JP2022148963A - Liner motion device and actuator - Google Patents

Abstract

To provide an actuator capable of releasing the connection with an output shaft.SOLUTION: A linear motion device comprises: a screw shaft; a nut that converts the rotational motion of the screw shaft into the axial linear motion of the screw shaft; a connection member that connects an output shaft for outputting an axial force based on the linear motion converted by the nut to the nut; and a release member capable of releasing the connection between the nut and the output shaft.SELECTED DRAWING: Figure 1

Description

The present invention relates to linear motion devices and actuators.

As an actuator for obtaining axial force from input torque, there is a technique using a ball screw that converts rotary motion into linear motion. This actuator converts the rotary motion of the screw shaft into the linear motion of the nut, and the axial force is extracted from the output shaft coupled to the nut. Patent Literature 1 discloses a technique using a transmission element for coupling a nut of an actuator and an output shaft.

JP 2012-42050 A

In an actuator that uses a transmission element to connect the nut and the output shaft, if the power transmission system is stuck, it is desirable to release the connection between the actuator and the output shaft in order to avoid the effects of the sticking.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a linear motion device and an actuator that can be disconnected from an output shaft using a cotter.

In order to solve the above problems, according to a linear motion device according to an aspect of the present invention, there are provided a screw shaft, a nut that converts rotary motion of the screw shaft into linear motion in the axial direction of the screw shaft, and the nut. a coupling member that couples an output shaft that outputs an axial force based on the linear motion converted to the nut to the nut; and a releasing member that can release the coupling between the nut and the output shaft.

As a result, even when the movement of the nut is restrained according to the fixed state or load state of the power transmission system, it is possible to prevent the movement of the output shaft from being restrained via the nut, thereby improving the power transmission system. It is possible to avoid the influence of sticking state or high load state.

Further, according to the linear motion device according to the aspect of the present invention, the releasing member can reversibly release the connection between the nut and the output shaft.

As a result, even if the movement of the nut is restrained due to the stuck state or load state of the power transmission system, the movement of the output shaft is prevented from being restrained via the nut without destroying the linear motion device. can be prevented. Therefore, it is possible to prevent the operation of the output destination of the axial force from the output shaft from being restrained via the output shaft, and to avoid the influence of the stuck state or high load state of the power transmission system. .

Further, according to the linear motion device according to the aspect of the present invention, the coupling member can penetrate the output shaft in a direction perpendicular to the axial direction of the screw shaft and can be inserted into and removed from the nut.

As a result, the nut and the output shaft can be coupled and the coupling between the nut and the output shaft can be released based on the insertion and removal of the coupling member. Complex arrangements such as mechanisms or clutch mechanisms are no longer required. Therefore, the nut and the output shaft can be coupled while suppressing an increase in the size and cost of the actuator.

Further, according to the linear motion device according to the aspect of the present invention, the releasing member can restore the coupling after releasing the coupling.

As a result, after releasing the coupling between the nut and the output shaft, the linear motion device can be operated normally without replacing the coupling member and the nut. Therefore, it is possible to release the connection between the nut and the output shaft while suppressing deterioration in maintainability of the actuator.

Moreover, according to the linear motion device according to the aspect of the present invention, the coupling member is a cotter or a key.

Accordingly, it is possible to connect the nut and the output shaft or to release the connection between the nut and the output shaft based on the insertion and removal of the connecting member.

Further, according to the linear motion device according to the aspect of the present invention, the cotter has a circumferential gap in the circumferential direction of the output shaft with respect to the nut and the output shaft, and the key has a gap between the nut and the output shaft. An axial clearance is provided with respect to the output shaft in the axial direction of the output shaft.

Accordingly, even when prying acts on the output shaft, the action can be absorbed by the circumferential clearance and the axial clearance, and prying can be prevented from acting on the ball screw. Therefore, even if misalignment occurs during assembly of the linear motion device and the output shaft, the life of the actuator using the linear motion device can be increased.

Further, according to the linear motion device according to the aspect of the present invention, the release member is an electromagnet capable of pulling out the coupling member from the nut.

Accordingly, by controlling the current flowing through the electromagnet, it is possible to couple the nut and the output shaft or to release the coupling between the nut and the output shaft. Therefore, in order to release the connection between the nut and the output shaft, there is no need to use a complicated structure such as a gripping mechanism or a clutch mechanism, and complication of the structure of the actuator can be suppressed.

Further, according to the linear motion device according to the aspect of the present invention, the elastic member is provided between the electromagnet and the coupling member, and holds the coupling member at a coupling position between the nut and the output shaft. .

As a result, the coupling member can be pulled out from the nut while preventing the coupling member from slipping out of the nut when coupling the nut and the output shaft, and the coupling between the nut and the output shaft can be reversibly released.

Further, according to the linear motion device according to one aspect of the present invention, the electromagnet includes a winding and an iron core around which the winding is wound, and the iron core is used for extracting the coupling member from the nut. It extends into the elastic member to a non-obstructive position.

As a result, the attractive force of the electromagnet can be increased without enlarging the linear motion device, and the efficiency of releasing the connection between the nut and the output shaft can be improved.

Further, according to the linear motion device according to the aspect of the present invention, the releasing member includes a motor having a rotating shaft having a male thread, and the rotating shaft extends in a direction perpendicular to the axial direction of the screw shaft. Disposed along the connecting member, the coupling member includes an opening formed with female threads mateable with the male threads.

As a result, the coupling member can be linearly moved in the axial direction of the rotary shaft based on the rotational motion of the motor. By switching the rotational direction of the motor, the nut and the output shaft can be coupled, can be unbound. Therefore, it is possible to release the coupling between the nut and the output shaft while suppressing the complication of the configuration of the actuator.

Further, according to the linear motion device according to the aspect of the present invention, the release member is an actuator capable of pulling out the coupling member from the nut.

Accordingly, by operating the actuator, the nut and the output shaft can be coupled, the coupling between the nut and the output shaft can be released, and the coupling between the nut and the output shaft can be released.

Further, according to a linear motion device according to an aspect of the present invention, there is provided a screw shaft, a nut that converts rotary motion of the screw shaft into linear motion in the axial direction of the screw shaft, and linear motion converted by the nut. and a pressing portion capable of reversibly pressing the coupling member in a direction in which the coupling member is accommodated in the recess of the nut, The coupling member moves in the axial direction of the screw shaft from the state accommodated in the recess of the nut based on the force applied in the axial direction of the screw shaft so that it can escape from the recess of the nut. A shape of the coupling member and the recess is set.

As a result, by pressing the connecting member, it is possible to connect the nut and the output shaft. The coupling member can be moved axially to move the coupling member out of the recess. Therefore, the connection between the nut and the output shaft can be released without using a complicated structure such as a gripping mechanism or a clutch mechanism. Able to avoid impact.

Further, according to the direct-acting device according to the aspect of the present invention, the coupling member has a shape that narrows in the direction toward the tip, and the recess has a shape corresponding to the shape of the coupling member.

