JP7707786B2 - Linear motion devices and actuators - Google Patents

Description

The present invention relates to a linear motion device and an actuator.

As an actuator that obtains axial force from input torque, there is a technology that uses a ball screw to convert rotational motion into linear motion. In this actuator, the rotational motion of the screw shaft is converted into linear motion of a nut, and the axial force is extracted from an output shaft connected to the nut. Patent Document 1 discloses a technology that uses a cotter to connect the nut and output shaft of the actuator.

JP 2012-42050 A

In an actuator that uses a cotter to connect a nut and an output shaft, if the power transmission system becomes stuck, it may be desirable to release the connection between the actuator and the output shaft to avoid the effects of the sticking.
Therefore, an object of one aspect of the present invention is to provide a linear motion device and an actuator that are capable of releasing the connection with an output shaft.

In order to solve the above problems, a linear motion device according to one aspect of the present invention includes a screw shaft, a nut that converts the rotational motion of the screw shaft into linear motion in the axial direction of the screw shaft, a coupling member that couples the nut to an output shaft that outputs an axial force based on the linear motion converted by the nut, and a support member that supports the coupling member so that the axial force can be transmitted from the nut to the output shaft while allowing the coupling between the nut and the output shaft to be released.

As a result, even if the movement of the nut is restricted due to a stuck state or a loaded state of the power transmission system, the movement of the output shaft can be prevented from being restricted via the nut without providing a complex mechanism for releasing the connection between the nut and the output shaft. This makes it possible to prevent the movement of the output destination of the axial force from the output shaft from being restricted via the output shaft while suppressing the increase in size and cost of the actuator, and to avoid the effects of a stuck state or a high load state of the power transmission system.

In addition, according to a linear motion device according to one aspect of the present invention, the support member releases the connection between the nut and the output shaft based on the load applied to the connecting member.

This allows the connection between the nut and the output shaft to be released without the need for a sensor to detect the stuck state or load state of the power transmission system, and prevents the movement of the output shaft from being restricted via the nut without the need for a complex mechanism for releasing the connection between the nut and the output shaft.

In addition, according to a linear motion device according to one aspect of the present invention, the support member can be broken or detached based on the load applied to the connecting member.

This allows the support member itself to have the function of releasing the connection between the nut and the output shaft. This eliminates the need to provide a part that releases the connection between the nut and the output shaft separately from the part that supports the connection member, making it possible to prevent the actuator from becoming larger and more expensive while preventing the operation of the output destination of the axial force from being restricted via the output shaft.

In addition, according to one aspect of the linear motion device of the present invention, the support member can release the connection in both the forward and backward directions of the output shaft.

This makes it possible to prevent the movement of the destination of the axial force from being restricted via the output shaft, regardless of whether the output shaft is moving forward or backward.

In addition, according to a linear motion device according to one aspect of the present invention, the coupling member can be inserted into the support member by penetrating the output shaft in a direction perpendicular to the axial direction of the screw shaft.

As a result, the nut and output shaft can be connected by simply inserting the connecting member itself, eliminating the need to use complex configurations such as a gripping mechanism or clutch mechanism to connect the nut and output shaft. This makes it possible to connect the nut and output shaft while preventing the actuator from becoming larger and more expensive.

In addition, according to a linear motion device according to one aspect of the present invention, the support member is provided on the nut.

This allows the nut to have the function of releasing the connection between the nut and the output shaft. This eliminates the need to provide a component for releasing the connection between the nut and the output shaft separately from the nut, and prevents the actuator from becoming larger and more expensive, while preventing the operation of the destination of the axial force from being restricted via the output shaft.

In addition, according to one aspect of the present invention, the linear motion device includes an intermediate member that mediates the connection between the nut and the output shaft, and the connection member includes a first connection member that connects the nut and the intermediate member and a second connection member that connects the intermediate member and the output shaft, and the support member is provided on the intermediate member.

This allows the joining position of the nut and intermediate member and the joining position of the intermediate member and the output shaft to be set separately in order to join the nut and the output shaft. This improves the degree of freedom in designing the position, size, shape, etc. of the nut and output shaft, and allows the nut or output shaft to be made smaller, lighter, less expensive, easier to process, and easier to assemble.

In addition, according to a linear motion device according to one aspect of the present invention, the intermediate member extends from the nut in the axial direction of the output shaft, and the axial position of the second connecting member is shifted closer to the output shaft than the axial position of the first connecting member.

This allows the nut and output shaft to be connected without extending the output shaft to the position of the first connecting member. This makes it possible to shorten the output shaft without reducing the axial stroke of the actuator, and eliminates the need to provide a through hole in the output shaft for inserting the first connecting member, making the output shaft smaller, lighter, less expensive, easier to process, more durable, and easier to assemble.

In addition, according to a linear motion device according to one aspect of the present invention, the strength of the support member is set based on the load required to release the connection.

As a result, compared to when the connection between the nut and the output shaft cannot be released, it is possible to release the connection between the nut and the output shaft by reducing the thickness of the support member or by changing the material of the support member. Therefore, even when the power transmission system becomes stuck, it is possible to prevent the actuator from becoming larger and more expensive, while preventing the operation of the output destination of the axial force from being restricted via the output shaft.

In addition, according to a linear motion device according to one aspect of the present invention, the support member is an elastic member that clamps the connecting member so that the connecting member is supported between the nut and the output shaft.

This eliminates the need to drive the coupling member into the nut in order to secure the coupling member to the nut via the output shaft. This makes it possible to prevent the nut from being damaged when the coupling member is secured to the nut, and also makes it easier to remove the coupling member from the nut, facilitating the disconnection of the nut from the output shaft.

In addition, a linear motion device according to one aspect of the present invention includes a screw shaft, a nut that converts the rotational motion of the screw shaft into linear motion in the axial direction of the screw shaft, a coupling member that couples the nut to an output shaft that outputs an axial force based on the linear motion converted by the nut, and an intermediate member that mediates the coupling between the nut and the output shaft, the coupling member comprising a first coupling member that couples the nut to the intermediate member and a second coupling member that couples the intermediate member to the output shaft.

This allows the nut's connecting position and the output shaft's connecting position to be set separately in order to connect the nut and the output shaft, improving the design freedom of the nut's and the output shaft's positions, sizes, shapes, etc.

In addition, according to a linear motion device according to one aspect of the present invention, the first coupling member can be inserted into the nut by penetrating the intermediate member in a direction perpendicular to the axial direction of the screw shaft, and the second coupling member can be inserted into the intermediate member by penetrating the output shaft in a direction perpendicular to the axial direction of the screw shaft.

