Method for detecting a first operating state of a handheld power tool

Patent metadata

Field	Value
Publication number	US-12145242-B2
Application number	US-202017441818-A
Country	US
Kind code	B2
Filing date	Mar 2, 2020
Priority date	Mar 25, 2019
Publication date	Nov 19, 2024
Grant date	Nov 19, 2024

Abstract

Method for detecting a first operating state of a handheld power tool, wherein the handheld power tool has an electric motor. In this case, the method comprises the steps of: (S 1 ) determining a signal of an operating variable of the electric motor; (S 2 ) comparing the signal of the operating variable with at least one model signal waveform typical of the state, wherein the model signal waveform typical of the state is assigned to the first operating state; (S 3 ) deciding whether the first operating state is present, wherein the decision at least partially depends on whether the model signal waveform typical of the state is identified in the signal of the operating variable in step S 2. Additionally disclosed is a handheld power tool, particularly an impact driver, with an electric motor and a control unit, wherein the control unit is designed to execute a method according to the disclosure.

First claim

The invention claimed is:

1. A method for detecting a first operating state of a handheld power tool having an electric motor, the method comprising:
ascertaining a signal of an operating quantity of the electric motor;
normalizing the signal of the operating quantity with at least one state-typical model signal form;
comparing the normalized signal of the operating quantity with the at least one state-typical model signal form to identify whether the state-typical model signal form is in the normalized signal of the operating quantity, the state-typical model signal form having been assigned to the first operating state; and
detecting the first operating state depending at least partially on whether the state-typical model signal form is identified in the normalized signal of the operating quantity,
wherein the state-typical model signal form, the pre-normalized signal of the operating quantity, and the normalized signal of the operating quantity represent the same operating quantity of the electric motor,
wherein the state-typical model signal form is an oscillation curve, and
wherein the normalization includes changing a wavelength of at least one of the pre-normalized signal of the operating quantity and the at least one state-typical model signal form so that the normalized signal of the operating quantity and the at least one state-typical model signal form have the same wavelength.

2. The method as claimed in claim 1 , wherein one of (i) the operating quantity is a speed of the electric motor and (ii) the operating quantity correlates the speed of the electric motor.

3. The method as claimed in claim 1 , the ascertaining further comprising:
recording the pre-normalized signal of the operating quantity as one of (i) a temporal progression of measured values of the operating quantity, and (ii) a temporal progression of measured values of a quantity of the electric motor that correlates with the temporal progression.

4. The method as claimed in claim 1 , wherein:
the ascertaining further comprises recording the pre-normalized signal of the operating quantity as a temporal progression of measured values of the operating quantity, and
the normalizing further includes transforming the temporal progression of the measured values of the operating quantity into a temporal progression of measured values of a quantity of the electric motor that correlates with the temporal progression of the measured values of the operating quantity.

5. The method as claimed in claim 1 , the ascertaining further comprising:
storing the pre-normalized signal of the operating quantity as a sequence of measured values in a memory of the handheld power tool.

6. The method as claimed in claim 5 , the ascertaining further comprising:
segmenting the sequence of measured values such that the pre-normalized signal of the operating quantity always comprises a predetermined number of measured values.

7. The method as claimed in claim 5 , wherein the memory of the handheld power tool is a ring memory configured to overwrite oldest data with newest data.

8. The method as claimed in claim 1 , the comparing further comprising:
comparing the normalized signal of the operating quantity with the state-typical model signal form using at least one of (i) a frequency-based comparison process and (ii) a comparative comparison process to determine whether at least one predetermined threshold value is satisfied.

9. The method as claimed in claim 8 , wherein:
the normalized signal of the operating quantity is compared with the state-typical model signal form using the frequency-based comparison process,
the frequency-based comparison process includes at least one of (i) bandpass filtering and (ii) frequency analysis, and
the predetermined threshold value is at least 85% of a predetermined limiting value.

10. The method as claimed in claim 9 , wherein the predetermined threshold value is at least one of (i) at least 90% of the predetermined limiting value and (ii) at least 95% of the predetermined limiting value.

11. The method as claimed in claim 8 , wherein:
the comparative comparison process includes at least one of (i) parameter estimation and (ii) cross-correlation, and
the predetermined threshold value is to at least 50% of a concordance of the normalized signal of the operating quantity with the state-typical model signal form.

12. The method as claimed in claim 1 , wherein:
the comparing further comprises determining a quality of the identification of the state-typical model signal form in the normalized signal of the operating quantity; and
the detecting further comprises detecting the first operating state at least partially based on the determined quality.

13. The method as claimed in claim 1 , wherein:
the comparing further comprises determining a deviation of the identification of the state-typical model signal form in the normalized signal of the operating quantity; and
the detecting further comprises detecting the first operating state at least partially based on the determined deviation.

14. The method as claimed in claim 1 , the detecting further comprising:
detecting the first operating state based on less than ten impacts of an impact mechanism of the handheld power tool.

15. The method as claimed in claim 14 , wherein the first operating state is identified based on at least one of (i) less than ten impact-oscillation periods of the electric motor, (ii) less than six impacts of the impact mechanism of the handheld power tool, in particular less than six impact-oscillation periods of the electric motor, (iii) less than four impacts of the impact mechanism of the handheld power tool, and (iv) less than four impact-oscillation periods of the electric motor.

16. The method as claimed in claim 1 , wherein the handheld power tool is an impact wrench and the first operating state is an impact mode.

17. The method as claimed in claim 16 , wherein the handheld power tool is a rotary impact wrench, and the first operating state is a rotary impact mode.

18. The method as claimed in claim 1 , wherein the state-typical model signal form is a trigonometric oscillation curve.

19. A handheld power tool comprising:
an electric motor;
a pick-up configured to measure values of an operating quantity of the electric motor and
a control unit configured to:
ascertain a signal of an operating quantity of the electric motor;
normalizing the signal of the operating quantity with at least one state-typical model signal form;
compare the normalized signal of the operating quantity with the at least one state-typical model signal form to identify whether the state-typical model signal form is in the normalized signal of the operating quantity, the state-typical model signal form having been assigned to a first operating state;
detect the first operating state depending at least partially on whether the state-typical model signal form is identified in the normalized signal of the operating quantity,

wherein the state-typical model signal form, the pre-normalized signal of the operating quantity, and the normalized signal of the operating quantity represent the same operating quantity of the electric motor,
wherein the state-typical model signal form is an oscillation curve, and
wherein the normalization includes changing a wavelength of at least one of the pre-normalized signal of the operating quantity and the at least one state-typical model signal form so that the normalized signal of the operating quantity and the at least one state-typical

Assignees

• Bosch Gmbh Robert

Inventors

• Winterhalter Juergen
• Erbele Simon
• Zibold Tobias
• Mock Stefan
• Herberger Wolfgang
• Saur Dietmar

Classifications

• B25B21/026

  Impact clutches · CPC title

• B25B23/1475 Primary

  for impact wrenches or screwdrivers · CPC title

• B25F5/00 Primary

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