HVAC Dual-Fan Control Using Variable and Constant Speed Motors
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Solution Overview
Problem
Existing HVAC systems are inefficient and resource-intensive due to the use of multiple motor drives or a single fan motor to control airflow, which increases implementation costs and physical footprint.
Innovation Solution
The implementation of an HVAC unit with a combination of a variable speed fan and a constant speed fan, controlled by a controller that determines target airflow and activates the fans accordingly, reducing the need for high-power motor drives and minimizing component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple motor drives or a single high-power fan motor is used to control airflow, then effective airflow control is achieved, but implementation costs increase and physical footprint enlarges
Solution Approach 1:
The patent divides the airflow control function into two separate fan motors: a first fan motor for providing base airflow and a second fan motor for providing additional airflow when needed. This segmentation allows each motor to be smaller and less complex than a single high-power motor, reducing overall device complexity and physical footprint while maintaining effective airflow control capability.
2Ease of operation
If a single variable speed fan motor is used to control airflow, then airflow adjustment is achieved, but motor losses and resource consumption increase
Solution Approach 1:
The patent segments the airflow provision into two constant-speed fan motors operating in parallel. The first fan motor operates continuously to provide base airflow, while the second fan motor operates only when additional airflow is required. This approach eliminates the need for a variable speed drive and associated motor losses, reducing energy consumption and resource usage while maintaining airflow adjustability through on/off control of the second motor.
3Adaptability or versatility
If multiple motor drives are used to control airflow, then airflow control flexibility is improved, but the number of components and manufacturing steps increase
Solution Approach 1:
The patent uses two constant-speed fan motors instead of one variable-speed motor drive. This segmentation provides airflow control flexibility by allowing the second motor to be activated when additional airflow is needed, while simplifying manufacturing by eliminating the need for complex variable speed drive electronics and reducing the number of manufacturing steps associated with assembling and calibrating a single high-power motor drive 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
This configuration reduces implementation costs and improves operational efficiency by allowing for a smaller physical footprint, fewer manufacturing steps, and less motor loss, while maintaining effective airflow control.
Implementation Method 1
a first exhaust fan capable of operating at variable speeds
Implementation Method 2
a second constant-speed fan
Data Source
AI summary
The present disclosure relates to a heating, ventilating, and air conditioning (HVAC) unit configured to supply conditioned air to a conditioned space. The HVAC unit includes a first exhaust fan capable of operating at variable speeds and a second constant-speed fan. The HVAC unit also includes a controller configured to determine a target airflow to be provided to the conditioned space, cause actuation of the first exhaust fan at a variable fan speed when the target airflow is greater than zero, and cause actuation of the second exhaust fan when the target airflow is greater than an airflow threshold.