As a result, the nut and intermediate member can be joined by inserting the first joining member, and the output shaft and intermediate member can be joined by inserting the second joining member. This allows the nut and output shaft to be joined while the joining position of the nut and the joining position of the output shaft are set separately, which increases the design freedom of the position, size, and shape of the nut and output shaft while preventing the actuator from becoming larger and more expensive.

In addition, a linear motion device according to one aspect of the present invention includes a screw shaft, a nut that converts the rotational motion of the screw shaft into linear motion in the axial direction of the screw shaft, a coupling member that couples the nut to an output shaft that outputs an axial force based on the linear motion converted by the nut, and an elastic member that clamps the coupling member so that the coupling member is supported by the nut.

This eliminates the need to drive the coupling member into the nut to secure the coupling member to the nut via the output shaft, making it possible to prevent the nut from being damaged when the coupling member is secured to the nut. It also makes it easier to remove the coupling member from the nut, making it easy to replace the coupling member and release the coupling between the nut and the output shaft.

In addition, according to a linear motion device according to one aspect of the present invention, the elastic member is a spring that can clamp the connecting member from both sides when fitted into the nut.

As a result, by fitting the spring into the nut while the connecting member is inserted into the nut, it is possible to prevent the connecting member from falling off the nut and also to make it easier to remove the connecting member from the nut.

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

This makes it possible to provide an actuator that can release the connection between the nut and the output shaft.

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

FIG. 1(a) is an exploded perspective view showing the configuration of the actuator before the cotter and key according to the first embodiment are attached, and FIG. 1(b) is an exploded perspective view showing the configuration of the actuator after the cotter and key according to the first embodiment are attached. FIG. 2(a) is a side view showing the configuration of the actuator according to the first embodiment as viewed from the cotter side, and FIG. 2(b) is a cross-sectional view showing the configuration of the actuator taken along line A-A in FIG. 2(a). FIG. 3 is a cross-sectional view showing an example of application of the actuator of FIG. 2(a) to a railway vehicle. FIG. 4(a) is an exploded perspective view showing the configuration of the actuator before the cotter, the key, and the intermediate member according to the second embodiment are attached, and FIG. 4(b) is an exploded perspective view showing the configuration of the actuator after the cotter, the key, and the intermediate member according to the second embodiment are attached. 5(a) and 5(b) are cross-sectional views showing a transmission path of an axial force of an actuator according to the second embodiment. Figure 6(a) is a cross-sectional view showing the transmission path of an external force when the output shaft of the actuator of the second embodiment is moved backward, Figure 6(b) is a cross-sectional view showing the broken state of a support member due to the external force of Figure 6(a), Figure 6(c) is a cross-sectional view showing the transmission path of an external force when the output shaft of the actuator of the second embodiment is moved forward, and Figure 6(d) is a cross-sectional view showing the broken state of a support member due to the external force of Figure 6(c). FIG. 7 is an exploded perspective view showing the configuration of the actuator after the cotter, the key, and the intermediate member according to the third embodiment are attached. FIG. 8(a) is a cross-sectional view showing the configuration of the nut portion of the linear motion device of the third embodiment, FIG. 8(b) is a plan view showing the configuration of the nut portion of FIG. 8(a), and FIGS. 8(c) and 8(d) are plan views showing the state when the spring of FIG. 8(b) is detached. 9A and 9B are cross-sectional views showing the configuration of an actuator according to a fourth embodiment. FIG. 10(a) is an exploded perspective view showing the configuration of the actuator before the cotter, key, and intermediate member according to the fifth embodiment are attached, and FIG. 10(b) is an exploded perspective view showing the configuration of the actuator after the cotter, key, and intermediate member according to the fifth embodiment are attached. FIG. 11 is an exploded perspective view showing the configuration of the actuator according to the sixth embodiment.

Below, the embodiments of the present invention will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (conditions of use, environment of use, etc.). The technical scope of the present invention is determined by the claims, and is not limited by the individual embodiments below. Also, the drawings used in the following description may differ in scale and shape from the actual structure in order to make each configuration easier to understand.

Figure 1(a) is an exploded perspective view showing the configuration of the actuator according to the first embodiment before the cotter and key are attached, Figure 1(b) is an exploded perspective view showing the configuration of the actuator according to the first embodiment after the cotter and key are attached, Figure 2(a) is a side view showing the configuration of the actuator according to the first embodiment as seen from the cotter side, and Figure 2(b) is a cross-sectional view showing the configuration of the actuator cut along line A-A in Figure 2(a).

1(a), 1(b), 2(a) and 2(b), the actuator EA1 outputs an axial force in the axial direction based on a rotational motion. The actuator EA1 includes a screw shaft 1, a nut 2, an output shaft 3, a cotter 4, a key 4' and a ball circulator 6. The screw shaft 1 and the nut 2 can be used as a ball screw constituting a linear motion device. The screw shaft 1 performs a rotational motion based on a rotational force generated from a driving source such as a motor. The nut 2 converts the rotational motion of the screw shaft 1 into a linear motion in the axial direction of the screw shaft 1. The output shaft 3 outputs an axial force based on the linear motion converted by the nut 2. The shape of the output shaft 3 is, for example, cylindrical. In this case, 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 and the key 4' are used as connecting members for connecting the output shaft 3 to the nut 2. The cotter 4 and the key 4' can be inserted into the nut 2 by penetrating the output shaft 3 in a direction perpendicular to the axial direction of the screw shaft 1. When the cotter 4 and the key 4' are inserted into the nut 2, they are supported by the nut 2 in a state where they protrude 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 key 4' can be used as a member for preventing the output shaft 3 from rotating relative to the nut 2. The key 4' can be arranged at a distance from the cotter 4 in the circumferential direction of the output shaft 3'. In this case, the longitudinal direction of the cotter 4 can be set in the circumferential direction of the output shaft 3, and the longitudinal direction of the key 4' can be set in the axial direction of the output shaft 3.

The ball circulator 6 circulates multiple balls loaded in a ball rolling path formed between the screw shaft 1 and the nut 2 by returning the balls from the end point of the ball rolling path to the start point. The ball circulator 6 is attached to the nut 2.

The screw shaft 1 has a screw groove 1m. The screw groove 1m is provided in a spiral shape on the outer peripheral surface of the screw shaft 1. The nut 2 has a screw groove 2m. The screw groove 2m is provided in a spiral shape on the inner peripheral surface of the nut 2 so as to face the screw 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.

The nut 2 has a support member 5 and a recess 2A'. The support member 5 has a recess 2A. The output shaft 3 has through holes 3A, 3A'.

