Motor Vehicle Thermostat Reducing Temperature Cycling via Upstream Sensor
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Solution Overview
Problem
The existing cooling systems for motor vehicles with thermostats downstream of the engine experience significant temperature regulation delays and oscillations, particularly during cold temperature-rise processes, which can lead to engine damage due to the time it takes for the wax element in the thermal sensing device to react and adjust the flow of the cooling medium.
Innovation Solution
The thermostat is reconfigured to detect a partial flow of the mixed cooling medium from the radiator and bypass line, using a wax element with added substances like aluminium, copper, or carbon powder, and an electrical device to regulate the temperature, allowing quicker opening and closing of the valve, thus reducing temperature cycling and stabilizing engine operation without substantial reconfiguration of the existing cooling system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thermostat is situated downstream of the engine, then the wax element can detect the temperature of the cooling medium after it has circulated through the engine, but this causes a considerable delay in temperature feedback and results in temperature oscillations and hunting behavior
Solution Approach 1:
The cooling system is divided into two separate detection paths: one path uses the wax element to detect temperature at the engine outlet (downstream location), while another path uses a thermal sensor to detect temperature at the radiator outlet (upstream location). This segmentation allows each sensor to perform its function independently, with the thermal sensor providing immediate feedback for control while the wax element maintains reliable operation.
Solution Approach 2:
A thermal sensor acts as an intermediary device that detects the temperature of the cooling medium at the radiator outlet and provides this information to the control unit. This intermediary enables the control system to receive real-time temperature feedback without requiring the wax element to be positioned upstream, thus eliminating the feedback delay while maintaining the reliability advantages of the downstream wax element placement.
2Loss of time
If the thermostat is relocated upstream of the engine, then temperature feedback is immediate and oscillations are reduced, but this requires substantial reconfiguration of pipelines and engine components
Solution Approach 1:
A thermal sensor is installed as an intermediary device in the cooling medium flow path at the radiator outlet, serving as a non-intrusive temperature detection point that does not require modification of the engine or major pipeline reconfiguration. This intermediary provides immediate temperature feedback to the control unit while maintaining the existing downstream thermostat configuration.
Solution Approach 2:
The mechanical wax element temperature detection system is supplemented by an electrical/electronic thermal sensor system. The thermal sensor uses electrical resistance or other electrical properties to detect temperature, replacing the need for mechanical reconfiguration of the wax element position. This substitution allows temperature detection at the radiator outlet without moving the wax element or reconfiguring the cooling system architecture.
3Stability of the object's composition
If the wax element reacts slowly to temperature changes, then the thermostat provides stable operation, but this causes the cooling medium flow to be unregulated for extended periods, potentially leading to engine damage during cold temperature-rise processes
Solution Approach 1:
The control unit receives continuous temperature feedback from the thermal sensor at the radiator outlet and actively controls the thermostat valve position based on this real-time information. This feedback mechanism allows the system to respond immediately to temperature changes during cold start, preventing unregulated cold flow into the engine while maintaining stable operation during normal conditions. The control unit adjusts the valve position dynamically to regulate cooling medium flow according to actual engine temperature needs.
Solution Approach 2:
The passive mechanical wax element response system is enhanced by an active electronic control system. The thermal sensor detects temperature changes and sends signals to the control unit, which then actively adjusts the thermostat valve position. This electronic substitution for the slow mechanical wax element response enables rapid detection and correction of temperature deviations during cold start, providing engine protection without sacrificing the stability benefits of the wax element mechanism.
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 reduces temperature cycling, providing more stable engine operation by quickly regulating the cooling medium flow, preventing engine damage and maintaining system stability during cold temperature-rise processes without requiring extensive reconfiguration of the cooling system.
Implementation Method 1
The wax element is adapted to detecting the temperature of the cooling medium
Implementation Method 2
The wax in the sensing device reacts to the temperature of the cooling medium in such a way that it melts at a certain temperature, whereby it acts upon a valve... When the cooling medium has cooled to a lower temperature, the wax cools and solidifies
Implementation Method 3
using a wax element with added substances like aluminium, copper, or carbon powder... The composition and characteristics of the wax element are such that it reacts quickly
Data Source
Figure 1
Figure 2~3
Figure 4a~4b
AI summary
The present invention relates to a cooling system for a motor vehicle comprising a cooling circuit (2) for cooling the vehicle's engine (100) by means of a cooling medium flowing in the cooling circuit, which cooling system comprises a radiator (20) for cooling the cooling medium, means (30) for circulating the cooling medium in the cooling circuit, a thermostat device (40) comprising a valve device (52) situated downstream of the engine, and at least one thermal element (54) which is connected to the valve device and adapted to detecting the temperature of the cooling medium in order on the basis thereof to direct the cooling medium through the radiator (20) and/or through a bypass line (8) past the radiator, the at least one thermal element (54) being situated upstream of the engine (100). The invention relates also to a thermostat device for a cooling system of a motor vehicle. The invention relates also to a motor vehicle.