Cryogenic Pump Stroke Velocity Control via Pressure Feedback
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Solution Overview
Problem
Hydraulic actuators in cryogenic pumps face challenges in maintaining optimal stroke velocity due to variations in hydraulic supply pressure, physical wear, and sensor offset errors, which can lead to inefficient or failed pump operations.
Innovation Solution
A method using sensors to detect the start and end of pump strokes, calculate stroke velocity, and adjust hydraulic supply pressure based on comparisons to a reference velocity, employing a PID controller to correct pressure errors and maintain optimal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed loop pressure control system is used to maintain desired pressure difference, then pressure control is achieved, but other effects affecting stroke velocity such as physical wear, hydraulic oil viscous temperature effects, and sensor offset errors are not captured
Solution Approach 1:
The patent implements feedback by using sensors to detect the actual stroke velocity and comparing it to the desired stroke velocity. The system continuously monitors the stroke velocity by detecting the position of the hydraulic piston at the start and end of each stroke, calculating the actual velocity, and using this feedback to adjust the hydraulic supply pressure through a control valve to maintain the desired stroke velocity despite physical wear, temperature effects, and sensor offset errors.
2Force
If too much hydraulic supply pressure is applied to actuate hydraulic piston, then actuation force is sufficient, but stroke velocity becomes higher than allowed which degrades pump components or leads to failure
Solution Approach 1:
The control system uses feedback from velocity sensors to continuously monitor the actual stroke velocity and adjusts the hydraulic supply pressure accordingly. When the stroke velocity exceeds the desired velocity, the system reduces the supply pressure through the control valve to slow down the piston movement, preventing component degradation while maintaining sufficient actuation force.
Solution Approach 2:
The system dynamically changes the hydraulic supply pressure parameter based on the detected stroke velocity. By adjusting the pressure parameter in real-time according to the actual velocity measurements and desired velocity profile, the system maintains optimal actuation force without exceeding velocity limits that would cause component degradation.
3Strength
If too little hydraulic supply pressure is applied to hydraulic piston, then component degradation is prevented, but stroke velocity becomes below desired velocity or pump does not perform full stroke leading to inefficient operation
Solution Approach 1:
The feedback control system monitors the actual stroke velocity and compares it to the desired velocity. When the stroke velocity is below the desired velocity, the system increases the hydraulic supply pressure through the control valve to accelerate the piston movement, ensuring the pump achieves full stroke and operates efficiently while preventing excessive pressure that would cause component degradation.
4Ease of operation
If sensor offset errors are present in velocity measurement, then measurement accuracy deteriorates, but stroke velocity control precision is maintained through continuous calibration
Solution Approach 1:
The system performs preliminary calibration actions by detecting the start and end positions of each stroke to establish reference points. By continuously recalibrating the velocity measurements based on the actual detected stroke positions at the beginning and end of each stroke, the system compensates for sensor offset errors and maintains measurement accuracy without requiring manual intervention.
Data Source
AI summary
A method for controlling a stroke velocity in a pump includes using a sensor to detect a start of a pump stroke and an end of the pump stroke. A stroke time is calculated, the stroke time being a time period between the start of the pump stroke and the end of the pump stroke. The stroke velocity is calculated based on a stroke length and the stroke time. The stroke velocity is compared to a reference stroke velocity. A hydraulic supply pressure to the pump is increased if the calculated stroke velocity is less than the reference stroke velocity, and the hydraulic supply pressure is decreased if the calculated stroke velocity is more than the reference stroke velocity.