Motor-pump Unit Research Articles

A Study on the Electro-Hydraulic Coupling Characteristics of an Electro-Hydraulic Servo Pump Control System

Electro-hydraulic servo pump control belongs to an electro-hydraulic coupling motion control system, which involves the mutual penetration and integration of mechanical, hydraulic, electrical, control, and other disciplines, as well as the time-varying, uncertain, multisource, and multifield problems of the internal and external excitation of the system, which makes the electro-hydraulic servo pump control system have the characteristics of a complex model, strong coupling, nonlinearity, and time-variation, resulting in the low accuracy and poor dynamic characteristics of the system. This paper takes a servo motor quantitative pump hydraulic cylinder load as the main dynamic line; divides the electro-hydraulic servo pump control system into a motor pump unit, a hydraulic transmission unit and a power output unit; analyzes its electromechanical coupling characteristics, pressure flow coupling characteristics, and mechanical–hydraulic coupling characteristics, respectively; studies the multiparameter characteristics of the system under the electromechanical–hydraulic coupling conditions; and summarizes the influence laws between the parameters. Finally, through a MATLAB/Simulink simulation, it provides a theoretical basis and guidance for high-performance control of the system.

Online Flow Estimation for Condition Monitoring of Pumps in Aircraft Hydraulics

Hydraulic systems in conventional civil aviation are currently monitored in a very rudimentary way. Normally, measured values are compared with a fixed threshold. If these measured values are outside the predefined limits, the entire hydraulic system is usually shut down. To overcome this deficit, a study regarding a novel prognostic health management method for aircraft hydraulic pumps, which allows a statement about the pump condition, is presented in this paper. The method is based on measuring differential pressure and temperature at a suitable resistance. In the first part of the study, the overall concept for monitoring the motor pump unit is analyzed. This is followed by a discussion of possible measurement methods and suitable resistors to determine the condition of the pump. In the second part of the study, the implementation for online monitoring of the pump is discussed. After a suitable approximation is found, the quality of the proposed method is evaluated with real hydraulic power generation and consumers.

Experimental Investigation of a Double-Acting Vane Pump with Integrated Electric Drive

The article presents an innovative design solution of a balanced vane pump integrated with an electric motor that has been developed by the authors. The designed and constructed bench, which enables testing of the system: power supply, converter, ntegrated motor—pump assembly and hydraulic load at different motor speeds and different pressures in the hydraulic system, is described. The electromagnetic and hydraulic processes in the motor-pump unit are investigated, and new, previously unpublished, results of experimental studies at steady and dynamic states are presented. The results of the study showed good dynamics of the integrated motor-pump assembly and proved its suitability to control the pump flow rate, and thus, the speed of the hydraulic cylinder or the speed of the hydraulic motor.

Analysis of vane loads and motion in a hydraulic double vane pump with integrated electrical drive

In this paper, the results of the analysis of the forces acting on vanes in a double-acting vane pump with an integrated electric drive have been presented. In the new motor pump unit, the pump is assembled inside the rotor of the electric motor. A dynamic model representing the vane movement has been developed considering the impact of pressure load distribution, vane support forces and friction forces. The loss of contact between the vane head and the cam ring lead to the noise and reduction of the volumetric pump efficiency. The dynamic model which describes the vane motion and contact between the vane tip and cam ring has been solved using MATLAB software. The influence of load distribution, pump design and operational parameters on the vane dynamics has been analysed.

Intelligent optimization of a hybrid renewable energy system-powered water desalination unit