The support member 5 supports the cotter 4 so that the nut 2 can be disconnected from the output shaft 3 while transmitting axial force from the nut 2 to the output shaft 3. The support member 5 can disconnect the nut 2 from the output shaft 3 based on the load applied to the cotter 4. At this time, the support member 5 can be broken based on the load applied to the cotter 4. The support member 5 can be provided on the outer peripheral surface of the nut 2.

The recess 2A accommodates the tip of the cotter 4. The tip of the cotter 4 refers to the tip (the portion that fits into the recess 2A of the nut 2) in the insertion direction of the cotter 4 (the radial direction of the nut 2). The planar shape of the recess 2A can correspond to the planar shape of the tip of the cotter 4. In this case, the cotter 4 can be fitted into the recess 2A. To prevent the cotter 4 from slipping out of the recess 2A, static friction may be applied between the cotter 4 and the recess 2A. For example, when fitting the cotter 4 into the recess 2A, the cotter 4 may be driven into the recess 2A.

The recess 2A is configured to receive the axial force applied to the cotter 4. For example, the recess 2A may be a groove provided in the support member 5 along the circumferential direction. At this time, the axial force applied to the cotter 4 can be received by the wall surfaces on both sides of the recess 2A formed in the support member 5. Here, the connection between the nut 2 and the output shaft 3 can be released by setting the strength of the wall surface of the recess 2A so that the wall surface of the recess 2A breaks based on the load applied to the cotter 4. The strength of the wall surface of the recess 2A can be adjusted based on the thickness or material of the wall surface of the recess 2A. At this time, the strength of the wall surface of the recess 2A can be set so that the connection between the nut 2 and the output shaft 3 is not released during normal operation of the actuator EA1, and the connection between the nut 2 and the output shaft 3 is released when a load larger than the normal operation of the actuator EA1 is applied to the cotter 4. In addition, by setting the strength of the wall surfaces on both sides of the recess 2A so that the wall surfaces on both sides of the recess 2A can be broken, the connection between the nut 2 and the output shaft 3 can be released in both the forward and backward directions of the output shaft 3.

The recess 2A' accommodates the tip of the key 4'. The tip of the key 4' refers to the tip (the part that fits into the recess 2A' of the nut 2) in the insertion direction of the key 4' (the radial direction of the nut 2). The recess 2A' can be provided on the outer circumferential surface of the nut 2. The recess 2A' can be arranged at a distance from the recess 2A in the circumferential direction of the nut 2. The planar shape of the recess 2A' can correspond to the planar shape of the tip of the key 4'. In this case, the key 4' can be fitted into the recess 2A'. To prevent the key 4' from slipping out of the recess 2A', static friction may be applied between the key 4' and the recess 2A'. For example, when fitting the key 4' into the recess 2A', the key 4' may be driven into the recess 2A'.

The recess 2A' is configured to receive the rotational force applied to the key 4'. For example, the recess 2A' may be a groove provided in the nut 2 along the axial direction. In this case, the wall surfaces on both sides of the recess 2A' formed in the nut 2 can receive the rotational force applied to the key 4'.

Through hole 3A accommodates the rear end of cotter 4. The rear end of cotter 4 refers to the rear end (the part that fits into through hole 3A of output shaft 3) in the insertion direction of cotter 4 (radial direction of nut 2). Through hole 3A can be provided on the side surface of output shaft 3. In this case, the tip of cotter 4 can be accommodated in recess 2A via through hole 3A.

Through hole 3A' accommodates the rear end of key 4'. The rear end of key 4' refers to the rear end (the part that fits into through hole 3A' of output shaft 3) in the insertion direction of key 4' (radial direction of nut 2). Through hole 3A' can be provided on the side of output shaft 3. Through hole 3A' can be arranged at a distance from through hole 3A in the circumferential direction of output shaft 3'. In this case, the tip of key 4' can be accommodated in recess 2A' via through hole 3A'.

The materials of the screw shaft 1, nut 2, output shaft 3, cotter 4, and key 4' are not particularly limited as long as they are rigid, and may be metals such as iron or aluminum alloys, or non-metals such as ceramics. The cross-sectional shape of each screw groove 1m, 2m may be, for example, a circular arc or a Gothic arc.

The rotational force generated by a drive source such as a motor is input to the screw shaft 1, causing the screw shaft 1 to rotate. When the screw shaft 1 rotates, the balls between the screw shaft 1 and the nut 2 circulate in the ball rolling path via the ball circulator 6, while the nut 2 moves linearly. The axial force based on the linear motion of the nut 2 is then transmitted to the output shaft 3 via the cotter 4, and is output via the output shaft 3.

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

Here, it is assumed that the movement of the nut 2 is restricted depending on the stuck state or load state of the power transmission system, such as the motor, gears, or linear motion parts. If the power transmission system is stuck, power cannot be transmitted from the motor and the reduction gear, and linear output from the output shaft 3 is not possible. Note that the power transmission system may be stuck due to, for example, the threads of the ball screw section sticking, the nut 2 being twisted, the ball circulator 6 becoming clogged, or other parts sticking.

At this time, the load on the cotter 4 increases depending on the stuck or high load state of the power transmission system. When the load on the cotter 4 exceeds a predetermined value, the support member 5 is unable to withstand the load and breaks. When the support member 5 breaks, 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 can be prevented from being restricted via the nut 2. This makes it possible to prevent the operation of the output destination of the axial force from the output shaft 3 from being restricted via the output shaft 3, and makes it possible to avoid the effects of a stuck or high load state of the power transmission system.

The actuator EA1 can reduce vibration and lateral shaking, for example, by being installed between the car body and the bogie of a railway vehicle.
FIG. 3 is a cross-sectional view showing an example of application of the actuator of FIG. 2(a) to a railway vehicle.
In Fig. 3, a car body 62 is supported on a bogie 61 via bolster springs 63. The bogie 61 includes wheels 65 and a bogie frame 69. The car body 62 is mounted on the bogie frame 69 via the bolster springs 63. A pair of wheels 65 are supported so as to face each other via wheel sets 66. An axle box 67 is provided on the outer side of each wheel 65, and an axle spring 68 is provided on the axle box 67. The bogie frame 69 is supported on the wheels 65 via the axle springs 68.

An actuator EA1 is installed between the bogie 61 and the car body 62. At this time, the actuator EA1 can be fixed to the car body 62 via a central pin 70 provided on the bottom surface of the car body 62. The vibration control system measures the vibration and lateral oscillation of the car body 62 with an acceleration sensor while the railway vehicle is running on the rails 64, calculates the vibration control force required to reduce the vibration and lateral oscillation of the car body 62 with a control device, and activates the actuator EA1.

