Pod Drive Reduction Gearing for Propeller Shaft Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pod drives with reduction gearing face challenges in achieving prolonged operation without failure due to limited service life of the propeller shaft bearing, which is exacerbated by the need for large and expensive electric motors for low-speed operation, leading to compromised propeller efficiency and increased drag.
Innovation Solution
The use of two spaced-apart bearings for the propeller shaft with a significant distance between them, allowing for a larger electric motor size reduction and improved bearing design, including a planetary system with a hollow rotor and sleeve configuration, to enhance service life and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large electric motor is used to achieve low propeller speed, then the propeller rotation speed is reduced, but the motor size and cost increase
Solution Approach 1:
A reduction gearing is introduced as an intermediary mechanism between the electric motor and the propeller shaft. The motor runs at higher speed while the gearing reduces the speed to optimal propeller rotation speed, avoiding the need for an oversized motor
Solution Approach 2:
The system changes the speed parameter through the reduction gearing, allowing the motor to operate at different speed than the propeller, optimizing both motor size and propeller efficiency
2Device complexity
If a single bearing is used for the propeller shaft, then the structure is simple, but the service life is limited
Solution Approach 1:
The single bearing is segmented into two spaced-apart bearings along the propeller shaft. This segmentation distributes the load and reduces stress on each individual bearing, significantly extending the overall service life of the bearing system
3Weight of moving object
If the propeller rotates slightly faster than optimum, then a smaller electric motor can be used, but the propeller efficiency decreases
Solution Approach 1:
The reduction gearing acts as a mediator that decouples the motor speed from propeller speed, allowing the motor to run faster (reducing its size) while the gearing ensures the propeller rotates at optimal speed (maintaining efficiency)
Solution Approach 2:
The reduction gearing changes the speed parameter between motor and propeller, enabling independent optimization of motor size and propeller efficiency through different rotational speeds
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
This configuration enables prolonged operation of pod drives with reduced motor size, lower drag, and improved handling, while maintaining propeller efficiency and extending the service life of the reduction gearing, comparable to conventional diesel drives.
Implementation Method 1
a planetary system, the details of which can be found in FIG. 3
Implementation Method 2
the rotor of the electric motor employed is hollow and the propeller shaft extends through the latter
Implementation Method 3
said bearing of said propeller shaft comprises two spaced-apart bearings
Data Source
AI summary
Pod drive which can be fitted to a vessel and which is provided with an electric motor which drives a propeller shaft which is likewise provided in the housing of the pod drive and is connected to a propeller which is situated outside the latter. It is proposed to use a fast-rotating electric motor in combination with a reduction gearing for driving the propeller shaft. The mounting of the propeller shaft is made particularly stable by mounting it on both sides of the electric motor. The reduction gearing may include a planetary system. The electric motor may be fitted next to the hollow propeller shaft. In this case, several electric motors can be arranged around the central propeller shaft. It is also possible to make the rotor of the electric motor hollow and to fit the propeller shaft inside the latter.