Method for regulating a speed of an electric motor of a power tool

Patent metadata

Field	Value
Publication number	US-10333441-B2
Application number	US-201715724352-A
Country	US
Kind code	B2
Filing date	Oct 4, 2017
Priority date	Oct 21, 2016
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

A method for regulating a speed of an electric motor of a power tool, the speed of the electric motor being established as a function of an actuation of a control device, the control device being actuated in such a way that a speed is requested which is less than a maximum speed, the speed being set in such a way that, in a first speed range upon an increase of the torque output by the electric motor, the speed decreases with a first negative slope, the speed being set in a second speed range in such a way that the speed proceeds with a second slope upon an increase of the output torque, the second slope being greater than the first slope when considered mathematically.

First claim

What is claimed is:

1. A method for regulating a speed of an electric motor of a power tool, the method comprising:
establishing the speed of the electric motor as a function of an actuation of a control device, the control device being actuated so that a speed is requested which is less than a maximum speed, the speed being set so that, in a first speed range upon an increase of torque output by the electric motor, the speed decreases with a first negative slope, the speed being set in a second speed range so that the speed extends with a second slope upon an increase of the output torque, the second slope being greater than the first slope when considered mathematically;
wherein a threshold speed is provided, the threshold speed delimiting two speed ranges, the curve of the speed over the torque having different slopes in the two speed ranges.

2. The method as recited in claim 1 , wherein, in the first speed range, the speed increases with the first slope upon a decrease of the output torque, and the speed extends with the second slope in the second speed range upon a decrease of the output torque.

3. The method as recited in claim 1 , wherein the speed is kept approximately constant in the second speed range, so that the second slope has a value of zero.

4. The method as recited in claim 1 , wherein a third speed range is provided, in the third speed range, the speed being set so that with an increase of the output torque, the speed changes with a third slope, the third slope being different from the second slope.

5. The method as recited in claim 4 , wherein there is at least one fourth speed range, and wherein in the fourth speed range, the speed of the electric motor is set so that the decrease of the speed with an increase of the output torque is less than in the second speed range.

6. The method as recited in claim 1 , wherein a change of the speed with the increase of the torque is a function of an operating parameter of the power tool.

7. The method as recited in claim 6 , wherein the operating parameter represents a transmission ratio of a transmission of the power tool.

8. The method as recited in claim 6 , wherein the operating parameter represents an actuation of the control device of the power tool.

9. The method as recited in claim 6 , wherein the operating parameter represents a voltage of a current supply of the electric motor, the current supply being a battery.

10. The method as recited in claim 6 , wherein the operating parameter represents a temperature of the power tool, the temperature being a temperature of at least one of a battery, electronics, and the electric motor.

11. The method as recited in claim 1 , wherein the threshold speed is a function of an operating parameter of the power tool.

12. The method as recited in claim 1 , wherein one of a ratio between the speed and the output torque, or a threshold speed, is changed via an actuation of an operating element on the power tool.

13. The method as recited in claim 1 , wherein one of a threshold speed, or a ratio between the speed and the output torque, is changed via a communication interface.

14. A control unit for regulating an electric motor of a power tool, comprising:
a control module configured to perform the following:
establishing the speed of the electric motor as a function of an actuation of a control device, the control device being actuated so that a speed is requested which is less than a maximum speed, the speed being set so that, in a first speed range upon an increase of the torque output by the electric motor, the speed decreases with a first negative slope, the speed being set in a second speed range so that the speed extends with a second slope upon an increase of the output torque, the second slope being greater than the first slope when considered mathematically;
wherein the control module includes a speed regulator, a setpoint current limiter, and a current regulator.

15. The control unit as recited in claim 14 , further comprising:
a signal processing unit, the signal processing unit detecting a current intensity output by power electronics to the electric motor, the signal processing unit detecting a signal for establishing a speed of the electric motor, the signal processing unit relaying a value of an output current of the power electronics to the current regulator, the signal processing unit relaying a value for the speed of the electric motor to the speed regulator and a setpoint current limiter, a setpoint speed being ascertained by the signal processing unit as a function of the actuation of the control device and the setpoint speed being relayed to the speed regulator, the speed regulator ascertaining a setpoint current as a function of a comparison of the ascertained speed and the setpoint speed, the setpoint current being relayed via a fifth control line to the setpoint current limiter, the setpoint current limiter ascertaining a value for the setpoint current as a function of the ascertained speed and the measured current, and the value for the setpoint current being relayed to the current regulator.

16. The control unit as recited in claim 15 , wherein the signal processing unit detects a voltage of a current/voltage source, the signal processing unit relaying the value of the voltage of the current/voltage source to the current regulator, and the signal processing unit relaying the value of the voltage of the current/voltage source to the setpoint current limiter, the setpoint current limiter ascertaining a value for the setpoint current as a function of the measured speed and the measured voltage and the measured current.

17. The control unit as recited in claim 16 , wherein the setpoint current limiter accesses data of a data memory and takes into consideration the predefined speed ranges, in which a predefined slope is predefined for the behavior of the speed with an increase or decrease of the torque.

18. A power tool, comprising:
a control unit;
an electric motor, the control unit designed to regulate a speed of the electric motor of a power tool, the control unit designed to establish the speed of the electric motor as a function of an actuation of a control device, the control device being actuated so that a speed is requested which is less than a maximum speed, the speed being set so that, in a first speed range upon an increase of torque output by the electric motor, the speed decreases with a first negative slope, the speed being set in a second speed range so that the speed extends with a second slope upon an increase of the output torque, the second slope being greater than the first slope when considered mathematically,
wherein a threshold speed is provided, the threshold speed delimiting two speed ranges, the curve of the speed over the torque having different slopes in the two speed ranges.

19. The power tool as recited in claim 18 , further comprising:
a transmission which changes a transmission ratio without further assistance by an operator of the power tool.

20. The power tool as recited in claim 18 , wherein the power tool includes a screwdriver without a striking mechanism.

21. The power tool as recited in claim 18 , further comprising:
a mechanical or electronic torque clutch;
wherein the power tool is in a drilling position without usage of the torque clutch.

22. A method for regulating a speed of an electric motor of a power tool, the method comprising:
establishing the speed of the electric motor as a function of an actuation of a

Assignees

• Bosch Gmbh Robert

Inventors

• Koniakowsky Joerg
• Mock Stefan

Classifications

• G05B19/414

  Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller · CPC title

• B23B45/02

  driven by electric power · CPC title

• H02K11/30

  Structural association with control circuits or drive circuits · CPC title

• H02K7/145

  Hand-held machine tool · CPC title

• B25B21/008 Primary

  with automatic change-over from high speed-low torque mode to low speed-high torque mode · CPC title