The use of renewable energies for pumping and desalination of seawater and/or brackish water can be a viable solution to reach a more sustainable freshwater production and reduce environmental impacts. In this way, a new approach based on the design of experiment method for optimal sizing a stand-alone solar–wind-reverse osmosis desalination system is investigated. For this, system modelling is presented with the development of a single sizing parameter between desalination motor pump and reverse osmosis unit and a dynamic simulator of the proposed energy–water system with its energy management loop is developed using climatology year data of southern Tunisia. In optimization loop, the methodology with one-year dynamic simulation necessarily leads to very long convergence times of several days. To try to reduce this time, a track has been proposed which consists in using meta-models instead of dynamic simulators. In order to apply this track, a meta-model (hybrid spline) that represents the system constraints and objectives is investigated based on design of experiments tool and a bi-objective genetic algorithm is applied in the optimization process via the developed meta-model. Two objective functions are used: loss of power supply probability (reliability indicator) which is used to present the dissatisfaction of the water production and embodied energy (environmental indicator) which is used to compute energetic cost (MJ) and to evaluate the environmental impacts potential (across the whole life cycle). Optimal sizing of the system via meta-models instead of dynamic simulator led to encouraging results with significantly reduced CPU times (from several days to 13 min).

Experimental study of the characteristic curves of 0.5 HP radial pump with constant speed

Radial (centrifugal) pumps are commonly used in industry and represent 22% of total consumption of the energy worldwide. The understanding of their operating conditions is important for a proper selection and use, specifically at the Best Efficient Point (BEP). This study analyzed the variation of the operating conditions of a common, small pump when the flow is regulated with a control valve at the pump discharge, keeping the rotational speed constant. The system consists in a closed loop using a turbine meter programmed in Arduino for flowrate measurement. The electric power and energy consumption were provided by an electronic Wattmeter, and the pressure at the suction/discharge of the pump was taken from Bourdon gauges. The minimum submergence of the pump intake was calculated with the Standard ANSI-HI-9.8 and the Bourdon gauges selection followed the recommendations of the Standard ASME B40.100-1998. All the measurements are part of the Energy equation for the pump-motor system (monoblock unit), whose H-Q curve is compared to manufacturer’s curve with reasonable agreement that served as validation. The electric power curve is the evidence that the flow regulation method is unappropriated because the power consumption increases as the flow is regulated. At the end, the efficiency curve of the motor-pump unit was presented, with a maximum value of 12%. The shock and recirculation losses are present, but the electrical losses are evidenced through excessive heating. The test bench will have a better pump and a variable frequency drive for further studies.

The Design, Control, and Testing of an Integrated Electrohydrostatic Powered Ankle Prosthesis

This paper presents a prototype powered ankle prosthesis that can operate passively in most of the gait cycle and provide powered assistance for toe push-off and subsequent foot dorsiflexion. The use of an electrohydrostatic actuator (EHA) gives the ability to switch quickly and smoothly between passive and active modes. In this new powered ankle prosthesis, the motor-pump unit is integrated with the ankle joint and the battery and controller are held in a backpack. A 100 W brushless dc motor is used to drive a 0.45 cc/rev gear pump, controlling flow to an ankle cylinder through a bespoke manifold. The motor runs wet, pressurized to 6 MPa, avoiding the need for a pump shaft seal and a refeeding circuit for external leakage. A dynamic system model has been develop to help analyze the EHA performance. A motor control method is proposed based on heel strike recognition and a middle stance time delay. The prosthesis has been tested with a 70 kg transtibial amputee, and results are presented for walking on a treadmill at three different speeds (2.8, 3.8, and 4.8 km/h). The amputee has provided positive subjective feedback. We conclude that the hybrid passive-active approach has significant advantages for prosthesis design, and we outline future testing and development requirements.

Intelligent SUV Chassis

RAPA has developed a unique motor pump unit for the E-Active Body Control chassis, as fitted to the trend-setting Mercedes-Benz GLE

Optimized design and characterization of motor-pump unit for energy-regenerative shock absorbers

The constant need to reduce emissions in the automotive sector has driven the electrification of powertrain and chassis. To comply with this trend and decrease the bound even further, the present paper proposes the use of hydraulic regenerative shock absorbers for automotive suspension systems. The conversion of linear into angular motion and the suitable control of an integrated electric machine allow to transform part of the vibrational energy into electricity. In these damping devices, the key element is the motor-pump unit that is interfaced onto a conventional hydraulic cylinder architecture. Hence, the proposed research focuses on this component by investigating different design aspects in all the domains of interest. The objective is to optimize the energy conversion efficiency of the unit without affecting its damping control property. To give means of validation, a motor-pump prototype is built and experimentally characterized through a dedicated test rig.

