Showing papers on "Hydraulic machinery published in 2013"

Hydraulic circuit for automatic transmission

Abstract: A hydraulic circuit may include a proportional control solenoid valve controlling hydraulic pressure such that an operating hydraulic pressure required by the friction member is supplied to the friction member; a supply hydraulic path connecting the proportional control solenoid valve with the friction member, and adapted to supply hydraulic pressure controlled by the proportional control solenoid valve to the friction member; and a switch valve disposed in the supply hydraulic path so as to selectively open/close the supply hydraulic path

Discrete Displacement Hydraulic Power Take-Off System for the Wavestar Wave Energy Converter

Abstract: The Wavestar Wave Energy Converter (WEC) is a multiple absorber concept, consisting of 20 hemisphere shaped floats attached to a single platform. The heart of the Wavestar WEC is the Power Take-Off (PTO) system, converting the wave induced motion of the floats into a steady power output to the grid. In the present work, a PTO based on a novel discrete displacement fluid power technology is explored for the Wavestar WEC. Absorption of power from the floats is performed by hydraulic cylinders, supplying power to a common fixed pressure system with accumulators for energy smoothing. The stored pressure energy is converted into electricity at a steady pace by hydraulic motors and generators. The storage, thereby, decouples the complicated process of wave power absorption from power generation. The core for enabling this PTO technology is implementing a near loss-free force control of the energy absorbing cylinders. This is achieved by using special multi-chambered cylinders, where the different chambers may be connected to the available system pressures using fast on/off valves. Resultantly, a Discrete Displacement Cylinder (DDC) is created, allowing near loss free discrete force control. This paper presents a complete PTO system for a 20 float Wavestar based on the DDC. The WEC and PTO is rigorously modeled from incident waves to the electric output to the grid. The resulting model of +600 states is simulated in different irregular seas, showing that power conversion efficiencies above 70% from input power to electrical power is achievable for all relevant sea conditions.

Drive Cycle Prediction and Energy Management Optimization for Hybrid Hydraulic Vehicles

Abstract: Increasing costs of fossil fuels and the requirement of reduced CO2 emissions for road vehicles make the development of alternative propulsion systems a top priority in automotive research. Hybrid hydraulic vehicles (HHVs) can contribute to improving the fuel efficiency of heavy vehicles such as garbage trucks and city buses. The combination of a conventional diesel engine with an additional hydraulic powertrain allows for regenerative braking. Further improvements with regard to fuel efficiency become possible through additional optimization of the energy management strategy, which decides when to apply which propulsion system. Rule-based strategies are the state of the art, but they cannot utilize the full potential because their performance is only superior on the cycles for which they have been developed. Approaches including numerical optimization are independent from the actual drive cycle and result in much higher savings. However, these techniques usually require a prediction of the driving profile. In this paper, a complete solution for predictive energy management in HHVs is presented. The fuel savings obtained through the developed algorithms used for prediction and optimization are determined in a simulation study, and the functionality of the concept is proven in a hybrid hydraulic testing vehicle.

Modeling and Control of Heave-Induced Pressure Fluctuations in Managed Pressure Drilling

Abstract: Automatic managed pressure drilling is an advanced pressure-control method which is intended to meet the increasingly high demands in drilling operations in the oil and gas industry. In this method, the circulating drilling fluid, which takes the cuttings out of the well, is released at the surface through a controlled choke. This choke is used for active control of the fluid pressure in the well. The corresponding automatic control system keeps the pressure at the bottom of the well at a specified setpoint despite various disturbances. One such disturbance, i.e., the vertical motion of the drill string, causes severe pressure fluctuations which need to be actively attenuated. In this paper, we present two different disturbance rejection strategies based on discretized partial differential equations for the well hydraulic system. The performance of the controllers is shown through simulations both under idealized conditions and on a high-fidelity drilling simulator.

