Dual Mode Thermal Actuator With Active Heater
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Solution Overview
Problem
Existing thermally actuated flow-control valves with wax-filled actuators lack the ability for active control of valve position, relying solely on temperature changes, which can be unreliable if the passive actuation fails or requires quick adjustments.
Innovation Solution
A dual mode thermal actuator with two wax-filled chambers, one actively heated by an electric heater and the other passively responding to temperature changes, allowing for supplemental or backup extension of the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a passive wax-filled actuator is used for temperature-sensitive flow control, then the system operates without external energy requirements, but the valve position cannot be quickly adjusted or actively controlled
Solution Approach 1:
The patent combines a passive wax-filled actuator with an active heating element (resistance heater) into a single integrated actuator assembly. The passive wax chamber responds to ambient temperature changes, while the active heater provides controlled thermal input when electrical power is supplied. This merging allows the system to achieve both passive temperature compensation and active valve position control without requiring separate actuators, thus improving ease of operation while limiting the increase in device complexity.
2Reliability
If a passive wax-filled actuator is used, then the device is self-contained and reliable, but it requires external energy for quick adjustments or backup control
Solution Approach 1:
The patent creates a dynamic actuator system that can operate in multiple modes: passive mode using only the wax-filled chamber for slow, automatic temperature compensation, and active mode where the resistance heater provides rapid thermal response for quick adjustments or backup control. The system dynamically switches between these modes based on control needs, maintaining reliability through the passive component while enabling energy-consuming active control when required.
3Speed
If the actuator is extended passively by wax expansion, then no external energy is required, but the response time is slow and cannot meet quick adjustment requirements
Solution Approach 1:
The patent changes the thermal input parameter to the wax actuator by introducing an electrically heated element that can rapidly increase the temperature of the wax chamber when electrical power is supplied. This active heating capability fundamentally changes the response time characteristic of the actuator, enabling quick adjustments from seconds to minutes, while the system can still operate in energy-efficient passive mode when rapid response is not required.
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
Enables intentional and active control of the actuator's length, providing reliable operation by combining passive and active modes, ensuring consistent fluid flow management.
Implementation Method 1
The first cup includes a resistance heater that can be selectively heated by connection to electrical power
Implementation Method 2
The wax expands in volume as the wax becomes a liquid, generating a force that is directed into the bore of the guide, and moves the piston away from the chamber
Implementation Method 3
two wax-filled chambers arranged so that expansion of the wax in either chamber acts to extend the actuator. One wax filled chamber is provided with an electric heater to heat and expand the wax in response to a control signal, while the other wax filled chamber is arranged to passively respond to a temperature
Data Source
AI summary
A dual mode thermal actuator (hereafter “the actuator”) includes a first cup defining a first chamber filled with thermally-responsive wax and a second cup defining a second chamber filled with thermally-responsive wax. A piston is disposed between the first and second cups. A first guide is received by the first cup. The first guide surrounds the piston and extends axially away from the first cup. A second guide is received by the second cup. The second guide surrounds the piston and extends axially away from the second cup. Expansion of the wax in the first chamber or expansion of the wax in the second chamber causes the actuator to go from a retracted position to an extended position. Expansion of the wax in the first chamber and expansion of the wax in the second chamber also causes the actuator to go from the retracted position to the extended position.