Vehicle Cooling Layout Using Height Difference to Suppress Boiling

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Solution Overview

Problem

In vehicle cooling systems with multiple heat exchangers in series, boiling of cooling water occurs in downstream exchangers due to increased temperature, leading to inefficiencies and potential damage.

Innovation Solution

Arranging the first heat exchanger at a higher position than the second heat exchanger creates a pressure gradient, suppressing boiling by increasing cooling water pressure in the downstream exchanger, while also positioning the second heat exchanger lower to benefit from lower atmospheric temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple heat exchangers are arranged in series on a cooling water circuit, then fuel consumption and output are improved, but cooling water temperature increases causing boiling in downstream heat exchangers

Engineering Contradiction:
Improvefuel consumption and outputVSAvoidcooling water temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent applies vertical positioning (height dimension) to resolve the temperature issue. By arranging the EGR cooler at a lower height than the intercooler, the system utilizes gravitational potential energy to increase cooling water pressure in the downstream EGR cooler, preventing boiling while maintaining the series configuration for improved fuel consumption and output.

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

2Productivity

If heat exchangers are arranged in series, then cooling efficiency is improved, but cooling water pressure drops causing boiling in downstream exchangers

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling water pressure
Core Design Contradiction:
ProductivityVSStress or pressure

Solution Approach 1:

The patent introduces vertical positioning to compensate for pressure drop. The EGR cooler is positioned lower than the intercooler, creating a height difference that generates additional pressure through position energy (gravitational potential energy), thereby maintaining sufficient cooling water pressure in the downstream EGR cooler despite the series arrangement.

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

3Adaptability or versatility

If downstream heat exchanger is positioned higher, then installation flexibility is improved, but atmospheric temperature increases causing boiling

Engineering Contradiction:
Improveinstallation flexibilityVSAvoidatmospheric temperature
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

The patent utilizes the vertical dimension for both pressure generation and temperature management. By positioning the EGR cooler lower than the intercooler, the system simultaneously increases cooling water pressure through position energy and exposes the downstream heat exchanger to lower atmospheric temperatures, preventing boiling while maintaining installation flexibility.

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 configuration effectively suppresses boiling in the downstream heat exchanger, allowing for controlled flow rates and improved fuel efficiency, and integrates the cooling system into a compact package.

Implementation Method 1

cooling water pressure in the second heat exchanger, which is positioned on a downstream side, rises due to position energy resulting from the height difference between the first heat exchanger and the second heat exchanger

Methodology Applied
Scientific EffectPosition energy (gravitational potential energy): Gravitation

Implementation Method 2

atmospheric temperature is higher toward an upper side, but the downstream second heat exchanger where cooling water temperature is higher is in a lower position

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4095366B1Cooling system for vehicle
Publication Date: 2024.05.15 NISSAN MOTOR CO LTD
  • EP4095366B1 patent drawingFigure 1
  • EP4095366B1 patent drawingFigure 2
  • EP4095366B1 patent drawingFigure 3~4

AI summary

A water-cooled intercooler (11) is arranged on an intake side of an engine (1), and a water-cooled EGR gas cooler (12) is arranged on the intake side of the engine (1). Cooling water is supplied to the water-cooled intercooler (11) by a cooling water pump (8), and the cooling water flows to the water-cooled EGR gas cooler (12) via an intermediate cooling water passage (13) crossing through an oil pan (6). The downstream water-cooled intercooler (11) is arranged in a low position as compared to a height position of the water-cooled intercooler (11). Due to this height difference, the cooling water in the water-cooled EGR gas cooler (12) has high pressure, and boiling of the cooling water is suppressed.