Energy harvesting from hydraulic pressure fluctuations

Abstract: State-of-the-art hydraulic hose and piping systems employ integral sensor nodes for structural health monitoring to avoid catastrophic failures. Energy harvesting in hydraulic systems could enable self-powered wireless sensor nodes for applications such as energy-autonomous structural health monitoring and prognosis. Hydraulic systems inherently have a high energy intensity associated with the mean pressure and flow. Accompanying the mean pressure is the dynamic pressure ripple, which is caused by the action of pumps and actuators. Pressure ripple is a deterministic source with a periodic time-domain behavior conducive to energy harvesting. An energy harvester prototype was designed for generating low-power electricity from pressure ripples. The prototype employed an axially-poled off-the-shelf piezoelectric stack. A housing isolated the stack from the hydraulic fluid while maintaining a mechanical coupling allowing for dynamic-pressure-induced deflection of the stack. The prototype exhibited an off-resonance energy harvesting problem since the fundamental resonance of the piezoelectric stack was much higher than the frequency content of the pressure ripple. The prototype was designed to provide a suitable power output for powering sensors with a maximum output of 1.2 mW. This work also presents electromechanical model simulations and experimental characterization of the piezoelectric power output from the pressure ripple in terms of the force transmitted into the harvester. (Some figures may appear in colour only in the online journal)

A textbook of fluid mechanics and hydraulic machines : in SI units

Abstract: A helpful text for University students exploring the properties of fluid mechanics, fluid dynamics, flow over notches, and pipe turbulent flow with centrifugal and reciprocating pumps.

Integrated electronic hydraulic brake system

Abstract: An integrated electronic hydraulic brake system provided with an actuator including a master cylinder and a pedal simulator, an electronic stability control (ESC) and a hydraulic power unit (HPU) in a single unit.

Nonlinear hydro turbine model having a surge tank

Abstract: This article models a hydro turbine based on the dynamic description of the hydraulic system having a surge tank and elastic water hammer. The dynamic of the hydraulic system is transformed from transfer function form into the differential equation model in relative value. This model is then combined with the motion equation of the main servomotor to form the nonlinear model of the hydro turbine, in which the power of the hydro turbine is calculated using algebraic equation. A new control model is thus proposed in which the dynamic of the surge tank is taken as an additional input of control items. As such, the complex hydraulic system is decomposed into a classical one penstock and one machine model with an additional input control. Therefore, the order of the system is descended. As a result, the feasibility of the system is largely improved. The simulated results show that the additional input of the surge tank is effective and the proposed method is realizable.

Design of a Hydraulic Motor System Driven by Compressed Air

Abstract: This paper presents the design of a highly efficient pneumatic motor system. The air engine is currently the most generally used device to convert potential energy of compressed air into mechanical energy. However, the efficiency of the air engines is too low to provide sufficient operating range for the vehicle. In this study, the energy contained in compressed air/pressurized hydraulic oil is transformed by a hydraulic motor to mechanical energy to enhance the efficiency of using air power. To evaluate the theoretical efficiency, the principle of balance of energy is applied. The theoretical efficiency of converting air into hydraulic energy is found to be a function of pressure; thus, the maximum converting efficiency can be determined. To confirm the theoretical evaluation, a prototype of the pneumatic hydraulic system is built. The experiment verifies that the theoretical evaluation of the system efficiency is reasonable, and that the layout of the system is determined by the results of theoretical evaluation.

Reliability-based maintenance scheduling of hydraulic system of rotary drilling machines

Abstract: Hydraulic system has a critical and important role in drilling machines. Any failure in this system leads to problems in power system and machine operation. Since the failure cannot be prevented entirely, it is important to minimize its probability. Reliability is one of the most efficient and important method to study safe operation probability of hydraulic systems. In this research, the reliability of hydraulic system of four rotary drilling machines in Sarcheshmeh Copper Mine in Iran has been analyzed. The data analysis shows that the time between failures (TBF) of Machines A and C obey the Weibull (2P) and Weibull (3P) distribution, respectively. Also, the TBF of Machines B and D obey the lognormal distribution. With regard to reliability plots of hydraulic systems, preventive reliability-based maintenance time intervals for 80% reliability levels for machines in this system are 10 h.

