Fluid-Driven Linear Motor With Extended Stroke Valve Control
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Solution Overview
Problem
Existing fluid-powered linear motors are limited by short stroke lengths, making them unsuitable for applications requiring longer strokes, such as driving downhole pumps in wells where efficient operation demands greater displacement.
Innovation Solution
The design incorporates an extension rod and a pressure chamber with a pressure control device, allowing the pilot rod to remain stationary during piston movement, reversing fluid flow, and utilizing a ball valve to manage pressure and prevent backflow, enabling longer stroke lengths and adaptable mounting orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the linear motor uses a conventional slide valve arrangement with a pilot rod, then the structure is simple and reliable, but the stroke length is limited to short distances
Solution Approach 1:
The linear motor is divided into multiple cylinders arranged in series, each cylinder-piston assembly acting as an independent segment. The piston rod of one cylinder connects to the drive rod of the next cylinder, allowing the stroke length to be extended by adding more segments rather than increasing the length of a single cylinder.
Solution Approach 2:
The pilot rod is extended with an extension rod that slides through the piston, creating a nested structure. The extension rod allows the pilot rod to maintain its control function while extending the effective stroke length beyond what a single pilot rod could achieve.
2Length of moving object
If the pilot rod moves synchronously with the piston to control the slide valve, then the control is direct and simple, but the stroke length cannot be extended
Solution Approach 1:
The synchronous movement between the pilot rod and piston is extracted and replaced by an independent control system. The extension rod with the ball valve allows the pilot rod to control fluid flow independently of piston position, enabling the piston to travel longer distances while the pilot rod remains relatively stationary or moves independently.
Solution Approach 2:
A ball valve is introduced as an intermediary between the pilot rod and the fluid flow control. The ball valve sits in a valve seat and is controlled by the extension rod, acting as a mediator that decouples the direct synchronous relationship between pilot rod movement and fluid flow direction changes.
3Productivity
If the linear motor is designed for long stroke lengths, then it can drive downhole pumps efficiently, but the structure becomes more complex with multiple components
Solution Approach 1:
The drive fluid serves multiple functions: it acts as the working fluid that drives the piston, as the control fluid that moves the slide valve, and as the medium that transmits power through the system. This multi-functionality reduces the need for separate control systems and components.
Solution Approach 2:
The control valve and fluid distribution functions are merged into the cylinder walls and piston structure. The slide valve is integrated with the cylinder assembly, and the fluid pathways are built into the structural components rather than being separate elements, reducing overall system complexity.
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 configuration enables fluid-powered linear motors to achieve stroke lengths of several meters, ensuring efficient operation in wells by maintaining fluid flow directionality and preventing pilot rod snapping, thus enhancing operational efficiency and versatility.
Implementation Method 1
a pressure chamber (209) with a pressure control device (205) for holding the pilot rod (22) in its end positions
Implementation Method 2
utilizing a ball valve to manage pressure and prevent backflow
Implementation Method 3
The first modification is that the pilot rod 22 is provided with an extension rod 204 that is arranged slideable through the piston 4 and into a bore 203 inside the piston rod 3
Implementation Method 4
a slide valve arrangement 8 with a slide 9 which is moved between its end positions by means of the drive fluid
Data Source
AI summary
A fluid-driven linear motor comprises a cylinder, a piston, and a piston rod connected to the piston. Two sides of the piston in the cylinder are alternately supplied with fluid from a slide valve arrangement. The slide valve arrangement includes a slide and a pilot rod adapted to alternately set a through-bore of a slide in fluid connection with the ends of the slide when the piston is located in its end positions. The pilot rod is provided with an extension rod adapted to move inside a bore of the piston and the piston rod, so that the stroke length of the linear motor can be extended. A pressure chamber is provided at the distal end of the pilot rod. The pressure chamber is adapted to hold the pilot rod with a holding force when in its end positions until mechanical forces from the piston overcome said holding force.