Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2009 ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 79%, and total system losses by 66%. Design equations are also derived. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly important as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency an on/off valve that was 5 times faster.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states when the switching times are not negligible. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 81% and total system losses by 64%. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly beneficial as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency of an on/off valve that was 4.4 times faster.

STEAM: A Mobile Hydraulic System With Engine Integration

2013 ◽  
Author(s):  
Milos Vukovic ◽  
Sebastian Sgro ◽  
Hubertus Murrenhoff
Keyword(s):  
Hydraulic System ◽  
High Efficiency ◽  
Combustion Engine ◽  
Low Cost ◽  
Total System ◽  
Hydraulic Systems ◽  
Pressure System ◽  
Operating Modes ◽  
Hydraulic Design ◽  
Displacement Pump

In recent years, research institutions worldwide have developed a number of new mobile hydraulic systems. Despite their improved energy efficiency, these systems have yet to gain market acceptance due to their related increase in component costs and decrease in robustness. At the Institute for Fluid Power Drives and Controls in Aachen, a new system for mobile machines, named STEAM (Steigerung der Energieeffizienz in der Arbeitshydraulik mobiler Arbeitsmaschinen), is being developed using inexpensive off-the-shelf components. The aim is to improve the total system efficiency by considering all the subsystems in the machine. This is done by integrating the internal combustion engine (ICE) into the hydraulic design process. By using a constant pressure system in combination with a low-cost fixed displacement pump the hydraulic system is designed to ensure the ICE experiences a constantly high load in a region of high efficiency, so-called point operation. To decrease the hydraulic losses incurred when supplying the linear actuators with flow, an additional intermediate pressure rail with independent metering edges is used. This enables various energy efficient discrete operating modes, including energy regeneration and recuperation.

Energy Consumption Model of the Force Application Hydraulic System for Friction Welding Machine

2014 ◽  
Vol 536-537 ◽  
pp. 1361-1364
Author(s):  
Zheng Qiang Yang ◽  
Sui Geng Du
Keyword(s):  
Energy Consumption ◽  
Friction Welding ◽  
Hydraulic System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Operating Characteristics ◽  
Force Application ◽  
Welding Machine ◽  
Output Flow ◽  
Low Efficiency

For the problem of low efficiency of the ordinary hydraulic systems of the friction welding machine, operating characteristics and efficiency model of the force application hydraulic system of friction welding machine are studied. The energy consumption characteristics of traditional welding machine are simulated, the efficiency characteristics of the force application hydraulic system of friction welding machine is studied, and the energy consumption and efficiency model are deduced. According to theoretical analysis, the system efficiency can be improved by changing pump output flow and relief output flow. The simulation results show that the working efficiency of the new system can be enhanced to 24%. The new friction welding hydraulic system was used in actual production and the system efficiency can be improved to 22%.

Paper 10: Unsteady Incompressible Flow through Hydraulic Systems

1966 ◽  
Vol 181 (1) ◽  
pp. 134-143
Author(s):  
B. W. Roberts
Keyword(s):  
Incompressible Fluid ◽  
Hydraulic System ◽  
Wave Speed ◽  
Characteristic Length ◽  
Dynamic Pressure ◽  
Bernoulli Equation ◽  
Hydraulic Systems ◽  
Worked Example ◽  
Hydraulic Machines ◽  
Flow Through

The unsteady Bernoulli equation applied to an incompressible fluid may be used to calculate the unsteady pressures and velocities in a hydraulic system involving pipework and hydraulic machines. The effects of changes in the dynamic pressure, fluid friction, and the quasi-steady pump or turbine characteristics can be included. The results are applicable to situations in which the time describing the system disturbances is very much slower than the characteristic length of the system divided by the wave speed. In other words, the approach is similar to a rigid water-column theory used in water-hammer analysis. A worked example is also included.

