Downhole Pump Reverse Reduction Gear for Autonomous Direction Switching
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Solution Overview
Problem
Existing submersible well pump systems with rolling screw-nut transmission face inefficiencies due to reliance on ground control stations for direction changes, leading to reduced reliability and energy efficiency, especially when control stations fail or experience abrupt motor starts.
Innovation Solution
Incorporating a reverse reduction gear with a switching mechanism, such as a tie-rod or additional screw-nut transmission, to autonomously switch direction of rotation at extreme positions, eliminating the need for external control station signals and reducing motor start-stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the direction of rotation is changed by control station signals, then the pump can be controlled remotely, but the reliability decreases when control station fails
Solution Approach 1:
The switching mechanism enables the system to automatically change rotation direction using mechanical feedback from the screw-nut transmission itself, eliminating dependence on external control station signals. The mechanism self-activates when the nut reaches extreme positions, ensuring continuous operation even during control station failures.
Solution Approach 2:
The switching mechanism uses mechanical feedback from the position of the nut in the screw-nut transmission to automatically trigger direction changes. The lock of extreme positions detects when the nut reaches the end of its travel and automatically initiates the switching process, creating a closed-loop control system that does not require external signaling.
2Adaptability or versatility
If the electric motor frequently starts and stops to change direction, then the pump can reverse, but the energy efficiency decreases due to current spikes
Solution Approach 1:
The switching mechanism allows the electric motor to operate continuously without frequent start-stop cycles. By mechanically reversing the rotation direction while the motor remains running, the system eliminates the energy-wasting current spikes associated with repeated motor startups, maintaining continuous useful action.
Solution Approach 2:
The reverse reduction gear with switching mechanism acts as an intermediary between the electric motor and the screw-nut transmission. It absorbs the directional change function, allowing the motor to maintain continuous rotation while the intermediary mechanism handles the reversal, thereby preventing direct motor stop-start cycles.
3Ease of operation
If the pump relies on control station signals for direction changes, then centralized control is maintained, but productivity decreases due to operational delays
Solution Approach 1:
The switching mechanism is pre-configured with locks of extreme positions that automatically detect when the nut reaches the end of its travel. This preliminary detection and automatic triggering eliminates delays associated with waiting for control station signals, allowing immediate direction changes and improving productivity.
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 enhances the reliability and energy efficiency of the downhole pump drive by allowing continuous operation without abrupt current spikes and ensuring reliable direction changes, even in the absence of a functioning control station.
Implementation Method 1
an elastic shell, wherein the drive shaft of the motor is connected with the rolling screw-nut transmission through a reverse reduction gear with a switching mechanism
Data Source
AI summary
A downhole pump drive includes a housing, a submersible electric motor and protector, the drive shaft of which is coupled to the screw of a ball screw actuator movably coupled to the housing and is coupled to a rod sealed inside the housing. Interior cavities of the housing communicate with an annular space of the borehole through an elastic shell. The drive shaft of the electric motor is connected to the ball screw actuator via a reverse reduction gear. The reverse reduction gear is switched only when the nut of the ball screw actuator (or of an additional ball screw actuator) arrives at its terminal positions, improving the drive's operational reliability. The electric motor operates in a continuous mode, increasing reliability and energy efficiency of the drive owing to the absence of repeated starting and stopping of the electric motor; consequently, a spike in current intensity upon start-up is avoided.