Linear motion device and actuator

Abstract

To provide an actuator capable of releasing coupling to an output shaft.SOLUTION: A linear motion device according to one embodiment includes: a screw shaft; a nut which converts rotational motion of the screw shaft into linear motion in an axial direction of the screw shaft; a coupling member which couples the nut to the output shaft, which outputs axial force, based on the linear motion converted by the nut; and a support member which can release coupling between the nut and the output shaft and supports the coupling member so that the axial force may be transmitted from the nut to the output shaft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a linear motion device and an actuator.

Background Art

[0002] As an actuator for obtaining an axial force in the axial direction from an input torque, there is a technique using a ball screw that converts rotational motion into linear motion. In this actuator, the rotational motion of the screw shaft is converted into the linear motion of the nut, and the axial force is extracted from the output shaft coupled to the nut. Patent Document 1 discloses a technique using a cotter for coupling the nut and the output shaft of the actuator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an actuator using a cotter for coupling the nut and the output shaft, when the power transmission system is fixed, it may be desirable to release the coupling between the actuator and the output shaft in order to avoid the influence of the fixation. Therefore, an aspect of the present invention aims to provide a linear motion device and an actuator capable of releasing the coupling with the output shaft.

Means for Solving the Problems

[0005] According to a linear motion device according to an aspect of the present invention, in order to solve the above problems, there are provided 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, and a support member that supports the coupling member so as to be able to transmit the axial force from the nut to the output shaft while enabling the release of the coupling between the nut and the output shaft.

[0006] Thereby, even when the movement of the nut is restricted according to the fixed state or load state of the power transmission system, etc., without providing a complicated mechanism for releasing the coupling between the nut and the output shaft, it is possible to prevent the movement of the output shaft from being restricted via the nut. For this reason, it is possible to suppress the increase in size and cost of the actuator, and to prevent the operation of the output destination of the axial force from the output shaft from being restricted via the output shaft, and to avoid the influence of the fixed state or high load state of the power transmission system.

[0007] According to a linear motion device according to an aspect of the present invention, the support member releases the coupling between the nut and the output shaft based on the load applied to the coupling member.

[0008] Thereby, without providing a sensor for detecting the fixed state or load state of the power transmission system, etc., it is possible to release the coupling between the nut and the output shaft, and without providing a complicated mechanism for releasing the coupling between the nut and the output shaft, it is possible to prevent the movement of the output shaft from being restricted via the nut.

[0009] According to a linear motion device according to an aspect of the present invention, the support member is breakable or detachable based on the load applied to the coupling member.

[0010] As a result, the support member itself can be provided with the function of releasing the connection between the nut and the output shaft. Therefore, there is no need to separately provide a component for releasing the connection between the nut and the output shaft from the component that supports the connection member, and while suppressing the increase in size and cost of the actuator, it is possible to prevent the operation of the output destination of the axial force from the output shaft from being restricted via the output shaft.

[0011] Also, according to the linear motion device according to one aspect of the present invention, the support member can release the connection in any direction of forward and backward movement of the output shaft.

[0012] As a result, in any direction of forward and backward movement of the output shaft, it is possible to prevent the operation of the output destination of the axial force from the output shaft from being restricted via the output shaft.

[0013] Also, according to the linear motion device according to one aspect of the present invention, the connection member can penetrate the output shaft in a direction orthogonal to the axial direction of the screw shaft and be inserted into the support member.

[0014] As a result, by inserting the connection member itself, the nut and the output shaft can be connected, and there is no need to use a complicated configuration such as a gripping mechanism or a clutch mechanism to connect the nut and the output shaft. Therefore, while suppressing the increase in size and cost of the actuator, the nut and the output shaft can be connected.

[0015] Also, according to the linear motion device according to one aspect of the present invention, the support member is provided on the nut.

[0016] As a result, the nut can be provided with the function of releasing the connection between the nut and the output shaft. Therefore, there is no need to separately provide a component for releasing the connection between the nut and the output shaft from the nut, and while suppressing the increase in size and cost of the actuator, it is possible to prevent the operation of the output destination of the axial force from the output shaft from being restricted via the output shaft.

[0017] Also, according to the linear motion device according to one aspect of the present invention, an intermediate member is provided for mediating the connection between the nut and the output shaft. The connecting member includes a first connecting member that connects the nut and the intermediate member, and a second connecting member that connects the intermediate member and the output shaft. The support member is provided on the intermediate member.

[0018] Thereby, in order to connect the nut and the output shaft, the connection position between the nut and the intermediate member and the connection position between the intermediate member and the output shaft can be set separately. Therefore, the degree of freedom in designing the positions, sizes, and shapes of the nut and the output shaft can be improved, and for the nut or the output shaft, it is possible to achieve miniaturization, weight reduction, cost reduction, simplification of processing, or improvement of assemblability.

[0019] Also, according to the linear motion device according to one aspect of the present invention, the intermediate member extends in the axial direction of the output shaft from the nut, and the axial position of the second connecting member is closer to the output shaft side than the axial position of the first connecting member.

