Heat pump adapted to environment temperature change

The utility model relates to a heat pump applicable to wide range of temperature, which comprises a compressor, a condenser communicated with an outlet of the compressor, a expansion valve fixed between an outlet of the condenser and an inlet of the evaporator, a filter connected with the outlet of the condenser with the inlet of the compressor. The utility model relates characterized in that the outlet and the inlet of the expansion valve is communicated with a bypass pipe.Part of the work substance is allowed to come into the evaporator directly through the bypass pipe, which can not only adjust the flux and the differential pressure of the work substance but also make up the lack that the expansion valve dose not match with the evaporator by the bypass pipe, thereby improving the thermal efficiency, enlarging the range of environmental temperature, improving energy efficiency ratio as well as working stability of the unit, prolonging the service life, thus facilitating the selection of the expansion valve.