Thereby, when force is applied to the coupling member in the axial direction of the output shaft, force can be applied in the radial direction of the output shaft as well. Therefore, the coupling member can be pulled out of the recess as the coupling member moves in the axial direction of the output shaft, and the coupling between the nut and the output shaft can be released while suppressing the complication of the actuator configuration. can be done.

Moreover, according to the direct-acting device according to the aspect of the present invention, the shape of the tip of the coupling member is wedge-shaped.

As a result, when a force is applied to the coupling member in the axial direction of the output shaft, it is possible to apply a force in the radial direction of the output shaft as well, and the complication of the configuration of the coupling member is suppressed. It is possible to release the connection between the nut and the output shaft while suppressing complication of the structure of the actuator.

Further, according to the linear motion device according to the aspect of the present invention, the shapes of the coupling member and the recess are rotationally symmetrical about the radial axis of the output shaft.

As a result, when force is applied to the coupling member in the axial direction of the output shaft, it is possible to apply force also in the radial direction of the output shaft, and to simplify the processing of the coupling member. be able to.

Further, according to the linear motion device according to the aspect of the present invention, the pressing portion includes a pressure medium that can be sealed in a space provided on the rear end side of the coupling member, and the pressure medium that is sealed in the space. a releasing part for releasing the medium.

As a result, by introducing a pressure medium into the space provided on the rear end side of the coupling member, the coupling member can be pressed, and the nut and the output shaft can be coupled together. By releasing the medium, it is possible to move the coupling member in the axial direction of the output shaft. It can be pulled out of the recess. Therefore, the connection between the nut and the output shaft can be released without using a complicated structure such as a gripping mechanism or a clutch mechanism. Able to avoid impact.

Moreover, according to the linear motion device according to the aspect of the present invention, the pressing portion is a spring provided on the rear end side of the coupling member.

Accordingly, by providing a compressed spring on the rear end side of the coupling member, the coupling member can be pressed, and the nut and the output shaft can be coupled together, and the coupling member can be moved in the axial direction of the output shaft. is moved, the coupling member can be pulled out of the recess while further compressing the spring. Therefore, the nut and the output shaft can be connected without providing a detector for detecting the sticking state of the power transmission system, a power section that supplies power from the outside, and a control section that controls the power based on the detection result of the sticking state. can be released from the coupling, and the effect of the sticking of the power transmission system can be avoided while suppressing the complication of the configuration of the actuator.

Further, according to the linear motion device according to the aspect of the present invention, the coupling member has a gap in the radial direction of the output shaft with respect to at least one of the nut and the output shaft.

As a result, even if prying action acts on the output shaft, the action can be absorbed by the gap between the connecting member and the prying action, and the prying action can be prevented from acting on the ball screw. Therefore, even if misalignment occurs during assembly of the linear motion device and the output shaft, the life of the actuator using the linear motion device can be increased.

An actuator according to an aspect of the present invention includes any one of the linear motion devices described above and the output shaft.

As a result, even when the power transmission system is stuck, it is possible to prevent the operation of the output destination of the axial force from the output shaft from being restrained via the output shaft without destroying the linear motion device. It is possible to avoid the effects of stuck state or high load state of the power transmission system.

Further, according to the actuator according to one aspect of the present invention, the output shaft includes a storage portion that stores the releasing member at a position that allows the coupling to be released.

As a result, the release member can be accommodated in the output shaft, and the release member can be prevented from protruding from the output shaft. Therefore, it is possible to construct an actuator capable of releasing the connection between the nut and the output shaft while preventing an increase in difficulty in handling and installing the actuator.

Further, according to the actuator of one aspect of the present invention, the storage portion is an opening provided in the output shaft.

As a result, the release member can be accommodated in the output shaft while suppressing the complication of the configuration of the output shaft, and the attachment of the release member to the actuator can be facilitated.

According to one aspect of the present invention, it is possible to provide a linear motion device and an actuator that can be disconnected from an output shaft using a cotter.

FIG. 1 is a perspective view showing the configuration of an actuator according to the first embodiment. FIG. Fig. 2(a) is a perspective view showing the coupling state between the nut and the output shaft of the actuator according to the first embodiment; Fig. 2(b) is a sectional view showing the coupling state between the nut and the output shaft; 2(c) is a perspective view showing a disengaged state between the nut and the output shaft, and FIG. 2(d) is a sectional view showing a disengaged state between the nut and the output shaft. 3(a) is a cross-sectional view showing a coupled state between the nut and the output shaft of the actuator according to the second embodiment, and FIG. 3(b) is a cross-sectional view showing a released state between the nut and the output shaft. be. FIG. 4 is a cross-sectional view showing a configuration example of the iron core of the electromagnet of the actuator according to the third embodiment. FIG. 5 is a perspective view showing the configuration of an actuator according to the fourth embodiment. FIG. 6(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the fifth embodiment, and FIG. 6(b) is an enlarged view of the cotter portion of FIG. 6(a). It is a sectional view showing. FIG. 7(a) is a cross-sectional view showing the configuration of the actuator when the coupling between the nut and the output shaft is released according to the fifth embodiment, and FIG. 7(b) is an enlarged view of the cotter portion of FIG. 7(a). It is a cross-sectional view shown in FIG. FIG. 8(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the sixth embodiment, and FIG. 8(b) is an enlarged view of the cotter portion of FIG. 8(a). It is a sectional view showing. Fig. 9(a) is a sectional view showing the configuration of the actuator when the coupling between the nut and the output shaft is released according to the sixth embodiment, and Fig. 9(b) is an enlarged view of the cotter portion of Fig. 9(a). It is a cross-sectional view shown in FIG. FIG. 10(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the seventh embodiment, and FIGS. 10(b) to 10(d) are the nut of FIG. Fig. 10 is an enlarged cross-sectional view showing the movement of the cotter when the coupling between the and the output shaft is released; 11(a) is a perspective view showing an example of the configuration of the cotter in FIG. 10(a), and FIG. 11(b) is a perspective view showing another example of the configuration of the cotter in FIG. 10(a). FIG. 12 is a side view showing an example of a gap between a cotter and a nut according to the eighth embodiment; FIG. 13 is a side view showing an example of the gap between the cotter and the output shaft according to the ninth embodiment. FIG. 14(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the tenth embodiment, and FIGS. Fig. 10 is an enlarged cross-sectional view showing the movement of the cotter when the coupling between the and the output shaft is released;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention, and not all combinations of features described in the embodiments are essential for the configuration of the present invention. The configuration of the embodiment can be appropriately modified or changed according to the specifications of the device to which the present invention is applied and various conditions (use conditions, use environment, etc.). The technical scope of the present invention is defined by the claims and is not limited by the following individual embodiments. In addition, the drawings used in the following description may differ from the actual structure in terms of scale, shape, etc., in order to make each configuration easier to understand.

