Fluid for high-pressure hydraulic systems

1983 ◽  
Vol 19 (1) ◽  
pp. 35-36
Author(s):  
L. G. Konovich ◽  
A. S. Zhurba ◽  
A. P. Furman
Keyword(s):  
High Pressure ◽  
Hydraulic Systems

scholarly journals Data-driven Adaptive Thresholding Model for Real-time Valve Delay Estimation in Digital Pump/Motors

2020 ◽  
Author(s):  
Abdallah Chehade ◽  
Farid Breidi ◽  
Keith Scott Pate ◽  
John Lumkes
Keyword(s):  
High Pressure ◽  
Real Time ◽  
Domain Knowledge ◽  
Operating Conditions ◽  
Delay Model ◽  
Hydraulic Systems ◽  
Pressure Transducers ◽  
Statistical Behavior ◽  
Shift Detection ◽  
And Performance

Valve characteristics are an essential part of digital hydraulics. The on/off solenoid valves utilized on many of these systems can significantly affect the performance. Various factors can affect the speed of the valves causing them to experience various delays, which impact the overall performance of hydraulic systems. This work presents the development of an adaptive statistical based thresholding real-time valve delay model for digital Pump/Motors. The proposed method actively measures the valve delays in real-time and adapts the threshold of the system with the goal of improving the overall efficiency and performance of the system. This work builds on previous work by evaluating an alternative method used to detect valve delays in real-time. The method used here is a shift detection method for the pressure signals that utilizes domain knowledge and the system’s historical statistical behavior. This allows the model to be used over a large range of operating conditions, since the model can learn patterns and adapt to various operating conditions using domain knowledge and statistical behavior. A hydraulic circuit was built to measure the delay time experienced from the time the signal is sent to the valve to the time that the valve opens. Experiments were conducted on a three piston in-line digital pump/motor with 2 valves per cylinder, at low and high pressure ports, for a total of six valves. Two high frequency pressure transducers were used in this circuit to measure and analyze the differential pressure on the low and high pressure side of the on/off valves, as well as three in-cylinder pressure transducers. Data over 60 cycles was acquired to analyze the model against real time valve delays. The results show that the algorithm was successful in adapting the threshold for real time valve delays and accurately measuring the valve delays. 

Micro Surface Shaping for the High-Pressure Operation of Piston Machines With Water as a Working Fluid

2015 ◽  
Author(s):  
Meike H. Ernst ◽  
Monika Ivantysynova
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Working Fluid ◽  
Hydraulic Systems ◽  
Machinery Construction ◽  
Pressure Buildup ◽  
Piston Cylinder ◽  
Low Viscosity ◽  
Load Carrying ◽  
Surface Shaping

Oil is the main working fluid used in the hydraulics industry today — but water is nonflammable, environmentally friendly and cheap: it is the better choice of working fluid for hydraulic systems. However, there is one caveat. Water’s extremely low viscosity undermines its ability to carry load. In forest machinery, construction machinery, and aircraft systems, today’s hydraulic circuits have high operating pressures, with typical values between 300 and 420 bar. These high pressures create the need for high load-carrying abilities in the fluid films of the tribological interfaces of pumps and motors. The most challenging of these interfaces is the piston-cylinder interface of swashplate type piston machines, because the fluid must balance the entire piston side load created in this design. The low viscosity of the water turns preventing metal-to-metal contact into quite a challenge. Fortunately, an understanding of how pressure builds and shifts about in these piston-cylinder lubrication interfaces, coupled with some clever micro surface shaping, can allow engineers to drastically increase the load-carrying ability of water. As part of this research, numerous different micro surface shaping design ideas have been simulated using a highly advanced non-isothermal multi-physics model developed at the Maha Fluid Power Research Center. The model calculates leakage, power losses, film thickness and pressure buildup in the piston-cylinder interface over the course of one shaft revolution. The results allow for the comparison of different surface shapes, such as axial sine waves along the piston, or a barrel-shaped piston profile. This paper elucidates the effect of those surface profiles on pressure buildup, leakage, and torque loss in the piston-cylinder interface of an axial piston pump running at high pressure with water as the lubricant.

scholarly journals Theoretical and Experimental Studies of a Digital Flow Booster Operating at High Pressures and Flow Rates

