Abstract: The invention relates to control apparatus for heat actuated devices of the type having a heating resistor and a spring biased motor member movable in response to heat generated by the resistor. A source of rectified AC voltage for the heating resistor is regulated by a controlled rectifier in series with the resistor. There is a comparator circuit for comparing a desired setting with the actual position of the motor member and generating a continuously variable control signal of a value corresponding to the departure value. An ignition circuit for pulsing the controlled rectifier has inputs including the control signal, a half wave AC voltage and a time dependent decreasing signal. The ignition circuit has an input threshold below which pulses are generated and above which pulses are not generated.

Abstract: The invention relates to a hydrostatic steering device comprising a servo-motor operable in dependence on direction and a control device having connections for a pump, a tank and the servo-motor as well as a valve arrangement which influences the flow of pressure medium from the pump to the servo-motor and from the latter to the tank and having two valve members which are relatively movable against the force of a neutral position spring depending on the comparison of the adjustment of a steering element and the follow-up motion of a metering motor.

Abstract: The invention relates to a valve unit for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The 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 in a valve closing direction 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 in a valve closing direction to be maintained in the chamber.

Abstract: The invention relates to a steering control unit for a bidirectional servomotor which is connectable to steerable wheels. A steering wheel controlled quantity setting unit of a known type has ports connectable to a pump and a return tank and two control ports through which metered quantities of fluid flow to opposite sides of the servomotor and to other parts of the apparatus for actuating the servomotor. A directional control valve for selectivity directing pressurized fluid from a power circuit to opposite sides of the servomotor is controlled by a control circuit containing the setting unit. A utility valve having the pressure regulating and control and power valve capabilities required for this type of apparatus is characterized by having only a single slide spool for performing all of these functions.

Abstract: The invention relates to a fluid pressure supply and exhaust system for controlling a two part servomotor wherein relative loads are anticipated for one side of the servomotor. The system has a switching valve unit for selecting parallel supply and exhaust branches to direct supply fluid to the servomotor side subjected to negative loading. There are pressure regulating and throttling valves in the supply branch and a reducing valve in the exhaust branch. The supply pressure downstream from the throttle valve is directed to the reducing valve with a valve closing effect so that a sharp negative load will simultaneously reduce the supply pressure to the servomotor while increasing the throttling of the return flow.

Abstract: The invention relates to an atomizer burner assembly for oil burners. The assembly has electric heating apparatus for maintaining a relatively constant temperature for the oil supply over a range of throughputs which may vary for different atomizer nozzles, for example, from 0.5 to 2.5 l/h. The heating apparatus includes a PTC resistor mounted in the supply pipe in series with a near zero temperature coefficient heating element which surrounds the supply pipe at a longitudinal position between the PTC resistor and the atomizer nozzle. The PTC resistor controls the heat generated by the heating element in accordance with the temperature of the throughput oil to maintain a constant temperature for the throughput oil.

Abstract: The invention relates to a valve assembly for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a reference pressure generator having 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 for controlling the valve and 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 in a valve opening direction to be maintained in a chamber.

Abstract: The invention relates to a control circuit for a brushless type DC motor of the type having a permanent magnet rotor and a pair of poles provided with two windings, the windings having a common junction which is connectable to the positive terminal of a DC voltage source. A pair of controllable switching elements are in respective series with the windings. A symmetrical square wave pulse generator responsive to the angular position of the rotor switches the switching elements on and off in a push-pull mode. The control circuit processes the square wave output and has dual outputs for driving the switching elements with the dual outputs having alternate pulses in time spaced relation to each other for driving the switching elements in underlapping relation to each other to prevent the elements from drawing current from the common junction at the same time.

Abstract: The invention relates to a motor and compressor assembly of the type in which the frame member of the compressor unit includes the bearing for the motor shaft and is bolted to only one side of the packet of the stator laminations of the motor unit. The invention is directed to the prevention of misalignment between the compressor and motor units attributable to the bolting of the compressor unit to only one side of the packet of laminations which results in the bolt pressures or forces acting to clamp the laminations closer together on the bolt side than on the other side. The bad effects of this are avoided with the present invention by providing slots in the packet of laminations in close proximity to the bolt holes therein in a manner so that approximately symmetrical characteristic bending moment curves are obtained along lines passing through the axis of each bolt hole and to both sides of the holes.

Abstract: The invention relates to defroster control apparatus for the evaporator of a refrigerator. A frost sensor for measuring temperature is mounted a predetermined distance from a surface of the evaporator which corresponds to the permissible thickness of frost layer. Control apparatus including a comparator circuit initiates defrosting when the frost sensor temperature falls below a reference temperature. In this construction the frost layer grows in the direction of the frost sensor which is swept by the surrounding air. During each operating cycle the frost sensor initially measures a temperature approximating to the surrounding temperature. As the frost progressively increases, this temperature falls because the air circulation in the vicinity of the frost sensor is progressively more influenced as the thickness of the frost layer increases. In the extreme case, the frost sensor can come into contact with the frost layer.

