Striking Tool Motor Control for Stable Plunger Stop Position
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing striking tools face challenges in stabilizing the stop position of a plunger due to varying drive speeds and difficulties in detecting the peak current, leading to inconsistent performance and potential misalignment.
Innovation Solution
A striking tool equipped with a motor, plunger, moving unit, speed variation acquiring unit, and control unit that acquires and controls the motor based on the variation in rotating speed, allowing for precise control and stabilization of the plunger's stop position without relying on position detection sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the stop position of the plunger is controlled based on battery voltage alone, then the control method is simple, but the stop position cannot be stabilized due to varying plunger drive speed
Solution Approach 1:
The control unit acquires actual rotating speed information from the motor and uses this feedback to dynamically adjust the stop position control, replacing the open-loop voltage-based control with a closed-loop speed-based control system
Solution Approach 2:
The control method transitions from using battery voltage as the control parameter to using actual rotating speed as the control parameter, allowing for more accurate and adaptive stop position control that accounts for varying drive conditions
2Measurement precision
If the peak current detection method is used to determine motor stop timing, then the stop position can be controlled, but false detection occurs when current remains at upper limit value
Solution Approach 1:
The electrical measurement method (current detection) is replaced with a mechanical measurement method (rotating speed detection), using the motor's rotational speed as the basis for determining stop timing and position
Solution Approach 2:
The rotating speed acts as an intermediary parameter that indirectly reflects the motor's operational state and plunger position, providing a more reliable control basis than direct current measurement in high-load conditions
3Device complexity
If the plunger drive speed is assumed constant for control purposes, then the control calculation is simplified, but the stop position varies due to actual speed fluctuations
Solution Approach 1:
The control system transitions from assuming constant speed to dynamically tracking and responding to actual speed variations, making the control adaptive to changing operational conditions while maintaining reasonable complexity
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
The solution effectively stabilizes the stop position of the plunger, reducing variation in response time and eliminating the risk of false detection, even under changing battery voltage and component wear conditions, thus enhancing operational efficiency and accuracy.
Implementation Method 1
a motor (18)
Data Source
Figure 1
Figure 2
Figure 3(A)~3(H)
AI summary
A striking tool (10) includes: a motor (18) including a rotor; a plunger (22) configured to be movable from a bottom dead point to a top dead point by the motor (18); a moving unit (26) configured to move the plunger (22) from the top dead point toward the bottom dead point; a speed variation acquiring unit configured to acquire an amount of variation in rotating speed of the rotor (18); and a control unit (20) configured to control the motor (18), based on the amount of variation acquired by the speed variation acquiring unit.