Non-linear Liquid Damper for Ship Stabilizer Low Angular Velocity
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Solution Overview
Problem
Existing ship stabilizers struggle to effectively dampen motion when the swing motion angular velocity is small, leading to inadequate motion reduction and discomfort for crew during low wave heights.
Innovation Solution
A passive-type damper mechanism with a non-linear damping coefficient that increases with angular velocity, utilizing a liquid damper with a variable orifice section to provide enhanced motion reduction torque, especially at low angular velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive-type damper mechanism with constant damping coefficient is used, then the device complexity is reduced, but the motion damping effect becomes insufficient at small angular velocities
Solution Approach 1:
The patent applies the dynamics principle by making the damping coefficient variable rather than constant. The orifice section area in the damper mechanism changes dynamically based on the angular velocity of the gimbal, allowing the damping coefficient to increase as angular velocity decreases. This dynamic adjustment ensures effective motion damping across all operating conditions without requiring complex active control systems.
Solution Approach 2:
The patent implements parameter changes by modifying the physical parameters of the damper mechanism. Specifically, the orifice section area is designed to vary with angular velocity, which directly changes the damping coefficient parameter. This allows the passive damper to adapt its damping characteristics to different operating conditions, maintaining reliability across the full range of motion.
2Reliability
If the damping coefficient is increased to improve motion reduction, then the motion reduction torque increases, but the damper becomes ineffective at low angular velocities
Solution Approach 1:
The patent uses the dynamics principle to create a damping coefficient that is dynamically adjusted based on operating conditions. The orifice section area changes with angular velocity, ensuring that the damping coefficient is appropriately sized for each operating regime. This dynamic behavior allows the damper to provide sufficient motion reduction torque at all speeds without being ineffective at low angular velocities.
Solution Approach 2:
The patent applies parameter changes by designing the orifice section area to vary as a function of angular velocity. This causes the damping coefficient parameter to change automatically with operating conditions, ensuring optimal motion reduction torque is provided across the entire angular velocity range, particularly improving performance at low speeds.
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 non-linear damper mechanism effectively increases output torque at low wave heights, improving motion reduction and crew comfort by suitably damping small angular velocities, while maintaining stability and avoiding excessive damping coefficient reduction.
Implementation Method 1
a liquid damper with a variable orifice section to provide enhanced motion reduction torque
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An anti-roll device (10) comprises: a base (20) fixed to an object (1) to be reduced in rolling; a gimbal (40) which is supported so as to be rotatable about a first shaft (RA); a damper mechanism (30) which dampens the relative rotative movement of the gimbal (40) with respect to the base (20); and a flywheel (50) which is rotatable about a second shaft (RB) perpendicular to the first shaft (RA). The damper mechanism (30) is a passive damper mechanism. A first value (D1) of a damping coefficient (D) of the damper mechanism (30) when the angular velocity of the gimbal (40) is a first angular velocity is greater than a second value (D2) of the damping coefficient (D) of the damper mechanism (30) when the angular velocity of the gimbal (40) is a second angular velocity lower than the first angular velocity.