Cutting Tool Hood Ratchet Using an Integrated Flat Spring Pawl

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

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 improved 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 combines the spring element and pawl into a single integrated flat spring component. The flat spring serves dual functions: providing the elastic force necessary for the pawl to engage with the toothing, and forming the pawl itself that interacts with the toothing to arrest rotation. This merging of components reduces device complexity while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flat spring performs multiple functions simultaneously: it acts as both the spring element storing elastic energy and the pawl that engages with the toothing. This multi-functionality reduces the number of separate components needed in the holding fixture, addressing the contradiction between reliability and device complexity.

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

2Ease of operation

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:
Improvehood rotation controlVSAvoidholding fixture manufacturing
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

By merging 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 single component can be produced as one piece through forming or bending operations, significantly reducing manufacturing effort compared to producing separate spring and pawl components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the essential functions of springing and pawl engagement and combines them into a single flat spring element, eliminating the need for separate mechanical components. This extraction of core functions into one component simplifies both manufacturing and maintenance.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a conventional latching mechanism with multiple components is used, then the holding fixture can engage the toothing, but the maintenance effort increases under harsh conditions

Engineering Contradiction:
Improveholding fixture performanceVSAvoidholding fixture maintenance
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The integration of spring and pawl into a single flat spring component means there are fewer moving parts and fewer interfaces between components that could wear or fail. Under harsh construction site conditions, this reduced component count translates to lower maintenance requirements while maintaining reliable engagement with the toothing.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flat spring design allows the holding fixture to be serviced as a single unit. The elastic properties of the flat spring provide self-adjusting characteristics that can compensate for wear and environmental effects, reducing the need for frequent maintenance and adjustment.

Inventive Principle:
Principle #25Self-service

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 solution for controlling hood rotation, enhancing operational reliability and reducing manufacturing effort while maintaining high performance.

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

PatentEP4599969A1Handheld cutting tool
Publication Date: 2025.08.13 HILTI AG
  • EP4599969A1 patent drawingFigure 1~3
  • EP4599969A1 patent drawingFigure 4~6
  • EP4599969A1 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 (130, 230)-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).