US Patent 10465952 Vapor injection heat pump and control method

A vapor injection heat pump includes a coolant loop and a refrigerant loop. The refrigerant loop includes a compressor, a valve directing a refrigerant of the compressor to a first or second heat exchanger dependent upon a mode of operation, an expansion device receiving the refrigerant from at least one of the heat exchangers, a separator receiving an expanded liquid/vapor refrigerant mix from the expansion device and directing a vapor component to a first input port of the compressor and a liquid component to a second valve. The second valve directs the liquid component to the heat exchangers, dependent upon the mode, and an accumulator receives an output refrigerant of the heat exchangers dependent upon the mode and directs a vapor component to a second input port of the compressor. A control module controls a pump in the coolant loop and the first and second valves dependent upon the mode.