Shock absorber

Abstract

A shock absorber (D) comprises a screw shaft (1), a screw nut (4) rotatably screwed with the screw shaft (1), a motor (M) having a rotor (R) connected to the screw nut (4), and a rotation stop mechanism (5) for disabling the screw shaft (1) from rotation. Since the screw shaft (1) is linearly moved and the rotation stop mechanism (5) is installed to disable the screw shaft (1) from rotation, the outer diameter of the shock absorber (D) can be reduced, and whereby, the performance of mounting the shock absorber (D) onto a vehicle can be improved.

Description

technical field [0001] This invention relates to improvements in buffers. Background technique [0002] As shown in Japanese Patent Laid-Open Publication No. 08-197931, this buffer is composed of a coil spring as a suspension spring elastically supporting the vehicle body, a screw shaft that is freely rotatable and screwed with a ball nut connected to the axle side, and a connection between the screw shaft and the screw shaft. It is composed of a motor connected at one end and connected to the vehicle body side. The relative movement of the vehicle body and the axle is actively controlled by using the rotational torque generated by the motor. In addition, a shock absorber in which hydraulic shock absorbers are arranged in series in the above structure has also been published. [0003] However, the shock absorber shown in JP-A-08-197931 has a structure in which the screw shaft is rotated and the ball nut is linearly moved in the up-and-down direction. In the above structure,...

AI Technical Summary

Problems solved by technology

[0003] However, the shock absorber shown in JP-A-08-197931 has a structure in which the screw shaft rotates and the ball nut moves linearly in the up and down direction. It is not clearly stated in the Japanese Patent Laid-Open Publication No. 08-197931, but in order to realize the above configuration, it is necessary to stop the rotation of the motor and the ball nut

[0004] In the above structure, the ball nut is supported on the part on the axle side through the cylinder to stop the rotation, but it is necessary to additionally install the rotation stopper of the motor. If the If the anti-rotation device is installed on the outer periphery of the motor frame, the outer diameter of the buffer will be enlarged accordingly.

[0005] In addition, in the above-mentioned buffer, the structure of setting the hydraulic shock absorber in series directly above the motor is also adopted, but in such a structure, due to the high input When the high-frequency vibration occurs, the inertial mass of the rotating parts is large. Therefore, the motor and the motion conversion mechanism also complement each other with the friction force of the rotating system, and cannot perform stretching action, resulting in the result that the motor is directly vibrated by the high-frequency vibration. Due to the high-frequency The acceleration of the vibration is also large, so there is a problem in the reliability of the shock absorber

[0006] Therefore, although it is considered to arrange the hydraulic shock absorber on the side closer to the axle than the motor, this results in the installation of the cylinder supporting the ball nut on the hydraulic shock absorber. construction on the drive, additional ball nut stoppers are required

[0007] Also, in the case of connecting the cylinder to the piston rod of the hydraulic shock absorber, the ball nut is prevented from rotating by preventing the rotation of the rod, but the When the anti-rotation device is installed in the rod guide part that supports the rod of the hydraulic shock absorber, the section of the guide rod cannot be formed into a circle, and the sealing structure of the hydraulic shock absorber is complicated and difficult to seal. If the shock absorber is installed elsewhere, the outer diameter of the hydraulic shock absorber will increase, the overall size of the device will increase, and the mountability on the vehicle will deteriorate.

[0008] In addition, in the case where the cylinder supporting the above-mentioned ball nut is connected to the cylinder part, a stopper is provided on the outer peripheral side of the cylinder part, which also makes the hydraulic shock absorber The outer diameter of the device is enlarged, in short, the overall device becomes larger, and the mountability to the vehicle is poor.

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