Propeller Drive Screw Pump Assembly for Efficient Oil Lubrication
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Solution Overview
Problem
Existing propeller drive assemblies for water surface vessels face challenges in achieving high oil pumping efficiency while maintaining low manufacturing complexity, as existing solutions either complicate the driveshaft design or result in low efficiency due to the integration of pumping mechanisms.
Innovation Solution
A separate screw pump mechanism is introduced, comprising a first and second element forming a helix within the driveshaft housing, allowing for efficient oil pumping without complicating the driveshaft design, and enabling the pump to be driven by the driveshaft during sailing, even when the engine is shut down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external screw shape is provided on the driveshaft to pump oil, then oil pumping function is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The screw pump is divided into two separate elements: a rotating element with a helical cavity and a stationary element with a matching helical cavity. These elements are manufactured separately and then assembled, allowing each component to be optimized independently and simplifying manufacturing compared to creating an external screw shape on the driveshaft.
Solution Approach 2:
The screw pump elements are nested within the housing, with the rotating element featuring an internal helical cavity rather than an external screw shape. This internal cavity design allows the pump to be integrated into the existing driveshaft housing structure without modifying the driveshaft itself.
2Reliability
If a stationary pump housing with internal thread is used, then oil pumping is achieved, but pumping efficiency is low
Solution Approach 1:
The rotating element with the helical cavity rotates within the stationary element, creating dynamic pumping action. This rotational movement generates more effective oil displacement compared to static thread structures, significantly improving pumping efficiency while maintaining reliable oil circulation.
3Reliability
If the driveshaft is modified to include pumping features, then oil lubrication is improved, but driveshaft design requirements become more complex
Solution Approach 1:
The pumping function is extracted from the driveshaft and implemented as a separate screw pump mechanism consisting of rotating and stationary elements. This allows the driveshaft to maintain its original design for torque transmission while the pump elements handle oil circulation, eliminating the need to modify the driveshaft structure.
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 enhances oil pumping efficiency and reduces manufacturing costs by allowing the screw pump to be manufactured separately from the driveshaft, facilitating easy integration into existing designs and providing effective lubrication during sailing, while maintaining a simple design.
Implementation Method 1
a screw pump, which may be referred to as an Archimedean screw pump, is provided in the propeller drive assembly, which pump is arranged to pump oil upwards along the driveshaft
Data Source
AI summary
A propeller drive assembly includes a driveshaft for transferring a torque between an engine and a propeller of a water surface vessel, and a housing enclosing the driveshaft. The assembly includes, separately from the driveshaft, a first element and a second element, the first element extending through a first bore of the second element, wherein one of the first and second elements is fixed to the driveshaft and the other of the first and second elements is arranged to be stationary in relation to the housing, and the one of the first and second elements which is fixed to the driveshaft presents in the first bore a first elongated cavity forming a first helix along the first bore, so as to form with the other of the first and second elements a screw pump.