United States Patent  [ii] Patent Number: 4,621,519
Phillips  Date of Patent: Nov. 11, 1986
Assistant Examiner—John E. Chapman, Jr.
Attorney, Agent, or Firm—Saul Elbaum; Thomas E.
McDonald; Anthony T. Lane
The invention involves the design of a piezoelectric pressure transducer used for measuring pressure-time characteristics in gun tubes during the propellent ignition and burning process. The transducer utilizes one or two Z-cut tourmaline crystals as the piezoelectric pressure sensing element which produces a finite amount of electrical charge for a given change in pressure. The tourmaline crystals are incapsulated in a mechanical fixture which provides means for mounting in the gun tube, electrical terminals for connecting to signal conditioning and recording instrumentation, and insulators for electrically insulating the transducer from the weapon ground. A needle valve is also incorporated in the transducer which provides means for replenishing the thermal protecting material around the crystal assembly without removing the transducer from the weapon.
8 Claims, 5 Drawing Figures