[0020] Thereby, the nut and the output shaft can be connected without extending the output shaft to the position of the first connecting member. Therefore, it is possible to shorten the output shaft without reducing the axial stroke amount of the actuator, and it is not necessary to provide a through hole in the output shaft for inserting the first connecting member, and it is possible to achieve miniaturization, weight reduction, cost reduction, simplification of processing, high durability, and improvement of assemblability of the output shaft.

[0021] Also, according to the 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.

[0022] As a result, compared with the case where the nut and the output shaft cannot be decoupled, by reducing the thickness of the support member or changing the material of the support member, the coupling between the nut and the output shaft can be made releasable. Therefore, even when the fixation of the power transmission system occurs, it is possible to prevent the operation 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.

[0023] Also, according to the linear motion device according to one aspect of the present invention, 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.

[0024] As a result, there is no need to drive the coupling member into the nut in order to fix the coupling member to the nut via the output shaft. Therefore, it is possible to prevent the nut from being damaged when the coupling member is fixed to the nut, and it is possible to easily extract the coupling member from the nut, facilitating the release of the coupling between the nut and the output shaft.

[0025] Also, according to the linear motion device according to one aspect of the present invention, 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, and an intermediate member that mediates the coupling between the nut and the output shaft are provided, and the coupling member includes a first coupling member that couples the nut and the intermediate member, and a second coupling member that couples the intermediate member and the output shaft.

[0026] As a result, in order to couple the nut and the output shaft, the coupling position of the nut and the coupling position of the output shaft can be set separately, improving the degree of freedom in the design of the positions, sizes, shapes, etc. of the nut and the output shaft.

[0027] Further, according to the linear motion device according to one aspect of the present invention, the first coupling member can be inserted into the nut through 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 through the output shaft in a direction perpendicular to the axial direction of the screw shaft.

[0028] Thereby, by inserting the first coupling member, the nut and the intermediate member can be coupled, and by inserting the second coupling member, the output shaft and the intermediate member can be coupled. For this reason, while separately setting the coupling position of the nut and the coupling position of the output shaft, the nut and the output shaft can be coupled, and while suppressing an increase in size and cost of the actuator, the degrees of freedom in design such as the position, size, and shape of the nut and the output shaft can be improved.

[0029] Further, according to the linear motion device according to one aspect of the present invention, it includes 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, and an elastic member that sandwiches the coupling member so that the coupling member is supported by the nut.

[0030] Thereby, in order to fix the coupling member to the nut via the output shaft, it is not necessary to drive the coupling member into the nut, and it becomes possible to prevent the nut from being damaged when the coupling member is fixed to the nut. Further, the removal of the coupling member from the nut can be facilitated, and the replacement of the coupling member and the release of the coupling between the nut and the output shaft can be easily performed.

[0031] Further, according to the linear motion device according to one aspect of the present invention, the elastic member is a spring that can sandwich the coupling member from both sides in a state of being fitted into the nut.

[0032] Thereby, by fitting the spring into the nut with the coupling member inserted into the nut, it becomes possible to prevent the coupling member from falling off the nut and to facilitate the removal of the coupling member from the nut.

[0033] Further, according to the actuator according to one aspect of the present invention, it includes any of the linear actuators described above and the output shaft.

[0034] Thereby, an actuator capable of releasing the connection between the nut and the output shaft can be provided.

Advantages of the Invention

[0035] According to one aspect of the present invention, a linear actuator and an actuator capable of releasing the connection with the output shaft can be provided.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all combinations of the features described in the embodiments are essential for the configuration of the present invention. The configuration of the embodiments can be appropriately modified or changed according to the specifications of the device to which the present invention is applied and various conditions (usage conditions, usage environment, etc.). The technical scope of the present invention is determined by the scope of 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, scale, shape, etc. in order to make each configuration easier to understand.

[0038] FIG. 1(a) is a perspective view showing the disassembled configuration of the actuator before mounting the cottar and the key according to the first embodiment, FIG. 1(b) is a perspective view showing the disassembled configuration of the actuator after mounting the cottar and the key according to the first embodiment, FIG. 2(a) is a side view showing the configuration of the actuator according to the first embodiment when viewed from the cottar side, and FIG. 2(b) is a cross-sectional view showing the configuration of the actuator cut along the line A-A in FIG. 2(a).

[0039] In FIGS. 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 cottar 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 drive 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. 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.

[0040] The cotter 4 and the key 4' are used as coupling members that couple the output shaft 3 to the nut 2. The cotter 4 and the key 4' can be inserted into the nut 2 through 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 of protruding toward the output shaft 3 side. 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 locking member for the output shaft 3 relative to the nut 2. The key 4' can be arranged at an interval from the cotter 4 in the circumferential direction of the output shaft 3'. At this time, 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.

[0041] The ball circulator 6 returns a plurality of balls that are rollably loaded in the ball rolling path formed between the screw shaft 1 and the nut 2 from the end point to the starting point of the ball rolling path to circulate the balls. The ball circulator 6 is attached to the nut 2.

[0042] The screw shaft 1 is provided with a screw groove 1m. The screw groove 1m is provided spirally on the outer peripheral surface of the screw shaft 1. The nut 2 is provided with a screw groove 2m. The screw groove 2m is provided spirally 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.

