JP2005256927A - Electromagnetic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic shock absorber improving ride comfort in a vehicle, even when rapid input in an axial direction is received from a road surface. <P>SOLUTION: This electromagnetic shock absorber is provided with a screw shaft 3 rotatably screwed into inside of a screw nut 4 and a motor 1 connected to the screw shaft 3, and suppresses relative displacement in the axial direction between the screw nut 4 and the screw shaft 3 by electromagnetic force of the motor 1. Between the screw shaft 3 and the motor 1, or between a support member and the screw nut 4, a torque change means D for changing transmission torque between the screw shaft 3 and the motor 1 or between the support member and the screw nut 4 is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention has a mechanism for converting a linear motion of a screw shaft into a rotational motion of a motor via the screw nut by screwing a screw shaft into the screw nut so as to be rotatable, and using the electromagnetic force of the motor as a damping force. The present invention relates to an electromagnetic shock absorber to be used.

  In general, a suspension is known in which a hydraulic shock absorber is interposed between a vehicle body and an axle in parallel with a suspension spring. This suspension suspends the vehicle body and attenuates input such as vibration from a road surface. The ride comfort and controllability are improved, or the vehicle height is kept constant by suppressing the displacement of the vehicle body. This hydraulic shock absorber is advantageous in that a high damping force can be obtained, but on the other hand, oil is required, and a seal mechanism and a complicated valve mechanism for preventing leakage of the oil are required.

  Therefore, recently, a new electromagnetic shock absorber that does not require oil, air, power supply, etc. has been studied and proposed (see Patent Document 1 and Non-Patent Document 1).

The basic structure of this electromagnetic shock absorber is composed of a screw shaft that is rotatably engaged with a ball screw nut, and a motor that is connected to one end of the screw shaft and short-circuits an electrode, and the ball screw nut is a shaft with respect to the screw shaft. The shaft of the motor and the shaft of the motor rotate, and the induced electromotive force generated by the rotation of the shaft attenuates the torque opposite to the rotational direction of the shaft and screw shaft to suppress the linear motion of the ball screw nut. It is used as power.
JP 2003-227543 A (paragraph number 0023, FIG. 1) Suematsu, Suda, "Study on Electromagnetic Suspension in Automobile", Japan Society for Automotive Engineers, Preprint of Academic Lecture, 2000, No4-00

  However, when the conventional screw shaft and the motor shaft described above are connected to each other and the electromagnetic shock absorber adopting the configuration for transmitting the rotational motion of the screw shaft to the motor is applied to a vehicle in particular, There is a problem.

  In the electromagnetic shock absorber, a damping force proportional to the rotational speed of the screw shaft is generated. Therefore, when a particularly rapid axial vibration such as a push-up input is input from the road surface, the rotational speed of the screw shaft is also increased. Therefore, since the motor shaft also rotates at a high speed accordingly, the electromagnetic force generated by the motor increases and a higher damping force is generated.

  Then, an impact is transmitted to the vehicle body side, and as a result, the riding comfort in the vehicle is deteriorated.

  Accordingly, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an electromagnetic shock absorber that improves riding comfort in a vehicle.

  In order to achieve the above-described object, the electromagnetic shock absorber in the first problem solving means includes a screw shaft that is rotatably screwed into a screw nut, and a motor that is coupled to the screw shaft. In the electromagnetic shock absorber that suppresses the relative movement of the screw nut and the screw shaft in the axial direction, torque changing means for changing the transmission torque between the screw shaft and the motor is provided.

  The electromagnetic shock absorber in the second problem solving means includes a screw shaft that is rotatably screwed into a screw nut supported by the support member, and a motor that is coupled to the screw shaft, and the electromagnetic force of the motor. In the electromagnetic shock absorber that suppresses the relative movement of the screw nut and the screw shaft in the axial direction, torque changing means for changing the transmission torque between the support member and the screw nut is provided.

