Tunnel Thruster Drive With Nested Planetary Gear Reduction
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Solution Overview
Problem
Tunnel thrusters face challenges with high vertical dimensions due to the size of electric motors required for sufficient torque, which limits their installation in boats with low ceiling spaces.
Innovation Solution
The design incorporates an electric motor with a planetary gear reducer that is embedded within the motor flanges, allowing for a reduction in the motor's axial length and thus reducing the overall vertical dimension of the driving unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an electric motor with higher torque is used to meet power requirements, then the motor power is sufficient, but the vertical dimension of the driving unit increases
Solution Approach 1:
The planetary gear reducer is nested within the motor flange structure, with gears arranged in a compact planetary configuration where planet gears orbit around a central sun gear. This nesting allows the reduction mechanism to be contained within the motor's axial space without increasing the overall vertical dimension, while still providing the necessary torque multiplication through gear ratio
Solution Approach 2:
The invention transitions from a conventional linear gear arrangement to a planetary gear system that utilizes radial and axial dimensions more efficiently. The planet gears are distributed around the sun gear in a radial pattern, converting the torque transmission from a single-line arrangement to a multi-dimensional configuration that fits within the motor flange's circular cross-section, thereby reducing the axial length
2Length of moving object
If a planetary gear transmission is added to reduce motor size, then the vertical dimension decreases, but the device complexity increases
Solution Approach 1:
The planetary gear reducer is merged with the motor flange structure, where the gear housing and flange become integrated components. The sun gear is directly coupled to the motor shaft, and the planet gears are mounted on pins that are part of the flange structure. This merging eliminates the need for separate transmission housings and mounting brackets, reducing the number of parts and assembly steps despite the complex gear mechanism
Solution Approach 2:
The motor flange structure serves multiple functions: it provides the mounting interface for the motor to the drive shaft, contains the planetary gear reduction mechanism, and supports the planet gears through integrated pins and bearings. This multi-functionality reduces the overall component count and simplifies the assembly process, offsetting the inherent complexity of the planetary gear system
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 solution enables the use of smaller, cheaper electric motors with lower torque but higher rpm, resulting in a more compact thruster driving unit with reduced vertical dimensions, facilitating installation in smaller spaces.
Implementation Method 1
a planetary gear transmission that is mounted in the motor housing outside the stator coil heads
Implementation Method 2
the gear transmission is a planetary gear reducer comprising a sun gear as a driving gear wheel, arranged on the motor shaft, a ring gear, and a carrier with planet gears
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a driving unit for an electric tunnel thruster. Such driving unit comprises an electric motor (1) with a shaft (2), an electric motor support (3) to be mounted on a tunnel (4) of the electric tunnel thruster and a driving unit transmission with reduction gear ratio >1 for transmitting of electric motor rotation to an L-shaped transmission (8) of the propeller (9). The driving unit transmission can be a gear transmission, such as a planetary gear reducer (11). Said planetary gear reducer can be fully or partially embedded in a cavity of the front flange (18) of the motor (1). The advantages of the electric tunnel thruster, according to the present invention, are the small vertical dimensions, the option to use a cheaper motor with less torque and a cheaper/smaller L-shaped redactor also allowing more water to flow through the tunnel cross-section.