Pressure relief valve for hydraulic system - includes piston moving under effect of thermal expansion caused by adjacent electric heating element

摘要

The drain valve includes a body (100) with an input orifice (101) connected to a pressurised circuit, and an outlet orifice (102) connected to a low pressure reservoir. The body houses a mobile piston (115) forming a valve which is able to block one of the orifices. The piston is operated by the thermal expansion of a material (135) which may for example change state according to the prevailing temp.. An increase in temperature may be achieved by passing current through an electric heating resistance (200) placed near to the thermal material. USE - Valve for relieving pressure in vehicle hydraulic braking system in order to prevent problems from slight permeability of membrane under sustained pressure.