Actuator and vehicle tilting system

Abstract

In linear-movement actuators, the screw mechanism is protected from external forces. [Solution] The actuator comprises a motor, a screw shaft that rotates when rotational force is transmitted from the motor, a nut that moves linearly along the screw shaft as the screw shaft rotates, an output rod that moves linearly in response to the force of the linear movement of the nut, a main body housing that holds the output rod in a state where it can move linearly, and a locking mechanism that locks the movement of the output rod relative to the main body housing when an external force is applied to the output rod, and releases the lock when a force is applied to the output rod from the nut side.

Description

Technical Field

[0001] The present invention relates to an actuator and a vehicle body tilting system.

Background Art

[0002] Conventionally, a linear actuator is known and is used, for example, in a vehicle body tilting system that controls the tilting of a vehicle body in a railway vehicle or an automobile. The actuator moves a moving object such as a vehicle body with the force output from the output shaft, but an external force may be applied to the output shaft of the actuator due to the swaying of the moving object. Therefore, for the purpose of protecting the motor from the external force, an actuator provided with a reverse input blocking device that blocks the external force applied to the output shaft has been proposed (for example, Patent Document 1, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the actuators described in Patent Document 1 and Patent Document 2, although the motor is protected, an external force acts on the screw mechanism that converts the rotational motion of the motor into a linear motion, and the screw mechanism is not protected. Therefore, an object of the present invention is to protect a screw mechanism from an external force in a linear motion type actuator.

Means for Solving the Problems

[0005] To solve the above problems, one embodiment of the actuator according to the present invention comprises a motor, a screw shaft that rotates when rotational force is transmitted from the motor, a nut that moves linearly along the screw shaft as the screw shaft rotates, an output rod that moves linearly in response to the force of the linear movement of the nut, a main body housing that holds the output rod in a state that allows for linear movement, and a locking mechanism that locks the movement of the output rod relative to the main body housing when an external force is applied to the output rod, and releases the lock when a force is applied to the output rod from the nut side.

[0006] With such an actuator, the external force applied to the output rod is transmitted to the main housing via a locking mechanism, thus protecting the screw mechanism, which consists of a nut and a screw shaft, from external forces. In the actuator described above, the locking mechanism preferably comprises a first locking part that can lock only the forward movement of the output rod in its linear movement, a second locking part that can lock only the backward movement, and a release part that releases the lock of the first locking part when the nut moves forward and releases the lock of the second locking part when the nut moves backward.

[0007] With such an actuator, the structure of the locking mechanism is simplified by the division of roles between the first locking part and the second locking part. Furthermore, in the actuator described above, it is preferable that the first locking portion and the second locking portion are positioned between the output rod and the main body housing. This arrangement of the locking portions suppresses an increase in the dimensions of the actuator.

[0008] Furthermore, in the actuator described above, the release portion comprises a pin protruding from the nut, a first release member incorporated into the first lock portion which releases the lock of the first lock portion by the force applied by the pin, and a second release member incorporated into the second lock portion which releases the lock of the second lock portion by the force applied by the pin. Preferably, the first lock portion is positioned in front of the pin, and the second lock portion is positioned behind the pin.

[0009] With this type of actuator configuration, unlocking becomes possible through a simple structure in which a pin pushes a release member. Furthermore, in the actuator described above, the first locking portion and the second locking portion each include a ball positioned between the output rod and the main body housing, and a cam surface that forms a gap in which the ball is sandwiched, with one side being narrower than the other being the front and rear, and the ball moves to the one side and fits into the gap, thereby locking the movement of the output rod. The first release member and the second release member preferably release the lock by being pushed by the pin, which moves the ball toward the wider side of the gap.

