JP4266856B2 - Electromagnetic shock absorber - Google Patents

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 the 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 direction of rotation of the shaft and the 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

  In general, when the load of the vehicle is loaded or the number of passengers increases or decreases, the driver's line of sight changes when the vehicle height changes, and the light's center of gravity changes at night to change the direction of the light. Since the driving environment changes for the driver, the vehicle height is preferably constant regardless of the weight of the load loaded on the vehicle and the number of passengers. Further, when considering the attitude control of the vehicle, appropriate control is possible by keeping the vehicle height constant.

  In particular, in a large vehicle, it is easy to board the vehicle while the vehicle is stopped, and it is preferable to maintain a certain vehicle height for the above reason during traveling.

  However, the conventional electromagnetic shock absorber is not particularly problematic for use in a vehicle, but the vehicle height cannot be adjusted. Therefore, improvements are desired in the above points.

  Accordingly, the present invention has been made in consideration of the above-mentioned problems, and the object of the present invention is to make it possible to adjust the vehicle height without using other power means in the electromagnetic shock absorber. .

  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, switching means that allows and blocks the rotation of the screw nut with respect to the screw shaft, a holding member that holds the screw nut, and a holding member that is freely rotatable A screwing member that is screwed to the lower suspension spring receiver, a rotation prevention member that prevents rotation of the screwing member, and a holding member and a rotation prevention member that allow and prevent rotation of the holding member relative to the rotation prevention member. It is characterized by being connected via a switching means.

  A second 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, and relative movement of the screw nut and the screw shaft in the axial direction by electromagnetic force of the motor. An electromagnetic shock absorber that suppresses the axial movement of the screw shaft, a connecting member that is allowed to move only in the axial direction and connected to the screw shaft, a holding member that holds the screw nut and is connected to the lower suspension spring receiver, and a holding member A rotation preventing member that prevents rotation; a screwing member that is rotatably engaged with the holding member and rotatably connected to the rotation preventing member; and the connecting member and the screwing member that rotate the connecting member with respect to the screwing member. It is characterized by being connected via switching means for allowing and blocking.

  A third 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, and relative movement of the screw nut and the screw shaft in the axial direction by electromagnetic force of the motor. An electromagnetic shock absorber that suppresses the axial movement of the screw shaft, a connecting member that is allowed to move only in the axial direction and connected to the screw shaft, a holding member that holds the screw nut and is connected to the lower suspension spring receiver, and a holding member A rotation preventing member that prevents rotation; a screw member that is rotatably connected to the holding member and screwed to the rotation preventing member; and the connecting member and the screw member rotate the connecting member relative to the screw member. It is characterized by being connected via switching means for allowing and blocking.

  According to a fourth problem solving means, in the first problem solving means, the switching means for allowing and preventing the rotation of the screw nut relative to the screw shaft engages with a key groove provided along the axial direction of the screw shaft. It is an electromagnet.

  According to a fifth problem solving means, in the first problem solving means, the switching means for allowing and preventing rotation of the holding member relative to the rotation holding preventing member is connected to the holding member at one end and to the rotation preventing member at the other end. It is an electromagnetic clutch.

  A sixth problem-solving means is the first problem-solving means, wherein an inner cylinder that covers the screw shaft or the motor and the screw shaft is provided, and a cylindrical holding member is slidably inserted into the inner cylinder. 2. The electromagnetic shock absorber according to claim 1, wherein the inner cylinder is slidably inserted into a cylindrical screwing member.

The seventh problem-solving means is the second or third problem-solving means, wherein the switching means for allowing and preventing rotation of the connecting member relative to the screwing member is connected to the connecting member at one end and to the screwing member at the other end. It is characterized by being an electromagnetic clutch.

  According to an eighth problem-solving means, in any one of the first to third problem-solving means, the holding member includes a small-diameter cylinder and a large-diameter cylinder concentric with the small-diameter cylinder, and a screw nut is attached in the small-diameter cylinder. A screw shaft or a motor and an inner tube covering the screw shaft are slidably inserted between the small diameter tube and the large diameter tube.

  According to the invention of each claim, the length of the lower part can be changed from the lower suspension spring receiver, and thereby the vehicle height can be adjusted.

  And, with this electromagnetic shock absorber, the vehicle height can be adjusted by the above operation, so the vehicle height can be kept constant even when the vehicle weight changes due to loading of luggage on the vehicle or increase / decrease of the number of passengers. Can do. Then, the driver's line of sight changes, and at night, the vehicle's center of gravity changes to change the direction of the lights, which can eliminate the negative effects of changing the driving environment for the driver. Therefore, it is possible to perform appropriate vehicle attitude control.

  In particular, in large vehicles, the vehicle height can be reduced and the boarding can be facilitated while the vehicle is stopped, and at the same time the vehicle is returned to the original vehicle height while traveling, thereby improving the usability of the vehicle while eliminating the above disadvantages. It becomes possible to improve.

  Furthermore, for vehicle height adjustment, the motor is constantly energized, and in response to changes in the vehicle weight, an axial force is generated against the load corresponding to the amount of change in the electromagnetic shock absorber to keep the vehicle height constant. The electromagnetic shock absorber of the present invention mechanically adjusts the vehicle height as compared with the case of keeping the motor at a constant value, so that it is not necessary to energize the motor constantly, and it is economical and it is possible to avoid burdening the motor. .

  According to the invention of claim 4, since the switching means is an electromagnet, the electromagnet can be used so as to suppress the rotation of the screw shaft with respect to the screw nut, and the electromagnetic force generated by the electromagnet is used as a damping force. You can also. Therefore, by controlling the current supply amount of the electromagnet, the damping force can be made variable, and even if the motor is damaged, the electromagnet can generate a certain amount of damping force by energizing the electromagnet. Even when the torque caused by the force cannot be generated, the situation where the damping force cannot be generated is avoided. Therefore, fail safe can be performed.

