Modeling and Designing a Variable-Displacement Open-Loop Pump

1996 ◽  
Vol 118 (2) ◽  
pp. 267-271 ◽  
Author(s):  
N. D. Manring ◽  
R. E. Johnson
Keyword(s):  
Closed Form ◽  
Dynamic Model ◽  
Dynamic Effect ◽  
Open Loop ◽  
Volume Discharge ◽  
Pumping System ◽  
Actuation System ◽  
Parameter Variations ◽  
Displacement Pump ◽  
Variable Displacement

This study develops closed-form equations that may be used to guide the up-front design of a variable-displacement pump. In particular, the initial design of the control actuation system and the controller flow-gain is considered. A dynamic model of the pumping system is also presented and the dynamic effect of parameter variations such as actuator volume, discharge-hose volume, controller flow-gain and system leakage is discussed.

Dynamic Modeling of an Indexing Valve Plate Pump

1999 ◽  
Author(s):  
J. Cho ◽  
X. Zhang ◽  
S. S. Nair ◽  
N. D. Manring
Keyword(s):  
Nonlinear Modeling ◽  
Open Loop ◽  
Valve Plate ◽  
Governing Equations ◽  
Pump Design ◽  
Pressure Port ◽  
Swash Plate ◽  
Plate Design ◽  
Displacement Pump ◽  
Variable Displacement

Abstract The swash-plate in a variable displacement pump experiences very large forces and moments that try to dislocate its position and therefore a large device is required for adequate control. In this paper, the dynamics of an alternative pump design using an indexing valve plate to position the swash-plate are reported. The indexing valve plate design is aimed at controlling the pressure transition for a piston, which is moving from a high-pressure port to a low-pressure port and back. In this paper, the governing equations for the pump are derived and the detailed open-loop, which is necessary for understanding the overall dynamic characteristics of the pump, is reported. Also, linear and nonlinear modeling approaches for the system are compared.

Transient Response and Thermal Performance of a Variable Displacement Vane Pump-Based Actuation System for Turbo Jet and Turbofan Aircraft Engines

2008 ◽  
Author(s):  
Paul J. Paluszewski ◽  
Mihir C. Desai
Keyword(s):  
Transient Response ◽  
Waste Heat ◽  
Vane Pump ◽  
Pumping System ◽  
Actuation System ◽  
Aircraft Fuel ◽  
Performance Predictions ◽  
Variable Displacement Vane Pump ◽  
Variable Displacement ◽  
And Performance

The Goodrich Variable Displacement Vane Pump (VDVP) has been described in earlier proceedings (GT2007-27948) as a potential solution to thermally constrained aircraft fuel systems. Higher fueldraulic system pressures and flow requirements have placed severe demands on fuel system thermal management techniques. Furthermore, larger heat loads from a variety of sources are constantly increasing the temperatures at which modern aircraft fuel systems are required to operate. The ongoing objective for the development of the VDVP and VDVP-based fuel systems is to minimize the waste heat returned to bulk fuel, which in turn can reduce or eliminate heat exchangers and/or increase aircraft mission capability. The earlier noted reference also describes how a twin-element pumping system can provide superior thermal and transient response when in a closed-loop pressure compensating regulation mode; one example of this is VDVP coupled to a Fixed Displacement Vane Pump (FDVP). These claims were substantiated analytically by several trade studies and performance predictions that have been performed throughout the development cycle. Since these performance predictions have been made, the aforementioned twin VDVP/FDVP pumping and control system has undergone extensive testing and development. This paper discusses the thermal and transient performance predictions and test data of the twin-element pumping system, and summarizes the development of the pumps and controls. For a given hypothetical mission cycle, the VDVP/FDVP fueldraulic system with quantified performance can be compared analytically to other pumping solutions operating in the same environment.

Energy Efficient Variable Pressure Valve-Controlled Hydraulic Actuation

2011 ◽  
Author(s):  
Marco Scopesi ◽  
Andrew Plummer ◽  
Can Du
Keyword(s):  
Variable Pressure ◽  
Input Energy ◽  
Pressure System ◽  
Load Sensing ◽  
Supply Pressure ◽  
Controlled Systems ◽  
Actuation System ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Electronic Controller

The subject of this paper is a VPVC (variable pressure valve-controlled) hydraulic actuation system, which is a hydraulic plant with variable supply pressure. The concept is similar to a load sensing system but it is implemented using an electronic controller, instead of a hydraulic one, and the flow is provided using a servo pump, instead of a variable displacement pump. The intention is to maintain a high dynamic response but substantially improve efficiency compared to a conventional system with fixed supply pressure. FPVC (fixed pressure valve-controlled) systems are unable to completely modulate the input energy due to the constant supply pressure. However, since the ability to control the energy flow is usually needed, a proportional valve for each actuator is used to dissipate the extra input energy. This leads to a simple but inefficient way to control, for example, the velocity of a piston. The idea of a VPVC system is that, instead of dissipating energy by throttling flow, it is better to generate less fluid power in the first place: this is achieved by adjusting the speed of the servo pump as well as the spool positions. In this paper, a controller for a VPVC system is presented along with numerical simulations showing a comparison with a fixed pressure system. Up to 70% energy saving is predicted.

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.

Avoiding Compressor Surge During Emergency Shutdown Hybrid Turbine Systems

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Paolo Pezzini ◽  
David Tucker ◽  
Alberto Traverso
Keyword(s):  
Fuel Cell ◽  
System Analysis ◽  
Risk Mitigation ◽  
Dynamic Effect ◽  
Transient Behavior ◽  
Open Loop ◽  
Department Of Energy ◽  
Mitigation Strategies ◽  
Emergency Shutdown ◽  
Compressor Surge

A new emergency shutdown procedure for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test, and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide a means of quantifying risk mitigation strategies. An open-loop system analysis regarding the dynamic effect of bleed air, cold air bypass, and load bank is presented in order to evaluate the combination of these three main actuators during emergency shutdown. In the previous Hybrid control system architecture, catastrophic compressor failures were observed when the fuel and load bank were cut off during emergency shutdown strategy. Improvements were achieved using a nonlinear fuel valve ramp down when the load bank was not operating. Experiments in load bank operation show compressor surge and stall after emergency shutdown activation. The difficulties in finding an optimal compressor and cathode mass flow for mitigation of surge and stall using these actuators are illustrated.

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.

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