Sensor for measuring the speed and/or position of a piston in relation to that of the cylinder it moves inside of in a dashpot or shock absorber

A sensor for measuring selectively speed and position of a piston relative to a cylinder in a dashpot for motor vehicles, comprising:

• a cylinder and a piston mounted on a piston rod movable within said cylinder, said cylinder being a first part and said piston and piston rod being a second part in said dashpot;
• a permanent magnet mounted on one of said first and second parts;
• a sensor winding mounted on the other one of said first and second parts and having a coreless cylindrical coil cooperating operatively with said magnet and having sensor leads;
• a first auxiliary coil with first leads, mounted on the other one of said first and second ports, at one end of said sensor winding;
• and a second auxiliary coil with second leads, mounted on the other one of said first and second parts, at another end of said sensor winding, relative motion between said piston and said cylinder producing linear relative motion between said magnet and said sensor winding and inducing a voltage in said cylindrical coil dependent on relative velocity between said magnet and said sensor winding due to relative motion between said piston and said cylinder, said first auxiliary winding and said second auxiliary winding being locates respectively at first and second end positions of travel of said piston, said magnet inducing voltages in said first auxiliary winding and said second auxiliary winding when reaching respectively said first and second end positions.