Abstract: Thermostat valves are disclosed for guiding the flow of coolant in an internal combustion engine, which includes three channels with a central valve chamber, the first channel including a first valve seat, and in which the thermostat valve includes a valve housing mounted within the valve chamber and including an opening facing the second channel and including a second valve seat, a tubular valve body movably mounted with respect to the valve housing along a valve axis between a first end position in which the tubular valve body bears against the first valve seat such that the first and second channels are in fluid communication and the first and third channels are blocked, and a second end position in which the tubular valve body bears against the second valve seat such that the first and second channels are in fluid communication and the first and third channels are blocked, and a temperature sensitive switch for moving the tubular valve body between the first and second end positions, in which the valve ho

Abstract: An object of the present invention is to provide a thermostat device which ensures a smooth slide without damaging the slide function by immersion of a cooling liquid, increase flexibility of a circulation channel design by miniaturization, and materializes a hand-operated opening and closing of a valve. In order to solve the problems, the thermostat device 1 in which a heat responding element (wax 3) to expand and shrink by sensing the heating or cooling of the circulating liquid in the circulation channel, is embedded, a sliding member (piston rod 9) is slid in accordance with volume changes caused by the expansion and shrinkage of the expansion element to open and close the valve body, is structured that a sensor case 2 which embeds the responding element is placed in the circulation channel of the circulating liquid, and the sliding member is placed outside of the circulation channel of the circulating liquid.