[0043] The nut 2 is provided with a support member 5 and a recess 2A'. The support member 5 is provided with a recess 2A. The output shaft 3 is provided with through holes 3A and 3A'.

[0044] The support member 5 supports the cotter 4 so that the axial force can be transmitted from the nut 2 to the output shaft 3 while enabling the release of the coupling between the nut 2 and the output shaft 3. The support member 5 can release the coupling between the nut 2 and 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.

[0045] The recessed portion 2A accommodates the tip of the cotter 4. Note that the tip of the cotter 4 refers to the tip in the insertion direction of the cotter 4 (the radial direction of the nut 2) (the portion that is fitted into the recessed portion 2A of the nut 2). The planar shape of the recessed portion 2A can correspond to the planar shape of the tip of the cotter 4. At this time, the cotter 4 can be fitted into the recessed portion 2A. In order to prevent the cotter 4 from coming out of the recessed portion 2A, static friction may act between the cotter 4 and the recessed portion 2A. For example, when fitting the cotter 4 into the recessed portion 2A, the cotter 4 may be driven into the recessed portion 2A.

[0046] The recessed portion 2A is configured to receive the axial force applied to the cotter 4. For example, the recessed portion 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 recessed portion 2A formed in the support member 5. Here, by setting the strength of the wall surface of the recessed portion 2A such that the wall surface of the recessed portion 2A breaks based on the load applied to the cotter 4, the connection between the nut 2 and the output shaft 3 can be released. The strength of the wall surface of the recessed portion 2A can be adjusted based on the thickness or material of the wall surface of the recessed portion 2A. At this time, the connection between the nut 2 and the output shaft 3 is not released during the normal operation of the actuator EA1, and the strength of the wall surface of the recessed portion 2A can be set such that the connection between the nut 2 and the output shaft 3 is released when a load greater than the normal operation of the actuator EA1 is applied to the cotter 4. Also, by setting the strength of the wall surfaces on both sides of the recessed portion 2A such that the wall surfaces on both sides of the recessed portion 2A can be broken, the connection between the nut 2 and the output shaft 3 can be released in either the forward or backward direction of the output shaft 3.

[0047] The recess 2A´ accommodates the tip of the key 4´. Note that the tip of the key 4´ refers to the tip in the insertion direction of the key 4´ (the radial direction of the nut 2) (the portion to be fitted into the recess 2A´ of the nut 2). The recess 2A´ can be provided on the outer peripheral surface of the nut 2. The recess 2A´ can be arranged at an interval 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´. At this time, the key 4´ can be fitted into the recess 2A´. In order to prevent the key 4´ from coming out of the recess 2A´, static friction may act 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´.

[0048] 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. At this time, the rotational force applied to the key 4´ can be received by the wall surfaces on both sides of the recess 2A´ formed in the nut 2.

[0049] The through-hole 3A accommodates the rear end portion of the cutter 4. Note that the rear end portion of the cutter 4 refers to the rear end in the insertion direction of the cutter 4 (the radial direction of the nut 2) (the portion to be fitted into the through-hole 3A of the output shaft 3). The through-hole 3A can be provided on the side surface of the output shaft 3. At this time, the tip of the cutter 4 can be accommodated in the recess 2A through the through-hole 3A.

[0050] The through-hole 3A´ accommodates the rear end portion of the key 4´. Note that the rear end portion of the key 4´ refers to the rear end in the insertion direction of the key 4´ (the radial direction of the nut 2) (the portion to be fitted into the through-hole 3A´ of the output shaft 3). The through-hole 3A´ can be provided on the side surface of the output shaft 3. The through-hole 3A´ can be arranged at an interval from the through-hole 3A in the circumferential direction of the output shaft 3´. At this time, the tip of the key 4´ can be accommodated in the recess 2A´ through the through-hole 3A´.

[0051] 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 bodies. For example, they may be metals such as iron or aluminum alloys, or non-metals such as ceramics. The cross-sectional shapes of the screw grooves 1m and 2m may be, for example, on an arc or in a Gothic arc shape.

[0052] The rotational force generated from a drive source such as a motor is input to the screw shaft 1, 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 the ball circulator 6 along the ball rolling path, while the nut 2 moves in a linear motion. Then, the 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.

[0053] The actuator EA1 can be used, for example, in a vibration damping device such as a vehicle. For example, in the case of a vibration damping device for a railway vehicle, the actuator EA1 can be installed between the car body and the bogie. Then, by outputting an axial force that is out of phase with the vibration of the car body from the output shaft 3, the vibration of the car body can be reduced.

[0054] Here, assume that the movement of the nut 2 is restricted according to the fixed state or load state of the power transmission system such as a motor, gear or linear moving parts. When the power transmission system is fixed, power cannot be transmitted from the motor and the reduction unit, and linear output from the output shaft 3 becomes impossible. Note that the fixation of the power transmission system includes, for example, the fixation of the screw in the ball screw part, the jamming of the nut 2, and the jamming of each component such as the ball circulator 6.

[0055] At this time, the load applied to the cotter 4 increases according to the fixed state or high load state of the power transmission system. When the load applied to the cotter 4 exceeds a predetermined value, the support member 5 can no longer receive the load, and the support member 5 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. Therefore, it is 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 it is possible to avoid the influence of the fixed state or high load state of the power transmission system.

