Experimental Studies of a Novel Alternating Flow (AF) Hydraulic Pump

2017 ◽  
Author(s):  
Ryan J. Foss ◽  
Mengtang Li ◽  
Eric J. Barth ◽  
Kim A. Stelson ◽  
James D. Van de Ven
Keyword(s):  
Phase Angle ◽  
Experimental Studies ◽  
Companion Paper ◽  
Pump Efficiency ◽  
Operating Pressure ◽  
Displacement Control ◽  
Displacement Pump ◽  
Pressure Dynamics ◽  
Variable Displacement ◽  
Control Circuits

The ideal variable displacement pump for a displacement control circuit is efficient across a wide operating range and readily mounted on a common shaft with multiple pumps. This paper presents a novel variable displacement pump architecture for displacement control circuits that uses the concept of alternating flow (AF) between piston pairs that share a common cylinder. The displacement is adjusted by varying the phase angle between the piston pairs. When the pistons are in phase, the pump displacement is at a maximum and when the pairs of pistons are out of phase, fluid is shuttled between the pistons and the pump produces no net flow. A prototype of the AF pump was constructed from two inline triplex pumps that were modified so that three piston pairs were created. The crankshafts of the two pumps were connected via a sprocket-and-chain transmission. The sprockets allow for accurate measurement of the phase angle, which is adjusted, in this early phase prototype, by disassembling the chain and shifting the sprockets. The prototype AF pump was then mounted to the test stand and experiments were conducted to map the AF pump efficiency and cylinder pressure dynamics across a range of operating pressure, speed, and displacement. The AF pump’s efficiency was measured for 8 diferent phase angles with an efficiency of near 90% at full flow and 65% at 36% displacement. The experimental results were compared to simulation results, presented in a companion paper at this conference.

Software Enabled Variable Displacement Pumps: Experimental Studies

2006 ◽  
Author(s):  
Michael B. Rannow ◽  
Haink C. Tu ◽  
Perry Y. Li ◽  
Thomas R. Chase
Keyword(s):  
Experimental Studies ◽  
Check Valve ◽  
Design Parameters ◽  
Duty Ratio ◽  
System Response ◽  
Experimental Apparatus ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Valve Control ◽  
Variable Displacement Pumps

The majority of hydraulic systems are controlled using a metering valve or the use of variable displacement pumps. Metering valve control is compact and has a high control bandwidth, but it is energy inefficient due to throttling losses. Variable displacement pumps are far more efficient as the pump only produces the required flow, but comes with the cost of additional bulk, sluggish response, and added cost. In a previous paper [1], a hydromechanical analog of an electronic switch-mode power supply was proposed to create the functional equivalent of a variable displacement pump. This approach combines a fixed displacement pump with a pulse-width-modulated (PWM) on/off valve, a check valve, and an accumulator. The effective pump displacement can be varied by adjusting the PWM duty ratio. Since on/off valves exhibit low loss when fully open or fully closed, the proposed system is potentially more energy efficient than metering valve control, while achieving this efficiency without many of the shortcomings of traditional variable displacement pumps. The system also allows for a host of programmable features that can be implemented via control of the PWM duty ratio. This paper presents initial experimental validation of the concept as well as an investigation of the system efficiency. The experimental apparatus was built using available off-the-shelf components and uses a linear proportional spindle valve as the PWM valve. Experimental results confirm that the proposed approach can achieve variable control function more efficiently than a valve controlled system, and that by increasing the PWM frequency and adding closed-loop control can decrease system response times and of the output ripple magnitude. Sources of inefficiency and their contributions are also investigated via modeling, simulation and are validated by experiments. These indicate design parameters for improving inefficiency.

