecting means includes:
Consisting of an axial seat thrust bearing. According to a fifth aspect of the present invention, in the electric actuator according to the third aspect, the rotation connecting means is constituted by a ball joint.

Therefore, according to the first aspect of the present invention,
In normal operation, the rotation of the restricting member is restricted by the switching means during operation of the electric motor, and the screw cannot rotate. Then, when the nut is rotated based on the operation of the electric motor, the screw combined with the nut moves in the axial direction, and the linear motion in the axial direction is transmitted to the driven member via the rotation coupling means and the drive transmission unit. You. On the other hand, when the electric motor becomes inoperable and the motor cannot rotate from the nut side, rotation of the regulating member is permitted by the switching means, and the screw becomes rotatable. At this time,
When an axial reaction force acts on the drive transmission member from the driven member, the drive transmission portion and the screw can rotate relative to each other.Therefore, only the screw is rotated by the nut without sliding contact with the driven member. Then, the screw retracts smoothly in the axial direction.

According to the second aspect of the present invention, the drive transmission portion and the screw are connected to each other by the thrust bearing so as to be relatively rotatable. According to the third aspect of the present invention, the drive transmission unit is rotatably connected to the screw and is swingably connected to the center axis of the screw by the rotation connection unit. Therefore, the drive transmission unit swings so that the direction of the force between the drive transmission unit and the driven member is orthogonal to the contact surface of the drive transmission unit, and the drive transmission between the drive transmission unit and the driven member is performed efficiently.

According to the fourth aspect of the present invention, the drive transmitting portion is connected to the screw by the aligning seat thrust bearing so as to be rotatable relative to the screw and to be swingable with respect to the center axis of the screw.

According to the fifth aspect of the present invention, the drive transmitting portion is connected to the screw by the ball joint so as to be rotatable relative to the screw and to be swingable with respect to the center axis of the screw.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the housing of the electric actuator 1 has first and second housings.
The housing 2, 3 and the cover 4 constitute a housing space 5. Various components such as an ultrasonic motor 6 as a driving source are accommodated in the accommodation space 5.

More specifically, a stator 7 is fixed to the first housing 2 by screws 8. Stator 7
Is provided with a vibration transmitting portion 7a for transmitting vibration to the rotor 10 described later. Further, a piezoelectric element 9 is joined to the stator 7.

The stator 7 is provided with a rotor 10 having a lining material (not shown) that comes into contact with the vibration transmitting portion 7a. The rotor 10 is connected to a substantially cylindrical nut 11 having a thread formed on an inner peripheral surface thereof by a key 12 so as to be movable in the axial direction and to be relatively non-rotatable.
1 and are connected so as to rotate together. This nut 11
Is rotatably supported by a tapered roller bearing 13 provided in the first housing 2 and a ball bearing 14 provided in the second housing 3.

The surface of the rotor 10 on the side opposite to the stator 7 is pressed by a pressure urging member 17 composed of a disc spring 15 and a plate 16. That is, in a state where the disc spring 15 is compressed and deformed in the axial direction by the rotor 10 and the plate 16, the plate 16 cannot be rotated with respect to the nut 11, and cannot be further moved toward the stator 7 by the circlip 18. Be linked. Thus, the rotor 10 is pressed against the stator 7 with a predetermined pressing force by the urging force of the disc spring 15. Such a pressure urging member 17 rotates integrally with the nut 11 and the rotor 10.

On the surface of the plate 16 on the side opposite to the stator 7, an annular magnet 19, which is multipolarly magnetized in the rotation direction at its outer peripheral portion, is fixed. On the other hand, in a portion of the second housing 3 facing the magnet 19,
A Hall element 20 that changes the magnetic field is provided. The Hall element 20 is provided to detect the number of rotations of the rotor 10 by detecting a magnetic field that changes with the rotation of the magnet 19.

In the ultrasonic motor 6 configured as described above, when a high-frequency drive voltage is applied to the piezoelectric element 9, the piezoelectric element 9 vibrates, and the vibration of the piezoelectric element 9 proceeds in the vibration transmitting portion 7 a of the stator 7. Wave vibration occurs. The rotor 10 rotates based on the traveling wave vibration, and the nut 11 rotates.