If the power transmission system becomes stuck at this time, the actuator EA1 will always be in a tensioned state, and the vibrations of the bogie 61 will be transmitted directly to the car body 62 via the actuator EA1, reducing the ride quality of the railway vehicle. At this time, the axial force applied to the support member 5 in FIG. 2(b) increases, causing the support member 5 to break, and the connection between the nut 2 and the output shaft 3 will be released. As a result, even if the power transmission system becomes stuck, it is possible to prevent the vibrations of the bogie 61 from being transmitted to the car body 62 via the actuator EA1, improving the ride quality of the railway vehicle.

In addition, because the support member 5 breaks based on the increase in axial force applied to the support member 5 when the power transmission system is stuck, the connection between the nut 2 and the output shaft 3 can be released without the need for a sensor to detect the stuck state of the power transmission system. This makes it possible to prevent the movement of the output shaft 3 from being restricted via the nut 2 without the need for a complex mechanism for releasing the connection between the nut 2 and the output shaft 3.

Also, by providing the support member 5 with the function of releasing the connection between the nut 2 and the output shaft 3, it is not necessary to provide a part for releasing the connection between the nut 2 and the output shaft 3 separately from the support member 5. This makes it possible to prevent the actuator EA1 from becoming larger and more expensive, while preventing the operation of the output destination of the axial force from the output shaft 3 from being restricted via the output shaft 3.

In addition, by using the cotter 4 to connect the nut 2 to the output shaft 3, it is possible to easily connect the nut 2 to the output shaft 3, and the support member 5 can be provided with a function for releasing the connection between the nut 2 and the output shaft 3 based on simple processing of the nut 2. This eliminates the need to use complex configurations such as a gripping mechanism or clutch mechanism to connect or release the connection between the nut 2 and the output shaft 3, thereby preventing the actuator EA1 from becoming larger and more expensive.

Figure 4(a) is an exploded perspective view showing the configuration of the actuator before the cotter, key, and intermediate member according to the second embodiment are attached, and Figure 4(b) is an exploded perspective view showing the configuration of the actuator after the cotter, key, and intermediate member according to the second embodiment are attached.

In Fig. 4(a) and Fig. 4(b), this actuator EA2 includes a screw shaft 11, a nut 12, an output shaft 13, a cotter 14, a key 14', and an intermediate member 17. The screw shaft 11 and the nut 12 can be used as a ball screw constituting a linear motion device. The screw shaft 11 performs rotational motion based on a rotational force generated by a driving source such as a motor. The nut 12 converts the rotational motion of the screw shaft 11 into linear motion in the axial direction of the screw shaft 11. The output shaft 13 outputs an axial force based on the linear motion converted by the nut 12. The intermediate member 17 mediates the connection between the nut 12 and the output shaft 13 while allowing the connection between the nut 12 and the output shaft 13 to be released.

The output shaft 13 and the intermediate member 17 are, for example, cylindrical in shape. The diameter of the intermediate member 17 can be smaller than that of the output shaft 13 so that the intermediate member 17 can be inserted into the output shaft 13 along the axial direction. The diameter of the intermediate member 17 can be larger than that of the nut 12 so that the nut 12 can be inserted into the intermediate member 17 along the axial direction. In this case, the inner peripheral surface of the output shaft 13 can be configured to follow the outer peripheral surface of the intermediate member 17. The inner peripheral surface of the intermediate member 17 can be configured to follow the outer peripheral surface of the nut 12. The nut 12 can be provided between the outer peripheral surface of the screw shaft 11 and the inner peripheral surface of the output shaft 13. The intermediate member 17 can be provided between the outer peripheral surface of the nut 12 and the inner peripheral surface of the output shaft 13.

In the example of FIG. 4, the cotter 14 is used as a first connecting member that connects the nut 12 and the intermediate member 17. The cotter 14 can be inserted into the nut 12 by penetrating the intermediate member 17 in a direction perpendicular to the axial direction of the screw shaft 11. When the cotter 14 is inserted into the nut 12, it is supported by the nut 12 in a state where it protrudes toward the intermediate member 17. The cotter 14 can be used as an axial force transmission member from the nut 12 to the intermediate member 17.

In the example of FIG. 4, the key 14' is used as a second connecting member that connects the intermediate member 17 and the output shaft 13. The key 14' can be inserted into the intermediate member 17 by penetrating the output shaft 13 in a direction perpendicular to the axial direction of the screw shaft 11. When the key 14' is inserted into the intermediate member 17, it is supported by the intermediate member 17 in a state in which it protrudes toward the output shaft 13. The key 14' can be used as an axial force transmission member from the intermediate member 17 to the output shaft 13.

The key 14' can also be inserted into the nut 12 via the intermediate member 17. In this case, the key 14' can also be used as a member for preventing the output shaft 13 from rotating relative to the nut 12. The key 14' can be arranged at a distance from the cotter 14 in the circumferential direction of the output shaft 13'.

The nut 12 has recesses 12A and 12A'. The output shaft 13 has a through hole 13A'. The intermediate member 17 has support members 15A and 15B, a through hole 17A, an insertion portion 17A', and a groove 17B'.

The recess 12A accommodates the tip of the cotter 14. The planar shape of the recess 12A can correspond to the planar shape of the tip of the cotter 14. At this time, the cotter 14 can be fitted into the recess 12A. To prevent the cotter 14 from slipping out of the recess 12A, static friction may be applied between the cotter 14 and the recess 12A.

The recess 12A is configured to receive the axial force applied to the cotter 14. For example, the recess 12A may be a groove provided in the nut 12 along the circumferential direction. In this case, the axial force applied to the cotter 14 can be received by the wall surfaces on both sides of the recess 12A formed in the nut 12.

The through hole 17A accommodates the rear end of the cotter 14. The through hole 17A can be provided on the side of the intermediate member 17. In this case, the tip of the cotter 14 can be accommodated in the recess 12A via the through hole 17A.

The recess 12A' accommodates the tip of the key 14'. The recess 12A' can be provided on the outer peripheral surface of the nut 12. The recess 12A' can be arranged at a distance from the recess 12A in the circumferential direction of the nut 12. The planar shape of the recess 12A' can correspond to the planar shape of the tip of the key 14'. In this case, the key 14' can be fitted into the recess 12A'. To prevent the key 14' from slipping out of the recess 12A', static friction may be applied between the key 14' and the recess 12A'.

