Contra-Rotating Propeller Motor Placement for Shroud Downsizing
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Solution Overview
Problem
The existing propulsion apparatus for underwater vehicles, as described in U.S. Pat. No. 8,074,592, requires a larger shroud to accommodate a pair of motors for contra-rotating propellers, leading to an inevitable upsizing of the shroud.
Innovation Solution
A fluid machine design that includes a shaft portion, a shroud surrounding the shaft portion, a first propeller and a second propeller, an outer periphery driving motor in the shroud, and an inner periphery driving motor in the shaft portion, allowing for downsizing of the shroud by optimizing the motor placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If both motors for contra-rotating propellers are accommodated in the shroud, then the propulsion function is achieved, but the shroud size increases
Solution Approach 1:
The propulsion system is segmented into two independent motor units: an outer periphery driving motor housed in the shroud, and an inner periphery driving motor housed in the shaft portion. This segmentation allows each motor to be positioned in separate spatial zones, eliminating the need to accommodate both motors within the shroud volume while maintaining full propulsion functionality through coordinated operation of both motor-propeller systems
Solution Approach 2:
The motor arrangement transitions from a two-dimensional planar layout (both motors in the shroud) to a three-dimensional distributed configuration (one motor in the shroud, another in the shaft portion). This dimensional redistribution optimizes spatial utilization by placing motors in different radial and axial positions, thereby reducing the shroud size requirement while preserving propulsion capability
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 proposed design achieves downsizing of the shroud, improves propulsion performance by reducing drag, and enhances the design flexibility to minimize water resistance, thereby improving the overall efficiency of the underwater vehicle.
Implementation Method 1
a first propeller provided rotatably around the axis between the shaft portion and the shroud; a second propeller provided rotatably around the axis between the shaft portion and the shroud on the downstream side of the first propeller
Implementation Method 2
an outer periphery driving motor provided in the shroud and configured to rotationally drive one of the first propeller and the second propeller; and an inner periphery driving motor provided in the shaft portion and configured to rotationally drive another of the first propeller and the second propeller
Data Source
AI summary
A fluid machine includes: a shaft portion extending in an axis direction; a shroud provided to surround the shaft portion, and forming a flow path between the shroud and the shaft portion, the flow path having one side in the axis direction serving as an upstream side and another side in the axis direction serving as a downstream side; a first propeller provided rotatably around the axis between the shaft portion and the shroud; a second propeller provided rotatably around the axis between the shaft portion and the shroud on the downstream side of the first propeller; an outer periphery driving motor provided in the shroud and configured to rotationally drive the first propeller; and an inner periphery driving motor provided in the shaft portion and configured to rotationally drive the second propeller in a direction opposite to the rotational direction of the first propeller.