Environmental fluidic switching device with plural diaphragms

Claim 1

A fluidic switching device operable in response to dynamic and environmental air pressure differences, comprising: a. a housing; b. a pressure chamber within said housing; c. pressure sensing means mounted within said pressure chamber; d. said pressure chamber being divided into two separate compartments by said pressure sensing means; each of said two pressure chamber compartments, respectively, having only a single fluid flow part thereto; e. a ram air inlet to said housing; f. a first passageway in said housing from said ram air inlet directly to the fluid flow port of the first of said two pressure chamber compartments, where dynamic ram air pressure is sensed; g. a second passageway in said housing from said ram air inlet to the fluid flow port of the second of said two pressure chamber compartments; h. a third passageway in said housing from the fluid flow port of the second of said two pressure chamber compartments to the ambient atmosphere; i. a separately adjustable pressure setting restrictor in each of said second and third passageways, respectively, said second and third passageways and restrictors forming a pneumatic resistance circuit, the pressure in the second of said two separate compartments being adjusted to provide a differential in pressure between the two compartments when there is ram air pressure at the ram air inlet; said device being selfcompensating for altitude ambient air density variation; j. said pressure sensing means sensing the presSure differential between said two compartments and operable to actuate an electrical circuit connected thereto at a selected desired differential in pressures; k. said pressure sensing means comprising first and second spaced apart, flexible diaphragms actuated by the differential in pressure in said two compartments, the spaced apart diaphragms containing electrical contacts to said electrical circuit and forming a pressure actuated switch means; l. said first and second flexible diaphragms being normally separated at no pressure differential wherein the switch is thus normally open at no pressure differential, and said first and second diaphragms making electrical contact and thus closing the switch for pressures greater than a specified magnitude, the pressures required to close the switch being predetermined by the setting of said pressure setting restrictors; m. the pressure in each of said pressure chamber compartments being sensed by said first and second pressure sensing diaphragms, the ram air pressure being sensed in the first of said pressure chamber compartments directly on said first diaphragm via said first passageway and partially in said second compartment on said second diaphragm via said second passageway, said second compartment being the low pressure side of said pressure chamber, and the pneumatic pressure on said second diaphragm being a resultant value of the pressures and air flow through the pressure setting restrictors in said second and third passageways, a closed electrical circuit being attained when the pneumatic pressures on said first and second diaphragms cause the two diaphragms to contact each other, the device actuating at low altitude and low ram air pressures when the restrictive value of the restrictor in said second passageway is increased relative to the value of the restrictor in said third passageway, and the device being actuated at high altitude and high ram air pressures when the restrictive value of the restrictor in said second passageway is decreased relative to the value of the restrictor in said third passageway.