Reciprocating Pump Drive Assembly Cable Configuration
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Solution Overview
Problem
Existing drive assemblies for reciprocating pumps, such as those used in oil wells, are complex and require significant maintenance due to the need for additional shock absorbers to manage rapid movement and potential power loss, leading to potential damage from cable failures.
Innovation Solution
A drive assembly design featuring a support frame, linear actuator, pump bracket, anchor bracket, and two pairs of direction-altering cable guides with four lengths of cable connected in series, providing a balanced and integral cable strand that distributes force evenly across the polish rod, minimizing damage from cable failure and maintaining balance during reciprocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional shock absorbers are added to manage rapid movement and power loss, then the reliability of the drive assembly improves, but the device complexity increases and maintenance requirements increase
Solution Approach 1:
The patent applies beforehand cushioning by configuring the cable system with multiple cable lengths and direction-altering cable guides arranged to absorb shock and control the movement of the travelling nut along the rotating screw. This arrangement provides gradual deceleration during power loss events without requiring separate shock absorber components, thereby improving reliability while avoiding the complexity of additional shock absorption devices.
2Reliability
If multiple cable lengths with direction altering cable guides are used, then the factor of safety improves and cable failure damage is minimized, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the cable system into multiple discrete cable lengths (first, second, third, and fourth cable lengths) with direction-altering cable guides positioned at specific locations. This segmentation creates redundant load paths so that if one cable fails, the remaining cables continue to support the polish rod, providing a factor of safety while distributing the complexity across modular, standardized components.
Solution Approach 2:
The arrangement of multiple cable lengths with direction-altering guides inherently provides shock absorption and gradual deceleration capabilities, cushioning against sudden cable failures and power loss events before they can cause damage, thereby improving safety factors without requiring separate cushioning devices.
3Reliability
If the cable system is designed to provide gradual deceleration during power loss, then the reliability improves, but the device complexity and maintenance requirements increase
Solution Approach 1:
The cable system configuration with multiple cable lengths and direction-altering guides provides beforehand cushioning by creating a progressive deceleration mechanism during power loss events. The geometry of the cable arrangement and guides naturally absorbs shock and controls the travelling nut's movement, improving reliability while using passive mechanical elements that require minimal maintenance compared to active shock absorption systems.
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 enhances the safety and reliability of the drive assembly by ensuring minimal damage from cable failure and maintaining balanced forces on the polish rod, reducing maintenance needs and preventing unnecessary wear, while providing a mechanical advantage for efficient pump operation.
Implementation Method 1
a linear actuator including a lower portion arranged to be fixed to the support frame and an upper portion supported on the lower portion for linear reciprocating movement
Implementation Method 2
the cable and cable guide configuration provide a mechanical advantage which results in the polish rod reciprocally moving a multiple of the distance traveled by the movable ram portion of the linear actuator
Data Source
AI summary
A drive assembly for connection to the polish rod of a reciprocating pump includes a support frame fixed in proximity to a wellhead. A linear actuator includes a lower portion fixed to the support frame and an upper portion supporting two pairs of direction altering cable guides thereon. Four lengths of cable each include a first portion substantially anchored to relative to the polish rod by a pump bracket, a second portion substantially anchored to the support frame by an anchor bracket, and an intermediate portion extending through a respective one of the direction altering cable guides on the upper portion of the linear actuator between the first portion and the second portion.