FIG. 1 is a perspective view showing the configuration of an actuator according to the first embodiment. FIG.
In FIG. 1, actuator EA1 outputs an axial force in the axial direction based on rotational motion. The actuator EA1 has a screw shaft 1, a nut 2, an output shaft 3 and a cotter 4. The screw shaft 1 and the nut 2 can be used as a ball screw that constitutes a linear motion device. The screw shaft 1 performs rotational motion based on rotational force generated from a driving source such as a motor. The nut 2 converts rotary motion of the screw shaft 1 into axial linear motion of the screw shaft 1 . The output shaft 3 outputs axial force based on the linear motion converted by the nut 2 . The shape of the output shaft 3 is, for example, cylindrical. At this time, the inner peripheral surface of the output shaft 3 can be configured to follow the outer peripheral surface of the nut 2 . The nut 2 can be provided between the outer peripheral surface of the screw shaft 1 and the inner peripheral surface of the output shaft 3 .

The cotter 4 is used as a connecting member that connects the output shaft 3 to the nut 2 . The cotter 4 penetrates the output shaft 3 in a direction orthogonal to the axial direction of the screw shaft 1 and can be inserted into and removed from the nut 2 . When the cotter 4 is inserted into the nut 2 , it is supported by the nut 2 while protruding toward the output shaft 3 . The cotter 4 can be used as an axial force transmission member from the nut 2 to the output shaft 3 .

The screw shaft 1 has a thread groove 1m. The thread groove 1m is spirally provided on the outer peripheral surface of the screw shaft 1 . The nut 2 has a thread groove 2m. The thread groove 2m is spirally provided on the inner peripheral surface of the nut 2 so as to face the thread groove 1m. At this time, the screw grooves 1m and 2m form a spiral ball rolling path between the screw shaft 1 and the nut 2. As shown in FIG.

The material of the screw shaft 1, the nut 2 and the output shaft 3 is not particularly limited as long as it is a rigid body. For example, it may be metal such as iron or aluminum alloy, or non-metal such as ceramic. The material of the cotter 4 is magnetic material such as iron or ferrite. The cross-sectional shape of each thread groove 1m, 2m may be, for example, an arc or a Gothic arc.

One end of the screw shaft 1 is connected to the gear 13 . The gear 13 is rotatably supported by the housing 12 via the bearing 11 and is axially fixed by the gear fixing nut 14 . The bearing 11 is, for example, an angular ball bearing.

A rotational force generated from a driving source such as a motor is input to the screw shaft 1 via the gear 13, and the screw shaft 1 is rotated. When the screw shaft 1 rotates, the balls between the screw shaft 1 and the nut 2 circulate in the ball rolling path via a ball circulator (not shown), and the nut 2 linearly moves. An axial force based on the linear motion of the nut 2 is transmitted to the output shaft 3 via the cotter 4 and output via the output shaft 3 .

Actuator EA1 can be used, for example, in a damping device for a vehicle. For example, in the case of a damping device for a railway vehicle, an actuator EA1 can be installed between the vehicle body and the bogie. By outputting from the output shaft 3 an axial force having a phase opposite to the vibration of the vehicle body, the vibration of the vehicle body can be reduced.

The actuator EA1 can reversibly release the connection between the nut 2 and the output shaft 3. Here, the actuator EA1 includes an electromagnet 5 as a releasing member capable of reversibly releasing the connection between the nut 2 and the output shaft 3. As shown in FIG. Electromagnet 5 can pull cotter 4 out of nut 2 . The electromagnet 5 includes an iron core 5A and windings 5B. Winding 5B is wound around iron core 5A. The material of the iron core 5A is preferably a material with high magnetic permeability, such as pure iron, silicon steel, or ferrite.

Actuator EA1 further comprises spring 6 and bearing 7 . The spring 6 is used as an elastic member that restrains the cotter 4 at the joint position between the nut 2 and the output shaft 3 . A spring 6 is provided between the electromagnet 5 and the cotter 4 . The spring 6 is not particularly limited as long as it is an elastic member such as a spring, a plate spring, or a disc spring that suppresses the cotter 4 . Rubber may be used instead of the spring 6 . Electromagnet 5 and spring 6 can be accommodated within output shaft 3 . Here, in order to accommodate the electromagnet 5 and the spring 6 in the output shaft 3, the thickness of the output shaft 3 may be increased at the position where the electromagnet 5 and the spring 6 are accommodated. Further, the distance between the electromagnet 5 and the cotter 4 can be set so that the cotter 4 can be pulled out from the nut 2 with the spring 6 contracted.

The bearing 7 supports the output shaft 3 so as to be linearly movable with respect to the housing containing the output shaft 3 . The bearing 7 is, for example, a sliding bearing. The bearing 7 can be fixed to the outer peripheral surface of the output shaft 3 . At this time, the bearing 7 may be arranged on the electromagnet 5 . The material of the bearing 7 is resin, for example. By disposing the bearing 7 on the electromagnet 5 , it is possible to prevent the electromagnet 5 and the spring 6 from slipping out of the output shaft 3 .

Here, it is assumed that the movement of the nut 2 is restrained according to the fixed state or load state of the power transmission system such as the motor, gear, or direct acting parts. At this time, when a stuck state or a high load state of the power transmission system is detected, an electric current is applied to the electromagnet 5 to compress the spring 6 and move the cotter 4 to a position where the cotter 4 is pulled out from the nut 2 . can be drawn to When the cotter 4 is pulled out from the nut 2, the axial force based on the linear motion of the nut 2 cannot be transmitted to the output shaft 3 via the cotter 4, and the movement of the output shaft 3 is restrained via the nut 2. can be prevented. Therefore, it is possible to prevent the operation of the output destination of the axial force from the output shaft 3 from being restrained via the output shaft 3, thereby avoiding the influence of the stuck state or high load state of the power transmission system. can be done.

For example, it is assumed that an actuator EA1 is installed between the vehicle body and bogie of a railway vehicle. At this time, if the power transmission system is stuck, the actuator EA1 is always in a taut state, and the vibration of the bogie is directly transmitted to the vehicle body via the actuator EA1, thereby deteriorating the ride comfort of the railcar. At this time, a current is applied to the electromagnet 5 to pull the cotter 4 out of the nut 2, thereby releasing the connection between the nut 2 and the output shaft 3. As a result, even when the power transmission system is stuck, it is possible to prevent the vibration of the bogie from being transmitted to the vehicle body as it is via the actuator EA1, thereby improving the ride comfort of the railway vehicle.

Further, by pulling out the cotter 4 from the nut 2 based on the electromagnetic force of the electromagnet 5, the connection between the nut 2 and the output shaft 3 can be released. Therefore, it is not necessary to destroy the nut 2 or the cotter 4 in order to release the connection between the nut 2 and the output shaft 3, and deterioration of maintainability of the actuator EA1 can be suppressed.

