Electric Machine Housing Guide Webs Cooling

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Solution Overview

Problem

Existing fluid-cooled electric machine housings suffer from reduced cooling efficiency due to dead water areas where air bubbles accumulate, leading to ventilation issues and suboptimal heat transfer, despite efforts to increase flow speed and cooling surface area.

Innovation Solution

Incorporating guide webs between meander webs in the housing to split the cooling fluid flow into parallel streams, reducing dead water areas and enhancing the cooling surface area without increasing flow resistance, thereby improving cooling efficiency and mechanical rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling fins, cooling needles or meandering cooling channels are incorporated into the housing to increase cooling surface area, then cooling efficiency is improved, but dead water areas arise where air bubbles accumulate and reduce cooling efficiency

Engineering Contradiction:
Improvecooling efficiencyVSAvoidventing performance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The cooling channel is segmented into multiple flow paths by introducing guide webs that divide the single meandering flow into several parallel streams. This segmentation prevents the formation of large dead water areas and improves air bubble venting while maintaining the meandering cooling pattern for efficient heat transfer.

Inventive Principle:
Principle #1Segmentation

2Speed

If the cooling fluid is guided around the housing in a helical shape or meandering manner to increase flow speed, then cooling efficiency is improved, but flow resistance increases

Engineering Contradiction:
Improveflow speedVSAvoidflow resistance
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The cooling fluid flow is extended into the axial dimension by introducing guide webs that create parallel flow paths between meander webs. This dimensional addition increases the effective cooling surface area and flow speed without proportionally increasing flow resistance, as the fluid travels through multiple parallel channels rather than a single long path.

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

3Temperature

If guide webs are added to divide cooling fluid into parallel flows to reduce dead water areas, then cooling efficiency and venting are improved, but device complexity increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoidhousing structure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The guide webs serve multiple functions simultaneously: they divide the cooling fluid into parallel flows to eliminate dead water areas, provide structural reinforcement to the housing, and act as additional cooling surfaces. This multi-functionality reduces the need for separate components and justifies the added complexity through enhanced performance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The guide webs are integrated directly into the housing structure, merging the flow division function with the housing structural elements. This integration eliminates the need for separate, detachable flow dividers and allows the guide webs to simultaneously serve as structural reinforcement and cooling channel components.

Inventive Principle:
Principle #5Merging (Combining)

4Temperature

If cooling surface area is enlarged to improve heat transfer, then cooling efficiency is improved, but flow resistance and pump capacity requirements increase

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidpump capacity
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The cooling surface area is expanded by utilizing the axial dimension through guide webs that create parallel flow paths. This allows the cooling fluid to access additional surface area without proportionally increasing the flow path length, thereby improving heat transfer efficiency without significantly increasing pump capacity requirements.

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

This design increases cooling efficiency by up to 30% with the same hydraulic pumping capacity, improves ventilation by reducing air bubble accumulation, and maintains pump capacity while enhancing mechanical rigidity and manufacturing ease.

Implementation Method 1

the at least one guide web is designed to divide the cooling fluid into parallel flows that are parallel to the longitudinal axis of the housing are guided between the first and the second meander web and flow in the same direction

Methodology Applied
Scientific EffectFluid flow division:

Implementation Method 2

the cooling fluid is guided around the housing in a helical shape, for example. Furthermore, elements such as cooling fins, cooling needles or the like can be incorporated into the housing

Methodology Applied
Scientific EffectMeandering flow:

Implementation Method 3

Electric machines can be cooled by liquids, for example. For this purpose, a cooling channel can be provided on the housing of the electric machine, in which a cooling fluid flows

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

The housing has a material with good thermal conductivity. For example, the housing may include a metal such as aluminum

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2701286B1Housing for an electric machine with meandering cooling channel and guide structures
Publication Date: 2020.03.04 ROBERT BOSCH GMBH
  • EP2701286B1 patent drawingFigure 1~3
  • EP2701286B1 patent drawingFigure 4~5
  • EP2701286B1 patent drawingFigure 6~7

AI summary

The housing (1) has outer- and inner circumferential surfaces (5, 7) forming a closed cooling passage (9) i.e. meander. Two meander bars (11, 13) are arranged at the cooling passage such that cooling fluid is conveyed into the cooling passage. Two guiding webs (17) are provided between the meander bars and connected to the outer- and inner circumferential surfaces. A longitudinal axis of the guiding web runs parallel to a longitudinal axis (15) of the housing. Longitudinal axes of the meander bars run parallel to the longitudinal axis of the housing. Independent claims are also included for the following: (1) a fluid-cooled electric machine (2) a method for manufacturing a housing.