Variable-Speed Pump Pilot Control for Pressure Drop Prevention
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Solution Overview
Problem
Variable-speed variable-displacement pumps face limitations in dynamics during non-cyclic operations, leading to pressure drops when handling large changes in quantity, restricting their use in machines that do not operate cyclically.
Innovation Solution
Implementing a pilot control mechanism that increases the setpoint speed using a ramp function and pre-control signals, particularly when triggering conditions such as pressure or volume flow differences exceed threshold values, to enhance pump dynamics and prevent pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the setpoint speed is determined as a function of actual delivery volume for pressure regulation, then energy-optimal operation is achieved, but the speed dynamics are limited and cannot follow changes quickly enough, leading to pressure drops
Solution Approach 1:
The pilot control applies a pre-control value to the setpoint speed in advance when a triggering condition is detected, before the actual pressure drop occurs. This preliminary speed increase prepares the system to respond more quickly to upcoming changes in delivery volume, preventing pressure drops while maintaining energy efficiency.
Solution Approach 2:
The system dynamically adjusts the setpoint speed by superimposing a speed increment on the originally calculated setpoint speed. This creates a more dynamic speed response that can quickly follow changes in delivery volume while still returning to energy-optimal operation after the transient condition passes.
2Reliability
If the drive speed is increased to follow large changes in quantity quickly, then pressure drops are prevented, but the system complexity increases due to the need for pilot control and triggering condition monitoring
Solution Approach 1:
The pilot control continuously monitors triggering conditions such as the time gradient of delivery volume or the difference between setpoint and actual delivery pressure. When these feedback signals indicate an upcoming pressure drop, the system automatically applies a speed increment to prevent the pressure drop, creating a closed-loop control that maintains reliability without requiring complex external control systems.
3Productivity
If a ramp function is used to increase speed with maximum gradient, then the fastest possible speed increase is achieved to minimize pressure drop duration, but the time delay between switching process and speed ramp start must be minimized
Solution Approach 1:
The pilot control detects triggering conditions in advance and applies the speed increment before the actual pressure drop occurs. This preliminary action eliminates time delays by preparing the speed increase proactively, allowing the ramp function to start immediately when needed rather than waiting for pressure changes to manifest.
Data Source
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AI summary
The method involves driving an axial-piston pump (20) by a variable-rotation speed drive (30). An actual volumetric flow and an actual delivery pressure are controlled at a target volumetric flow and/or a target delivery pressure by adjusting a target conveying rate of the pump and a target rotation speed of the drive. The target speed is increased using a pilot controller in a predetermined release condition. A precontrol value is determined from a difference between a reference value and an actual value of the delivery pressure, the volumetric flow, conveying volume or the rotation speed. The variable-rotation speed drive is designed as an asynchronous motor (31). Independent claims are also included for the following: (1) a computing unit for operating a variable-rotation speed adjustable flow pump (2) a variable-rotation speed adjustable flow pump.