Electric Machine Case Ribs for Cooling Flow Control

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Solution Overview

Problem

The existing internal rotor type electric rotating machines with columnar supports in the cooling passage face increased manufacturing costs and difficulty in controlling cooling fluid flow, leading to complex core splitting and reduced cooling efficiency.

Innovation Solution

A case design with a cylindrical shape featuring a cooling passage and ribs that partition the passage in the axial direction, allowing for improved fluid flow control and reduced manufacturing complexity by connecting inner and outer radial walls circumferentially, with openings along the center axis to distribute cooling fluid effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If columnar supports are distributed and arranged in the cooling passage to increase rigidity, then the rigidity of the case is improved, but core splitting becomes complex during casting and manufacturing cost increases

Engineering Contradiction:

Improverigidity of the caseVSAvoidcore splitting complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the single complex columnar support structure with multiple simplified rib structures that are segmented and distributed within the cooling passage. Each rib is a simple linear element connecting the inner and outer circumferential surfaces, avoiding the complexity of columnar supports while collectively providing the necessary rigidity reinforcement.

Inventive Principle:

Principle #1Segmentation

2Strength

If columnar supports are distributed and arranged in the cooling passage to increase rigidity, then the rigidity of the case is improved, but the number of processes of core sand drainage increases and manufacturing cost increases

Engineering Contradiction:

Improverigidity of the caseVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The cooling passage is divided into multiple segments by the rib structures, creating distinct regions that facilitate systematic core sand drainage. Each rib acts as a separator that organizes the cooling passage into manageable sections, allowing for more efficient manufacturing processes compared to the undivided structure with columnar supports.

Inventive Principle:

Principle #1Segmentation

3Strength

If columnar supports are distributed and arranged in the cooling passage, then the rigidity of the case is improved, but it is difficult to control the flow direction of the cooling fluid

Engineering Contradiction:

Improverigidity of the caseVSAvoidcooling fluid flow control

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The rib structures are strategically positioned at specific locations within the cooling passage to locally guide and control the flow direction of the cooling fluid. By placing ribs at key positions, the patent creates flow control zones that direct the cooling fluid along desired paths, enabling effective flow management while maintaining case rigidity.

Inventive Principle:

Principle #3Local quality

4Object-affected harmful factors

If ribs are provided on the outer surface of the outer wall to prevent surface vibration, then surface vibration is reduced, but the device complexity increases

Engineering Contradiction:

Improvesurface vibrationVSAvoidstructural complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent combines the vibration prevention function with the existing rib structures inside the cooling passage. The same ribs that reinforce case rigidity and facilitate flow control also serve to reduce surface vibration, eliminating the need for separate external rib structures and thereby avoiding additional device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 enhances rigidity, reduces surface vibration, simplifies the cooling passage shape, decreases production costs, and increases cooling efficiency by facilitating easier sand drainage and fluid distribution, while allowing for flow rate adjustments and enhanced heat transfer.

Implementation Method 1

a cooling fluid is caused to flow through the cooling passage to transfer the heat of the stator core to the cooling fluid via the case

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

a rib which is provided inside the cooling passage, connects a wall portion on an inside in a radial direction of the case and a wall portion on an outside in the radial direction of the case, along the circumferential direction, are arranged to be separated from each other in an axial direction of the case, and partition the cooling passage into plural

Methodology Applied

Scientific EffectFluid flow control:

Data Source

PatentUS9331551B2Case of electric rotating machine

Publication Date: 2016.05.03 HONDA MOTOR CO LTD

AI summary

A case of an electric rotating machine, includes: a cooling passage which is provided inside the case along a circumferential direction of the case and through which a cooling fluid is able to flow; a cooling fluid inlet and a cooling fluid outlet which communicate with the cooling passage; and a rib which is provided inside the cooling passage, connect a wall portion on an inside in a radial direction of the case and a wall portion on an outside in the radial direction of the cooling passage along the circumferential direction, are arranged to be separated from each other in an axial direction of the case, and partition the cooling passage into a plurality of cooling passages.