Pressure responsive sensing device

Claim 1

An improved pressure sensitive transducer measurement device comprising, in combination: a housing, said housing defining a chamber open at one end having a tubular housing wall; a generally non-compressible fluid within the chamber; a constricted passage through the housing wall to the chamber for receipt of said fluid; an electronic transducer device attached to the housing in communication with the constricted passage and on the outside of the chamber; a cover plate over the open end of the housing and attached to enclose the chamber; a diaphragm member retained between the cover plate and the housing and defining a generally planar interior surface of the chamber at the open end; a plate member retained by the cover plate in opposed relation with the diaphragm member on the side of the diaphragm member opposite the interior of the chamber; said cover plate having a bearing passage defining a bearing surface; and a stem connected to the plate member and having an anvil attached to an end, said end generally frictionlessly projecting through the bearing passage in the cover plate for receipt of a force, said stem transmitting said force through the plate member against the diaphragm and to the noncompressible fluid within the chamber, so that the pressure in the fluid is equal to the force divided by the area of the interior surface of the diaphragm member, said pressure being transmitted through the constricted passage to the electronic transducer device, the diameter of the constricted passage and the ratio of the area of said plate member to the anvil so dimensioned to thereby avoid hysteresis in the output of said device, the ratio of the length of the bearing surface to the diameter of the stem being greater than 2.0 to 1.