Adjustable-Pitch HVAC Fan Assembly for Airflow Control Without VFDs
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Solution Overview
Problem
Conventional HVAC system fans are unable to efficiently adjust air flow rates in response to changes in operational parameters, leading to reduced operational efficiency and increased costs due to the need for expensive variable frequency drives (VFDs).
Innovation Solution
A fan assembly with a pitch adjuster mechanism that allows fan blades to change pitch angles without altering the operational speed of the fan, using an actuator to adjust the pitch of the blades relative to the hub, enabling adjustable air flow rates without the need for VFDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional fans are used with fixed pitch blades, then the fan structure is simple and reliable, but the air flow rate cannot be adjusted efficiently in response to operational parameter changes
Solution Approach 1:
The fan blade pitch is made dynamically adjustable through a pitch adjuster mechanism that allows the blade angle to change relative to the hub. The actuator can move the pitch adjuster axially along the motor shaft, which in turn rotates the fan blade about its spanwise axis to change the pitch angle, enabling the fan to adapt to different operational conditions.
Solution Approach 2:
The invention changes the geometric parameter of the fan blade (pitch angle) to control air flow rate. By varying the pitch angle through the pitch adjuster mechanism, the fan can efficiently adjust air flow without changing rotational speed, providing adaptability to different operational requirements.
2Adaptability or versatility
If variable frequency drives (VFDs) are used to adjust air flow rates, then the air flow can be controlled, but the production and maintenance costs increase
Solution Approach 1:
The invention extracts the air flow control function from the motor speed control system (VFD) and implements it through a mechanical pitch adjustment mechanism. By changing the blade pitch angle independently of the motor speed, the system achieves air flow control without requiring expensive VFDs, thereby reducing production and maintenance costs.
Solution Approach 2:
The pitch adjuster mechanism provides a cost-effective alternative to expensive electronic control systems like VFDs. The mechanical mechanism uses simple components (actuator, pitch adjuster, and blade connection) that are cheaper to manufacture and maintain compared to electronic variable frequency drives.
3Productivity
If the fan blade pitch is fixed, then the manufacturing process is simple, but the operational efficiency decreases when operational parameters change
Solution Approach 1:
The fan blade pitch is made dynamically adjustable through a pitch adjuster mechanism that allows the blade angle to change relative to the hub. The actuator can move the pitch adjuster axially along the motor shaft, which in turn rotates the fan blade about its spanwise axis to change the pitch angle, enabling the fan to adapt to different operational conditions.
Solution Approach 2:
The pitch adjuster mechanism serves multiple functions: it adjusts the blade pitch angle to optimize performance under different operational conditions, maintains efficient operation across varying loads, and does so without complicating the overall manufacturing process significantly. The mechanism integrates with the existing motor shaft and hub structure.
Data Source
AI summary
A fan assembly for a heating, ventilation, and/or air conditioning (HVAC) unit includes a hub having a fan blade extending therefrom. The fan assembly includes a fan pitch adjuster configured to engage the fan blade and to adjust a pitch of the fan blade relative to the hub in response to movement of the fan pitch adjuster relative to the hub. The fan assembly also includes a motor shaft coupled to the fan pitch adjuster and to the hub, where the motor shaft is configured to drive rotation of the fan pitch adjuster and the hub. The fan assembly further includes an actuator coupled to the fan pitch adjuster and configured to axially move the fan pitch adjuster along the motor shaft and relative to the hub to adjust the pitch of the fan blade.