Electric Tool Motor Control for Current Protection

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional electric tools require users to manually release and re-engage the operation switch to cancel motor deactivation due to excess current, leading to inefficiencies in work processes.

Innovation Solution

An electric tool with a control system that includes a current detection mechanism and two cancel conditions: releasing the main switch or manipulating the output adjustment switch, allowing for automatic cancellation of motor deactivation and adjusting the current threshold for improved efficiency and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the operation switch is released to cancel motor deactivation, then the motor can be restarted, but the user must repeatedly release and press the switch which deteriorates work efficiency

Engineering Contradiction:
Improvemotor protectionVSAvoidwork efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system automatically cancels the forcible deactivation state when the output adjustment switch is manipulated, without requiring user intervention to release the main switch. The control means detects switch manipulation and autonomously restores motor operation, allowing the system to serve itself in canceling the protective deactivation state.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The output adjustment switch serves dual functions: adjusting motor rotational output and canceling the forcible deactivation state. This multi-functionality eliminates the need for a separate action to restart the motor, as the same switch controls both speed adjustment and deactivation cancellation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If the main switch is released to cancel deactivation, then the motor restarts, but this requires manual intervention that reduces productivity

Engineering Contradiction:
Improveexcess current protectionVSAvoidtime for switch re-engagement
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system prepares for potential deactivation by monitoring current continuously and pre-configuring the cancellation mechanism through the output adjustment switch. When deactivation occurs, the cancellation path is already established, allowing immediate restoration upon switch manipulation without requiring preliminary user decisions about whether to restart.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the operation switch must be released to cancel deactivation, then motor safety is maintained, but work continuity is interrupted

Engineering Contradiction:
Improvemotor safetyVSAvoidwork continuity
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The system maintains continuous useful action by enabling quick restoration of motor operation through output adjustment switch manipulation. The deactivation state is temporary and easily cancelable, allowing the motor to remain in productive operation with minimal interruption, thus preserving the continuity of the useful work being performed.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP2689896B1Electric tool
Publication Date: 2021.03.31 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP2689896B1 patent drawingFigure 1
  • EP2689896B1 patent drawingFigure 2~3

AI summary

It is provided an electric tool capable of securing safety by forcibly deactivating a motor when a motor current exceeds a threshold while suppressing a deterioration of the work efficiency. The electric tool of the invention includes a motor 3, a main switch 1 for switching ON or OFF of electricity supply to the motor 3, an output adjustment switch 2 for adjusting a rotational output of the motor 3, and a control means 6 configured to forcibly deactivate the motor 3 when a detection result by a current detection means exceeds a predetermined threshold. The control means cancels a forcibly deactivation state: when the main switch 1 is turned off under the forcibly deactivation state; or when the output adjustment switch 2 is manipulated under the forcibly deactivation state.