Radial Piston Pump Research Articles

Study on Film Characteristics of Piston-Cylinder Interface of High-Pressure Common Rail Radial Piston Pump with Micro Motion

When the high-pressure common rail radial piston pump works, the piston is subjected to film pressure and cam driving force, resulting in some micro-motion such as offset and inclination. A large number of theoretical studies have shown that the micro-motion of piston has an important effect on the film characteristics of piston-cylinder interface. In this paper, according to the theory of hydrodynamic lubrication, Reynolds equation and film thickness equation of piston micro-motion are established, and solve the problem of the lubricant film of the piston-cylinder interface under different working conditions. The results show that the working pressure and cam speed have great influence on the film characteristics of piston-cylinder interface with micro-motion. The research results provide theoretical support for the optimization of the film parameters of the piston-cylinder interface.

Mechanical design and numerical simulation of digital-displacement radial piston pump for multi-megawatt wind turbine drivetrain

Digital displacement radial piston pump offers an alternative to existing drivetrain concepts of wind turbines. However, today's hydraulic components have not been scaled up to handle the loads of multi-megawatt turbines. This study aimed to exploit the mechanical design of digital-displacement radial piston pump for large-scale wind turbine drivetrain with the combination of parametric modeling, algorithm-based generative design and simulation-based evaluation methods. It first presents the analysis of working principles, parametrical modeling of major components and mathematical modeling of design constraints of the pump. Then, an exhaustive method–based generative approach is proposed for more innovative and effective pump design and the mechanical-hydraulic coupling model is developed for dynamic characteristic analysis and design evaluation. The proposed models and approaches are then applied to the design of a 5 MW radial piston digital-displacement pump for demonstration and validation. The comparison between the proposed optimal pump design scheme and an existing conceptual pump shows similar efficiency, but much more compact structure, higher power density and potentially better controllability and reliability which are likely preferred for wind turbine application.

Study on Film Characteristics of Piston-Cylinder Interface of High Pressure Common Rail Radial Piston Pump with Viscosity-Temperature-Pressure Effect

Aiming at the inaccuracy of equivalent viscosity method in solving the film characteristics of piston-cylinder interface of high-pressure common rail radial piston pump, the film characteristics equation of piston-cylinder interface was established based on the theory of thermo-hydrodynamic lubrication. Through the solution, the thermal properties of the piston-cylinder interface film, which accounted for viscosity-temperature-pressure effect, were studied. The effects of cam speed and film inlet pressure on the characteristics of the piston-cylinder interface film were discussed. The conclusion has certain theoretical and engineering application value for the design and basic research of piston-cylinder interface.

Modeling of radial piston machines considering elastohydrodynamic effects in both cam–piston and piston–cylinder lubricating interfaces

This study illustrates a novel numerical approach for investigating the complex physics involved in radial piston pump (rotating cam type) operation. This approach is based on a fully-coupled model that combines the evaluation of the main flow through the unit, realized by the pistons’ displacement, with the simulation of the internal lubricating interfaces, given by the piston–cylinder interface and the cam–piston interface. These interfaces represent the main source of power dissipation due to leakages and shear. The comprehensive multi-domain simulation tool presented in this paper incorporates a robust fluid–structure interaction based numerical model for the piston–cylinder lubricating interface as well as a model for the lubricant flow in the cam–piston interface. Since the approach used for piston–cylinder interface was previously presented by the authors, in this work particular emphasis is given to the description of the elastohydrodynamic lubrication model for the cam–piston interface. The overall coupling between these models enables an accurate estimation of the piston micro-motion that is critical to analyzing fluid flow in the lubricating gaps during pump operation. Results are shown with reference to a pump with four pistons designed to reach pressures up to 2500 bar. For this unit, the outer race of the cam—which is in contact with multiple pistons during pump operation—is unconstrained in its rotation, and it undergoes a complex motion due to which experimental measurements of its angular velocity were performed. The results from the study confirm the utility of the numerical model as an effective tool for modeling radial piston machines.

Experimental Study on Variable Displacement Radial Piston Pump Performance: Injection Application in Round Pipe Cross-Flow

AbstractAn experimental study has been carried out on the injection of a single piston into a confined cross-flow of a round pipe. Five liters per minute have been used for the cross-flow with vari...

Radial-piston pump for drive of test machines

The article reviews the development of radial-piston pump with phase control and alternating-flow mode for seismic-testing platforms and other test machines. The prospects for use of the developed device are proved. It is noted that the method of frequency modulation with the detection of the natural frequencies is easily realized by using the radial-piston pump. The prospects of further research are given proof.