Also, by cutting off the current flowing through the electromagnet 5, the connection between the nut 2 and the output shaft 3 can be restored. Therefore, even when the coupling between the nut 2 and the output shaft 3 is released, the actuator EA1 can be returned to normal operation without replacing the nut 2 and the cotter 4. FIG.

Furthermore, by using the cotter 4 for coupling the nut 2 and the output shaft 3, the nut 2 and the output shaft 3 can be coupled or the coupling between the nut 2 and the output shaft 3 can be released based on the insertion and withdrawal of the cotter 4. It becomes unnecessary to use a complicated structure such as a gripping mechanism or a clutch mechanism in order to release the connection between the nut 2 and the output shaft 3 . Therefore, the nut 2 and the output shaft 3 can be coupled while suppressing an increase in the size and cost of the actuator EA1.

The operation of releasing the connection between the nut 2 and the output shaft 3 using the electromagnet 5 will be described in detail below.
FIG. 2(a) is a perspective view showing the coupling state between the nut and the output shaft of the actuator according to the first embodiment, and FIG. 2(b) is an axially cut view of the coupling state between the nut and the output shaft. Fig. 2(c) is a perspective view showing a state in which the connection between the nut and the output shaft is released; It is a sectional view showing.

In FIGS. 2(a) and 2(b), the nut 2 has a recess 2A. The recess 2A accommodates the tip of the cotter 4. As shown in FIG. The planar shape of the recess 2</b>A can correspond to the planar shape of the tip of the cotter 4 . The recess 2A can be provided on the outer peripheral surface of the nut 2. As shown in FIG.

The output shaft 3 has a through hole 3A and openings 3B-3D. The through hole 3A and openings 3B to 3D can be provided on the side surface of the output shaft 3. As shown in FIG. At this time, the tip of the cotter 4 can be accommodated in the recess 2A through the through hole 3A and the openings 3B to 3D. The through hole 3A accommodates the rear end of the cotter 4. As shown in FIG. Opening 3B accommodates spring 6 between electromagnet 5 and cotter 4 . The opening 3</b>C accommodates the electromagnet 5 with a gap from the cotter 4 in the radial direction of the output shaft 3 . The opening 3D accommodates the bearing 7 so as to cover the electromagnet 5 .

A step may be provided between the openings 3B and 3C in order to support the electromagnet 5 in the output shaft 3 with a gap from the cotter 4. As shown in FIG. By installing the electromagnet 5 accommodated in the case 8 on the step between the openings 3B and 3C, the electromagnet 5 can be supported in the output shaft 3 with a gap from the cotter 4.

In the coupled state of the nut 2 and the output shaft 3, the rear end of the cotter 4 is fitted into the recess 2A while protruding into the through hole 3A. The cotter 4 is pressed by a spring 6 so as not to come out of the recess 2A. At this time, the spring 6 is maintained in a state of being compressed between the cotter 4 and the electromagnet 5 . That is, in the coupled state of the nut 2 and the output shaft 3, the spring 6 presses the cotter 4 and is maintained in a state capable of further contracting.

It is assumed that the power transmission system is fixed and the movement of the nut 2 is restrained when the nut 2 and the output shaft 3 are connected. At this time, when the fixed state of the power transmission system is detected and current is applied to the electromagnet 5, the cotter 4 is attracted to the electromagnet 5 while the spring 6 is compressed. Then, as shown in FIGS. 2(c) and 2(d), when the cotter 4 is pulled out from the nut 2 and the tip of the cotter 4 reaches the through hole 3A, the output shaft 3 is restrained by the nut 2. be released from

Here, by providing an opening 3C in the output shaft 3 as a housing portion for housing the electromagnet 5, the electromagnet 5 can be housed in the output shaft 3 while suppressing complication of the configuration of the output shaft 3. As a result, attachment of the electromagnet 5 to the actuator EA1 can be facilitated.

Further, by providing a step between the openings 3B and 3C, the spring 6 is housed in the opening 3B, and then the electromagnet 5 is installed on the step between the openings 3B and 3C to provide a gap from the cotter 4. It becomes possible to support the electromagnet 5 within the output shaft 3 by using the As a result, the coupling between the nut 2 and the output shaft 3 can be reversibly released while suppressing the complication of the configuration of the output shaft 3, and the attachment of the spring 6 and the electromagnet 5 to the actuator EA1 is facilitated. be able to.

Fig. 3(a) is a cross-sectional view showing a coupling state between the nut and the output shaft of the actuator according to the second embodiment, cut in the axial direction; It is sectional drawing which cut|disconnects and shows a state in an axial direction.
3(a) and 3(b), the actuator comprises an electromagnet 5' instead of the electromagnet 5 of FIGS. 2(b) and 2(d). The electromagnet 5' has an iron core 5A' in place of the iron core 5A in FIGS. 2(b) and 2(d). The iron core 5A' protrudes from the winding 5B toward the cotter 4 and is extended into the spring 6 to a position where it does not interfere with withdrawal of the cotter 4 from the nut 2. As shown in FIG.

As a result, the attractive force of the electromagnet 5' can be increased without enlarging the actuator, and the efficiency of releasing the connection between the nut 2 and the output shaft 3 can be improved.

FIG. 4 is a cross-sectional view showing a configuration example of an iron core of an electromagnet of an actuator according to the third embodiment, cut in the circumferential direction.
In FIG. 4, this actuator comprises an electromagnet 5'' instead of electromagnet 5 in FIGS. 2(b) and 2(d). The electromagnet 5'' includes an iron core 5A'' instead of the iron core 5A in FIGS. 2(b) and 2(d). In the circumferential direction of the output shaft 3 , the outer peripheral surface of the iron core 5</b>A″ is configured to follow the inner peripheral surface of the bearing 7 . For example, the curvature of the outer peripheral surface of the iron core 5A″ can be made equal to the curvature of the inner peripheral surface of the bearing 7 .

As a result, the contact area between the iron core 5A'' and the bearing 7 can be increased without enlarging the actuator, and the electromagnet 5'' can be prevented from coming off in the circumferential direction when the bearing 7 is mounted. can.

FIG. 5 is a perspective view showing the configuration of an actuator according to the fourth embodiment.
5, this actuator EA2 has a nut 2' and an output shaft 3' instead of the nut 2 and output shaft 3 of FIG. Further, this actuator EA2 has a key 4', an electromagnet 5' and a spring 6' added to the actuator EA1 of FIG.

The nut 2' converts the rotary motion of the screw shaft 1 into the linear motion of the screw shaft 1 in the axial direction. The output shaft 3' outputs axial force based on the linear motion converted by the nut 2'. Here, not only the cotter 4 but also the key 4' is used for connecting the nut 2' and the output shaft 3'. The key 4' can be spaced apart from the cotter 4 in the circumferential direction of the output shaft 3'.

