Hybrid Vehicle Common Coolant Circuit Temperature Management

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Solution Overview

Problem

Existing motor vehicles with hybrid drive systems require separate cooling circuits for internal combustion engines and electric motors, leading to inefficiencies in space, mass, and energy management, as well as increased CO2 emissions.

Innovation Solution

A common coolant circuit is used to cool both the internal combustion engine and electric machine, with temperature settings adjusted based on the vehicle's operational mode, allowing for efficient cooling and power delivery while minimizing CO2 emissions and optimizing battery capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate cooling circuits are used for internal combustion engine and electric motor, then each machine can be cooled independently, but the system complexity, space requirements, and mass increase

Engineering Contradiction:
Improveindependent cooling capabilityVSAvoidcooling system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines separate cooling circuits for the internal combustion engine and electric motor into a single common cooling circuit. This merging reduces system complexity and the number of components while maintaining the ability to cool both machines effectively through a unified coolant flow path.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The common cooling circuit is designed to serve multiple functions: cooling the internal combustion engine, cooling the electric motor, and potentially cooling other vehicle components. This multi-functional approach eliminates the need for separate dedicated cooling systems for each machine.

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

2Reliability

If separate cooling circuits are used for internal combustion engine and electric motor, then each machine has dedicated cooling, but space and mass requirements increase

Engineering Contradiction:
Improvecooling effectivenessVSAvoidcooling system mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

By merging separate cooling circuits into a common cooling circuit, the patent reduces the total mass of cooling system components including pumps, radiators, and coolant reservoirs. The shared infrastructure eliminates redundant elements that would increase overall system weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The universal cooling circuit design allows a single system to cool multiple heat-generating components, thereby reducing the total mass compared to having separate dedicated cooling systems for each component.

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

3Reliability

If high coolant temperature is used for internal combustion engine, then engine cooling is effective, but electric motor cooling efficiency decreases

Engineering Contradiction:
Improveengine cooling efficiencyVSAvoidcoolant temperature for electric motor
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent segments the common cooling circuit into different zones or paths that can operate at different temperatures. This allows the coolant to be cooled to a lower temperature suitable for the electric motor while maintaining higher temperature operation for the internal combustion engine, effectively resolving the temperature conflict between the two machines.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the cooling system are designed with local quality variations, including temperature-specific cooling zones and selective coolant flow paths. This enables optimized cooling temperatures for each machine based on their specific thermal requirements.

Inventive Principle:
Principle #3Local quality

4Productivity

If dynamic temperature adjustment is implemented, then cooling efficiency is optimized, but control system complexity increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoidtemperature control complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic temperature adjustment capabilities in the common cooling circuit, allowing the system to adapt coolant flow and temperature based on real-time operational conditions. This enables optimized cooling efficiency for different driving modes and thermal loads.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The dynamic temperature control system incorporates feedback mechanisms that monitor thermal conditions of the internal combustion engine and electric motor, automatically adjusting coolant flow rates and temperatures to maintain optimal cooling efficiency without requiring complex manual intervention.

Inventive Principle:
Principle #23Feedback

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 approach reduces the complexity and resource requirements for cooling systems, enhances power density, and improves the electric range by dynamically managing coolant temperatures across different operational modes, thereby optimizing the performance and efficiency of hybrid vehicles.

Implementation Method 1

Both machines are cooled with one coolant via a common coolant circuit

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

coolant first being conveyed to the electric machine and from the electric machine to the internal combustion engine

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

the coolant to be conveyed by a pump of the coolant circuit is conveyed from the cooler first to the power electronics

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentEP3214285B1Method for operating a motor vehicle
Publication Date: 2021.04.07 AUDI AG
  • EP3214285B1 patent drawingFigure 1

AI summary

The invention relates to a method for operating a motor vehicle comprising a machine designed as an internal combustion engine (6) and a machine designed as an electric machine (4), wherein the motor vehicle is driven by at least one of these two machines, wherein both machines are cooled by a coolant via a common coolant circuit (10), wherein the internal combustion engine (6) is connected downstream of the electric machine (4), wherein coolant is first conveyed to the electric machine (4) and from the electric machine (4) to the internal combustion engine (6), wherein a first temperature is set for the coolant when the motor vehicle is driven solely by the internal combustion engine (6), and wherein a second temperature is set for the coolant when the motor vehicle is driven by the electric machine (4) and the internal combustion engine (6).where the second temperature is lower than the first temperature.