[0010] With this type of actuator configuration, the locking mechanism has a simple structure consisting of a ball and a cam surface, resulting in high robustness. To solve the above problems, the vehicle body tilting system according to the present invention comprises an actuator that changes the tilt of the vehicle body, and a control unit that controls the tilt of the vehicle body by controlling the actuator. Such a vehicle body tilting system allows for energy savings and protection of the screw mechanism while maintaining the vehicle body's tilt. [Effects of the Invention]

[0011] According to the present invention, the screw mechanism in a linear-movement actuator can be protected from external forces. [Brief explanation of the drawing]

[0012] [Figure 1] This is a functional block diagram showing a railway vehicle incorporating one embodiment of the vehicle body tilting system of the present invention. [Figure 2] This is a structural conceptual diagram showing a railway vehicle incorporating one embodiment of the vehicle body tilting system of the present invention. [Figure 3] This is a cross-sectional view showing the structure of an electric actuator. [Figure 4] This is a magnified view of a portion of the locking mechanism. [Figure 5] This diagram shows a cam component and a ball. [Figure 6] This is a magnified view showing the cam component and ball. [Figure 7] This diagram shows the operation of the retainer. [Figure 8] This diagram shows the state in which an external force is applied to the output rod. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. However, in order to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. In addition, elements described in the previously mentioned drawings may be referred to as appropriate in the subsequent descriptions of the drawings.

[0014] Figures 1 and 2 schematically show a railway vehicle incorporating one embodiment of the vehicle body tilting system of the present invention. Figure 1 shows a functional block diagram, and Figure 2 shows a structural conceptual diagram. The railway vehicle 1000 has a car body 100 and a bogie 200, and a car body tilting system 300 is provided between the car body 100 and the bogie 200. Any type of car body tilting system 300 may be adopted, such as a controlled natural pendulum type, a forced car body tilting type, an air spring type with an actuator, or a hybrid car body tilting system that combines a pendulum type and an air spring type. This car body tilting system 300 corresponds to one embodiment of the car body tilting system of the present invention.

[0015] The car body tilting system 300 includes a car body tilting mechanism 310, an ECU (Electronic Control Unit) 320, a car body tilting control device 330, and a sensor 340. The car body tilting mechanism 310 is a mechanism that changes and maintains the tilt of the car body 100 with respect to the bogie 200 by means of an electric actuator 350. The electric actuator 350 corresponds to an embodiment of the actuator of the present invention. As the sensor 340, for example, an acceleration sensor, a gyro sensor, and a speed sensor are mainly used.

[0016] The car body tilting control device 330 calculates a desired tilt of the car body 100 based on the running information of the railway vehicle 1000 obtained by the sensor 340, and issues a command to the ECU 320 so as to achieve the calculated car body tilt. By the ECU 320 controlling the electric actuator 350 to drive the car body tilting mechanism 310, the desired car body tilt is realized. The car body tilting control device 330 corresponds to an example of the control unit in the present invention that controls the tilt of the car body by controlling the electric actuator 350.

[0017] A lock mechanism 360 is incorporated in the electric actuator 350. As will be described in detail later, protection of the screw mechanism in the electric actuator 350 is achieved, and energy saving is also achieved for maintaining the tilt of the car body 100. Hereinafter, the detailed structure of the electric actuator 350 will be described.

[0018] FIG. 3 is a cross-sectional view showing the structure of the electric actuator 350. FIG. 3 shows a cross-section cut along the plane centered on the output shaft of the electric actuator 350. Also, for some elements, for convenience of understanding, the appearance rather than the cross-section is shown. The electric actuator 350 of the present embodiment is a ball screw type linear motion actuator that uses a ball screw as a screw mechanism for converting rotational motion into linear motion, and converts the rotational force input from the motor into an axial force in the direction along the rotation axis and outputs it.

[0019] In this embodiment, the electric actuator 350 is connected to two connectors 61 and 62, with one connector 61 fixed to, for example, the bogie 200 side and the other connector 62 fixed to, for example, the vehicle body 100 side. The electric actuator 350 can change the inclination of the vehicle body 100 by changing the distance between the two connectors 61 and 62.

[0020] The electric actuator 350 of this embodiment comprises a ball screw 10, a reduction gear 20, an input rotating shaft 22, an output rod 30, a main body housing 40, a ball bearing 51, a bearing housing 50, a locking mechanism 360, and a motor 60. The output rod 30 corresponds to an example of an output rod as defined in the present invention, the main body housing 40 corresponds to an example of a main body housing as defined in the present invention, and the locking mechanism 360 corresponds to an example of a locking mechanism as defined in the present invention. The reducer 20 receives rotational force from the motor 60, increases the rotational force by reducing the rotational speed via multiple gears 23 and 24, and transmits the rotational force to the input side rotating shaft 22. The input side rotating shaft 22 is connected to the screw shaft 11 of the ball screw 10, and the rotational force transmitted to the input side rotating shaft 22 is directly transmitted to the screw shaft 11 of the ball screw 10.

