Power Tool Kickback Control With Angular Velocity Shutdown
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Solution Overview
Problem
Power tools experience kickback due to binding in workpieces, leading to loss of user control and potential injury, as existing technologies lack effective mechanisms to prevent or mitigate this issue.
Innovation Solution
A power tool equipped with a brushless DC motor, a switching network, a movement sensor, and an electronic processor that monitors angular velocity and power tool characteristics to implement kickback control by ceasing motor drive when predetermined thresholds are exceeded, adjusting operating parameters, and reversing motor direction to manage binding situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power tool is equipped with kickback control mechanisms including movement sensors and electronic processors, then user safety and control are improved, but device complexity increases
Solution Approach 1:
The patent implements feedback control by using movement sensors to detect tool motion and electronic processors to analyze sensor data, comparing measured values against threshold values to determine when kickback is occurring and automatically adjusting motor drive accordingly
Solution Approach 2:
The patent replaces traditional mechanical kickback prevention mechanisms with an electronic control system that uses sensors, processors, and software algorithms to detect and respond to kickback conditions, thereby reducing mechanical complexity while improving safety
2Measurement precision
If the electronic processor continuously monitors angular velocity and power tool characteristics to detect kickback, then kickback detection precision is improved, but use of energy increases
Solution Approach 1:
The patent applies partial monitoring by continuously tracking certain parameters like angular velocity while periodically or event-drivenly monitoring other power tool characteristics, rather than continuously monitoring all parameters at maximum precision, thus reducing energy consumption while maintaining adequate detection capability
3Ease of operation
If the switching network ceases motor drive immediately when kickback threshold is exceeded, then user control is improved, but productivity decreases
Solution Approach 1:
The patent applies preliminary anti-action by detecting early signs of kickback through sensor monitoring and threshold comparison, then proactively adjusting motor drive to prevent full kickback events from occurring, rather than waiting for kickback to fully develop and then reacting
Solution Approach 2:
The patent implements dynamic control by continuously adjusting motor drive based on real-time sensor feedback and changing operating conditions, allowing the system to optimize between productivity and safety depending on the current state rather than using fixed on/off control
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 reduces kickback occurrences, enhancing user control and safety by dynamically responding to binding conditions and adjusting power delivery, thereby preventing unintended tool movement.
Implementation Method 1
a brushless direct current (DC) motor within the motor housing portion and having a rotor and a stator. The rotor is configured to rotationally drive a motor shaft about a rotational axis
Implementation Method 2
a movement sensor configured to measure an angular velocity of the housing of the power tool about the rotational axis
Data Source
AI summary
Kickback control methods for power tools. One power tool includes a movement sensor configured to measure an angular velocity of the housing of the power tool about the rotational axis. The power tool includes an electronic processor coupled to the switching network and the movement sensor and configured to implement kickback control of the power tool. To implement the kickback control, the electronic processor is configured to control the switching network to drive the brushless DC motor, receive measurements of the angular velocity of the housing of the power tool from the movement sensor, determine that a plurality of the measurements of the angular velocity of the housing of the power tool exceed a rotation speed threshold, and control the switching network to cease driving of the brushless DC motor in response to determining that the plurality of the measurements of the angular velocity exceed the rotation speed threshold.