Adjustable Fan Wheel With Planetary Gearing for Low-Stress Blade Switching
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Solution Overview
Problem
Existing fan wheels with adjustable fan wings face challenges in avoiding high component loads when changing the wing angle, which can lead to mechanical stress and inefficiency.
Innovation Solution
The fan wheel design incorporates a planetary gear system with a freewheel mechanism, allowing for adjustable wing angles without reversing the rotation direction, thereby reducing component loads and ensuring smooth transitions between air production and cleaning modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fan blades are adjusted by inertial rotation and aerodynamic loading as in prior art, then the blade position can be changed, but high component loads and mechanical stress occur during the adjustment process
Solution Approach 1:
A planetary gear mechanism is introduced as an intermediary between the drive shaft and the fan blades. The planetary gear includes a sun gear connected to the drive shaft, planet gears mounted on a planet carrier, and a ring gear connected to the hub. This gear system mediates the force transmission during blade adjustment, distributing loads across multiple gear teeth and reducing peak component loads compared to direct inertial rotation methods.
Solution Approach 2:
The system utilizes controlled dynamic adjustment where the planet carrier can rotate relative to the sun gear to change blade angles. The adjustment is performed by rotating the planet carrier through a limited angle while the fan wheel rotates, allowing continuous blade position changes during operation. This dynamic adjustment mechanism avoids the high impulse loads associated with abrupt position changes.
2Adaptability or versatility
If the fan wheel reverses rotation direction to change conveying direction as in prior art, then the conveying direction can be switched, but the mechanism becomes more complex and requires bidirectional drive capability
Solution Approach 1:
Instead of reversing the rotation direction of the fan wheel to change conveying direction, the invention inverts the approach by adjusting the blade angles while maintaining unidirectional rotation. The planetary gear mechanism allows the planet carrier to rotate in the opposite direction relative to the sun gear, which changes the blade attack angle and thus the conveying direction, while the drive shaft continues to rotate in only one direction.
Solution Approach 2:
The planetary gear mechanism serves multiple functions: it transmits drive torque from the drive shaft to the hub, enables blade angle adjustment during rotation, and allows conveying direction switching through planet carrier rotation. This multi-functionality eliminates the need for separate bidirectional drive mechanisms or reversal systems.
3Speed
If high speed rotation is used for rapid blade adjustment, then the adjustment speed increases, but high impulse loads are generated at end positions
Solution Approach 1:
The planetary gear mechanism provides inherent cushioning before the blade adjustment reaches end positions. As the planet carrier approaches the limits of its rotation range, the gear teeth gradually engage and disengage, distributing the impulse loads across multiple teeth and reducing peak stresses. The ring gear and sun gear configuration creates a mechanical buffer that prevents sudden stops and reduces shock loads at the extremes of blade adjustment.
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 component loads and avoids high mechanical stress during wing angle changes, enabling efficient operation in both air production and cleaning modes without the need for directional rotation reversals.
Implementation Method 1
The fan wheel (1) comprises a planetary gear (8) with a sun gear (9), planet gears (10) on a planet carrier (11) and a ring gear (12)
Implementation Method 2
The hub (4) is connected to the drive flange (6) via a limited freewheel (14, 15)
Implementation Method 3
a reduction in speed, which occurs with a minimum deceleration, moves the fan blades from the conveying position to the cleaning position
Data Source
Figure 1
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AI summary
The invention relates to a fan wheel comprising fan blades which are mounted in a hub so as to pivot about their blade longitudinal axes, wherein the fan wheel has a drive flange connected to the hub via a limited freewheel, said fan wheel being provided with a planetary gearing between the drive flange and the fan blades. A sun gear of the planetary gearing, which is connected to the drive flange in a rotationally fixed manner, and the drive flange are arranged on axially opposite end faces of the fan wheel.