Outboard Motor Speed Control for Tilt Rod Load Management
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Solution Overview
Problem
Conventional outboard motors face issues with sudden propulsive forces when tilted up, leading to potential misfire and inadequate propulsive force due to faulty angle detection, and they struggle to manage loads on tilt rods effectively, risking component damage.
Innovation Solution
An outboard motor system with an attachment mechanism, pivoting mechanism, angle detecting device, and controller that adjusts engine speed based on inclination angles and detects abnormalities in the angle detecting device to prevent unnecessary speed reduction and manage loads on tilt rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outboard motor main body is tilted up to prevent contact with shallow bottom or bring vessel onto land, then the propeller is close to water surface which allows easy access, but when propeller enters and exits water suddenly, large propulsive force is suddenly applied causing load on tilt rod and potential component damage
Solution Approach 1:
The controller executes speed reduction control before the propeller enters the water by detecting the inclination angle and predicting propeller entry. When the inclination angle indicates the propeller is approaching water surface, the controller reduces engine speed in advance, preventing sudden application of large propulsive force to the tilt rod and attachment mechanism when the propeller enters water.
Solution Approach 2:
The system continuously monitors the inclination angle of the outboard motor main body and provides feedback to the controller. Based on this feedback, the controller adjusts engine speed dynamically - reducing speed when the inclination angle indicates the propeller is approaching water surface, and maintaining normal speed when the propeller is safely in water or air, thus preventing sudden load on structural components.
2Strength
If the controller makes the engine misfire to reduce engine speed when inclination angle exceeds threshold, then large propulsive force is prevented, but when angle detection device is faulty, unnecessary speed reduction occurs leading to inadequate propulsive force
Solution Approach 1:
The system changes the control parameter from a fixed inclination angle threshold to a dynamically adjusted threshold based on engine speed. When engine speed exceeds the speed threshold, the inclination angle threshold is increased (made more permissive). This allows the system to tolerate higher inclination angles at high speeds without triggering unnecessary speed reduction, while still providing protection when the propeller is actually at risk of entering water.
Solution Approach 2:
The control system transitions from a static threshold-based control to a dynamic control that adapts to current operating conditions. The inclination angle threshold is no longer fixed but varies with engine speed, allowing the system to optimize between protection and performance based on real-time conditions. This dynamic adjustment prevents faulty angle detection from causing unnecessary speed reduction.
3Device complexity
If the speed threshold is fixed, then control is simple, but when propeller is close to water surface, fixed threshold may trigger misfire unnecessarily or fail to prevent load when inclination angle varies
Solution Approach 1:
The control system makes the inclination angle threshold dynamic by linking it to engine speed. When engine speed is high (indicating propeller is likely in water or air), the threshold is increased to prevent unnecessary speed reduction. When engine speed is low (propeller may be near water surface), the threshold is decreased to provide adequate protection. This dynamic approach maintains reliability without requiring complex additional sensors.
Data Source
AI summary
An outboard motor includes an outboard motor main body, an attachment mechanism, a pivoting mechanism, an angle detecting device, a rotation speed detecting device, and a controller. The pivoting mechanism includes a first cylinder arranged to support and pivot the outboard motor main body about a horizontal shaft from a first angle to a second angle greater than the first angle. An angle detection value and a speed detection value are input into the controller. The controller is arranged to execute a speed reduction control to control the engine so as to reduce the engine speed. The controller is arranged not to execute the speed reduction control when the angle detection value is a value corresponding to the inclination angle less than the first angle or a value corresponding to the inclination angle greater than the second angle.