Outboard Motor Trim-Tilt Inrush Current Limiting
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Solution Overview
Problem
Outboard motors face challenges in managing large inrush currents for trim-tilt and steering devices, leading to increased generator or battery size requirements, which is impractical due to limited space within the motor cowl.
Innovation Solution
Implementing Pulse Width Modulation (PWM) control to limit inrush current into the electric motor of the trim-tilt device for a predetermined period during startup, reducing the peak current demand and preventing the need for larger power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the PTT motor, steering motor and fuel pump are connected to a common power source, then the outboard motor can operate all devices, but the size of the generator or battery must increase
Solution Approach 1:
The controller performs preliminary action by detecting the start of inrush current to the PTT motor and preemptively activating PWM control. This preliminary detection and response prevents the full inrush current from occurring, allowing the power source to be sized for normal operating current rather than peak inrush current, thus reducing power source size while maintaining full device operation capability
Solution Approach 2:
The controller applies PWM control periodically or continuously during the period when inrush current is detected, modulating the power delivery to the PTT motor. This periodic modulation limits the peak current while maintaining average power delivery, enabling operation of all devices with a smaller power source that wouldn't need to handle continuous peak loads
2Volume of stationary object
If PWM control is applied to limit inrush current, then the power source size can be reduced, but the control complexity increases
Solution Approach 1:
The controller uses feedback by continuously monitoring the current draw of the PTT motor and detecting when inrush current conditions occur. Based on this feedback, the controller automatically adjusts PWM duty cycle to limit current. This feedback mechanism provides an automated, adaptive solution that reduces power source size requirements without requiring complex manual control systems or oversized components
Solution Approach 2:
The patent replaces what would traditionally require mechanical oversizing of the power source with an electronic control solution (PWM). Instead of mechanically designing the power source to handle peak inrush currents, the electronic PWM control dynamically manages current delivery, substituting a simple electronic control system for a mechanically oversized power source
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 approach effectively reduces the size requirements for generators or batteries while ensuring reliable power supply to the trim-tilt device, even during simultaneous operation with the steering device, without causing significant voltage drops.
Implementation Method 1
The controller is configured or programmed to limit an inrush current into the first electric motor using a PWM (Pulse Width Modulation) control for a predetermined period of time from a starting time point of an input current into the first electric motor.
Data Source
AI summary
A trim-tilt device includes a first electric motor electrically connected to a power source and tilts an outboard motor body in an up-and-down direction. A steering device includes a second electric motor electrically connected to the power source. The steering device turns the outboard motor body in a right-and-left direction. A fuel pump is electrically connected to the power source, and supplies fuel to an engine. A controller limits an inrush current into the first electric motor using a PWM control for a predetermined period of time from a starting time point of an input current into the first electric motor.