Abstract: The invention relates to hydraulic steering apparatus of the type having valve gear for selectively directing pressurized fluid to and from opposite sides of a servomotor connected to vehicle wheels to be steered. This type of steering apparatus only requires pressurized fluid when actuated and may provide an auxiliary circuit with pressured fluid at times when it is not being actuated. Priority valves give priority to the steering apparatus. During extended intervals when pressured fluid is supplied to an auxiliary circuit, parts of the steering apparatus are subjected to substantial cooling. Then when the priority valve diverts hot pressurized fluid from the auxiliary circuit to the cooled steering apparatus the temperature differential causes an adverse effect on the steering apparatus by creating a tendency for binding of parts due to the unequal expansion of valve sleeves.

Abstract: The invention relates to a hydraulic motor assembly which includes a hydraulic servomotor operable in either direction with a control valve. When the motor is operated in a selected direction, as distinguished from the return direction, it is desired that external forces acting on linkage connected to the piston of the hydraulic motor do not alter the speed of the piston. The control valve has two operating positions and two sets of supply and return passages which facilitate operation of the servomotor in either direction. A brake valve between one of the servomotor ports and the control valve has a scanning port which scans or senses the downstream pressure of either of the control valve supply passages, depending on the control position of the control valve.

Abstract: The invention relates to an encapsulated refrigerator assembly of the type in which an integrated motor and compressor unit is resiliently mounted in a hermetically sealed casing or capsule. An oil sump at the bottom of the capsule is provided for lubricating oil. An externally disposed centrifugal separator with an oil collecting tank at the bottom thereof provides refrigerant in vapor form for the compressor and oil for the oil sump. The compressor has an inlet for receiving refrigerant vapor from the separator and the capsule has a single port connected to the separator. A connecting pipe inside the capsule provides fluid communication between the capsule port and the inlet of the compressor. Universal joint fittings at opposite ends of the connecting pipe allow for relative movement between the resiliently mounted motor compressor unit in the capsule and the relatively stationary capsule walls.

Abstract: The invention relates to a fluid pressure operated motor or pump of the type having a gerotor displacement mechanism which normally includes inner and outer wheel and ring gears which in operation have relative rotational and orbital movement therebetween. Such devices inherently have a form of valving wherein, with a commutating type of action, fluid is directed from the casing inlet to expanding chambers of the gerotor and directed from collapsing gerotor chambers to the casing outlet. In the unit herein the commutator valving includes two valve plates attached to opposite sides of the orbiting and rotating wheel gear which have the commutating action with the surrounding stationary ring gear.

Abstract: The invention relates to a thermostat unit adapted to be attached to a radiator valve of the type having a rotatable adjusting spindle and a surrounding ring shaped housing portion. The thermostat has a rotary knob unit with a body portion and a smaller diameter neck portion which connects to the valve spindle. The thermostat has a base unit with a supporting ring portion which surrounds said rotary knob body portion and a tightening ring portion which is attachable to the valve housing. The base unit supporting ring portion provides lateral or transverse support for the knob unit body portion to prevent breaking thereof when the knob unit body portion is subjected to large transverse forces resulting from accidental blows to which the knob unit body portion may be subjected.

Abstract: 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.

Abstract: The invention relates to a hydraulic planetary piston type machine and particularly to the rotary slide valve thereof. This type of machine has a rotary piston gear having rotational and orbital movement and a cardan type shaft connects the slide valve to the piston gear. The valve has inlet and outlet, annularly shaped, axially spaced distributor grooves in axially spaced relation. Alternately arranged inlet and outlet stub grooves extend axially from the distributor grooves into axially overlapping relation. The stub grooves in the valve have a commuting action with circumferentially arranged ports in the casing to provide for feeding and exhausting pressurized fluid to and from expanding and contracting chambers formed by the piston gear. In smaller machines the correspondingly smaller flow passages present sufficient flow resistance to substantially affect the efficiency of the machine.

Abstract: 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.

Abstract: The invention relates to an electrohydraulic control assembly of the type having a slide valve unit for controlling the operating direction of a hydraulic servomotor. The assembly includes a bridge circuit between the pressure source and the drain tank which has a pressure operated valve in each of its four branches. Diagonally opposite bridge terminals between the supply and exhaust branches of the bridge circuit are connected operating chambers on opposite sides of the slide valve unit. The bridge circuit valves are operated by solenoid valves to achieve selective directional operation of the slide valve unit.

Abstract: The invention relates to a gerotor type of rotary piston machine. In this type of device an externally toothed rotor member is eccentrically offset relative to an internally toothed stator member and in operation these members mesh to form expanding and contracting cells on opposite sides of the line of eccentricity. There is a shaft means for driving the rotor and a distributing valve for feeding and exhausting the cells. The distributing valve, which is normally connected to the drive shaft, is connected to the rotor member for movement therewith adjacent to the rotor and stator member. An annular chamber is formed between the periphery of the distributing valve and the interior of the casing. One set of the distributing ports is formed as ports within the confines of the periphery of the valve. The other set of distributing ports are formed by the periphery of the valve.