JP4367333B2 - Torque limiter - Google Patents

Description

  The present invention relates to a power transmission system for general industrial equipment, aircraft, and the like, and relates to a torque limiting device that suppresses transmission of torque when a torque exceeding a specified value is about to act.

Examples of conventionally known torque limiting devices include those shown in the following patent documents. An outline of a conventional torque limiting device will be described with reference to FIG. This type of torque limiting device includes a ball ramp portion that senses torque transmitted from the input shaft E1 side to the output shaft E2 side (the ball ramp E4 that houses the ball E3 and the ball E3 is an element), and a ball ramp portion. And a brake plate E5 that brakes the output shaft E2 when a torque greater than a specified value is sensed. When a torque exceeding the specified value is input, the axial force generated at the ball ramp exceeds the preload force by the spring E8, and the plate E7 is displaced toward the brake plate E5 so that the ball E3 rides on the ball ramp E4. Let As a result, the plate E7 presses the brake plate E5 and causes braking torque. The brake plate E5 is configured such that a rotor E51 that is spline-coupled (key-coupled) to the output shaft E2 and a stator E52 that is spline-coupled to the housing E9 are alternately arranged so that the rotor E51 and the stator E52 are plates. When pressed by E7, the friction force is exerted to brake the output shaft. The torque transmitted from the input shaft E1 side to the output shaft E2 side is absorbed by the housing E6.
Japanese Patent No. 2756456

  In the torque transmission device of the above example, the output shaft is braked when a torque greater than a specified value is input, and excessive torque is prevented from acting on the output shaft side. However, in such a case, it cannot be denied that the output shaft rotating at high speed is suddenly braked when the input torque exceeds a specified value. Therefore, due to the failure of the input shaft and other elements that continue to rotate due to inertia and the output shaft that suddenly decelerates (or stops suddenly), the rotational speed of the input shaft drops sharply and a tremendous surge torque is generated. This surge torque may cause fatal damage to members constituting the system. Therefore, it becomes necessary to take an excessive strength measure when designing the members constituting the system, resulting in an increase in weight and cost of the members and the entire system.

  The present invention made in view of the above is intended to realize a torque limiting device capable of suppressing transmission of torque exceeding a specified value while avoiding occurrence of surge torque.

  In the present invention, a friction plate that is interposed between the input shaft and the output shaft and transmits torque by friction, a pressing portion that presses the friction plate and exerts a friction force capable of transmitting torque to the friction plate, A spring for applying a spring force for pressing the friction plate to the pressing portion, and an excessive torque transmitted from the input shaft side to the output shaft side is sensed and this can be resisted against the spring force. A torque conversion mechanism for converting the mechanical displacement into a mechanical displacement, and the torque conversion mechanism that senses a torque greater than a specified value causes a mechanical displacement to generate a force that opposes the spring force, A torque limiting device that reduces the transmitted torque by reducing the frictional force in the friction plate is configured.

  That is, when an excessive torque exceeding the specified value is input, the output shaft is not braked, but the friction force on the friction plate that transmits torque from the input shaft side to the output shaft side is reduced to generate a slip. I did it. With such a configuration, the rotation speed of the input shaft does not drop rapidly, and the generation of surge torque can be avoided.

  ADVANTAGE OF THE INVENTION According to this invention, the torque limiting device which can suppress transmission of the torque exceeding a regulation value, avoiding generation | occurrence | production of surge torque is implement | achieved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the torque limiting device D of the present embodiment, torque input to the input shaft 1 is transmitted to the output shaft 2 and these are rotationally driven around the axis A. As shown in FIG. A friction plate 3 interposed between 1 and the output shaft 2 for transmitting torque by friction; a pressing portion 4 for pressing the friction plate 3 to exert a frictional force capable of transmitting torque to the friction plate 3; 4, springs 51 and 52 for applying a spring force for pressing the friction plate 3, and a direction in which excessive torque transmitted from the input shaft 1 side to the output shaft 2 side can be sensed and resisted against the spring force And a torque conversion mechanism 6 for converting into a mechanical displacement.