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 211 ◽  
Author(s):  
Chenggang Yuan ◽  
Vinrea Lim Mao Lung ◽  
Andrew Plummer ◽  
Min Pan
Keyword(s):  
Energy Efficiency ◽  
High Pressure ◽  
Flow Rate ◽  
High Energy ◽  
Control Flow ◽  
Fluid Power ◽  
Analytical Models ◽  
Operating Pressure ◽  
Hydraulic Systems ◽  
Flow Rates

The switched inertance hydraulic converter (SIHC) is a new technology providing an alternative to conventional proportional or servo-valve-controlled systems in the area of fluid power. SIHCs can adjust or control flow and pressure by means of using digital control signals that do not rely on throttling the flow and dissipation of power, and provide hydraulic systems with high-energy efficiency, flexible control, and insensitivity to contamination. In this article, the analytical models of an SIHC in a three-port flow-booster configuration were used and validated at high operating pressure, with the low- and high-pressure supplies of 30 and 90 bar and a high delivery flow rate of 21 L/min. The system dynamics, flow responses, and power consumption were investigated and theoretically and experimentally validated. Results were compared to previous results achieved using low operating pressures, where low- and high-pressure supplies were 20 and 30 bar, and the delivery flow rate was 7 L/min. We concluded that the analytical models could effectively predict SIHC performance, and higher operating pressures and flow rates could result in system uncertainties that need to be understood well. As high operating pressure or flow rate is a common requirement in hydraulic systems, this constitutes an important contribution to the development of newly switched inertance hydraulic converters and the improvement of fluid-power energy efficiency.

scholarly journals Determination of basal hydraulic systems based on subglacial high-pressure pump experiments

2005 ◽  
Vol 40 ◽  
pp. 37-42 ◽  
Author(s):  
Gaute Lappegard ◽  
Jack Kohler
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Water Pressure ◽  
Drainage System ◽  
Load Cell ◽  
Low Flow ◽  
Hydraulic Systems ◽  
High Pressure Pump ◽  
Pressure Transducers ◽  
Fast Flow

AbstractWe have conducted short-term pump experiments with pump pressures exceeding ice overburden to study the seasonality of the subglacial hydraulic system of Engabreen, Norway. Data were collected from load cells installed flush with the ice–bedrock interface and pressure transducers installed in boreholes leading from bedrock tunnels underneath the glacier to the ice–bedrock interface. The water-pressure recordings, seen in relation with the load-cell record, show the existence of hydraulically connected vs unconnected bed areas. Monitored boreholes have been used to inject water at high pressures. Each experiment led to the growth of a high-pressure water cavity whose spatial extent could be inferred from load-cell and pressure transducer records. Post-pump pressures were low after summer pump tests and close to ice-overburden level after winter pump experiments. We conclude that drainage takes place in a fast-flow, low-pressure, channel-based drainage system during summer, and a low-flow, high-pressure, linked-cavity drainage system during winter.

scholarly journals Mobile Processing of Pipeline Assembly Units

2019 ◽  
Vol 297 ◽  
pp. 02008
Author(s):  
Sergey Safonov ◽  
Vladislav Smolentsev ◽  
Yana Smolentseva
Keyword(s):  
High Pressure ◽  
Contact Method ◽  
Technological Equipment ◽  
Electric Contact ◽  
Hydraulic Systems ◽  
Emergency Situations ◽  
Traditional Processing ◽  
The Cost ◽  
Limited Scope

The paper addresses the issues, related to the preparation of pipeline docking elements during the repair and recovery of pipelines in field conditions with a limited scope of technological equipment. It has been shown that the replacement of traditional processing methods by combined types of preparation of replaceable pipeline sections for welding can improve the accuracy of mating elements, preventing the occurrence of burrs at the joint. This enhances the quality of repair, ensures the tightness of pipelines, reduces the cost of operation and the period of pipeline recovery. The application of the electric-contact method of processing assembly units, based on the proposed schemes, makes it possible, without sophistication of mobile servicing means, to timely restore the performance of products, eliminating the causes of emergency situations in construction and during operation of pipelines in hydraulic systems of transport machines, especially when used under operation in high-pressure media.

