Thermal element and parts therefor and methods of making the same

摘要

A thermal element having a cylinder member carrying a piston member that projects out of an opening of an end of the cylinder member to be extended and retracted relative thereto upon changes of sensed temperature. A washer-like resilient seal member is carried by the end of the cylinder member and has an opening therethrough that press-fittingly receives the piston member therethrough in such a manner that an inner peripheral portion of the washer-like seal member is turned into substantially parallel sealing and wiping engagement with the stem while being substantially transverse to the remainder of the washer-like seal member, the washer-like seal member containing abrasive material therein to provide a scraping action of the inner peripheral portion thereof against the piston member to clean the same as the piston member is moved relative thereto.