Rotating Inlet Rotor for Cross Flow Fan Noise Reduction
Solution Overview
Problem
Agricultural combine harvesters face limitations in increasing air flow without enhancing noise levels, as conventional methods to boost fan performance result in increased noise, and space constraints prevent larger fan diameters, while existing noise-reducing solutions compromise air flow uniformity.
Innovation Solution
A transverse fan assembly with a rotating, bladed inlet rotor arranged in a chevron-like configuration, situated at the plenum inlet opening edge, which increases air flow while reducing noise by minimizing the interaction between fan blades and the inlet edge, using a cooperating fan blade orientation and plenum design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fan tip speed is increased to boost air flow, then air flow is improved, but noise level increases
Solution Approach 1:
The inlet edge is made rotatable about the fan axis, transforming a static structure into a dynamic one. The inlet edge rotates synchronously with the fan blades, maintaining optimal positioning relative to the blades throughout the rotation cycle. This dynamic adjustment reduces noise by preventing continuous instantaneous contact between blade tips and the inlet edge, while still allowing the fan to operate at high tip speeds for increased air flow.
2Productivity
If fan diameter is increased to boost air flow, then air flow is improved, but space requirements increase
Solution Approach 1:
The invention changes the operational parameters of the existing fan by introducing a rotatable inlet edge that optimizes the interaction between the fan blades and inlet structure. This allows the fan to achieve enhanced air flow performance without increasing its physical diameter, effectively changing the performance characteristics rather than the physical dimensions.
3Productivity
If fan rotational speed is increased to boost air flow, then air flow is improved, but noise level increases
Solution Approach 1:
The rotatable inlet edge creates a dynamic system where the inlet structure rotates with the fan blades. This synchronous rotation ensures that the inlet edge is always positioned optimally relative to the passing blades, reducing turbulence and noise even at high rotational speeds. The dynamic positioning allows the fan to operate at higher speeds for increased air flow without the proportional increase in noise that would occur with a static inlet edge.
4Object-generated harmful factors
If angled blades are used to reduce noise, then noise is reduced, but air flow uniformity deteriorates
Solution Approach 1:
The inlet structure is segmented into multiple discrete inlet edges positioned at different angular locations around the fan axis. Each inlet edge can be independently positioned to optimize its interaction with the passing fan blades. This segmentation allows different portions of the inlet to serve different functions: some edges are positioned to reduce noise by minimizing blade-edge contact, while others are positioned to maintain uniform air flow distribution across the fan outlet.
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
The solution provides a durable, low-maintenance, and cost-effective transverse fan assembly that enhances air flow to higher capacity combines without increasing noise levels, ensuring efficient and uniform air distribution across the fan outlet.
Implementation Method 1
Agricultural combine harvesters face limitations in increasing air flow without enhancing noise levels, as conventional methods to boost fan performance result in increased noise
Implementation Method 2
A transverse fan assembly with a rotating, bladed inlet rotor arranged in a chevron-like configuration, situated at the plenum inlet opening edge, which increases air flow while reducing noise
Data Source
Figure 1
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AI summary
A transverse fan assembly (10) that includes a fan (42) rotatably disposed in an air plenum (44) for drawing air through an inlet opening (62) and drivingly forcing air from an outlet opening (66) defined by the air plenum (44), the inlet opening (62) having an elongate, bladed, inlet rotor (70) oriented on a rotational axis (74) parallel to the fan (42), extending the length of the fan (42), and positioned proximate to the fan periphery to increase air flow and improve air flow distribution from the outlet (66) of the air plenum (44) along the length of the fan (42) while generating less noise.