Electric Machine Housing Seal Ring That Isolated Coolant From the Carrier

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Solution Overview

Problem

Existing electrical machine stator housings face challenges with sealing coolant flows due to swelling of polyamide seals, leading to adhesive bonds and increased costs, and potential disruptions in coolant flow causing cooling losses and drive unit failures.

Innovation Solution

A hollow cylindrical housing element with radially extending cooling channel sections and a ring-shaped carrier made of easy-to-process, fiber-filled thermoplastic, sealed by liquid silicone rubber, which prevents contact with the cooling medium and ensures a cost-effective, dimensionally stable seal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polyamide plastic ring is used to seal the cooling channel, then the seal forms an adhesive bond with the housing due to swelling, but the material becomes difficult to process and expensive

Engineering Contradiction:
Improvesealing reliabilityVSAvoidprocessing ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The sealing system is divided into two separate components: a support structure (carrier) made of easy-to-process thermoplastic material and a sealing arrangement made of hydrolysis-resistant elastomer. This segmentation allows each component to be optimized independently - the carrier for ease of manufacture and the sealing arrangement for reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The support structure acts as an intermediary between the housing and the sealing arrangement. It provides a stable, easy-to-manufacture base structure that does not contact the cooling medium, while the sealing arrangement (elastomer) directly contacts both the housing and cooling medium, providing the necessary sealing function without processing difficulties.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a polyamide plastic ring is used to seal the cooling channel, then the seal forms an adhesive bond with the housing, but the cost increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The sealing system is divided into two separate components: a support structure (carrier) made of easy-to-process thermoplastic material and a sealing arrangement made of hydrolysis-resistant elastomer. This segmentation allows each component to be optimized independently - the carrier for ease of manufacture and the sealing arrangement for reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The support structure is made from inexpensive, easy-to-process thermoplastic material that does not require expensive hydrolysis-resistant materials, since it does not contact the cooling medium. Only the sealing arrangement requires premium materials, reducing overall cost.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If the cooling channel sections are completely separated within the housing element, then the cooling medium flow can be controlled, but the device complexity increases

Engineering Contradiction:
Improvecooling medium flow controlVSAvoidhousing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cooling channel is divided into multiple completely separated cooling channel sections that extend radially into the housing element. This segmentation allows independent control of cooling medium flow in each section while maintaining a relatively simple overall housing structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling channel sections extend radially into the housing element rather than linearly, utilizing the radial dimension to create separated flow paths. This dimensional approach allows flow control without significantly increasing structural complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 provides a reliable and cost-effective sealing mechanism that prevents coolant leakage and flow disruptions, ensuring optimal cooling and safe operation of electrical machines by using a thermoplastic carrier completely shielded from the cooling medium, reducing the risk of swelling and hydrolysis resistance requirements.

Implementation Method 1

The sealing arrangement completely shields the support from fluid flowing along the cooling channel. This means that the sealing arrangement encloses the support in such a way that the support is completely sealed off from the cooling channel of the housing.

Methodology Applied
Scientific EffectPhysical containment / Sealing: Physical Containment

Implementation Method 2

a cooling channel, along which a cooling medium flows, runs from one of the cooling channel sections through a through-opening of the flat gasket, through the deflection section formed in the housing cover, and through another through-opening of the flat gasket to another cooling channel section

Methodology Applied
Scientific EffectConvection cooling: Convection

Implementation Method 3

The housing, in particular, has an optimized sealing ring... ensures optimal cooling and safe operation of electrical machines

Methodology Applied
Scientific EffectThermal cooling: Cooling

Data Source

PatentEP3959798B1Housing of an electric machine having an optimized sealing ring
Publication Date: 2024.06.05 ROBERT BOSCH GMBH
  • EP3959798B1 patent drawingFigure 1
  • EP3959798B1 patent drawingFigure 2
  • EP3959798B1 patent drawingFigure 3~4

AI summary

The present invention relates to a housing of an electric machine (1), comprising a hollow cylindrical housing element (5), in particular housing jacket, and at least one housing cover (6), which is attached to the end of the housing element (5), a cooling channel (8) being formed in the housing, the housing element (5) having at least two cooling channel sections (8.1) of the cooling channel (8), which each extend from a channel end opening (13) in an end face (11) of the housing element (5) in an axial direction relative to a housing axis (100) into the housing element (5). Two adjacent cooling channel sections (8.1) are flow-connected to each other via a deflection section (8.2) formed in the housing cover (6). There is a sealing gasket (7) for sealing off the cooling channel (8) between the housing element (5) and the housing cover (6), the sealing gasket (7) having through-openings (20) in the region of the channel end openings (13) for directing the cooling channel into the housing cover (6), and the sealing gasket (7) having an annular support (10) and a sealing assembly (9) mounted on the support. The housing is characterized in that the sealing assembly (9) surrounds the support (10) such that the support (10) is completely sealed off from the cooling channel (8) of the housing.