Drilling Rig Steering System Electric Drive Control
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Solution Overview
Problem
Current drilling rigs in the Arctic face challenges with large turning radii, tire scrub, and environmental risks due to high-pressure hydraulic systems, which lead to potential spills and stability issues during maneuvering.
Innovation Solution
An electric drive, hydraulic steer moving system that allows for precise directional control of 8 tires, using AC electric motors and a Variable Frequency Drive (VFD) system to balance wheel loads and speeds, with a double-ended cylinder steering mechanism that reduces hydraulic fluid usage and pressure, enabling smooth turns and reduced tire scrub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-pressure hydraulic systems are used to power the moving system, then sufficient power and tractive effort are provided to move the rig, but the risk of environmental oil spills increases due to hose failure or leaks
Solution Approach 1:
The patent replaces the high-pressure hydraulic drive system with an electric drive system using motors and generators. This substitution eliminates the need for large volumes of hydraulic fluid under high pressure, thereby removing the primary source of environmental spill risk while maintaining the capability to provide sufficient tractive effort to move the rig.
Solution Approach 2:
The patent changes the operating parameters of the hydraulic system by reducing both the pressure and flow rate. By operating at lower pressures and flow rates, the system maintains adequate power transmission while significantly reducing the volume of hydraulic fluid required, thus minimizing environmental risk in case of leaks or failures.
2Ease of operation
If Akermann steering with a long steering bar is used, then steering control is provided, but the steering bar cannot rotate wheel sets 90 degrees without removal and replacement
Solution Approach 1:
The patent employs a steerable wheel assembly where the steering bar is dynamically repositioned along the longitudinal axis of the rig based on the required travel direction. For lateral travel, the steering bar is positioned at one end; for longitudinal travel, it is repositioned to the center. This dynamic adjustment eliminates the need for physical removal and replacement of the steering bar, enabling continuous operation across different travel modes.
Solution Approach 2:
The steering bar is designed to serve multiple functions by being repositionable along the rig's longitudinal axis. The same steering bar handles both lateral steering (when positioned at the end) and longitudinal steering (when positioned at the center), eliminating the need for separate steering mechanisms or bar replacements for different travel directions.
3Ease of operation
If current steering geometry is used, then front and back steering mechanisms operate independently, but the turning radius increases and tires may walk off rims during tight curve negotiation
Solution Approach 1:
The patent merges the front and back steering mechanisms into a coordinated system where both steering bars are actuated simultaneously to point to a common turn center. This coordinated operation ensures that all four wheel sets follow concentric radial paths during curve negotiation, preventing tire walk-off from rims while maintaining proper steering geometry for tight turns.
Solution Approach 2:
The system incorporates feedback control where the positions and orientations of front and back wheel sets are continuously monitored and adjusted to maintain proper steering geometry. This feedback ensures that during curve negotiation, the steering angles are coordinated to keep all tires following their correct radial paths, preventing tire walk-off and improving reliability.
4Measurement precision
If electric motors with VFD control are used, then precise directional control and wheel load balancing are achieved, but system complexity increases
Solution Approach 1:
The patent uses Variable Frequency Drives (VFDs) to dynamically control the speed and torque parameters of each electric motor independently. By adjusting these parameters, the system achieves precise directional control and automatic wheel load balancing. The VFDs allow each wheel to operate at optimized speeds and torques, improving control precision while the electronic control system manages the complexity through automated algorithms.
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 system enables the drilling rig to navigate tight curves with minimal tire scrub, reduces the risk of environmental spills, and enhances operational safety by using less hydraulic fluid and lower pressure, allowing for precise control and reduced heat generation in the tire system.
Implementation Method 1
Each wheel assembly may include an AC electric motor
Implementation Method 2
utilizing its own power and in any direct... The 8 AC electric motors may be controlled from a Variable Frequency Drive (VFD) house
Implementation Method 3
The rig may include a vertical hydraulic lift cylinder over each of the trunnions
Implementation Method 4
double-ended cylinder steering mechanism that reduces hydraulic fluid usage and pressure
Data Source
AI summary
A drill rig with a steering system may include a substructure having a wheelhouse, a drill floor arranged atop the substructure, a mast extending upwardly and above the drill floor, and a steering system arranged within the wheelhouse. The steering system may include a wheel assembly comprising an electric motor configured for driving rotational motion of a wheel, a deployment device configuring for deploying the wheel assembly to carry the drill rig, and a steering mechanism configured for selective engagement with the wheel assembly and rotating the wheel assembly.