Centrifugal Blower Rotor Guide Surface and Blade Alignment
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Solution Overview
Problem
Conventional centrifugal blowers experience insufficient reduction of air flow separation near the shroud ring, leading to increased noise, and the assembly of turbo fans and outer rotors can result in axial misalignment, obstructing air flow and increasing noise further.
Innovation Solution
The centrifugal blower design includes a turbo fan with blades inclined such that one side portion is positioned ahead of the other side portion in the rotation direction, and an outer rotor with a rotor guide surface aligned to guide air flow into inter-blade channels, ensuring proper alignment and reducing obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the blade is designed with a two-dimensional shape where all one side portions overlap with other side portions in the rotation axis direction, then the manufacturing is simplified, but air flow separation occurs near the shroud ring leading to increased noise
Solution Approach 1:
The blade is designed with a three-dimensional shape where one side portions are positioned ahead of other side portions in the rotation direction, creating a staggered configuration. This dimensional change from a two-dimensional overlapping structure to a three-dimensional staggered structure prevents air flow separation near the shroud ring while maintaining manufacturing feasibility through integral molding processes.
2Length of moving object
If the outer rotor is disposed inside the cylinder portion and fixed to the fan, then the thickness of the centrifugal blower is reduced, but axial misalignment occurs during assembly causing air flow obstruction and increased noise
Solution Approach 1:
A positioning protrusion on the outer rotor fits into a positioning groove on the turbo fan, serving as a mechanical intermediary that ensures precise axial alignment during assembly. This positioning mechanism prevents misalignment between the outer rotor and turbo fan, eliminating air flow obstruction while maintaining the reduced thickness design.
3Length of moving object
If the outer rotor surface is positioned lower than the upper end of the cylinder portion to reduce thickness, then the blower becomes thinner, but air flow collides with the cylinder portion side surface causing noise
Solution Approach 1:
The outer rotor surface is positioned at different heights at different radial locations: at the radial inner side, it is positioned lower to reduce overall thickness, while at the radial outer side, it is positioned higher to prevent air flow collision with the cylinder portion. This local quality variation allows the design to achieve both thickness reduction and noise prevention.
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 design effectively reduces air flow separation near the shroud ring, decreases noise, and allows for a thinner blower configuration by ensuring accurate positioning of the turbo fan and outer rotor during assembly, thereby enhancing air flow guidance.
Implementation Method 1
the occurrence of separation of the air flow from the blade is insufficiently reduced in the vicinity of a shroud ring
Implementation Method 2
a rotor guide surface that guides an air flow toward an inter-blade flow channel provided between adjacent blades
Data Source
AI summary
A centrifugal blower includes an outer rotor, and a turbo fan. The turbo fan includes blades, an other end plate, and a cylinder portion. The cylinder portion is located inside the other end plate, and is fixed to the outer rotor. A surface of the outer rotor configures a rotor guide surface that guides an air flow toward a channel provided between adjacent blades. Each blade has a leading edge side portion located radially inside the cylinder portion. An outer end portion of the rotor guide surface in the radial direction is located at the same position in the axial direction as a one side cylinder end portion of the cylinder portion in the axial direction, in a state where a rotor contact portion of the outer rotor and a blade contact portion of the leading edge side portion are in contact with each other.