The key 4' is used as a connecting member that connects the output shaft 3 to the nut 2. As shown in FIG. The key 4 ′ penetrates the output shaft 3 in a direction orthogonal to the axial direction of the screw shaft 1 and can be inserted into and removed from the nut 2 . When the key 4 ′ is inserted into the nut 2 , the key 4 ′ is supported by the nut 2 while protruding toward the output shaft 3 . The material of the key 4' is a magnetic material such as iron or ferrite. The key 4 ′ can be used as a detent member for the output shaft 3 with respect to the nut 2 .

At this time, the longitudinal direction of the cotter 4 is set in the circumferential direction of the output shaft 3 , whereas the longitudinal direction of the key 4 ′ can be set in the axial direction of the output shaft 3 . Further, while the recess of the nut 2' in which the tip of the cotter 4 is accommodated is configured to receive the axial force applied to the cotter 4, the recess of the nut 2' in which the tip of the key 4' is accommodated is It is configured to receive a rotational force applied to the key 4'. For example, the recess of the nut 2' in which the tip of the cotter 4 is accommodated may be a groove provided in the nut 2' along the circumferential direction, or the nut 2' in which the tip of the key 4' is accommodated. The recess may be a groove provided in the nut 2' along the axial direction.

In this actuator EA2, similarly to the actuator EA1 in FIG. 1, a rotational force generated from a driving source such as a motor is input to the screw shaft 1 via the gear 13, and the screw shaft 1 is rotated. When the screw shaft 1 rotates, the balls between the screw shaft 1 and the nut 2' circulate through a ball rolling path via a ball circulator (not shown), and the nut 2' linearly moves. An axial force based on the linear motion of the nut 2' is transmitted to the output shaft 3' via the cotter 4' and output via the output shaft 3'.

This actuator EA2 can reversibly release the connection between the nut 2' and the output shaft 3'. Here, the actuator EA2 includes an electromagnet 5' in addition to the electromagnet 5 shown in FIG. 1 as a releasing member capable of reversibly releasing the connection between the nut 2' and the output shaft 3'. The actuator EA2 also includes a spring 6' as an elastic member that holds the key 4' at the joint position between the nut 2' and the output shaft 3'. A spring 6' is provided between the electromagnet 5' and the key 4'. The spring 6' is not particularly limited as long as it is an elastic member such as a spring, a plate spring, or a disc spring that holds down the key 4'. Electromagnet 5' and spring 6' can be housed in output shaft 3'. Here, in order to accommodate the electromagnet 5' and the spring 6' in the output shaft 3', the thickness of the output shaft 3' may be increased at the accommodation position of the electromagnet 5' and the spring 6'. Also, the distance between the electromagnet 5' and the key 4' can be set so that the key 4' can be pulled out from the nut 2' when the spring 6' is compressed.

Here, it is assumed that the movement of the nut 2' is restrained according to the fixed state or load state of the power transmission system such as the motor, gears, or direct acting parts. At this time, when a stuck state or a high load state of the power transmission system is detected and current is applied to the electromagnets 5 and 5', the cotter 4 and the key 4' are pulled out from the nut 2' while the springs 6 and 6' are compressed. The cotter 4 and key 4' can be drawn to each electromagnet 5, 5' to a position where When the cotter 4 and key 4' are withdrawn from the nut 2', the motion of the nut 2' can no longer be transmitted to the output shaft 3' via the cotter 4 and key 4', and the motion of the output shaft 3' is transferred to the nut 2'. can be prevented from being restrained via Therefore, it is possible to prevent the operation of the connection destination of the output shaft 3' from being restrained via the output shaft 3', and to avoid the influence of the stuck state or high load state of the power transmission system. .

Further, by pulling out the cotter 4 and the key 4' from the nut 2' based on the electromagnetic force of the electromagnets 5 and 5', the connection between the nut 2' and the output shaft 3' can be released. Therefore, it is not necessary to destroy the nut 2 or the cotter 4 and the key 4' in order to release the connection between the nut 2' and the output shaft 3', thereby reducing the maintainability of the actuator EA2. can be suppressed.

Also, by cutting off the current flowing through the electromagnets 5 and 5', the connection between the nut 2' and the output shaft 3' can be restored. Therefore, even when the coupling between the nut 2' and the output shaft 3' is released, the actuator EA2 can be restored to normal operation without replacing the nut 2', the cotter 4 and the key 4'.

Furthermore, by using the cotter 4 and the key 4' for connecting the nut 2' and the output shaft 3', the nut 2' and the output shaft 3' can be connected and The connection between the nut 2' and the output shaft 3' can be released, and in order to release the connection between the nut 2' and the output shaft 3', it is necessary to use a complicated structure such as a gripping mechanism or a clutch mechanism. disappears. Therefore, the nut 2' and the output shaft 3' can be coupled while suppressing an increase in the size and cost of the actuator EA2.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

For example, in the above-described embodiments, an example was shown in which a spring was used to hold down the cotter or key when the nut and the output shaft were coupled. . For example, the cotter or key may consist of permanent magnets (eg, neodymium magnets), or permanent magnets may be embedded or attached to the surface of the cotter or key. When the nut and the output shaft are coupled, a repulsive force acts between the electromagnet and the permanent magnet to hold the cotter or key inside the nut, and when the nut and the output shaft are released, the electromagnet The cotter or key may be withdrawn from the nut by exerting an attractive force between the nut and the permanent magnet.

FIG. 6(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the fifth embodiment, and FIG. 6(b) is an enlarged view of the cotter portion of FIG. 6(a). 7A is a cross-sectional view showing the configuration of the actuator when the coupling between the nut and the output shaft according to the fifth embodiment is released; FIG. 7B is the cotter of FIG. 3 is a cross-sectional view showing an enlarged portion of .

In FIGS. 6(a), 6(b), 7(a) and 7(b), actuator EA3 replaces output shaft 3, cotter 4, electromagnet 5 and spring 6 of actuator EA1 of FIG. , an output shaft 13, a cotter 4A and a motor 21.

The output shaft 13 outputs axial force based on the linear motion converted by the nut 2 . The output shaft 13 has a through hole 13A and openings 13C and 13D. Through hole 13A and openings 13C and 13D can be provided on the side surface of output shaft 13 . At this time, the tip of the cotter 4A can be accommodated in the recess 2A via the through hole 13A and the openings 13C and 13D. The through hole 13A accommodates the rear end of the cotter 4A. The opening 13</b>C accommodates the motor 21 with a gap from the cotter 4</b>A in the radial direction of the output shaft 13 . The opening 13D accommodates the bearing 7 so as to cover the motor 21 .

The cotter 4</b>A is used as a connecting member that connects the output shaft 13 to the nut 2 . The cotter 4A penetrates the output shaft 13 in a direction perpendicular to the axial direction of the screw shaft 1 and can be inserted into and pulled out of the nut 2 . The cotter 4A has an opening KA formed in the radial direction of the output shaft 13 . The opening KA may be a through hole penetrating the output shaft 13 in the radial direction. The opening KA has a female thread that can mesh with a male thread formed on the outer peripheral surface of the rotation shaft JA of the motor 21 .