Consideration of the resonance effects in the fatigue analysis of the body in white

In the development of the body in white (BIW) the fatigue evaluation is an important building block in ensuring the functional characteristics. Due to the continuously increasing time and cost pressure in vehicle development, a reliable fatigue evaluation based on digital methods is absolutely essential. Yet the current methods cannot sufficiently consider the dynamic effects which are induced by the natural vibrations. Components with concentrated masses are mostly affected by this shortcoming. Hence, proper dimensioning of the connections of these com ponents based on digital methods involves considerable risks at present. In order to fill this gap, a calculation method has been developed by Mercedes-Benz and the Fraunhofer Institute LBF, which takes the dynamic effects into account via superposition of the modal stresses. The procedure will be presented in this article using the example of a motor pump unit.

Verificação das relações de Rateaux pelo emprego de um inversor de freqüência

Este trabalho teve como objetivo verificar a veracidade das relações de Rateaux e a redução no consumo da potência consumida no bombeamento, quando se emprega o inversor de freqüência, o qual permite a variação de rotação do conjunto motobomba. Empregando-se o inversor de freqüência, a redução média da potência consumida foi de 40,7 e 75,0% com a adoção da redução da rotação de 1800 para 1500 rotações min-1 e de 1800 para 1100 rotações min-1, respectivamente. Quando se avaliou a potência consumida usando-se essas mesmas relações, o erro médio na redução de potência foi de 1,33 e 2,00% para as rotações min-1 de 1500 e 1100, respectivamente, o que permite o emprego das relações para se estimar as grandezas altura manométrica, vazão e potência, a partir da curva característica obtida experimentalmente.

Cora valveless pulsatile rotary pump: New design and control

For decades, research for developing a totally implantable artificial ventricle has been carried on. For 4 to 5 years, two devices have been investigated clinically. For many years, we have studied a rotary (but not centrifugal) pump that furnishes pulsatile flow without a valve and does not need external venting or a compliance chamber. It is a hypocycloidal pump based on the principle of the Maillard-Wankel rotary compressor. Currently made of titanium, it is activated by an electrical brushless direct-current motor. The motor-pump unit is totally sealed and implantable, without noise or vibration. This pump was implanted as a left ventricular assist device in calves. The midterm experiments showed good hemodynamic function. The hemolysis was low, but serious problems were encountered: blood components collecting on the gear mechanism inside the rotor jammed the pump. We therefore redesigned the pump to seal the gear mechanism. We used a double system to seal the open end of the rotor cavity with components polished to superfine optical quality. In addition, we developed a control system based on the study of the predicted shape of the motor current. The new design is now underway. We hope to start chronic experiments again in a few months. If the problem of sealing the bearing could be solved, the Cora ventricle could be used as permanent totally implantable left ventricular assist device.

Energy flow, energy losses and efficiency of the hydraulic press system

For a 1000 kN gap-frame hydraulic press and a 5000 kN straight-side press the values of the overall efficiency were experimentally determined by three different forming processes. The energy losses of the drive system (drive efficiency of motor-pump unit) and of the hydraulic system (pipes, valves and main cylinder) constitute the main influence on the overall efficiency of the press. The energy losses depend on the forming process (e.g. deep drawing, upsetting, blanking), on the load ratio of the press in regard to deformation work and forming force, and on the velocity of the slide. A comparison of the overall efficiency of hydraulic presses with the values of eccentric presses with similar characteristics was carried out.

A forced circulation system for solar water heating

The work reported here gives the results of a project carried out to examine the possibility of using a forced circulation system operated by solar energy via solar (photovoltaic) cells. The cost of such a device could be offset by savings in using the existing ground level storage tank and savings in the size of the interconnecting pipework required. Such a system would also be to some extent self-controlling in that pumping would only occur at the times when the absorbers were also receiving solar radiation. The study first examined the characteristics of solar cells, then an estimate of the power requirement for a typical installation was made. A motor-pump unit was developed which met some of the requirements and finally the unit was tested in a simple solar water heating circuit. (WDM)