[0056] The actuator EA1 can reduce vibration and roll, 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 application example of the actuator in FIG. 2(a) to a railway vehicle. In FIG. 3, the car body 62 is supported on the bogie 61 via the bolster spring 63. The bogie 61 includes wheels 65 and a bogie frame 69. The car body 62 is installed on the bogie frame 69 via the bolster spring 63. A pair of wheels 65 are supported to face each other via an axle 66. An axle box 67 is provided outside each wheel 65, and a suspension spring 68 is provided on the axle box 67. The bogie frame 69 is supported on the wheels 65 via the suspension spring 68.

[0057] The 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 center pin 70 provided on the bottom surface of the car body 62. Then, the vibration damping system measures the vibration and roll of the car body 62 with an acceleration sensor while the railway vehicle is running on the rail 64, calculates the vibration damping force required to reduce the vibration and roll of the car body 62 with a control device, and operates the actuator EA1.

[0058] At this time, if the power transmission system becomes fixed, the actuator EA1 will always be in a taut state, and the vibration of the bogie 61 will be directly transmitted to the car body 62 via the actuator EA1, deteriorating the riding comfort of the railway vehicle. At this time, the axial force applied to the support member 5 in Fig. 2(b) increases, and when the support member 5 breaks, the connection between the nut 2 and the output shaft 3 is released. As a result, even when the power transmission system becomes fixed, it is possible to prevent the vibration of the bogie 61 from being transmitted to the car body 62 via the actuator EA1, and the riding comfort of the railway vehicle can be improved.

[0059] Also, based on the increase in the axial force applied to the support member 5 when the power transmission system becomes fixed, by breaking the support member 5, it is possible to release the connection between the nut 2 and the output shaft 3 without providing a sensor for detecting the fixed state of the power transmission system. Therefore, it is possible to prevent the movement of the output shaft 3 from being restricted via the nut 2 without providing a complicated mechanism for releasing the connection between the nut 2 and the output shaft 3.

[0060] Also, by giving the support member 5 the function of releasing the connection between the nut 2 and the output shaft 3, there is no need to separately provide a component for releasing the connection between the nut 2 and the output shaft 3 from the support member 5. Therefore, it is 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 while suppressing the increase in size and cost of the actuator EA1.

[0061] Also, by using the cotter 4 for the connection between the nut 2 and the output shaft 3, it becomes possible to easily connect the nut 2 and the output shaft 3, and based on the simple processing of the nut 2, the support member 5 can be given the function of releasing the connection between the nut 2 and the output shaft 3. Therefore, there is no need to use a complicated configuration such as a gripping mechanism or a clutch mechanism to connect or release the connection between the nut 2 and the output shaft 3, and it is possible to suppress the increase in size and cost of the actuator EA1.

[0062] FIG. 4(a) is a perspective view showing the disassembled configuration of the actuator before mounting the cottar, key, and intermediate member according to the second embodiment, and FIG. 4(b) is a perspective view showing the disassembled configuration of the actuator after mounting the cottar, key, and intermediate member according to the second embodiment.

[0063] In FIGS. 4(a) and 4(b), this actuator EA2 includes a screw shaft 11, a nut 12, an output shaft 13, a cottar 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 a rotational motion based on the rotational force generated from a drive source such as a motor. The nut 12 converts the rotational motion of the screw shaft 11 into a 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 enabling the release of the connection between the nut 12 and the output shaft 13.

[0064] The shapes of the output shaft 13 and the intermediate member 17 are, for example, cylindrical. The diameter of the intermediate member 17 can be made smaller than the diameter of the output shaft 13 so that the intermediate member 17 can be inserted into the output shaft 13 along the axial direction. Also, the diameter of the intermediate member 17 can be made larger than the diameter of the nut 12 so that the nut 12 can be inserted into the intermediate member 17 along the axial direction. At this time, 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.

[0065] In the example of FIG. 4, the cotter 14 is used as a first coupling member that couples the nut 12 and the intermediate member 17. The cotter 14 can be inserted into the nut 12 through the intermediate member 17 in a direction orthogonal 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 of protruding 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.

[0066] Also, in the example of FIG. 4, the key 14' is used as a second coupling member that couples the intermediate member 17 and the output shaft 13. The key 14' can be inserted into the intermediate member 17 through the output shaft 13 in a direction orthogonal 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 of protruding 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.

[0067] Also, the key 14' can be inserted into the nut 12 via the intermediate member 17. At this time, the key 14' can also be used as a rotation prevention member of the output shaft 13 with respect 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'.

[0068] The nut 12 includes recesses 12A and 12A'. The output shaft 13 includes a through hole 13A'. The intermediate member 17 includes support members 15A and 15B, a through hole 17A, an insertion portion 17A', and a groove 17B'.

[0069] 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. In order to prevent the cotter 14 from coming out of the recess 12A, static friction may act between the cotter 14 and the recess 12A.

[0070] 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. At this time, 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.

[0071] The through hole 17A houses the rear end portion of the cotter 14. The through hole 17A can be provided on the side surface of the intermediate member 17. At this time, the tip end portion of the cotter 14 can be housed in the recess 12A through the through hole 17A.

