Multi-blade fan with variable outlet angles
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Solution Overview
Problem
Conventional multi-blade fans with bellmouth-shaped inlets struggle to maintain constant air volume control due to limited differences in rotation numbers at varying pressures, resulting in inefficient fan operation.
Innovation Solution
A multi-blade fan design featuring a spirally-shaped casing with a bellmouth-shaped inlet and outlet, where the main plate has a smaller diameter than the blades, and the outlet angles of the blades are sequentially changed along the axis, allowing for increased differences in rotation numbers at low and high pressures, facilitating constant air volume control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional multi-blade fans use bellmouth-shaped inlets with fixed blade angles, then the structure is simple, but the difference in rotation numbers at low and high pressure is small, making air volume control difficult
Solution Approach 1:
The patent applies the dynamics principle by changing the blade outlet angles from fixed to variable along the axis direction. The outlet angles are designed to be sequentially changed in the axis direction, creating different effective angles at different pressures. This dynamic geometric variation enables the fan to achieve larger differences in rotation numbers between low and high pressure conditions, thereby improving air volume control capability without requiring complex external control mechanisms.
Solution Approach 2:
The patent applies the local quality principle by creating different outlet angles at different locations along the blade axis. The outlet angle varies locally along the axis direction, with different sections having different angles optimized for different pressure conditions. This local differentiation allows the blade to perform differently at various radial positions, increasing the rotation number difference between pressure conditions and enabling better air volume control.
2Productivity
If conventional multi-blade fans have fixed blade outlet angles, then manufacturing is simple, but fan efficiency is poor and rotation number difference is small
Solution Approach 1:
The patent applies the dynamics principle by designing outlet angles that vary dynamically along the axis direction rather than being fixed. This sequential change in outlet angles creates optimal aerodynamic conditions at different pressures, significantly improving fan efficiency. The manufacturing complexity is managed by forming these gradual angle variations during the blade molding process, making the design feasible for production.
Solution Approach 2:
The patent applies the parameter changes principle by systematically varying the outlet angle parameter along the axis direction. Instead of using a single fixed angle, the outlet angle is changed as a continuous or discrete parameter along the blade length. This parameter variation optimizes the blade performance across different operating conditions, achieving higher fan efficiency while maintaining manufacturing feasibility through standardized molding techniques.
3Measurement precision
If conventional fans detect rotation number for control, then control is possible, but the small difference in rotation numbers at different pressures limits control effectiveness
Solution Approach 1:
The patent applies the parameter changes principle by modifying the blade geometric parameters (outlet angles) to create larger variations in rotation numbers at different pressures. By sequentially changing outlet angles along the axis, the system generates more distinct rotation number signals for the same detection mechanism, thereby improving control precision without changing the detection method itself.
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 enhances fan efficiency by increasing the difference in rotation numbers between low and high pressure conditions, enabling effective control of air volume and improving overall performance.
Implementation Method 1
an electric motor disposed inside this casing
Implementation Method 2
a spirally-shaped casing having a bellmouth-shaped inlet and an outlet at one side
Data Source
AI summary
A multi-blade fan including a spirally-shaped casing having an inlet and an outlet; an electric motor disposed inside the casing; a main plate provided perpendicular to a rotation axis of the electric motor and having a ventilation hole; first blades disposed at a side of the inlet of the main plate; and second blades disposed at an opposite side of the inlet of the main plate. Herein, a diameter of the main plate is smaller than an outer diameter of the first and second blades and is larger than an inner diameter of them. Furthermore, an outlet angle of any one or both of the first blade and the second blade is sequentially changed in an axis direction.