Fuel Cell Vehicle Thermal Management via Switching Valve

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Solution Overview

Problem

Fuel-cell vehicles face challenges in maintaining the optimal temperature of secondary batteries, which affects their performance, as existing cooling systems either fail to prevent temperature decrease or cause overheating, especially when the ignition is turned on.

Innovation Solution

A cooling system configuration that includes a radiator, circulation and bypass flow passages, a switching valve, and temperature sensors, controlled by a controller to direct coolant flow between the fuel cell and secondary battery based on temperature thresholds, ensuring the battery is heated when necessary and cooled when not.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the cooling system of the fuel cell is used to control the temperature of the secondary battery, then the temperature of the secondary battery can be maintained, but the system complexity increases due to additional flow passages and switching valves

Engineering Contradiction:
Improvesecondary battery temperatureVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling system of the fuel cell is designed to serve dual purposes: cooling the fuel cell and controlling the temperature of the secondary battery. By making the cooling system universal, the patent eliminates the need for a separate battery temperature control system, thereby reducing overall system complexity while maintaining effective temperature control of the secondary battery

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

2Object-affected harmful factors

If coolant circulation is stopped when the secondary battery temperature exceeds a threshold, then overheating is prevented, but temperature control precision decreases

Engineering Contradiction:
Improveoverheating preventionVSAvoidtemperature control precision
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent employs dynamic temperature control by continuously monitoring the secondary battery temperature and adjusting coolant circulation accordingly. The switching valve dynamically redirects coolant flow between the fuel cell and secondary battery based on real-time temperature readings, enabling precise temperature control rather than simple on/off circulation control

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates temperature sensors that continuously monitor the secondary battery temperature and provide feedback to the control unit. This feedback mechanism enables the control unit to make real-time adjustments to the switching valve, ensuring precise temperature control and preventing overheating through continuous regulation rather than passive circulation stopping

Inventive Principle:
Principle #23Feedback

3Temperature

If the switching valve directs coolant to the bypass flow passage, then the secondary battery is heated, but the fuel cell cooling efficiency decreases

Engineering Contradiction:
Improvesecondary battery temperatureVSAvoidfuel cell cooling efficiency
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The switching valve dynamically adjusts coolant flow distribution between the fuel cell and secondary battery based on real-time temperature requirements. When the secondary battery requires heating, the valve directs coolant to the bypass flow passage; when the fuel cell requires cooling, the valve redirects coolant to the fuel cell. This dynamic adjustment minimizes energy loss by ensuring the cooling system responds to the immediate thermal needs of each component

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system periodically monitors temperatures of both the fuel cell and secondary battery, and the switching valve periodically adjusts coolant flow distribution accordingly. This periodic action ensures that both components receive appropriate thermal management over time, balancing the heating needs of the secondary battery with the cooling needs of the fuel cell to minimize overall energy loss

Inventive Principle:
Principle #19Periodic action

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 maintains the secondary battery within an optimal temperature range, enhancing its performance by heating it when low and preventing overheating, thus improving the overall power delivery in fuel-cell vehicles.

Implementation Method 1

a radiator (15) that cools the coolant

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

a radiator (15) that cools the coolant

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

a circulation flow passage (12) that causes a coolant to circulate between the fuel cell (2) and the radiator (15)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

a switching valve (14) that switches a flow direction of the coolant between a radiator side and a bypass flow passage side

Methodology Applied
Scientific EffectValve flow control: Valve

Data Source

PatentEP3474368B1Fuel-cell vehicle with thermal management of fuel cell and secondary battery
Publication Date: 2020.07.22 TOYOTA JIDOSHA KK
  • EP3474368B1 patent drawingFigure 1
  • EP3474368B1 patent drawingFigure 2
  • EP3474368B1 patent drawingFigure 3

AI summary

A fuel-cell vehicle includes a fuel cell (2) and a secondary battery (3). A circulation flow passage (12) causes a coolant to circulate between the fuel cell (2) and a radiator (15). A bypass flow passage (16) passes through the secondary battery (3). One end of the bypass flow passage (16) is connected to an upstream side of the radiator (15) and the other end thereof is connected to a downstream side of the radiator (15) of the circulation flow passage (12). A controller (30) switches a switching valve (14) such that the coolant flows to the radiator side when a coolant temperature is higher than a predetermined temperature threshold value, and switches the switching valve (14) such that the coolant flows to the bypass flow passage side when the coolant temperature is lower than the temperature threshold value.