Combustion chamber pressure transducer and method of making same
First Claim
1. A method of sensing combustion pressure in a port in the combustion chamber of an internal combustion engine comprising:
- (a) forming a beam of refractory piezoresistive material and supporting said beam at its ends for bending;
(b) supporting a pressure responsive diaphragm in said port with one side thereof exposed to the combustion;
(c) disposing said beam adjacent the side of said diaphragm opposite said combustion with a portion of said diaphragm contacting said beam and applying to said beam a force indicative of the combustion pressure forces acting on said diaphragm; and
,(d) deflecting said beam with said force and generating an electrical signal representative of said beam deflection.
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Accused Products
Abstract
A transducer housing for mounting a port in a combustion chamber has a metal diaphragm exposed to the combustion gasses. The pressure of the combustion gasses deflects the diaphragm which locally deflects a simply supported beam. The beam is formed of refractory material having epitaxially grown crystalline piezoresistors formed on one surface of the beam and connected in a bridge circuit. Noble metal foil leads connect to the piezoresistors to form the bridge and provide attachment pads. The pads are noble metal welded to other noble metal foil pads provided on a ceramic substrate to form a sensor subassembly for mounting adjacent the diaphragm to form a transducer.
27 Citations
17 Claims
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1. A method of sensing combustion pressure in a port in the combustion chamber of an internal combustion engine comprising:
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(a) forming a beam of refractory piezoresistive material and supporting said beam at its ends for bending; (b) supporting a pressure responsive diaphragm in said port with one side thereof exposed to the combustion; (c) disposing said beam adjacent the side of said diaphragm opposite said combustion with a portion of said diaphragm contacting said beam and applying to said beam a force indicative of the combustion pressure forces acting on said diaphragm; and
,(d) deflecting said beam with said force and generating an electrical signal representative of said beam deflection. - View Dependent Claims (2, 3, 4)
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5. A combustion chamber transducer comprising:
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(a) body structure adapted for mounting in a sensing port in a combustion chamber and defining a cavity therein; (b) a resilient pressure responsive diaphragm closing said cavity and formed of material capable of withstanding the temperatures and pressures of said combustion chamber; (c) a beam of piezoresistive material supported in said body structure cavity with a certain portion of said diaphragm contacting said beam; and
,(d) responsive to combustion pressure movement of said diaphragm, said certain portion is operative for effecting bending of said beam and thereby generating an electrical signal indicative of said bending. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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14. A combustion chamber pressure transducer comprising:
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(a) housing means adapted for installation in a combination chamber port; (b) a substrate formed of nonconductive refractory material and mounted on said housing means; (c) an elongated beam formed of crystalline refractory material and having a plurality of piezoresistors formed by epitaxial crystalline growth on a surface of said beam; (d) a plurality of electrically conductive leads formed on said surface of said beam, said leads each attached to one of said piezoresistors; (e) weldment means attaching the opposite ends of said beam to said substrate; and
,(f) pressure responsive means mounted on said housing means and having a certain portion thereof contacting said beam and upon exposure of said diaphragm to said combustion pressure said certain portion is operable to effect deflection of said beam for causing said piezoresistors to generate a signal indicative of said deflection. - View Dependent Claims (15, 16, 17)
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Specification