Abstract: A pressure compensated safety control is employed to shut off the compressor at high compression ratios, caused, for example, by reduced air flow over the condenser or other reasons. This is especially useful on both reverse cycle heat pumps and conventional, non-reversible refrigeration and air conditioning systems to protect the compressor. In a preferred embodiment, the compensation is provided by making the control responsive to compressor suction pressure.

Abstract: A loss of refrigerant and/or high discharge temperature detection and control system for a reverse cycle refrigeration system by providing a fault indication whenever the temperature of the compressor discharge refrigerant is at or above a predetermined value (which value is a function of the magnitude of the outdoor air temperature) and which functions further by inhibiting the operation of the compressor of the reverse cycle refrigeration system whenever the temperature of the refrigerant at the compressor discharge exceeds a predetermined value above which the compressor would be damaged if it continued to operate.

Abstract: Frost control apparatus is disclosed for a temperature conditioning system such as a heat pump or the like, wherein a compressor circulates a volatile fluid through the closed system. Frost-buildup on the indoor and outdoor coils of the system is controlled by means of respective defrost cycles which occur in accordance with the conditions sensed by temperature sensing elements positioned at various points in the system. The defrost cycle for the indoor coil is maintained throughout a predetermined temperature range of ambient indoor air. The defrost cycle for the outdoor coil is initiated as a function of the differential between the temperature of the outdoor coil and that of ambient outdoor air and it varies in magnitude as a function of ambient outdoor air temperature. The termination of the outdoor coil defrost cycle is determined by a sensed temperature condition.

Abstract: An improper or wrong operational mode fault detection and control system for a reverse cycle refrigeration system for detecting faulty operation, i.e., operation in the cooling mode when heating is desired or in the heating mode when cooling is requested, and for controlling the system in response to the detection of a fault by inhibiting the compressor and for providing a fault indication, the control system comprising a controller means receiving inputs indicative of the outdoor air temperature, the temperature of the outdoor heat exchanger coil refrigerant, and an output indicative of a demand from a building temperature sensing means for heating or cooling of the building. The controller means also includes timing means and means for comparing the value of the outdoor heat exchanger coil refrigerant temperature and the value of the outdoor air temperature.

Abstract: A control system for a reverse cycle refrigeration system for controlling the defrosting of the outdoor coil thereof on a cost effective basis; the control system comprising a controller means receiving inputs indicative of the outdoor air temperature, the temperature of the outdoor coil, and the operation of the compressor means; the controller means having a timing function which is initiated upon the outdoor coil temperature being at or below a preselected value and the compressor means being operated; the duration of the timing function being determined on a substantially continuous basis as a function of the magnitude of the outdoor air temperature; and the controller means having an operative connection to the system so as to, upon completion of the timing function, place the reverse cycle refrigeration system into an outdoor coil defrost mode of operation.

Abstract: Surge in a compressor-driven system, such as a refrigeration system, is precluded by sensing an appropriate parameter, for example the gas flow at the compressor discharge outlet, and developing therefrom a feedback signal which dynamically varies the capacity of the compressor so that the discharge pressure versus discharge flow rate characteristic curve of the compressor always has a negative slope at the operating point, regardless of where that point is located on the curve. By providing a negative slope at all operating conditions, the system is incapable of surge. In order to satisfy variable load requirements, the compressor capacity is adjusted to vary the steady state operating point on the characteristic curve.

Abstract: An absorption refrigeration system is adapted to be powered by solar energy or a source of relatively low temperature waste heat. A control system automatically adjusts the maximum energizing temperature as the temperature of the cooling water, used to cool the condenser and absorber coils, varies.

Abstract: A controlled space is maintained at a desired set point temperature by adjusting the evaporator boiling pressure in a refrigeration system, thereby controlling the evaporator capacity (namely, the amount of cooling imparted to the air supplied to the space) which is inversely proportional to the evaporator boiling pressure. When the space temperature tends to vary from the desired set point due, for example, to a changing heat load, the control system automatically changes the refrigerant flow through the evaporator to establish the evaporator boiling pressure (and hence the boiling temperature) at the control point required to cool the air sufficiently to maintain the controlled space at the desired temperature. More specifically, in response to a space temperature increase, the flow rate of the refrigerant increases to decrease the evaporator boiling pressure; and in response to a drop below the set point, the refrigerant flow decreases to increase the evaporator boiling pressure.

Abstract: A controlled space is maintained at a desired set point temperature by adjusting the refrigerant temperature at the evaporator outlet in a refrigeration system, thereby controlling the evaporator effectiveness or capacity which is inversely proportional to the outlet temperature. When the space temperature tends to vary from the desired set point due to a changing heat load, the control system automatically changes the refrigerant flow through the evaporator to establish the evaporator outlet temperature at the control point required to maintain the controlled space at the desired temperature. More specifically, in response to a space temperature increase, the flow rate of the refrigerant increases; and in response to a drop below the set point, the refrigerant flow decreases. Such control of the flow rate is achieved by varying the displacement of a controlled displacement compressor included in the refrigeration system.

Abstract: A heating system for a motor vehicle has temperature sensors for gauging the compartment temperature as well as for gauging the temperature of the effluent hot air. These sensors are connected in series, with the compartment sensor generating the more significant control signal. The flow of heating medium, for example engine water, is regulated by a valve under the control of a regulator which compares the sensors signals with a set-point value. The valve may be cyclically actuated by pulses of fixed frequency but having a width which depends on the results of the signal comparison.

Abstract: A control system for an air conditioner having detectors for detecting at least the radiation temperature in a room or controlled space, a device for setting a desired room air parameter in response to the detected radiation temperature, and a controller for controlling the air conditioner in accordance with the desired room air parameter.

Abstract: A switching device responsive to pressure at two inputs with pressure responsive members each of which moves an actuating member in response to pressure variations. First and second electrical switches are positioned to be operated by the respective actuating members and a third switch is mounted for movement with one of the members and actuated by the other member. Springs apply appropriate forces to the member and are adjustable as to applied force.

Abstract: An automatic electronic ice-making control system for automatic ice-making machines including an ice-making chamber in which is arranged a semiconductor temperature sensitive element which may comprise a thermistor, which translates temperature changes into resistance changes and for terminating an ice-making cycle a differential amplifier is provided in which said thermistor is connected as a temperature sensitive element, a variable resistance element sensitive to ambient changes being provided in said differential amplifier in series connection with said thermistor across a voltage source, the variable resistance element compensating the characteristics of the thermistor in accordance with atmospheric ambient temperature changes to actuate with an output signal derived from the differential amplifier a Schmidt circuit and relays in accordance with temperature conditions prevailing in the ice-making chamber and compensated for ambient temperature changes, thereby to terminate the ice-making operation upon p

Abstract: A refrigerator has a low-temperature cooling compartment and a higher-temperature cooling compartment, and is provided with a cooling system comprised of a cooling-medium flow circuit. The flow circuit includes a compressor, a condenser downstream of the compressor, a flow restrictor downstream of the condenser, a first evaporator section downstream of the flow restrictor and operative for cooling the lower-temperature compartment, and a second evaporator section downstream of the first evaporator section and operative for cooling the higher-temperature compartment. An accumulator communicates with the flow circuit upstream of the flow restrictor. A heater is provided for heating liquid cooling medium in the accumulator to cause evaporation of part of such liquid cooling medium and concomitant pushing of the liquid remainder of the liquid cooling medium in the accumulator out of the accumulator and into the second evaporator section.