Watercraft Steering Layout With Overlapping Motor and Reduction Gear
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Solution Overview
Problem
Existing propulsion apparatus for watercraft have a high overall height due to the positioning of the electric motor and planetary gear mechanism, which affects the compactness and efficiency of the steering system.
Innovation Solution
A propulsion apparatus design that overlaps the steering motor and steering reduction gear mechanism vertically, with a brake mechanism and planetary gear mechanism positioned to minimize height, and includes a compact power transmission path using identical diameter spur gears and an oil pan for efficient lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the electric motor and planetary gear mechanism are positioned on top of each other to achieve a compact design, then the overall height is reduced, but the steering system becomes more complex in terms of power transmission path
Solution Approach 1:
The patent positions the steering motor (30) and steering reduction gear mechanism (37) vertically overlapping within the upper case (10), with the motor located above the gear mechanism. This nesting arrangement minimizes the overall height of the steering system while accommodating both components in a compact configuration.
Solution Approach 2:
The patent divides the steering system into distinct functional segments: the steering motor (30) for power generation, the steering reduction gear mechanism (37) for speed reduction and torque multiplication, and the lower case (11) for directional control. This segmentation allows each component to be optimized independently while maintaining overall compactness.
2Volume of moving object
If the steering motor and steering reduction gear mechanism are positioned vertically overlapping, then the vertical space is minimized, but the lubrication system becomes more complex
Solution Approach 1:
The upper case (10) serves multiple functions: it provides structural support for the steering motor (30) and steering reduction gear mechanism (37), acts as a lubrication reservoir through the oil pan (10c), and facilitates power transmission through the drive shaft (22). This multi-functionality reduces the need for separate lubrication components.
Solution Approach 2:
The steering reduction gear mechanism (37) is designed to be self-lubricated through the oil pan (10c) integrated into the upper case (10). The gear mechanism automatically draws lubrication from the oil reservoir without requiring external lubrication systems, simplifying the overall design.
3Ease of manufacture
If identical diameter spur gears are used in the power transmission path, then manufacturing is simplified, but the transmission efficiency may be reduced
Solution Approach 1:
The patent specifies that the first spur gear (32) and second spur gear (35) have substantially the same diameter, which simplifies manufacturing processes and inventory management. This parameter standardization is achieved while optimizing the gear ratio and tooth design to maintain adequate transmission efficiency for the steering application.
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 design achieves a compact vertical dimension, efficient lubrication, and improved reliability with simplified power transmission, allowing for stable and predictable steering even in failure scenarios.
Implementation Method 1
a planetary gear mechanism interposed between the output shaft of the electric motor and the propulsion unit
Implementation Method 2
a brake mechanism (34) including a vertically extending brake shaft (33) and an electromagnetic clutch which selectively engages the brake shaft with a fixed part of the upper case
Implementation Method 3
an electromagnetic clutch which selectively engages the brake shaft with a fixed part of the upper case
Implementation Method 4
the lubrication of the steering reduction gear mechanism can be performed in an efficient manner
Data Source
AI summary
A propulsion apparatus for watercraft, including a propulsion motor (M) supported by an upper case, a lower case (11) supported by the upper case so as to be rotatable around a steering axis, and rotatably supporting a drive shaft (22) for transmitting power from the propulsion motor to a propulsion device (13), a steering motor (30) received in the upper case, and a steering reduction gear mechanism (37) received in the upper case, wherein an axis of a rotational output of the steering reduction gear mechanism and an axis of a rotational output of the steering motor extend vertically in parallel with an axis of the drive shaft, and the steering motor overlaps with the steering reduction gear mechanism with respect to a vertical direction.