Thermostat Housing Flow Path for Stable Coolant Temperature Sensing
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Solution Overview
Problem
Conventional thermostat devices experience reduced sensitivity and responsivity due to coolant flow dynamics that affect the thermo-element, leading to unstable control valve operations and hunting.
Innovation Solution
The thermostat device incorporates a housing design with an annular groove and slope configuration that redirects cooled coolant away from the thermo-element, improving temperature sensitivity and responsivity by preventing coolant from the radiator side from directly impacting the thermo-element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooled coolant flows directly past the thermo-element to improve cooling efficiency, then cooling performance is improved, but temperature sensitivity and responsivity of the thermo-element deteriorate
Solution Approach 1:
The housing internal flow path is segmented into distinct regions: a first flow path for cooled coolant that bypasses the thermo-element, and a second flow path for heated coolant that flows past the thermo-element. This segmentation allows the cooled coolant to provide efficient cooling while preventing it from directly impacting the thermo-element's temperature sensing accuracy.
Solution Approach 2:
Different regions of the housing are assigned different flow characteristics: the region near the first flow inlet is designed to guide cooled coolant away from the thermo-element, while the region near the second flow inlet allows heated coolant to flow past the thermo-element. This local differentiation ensures optimal temperature sensitivity at the thermo-element location while maintaining overall cooling efficiency.
2Temperature
If coolant mixing occurs in the housing to improve temperature regulation, then temperature control is improved, but control valve stability deteriorates due to hunting
Solution Approach 1:
The housing separates the mixing process from the thermo-element sensing zone. Cooled coolant from the first flow inlet and heated coolant from the second flow inlet are directed to mix in a designated mixing region, while the thermo-element is positioned to sense temperatures before mixing occurs. This prevents the mixed coolant's turbulent flow from affecting control valve stability.
Solution Approach 2:
The housing structure acts as an intermediary that mediates between the cooled coolant flow and the thermo-element. By providing a specific flow path configuration with guiding surfaces, the housing ensures that cooled coolant does not directly interact with the thermo-element, thereby maintaining stable control valve operation while still achieving temperature regulation through controlled mixing.
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 design enhances temperature sensitivity and stability of the control valve operation, preventing hunting and ensuring consistent coolant temperature control.
Implementation Method 1
a thermo-element incorporating a thermal expansion body (wax) expanding and contracting by sensing a temperature change in the coolant flowing through the circulation flow passage
Implementation Method 2
functions to maintain the coolant at a predetermined temperature by opening and closing a control valve (valve body) by volume change caused by expansion and contraction of the thermal expansion body
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Provided is a thermostat device with which temperature sensitivity and responsiveness can be improved, and which resolves the problem of instability of operation of a control valve, and the problem of hunting. The thermostat device is provided with: a housing (3) including a first inflow port (5a) for accepting cooling liquid from a radiator, a second inflow port (4b) for accepting cooling liquid that has passed through a bypass passage, and an outflow port (4c) for cooling liquid obtained by mixing the cooling liquids; a thermoelement (2a) which is accommodated in the housing (3), and which moves in an axial direction in accordance with the temperature of the cooling liquid from the second inflow port (4b); a control valve (2c) which controls an introduction quantity of the cooling liquid from the first inflow port in conjunction with the movement of the thermoelement (2a); a valve seat (5c) which is formed in a tip end portion of an annular projecting portion (5d) formed projecting in a movement axis direction of the thermoelement (2a) in the housing (3), and against which the control valve (2c) abuts when the valve is closed; and an annular groove (3d) configured by means of an annular gap which is continuous in a circumferential direction, and which is applied to the outside of the valve seat (5c).