High Pressure Hydraulic Systems

1943 ◽  
Author(s):  
Philip De Beixedon
Keyword(s):  
High Pressure ◽  
Hydraulic Systems

Friction characteristics of a multi-chamber cylinder for digital hydraulics

2015 ◽  
Vol 230 (5) ◽  
pp. 685-698
Author(s):  
Seung Ho Cho ◽  
Olli Niemi-Pynttäri ◽  
Matti Linjama
Keyword(s):  
High Pressure ◽  
Friction Force ◽  
Equation Of Motion ◽  
Binary Digit ◽  
Hydraulic Systems ◽  
Secondary Control ◽  
Friction Characteristics ◽  
Mass Load ◽  
Load Conditions ◽  
Mobile Machine

This paper deals with the issue of defining friction characteristics of a multi-chamber cylinder for digital hydraulics. Using a multi-chamber cylinder under a set of supply pressures, friction characteristics are experimentally investigated for a range of velocity according to load conditions. A binary digit-based pressure e.g., high pressure or low pressure has been applied to each chamber. The friction force is measured based on the equation of motion using measured values of the pressures in the chambers of the multi-chamber cylinder and the position of the piston. As a mechanism to load the multi-chamber cylinder, a 1-Degree of Freedom (DOF) boom mockup mimicking a medium-sized mobile machine boom has been constructed. Then it has been utilized to test the motion of the cylinder under different mass–load conditions. It is shown that the cylinder states do not dominantly affect the friction force of a multi-chamber cylinder, comparing the effect of other parameter such as mass load and velocity, which is expected to be useful for the secondary control of digital hydraulic systems.

Modelling and Simulation of a Cartridge Pressure Amplifier

2018 ◽  
Author(s):  
Barbara Zardin ◽  
Giovanni Cillo ◽  
Massimo Borghi ◽  
Peter Zavadinka ◽  
Juraj Hanusovsky
Keyword(s):  
High Pressure ◽  
Power Saving ◽  
Hydraulic Cylinder ◽  
Modelling And Simulation ◽  
Normal Operation ◽  
Design Parameters ◽  
Hydraulic Pressure ◽  
Hydraulic Systems ◽  
Pressure Work ◽  
Narrow Space

Hydraulic pressure amplifiers of the cylinder type are much appreciated in hydraulic systems where high pressure work is needed only for a limited period of time, while during the remaining duty cycle the system operates at a standard level of pressure. The use of these elements allows the designer not to oversize the system, which will perform the work with a considerable power saving, confining the high pressure operation only on the side of the hydraulic cylinder. This works describes the modelling and simulation of a compact cartridge pressure amplifier for linear actuators. The cartridge amplifier is able to double or more the pressure in the system when needed and to not interfere during normal operation of the system. It has been designed to fit in the narrow space of the rod of normal hydraulic cylinder, being extremely compact and efficient. Designing such a component and the study of the main design parameters influence have required a strong work of modelling and simulation, performed with a lumped parameters approach to depict the dynamic behaviour of the amplifier. This work illustrates the building of the model and a first comparison between simulated and experimental data. Moreover, the simulation activity is enlarged to analysis of the influence of some operating and design parameters on the amplifier dynamic behavior.

scholarly journals Bench tests of a support system of a powered roof support’s hydraulic leg aimed at minimizing consequences of leaks

2019 ◽  
Vol 134 ◽  
pp. 01003
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny ◽  
Marcin Brzózka ◽  
Ryszard Diederichs
Keyword(s):  
High Pressure ◽  
Support System ◽  
Extraction Process ◽  
Main Element ◽  
Hydraulic Systems ◽  
Working Pressure ◽  
Bench Tests ◽  
Main Component ◽  
Valve Block ◽  
Roof Support

Effectiveness of a powered roof support significantly impacts on the efficiency and safety of a mining process. The main element of the support is a hydraulic leg which transfers loads imposed by the rock mass. One of the basic issues occurring during the extraction process are internal and external leaks of hydraulic systems. A new support system was designed to limit and later eliminate the consequences of such leaks. Its main component is a valve block equipped with two independent check valves. This solution allows to maintain high pressure in both chambers of a leg despite leaks. The article discusses the developed solution and presents preliminary results of bench tests of a leg equipped with the new block and loaded dynamically. The results are promising, and the tested block fulfils its task by maintaining the working pressure in the leg during load.

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