Power Tool Motor Control System and Method

Patent metadata

Field	Value
Publication number	US-2024278410-A1
Application number	US-202418582370-A
Country	US
Kind code	A1
Filing date	Feb 20, 2024
Priority date	Feb 21, 2023
Publication date	Aug 22, 2024
Grant date	—

Abstract

Embodiments of the disclosure provide a system and method of operating a power tool. The method includes measuring a battery current draw, sampling the battery current draw to generate a plurality of battery current samples, calculating an averaged current value by averaging the plurality of battery current samples, and comparing the averaged current value with a predetermined current value. The method also includes determining a number of motor revolutions, comparing the number of motor revolutions to a startup threshold, and determining a cycle is complete and stopping the motor when the number of motor revolutions exceeds the startup threshold and the averaged current value is greater than the predetermined current value.

First claim

1 . A method of operating a power tool, the power tool including a motor and a battery, the method comprising:
measuring battery current draw; sampling the battery current draw while the motor is running to generate a plurality of battery current samples; calculating an averaged current value by averaging the plurality of battery current samples; comparing the averaged current value with a predetermined current value; determining a number of motor revolutions; comparing the number of motor revolutions to a startup threshold; and determining a cycle is complete and stopping the motor when the number of motor revolutions exceeds the startup threshold and the averaged current value is greater than the predetermined current value.

2 . The method of claim 1 and further comprising measuring the battery current draw with a current sense resistor in series with the motor and the battery.

3 . The method of claim 1 and further comprising sampling the battery current draw at least once per millisecond while the motor is running.

4 . The method of claim 1 and further comprising calculating the averaged current value using at least 15 battery current samples.

5 . The method of claim 1 and further comprising using the averaged current value to estimate pressure without the use of a pressure sensor.

6 . The method of claim 1 and further comprising measuring a battery voltage and a battery impedance to estimate hydraulic pressure.

7 . The method of claim 1 wherein the power tool is a hydraulic power tool.

8 . The method of claim 7 and further comprising determining that a hydraulic cycle for at least one of a crimp operation and a cutting operation is complete based on the averaged current value.

9 . The method of claim 7 and further comprising determining that a hydraulic cycle for at least one of a crimp operation and a cutting operation is complete based on the averaged current value, battery voltage, and battery impedance.

10 . The method of claim 1 and further comprising measuring system temperature using a thermistor to adjust estimated pressure.

11 . A power tool comprising:
a hydraulic pump; a motor to drive the hydraulic pump; a battery to power the motor; a current sense resistor in series with the motor and the battery; and a controller that measures current drawn from the battery using the current sense resistor to determine a plurality of battery current samples, the controller
calculating an averaged current value by averaging the plurality of battery current samples,
comparing the averaged current value to a predetermined current value,
determining a number of motor revolutions,
comparing the number of motor revolutions to a startup threshold, and
determining a cycle is complete and stopping the motor when the number of motor revolutions exceeds the startup threshold and the averaged current value is greater than the predetermined current value.

12 . The power tool of claim 11 , wherein the controller samples the battery current draw at least once per millisecond while the motor is running.

13 . The power tool of claim 11 , wherein the controller calculates the averaged current value using at least 15 battery current samples.

14 . The power tool of claim 11 , wherein the controller uses the averaged current value to estimate pressure.

15 . The power tool of claim 11 , wherein the controller measures a battery voltage and a battery impedance to estimate hydraulic pressure.

16 . The power tool of claim 11 , wherein the power tool is a hydraulic power tool.

17 . The power tool of claim 16 , wherein the controller determines that a hydraulic cycle for at least one of a crimp operation and a cutting operation is complete based on the averaged current value.

18 . The power tool of claim 16 , wherein the controller determines that a hydraulic cycle for at least one of a crimp operation and a cutting operation is complete based on the averaged current value and battery voltage.

19 . The power tool of claim 16 , wherein the controller determines that a hydraulic cycle for at least one of a crimp operation and a cutting operation is complete based on the averaged current value and battery impedance.

20 . The power tool of claim 11 , and further comprising a thermistor to measure system temperature and to adjust estimated pressure.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Kuhls Alex R
• Ruppert Daniel

Classifications

• H02J7/80

  including monitoring or indicating arrangements · CPC title

• B25F5/00

  Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for · CPC title

• B25F5/005 Primary

  Hydraulic driving means · CPC title

• G01R19/16542 Primary

  for batteries (charge condition monitoring in G01R31/36) · CPC title

• H02J7/0047

  Electricity · mapped topic