Motor Control Method for Hand-Held Power Tools
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Solution Overview
Problem
Hand-held power tools with lockable operator control elements risk undesired restarts when the control element is locked, posing safety hazards due to the potential for accidental activation when connected to a power source.
Innovation Solution
A method for controlling the motor of a hand-held power tool that deactivates it if the deviation between the first and second positions of the operator control element falls below a threshold value, utilizing a position-determining unit such as a potentiometer or optical detection element to ascertain positions and prevent motor activation when the control element is locked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electronics system is supplied with electricity immediately when connected to a power source, then the power tool is ready for operation, but the motor may activate accidentally when the operator control element is locked
Solution Approach 1:
The system performs preliminary actions (supplying electricity and initializing the electronics system) before the operator control element is released, but delays motor activation until after the control element is released and position verification is complete. This preliminary preparation enables quick operation while the delayed motor activation prevents accidental startup.
Solution Approach 2:
The system continuously monitors the position of the operator control element using a position-determining unit and compares it against threshold values. This feedback mechanism detects whether the control element is locked or intentionally activated, enabling the system to distinguish between accidental contact during locking and deliberate activation attempts, thus preventing false motor activation.
2Ease of operation
If the operator control element is locked in position, then simplified handling is achieved, but the position-determining unit may detect position changes due to locking mechanism movement
Solution Approach 1:
The system determines a first position of the operator control element before the locking operation is completed, then determines a second position after locking. By comparing these positions and allowing for expected movement due to the locking mechanism, the system accommodates the position change while still detecting intentional activation attempts.
Solution Approach 2:
The system changes the evaluation criterion from absolute position matching to position deviation analysis. Instead of requiring the control element to remain at exactly the same position, the system evaluates whether the position change exceeds a threshold value, accounting for the expected movement during locking while detecting excessive movement that indicates intentional activation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents the hand-held power tool from restarting when the operator control element is locked, enhancing safety by ensuring the motor remains deactivated until the control element is intentionally activated, thereby preventing accidental startup.
Implementation Method 1
The position-determining unit can comprise, by way of example, a potentiometer which determines the position of the operator control element by way of a changing resistance
Implementation Method 2
In addition or as an alternative, it is also conceivable for the position-determining unit to comprise an optical detection element which optically detects the position of the operator control element
Implementation Method 3
It is likewise conceivable for the detection unit to comprise a magnetic detection element, such as a Hall sensor for example, which magnetically detects the position of the operator control element
Data Source
AI summary
The disclosure relates to a method for controlling a motor of a hand-held power tool by means of a blockable operating element, wherein a first position and a second position of the operating element are ascertained. According to the disclosure, the motor remains deactivated if a deviation of the ascertained first position from the ascertained second position is less than a threshold value.