  According to the sixth and eighth aspects of the present invention, since the constituent members of the electromagnetic shock absorber are covered with the holding member and the inner cylinder, stepping stones from the road surface, rainwater, etc. are directly applied to the screw nut, motor, screw shaft and switching means. Etc. are prevented.

  Further, since the inner cylinder is inserted into the screwing member or the inner cylinder is slidably inserted between the small-diameter cylinder and the large-diameter cylinder of the holding member, the screw shaft is prevented from being shaken with respect to the screw nut. Thus, it is possible to prevent a load from being concentrated on a part of the screw nut and to avoid a situation in which the screw nut or the screw groove of the screw shaft is damaged. Further, since the screw nut or the screw groove of the screw shaft can be prevented from being damaged, the smoothness of each operation of the rotation of the screw shaft and the screw nut or the movement of the electromagnetic shock absorber in the expansion / contraction direction can be maintained. Since the smoothness can be maintained, the function as an electromagnetic shock absorber is not impaired, and the failure of the electromagnetic shock absorber can be prevented.

  According to the seventh aspect of the present invention, it is not necessary to always supply current to the electromagnetic clutch, and it is more economical because it is sufficient to supply current only when adjusting the vehicle height.

  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 an enlarged cross-sectional view of a part of the electromagnetic shock absorber according to the second embodiment. FIG. 5 is a longitudinal sectional view of an electromagnetic shock absorber according to the third embodiment of the present invention. FIG. 6 is a longitudinal sectional view of an electromagnetic shock absorber according to the fourth embodiment of the present invention.

  As shown in FIG. 1, the electromagnetic shock absorber according to the first embodiment includes a ball screw nut 4 as a screw nut, a screw shaft 3, a motor 1 connected to the screw shaft 3, and a ball screw for the screw shaft 3. An electromagnet 10 as switching means for allowing and preventing rotation of the nut 4, a holding member 11 that holds the ball screw nut 4, an outer cylinder 5 that is a screwing member that is rotatably engaged with the holding member 11, and an outer cylinder 5 includes a bracket 6 serving as a rotation preventing member for preventing rotation of 5 and an electromagnetic clutch D serving as switching means for permitting and preventing rotation of the holding member 11 with respect to the bracket 6 serving as the rotation preventing member, and the screw shaft 3 is a ball screw nut 4. 1, 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, and this rotational motion is transmitted to the motor 1 to generate electromagnetic force to the motor 1. The torque against the rotation of the screw shaft 3 caused by the electromagnetic force is used as a damping force for suppressing the linear motion of the ball screw nut 4, and the axial direction of the ball screw nut 4 and the screw shaft 3 is used. Relative movement 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 inner cylinder 13 through ball bearings 7 and 8 so as to be rotatable. Further, a key groove 3b is provided on the outer periphery of the screw shaft 3 along the axial direction. The upper end of the screw shaft 3 in FIG. 1 is connected to the shaft 1 a so that the rotational motion of the screw shaft 3 can be transmitted to the shaft 1 a of the motor 1.

  On the other hand, the motor 1 is fixed to the upper end side of the inner cylinder 13 via the body C of the vehicle. That is, in the present embodiment, the motor 1 is arranged on the inner side of the vehicle body. As a result, mud, rain, stepping stones, etc. hit the motor 1 while the vehicle is running, and the motor 1 is damaged. This is prevented. The motor 1 may be directly fixed to the upper end of the inner cylinder 13, or the motor 1 may be fixed in the inner cylinder 13. Even when the motor 1 is fixed in the inner cylinder 13, since the motor 1 is covered with the inner cylinder 13, mud, rain, stepping stones, etc. hit the motor 1 while the vehicle is running, and the motor 1 is damaged. Can be prevented. Although the motor 1 is not illustrated, when 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 pieces 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. Accordingly, the motor 1 is adjusted so as to obtain a desired damping force, and at the same time, the current can be positively supplied to the motor 1 when the vehicle height is adjusted as described later. When the current is actively supplied to the motor 1, the generated damping force can be adjusted by adjusting the torque caused by the electromagnetic force of the motor 1, and the motor 1 is actively energized. Thus, the motor 1 can be driven to function as an actuator as well as a shock absorber and used as an active suspension.

  Incidentally, 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 detection means. However, as long as a torque caused by electromagnetic force is simply generated, the position detection means is not 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 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, an electromagnet 10 is inserted into the screw shaft 3 above the ball screw nut 4 in FIG. The electromagnet 10 is provided with a key (not shown) that engages with the key groove 3b of the screw shaft 3 on the inner peripheral side. The electromagnet 10 is attached to the screw shaft 3 by the engagement of the key and the key groove 3b. Only axial movement is allowed. Therefore, the electromagnet 10 can rotate together with the screw shaft 3, and the ball screw nut 4 is screwed to the screw shaft 3, so that the electromagnet 10 comes into contact with the ball screw nut 4 by its own weight. . Therefore, when the screw shaft 3 rotates, the electromagnet 10 moves in the vertical direction while contacting the ball screw nut 4. The electromagnet 10 is well known in the art and will not be described in detail. However, the electromagnet 10 is composed of an annular core that can be inserted into the screw shaft 3 and a coil wound around the core. When energizing the electromagnet 10, although not shown, for example, a pair of electrodes are provided along the side surface of the key groove 3b, and the corresponding electrodes are also provided on the key on the electromagnet 10 side. Further, a brush equivalent to a brush used in a DC motor is formed at the upper end in FIG. 1 of the screw shaft 3 so that each electrode provided in the key groove 3b of the screw shaft 3 can be energized. 3, even if it moves up and down, the electromagnet 10 may be energized through the electrode formed in the key groove 3 b of the screw shaft 3. The above energization method is an example, and other methods may be used.

