Reciprocating Tool Jam Control via Sensor Feedback

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Solution Overview

Problem

Reciprocating tools such as hedge trimmers often jam during operation, causing delays and increasing the risk of injury when users attempt to clear the jam manually.

Innovation Solution

A reciprocating tool with an electric motor controlled by a controller that includes a jam sensing device to detect jams and initiate un-jamming procedures, including terminating the drive and reversing the reciprocating arrangement for a brief period upon user input.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the reciprocating arms are driven to move about each other to perform cutting function, then the productivity is improved, but the reciprocating arms may jam resulting in the tool being stuck in the jam position

Engineering Contradiction:

Improvecutting operation efficiencyVSAvoidjam-free operation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The controller proactively initiates un-jamming procedures upon detecting a jam condition through the jam sensing device, rather than waiting for the jam to persist. This preliminary action prevents the tool from remaining stuck and maintains operational reliability during high-productivity cutting operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The jam sensing device provides real-time feedback to the controller about the operational state of the reciprocating arms. This feedback mechanism enables the controller to detect jams and automatically initiate appropriate un-jamming procedures, resolving the contradiction between maintaining continuous productive operation and preventing jam-related failures.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If the user manipulates the reciprocating arms to clear the jam manually, then the jam can be cleared, but the risk of injury increases and operational delays occur

Engineering Contradiction:

Improvejam clearing capabilityVSAvoiduser injury risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The reciprocating tool performs self-service by automatically detecting jams through the jam sensing device and executing un-jamming procedures controlled by the controller. This eliminates the need for users to manually manipulate the reciprocating arms to clear jams, thereby removing the associated injury risk and operational delays while maintaining ease of operation.

Inventive Principle:

Principle #25Self-service

3Loss of time

If the controller activates un-jamming procedures automatically upon jam detection, then the loss of time is reduced, but the device complexity increases due to additional sensing and control mechanisms

Engineering Contradiction:

Improvejam clearance timeVSAvoidcontrol system complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The jam sensing device provides automated feedback to the controller, enabling rapid detection and response to jam conditions. This feedback mechanism significantly reduces the time loss associated with jams by eliminating manual detection and intervention, justifying the added device complexity through substantial productivity gains and safety improvements.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces manual mechanical manipulation of the reciprocating arms with an automated electronic control system. The controller uses electrical signals from the jam sensing device to activate motor-driven un-jamming procedures, substituting complex manual mechanical operations with a more efficient electromechanical system that reduces time loss despite increased initial complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Automatically detects and resolves jams in reciprocating tools, reducing operational delays and user risk by implementing controlled un-jamming procedures, enhancing safety and efficiency.

Implementation Method 1

the jam sensing device includes a hall effect sensor and/or an optical sensor to determine the position, speed, direction of movement, or any combination thereof of one or more operating component of the reciprocating tool to detect the jam

Methodology Applied

Scientific EffectHall effect: Hall Effect

Implementation Method 2

Methodology Applied

Scientific EffectOptical sensing:

Implementation Method 3

a reciprocating arrangement driven by an electric motor

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP3420808B1A reciprocating tool and a method to control thereof

Publication Date: 2020.06.03 TECHTRONIC OUTDOOR PRODS TECH

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AI summary

A reciprocating tool (10) comprising of a reciprocating arrangement (290, 312) driven by an electric motor (302) controlled by a controller (306) arranged to receive user input; wherein, the controller includes a jam sensing device (308) arranged to detect a jam in the reciprocating arrangement when the reciprocating arrangement is driven in a first direction, and when upon a jam is detected, activate a first un-jamming procedure (310) and when upon a change in the user input is detected, activate a second un-jamming procedure (310) arranged to drive the reciprocating arrangement in a second direction.