Patent ID: 6978679

Claim:
A hydraulic fluid pressure sensor for measuring the pressure of a hydraulic fluid in a pressure chamber, comprising a reservoir housing including a peripheral wall which is connected to the pressure chamber, a partition dividing the interior of the reservoir housing into a reservoir chamber formed on the side of the partition facing the pressure chamber and a sensor chamber on the opposite side of the partition, a throttle passage formed between the interior of the pressure chamber and the reservoir chamber so that hydraulic fluid in the pressure chamber can flow from the pressure chamber into the reservoir chamber, a sensor element connected to communicate with the sensor chamber of the reservoir housing, and said partition comprising a piston which is mounted in the reservoir housing for sliding movement along the interior of the peripheral wall of the reservoir housing so as to generate a frictional force therebetween, and a support spring disposed in the interior of the sensor chamber for biasing the piston in a direction toward the reservoir chamber.