Adaptive impact blow detection

Patent metadata

Field	Value
Publication number	US-11485000-B2
Application number	US-202016796594-A
Country	US
Kind code	B2
Filing date	Feb 20, 2020
Priority date	May 4, 2015
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A power tool and method of detecting impacts of a power tool that includes a motor driving a hammer to impact an anvil. A motor control unit is configured to determine a motor characteristic indicative of a speed of the motor. When the motor characteristic indicates that the speed of the motor is below a speed threshold, the motor control unit employs an acceleration-based technique to detect a first impact based on a change in motor acceleration and generate a first impact indication in response to detecting the first impact. When the motor characteristic indicates that the speed is above the speed threshold, the motor control unit employs a time-based technique to detect a second impact based on an elapsed time and generates a second impact indication in response to detecting the second impact.

First claim

What is claimed is:

1. A power tool comprising:
a housing;
an anvil supported by the housing;
a motor positioned within the housing configured to drive the anvil;
a hammer mechanically coupled to the motor, the hammer configured to deliver impacts to the anvil; and
a processor configured to:
determine a motor characteristic indicative of a speed of the motor,
when the motor characteristic indicates that the speed of the motor is below a speed threshold,
employ an acceleration-based technique to detect a first impact based on a change in motor acceleration, and
generate a first impact indication in response to detecting the first impact, and

when the motor characteristic indicates that the speed exceeds the speed threshold,
employ a time-based technique to detect a second impact based on an elapsed time, and
generate a second impact indication in response to detecting the second impact.

2. The power tool of claim 1 , wherein the processor is further configured to:
count the impacts delivered to the anvil using the acceleration-based technique and the time-based technique to determine an impact count, and
control the motor based on the impact count.

3. The power tool of claim 2 , wherein the processor is further configured to:
receive an impact count threshold indicating a desired number of impacts,
determine whether the impact count exceeds the impact count threshold, and
when the impact count exceeds the impact count threshold, perform one selected from the group consisting of stopping the motor, increasing a speed of the motor, decreasing the speed of the motor, and changing a direction of the motor.

4. The power tool of claim 1 , wherein, to detect the first impact according to the acceleration-based technique, the processor is configured to:
determine an acceleration of the motor, and
determine whether a change in the acceleration of the motor exceeds an acceleration threshold, and
wherein the first impact indication is generated when the change in the acceleration of the motor exceeds the acceleration threshold.

5. The power tool of claim 4 , further comprising a sensor within the housing to detect a rotational position of the motor, wherein the processor is further configured to determine the acceleration of the motor and the speed of the motor based on an output from the sensor.

6. The power tool of claim 4 , wherein the acceleration threshold is set based on at least one selected from the group consisting of a voltage of the motor and a speed of the motor.

7. The power tool of claim 1 , wherein, to detect the second impact according to the time-based technique, the processor is configured to determine that a predetermined impact time period elapsed.

8. A power tool comprising:
a housing;
an anvil supported by the housing;
a motor positioned within the housing configured to drive the anvil;
a hammer mechanically coupled to the motor, the hammer configured to deliver impacts to the anvil; and
a processor configured to:
determine a motor characteristic indicative of a speed of the motor,
set an acceleration threshold based on the motor characteristic,
detect an impact based on a change in motor acceleration exceeding the acceleration threshold, and
generate an impact indication in response to detecting the impact.

9. The power tool of claim 8 , wherein the processor is further configured to:
determine that the motor characteristic indicates that the speed of the motor exceeds a speed threshold, and
employ a time-based technique to detect a second impact when the speed of the motor exceeds the speed threshold.

10. The power tool of claim 9 , wherein, to employ the time-based technique to detect the second impact, the processor is further configured to:
set an impact time period based on the speed of the motor,
start a timer, and
determine, based on the timer, that the impact time period elapsed.

11. The power tool of claim 8 , wherein the processor is further configured to:
determine that the motor characteristic indicates that the speed of the motor exceeds a speed threshold,
determine that a current of the motor exceeds a current threshold, and
employ a time-based technique to detect a second impact when the speed of the motor exceeds the speed threshold and the current of the motor exceeds the current threshold.

12. The power tool of claim 8 , wherein the processor is further configured to:
count the impacts delivered to the anvil to determine an impact count, and
control the motor based on the impact count.

13. The power tool of claim 8 , wherein the processor is further configured to:
receive an impact count threshold indicating a desired number of impacts,
determine whether the impact count exceeds the impact count threshold, and
when the impact count exceeds the impact count threshold, performing, with the processor, one selected from the group consisting of stopping the motor, increasing a speed of the motor, decreasing the speed of the motor, and changing a direction of the motor.

14. The power tool of claim 13 , wherein the desired number of impacts is received via a user interface of the power tool, via a communication interface of the power tool from a user interface of an application executing on an external device, or via preprogramming of the power tool.

15. The power tool of claim 8 , wherein a value at which the acceleration is set decreases as the speed of the motor increases.

16. The power tool of claim 8 , wherein the change in motor acceleration is determined based on a difference between two motor velocity measurements over an elapsed time period.

17. A power tool comprising:
a housing;
an anvil supported by the housing;
a hammer mechanically coupled to the motor, the hammer configured to deliver impacts to the anvil;
a motor positioned within the housing, the motor configured to drive the hammer to deliver the impacts to the anvil; and
a processor configured to:
determine a motor characteristic indicative of a speed of the motor,
set an acceleration threshold based on the motor characteristic,
detect an impact based on a change in motor acceleration exceeding the acceleration threshold,
generate an impact indication in response to detecting the impact,
determine that the motor characteristic indicates that the speed of the motor exceeds a speed threshold,
determine that a current of the motor exceeds a current threshold, and
employ a time-based technique to detect a second impact when the speed of the motor exceeds the speed threshold and the current of the motor exceeds the current threshold.

18. The power tool of claim 17 , wherein the processor is further configured to:
set an impact period based on the speed of the motor,
set a timer in response to detecting the impact, and
detect the second impact when the impact period has elapsed based on the timer.

19. The power tool of claim 18 , wherein the processor is further configured to:
receive a desired number of impacts to be delivered, wherein the desired number of impacts is received via a user interface of the power tool, via a communication interface of the power tool from a user interface of an application executing on an external device, or via preprogramming of the power tool, and
when a number of detected impacts is greater than the desired number of impacts, perform one selected from the group consisting of stopping the motor, increasing a speed of the motor, decreasing the speed of the motor, and changing a direction of the motor.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Huber Alex
• Wycklendt Matthew
• Mergener Matthew
• Conrad Cole
• Yip Wing Fung

Classifications

• B25B23/18

  Devices for illuminating the head of the screw or the nut · CPC title

• B25B23/1475 Primary

  for impact wrenches or screwdrivers · CPC title

• B25B21/02

  with means for imparting impact to screwdriver blade or nut socket · CPC title