GB760111A - Improvements in or relating to mass flow control systems - Google Patents

Abstract

760,111. Automatic air-flow control systems. NORMALAIR, Ltd. May 6, 1954 [May 6, 1953], No. 12581/53. Class 38 (4). In a system for maintaining constant mass air-flow through a duct to the pressurized cabin of an aircraft in which the pressure difference in a venturi-type head measuring airflow in the duct controls electrical contacts energizing an electrically operated flow valve in the duct, the venturi is automatically throttled in response to pressure in the duct. In Fig. 1, air supplied to conduits 10 from port and starboard aircraft engines, respectively, passes through refrigerators s and non-return valves t to a common conduit 13 leading to the aircraft cabin. In each conduit 10 a venturi tube 1 measuring air-flow is arranged to maintain constant mass air-flow by electrically controlling a valve 2. In order to increase airflow automatically whenever a refrigerator s is put into operation, the increase in back pressure resulting from putting the refrigerator into operation influences a piston 3 through a conduit 14 to move a spring-loaded rod 4 into the throat of venturi tube 1. In the event of failure of one of the aircraft engines, the resulting drop of pressure in the corresponding conduit 10 allows an associated spring-loaded piston 6 to be moved so that the pressure in the other conduit 10 is effective through an associated non-return valve 9 and conduit 8 to influence pistons 16 moving rod 4 into the venturi throat so as to increase air flow from the engine still functioning. Specifications 655,328 and 656,763 are referred to.