Fail safe thermostat for engine cooling system - has holes in shut off element blanked by alloy which melts on thermostat failure to prevent overheating

摘要

A frame (12) is fixed to a circular valve seat (14) forming an opening which allows coolant liquid to circulate. A shaft (16) is fixed to the frame and passes through the opening into a reservoir (18) containing a thermosensitive product. Contraction or expansion of the product causes relative movement between the shaft and reservoir. A shut off element (20) is fixed to the reservoir and moves with it. A coil spring (22) around the reservoir is in contact with the shut off element and the frame to return the shut off element to a closed position. In the event of failure of the reservoir to move the spring maintains the thermostat in the closed position. Orifices in the shut off element are blanked off with a fusible which melts alloy at a predetermined temperature. If the thermostat mechanism fails the alloy melts to allow circulation of coolant to prevent overheating of the engine.