Patent ID: 9683625
Date: 2017-06-20
CPC Classifications: B62K,F16F

Claim:
1. A shock absorber comprising: a tubular cylinder; a piston rod configure to proceed into and recede from the cylinder; a piston joined to the piston rod; an extension-side chamber and a compression-side chamber configured to be formed inside the cylinder, separated from each other by the piston, and filled with a working fluid; a tank arranged outside the cylinder and configured to have the working fluid reserved therein; passages connecting between the extension-side chamber and the compression-side chamber and between the cylinder and the tank, the passages comprising: an extension-side damping valve provided in the first extension-side discharge passage and configured to apply predetermined resistance to the working fluid passing through the first extension-side discharge passage; an extension-side electromagnetic pressure control valve provided in the second extension-side discharge passage and configured to control a pressure in the extension-side chamber; a compression-side damping valve provided in the first compression-side discharge passage and configured to apply predetermined resistance to the working fluid passing through the first compression-side discharge passage; and a compression-side electromagnetic pressure control valve provided in the second compression-side discharge passage and configured to control a pressure in the compression-side chamber, wherein the extension-side electromagnetic pressure control valve and the compression-side electromagnetic pressure control valve change an opening degree of the second extension-side discharge passage or an opening degree of the second compression-side discharge passage so that a pressure in the extension-side chamber or the compression-side chamber matches a predetermined constant target pressure when a piston speed is in a first speed range, the extension-side electromagnetic pressure control valve and the compression-side electromagnetic pressure control valve are controlled so that the opening degree of the second extension-side discharge passage or the opening degree of the second compression-side discharge passage becomes maximum when the piston speed is in a second speed range set to a range faster than the first speed range, the first extension-side discharge passage bypasses the extension-side electromagnetic control valve, and the first compression-side discharge passage bypasses the compression-side electromagnetic control valve.