  The friction plate 3 includes a friction plate element 31 that is spline-coupled to the inner periphery of the input shaft 1 and a friction plate element 32 that is spline-coupled to the outer periphery of the plate 7 that is disposed relative to the inner periphery of the input shaft 1. Are arranged so as to alternately overlap in the direction of the axis A.

  The pressing portion 4 receives the spring force from the springs 51 and 52 and presses the friction plate 3 in the direction of the axis A.

  The springs 51 and 52 play a role of pressing the friction plate 3 through the pressing portion 4. In the present embodiment, there are a spring 51 that presses the output shaft 2 facing the plate 7 in the direction of the axis A toward the plate 7, and a spring 52 that is interposed between the output shaft 2 and the pressing portion 4. .

  The torque conversion mechanism 6 includes a ball 61 that senses torque transmitted from the input shaft 1 side to the output shaft 2 side, and a ball lamp 62 that houses the ball 61. The ball lamp 62 is formed on both the plate 7 and the output shaft 2, and the ball 61 accommodated in the ball lamp 62 is sandwiched between the plate 7 and the output shaft 2. A cross-sectional shape of the ball lamp 62 is shown in FIG.

Torque input to the input shaft 1 is transmitted to the plate 7 via the friction plate 3 and further transmitted to the output shaft 2 via the balls 61. As shown in FIG. 2, the axial force parallel to the axis A is applied to the output shaft 2 due to the torque transmitted from the plate 7 to the output shaft 2 due to the shape of the ball lamp 62 having a substantially V-shaped groove shape in cross section. Works. This axial force tends to move the output shaft 2 away from the plate 7. When the distance from the axis A to the ball lamp 62 is R, the torque is T, the axial force is W, and the angle between the opposing surface of the plate 7 and the output shaft 2 and the inner surface of the ball lamp 62 is θ, the torque T Between the axial force W and W = T / Rtanθ
This relationship is established. Further, the difference between the spring force exerted by the spring 51 and the spring force exerted by the spring 52 acts on the ball 61 as a preload.

  The magnitude of the axial force when a torque having a specified value (the upper limit of the allowable transmission torque) is input can be calculated from the above equation. The spring constants and dimensions of the springs 51 and 52 are designed so that a preload equivalent to the calculated axial force is applied to the ball 61.

  When an excessive torque exceeding the specified value is input to the input shaft 1 and transmitted to the output shaft 2 via the friction plate 3, the plate 7 and the ball 61, the ball 61 is displaced relative to the ball lamp 62. . That is, the ball 61 starts to ride on the inner surface of the ball lamp 62. Therefore, a larger axial force acts on the output shaft 2 and the output shaft 2 is displaced in a direction away from the plate 7. When the output shaft 2 that is separated from the plate 7 comes into contact with the pressing portion 4, at least a part of the spring force acting on the pressing portion 4 is replaced by the output shaft 2, and as a result, the pressure that presses the friction plate 3 decreases. To do. Accordingly, the friction between the friction plate element 31 on the input shaft 1 side and the friction plate element 32 on the plate 7 side (that is, on the output shaft 2 side) is reduced to cause a slip, and the torque transmitted by the friction plate 3 is also reduced. To do. At this time, since the displacement amount that the ball 61 rides on the inner surface of the ball ramp 62 is maintained, the torque transmitted by the friction plate 3 is maintained at the magnitude when the slip occurs.

  The torque limiting device D of this embodiment can be mounted on an aircraft steering surface drive system as shown in FIG. 3, for example. The control surface X1 disposed on each wing is driven by a torque shaft X2. Needless to say, the torque shaft X2 is connected to the output shaft 2 of the torque limiting device D. In order to distribute the torque evenly between the two blades, the drive source (such as a motor) X3 is disposed between the two blades.

