Marine Propeller Pitch Control With a Preloaded Flat Spring
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Solution Overview
Problem
Conventional propellers face inefficiencies in maneuvering and cruising navigation due to fixed or variable pitch designs that do not adapt well to various engine types, particularly those with low torque values at low rotation speeds, leading to unsatisfactory performance and increased friction issues with existing elastic elements.
Innovation Solution
A propeller with a preloaded elastic element that maintains a fixed fluid dynamic pitch during initial operation, adjusting only when resistant torque exceeds the preload, combined with a flat spring design featuring variable elastic modulus and notch arrangements to minimize friction and optimize deformation, allowing for efficient pitch modification and reduced dynamic stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high fluid dynamic pitch is used to guarantee high efficiency at medium rotation speeds (cruising navigation), then efficiency in the second operation step is improved, but efficiency in the first operation step (maneuvering) deteriorates due to excessive pitch at low rotation speeds
Solution Approach 1:
The patent applies a preloaded elastic element that enables the propeller blades to dynamically adjust their pitch angle based on operating conditions. During maneuvering at low rotation speeds, the preload keeps the pitch fixed at a lower value for responsiveness. During cruising at medium speeds, the elastic element deforms under torque load, automatically increasing the pitch to optimize efficiency, thus resolving the contradiction between maneuverability and cruising efficiency
Solution Approach 2:
The invention changes the pitch parameter dynamically through the deformation of the preloaded elastic element. The pitch angle is not fixed but varies with the torque applied to the propeller shaft, transitioning from a lower pitch value during maneuvering to a higher pitch value during cruising navigation, thereby optimizing performance across different operational phases
2Productivity
If a low fluid dynamic pitch is used to improve responsiveness in maneuvering, then efficiency in the first operation step is improved, but efficiency in the second operation step (cruising navigation) deteriorates due to insufficient pitch at medium rotation speeds
Solution Approach 1:
The preloaded elastic element creates a dynamic pitch adjustment system that adapts to different operational phases. During maneuvering, the low pitch provides quick responsiveness. As the propeller enters cruising mode and torque increases, the elastic element deforms to increase the pitch angle, thereby maintaining high efficiency across both maneuvering and cruising operations
Solution Approach 2:
The elastic element is preloaded during assembly to establish an initial pitch configuration optimized for maneuvering. This preliminary setting ensures good responsiveness at low speeds, while the design anticipates the need for pitch increase during cruising by allowing deformation under operational torque loads
3Productivity
If a fixed-pitch propeller is designed for maximum rotation speed efficiency, then efficiency in the third operation step is improved, but efficiency in the second operation step (cruising navigation) deteriorates
Solution Approach 1:
The invention transforms the fixed-pitch design into a dynamic pitch system using a preloaded elastic element. The pitch angle automatically adjusts based on the torque applied: maintaining a configuration suitable for cruising at medium speeds, and transitioning to a configuration optimized for maximum speed at high rotation speeds, thereby resolving the efficiency trade-off between different operational phases
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 enables high efficiency across all operational steps, independent of engine type, with improved maneuverability and reduced friction, allowing for effective use in both low-speed and high-speed navigation without the need for additional locking mechanisms, thus enhancing propeller performance and reliability.
Implementation Method 1
a preloaded elastic element that maintains a fixed fluid dynamic pitch during initial operation, adjusting only when resistant torque exceeds the preload
Implementation Method 2
a flat spring design featuring variable elastic modulus and notch arrangements to minimize friction and optimize deformation
Implementation Method 3
notch arrangements to minimize friction and optimize deformation
Data Source
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.