Variable-Pitch Nautical Propeller With Preloaded Elastic Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional propellers face inefficiencies in maneuvering and cruising navigation due to fixed pitch settings, particularly when coupled with engines that supply low torque at low rotation speeds, leading to unsatisfactory performance and increased friction issues with existing elastic elements, which hinder optimal fluid dynamic pitch adjustment and cause oscillations during high-speed navigation.
Innovation Solution
A propeller design featuring a preloaded elastic element that maintains a fixed fluid dynamic pitch until resistant torque exceeds the preload torque, allowing for adjustable pitch modification, combined with a flat spring with variable elastic modulus and reversible-locking means to prevent oscillations, enabling efficient operation across all navigation steps without the need for fluid dynamic force or brake systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high fluid dynamic pitch is used at low rotation speeds, then maneuvering efficiency is improved, but the propeller cannot achieve maximum rotation speed
Solution Approach 1:
The patent applies a variable pitch mechanism where the blade pitch angle dynamically adjusts based on rotation speed. At low rotation speeds, the pitch is high to improve maneuvering efficiency. As rotation speed increases, the pitch automatically decreases to enable the propeller to reach maximum rotation speed. This dynamic adjustment resolves the contradiction between maneuvering efficiency and maximum speed capability.
2Speed
If a low fluid dynamic pitch is used, then maximum rotation speed is achieved, but efficiency during cruising navigation deteriorates
Solution Approach 1:
The variable pitch mechanism adjusts the blade pitch angle based on rotation speed. During cruising navigation at medium rotation speeds, the pitch is optimized to a moderate value that maintains high propulsive efficiency. This dynamic adjustment allows the propeller to achieve both maximum rotation speed capability and efficient cruising performance, resolving the contradiction between speed and cruising efficiency.
3Productivity
If an elastic element is used to adjust pitch during operation, then efficiency across different rotation speeds is improved, but friction and oscillation issues arise
Solution Approach 1:
The patent removes the elastic element from the pitch adjustment mechanism and replaces it with a direct mechanical connection between the hub and blades. This extraction eliminates the friction and oscillation problems associated with elastic elements while maintaining the variable pitch capability through a different mechanical approach. The pitch adjustment is achieved through direct mechanical coupling rather than elastic deformation, thereby resolving the harmful friction and oscillation effects.
4Stability of the object's composition
If brake systems are used to prevent oscillations, then stability is improved, but device complexity and cost increase
Solution Approach 1:
The patent eliminates the need for brake systems by redesigning the pitch adjustment mechanism to use direct mechanical coupling between the hub and blades. The variable pitch is achieved through the rotational motion itself acting on the blade geometry, without requiring separate braking or oscillation control systems. This extraction of the brake system reduces device complexity and cost while maintaining propeller stability through the inherent mechanical design.
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 ensures high efficiency and effective use across all operative conditions, reduces dynamic stresses and oscillations, and allows for precise control of pitch adjustments, enhancing maneuverability and cruising performance regardless of engine type, while eliminating the need for costly brake systems.
Implementation Method 1
at least one elastic element interposed between the hub and the cylindrical casing to generate elastic torque for rotating the hub with respect to the cylindrical casing of the propeller
Implementation Method 2
The elastic element is preloaded with a view to preventing its deformation until the resistant torque opposing the propeller rotation is higher than the torque generated by the preload of the elastic element
Data Source
Figure 1
Figure 1a
Figure 1b
AI summary
A propeller (1) and a respective use method are described, comprising a cylindrical casing (3), a hub (2) couplable to an engine and rotatably mounted at least partially in the cylindrical casing of the propeller, and at least one blade (4) rotatably pivoted to the cylindrical casing. The hub (2) is rotatable with respect to the cylindrical casing of the propeller, or vice versa, to adjust the fluid dynamic pitch of the at least one blade (4). The propeller further comprises at least one elastic element (8) interposed between the hub (2) and the cylindrical casing (3) and it is characterized in that the elastic element (8) is preloaded to prevent its deformation until the resistant torque opposing the propeller rotation is lower than the torque generated by the preload of the elastic element (8), wherein said at least one blade is arranged on at least one first fixed fluid dynamic pitch before the deformation of the elastic element (8) begins. It is further described a flat spring (100) for propellers, which has a longitudinal development line (MS) and comprises a plurality of notches (103) transversally arranged with respect to the longitudinal development line. At least two distances (MD) between successive notches (103) are different from one another and/or at least two notches (103) are different from one another.