Variable Pitch Propeller Drive with Eccentric Blade Actuation
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Solution Overview
Problem
Variable pitch propellers in ships do not efficiently maximize propulsion efficiency due to uniform pitch angles applied across all blades, leading to cavitation and hull vibrations, as the speed of fluid introduction is not uniform, causing uneven pitch angles that result in inefficient propulsive force generation.
Innovation Solution
A driving apparatus for variable pitch propellers with a pitch angle control system that adjusts each blade's pitch angle based on the rotational direction of the propeller shaft, using blade actuating shafts connected to eccentric stubs and a power converter that converts rotational motion into linear reciprocation, with guide pins and a guide ring to adjust pitch angles according to fluid speed, ensuring optimal pitch angles are maintained from the uppermost to lowermost end of the propeller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform pitch angle is applied to all blades, then manufacturing and control are simplified, but propulsion efficiency deteriorates due to cavitation and hull vibrations caused by non-uniform fluid speed
Solution Approach 1:
The propeller blades are divided into multiple segments along the rotational direction, with each segment having independently adjustable pitch angles. This allows different pitch angles to be applied to different blades according to the non-uniform fluid speed distribution, resolving the contradiction between simplified control and propulsion efficiency by enabling differentiated pitch control without complex centralized systems
Solution Approach 2:
Each blade is assigned a specific pitch angle tailored to its local operating conditions (fluid speed at its position). The pitch angle of each blade is optimized for its specific location in the fluid flow, allowing local optimization of propulsion efficiency while maintaining a relatively simple overall control structure
2Productivity
If pitch angle is adjusted to match fluid speed variations, then propulsion efficiency is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The pitch adjustment mechanism utilizes the propeller's own rotational motion and the natural non-uniform fluid flow patterns to automatically differentiate pitch angles among blades. The system leverages existing operational parameters (rotation, fluid flow) to achieve differentiated pitch control without requiring external sensors, actuators, or complex control systems for each blade
Solution Approach 2:
A single pitch control mechanism serves multiple functions by simultaneously controlling the pitch angles of all blades through a unified structure. The mechanism achieves differentiated pitch control for multiple blades using one set of control elements, reducing overall system complexity while maintaining the ability to optimize each blade's pitch angle
3Manufacturing precision
If separate hydraulic control system is used for pitch adjustment, then precise pitch control is achieved, but system complexity and weight increase
Solution Approach 1:
The patent replaces complex hydraulic control systems with a simplified mechanical pitch adjustment mechanism. The mechanical system uses direct mechanical linkages between the pitch control mechanism and the blades, eliminating the need for hydraulic actuators, fluid lines, and associated control systems while maintaining sufficient pitch control precision
Solution Approach 2:
The hydraulic control system is completely removed from the pitch adjustment mechanism. Only the essential mechanical elements needed for pitch differentiation are retained, extracting away the complex hydraulic components while preserving the core function of pitch angle 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
The solution stabilizes and optimizes blade pitch adjustments, enhancing propulsive efficiency by ensuring each blade's pitch angle corresponds to the fluid speed, reducing cavitation and hull vibrations, and simplifying the propeller hub and shaft system by eliminating the need for a separate hydraulic control system.
Implementation Method 1
a power converter that converts a rotating motion of the propeller shaft into a linearly reciprocating motion of the blade actuating shafts
Implementation Method 2
blade actuating shafts that are connected to eccentric stubs coupled to lower ends of the blades and are disposed inside the propeller shaft so as to allow linear reciprocation and to push or pull the eccentric stubs
Data Source
AI summary
Provided is a driving apparatus of a variable pitch propeller having blades, each of which has a pitch angle changed in a rotational direction of a propeller shaft, and a pitch adjuster for adjusting the pitch angle. The pitch adjuster includes blade actuating shafts that are connected to eccentric stubs coupled to lower ends of the blades and are disposed inside the propeller shaft so as to allow linear reciprocation and to push or pull the eccentric stubs, and a power converter that converts a rotating motion of the propeller shaft into a linearly reciprocating motion of the blade actuating shafts.