The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 13, 1976
Filed:
Oct. 29, 1974
Kenneth P Hansen, Enfield, CT (US);
Dean H Crombie, Ellington, CT (US);
United Technologies Corporation, Hartford, CT (US);
Abstract
A fluid-operated apparatus receiving an input pressure signal exhibits a hysteresis or deadband effect by responding to an increasing pressure signal at a first level and a decreasing signal at a second and lower level. The apparatus includes a spool valve to which the input pressure signal is applied at one end of the spool. The opposite end of the spool having a given cross sectional area projects into a pressure chamber and contacts the poppet of a poppet valve held closed by a regulated pressure in opposition to forces produced by the spool. The seat of the poppet valve surrounds an opening into the pressure chamber so that the regulated pressure is admitted into the pressure chamber when the spool pushes the poppet open. The effective area of the valve seat is greater than the cross sectional area of the spool end engaging the poppet so that the force or input pressure signal required to move the spool and open the poppet valve is greater than that which permits the spool to return and close the poppet valve. A hysteresis or deadband effect determined by the different cross sectional areas is manifested by the spool movements and a hydraulic mechanism controlled by those movements.