JP2005256921A - Electromagnetic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a degree of freedom of a design of an electromagnetic shock absorber by enabling change in rotation amount of a motor. <P>SOLUTION: This electromagnetic shock absorber is provided with a motion converting mechanism converting relative linear motion of one member and the other member into rotary motion, and the motor 1 to which the rotary motion is transmitted, and damps the linear motion by the electromagnetic force of the motor 1. The motion converting mechanism comprises a rack 4 and a pinion gear 2 connected to the motor 1, and the gear ratio of the motion converting mechanism can be varied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electromagnetic shock absorber that uses an electromagnetic force of a motor as a damping force.

  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. In this case, the motion conversion mechanism includes a screw shaft and a ball screw nut.
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, an electromagnetic shock absorber that employs a configuration that transmits the rotational movement of the screw shaft to the motor by connecting the above-described conventional screw shaft and the motor shaft is superior in that it does not require oil or air. However, there are the following problems.

  In the conventional electromagnetic shock absorber, even if the screw shaft and the ball screw nut move relative to each other in the axial direction, the gear ratio of the motion conversion mechanism constituted by the screw shaft and the ball screw nut is constant. The motor also rotates in proportion to the ball screw nut and the relative movement speed.

  Therefore, since the rotation speed of the motor is proportional to the relative speed, the rotation amount of the motor cannot be changed, and the degree of freedom in design is small.

  Therefore, the present invention was created in consideration of the above-mentioned problems, and the object of the present invention is to improve the degree of freedom in designing the electromagnetic shock absorber by changing the rotation amount of the motor. It is in.

  In order to achieve the above-described object, the electromagnetic shock absorber according to the first problem solving means of the present invention has a motion conversion mechanism that converts relative linear motion of one member and the other member into rotational motion, and the rotational motion is transmitted. A motion converting mechanism comprising a rack and a pinion connected to the motor, and the motion converting mechanism is an electromagnetic shock absorber that is used as a damping force that attenuates the linear motion by the electromagnetic force of the motor. The gear ratio is variable.

  The second problem solving means is characterized in that, in the first problem solving means, the rack pitch near the neutral point is reduced.

  Further, the third problem solving means is characterized in that, in the first or second problem solving means, the pitch on the end side of the rack is reduced.

  According to the invention of each claim, by making the gear ratio of the motion conversion mechanism variable, the amount of rotation of the motor with respect to the amount of movement of the rack can be changed, and in an environment where an electromagnetic shock absorber such as a vehicle is applied. A suitable electromagnetic shock absorber can be designed, and the degree of freedom in designing the electromagnetic shock absorber can be improved.

  According to the invention of claim 2, since the rack pitch is set to be small in the vicinity of the neutral point of the electromagnetic shock absorber, the motor rotation amount is larger than the rack movement amount in the vicinity of the neutral point. It is set to be. Therefore, particularly when used in a vehicle, the motor can be driven efficiently and a large electromagnetic force can be generated in the minute stroke band that is frequently used.

  That is, a sufficient damping force can be generated even in this minute stroke band, and the influence of the dead zone of the motor can be reduced in this minute stroke band. In addition, since the amount of rotation of the motor can be increased sufficiently even in the minute stroke band, it is advantageous in terms of resolution and the controllability of the electromagnetic shock absorber is improved. Therefore, the controllability of the vibration in the minute stroke band near the neutral point of the electromagnetic shock absorber is improved.

  According to the third aspect of the present invention, if the pitch on the end side of the rack is reduced, the amount of rotation of the motor relative to the amount of movement of the rack is increased at the time of maximum compression and extension of the electromagnetic shock absorber. Thus, a larger electromagnetic force can be generated, so that the movement of the rack can be suppressed by the large electromagnetic force and the impact at the time of the maximum compression or the maximum compression can be reduced.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a perspective view of an electromagnetic shock absorber according to an embodiment of the present invention.

 As shown in FIG. 1, the electromagnetic shock absorber according to the present embodiment is slid onto the motor 1, the pinion gear 2 fitted to the shaft 1 a of the motor 1, the rack guide 3 that holds the motor 1, and the rack guide 3. The rack 4 is freely attached, and the pinion gear 2 is engaged with the rack 4 to form a motion conversion mechanism. When the rack guide 3 and the rack 4 move relative to each other, that is, when the electromagnetic shock absorber expands and contracts, the linear motion in the vertical direction of the rack 4 in FIG. 1 is converted into the rotational motion of the pinion gear 2, and this rotational motion. 1 can be transmitted to the motor 1, and the electromagnetic force of the motor 1 can suppress or promote the linear motion of the rack 4 in the vertical direction in FIG. 1.

