Electric Generator Cooling via Rotor-Induced Airflow

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional cooling systems for electric generators in hybrid vehicles are cumbersome, costly, and inefficient, especially under low-load conditions, as they require radiators, cooling water pipes, and pumps, leading to increased weight and driving loss due to air friction from fans even when minimal cooling is needed.

Innovation Solution

A simplified cooling system where an electric generator is integrated with a rotor mounted to a crankshaft, featuring a cylindrical accommodating member with an air outlet that directs airflow to facilitate heat radiation without a fan, reducing air friction and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a water-cooling system with radiator, cooling water pipes, and pump is used, then cooling effectiveness is improved, but device complexity and weight increase

Engineering Contradiction:

Improvecooling effectivenessVSAvoidsystem complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent extracts and removes the complex water-cooling system components (radiator, cooling water pipes, pump) from the hybrid vehicle, replacing them with a simplified air-cooling system that uses only an air outlet and introduction port, thereby reducing device complexity while maintaining cooling functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical water-cooling system with a passive air-cooling system that utilizes natural airflow and pressure differential created by rotor rotation, eliminating the need for mechanical pumps and radiators

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If a fan is used for air-cooling, then cooling effectiveness is improved, but driving loss increases due to air friction resistance

Engineering Contradiction:

Improvecooling effectivenessVSAvoiddriving loss

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent enables the electric generator to cool itself by utilizing the pressure differential created during its own operation. The rotor rotation naturally creates negative pressure that draws in cooling air and positive pressure that expels hot air, eliminating the need for an external fan and reducing driving loss

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent removes the fan component from the cooling system, replacing active mechanical cooling with passive air-cooling that relies on pressure differential, thereby eliminating air friction resistance and reducing driving loss

Inventive Principle:

Principle #2Taking out (Extraction)

3Temperature

If a fan is installed for cooling, then cooling capability is improved, but costs increase

Engineering Contradiction:

Improvecooling capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the fan component from the cooling system, replacing it with a passive air-cooling mechanism that uses only structural modifications (air outlet and introduction port), thereby reducing manufacturing costs while maintaining cooling capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical fan system with a passive structural solution involving air outlets and introduction ports, eliminating the need for additional expensive components and simplifying manufacturing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration effectively radiates heat from the electric generator without increasing driving loss or costs, maintaining efficiency even under low-load conditions by utilizing natural airflow for cooling.

Implementation Method 1

the air flow generated in the vicinity of the rotor rotating is pushed out toward the air outlet in the vicinity of the rotor and discharged from the accommodating member through the air outlet. Thereby, an internal pressure in the accommodating member decreases, and the outside air is introduced into the accommodating member

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

the air flow generated in the vicinity of the rotor rotating... facilitates heat radiation from the rotor and the stator

Methodology Applied

Scientific EffectForced convection: Forced Convection

Implementation Method 3

air flow... facilitates heat radiation from the rotor and the stator

Methodology Applied

Scientific EffectConvection heat transfer: Convection

Data Source

PatentUS8766498B2Electric generator with cooling system and hybrid vehicle incorporating electric generator

Publication Date: 2014.07.01 KAWASAKI MOTORS LTD

AI summary

An electric generator incorporated into a hybrid vehicle including an engine and an electric drive motor and actuated by the engine, comprises a rotor mounted to one end portion of a crankshaft of the engine such that the rotor is rotatable integrally with the crankshaft; a cylindrical accommodating member surrounding an outer periphery of the rotor; and an air outlet provided on a peripheral wall portion of the accommodating member such that the air outlet opens in the vicinity of the outer periphery of the rotor and is tilted in a forward direction of a rotational direction of the rotor and in a radially outward direction.