Cooling Jacket Gap Bridging for Quieter Electric Machines

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Solution Overview

Problem

Existing electric machines experience disruptive vibrations and unwanted sound production due to secondary forces, which are exacerbated by gaps between the cooling jacket and housing, necessitating costly solutions like increased wall thickness or stiffening ribs.

Innovation Solution

Incorporating a material that expands to close the gap between the cooling jacket and housing during operation, providing a firm connection without additional structural reinforcement, using temperature or fluid-activated swelling materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the gap between the cooling jacket and housing is eliminated by increasing housing wall thickness, then vibration reduction is achieved, but weight and manufacturing costs increase

Engineering Contradiction:

ImprovevibrationVSAvoidhousing weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

A swellable material is introduced as an intermediary substance between the cooling jacket and housing. This material actively closes the gap through volume expansion, providing vibration damping and firm connection without requiring increased housing wall thickness, thus avoiding additional weight while effectively reducing vibrations

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The physical state of the gap-closing material is changed through parameter variation (temperature, fluid contact) to trigger volume expansion. This dynamic parameter change allows the material to transition from a compact installation state to an expanded operational state, firmly connecting the cooling jacket to the housing to reduce vibrations without permanent structural modifications

Inventive Principle:

Principle #35Parameter changes

2Strength

If additional stiffening ribs are added to the housing, then vibration resistance is improved, but manufacturing complexity and costs increase

Engineering Contradiction:

Improvevibration resistanceVSAvoidhousing structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The swellable material serves as an intermediary that provides vibration resistance through its expansion mechanism rather than through structural reinforcement. This eliminates the need for additional stiffening ribs or structural modifications to the housing, maintaining simplicity while achieving the desired vibration resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanical reinforcement approach (adding ribs) is replaced by a material-based solution (swellable material). The material's volume expansion creates firm mechanical connection and vibration damping without requiring complex structural modifications, substituting a simpler system for the more complex mechanical reinforcement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a press fit connection is implemented, then firm connection is achieved, but installation complexity and costs increase

Engineering Contradiction:

Improveconnection firmnessVSAvoidinstallation process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The gap-closing material is pre-installed in a compact state during the manufacturing process, before final assembly. This preliminary placement allows for simple installation without requiring complex heating or shrinking operations, while the material's subsequent expansion during operation achieves the firm press-fit-like connection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The connection mechanism transitions from static (permanent press fit requiring heating) to dynamic (material that expands and contracts). The swellable material can be easily installed in a compact state and then dynamically expands to create firm connection during operation, or contracts to allow disassembly, providing both reliability and ease of manufacture

Inventive Principle:

Principle #15Dynamics

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

Effectively reduces or eliminates vibrations and sound propagation by bridging the gap, maintaining a stable connection while allowing easy installation and disassembly.

Implementation Method 1

the material increases its volume at least during the operation of the electric machine, closing a gap between the respective web and the inner wall in the enlarged state

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

using temperature or fluid-activated swelling materials

Methodology Applied

Scientific EffectSwelling:

Data Source

PatentUS12580446B2Electric machine

Publication Date: 2026.03.17 AUDI AG

AI summary

An electric machine is provided including a stator, which is contained in a cooling jacket surrounding the stator about a periphery thereof, which cooling jacket is contained in a housing, wherein a plurality of outwardly protruding webs are provided on an outside of the cooling jacket, projecting in a direction of an inner wall of the housing, while between the webs and the inner wall there is provided a material which increases in volume to have an enlarged state at least during operation of the electric machine, closing a gap between each of the respective webs and the inner wall when in the enlarged state.