TORQUE WRENCH

• US 20100206141A1
• Filed: 05/28/2008
• Published: 08/19/2010
• Est. Priority Date: 06/13/2007
• Status: Active Grant

• Current Assignee: Hosiden Corporation, Kyoto Tool Co., Ltd.
• Original Assignee: Hosiden Corporation, Kyoto Tool Co., Ltd.
• Inventors: Fujita, Kouji, Uchida, Hiroshi, Hanai, Tadashi, Nakata, Shogo, Umekawa, Masahiko
• Granted Patent: US 8,234,936 B2
• Time in Patent Office: Days
• US Class Current: 81/479
• CPC Class Codes: B25B 23/1425 by electrical means

Abstract

[Problem to be Solved] The invention aims at ease of operation compatible with improved accuracy of measurement.

[Constitution] The invention includes a tightening portion 10 such as a ratchet wrench, a housing 20 having a front side cover part 21 and a back side grip part 22, a shaft-like strain body 30 that is contained inside the housing 20 and has a leading end coupled with the replaceable tightening portion 10, first distortion sensors 42a and 42b and second distortion sensors 43a and 43b that are arranged at spaced points in the axial direction of the strain body 30 for measuring a tightening torque T, a setting portion 70 for setting a tightening torque set value etc., a microprocessor chip 100 having functions including computation of the tightening torque T while correcting errors due to changes in point of effort based on the detection result of the first distortion sensors 42a and 42b and the second distortion sensors 43a and 43b, and an output portion 300 for outputting the tightening torque T etc.

Claims

1. A torque wrench comprising:

a shaft-like strain body having a leading end coupled with a replaceable tightening portion;

a housing for containing the strain body;

first and second distortion sensors for measuring a tightening torque, the first and second distortion sensors being arranged at spaced points in an axial direction of the strain body;

a torque computation section for performing a computation of the tightening torque while correcting an error due to a change in a point of effort, at least based on measurement results of the first and second distortion sensors; and

an output portion for outputting at least a result of the computation performed in the torque computation section as a tightening torque measurement value.

2. The torque wrench according to claim 1, wherein

the housing is of a separable two-piece structure comprising:

a front side cover part in a tubular shape adapted to receive the leading end of the strain body, a leading endface of the front side cover part being provided with a hole for receiving a proximal end of the tightening portion; and

a back side grip part in a tubular shape adapted to receive a proximal end of the strain body, the back side grip part being provided therein with a shaft extending in a direction orthogonal to tightening force,

the shaft passes through side faces of the strain body, and

a rear end of the strain body is fixed to the back side grip part.

3. The torque wrench according to claim 1, further comprising:

a setting portion for setting a tightening torque set value; and

a torque determination section for making a determination whether or not the torque measurement value indicated by the result of the computation by the torque computation section is close to or has attained the tightening torque set value that is set via the setting portion, the torque determination section being adapted to order the output portion to output a result of the determination.

4. The torque wrench according to claim 1, wherein

a sensor unit is attached to a surface of the strain body, the sensor unit being configured such that the first and second distortion sensors are formed on a flexible circuit board.

5. The torque wrench according to claim 4, wherein

the surface of the strain body is formed with a recess having a length dimension corresponding to the sensor unit, and the sensor unit is affixed to the recess.