Active FTC for hydraulic pitch system for an off-shore wind turbine

Abstract: This paper describes the development and testing of the implementation of a linear parameter varying (LPV) fault tolerant control (FTC) approach to hydraulic pitch actuation for an off-shore wind turbine (OWT) system with independent pitch actuators. The study involves two separate actuator fault scenarios. In the first scenario the pitch actuator position sensor signal is considered to be stuck at a fixed value. In this case, a fault hiding approach is used to compensate for this fault in the control system, as a form of sensor FTC scheme with fault estimation. The second fault scenario is caused either by a drop in pressure in the hydraulic supply system or the high air content in the oil. In this case, the fault-free pitch actuator systems are both utilized to synchronize all three pitch systems in order to prevent further damage caused by unbalanced structural loads.

Universal oil composition for environment-friendly energy-saving engineering machinery

Abstract: The invention discloses a universal oil composition for environment-friendly energy-saving engineering machinery. The universal oil composition comprises the following components according to mass percent: 85%-90% of composite base oil and 15%-10% of other additives. The universal oil composition for the environment-friendly energy-saving engineering machinery adopts a poly-alpha-olefin (PAO) and dioctyl sebacate composition as the base oil, is good in comprehensive performance, can replace diesel engine oil, hydraulic oil, gear oil, hydraulic transmission fluid and other various unit oil used in the engineering machinery, achieves multiple purposes, increases the power of a diesel engine, improves the reliability, the fuel economy and the low-temperature start performance of the diesel engine and the working efficiency and the precision of a hydraulic system, and effectively prolongs the service life and the oil draining period of the hydraulic system, the diesel engine, a gear system, a hydraulic transmission system and other various units.

System to diagnose variable valve actuation malfunctions by monitoring fluid pressure in a hydraulic lash adjuster gallery

Abstract: A system for diagnosing malfunctions in a variable valve actuation device is disclosed. The system has a rocker arm assembly that includes: a first arm, a second arm with the first and second arms attached at a first end, a hydraulically operated latch assembly that functions to secure the first arm to the second arm when latched. The rocker arm assembly pivots upon a hydraulic lash adjuster. It also includes a source of pressurized fluid connected to a hydraulic valve that provided fluid high or low pressure fluid to the hydraulically-operated latch. The latch may be operated by a remote device. A pressure transducer is positioned within the hydraulic lash adjuster (HLA) and is adapted to create a signal indicating the fluid pressure in the HLA. A control unit is coupled to the hydraulic valve and the pressure transducer, and is adapted to sense engine operation parameters, actuate the hydraulic valve, read the signal from the pressure transducer and identify malfunctions of the rocker arm assembly based upon the signal from the transducer.

STEAM: A Mobile Hydraulic System With Engine Integration

Abstract: 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.Copyright © 2013 by ASME

Analysis of Small-Scale Hydraulic Actuation Systems

Abstract: We investigated small-scale hydraulic power actuation systems using a system level analysis, where small-scale refers to systems generating 10 to 100 W output power, to determine whether the high power density advantage of hydraulics holds at small sizes. Hydraulic actuator system power density was analyzed with simple physics models and compared to an equivalent electromechanical system comprised of off-the-shelf components. Calculation results revealed that high operating pressures are needed for small-scale hydraulics to be lighter than the equivalent electromechanical system. The analysis was limited to the actuator and conduit as those are the components that must be located on the mechanism. A complete comparison should add the weight and efficiency of the power supply.

Hydraulic system and method of monitoring

Abstract: A technique involves monitoring a hydraulic system having a hydraulic pump coupled to a hydraulic motor which can be used to drive well related equipment. The system and methodology utilize sensors positioned to monitor parameters related to operation of the hydraulic pump and the hydraulic motor. A processor system is coupled to the sensors to obtain data output by the sensors. The processor system analyzes the sensor data for failure signatures that can be used to determine a failure or potential failure in the hydraulic system.

