Marine Power Steering Flow Limiting Valve Chatter Control
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Solution Overview
Problem
Marine power steering systems face challenges with rapid steering, leading to power supply overload and system responsiveness degradation, due to high hydraulic fluid volume requirements and chatter issues from traditional valving with linear flow characteristics, which also complicates assembly and sealing.
Innovation Solution
A flow limiting valve system with a body of varying diameter and an annular gap to control fluid flow rates, limiting initial flow and increasing progressively, and ball-type check valves within the actuator block for controlled ram movement, reducing chatter and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional linear flow characteristic valves are used, then the valve is simple in structure, but the ram moves too rapidly causing chatter at low steering inputs
Solution Approach 1:
The patent changes the flow characteristic parameter of the valve from linear to non-linear by incorporating a flow limiting orifice. This orifice restricts fluid flow during specific phases of valve operation, creating a non-linear flow characteristic that prevents rapid ram movement and chatter while maintaining valve structural simplicity.
Solution Approach 2:
The flow limiting orifice acts as an intermediary element within the valve system. It mediates between the steering input and the ram movement by controlling fluid flow rates, preventing direct transmission of small steering inputs that would otherwise cause chatter, while allowing full flow during maximum steering demands.
2Quantity of substance
If a continuous running electric powered pump is used, then adequate hydraulic fluid volume is provided for rapid steering, but the electrical charging system becomes overloaded
Solution Approach 1:
The patent replaces continuous pump operation with periodic action through an accumulator-based system. The accumulator stores hydraulic fluid under pressure during periods when steering is not demanded, and releases it rapidly when steering is needed. This periodic charging and discharging eliminates the need for continuous electrical power while maintaining adequate fluid volume for rapid steering.
Solution Approach 2:
The accumulator performs preliminary action by pre-storing pressurized hydraulic fluid before it is needed. This advance preparation allows the system to deliver large volumes of fluid rapidly during steering maneuvers without requiring continuous electrical power input, as the fluid is already pressurized and ready for immediate use.
3Ease of manufacture
If the valve flow area increases linearly throughout the operating stroke, then the valve is easy to manufacture, but the ram extension or retraction speed exceeds steering input speed causing chatter
Solution Approach 1:
The patent modifies the flow area parameter along the valve stroke from linear to non-linear distribution. By positioning a flow limiting orifice at a specific location within the valve, the effective flow area remains restricted during initial valve movement, then increases rapidly once the orifice is cleared. This creates a non-linear flow characteristic that matches steering input speed with ram speed, eliminating chatter while maintaining manufacturing simplicity.
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 provides controlled ram movement at reduced rates during initial phases, reducing chatter and power supply overload, while allowing increased flow rates during larger strokes, enhancing system responsiveness and ease of assembly and maintenance.
Implementation Method 1
A flow limiting valve is provided within the actuator block to control fluid flow rates to and from the hydraulic cylinder. The flow limiting valve has a body of varying diameter and an annular gap which, through a substantial portion of a stroke of the flow limiting valve, limits fluid flow rates through the flow limiting valve to a relatively low value during the early phases of valve opening.
Implementation Method 2
The valving may comprise ball-type extend and retract check valves located in the actuator block.
Data Source
AI summary
A power steering system for a marine steering includes a hydraulic cylinder, an actuator block that is mounted on an outer end of a ram of the cylinder, and valving. In one embodiment, the valving is located in the hydraulic cylinder and includes at least one flow limiting valve that, through an initial portion of a stroke thereof, limits fluid flow rates through the valve to a generally constant, relatively low level. This limits the rate of extension or retraction of the ram out of or into the barrel and prevents valve chatter. In another embodiment the valving includes ball-type check valves that are located within the actuator block and that are actuated by a rocker arm assembly in the actuator block.