Wax thermostatic element
Type of transducer
The wax thermostatic element was invented in 1934 by Sergius Vernet (1899–1968). Its principal application is in automotive thermostats used in the engine cooling system. The first applications in the plumbing and heating industries were in Sweden (1970) and in Switzerland (1971).
Wax thermostatic elements transform heat energy into mechanical energy using the thermal expansion of waxes when they melt. This wax motor principle also finds applications besides engine cooling systems, including heating system thermostatic radiator valves, plumbing, industrial, and agriculture.
Automotive thermostats
The internal combustion engine cooling thermostat maintains the temperature of the engine near its optimum operating temperature by regulating the flow of coolant to an air-cooled radiator. This regulation is now carried out by an internal thermostat. Conveniently, both the sensing element of the thermostat and its control valve may be placed at the same location, allowing the use of a simple self-contained non-powered thermostat as the primary device for the precise control of engine temperature. Although most vehicles now have a temperature-controlled electric cooling fan, "the unassisted air stream can provide sufficient cooling up to 95% of the time" and so such a fan is not the mechanism for primary control of the internal temperature.
Research in the 1920s showed that cylinder wear was aggravated by condensation of fuel when it contacted a cool cylinder wall which removed the oil film.
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This entry incorporates text from “Wax thermostatic element” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.