Hydraulic drive circuit

Abstract: [Problem] To provide a hydraulic drive circuit that, in a hydraulic drive system widely used in construction machines, industrial apparatuses such as presses, and the like, can achieve high responsiveness, high precision, and high efficiency at a low cost. [Solution] This hydraulic drive circuit (1), which drives a hydraulic actuator (2) by means of supplying hydraulic fluid discharged from a main hydraulic fluid pump (P), is provided with: a first valve (4) that is disposed at a main tubing pathway (3) through which the hydraulic fluid discharged from the main hydraulic pump (P) flows to the hydraulic actuator (2); a second valve (5) for causing hydraulic fluid to flow into one fluid chamber of the hydraulic actuator (2) and for returning to a tank (T) the hydraulic fluid discharged from another fluid chamber; and a sub-hydraulic pump (7) that increases/amplifies the hydraulic fluid of the main tubing pathway (3) by a predetermined amount using the hydraulic fluid flowing to a branched tubing pathway (6) that branches from the main tubing pathway (3) between the main hydraulic fluid pump (P) and the drive switching valve (4).

Observer-Based Robust Control for Hydraulic Velocity Control System

Abstract: This paper investigates the problems of robust stabilization and robust control for the secondary component speed control system with parameters uncertainty and load disturbance. The aim is to enhance the control performance of hydraulic system based on Common Pressure Rail (CPR). Firstly, a mathematical model is presented to describe the hydraulic control system. Then a novel observer is proposed, and an observed-based control strategy is designed such that the closed-loop system is asymptotically stable and satisfies the disturbance attenuation level. The condition for the existence of the developed controller can by efficiently solved by using the MATLAB software. Finally, simulation results are provided to demonstrate the effectiveness of the proposed method.

Independent load sensing for a vehicle hydraulic system

Abstract: A hydraulic system for a vehicle includes a first hydraulic circuit, a second hydraulic circuit, and a main actuator. The first hydraulic circuit includes a first pump having a flow outlet; a first pressure line having a pump end coupled to the flow outlet of the first pump; and a first load sensing line having a pump end coupled to the first pump and a pressure end coupled to the first pressure line. The second hydraulic circuit includes a second pump having a flow outlet; a second pressure line having a pump end coupled to the flow outlet of the second pump; and a second load sensing line having a pump end coupled to the second pump and a pressure end coupled to the second pressure line. The main actuator is coupled to the first pressure line and the second pressure line and is configured to oppose a load force. The first load sensing line is separate from the second load sensing line such that the first pump and the second pump respond independently to the load force.

Active control of pressure pulsation in a switched inertance hydraulic system

Abstract: The nature of digital hydraulic systems may cause severe pressure pulsation problems. For example, switched inertance hydraulic systems can be used to adjust or control flow and pressure by a means that does not rely on dissipation of power, but they have noise problems because of the pulsed nature of the flow. An effective method to reduce the noise is needed that does not impair the system performance and efficiency. This article reports on an initial investigation of an active attenuator for pressure pulsation cancellation in a switched inertance hydraulic system. Using the designed noise attenuator, the pressure pulsation can be decreased effectively by superimposing an anti-phase control signal. A high-performance piezoelectric valve was selected and used as the secondary path actuator in terms of its fast response and wide bandwidth. Adaptive notch filters with the filtered-X least mean square algorithm were applied for pressure pulsation attenuation, while a frequency-domain least mean square filte...

Online monitoring and fault diagnosis system of large wind turbine units

Abstract: The invention discloses an online monitoring and fault diagnosis system of large wind turbine units. A sensor and data collection equipment are installed on a wind turbine unit to be detected, so as to collect equipment operation state characteristic signals, such as video signals, noise signals, flame signals, electric signals, vibration signals and pressure signals, of the wind turbine unit, and transmits the state characteristic signals to a central control room of a wind power plant through a network in real time; and operation and maintenance personnel can know the operation state of the wind turbine unit at any time in the central control room of the wind power plant, and can directly analyze signal data of the abnormally operated wind turbine unit, so that operation conditions of gear boxes, main shafts, generators, bearings, hydraulic systems, yaw systems, bearing lubricating systems, brake systems, blades and towers of all units in the wind power plant are monitored in real time and failure warning information is output. Data can also be transmitted to a remote fault diagnosis center through a network, a project team performs professional analysis to faults and issues a diagnosis report, and a field maintenance team performs corresponding repair/maintenance operation.

Design of full electric power steering with enhanced performance over that of hydraulic power-assisted steering

Abstract: This paper presents a method of designing a full electrical power steering system to replace a hydraulic power-assisted steering system with improved performance and benefits including energy savin...