Hydraulic Pumping Apparatus Stroke Control
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Solution Overview
Problem
Existing oil well pumping systems experience shock and excess load when changing direction, particularly at the bottom of the stroke, due to inadequate control mechanisms, leading to potential damage and inefficiency.
Innovation Solution
A hydraulic oil well pumping apparatus utilizing a hydraulic cylinder with a piston and sucker rod, controlled by electronic means with proximity or limit switches and a directional control valve, which manages the valving arrangement to smoothly transition between up and down strokes, reducing stress on the pumping string and sucker rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hydraulic pumping systems operate without advanced electronic control, then the system structure remains simple, but shock and excess load occur during direction changes causing potential damage
Solution Approach 1:
The proximity switch detects the piston's approach to the bottom of the stroke and activates the directional control valve in advance to close the inlet valve before the piston actually reverses direction. This preliminary action prevents shock and excess load by preparing the valve arrangement before the directional change occurs, eliminating the need for complex active control during the reversal moment.
Solution Approach 2:
The proximity switch provides feedback about the piston's position near the bottom of the stroke to the directional control valve. This feedback mechanism allows the system to automatically adjust the valve position based on real-time piston location, ensuring smooth directional transitions without requiring complex control algorithms or multiple sensors.
2Productivity
If the directional control valve responds quickly to piston position changes, then pumping efficiency improves, but shock load increases during direction changes
Solution Approach 1:
The proximity switch activates the directional control valve in advance before the piston reaches the bottom of the stroke. This timing ensures that the inlet valve closes smoothly as the piston begins its upward movement, preventing sudden pressure changes and shock load while maintaining efficient pumping operation.
Solution Approach 2:
By closing the inlet valve before the piston reverses direction at the bottom of the stroke, the system cushions against the harmful shock load that would otherwise occur during the directional change. This preliminary valve action absorbs the pressure surge and protects the pumping string and sucker rod from mechanical stress.
3Reliability
If the inlet valve closes at the bottom of the stroke to prevent backflow, then fluid containment improves, but shock and excess load occur during direction change
Solution Approach 1:
The proximity switch triggers the directional control valve to close the inlet valve before the piston reaches the bottom of the stroke. This timing ensures that the valve is already closed when the piston reverses direction, preventing backflow while eliminating shock force by avoiding sudden pressure changes during the directional transition.
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 effectively minimizes shock and excess load during operation, enhancing the reliability and efficiency of oil extraction by ensuring a bumpless transfer of fluid and balancing pressures, thus prolonging equipment life and optimizing pumping performance.
Implementation Method 1
A prime mover such as an engine is connected to a compensating type hydraulic pump. A hydraulic flow line connects the pump and the hydraulic cylinder.
Implementation Method 2
A directional control valve moves between open flow and closed flow positions.
Implementation Method 3
Electronic controls are provided that control movement of the piston as it moves between the upper and lower positions utilizing proximity or limit switches.
Data Source
AI summary
A pumping arrangement employs a compensating type hydraulic pump, a directional valving arrangement and a proportioning valving arrangement. When the directional valve is energized, oil is directed to the rod end of the hydraulic cylinder. The rod or piston part of the hydraulic cylinder will then elevate until a first limit switch is actuated which then will de-energize the directional valve and send a current signal to the proportional valve. This current signal to the proportional valve forces it to open to a point at which the cylinder rod would extend at the desired velocity until it reaches a second limit switch. The current signal to the proportional valve is then decreased, creating a choking arrangement that forces the cylinder rod to decelerate. Upon reaching the third limit switch, the signal is removed from the proportional valve so that it closes.