Electric Power Tool Motor Control Stage Timing

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Solution Overview

Problem

Conventional electric power tools, such as screwdrivers, do not allow users to advance the timing of starting specific stages in the motor control processing, limiting user flexibility during screw-tightening operations.

Innovation Solution

An electric power tool with a microcomputer-controlled circuit that enables users to set the operation mode to a measurement mode, allowing for advanced timing of starting specific stages, thereby allowing users to initiate the measurement mode at desired times and reducing the time required for torque measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional multi-stage control processing is used for motor control during screw-tightening, then the screw-tightening process is structured and controllable, but users cannot advance the timing of starting specific stages as they desire

Engineering Contradiction:
ImproveUser control over stage timingVSAvoidFixed multi-stage control structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the control stage transition timing adjustable rather than fixed. The microcomputer allows users to set custom timing for transitioning between control stages (S1, S2, S3) based on actual torque values detected during operation. This transforms the static, predetermined stage progression into a dynamic, adaptable process that responds to real-time operational conditions and user preferences.

Inventive Principle:
Principle #15Dynamics

2Productivity

If all control stages are executed in sequence, then complete torque control is achieved, but time is consumed for measurements and processing in each stage

Engineering Contradiction:
ImproveScrew-tightening speedVSAvoidTime for torque measurement and stage transitions
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent implements preliminary action by pre-setting multiple control stages with predetermined torque thresholds and transition conditions. The microcomputer is programmed with advance instructions for when to transition between stages based on detected torque values. This allows the system to automatically progress through stages without real-time decision delays, maintaining high productivity while ensuring complete torque control through the structured multi-stage approach.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If fixed control conditions are used for each stage, then the control process is simple and reliable, but adaptability to different user requirements and conditions is limited

Engineering Contradiction:
ImproveFlexibility in stage timing configurationVSAvoidConfiguration and control system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by allowing users to modify control parameters such as torque thresholds, timing delays, and transition conditions for each control stage. The microcomputer stores and processes these adjustable parameters, enabling the same hardware system to adapt to different screw-tightening requirements, material types, and user preferences without changing the physical structure, thereby achieving high adaptability through software-based parameter configuration.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3299128B1Electric power tool
Publication Date: 2021.07.28 MAKITA CORP
  • EP3299128B1 patent drawingFigure 1
  • EP3299128B1 patent drawingFigure 2
  • EP3299128B1 patent drawingFigure 3

AI summary

An electric power tool (1) includes a motor (4) and a controller (48). The controller (48) is configured to control the motor (4). Specifically, the controller (48) is configured to operate in at least two modes: a first mode and a second mode. The first mode includes a plurality of stages having different control conditions related to the motor (4). The second mode includes at least a common stage having control conditions same as those for a specific stage among the plurality of stages of the first mode. The common stage of the second mode starts more quickly than the specific stage of the first mode.