ApplicationNo. 186003 filed on 01/24/1994
US Classes:73/724, Capacitive73/718Capacitive
ExaminersPrimary: Chilcot, Richard
Assistant: Biegel, R.
Attorney, Agent or Firm
Foreign Patent References
International ClassH01G 001/00
AbstractA variable capacitance type pressure sensor with excellent manufacturability center-mounts an electrode on an edge-mounted diaphragm using a metal-glass-metal subassembly. An inner metal post of the assembly is welded to the diaphragm. A solder or flowable cement secures the electrode to an outer metal collar of the assembly with the initial diaphragm-to-electrode spacing set by a temporary shim. The position of the glass and the physical lengths of the metallic members of the assembly are adjusted to provide self-compensation for temperature variations. In a preferred form for low and medium pressure applications, the diaphragm is stamped from sheet metal with a central dimple that resists rotation of the attached assembly and isolates diaphragm deformation stresses from the post-to-diaphragm weld. In a high pressure form, a machined central boss isolates this weld from stress. A fitting that edge-mounts the diaphragm has a thinned end wall, or the diaphragm has a thin-walled skirt, to relieve stress on the diaphragm-to-fitting joint.