  More specifically, the rack 4 includes an elongated rack body 4a, a plurality of teeth 4b that mesh with the pinion gear 2 provided on the rack body 4a, and a bracket 4c provided at the lower end of the rack body 4a in FIG. And a groove 4d that engages with a trapezoidal locking portion 3b provided along the longitudinal direction in FIG. 1 of the rack guide 3 provided on the surface opposite to the surface on which the teeth 4a of the rack 4 are formed. And a linear bearing (not shown) provided in the groove, and the pitch of the rack 4 is set to be small near the neutral point of the electromagnetic shock absorber. That is, the pitch at the upper and lower ends of the rack body 4a is larger than the pitch near the neutral point.

  The rack guide 3 extends from the side of the rack guide body 3a, a long plate-shaped rack guide body 3a, a locking portion 3b that engages with the linear bearing and groove of the rack 4 formed in the rack guide body 3a. The motor holding portion 3c is provided and a bracket 3d provided at the upper end of the rack guide main body 3a in FIG. The rack 4 is slidably attached to the rack guide 3 by engaging the groove 4d of the rack 4 with the locking portion 3b. Therefore, the rack 4 is allowed to move only in the vertical direction in FIG. 1 with respect to the rack guide 3 by the engagement of the locking portion 3b and the groove 4d of the rack 4. Further, as long as the rack guide 3 of the rack 4 is only allowed to move in the vertical direction in FIG. 1, it is only necessary to provide the locking portion 3b and the groove 4d. In the case of the present embodiment, a linear bearing is used. Since it is provided, the rack 4 can move smoothly with respect to the rack guide 3. Further, as a means for allowing the rack guide 3 of the rack 4 to move only in the vertical direction in FIG. 1, the shape of the locking portion 3b and the groove 4d may be other shapes, and the locking portion 3b. In addition to the groove 4d, other known means may be used.

  Further, since the motor 1 held by the motor holding portion 3c is attached to the rack guide 3, when the rack 4 moves in the vertical direction in FIG. Will also move up and down in FIG.

  When the motor 1 is described as an example of a brushless motor, although not shown in detail, a hollow frame, a shaft 1a rotatably inserted into the frame, a coil wound around a core attached to the inner periphery of the frame, The three-phase brushless motor is composed of a plurality of magnets attached to the shaft 1a, and the magnets are provided to face the coil and the core. Each electrode 10 of the motor 1 is set so as to obtain a desired damping force when connected to an external power source, a control circuit, or the like or short-circuited. Although the motor 1 has been described as a brushless motor in the present embodiment, 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. When this electromagnetic shock absorber is used as an active suspension, it is possible to drive the motor 1 by actively energizing the motor 1 so that it functions not only as a shock absorber but also as an actuator.

  Further, a pinion gear 2 is fitted on the shaft 1 a of the motor 1, and the pinion gear 2 is meshed with the teeth 4 b of the rack 4. That is, when the rack 4 linearly moves in the vertical direction in FIG. 1 with respect to the rack guide 3, the linear motion of the rack 4 is converted into the rotational motion of the pinion gear 2 by the mechanism of the rack 4 and the pinion gear 2, and the motor 1 The shaft 1a also exhibits rotational movement.

  And as for the electromagnetic shock absorber comprised as mentioned above, the one side member and other member of the attachment location where this electromagnetic shock absorber is applied, for example, the vehicle body side member which is one member of the vehicle, and the axle side member which is the other member, These are interposed via brackets 3d provided on the rack guide 3 side and brackets 4c provided on the rack 4 side, respectively.

  Moreover, since the pitch of the rack 4 is small in the vicinity of the neutral point of the electromagnetic shock absorber, the gear ratio becomes large at the neutral point of the electromagnetic shock absorber, and the electromagnetic shock absorber is expanded or compressed. And the gear ratio becomes small. That is, the gear ratio changes depending on the stroke amount of the electromagnetic shock absorber. Here, the neutral point of the electromagnetic shock absorber specifically refers to the side of the vehicle body when the electromagnetic shock absorber is applied to the application location and is in a stationary state. The state when the member is suspended and balanced by the suspension spring is described, and therefore the pitch of the rack 4 is set to be small at the position where the pinion gear 2 in the state meshes with the rack 4.