[0021] The ball screw 10 converts the rotational motion of the screw shaft 11, caused by the rotational force transmitted via the input side rotating shaft 22, into the linear motion of the nut 13. The locking mechanism 360 is positioned between the main body housing 40 and the output rod 30, and when the axial force converted from the rotational force by the ball screw 10 is transmitted to the output rod 30, it unlocks the output rod 30 from the main body housing 40. The output rod 30 outputs the transmitted axial force, which is transmitted to the car body 100 and the bogie 200 via two connectors 61 and 62, thereby changing the inclination of the car body 100 relative to the bogie 200.

[0022] The main housing 40 is a substantially cylindrical member that encloses the ball screw 10, the locking mechanism 350, and the output rod 30, and holds the entire electric actuator 350. The main housing 40 holds the output rod 30 via a bearing 52 in a state that allows for linear movement in the axial direction. In this specification, unless otherwise specified, the axial direction refers to the direction in which the screw shaft 11 extends. Also, in this specification, the direction in which the output rod 30 extends out of the main housing 40 is conveniently referred to as "forward," and the direction in which the output rod 30 enters the main housing 40 is conveniently referred to as "rear."

[0023] The ball bearing 51 rotatably holds the screw shaft 11 and the input side rotating shaft 22 of the ball screw 10. The bearing housing 50 fixes the ball bearing 51 to the main housing 40. Therefore, the main housing 40 rotatably holds the screw shaft 11 via the bearing housing 50 and the ball bearing 51.

[0024] The ball screw 10 is an example of a screw mechanism and comprises a screw shaft 11 and a nut 13. The screw shaft 11 of the ball screw 10 corresponds to an example of a screw shaft as defined in the present invention, and the nut 13 of the ball screw 10 corresponds to an example of a nut as defined in the present invention. The screw shaft 11 has a helical screw groove 11a on its outer circumference, and the nut 13 has a helical screw groove (not shown) on its inner circumference that is opposite to the screw groove 11a of the screw shaft 11. Multiple balls (not shown) are loaded to roll freely within the helical ball rolling path formed by both screw grooves.

[0025] The ball screw 10 also includes a ball circulation path (not shown) that returns the balls from the end point to the starting point of the ball rolling path, thus circulating them. The materials of the screw shaft 11, nut 13, and balls are not particularly limited, and common materials can be used, such as metals like steel or ceramics. The cross-sectional shape of the screw groove may be arc-shaped or Gothic arc-shaped.

[0026] When the ball screw 10 is rotated relative to the nut 13 and the screw shaft 11, which are indirectly engaged via the balls, the screw shaft 11 and the nut 13 move linearly relative to each other in the axial direction via the rolling of the balls. An endless ball passage is formed by the ball rolling path and the ball circulation path, and since the balls circulate infinitely within the ball passage, the screw shaft 11 and the nut 13 can move linearly continuously. The direction of linear movement of the nut 13 is determined by the direction of rotation of the screw shaft 11.

[0027] When the nut 13 moves linearly, the axial force is transmitted to the output rod 30 via the pin 365 (described later), and the output rod 30 moves linearly together with the nut 13, so that the axial force is output from the output shaft 30. However, the nut 13 is not fixed to the output rod 30, but is held by the inner wall of the output rod 30 via the bearing 53, so it is possible for the nut 13 to move slightly linearly in the axial direction relative to the output rod 30.

[0028] The ball screw 10 offers excellent power transmission efficiency, responsiveness, and precision, with over 90% of the rotational force input to the screw shaft 11 being output as linear movement of the output rod 30. However, if an external force is applied to the output rod 30 and transmitted to the ball screw 10, energy will be consumed to maintain the inclination of the vehicle body 100. Furthermore, there is a risk that the ball screw 10 may be damaged by the external force.

