Patent ID: 7445663

Claim:
A method for controlling the energy efficiency of a pressure swing oxygen concentrator having a compressor which provides a flow of pressurized feed gas, a plurality of gas separation elements which pass a flow of oxygen while blocking the flow of nitrogen, said oxygen concentrator having an operating cycle in which at least one element separates nitrogen from pressurized feed gas from the compressor to produce oxygen rich gas and in which nitrogen is purged from at least one other gas separation element, and at least one valve for switching the elements between the gas separating mode and the purge mode, said method comprising the steps of: a) selecting a desired oxygen enriched gas flow rate from said oxygen concentrator; b) providing a rotary valve for switching the elements between the gas separating mode and the purge mode, said rotary valve having a feed gas inlet port, an exhaust port, a first port connected to an inlet side of a first one of the gas separation elements, a second port connected to the inlet side of a second one of the gas separation elements, and a motor controlled by a controller to sequentially move said rotary valve between a first position wherein said inlet port is connected to the first port and said exhaust port is connected to the second port, a second position wherein the inlet port is connected to the first and second ports, a third position wherein the inlet port is connected to the second port and said exhaust port is connected to the first port, and a fourth position wherein the inlet port is connected to the first and second ports; and c) controlling the cycle time for the gas separation elements at a rate inverse to the desired oxygen flow rate, whereby as the desired oxygen enriched gas flow rate is decreased below a maximum flow rate for the oxygen concentrator, the gas separation elements are cycled between a gas separation mode and a purge mode at an increased rate by controlling the motor to rotate the rotary valve at a controlled rate.