Axle Box Suspension Stopper Structure for Rubber Bushing Distortion

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Solution Overview

Problem

The existing axle beam type axle box suspension systems for railcars face challenges in preventing excessive distortion of the elastic bushing during wheel tread brake operation, which increases the complexity and cost of the system.

Innovation Solution

The proposed solution involves an axle box suspension design with a tubular elastic bushing and a stopper portion at the axle beam, where the stopper portion limits excessive displacement by reacting with the core rod, allowing the elastic bushing to serve as a sacrificial component, thus preventing excessive distortion and maintaining cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a displacement suppressing mechanism is incorporated into the rubber bushing, then the durability of the rubber is secured, but the structure of the rubber bushing becomes complex and the cost for components increases

Engineering Contradiction:

Improvedurability of rubberVSAvoidstructure of rubber bushing

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The displacement suppressing function is segmented from the rubber bushing and transferred to the stopper portion provided on the axle beam. This separates the elastic function (rubber bushing) from the displacement limitation function (stopper portion), simplifying the rubber bushing structure while maintaining durability protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stopper portion acts as an intermediary element between the axle beam and the rubber bushing. It mediates the displacement control function, preventing excessive movement of the axle beam relative to the core rod, thereby protecting the rubber bushing from excessive distortion without requiring the rubber bushing itself to have a complex structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the spring constant of the rubber bushing is made small, then the travelling performance is improved, but the rubber is largely distorted when the wheel tread brake operates

Engineering Contradiction:

Improvetravelling performanceVSAvoiddistortion of rubber

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The stopper portion provides preliminary anti-action by establishing a mechanical stop before the rubber bushing can undergo excessive distortion. When the wheel tread brake operates and the axle beam displaces outward, the stopper portion contacts the core rod first, preventing the rubber bushing from experiencing large distortions that would compromise its strength.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If a displacement suppressing mechanism is incorporated into the rubber bushing, then excessive distortion is prevented, but the cost for components increases

Engineering Contradiction:

Improveprevention of excessive distortionVSAvoidcost for components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The stopper portion is designed as a simple, inexpensive structural feature on the axle beam that can be easily manufactured. Instead of making the rubber bushing complex and expensive to incorporate displacement suppression, the solution uses a simple stopper structure that achieves the same protective function at lower cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

This design effectively prevents excessive distortion of the elastic bushing and suppresses cost increases by allowing the elastic bushing to absorb stress while maintaining the structural integrity of the stopper portion, facilitating easy inspection and improved traveling performance.

Implementation Method 1

a tubular elastic bushing interposed between the tubular portion and the core rod... prevents excessive distortion of the elastic bushing

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11787451B2Axle box suspension and elastic bushing shaft body for use in railcar

Publication Date: 2023.10.17 KAWASAKI RAILCAR MFG CO LTD

AI summary

An elastic bushing includes a recess at a portion of an outer peripheral surface of the elastic bushing which portion is located at an inner side in a car longitudinal direction, the recess being recessed outward in the car longitudinal direction. A tubular portion of an axle beam includes a convex stopper portion protruding outward in the car longitudinal direction from a part of an inner peripheral surface of the tubular portion which part is located at the inner side in the car longitudinal direction, the stopper portion being inserted into the recess with a gap between the stopper portion and a bottom surface of the recess. A thickness of the elastic bushing at the recess in a radial direction is equal to or less than half a thickness of a portion of the elastic bushing in the radial direction which portion is located adjacent to the recess.