Numerical Analysis of the Water Film Characteristics in the Eccentric State of a Radial Piston Pump

This paper investigates the working efficiency and reliability of a piston pair of radial piston pumps by accurately calculating the shape and pressure distribution of the piston pair. First, a leakage model of the piston pair is established based on the equivalent liquid resistance and adaptive eccentricity. This model considers the piston micro-motion in the cylinder and the force balance. Then, the piston clearance shape and pressure distribution are numerically simulated using a genetic algorithm and the finite-volume method, and the clearance leakage flow is discussed. The example analysis demonstrates the accuracy of the model; the iterative algorithm has good numerical stability at the given precision and can rapidly converge to the global optimal solution of the model to obtain the real-time piston eccentricity state and pressure distribution with high accuracy. The results demonstrate that the model has high accuracy. Finally, the effects of various parameters such as the piston diameter, initial clearance of the piston pairs, and piston speed on the leakage rate are discussed. The conclusions of this paper provide guidance for the design of water piston pumps.

Experimental investigation of the effect of grooves cut over the piston surface on the volumetric efficiency of a radial hydraulic piston pump

AbstractA radial piston pump often used in high pressure applications. The geometry of the pistons used affects the mechanical and volumetric efficiency of the pump and its long term performance. In the present study, the effect of grooves cut on the piston surface, the number of the grooves and their location over the piston surface on the volumetric efficiency of the hydraulic radial piston pumps was investigated. In order to perform the research tests, the three-piston fixed displacement pump with seven configurations was firstly designed and fabricated. The output flow rate of the pump was determined at pressure outlets of 350 and 500 bar and then the volumetric efficiency was calculated as the mean values of measured data. The results showed that the grooves cut on the piston surface produces a higher piston–cylinder overall leakage and then tend to reduce the volumetric efficiency. Also as the number of grooves being cut on piston surface increases, an increase in leakage will happen. In addition, b...

Study on flow characteristics and flow ripple reduction schemes of spool valves distributed radial piston pump

This paper studies the flow characteristics and flow ripple reduction techniques of a spool valves distributed radial piston pump. The mathematical models of the pump are established, and simulations based on the mathematics are performed in AMESim environment. The results indicate that the spool valves distributed radial piston pump has fewer flow fluctuations than the pump distributed by check valves, due to the rigid motion of its distribution component—the spool valves. Then, in order to reduce the flow ripple of the spool valves distributed radial piston pump, three techniques, namely, time delay, relief chamfer and transition compression filter volume, are proposed and their working principles are illustrated. Particularly, the design method of time delay is elaborated and its effectiveness is evaluated. The simulation results suggest that with the usage of the time delay method, the fluctuation range of the spool valves distributed radial piston pump is expected to be reduced by 21.7%.

Design and theoretical analysis of a sliding valve distribution radial piston pump

A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced.

Design and experimental studies of a novel double-row radial piston pump

This paper proposed a novel double-row radial piston pump. In this pump, the transformation from the rotation of the shaft to the reciprocation of the piston is realized by a pentagon mechanism, and the oil is distributed by check valves, which are integrally designed on the pump body. Theoretical calculation demonstrated that this improved design can substantially reduce the force on the main shaft of pump. The formulas of instantaneous flow rate and fluctuation coefficient of the pump are deduced. For studying the working characteristics of the pump further, a prototype was manufactured and tested. Results show that when the rotation speed is over 125 r/min, the performances of pump prototype are qualified, the fluctuation rate is limited to 20% and the volumetric efficiency can reach 90%. Moreover, the pump was disassembled after 100 h of service and the wear condition was checked. Except for the pentagon which has indentation on the surface, the components of the pump are all kept intact.

Research on Velocity Vibration Characteristics of Stator of Radial Piston Pump in Time Domain

The working mode of constant-pressure radial piston pump includes the mode of constant flow and constant pressure. The dynamic model of stator vibration was established and the analysis was made on the stator vibrating velocity in time domain to the two modes. Measurement mechanism was designed to test the vibration of stator of JB32H-type radial piston pump. It is concluded from the analysis and test results that the velocity of stator vibrates periodically on the two modes. The maximum amplitude on the mode of constant pressure is smaller than the one on the mode of constant flow. The conclusions are helpful to the noise control of piston pump.

Design of a Shaft Assignment Radial Piston Pump

This paper introduces a kind of shaft structure improvement after assignment radial piston pump, its structure and working principle to improve the axial flow past with radial piston pump shaft with flow the stress of the situation, and improve the hydraulic pump pressure of work and service life.