[0072] The recess 12A' houses the tip end portion 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 end of the key 14'. At this time, the key 14' can be fitted into the recess 12A'. In order to prevent the key 14' from coming out of the recess 12A', static friction may act between the key 14' and the recess 12A'.

[0073] 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. At this time, the rotational force applied to the key 14' can be received by the wall surfaces on both sides of the recess 12A' formed in the nut 12.

[0074] The support members 15A and 15B support the key 14' so as to be able to transmit the axial force from the intermediate member 17 to the output shaft 13 while enabling the release of the connection between the nut 12 and the output shaft 13. 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 a part of the side surface 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.

[0075] Here, by setting the strength of the support members 15A and 15B such that the support members 15A and 15B break based on the load applied to the key 14', the connection between the nut 12 and the output shaft 13 can be released. 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, during the normal operation of the actuator, the connection between the nut 12 and the output shaft 13 is not released, and the strength of the support members 15A and 15B can be set such that the connection between the nut 12 and the output shaft 13 is released when a load greater than the normal operation of the actuator EA2 is applied to the key 14'. Also, by setting the strength of the support members 15A and 15B such 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 either the forward or backward direction of the output shaft 13.

[0076] The insertion portion 17A' is provided between the support members 15A and 15B and the key 14' can be inserted therein. 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' such that the connection between the nut 12 and the output shaft 13 can be released while the axial force can be transmitted from the intermediate member 17 to the output shaft 13.

[0077] The groove 17B' allows the key 14' to move axially. The groove 17B' can be arranged to be axially continuous with the insertion portion 17A' via the support member 15B. The groove 17B' allows the key 14' to escape axially when the support member 15B breaks.

[0078] The through-hole 13A' accommodates the rear end portion of the key 14'. The through-hole 13A' can be provided on the side surface of the output shaft 13. At this time, the key 14' can be inserted into the insertion portion 17A' via the through-hole 13A'.

[0079] 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 bodies. For example, they may be metals such as iron or aluminum alloys, or non-metals such as ceramics.

[0080] Here, by making it possible to couple the nut 12 and the output shaft 13 via the intermediate member 17, the coupling position of the nut 12 and the coupling position of the output shaft 13 can be set separately. For this reason, the degree of freedom in the design of the positions, sizes, and shapes of the nut 12 and the output shaft 13 can be improved, and for the nut 12 or the output shaft 13, miniaturization, weight reduction, cost reduction, simplification of processing, or improvement in assemblability can be achieved.

[0081] Figs. 5(a) and 5(b) are cross-sectional views showing the axial force transmission path of the actuator according to the second embodiment. Note that Fig. 5(a) is a cross-sectional view cut at the position of the cotter 14 along the axial direction of the actuator, and Fig. 5(b) is a cross-sectional view cut at the position of the key 14' along the axial direction of the actuator.

[0082] In Figs. 5(a) and 5(b), one end of the screw shaft 11 is connected to the gear G3. The gear G3 is rotatably supported by the housing G2 via the bearing G1 and is axially fixed by the gear fixing nut G4. The bearing G1 is, for example, an angular ball bearing.

[0083] As shown in Fig. 5(a), the rotational force F1 generated from a drive source such as a motor is input to the screw shaft 11, and the screw shaft 11 is rotated. When the screw shaft 11 rotates, the nut 12 moves in a linear motion. Then, the 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, as shown in Fig. 5(b), the axial force F2 is transmitted from the intermediate member 17 to the output shaft 13 and is output via the output shaft 13.

[0084] FIG. 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 retreats, FIG. 6(b) is a cross-sectional view showing the fracture state of the support member based on the external force in FIG. 6(a), FIG. 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 advances, and FIG. 6(d) is a cross-sectional view showing the fracture state of the support member based on the external force in FIG. 6(c). Note that FIGS. 6(a) to 6(d) are cross-sectional views cut at the position of key 14' along the axial direction of the actuator.

[0085] In FIG. 6(a), it is assumed that the movement of nut 12 is restricted according to the fixed state or load state of the power transmission system such as a motor, a gear, or a linear motion part. When the screw of the ball screw part is fixed, the nut 12 is jammed, or the power transmission system is fixed at each part such as the ball circulator 6 being pinched, power cannot be transmitted from the motor and the reduction part, and linear output from the output shaft 3 becomes impossible. At this time, when an external force F11 is applied in the retreat direction of the output shaft 13, the external force F11 is applied to key 14' via the output shaft 13. The external force F11 applied to key 14' is applied to the support member 15A. When the load applied to key 14' exceeds a predetermined value, the support member 15A cannot withstand the load, and as shown in FIG. 6(b), the support member 15A breaks.

[0086] Also, in FIG. 6(c), when an external force F12 is applied in the advance direction of the output shaft 13, the external force F12 is applied to key 14' via the output shaft 13. The external force F12 applied to key 14' is applied to the support member 15B. When the load applied to key 14' exceeds a predetermined value, the support member 15B cannot withstand the load, and as shown in FIG. 6(d), the support member 15B breaks.

