Contra-Rotating Propulsion Motor with Hollow Shaft
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Solution Overview
Problem
Conventional contra-rotating propulsion apparatuses require large planetary gear units, which are difficult to install and maintain, leading to space constraints and potential operational interruptions due to gear unit malfunctions, and increasing the length of the hollow shaft complicates lubrication and alignment.
Innovation Solution
A propulsion apparatus with a drive motor inside the stern boss part to rotate the hollow shaft opposite to the main shaft, reducing the length of the hollow shaft and allowing operation with either the front or rear propeller, even if the other fails, using a separate power unit and electricity supply to ensure propulsion, and incorporating a superconducting motor with a cooling system for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large planetary gear unit is used to rotate the front and rear propellers in opposite directions, then the contra-rotating propulsion function is achieved, but the installation space requirement increases and the device complexity increases
Solution Approach 1:
The patent extracts the gear transmission function from the propulsion system by using an independently rotating hollow shaft instead of a planetary gear unit. The hollow shaft is directly driven by a motor to rotate in the opposite direction to the main shaft, eliminating the need for complex gear mechanisms while maintaining the contra-rotating propulsion capability.
Solution Approach 2:
The patent replaces the mechanical planetary gear system with a dual-motor electromagnetic drive system. Each shaft (main shaft and hollow shaft) has its own motor, allowing independent rotation control without mechanical gear transmission. This substitution reduces device complexity and installation space requirements.
2Volume of stationary object
If the planetary gear unit is deployed in a forward position to secure installation space, then the installation space is secured, but the hollow shaft length increases causing lubrication difficulties and alignment problems
Solution Approach 1:
The patent segments the propulsion system into two independent rotational systems: the main shaft driven by the power unit and the hollow shaft driven by the motor. This segmentation allows each shaft to be optimized independently, with the hollow shaft positioned at the stern end rather than extending forward, thereby reducing its length and eliminating lubrication and alignment issues.
3Productivity
If a planetary gear unit is used to achieve contra-rotation, then the propeller efficiency is improved, but the reliability decreases due to potential malfunctions interrupting operation
Solution Approach 1:
The patent extracts the unreliable planetary gear unit from the system and replaces it with independently driven shafts. Each shaft has its own motor, so if one motor or shaft fails, the other can continue to provide propulsion, significantly improving operational reliability and continuity.
Solution Approach 2:
The patent incorporates redundancy by providing two independent drive systems (power unit for main shaft and motor for hollow shaft). This beforehand cushioning ensures that if one drive system fails, the other can compensate and maintain propulsion capability, preventing complete operational interruption.
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
Enables efficient propulsion with reduced space requirements, improved lubrication and alignment, and continued operation if one propeller fails, while optimizing space utilization and reducing the risk of operational interruptions.
Implementation Method 1
a drive motor including a rotor coupled to an outer circumferential surface of the hollow shaft and a stator supported by the hull, the drive motor rotating the hollow shaft in a direction opposite to a direction of rotation of the main shaft
Implementation Method 2
The drive motor may be a superconducting motor. The rotor of the drive motor may include a superconducting coil
Implementation Method 3
a cooling chamber to accommodate coolant to cool the superconducting coil
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed herein is a propulsion apparatus for ships. The propulsion apparatus, which includes a front propeller and a rear propeller to rotate in opposite directions and provides propulsion power to propel a hull of a ship, includes a power unit to supply power to rotate the rear propeller, a main shaft to transfer the power supplied from the power unit to the rear propeller, a hollow shaft extending in a longitudinal direction of the main shaft to allow the main shaft to pass therethrough and coupled to the front propeller, a drive motor including a rotor coupled to an outer circumferential surface of the hollow shaft and a stator supported by the hull, the drive motor rotating the hollow shaft in a direction opposite to a direction of rotation of the main shaft, and an electricity supply unit to supply electricity to the drive motor.