Tandem Thermal Actuator for Extended Stroke in Thermostats
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Solution Overview
Problem
Current wax-based thermal actuators in thermostat assemblies for internal combustion engines face challenges with leakage under high pressure and limited stroke extension, particularly with annular type seals, and require significant design and production investments to extend the diaphragm type seals for longer strokes.
Innovation Solution
A thermostat assembly with a tandem thermal actuator configuration, featuring two thermal elements positioned back to back within a bushing capsule, allowing for a longer stroke and improved heat transfer, along with protrusions for fluid flow and a spring-activated valve mechanism, enhances the operational range and efficiency of the thermal actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If annular type seal is used to extend the stroke of thermal actuator, then the stroke is extended, but leaking problems occur under high pressure
Solution Approach 1:
The single thermal actuator is segmented into two separate thermal actuators with diaphragm-type seals, each providing a portion of the total required stroke. This segmentation allows each seal to remain compact and reliable while achieving a longer combined stroke through the series arrangement of the two actuators.
2Length of moving object
If diaphragm type seal length is extended to achieve long stroke, then the stroke is extended, but seal and vessel design and production investments increase significantly
Solution Approach 1:
Instead of extending a single diaphragm seal and vessel, the design segments the actuator into two separate units, each with standard-length diaphragm seals. This avoids the need for custom-designed long seals and vessels, thereby reducing design and production complexity while achieving the required stroke length.
Solution Approach 2:
The two thermal actuators are arranged in a nested or series configuration within the housing, with one actuator positioned inside or adjacent to the other. This nesting approach allows both actuators to occupy a compact space while providing the combined stroke length needed for the application.
3Length of moving object
If annular type seal is used for long stroke, then the stroke is extended, but leaking problems occur under high pressure
Solution Approach 1:
The actuator system is divided into two separate thermal actuators, each with its own diaphragm-type seal. This segmentation allows each seal to operate within its optimal pressure containment range while collectively providing the extended stroke needed, thereby eliminating the leakage problems associated with single long-stroke annular seals.
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 tandem thermal actuator design achieves a two-fold longer stroke and reduced response time, addressing leakage issues and enabling efficient operation under high pressure conditions without the need for extensive design modifications, while maintaining leak-proof performance.
Implementation Method 1
at least two thermal elements (22) are positioned back to back inside said bushing capsule (21)... Each thermal element (22) comprises a cover (23) and a piston (24) which extend from inside to outside of said cover (23). A thermally sensitive compound captured inside the thermal elements (22) expands or shrinks according to the temperature and said thermally sensitive compound triggers piston (24) movement.
Implementation Method 2
bushing capsule (21) having a hollowed cylindrical geometry... made of a heat conductive material, preferably metal, so that proper heat transfer from coolant to thermal elements (22) is improved.
Implementation Method 3
Said tandem thermal actuator (2) acts upon a valve (3) so that two times longer stroke is provided compared with prior art under the same conditions. In a similar manner, by means of the subject matter product, the same stroke can be obtained at lower temperatures compared with prior art under the same conditions.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A thermal assembly (1) developed for use in the cooling circuits of internal combustion engines and comprising a thermal actuator (2) having at least one thermal element (22) comprising a thermally sensitive component encapsulated inside a vessel, a cover (23) positioned on said vessel and a piston (24) provided in a manner movable outwardly from the inner section of said cover (23), characterized by comprising a bushing capsule (21) wherein at least two thermal elements (22) are placed back to back in opposite directions and which at least partially encircles the thermal elements (22).