Actuator EA3 can reversibly release the connection between nut 2 and output shaft 13 . Here, the actuator EA3 includes a motor 21 as a releasing member capable of reversibly releasing the connection between the nut 2 and the output shaft 13. As shown in FIG. The motor 21 can insert the cotter 4A into the recess 2A and pull it out from the recess 2A. The motor 21 has a rotating shaft JA with a male thread. The rotating shaft JA of the motor 21 is inserted into the opening KA of the cotter 4A. At this time, the male thread of the rotary shaft JA and the female thread of the opening KA are meshed, and the rotary motion of the rotary shaft JA is converted into the linear motion of the cotter 4A.

Here, the motor 21 switches the rotation direction of the rotary shaft JA to insert the cotter 4A into the recess 2A as shown in FIGS. As shown in FIG. 7B, the cotter 4A can be pulled out from the recess 2A. Therefore, by switching the rotation direction of the rotating shaft JA, the nut 2 and the output shaft 13 can be coupled or the coupling between the nut 2 and the output shaft 13 can be released. As a result, it is no longer necessary to destroy the nut 2 or the cotter 4A in order to release the connection between the nut 2 and the output shaft 13. Actuator EA3 can be restored to normal operation. In addition, by securing a space for installing the motor 21 on the output shaft 13, the connection between the nut 2 and the output shaft 13 can be released, and the complication and increase in size of the actuator EA3 can be suppressed. It is possible to avoid the influence of the fixed state of the transmission system.

FIG. 8(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the sixth embodiment, and FIG. 8(b) is an enlarged view of the cotter portion of FIG. 8(a). Fig. 9(a) is a sectional view showing the configuration of the actuator when the coupling between the nut and the output shaft is released according to the sixth embodiment; Fig. 9(b) is the cotter of Fig. 9(a) 3 is a cross-sectional view showing an enlarged portion of .

8(a), 8(b), 9(a) and 9(b), the actuator EA4 replaces the output shaft 3, the cotter 4, the electromagnet 5 and the spring 6 of the actuator EA1 of FIG. , an output shaft 23, a cotter 4B and an actuator 31.

The output shaft 23 outputs axial force based on the linear motion converted by the nut 2 . The output shaft 23 has a through hole 23A and openings 23C and 23D. Through hole 23A and openings 23C and 23D can be provided on the side surface of output shaft 23 . At this time, the tip of the cotter 4B can be accommodated in the recess 2A via the through hole 23A and the openings 23C and 23D. The through hole 23A accommodates the rear end portion of the cotter 4B. The opening 23</b>C accommodates the actuator 31 with a gap from the cotter 4</b>B in the radial direction of the output shaft 23 . The opening 23</b>D accommodates the bearing 7 so as to cover the actuator 31 .

The cotter 4</b>B is used as a connecting member that connects the output shaft 23 to the nut 2 . The cotter 4B can penetrate the output shaft 23 in a direction perpendicular to the axial direction of the screw shaft 1 and can be inserted into and pulled out of the nut 2 .

Actuator EA4 can reversibly release the connection between nut 2 and output shaft 23 . Here, the actuator EA4 includes an actuator 31 as a releasing member capable of reversibly releasing the connection between the nut 2 and the output shaft 23. As shown in FIG. The actuator 31 has an output shaft JB. An output shaft JB of the actuator 31 is coupled to the cotter 4B. The actuator 31 can linearly move the output shaft JB in the radial direction of the output shaft 23 to insert the cotter 4B into the recess 2A or pull it out from the recess 2A. The actuator 31 may be a hydraulic actuator, a pneumatic actuator, or an electric actuator.

Here, by advancing the output shaft JB, the actuator 31 inserts the cotter 4B into the recess 2A and retreats the output shaft JB as shown in FIGS. 8(a) and 8(b). , as shown in FIGS. 9A and 9B, the cotter 4B can be pulled out from the recess 2A. Therefore, by switching the traveling direction of the output shaft JB, the nut 2 and the output shaft 23 can be coupled or the coupling between the nut 2 and the output shaft 23 can be released. As a result, there is no need to break the nut 2 or the cotter 4B in order to release the connection between the nut 2 and the output shaft 23. Actuator EA4 can be restored to normal operation. In addition, by securing a space for installing the actuator 31 on the output shaft 23, the connection between the nut 2 and the output shaft 23 can be released. It is possible to avoid the influence of the fixed state of the transmission system.

In the actuators EA1 to EA4 described above, the cotter can be used as an axial force transmission element, and the key can be used as a rotational force transmission element, as disclosed in Japanese Patent Application Laid-Open No. 2012-42050. At this time, both axial end faces of the cotter may be in contact with the nut and the output shaft, and the circumferential end faces of the cotter may have a circumferential gap between the nut and the output shaft. Also, both circumferential end faces of the key may be in contact with the nut and the output shaft, and both axial end faces of the key may have an axial clearance between the nut and the output shaft.

Accordingly, even when prying acts on the output shaft, the action can be absorbed by the circumferential clearance and the axial clearance, and prying can be prevented from acting on the ball screw. Therefore, even if misalignment occurs during assembly of the linear motion device and the output shaft, the life of the actuator using the linear motion device can be increased.

FIG. 10(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the seventh embodiment, and FIGS. 10(b) to 10(d) are the nut of FIG. Fig. 10 is an enlarged cross-sectional view showing the movement of the cotter when the coupling between the and the output shaft is released;

10(a) and 10(b) to 10(d), the actuator EA5 has a nut 42 instead of the nut 2, the output shaft 3, the cotter 4, the electromagnet 5 and the spring 6 of the actuator EA1 of FIG. , an output shaft 43 and a cotter 4C.

The nut 42 converts rotary motion of the screw shaft 1 into axial linear motion of the screw shaft 1 . The nut 42 has a recess 42A instead of the recess 2A in FIG. 2(b). The recessed portion 42A moves in the axial direction of the screw shaft 1 from the state accommodated in the recessed portion 42A of the nut 42 based on the force applied to the cotter 4C in the axial direction of the screw shaft 1. It is set in a shape that allows it to escape. At this time, when a force is applied to the cotter 4C in the axial direction of the output shaft 43, the force is also applied to the output shaft 43 in the radial direction. can be provided. Also, the shape of the recess 42A is set so as to correspond to the shape of the tip of the cotter 4C. For example, when the shape of the tip of the cotter 4C is conical, the recess 42A can be shaped like a mortar.

The output shaft 43 outputs axial force based on the linear motion converted by the nut 42 . The output shaft 43 has a through hole 43A and an opening 23D. The through hole 43A and the opening 23D can be provided on the side surface of the output shaft 43. As shown in FIG. At this time, the tip of the cotter 4C can be accommodated in the recess 42A via the through hole 43A and the opening 23D. The through hole 43A accommodates the rear end portion of the cotter 4C. At this time, the height of the through hole 43A is set so that a space 43C is formed on the rear end side of the cotter 4C when the cotter 4C is accommodated in the recess 42A. The height of the space 43C can be set to a height necessary for the cotter 4C to escape from the recess 42A. The opening 23D accommodates the bearing 7 so that the bearing 7 is positioned above the space 43C.