  In the electromagnetic shock absorber in the third problem solving means, the torque changing means in the first problem solving means has a torque for rotating the screw shaft or a torque for rotating the shaft of the motor by the electromagnetic force generated by the motor. When the torque becomes higher than the torque, the transmission of the torque is suppressed or released.

  Further, in the electromagnetic shock absorber in the fourth problem solving means, in the second problem solving means, the torque changing means is configured to reduce the torque applied to the support member when the torque acting on the screw nut exceeds a predetermined torque. It is characterized by suppressing or canceling transmission.

  Furthermore, the electromagnetic shock absorber in the fifth problem solving means is characterized in that, in any of the first to fourth problem solving means, the torque changing means is a clutch, an electromagnetic clutch or a torque limiter.

  In the electromagnetic shock absorber in the sixth problem solving means, in any one of the first to fourth problem solving means, the torque changing means is an electromagnetic clutch, and the motor is controlled by controlling the current supply amount to the electromagnetic clutch. It is characterized by controlling the damping force due to the moment of inertia.

  According to the invention of each claim, the torque changing means can change the transmission torque between the screw shaft and the motor or between the screw nut and the support member. In addition, when a sudden and large load such as a push-up input from the road surface is input to the electromagnetic shock absorber, the motor can be prevented from generating a damping force or the generated damping force can be reduced. Therefore, an impact is not transmitted to the vehicle body side, and the riding comfort in the vehicle is improved.

  According to the invention of claim 3, when the torque for rotating the screw shaft by the linear motion of the screw nut in the vertical direction is equal to or higher than a predetermined torque, for example, when this electromagnetic shock absorber is applied to a vehicle, it is pushed up from the road surface. When a sudden and large load such as an input is input to the electromagnetic shock absorber, the torque changing means suppresses or cancels the torque transmission, so that the motor is prevented from generating a damping force or the generated damping force is reduced. be able to. Therefore, an impact is not transmitted to the vehicle body side, and the riding comfort in the vehicle is improved.

  The predetermined torque is set to a torque generated at the time of vibration input that deteriorates the riding comfort in the vehicle so as to be suitable for the vehicle to which the electromagnetic shock absorber is applied. Only when a large and sudden load is input to the electromagnetic shock absorber, the ride comfort in the vehicle can be improved by releasing the torque transmission.

  According to the invention of claim 4, when the torque for rotating the screw nut is equal to or greater than a predetermined torque, for example, when this electromagnetic shock absorber is applied to a vehicle, a sudden and large load such as a push-up input from the road surface Is input to the electromagnetic shock absorber, the torque changing means suppresses or cancels the torque transmission, so that the motor can be prevented from generating a damping force or the generated damping force can be reduced. Therefore, an impact is not transmitted to the vehicle body side, and the riding comfort in the vehicle is improved.

  The predetermined torque is set to a torque generated at the time of vibration input that deteriorates the riding comfort in the vehicle so as to be suitable for the vehicle to which the electromagnetic shock absorber is applied. Only when a large and sudden load is input to the electromagnetic shock absorber, the ride comfort in the vehicle can be improved by releasing the torque transmission.

  According to the fifth aspect of the present invention, the electromagnetic force generated by the motor is controlled by adjusting the electromagnetic clutch or the torque limiter so that the electromagnetic clutch or the torque limiter is in a idling state, that is, a slipping state when a predetermined torque is applied. In addition, adverse effects due to damping force due to the moment of inertia of the rotor of the motor can be suppressed. That is, adverse effects due to the moment of inertia can be prevented, and the riding comfort in the vehicle can be improved.

  When an electromagnetic clutch is used, if the current supply to the electromagnetic clutch is cut off when the rotational speed of the screw shaft exceeds the allowable rotational speed of the motor, the motor caused by abnormal heat generation of the motor Insulation deterioration due to chemical change or the like of the insulating film of the conductive wire forming the coil, and thus adverse effects such as leakage due to the deterioration of insulation and damage to the motor itself can be prevented.