  When the electromagnet 10 is energized, the ball screw nut 4 is attracted to the electromagnet 10, and when the screw shaft 3 rotates in this state, the ball screw nut 4 can rotate together with the electromagnet 10.

  Further, the ball screw nut 4 is fixed by being screwed, fitted, press-fitted or the like in the bracket 12, and the bracket 12 is connected to a cylindrical holding member 11. The ball screw nut 4, the bracket 12, and the holding member 11 are inserted into the inner cylinder 13.

  Further, a screw portion 11a is provided on the outer periphery of the lower end of the holding member 11, and a screw portion 5a provided on the inner periphery of the lower end in FIG. 1 of the outer cylinder 5 serving as a screwing member is screwed to the screw portion 11a. . Further, the inner cylinder 13 is slidably inserted into the outer cylinder 5 via annular bearings 18 and 19. A lower suspension spring receiver 20 for supporting a lower end of a suspension spring S interposed between the vehicle body and the axle of the vehicle is provided on the outer periphery of the outer cylinder 5 in FIG. A key 5 b is provided on the outer periphery along the axial direction of the outer cylinder 5, and a dust seal R for sealing between the inner cylinder 13 and the upper end thereof is provided. Incidentally, due to the bearings 18 and 19 provided between the outer cylinder 5 and the inner cylinder 13, the inner cylinder 13 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 outer circumference of the inner cylinder 13. This prevents the deterioration of the sealing performance between the outer cylinder 5 and the inner cylinder 13. Further, since the bearings 18 and 19 prevent the axial displacement of the inner cylinder 13 with respect to the outer cylinder 5, the axial displacement of the holding member 11 to which the outer cylinder 5 is screwed is also prevented. The axial movement of the screw shaft 3 with respect to the ball screw nut 4 fixed to the member 11 is prevented, and it is possible to prevent a load from being concentrated on a part of the balls (not shown) of the ball screw nut 4. Or it is possible to avoid the situation where the screw groove 3a of the screw shaft 3 is damaged. Moreover, since the damage to the ball or the screw groove 3a of the screw shaft 3 can be prevented, the smoothness of each operation of the rotation of the screw shaft 3 with respect to 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.

  As shown in the drawing, in order to prevent the axial displacement between the holding member 11 and the inner cylinder 13, the outer periphery of the bracket 12 is brought into sliding contact with the inner periphery of the inner cylinder 13. 1, an annular bearing 16 locked by a stopper 17 may be provided at the lower end in the middle, and the inner periphery of the bearing 16 may be brought into sliding contact with the outer periphery of the holding member 11.

  Furthermore, the lower end of the outer cylinder 5 is inserted into a bracket 6 which is a bottomed cylindrical rotation blocking member. The bracket 6 is formed in a bottomed cylindrical shape as described above, and an eye 6a is provided at the lower end of the bracket 6 so that the electromagnetic shock absorber can be connected to the vehicle axle, and the inner peripheral side of the cylindrical portion 6b. Is formed with a key groove 6c, and the key 5b of the outer cylinder 5 is engaged with the key groove 6c provided on the inner periphery of the cylinder portion 6b of the bracket 6 so that the outer cylinder 5 rotates relative to the bracket 6. It is prevented from doing. Therefore, the outer cylinder 5 is only allowed to move in the vertical direction in FIG. Further, one end of the electromagnetic clutch D is connected to the inner peripheral side of the bottom portion of the bracket 6, and the lower end of the holding member 11 in FIG. 1 is connected to the other end of the electromagnetic clutch D. Note that the electromagnetic clutch D can permit and block the rotation of the holding member 11 with respect to the bracket 6, and a known one may be used. Specifically, for example, FIG. 2, an electromagnet holding member 31 rotatably attached to a shaft 11 b provided at the lower end of the holding member 11 via a ball bearing 30, and an electromagnet provided with a coil 32 and fixed to the electromagnet holding member 31. M, a clutch plate 33 fitted to the shaft 11b, an annular friction plate 34 provided on the clutch plate 33, and a shaft 11b rotatably attached to the shaft 11b via a ball bearing 35. A clutch plate holding member 36 fitted to a shaft 6d rising from the bottom, and a clutch plate 38 attached to the clutch plate holding member 36 through an annular plate spring 37 so as to be swingable; Constructed, the electromagnet holding member 31 is fixed to the bracket 6 side. When a current is applied to the coil 32, the clutch plate 38 is attracted to and abuts against the clutch plate 33 against the spring force of the annular leaf spring 37, thereby forming the shaft 6 d of the bracket 6 and the holding member 11. When the shaft 11b is connected, the holding member 11 is prevented from rotating with respect to the bracket 6 and, on the contrary, when the coil 32 is de-energized, the clutch plate 38 is moved by the restoring force of the annular leaf spring 37 to the clutch plate 33. Therefore, the connection state between the shaft 6 d of the bracket 6 and the shaft 11 b formed on the holding member 11 is released, and the holding member 11 is allowed to rotate freely with respect to the bracket 6.

  Since the components of the electromagnetic shock absorber configured as described above are covered with the outer cylinder 5, the inner cylinder 13, and the bracket 6, stepping stones from the road surface, rainwater, and the like are directly applied to the ball screw nut 4 and the motor 1. The electromagnetic clutch D and the screw shaft 3 are prevented from hitting.

