George E Coultas

US Patent:

40263215, May 31, 1977

Filed:

Dec 12, 1975

Appl. No.:

5/640043

Inventors:

H. Taylor Kahoe - Mentor OH
George E. Coultas - Euclid OH
Dana W. Skipworth - Cleveland OH

Assignee:

Kahoe Laboratories, Inc. - Eastlake OH

International Classification:

G05D 706

US Classification:

137487

Abstract:

A control system for use in central heating and air-conditioning installations to control the volumetric flow rate of conditioned air through a supply duct to an enclosed space to be serviced. The system is adapted to maintain a desired ambiant temperature in the enclosed space by regulating the circulation of conditioned air in accordance with the demand generated by prevailing conditions. An adjustable restrictor valve defining an orifice is located in the supply duct and sensors are provided to continuously measure the orifice diameter and the pressure drop across the orifice. Electronic circuitry is provided to generate a flow rate voltage signal representative of the product of the orifice diameter and the pressure drop across the orifice and to compare the flow rate voltage level with a fixed or temperature controlled reference voltage to obtain either an "increase" or "decrease" control voltage signal. An "increase" control signal is used to enlarge the orifice diameter and increase the volumetric flow rate while a "decrease" control signal is used to decrease the flow rate and reduce the orifice diameter.