[0029] Therefore, the electric actuator 350 is equipped with a locking mechanism 360 between the main housing 40 and the output rod 30, and the external force applied to the output rod 30 is transmitted to the housing by the locking mechanism 360. The locking mechanism 360 transmits external forces from the output rod 30 side to the main housing 40 regardless of whether the rod moves forward or backward in the axial direction. On the other hand, the locking mechanism 360 releases the lock when axial force is applied from the nut 13 side, and transmits the axial force regardless of whether it is forward or backward in the axial direction to the output rod 30 side.

[0030] The locking mechanism 360 transmits external forces such as vibrations of the vehicle body 100 to the main housing 40, protecting the ball screw 10. Furthermore, the motor does not need to be driven when maintaining the tilt of the vehicle body 100, resulting in energy savings. In addition, the electric actuator 350 equipped with the locking mechanism 360 has a compact configuration and requires less installation space compared to hydraulic actuators, thus saving space. Moreover, the electric actuator 350 does not require lubrication and does not leak oil, making maintenance easier compared to hydraulic actuators.

[0031] Next, we will describe the detailed structure of the locking mechanism 360. Figure 4 is a partially enlarged view showing the locking mechanism 360. Multiple locking mechanisms 360 are provided around the nut 13, and in this embodiment, as an example, two locking mechanisms 360 are provided. The number of locking mechanisms 360 may depend on the strength and balance of the lock, and may be provided, for example, at each of the four directions surrounding the nut 13 (4 locations), or at six or eight locations. Alternatively, locking mechanisms 360 may be provided at each of the odd-numbered directions surrounding the nut 13 (for example, at three, five, or seven locations).

[0032] Each locking mechanism 360 comprises a first locking portion 361 positioned on the front side and a second locking portion 362 positioned on the rear side. Between the first locking portion 361 and the second locking portion 362 is a pin 365 fixed to a nut 13 and protruding from the nut 13. The pin 365 passes through a through hole 30a in the output rod 30 and protrudes to the outer circumference of the output rod 30. When the nut 13 moves linearly, the pin 365 contacts the inner wall of the through hole 30a, and axial force is transmitted to the output rod 30. The through hole 30a is larger than the pin 365, and a radial gap is provided between the nut 13 and the output rod 30.

[0033] The first locking part 361 locks the output rod 30 to move forward relative to the main housing 40, and the second locking part 362 locks the output rod 30 to move backward relative to the main housing 40. The direction in which the first locking part 361 and the second locking part 362 lock the output rod 30 relative to the main housing 40 is sometimes referred to as the locking direction of each locking part 361 and 362. That is, the first locking part 361 locks forward, and the second locking part 362 locks backward.

[0034] The first locking section 361 and the second locking section 362 release the lock when the output rod 30 moves in the opposite direction to the locking direction. By providing a first locking section 361 and a second locking section 362 with different locking directions and dividing their roles, the structure of the locking mechanism 360 is simplified, and space saving and robustness are also improved. Furthermore, since the first locking section 361 and the second locking section 362 are positioned between the main body housing 40 and the output rod 30, the increase in the dimensions of the electric actuator 350 is suppressed.

[0035] The first locking portion 361 comprises a cam member 363, a ball 364, and a retainer 366, and the second locking portion 362 also comprises a cam member 363, a ball 364, and a retainer 366. The retainer 366 corresponds to an example of a release member as defined in the present invention, and the retainer 366 and pin 365 together correspond to an example of a release portion as defined in the present invention. The cam member 363 is fixed to the outer circumference of the output rod 30 and faces the inner circumferential surface of the main housing 40. The ball 364 is sandwiched between the main housing 40 and the cam member 363.

[0036] Figures 5 and 6 illustrate the locking operation by the cam member 363 and the ball 364, with Figure 6 being a schematic partial enlargement. In this embodiment, the first locking portion 361 and the second locking portion 362 each have, for example, four balls 364, and the cam member 363 is provided with cam surfaces 363a corresponding to each ball 364. The number of balls 364 and cam surfaces 363a can be selected according to the strength of the lock, etc.

