Wear-Resistant Buffer Stopper for Higher Energy Absorption

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Solution Overview

Problem

Existing buffer stoppers in steering gears face challenges in increasing absorbable energy without altering characteristics, particularly when space is limited, and suffer from wear issues that affect reaction force and displacement, leading to decreased performance.

Innovation Solution

A buffer stopper with a rubber elastic body and a wear-resistant sheet made of elastic cloth surrounding the buffer body, which contacts the housing's inner surface during radial expansion and deformation, preventing wear and enhancing compression reaction force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the volume of the buffer body is increased to increase absorbable energy amount, then the absorbable energy amount increases, but the permissible space is severely limited due to the structure of the apparatus

Engineering Contradiction:
Improveabsorbable energy amountVSAvoidvolume of buffer body
Core Design Contradiction:
Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The invention uses a composite structure combining a rubber elastic body with a wear resistant sheet having different material properties. The rubber elastic body provides energy absorption through elasticity, while the wear resistant sheet provides friction control and prevents direct contact between the buffer body and housing, enabling enhanced energy absorption within limited space.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the friction parameters by introducing a wear resistant sheet with specific friction characteristics. This allows control over the interaction between the buffer body and housing, enabling optimization of energy absorption efficiency without increasing the buffer body volume.

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If a rubber elastic body having a high spring constant is used to increase absorbable energy amount in limited space, then the absorbable energy amount increases, but the spring constant is limited and sufficiently high reaction force cannot be obtained

Engineering Contradiction:
Improveabsorbable energy amountVSAvoidreaction force
Core Design Contradiction:
Use of energy by moving objectVSForce

Solution Approach 1:

The composite structure of the rubber elastic body combined with the wear resistant sheet creates a system where the frictional interaction between the sheet and housing contributes additional reaction force, supplementing the elastic reaction force and enabling sufficiently high total reaction force within limited space.

Inventive Principle:
Principle #40Composite materials

3Force

If the outer peripheral surface of the buffer body contacts the inner peripheral surface of the housing to secure compression reaction force, then the reaction force increases, but the outer peripheral surface of the buffer body is worn by repeatedly sliding

Engineering Contradiction:
Improvecompression reaction forceVSAvoidwear resistance
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The wear resistant sheet acts as an intermediary between the buffer body and the housing. It transfers the compressive load from the buffer body to the housing through friction, providing the necessary reaction force while preventing direct contact and wear between the buffer body and housing surfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The wear resistant sheet functions as a flexible thin film that surrounds the buffer body, allowing radial expansion and deformation while maintaining contact with the housing to transmit compressive forces, thereby protecting the buffer body from wear.

Inventive Principle:
Principle #30Flexible shells and thin films

4Reliability

If the outer peripheral surface of the buffer body is prevented from wearing by contacting the housing, then the reaction force is secured, but the transition point in the characteristic line moves to the large displacement side, decreasing reaction force in predetermined displacement

Engineering Contradiction:
Improvewear resistanceVSAvoidreaction force in predetermined displacement
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The wear resistant sheet changes the friction parameters of the system, creating a controlled frictional interaction that maintains reaction force in the predetermined displacement range while preventing wear. The sheet's material properties are selected to optimize both wear resistance and force characteristics.

Inventive Principle:
Principle #35Parameter changes

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 increases absorbable energy while preventing wear and maintaining characteristic stability, ensuring effective shock absorption and prolonged component life by managing spring constant and reducing wear-related deterioration.

Implementation Method 1

the buffer body 103 integrally provided between the metal rings 101 and 102 and containing a rubber elastic body (rubber material or synthetic resin material having rubber-like elasticity)... reduces a shock by the compression and deformation in the axial direction of the buffer body 103

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The magnitude of the absorbable energy amount can be expressed as the area of a hatched region between the characteristic line of the buffer body 103 and the horizontal axis... the reaction force is plotted on the vertical axis and the displacement amount is plotted on the horizontal axis

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

there is a concern of causing changes in characteristics in which the outer peripheral surface of the buffer body 103 is worn by repeatedly sliding with the inner peripheral surface 202a of a large-diameter cylindrical portion 202 of the housing 200

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 4

the outer peripheral surface of the buffer body 103 is worn by repeatedly sliding with the inner peripheral surface 202a

Methodology Applied
Scientific EffectWear: Wear

Data Source

PatentEP3431808B1Buffer stopper
Publication Date: 2022.11.16 NOK CORP
  • EP3431808B1 patent drawingFigure 1
  • EP3431808B1 patent drawingFigure 2~3
  • EP3431808B1 patent drawingFigure 4

AI summary

This invention provides a buffer stopper (1) capable of increasing an absorbable energy amount without causing changes in characteristics due to wear of a buffer body (13). In order to achieve the object, the buffer body (13) containing a rubber elastic body disposed between an end surface (21a) formed in a housing (2) and an end surface (31a) formed in a shaft (3) which is relatively movable in the axial direction with respect to the housing (2) and a wear resistant sheet (14) which is provided so as to surround the outer peripheral surface of the buffer body (13) and which can contact an inner peripheral surface (22a) of the housing (2) by expansion and deformation in the radial direction of the buffer body (13) are provided.