Internal Combustion Engine Cooling Circuit with Bypass Valve

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Solution Overview

Problem

In cooling circuits for internal combustion engines, the cessation of coolant flow in the exhaust heat recovery system can lead to excessive coolant temperature and boiling, resulting in bubble formation that may cause pressure feed failures in the pressure-feeding unit.

Innovation Solution

The cooling circuit design includes a multi-control valve system that manages coolant flow through various heat exchangers, ensuring a minimum flow rate in the circulation circuit even when the primary circuit is shut off, thereby preventing pressure feed failures by maintaining coolant circulation through a secondary circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the valve unit stops the coolant flow in the exhaust heat recovery system, then the heat recovery efficiency is improved, but the coolant temperature increases excessively and boils causing bubbles that lead to pressure feed failure

Engineering Contradiction:
Improveheat recovery efficiencyVSAvoidpressure feed reliability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The cooling circuit is divided into multiple independent circulation paths: a first circulation path for engine cooling, a second circulation path for heat recovery, and a third circulation path as a bypass. The valve unit can selectively control coolant flow in each path, allowing the exhaust heat recovery system to operate independently without affecting the other circulation paths. This segmentation enables heat recovery efficiency to be improved while maintaining pressure feed reliability through alternative circulation routes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bypass circulation path acts as an intermediary solution between the conflicting requirements of heat recovery and pressure feed reliability. When the exhaust heat recovery system needs to stop coolant flow to improve heat recovery efficiency, the bypass path provides an alternative route that maintains minimum coolant circulation, preventing bubble formation and ensuring pressure feed reliability is maintained.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If the coolant flow is stopped in the exhaust heat recovery system, then the heat recovery effectiveness is improved, but bubbles are generated due to excessive temperature increase

Engineering Contradiction:
Improveexhaust heat recovery effectivenessVSAvoidbubble generation
Core Design Contradiction:
Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The cooling circuit is divided into multiple independent circulation paths: a first circulation path for engine cooling, a second circulation path for heat recovery, and a third circulation path as a bypass. The valve unit can selectively control coolant flow in each path, allowing the exhaust heat recovery system to operate independently without affecting the other circulation paths. This segmentation enables heat recovery efficiency to be improved while maintaining pressure feed reliability through alternative circulation routes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bypass circulation path acts as an intermediary solution between the conflicting requirements of heat recovery and pressure feed reliability. When the exhaust heat recovery system needs to stop coolant flow to improve heat recovery efficiency, the bypass path provides an alternative route that maintains minimum coolant circulation, preventing bubble formation and ensuring pressure feed reliability is maintained.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If the valve unit shuts off the primary circulation circuit, then the engine warm-up efficiency is improved, but the pressure feed unit fails due to bubbles in the exhaust heat recovery system

Engineering Contradiction:
Improveengine warm-up efficiencyVSAvoidpressure feed reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The cooling circuit is divided into multiple independent circulation paths: a first circulation path for engine cooling, a second circulation path for heat recovery, and a third circulation path as a bypass. The valve unit can selectively control coolant flow in each path, allowing the exhaust heat recovery system to operate independently without affecting the other circulation paths. This segmentation enables heat recovery efficiency to be improved while maintaining pressure feed reliability through alternative circulation routes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bypass circulation path acts as an intermediary solution between the conflicting requirements of heat recovery and pressure feed reliability. When the exhaust heat recovery system needs to stop coolant flow to improve heat recovery efficiency, the bypass path provides an alternative route that maintains minimum coolant circulation, preventing bubble formation and ensuring pressure feed reliability is maintained.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 prevents pressure feed failures due to bubble formation in the exhaust heat recovery system while allowing for efficient engine warm-up and heat recovery, maintaining operational stability.

Implementation Method 1

an exhaust heat recovery system for collecting heat from exhaust air of the internal combustion engine by coolant

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a pressure-feeding unit for feeding coolant under pressure

Methodology Applied
Scientific EffectPressure feeding: Pressure Gradient

Implementation Method 3

the temperature of the coolant in the exhaust heat recovery system increases excessively, and the coolant boils, the result being that bubbles may be generated in the coolant

Methodology Applied
Scientific EffectBoiling: Boiling

Data Source

PatentEP3147473B1Cooling circuit including an internal combustion engine
Publication Date: 2022.06.29 NISSAN MOTOR CO LTD
  • EP3147473B1 patent drawingFigure 1
  • EP3147473B1 patent drawingFigure 2
  • EP3147473B1 patent drawingFigure 3

AI summary

A cooling circuit for internal combustion engines includes an internal combustion engine, a pressure-feeding unit for feeding coolant, which cools the internal combustion engine under pressure, a valve unit having a plurality of heat exchangers connected in parallel thereto, an exhaust heat recovery system for recovering heat from exhaust air of the internal combustion engine by the coolant, a first circulation circuit including the pressure-feeding unit, the valve unit and the exhaust heat recovery system, and a second circulation circuit including the pressure-feeding unit and the exhaust heat recovery system.