  Subsequently, the operation will be described. When the outer cylinder 5 expands and contracts to the electromagnetic shock absorber, that is, when the outer cylinder 5 moves in the vertical direction in FIG. 1 with respect to the inner cylinder 13, the ball screw nut 4 connected to the outer cylinder 5 via the holding member 11 is exercise. Here, the electromagnetic clutch D is energized, and the holding member 11 that holds the ball screw nut 4 is prevented from rotating with respect to the bracket 6, and power is not supplied to the electromagnet 10. Therefore, since the rotation of the ball screw nut 4 is prevented and the rotation of the screw shaft 3 with respect to the ball screw nut 4 is allowed, the linear motion of the ball screw nut 4 causes the ball screw nut 4 and the screw shaft 3 to rotate. Is converted into a rotational movement of the screw shaft 3 by the ball screw mechanism.

  When the screw shaft 3 exhibits rotational movement, 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. Here, if the current is positively supplied to the motor 1, the torque can be adjusted, so that the damping force generated by the electromagnetic shock absorber can be changed, and further, it can function as an actuator. Not only can the expansion and contraction of the shock absorber be suppressed, but the length can be increased, and furthermore, the electromagnetic shock absorber can be freely expanded and contracted.

  As described above, the function as an electromagnetic shock absorber can be exhibited by a series of operations. Next, the vehicle height adjustment function of the electromagnetic shock absorber will be described. First, the electromagnet 10 is energized to attract the ball screw nut 4 to the electromagnet 10. Further, the power supply to the electromagnetic clutch D is cut off. In this state, the motor 1 is energized to rotate the shaft 1a. Then, the screw shaft 3 connected to the shaft 1 a rotates, and the electromagnet 10 that attracts the ball screw nut 4 is restricted from freely rotating with respect to the screw shaft 3, and the holding member 11 that holds the ball screw nut 4. Since the power supply to the electromagnetic clutch D is cut off, the holding member 11 can freely rotate with respect to the bracket 6, and the ball screw nut 4 also rotates in the same manner as the screw shaft 3.

  Then, the holding member 11 that holds the ball screw nut 4 is also rotated by the rotation of the ball screw nut 4, and the outer cylinder 5 that is a screwing member that is screwed to the screw portion 11 a provided below the holding member 11 in FIG. Torque acts to rotate. However, since the outer cylinder 5 is prevented from rotating with respect to the bracket 6 by the key 5b provided on the outer cylinder 5 and the key groove 6c provided on the bracket 6, the outer cylinder 5 eventually rotates when the holding member 11 rotates. 1 is moved upward or downward in FIG. 1 by a screw mechanism of the screw part 11a and the screw part 5a. Then, the outer cylinder 5 is moved upward or downward with respect to the bracket 6, and the basic length of the electromagnetic shock absorber itself changes. In the case of an electromagnetic shock absorber, if no current is supplied to the motor 1, no force in the direction against the load of the vehicle weight is generated unless the motor 1 is supplied with current. Although the axial length is determined and the vehicle height is determined by the vehicle weight, the change in the basic length is only the downward change from the lower suspension spring receiver 20, and thus the vehicle height can be adjusted. .

  And, with this electromagnetic shock absorber, the vehicle height can be adjusted by the above operation, so the vehicle height can be kept constant even when the vehicle weight changes due to loading of luggage on the vehicle or increase / decrease of the number of passengers. Can do. Then, the driver's line of sight changes, and at night, the vehicle's center of gravity changes to change the direction of the lights, which can eliminate the negative effects of changing the driving environment for the driver. Therefore, it is possible to perform appropriate vehicle attitude control.

  In particular, in large vehicles, the vehicle height can be reduced and the boarding can be facilitated while the vehicle is stopped, and at the same time the vehicle is returned to the original vehicle height while traveling, thereby improving the usability of the vehicle while eliminating the above disadvantages. It becomes possible to improve.

  Furthermore, for vehicle height adjustment, the motor 1 is energized continuously, and in response to changes in the vehicle weight, an axial force that resists the load corresponding to the amount of change is generated in the electromagnetic shock absorber. Compared with keeping constant, the electromagnetic shock absorber of the present invention adjusts the vehicle height mechanically, so it is not necessary to energize the motor 1 constantly, it is economical, and the motor 1 is burdened. I'm sorry.

  Further, the electromagnet 10 can be used so as to suppress the rotation of the screw shaft 3 with respect to the ball screw nut 4, and the electromagnetic force generated by the electromagnet 10 can also be used as a damping force. Therefore, if the current supply amount of the electromagnet 10 is controlled, the damping force can be made variable, and even if the motor 1 is damaged, the electromagnet 10 can be energized to generate a damping force to some extent. Even when the motor 1 becomes unable to generate torque due to electromagnetic force, a situation where the damping force cannot be generated is avoided. Therefore, fail safe can be performed.

  Incidentally, in this embodiment, the lower suspension spring receiver 20 is directly welded to the outer periphery of the outer cylinder 5 which is a screwing member, but the lower suspension spring receiver 20 is not directly provided on the screwing member. A member that can be moved up and down with respect to the holding member in connection with the screwing member may be provided, and the lower suspension spring receiver 20 may be provided on this member.

  Next, a second embodiment will be described. Hereinafter, the same members as those in the first embodiment are only given the same reference numerals, and detailed description thereof is omitted. Note that the above omission is the same in the description of other embodiments. As shown in FIG. 3, the electromagnetic shock absorber according to the second embodiment includes a ball screw nut 4, a screw shaft 3, a motor 1 connected to the screw shaft 3, and a ball screw nut 4 with respect to the screw shaft 3. The electromagnet 10 as switching means for allowing and preventing rotation, the holding member 40 that holds the ball screw nut 4, the intermediate cylinder 45 that is a screwing member that is rotatably engaged with the holding member 40, and the rotation of the intermediate cylinder 45 A rotation-preventing member bracket 46 and an electromagnetic clutch D serving as switching means for allowing and preventing rotation of the holding member 40 with respect to the rotation-preventing member bracket 46, as in the first embodiment. The 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, and this rotational motion is transmitted to the motor 1. An electromagnetic force is generated in the motor 1, and a torque against the rotation of the screw shaft 3 generated due to the electromagnetic force is used as a damping force for suppressing the linear motion of the ball screw nut 43. The relative movement in the axial direction between the screw shaft 3 and the screw shaft 3 can be suppressed. The difference from the first embodiment is that the holding member 40 includes a small-diameter cylinder 41 and a large-diameter cylinder 42 concentric with the small-diameter cylinder 41, and the ball screw nut 4 is disposed in the upper end portion of the small-diameter cylinder 41 in FIG. In addition to being attached, the inner cylinder 13 is slidably inserted between the small-diameter cylinder 41 and the large-diameter cylinder 42, and an intermediate cylinder 45 is provided instead of the outer cylinder 5.