The nut 11 that operates as described above is screwed with a substantially cylindrical screw 21 having a thread formed on the outer peripheral surface. A restricting member 22 for allowing or restricting the rotation of the screw 21 is connected to the base end of the screw 21.

More specifically, the regulating member 22 includes a substantially cylindrical insertion portion 22a and a substantially disk-shaped flange portion 22b. The insertion portion 22a has a key 22c that extends in the axial direction on the outer peripheral surface. On the other hand, the screw 21 is formed with a fitting hole 21a having the same shape as the radial cross section of the inserting portion 22a, and the inserting portion 22a is fitted into the fitting hole 21a. Therefore, the screw 21 is supported so as to be movable in the axial direction with respect to the regulating member 22 and to be relatively non-rotatable.

A disc-shaped leaf spring 23 is provided on the flange portion 22b.
An annular armature 24 made of a magnetic material is fixed to an outer peripheral portion of the leaf spring 23. In contrast,
The excitation coil 25a for attracting the armature 24
The coil bobbin 25b around which the coil 25a is wound is
It is fixed to the housing 3. Then, the exciting coil 25a
The armature 24 and the armature 24 constitute an electromagnetic clutch 26, which permits or regulates the rotation of the regulating member 22.

That is, when the excitation coil 25a is energized and excited, the armature 24 is attracted to the coil 25a, so that the regulating member 22 cannot rotate. On the other hand, when the exciting coil 25a is de-energized to be in a non-excited state, the armature 24 is separated from the coil 25a, so that the regulating member 22 becomes rotatable.

The regulating member 22 is provided with a thrust receiving plate 27 which receives a thrust force in a direction in which the regulating member 22 comes out of the screw 21. A holding rubber 28 is attached to the thrust receiving plate 27, and the holding rubber 28 is assembled to the cover 4. Then, the thrust receiving plate 27 abuts on the leaf spring 23, and regulates the movement of the regulating member 22 in the direction of coming out of the screw 21 any more. That is, the gap between the armature 24 and the exciting coil 25a is prevented from widening.

A piston 29 is attached to the tip of the screw 21. That is, a mounting hole 21b is formed at the tip of the screw 21, and the piston body 29a is fitted and fixed in the mounting hole 21b. A piston head 29c is rotatably connected to the piston main body 29a via a thrust needle bearing 29b. Also, the piston body 2
9a is provided with a load sensor 30 for detecting a load applied to the piston head 29c. As the load sensor 30, for example, a strain gauge type or a piezoelectric ceramic type load sensor is used. The piston head 29c has a planar contact surface 29d, and the contact surface 29d is brought into contact with the member to be pressed 31 and the screw 2
The member 1 is pressed to press the member 31 to be pressed.

The electric actuator 1 thus configured is controlled by the controller 32. The piezoelectric element 9, the Hall element 20, the exciting coil 25a, and the load sensor 30 are electrically connected to the controller 32. The controller 32 detects the rotation speed of the rotor 10 of the ultrasonic motor 6 based on the detection signal from the Hall element 20 and detects the load applied to the piston head 29c based on the detection signal from the load sensor 30.

The controller 32 controls the ultrasonic motor 6 (piezoelectric element 9) according to two operation modes: a "normal operation mode" and an "abnormal operation mode" when the ultrasonic motor 6 becomes inoperable. And the excitation coil 25a.

As an initial state of the "normal operation mode", the electromagnetic clutch 26 is off, that is, the exciting coil 25a is in a non-exciting state. Therefore, since the armature 24 is separated from the exciting coil 25a, the regulating member 22 is in a rotatable state.

The controller 32 first switches the exciting coil 25a to the excited state based on the pressurizing command. Then, the armature 24 is attracted to the exciting coil 25a, so that the regulating member 22 cannot rotate. Therefore, the regulating member 22 regulates the rotation of the screw 21, so that the screw 21 can move only in the axial direction.

Next, the controller 32 applies a high-frequency drive voltage to the piezoelectric element 9 to operate the ultrasonic motor 6,
Rotate the rotor 10 forward. Then, the nut 11 rotates forward, and the screw 21 whose rotation is restricted protrudes and moves along the axial direction. Due to the projecting movement of the screw 21, the piston 29 applies a pressing force to the member to be pressed 31.