[0087] 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 movement 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 restraint of the output shaft 13 due to the fixation of the power transmission system is released, and the actuator EA2 becomes in a free state. Therefore, when the actuator EA2 is installed between the vehicle 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 vehicle body 52 via the actuator EA2 when the power transmission system is fixed, and the riding comfort of the railway vehicle can be improved. Note that the broken support members 15A and 15B can be held inside the actuator EA2, and it is possible to prevent the broken support members 15A and 15B from scattering outside the actuator EA2.

[0088] FIG. 7 is a perspective view showing an exploded configuration of an actuator after mounting a cotter, a key, and an intermediate member according to the third embodiment. In FIG. 7, this actuator EA3 includes an intermediate member 27 instead of the intermediate member 17 of the actuator EA2 in FIG. 4(b). Further, this actuator EA3 includes elastic members 25A and 25B in addition to the configuration of the actuator EA2 in FIG. 4(b).

[0089] The intermediate member 27 mediates the connection between the nut 12 and the output shaft 13 while being able to reversibly release the connection between the nut 12 and the output shaft 13. The shape of the intermediate member 27 is, for example, cylindrical. The intermediate member 27 can be inserted into the output shaft 13 along the axial direction. Further, the intermediate member 27 can be inserted with the nut 12 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.

[0090] Note that the cotter 14 is used as a first coupling member that couples the nut 12 and the intermediate member 27. Further, the key 14' is used as a second coupling member that couples the intermediate member 27 and the output shaft 13.

[0091] 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 in a state of being fitted into the intermediate member 27. This spring is, for example, a thin plate spring bent in the middle.

[0092] The intermediate member 27 includes through holes 27A, 27A' and a groove 27B'. The through hole 27A accommodates the rear end portion of the cotter 14. The through hole 27A can be provided on the side surface of the intermediate member 27.

[0093] The through hole 27A' can fit the elastic members 25A and 25B. By fitting the elastic members 25A and 25B into the through hole 27A' so that the key 14' inserted into the through hole 27A' is sandwiched from both sides, the elastic members 25A and 25B can support the key 14' so as to be able to transmit an axial force from the intermediate member 27 to the output shaft 13 while enabling the release of the connection between the nut 12 and the output shaft 13.

[0094] 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 surface of the key 14' from both sides so as to be detachable along the groove 27B'.

[0095] Here, by setting the strength of the elastic members 25A and 25B such that the elastic members 25A and 25B disengage based on the load applied to the key 14', the connection between the nut 12 and the output shaft 13 can be released. 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 connection between the nut 12 and the output shaft 13 is not released during the normal operation of the actuator EA3, and the strength of the elastic members 25A and 25B can be set such that the connection between the nut 12 and the output shaft 13 is released when a load greater than the normal operation of the actuator EA3 is applied to the key 14'. Further, by setting the strength of the elastic members 25A and 25B such that the elastic members 25A and 25B can be disengaged, the connection between the nut 12 and the output shaft 13 can be released in either the forward or backward direction of the output shaft 13.

[0096] The groove 27B' can axially move the key 14' and the elastic members 25A and 25B. The groove 27B' can axially release the key 14' and the elastic members 25A and 25B when the elastic members 25A and 25B are disengaged.

[0097] Here, by using the elastic members 25A and 25B to support the key 14' with the intermediate member 27, it is not necessary to drive the key 14' into the nut 12 to fix the key 14' to the nut 12 via the output shaft 13. For this reason, it is possible to prevent the nut 12 from being damaged when fixing the key 14' to the nut 12, and it is possible to easily extract the key 14' from the nut 12, facilitating the release of the connection between the nut 12 and the output shaft 13.

[0098] FIG. 8(a) is a cross-sectional view showing the configuration of the nut portion of the linear motion device according to 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 at the time of spring disengagement of FIG. 8(b). Note that FIG. 8(a) is a cross-sectional view taken at the position of the key 14' along the axial direction of the actuator.

[0099] In FIGS. 8(a) and 8(b), with the key 14' inserted into the through-hole 27A', the key 14' is sandwiched from both sides by the elastic members 25A and 25B. Thereby, the elastic members 25A and 25B can support the key 14' so as to be able to transmit an axial force from the intermediate member 27 to the output shaft 13 while enabling the release of the connection between the nut 12 and the output shaft 13.

[0100] In FIG. 8(c), it is assumed that the movement of the nut 12 is restricted according to the fixed state or load state of the power transmission system such as a motor, a gear, or a linear motion component. At this time, when an external force is applied in the retraction 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 applied to the key 14' exceeds a predetermined value, the elastic member 25A can no longer receive the load, and the elastic member 25A and the key 14' are disengaged.

[0101] Also, 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 applied to the key 14' exceeds a predetermined value, the elastic member 25B can no longer receive the load, and the elastic member 25B and the key 14' are disengaged.

[0102] When the elastic members 25A, 25B, and the key 14' are disengaged, 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 it is possible to prevent the movement of the output shaft 13 from being restricted via the nut 12.

[0103] FIGS. 9(a) and 9(b) are cross-sectional views showing the configuration of the actuator according to the fourth embodiment. Note that FIG. 9(a) is a cross-sectional view taken at the position of the cotter 14 along the axial direction of the actuator, and FIG. 9(b) is a cross-sectional view taken at the position of the key 14' along the axial direction of the actuator.

