Electronic torque wrench

Claim 2

Apparatus for measuring torque applied to a structure comprising: torque applying means: a piezoelectric element for generating from within the piezoelectric element an electrical signal in response to application of a torque force; means for amplifying the signal generated by the piezoelectric element; a selectively operable internal calibrating standard cell operatively connected to the piezoelectric element and to the amplifying means; means for integrating the amplified signal over a predetermined time interval, the integrating means including timing and counting means; further means for collecting the integration result, the collecting means operatively connected to a memory unit; and a readout display associated with the memory unit for displaying the integration result, the readout display selectively adjustable to present measured torque values in one of a plurality of physical measuring units.

Claim 3

Apparatus for measuring strain deformation in a structure including, in combination: means for applying a torque to a structure; a signal amplifier operatively connected to the torque applying means; an integrator operatively connected to the signal amplifier for integrating the amplifier output over a predetermined time interval; memory means for collecting the resultant output of the integrator operatively connected to a readout for displaying the integrator output numerically; the improvement comprising: a piezoelectric element responsive to the torque applied through the torque applying means for generating a signal representing said applied torque, the signal thus generated being amplified by said amplifier; a selectively operable internal standard calibrating cell connected to the piezoelectric element and the amplifier; and a readout display unit selectively adjustable to present measured strain in one of a plurality of physical measuring units.

Claim 4

Apparatus for measuring strain deformation in a structure including, in combination: means for applying a torque to a structure; a signal amplifier operatively connected to the torque applying means; an integrator operatively connected to the signal amplifier for integrating the amplifier output over a predetermined time interval; memory means for collecting the resultant output of the integrator operatively connected to a readout for displaying the integrator output numerically; the improvement comprising: a piezoelectric element responsive to the torque applied through the torque applying means for generating a signal representing said applied torque, the signal thus generated being amplified by said amplifier; a selectively operable internal standard calibrating cell connected to the piezoelectric element and the amplifier; and a readout display unit selectively adjustable to present measured strain in one of a plurality of physical measuring units.

Claim 5

An electronic torque wrench comprising: means for simultaneously applying a mechanical strain to a structure and to a piezoelectric element so that the piezoelectric element generates a signal from within said element in response to said strain application; a first amplifier for amplifying the signal generated by the piezoelectric element; voltage limiting means interposed between the piezoelectric element and the first amplifier for limiting piezoelectric voltage output to said amplifier; an internal, selectively operable, calibrating standard cell operatively connected to the piezoelectric element and to the first amplifier; a second amplifier connected to the first amplifier for further amplifying the signal from the piezoelectric element, the second amplifier including a resistive summing junction; means including a capacitor associated with a resistor and an amplifier for integrating the output signal from the second amplifier over a predetermined time interval, the time interval controlled by a timer associated with an oscillator; a plurality of transistors controlled by a flip-flop switch for controlling admission of the output signal from the second amplifier to the integrating means, the plurality of transistors including means for automatically switching to a standard reference voltage during the predetermined time interval when the integrating means is operating; memory means for receiving and storing the output of the integrating means; and a visual readout unit associated with the memory means for displaying a representation of the applied strain, the readout selectively adjustable to represent the applied strain values in one of a plurality of physical measuring units.

Claim 6

An electronic torque wrench comprising: means for simultaneously applying a mechanical strain to a structure and to a piezoelectric element so that the piezoelectric element generates a signal from within said element in response to said strain application; a first amplifier for amplifying the signal generated by the piezoelectric element; voltage limiting means interposed between the piezoelectric element and the first amplifier for limiting piezoelectric voltage output to said amplifier; an internal, selectively operable, calibrating standard cell operatively connected to the piezoelectric element and to the first amplifier; a second amplifier connected to the first amplifier for further amplifying the signal from the piezoelectric element, the second amplifier including a resistive summing junction; means including a capacitor associated with a resistor and an amplifier for integrating the output signal from the second amplifier over a predetermined time interval, the time interval controlled by a timer associated with an oscillator; a plurality of transistors controlled by a flip-flop switch for controlling admission of the output signal from the second amplifier to the integrating means, the plurality of transistors including means for automatically switching to a standard reference voltage during the predetermined time interval when the integrating means is operating; memory means for receiving and storing the output of the integrating means; and a visual readout unit associated with the memory means for displaying a representation of the applied strain, the readout selectively adjustable to represent the applied strain values in one of a plurality of physical measuring units.