Marine Propulsion Motor Layout for Lower-Head Cooling Pumps
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Solution Overview
Problem
Existing marine propulsion devices require large pumps for effective cooling due to the significant height difference between the pump discharge port and the uppermost end of the motor water jacket, leading to increased device size and manufacturing costs.
Innovation Solution
The marine propulsion device is designed with the motor oriented horizontally such that the output shaft extends in a front-rear direction, reducing the height difference between the pump discharge port and the uppermost end of the motor water jacket, allowing for a smaller, lower-head pump to be used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the motor is disposed vertically above the pump with a large height difference, then the cooling water can effectively reach the motor water jacket, but a large high-head pump is required which increases device size and manufacturing costs
Solution Approach 1:
The motor is reoriented from a vertical arrangement (with large height difference from pump) to a horizontal arrangement where the output shaft extends in the front-rear direction. This dimensional change reduces the vertical height difference between pump discharge port and motor water jacket, allowing use of a smaller, lower-head pump while maintaining cooling effectiveness.
2Quantity of substance
If a large pump is used to overcome the height difference, then adequate cooling water flow can be achieved, but the device size and manufacturing costs increase
Solution Approach 1:
By changing the motor orientation from vertical to horizontal, the vertical distance that cooling water must travel is reduced. This allows adequate cooling water flow rate to be achieved with a smaller pump, reducing both pump volume and overall device volume.
3Ease of manufacture
If the motor is oriented horizontally with output shaft extending in front-rear direction, then the height difference is reduced allowing smaller pump, but the transmission mechanism arrangement becomes more complex
Solution Approach 1:
The transmission mechanism is divided into two separate mechanisms: first transmission mechanism positioned in front of the motor and second transmission mechanism positioned below the first. This segmentation allows the horizontal motor orientation to be achieved while distributing the transmission functions across different spatial locations, managing the complexity through modular arrangement.
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 minimizes the pump size and reduces manufacturing costs while maintaining effective cooling capacity for the motor, speed reducer, and inverter components.
Implementation Method 1
a water pump disposed below the motor and configured to send water taken into the marine propulsion device from the intake port to the motor water jacket as cooling water
Implementation Method 2
The cooling water flows in the water jacket, thereby cooling the motor
Data Source
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AI summary
A marine propulsion device includes a motor including an output shaft, a drive shaft extending in a vertical direction of the marine propulsion device, and a cooling device. The motor is disposed so that an extension direction of the output shaft is a direction perpendicular to the vertical direction. The cooling device includes an intake port taking water outside the marine propulsion device into the marine propulsion device, a motor water jacket provided in the motor and cooling the motor, a water pump disposed below the motor and sending water taken into the marine propulsion device from the intake port to the motor water jacket as cooling water, and a first cooling water passage connecting a discharge port of the water pump to an inlet port of the motor water jacket.