  According to the sixth aspect of the present invention, if the amount of current that can be transmitted to the electromagnetic clutch is controlled by controlling the amount of current supplied to the electromagnetic clutch, the harmful effect caused by the damping force caused by the moment of inertia of the rotor of the motor. In addition, the ride comfort in the vehicle can be improved.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of an electromagnetic shock absorber according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the electromagnetic clutch. FIG. 3 is a longitudinal sectional view of an electromagnetic shock absorber according to the second embodiment of the present invention. FIG. 4 is a longitudinal sectional view of the torque limiter.

  As shown in FIG. 1, the electromagnetic shock absorber according to the first embodiment includes a motor 1, a screw shaft 3, a ball screw nut 4 as a screw nut, and an electromagnetic clutch D as torque changing means. The screw shaft 3 is screwed into the ball screw nut 4, and the linear motion of the ball screw nut 4 in the vertical direction in FIG. 1 is converted into the rotational motion of the screw shaft 3. The ball screw nut 4 and the screw shaft are generated by using the torque against the rotation of the screw shaft 3 caused by the electromagnetic force as a damping force for suppressing the linear motion of the ball screw nut 4. The relative movement in the axial direction with respect to 3 can be suppressed.

  More specifically, the screw shaft 3 has a screw groove 3a formed on the outer periphery thereof, and the upper portion in FIG. 1 is inserted into the bottomed cylindrical outer cylinder 5 via ball bearings 7 and 8 so as to be rotatable. The upper end of the screw shaft 3 is connected to one end of the electromagnetic clutch D. Further, the screw shaft 3 is rotatably screwed into the ball screw nut 4, and a cushion member 15 is provided at the tip, that is, the lower end in FIG. 1, and the ball screw nut 4 moves downward in FIG. When the electromagnetic shock absorber is fully extended, the cushion member 15 provided at the lower end in FIG. 1 of the screw shaft 3 comes into contact with the lower end in FIG. 1 of the ball screw nut 4 so that the screw shaft 3 becomes the ball screw. It is prevented that the nut 4 comes off, and the impact at the time of full extension is alleviated.

  Here, although the structure of the ball screw nut 4 is not particularly illustrated, for example, a spiral ball holding portion is provided on the inner periphery of the ball screw nut 4 so as to coincide with the spiral screw groove 3 a of the screw shaft 3. A large number of balls are arranged in the holding portion, and a passage is provided in the ball screw nut 4 to communicate both ends of the helical holding portion so that the balls can circulate. When the screw shaft 3 is screwed into the ball screw nut 4, the ball screw nut 4 is fitted into the spiral screw groove 3a of the screw shaft 3, and the ball screw nut 4 is shown in FIG. Since the ball itself is rotated by the frictional force with the screw groove 3a of the screw shaft 3 along with the linear motion in the middle / up / down direction, a smooth operation is possible as compared with a mechanism such as a rack and pinion. Further, the ball screw nut 4 is connected to a bottomed cylindrical inner cylinder 6 via a bracket 10.

