Planetary Roller Screw Pitch Control Unit for Marine Propellers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing controllable pitch propeller systems face inaccuracies due to elastic deformations and maintenance issues, particularly in hydraulic systems, which are environmentally unfriendly and noisy, while mechanical systems are inefficient and complex.
Innovation Solution
A pitch control unit utilizing a planetary roller screw assembly that converts rotational motion into precise axial displacement of the actuator rod, eliminating backlash and allowing for accurate blade pitch adjustment, with a compact design that minimizes noise and environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hydraulic systems are used for pitch control, then high power transmission capability is achieved, but accuracy deteriorates due to elastic deformations and leakages
Solution Approach 1:
The patent replaces the hydraulic system with an electrical motor-driven screw assembly system. The control motor drives the screw assembly to convert rotational motion into precise linear displacement of the actuator rod, eliminating hydraulic fluid leakages and elastic deformations of hydraulic components. This mechanical-electrical system provides both high power transmission and precise position control through direct coupling and rigid mechanical transmission.
2Power
If hydraulic systems are used for pitch control, then high power transmission capability is achieved, but environmental harm increases due to oil leakage
Solution Approach 1:
The patent eliminates hydraulic systems entirely and replaces them with an electrical motor and screw assembly mechanism. This substitution removes the source of environmental pollution (hydraulic oil leakage) while maintaining the required power transmission capability through the motor's rotational output converted to linear actuation via the screw mechanism.
3Power
If hydraulic systems are used for pitch control, then high power transmission capability is achieved, but noise levels increase
Solution Approach 1:
The patent replaces the noisy hydraulic system with an electrical motor-driven system. The motor operates quietly compared to hydraulic pumps and actuators, and the screw assembly provides smooth, vibration-free operation. This eliminates the high noise levels associated with hydraulic fluid flow, pump operation, and pressure fluctuations while maintaining effective power transmission for pitch control.
4Ease of manufacture
If mechanical systems are used for pitch control, then simplicity is improved, but efficiency deteriorates and device complexity increases
Solution Approach 1:
The patent employs an electrical motor instead of complex mechanical linkages, cams, or gear trains. The motor directly drives the screw assembly through a simple transmission path, eliminating multiple mechanical components that would reduce efficiency and increase complexity. The electrical control system provides precise, responsive pitch adjustment with high efficiency and minimal mechanical losses.
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 high accuracy, low maintenance, and reduced noise, enabling precise control of blade pitch over a wide range while being environmentally friendly and capable of handling high loads, thus overcoming the limitations of existing systems.
Implementation Method 1
a screw assembly arranged around the hollow drive shaft, the screw assembly comprising a rotatable body, and a travelling body, wherein the control motor is arranged to drive rotation of the rotatable body and wherein the screw assembly converts the rotation of the rotatable body into an axial displacement of the travelling body
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A pitch control unit for adjusting the pitch of a controllable pitch propeller of a vessel using a mechanical system. The pitch control unit comprises a hollow drive shaft with an input side for receiving power from a prime mover and an output side for delivering power to the propeller. The pitch control unit further comprises a control motor and a screw assembly arranged around the hollow drive shaft. The control motor drives rotation of a rotatable body of the screw assembly and the screw assembly converts that rotation into an axial displacement of a travelling body of the screw assembly. The travelling body is connected to a coupling member that extends through the hollow drive shaft and is connected to an actuator rod that upon linear displacement actuates a blade pitch adjustment mechanism inside a controllable pitch propeller. The connection between the travelling body and the coupling member is arranged by a yoke assembly that translates together with both the travelling body and the coupling member, and that rotates along with the drive shaft. The invention further relates to a vessel and propulsion arrangement comprising such a pitch control unit.