Transmission of Fluid Power by Pulsating-Flow (P-F) Concept in Hydraulic Systems

1966 ◽  
Vol 88 (2) ◽  
pp. 316-321 ◽  
Author(s):  
Cheng-Kuo Weng
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Power Transmission ◽  
Pulsating Flow ◽  
Fluid Power ◽  
Experimental Investigations ◽  
System Efficiency ◽  
Test Results ◽  
Hydraulic Systems ◽  
Line Loss

Theoretical and experimental investigations have been made on fluid-power transmission in hydraulic systems by pulsating flow. In particular, the system efficiency and the viscosity effect on the dynamic response of pulsating flow in the fluid line have been studied. Test results on the fluid-line dynamic response and on the system efficiency that obtained from the line-loss test setup and the miniaturized P-F hydraulic system setup, respectively, are presented.

Novel Hydraulic System for Mini Excavators Without Electronic Controls

2016 ◽  
Author(s):  
Ken Sugimura ◽  
Hubertus Murrenhoff
Keyword(s):  
Urban Areas ◽  
Hydraulic System ◽  
Mechanical Valve ◽  
The Novel ◽  
Hydraulic Systems ◽  
Pressure System ◽  
System Architectures ◽  
Load Sensing ◽  
Controlled Systems ◽  
Hydraulic Excavators

The target application of this study is hydraulic excavators, which are one of the most common machines found at construction sites across the world. Road constructions and improvements, laying operation of cables or pipes and building can be seen in urban areas and digging and dumping operations of natural resource are done in country regions. For the construction site in urban areas, mini hydraulic excavators with operating weights up to 6 tons are often used and they make up more than 60% of the total hydraulic excavators market [1]. In recent years, a number of new system architectures for mobile hydraulic systems have been proposed. Examples of such improved architectures are displacement control, transformer systems and valve controlled systems with multiple pressure rails. For these systems, electronic controls are always used. Although these new methods are promising, they cannot be applied to mini-excavators, because today’s mini-hydraulic excavators do not use electronic controls as this would increase costs and make the system complex. Therefore, the goal of this study is to propose a fully hydro-mechanical valve controlled constant pressure system, which can be applied to mini-excavators in the future. This paper begins by introducing the details of this novel hydraulic system and shows its advantages. Using a simulation model of an 18 ton excavator, it is confirmed that the novel system functions well and the energy efficiency is compared to a conventional Load Sensing system. The simulation results show that the novel system can save 22% and 24% of fuel in leveling and 90° dig-dump cycles respectively.

Modeling of Cavitation-Induced Air Release Phenomena in Micro-Orifice Flows

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Hans-Arndt Freudigmann ◽  
Aaron Dörr ◽  
Uwe Iben ◽  
Peter F. Pelz
Keyword(s):  
Mass Transfer ◽  
Hydraulic System ◽  
System Simulation ◽  
Air Bubbles ◽  
Hydraulic Systems ◽  
Modeling Approach ◽  
Diffusive Mass Transfer ◽  
Orifice Flow ◽  
Flow Through ◽  
Dissolved Air

Impurities like air bubbles in hydraulic liquids can significantly affect the performance and reliability of hydraulic systems. The aim of this study was to develop a model suited for hydraulic system simulation to determine the rate of degassing of dissolved air in a micro-orifice flow at cavitating conditions. An existing model for the flow through a micro-orifice was extended to account for the generation of vapor which is suggested to play the key-role for the degassing mechanism. In comparison with measurements, the results of the modeling approach imply that diffusive mass transfer of dissolved air into generated vapor cavities is the dominating mechanism for the observed air release phenomena.

