Automatic changeover mode in an HVAC controller with reversible deadband enforcement

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Solution Overview

Problem

HVAC controllers lack efficient mechanisms to maintain a minimum deadband between heat and cool temperature set points, leading to inefficient operation when users adjust these settings, resulting in energy wastage and discomfort.

Innovation Solution

The HVAC controller enforces a minimum deadband by automatically adjusting the heat and cool temperature set points when they approach each other, ensuring that the deadband is maintained by tracking and reverting the settings to their original values when adjustments are made.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the user adjusts the HEAT temperature set point or COOL temperature set point freely, then the ease of operation is improved, but the minimum deadband between set points cannot be maintained, leading to energy wastage and inefficient operation

Engineering Contradiction:

Improveuser ability to adjust temperature set pointsVSAvoidenergy wastage due to violated deadband

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The controller continuously monitors the relationship between HEAT and COOL temperature set points and provides feedback adjustments. When a user adjusts one set point toward the other, the controller detects this change and automatically adjusts the opposing set point to maintain the minimum deadband, creating a closed-loop control system that prevents energy wastage while respecting user input

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs self-adjustment of temperature set points to maintain the minimum deadband requirement. When user input would violate the deadband, the controller autonomously modifies the appropriate set point without requiring user intervention, enabling the system to self-correct and prevent energy inefficiency

Inventive Principle:

Principle #25Self-service

2Adaptability or versatility

If the user adjusts one temperature set point toward the other, then the adaptability is improved, but the system reliability deteriorates when the minimum deadband is violated

Engineering Contradiction:

Improveuser ability to change temperature settingsVSAvoidsystem operation reliability when deadband is violated

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The controller proactively prevents deadband violation by automatically adjusting the opposing temperature set point before the minimum deadband can be compromised. This preliminary action ensures the system always operates within reliable parameters while still allowing user adaptability in temperature selection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The continuous monitoring and automatic adjustment mechanism provides real-time feedback to maintain the minimum deadband, ensuring system reliability is preserved regardless of user adjustments to temperature set points

Inventive Principle:

Principle #23Feedback

3Use of energy by moving object

If the controller enforces minimum deadband automatically, then the energy efficiency is improved, but the device complexity increases due to tracking and automatic adjustment mechanisms

Engineering Contradiction:

ImproveHVAC system energy efficiencyVSAvoidcontroller complexity for deadband enforcement

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The controller performs self-adjustment of temperature set points to maintain the minimum deadband, eliminating the need for complex external control systems. The system monitors its own state and autonomously corrects set points, achieving energy efficiency through relatively simple internal logic

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The deadband enforcement functionality is integrated directly into the existing temperature control system, combining multiple functions (temperature regulation, deadband maintenance, user input handling) into a single unified controller, thereby reducing overall system complexity

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If the controller tracks and reverts set point adjustments to maintain deadband, then the system reliability is improved, but the loss of time occurs during automatic adjustments

Engineering Contradiction:

Improvedeadband maintenance reliabilityVSAvoidtime for automatic set point adjustments

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The controller performs deadband maintenance adjustments instantaneously or near-instantaneously through automated electronic control, skipping the time-consuming manual adjustment process. The system rapidly detects violations and applies corrections, minimizing time loss while maintaining reliability

Inventive Principle:

Principle #21Skipping (Rushing through)

Data Source

PatentUS10907854B2Automatic changeover mode in an HVAC controller with reversible deadband enforcement

Publication Date: 2021.02.02 HONEYWELL INTERNATIONAL INC

AI summary

An HVAC controller is configured to automatically change between a HEAT mode and a COOL mode in accordance with a sensed temperature in the building structure, a HEAT temperature set point and a COOL temperature set point. The user is allowed to adjust the HEAT temperature set point and the COOL temperature set point, with the HVAC controller automatically adjusting one of the set points in response to the user making a change to the other of the other of the set points that violates a minimum deadband. If the user readjusts the user-adjusted set point in a way that no longer violates the minimum deadband, the HVAC controller will adjust the other set point back towards its previous setting.