Fastener Gripping Position Tracking Without Multiple Sensors
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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 the need for multiple sensors, which increases the likelihood of tool failure and requires clutch mechanisms to protect components from overshooting.
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 motor turn information and home position sensor output, eliminating the need for multiple sensors and clutch mechanisms by resetting position inaccuracies after each fastening operation.
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 combines multiple sensing functions into a single sensor system. The jaw assembly position is determined by integrating motor turn information with home position sensor output, merging the functions of multiple sensors into one coordinated system that reduces component count while maintaining measurement precision.
Solution Approach 2:
The motor turn information serves multiple functions: it tracks jaw assembly position during operation, determines when the home position is reached, and provides feedback for controller decision-making. This multi-functional use of motor information eliminates the need for dedicated position 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 combines multiple sensing functions into a single sensor system. The jaw assembly position is determined by integrating motor turn information with home position sensor output, merging the functions of multiple sensors into one coordinated system that reduces component count while maintaining measurement precision.
Solution Approach 2:
The controller acts as an intermediary that processes motor turn information and home position sensor output to determine jaw assembly position. This intermediary approach allows the system to achieve multi-sensor precision without physically installing multiple sensors.
3Reliability
If clutch mechanisms are added to protect components from overshooting, then reliability is improved, but device complexity increases
Solution Approach 1:
The system uses feedback from the home position sensor and motor turn information to detect when the jaw assembly reaches the home position. The controller receives this feedback and stops the motor, preventing overshooting without requiring mechanical clutch mechanisms.
Solution Approach 2:
The patent replaces mechanical clutch mechanisms with an electronic control system. The controller uses electrical signals from the home position sensor and motor turn information to stop the motor at the correct position, substituting mechanical protection with electronic control.
4Duration of action of moving object
If position inaccuracies accumulate over time, then measurement precision deteriorates, but operating duration increases
Solution Approach 1:
The system performs a preliminary action by detecting the home position using the home position sensor before resuming normal operation. This preliminary detection resets the position reference, preventing accumulation of position inaccuracies over time while allowing continuous operation.
Solution Approach 2:
The home position detection occurs periodically during reset stages of operation. This periodic re-calibration of the position reference ensures that measurement precision is maintained throughout extended operational periods by resetting accumulated errors.
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 determination of the jaw assembly's home position, reducing the likelihood of tool failure and eliminating the need for clutch mechanisms, thereby improving the tool's operational precision and reliability.
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
Figure 1
Figure 2
Figure 3a~3b
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.