Power tool with output torque compensation and method therefor

• US 10,639,771 B2
• Filed: 03/30/2016
• Issued: 05/05/2020
• Est. Priority Date: 04/02/2015
• Status: Active Grant

• Current Assignee: Atlas Copco Industrial Technique Ab (Atlas Copco AB)
• Original Assignee: Atlas Copco Industrial Technique Ab (Atlas Copco AB)
• Inventors: Forsberg, Per Ingemar, Sundberg, Klas Erik
• Primary Examiner(s): Stinson, Chelsea E
• Assistant Examiner(s): Song, Himchan "Aiden"
• Application Number:
  US15/563,886
• Publication Number:
  US 20180117746A1
• Time in Patent Office: 1,497 Days
• Field of Search: 173 2, 173170, 173176, 173183, 173 5, 173 6, 81479
• 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 23/147 specially adapted for electrically operated wrenches or screwdrivers
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: B25F 5/001 Gearings, speed selectors, clutches or the like specially adapted for rotary tools

Abstract

A torque delivering power tool includes a power line driven by a motor. The power line includes an input part with an input shaft, an output part with an output shaft, and at least one gear. The input shaft is drivingly connected to the output shaft via the gear. A motor shaft is drivingly connected to the input shaft via a reduction gearing. A torque meter monitors a torque acting in at least one point along the power line, an angle meter monitors an angular rotation in the power line, and an index meter monitors absolute angular positions of the input shaft or the output shaft. A control unit receives information from the angle meter, torque meter and index meter, and controls a torque output of the motor according to a mapping function corresponding to an angular index position dependent torque transmission over the power line.

Claims

1. A torque delivering power tool comprising:

a power line driven by a motor, the power line comprising an input part with an input shaft, an output part with an output shaft, and at least one gear, such that the input shaft is drivingly connected to the output shaft via the at least one gear, and wherein a motor shaft is drivingly connected to the input shaft via a reduction gearing;

a torque meter which monitors a torque acting in at least one point along the power line, the torque meter being arranged along the input part of the power line;

an angle meter which monitors an angular rotation in the power line;

an index meter which monitors an absolute angular position (α

) of the input shaft or an absolute angular position (β

) of the output shaft; and

a control unit which receives information from the angle meter, the torque meter and the index meter, and controls a torque output of the motor according to a mapping function in order to deliver an output torque from the output shaft that is compensated for angular variation of an angular-index-position-dependent torque transmission over the power line,

wherein the mapping function describes the torque transmission over the power line as a function of at least one of the absolute angular position (α

) of the input shaft and the absolute angular position (β

) of the output shaft.

2. The torque delivering power tool according to claim 1, wherein the motor comprises the angle meter, and the angle meter monitors the angular rotation of the motor shaft directly driven by the motor.

3. The torque delivering power tool according to claim 1, wherein the motor comprises the torque meter, and the torque meter monitors the torque acting on an input side of the power line.

4. The torque delivering power tool according to claim 2, wherein the motor comprises the torque meter, and the torque meter monitors the torque acting on an input side of the power line.

5. The torque delivering power tool according to claim 1, wherein an auxiliary index meter is arranged such that index meters are arranged at both the input shaft and the output shaft, whereby the absolute angular position (α

) of the input shaft and the absolute angular position (β

) of the output shaft are monitored.

6. The torque delivering power tool according to claim 2, wherein an auxiliary index meter is arranged such that index meters are arranged at both the input shaft and the output shaft, whereby the absolute angular position (α

) of the input shaft and the absolute angular position (β

) of the output shaft are monitored.

7. The torque delivering power tool according to claim 3, wherein an auxiliary index meter is arranged such that index meters are arranged at both the input shaft and the output shaft, whereby the absolute angular position (α

) of the input shaft and the absolute angular position (β

) of the output shaft are monitored.

8. The torque delivering power tool according to claim 4, wherein an auxiliary index meter is arranged such that index meters are arranged at both the input shaft and the output shaft, whereby the absolute angular position (α

) of the input shaft and the absolute angular position (β

) of the output shaft are monitored.

9. The torque delivering power tool according to claim 1, wherein the angle meter and the index meter are integrated in one unit, and wherein a power source is arranged to continuously power said one unit, such that the absolute angular position (α

) of the input shaft or the absolute angular position (β

) of the output shaft is continuously monitored.

10. The torque delivering power tool according to claim 2, wherein the angle meter and the index meter are integrated in one unit, and wherein a power source is arranged to continuously power said one unit, such that the absolute angular position (α

) of the input shaft or the absolute angular position (β

) of the output shaft is continuously monitored.

11. The torque delivering power tool according to claim 3, wherein the angle meter and the index meter are integrated in one unit, and wherein a power source is arranged to continuously power said one unit, such that the absolute angular position (α

) of the input shaft or the absolute angular position (β

) of the output shaft is continuously monitored.

12. The torque delivering power tool according to claim 4, wherein the angle meter and the index meter are integrated in one unit, and wherein a power source is arranged to continuously power said one unit, such that the absolute angular position (α

) of the input shaft or the absolute angular position (β

) of the output shaft is continuously monitored.

13. The torque delivering power tool according to claim 1, wherein the control unit varies the torque output of the motor during each rotation of the input shaft in order to deliver the output torque from the output shaft that is compensated for the angular variation of the torque transmission over the power line.

14. The torque delivering power tool according to claim 1, wherein the index meter is provided on the input shaft or on the output shaft.

15. The torque delivering power tool according to claim 1, wherein the index meter is provided on the input shaft.

16. A method for compensating a torque output in a torque delivering power tool, said torque delivering power tool including a power line including an input shaft, an output shaft and at least one gear arranged between the input shaft and the output shaft, and a motor shaft drivingly connected to the input shaft via a reduction gearing, the method comprising:

driving the input shaft by a motor, the input shaft being drivingly connected to the output shaft over the power line including the at least one gear;

monitoring an angular rotation of at least one of the input shaft and the output shaft;

monitoring an angular index position of at least one of the input shaft and the output shaft so as to obtain at least one of an absolute angular position (α

) of the input shaft and an absolute angular position (β

) of the output shaft; and

controlling a torque output of the motor according to a mapping function in order to deliver an output torque from the output shaft that is compensated for angular variation of an angular-index-position-dependent torque transmission over the power line,

wherein the mapping function describes the torque transmission over the power line as a function of at least one of the absolute angular position (α

) of the input shaft and the absolute angular position (β

) of the output shaft.

17. The method according to claim 16, wherein controlling the torque output of the motor comprises varying the torque output of the motor during each rotation of the input shaft in order to deliver the output torque from the output shaft that is compensated for the angular variation of the torque transmission over the power line.