POWER WRENCH WITH A TORQUE SENSING UNIT

• US 20140026723A1
• Filed: 05/03/2012
• Published: 01/30/2014
• Est. Priority Date: 05/04/2011
• Status: Active Grant

• Current Assignee: Atlas Copco Industrial Technique Ab (Atlas Copco AB)
• Original Assignee: Atlas Copco Industrial Technique Ab (Atlas Copco AB)
• Inventors: Persson, Erik Vilhelm, Brndstrm, Ulf Roland, Berglind, John, Hertsius, Martin
• Granted Patent: US 9,186,784 B2
• Time in Patent Office: Days
• US Class Current: 81/479
• CPC Class Codes: B25B 21/00 Portable power-driven screw or nut setting or loosening tools; details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; for mounting or dismounting wheels B60B29/006; Attachments for drilling apparatus serving the same purpose machines B23P19/06
• CPC Class Codes: B25B 23/14 Arrangement of torque limiters or torque indicators in wrenches or screwdrivers couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers

Abstract

A power wrench with a torque sensing unit includes a housing, a motor, an output shaft, and a planetary reduction gearing connecting the motor to the output shaft and including a stationary ring gear supported in the housing, wherein the torque sensing unit includes a torque transferring element with a single radially extending reaction arm arranged to transfer reaction torque from the ring gear to the housing and carrying strain measuring sensors for generating signals in response to the transferred reaction torque. The torque transferring element includes an annular body with two weak portions to be elastically deformed during torque transfer and having flat surfaces for carrying the strain measuring sensors.

Claims

1. A power wrench with a torque sensing unit, comprising a housing, a motor, an output shaft, and a planetary reduction gearing connecting the motor to the output shaft and including a stationary ring gear supported in the housing, wherein the torque sensing unit comprises a torque transferring element arranged to transfer reaction torque from the ring gear to the housing and carrying a strain measuring sensor arranged to generate electric signals in response to the magnitude of the transferred reaction torque, wherein:

the torque transferring element comprises an annular body with an outer diameter equal to the inner diameter of the ring gear and having at an outer periphery a number of teeth matching and engaging teeth of the ring gear to thereby rotationally lock the torque transferring element to the ring gear, and

said torque transferring element comprises a single reaction arm extending radially from the annular body and arranged to engage an abutment on the housing.

2. The power wrench according to claim 1, wherein said teeth are provided in a sector of the outer periphery of said annular body, said sector being located diametrically opposite said reaction arm.

3. The power wrench according to claim 2, wherein said sector extends over at least 180 degrees of the periphery of said annular body.

4. The power wrench according to claim 1, wherein said annular body comprises at least one weak portion with a flat surface for carrying the strain measuring means, and wherein said flat surface is located in a plane parallel to a geometric axis of the ring gear.

5. The power wrench according to claim 4, wherein said annular body comprises two weak portions located at opposite sides of said reaction arm.

6. The power wrench according to claim 2, wherein said annular body comprises at least one weak portion with a flat surface for carrying the strain measuring means, and wherein said flat surface is located in a plane parallel to a geometric axis of the ring gear.

7. The power wrench according to claim 6, wherein said annular body comprises two weak portions located at opposite sides of said reaction arm.

8. The power wrench according to claim 3, wherein said annular body comprises at least one weak portion with a flat surface for carrying the strain measuring means, and wherein said flat surface is located in a plane parallel to a geometric axis of the ring gear.

9. The power wrench according to claim 8, wherein said annular body comprises two weak portions located at opposite sides of said reaction arm.