Blower Scroll Casing Recessed Portion Design
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Solution Overview
Problem
Conventional blowers with bellmouth-shaped inflow ports suffer from reduced air blowing efficiency due to the narrowing of the blowout port caused by the overlap of the impeller blades with the recessed portion, leading to increased turbulence and noise.
Innovation Solution
A blower design featuring a scroll casing with a bellmouth-shaped inflow and outflow port, a centrifugal impeller, and a motor, where the recessed portion is formed outside the lateral plate, creating an angle between the inner-circumferential flat portion and the recessed portion to generate small vortices that suppress airflow peeling and turbulence, preventing blade cutting and maintaining equal blowout and suction port heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the recessed portion is formed to suppress turbulence and noise, then the airflow stability is improved, but the blowout port is narrowed due to blade cutting, reducing air blowing efficiency
Solution Approach 1:
The recessed portion is repositioned from overlapping with the impeller blades to a location outside the lateral plate's radial extent. This spatial reconfiguration in the radial dimension eliminates blade cutting while preserving the turbulence-suppressing function of the recessed portion, thereby maintaining air blowing efficiency without sacrificing airflow stability.
Solution Approach 2:
The harmful effect of blade cutting is extracted and eliminated by separating the recessed portion from the impeller blade path. The recessed portion is extracted from the overlapping region and repositioned outside the lateral plate, removing the conflict between turbulence suppression and blade integrity while maintaining both functions independently.
2Stability of the object's composition
If the recessed portion is positioned to overlap with the impeller, then turbulence is suppressed, but the blades must be cut away causing blowout port narrowing
Solution Approach 1:
The recessed portion is repositioned in the radial dimension to lie outside the lateral plate's outer circumference, eliminating interference with impeller blades while maintaining its turbulence-suppressing function. This dimensional relocation preserves flow stability without compromising blowout port geometry.
Solution Approach 2:
The conflict between flow stability and blade geometry is resolved by extracting the recessed portion from the impeller overlap region. The recessed portion is repositioned outside the lateral plate, removing the harmful interaction while preserving the beneficial flow stabilization effect.
3Object-affected harmful factors
If the blowout port is narrowed due to blade cutting, then the recessed portion can be formed for turbulence suppression, but air blowing efficiency decreases
Solution Approach 1:
The recessed portion is repositioned radially outside the lateral plate, eliminating the need to cut impeller blades while maintaining turbulence suppression. This spatial reconfiguration preserves the full blowout port opening, thereby maintaining air blowing efficiency without sacrificing turbulence control.
Solution Approach 2:
The harmful effect of blade cutting is extracted and eliminated by relocating the recessed portion outside the impeller blade path. The recessed portion is positioned outside the lateral plate, removing the conflict between turbulence suppression and blade integrity while maintaining both functions independently.
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 turbulence and noise while maintaining air blowing efficiency by preventing airflow peeling and circulation, ensuring the blowout port is not narrowed, thus enhancing the blower's performance.
Implementation Method 1
extremely small vortices are generated from a connection portion between the inner-circumferential flat portion and the recessed portion inner surface
Implementation Method 2
peeling of the flow of air which flows into the blower along the bellmouth-shaped inflow port can be suppressed
Implementation Method 3
centrifugal impeller and a motor disposed in the inside of the scroll casing, the motor being configured to drive the centrifugal impeller
Data Source
AI summary
Blower includes: scroll casing, centrifugal impeller and a motor. Scroll casing includes: recessed portion formed outside lateral plate concentrically with centrifugal impeller; inner-circumferential flat portion disposed more on an inner circumference than recessed portion; and outer-circumferential flat portion disposed more on an outer circumference than recessed portion. Bottommost surface of recessed portion is disposed on a same plane as lateral plate end surface of lateral plate. Angle θa made by inner-circumferential flat portion and recessed portion inner surface of recessed portion on an inner circumference is set to a value which falls within a range of 90° or more to 120° or less.