Braking Resistor Bearing Structure for Thermal Expansion Control

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Solution Overview

Problem

Existing braking resistors in vehicles equipped with electrodynamic braking devices face thermal deformations and uneven cooling due to varying wind exposure, leading to potential mechanical stress on electrical connections.

Innovation Solution

The braking resistor features elongated, cylindrical heating cartridges with a bearing arrangement that includes fixed bearings and thin-walled, high-temperature-resistant retaining tabs, ensuring preload and preventing longitudinal displacement and twisting, thus protecting electrical connections from mechanical stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the braking resistor is continuously exposed to airflow for cooling, then heat dissipation is improved, but uneven cooling across different surface sections causes thermal deformations and mechanical stress on electrical connections

Engineering Contradiction:
Improveheat dissipationVSAvoidthermal deformation
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies local quality by making the bearing arrangement adaptable to local thermal conditions. The flexible retaining tabs allow each local section of the heating cartridge to expand and contract independently based on its specific thermal exposure, rather than requiring uniform thermal conditions across the entire component.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs parameter changes by allowing the bearing arrangement to dynamically adjust its mechanical constraints based on temperature variations. The flexible retaining tabs change their mechanical properties (flexibility) in response to thermal conditions, enabling the system to accommodate thermal expansion and contraction without deformation.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the heating cartridges are rigidly fixed to prevent movement, then positional stability is improved, but thermal expansion and contraction cause mechanical stress and potential destruction of electrical connections

Engineering Contradiction:
Improvepositional stabilityVSAvoidelectrical connection integrity
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies dynamics by transitioning from a static, rigid fixing system to a dynamic, flexible bearing arrangement. The retaining tabs can flex and move with the heating cartridges during thermal cycles, providing positional stability while accommodating dimensional changes without causing stress concentration that would damage electrical connections.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs beforehand cushioning by designing the flexible retaining tabs to anticipatorily absorb and accommodate thermal expansion and contraction forces before they can transmit stress to the electrical connections. This cushioning effect prevents mechanical stress buildup that would otherwise lead to connection failure.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If thick-walled retaining tabs are used for structural strength, then mechanical strength is improved, but flow resistance increases and heat dissipation efficiency decreases

Engineering Contradiction:
Improvestructural strengthVSAvoidheat dissipation efficiency
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The patent applies flexible shells and thin films by using thin-walled retaining tabs that provide sufficient mechanical strength through their flexible nature rather than through thickness. These thin-walled structures create minimal flow resistance to the cooling airflow while maintaining the necessary structural integrity to hold the heating cartridges, thereby optimizing heat dissipation efficiency.

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution ensures consistent heat dissipation across the braking resistor, preventing thermal deformations and mechanical stress on electrical connections, ensuring safe operation under varying thermal conditions.

Implementation Method 1

the heating cartridges are supplied with current from the vehicle's electrodynamic brake. This current causes the braking resistor to heat up

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

the braking resistor is continuously exposed to airflow to cool the braking resistor

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP4072894B1Braking resistor and vehicle equipped with same
Publication Date: 2024.08.28 SIEMENS MOBILITY GMBH DE
  • EP4072894B1 patent drawingFigure 1~4
  • EP4072894B1 patent drawingFigure 5~6
  • EP4072894B1 patent drawingFigure 7~8

AI summary

The invention relates to a braking resistor for a vehicle equipped with an electrodynamic braking device, wherein the braking resistor has a plurality of elongate, cylindrical heating cartridges (1) that are supported parallel to one another on at least two support carrier portions (6) of a support carrier (17), wherein the heating cartridges (1) are held by means of a bearing arrangement which comprises fixed bearings that prestress the heating cartridges (1) in the direction of the support carrier portions (6).