The recess 12A' is configured to receive the rotational force applied to the key 14'. For example, the recess 12A' may be a groove provided in the nut 12 along the axial direction. In this case, the wall surfaces on both sides of the recess 12A' formed in the nut 12 can receive the rotational force applied to the key 14'.

The support members 15A and 15B support the key 14' so that the axial force can be transmitted from the intermediate member 17 to the output shaft 13 while allowing the connection between the nut 12 and the output shaft 13 to be released. The support members 15A and 15B can release the connection between the nut 12 and the output shaft 13 based on the load applied to the key 14'. At this time, the support members 15A and 15B can be broken based on the load applied to the key 14'. The support members 15A and 15B can be used as part of the side of the intermediate member 17. The support members 15A and 15B can be arranged at intervals along the axial direction so that the key 14' can be inserted between the support members 15A and 15B.

Here, the connection between the nut 12 and the output shaft 13 can be released by setting the strength of the support members 15A and 15B so that the support members 15A and 15B break based on the load applied to the key 14'. The strength of the support members 15A and 15B can be adjusted based on the thickness or material of the support members 15A and 15B. At this time, the strength of the support members 15A and 15B can be set so that the connection between the nut 12 and the output shaft 13 is not released during normal operation of the actuator, and the connection between the nut 12 and the output shaft 13 is released when a load larger than the normal operation of the actuator EA2 is applied to the key 14'. In addition, by setting the strength of the support members 15A and 15B so that the support members 15A and 15B can be broken, the connection between the nut 12 and the output shaft 13 can be released in both the forward and backward directions of the output shaft 13.

The insertion portion 17A' is provided between the support members 15A and 15B, and allows the key 14' to be inserted. At this time, the tip of the key 14' can be accommodated in the recess 12A' via the insertion portion 17A'. By inserting the key 14' into the insertion portion 17A', the support members 15A and 15B can support the key 14' so that the axial force can be transmitted from the intermediate member 17 to the output shaft 13 while allowing the connection between the nut 12 and the output shaft 13 to be released.

The groove 17B' allows the key 14' to move in the axial direction. The groove 17B' can be arranged in axial continuity with the insertion portion 17A' via the support member 15B. The groove 17B' allows the key 14' to escape in the axial direction when the support member 15B breaks.

The through hole 13A' accommodates the rear end of the key 14'. The through hole 13A' can be provided on the side of the output shaft 13. In this case, the key 14' can be inserted into the insertion portion 17A' through the through hole 13A'.

The materials of the screw shaft 11, nut 12, output shaft 13, cotter 14, key 14' and intermediate member 17 are not particularly limited as long as they are rigid, and may be metals such as iron or aluminum alloys, or non-metals such as ceramics.

By making it possible to connect the nut 12 and the output shaft 13 via the intermediate member 17, the connection position of the nut 12 and the connection position of the output shaft 13 can be set separately. This improves the degree of freedom in designing the positions, sizes, shapes, etc. of the nut 12 and the output shaft 13, and allows the nut 12 or the output shaft 13 to be made smaller, lighter, less expensive, easier to process, or easier to assemble.

Figures 5(a) and 5(b) are cross-sectional views showing the transmission path of the axial force of the actuator according to the second embodiment. Note that Figure 5(a) is a cross-sectional view taken along the axial direction of the actuator at the position of the cotter 14, and Figure 5(b) is a cross-sectional view taken along the axial direction of the actuator at the position of the key 14'.

In Figures 5(a) and 5(b), one end of the screw shaft 11 is connected to a gear G3. The gear G3 is rotatably supported by the housing G2 via a bearing G1, and is fixed in the axial direction by a gear fixing nut G4. The bearing G1 is, for example, an angular ball bearing.

As shown in FIG. 5(a), a rotational force F1 generated by a drive source such as a motor is input to the screw shaft 11, causing the screw shaft 11 to rotate. When the screw shaft 11 rotates, the nut 12 moves linearly. Then, an axial force F2 based on the linear motion of the nut 12 is transmitted to the intermediate member 17 via the cotter 14. When the axial force F2 is transmitted to the intermediate member 17, the axial force F2 is transmitted from the intermediate member 17 to the output shaft 13 as shown in FIG. 5(b), and is output via the output shaft 13.

Figure 6(a) is a cross-sectional view showing the transmission path of an external force when the output shaft of the actuator according to the second embodiment is moved backward, Figure 6(b) is a cross-sectional view showing the broken state of the support member due to the external force of Figure 6(a), Figure 6(c) is a cross-sectional view showing the transmission path of an external force when the output shaft of the actuator according to the second embodiment is moved forward, and Figure 6(d) is a cross-sectional view showing the broken state of the support member due to the external force of Figure 6(c). Note that Figures 6(a) to 6(d) are cross-sectional views taken along the axial direction of the actuator at the position of key 14'.

In FIG. 6(a), the movement of the nut 12 is restricted depending on the stuck or loaded state of the power transmission system such as the motor, gears, or linear motion parts. If the power transmission system is stuck in each part such as the screw of the ball screw part stuck, the nut 12 is twisted, or the ball circulator 6 is clogged, power cannot be transmitted from the motor and the reduction part, and linear output from the output shaft 3 is not possible. At this time, if an external force F11 is applied in the backward direction of the output shaft 13, the external force F11 is applied to the key 14' via the output shaft 13. The external force F11 applied to the key 14' is applied to the support member 15A, and when the load on the key 14' exceeds a predetermined value, the support member 15A cannot withstand the load, and the support member 15A breaks as shown in FIG. 6(b).

In addition, in FIG. 6(c), when an external force F12 is applied in the forward direction of the output shaft 13, the external force F12 is applied to the key 14' via the output shaft 13. The external force F12 applied to the key 14' is applied to the support member 15B, and when the load on the key 14' exceeds a predetermined value, the support member 15B is no longer able to withstand the load, and as shown in FIG. 6(d), the support member 15B breaks.

When the support members 15A and 15B break, the axial force based on the linear motion of the nut 12 cannot be transmitted to the output shaft 13 via the intermediate member 17, and the motion of the output shaft 13 can be prevented from being restricted via the nut 12. At this time, when the support members 15A and 15B break, the restriction of the output shaft 13 caused by the sticking of the power transmission system is released, and the actuator EA2 becomes free. Therefore, when the actuator EA2 is installed between the car body 52 and the bogie 51 in FIG. 3, it is possible to prevent the vibration of the bogie 51 from being transmitted to the car body 52 via the actuator EA2 when the power transmission system is stuck, and the ride comfort of the railway vehicle can be improved. In addition, the broken support members 15A and 15B can be held within the actuator EA2, and the broken support members 15A and 15B can be prevented from scattering outside the actuator EA2.

