Cutting Tool Hood Ratchet Using an Integrated Flat Spring Pawl

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Solution Overview

Problem

Existing handheld cutting tools with protective hoods face challenges in providing reliable and efficient rotation arrest mechanisms that are both low-maintenance and cost-effective, often requiring multiple mechanical components that are prone to wear and tear under harsh conditions.

Innovation Solution

A handheld cutting tool with a holding fixture that integrates a spring-loaded pawl and toothing mechanism into a monolithic flat spring, allowing for a compact design with reduced parts and enhanced reliability, featuring a ratchet mechanism for controlled hood rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a latching mechanism with multiple mechanical components is used for arresting hood rotation, then the holding fixture can provide reliable rotation arrest, but the device complexity and manufacturing effort increase

Engineering Contradiction:
Improverotation arrest reliabilityVSAvoidholding fixture complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the spring element and pawl into a single integrated flat spring component. The flat spring serves dual functions: it provides the elastic force necessary for the pawl to engage with the toothing, and it forms the pawl itself that engages with the toothing on the hood. This consolidation reduces the number of separate mechanical components while maintaining the reliability of the rotation arrest function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flat spring performs multiple functions simultaneously: it acts as both the spring element and the pawl in the latching mechanism. This multi-functionality reduces device complexity by eliminating the need for separate spring components and pawl components, while still providing reliable rotation arrest of the hood.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple mechanical components are used in the holding fixture, then the rotation arrest function can be achieved, but the manufacturing effort and maintenance requirements increase

Engineering Contradiction:
Improveholding fixture reliabilityVSAvoidmanufacturing effort
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

By combining the spring and pawl into a single flat spring component, the patent reduces the number of parts that need to be manufactured, assembled, and maintained. This integration simplifies the manufacturing process while maintaining the reliability of the rotation arrest function through the inherent elastic properties and geometric design of the flat spring.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a conventional latching mechanism with separate components is used, then the holding fixture can engage the toothing, but the number of parts and moving components increases

Engineering Contradiction:
Improvehood rotation controlVSAvoidnumber of parts
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent integrates the spring element and pawl into a single flat spring component, reducing the number of parts in the holding fixture. This integration maintains ease of operation for hood rotation control while simplifying the overall structure by eliminating the need for multiple separate components.

Inventive Principle:
Principle #5Merging (Combining)

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 integrated flat spring design provides a robust and low-maintenance rotation arrest system that enhances handling and reduces manufacturing effort while ensuring reliable operation under harsh conditions.

Implementation Method 1

the holding fixture comprises a flat spring, wherein the pawl is formed by the flat spring

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4599968A1Handheld cutting tool
Publication Date: 2025.08.13 HILTI AG
  • EP4599968A1 patent drawingFigure 1~3
  • EP4599968A1 patent drawingFigure 4~6
  • EP4599968A1 patent drawingFigure 7~9

AI summary

Handheld cutting tool (101, 201) for driving a disc blade (109, 209), comprising a housing (110, 210), a hood (120, 220) for covering the disc blade (109, 209), wherein the hood (120, 220) is rotatably mounted on the housing (110, 210), a holding fixture for arresting rotation of the hood (120, 220) on the housing (110, 210), wherein the holding fixture comprises a toothing (125, 225) that is arranged on the hood (120, 220) and a spring-loaded pawl (132, 232) for engaging the toothing (125, 225), wherein the pawl (132, 232) is arranged on the housing (110, 210), characterized in that the holding fixture comprises a flat spring (130, 230), wherein the pawl (132, 232) is formed by the flat spring (130, 230).