  The difference from the first embodiment will be described in detail above. The holding member 40 that holds the ball screw nut 4 is, as described above, the small diameter cylinder 41 and the small diameter cylinder 41 that is concentric with the small diameter cylinder 41 and has a larger diameter. 3 and the lower end in FIG. 3 of the small diameter cylinder 41 and the large diameter cylinder 42 are connected by a disk 43. And the holding member 40 is connected with the end of the electromagnetic clutch D via the axis | shaft (not shown) suspended from the lower end in FIG. The electromagnetic clutch D is the same as that of the first embodiment, and the shaft (not shown) is connected to the electromagnet holding member 31, the clutch plate 33, and the clutch plate holding member 36 of the electromagnetic clutch D.

  Furthermore, as shown in FIG. 4, a ball screw nut 4 is connected to the upper end portion of the small diameter cylinder 41 of the holding member 40 in FIG. 4 via the bracket 12, and the upper end portion of the large diameter cylinder 42 in FIG. 4. A screw portion 42a is provided on the outer periphery, and a screw portion 45b provided on the inner periphery of the intermediate tube 45 is screwed to the screw portion 42a. The inner cylinder 13 is slidably inserted between the small diameter cylinder 41 and the large diameter cylinder 42 via the annular bearings 51 and 52, the bearing 16, and the bracket 12. Therefore, also in the present embodiment, the shaft of the screw shaft 3 with respect to the holding member 40 and the ball screw nut 4 is prevented. Further, a dust seal R for sealing between the inner cylinder 13 and the large-diameter cylinder 42 provided at the upper end in FIG. 3 of the large-diameter cylinder 42 is provided, but provided between the large-diameter portion 42 and the inner cylinder 13. The bearings 51 and 52 prevent the inner cylinder 13 from being axially displaced with respect to the large-diameter portion 42 and prevents the inner periphery of the upper-diameter portion 42 from biting the outer periphery of the inner cylinder 13. The deterioration of the sealing performance between the large diameter portion 42 and the inner cylinder 13 is also prevented.

  The intermediate cylinder 45 is provided with a lower suspension spring receiver 50 on the outer periphery thereof, and a key 45a is provided at the lower end of the outer periphery in FIG. The lower suspension spring receiver 50 supports the lower end of the suspension spring S.

  On the other hand, the bracket 46 connected to the other end of the electromagnetic clutch D is formed in a bottomed cylindrical shape as in the first embodiment, and an electromagnetic shock absorber can be connected to the axle of the vehicle at the lower end. Further, as shown in FIG. 4, a key groove 46c is formed on the inner peripheral side of the cylindrical part 46b, and a key groove 46c provided on the inner peripheral side of the cylindrical part 46b of the bracket 46 is provided. The key 45 a of the intermediate cylinder 45 is engaged to prevent the intermediate cylinder 45 from rotating with respect to the bracket 46.

  And the other structure is the same as that of 1st Embodiment, Since the structural member of the electromagnetic shock absorber comprised as mentioned above is covered with the holding member 40, the inner cylinder 13, and the bracket 46, it is from a road surface. Are prevented from directly hitting the ball screw nut 4, the motor 1, the electromagnetic clutch D and the screw shaft 3.

  Subsequently, the operation will be described. When the holding member 40 expands or contracts with respect to the electromagnetic shock absorber, that is, when the holding member 40 moves in the vertical direction in FIG. 3, the ball screw nut 4 connected to the holding member 40 also performs a linear motion in the vertical direction. Here, the electromagnetic clutch D is energized, the holding member 40 that holds the ball screw nut 4 is prevented from rotating with respect to the bracket 46, and no power is supplied to the electromagnet 10. Therefore, since the rotation of the ball screw nut 4 is prevented and the rotation of the screw shaft 3 with respect to the ball screw nut 4 is allowed, the linear motion of the ball screw nut 4 causes the ball screw nut 4 and the screw shaft 3 to rotate. Is converted into a rotational motion of the screw shaft 3, the shaft 1a of the motor 1 rotates, and the motor 1 generates a torque that resists the rotation of the shaft 1a. Thereby, the function as a buffer is similarly demonstrated in 1st Embodiment.

  Next, the vehicle height adjustment function of the electromagnetic shock absorber will be described. First, the electromagnet 10 is energized to attract the ball screw nut 4 to the electromagnet 10. Further, the power supply to the electromagnetic clutch D is cut off. In this state, the motor 1 is energized to rotate the shaft 1a. Then, the screw shaft 3 connected to the shaft 1 a rotates, and the electromagnet 10 that attracts the ball screw nut 4 is restricted from freely rotating with respect to the screw shaft 3, and the holding member 40 that holds the ball screw nut 4. Since the power supply to the electromagnetic clutch D is cut off, the holding member 40 can freely rotate with respect to the bracket 46, and the ball screw nut 4 also rotates in the same manner as the screw shaft 3.

