HVAC Actuator Inductive Position Sensing for Unpowered Tracking
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Solution Overview
Problem
HVAC actuators face challenges with existing position sensing techniques, such as wear and degradation with resistive potentiometers and the need for power to operate Hall effect sensors, which limits position tracking when the actuator is unpowered.
Innovation Solution
An HVAC actuator utilizing an inductive sensor with a conductive target having multiple portions of different inductance, allowing position determination even when unpowered, by using a controller to interpret the inductance signal and adjust the actuator position accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistive potentiometers are used for position sensing, then position feedback is obtained, but wear and degradation occur due to physical connection with the gear train
Solution Approach 1:
The patent replaces the mechanical contact-based resistive potentiometer with a magnetic field-based inductive sensor. The inductive sensor detects position through changes in inductance caused by the relative position of a conductive target, eliminating mechanical contact and thereby preventing wear and degradation while maintaining position feedback accuracy.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the sensor and the moving component. The inductive sensor detects position through the magnetic field's interaction with the conductive target, rather than through direct mechanical contact, serving as a non-contact mediator that transfers position information without physical wear.
2Measurement precision
If Hall effect sensors are used for position sensing, then position tracking is achieved, but power consumption is required to monitor sensor feedback
Solution Approach 1:
The inductive sensor utilizes periodic oscillation of an AC bridge circuit to detect position changes. The oscillating magnetic field periodically interacts with the conductive target, allowing position detection through frequency or amplitude modulation of the oscillation, which consumes less power than continuous DC monitoring of Hall effect sensors.
Solution Approach 2:
The inductive sensing system is passive in the sense that it detects position changes through natural inductance variations in the magnetic field caused by the conductive target's position. The system does not require active power consumption to maintain a detection field, as the position information is derived from the inherent electromagnetic properties of the components.
3Measurement precision
If Hall effect sensors are used for position sensing, then position feedback is obtained, but position tracking fails when the actuator is unpowered
Solution Approach 1:
The patent replaces the active electronic Hall effect sensor with a passive inductive sensing system that detects position through electromagnetic induction. The inductive sensor can detect position changes even when the actuator is unpowered, as it responds to the physical position of the conductive target through magnetic field interaction without requiring active power consumption for detection.
Solution Approach 2:
The inductive sensor detects position by measuring changes in inductance parameter of the AC bridge circuit caused by the relative position of the conductive target. This parameter change approach allows the system to detect position through passive electromagnetic properties rather than active electronic signals, enabling operation under unpowered conditions.
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 inductive sensing system provides accurate and durable position feedback without physical wear, enabling actuator position tracking regardless of power state, enhancing reliability and longevity.
Implementation Method 1
an inductive sensor... Each of the multiple different portions has a different inductance. The controller is configured to receive a signal from the inductive sensor indicating an observed inductance
Data Source
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AI summary
An actuator (500) in a HVAC system includes an inductive sensor (526), a conductive target (532), and a controller (528). The conductive target (532) has multiple different portions that become aligned with the inductive sensor (526) as a position of the actuator (500) changes. Each of the multiple different portions have a different inductance. The controller (528) receives a signal from the inductive sensor (526) indicating an observed inductance of the portion of the conductive target (532) aligned with the inductive sensor (526). The controller (528) uses a stored relationship between the observed inductance and the position of the actuator (500) to determine the position of the actuator (500) based on the observed inductance. The controller (528) operates the actuator (500) to change the position of the actuator (500) based on the determined position.