Transport refrigeration system having means for enhancing the capacity of a heating cycle

Claim 1

In a transport refrigeration system which holds a set point temperature via heating and cooling cycles, a refrigerant circuit which includes a compressor, condenser, receiver, evaporator, and accumulator, mode selector valve means having heating and cooling positions, and control means for providing a heat signal when the need for a heating cycle is detected, the improvement comprising: means responsive to said heat signal for connecting the receiver and accumulator in direct fluid flow communication, and time delay means responsive to said heat signal which operates said mode selector valve means from the cooling position to the heating position after a predetermined time delay, whereby a condenser flushing mode occurs prior to each heating cycle, which forces liquid refrigerant trapped in the condenser to flow to the accumulator via the receiver, to enhance the heating capacity of the system.

Claim 5

A method of improving the heating capacity of a transport refrigeration system which maintains a selected set point temperature in a served space by heating and cooling cycles, including a refrigerant circuit which includes a compressor, condenser, receiver, evaporator, and accumulator, and mode selector valve means operable to initiate a selected one of the heating and cooling cycles, the steps of: providing a heat signal when the need for a heat cycle is detected during a cooling cycle, connecting the receiver and accumulator in direct fluid flow communication when the heat signal is provided, initiating a predetermined timing period in response to the heat signal, maintaining the mode selector valve means in a cooling cycle position during the timing period, and operating the mode selector valve means to select the heating cycle at the expiration of the timing period, whereby continuing the cooling cycle for the time delay period while the receiver is connected to the accumulator forces liquid refrigerant in the condenser to be transferred to the accumulator for availability during the heating cycle.

Claim 6

A method of improving the heating capacity of a transport refrigeration system which maintains a selected set point temperature in a served space by heating and cooling cycles, including a refrigerant circuit which includes a compressor, condenser, receiver, evaporator, and accumulator, and mode selector valve means operable to initiate a selected one of the heating and cooling cycles, the steps of: providing a heat signal when the need for a heat cycle is detected during a cooling cycle, connecting the receiver and accumulator in direct fluid flow communication when the heat signal is provided, initiating a predetermined timing period in response to the heat signal, maintaining the mode selector valve means in a cooling cycle position during the timing period, and operating the mode selector valve means to select the heating cycle at the expiration of the timing period, whereby continuing the cooling cycle for the time delay period while the receiver is connected to the accumulator forces liquid refrigerant in the condenser to be transferred to the accumulator for availability during the heating cycle.

Claim 11

A method of improving the heating capacity of a transport refrigeration system which maintains a selected set point temperature in a served space by heating and cooling cycles, including a refrigerant circuit which includes a compressor, condenser, receiver, evaporator, and accumulator, and mode selector valve means operable to initiate a selected one of the heating and cooling cycles, the steps of: providing a heat signal when the need for a heat cycle is detected during a cooling cycle, providing an ambient temperature signal when the ambient temperature is below a predetermined value, connecting the receiver and accumulator in direct fluid flow communication when the heat signal is provided while the ambient temperature signal is being provided, initiating a predetermined timing period when the heat signal is provided while the ambient temperature signal is being provided, maintaining the mode selector valve means in a cooling cycle position during the timing period, and operating the mode selector valve means to select the heating cycle at the expiration of the timing period, whereby continuing the cooling cycle for the time delay period while the receiver is connected to the accumulator forces liquid refrigerant in the condenser to be transferred to the accumulator for availability during the heating cycle.

Claim 12

A method of improving the heating capacity of a transport refrigeration system which maintains a selected set point temperature in a served space by heating and cooling cycles, including a refrigerant circuit which includes a compressor, condenser, receiver, evaporator, and accumulator, and mode selector valve means operable to initiate a selected one of the heating and cooling cycles, the steps of: providing a heat signal when the need for a heat cycle is detected during a cooling cycle, providing an ambient temperature signal when the ambient temperature is below a predetermined value, connecting the receiver and accumulator in direct fluid flow communication when the heat signal is provided while the ambient temperature signal is being provided, initiating a predetermined timing period when the heat signal is provided while the ambient temperature signal is being provided, maintaining the mode selector valve means in a cooling cycle position during the timing period, and operating the mode selector valve means to select the heating cycle at the expiration of the timing period, whereby continuing the cooling cycle for the time delay period while the receiver is connected to the accumulator forces liquid refrigerant in the condenser to be transferred to the accumulator for availability during the heating cycle.