Design of the Several Pneumatic Tendon Piston

With the rapid development of hydraulic technology, pressure-driven piston pump, the output pressure, simple structure, in the field of mechanical engineering and field engineering work has been widely used. For existing pneumatic piston existence of a functional insufficiency, poor technical performance, the irrational structure, and high-pressure areas, especially in high pressure areas occupy an irreplaceable position in the axial and radial piston pumps, there are also complex, expensive, traffic pulse rate not ideal and other indicators of disadvantage. In this paper, the normal replacement method for flexible-rigid pneumatic cylinder replacement tendons, structural design, light weight, is able to adapt to harsh environments tendon type pneumatic piston. Practical results shows that the design of the pneumatic piston in the wild-type tendon in applied engineering work obtains good results.

Experimental Analysis, Modeling, and Control of Volumetric Radial-Piston Pumps

An experimental-theoretical study has been carried out on high-pressure volumetric radial-piston pumps for diesel fuel injection systems. The dependence of the pump inducted flow rate on speed and load was investigated and the characteristic curve of the pump cooling-lubrication circuit was derived. The head-capacity curves were determined for different types of pumps at different revolution speeds and compared with the injector flow requirements in order to evaluate the pressure-control strategy efficiency. An insight into the ageing effects on the pump performance was also provided. Furthermore, the dynamic pump behavior was investigated, with specific reference to the flow-rate ripple at the delivery port. A general analytical expression has been derived for the volumetric efficiency. Furthermore, a specific procedure has been developed and applied to the experimental evaluation of the fuel leakages in pressure control valve (PCV) integrated pumps. Finally, the mechanical-hydraulic efficiency of the pump has experimentally been assessed as a function of head and speed in order to obtain a reliable evaluation of the pump shaft power and torque at different working conditions.

Analysis on Velocity Vibration Characteristics of Stator of Radial Piston Pump

The working mode of constant-pressure radial piston pump includes the mode of constant flow and constant pressure. The dynamic model of stator vibration was established and the analysis was made on the stator vibrating velocity in frequency domain to the two modes. Measurement mechanism was designed to test the vibration of stator of JB32H-type radial piston pump. It is concluded from the analysis and test results that the velocity of stator vibrates periodically on the two modes. Stator velocity vibrates in the range of higher frequency on the mode of constant flow than on the mode of constant pressure. The conclusions are helpful to the noise control of piston pump.

The Electro-Hydraulic Proportional Control and Simulation of the Radial Piston Pump Based on Proportional-Integral-Derivative Neural Network

In this paper a new control method has been studied in which PID control system was integrated into the neural network. It could overcome some disadvantages such as neural network’s slow rate of convergence and PID’s difficulty in application of multivariate nonlinear systems. A controller of the Electro-hydraulic proportional control stroking mechanism for radial piston pump was designed based on the PID neural network control algorithm. The system responses of system variable control signal of system track were achieved by computer simulation. It was found by PIDNN that the control system could reach steady state in a shorter time, compared with PID control system response time by 65% to 80%. The simulation results showed that the controller for the Electro-hydraulic proportional Radial Piston Pump based PID neural network control algorithm would have a good controlling performance.

Research of Hydrotronic Variable-Displacement Radial Piston Pump with Electro-Pneumatic Control

The paper presents the developed new electro-pneumatic control (pneumotronic) system for hydraulic fixed-displacement radial piston pump. Hydraulic fixed-displacement radial piston pump equipped with the proposed control system changes into hydrotronic variable-displacement radial piston pump. Pump flow rate control is realized by means of programmable logic controller, electro-pneumatic valves, pneumatic cylinders and a sensor.

Research of the Pressure Pulsation within Piston Chamber in Radial Piston Pump

Noise reduction in piston pumps has been being the focus research. Many methods have been designed to smooth it. Research shows that noise takes place at the time when pistons enter the discharge port or enter the suction port. In fact, noise is induced by imbalance pressure in piston chamber. In this paper, piston initial volume and instantaneous controlled volume are deduced. Equations describing pressure angle-rate-of-change are also deduced. Keep the pressure increment equal when the pump eccentric distance is maximum and minimum, and then find out the optimal structure parameters. The parameters makes the pressure ripple minimize and makes the lowest noise.

Study of the delivery behaviour of a pump for common rail fuel injection equipment

This work deals with the delivery flowrate of a radial piston pump for common rail fuel injection equipment. At first, attention is paid to the volumetric efficiency of the pump, presenting basic formulas and reviewing common theory. A new efficiency model is proposed and considerations regarding the pump running under large pressure differences between suction and delivery and variable driving speeds are formulated in order to realize difficulties in pump filling. Later, a numerical model simulating the working behaviour of the pump is used to investigate the effects of variable inlet pressures under high delivery pressure and different driving speeds. Comparisons between numerical results and experimental data referring to the delivery behaviour of the pump are reported, as well as in-cylinder pressure diagrams, necessary to realize filling deficiencies quickly. The flowrate delivered by the investigated pump depends on both the inlet and outlet pressures. Increasing the driving speed beyond certain values does not result in proportional flowrate at pump delivery.