Refrigerant control

Claim 1

A refrigerant control system in combination with an air conditioner having a compressor with a high pressure output and a suction input, a condensor, and an evaporator, the control system being operable to reduce the capacity of the evaporator in response to a heavy load on the system, thereby to reduce the load on the compressor, the improvement comprising: (a) said evaporator including: a first evaporator coil circuit, and a second evaporator coil circuit, said first circuit and said second circuit being independent of each other; and (b) said control system including: a distributor receiving liquid refrigerant from said condensor, a first feed conduit having only one fluid control first means associated therewith which first control means consists of a first expansion device for the liquid refrigerant, operably connecting said first circuit to said distributor, said first expansion device being operable to impart to said first conduit a direct pressure-fluid flow characteristic whereby an increase in the pressure differential across said first conduit will normally result in an increase in fluid flow through said first conduit, a second feed conduit operably connecting said second circuit to said distributor and having only one fluid flow control second means associated therewith which second control means consists of a second expansion device for the liquid refrigerant, said second expansion device being operable to impart to said second conduit an inverse pressure-fluid flow characteristic which, over a predetermined operating range, will result in a decrease in or substantially complete throttling of, any fluid flow through said second circuit with an increase in the pressure differential across said second conduit, thereby to make the system responsive to a heavy load by reducing the capacity of the evaporator, while sustaining a flow of liquid refrigerant through said first circuit.