Variable Pitch Fan With Mechanical Rack-and-Pinion Blade Adjustment
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Solution Overview
Problem
Existing variable pitch fans for cooling systems, such as those in tractors, are complex and expensive due to the use of hydraulic or pneumatic fluids for actuation, which leads to leakage issues and high maintenance costs.
Innovation Solution
A mechanical driving element, comprising a rack and a rotatable pinion, is used to adjust the blade pitch, eliminating the need for hydraulic or pneumatic fluids and simplifying the system, with a transmission device featuring discrete bodies like spheres or rollers to transmit linear motion efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic or pneumatic fluid is used to actuate the adjusting device, then the blade pitch can be varied, but the structure becomes complicated and expensive due to leakage risks and sealing requirements
Solution Approach 1:
The patent replaces the hydraulic or pneumatic fluid actuation system with a purely mechanical actuation system. The mechanical driving element directly transmits force through mechanical contact (pushing the discrete bodies) to rotate the blades, eliminating the need for fluid seals and hydraulic/pneumatic components. This substitution resolves the contradiction by maintaining actuation functionality while removing the complexity and reliability issues associated with fluid sealing systems.
2Ease of manufacture
If hydraulic or pneumatic fluid is used for actuation, then blade pitch adjustment is achieved, but manufacturing and assembly costs increase due to sealing systems
Solution Approach 1:
The patent eliminates sealing systems by replacing hydraulic/pneumatic actuation with direct mechanical actuation. The mechanical driving element pushes discrete bodies (rollers or balls) that engage with the blade mounting structure, creating a seal-free actuation mechanism. This resolves the contradiction by removing the costly and unreliable sealing components while maintaining effective blade pitch control.
3Reliability
If rotating sealing elements are used in hydraulic systems, then fluid leakage is prevented, but maintenance frequency increases due to rapid wear
Solution Approach 1:
The patent replaces the hydraulic system with rotating sealing elements with a mechanical pushing system. The mechanical driving element directly pushes the discrete bodies without requiring any rotating seals. This eliminates wear-prone sealing components entirely, resolving the contradiction by achieving reliable fluid containment (through mechanical contact) while eliminating the maintenance burden of worn seals.
4Ease of operation
If a mechanical driving element with rack and pinion is used, then blade pitch control is achieved, but the transmission path requires discrete bodies to navigate curved paths
Solution Approach 1:
The patent introduces discrete bodies (rollers or balls) as intermediary elements between the mechanical driving element and the blade mounting structure. These discrete bodies roll along a curved guide path, translating the linear motion of the mechanical driver into rotational motion of the blades. This intermediary mechanism resolves the contradiction by enabling complex motion transformation while keeping individual components simple and maintenance-free.
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 solution reduces manufacturing and assembly costs, enhances reliability, and allows for easy maintenance, while enabling precise control of air flow rates by varying blade pitch without the need for complex sealing systems.
Implementation Method 1
The transmission device comprises a plurality of discrete bodies, particularly rolling bodies such as spheres or rollers, arranged inside a guide interposed between the actuator and the mechanical driving element
Implementation Method 2
the mechanical driving element comprises a rack and the driven element comprises a rotatable element having a toothed portion, particularly a pinion
Data Source
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AI summary
A variable pitch fan is provided, which comprises a plurality of blades (2), a supporting device (3) for supporting the blades (2), a rotation device (18) for rotating the supporting device (3)around a rotation axis (X), so that the blades (2) rotate with the supporting device (3) to control an air flow, and an adjusting device for adjusting a pitch of the blades by tilting each blade (2) around a respective tilt axis (Z), the adjusting device comprising a driven element (4) fixed relative to a blade (2). The adjusting device further comprises a mechanical driving element (5) supported by the supporting device (3) so as to rotate with the supporting device (3), the mechanical driving element (5)being linearly displaceable relative to the supporting device (3) and being coupled to the driven element (4) so that a linear motion of the mechanical driving element (5) is converted into a rotary motion of the driven element (4) around the tilt axis (Z).