Marine Power Steering Pump Speed Control for Aeration Prevention
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Solution Overview
Problem
Aeration of hydraulic fluid in power steering systems for outboard motors occurs when the pump is angled, reducing the volume and positive head of fluid above the pump inlet, leading to inefficient steering performance due to the pump operating at higher speeds and steep trim angles.
Innovation Solution
A control system that adjusts the pump speed based on the trim angle of the outboard motor, using a tilt sensor to detect the angle and a lookup table to cap pump speed, thereby minimizing aeration risks and maintaining steering performance across various trim angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pump operates at higher speeds to improve steering response, then steering performance is improved, but aeration of hydraulic fluid occurs reducing system reliability
Solution Approach 1:
The pump speed is made dynamic and adjustable based on the trim angle condition. The system transitions from fixed-speed pump operation to variable-speed operation, where the control system adjusts pump speed according to real-time trim angle detection, allowing optimal performance across different operating conditions while preventing aeration at steep angles.
Solution Approach 2:
The system implements feedback control by continuously monitoring the trim angle via the tilt sensor and using this information to adjust pump speed through the control system. This closed-loop feedback mechanism ensures that pump speed is reduced when steep trim angles are detected, preventing aeration while maintaining steering responsiveness under normal conditions.
2Measurement precision
If the outboard motor is trimmed to steeper angles to improve positioning, then positioning capability is improved, but pump aeration occurs leading to loss of hydraulic fluid
Solution Approach 1:
The control system takes preliminary action by detecting steep trim angles before aeration can occur and proactively reducing pump speed in advance. This preventive measure ensures that the pump operates within safe parameters even when the outboard motor is positioned at steep angles, preventing hydraulic fluid loss before it occurs.
Solution Approach 2:
The system changes the operating parameters of the pump based on trim angle conditions. Specifically, the pump speed parameter is adjusted according to the detected trim angle, reducing speed when steep angles are detected. This parameter change allows the system to maintain positioning capability while preventing aeration and hydraulic fluid loss.
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 effectively prevents aeration by reducing pump speed at steeper trim angles, ensuring consistent steering performance and reducing the time required for the fluid to return to a non-aerated state, thus maintaining system functionality throughout the full range of trim angles.
Implementation Method 1
A tilt sensor detects a trim angle of the outboard motor
Implementation Method 2
A pump communicates a hydraulic fluid with the hydraulic actuator to cause actuation thereof
Data Source
AI summary
A steering system for a trimmable outboard motor. The steering system includes a hydraulic steering device that upon actuation changes a steering angle of the outboard motor. A pump communicates a hydraulic fluid with the hydraulic actuator to cause actuation thereof, where the pump operates at a pump speed, and where the pump speed impacts a change rate for the hydraulic steering device changing the steering angle. A reservoir is fluidly coupled to the pump and configured to retain the hydraulic fluid. A tilt sensor detects a trim angle of the outboard motor. A control system is operatively coupled with the pump and receives requests for changing the steering angle. The control system controls the pump speed of the pump based at least in part on the trim angle of the outboard motor.