Abstract: A thermostat device useful in a cooling system circulating liquid coolant has a valve, a cylindrical valve seat having an inner peripheral surface, and a circular sealing lip elastically pressure welded to the inner peripheral surface when the valve is closed, the sealing lip forming a waveform having concavity and convexity curving in the valve drive direction due to a thermo-sensitive movable body, allowing displacement of the contact position of the sealing lip with the inner peripheral surface when the valve is closed in the valve drive direction according to the position in the circumferential direction of the circular sealing lip, which device stabilizes system operation during initial valve opening, and which device stabilizes the liquid coolant temperature.

Abstract: An apparatus includes a movable temperature sensing member capable of sensing mainly the temperature of high-temperature coolant flowing in from a high-temperature coolant port and driving toward the side of the high-temperature coolant port in dependence upon the sensed temperature; a main valve fitted integrally to the movable temperature sensing member and constructed so as to render a low-temperature coolant port and a mixing compartment openable in conformity to the driving of the movable temperature sensing member toward the side of the high-temperature coolant port, thereby controlling the inflow rate of low-temperature coolant from the low-temperature coolant port to the mixing compartment; and a high-temperature coolant inducing part communicating with the high-temperature coolant port and adapted to regulate the flow of high-temperature coolant from the high-temperature coolant port toward the surround of the movable temperature sensing member and effect outflow thereof to the mixing compartment.

Abstract: Provided is a thermostat device which improves the assembling work, reduces the manufacturing cost, and transfers heat to a temperature sensing/operating part more efficiently.