Ratchet Striking Mechanism Housing Stability

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Solution Overview

Problem

Hand-held power tools in shell construction with plastic housing face issues of reduced work output and stability due to impact energy losses and deformation under external forces, which disrupt the functioning of the gearing and torque coupling.

Innovation Solution

A sleeve-shaped support body with radially protruding arms provides a stable radial supporting effect, increasing the mass responsible for the primary support and reducing impact energy losses, while a metal support body enhances stability against external loads and simplifies assembly by being cast into the gear housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a plastic housing in shell construction is used, then the weight is kept low, but the housing is susceptible to deformation under external forces which disrupts the functioning of the gearing and torque coupling

Engineering Contradiction:
Improveweight of housingVSAvoidstability of housing
Core Design Contradiction:
Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The housing is constructed as a composite structure combining a plastic outer shell with an integrated metal reinforcement cage. The metal cage provides structural stability and resistance to deformation, while the plastic shell maintains low weight. This composite construction allows the housing to withstand external forces without disrupting internal components like the gearing and torque coupling.

Inventive Principle:
Principle #40Composite materials

2Device complexity

If the support body has minimal mass, then the device complexity is reduced, but impact energy losses increase due to insufficient support stability

Engineering Contradiction:
Improvecomplexity of support structureVSAvoidimpact energy losses
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The support body is merged with the housing structure through direct integration of the metal reinforcement cage into the plastic shell. This combining of structural elements creates a stable support system with sufficient mass to minimize impact energy losses, while avoiding the complexity of separate support components. The metal cage acts as both a structural reinforcement and a stable support body for the ratchet mechanism.

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 solution significantly increases the work performance and stability of the power tool by reducing impact energy losses and preventing deformation, ensuring a direct and efficient transmission of forces and maintaining the functionality of the tool under external loads.

Implementation Method 1

the tool spindle can be subjected to impulse-like axial movements along the working axis by a ratchet impact mechanism

Methodology Applied
Scientific EffectRatchet mechanism: Ratchet

Implementation Method 2

the support body has a sleeve-shaped base body from which a plurality of support arms protrude radially, which form the radial contact surface at their free ends

Methodology Applied
Scientific EffectImpact energy absorption: Impact Force

Data Source

PatentEP1800803B1Hand tool with a ratchet striking mechanism
Publication Date: 2009.06.17 HILTI AG
  • EP1800803B1 patent drawingFigure 1
  • EP1800803B1 patent drawingFigure 2
  • EP1800803B1 patent drawingFigure 3

AI summary

The tool (2) has a shell type construction main housing (4) from which a tool spindle (14) projects towards the working tool side end (18) and rotates around operational axis by a motor (12). A gear unit (16) accommodated in main housing transmits a driving torque from motor to the spindle using a ratchet percussion mechanism that has toothed rim fixed respect to housing, and is connected to supporting element which is formed in a circumferentially extending manner at an inner surface of the outer shell of the main housing.