  On the other hand, the shaft 1a of the motor 1 is connected to the other end side of the electromagnetic clutch D, which is a torque changing means connected to the upper end of the screw shaft 3, and when the screw shaft 3 rotates, the electromagnetic clutch D passes through the electromagnetic clutch D. The shaft 1a of the motor 1 can also rotate. The motor 1 is fixed and accommodated in the outer cylinder 5. Here, the motor 1 is not illustrated, but if a brushless motor is taken as an example, a shaft 1a rotatably inserted into the frame, a coil wound around a core attached to the frame, and a plurality of attached to the shaft 1a. The magnet is provided so as to face the coil and the core. That is, when the shaft 1a exhibits a rotational movement with respect to the frame, the magnet also rotates, so that an induced electromotive force is generated when the coil crosses the magnetic field generated by the magnet. Each of the electrodes of the motor 1 is connected to a control circuit or the like (not shown), or is short-circuited to be a closed circuit so as to generate torque against the rotation of the shaft 1a caused by electromagnetic force. By adjusting, the desired damping force is adjusted. In the case of a brushless motor, a Hall element, a magnetic sensor, an optical sensor, or the like is mounted as a rotor position detecting means. However, as long as a torque due to electromagnetic force is simply generated, the position detecting means is used. There is no need to provide it. However, by providing the position detection means, it is possible to grasp the state of rotation of the rotor (rotation angle, angular velocity, etc.), which is convenient for motor control. For example, taking a Hall element as an example, it is necessary to energize the element from an external power source, but it is sufficient to supply a current by connecting an electric wire for energization to the element. Since power is generated by the rotation of the shaft 1a without using a power source, the current generated by the induced electromotive force is supplied to the Hall element, or is stored in an external battery and supplied from the battery. You may do that. From the above description, the coil is attached to the frame and the magnet is attached to the shaft 1a. However, the coil may be attached to the shaft 1a and the magnet may be attached to the frame. In the present embodiment, the motor 1 is a brushless motor, but various motors such as a DC motor, an AC motor, an induction motor, and the like can be used as long as they can be used as an electromagnetic force generation source.

  Further, the electromagnetic clutch D is set so as to disconnect the shaft 1a of the motor 1 when the torque for rotating the screw shaft 3 becomes equal to or greater than a predetermined torque. The electromagnetic clutch D may be a well-known one that can transmit or disable the transmission of rotational motion. Specifically, for example, as shown in FIG. 2, a ball bearing 30 is attached to the shaft 1a of the motor 1. An electromagnet holding member 31 rotatably attached thereto, an electromagnet M in which a coil 32 is provided and fixed to the electromagnet holding member 31, a clutch plate 33 fitted to the shaft 1a, and a clutch plate 33. An annular friction plate 34, a clutch plate holding member 36 that is rotatably attached to the shaft 1a via a ball bearing 35, and is fitted to the screw shaft 3, and an annular plate spring 37 on the clutch plate holding member 36. When the current is applied to the coil 32, the clutch plate 38 resists the spring force of the annular leaf spring 37 and is applied to the clutch plate 38. When the rotation of the screw shaft 3 is transmitted to the shaft 1a of the motor 1 and the coil 32 is de-energized, the clutch plate 38 is clutched by the restoring force of the annular leaf spring 37. Since it is separated from the plate 33, the rotation of the screw shaft 3 is not transmitted to the shaft 1a.

  Further, the above-described inner cylinder 6 is slidably inserted into the outer cylinder 5 via a bearing 9 and a bracket 10, and a dust seal S is provided at the lower end of the outer cylinder 5 in FIG. Therefore, since the constituent members of the electromagnetic shock absorber are covered by the outer cylinder 5 and the inner cylinder 6, stepping stones, rainwater, etc. from the road surface directly hit the ball screw nut 4, the motor 1, the electromagnetic clutch D, and the screw shaft 3. Is prevented. Further, the shaft 9 of the screw shaft 3 with respect to the inner cylinder 6 and the ball screw nut 4 is prevented by the bearing 9 and the bracket 10, and a load is concentrated on a part of the balls (not shown) of the ball screw nut 4. This can prevent the ball or the screw groove 3a of the screw shaft 3 from being damaged. In addition, since the ball or the screw groove 3a of the screw shaft 3 can be prevented from being damaged, the smoothness of each operation of the rotation of the screw shaft 3 and the ball screw nut 4 or the movement of the electromagnetic shock absorber in the expansion / contraction direction can be maintained. Since the smoothness of each of the above operations can be maintained, the function as an electromagnetic shock absorber is not impaired, and consequently failure of the electromagnetic shock absorber can be prevented.