The cotter 4</b>C is used as a connecting member that connects the output shaft 43 to the nut 42 . The cotter 4</b>C penetrates the output shaft 43 in a direction orthogonal to the axial direction of the screw shaft 1 and can be inserted into and removed from the nut 42 . Based on the force applied to the cotter 4C in the axial direction of the screw shaft 1, the cotter 4C moves in the axial direction of the screw shaft 1 from the state accommodated in the recess 42A of the nut 42, and moves out of the recess 42A of the nut 42. It is set in a shape that allows it to escape. At this time, when a force is applied to the cotter 4C in the axial direction of the output shaft 43, the force is also applied to the output shaft 43 in the radial direction. be prepared. For example, the shape of the cotter 4C can have a shape that narrows in the direction toward the tip, and the concave portion 42A can have a shape corresponding to the shape of the cotter 4C. At this time, the inclined surface MC of the cotter 4C can come into contact with the inclined surface MA of the recess 42A.

Actuator EA5 can reversibly release the connection between nut 42 and output shaft 43 . Here, the actuator EA5 is provided with a pressure medium PB that can be sealed in the space 43C in order to couple the nut 42 and the output shaft 43 together. The pressure medium PB may be a liquid such as oil, or a gas such as air. Actuator EA5 can release pressure medium PB in order to release the connection between nut 42 and output shaft 43 . The actuator EA5 has a pipe 52 and a control valve 53 as a releasing portion for releasing the pressure medium PB. The pipe 52 is connected to the space 51 and drawn out of the output shaft 43 . The control valve 53 closes or opens the passage of the pipe 52 .

Here, as shown in FIG. 10(b), after the control valve 53 opens the passage of the pipe 52 and introduces the pressure medium PB into the space 43C, the control valve 53 closes the passage of the pipe 52 so that the pressure medium The PB can be enclosed within space 43C. At this time, the pressure medium PB presses the cotter 4C to accommodate the tip of the cotter 4C in the recess 42A, thereby coupling the nut 42 and the output shaft 43 together.

Then, it is assumed that the power transmission system is stuck and the actuator EA5 is always in a stretched state. At this time, the pressure medium PB sealed in the space 43C is released by opening the passage of the pipe 52 by the control valve 53, and the pressing force applied to the rear end portion of the cotter 4C is reduced. As shown in FIGS. 10(c) and 10(d), when a force is applied to the cotter 4C in the axial direction of the output shaft 43, the force is applied in the radial direction of the output shaft 43 via the inclined surfaces MA and MC. It takes a lot of force. Therefore, the cotter 4C can be pulled out of the recess 42A as the cotter 4C moves in the axial direction of the output shaft 43, and the connection between the nut 42 and the output shaft 43 can be released. As a result, it is no longer necessary to destroy the nut 42 or the cotter 4C in order to release the connection between the nut 42 and the output shaft 43. Actuator EA5 can be restored to normal operation. In addition, by securing the space 43B necessary for the cotter 4C to escape from the recess 42A in the output shaft 43, the connection between the nut 42 and the output shaft 43 can be released, which complicates the structure of the actuator EA5 and It is possible to avoid the influence of the stuck state of the power transmission system while suppressing an increase in size.

11(a) is a perspective view showing an example of the configuration of the cotter in FIG. 10(a), and FIG. 11(b) is a perspective view showing another example of the configuration of the cotter in FIG. 10(a).
In FIG. 11(a), the cotter 4D has an inclined surface MD. The inclined surface MD can apply force to the cotter 4D in the radial direction of the output shaft 43 when the force is applied to the cotter 4D in the axial direction of the output shaft 43 . At this time, the shape of the tip of the cotter 4D can be wedge-shaped.

As a result, when a force is applied to the cotter 4D in the axial direction of the output shaft 43, the force can be applied in the radial direction of the output shaft 43, and the nut 42 and the output shaft 43 are connected. can be released, and the connection between the nut 42 and the output shaft 43 can be released by a simple process of providing the inclined surface MC on the cotter 4D, and the complication of the configuration of the actuator EA5 can be reduced. It is possible to suppress the increase in size and cost of the actuator EA5.

In FIG. 11(b), the cotter 4E has an inclined surface ME. The inclined surface ME can apply force to the cotter 4E in the radial direction of the output shaft 43 when the force is applied to the cotter 4E in the axial direction of the output shaft 43 . At this time, the shape of the tip of the cotter 4E can be rotationally symmetrical about the radial axis of the output shaft 43, and can be, for example, conical.

As a result, when a force is applied to the cotter 4E in the axial direction of the output shaft 43, it is possible to apply a force in the radial direction of the output shaft 43, thereby coupling the nut 42 and the output shaft 43 together. can be released, the slanted surface ME can be provided on the cotter 4E by simple processing, the complication of the configuration of the actuator EA5 can be suppressed, and the increase in size and cost of the actuator EA5 can be suppressed. can.

FIG. 12 is a side view showing an example of a gap between a cotter and a nut according to the eighth embodiment;
In FIG. 12, the actuator EA6 has a cotter 4F instead of the cotter 4C of the actuator EA5 in FIG. 10(a). A step HC is provided on the rear end side of the cotter 4F. Further, the through hole 43A of the output shaft 43 is provided with a step DA capable of receiving the step HC. Then, the cotter 4F can be configured so that there is a gap Cc between the inclined surface MC of the cotter 4F and the inclined surface MA of the recess 42A when the steps HC and DA contact each other.

As a result, even if the output shaft 43 is pryed, the action can be absorbed by the clearance Cc between the inclined surfaces MA and MC, and prying can be prevented from acting on the ball screw. Therefore, even if misalignment occurs during assembly of the linear motion device and the output shaft 43, the life of the actuator EA6 using the linear motion device can be extended.

FIG. 13 is a side view showing an example of the gap between the cotter and the output shaft according to the ninth embodiment.
13(a) and 13(b), the actuator EA7 has a cotter 4G instead of the cotter 4C of the actuator EA5 in FIG. 10(a). A step HC is provided on the rear end side of the cotter 4G. Further, the through hole 43A of the output shaft 43 is provided with a step DA capable of receiving the step HC. Then, the cotter 4G can be configured so that there is a gap Cd between the steps HC and DA when the slanted surface MC of the cotter 4G and the slanted surface MA of the recess 42A are in contact with each other.

As a result, even if prying acts on the output shaft 43, the action can be absorbed by the clearance Cd between the steps HC and DA, and prying can hardly act on the ball screw. Therefore, even if misalignment occurs during assembly of the linear motion device and the output shaft 43, the life of the actuator EA7 using the linear motion device can be increased.

