Driving Tool Plunger Stop Position Control via Voltage Fluctuation
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Solution Overview
Problem
Existing driving tools face challenges in stabilizing the stop position of a plunger due to varying plunger speeds caused by component wear and difficulties in detecting current peaks, especially when the plunger is stopped at the top dead center, leading to inaccuracies in determining the stop timing.
Innovation Solution
A driving tool equipped with a voltage fluctuation information acquisition unit and a control unit that utilizes inflection points in voltage and current fluctuations, along with speed and temperature information, to accurately control the motor and stabilize the plunger's stop position, reducing the need for position detection sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the stop position of the plunger is controlled based only on battery voltage, then the control system remains simple, but the stop position cannot be stabilized when plunger speed varies due to component wear
Solution Approach 1:
The system detects the inflection point in voltage fluctuation as feedback signal indicating plunger position, and uses this feedback to dynamically adjust motor control timing. This closed-loop feedback mechanism enables accurate stop position control without adding complex mechanical sensors, resolving the contradiction between system simplicity and positioning reliability.
2Measurement precision
If the plunger stop timing is determined by detecting current peak, then positional accuracy may be improved, but the current peak cannot be detected when start load increases and upper limit current is reached
Solution Approach 1:
The system uses voltage fluctuation as an intermediary parameter to indirectly detect plunger position. Instead of directly measuring current peak which fails under high load, the voltage fluctuation serves as a reliable mediator that consistently indicates plunger movement state and inflection points, enabling accurate position detection across all load conditions.
3Measurement precision
If additional sensors are added to detect plunger position accurately, then positional accuracy improves, but device complexity and cost increase
Solution Approach 1:
The system uses the motor's own voltage fluctuations during operation as the detection signal, making the motor serve dual purposes: both actuation and position sensing. This self-service approach eliminates the need for separate position detection sensors while maintaining high measurement precision, directly resolving the contradiction between accuracy and complexity.
Data Source
AI summary
A driving tool comprising: a plunger; a motor configured to move the plunger from a bottom dead center to a top dead center; a driving unit configured to use the plunger to drive a fastener by moving the plunger from the top dead center to the bottom dead center; a voltage fluctuation information acquisition unit configured to acquire voltage fluctuation information indicating a fluctuation amount of a voltage applied to the motor during movement of the plunger; and a control unit configured to control the motor based on the voltage fluctuation information.