[0037] The cam member 363 forms a gap between itself and the main body housing 40 via the cam surface 363a, and the balls 364 are housed in each of these gaps. The gap formed by the cam surface 363a is wider on the side in the locking direction and narrower on the side in the opposite direction to the locking direction.

[0038] As indicated by arrow F in Figure 6, when the output rod 30 moves forward, the cam member 363 in the first locking part 361 moves in the locking direction. Consequently, in the first locking part 361, the ball 364 is clamped between the cam surface 363a and the main body housing 40, and the output rod 30 is locked to the main body housing 40. On the other hand, in the second locking section 362, the cam member 363 moves in the opposite direction to the locking direction. Therefore, in the second locking section 362, the ball 364 moves to the wider gap, and the lock is released. The structure in which locking and unlocking are performed by the ball 364 and the cam surface 363a is simple and highly robust.

[0039] When the output rod 30 moves to the rear, the lock is released by the first locking part 361 and locked by the second locking part 362, the opposite of the state in Figure 6. In other words, whether the output rod 30 moves forward or backward, it is locked by one of the first locking part 361 or the second locking part 362 and unlocked by the other.

[0040] Figure 7 shows the operation of the retainer 366. The upper part of Figure 7 shows a view of the retainer 366 from above, and the lower part shows a view of the retainer 366 from the side. The retainer 366 has, for example, a hole 366a in which the ball 364 is housed. When the pin 365 moves in conjunction with the movement of the nut 13, the ball 364 is pushed by the pin 365, pushing it in the direction that widens the gap between the cam surface 363a and the main housing 40. As a result, the locking parts 361 and 362, which are pressed by the pin 365 on the retainer 366, are released. The play provided between the nut 13 and the output rod 30 allows the pin 365 to move in order to push the retainer 366. In this embodiment, the lock can be released by a simple structure in which the pin 365 presses against the retainer 366.

[0041] For example, if the nut 13 moves forward as indicated by arrow F in Figure 7, the output rod 30 also moves forward along with the movement of the nut 13, and the cam member 363 moves in the locking direction in the first locking part 361. However, since the pin 365 pushes the retainer 366 of the first locking part 361, the lock of the first locking part 361 is released. On the other hand, in the second locking part 362, the retainer 366 is not pushed, but the cam member 363 moves in the opposite direction to the locking direction, so the lock is released.

[0042] In other words, when the axial force is transmitted to the output rod 30 by the movement of the nut 13, both the first locking part 361 and the second locking part 362 are released, so the output rod 30 can output the axial force. The same applies when the direction of movement of the nut 13 is backward, opposite to the direction shown in Figure 7. That is, the lock on the first locking part 361 is released because the direction of movement is opposite to the locking direction, and the lock on the second locking part 362 is released because although the direction of movement is the locking direction, the retainer 366 is pushed by the pin 365. Therefore, no matter whether the nut 13 moves in the forward or backward direction, the lock is released at both the first locking part 361 and the second locking part 362, and the output rod 30 can output axial force.

[0043] Figure 8 shows the state in which an external force is applied to the output rod 30. The upper part of Figure 8 shows a view of the retainer 366 from above, and the lower part shows a view of the retainer 366 from the side. When the output rod 30 moves to the rear side indicated by arrow B in Figure 8 due to an external force, the cam member 363 in the first locking part 361 moves in the opposite direction to the locking direction. Also, as the output rod 30 moves, the pin 365 comes into contact with the retainer 366 of the first locking part 361. Therefore, the lock in the first locking part 361 is released.

[0044] On the other hand, in the second locking part 362, the cam member 363 moves in the locking direction, and the retainer 366 is not pushed by the pin 365, so the output rod 30 is locked to the main housing 40 by the second locking part 362. In other words, when an external force is applied to the output rod 30, the external force is transmitted from the output rod 30 to the main housing 40, and the ball screw 10 is protected from the external force. The same applies when the direction of movement of the output rod 30 due to external force is forward, opposite to the direction shown in Figure 8. That is, in the second locking part 362, the direction of movement is opposite to the locking direction and the pin 365 also contacts the retainer 366, so the lock is released, while in the first locking part 361, the direction of movement is the locking direction and the retainer 366 is not pushed by the pin 365, so the lock is engaged.