  Then, the holding member 40 that holds the ball screw nut 4 is also rotated by the rotation of the ball screw nut 4, and the intermediate cylinder 45 that is a screwing member that is screwed to the screw portion 42 a provided in the large-diameter cylinder 42 of the holding member 40. Torque acts to rotate. However, since the intermediate cylinder 45 is prevented from rotating with respect to the bracket 46 by the key 45 a provided in the intermediate cylinder 45 and the key groove 46 c provided in the bracket 46, the intermediate cylinder 45 eventually rotates when the holding member 40 rotates. 3 is moved upward or downward in FIG. 3 by the screw mechanism of the screw part 42a and the screw part 45b. Then, the intermediate cylinder 45 is moved upward or downward with respect to the bracket 46, and the basic length of the electromagnetic shock absorber itself changes. In the case of an electromagnetic shock absorber, if no current is supplied to the motor 1, no force in the direction against the load of the vehicle weight is generated unless the motor 1 is supplied with current. Although the axial length is determined and the vehicle height is determined by the vehicle weight, the change in the basic length is only the downward change from the lower suspension spring receiver 50, so that the vehicle height can be adjusted. . Therefore, it is possible to achieve the same operational effects as the first embodiment. The electromagnet 10 can also be used as a damping force generation source, as in the first embodiment.

  Further, a third embodiment will be described. As shown in FIG. 5, the electromagnetic shock absorber according to the third embodiment includes a ball screw nut 4, a screw shaft 83, a motor 1 connected to the screw shaft 83, and axial movement with respect to the screw shaft 83. A connecting member 80 that is only allowed and connected to the screw shaft 83, a holding member 60 that holds a ball screw nut and is provided with a lower suspension spring receiver, a bracket 66 that is a rotation preventing member that prevents the holding member from rotating, and a holding member A screwing member 65 that is rotatably screwed to the member 60 and rotatably connected to the bracket 66, and an electromagnetic clutch D that is a switching means that allows and blocks rotation of the screwing member 65 with respect to the connecting member 80; As in the first embodiment, 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 The electromagnetic force is generated in the motor 1 by transmitting to the motor 1, and the torque against the rotation of the screw shaft 3 generated due to the electromagnetic force is used as a damping force for suppressing the linear motion of the ball screw nut 4. In addition, relative movement in the axial direction between the ball screw nut 4 and the screw shaft 3 can be suppressed.

  More specifically, the upper end of the screw shaft 83 in FIG. 5 is connected to the shaft 1a of the motor 1, and the outer periphery thereof is provided with a screw groove 83a as in the first embodiment. A hollow portion 83b is provided in the shaft center portion. The hollow portion 83b is provided with a key groove (not shown), and a cylindrical connecting member 80 having a key 81 that engages with the key groove is inserted into the hollow portion 83b. Yes. Therefore, only the rotation of the connecting member 80 is restricted with respect to the screw shaft 83 by the key 81 and the key groove, and only the movement in the axial direction, that is, the vertical direction in FIG. 5 is allowed. The screw shaft 83 is also screwed into the ball screw nut 4.

  And the lower end in FIG. 5 of this connection member 80 is connected with the end of the electromagnetic clutch D similar to 1st Embodiment. Specifically, the electromagnetic clutch D is connected to the electromagnet holding member 31, the clutch plate 33, and the clutch plate holding member 36.

  The motor 1 connected to the screw shaft 83 is fixed in the inner cylinder 73, and the screw shaft 83 is also rotatably inserted into the inner cylinder 73 via a ball bearing 74.

  On the other hand, the holding member 60 that holds the ball screw nut 4 includes a small-diameter cylinder 61 and a large-diameter cylinder 62 that is concentric with the small-diameter cylinder 61 and larger in diameter than the small-diameter cylinder 61. Is connected to the lower outer periphery of the small diameter cylinder 61 in FIG. 5, and a key groove 62 a is provided below the large diameter cylinder 62 in FIG. 5. Further, a screw 61a is provided on the lower outer periphery of the small diameter tube 61 in FIG.

  Furthermore, the ball screw nut 4 is connected to the upper end portion in FIG. 5 of the small-diameter cylinder 61 of the holding member 60 configured as described above, and a screw portion 61a of the small-diameter cylinder 61 is screwed to the inner periphery of the cylinder portion. A bottomed cylindrical threaded member 65 having a portion 65a is screwed. Further, a lower suspension spring receiver 79 is provided on the upper outer periphery in FIG. 5 of the large diameter cylinder 62, and the lower end of the suspension spring S is supported.

  An inner cylinder 73 is slidably inserted between the small diameter cylinder 61 and the large diameter cylinder 62. Therefore, also in the present embodiment, the shaft of the screw shaft 3 with respect to the holding member 60 and the ball screw nut 4 is prevented.

Further, the large-diameter cylinder 62 is slidably inserted into a bottomed cylindrical bracket 66, this is on the inner periphery of the cylindrical portion 66a of the bracket 66 key 66d is provided, also, the bottom lower eye 66c is provided, and a hole 66b is provided at the bottom. When inserting the large-diameter cylinder 62 into the bracket 66, the holding member 60 is prevented from rotating with respect to the bracket 66 because the key groove 62a and the key 66d are engaged with each other. Only axial movement is allowed.

  Further, the screwing member 65 screwed to the small diameter cylinder 61 of the holding member 60 is a bottomed cylinder, and a screw part 65a is provided on the inner periphery of the cylinder part, and a shaft 71 is provided on the shaft center part of the bottom part. Is fitted. The upper end of the shaft 71 in FIG. 5 is connected to the other end of the electromagnetic clutch D, specifically the clutch plate holding member 36, and the lower end in FIG. 5 is fitted in the hole 66 b of the bracket 66. The ball bearing 70 is fitted to the inner periphery. Therefore, the screwing member 65 is rotatably connected to the bracket 66.

