Battery-Powered HVAC Mesh Network with Sleep Current Fault Detection

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Solution Overview

Problem

Existing wireless HVAC systems face challenges with high installation costs due to hard-wiring, limited battery life in wireless devices requiring frequent maintenance, and increased manufacturing costs from designing multiple device versions with user interfaces.

Innovation Solution

The implementation of a method to detect excessive sleep current draw in battery-powered HVAC devices using a MOSFET and transistor circuitry, which generates an interrupt for the microcontroller to transmit a fault signal, and an energy-efficient mesh network method that minimizes end node wake times and delegates destination address determination to routers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If wireless HVAC devices use battery power to eliminate hard-wiring, then installation cost and complexity are reduced, but battery lifespan is limited and requires periodic maintenance

Engineering Contradiction:

Improveinstallation costVSAvoidbattery lifespan

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The system enables self-service through mesh networking where battery-powered devices communicate wirelessly without requiring hard-wired connections, eliminating installation complexity while maintaining operational reliability through intelligent power management and fault detection

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system implements feedback mechanisms through fault detection circuits that monitor battery status and sleep current draw, allowing the device to detect and report issues before they compromise reliability, enabling proactive maintenance

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If wireless devices enter sleep mode to conserve battery power, then energy consumption is reduced, but fault detection during sleep mode becomes difficult

Engineering Contradiction:

Improvepower consumptionVSAvoidfault detection

Core Design Contradiction:

Use of energy by moving objectVSDifficulty of detecting and measuring

Solution Approach 1:

The fault detection circuit performs preliminary monitoring of sleep current draw continuously, even when the microcontroller is in sleep mode, so that faults are detected before they can compromise battery life or system operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A dedicated fault detection circuit acts as an intermediary between the sleeping microcontroller and the battery, monitoring current draw and generating interrupt signals when faults are detected, enabling fault detection without waking the main processor

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If mesh network routers determine destination addresses to simplify end node design, then manufacturing cost is reduced, but network communication complexity increases

Engineering Contradiction:

Improvemanufacturing costVSAvoidnetwork communication

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The system segments network functionality by separating address determination (routing) functions performed by powered routers from simple data transmission functions performed by battery-powered end nodes, reducing end node complexity and manufacturing cost

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Powered routers in the mesh network perform multiple functions including address determination, data forwarding, and network management, allowing battery-powered end nodes to have simplified designs while maintaining full network capability through the multi-functional routers

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reduces power consumption, lowers manufacturing costs, and increases the reliability of wireless HVAC devices by extending battery life and simplifying device design while maintaining network reliability.

Implementation Method 1

measuring a voltage drop across a MOSFET device coupled in a forward-conducting orientation in series between the battery and the microcontroller

Methodology Applied

Scientific EffectVoltage drop measurement: Ohm's Law

Implementation Method 2

causing a transistor to conduct when the voltage drop exceeds a predetermined threshold to generate a first trigger signal

Methodology Applied

Scientific EffectTransistor conduction: Electrical Resistance

Data Source

PatentUS12213071B2Mesh routing of sleepy sensor data

Publication Date: 2025.01.28 TRANE INTERNATIONAL INC

AI summary

HVAC components having improved efficiency are described. In one embodiment, excessive sleep current draw in a battery-powered device having a microcontroller is detected by measuring a voltage drop across a MOSFET device coupled in a forward-conducting orientation in series between the battery and the microcontroller, causing a transistor to conduct when the voltage drop exceeds a predetermined threshold to generate a first trigger signal, integrating the first trigger signal to generate a second trigger signal, and generating an interrupt to the microcontroller. In another embodiment, a battery-saving method of operating an HVAC component includes maintaining the HVAC device in the sleep mode, receiving a user input to wake the device, transmitting a data request and returning the HVAC component to the sleep mode, waking up the HVAC device to poll an adjacent network node storing a cached response, displaying the response, and returning the HVAC device to sleep.