Turn-of-the-nut wrench shutoff system

Claim 2

A power wrench comprising: a casing containing a motor, a spindle adapted to drive a fastener and drive means interconnecting the motor to the spindle; a power supply system for supplying power to the motor and containing means adapted to be actuated to stop the flow of power to the motor; means for measuring the speed of said spindle during wrench operation and operative to provide a signal when the speed of the spindle is reduced to a predetermined speed; and means for measuring the amount or angle of rotation of said spindle and operative to begin measuring the spindle rotation in response to said signal and to actuate said means for stopping the motor power after said spindle is rotated through a predetermined angle following said signal.

Claim 3

A power wrench comprising: a casing containing a motor, a spindle and a drive mechanism for interconnecting the motor to the spindle; a valve operative in response to a high pressure signal to close and stop the supply of power to the motor; means for measuring the speed of the spindle and operative, in response to a selected slow speed, to create an intermediate pressure signal; and means operative in response to said intermediate pressure signal to begin measuring the angle of rotation of the spindle and to create a high pressure signal after a predetermined amount of rotation of said spindle for operating said valve and causing it to close.

Claim 4

A power wrench comprising: a casing containing a motor, a spindle and a drive mechanism for interconnecting the motor to the spindle; a valve operative in response to a high pressure signal to close and stop the supply of power to the motor; means for measuring the speed of the spindle and operative, in response to a selected slow speed, to create an intermediate pressure signal; and means operative in response to said intermediate pressure signal to begin measuring the angle of rotation of the spindle and to create a high pressure signal after a predetermined amount of rotation of said spindle for operating said valve and causing it to close.

Claim 5

The wrench of claim 2 wherein: said valve is a pressure-operated shutoff valve and includes a chamber adapted to contain pressure acting on said valve urging it to close.

Claim 6

The wrench of claim 3 including: means for continually pressurizing said chamber; primary exhaust means for said chamber and including chopper means rotated by said spindle and alternately opening and closing said primary exhaust means as said spindle rotates whereby the pressure in said chamber rises as the spindle speed is reduced; a moveable member subject to the pressure in said chamber and resiliently urged to one position when the wrench is at rest, said movable member being operative, in response to the rise of pressure in said chamber to a first predetermined pressure in response to the reduction in speed of said spindle, to move to a second position; a second member cooperating with said movable member when in said second position to provide secondary exhaust means for said chamber, and operative to measure the angle of rotation of said spindle and to close said secondary exhaust means in response to the rotation of said spindLe through a predetermined angle thereby causing the pressure in said chamber to rise to a magnitude sufficient to cause said shutoff valve to close.

Claim 7

The wrench of claim 4 wherein: said movable member is a piston slidably and nonrotatably engaged to said spindle and cooperating with said casing to form a second chamber connected to said first chamber, said piston being movable to said second position by pressure in said second chamber.

Claim 8

The wrench of claim 5 wherein: said chopper means includes teeth mounted on said piston and rotating across the outlet of a primary exhaust passage connected to said second chamber when said piston is in its first position; and said outlet of said primary exhaust passage being closed when said piston is in its second position.

Claim 9

The wrench of claim 6 wherein: said secondary exhaust means includes a secondary exhaust passage which is opened by said piston in its second position; and said second member is rotatably mounted in said casing and arranged to be engaged with said piston in its second position to rotate with said piston.

Claim 10

The wrench of claim 7 wherein: said second member is a ring located to rotate across the outlet of said secondary exhaust passage and interconnected to the casing by a spring which returns the second member to a starting position when disengaged from said piston.