Patent ID: 6948380
Filing Date: 2005-09-27
Classification: B25B

Abstract:
1. A torque-indicating wrench comprising: a wrench body having a head which is adapted to engage and turn a workpiece about a rotational axis, and a stem which extends from said head in a longitudinal direction radial to the rotational axis, and which terminates at a coupled end, said stem being made from a material with a first modulus of elasticity, and having an inner peripheral wall to define a mounting slot, said inner peripheral wall including two longitudinal wall segments which are opposite to each other relative to a neutral line in the longitudinal direction, and front and rear transverse wall segments which are spaced apart from each other in the longitudinal direction, and which cooperate with the longitudinal wall segments to define said mounting slot, each of said longitudinal wall segments including front and rear regions which are proximate to said front and rear transverse wall segments, respectively, and a middle region which is interposed therebetween; a handle disposed to couple with said coupled end and operable to turn said head about the rotational axis; a strainable body made from a material with a second modulus of elasticity that is smaller than the first modulus of elasticity, and having an outer peripheral wall which is configured to be insertable into said mounting slot so as to place said strainable body in a position of use where said strainable body is subject to stretching in the longitudinal direction in response to turning movement of said handle about the rotational axis, said outer peripheral wall including a strain gage unit attached to at least one of said gage carrying regions and confronting said middle region of a corresponding one of said longitudinal wall segments to detect change in resistance values which is a function of extent of stretching deformation of said strainable body as a result of application of torque by said head when said head turns the workpiece about the rotational axis, and to translate the change in resistance values into an electrical signal; a processing circuit connected electrically to said strain gage unit, said processing circuit calculating a value of the torque applied to the workpiece in accordance with the electrical signal from said strain gage unit so as to generate an output signal; and a display unit connected electrically to said processing circuit for receiving the output signal from said processing circuit and translating the output signal into a visual presentation.