Centrifugal Blower Hub Guide Portions for Noise and Flow Control
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Solution Overview
Problem
In existing centrifugal blowers for air conditioners, the sub-flow's flow path resistance is increased, leading to a reduction in air volume and potential deterioration of fan motor cooling efficiency, along with noise issues during flow merging.
Innovation Solution
A centrifugal blower design featuring a rotary shaft, an impeller with a main plate, shroud, and vane portions, where the hub has guide portions with outward protrusions and air holes, and peripheral surface configurations that reduce sub-flow resistance and promote smooth merging with the main flow, thereby enhancing flow rate and noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the flow path resistance of the sub-flow is increased to abruptly bend the flow direction, then the noise accompanying the merging of sub-flow and main flow is suppressed, but the air volume of the sub-flow is reduced and cooling efficiency deteriorates
Solution Approach 1:
The hub is divided into multiple guide portions arranged in the rotation direction, with each guide portion having air holes. This segmentation allows the sub-flow to be divided into multiple smaller streams that merge gradually with the main flow, reducing noise while maintaining air volume.
Solution Approach 2:
The guide portions protrude outward in the radial direction, creating a three-dimensional structure that guides the sub-flow. This radial arrangement allows the sub-flow to change direction more smoothly by utilizing the radial dimension, reducing both noise and resistance.
2Temperature
If the flow path resistance is increased to cool the fan motor, then the cooling efficiency is improved, but the air volume is reduced
Solution Approach 1:
The guide portions and air holes are designed in advance to pre-cool the fan motor by directing sub-flow through the hub structure. This preliminary cooling action occurs before the sub-flow merges with the main flow, ensuring adequate cooling without requiring high flow path resistance.
3Temperature
If the sub-flow is directed radially inward to cool the fan motor, then the cooling function is achieved, but noise is generated during merging with main flow
Solution Approach 1:
The guide portions act as intermediary structures between the sub-flow and main flow. They gradually guide the radially inward sub-flow to merge with the radially outward main flow, mediating the interaction to reduce noise while maintaining the cooling function.
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 design effectively secures a sufficient sub-flow rate while minimizing noise, improving the cooling efficiency of the fan motor by reducing flow path resistance and diffusing the sub-flow for smoother merging with the main flow.
Implementation Method 1
a sub-flow that is directed radially inward on an upper side of the main plate is generated to cool a fan motor
Implementation Method 2
a centrifugal blower that suctions air upward from below and blows out the air by diverting the flow outward in a radial direction
Data Source
AI summary
A centrifugal blower includes: a drive portion having a rotary shaft that rotates about a rotation axis; and an impeller configured to be rotated forward in a rotation direction around the rotation axis by the drive portion, in which the impeller includes a main plate, a shroud facing the main plate in the axial direction, and a plurality of vane portions connecting the main plate and the shroud, the main plate has a hub that covers the drive portion and has a plurality of guide portions protruding outward in the radial direction and arranged in the rotation direction, air holes are formed in the plurality of guide portions, and each outer peripheral surfaces of the plurality of guide portions has a pair of peripheral surface portions located on front and rear sides in the rotation direction with respect to the air hole and facing outward in the radial direction.