Hydraulic Drive Switching Control for Alternating Pressure Loads
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Solution Overview
Problem
Conventional hydraulic drives for alternately pressurized systems face challenges in achieving optimal operation with unpredictable switching states and inefficiencies due to dynamic pressure differences, leading to suboptimal cycle times and energy usage.
Innovation Solution
A hydraulic drive system with a controllable outfeed device and infeed device that selectively opens or closes hydraulic connections between lines and a tank, allowing for predictable switching states and pressure-dependent fluid feeding to manage leakage and ensure efficient operation, including the use of variable hydraulic machines and electronically controlled valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional hydraulic drives use dynamic pressure difference switching, then the system can operate with simple valve control, but the switching states become unpredictable and cycle time increases
Solution Approach 1:
The outfeed device is configured to open or close hydraulic connections at predetermined switching timepoints before the actual pressure equalization occurs. This preliminary action allows the control device to predict and plan switching states in advance, making them deterministic rather than reactive to unpredictable pressure dynamics.
Solution Approach 2:
The control device receives information about the actual switching states and uses this feedback to optimize future switching timepoints. This closed-loop control enables continuous improvement of cycle time while maintaining predictable switching behavior through learned patterns.
2Loss of energy
If conventional hydraulic drives operate without controlled outfeed, then the system structure is simpler, but energy efficiency decreases due to unmanaged pressure differences
Solution Approach 1:
The outfeed device acts as an intermediary component between the hydraulic lines and the tank, providing controlled fluid discharge paths. This intermediary structure enables energy-efficient pressure management by allowing controlled equalization rather than direct, unmanaged discharge, achieving good energy efficiency with moderate structural complexity.
3Reliability
If the infeed device feeds hydraulic fluid continuously, then the hydraulic lines are always charged, but leakage compensation and cooling requirements increase system complexity
Solution Approach 1:
The infeed device transitions from continuous feeding to dynamic, pressure-dependent feeding. It actively monitors pressure differences between the infeed line and hydraulic lines, opening or closing connections based on real-time conditions. This dynamic approach maintains reliable suction conditions while reducing unnecessary fluid flow for cooling and leakage compensation.
4Productivity
If switching timepoints are optimized for short cycle time, then productivity increases, but energy efficiency may deteriorate due to rushed pressure equalization
Solution Approach 1:
The outfeed device operates in periodic cycles with optimized switching timepoints that balance speed and efficiency. By rhythmically opening and closing hydraulic connections at predetermined moments, the system achieves short cycle times while allowing sufficient time for energy-efficient pressure equalization during each phase of the periodic operation.
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 solution enables improved energy efficiency and shorter cycle times by allowing precise control over hydraulic fluid flow, predicting switching states, and maintaining correct suction conditions, thus enhancing the performance of hydraulic consumers like piston compressors.
Implementation Method 1
the infeed device ensures that leakage from the hydraulic machine and other hydraulic components is compensated for, that the low-pressure side is charged to ensure correct suction conditions at the hydraulic machine
Implementation Method 2
an outfeed device which is configured to selectively open or close, in a controllable manner, hydraulic connections between the first line or the second line, respectively, and an outfeed line which is hydraulically connected to a tank
Implementation Method 3
a double-acting hydraulic cylinder with two chambers supplied with pressurized hydraulic fluid so that a piston located between the two chambers is moved alternately in opposite directions
Data Source
AI summary
A hydraulic drive for a hydraulic consumer alternately pressurized in opposite directions during operation is disclosed. The hydraulic drive includes (i) first and second hydraulic power outputs, (ii) a hydraulic machine driven by an electric machine, said hydraulic drive comprising a first hydraulic working output which is connected to the first drive output via a first hydraulic line, and comprising a second hydraulic working output connected to the second drive output via a second hydraulic line, (iii) an infeed device which is configured to feed hydraulic fluid from a tank into the first and/or the second line in a pressure-dependent manner by way of an infeed line, and (iv) a outfeed device which is configured to selectively open or close a hydraulic connection between the first hydraulic line and a hydraulic outfeed line which is hydraulically connected to the tank in a controllable manner and a hydraulic connection between the second hydraulic line and the hydraulic outfeed line to be selectively opened or closed in a controllable manner.