Thermo-element

A thermo-element including a thermally expandable component made of a wax which is expandable and contractible by a temperature change, expansion and contraction of said wax causing a piston to move in and to move out, said thermo-element comprising:

• a cylindrical casing, one end portion thereof being open for enclosing said wax therein;
• a cylindrical guide member which engages said one end portion of said casing;
• a piston held inside said guide member so that said piston can slide freely;
• and
• a thick sealing member arranged between said guide member and said wax for enclosing said wax in said casing and for moving-in and moving-out said piston, wherein
• said thick sealing member is formed of a rubber elastomer;
• said thick sealing member has a piston insertion bore formed in a central portion thereof for supporting one end portion of said piston;
• said thick sealing member has a thin portion at an end portion of said piston insertion bore, an annular rib arranged at an outer peripheral region for sealing said wax and a thick portion having a high thickness between said thin portion and said rib;
• one surface of said thick portion is in contact with a contact surface of a base of said guide member and the other surface of said thick portion is in contact with said wax;
• and
• as said wax expands by a temperature change, said thick portion and said thin portion of said thick sealing member are deformed and thus push up said piston.

A thick sealing member used in a thermo-element, wherein a wax expandable and contractible by a temperature change is used as a thermally expandable component, expansion and contraction of said wax causing a piston to move in and to move out, said thick sealing member:

• being composed of a rubber elastomer;
• and including
• a piston insertion bore formed in a central portion thereof for supporting one end portion of said piston;
• a thin portion at an end portion of said piston insertion bore;
• an annular rib arranged at an outer peripheral region;
• and
• a thick portion having a high thickness between said thin portion and said rib, wherein said thick portion and said thin portion are deformable by a pressure from said wax and push up said piston.