Modular Fluid Piston Motor with Harmonic Drive for Downhole Drilling
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Solution Overview
Problem
Existing downhole drill rotation systems are limited by complexity, large form factors, high maintenance requirements, and temperature limitations, particularly in high-temperature environments, and generate lateral vibrations due to eccentric motion in positive displacement motors.
Innovation Solution
A fluid-powered motor system using a piston/harmonic drive assembly within a housing, where pressurized fluid drives the piston/harmonic drive assembly over a liner to impart rotation to a rotor assembly, maintaining components on centerline and reducing lateral vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If positive displacement motors are used to generate downhole rotation, then rotational energy is transferred to the drill bit, but lateral vibrations are induced due to eccentric motion of the rotor
Solution Approach 1:
The patent replaces the traditional eccentric rotor mechanism with a linear piston motor system that uses fluid pressure to drive pistons in and out, which then drive a rotor through a harmonic drive mechanism. This substitution eliminates the inherent eccentric motion that causes lateral vibrations while maintaining the ability to generate rotational power at the drill bit.
Solution Approach 2:
The invention uses hydraulic fluid pressure to drive the pistons, converting fluid energy into mechanical motion. The pressurized fluid acts on the pistons to create linear motion, which is then converted to rotational motion through the harmonic drive, providing power transmission without the harmful vibrations of traditional mechanical systems.
2Power
If traditional drill pipe rotation systems are used, then rotational energy is transferred downhole, but the system complexity and maintenance requirements increase
Solution Approach 1:
The patent divides the motor into modular components including pistons, cylinders, and a harmonic drive mechanism, allowing for compact packaging and simplified assembly. The segmented design enables the complex functions to be achieved through coordinated simple components, reducing overall system complexity while maintaining power transmission capability.
Solution Approach 2:
The invention employs a nested arrangement where the piston assembly is contained within the motor housing, and the harmonic drive mechanism is integrated within the piston assembly. This nesting allows multiple functional components to be compactly arranged, reducing the overall form factor and simplifying the system architecture.
3Temperature
If positive displacement motors operate in high-temperature environments, then drilling in hot wells is enabled, but the elastomers are limited by temperature range
Solution Approach 1:
The patent replaces elastomeric seals and flexible components with metal-to-metal sealing surfaces and rigid mechanical elements that can withstand high temperatures. The harmonic drive mechanism uses rigid gears and bearings instead of flexible couplings, eliminating the temperature sensitivity of elastomers while maintaining the motor's ability to operate in hot environments.
Solution Approach 2:
The invention employs high-temperature resistant materials including heat-treated steel alloys for the piston and housing, and specialized coatings on the harmonic drive components. These composite material selections enable the motor to maintain structural integrity and functional reliability in temperatures exceeding the limits of conventional elastomeric materials.
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 provides efficient and reliable drill rotation with reduced maintenance and operational in high-temperature environments by converting hydraulic power into rotational force without inducing lateral vibrations, enhancing drilling efficiency and durability.
Implementation Method 1
Fluid provided from the rotor assembly to the valve assembly axially drives the piston/harmonic drive assembly over the liner
Implementation Method 2
piston/harmonic drive assembly comprises a piston and a harmonic drive... axially driving the piston/harmonic drive assembly over the liner imparts rotation to the rotor assembly
Data Source
AI summary
A modular motor is disclosed that includes a piston/harmonic drive assembly that is axially cycled. The piston/harmonic drive assembly is coupled to a ball transfer arrangement that converts the axial motion into rotary motion to rotate a rotor that can be used to rotate a drill bit.