Abstract: The invention relates to a refrigeration machine, particularly a heat pump, comprising a closed circuit, which contains a coolant and in which an evaporator, a compressor, a condenser and an, in particular, electrically operated expansion valve are arranged one after the other. The refrigeration machine also comprises an overheating control unit for at least intermittently regulating the temperature of the coolant in the area of the compressor, particularly the compression final temperature. The invention also relates to a method for operating a refrigeration machine of the aforementioned type.

Abstract: The present invention relates to a method for the determination of the coefficient of performance of a refrigeration machine, in particular of a heat pump, which includes a closed circuit which has a refrigerant and in which an evaporator, a compressor, a condenser and an expansion valve are arranged. In the method, at least three temperatures of the refrigerant are determined using temperature sensors arranged in the circuit. Alternatively, at least two temperatures and at least one pressure of the refrigerant is determined using sensors arranged in the circuit. Enthalpies of the circuit are calculated from the determined refrigerant temperatures and refrigerant pressures and the heat output and the taken up electrical power of the refrigeration machine are calculated therefrom to determine the coefficient of performance of the refrigeration machine from the quotient of the calculated heat output and the calculated taken up electrical power.

Abstract: The invention relates to a control unit for a refrigeration or air conditioning device, comprising a main processor that is situated in a housing and that controls the temperature, fan and/or the defrosting process of a refrigeration or air conditioning device. Contact points for a co-processor, which is separate from the main processor and is suitable for controlling an electronic expansion valve, are located in said housing.

Abstract: The invention relates to a control unit for controlling the expansion valve of a refrigeration or air conditioning system, comprising a temperature sensor that is connected upstream of the expansion valve in the coolant circuit. If the control unit detects a decrease in temperature of the aforementioned temperature sensor, which is generally caused by the start of a defrosting process, it displaces the expansion valve into a static state, to protect said valve during the defrosting process.

Abstract: The invention relates to a refrigeration machine, particularly a heat pump, comprising a closed circuit, which contains a coolant and in which an evaporator, a compressor, a condenser and an, in particular, electrically operated expansion valve are arranged one after the other. The refrigeration machine also comprises an overheating control unit for at least intermittently regulating the temperature of the coolant in the area of the compressor, particularly the compression final temperature. The invention also relates to a method for operating a refrigeration machine of the aforementioned type.