OUTDOOR UNIT ANTI-FROST DEVICE OF HEAT PUMP SYSTEM FOR HEATING AND COOLING

摘要

PURPOSE: An outdoor unit anti-frost device of a heating and cooling heat pump system is provided to prevent frost from being attached to the surface of an outdoor unit and improve the heating efficiency of the system while minimizing user's inconvenience and a stoppage and a brake down of the system. CONSTITUTION: A heating and cooling heat pump system selectively executes heating and cooling by an indoor unit(12) by selectively supplying a refrigerant gas to the indoor unit or an outdoor unit(15) from a compressor(10) through a four-way valve(11) and by re-flowing the supplied refrigerant into the compressor passing through the outdoor unit or the indoor unit from adjacent expansion valves(13,13') connected parallel with one-way check valves(14,14'). In an outdoor unit anti-frost device of the heating and cooling heat pump system, first and second temperature sensors(21,22) are each installed to a suction side pipe and a discharge side pipe of the compressor. A bypass pipe(20) extended from the discharge pipe of the compressor branches off into a first supply pipe(20a) connected to an input side pipe of the expansion valve and a second supply pipe(20b) connected to an input side pipe of the outdoor unit. A one-way check valve(26) is installed to the bypass pipe. A solenoid valve(23) operated by the first temperature sensor, and a flow control valve(24) are installed to the first supply pipe. A solenoid valve operated by the second temperature sensor, and a needle valve(25) are installed to the second supply pipe.