FIG. 7 is an exploded perspective view showing the configuration of the actuator after the cotter, the key, and the intermediate member according to the third embodiment are attached.
In Fig. 7, this actuator EA3 includes an intermediate member 27 instead of the intermediate member 17 of the actuator EA2 of Fig. 4(b). Furthermore, this actuator EA3 includes elastic members 25A and 25B in addition to the configuration of the actuator EA2 of Fig. 4(b).

The intermediate member 27 mediates the connection between the nut 12 and the output shaft 13 while allowing the connection between the nut 12 and the output shaft 13 to be reversibly released. The intermediate member 27 is, for example, cylindrical in shape. The intermediate member 27 can be inserted into the output shaft 13 along the axial direction. The nut 12 can be inserted into the intermediate member 27 along the axial direction. At this time, the outer peripheral surface of the intermediate member 27 can be configured to follow the inner peripheral surface of the output shaft 13. The inner peripheral surface of the intermediate member 27 can be configured to follow the outer peripheral surface of the nut 12.

The cotter 14 is used as a first connecting member that connects the nut 12 and the intermediate member 27. The key 14' is used as a second connecting member that connects the intermediate member 27 and the output shaft 13.

The elastic members 25A and 25B sandwich the key 14' so that the key 14' is supported by the intermediate member 27. At this time, the elastic members 25A and 25B can be fitted into the intermediate member 27. Each of the elastic members 25A and 25B is, for example, a spring that can sandwich the key 14' from both sides when fitted into the intermediate member 27. This spring is, for example, a thin flat spring bent in the middle.

The intermediate member 27 has through holes 27A, 27A' and a groove 27B'. The through hole 27A accommodates the rear end of the cotter 14. The through hole 27A can be provided on the side of the intermediate member 27.

The through-hole 27A' can receive the elastic members 25A and 25B. By receiving the elastic members 25A and 25B in the through-hole 27A' so that the key 14' inserted in the through-hole 27A' is sandwiched from both sides, the elastic members 25A and 25B can support the key 14' so that the axial force can be transmitted from the intermediate member 27 to the output shaft 13 while allowing the connection between the nut 12 and the output shaft 13 to be released.

The elastic members 25A and 25B can release the connection between the nut 12 and the output shaft 13 based on the load applied to the key 14'. At this time, the elastic members 25A and 25B are elastically deformed based on the load applied to the key 14' and can be detached from the through hole 27A'. The elastic members 25A and 25B can be arranged along the axial direction so as to sandwich the side surfaces of the key 14' from both sides so that they can be detached along the groove 27B'.

Here, the connection between the nut 12 and the output shaft 13 can be released by setting the strength of the elastic members 25A and 25B so that the elastic members 25A and 25B can be detached based on the load applied to the key 14'. The strength of the elastic members 25A and 25B can be adjusted based on the thickness or material of the elastic members 25A and 25B. At this time, the strength of the elastic members 25A and 25B can be set so that the connection between the nut 12 and the output shaft 13 is not released during normal operation of the actuator EA3, and the connection between the nut 12 and the output shaft 13 is released when a load larger than the normal operation of the actuator EA3 is applied to the key 14'. In addition, by setting the strength of the elastic members 25A and 25B so that the elastic members 25A and 25B can be detached, the connection between the nut 12 and the output shaft 13 can be released in both the forward and backward directions of the output shaft 13.

The groove 27B' allows the key 14' and the elastic members 25A and 25B to move in the axial direction. The groove 27B' allows the key 14' and the elastic members 25A and 25B to escape in the axial direction when the elastic members 25A and 25B are detached.

Here, by using elastic members 25A and 25B to support key 14' with intermediate member 27, it is no longer necessary to drive key 14' into nut 12 in order to fix key 14' to nut 12 via output shaft 13. This makes it possible to prevent damage to nut 12 when key 14' is fixed to nut 12, and also makes it easier to remove key 14' from nut 12, facilitating the release of the connection between nut 12 and output shaft 13.

Figure 8(a) is a cross-sectional view showing the configuration of the nut portion of the linear motion device according to the third embodiment, Figure 8(b) is a plan view showing the configuration of the nut portion of Figure 8(a), and Figures 8(c) and 8(d) are plan views showing the state when the spring of Figure 8(b) is released. Note that Figure 8(a) is a cross-sectional view cut at the position of key 14' along the axial direction of the actuator.

In Figures 8(a) and 8(b), when inserted into the through hole 27A', the key 14' is sandwiched from both sides by the elastic members 25A and 25B. This allows the elastic members 25A and 25B to support the key 14' so that the axial force can be transmitted from the intermediate member 27 to the output shaft 13 while allowing the connection between the nut 12 and the output shaft 13 to be released.

In FIG. 8(c), the movement of the nut 12 is restricted due to the stuck or loaded state of the power transmission system, such as the motor, gears, or linear motion parts. At this time, when an external force is applied in the backward direction of the output shaft 13, the external force is applied to the key 14' via the output shaft 13. The external force applied to the key 14' is applied to the elastic member 25A, and when the load on the key 14' exceeds a predetermined value, the elastic member 25A can no longer withstand the load, and the elastic member 25A and the key 14' become detached.

In addition, in FIG. 8(d), when an external force is applied in the forward direction of the output shaft 13, the external force is applied to the key 14' via the output shaft 13. The external force applied to the key 14' is applied to the elastic member 25B, and when the load on the key 14' exceeds a predetermined value, the elastic member 25B can no longer withstand the load, and the elastic member 25B and the key 14' become detached.

When the elastic members 25A, 25B and the key 14' are detached, the axial force based on the linear motion of the nut 12 cannot be transmitted to the output shaft 13 via the intermediate member 27, and the movement of the output shaft 13 can be prevented from being restricted via the nut 12.

Figures 9(a) and 9(b) are cross-sectional views showing the configuration of an actuator according to the fourth embodiment. Note that Figure 9(a) is a cross-sectional view taken along the axial direction of the actuator at the position of the cotter 14, and Figure 9(b) is a cross-sectional view taken along the axial direction of the actuator at the position of the key 14'.

In Figures 9(a) and 9(b), this actuator EA4 includes a screw shaft 11, a nut 32, an output shaft 33, a cotter 14, a key 14', and an intermediate member 37. The screw shaft 11 and the nut 32 can be used as a ball screw that constitutes a linear motion device. The nut 32 converts the rotational motion of the screw shaft 11 into linear motion in the axial direction of the screw shaft 11. The output shaft 33 outputs an axial force based on the linear motion converted by the nut 32. The intermediate member 37 mediates the connection between the nut 32 and the output shaft 33 while increasing the degree of freedom of the axial spacing between the key 14' and the cotter 14.