 Further, by providing the bearing 9 and the bracket 10 between the outer cylinder 5 and the inner cylinder 6, the inner cylinder 6 is misaligned with respect to the outer cylinder 5, and the inner circumference of the upper end portion of the outer cylinder 5 is the inner cylinder 6. The situation which bites the outer periphery of the outer cylinder 5 is prevented, and the deterioration of the sealing performance between the outer cylinder 5 and the inner cylinder 6 is also prevented.

  Incidentally, a bracket (not shown) is provided at the upper end of the outer cylinder 5, and this electromagnetic shock absorber is connected, for example, between the vehicle body side and the axle side of the vehicle by an eye-shaped bracket 20 provided at the lower end of the inner cylinder 6. Can be intervened.

  Subsequently, the operation will be described. When the inner cylinder 6 expands and contracts to the electromagnetic shock absorber, that is, when the inner cylinder 6 moves in the vertical direction in FIG. 1, the ball screw nut 4 connected to the inner cylinder 5 also performs a linear motion in the vertical direction. The linear motion of the ball screw nut 4 is converted into rotational motion of the screw shaft 3 by the ball screw mechanism of the ball screw nut 4 and the screw shaft 3.

  Here, when the electromagnetic clutch D connects the screw shaft 3 and the shaft 1a, that is, when the torque for rotating the screw shaft 3 is equal to or less than a predetermined torque, the screw shaft 3 can rotate with respect to the shaft 1a. In the absence, when the screw shaft 3 exhibits a rotational motion, the shaft 1a also rotates. Then, the coil in the motor 1 crosses the magnetic field of the magnet, and an induced electromotive force is generated in the coil. As described above, each electrode of the motor 1 is short-circuited. Torque against the rotation of the shaft 1a caused by electric power is generated. The torque against the rotation of the shaft 1a suppresses the rotation of the screw shaft 3 and the linear motion of the ball screw nut 4 because the shaft 1a is connected to the screw shaft 3.

  Therefore, the action of suppressing the rotational movement of the shaft 1a of the motor 1 works to suppress the linear movement of the ball screw nut 4, so that it acts as a damping force that suppresses the linear movement of the ball screw nut 4, and the vibration energy is reduced. Absorb absorption.

  As described above, the function as an electromagnetic shock absorber can be exhibited by a series of operations. However, when the torque for rotating the screw shaft 3 by the linear motion of the ball screw nut 4 in the vertical direction is equal to or higher than a predetermined torque, for example, When this electromagnetic shock absorber is applied to a vehicle and a sudden and large load such as a push-up input is input to the electromagnetic shock absorber, the electromagnetic clutch D cuts off the current supply to the coil in the electromagnet. Then, only the screw shaft 3 rotates, the shaft 1a does not rotate, and the motor 1 does not generate electromagnetic force. Therefore, in the above situation, the generation of damping force can be prevented, so that the impact is not transmitted to the vehicle body side, and the riding comfort in the vehicle is improved.

  When the torque for rotating the screw shaft 3 is equal to or less than a predetermined torque, the coil of the electromagnetic clutch D is energized and a normal damping force is generated. Therefore, the ride comfort in the vehicle can be improved by releasing the torque transmission only when a sudden and large load such as a push-up input from the road surface is input to the electromagnetic shock absorber. Further, the predetermined torque is preferably set to a torque generated at the time of vibration input that deteriorates the riding comfort in the vehicle so as to be suitable for the vehicle to which the electromagnetic shock absorber is applied.

  In the above description, the electromagnetic clutch D cuts off the power supply to the coil in the electromagnet when the predetermined torque is loaded. However, the clutch plate 33 and the clutch plate 38 are in contact with each other in advance when the predetermined torque is loaded. However, the force for attracting the clutch plate 38 may be adjusted so as to be in the idling state, that is, the slipping state. In this case, what is necessary is just to adjust the electric current amount so that it may be in the said state according to the specification of an electromagnet. By doing so, since the electromagnetic clutch D does not directly transmit the rotation of the screw shaft 3 to the shaft 1a, the shaft 1a of the motor 1 does not rotate or even if it rotates, the rotation speed is lower than the rotation speed of the screw shaft 3. Even when a sudden vibration is input, a large damping force is not generated, and the riding comfort in the vehicle can be improved.

