Lightweight Bogie Frame: Extruded Side Members and Cast Centre

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Solution Overview

Problem

Existing railway bogie frames face challenges in achieving mechanical strength and stiffness while maintaining weight reduction, with welded joints and single casting methods compromising reliability.

Innovation Solution

A frame structure for a railway vehicle comprising extruded aluminium alloy side members and a cast centre member, connected via bolt connections and/or adhesive bonds, which absorb multidirectional loads and avoid weakening the material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If welded joints or single casting methods are used for aluminium alloy bogie frames, then weight reduction is achieved, but mechanical strength and reliability deteriorate

Engineering Contradiction:
Improvebogie frame weightVSAvoidmechanical strength and reliability
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The bogie frame is divided into multiple separate components (side members, cross members, end members) that are manufactured independently and then assembled together. This segmentation allows each component to be optimized for its specific function while maintaining lightweight construction, avoiding the need for heavy welded joints or single-piece casting.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses composite construction combining aluminium alloy components with strategic reinforcement elements and joining methods. The frame incorporates different aluminium alloys for different components, and uses adhesive bonds combined with mechanical fasteners to create a composite structure that achieves both weight reduction and enhanced mechanical strength.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If conventional frame structures are used, then manufacturing simplicity is maintained, but stiffness and mechanical strength deteriorate under multidirectional loads

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidstiffness under multidirectional loads
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The frame structure implements local quality optimization by placing ribs and reinforcement elements specifically at locations where multidirectional loads occur (such as at junctions of side members and cross members). This allows the structure to withstand complex loading conditions without requiring uniform thickening of all components, maintaining manufacturing simplicity while enhancing local stiffness.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The combination of extruded aluminium alloy members with cast aluminium alloy nodes creates a composite structure that efficiently handles multidirectional loads. The cast nodes can incorporate complex rib structures in multiple directions to resist torsional and bending loads, while the extruded members provide lightweight longitudinal strength.

Inventive Principle:
Principle #40Composite materials

3Weight of moving object

If material is removed for weight reduction, then weight decreases, but mechanical strength and vibration resistance deteriorate

Engineering Contradiction:
Improveframe weightVSAvoidvibration and noise resistance
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

Adhesive bonds serve as intermediary elements between the various frame components, providing not only structural joining but also damping and vibration isolation. The adhesive layer acts as a mediator that reduces noise and vibration transmission while maintaining the lightweight construction, preventing the deterioration of reliability that would otherwise result from material removal.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The composite construction with adhesive bonding creates a multi-layered structure that inherently provides vibration damping. The combination of different materials and the adhesive interface dissipate vibrational energy, allowing weight reduction without compromising vibration and noise resistance.

Inventive Principle:
Principle #40Composite materials

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 structure achieves improved mechanical strength and stiffness without increasing weight, while reducing vibration and noise transmission.

Implementation Method 1

the material of an extruded profile has a fibrous structure in the extrusion direction which cannot be achieved by a casting process, and which enables it to withstand high loads in the fibre direction

Methodology Applied
Scientific EffectFibrous structure:

Implementation Method 2

the centre member not only to absorb bending loads but also torsional loads

Methodology Applied
Scientific EffectTorsional load absorption:

Implementation Method 3

The side members are connected to the centre member by means of a bolt connection and/or an adhesive bond

Methodology Applied
Scientific EffectAdhesive bond: Adhesive

Data Source

PatentEP4219264B1Frame structure for a bogie
Publication Date: 2025.07.02 HITACHI LTD
  • EP4219264B1 patent drawingFigure 1a~1c
  • EP4219264B1 patent drawingFigure 2a~2b
  • EP4219264B1 patent drawingFigure 3

AI summary

The present subject matter in particular relates to a frame structure (1) for a bogie of a railway vehicle including at least one side member (20) which, when mounted on the railway vehicle, extends in longitudinal direction of the railway vehicle, and a centre member (30) which, when mounted on the railway vehicle, extends in a transverse direction of the railway vehicle. The at least one side member (20) comprises an extruded profile (2) made of an aluminium alloy, and the centre member (30) comprises a cast element (3) made from metal casting. The side member (20) is connected to the centre member (30) by means of a bolt connection (40) and/or an adhesive bond.