Abstract A thermal actuator comprising a pressure chamber, expansible material responsive to heat in the chamber, and a piston shaft driven by the expansible material, the shaft being slidable in a bearing in the actuator housing and having an enlarged inner end which prevents complete ejection from the actuator by becoming embedded in the bearing in the event the shaft is expelled from the pressure chamber due to excessive pressure resulting from conversion of the expansible material from its liquid state to a gaseous condition by overheating. The piston shaft is slidable through a seal and polyethylene washer bearing on the pressure chamber side of the seal, said washer gradually coming into solution with and increasing the viscosity of the expansible material in the normal operation of the actuator.
A thermal actuator comprising a. a high pressure housing having a pressure chamber and a heating element therein, b. expansible material responsive to heat in the chamber, said material being convertible to gaseous state by overheating, c. a bearing fixedly mounted in the housing, d. a piston shaft slidable in the bearing, said shaft having an enlarged inner end in the pressure chamber which becomes embedded in and is held captive in the bearing in the event the shaft is expelled from the pressure chamber by overheating of the expansible material, whereby complete ejection of the shaft from the actuator is prevented, and e. a seal and a washer surrounding the piston shaft, the washer being located on the pressure chamber side of the seal and soluble in the expansible material when heated to increase the viscosity of the solution and the sealing capacity of the seal.
Claim 2
Dependent Claim
14 words
The actuator defined by claim 2, in which the washer is made of polyethylene.
Claim 3
Dependent Claim
33 words
The actuator defined by claim 2, in which the seal is located in a recess in the bearing and contacts a shoulder formed in the housing adjacent the end of the pressure chamber.
Claim 4
Dependent Claim
24 words
The actuator defined by claim 4, in which the washer is fitted tightly in the pressure chamber end of the housing adjacent the seal.
Claim 5
Dependent Claim
93 words
A thermal actuator comprising a. a high pressure housing having a pressure chamber and a heating element therein, b. expansible material responsive to heat in the chamber, c. a bearing fixedly mounted in the housing, d. a piston shaft slidable in the bearing, e. a seal surrounding the shaft between the bearing and pressure chamber, and f. a washer adjacent the seal made of material soluble in the expansible material when subjected to heat and having high viscosity when melted which increases the viscosity of the solution and sealing capacity of the seal.
Claim 6
Dependent Claim
15 words
The thermal actuator defined by claim 6 in which the washer is made of polyethylene.