[0045] In other words, regardless of whether the output rod 30 moves in the forward or backward direction due to external force, the output rod 30 is locked to the main housing 40, protecting the ball screw 10 from external force. Furthermore, since the motor 60 does not need to be driven to maintain the position of the output rod 30, energy savings are achieved in maintaining the tilt of the vehicle body 100.

[0046] In the above explanation, as an example, a configuration is shown in which the first locking part 361, whose locking direction is forward, is positioned in front of the pin 365, and the second locking part 362, whose locking direction is rearward, is positioned behind the pin 365. However, an arrangement in which the positions of the first locking part 361 and the second locking part 362 are reversed is also possible. In this case, the pin 365 passes through an elongated hole or the like provided in the retainer 366, and the lock is released by pulling the retainer 366. Furthermore, while the above description shows an electric actuator 350 equipped with a ball screw as a preferred example, the actuator of the present invention may be equipped with, for example, a roller screw or a sliding screw.

[0047] Furthermore, although the above description shows an example of the application of the vehicle body tilting system to railway vehicles, the vehicle body tilting system of the present invention may also be applied to other vehicles, such as automobiles. Furthermore, while the above description shows an example of the actuator's application to a vehicle body tilting system, the actuator of the present invention can be applied to a wide range of fields as an actuator for devices that maintain posture against external forces, such as walking assistance devices and robot arms. Furthermore, the actuator of the present invention may be applied to drive mechanisms in construction machinery and the like. [Explanation of Symbols]

[0048] 1000...railway vehicle, 100...car body, 200...bogie, 300...car body tilting system 310...Vehicle tilting mechanism, 320...ECU (Electronic Control Unit), 330... Vehicle tilt control device, 340... Sensor, 350... Electric actuator, 10...Ball screw, 11...Screw shaft, 13...Nut, 20...Gear reducer, 22...Input side rotating shaft, 23, 24... Gears, 30... Output rod, 40... Main housing, 51... Ball bearing 50...Bearing housing, 60...Motor, 61, 62...Connectors, 360...Locking mechanism 361...First locking part, 362...Second locking part, 363...Cam member, 363a...Cam surface, 364...Ball, 365...Pin, 366...Retainer

Claims

1. Motor and, A screw shaft that rotates by the rotational force transmitted from the motor, A nut that moves linearly along the screw shaft as the screw shaft rotates, An output rod that moves linearly by receiving the force of the linear movement of the nut, The output rod is held in a state that allows for linear movement by a main housing, A locking mechanism that locks the movement of the output rod relative to the main housing when an external force is applied to the output rod, and releases the lock when a force is applied to the output rod from the nut side, An actuator equipped with the following features.

2. The locking mechanism is A first locking mechanism that can lock only the forward movement of the output rod in its linear movement, A second locking mechanism that can lock only the movement to the rear, A release unit that releases the lock of the first locking unit when the nut moves forward, and releases the lock of the second locking unit when the nut moves backward, The actuator according to claim 1, comprising:

3. The actuator according to claim 2, wherein the first locking portion and the second locking portion are arranged between the output rod and the main body housing.

4. The release unit is The pin protruding from the aforementioned nut, A first release member is incorporated into the first locking portion and releases the lock of the first locking portion by the force applied by the pin, A second release member is incorporated into the second locking portion and releases the lock of the second locking portion by the force applied by the pin, Equipped with, The first locking portion is positioned in front of the pin, The actuator according to claim 2, wherein the second locking portion is positioned rearward with respect to the pin.

5. The first locking part and the second locking part are A ball is positioned between the output rod and the main housing, A cam surface in which the ball is sandwiched forms a narrow gap on one side, the front and the rear, and the ball moves to the one side and fits into the gap, thereby locking the movement of the output rod. Equipped with, The actuator according to claim 4, wherein the first release member and the second release member are pressed by the pin and move the ball toward the wider gap to release the lock.

6. An actuator according to any one of claims 1 to 5 that changes the tilt of the vehicle body, A control unit that controls the tilt of the vehicle body by controlling the actuator, A vehicle tilting system equipped with a vehicle body tilting system.

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