  It continues and demonstrates the effect | action of the electromagnetic shock absorber of this Embodiment mentioned above. When the motor 1 of the electromagnetic shock absorber is not energized by an external power source, the mechanism of the rack 4 and the pinion gear 2 is expanded and contracted to the electromagnetic shock absorber, that is, when the rack 4 moves in the vertical direction in FIG. Thus, the linear motion of the rack 4 is converted into the rotational motion of the shaft 1 a of the motor 1.

  Then, the coil in the motor 1 crosses the magnetic field of the magnet, an induced electromotive force is generated in the coil, and the motor 1 generates a torque against the rotation of the shaft 1a caused by the induced electromotive force. The torque against the rotation of the shaft 1a suppresses the linear motion of the rack 4 because the shaft 1a is connected to the pinion gear 2.

  Therefore, the action of suppressing the rotational movement of the shaft 1a of the motor 1 works to suppress the linear movement of the rack 4, so that it acts as a damping force that suppresses the linear movement of the rack 4 and absorbs and relaxes vibration energy. As described above, the function as an electromagnetic shock absorber can be exhibited by a series of operations.

  Further, when the motor 1 is energized by an external power source, the linear motion of the rack 4 can be suppressed or promoted by the electromagnetic force generated by the motor 1, and in this case, the actuator function is also exhibited and active. It can be used as a suspension.

  As described above, the pitch of the rack 4 is set so as to decrease near the neutral point of the electromagnetic shock absorber. Therefore, the rotation amount of the motor 1 is less than the movement amount of the rack 4 near the neutral point. It is set to increase. Therefore, particularly when used in a vehicle, the motor 1 can be driven efficiently and a large electromagnetic force can be generated in the minute stroke band that is frequently used.

  That is, a sufficient damping force can be generated even in this minute stroke band, and the influence of the dead zone of the motor 1 can be reduced in this minute stroke band, and the rotation state of the motor 1 is used for control. In this case, the amount of rotation of the motor 1 can be sufficiently increased even in a minute stroke band, which is advantageous in terms of resolution and improves the controllability of the electromagnetic shock absorber. In particular, in the present embodiment, since the pitch near the neutral point of the rack 4 is reduced, the controllability of the vibration in the minute stroke band near the neutral point is improved.

  In the above description, the rack pitch near the neutral point of the electromagnetic shock absorber is reduced. In addition to this, if the pitch on the end side of the rack is reduced, the maximum amount of the electromagnetic shock absorber. At the time of compression and maximum extension, the amount of rotation of the motor relative to the amount of movement of the rack can be increased so that a large electromagnetic force can be generated by the motor. The impact at the time of compression or the maximum compression can be reduced.

  Therefore, by making the gear ratio of the motion conversion mechanism variable, the rotation amount of the motor 1 with respect to the movement amount of the rack 4 can be changed, and the electromagnetic shock absorber suitable for an environment where an electromagnetic shock absorber such as a vehicle is applied. Thus, the degree of freedom in designing the electromagnetic shock absorber is improved.

  In the above description, the case where the electromagnetic shock absorber is applied particularly to a vehicle has been described. However, it goes without saying that the electromagnetic shock absorber can be used in a portion where the normal shock absorber is used.

  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 perspective view which shows in principle the electromagnetic shock absorber in one embodiment of this invention.

Explanation of symbols

1 Motor 1a Shaft 2 Pinion Gear 3 Rack Guide 4 Rack

Claims (3)

An electromagnetic system comprising a motion conversion mechanism that converts relative linear motion between one member and the other member into rotational motion, and a motor that transmits the rotational motion, and is used as a damping force that attenuates the linear motion by the electromagnetic force of the motor. In the shock absorber, the motion converting mechanism includes a rack and a pinion connected to a motor, and the gear ratio of the motion converting mechanism is variable. 2. The electromagnetic shock absorber according to claim 1, wherein a pitch interval between racks near a neutral point is reduced. The electromagnetic shock absorber according to claim 1 or 2, wherein a pitch on an end portion side of the rack is reduced.

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