Telescopic Screw Drive Assembly for Reciprocating Pump
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Solution Overview
Problem
Longer linear actuators, such as hydraulic rams and lifting screws, are prone to deflection, which can lead to jamming, bending, or fatigue failure, and existing solutions either increase the diameter or limit the stroke length to mitigate this, but these approaches have limitations.
Innovation Solution
A drive assembly combining a rotating screw with a travelling nut and telescopic fluid cylinders, where the telescopic cylinders act as shock absorbers to slow the movement of the nut in case of power loss, preventing damage to the pumping unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the diameter of the linear actuator is increased to reduce deflection, then the structural strength and stability improve, but the device complexity and cost increase
Solution Approach 1:
The linear actuator is divided into multiple telescopic sections that can extend and retract relative to each other. This segmentation allows the actuator to maintain high strength and resistance to deflection in each section while keeping the overall diameter small, thus avoiding the need for a large-diameter single-piece actuator.
Solution Approach 2:
The telescopic sections are nested within each other, with smaller diameter sections contained within larger diameter sections. This nesting arrangement allows the actuator to achieve a long extended length without requiring a proportionally large diameter, thereby maintaining strength while reducing device complexity and cost.
2Length of moving object
If the length of the linear actuator is increased to achieve the required stroke, then the operational capability improves, but the actuator becomes more prone to deflection and failure
Solution Approach 1:
The long stroke requirement is met by dividing the actuator into multiple telescopic segments that can extend sequentially. Each segment maintains a manageable length that avoids excessive deflection, while the combined extension of all segments achieves the required total stroke length, thus maintaining reliability.
Solution Approach 2:
The actuator transitions from a static, fixed-length structure to a dynamic, variable-length structure through telescopic extension. During operation, the actuator can adjust its effective length, maintaining optimal structural integrity at each extension stage rather than requiring a constantly long, vulnerable structure.
3Use of energy by moving object
If the rotating screw acts as the primary linear actuator, then the operational cost is reduced, but the descent speed during power loss becomes excessively rapid causing damage risk
Solution Approach 1:
The patent combines the rotating screw mechanism (low operational cost) with telescopic fluid cylinders (shock absorption capability) into a hybrid actuator system. The fluid cylinders are integrated alongside the screw mechanism, allowing the system to benefit from both the energy efficiency of the screw and the safety of the fluid cushioning during uncontrolled descent.
Solution Approach 2:
The telescopic fluid cylinders are pre-configured to provide cushioning and damping effects. In the event of power loss, these fluid cylinders automatically engage to slow the descent of the travelling nut before damage can occur, providing beforehand protection against the harmful rapid descent effect.
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 solution effectively reduces the risk of damage to the pumping unit during power loss by slowing the rapid descent of the travelling nut, thereby enhancing the operational safety and reliability of the drive assembly.
Implementation Method 1
The telescopic fluid cylinders serve as shock absorbers which slow the movement of the travelling nut
Implementation Method 2
The telescopic fluid cylinders serve as shock absorbers which slow the movement of the travelling nut
Implementation Method 3
a rotating screw with a travelling nut are combined
Implementation Method 4
The inclined plane provided by the rotating screw is substantially less expensive to operate than a telescopic fluid driven cylinder
Data Source
AI summary
A drive assembly for a reciprocating pump includes a support structure with a linear actuator mounted on the support structure. The linear actuator has a stationary portion and a movable ram portion. At least one direction altering cable guide is mounted to the movable ram portion of the linear actuator. At least one cable is provided having a first end and a second end. The first end is anchored to one of the support structure or the stationary portion of the linear actuator. The second end is adapted for attachment to a polish rod of a reciprocating pump. As the movable ram portion moves, the cable and cable guide configuration provide a mechanical advantage which results in the polish rod reciprocally moving a multiple of the distance travelled by the movable ram portion of the linear actuator.