On the other hand, based on the pressure reduction command, the controller 32 applies a high-frequency driving voltage to the piezoelectric element 9 to rotate the rotor 10 in the reverse direction. Then, the nut 11 is reversed, and the screw 21 is immersed and moved along the axial direction. Due to such immersion movement of the screw 21, the pressure of the piston 29 applied to the member to be pressed 31 is reduced.

In this way, the controller 32 controls the pressing force applied to the pressurized member 31 by rotating the nut 11 forward and backward based on the pressurizing command and the pressure reducing command, causing the screw 21 to protrude and retract. When the pressurizing command and the depressurizing command disappear, the controller 32 sets the exciting coil 25
a is switched to the non-excited state, and the regulating member 22 is brought into a rotatable state, that is, the above-mentioned initial state.

"Abnormal operation mode" This mode is a mode when the ultrasonic motor 6 becomes inoperable. The controller 32 determines that the ultrasonic motor 6 cannot be operated when the rotation speed of the rotor 10 is continuously detected as “0” by the Hall element 20 even if a high-frequency drive voltage is applied to the piezoelectric element 9, for example. Then, control according to the mode is performed.
That is, in this mode, the controller 32 maintains the electromagnetic clutch 26 in the off state, that is, the excitation coil 25a in the non-excitation state even when the above-described pressurization command and pressure reduction command are generated. Therefore, the armature 24 is connected to the exciting coil 25a.
, The regulating member 22 is maintained in a rotatable state.

If the ultrasonic motor 6 becomes inoperable with the screw 21 protruding, that is, with the piston 29 pressing the member 31 to be pressed, the piston head 2
A reaction force acts on 9c in a direction in which the screw 21 is immersed and moved from the pressed member 31. At this time, since the ultrasonic motor 6 has a large holding force when stopped, the nut 11 does not rotate.

On the other hand, as described above, since the rotation of the regulating member 22 is permitted, the screw 21 is in a rotatable state. Therefore, when a reaction force acting in the direction of retracting the screw 21 acts on the piston head 29c, the thrust needle bearing 29b causes the piston body 2 to move.
9a rotates with respect to the piston head 29c, that is, the screw 21 rotates. Then, the screw 21 is immersed and moved while being rotated by the nut 11. As described above, even if the ultrasonic motor 6 becomes inoperable, the screw 21 can be retracted, so that it is possible to avoid the state where the piston 29 keeps pressing the pressed member 31. .

In the present embodiment, the piston head 2
Since the thrust needle bearing 29b is provided between the piston 9c and the piston main body 29a (the screw 21), the piston head 29c does not rotate with respect to the pressurized member 31 even when the piston main body 29a rotates together with the screw 21. Therefore, since the piston head 29c and the member to be pressurized 31 do not slide with each other, the screw 21 can be retracted smoothly.

The electric actuator 1 according to the present embodiment
Is used in various devices as shown in FIGS. 2 (a) to 2 (d), for example. FIG. 2A shows a disc brake device 100 for a vehicle. The electric actuator 1 makes use of the axial movement of the screw 21 to move the brake pad 101 toward and away from the brake disk 102 to adjust the braking force of the vehicle.

FIG. 2B shows a tension device 110 for a belt-type variable speed reducer. The electric actuator 1 controls the pressing force applied to the belt 111 by using the axial movement of the screw 21 to apply a predetermined tension to the belt 111.

FIG. 2C shows a hydraulic control device 120. The electric actuator 1 controls the pressing force of the piston 121 by using the axial movement of the screw 21 to control the hydraulic pressure in the pipe 122.

FIG. 2D shows an electric press device 130. The electric actuator 1 presses the upper mold 131 by using the axial movement of the screw 21 and presses the material 133 by the upper mold 131 and the lower mold 132.

