The invention relates to a thermal servomotor which includes two operating elements particularly bellows boxes, which act oppositely on a valve actuating bridge. Each operating element has a temperature-dependent filling. Each operating element is connected to a relatively small container having a volume on the order of 0.2 cm.sup.3 by a capillary passage which has the effect of partially thermally insulating each operating element from the associated container. Each container contains the medium of the filling that determines the pressure and separate heating apparatus is associated with each of the two containers.

An engine powered by low boiling liquid and adapted to operate upon partial immersion in a heated liquid, which may be solar heated, is provided by a circular train of tubular compartments in which adjacent compartments are sealed to interconnectors and the train is tied to a central axle so that rotation of the train will rotate the axle. The interconnectors have an opening and a tube extending forwardly into the leading compartment, and one way valves permit rearward movement through the tube while preventing forward movement through the tube, and this allows liquid in the bottom compartment to be pumped rearwardly to a descending compartment to power the engine while liquid in an ascending compartment drains rearwardly to minimize the drag on the engine.

The solar-differential temperature motor consists of a relatively warm evaporator chamber inside a transparent enclosure which is designed to absorb and trap solar energy. The evaporator chamber is paired with a relatively cold condensor chamber shielded from direct solar radiation by non-transparent barriers. The cold chamber is cooled by evaporation of water from its surfaces or by immersion in a relatively cold body of water. Insides of warm and cold chambers are sealed from the outside environment and contain a low boiling point fluid. By closing and opening of a communication between the vapor phases of the chambers cyclic difference in vapor pressures between the chambers is obtained. Pressure differences are translated into motion by means of a movable part of the chambers which responds to changes in pressures in the chambers. A predetermined resistance of the moving part and synchronization of moving part with the opening and closing of communication between the vapor phases provides a cyclic movement of the moving part. By means of proper linkage the movement is translated into useful work. Pump or gravity means are provided for the return of condensed liquid from cold to warm chamber. In one form of the invention the liquid phase of the warm chamber is separated from the vapor phase of the warm chamber during opening of communication between vapor phases of warm and cold chambers.

A container lid is released at a desired point in a sterilizing cycle with the actuating movement being provided by an expandable chamber having a quantity of sterilizing environment captured during the sterilizing cycle.

The invention relates to a valve assembly. A closure member for the valve unit is controlled directly or indirectly by a movable wall of an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The pressure exerted by the vapor phase of the medium provides a bias which is directly related to the temperature of the liquid phase. A heat transfer element such as a heating resistor in the liquid phase is heated or allowed to cool in a controlled manner by an external control unit. A temperature responsive sensor element in the liquid phase of the medium is part of a feedback system for the control unit which allows a selected temperature to be maintained in the chamber which results in a desired constant pressure to be maintained in the chamber. A pilot valve unit is disposed between the valve closure member and the movable wall. An expansible chamber behind the closure member houses a spring for biasing in a valve closing direction. A bypass throttle passage has a first section extending from the valve inlet to the expansible chamber and a second section extending from the expansible chamber to the valve outlet. The pilot valve unit includes a valve element operably connected to the movable wall for controlling fluid flow through the second bypass section and thus control the opening of the valve closure element.