HVAC actuator with inductive position sensing

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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 system utilizing an inductive sensor and conductive target, where the inductive sensor detects changes in inductance as the conductive target aligns with it, allowing for accurate position determination and control of the actuator even when unpowered, using a stored relationship between inductance and position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If resistive potentiometers are used to measure actuator position, then position feedback is obtained, but the physical connection to the gear train causes wear and degradation

Engineering Contradiction:

Improveposition feedback accuracyVSAvoidcomponent durability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical contact-based resistive potentiometer with a magnetic field-based inductive sensing system. The inductive sensor detects changes in inductance caused by the movement of a conductive target attached to the drive device, eliminating the need for physical contact between the sensing component and the moving parts. This substitution of mechanical sensing with electromagnetic sensing resolves the wear and degradation issue while maintaining position measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If Hall effect sensors are used to measure actuator position, then position tracking is achieved, but power is required to monitor feedback which limits tracking when unpowered

Engineering Contradiction:

Improveposition tracking accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The inductive sensing system is designed to be passive from the perspective of the conductive target. The target does not require any power source or active electronics; it simply responds to the magnetic field generated by the inductive sensor through changes in its electromagnetic properties. This allows the system to detect position changes even when the actuator is unpowered, as the sensor can detect the physical position of the conductive target without requiring power to the target itself.

Inventive Principle:

Principle #25Self-service

3Loss of information

If Hall effect sensors are used for position measurement, then position feedback is obtained, but the system cannot track position changes when the actuator is not powered

Engineering Contradiction:

Improveposition information continuityVSAvoidpower requirement

Core Design Contradiction:

Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent replaces the active electronic Hall effect sensor system with a passive inductive sensing system. The inductive sensor generates a magnetic field that interacts with the conductive target, and the resulting inductance changes are detected without requiring power to the target or complex electronic circuits. This allows continuous position tracking regardless of the actuator's power state, as the system relies on electromagnetic induction rather than powered electronic sensing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 continuous tracking of actuator position regardless of power state, improving reliability and maintenance in HVAC systems.

Implementation Method 1

an inductive sensor, a conductive target, and a controller. The drive device is coupled to a movable HVAC component for driving the movable HVAC component between multiple positions. The conductive target is coupled to the drive device such that a portion of the conductive target aligns with the inductive sensor

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

Each of the multiple different portions has a different inductance. The controller receives a signal from the inductive sensor indicating an observed inductance of the portion of the conductive target aligned with the inductive sensor

Methodology Applied

Scientific EffectEddy Currents: Eddy Currents

Data Source

PatentUS10571304B2HVAC actuator with inductive position sensing

Publication Date: 2020.02.25 TYCO FIRE & SECURITY GMBH

AI summary

An actuator in a HVAC system includes an inductive sensor, a conductive target, and a controller. The conductive target has multiple different portions that become aligned with the inductive sensor as a position of the actuator changes. Each of the multiple different portions have a different inductance. The controller receives a signal from the inductive sensor indicating an observed inductance of the portion of the conductive target aligned with the inductive sensor. The controller uses a stored relationship between the observed inductance and the position of the actuator to determine the position of the actuator based on the observed inductance. The controller operates the actuator to change the position of the actuator based on the determined position.