Centrifugal Impeller Cover Plate Circular Mounting Holes
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Solution Overview
Problem
Conventional centrifugal impellers in blowers, such as those used in hand dryers and vacuum cleaners, tend to fail due to stress cracking at high motor speeds above 33,000 RPM, leading to reduced lifespan.
Innovation Solution
The centrifugal impeller design features blade mounting holes on the cover plate with a circular or regular polygon shape, reducing stress concentration and increasing the strength of the cover plate, with a blade assembly fixed between the base and cover plates using rivet connections and strategically placed mounting holes and protrusions for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rectangular blade mounting holes are used in the cover plate, then the manufacturing is simple, but the cover plate strength is insufficient and cracks occur at high speeds above 33,000 RPM
Solution Approach 1:
The patent applies curvature by changing the blade mounting hole shape from rectangular to circular. The circular shape eliminates sharp corners that act as stress concentration points, thereby preventing crack initiation and improving cover plate strength under high-speed rotation without significantly complicating the manufacturing process.
2Productivity
If the motor speed is increased above 33,000 RPM to improve productivity, then the air output increases, but the centrifugal impeller breaks due to stress cracking
Solution Approach 1:
By changing the mounting hole shape from rectangular to circular, the patent eliminates stress concentration at corners, preventing crack formation that would lead to impeller failure at high speeds, thus enabling reliable operation above 33,000 RPM for increased productivity.
Solution Approach 2:
The patent changes the geometric parameter of the mounting hole from rectangular to circular shape, which fundamentally alters the stress distribution pattern in the cover plate, allowing the structure to withstand the increased centrifugal forces generated at high rotational speeds.
3Stability of the object's composition
If multiple mounting holes and protrusions are used to enhance blade assembly stability, then the structural integrity improves, but the device complexity increases
Solution Approach 1:
The circular mounting holes provide uniform stress distribution around the entire perimeter of the hole, maximizing structural stability with a simple geometric change that does not require additional mounting features or complex assembly procedures.
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 prevents failure under high-speed rotation, significantly prolonging the lifespan of the blower by distributing stress more evenly and enhancing structural integrity.
Implementation Method 1
blade mounting holes on the cover plate with a circular or regular polygon shape, reducing stress concentration and increasing the strength of the cover plate
Implementation Method 2
A hand drier and a vacuum cleaner typically employ a centrifugal blower with a central air inlet and a peripheral air outlet
Data Source
AI summary
A centrifugal impeller for a blower has a base plate, a cover plate, and a plurality of curved blades mounted between the base plate and the cover plate. The base plate and the cover plate have blade mounting portions including a plurality of mounting holes. Cover plate mounting portions and base plate mounting portions project from each blade and engage with the mounting holes of the cover plate and base plate, respectively. The mounting holes of the cover plate include first mounting holes arranged outwardly from a central region. The first mounting holes have a circular shape. The cover plate mounting portions of each blade include first mounting protrusions engaged with the first mounting holes.