Variable Pressure Cap Using Shape Memory Polymer
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Solution Overview
Problem
Existing pressure caps for vehicle cooling systems maintain high pressure for extended periods, leading to reduced durability of components like surge tanks, radiators, and hoses, resulting in frequent replacements and increased maintenance due to prolonged exposure to high pressure.
Innovation Solution
A pressure cap with a shape memory member, such as a shape memory polymer, that compresses the positive pressure spring in advance, maintaining low pressure below the boiling point of cooling water and switching to high pressure only when the water reaches boiling point, thereby reducing overall system pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure cap maintains high pressure in the cooling system, then the boiling point of cooling water is increased and overheating is prevented, but the durability of components (surge tank, radiator, hose) is reduced due to prolonged high pressure exposure
Solution Approach 1:
The pressure cap dynamically adjusts the opening pressure based on cooling water temperature. Below the boiling point, it maintains low opening pressure to reduce stress on components. Above the boiling point, it switches to high opening pressure to prevent overheating. This dynamic adjustment resolves the contradiction by making the pressure maintenance adaptive rather than static.
Solution Approach 2:
The pressure cap changes the pressure parameter according to temperature conditions. At temperatures below the boiling point, the opening pressure is maintained at a low level (e.g., 0.3 bar). When temperature exceeds the boiling point, the opening pressure increases to a high level (e.g., 0.7 bar). This parameter change strategy allows the system to optimize both component durability and overheating prevention.
2Reliability
If the pressure cap maintains high pressure continuously, then overheating protection is ensured, but frequent component replacement is required due to reduced durability
Solution Approach 1:
The pressure cap transitions from static high-pressure maintenance to dynamic pressure adjustment. It maintains low pressure during normal operating conditions (below boiling point) and only switches to high pressure when necessary (above boiling point). This reduces cumulative stress on components, extending their service life and reducing maintenance frequency while preserving overheating protection when needed.
Solution Approach 2:
The pressure cap applies high pressure only periodically or conditionally (when temperature exceeds boiling point) rather than continuously. During normal operation, it maintains low pressure. This periodic/conditional high-pressure action ensures overheating protection is available when needed while minimizing the total duration of high-stress exposure, thereby reducing component wear and maintenance requirements.
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 maintains the cooling system at a lower pressure, enhancing the durability of components and reducing the frequency of replacements, thus minimizing maintenance and operational losses.
Implementation Method 1
A pressure cap with a shape memory member, such as a shape memory polymer, that compresses the positive pressure spring in advance
Implementation Method 2
a shape memory member restored to the initial shape when reaching a predetermined temperature
Data Source
AI summary
A pressure cap structure for a cooling system having variable opening pressure, which is applied to a cooling system for circulating cooling water to radiate heat generated by an engine of a vehicle, and maintains the inside pressure of the cooling system in a predetermined range, the pressure cap may include a positive pressure spring mounted in a valve body, and operated to connect the cooling system to the outside when the pressure of the cooling system rises, and a shape memory member restored to the initial shape when reaching a predetermined temperature, and mounted between the positive pressure spring and a spring guard supporting the positive pressure spring.