Electric Outboard Motor Neutral Shift for Reverse Switching
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Solution Overview
Problem
Existing electric-powered outboard motors for watercraft experience damage to mechanical parts when the rotation direction of the electric motor is switched while the watercraft is moving, due to sudden changes in force acting on the propeller and power transmission mechanism.
Innovation Solution
An electric outboard motor with a control device that transitions the drive state of the electric motor to a neutral state for a predetermined time period before switching from forward to reverse rotation, or vice versa, based on watercraft speed and torque, to reduce mechanical stress on the propeller and power transmission mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotation direction of the electric motor is switched suddenly from forward to reverse while the watercraft is moving, then the response time for avoiding obstacles is improved, but the mechanical parts (propeller and power transmission mechanism) are damaged due to large force acting on them
Solution Approach 1:
The control device performs preliminary action by transitioning the electric motor to a neutral state before completing the rotation direction switch. When a direction change is detected, the control device first sets the motor to neutral state, allowing the propeller to slow down gradually before reversing rotation, thereby preventing sudden force changes that would damage mechanical parts
Solution Approach 2:
The neutral state acts as a cushioning intermediate state between forward and reverse rotation. During this neutral state, the electric motor does not drive the propeller, allowing the mechanical system to absorb the shock of direction change gradually rather than experiencing abrupt force reversal, thus protecting the propeller and power transmission mechanism
2Strength
If a neutral state is introduced between forward and reverse rotation states, then the mechanical parts are protected from damage, but the time required for rotation direction switching is increased
Solution Approach 1:
The control device dynamically adjusts the duration of the neutral state based on real-time watercraft speed. When the watercraft is moving at high speed, the neutral state is maintained longer to allow gradual deceleration; when speed is low, the neutral state duration is shortened. This dynamic adjustment protects mechanical parts while minimizing unnecessary time loss
Data Source
AI summary
An electric outboard motor 1 includes an operating part 33 that is switchable between forward and reverse rotation positions; a control device 35 configured to switch, based on the position of the operating part, a drive state of an electric motor 8 between forward, reverse, and neutral states. When the position of the operating part is switched from the forward rotation position to the reverse rotation position (ST1 Yes) while a watercraft is moving (ST2: Yes), the control device causes the drive state to transition from the forward rotation state to the reverse rotation state (ST3) such that, before completion of the transition, the drive state is held to be the neutral state for a predetermined time period (ST4).