  Further, in the present embodiment, the electromagnetic clutch D prevents the rotation of the screwing member 65 with respect to the connecting member 80 when energized, and conversely, when the current supply is cut off. The screw member 65 is allowed to rotate with respect to the member 80.

  Since the constituent members of the electromagnetic shock absorber configured as described above are covered with the holding member 60, the inner cylinder 13 and the bracket 66, stepping stones from the road surface, rainwater, etc. are directly applied to the ball screw nut 4 and the motor 1. The electromagnetic clutch D and the screw shaft 3 are prevented from hitting.

  In the electromagnetic shock absorber according to the third embodiment configured as described above, the electromagnetic clutch D is not energized, and the connecting member 80 can freely rotate with respect to the screwing member 65. When the electromagnetic shock absorber expands and contracts, the linear motion of the ball screw nut 4 in the vertical direction in FIG. 5 is converted into the rotational motion of the screw shaft 3, the shaft 1a of the motor 1 rotates, and the motor 1 resists the rotation of the shaft 1a. Generate torque. Thereby, the function as a buffer is similarly demonstrated in 1st Embodiment. At this time, the connecting member 80 can freely rotate, and further, movement in the axial direction with respect to the screw shaft 3 is allowed, so that the rotational movement of the screw shaft 3 is not hindered.

  On the other hand, in the present embodiment, the vehicle height adjustment is realized as follows. In adjusting the vehicle height, the electromagnetic clutch D is energized, and the connecting member 80 is connected to a shaft 71 that is fitted to the screwing member 65. When the motor 1 is rotationally driven in this state, the screw shaft 3 rotates, but the connecting member 80 also rotates in the same manner as the screw shaft 3. Then, the rotational motion of the connecting member 80 is also transmitted to the shaft 71, and the screwing member 65 is rotationally driven. The holding member 60 is prevented from rotating with respect to the bracket 66 and is only allowed to move in the axial direction. The screw between the screw part 65 a of the screwing member 65 and the screw part 61 a provided in the small diameter cylinder 61 of the holding member 60. The holding member 60 is moved upward or downward in FIG. 5 by the mechanism. Therefore, since the holding member 60 can move upward or downward with respect to the bracket 66, the basic length of the electromagnetic shock absorber itself changes. In addition, the change in the basic length is a change only from the lower suspension spring receiver 79, so that the vehicle height can be adjusted. In the present embodiment, it is not necessary to always supply current to the electromagnetic clutch D, and it is more economical because it is only necessary to supply current only when adjusting the vehicle height.

  Incidentally, in the present embodiment, the screwing member is a bottomed cylindrical shape, and the inner periphery of the cylindrical portion is screwed to the outer periphery of the small-diameter tube 61 of the holding member 60, but the shaft 71 is used as the screwing member. Even if the screw part is provided on the outer periphery of the shaft and the screw part is provided on the inner periphery of the small-diameter cylinder 61 of the holding member 60 and the screw part of the shaft and the screw part of the holding member are screwed together, the vehicle height can be adjusted Therefore, it may be configured as such.

  Finally, a fourth embodiment will be described. As shown in FIG. 6, the electromagnetic shock absorber according to the fourth embodiment is obtained by changing the holding member, bracket, and screwing member of the electromagnetic shock absorber according to the third embodiment as follows.

  The difference from the third embodiment will be described in detail. The holding member 85 in the fourth embodiment includes a small diameter cylinder 86 and a large diameter cylinder 87 that is concentric with the small diameter cylinder 86 and larger in diameter than the small diameter cylinder 86. The lower end of the large diameter cylinder 87 in FIG. 6 is connected to the lower end of the small diameter cylinder 86 in FIG. 6, and a key groove 87 a is provided below the large diameter cylinder 87 in FIG. 6. Further, an electromagnetic clutch D is fixed to the outer periphery of the lower end of the small diameter cylinder 86 in FIG. Specifically, the electromagnet holding member 31 of the electromagnetic clutch D is coupled to the inner periphery of the small diameter cylinder 86. The electromagnet holding member 31 may be integrally formed with the small diameter cylinder 61.

  Further, the ball screw nut 4 is connected to the upper end portion in FIG. 6 of the small-diameter cylinder 86 of the holding member 85 configured as described above, and the large-diameter cylinder 87 is suspended on the upper outer periphery in FIG. A spring receiver 79 is provided, and also supports the lower end of the suspension spring S.

  An inner cylinder 73 is slidably inserted between the small diameter cylinder 86 and the large diameter cylinder 87. Therefore, also in the present embodiment, the shaft of the screw shaft 3 with respect to the holding member 85 and the ball screw nut 4 is prevented.

  The large-diameter cylinder 87 has a bottomed cylindrical bracket 90 slidably inserted therein, a key 90b is provided on the inner periphery of the cylindrical portion 90a of the bracket 90, and an eye 90c at the bottom lower end. When the large-diameter cylinder 87 of the holding member 85 is inserted into the bracket 90, the holding member 85 is rotated with respect to the bracket 90 because the key groove 87a and the key 90b are engaged with each other. And only axial movement is allowed. Further, a screw portion 90d is provided on the lower inner periphery of the cylindrical portion 90a of the bracket 90, and a screwing member 92 is screwed to the screw portion 90d.

  Furthermore, the screwing member 92 has a disk shape, and a screw portion 92a is provided on the outer periphery of the screwing member 92 so as to be screwable with the screw portion 90d of the bracket 90, and the shaft 93 stands upright from the shaft center portion. Yes. The upper end of the shaft 93 in FIG. 6 is connected to the other end of the electromagnetic clutch D, one end of which is connected to the connecting member 80, specifically to the clutch plate holding member 36, as in the third embodiment. . Therefore, the screwing member 92 is rotatably connected to the holding member 85. Further, when the electromagnetic clutch D is energized, the screwing member 92 is prevented from rotating with respect to the connecting member 80. On the contrary, when the current supply is cut off, the screwing member 90 is allowed to rotate with respect to the connecting member 80.

