Propulsion Module Worm Gear High Ratio
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Solution Overview
Problem
Current pulling tools for installing fibre optic cables and slick lines in horizontal wells face challenges due to the limited rigidity of these cables, requiring efficient and lightweight battery-operated tools with insufficient gear ratios for high RPM operation, and existing gear systems are either complex or have low achievable gear ratios, making it difficult to achieve a compact and efficient design.
Innovation Solution
A compact and efficient gear system with a higher gear ratio is achieved using an eccentric, internally toothed gear system, such as a cycloid, hypocycloid, or harmonic gear, allowing for a smaller diameter and higher performance propulsion unit with a brushless motor, enabling a transmission ratio greater than 1:50, which is not possible with traditional planetary gears of the same size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional planetary gears are used in the propulsion wheel, then the gear system can reduce rotational speed, but the achievable gear ratio is relatively low and the system becomes complex
Solution Approach 1:
The patent replaces the traditional planetary gear mechanism with a worm gear system. The worm gear consists of a worm (screw-like component) and a worm wheel (gear with teeth cut in a helical pattern), which provides a fundamentally different mechanical approach to achieving high reduction ratios. This substitution eliminates the complex nested structure of planetary gears while delivering superior gear reduction capability.
Solution Approach 2:
The worm gear introduces a third dimensional element (the helical thread of the worm) to the traditional two-dimensional gear interaction. This dimensional change allows for self-locking capability and much higher reduction ratios in a more compact configuration, as the worm can drive the worm wheel but the worm wheel cannot back-drive the worm, providing inherent mechanical advantage.
2Volume of moving object
If the pulling tool diameter is reduced to pass through small nipple profiles, then the tool can access narrow well diameters, but the gear system becomes more constrained
Solution Approach 1:
By replacing the planetary gear system with a worm gear system, the patent achieves a more compact and simpler gearing solution that fits within the constrained diameter of the pulling tool. The worm gear's linear-wrapped geometry allows for efficient power transmission in a smaller radial envelope compared to the multi-component planetary arrangement.
3Use of energy by moving object
If a high RPM brushless motor is used, then the motor operates at higher efficiency, but the gear ratio must be increased to match the propulsion wheel speed requirements
Solution Approach 1:
The worm gear system provides the necessary high gear ratio (greater than 1:50) to bridge the speed gap between the high RPM brushless motor and the propulsion wheel. The worm gear's inherent mechanical advantage allows the motor to operate at its efficient high RPM range while still delivering the required low-speed, high-torque output to the propulsion wheel.
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 solution enables a smaller, lightweight, high-performance pulling tool with a higher gear ratio, allowing for efficient operation in narrow well diameters and effective installation of fibre optic cables and slick lines, while maintaining efficiency and power over time, even in moist environments.
Implementation Method 1
A propulsion module of a pulling tool (64) for pulling a slick line or fibre optic cable (30) within a wellbore or a tubing includes an electric motor (8) for driving a propulsion wheel (6) via the gear system
Implementation Method 2
The gear system of the propulsion wheel (6) comprises an eccentric, internally toothed gear system including a fixed inner gear and a moving outer gear
Data Source
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AI summary
The present invention relates to a slick line and/or fibre optic cable pulling wellbore and/or tubing pulling tool including a propulsion module (64) having a main section (1 ) and a hinged propulsion arm (2). A propulsion wheel (6) with a gear system is supported in the propulsion arm. A gear system of the propulsion wheel (6) comprises an eccentric, internally toothed gear system with a fixed inner gear and a moving outer gear. The moving outer gear constitutes the propulsion wheel (6) of the pulling tool. An electric motor (8) drives the propulsion wheel (6) via the gear system. Also described is a propulsion module for such a pulling tool.