Theoretical and experimental studies of the steady-state performance of a primary and secondary-controlled closed-circuit hydrostatic drive

2019 ◽  
Vol 233 (5) ◽  
pp. 1024-1035
Author(s):  
Ajit Kumar Pandey ◽  
Alok Vardhan ◽  
K Dasgupta
Keyword(s):  
Steady State ◽  
System Modeling ◽  
Experimental Studies ◽  
Simulation Method ◽  
Closed Circuit ◽  
Displacement Pump ◽  
Torque Loss ◽  
Variable Displacement ◽  
Graph Simulation ◽  
Steady State Performance

In this article, performance of a closed-circuit hydrostatic drive in primary and secondary mode of operations has been studied through theory and experiment. This drive consists of a variable displacement pump that supplies pressurized fluid to a variable displacement hydro-motor of bent axis design. Bond graph simulation method is adopted for system modeling. In the model, the losses of the drive are accounted by suitable resistive elements, and their characteristics are identified through experiments. The predicted drive’s performances are studied with respect to the overall efficiency, torque loss (%), and slip at different torque levels which are also validated experimentally. The investigation made in the article identifies the efficient zone of operation of the drive which will be useful to the practicing engineers to select such a drive used in heavy constructional equipment. From the steady-state performance of the pump and the motor, their critical control parameters are identified. The studies may be useful for the design of the suitable control strategy to obtain the optimum performance of the drives.

Energy Efficiency of Displacement Control Drive Systems in Hydraulic Forming Presses

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Christer Schenke ◽  
Jürgen Weber
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Deep Drawing ◽  
Control Methods ◽  
Displacement Control ◽  
Valve Drive ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Drive Systems ◽  
Two Alternatives

Hydraulic deep drawing presses are manifold machines that can be used for a number of use cases. The general need for the reduction of the energy consumption of industrial machines forces press manufacturers and owners to optimize their machines and processes. This article presents methods for the analysis and optimization of the drive systems of a hydraulic deep drawing press with four-point die cushion. For the slide drive, two alternatives of control methods for speed variable displacement pumps are compared to the conventionally used displacement pump with a constant speed. For the drive of the die cushion, two displacement control drive systems are compared to a conventional valve drive system.

Energy-saving design of variable-displacement bi-directional pump-controlled electrohydraulic system

2020 ◽  
pp. 095965182097389
Author(s):  
Samir Kumar Hati ◽  
Nimai Pada Mandal ◽  
Dipankar Sanyal
Keyword(s):  
Energy Saving ◽  
Absolute Error ◽  
Fast Response ◽  
Maximum Energy ◽  
Radial Clearance ◽  
Simulation Based Design ◽  
Simulation Based ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Axial Piston

Losses in control valves drag down the average overall efficiency of electrohydraulic systems to only about 22% from nearly 75% for standard pump-motor sets. For achieving higher energy efficiency in slower systems, direct pump control replacing fast-response valve control is being put in place through variable-speed motors. Despite the promise of a quicker response, displacement control of pumps has seen slower progress for exhibiting undesired oscillation with respect to the demand in some situations. Hence, a mechatronic simulation-based design is taken up here for a variable-displacement pump–controlled system directly feeding a double-acting single-rod cylinder. The most significant innovation centers on designing an axial-piston pump with an electrohydraulic compensator for bi-directional swashing. An accumulator is conceived to handle the flow difference in the two sides across the load piston. A solenoid-driven sequence valve with P control is proposed for charging the accumulator along with setting its initial gas pressure by a feedforward design. Simple proportional–integral–derivative control of the compensator valve is considered in this exploratory study. Appropriate setting of the gains and critical sizing of the compensator has been obtained through a detailed parametric study aiming low integral absolute error. A notable finding of the simulation is the achievement of the concurrent minimum integral absolute error of 3.8 mm s and the maximum energy saving of 516 kJ with respect to a fixed-displacement pump. This is predicted for the combination of the circumferential port width of 2 mm for the compensator valve and the radial clearance of 40 µm between each compensator cylinder and the paired piston.

scholarly journals Ice nucleation efficiency of AgI: review and new insights

2016 ◽  
Author(s):  
Claudia Marcolli ◽  
Baban Nagare ◽  
André Welti ◽  
Ulrike Lohmann
Keyword(s):  
Water Saturation ◽  
Experimental Studies ◽  
Freezing Temperature ◽  
Nucleating Agent ◽  
Companion Paper ◽  
Chem Phys ◽  
Ice Nucleation ◽  
Lattice Match ◽  
Ice Nuclei ◽  
Immersion Freezing

