Engine Cooling Bypass Circuit for Rapid Warm-Up
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Solution Overview
Problem
Engine startability and fuel efficiency are compromised in cold conditions due to engine cooling systems that fail to rapidly warm up engines and powertrain components, leading to prolonged engine temperature rise and differing cooling requirements for components like EGR and SCR systems.
Innovation Solution
An engine cooling system with a bypass circuit that prevents coolant from being cooled in the radiator during engine warm-up, utilizing a low-temperature thermostat and parallel circuits with heat exchangers to direct coolant flow for rapid heating of critical components, and a flow controlling device to manage coolant distribution efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the radiator is bypassed during cold start to prevent coolant cooling, then engine warm-up speed is improved, but temperature control for other components (EGR heat exchanger, transmission cooler, SCR device) deteriorates
Solution Approach 1:
The cooling system is divided into multiple independent circuits: a first coolant circuit connecting the engine to the radiator, and a second coolant circuit connecting the radiator to the engine, with additional parallel circuits for EGR heat exchanger, transmission cooler, and SCR device. This segmentation allows different temperature control strategies for different components simultaneously.
Solution Approach 2:
A controllable valve is introduced to dynamically switch coolant flow paths between the first and second circuits. During cold start, the valve directs coolant through the bypass to prioritize engine warm-up; during normal operation, the valve redirects coolant through the radiator to enable component cooling, providing adaptive temperature control.
2Reliability
If the thermostat is kept closed during engine warm-up to prevent radiator cooling, then engine startability is improved, but cooling of powertrain components deteriorates
Solution Approach 1:
The system separates the engine cooling path from the component cooling path by creating parallel circuits. The first circuit handles engine-to-radiator cooling while the second circuit handles radiator-to-engine cooling, with additional branches for powertrain components. This allows the thermostat to remain closed for engine warm-up while still enabling coolant flow to components through alternative paths.
Solution Approach 2:
The controllable valve acts as an intermediary that manages coolant distribution between different circuits. It enables the thermostat to maintain its temperature control function for the engine while allowing coolant to be diverted to powertrain components through the second circuit and parallel branches.
3Temperature
If coolant flows through the radiator during cold start to cool components, then component cooling is improved, but engine warm-up time increases
Solution Approach 1:
The controllable valve dynamically adjusts coolant flow distribution based on operating conditions. During cold start, it closes the path through the radiator for the engine circuit to minimize warm-up time, while simultaneously opening paths in the second circuit and parallel branches to allow coolant flow to powertrain components, achieving both goals through dynamic flow management.
Solution Approach 2:
By segmenting the cooling system into multiple independent circuits with separate flow paths, the system allows the engine circuit to bypass the radiator during cold start while enabling component cooling through alternative circuits, eliminating the need to choose between engine warm-up and component cooling.
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 solution enables faster engine and powertrain component warm-up, improving startability and fuel efficiency, while ensuring appropriate temperature control for components like EGR and SCR systems, reducing NOx emissions and preventing freezing.
Implementation Method 1
the cooling water that is heated by the engine is returned through the cooling water return passage to the radiator, where the cooling water is cooled down due to heat transfer between the cooling water and the open air
Implementation Method 2
the cooling water that is cooled down by a radiator is supplied to the water cooled engine through a cooling water supply passage, and the cooling water that is heated by the engine is returned through the cooling water return passage to the radiator, where the cooling water is cooled down due to heat transfer between the cooling water and the open air
Implementation Method 3
each parallel circuit is provided with a heat exchanger that is arranged for selectively heating or cooling a powertrain component
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The invention relates to an engine cooling system in a vehicle, which cooling system comprises a first coolant circuit (21) and a second coolant circuit (22) connecting the engine to a radiator (31). A thermostat (32) is arranged in the first coolant circuit (21) and is arranged to be closed during engine warm-up, to prevent flow through the first coolant circuit (21). The cooling system further comprises a bypass circuit (24) connecting the thermostat (32) to the second coolant circuit (22) and at least one parallel circuit (25, 26, 27). Each parallel circuit (25, 26, 27) is connected to the second coolant circuit (22) upstream of the bypass circuit (24), wherein a partial coolant flow is directed from the bypass circuit (24) and upstream through the second coolant circuit (22) into the at least one parallel circuit (25, 26, 27) during engine warm-up. The invention further relates to a method for controlling such an engine cooling system