Outboard Motor Cooling Pump Layout Without Priming
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Solution Overview
Problem
Existing electric propulsion machines face challenges in reducing size and durability due to the use of rotary volume change pumps with rubber impellers, which require priming and are prone to damage when the motor rotation direction is reversed.
Innovation Solution
Implementing a non-positive displacement pump, such as a centrifugal pump, located on the propeller shaft below the water surface to ensure easy priming and improved durability by reversing the impeller rotation direction without damaging the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotary volume change pump with rubber impeller is used to achieve high suction capacity, then the pump can suction out air and water effectively, but the pump size increases and durability decreases when rotation direction reverses
Solution Approach 1:
The patent inverts the conventional pump design by placing the pump on the propeller shaft instead of the drive shaft. This allows the pump to rotate with the propeller shaft, which maintains consistent rotation direction regardless of motor reversal, thereby solving the durability issue while maintaining suction capacity through proper impeller design
2Productivity
If a rotary volume change pump with rubber impeller is used to achieve high suction capacity, then the pump can suction out air and water effectively, but the overall device size increases
Solution Approach 1:
The patent merges the pump function with the propeller shaft by positioning the pump on the propeller shaft and utilizing its rotation. This integration allows the pump to share structural space with the propeller assembly, reducing overall device volume while maintaining effective suction capacity through optimized impeller geometry
3Reliability
If the pump is disposed above the anti-cavitation plate, then the motor cooling can be achieved, but the periphery of the impeller may not be filled with water at startup requiring priming
Solution Approach 1:
The patent applies preliminary action by positioning the pump on the propeller shaft below the water surface, ensuring that the impeller periphery is pre-filled with water before operation begins. This eliminates the need for priming while maintaining the pump's ability to deliver cooling water to the motor
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 solution allows for a compact design and enhanced durability by ensuring easy priming and maintaining pump functionality regardless of motor rotation direction, thus reducing the overall size and weight of the electric propulsion machine.
Implementation Method 1
a non-positive displacement pump (centrifugal pump)
Data Source
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AI summary
An electric propulsion machine (1) for propelling a boat. The electric propulsion machine (1) includes a motor (2) provided in an upper portion of the electric propulsion machine (1), a propeller shaft (5) provided in a lower portion of the electric propulsion machine (1), a propeller (4) provided in the propeller shaft (5), a drive shaft (6) extending in an upper-lower direction and configured to transmit rotation of the motor (2) to the propeller shaft (5), and a first non-positive displacement pump (22) provided in the propeller shaft (5) and configured to supply cooling water to the motor (2), the cooling water cooling the motor (2).