  Further, if the current supply to the electromagnetic clutch D is cut off when the rotational speed of the screw shaft 3 exceeds the allowable rotational speed of the motor 1, a lead wire that forms a motor coil caused by abnormal heat generation of the motor. Insulation deterioration due to chemical change of the insulating coating, and thus adverse effects such as leakage due to the deterioration of insulation and damage to the motor itself can be prevented.

  The damping force generated by the conventional electromagnetic shock absorber is not due to the electromagnetic force generated by the motor, but the rotor of the motor, specifically, the shaft of the motor 1 in this embodiment. Some are caused by the moment of inertia of the magnets attached to 1a and the shaft 1a. That is, the damping force generated by the electromagnetic shock absorber is the sum of the moment of inertia of the rotor of the motor, the moment of inertia of the screw shaft, and the electromagnetic force generated by the motor. The moment of inertia of the motor is the angular acceleration of the motor shaft. Since it is proportional to the acceleration of the telescopic motion of the shock absorber, it is proportional to the acceleration of the telescopic motion of the shock absorber.

  Since the inertia moment of the rotor is proportional to the acceleration of the telescopic motion as described above, the axial vibration input to the electromagnetic shock absorber does not depend on the electromagnetic force of the motor. Damping force will be generated, especially when electromagnetic shock absorbers are applied to vehicles, especially when a sudden axial vibration is input, such as when pushing up from the road surface etc. Will generate power.

  Therefore, a damping force due to the moment of inertia of the rotor of the motor is always generated prior to the damping force depending on the electromagnetic force. Further, as described above, the moment of inertia of the rotor of the motor is relatively large. Riding comfort will deteriorate, but here, if the amount of current supplied to the electromagnetic clutch D is controlled to positively control the state in which the clutch plate 33 and the clutch plate 38 slide, the rotor of the motor 1 It is also possible to suppress adverse effects caused by the damping force caused by the moment of inertia. That is, since the electromagnetic clutch D can also control the transmission of torque by the electromagnetic force generated by the motor 1, as described above, it is impossible to transmit the torque caused by the electromagnetic force more than necessary to the screw shaft 3. Therefore, if the amount of current that can be transmitted to the electromagnetic clutch D is controlled by controlling the amount of current supplied to the electromagnetic clutch D, adverse effects due to the moment of inertia can be prevented, and the riding comfort in the vehicle can be further reduced. It can also be improved.

  Next, a second embodiment will be described. In addition, about the member similar to 1st Embodiment, suppose that detailed description is abbreviate | omitted only to attach | subject the same code | symbol. As shown in FIG. 3, the electromagnetic shock absorber according to the second embodiment has substantially the same configuration as that of the first embodiment. The difference from the first embodiment is that the first embodiment is different from the first embodiment. In the second embodiment, the electromagnetic clutch D is provided between the screw shaft 3 and the shaft 1a of the motor 1. However, in the second embodiment, the screw shaft 3 and the motor 1a are directly connected. A torque limiter T is provided between the inner cylinder 6 and the eye bracket 20 in place of the electromagnetic clutch D.

