Fastener Gripping Position Tracking Without Clutch Overshoot

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Solution Overview

Problem

Existing blind rivet setting tools face inaccuracies in jaw assembly position calculation over time due to cumulative errors, often requiring complex clutch mechanisms to prevent tool failure from overshooting, which increases tool complexity and reduces reliability.

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, allowing precise positioning without the need for a clutch mechanism by resetting inaccuracies after each fastening operation.

Engineering Contradictions & Design Principles

VSEngineering 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

Engineering Contradiction:

Improvejaw assembly position measurementVSAvoidtool failure likelihood

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical multi-sensor system with an electronic solution using a single home position sensor combined with motor turn counting. The controller calculates jaw assembly position by integrating motor rotation data, eliminating the need for multiple mechanical sensors and their associated complexity and failure points.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces motor turn information as an intermediary measurement. Instead of directly measuring jaw assembly position with multiple sensors, the system measures motor rotation and uses this intermediate data to calculate position, reducing sensor requirements while maintaining measurement capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple sensors are used to monitor jaw assembly position, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvejaw assembly position measurementVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple position measurement sensors into a single home position sensor combined with motor turn counting. This consolidation reduces the number of separate components while achieving the same measurement objective, directly reducing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The motor serves multiple functions: it drives the jaw assembly and simultaneously provides position information through turn counting. This multi-functionality eliminates the need for dedicated position sensors, reducing overall system complexity while maintaining measurement precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If cumulative errors in position calculation are not corrected, then device complexity is reduced, but manufacturing precision deteriorates

Engineering Contradiction:

Improveposition control systemVSAvoidjaw assembly positioning accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent implements preliminary action by resetting the motor turn counter to zero at the home position before each fastening operation. This periodic reset prevents cumulative error accumulation, maintaining positioning accuracy without requiring complex correction mechanisms throughout the operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The home position sensor provides feedback to the controller, which uses this information to reset the position reference. This feedback loop ensures that position calculation starts from a known accurate point for each operation, preventing error accumulation while keeping the system simple.

Inventive Principle:

Principle #23Feedback

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 enables accurate and reliable positioning of the jaw assembly with each fastening operation, reducing the likelihood of tool failure and eliminating the need for complex clutch mechanisms, thereby enhancing tool reliability and simplifying design.

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

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS20230012107A1Power tool having fastener gripping portion position tracking functionality

Publication Date: 2023.01.12 BLACK & DECKER CORP

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.