[0104] In FIGS. 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 a 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 interval between the key 14' and the cotter 14.

[0105] The shapes of the output shaft 33 and the intermediate member 37 are, for example, cylindrical. The intermediate member 37 can be inserted into the output shaft 33 along the axial direction. Also, the intermediate member 37 can be inserted into the nut 32 along the axial direction.

[0106] Note that the cotter 14 is used as a first coupling member that couples the nut 32 and the intermediate member 37. Also, the key 14' is used as a second coupling member that couples the intermediate member 37 and the output shaft 33.

[0107] Also, in the nut 32 and the intermediate member 37, the axial position of the key 14' is closer to the output shaft 33 side than the axial position of the cotter 14. Also, the intermediate member 37 extends axially from the nut 32 toward the output shaft 33. The length of the output shaft 33 is shortened so that the cotter 14 is exposed.

[0108] For example, as shown in FIGS. 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.

[0109] In contrast, as shown in FIGS. 9(a) and 9(b), in the actuator EA4, with respect to the position of the axial end face E1 on the gear G3 side of the nut 32, 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. 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.

[0110] Also, in the actuator EA4, with respect to the position of the axial end face E3 on the output shaft 33 side of the nut 32, 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. At this time, the position of the key 14' can be set so as to bear on the axial end face E3 on the output shaft 33 side of the nut 32.

[0111] The output shaft 33 is provided with a through hole 33A'. The intermediate member 37 is provided with 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 manner as the through hole 13A', support members 15A, 15B and groove 17B' of the actuator EA2, except that their positions are different. However, the length of the groove 37B' can be adjusted corresponding to the extension length of the intermediate member 37 toward the output shaft side.

[0112] Here, by using the intermediate member 37 for the connection between the nut 32 and the output shaft 33 and shifting the axial position of the key 14' closer to the output shaft 33 side compared to the axial position of the cotter 14, the nut 32 and the output shaft 33 can be connected without extending the output shaft 33 to the position of the cotter 14. For this reason, it is possible to shorten the output shaft 33 without reducing the axial stroke amount of the actuator EA4, and there is no need to provide a through hole for inserting the cotter 14 in the output shaft 33, thereby achieving miniaturization, weight reduction, low cost, simplified machining, high durability and improved assemblability of the output shaft 33.

[0113] FIG. 10(a) is a perspective view showing an exploded configuration of an actuator before mounting a cottar, a key, and an intermediate member according to the fifth embodiment, and FIG. 10(b) is a perspective view showing an exploded configuration of the actuator after mounting the cottar, the key, and the intermediate member according to the fifth embodiment. In FIGS. 10(a) and 10(b), this actuator EA5 includes an intermediate member 47 instead of the intermediate member 17 of the actuator EA2 in FIG. 4(b).

[0114] The intermediate member 47 mediates the connection between the nut 12 and the output shaft 13. The intermediate member 47 includes through holes 47A, 47A'. The through hole 47A accommodates the rear end portion of the cottar 14. The through hole 47A can be provided on the side surface of the intermediate member 47. At this time, the tip portion of the cottar 14 can be accommodated in the recess 12A through the through hole 47A. The through hole 47A' accommodates the intermediate portion of the key 14'. The through hole 47A' can be provided on the side surface of the intermediate member 47. At this time, the tip portion of the key 14' can be accommodated in the recess 12A' through the through hole 47A'. The rear end portion of the key 14' is accommodated in the through hole 13A'.

[0115] Note that the cottar 14 is used as a first coupling member that couples the nut 12 and the intermediate member 47. Also, the key 14' is used as a second coupling member that couples the intermediate member 47 and the output shaft 13.

[0116] Here, by enabling the connection between 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. For this reason, the degree of freedom in design such as the position, size, and shape of the nut 12 and the output shaft 13 can be improved, and for the nut 12 or the output shaft 13, miniaturization, weight reduction, cost reduction, simplification of processing, or improvement in assemblability can be achieved.

[0117] Further, by inserting the cotter 14, the nut 12 and the intermediate member 47 can be coupled, and by inserting the key 14', the output shaft 13 and the intermediate member 47 can be coupled. Therefore, in order to couple the nut 12 and the output shaft 13, it is not necessary to use a complicated configuration such as a gripping mechanism or a clutch mechanism, and while suppressing the increase in size and cost of the actuator EA5, the degrees of freedom in the design of the positions, sizes, shapes, etc. of the nut 12 and the output shaft 13 can be improved.

[0118] FIG. 11 is a perspective view showing an exploded configuration of an 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 in FIG. 1. Further, this actuator EA5 includes elastic members 55, 55' in addition to the configuration of the actuator EA1 in FIG. 1.

[0119] The nut 52 converts the rotational motion of the screw shaft 1 into a linear motion in the axial direction of the screw shaft 1 while being able to reversibly release the coupling between the nut 2 and the output shaft 3. The nut 52 includes recesses 52A, 52A'.

[0120] The recess 52A houses 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 as to be sandwiched by the elastic member 55 around it. 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 static frictional force acts between the recess 52A and the elastic member 55 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.