The output shaft 33 and the intermediate member 37 are, for example, cylindrical in shape. The intermediate member 37 can be inserted into the output shaft 33 along the axial direction. The nut 32 can also be inserted into the intermediate member 37 along the axial direction.

The cotter 14 is used as a first connecting member that connects the nut 32 and the intermediate member 37. The key 14' is used as a second connecting member that connects the intermediate member 37 and the output shaft 33.

In addition, in the nut 32 and intermediate member 37, the axial position of the key 14' is shifted toward the output shaft 33 compared to the axial position of the cotter 14. The intermediate member 37 extends from the nut 32 in the axial direction of the output shaft 33. The length of the output shaft 33 is shortened so that the cotter 14 is exposed.

For example, as shown in Figures 5(a) and 5(b), in the actuator EA2, the position of the axial end face E1 on the gear G3 side of the nut 12 and the position of the axial end face E2 on the gear G3 side of the output shaft 13 coincide with each other. Also, in the actuator EA2, the position of the axial end face E3 on the output shaft 13 side of the nut 12 and the position of the axial end face E4 on the output shaft 13 side of the intermediate member 17 coincide with each other.

In contrast, as shown in Figures 9(a) and 9(b), in the actuator EA4, the position of the axial end face E5 on the gear G3 side of the output shaft 33 is set so that the cotter 14 is exposed relative to the position of the axial end face E1 on the gear G3 side of the nut 32. At this time, the length of the output shaft 33 can be shortened by the distance between the position of the axial end face E2 on the gear G3 side of the output shaft 13 of the actuator EA2 and the position of the axial end face E5 on the gear G3 side of the output shaft 33 of the actuator EA4.

In addition, in the actuator EA4, the position of the axial end face E6 on the output shaft 33 side of the intermediate member 37 is set to be closer to the output shaft 33 side than the position of the axial end face E3 on the output shaft 33 side of the nut 32. At this time, the position of the key 14' can be set so that it overlaps with the axial end face E3 on the output shaft 33 side of the nut 32.

The output shaft 33 has a through hole 33A'. The intermediate member 37 has support members 35A, 35B and a groove 37B'. The through hole 33A', support members 35A, 35B and groove 37B' of the actuator EA4 can be configured in the same way as the through hole 13A', support members 15A, 15B and groove 17B', except that they are positioned differently from the through hole 13A', support members 15A, 15B and groove 17B' of the actuator EA2. However, the length of the groove 37B' can be adjusted according to the extension length of the intermediate member 37 toward the output shaft.

Here, by using an intermediate member 37 to connect the nut 32 to the output shaft 33 and by shifting the axial position of the key 14' closer to the output shaft 33 than the axial position of the cotter 14, the nut 32 can be connected to the output shaft 33 without extending the output shaft 33 to the position of the cotter 14. This makes it possible to shorten the output shaft 33 without reducing the axial stroke of the actuator EA4, and eliminates the need to provide a through hole in the output shaft 33 for inserting the cotter 14, making it possible to reduce the size and weight of the output shaft 33, reduce costs, simplify processing, improve durability, and improve ease of assembly.

FIG. 10(a) is an exploded perspective view showing the configuration of the actuator before the cotter, key, and intermediate member according to the fifth embodiment are attached, and FIG. 10(b) is an exploded perspective view showing the configuration of the actuator after the cotter, key, and intermediate member according to the fifth embodiment are attached.
10(a) and 10(b), this actuator EA5 includes an intermediate member 47 instead of the intermediate member 17 of the actuator EA2 of FIG. 4(b).

The intermediate member 47 mediates the connection between the nut 12 and the output shaft 13. The intermediate member 47 has through holes 47A and 47A'. The through hole 47A accommodates the rear end of the cotter 14. The through hole 47A can be provided on the side of the intermediate member 47. At this time, the tip end of the cotter 14 can be accommodated in the recess 12A through the through hole 47A. The through hole 47A' accommodates the middle part of the key 14'. The through hole 47A' can be provided on the side of the intermediate member 47. At this time, the tip end of the key 14' can be accommodated in the recess 12A' through the through hole 47A'. The rear end of the key 14' is accommodated in the through hole 13A'.

The cotter 14 is used as a first connecting member that connects the nut 12 and the intermediate member 47. The key 14' is used as a second connecting member that connects the intermediate member 47 and the output shaft 13.

By making it possible to connect the nut 12 and the output shaft 13 via the intermediate member 47, the connection position of the nut 12 and the connection position of the output shaft 13 can be set separately. This improves the degree of freedom in designing the positions, sizes, shapes, etc. of the nut 12 and the output shaft 13, and allows the nut 12 or the output shaft 13 to be made smaller, lighter, less expensive, easier to process, or easier to assemble.

In addition, the nut 12 and the intermediate member 47 can be joined by inserting the cotter 14, and the output shaft 13 and the intermediate member 47 can be joined by inserting the key 14'. This eliminates the need to use a complex configuration such as a gripping mechanism or clutch mechanism to join the nut 12 and the output shaft 13, and improves the design freedom of the position, size, shape, etc. of the nut 12 and the output shaft 13 while preventing the actuator EA5 from becoming larger and more expensive.

FIG. 11 is an exploded perspective view showing the configuration of the actuator according to the sixth embodiment.
In Fig. 11, this actuator EA6 includes a nut 52 instead of the nut 2 of the actuator EA1 of Fig. 1. Also, this actuator EA5 includes elastic members 55, 55' in addition to the configuration of the actuator EA1 of Fig. 1.

The nut 52 converts the rotational motion of the screw shaft 1 into linear motion in the axial direction of the screw shaft 1 while reversibly releasing the connection between the nut 2 and the output shaft 3. The nut 52 has recesses 52A and 52A'.

The recess 52A accommodates the tip of the cotter 4 together with the elastic member 55. The recess 52A can be provided on the outer peripheral surface of the nut 2. At this time, the cotter 4 can be fitted into the recess 52A so that the cotter 4 is sandwiched around the periphery by the elastic member 55. The recess 52A is configured to receive the axial force applied to the cotter 4. For example, the recess 52A may be a groove provided in the nut 2 along the circumferential direction so that a static friction force acts between the elastic member 55 and the recess 52A when the elastic member 55 is fitted. At this time, the axial force applied to the cotter 4 can be received by the wall surfaces on both sides of the recess 52A formed in the nut 2.