As described above, according to the present embodiment,
The following effects are obtained. (1) The screw 21 and the piston head 29c are relatively rotatable using the thrust needle bearing 29b. Therefore, when the ultrasonic motor 6 becomes inoperable and the screw 21 is retracted, the piston head 29c does not rotate with respect to the member to be pressed 31 even when the piston main body 29a rotates together with the screw 21. Accordingly, since the piston head 29c and the member to be pressed 31 do not slide with each other, the screw 2 can be efficiently driven by the reaction force from the member to be pressed 31.
1, and the screw 21 can be retracted smoothly. Further, since the piston head 29c and the member to be pressed 31 do not slide with each other, they do not wear each other.

(2) Screw 21 and piston head 2
Since the thrust needle bearing 29b is used as a means for connecting the shaft 9c to the shaft 9c so as to be relatively rotatable, the structure can be simplified.

(3) Since the switching of the rotation of the regulating member 22 is permitted or regulated by the electromagnetic clutch 26, the switching operation can be performed without complication.

The embodiment of the present invention may be modified as follows. In the above embodiment, the screw 21 and the piston head 29c can be rotated relative to each other by using the thrust needle bearing 29b. However, the present invention is not limited to this configuration. For example, another thrust bearing such as a thrust ball bearing may be used. Further, the configuration may be as shown in FIGS.

As shown in FIG. 3, a piston 33 may be attached to the tip of the screw 21. More specifically, the piston body 33a is attached to the mounting hole 2 at the tip of the screw 21.
1b. In this piston body 33a,
The piston head 33c is connected via the alignment seat thrust ball bearing 33b. That is, the bearing 33b has a spherical sliding contact surface 33d, and the piston body 29a has a spherical sliding contact concave portion 33e with which the sliding contact surface 33d slides. Accordingly, the piston head 33c is moved by the thrust ball bearing 33b.
(Screw 21), and connected to the center axis L1 of the piston body 33a (screw 21) so as to be swingable. And the piston head 33c
It has a flat contact surface 33f that comes into contact with the pressed member 31.

In this way, the bearing 33
Since the piston head 33c swings so that the direction of the force between the piston head 33c and the pressed member 31 is orthogonal to the contact surface 33f of the piston head 33c,
The drive transmission between them can be performed efficiently. Further, even if the member to be pressed 31 swings with respect to the center axis L1, the swing is absorbed by the bearing 33, so that the swing of the screw 21 itself can be suppressed. Therefore, the screw 21
Since a large force does not act on the member attached to the screw 21 in the swinging direction, the durability can be improved.

Of course, in FIG. 3, the aligning seat thrust ball bearing 33b is used, but the present invention is not limited to this, and other aligning seat thrust bearings may be used such as the aligning seat thrust roller bearing.

As shown in FIG. 4, the piston head 33c
The contact surface 33g with the member to be pressed 31 may be spherical. By doing so, in addition to the operation and effect of the embodiment shown in FIG. 3 described above, even if the pressed member 31 swings with respect to the center axis L1, the contact surface 33g is spherical, so that
The swing of the screw 21 itself can be suppressed. Therefore, since a large force does not act on the screw 21 and the members attached to the screw 21 in the swinging direction, the durability can be improved.

As shown in FIG. 5, a piston 34 may be attached to the tip of the screw 21. More specifically, the piston body 34a is attached to the mounting hole 2 at the tip of the screw 21.
1b. The piston body 34a includes:
Piston head 34c via ball joint 34b
Are linked. Specifically, a ball 34d is interposed between the piston main body 34a and the piston head 34c, and the piston main body 34a and the piston head 34c are connected. That is, the piston head 34c is connected to the piston body 34a (the screw 2) by the ball joint 34b.
1), it is rotatably connected to the center axis L1 of the piston body 34a (the screw 21). Then, the piston head 34c is connected to the pressed member 31.
Has a spherical contact surface 34e that abuts the contact surface 34e. Even in this case, the same operation and effect as in the embodiment shown in FIG.

As shown in FIG. 6, a piston 35 may be attached to the tip of the screw 21. More specifically, the piston body 35a is attached to the mounting hole 2 at the tip of the screw 21.
1b. A ball joint 35b is formed in the piston body 35a. That is, a spherical concave portion 35c is formed in the piston body 35a, and the concave portion 35c
Is fitted with the ball 35d. And this ball 35
A flat contact surface 35e with which the member to be pressed 31 directly contacts is formed at d. That is, the ball 35d is relatively rotatable with respect to the piston body 35a (the screw 21), and the center axis L1 of the piston body 35a (the screw 21).
Can be swung with respect to. Even in this case, the same operation and effect as in the embodiment shown in FIG. In addition, the piston 35 can be constituted by a small number of members.

