Dual Heat Exchanger ATF Cooling for Fuel-Efficient Vehicles
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Solution Overview
Problem
Conventional cooling devices for vehicles with torque converterless transmissions face challenges in maintaining the temperature of lubricating fluid for friction engagement elements, leading to excessive temperature drops that increase friction loss in the internal combustion engine, thereby reducing fuel efficiency.
Innovation Solution
A cooling device with dual heat exchangers and adjustable flow rate controllers for the lubricating fluid circuit, allowing independent adjustment of flow rates through each exchanger based on temperature sensors, ensuring suitable temperature maintenance for the lubricating fluid, thereby preventing excessive temperature drops or rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the conventional cooling device uses two heat exchangers to cool the ATF, then the cooling effectiveness of the ATF is improved, but the temperature of the first coolant drops excessively, increasing friction loss in the internal combustion engine and reducing fuel efficiency
Solution Approach 1:
The patent introduces a thermostat valve that dynamically adjusts the flow rate of ATF through the second heat exchanger based on temperature conditions. When ATF temperature is low (normal travel), the valve reduces flow through the second heat exchanger to prevent excessive cooling of the first coolant. When ATF temperature is high (off-road or towing), the valve increases flow to enhance cooling. This dynamic adjustment resolves the contradiction between maintaining ATF temperature and preserving fuel efficiency.
Solution Approach 2:
The patent changes the flow rate parameter of ATF through the second heat exchanger based on operating conditions. By adjusting this parameter, the system optimizes heat exchange efficiency while preventing excessive temperature drop of the first coolant, thereby resolving the energy loss issue while maintaining ATF cooling effectiveness when needed.
2Temperature
If the thermostat valve increases flow rate through the second heat exchanger to cool the ATF, then the ATF temperature is reduced, but the first coolant temperature drops excessively, increasing friction loss in the internal combustion engine
Solution Approach 1:
The thermostat valve operates based on feedback from ATF temperature sensors. When the ATF temperature is low, the valve receives feedback to close or reduce opening, thereby reducing flow through the second heat exchanger. This prevents excessive heat extraction from the first coolant, avoiding the harmful effect of increased friction loss in the internal combustion engine.
Solution Approach 2:
The thermostat valve performs preliminary anti-action by preventing the ATF from becoming too cold in the first place. During normal travel conditions, the valve maintains a closed or partially closed state, anticipating that excessive cooling would harm the first coolant temperature and subsequently increase friction loss. This preventive approach avoids the harmful effect before it occurs.
3Reliability
If the conventional cooling device maintains ATF at suitable temperature, then the friction engagement elements are cooled effectively, but the first coolant temperature drops during normal travel, reducing fuel efficiency
Solution Approach 1:
The system dynamically adjusts ATF flow rate through the second heat exchanger based on vehicle operating conditions. During normal travel, the thermostat valve reduces flow to minimize impact on first coolant temperature, preserving fuel efficiency. During off-road or towing conditions, the valve increases flow to ensure adequate cooling of friction engagement elements. This dynamic behavior resolves the contradiction between reliability and energy efficiency.
Solution Approach 2:
The patent applies different cooling strategies to different operating conditions through the thermostat valve. Instead of uniformly cooling the ATF in all conditions, the system provides localized cooling only when necessary (off-road or towing), while maintaining fuel efficiency during normal travel. This selective approach resolves the contradiction between cooling effectiveness and energy consumption.
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
The solution effectively maintains the lubricating fluid temperature, reducing friction loss in the internal combustion engine and improving fuel efficiency by optimizing heat exchange according to operational conditions, including cold starts, normal travel, and off-road or towing scenarios.
Implementation Method 1
a first heat exchanger configured to exchange heat between the fluid and the first coolant
Implementation Method 2
a second heat exchanger that is arranged in series with the first heat exchanger, and configured to exchange heat between the fluid and the second coolant
Data Source
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AI summary
A cooling device of a vehicle is provided, which includes a transmission, a first coolant circuit where a first coolant which cools the internal combustion engine circulates, a second coolant circuit independent from the first coolant circuit, where a second coolant which cools the electric drive system circulates, and a fluid circuit where fluid which lubricates and cools friction engagement elements in the transmission circulates. The fluid circuit includes a first heat exchanger which exchanges heat between the fluid and the first coolant, a second heat exchanger in-series with the first heat exchanger which exchanges heat between the fluid and the second coolant, a first adjuster which changes a flow rate of the fluid passing through the first heat exchanger, and a second adjuster which changes a flow rate of the fluid passing through the second heat exchanger.