  Since the constituent members of the electromagnetic shock absorber configured as described above are covered with the holding member 85, the inner cylinder 13 and the bracket 90, stepping stones from the road surface, rainwater, etc. are directly applied to the ball screw nut 4 and the motor 1. The electromagnetic clutch D and the screw shaft 3 are prevented from hitting.

  Since the configuration other than the above is the same as that of the third embodiment, the description thereof is omitted.

  Now, in the electromagnetic shock absorber according to the fourth embodiment configured as described above, the electromagnetic clutch D is not energized and the connecting member 80 can freely rotate with respect to the screwing member 92. When the electromagnetic shock absorber expands and contracts, the linear motion of the ball screw nut 4 in the vertical direction in FIG. 6 is converted into the rotational motion of the screw shaft 3, the shaft 1a of the motor 1 rotates, and the motor 1 resists the rotation of the shaft 1a. Generate torque. Thereby, the function as a buffer is similarly demonstrated in 1st Embodiment. At this time, the connecting member 80 can freely rotate, and further, movement in the axial direction with respect to the screw shaft 3 is allowed, so that the rotational movement of the screw shaft 3 is not hindered.

  On the other hand, in the present embodiment, the vehicle height adjustment is realized as follows. In adjusting the vehicle height, the electromagnetic clutch D is energized, and the connecting member 80 is connected to a shaft 93 erected from the screwing member 92. When the motor 1 is rotationally driven in this state, the screw shaft 3 rotates, but the connecting member 80 also rotates in the same manner as the screw shaft 3. Then, the rotational movement of the connecting member 80 is also transmitted to the shaft 93 to drive the screwing member 92 to rotate. The holding member 85 is prevented from rotating with respect to the bracket 90 and is only allowed to move in the axial direction. The holding member 85 is formed by a screw mechanism of a screw portion 92a of the screwing member 92 and a screw portion 90d provided on the bracket 90. 85 is moved upward or downward in FIG. Therefore, since the holding member 85 can move upward or downward with respect to the bracket 90, the basic length of the electromagnetic shock absorber itself changes. In addition, the change in the basic length is a change only from the lower suspension spring receiver 79, so that the vehicle height can be adjusted. In the present embodiment, it is not necessary to always supply current to the electromagnetic clutch D, and it is more economical because it is only necessary to supply current only when adjusting the vehicle height.

  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 partial expanded sectional view of the electromagnetic shock absorber in the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the electromagnetic shock absorber in the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the electromagnetic shock absorber in the 4th Embodiment of this invention.

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, 45, 65, 92 Screw member 6, 46, 66, 90 Bracket which is a rotation prevention member 10 Electromagnet 11, 40, 60, which is a switching means 85 Holding member 13, 73 Inner cylinder 20, 50, 79 Lower suspension spring receiver 80 Linking member D Electromagnetic clutch as switching means

Claims (8)

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. Switching means for allowing and preventing rotation of the screw nut with respect to the screw shaft, a holding member for holding the screw nut, a screwing member rotatably engaged with the holding member and linked to the lower suspension spring receiver, and a screwing member An electromagnetic shock absorber comprising: a rotation preventing member for preventing rotation of the motor; and a holding member and the rotation preventing member connected via a switching means for allowing and preventing rotation of the holding member relative to the rotation preventing member. 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. A connecting member that is allowed to move only in the axial direction with respect to the screw shaft and connected to the screw shaft, a holding member that holds the screw nut and is connected to the lower suspension spring receiver, and a rotation blocking member that prevents the holding member from rotating. A screwing member that is rotatably screwed to the holding member and is rotatably connected to the rotation preventing member, and a connecting member and the screwing member via switching means that allows and blocks rotation of the connecting member relative to the screwing member. Electromagnetic shock absorber characterized by being connected. 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. A connecting member that is allowed to move only in the axial direction with respect to the screw shaft and connected to the screw shaft, a holding member that holds the screw nut and is connected to the lower suspension spring receiver, and a rotation blocking member that prevents the holding member from rotating. A screwing member rotatably connected to the holding member and screwed to the rotation preventing member, and a connecting member and the screwing member via switching means for allowing and preventing rotation of the connecting member with respect to the screwing member. Electromagnetic shock absorber characterized by being connected. 2. The electromagnetic buffer according to claim 1, wherein the switching means for allowing and preventing the rotation of the screw nut with respect to the screw shaft is an electromagnet that engages with a key groove provided along the axial direction of the screw shaft. vessel. 2. The electromagnetic buffer according to claim 1, wherein the switching means for allowing and preventing the rotation of the holding member relative to the rotation preventing member is an electromagnetic clutch having one end connected to the holding member and the other end connected to the rotation preventing member. vessel. An inner cylinder that covers the screw shaft or the motor and the screw shaft is provided, a cylindrical holding member is inserted into the inner cylinder, and the inner cylinder is slidably inserted into the cylindrical screwing member. The electromagnetic shock absorber according to 1. The switching means for allowing and preventing rotation of the connecting member with respect to the screwing member is an electromagnetic clutch having one end connected to the connecting member and the other end connected to the screwing member . Electromagnetic shock absorber. The holding member includes a small-diameter cylinder and a large-diameter cylinder concentric with the small-diameter cylinder. A screw nut is attached to the small-diameter cylinder, and the screw shaft or the motor and the screw shaft are covered between the small-diameter cylinder and the large-diameter cylinder. 4. The electromagnetic shock absorber according to claim 1, wherein the cylinder is slidably inserted.

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