Damping of Self-Excited Pressure Pulsations in Petrodiesel Pipeline

2014 ◽  
Vol 630 ◽  
pp. 375-382 ◽  
Author(s):  
Daniel Himr ◽  
Vladimir Haban
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Control Valve ◽  
Sampling Frequency ◽  
Pressure Pulsations ◽  
One Dimensional ◽  
Fuel Storage ◽  
Excited Oscillation ◽  
Subsequent Measurement ◽  
And Control

A pumping station in a fuel storage suffered from pressure pulsations in a petrodiesel pipeline. Check valves protecting the station against back flow made a big noise when disc hit a seat. Due to employees complaints we were asked to solve the problem, which could lead to serious mechanical problems. Pressure measurement in the pipeline showed great pulsations, which were caused by self-excited oscillation of control valves at the downstream end of pipeline. The operating measurement did not catch it because of too low sampling frequency. One dimensional numerical model of the whole hydraulic system was carried out. The model consisted of check valve, pipeline and control valve, which could oscillate, so it was possible to simulate the unsteady flow. When the model was validated, a vessel with nitrogen was added to attenuate pressure pulsations. According to the results of numerical simulation, the vessel was installed on the location. Subsequent measurement proved noticeably lower pulsations and almost no noise.

Dynamic balance analysis of contamination control for hydraulic systems based on dynamic filtration ratio

2016 ◽  
Vol 68 (1) ◽  
pp. 45-51
Author(s):  
Guangying Ma ◽  
Shurong Ning ◽  
Yunlong Hu ◽  
jun Gao
Keyword(s):  
Hydraulic System ◽  
Dynamic Balance ◽  
Contamination Level ◽  
Hydraulic Systems ◽  
Level Control ◽  
Content Type ◽  
Contamination Control ◽  
Precise Control ◽  
Dynamic Filtration ◽  
The Relationship

Purpose – The aim of this study is to establish a dynamic model of the filtration ratio. For the problem that the measured value of the filtration ratio is far less than the theoretical value in the actual hydraulic filtering system, the paper aims to find the relationship between the filtration ratio and the parameters of the hydraulic systems, such as the contamination level and the dirt-holding quantity of the filter. Design/methodology/approach – The paper opted for the method of experimental analysis and simulation to determine the relationship between the filtration ratio and the parameters of the hydraulic system, and established a dynamic filtration ratio model. Findings – The paper provides a preliminary model of dynamic filtration ratio, and the model shows that the filtration ratio is exponentially related to the contamination level and the dirt-holding quantity. Different filters have different influence coefficients. The filtering capacity for a certain particle size and the contamination level control of the filter for different hydraulic systems can be judged according to the dynamic balance equation of hydraulic systems. Originality/value – The paper is useful in the selection of filters and in the precise control of the contamination level of the hydraulic system.

Instability Modes of Two-Phase Flows in a Mixing-Layer Microdevice

2001 ◽  
Author(s):  
Tak For Yu ◽  
Sylvanus Yuk Kwan Lee ◽  
Yitshak Zohar ◽  
Man Wong
Keyword(s):  
Gas Flow ◽  
Mixing Layer ◽  
Fluid Flows ◽  
Two Phase Flows ◽  
Two Phase ◽  
Pressure Distributions ◽  
Instability Modes ◽  
In Series ◽  
Mass Flow Rates ◽  
Flow Through

Abstract Extensive development of biomedical and chemical analytic microdevices involves microscale fluid flows. Merging of fluid streams is expected to be a key feature in such devices. An integrated microsystem consisting of merging microchannels and distributed pressure microsensors has been designed and characterized to study this phenomenon on a microscale. The two narrow, uniform and identical channels merged smoothly into a wide, straight and uniform channel downstream of a splitter plate. All of the devices were fabricated using standard micromachining techniques. Mass flow rates and pressure distributions were measured for single-phase gas flow in order to characterize the device. The experimental results indicated that the flow developed when both inlets were connected together to the gas source could be modeled as gas flow through a straight and uniform microchannel. The flow through a single branch while the other was blocked, however, could be modeled as gas flow through a pair of microchannels in series. Flow visualizations of two-phase flows have been conducted when driving liquid and gas through the inlet channels. Several instability modes of the gas/liquid interface have been observed as a function of the pressure difference between the two streams at the merging location.

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