  Hereinafter, the points different from the first embodiment will be described in detail. The ball screw nut 4 is fitted to a bracket 10 connected to the inner cylinder 6, and the inner cylinder 6 is an eye-shaped bracket as a support member. 20 is connected via a torque limiter T. As shown in FIG. 4, the torque limiter T includes a shaft 40 coupled to the lower end of the inner cylinder 6, a lower friction plate holding member 42 rotatably coupled to the shaft 40 via a ball bearing 41, An annular lower friction plate 43 provided on the lower friction plate holding member 42, an upper friction plate holding member 44 that is fitted to the shaft 40 while allowing only a vertical movement in FIG. 4, and an upper friction plate holding member 44. The upper friction plate 45 is provided between the lower end surface of the inner cylinder 6 and the upper friction plate holding member 44, and the upper friction plate holding member 44 is attached to the lower friction plate holding member 42. The disc spring 46 is energized. In addition, since the shaft 40 is coupled to the inner cylinder 6, an axial force acts when the electromagnetic shock absorber expands and contracts, but the shaft 40 is prevented from falling off the lower friction plate holding member 42. Reference numeral 40 denotes a ball bearing 41, and the lower friction plate holding member 42 also holds the ball bearing 41. In the torque limiter T, the shaft 40 is engaged with the key 40a and the key groove 44a provided in the upper friction plate holding member 44, and the upper friction plate holding member 44 is in the vertical direction with respect to the shaft 40. Since only movement is permitted and rotation in the circumferential direction is restricted, the upper friction plate holding member 44 rotates integrally with the inner cylinder 6, and this upper friction plate holding member 44 is attached by a disc spring 46. Therefore, the upper friction plate 45 and the lower friction plate 43 attached to the eye bracket 20 via the lower friction plate holding member 42 are always in contact with each other. The rotation of the inner cylinder 6 with respect to the eye-shaped bracket 20 as a support member can be restricted by the frictional force generated between the plate 43 and the plate 43. When the torque for rotating the inner cylinder 6, that is, the torque for rotating the ball screw nut 4 connected to the inner cylinder 6 via the bracket 10, exceeds a predetermined torque, the upper friction plate 45 is moved to the lower friction plate. The initial load of the disc spring 46 is set so as to slide with respect to 43 and rotate. The torque limiter T having the above-described configuration is an example, and it goes without saying that a known torque limiter may be employed in addition to this.

  The electromagnetic shock absorber according to the second embodiment is configured as described above, and the operation thereof will be described. When the inner cylinder 6 expands and contracts to the electromagnetic shock absorber, that is, when the inner cylinder 6 moves in the vertical direction in FIG. 1, the ball screw nut 4 connected to the inner cylinder 5 also performs a linear motion in the vertical direction. The linear motion of the ball screw nut 4 is converted into rotational motion of the screw shaft 3 by the ball screw mechanism of the ball screw nut 4 and the screw shaft 3.

  Here, the torque limiter T can prevent the rotation of the inner cylinder 6, that is, the torque for rotating the ball screw nut 4 is equal to or lower than a predetermined torque, and the torque limiter T is connected to the eye bracket 20. In the state where it does not rotate, when the screw shaft 3 exhibits a rotational motion, the shaft 1a directly connected to the screw shaft 3 also rotates. Then, the coil in the motor 1 crosses the magnetic field of the magnet, and an induced electromotive force is generated in the coil. As described above, each electrode of the motor 1 is short-circuited. Torque against the rotation of the shaft 1a caused by electric power is generated. The torque against the rotation of the shaft 1a suppresses the rotation of the screw shaft 3 and the linear motion of the ball screw nut 4 because the shaft 1a is connected to the screw shaft 3.

  Therefore, the action of suppressing the rotational movement of the shaft 1a of the motor 1 works to suppress the linear movement of the ball screw nut 4, so that it acts as a damping force that suppresses the linear movement of the ball screw nut 4, and the vibration energy is reduced. Absorb absorption.

  As described above, the function as an electromagnetic shock absorber can be exhibited by a series of operations. Here, when the ball screw nut 4 exhibits a linear motion in the vertical direction, the screw shaft 3 is rotated. As a reaction force, the nut 4 is also loaded with a torque that rotates the ball screw nut 4. And when the torque which rotates this ball screw nut 4 becomes more than the predetermined torque set by the torque limiter T, for example, when this electromagnetic shock absorber is applied to a vehicle, a sudden and large load such as a push-up input or the like is applied. Is input to the electromagnetic shock absorber, the upper friction plate 45 of the torque limiter T slides relative to the lower friction plate 43 and rotates. Then, when only the ball screw nut 4 rotates, the screw shaft 3 does not rotate, the shaft 1a does not rotate, and the motor 1 does not generate electromagnetic force. Further, when the ball screw nut 4 rotates and the screw shaft 3 also rotates, the rotation speed of the screw shaft 3 is smaller than the rotation speed when only the screw shaft 3 rotates, so that the electromagnetic force generated by the motor 1 is Decrease.