The recess 52A' accommodates the tip of the key 4' together with the elastic member 55'. The recess 52A' can be provided on the outer peripheral surface of the nut 2. The recess 52A' can be arranged at a distance from the recess 52A in the circumferential direction of the nut 2. At this time, the key 4' can be fitted into the recess 52A' so that the elastic member 55' pinches the periphery of the key 4'. The recess 52A' is configured to receive the rotational force applied to the key 4'. For example, the recess 52A' may be a groove provided in the nut 2 along the axial direction so that a static frictional force acts between the elastic member 55' and the recess 52A' when the elastic member 55' is fitted. At this time, the rotational force applied to the key 4' can be received by the wall surfaces on both sides of the recess 52A' formed in the nut 2.

The elastic member 55 sandwiches the cotter 4 so that the cotter 4 is supported by the nut 52. At this time, the elastic member 55 can be fitted into the nut 52. The elastic member 55 is, for example, a spring that can sandwich the cotter 4 from the periphery while being fitted into the nut 52. This spring is, for example, a thin leaf spring that is bent to surround the periphery of the cotter 4 while being expandable in the longitudinal direction of the cotter 4. When this spring expands in the longitudinal direction of the cotter 4, it narrows in the lateral direction of the cotter 4, and when it contracts in the longitudinal direction of the cotter 4, it can expand in the lateral direction of the cotter 4. At this time, the elastic member 55 is fitted into the recess 52A while sandwiching the cotter 4 from the periphery, so that static friction can work between the cotter 4 and the nut 52, and the cotter 4 can be prevented from slipping out of the recess 52A.

The elastic member 55' sandwiches the key 4' so that the key 4' is supported by the nut 52. At this time, the elastic member 55' can be fitted into the nut 52. The elastic member 55' is, for example, a spring that can sandwich the key 4' from the periphery while being fitted into the nut 52. This spring is, for example, a thin leaf spring that is bent to surround the periphery of the key 4' while being expandable in the longitudinal direction of the key 4'. When this spring expands in the longitudinal direction of the key 4', it narrows in the lateral direction of the key 4', and when it contracts in the longitudinal direction of the key 4', it can expand in the lateral direction of the key 4'. At this time, the elastic member 55' is fitted into the recess 52A' while sandwiching the key 4' from the periphery, so that static friction can be applied between the key 4' and the nut 52, and the key 4' can be prevented from slipping out of the recess 52A'.

Here, by using elastic members 55, 55' to support the cotter 4 and key 4' with the nut 52, it is no longer necessary to drive the cotter 4 and key 4' into the nut 52 in order to fix the cotter 4 and key 4' to the nut 52 via the output shaft 3. This makes it possible to prevent the nut 52 from being damaged when fixing the cotter 4 and key 4' to the nut 52, and also makes it easier to remove the cotter 4 and key 4' from the nut 52, facilitating replacement of the cotter 4 and key 4' and release of the connection between the nut 52 and the output shaft 3.

Furthermore, by fitting the elastic members 55, 55' into the nut 52 while the cotter 4 and key 4' are inserted into the nut 52, it is possible to prevent the cotter 4 and key 4' from falling off the nut 52 and to facilitate the removal of the cotter 4 and key 4' from the nut 52.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and includes various modified examples. For example, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

For example, in the actuator EA2 of Figures 4(a) and 4(b), support members 15A and 15B that can release the connection between the nut 12 and the output shaft 13 are provided on the key 14' side, but support members that can release the connection between the nut 12 and the output shaft 13 may be provided on the cotter 14 side.

In addition, in the actuator EA3 of FIG. 7, an example is shown in which the key 14' is supported by the elastic members 25A and 25B to enable the connection between the nut 12 and the output shaft 13 to be released, but the cotter 14 may also be supported by an elastic member.

1 Screw shaft, 2 Nut, 2A, 2A' Recess, 3 Output shaft, 3A, 3A' Through hole, 4 Cotter, 4' Key, 5 Support member, 6 Ball circulator

Claims (12)

A screw shaft,
A nut that converts the rotational motion of the screw shaft into a linear motion in the axial direction of the screw shaft;
A coupling member that couples the nut to an output shaft that outputs an axial force based on the linear motion converted by the nut;
a support member that supports the coupling member so as to transmit the axial force from the nut to the output shaft while enabling the coupling between the nut and the output shaft to be released ;
an intermediate member that mediates the connection between the nut and the output shaft ,
The connecting member is
a first connecting member that connects the nut and the intermediate member;
a second coupling member that couples the intermediate member and the output shaft,
The linear motion device , wherein the support member is provided on the intermediate member . The intermediate member extends from the nut in the axial direction of the output shaft,
2. The linear motion device according to claim 1 , wherein the axial position of the second connecting member is shifted toward the output shaft as compared with the axial position of the first connecting member. 3. The linear motion device according to claim 1 , wherein the support member releases the connection between the nut and the output shaft based on a load applied to the connection member. 4. The linear motion device according to claim 3 , wherein the support member is breakable or detachable based on a load applied to the connecting member. 5. The linear motion device according to claim 1, wherein the support member is capable of releasing the connection in both the forward and backward directions of the output shaft. The first coupling member can be inserted into the nut by penetrating the intermediate member in a direction perpendicular to the axial direction of the screw shaft,
6. The linear motion device according to claim 1 , wherein the second coupling member is insertable into the intermediate member through the output shaft in a direction perpendicular to an axial direction of the screw shaft. 7. The linear motion device according to claim 1, wherein the support member is provided on the nut. 8. The linear motion device according to claim 1 , wherein the strength of the support member is set based on a load required for releasing the connection. 9. The linear motion device according to claim 1, wherein the support member is an elastic member that sandwiches the coupling member so that the coupling member is supported between the nut and the output shaft. A screw shaft,
A nut that converts the rotational motion of the screw shaft into a linear motion in the axial direction of the screw shaft;
A coupling member that couples the nut to an output shaft that outputs an axial force based on the linear motion converted by the nut;
an intermediate member that mediates the connection between the nut and the output shaft,
The connecting member is
a first connecting member that connects the nut and the intermediate member;
a second connecting member connecting the intermediate member and the output shaft. The first coupling member can be inserted into the nut by penetrating the intermediate member in a direction perpendicular to the axial direction of the screw shaft,
The linear motion device according to claim 10 , wherein the second coupling member is insertable into the intermediate member through the output shaft in a direction perpendicular to an axial direction of the screw shaft. A linear motion device according to any one of claims 1 to 11 ,
An actuator comprising the output shaft.