Electric Tool Torque Cutoff Using Composite Load Slope Detection

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Solution Overview

Problem

Existing electric tools, such as handheld drills, struggle to accurately adapt to varying working conditions and shut down at a preset position, leading to reduced efficiency in automatic fastening operations due to high misjudgment rates in torque control.

Innovation Solution

A control method and apparatus that calculates average current values using a composite average algorithm, combining arithmetical and sliding average algorithms, and determines slope values to accurately reflect the electric motor's working condition, thereby reducing misjudgment in torque output and enhancing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a simple average algorithm is used to calculate current values, then the calculation is simple and fast, but the accuracy of reflecting actual working conditions is low leading to high misjudgment rates

Engineering Contradiction:

Improveaccuracy of working condition detectionVSAvoidcomplexity of control algorithm

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the current calculation into multiple segments: obtaining multiple current values at different time points, calculating average current for each segment, then calculating a composite average of these segment averages. This segmentation approach improves accuracy by capturing variations in working conditions while maintaining manageable calculation complexity through structured processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary calculations by obtaining multiple current values and calculating their averages before making the final shutdown decision. This preliminary action of pre-processing current data ensures that the most accurate representation of working conditions is available when the shutdown threshold comparison is made, reducing misjudgment rates.

Inventive Principle:

Principle #10Preliminary action

2Extent of automation

If the electric tool shuts down automatically at preset position, then manual operation is reduced, but misjudgment of working conditions causes reduced efficiency in automatic fastening operations

Engineering Contradiction:

Improveautomatic shutdown functionVSAvoidefficiency of automatic fastening operation

Core Design Contradiction:

Extent of automationVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism where multiple current values are continuously monitored and averaged, and the shutdown decision is made based on comparing this feedback information against a preset threshold. This feedback-based approach ensures that the automatic shutdown function responds accurately to actual working conditions, maintaining high productivity by avoiding premature or delayed shutdowns.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameter used for shutdown control from a single current value to a composite average of multiple current values. This parameter change makes the control system more robust to variations in working conditions, ensuring that automatic fastening operations maintain high efficiency by shutting down at the correct position without misjudgment.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If current values are sampled at single time point, then the control response is fast, but the representation of actual working condition is inaccurate

Engineering Contradiction:

Improveaccuracy of working condition representationVSAvoidtime for current sampling and processing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent employs periodic sampling of current values at multiple time points before making the shutdown decision. This periodic action captures the dynamic nature of working conditions over time, ensuring accurate representation of the actual state. The composite average calculation then synthesizes these periodic measurements efficiently, minimizing time loss while maintaining high reliability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent performs preliminary sampling and averaging of multiple current values before the final shutdown decision is made. This preliminary action of pre-processing the current data ensures that accurate working condition representation is achieved without delaying the control response, as the multiple measurements are collected and processed in advance of the threshold comparison.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3476509B1Method and apparatus for controlling electric tool, and electric tool

Publication Date: 2025.06.25 POSITEC POWER TOOLS (SUZHOU) CO LTD

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AI summary

The present invention provides a control method and apparatus for an electric tool, and further provides an electronic tool, which relates to the field of automatic control of electric tools. The method comprises: Obtaining parameters characterizing an output shaft load during a running process of an electric tool; calculating the average values of the parameters characterizing an output shaft load according to a composite average algorithm, wherein the composite average algorithm comprises a combination of at least two average algorithms; calculating slope values of the parameters characterizing the output shaft load according to the average values of the parameters characterizing the output shaft load; and interrupting torque output of the electric tool according to the slope values of the parameters characterizing the output shaft load.