RESIDUAL PRESSURE SENSOR AND APPARATUS FOR MONITORING THE SAME

摘要

A residual pressure sensor for ascertaining a zero residual pressure, and an apparatus for monitoring the sensor for failure thereof. In order to detect a residual pressure reduced to zero, the condition of variation of an output from a residual pressure sensor is detected. This residual pressure sensor is not allowed to generate an output representative of zero residual pressure while the first-mentioned output varies. The energizing condition of a driving solenoid (21) for a solenoid valve which is adapted to open and close a pressure supply passage is monitored by using a current sensor (21) of a fail-safe structure adapted to detect the presence of a current and output a logical value 0, and detect the absence of a current and output a logical value 1, and the residual sensor is monitored for failure based on the monitor output condition of the current sensor and the output condition of the residual pressure sensor. <IMAGE>