As shown in FIG. 7, a piston 36 may be attached to the tip of the screw 21. More specifically, the piston body 36a is attached to the mounting hole 2 at the tip of the screw 21.
1b. In this piston body 36a,
Piston head 36c via ball joint 36b
Are linked. Specifically, a ball 36d is formed integrally with the piston body 36a, and the piston head 36c is connected to the ball 36d. That is, the piston head 36c is connected to the piston main body 36a (the screw 21) by the ball joint 36b so as to be relatively rotatable and swingable about the center axis L1 of the piston main body 36a (the screw 21). And the piston head 3
6c is a spherical contact surface 36 contacting the member 31 to be pressed.
e. Even in this case, the same operation and effect as those of the embodiment shown in FIG. 5 are obtained.

As shown in FIG. 8, the piston head 36c
An annular contact convex portion 36g may be formed on the outer peripheral portion of the surface 36f facing the member 31 to be pressed. In this way, in addition to the effects of the embodiment shown in FIG. 3, the pressure can be concentrated on the contact projection 36g.

In the above embodiment, the electromagnetic clutch 26 is used as the electric switching means for permitting or restricting the rotation of the regulating member 22, but an apparatus having another configuration may be used. Alternatively, the rotation of the restricting member 22 may be manually switched between allowable and restricted.

In the above-described embodiment, the regulating member 22 is formed as shown in FIG. 1. However, the shape of the regulating member is not limited to this as long as the screw 21 can be supported so as to be movable in the axial direction and not to rotate relatively. Not something.

In the above embodiment, even if a high-frequency drive voltage is applied to the piezoelectric element 9, the ultrasonic motor 6 operates when the rotation number of the rotor 10 continuously detects “0” by the Hall element 20. Although it is determined that it is impossible, the present invention is not limited to this.

In the above embodiment, the electric actuator 1 uses the traveling wave type ultrasonic motor 6.
The configuration is not limited to this. For example, an electric actuator using a standing wave type ultrasonic motor or a motor having a large cogging torque / detent torque as a drive source may be used. Further, an electric actuator having a configuration in which the rotation of the motor is transmitted to the nut via a reduction gear having a large reduction ratio, such as a worm and a worm wheel, may be used. That is, any electric actuator having a configuration that is difficult to rotate from the nut side may be used.

The screws and nuts according to the above-described claims also include a ball screw having a ball rotatably interposed between the screw and the nut, and a nut thereof.

The technical ideas other than the claims that can be grasped from the above embodiments will be described below together with their effects. (A) The electric actuator according to claim 2, wherein the thrust bearing is constituted by a thrust ball bearing or a thrust roller bearing. With this configuration, the drive transmission unit and the screw can be connected to be relatively rotatable.

(B) The electric actuator according to claim 4, wherein the aligning seat thrust bearing is constituted by an aligning seat thrust ball bearing or an aligning seat thrust roller bearing. With this configuration, the drive transmission unit can be connected to the screw so as to be rotatable relative to the screw and swingably with respect to the center axis of the screw.

(C) In the electric actuator according to claim 5, the ball joint is fixed to the screw and has a ball receiving portion having a spherical concave portion, and a ball receiving portion fitted to the spherical concave portion and connected to the driven member. An electric actuator, comprising: a ball having a contact surface and functioning as the drive transmission unit. With this configuration, the drive transmission unit can be connected to the screw so as to be rotatable relative to the screw and swingably with respect to the center axis of the screw.

(D) Claims 1 to 5 or (a) to (d)
(C) The electric actuator according to any one of (1) to (4), wherein the drive transmitting unit has a spherical contact surface with the driven member. With this configuration, even if the driven member swings with respect to the center axis of the screw, the swing of the screw itself can be suppressed because the contact surface is spherical. Therefore, since a large force does not act on the screw or the member attached to the screw in the swing direction, the durability can be improved.

