PURPOSE: To enable detection of a relative speed between positions on and below a coil spring without any differentiation processing using a compression force working on a car body from the spring.
CONSTITUTION: In a shock absorber 6, a piston not illustrated is inserted into a cylinder 4 axially free to slide. The piston is connected to one end of a piston rod 7 while the other end of the piston rod 7 is mounted on the body 1 through an upper support 2. The cylinder 4 is provided with a spring receiver 10 and a coil spring 3 is arranged between a sensor section 3 and the spring receiver 10 being compressed beforehand. As the coil spring 3 is arranged being compressed, a compression force works on the sensor section 5 even at the initial state. A piezoelectric body is provided inside the sensor section 5 and a rate of change in compression force, namely, relative speed is taken out as voltage by the piezoelectric body and a resistance.
TERAMURA EIJI
HOUDAIRA KINJI
