Fastener Gripping Position Tracking With Home Sensor Reset
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Solution Overview
Problem
Existing blind rivet setting tools face inaccuracies in jaw assembly position calculation over time, leading to potential tool failure due to reliance on multiple sensors, which increases the likelihood of overshooting the intended range of movement.
Innovation Solution
A power tool with a motor, a fastener gripping portion, a home position sensor, and a controller that determines the fastener gripping portion's position using both sensor output and motor turn information, eliminating the need for multiple sensors by resetting position inaccuracies after each fastening operation and using a Hall sensor to detect magnetic flux for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to monitor jaw assembly position, then measurement precision is improved, but device complexity increases and reliability decreases
Solution Approach 1:
The patent extracts and eliminates redundant sensors from the system. Instead of using multiple sensors to monitor jaw assembly position, the invention uses a single home position sensor combined with motor turn information to determine position, thereby reducing sensor count while maintaining measurement precision and improving reliability.
Solution Approach 2:
The patent introduces motor turn information as an intermediary element to bridge the gap between the single home position sensor and continuous jaw assembly position monitoring. By counting motor turns and combining this data with home position sensor output, the system achieves accurate position tracking without requiring multiple sensors.
2Measurement precision
If multiple sensors are used to monitor jaw assembly position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent removes redundant sensors from the system architecture. By using motor turn information in combination with a single home position sensor, the invention eliminates the need for multiple position monitoring sensors, thereby reducing device complexity while preserving measurement precision.
Solution Approach 2:
The home position sensor serves multiple functions: it detects when the jaw assembly reaches the home position and works in conjunction with motor turn counting to provide continuous position monitoring throughout the jaw assembly's range of motion, eliminating the need for dedicated sensors at multiple positions.
3Device complexity
If motor turn information is used to track jaw assembly position, then device complexity is reduced, but measurement precision may deteriorate over time due to accumulation of errors
Solution Approach 1:
The patent implements a feedback mechanism where the home position sensor periodically verifies and corrects the jaw assembly position based on motor turn counting. When the jaw assembly returns to the home position, the sensor generates output that resets the motor turn counter, thereby eliminating accumulated positioning errors and maintaining long-term measurement precision.
Solution Approach 2:
The system performs preliminary positioning by using motor turn information to bring the jaw assembly close to the home position, then uses the home position sensor to make the final precise adjustment. This two-stage approach combines the efficiency of motor turn tracking with the accuracy of sensor-based detection.
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 ensures accurate and reliable positioning of the jaw assembly by resetting position inaccuracies after each use, reducing the need for clutch mechanisms and enhancing tool reliability by using a single sensor for precise detection of the home position, thereby preventing overshooting and extending tool lifespan.
Implementation Method 1
The home position sensor may be a Hall sensor mounted in a fixed position within the tool which is configured to detect a magnet which is axially fixed relative to the fastener gripping portion
Data Source
AI summary
A power tool comprising: a motor; a fastener gripping portion operatively coupled to the motor for causing movement of the fastener gripping portion between a home position and a retracted position to set a fastener; a home position sensor for generating output indicative that the fastener gripping portion has reached the home position during a reset stage of operation in which the fastener gripping portion is moved towards the home position; and a controller for receiving motor turn information indicative of the number of turns of the motor and for monitoring the position of the fastener gripping portion based on the motor turn information and the output generated by the home position sensor.