  Thus, when a failure or other malfunction occurs, it may be necessary to limit the torque transmitted only to the torque shaft X2 on one side. In the torque limiting device D of the present embodiment, the friction plate 3, the pressing portion 4, the ball 61, the ball lamp 62, and the output shaft 2 are symmetrically arranged on both sides in the direction of the axis A, and from the single input shaft 1. The input torque can be distributed in the left and right directions, and the torque can be limited separately on the left and right. However, the aspect in which the friction plate 3, the pressing portion 4, the ball 61, the ball lamp 62, and the output shaft 2 are arranged only on one side, in other words, the aspect in which the torque is not distributed in a plurality of directions is not disturbed.

  The torque limiting device D of the present embodiment includes a friction plate 3 that is interposed between the input shaft 1 and the output shaft 2 and transmits torque by friction, and presses the friction plate 3 to apply torque to the friction plate 3. A pressing portion 4 that exerts a transmittable frictional force; springs 51 and 52 that apply a spring force to press the friction plate 3 against the pressing portion 4; and from the input shaft 1 side to the output shaft 2 side. A ball ramp portion that is a torque conversion mechanism 6 having a ball 61 that senses the transmitted torque and a ball ramp 62 that houses the ball 61. In contrast, a force against the spring force is generated through relative displacement, and the frictional force in the friction plate 3 is reduced to suppress the transmitted torque. When an excessive torque exceeding the specified value is input, the friction plate 3 shifts from a normal torque transmission to a sliding friction transmission with a slip to reduce the transmitted torque. Therefore, the rotational speed of the input shaft 1 does not drop sharply, and fluctuations in the angular acceleration of rotation do not occur, so that generation of surge torque is avoided. The torque limiting device D of the present embodiment can be lightweight, low cost and highly reliable. Furthermore, it is also freed from the need to provide a separate surge torque damper in the system.

  The present invention is not limited to the embodiment described in detail above. The specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

The figure which shows the torque limiting apparatus of one Embodiment of this invention. The figure which shows the cross-sectional shape of the ball lamp in the embodiment. The figure which shows the usage example of the torque limiting device of the embodiment. The figure which shows the conventional torque limiting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Input shaft 2 ... Output shaft 3 ... Friction plate 4 ... Press part 51, 52 ... Spring 6 ... Torque conversion mechanism

Claims (2)

Torque input to the input shaft is transmitted to a first output shaft and a second output shaft that are symmetrically arranged on both sides in the axial direction, and these are rotated,
A friction plate for transmitting torque by friction;
A plate that receives torque via the friction plate and transmits the torque to each of the first output shaft and the second output shaft;
A pair of pressing portions that are located on both sides of the friction plate and exert a friction force that can transmit torque by pressing the friction plate from both sides;
A first spring that applies a spring force that biases one of the pair of pressing portions toward the other;
A second spring that applies a spring force that biases the other of the pair of pressing portions toward one side;
An excessive torque that is interposed between the plate and the first output shaft and is transmitted from the input shaft side to the first output shaft side is detected, and this is used as the spring force of the first spring. A first torque conversion mechanism that converts mechanical displacement in a direction that can be resisted;
An excessive torque that is interposed between the plate and the second output shaft and is transmitted from the input shaft side to the second output shaft side is detected, and this is used as the spring force of the second spring. A second torque conversion mechanism that converts mechanical displacement in a direction that can be resisted , and
The torque conversion mechanism that senses a torque exceeding a specified value generates a force that opposes the spring force through causing mechanical displacement, and reduces the frictional force in the friction plate to suppress the transmitted torque. A torque limiting device characterized by the above. The first spring and the second spring are respectively
2. The torque limiting device according to claim 1, wherein the torque limiting device includes a spring that biases the output shaft toward the plate and a spring that biases the pressing portion toward the other side using the output shaft as a scaffold.

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