Power tool including an output position sensor

Patent metadata

Field	Value
Publication number	US-2017246732-A1
Application number	US-201715441953-A
Country	US
Kind code	A1
Filing date	Feb 24, 2017
Priority date	Feb 25, 2016
Publication date	Aug 31, 2017
Grant date	—

Abstract

A power tool including a motor and an impact mechanism. The impact mechanism is coupled to the motor and includes a hammer driven by the motor, and an anvil positioned at a nose of the power tool, and configured to receive an impact from the hammer. The power tool also includes a sensor assembly positioned at the nose of the power tool, and an electronic processor. The sensor assembly includes an output position sensor configured to generate an output signal indicative of a position of the hammer or the anvil. The electronic processor is coupled to the output position sensor and to the motor, and is configured to operate the motor based on the output signal from the output position sensor.

First claim

1 . A power tool comprising:
a motor; an impact mechanism coupled to the motor, the impact mechanism including
a hammer driven by the motor and
an anvil positioned at a nose of the power tool, and configured to receive an impact from the hammer;
an impact case housing the anvil and the hammer; a sensor assembly positioned in the impact case, the sensor assembly includes an output position sensor configured to generate an output signal indicative of one selected from a group consisting of a position of the hammer and a position of the anvil; and an electronic processor coupled to the output position sensor and to the motor, the electronic processor configured to:
control the motor based on the output signal from the output position sensor.

2 . The power tool of claim 1 , further comprising a motor position sensor configured to sense a rotational position of the motor and to provide motor position feedback information to the electronic processor.

3 . The power tool of claim 1 , wherein the output position sensor includes an inductive sensor.

4 . The power tool of claim 3 , wherein the anvil includes an engagement structure to engage with the hammer, and wherein the inductive sensor detects a rotational position of the engagement structure.

5 . The power tool of claim 3 , wherein the inductive sensor is an elongated sensor including a plurality of unevenly distributed inductive coils, such that a first end of the inductive sensor includes more densely arranged inductive coils than a second, opposite end.

6 . The power tool of claim 1 , wherein the output position sensor includes an inductive sensor configured to generate the output signal indicative of the axial position of the hammer.

7 . The power tool of claim 1 , wherein the output position sensor generates the output signal indicative of the position of the anvil, and wherein the sensor assembly further includes a second sensor configured to detect when the hammer is within a predetermined distance from the anvil.

8 . The power tool of claim 7 , wherein the electronic processor is configured to receive the output signal from the output position sensor, and operate the motor based on the output signals received while the hammer was outside the predetermined distance from the anvil according to the second sensor, and excluding the output signals received while the hammer was within the predetermined distance from the anvil.

9 . The power tool of claim 1 , wherein the sensor assembly is positioned in one selected from a group consisting of radially outward of an outer periphery of the hammer and on an annular structure that is circumferentially around the anvil.

10 . The power tool of claim 1 , further comprising a transmission coupled between the motor and the impact mechanism, and wherein the sensor assembly is positioned in front of the transmission.

11 . The power tool of claim 1 , wherein the electronic processor is configured to determine a speed of the motor; and control the motor based on the speed of the motor.

12 . The power tool of claim 1 , wherein the electronic processor is configured to determine a state of charge of a battery connected to the power tool, and change a control signal to the motor based on the state of charge of the battery.

13 . A method of operating a power tool, the method comprising:
activating, via an electronic processor, a motor of the power tool; driving, via the motor, an impact mechanism of the power tool, the impact mechanism including a hammer, and an anvil configured to receive an impact from the hammer, and the impact mechanism housed within an impact case; detecting, with a sensor assembly, a position of one selected from a group consisting of the hammer and the anvil, the sensor assembly being housed within the impact case; generating, with the sensor assembly, an output signal indicative of the position of the one selected from the group consisting of the hammer and the anvil, the position detected by the sensor assembly; and controlling, via the electronic processor, the motor based on the output signal.

14 . The method of claim 13 , wherein generating the output signal includes generating the output signal indicating that the hammer is within a predetermined distance of the anvil.

15 . The method of claim 13 , wherein detecting the position of the anvil includes detecting a position of an engagement structure of the anvil.

16 . The method of claim 15 , further comprising:
generating, via a hammer detector of the sensor assembly, a second output signal indicating that the hammer is within a predetermined distance from the anvil; generating, with the electronic processor, an averaged output position based on an average of the output signals received from the sensor assembly while the hammer is outside the predetermined distance from the anvil; and wherein controlling the motor includes controlling, via the electronic processor, the motor based on the average of the output signals.

17 . The method of claim 13 , further comprising generating a motor feedback signal, via a motor position sensor, the motor feedback signal providing feedback information regarding the motor, the feedback information including position information of the motor.

18 . The method of claim 13 , wherein controlling, via the electronic processor, the motor includes controlling the motor according to a first speed when the output signal indicates that the hammer is not impacting the anvil, and controlling the motor according to a second speed when the output signal indicates that the hammer is impacting the anvil.

19 . The method of claim 13 , wherein generating, with the sensor assembly, the output signal having a first output state indicating that the hammer is impacting the anvil, and a second output state indicating that the hammer is not impacting the anvil.

20 . The method of claim 13 , wherein generating, with the sensor assembly, the output signal includes generating an analog signal indicative of a distance between the hammer and the anvil.

21 . The method of claim 13 , wherein generating, with the sensor assembly, the output signal includes generating an analog signal indicative of a radial position of the anvil.

22 . The method of claim 13 , wherein controlling the motor includes controlling, with the electronic processor, a duty ratio of a motor control signal based on battery voltage of a power source powering the power tool.

23 . The method of claim 13 , further comprising:
receiving, at the electronic processor, a signal from a motor position sensor; and wherein controlling the motor includes controlling the motor based on the signal from the motor position sensor.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Dey Iv John Stanley
• Schneider Jacob Paul

Classifications

• B25B21/026

  Impact clutches · CPC title

• B25B23/1475 Primary

  for impact wrenches or screwdrivers · CPC title

• G01D5/2006

  by influencing the self-induction of one or more coils (G01D5/22 takes precedence) · CPC title

• B25D2250/005

  Adjustable tool components; Adjustable parameters · CPC title

• B25D2211/06

  Means for driving the impulse member · CPC title