Torque Limiting Gear Train for Offshore Jack-Up Stability
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Solution Overview
Problem
Offshore jack-up machines face dynamic overloads due to swell movements, which conventional gear systems struggle to absorb, limiting their operational range and stability, especially in moderate to strong swell conditions.
Innovation Solution
Incorporating torque limiting means into the gear train connecting the driving means with the output pinion, which allows rotation when torque exceeds a predetermined limit, preventing static or dynamic overloads and enabling effective dissipation of forces during leg percussion against the seabed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gear systems are used to drive the output pinion, then the structure can be maneuvered in calm water conditions, but the system cannot effectively absorb dynamic overloads caused by swell movements
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed, rigid gear train with a dynamic system that can adapt to varying load conditions. The torque-limiting device allows the gear train to flex and accommodate dynamic overloads from swell movements, enabling the structure to maneuver reliably in both calm and rough water conditions.
2Reliability
If an elastic device is used to connect the gear train to the hull, then some dynamic overload is reduced, but the rigidity and stability of the offshore machine in the raised position is compromised
Solution Approach 1:
The patent applies local quality by placing the torque-limiting device specifically at the connection between the gear train and the output pinion, rather than using a general elastic coupling throughout the system. This localized solution provides dynamic overload protection only where needed, while maintaining the rigidity and stability of the overall structure in its raised position.
3Manufacturing precision
If the gear train is made rigid to ensure stable maneuvering, then positioning accuracy is improved, but dynamic overloads from swell cannot be absorbed
Solution Approach 1:
The patent introduces a torque-limiting device as an intermediary element between the rigid gear train and the output pinion. This intermediary component allows the rigid gear train to maintain positioning accuracy while providing a mechanism to absorb and dissipate dynamic overloads from swell movements, protecting the system from harmful forces.
4Reliability
If torque limiting means are added to the gear train, then dynamic overload is absorbed, but the device complexity increases
Solution Approach 1:
The patent applies the extraction principle by isolating the torque-limiting function into a separate, dedicated device that can be integrated into the existing gear train without fundamentally redesigning the entire system. This modular approach adds the necessary overload absorption capability while minimizing the increase in overall device complexity.
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 absorbs and dissipates static and dynamic overloads, allowing the jack-up machine to operate safely in unfavorable swell conditions by preventing mechanical deterioration of the gear train and maintaining stability.
Implementation Method 1
torque limiting means cooperating with said frame, which torque limiting means have a limit torque which is determined so: in immobilizing said slaved element in rotation with respect to said frame when its torque is less than said limit torque, and to allow rotation of said element slaved with respect to said frame when its torque is greater than said limit torque
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The present invention relates to a device for the translational manoeuvring of a structure that is able to move with respect to a fixed support, advantageously an aerial lift, which device (1) comprises at least one rack (2) and at least one output pinion (3) which is driven by motor means (4) and is so via a gear train (5) borne by a chassis (C). At least one of the elements (16) of said gear train (5) consists in a slave element (16) borne by a shaft (17) equipped with torque limiting means (18) collaborating with said chassis (C) and having a limit torque which is determined in such a way: as to immobilize said slave element (16) in terms of rotation with respect to said chassis (C) when its torque is below said limit torque so as to allow translational manoeuvring of said mobile structure by the turning of said output pinion (3, 19), and - as to allow said slave element (16) to rotate with respect to said chassis (C) when its torque is higher than said limit torque, so as to avoid a static or dynamic overload being applied to said gear train (5).