FIG. 14(a) is a cross-sectional view showing the configuration of the actuator when the nut and the output shaft are coupled according to the tenth embodiment, and FIGS. Fig. 10 is an enlarged cross-sectional view showing the movement of the cotter when the coupling between the and the output shaft is released;
14(a) and 14(b) to 14(d), the actuator EA8 comprises an output shaft 63 and a spring 61 instead of the output shaft 43 and pressure medium PB of the actuator EA5 of FIG.

The output shaft 63 outputs axial force based on the linear motion converted by the nut 4 . The output shaft 63 has a through hole 63A. 63 A of through-holes can be provided in the side surface of the output shaft 63. As shown in FIG. At this time, the tip of the cotter 4C can be accommodated in the recess 42A through the through hole 63A. The through hole 63A accommodates the rear end portion of the cotter 4C. At this time, the height of the through hole 63A is set so that a space 63C is formed on the rear end side of the cotter 4C when the cotter 4C is housed in the recess 42A. The height of the space 63C can be set to a height necessary for the cotter 4C to escape from the recess 42A.

Actuator EA8 can reversibly release the connection between nut 42 and output shaft 63 . Here, the actuator EA8 has a spring 61 that presses the cotter 4C in order to couple the nut 42 and the output shaft 63 together.
As shown in FIG. 14(b), the spring 61 is installed in the space 63C and can be arranged so as to be in contact with the rear end surface of the cotter 4C. At this time, the compression force of the spring 61 can be set so that the contact state between the contact surface MA of the nut 42 and the contact surface MC of the cotter 4C is maintained during normal operation of the actuator EA8. Further, the spring 61 can be configured to be able to further contract from the contracted pressure state when the nut 42 and the output shaft 63 are coupled until the cotter 4C is completely removed from the recess 42A.

Then, it is assumed that the power transmission system is stuck and the actuator EA8 is always in a state of being stretched. At this time, as shown in FIGS. 14(c) and 14(d), when a force is applied to the cotter 4C in the axial direction of the output shaft 63, the force is applied in the radial direction of the output shaft 63 via the inclined surfaces MA and MC. also requires force. Therefore, the cotter 4C can be pulled out of the recess 42A as the cotter 4C moves in the axial direction of the output shaft 63, and the connection between the nut 42 and the output shaft 63 can be released. Therefore, there is no need to destroy the nut 42 or the cotter 4C in order to release the connection between the nut 42 and the output shaft 63. After the fixed state of the power transmission system is resolved, the actuator EA8 can be replaced without replacement. Actuator EA8 can be restored to normal operation. In addition, in order to release the connection between the nut 42 and the output shaft 63, a detector that detects the fixed state of the power transmission system, a power unit that supplies power from the outside, and power based on the detection result of the fixed state. There is no need to provide a control unit for control, and it is possible to avoid the effects of sticking of the power transmission system, etc., while suppressing the complication of the configuration of the actuator EA8. Furthermore, by securing the space 63C necessary for the cotter 4C to escape from the recess 42A in the output shaft 63, the connection between the nut 42 and the output shaft 63 can be released, which complicates the configuration of the actuator EA8 and It is possible to avoid the influence of the stuck state of the power transmission system while suppressing an increase in size.

1 screw shaft 2 nut 3 output shaft 4 cotter 5 electromagnet 5A iron core 5B winding 6 spring 7, 11 bearing 12 housing 13 gear 14 gear fixing nut

Claims (21)

a screw shaft;
a nut that converts rotational motion of the screw shaft into axial linear motion of the screw shaft;
a connecting member that connects an output shaft that outputs an axial force based on the linear motion converted by the nut to the nut;
A linear motion device, comprising: a release member capable of releasing coupling between the nut and the output shaft. 2. The linear motion device according to claim 1, wherein the release member can reversibly release the connection between the nut and the output shaft. 3. The linear motion device according to claim 1, wherein the coupling member penetrates the output shaft in a direction perpendicular to the axial direction of the screw shaft and can be inserted into and removed from the nut. The linear motion device according to any one of claims 1 to 3, wherein the release member is capable of restoring the coupling after releasing the coupling. The linear motion device according to any one of claims 1 to 4, wherein the coupling member is a cotter or a key. the cotter has a circumferential clearance in the circumferential direction of the output shaft with respect to the nut and the output shaft;
6. The linear motion device according to claim 5, wherein the key has an axial clearance in the axial direction of the output shaft with respect to the nut and the output shaft. The linear motion device according to any one of claims 1 to 6, wherein the release member is an electromagnet capable of pulling out the coupling member from the nut. 8. The linear motion device according to claim 7, further comprising an elastic member provided between the electromagnet and the coupling member and holding the coupling member at a coupling position between the nut and the output shaft. The electromagnet is
a winding;
An iron core around which the winding is wound,
9. A linear motion device according to claim 8, wherein said iron core extends into said elastic member to a position where it does not hinder extraction of said connecting member from said nut. the releasing member comprises a motor having a rotating shaft with a male thread;
The rotating shaft is arranged along a direction perpendicular to the axial direction of the screw shaft,
The linear motion device according to any one of claims 1 to 6, wherein the coupling member has an opening formed with a female thread that can be engaged with the male thread. The linear motion device according to any one of claims 1 to 6, wherein the release member is an actuator capable of pulling out the coupling member from the nut. a screw shaft;
a nut that converts rotational motion of the screw shaft into axial linear motion of the screw shaft;
a connecting member that connects an output shaft that outputs an axial force based on the linear motion converted by the nut to the nut;
a pressing portion capable of reversibly pressing the coupling member in a direction in which the coupling member is accommodated in the recess of the nut;
The coupling member moves in the axial direction of the screw shaft from the state accommodated in the recess of the nut based on the force applied in the axial direction of the screw shaft so that it can escape from the recess of the nut. A linear motion device, wherein the shapes of the coupling member and the recess are set. 13. The linear motion device according to claim 12, wherein the coupling member has a shape that narrows toward the tip, and the recess has a shape corresponding to the shape of the coupling member. 14. A linear motion device according to claim 13, wherein the shape of the tip of said connecting member is wedge-shaped. The linear motion device according to any one of claims 11 to 14, wherein shapes of the coupling member and the recess are rotationally symmetrical about a radial axis of the output shaft. The pressing part is
a pressure medium that can be sealed in a space provided on the rear end side of the coupling member;
16. The linear motion device according to any one of claims 11 to 15, further comprising a releasing portion for releasing said pressure medium sealed in said space. The linear motion device according to any one of claims 11 to 15, wherein the pressing portion is a spring provided on the rear end side of the coupling member. The linear motion device according to any one of claims 12 to 17, wherein the coupling member has a gap in a radial direction of the output shaft with respect to at least one of the nut and the output shaft. . A linear motion device according to any one of claims 1 to 18;
An actuator comprising the output shaft. 20. The actuator according to claim 19, wherein the output shaft has a storage portion that stores the release member at a position where the coupling can be released. 21. An actuator according to claim 20, wherein said storage portion is an opening provided in said output shaft.

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