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Title: Pneumatic pressure transmitter responsive to temperature and humidity
Claims: I claim: 1. A force-balance pneumatic pressure transmitter responsive to temperature and humidity comprising: a nozzle; an inlet for conducting a restricted supply of fluid under pressure to said nozzle; a flapper operatively associated with said nozzle to vary fluid flow through the nozzle; a first pivot displaced from said nozzle; a first elongated resilient simple beam supported at one end upon said first pivot and connected at the other end to said flapper; a first abutment associated with said first beam and located between said nozzle and said first pivot biasing said flapper toward said nozzle through said first beam; a second pivot displaced from said nozzle; a second elongated resilient simple beam supported at one end upon said second pivot and connected at its other end to said flapper; a second abutment associated with said second beam and located between said nozzle and said second pivot biasing said flapper toward said nozzle through said second beam; first means for applying a bending moment to one of said beams in response to sensed temperature; second means for applying a bending moment to the other of said beams in response to sensed humidity, said first and second means acting together to apply a variable control force through said first and second beams to said flapper to modulate said fluid pressure in response to the sensed temperature and humidity, said fluid pressure acting over the area of the nozzle to provide to the flapper a negative feedback force proportional to said fluid pressure. 2. A transmitter according to claim 1 wherein one of said pivots is movable substantially perpendicular to a respective one of said beams. 3. A transmitter according to claim 2 wherein said one pivot comprises a post movable longitudinally. 4. A transmitter according to claim 3 wherein said post comprises a threaded portion and the other of said pivots comprises a nut threaded upon said threaded portion. 5. A transmitter according to claim 4 wherein said nut comprises a sloping shoulder in engagement with the other of said beams. 6. A transmitter according to claim 3 wherein said post comprises a sloping shoulder in engagement with said one beam. 7. A transmitter according to claim 1 wherein one of said abutments is movable along the length of its associated beam to permit span adjustment of the control force due to the bending moment applied by one of said first and second means. 8. A transmitter according to claim 1 wherein said second beam is connected to said flapper through a connecting member associated with said first beam. 9. A transmitter according to claim 8 wherein said first and second beams are substantially parallel to the plane of said flapper, said connecting member extending between the ends of said beams proximate to said flapper. 10. A transmitter according to claim 9 wherein said connecting member is rigidly fixed to said first beam. 11. A transmitter according to claim 10 wherein said second beam is detachable from said connecting member. 12. A transmitter according to claim 11 wherein said connecting member extends substantially perpendicular from said first beam and comprises a cross-member displaced from said first beam, said second beam having a notched end adapted to operatively engage said cross-member. 13. A transmitter according to claim 1 wherein said flapper and said first beam are one. 14. A transmitter according to claim 1 wherein one of said beams comprises a laminated composite material, the bending moment resulting from differential expansion and contraction of the laminations in response to change in one of the sensed temperature and the sensed humidity. 15. A transmitter according to claim 14 wherein said laminated composite material comprises a temperature responsive bimetal member. 16. A transmitter according to claim 1 wherein one of said first and second means comprises a pair of brackets displaced from each other and fixed substantially perpendicular to a respective beam, an element mounted between the free ends of said brackets, the bending moment resulting from expansion and contraction of said element in response to change in one of the sensed temperature and the sensed humidity. 17. A transmitter according to claim 1 additionally comprising means to shield one of said first and second means from fluid flowing from said nozzle. 18. A transmitter according to claim 16 additionally comprising a housing associated with said nozzle and said one means, said housing having a rib separating said element from said nozzle so as to inhibit the circulation of fluid from said nozzle around said element. 19. A transmitter according to claim 8 wherein said brackets extend from said respective beam through respective holes in said rib to said element, said transmitter additionally comprising a disc to cover one of said holes, said disc provided with an opening to permit a respective one of said brackets to extend therethrough. Other info: Inventors: Stark, Ernest H. (Rockford, IL, US) Application Number: 790372 Filing Date: 1977-04-25 Publication_date: 1978-05-30 Assignee: Barber-Colman Company (Rockford, IL) Primary Class(es): 236/44C 73/335.02, 200/61.06, 236/87 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Wayner, William E. Assistant Examiner: Attorney: Hammes, Jr.; Robert M. |
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