GB703354A - Device moved by evaporation and condensation of fluid - Google Patents

Abstract

703,354 Temperature-responsive actuating-elements. WILKINS, E. G. April 3, 1951 [April 4, 1950], No. 8489/50. Class 64(2) [Also in Group XXIX] A device moved by evaporation and condensation of low boiling-point fluid comprises interconnected chambers containing the fluid which are carried by a float or floatable vessel, the chambers being so arranged on the float that one of the chambers may be exposed alternately to a temperature above and below the boiling point of the fluid and the device so moved. The fluid may be monofluorotrichloro-methane. In one embodiment, Fig. 2, the device is in the form of a toy duck which is floated in a hot bath; the vapour pressure of the low boiling-point liquid in the tank 15 forces some liquid up the tube 16 into the tank 14. When sufficient liquid has collected in the upper tank the duck overbalances, the liquid in the tank 14 thus evaporating and forcing the liquid back into the tank 15 so that the duck's head rises again. In another embodiment, Fig. 3, the device comprises a hollow metal sphere 17, having one or more small openings in its lower part, and an upper chamber 20, containing low boiling-point liquid, connected by a pipe 21 to a rubber bag 19. When the device is placed in a hot bath the water passes into the sphere through its small bottom openings and the device sinks. The low boiling-point liquid in the chamber 20 then evaporates and the vapour passes down the pipe 21 and expands the bag 19 which expels the water from the sphere through a large opening 18. The device then rises until the chamber 20 is out of the water when the vapour in the bag passes up the pipe 21, condenses in the chamber 20 and the device again sinks. An inverted cap 22 having a one-way valve 23 allows rapid descent and slow ascent.