[0121] 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 an interval 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 as to be sandwiched by the elastic member 55' around it. 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 along the axial direction on the nut 2 so that static frictional force acts between the recess 52A' and the elastic member 55' 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.

[0122] 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 around it in a state of being fitted into the nut 52. This spring is, for example, a thin plate spring that is bent so as to surround the cotter 4 while being stretchable in the longitudinal direction of the cotter 4. When this spring extends in the longitudinal direction of the cotter 4, it narrows in the short direction of the cotter 4, and when it contracts in the longitudinal direction of the cotter 4, it can expand in the short direction of the cotter 4. At this time, by fitting the elastic member 55 into the recess 52A in a state of sandwiching the cotter 4 from around it, static friction can act between the cotter 4 and the nut 52, and the cotter 4 can be prevented from coming out of the recess 52A.

[0123] 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 surroundings in a state of being fitted into the nut 52. This spring is, for example, a thin plate spring that is bent so as to surround the key 4' while being stretchable in the longitudinal direction of the key 4'. When this spring extends in the longitudinal direction of the key 4', it narrows in the short direction of the key 4', and when it contracts in the longitudinal direction of the key 4', it can expand in the short direction of the key 4'. At this time, the elastic member 55' can be fitted into the recess 52A' while sandwiching the key 4' from the surroundings, so that static friction can act between the key 4' and the nut 52, and the key 4' can be prevented from coming out of the recess 52A'.

[0124] Here, in order to support the cotter 4 and the key 4' with the nut 52, by using the elastic members 55, 55', it is no longer necessary to drive the cotter 4 and the key 4' into the nut 52 in order to fix the cotter 4 and the key 4' to the nut 52 via the output shaft 3. For this reason, it is possible to prevent the nut 52 from being damaged when fixing the cotter 4 and the key 4' to the nut 52, and it is possible to make it easier to extract the cotter 4 and the key 4' from the nut 52, facilitating the replacement of the cotter 4 and the key 4' and the release of the connection between the nut 52 and the output shaft 3.

[0125] Furthermore, by fitting the elastic members 55, 55' into the nut 52 with the cotter 4 and the key 4' inserted into the nut 52, it is possible to prevent the cotter 4 and the key 4' from falling out of the nut 52, and it is possible to make it easier to remove the cotter 4 and the key 4' from the nut 52.

[0126] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to the above-described embodiments and includes various modifications. For example, it is possible to replace a 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. Further, for a part of the configuration of each embodiment, it is possible to add, delete, or replace with other configurations.

[0127] For example, in the actuators EA2 of FIGS. 4(a) and 4(b), an example is shown in which support members 15A and 15B capable of releasing the connection between the nut 12 and the output shaft 13 are provided on the key 14' side. However, support members capable of releasing the connection between the nut 12 and the output shaft 13 may be provided on the cotter 14 side.

[0128] Further, in the actuator EA3 of FIG. 7, an example is shown in which the key 14' is supported by elastic members 25A and 25B in order to make the connection between the nut 12 and the output shaft 13 releasable. However, the cotter 14 may be supported by an elastic member.

Explanation of Reference Numerals

[0129] 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

1. A screw shaft, a nut that converts the rotational movement of the screw shaft into linear movement 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 movement converted by the nut, a support member that supports the coupling member so as to be able to transmit the axial force from the nut to the output shaft while enabling the release of the coupling between the nut and the output shaft, and an intermediate member that mediates the coupling between the nut and the output shaft, wherein the coupling member, comprises a first coupling member that couples the nut and the intermediate member, and a second coupling member that couples the intermediate member and the output shaft, and the support member is provided on the intermediate member, a linear motion device characterized by this.

2. The intermediate member extends in the axial direction of the output shaft from the nut, The linear motion device according to claim 1, wherein the axial position of the second coupling member is closer to the output shaft side than the axial position of the first coupling member.

3. The linear motion device according to claim 1 or 2, wherein the support member releases the coupling between the nut and the output shaft based on the load applied to the coupling member.

4. The linear motion device according to claim 3, wherein the support member is breakable or detachable based on the load applied to the coupling member.

5. The linear motion device according to any one of claims 1 to 4, wherein the support member can release the coupling in either the forward or backward direction of the output shaft.

6. The first coupling member can be inserted into the nut through the intermediate member in a direction orthogonal to the axial direction of the screw shaft, The linear motion device according to any one of claims 1 to 5, wherein the second coupling member can be inserted into the intermediate member through the output shaft in a direction orthogonal to the axial direction of the screw shaft.

7. The linear motion device according to any one of claims 1 to 6, wherein the support member is provided on the nut.

8. The linear motion device according to any one of claims 1 to 7, wherein the strength of the support member is set based on the load required to release the coupling.

9. The linear motion device according to any one of claims 1 to 8, 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.

10. 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, An intermediate member that mediates the coupling between the nut and the output shaft, The coupling member, A first coupling member that couples the nut and the intermediate member, A linear motion device characterized by comprising a second coupling member that couples the intermediate member and the output shaft.

11. The first coupling member can be inserted into the nut through 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 can be inserted into the intermediate member through the output shaft in a direction perpendicular to the axial direction of the screw shaft.

12. A linear motion device according to any one of claims 1 to 11, An actuator characterized by comprising the output shaft.

Images