Abstract. AgI is one of the best investigated ice nuclei. It has relevance for the atmosphere since it is used for glaciogenic cloud seeding. Theoretical and experimental studies over the last sixty years provide a complex picture of silver iodide as ice nucleating agent with conflicting and inconsistent results. This review compares experimental ice nucleation studies in order to analyse the factors that influence the ice nucleation ability of AgI. We have performed experiments to compare contact and immersion freezing by AgI. This is one of three papers that describe and analyse contact and immersion freezing experiments with AgI. In Nagare et al. (Nagare, B., Marcolli, C., Stetzer, O., and Lohmann, U.: Comparison of measured and calculated collision efficiencies at low temperatures, Atmos. Chem. Phys., 15, 13759–13776, doi:10.5194/acp-15-13759-2015, 2015) collision efficiencies based on contact freezing experiments with AgI are determined and compared with theoretical formulations. In a companion paper, contact freezing experiments are compared with immersion freezing experiments conducted with AgI, kaolinite, and ATD as ice nuclei. The following picture emerges from this analysis: The ice nucleation ability of AgI seems to be enhanced when the AgI particle is on the surface of a droplet, which is indeed the position that a particle takes when it can freely move in a droplet. Ice nucleation by particles with surfaces exposed to air, depends on water adsorption. AgI surfaces seem to be most efficient as ice nuclei when they are exposed to relative humidity at or even above water saturation. For AgI particles that are totally immersed in water, the freezing temperature increases with increasing AgI surface area. Higher threshold freezing temperature seem to correlate with improved lattice matches as can be seen for AgI-AgCl solid solutions and 3AgI•NH4I•6H2O, which have slightly better lattice matches with ice than AgI and also higher threshold freezing temperatures. However, the effect of a good lattice match is annihilated when the surfaces have charges. Also, the ice nucleation ability seems to decrease during dissolution of AgI particles. This introduces an additional history and time dependence of ice nucleation in cloud chambers with short residence times.

Robust Nonlinear Control of a Novel Indexing Valve Plate Pump: Simulation Studies

2002 ◽  
Vol 124 (4) ◽  
pp. 613-616 ◽  
Author(s):  
X. Zhang ◽  
S. S. Nair ◽  
N. D. Manring
Keyword(s):  
Pressure Control ◽  
Plate Motion ◽  
Nonlinear Simulation ◽  
Response Characteristics ◽  
Model Free ◽  
Swash Plate ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Robust Adaptive ◽  
Improved Performance

A robust adaptive pressure control strategy is proposed for a novel indexing variable-displacement pump. In the proposed approach, parametric uncertainties and unmodeled dynamics are identified to the extent possible using a model free learning network and used to decouple the dynamics using physical insights derived from careful reduced order modeling. The swash plate motion control is then carefully designed to provide the desired pressure response characteristics showing improved performance with learning. The proposed control framework and designs are validated using a detailed nonlinear simulation model.

Symmetric Single Rod Cylinders With Variable Piston Area? A Comprehensive Approach to the Right Solution

2018 ◽  
Author(s):  
Giacomo Kolks ◽  
Jürgen Weber
Keyword(s):  
Experimental Validation ◽  
Design Space ◽  
Solution Space ◽  
Hydraulic Cylinder ◽  
Load Cycle ◽  
Displacement Control ◽  
Comprehensive Description ◽  
Subsequent Step ◽  
Variable Displacement ◽  
The Right

In contrast to rotational hydraulic displacement units, such as pumps or motors, conventional hydraulic cylinder actuators do not allow a continuous variation of their displacement quantity: the piston area is regarded constant. In order to adapt to varying load and velocity requirements in a load cycle under torque restrictions of the driving motor, cylinder drives often implement pumps with variable displacement. In this paper, cylinders with discretely variable effective piston area by means of variable circuitry of multi-chamber cylinders are discussed. Hydraulic symmetry or constant asymmetry of the hydraulic cylinder are traits of the cylinder that are required to fit the cylinder to pump structures for closed-circuit displacement control, as given in electro-hydrostatic compact drives (ECD). A methodology to generate all possible solutions of variable area cylinders under the constraint of ECD requirements is proposed. A comprehensive description of the solution space is given, based on combinatorics and solution of equation systems. The methodology dealing with abstract cylinder areas is backed up by a general approach to describe the mechanical cylinder design space to combine multiple cylinder areas in one structural unit. Examples for design of three and four area cylinders are given and results are discussed. The paper concludes with the development of a demonstrator design to allow experimental validation in a subsequent step.

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