Transducer device for monitoring pressure

Claim 1

A transducer for developing an electrical signal in response to pressure variations within the combustion chamber of an engine of the type having a) a threaded port extending from the combustion chamber to the outer surface of the engine and b) a glow or spark plug having a shank portion threaded into said port and an enlarged head portion exterior to said shank portion, said transducer comprising: a housing sized and shaped for insertion around said shank portion while underlying said enlarged head portion, said housing having a thickness sufficient to ensure that said glow or spark plug head portion compresses said housing against said engine and seats against said housing; a piezoelectric element disposed within said housing for developing an electrical signal in response to pressure variations on said glow or spark plug from within said combustion chamber; and terminal means for transmitting the electrical signal from said piezoelectric element.

Claim 9

A method for dynamically monitoring the performance of an internal combustion engine of the type having at least one spark or glow plug threaded into a receptacle which extends from the outside of the engine into a cylinder combustion chamber and which plug has an enlarged head portion exterior to said engine, said method comprising the steps of: at least partially unscrewing said plug from its receptacle so as to unseat said plug from the engine; inserting around said plug a pressure responsive transducer which is shaped to fit around said plug between said enlarged plug head portion and the outer face of said engine; screwing said plug back into its receptacle until the enlarged head portion compresses said transducer against the outer face of said engine so that axial pressures on said plug from within said cylinder create pressure variations on said transducer which generate a transducer output signal.

Claim 10

A method for dynamically monitoring the performance of an internal combustion engine of the type having at least one spark or glow plug threaded into a receptacle which extends from the outside of the engine into a cylinder combustion chamber and which plug has an enlarged head portion exterior to said engine, said method comprising the steps of: at least partially unscrewing said plug from its receptacle so as to unseat said plug from the engine; inserting around said plug a pressure responsive transducer which is shaped to fit around said plug between said enlarged plug head portion and the outer face of said engine; screwing said plug back into its receptacle until the enlarged head portion compresses said transducer against the outer face of said engine so that axial pressures on said plug from within said cylinder create pressure variations on said transducer which generate a transducer output signal.

Claim 19

A method for detecting force waves in solid metal objects comprising the steps of forming a cylindrical cavity in the metal such that the axis of the cavity is substantially perpendicular to the movement of the force wave to be detected, placing at the inner end of said cavity a flat piece of piezoelectricl material having a first face in electrical contact with the inner end of said cavity and the second and opppsite face facing outward from said cavity, inserting into said cavity from its outer end an element comprising an inner core of conductive material within an outer sleeve of insulating material which surrounds said conductive material except for the forward and rearward ends thereof, the forward end of said conductive material being uninsulated and adapted to be pressed against the outward facing portion of said piezoelectric element; positioning in said cavity a coaxial fitting of the type having a protruding central conductor shaft supported in spaced insulated relation to an outer cylindrical conductor, the central shaft of said coaxial fitting being adapted to conductively engage the rearward end of the conductive core upon positioning of said coaxial end fitting into said cavity, whereby said conductive core is compressed between the outward face of said piezoelectric element and said central conductor shaft of the coaxial fitting so as to provide an output terminal for the signal which develops in the piezoelectric material in response to the force waves.

Claim 20

A method for detecting force waves in solid metal objects comprising the steps of forming a cylindrical cavity in the metal such that the axis of the cavity is substantially perpendicular to the movement of the force wave to be detected, placing at the inner end of said cavity a flat piece of piezoelectricl material having a first face in electrical contact with the inner end of said cavity and the second and opppsite face facing outward from said cavity, inserting into said cavity from its outer end an element comprising an inner core of conductive material within an outer sleeve of insulating material which surrounds said conductive material except for the forward and rearward ends thereof, the forward end of said conductive material being uninsulated and adapted to be pressed against the outward facing portion of said piezoelectric element; positioning in said cavity a coaxial fitting of the type having a protruding central conductor shaft supported in spaced insulated relation to an outer cylindrical conductor, the central shaft of said coaxial fitting being adapted to conductively engage the rearward end of the conductive core upon positioning of said coaxial end fitting into said cavity, whereby said conductive core is compressed between the outward face of said piezoelectric element and said central conductor shaft of the coaxial fitting so as to provide an output terminal for the signal which develops in the piezoelectric material in response to the force waves.