Outboard Motor Water Pump Layout for Bidirectional Propeller Drive
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Solution Overview
Problem
The installation position of the water pump in outboard motors is restricted by the attachment to the drive shaft, limiting design flexibility and requiring additional space for components due to the need for a clutch mechanism to handle bidirectional rotation.
Innovation Solution
The water pump is driven by the propeller shaft, allowing it to be installed near the propeller shaft where there is more space, and is designed as a non-volumetric pump with a coaxial pump shaft that can rotate in both forward and reverse directions, eliminating the need for a clutch and enabling more flexible component arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the water pump is attached to the drive shaft, then the pump can be driven directly by the engine, but the installation position is restricted and design flexibility is reduced
Solution Approach 1:
The patent separates the water pump drive system from the main drive shaft, creating an independent pump shaft that rotates coaxially with the propeller shaft. This segmentation allows the water pump to be positioned independently near the propeller shaft, freeing it from the restrictions of drive shaft attachment and enabling greater design flexibility in component arrangement.
Solution Approach 2:
The patent introduces a transmission mechanism as an intermediary to transfer rotational motion from the drive shaft to the pump shaft. This intermediary allows the water pump to be driven by the engine while being positioned near the propeller shaft, resolving the spatial conflict between direct drive shaft attachment and optimal pump placement.
2Adaptability or versatility
If the drive shaft rotates in both forward and reverse directions, then bidirectional propulsion is achieved, but a clutch mechanism is required increasing space requirements
Solution Approach 1:
The patent employs a non-volumetric pump (centrifugal pump) that can operate effectively in both forward and reverse rotation directions without requiring a clutch mechanism. This multi-functional capability allows the pump to handle bidirectional rotation from the propeller shaft, enabling bidirectional propulsion while eliminating the space-consuming clutch assembly.
Solution Approach 2:
The patent removes the clutch mechanism from the system by selecting a non-volumetric pump that inherently handles bidirectional rotation. This extraction of the unnecessary clutch component frees up space around the propeller shaft while maintaining the bidirectional rotation capability needed for reverse propulsion.
3Ease of repair
If the pump shaft is detachably connected to the propeller shaft, then maintenance is facilitated, but the connection mechanism adds complexity
Solution Approach 1:
The patent divides the pump shaft connection into detachable segments that can be separated from the propeller shaft for maintenance. This segmentation allows the pump shaft to be independently removed and serviced without disassembling the entire propulsion system, facilitating easier maintenance while keeping the connection mechanism relatively simple through standardized coupling interfaces.
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 increases design flexibility, optimizes the arrangement of cooling water transport components, and simplifies maintenance by allowing the pump shaft to be detached from the propeller shaft, reducing manufacturing complexity and component size.
Implementation Method 1
the water pump includes an impeller and a pump shaft to rotate together with the impeller
Data Source
AI summary
An outboard motor includes an electric motor, a drive shaft to be rotationally driven by the electric motor, a propeller, a propeller shaft to rotate together with the propeller, a gear mechanism to transmit rotation of the drive shaft to the propeller shaft, a cooling water flow path through which cooling water flows, and a water pump to pump the cooling water into the cooling water flow path. The water pump includes an impeller and a pump shaft to rotate together with the impeller, and the pump shaft is coaxial with the propeller shaft and rotatable together with the propeller shaft.