(E) Claims 1 to 5 or (A) to (C)
(C) The electric actuator according to any one of (1) to (4), wherein the drive transmission unit has a contact projection formed on a surface facing the driven member. By doing so, the force can be concentrated on the contact convex portion.

(F) Claims 1 to 5 or (A) to (C)
The electric actuator according to any one of (e) to (f), wherein the switching unit electrically permits or restricts rotation of the restricting member. According to this configuration, since the rotation of the rotation of the regulating member or the switching of the regulation is performed electrically, the switching operation can be performed without complication.

(G) Claims 1 to 5 or (A) to (C)
(F) The electric actuator according to any one of (1) to (4), wherein the electric motor is an ultrasonic motor. With this configuration, even if the ultrasonic motor becomes inoperable and the motor cannot rotate from the nut side, the screw can be smoothly moved in the axial direction.

[0067]

As described in detail above, according to the present invention,
An electric actuator that rotates a nut based on the operation of an electric motor and moves a screw combined with the nut in the axial direction, even if the electric motor becomes inoperable and the motor cannot rotate from the nut side, It is possible to provide an electric actuator capable of smoothly moving the actuator in the axial direction.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electric actuator according to an embodiment.

FIG. 2 is a schematic diagram of a pressurizing and depressurizing device using an electric actuator.

FIG. 3 is a sectional view of a main part of another example of an electric actuator.

FIG. 4 is a sectional view of a main part of another example of an electric actuator.

FIG. 5 is a sectional view of a main part of another example of an electric actuator.

FIG. 6 is a sectional view of a main part of another example of the electric actuator.

FIG. 7 is a sectional view of a main part of another example of an electric actuator.

FIG. 8 is a sectional view of a main part of another example of an electric actuator.

[Explanation of symbols]

6 ... Ultrasonic motor as electric motor, 11 ... Nut,
Reference numeral 21: screw, 22: regulating member, 26: electromagnetic clutch as switching means, 29b: thrust needle bearing as rotary connection means and thrust bearing, 29c: piston head as drive transmission part, 31: driven member, 33
b: Alignment seat thrust ball bearing as rotary connection means and alignment seat thrust bearing; 33c: Piston head as drive transmission unit; 34b, 35b, 36b: Ball joint as rotation connection means; 34c, 36c: Drive transmission Piston head as part, 35d ball as drive transmission part, L1 central axis.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H605 CC02 CC03 EB02 EB10 5H607 BB01 BB08 CC01 CC03 DD02 EE07 EE52 FF01 5H680 BB03 CC06 EE02 EE03 EE23 FF23 GG01

Claims (5)

[Claims] An electric motor (6) as a drive source, and a nut (1) rotated by the operation of the electric motor (6).
1) and the nut (11).
A screw (21) for converting the rotational motion of 1) into a linear motion in the axial direction; and a linear motion of the screw (21) for the driven member (3).
1), the drive transmission units (29c, 33c, 34c,
35d, 36c), and the drive transmission units (29c, 33c, 34c, 35d, 3)
6c) and the screw (21), and the drive transmission parts (29c, 33c, 34c, 35d, 36c)
Connecting means (29b, 33b, 34b, 35b, 36b) for connecting the screw and the screw (21) so as to be relatively rotatable.
And the screw (21) is connected to the screw (2).
An electric actuator comprising: a regulating member (22) for permitting or regulating the rotation of 1); and a switching means (26) for permitting or regulating the rotation of the regulating member (22). 2. The electric actuator according to claim 1, wherein the rotary connecting means (29b) includes a thrust bearing (29).
An electric actuator, which is constituted by b). 3. The electric actuator according to claim 1, wherein the rotation connecting means includes a rotating connection unit.
Are further provided with the drive transmission units (33c, 34c, 35d, 3).
An electric actuator characterized in that 6c) is swingably connected to a center axis (L1) of the screw (21). 4. The electric actuator according to claim 3, wherein the rotation connecting means (33b) is constituted by an aligning seat thrust bearing (33b). 5. The electric actuator according to claim 3, wherein said rotation connecting means (34b, 35b, 36b) is constituted by a ball joint (34b, 35b, 36b).