Plunge Router Locking Lever With Spring-Biased Catch Release

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Solution Overview

Problem

The existing plunge router locking systems are prone to accidental unlocking due to the lock arm lever being knocked, and the mating catch device is susceptible to failure over time, requiring constant force to maintain the locked position.

Innovation Solution

A power tool with a plunge locking lever that is biased to the locked position and a catch mechanism engaged by a release lever, allowing for easy transition between locked and unlocked positions, reducing the risk of accidental unlocking and extending the device's lifespan by eliminating the need for constant force application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the lock arm lever is held in the unlocked position by the operator or a mating catch device, then the guide post can be adjusted, but the lock arm lever can be accidentally knocked back to the locked position and the mating catch device is prone to failure over time

Engineering Contradiction:
Improveease of adjusting guide postVSAvoidreliability of locking system
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention inverts the traditional locking mechanism by making the locked position the default state through a spring bias, rather than requiring active holding force. The lever naturally returns to the locked position unless actively disengaged by the catch mechanism, reversing the conventional approach where the unlocked position must be actively maintained.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The spring-loaded mechanism provides self-service by automatically returning the lever to the locked position without requiring continuous operator input. The system serves itself by using the spring's stored energy to maintain the default locked state and reset the lever after each adjustment operation.

Inventive Principle:
Principle #25Self-service

2Reliability

If the operator applies sufficient force to the lock arm lever to return it to the locked position, then the lever can be reset, but the mating catch device requires constant force application and is prone to failure

Engineering Contradiction:
Improvedurability of catch deviceVSAvoideffort to release lever
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The mechanism uses periodic action through the spring's oscillating force to automatically reset the lever to the locked position. Instead of requiring continuous force application, the spring provides periodic resetting action that occurs naturally with each cycle of lever movement, reducing wear on the catch device.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The spring provides beforehand cushioning by storing energy during the unlocking phase and releasing it to cushion the lever's return to the locked position. This pre-stored energy protects the catch device from impact forces and reduces mechanical stress during operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If the plunge locking lever is biased to the locked position, then accidental plunging is prevented, but the lever requires a catch mechanism for unlocking

Engineering Contradiction:
Improveaccidental plunging preventionVSAvoidcomplexity of catch mechanism
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention extracts the safety function from the general locking mechanism by implementing a dedicated spring bias system specifically for preventing accidental plunging. This separate safety mechanism works independently from the catch mechanism, allowing the catch to be simpler while maintaining enhanced safety through the spring's default locked positioning.

Inventive Principle:
Principle #2Taking out (Extraction)

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 provides a secure and reliable locking mechanism that prevents accidental plunging and reduces the likelihood of catch device failure, enhancing user safety and tool durability.

Implementation Method 1

the plunge locking lever is biased to the locked position

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

The rod is threaded through a spring arranged to bias the plunge locking lever

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4142974B1Power tool, locking system and plunge base
Publication Date: 2024.05.22 BLACK & DECKER CORP
  • EP4142974B1 patent drawingFigure 1
  • EP4142974B1 patent drawingFigure 2a~2c
  • EP4142974B1 patent drawingFigure 3

AI summary

A power tool comprises a housing and a motor assembly arranged to rotate a cutting tool, the motor being mounted in the housing. The power tool comprises at least one guide post slidably mounted to the housing and a base fixed to the at least one guide post. The power tool further comprises a plunge locking lever mounted to the housing. The plunge locking lever is moveable between a locked position wherein the at least one guide post is fixed with respect to the housing and an unlocked position wherein the at least one guide post is slidable with respect to the housing thereby adjusting the distance between the base and the housing wherein the plunge locking lever is biased to the locked position. The power tool comprises a catch mechanism arranged to engage the plunge locking lever in the unlocked position. The catch mechanism is mechanically coupled to a release lever arranged to disengage the catch mechanism and release the plunge locking lever from the unlocked position.