  Therefore, in either case, the motor 1 cannot generate electromagnetic force or the generated electromagnetic force is reduced, so that an impact is not directly transmitted to the vehicle body side. Comfort is improved.

  Therefore, only when a sudden and large load such as a push-up input from the road surface is input to the electromagnetic shock absorber, the torque change means suppresses or cancels the transmission of the torque, so that the riding comfort in the vehicle can be improved. Further, the predetermined torque is preferably set to a torque generated at the time of vibration input that deteriorates the riding comfort in the vehicle so as to be suitable for the vehicle to which the electromagnetic shock absorber is applied. As described above, it can be adjusted by the initial load of the disc spring 46 of the torque limiter T.

  Further, since the upper friction plate 45 and the lower friction plate 43 of the torque limiter T are in a sliding state, adverse effects caused by the damping force caused by the inertia moment of the rotor of the motor 1 can be suppressed.

  Incidentally, in the present embodiment, a torque limiter T is provided between the lower end of the inner cylinder 6 and the eye bracket 20, but a ball screw nut side friction plate is provided on the outer periphery of the ball screw nut 4. A torque plate may be formed by providing a friction plate facing the ball screw nut side friction plate. In this case, the support member is a member that connects the vehicle body or axle of the vehicle and the ball screw nut 4 and is the inner cylinder 6 in the present embodiment.

  Further, although the electromagnetic clutch D is used in the first embodiment and the torque limiter T is used in the second embodiment, the torque limiter T is used in the first embodiment. You may use the electromagnetic clutch D for a form.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a longitudinal cross-sectional view of the electromagnetic shock absorber in the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of an electromagnetic clutch. It is a longitudinal cross-sectional view of the electromagnetic shock absorber in the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of a torque limiter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 1a Shaft 3 Screw shaft 3a Screw groove 4 Ball screw nut which is a screw nut 5 Outer cylinder 6 Inner cylinder 20 Eye-shaped bracket which is a support member D Electromagnetic clutch T Torque limiter

Claims (6)

In an electromagnetic shock absorber comprising: a screw shaft that is rotatably engaged in a screw nut; and a motor connected to the screw shaft, wherein the electromagnetic nut of the motor suppresses relative movement in the axial direction of the screw nut and the screw shaft. An electromagnetic shock absorber provided with a torque changing means for changing a transmission torque between the screw shaft and the motor. A screw shaft that is rotatably engaged in a screw nut supported by a support member and a motor that is coupled to the screw shaft are provided, and the relative movement of the screw nut and the screw shaft in the axial direction is suppressed by the electromagnetic force of the motor. In the electromagnetic shock absorber, a torque changing means for changing a transmission torque between the support member and the screw nut is provided. The torque changing means suppresses or cancels the transmission of the torque when the torque for rotating the screw shaft or the torque for rotating the shaft of the motor by the electromagnetic force generated by the motor exceeds a predetermined torque. The electromagnetic shock absorber according to claim 1. The torque changing means suppresses or cancels the transmission of the torque to the support member when the torque acting on the screw nut becomes equal to or greater than a predetermined torque. The electromagnetic shock absorber according to any one of claims 1 to 4, wherein the torque changing means is a clutch, an electromagnetic clutch, or a torque limiter. The electromagnetic shock absorber according to any one of claims 1 to 4, wherein the torque changing means is an electromagnetic clutch, and the damping force due to the moment of inertia of the motor is controlled by controlling a current supply amount to the electromagnetic clutch. .

Images