Variable Displacement Vane Pump Research Articles

3D CFD numerical analysis of vane dynamic effects on the pressure ripple in a variable displacement vane pump

A numerical three-dimensional CFD analysis of a variable displacement vane pump has been conducted, investigating the effects on the pressure ripple caused by the vane detaching from the pressure ring. The volume of the fluid over the vane tip has been re-meshed at every time step as a function of the forces acting on the bottom and the top of each vane. The numerical model has been developed using the commercial tool, Simerics MP+, including turbulence and cavitation models. The validation of the model has been done comparing numerical and experimental data. It has been observed that the detachment of the vane occurs during the transition zones when unwanted pressure spikes are generated by a nonoptimized valve plate design. The prediction of vane detachment is crucial for designing a quieter and more durable pump. Vane collision on the stator ring can be a source of noise producing premature wear of both components. Vane detachment from the stator ring has a large effect on pressure ripple even if the volumetric efficiency is only slightly influenced.

Lumped Parameter and Three-Dimensional Computational Fluid Dynamics Simulation of a Variable Displacement Vane Pump for Engine Lubrication

The paper describes the modeling and the experimental tests of a variable displacement vane pump for engine lubrication. The approach used for the simulation has involved three-dimensional (3D) commercial tools for tuning a zero-dimensional (0D) customized model implemented in the LMS Amesim® environment. Different leakage paths are considered and the axial clearances are variable to take into account the deformation of the pump cover, calculated through a finite element analysis with ANSYS. The vane tip clearances are calculated as function of the dynamic equilibrium equation of the vanes. The displacement control takes into account the internal forces on the stator due to the pressure in all variable chambers and to the contact force exerted by the vanes. The discharge coefficients in the resistive components have been tuned by means of a complete 3D transient model of the pump built with PumpLinx®. The tuned 0D model has been proved to be reliable for the determination of the steady-state flow-speed and flow-pressure curves, with a correct estimation of the internal leakages and of the pressure imposed by the displacement control. The pump has been also tested using a simplified circuit, and a fair agreement has been found in the evaluation of the delivery pressure ripple.

Variable displacement vane pump, part II: nonlinear volume flow control

Variable displacement vane pumps are one means to provide automotive transmissions with fluid energy. With their ability to adapt volume flow, they have the potential to adjust volume flow according to the specification at hand and thereby to increase energy efficiency. In this paper, a nonlinear volume flow approach for a variable displacement vane pump is suggested based on input–output linearization. A nonlinear observer concept based on high gain state estimation is presented, too. Ultimately, a feedforward linearizing control concept with PI output feedback is discussed as an alternative to the full state feedback input–output linearization approach.

Variable displacement vane pump, part I: a minimal nonlinear model

Variable displacement vane pumps are used in a variety of applications, most prominently in the context of modern automotive vehicles. They provide a means to react to changing consumer needs for oil flow and thereby to save energy. Despite their great practical relevance, minimal models capturing the main dynamic effects of such pumps have remained scarce. In this paper, a contribution is made in the form of a minimal model taking into account the force effects from line pressure exposure and dead volume compression and expansion. The thus-obtained pump model is autonomous and allows for a simple integration in simulation models. For a classic circuit with pressure regulation, a circuit model featuring the variable displacement vane pump model is developed for which simulation results are presented.

The effect of soot and diesel contamination on wear and friction of engine oil pump

The effect of oil contamination and oil degradation on friction and wear of engine oil pump are addressed in this paper. It provides a summary of an experimental study on the effects of oil contamination and oil degradation on tribological performance of a Variable Displacement Vane Pump (VDVP); a particular focus is on the vane-rotor contact. Firstly, a lab-based artificial ageing of fully-formulated engine oil (FFO) with the addition of contaminants such as carbon black (CB) and diesel is conducted. Secondly, the impact of these contaminants on the bulk property of the oil during the ageing process is investigated, using rheometry and Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR/FTIR). Thirdly, the performance of these oils on friction and wear of the vane-rotor contact under boundary lubrication regime is evaluated. The wear mechanism and chemical nature of tribofilms formed in tribological tests are addressed using Scanning Electron Microscopy/Energy Dispersive X-ray analysis (SEM/EDX) and Raman spectroscopy. It is found that the consumption of the additives by soot (additive adsorption) in the engine oil during the ageing process has a significant effect on wear of the components. This mechanism has a higher impact on producing high wear than abrasion by soot particles.

Theoretical study on performance characteristics of a variable displacement vane pump according to a variable amount occurrence

Theoretical studies were performed to understand the variation of performance of a variable displacement vane pump with automatic transmission according to the operating conditions and variable parameters. Chamber volume, discharge flow, pressure ripples, and cavitation occurrence were analyzed with variable amounts. The analysis result indicated that the discharge flow rate and pressure ripples increased with a rise of rotational speed, but decreased with variable amount increases. Increase of the oil temperature caused a slight decrease of the discharge flow and the driving torque. Cavitation definitely appeared at low temperatures and high rotational speeds, but it dramatically decreased with variable amount increases. The driving torque increased proportionally with the rotational speed and decreased with oil temperature. The maximum total efficiency was 73.8% at an oil temperature of 80°C but it decreased by 3.5% at 120°C.

Development of an electronically controlled variable displacement vane pump for engine lubrication

Lubrication is one of the most important factors in developing internal combustion engines. And vane pumps are known as potential choices for conducting the engine lubrication systems. To better optimize the lubrication performance, an electronically controlled variable displacement vane pump developed from a typical vane pump is newly introduced in this paper. Firstly, the concept and methodology to design properly an electric actuator to provide an additionally degree of pump control by regulating the pump displacement is carefully considered. Secondly, a control logic is developed to manage the operation of the actuator and subsequently, smoothly varying the pump output in order to satisfy any given lubrication profile. Finally, test rigs are setup to investigate the performances of the fabricated actuator and pump prototype. Practical tests are performed to evaluate the effectiveness of the newly pump design over the typical one.

Increasing the Lifetime of Variable Displacement Vane Pump with Aluminium Body

In this study, anodic oxidation method is applied to a flow-regulating valve and valve seat of the variable displacement vane pump with an aluminium body, which is used commonly in commercial vehicle steering systems. Then the lifetime of the pump is tested in a contaminated hydraulic fluid. After the lifetime tests, surfaces of the coatings are characterized with scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The thickness of the coating after the process is measured between 30 and 40 microns, and the hardness of the coating is between 360 and 440 Hv. This experiment proved that the resistance of the valve seat increased by between 30 and 40% after the coating process.

Increasing the Lifetime of Variable Displacement Vane Pump with Aluminium Body

In this study, anodic oxidation method is applied to a flow-regulating valve and valve seat of the variable displacement vane pump with an aluminium body, which is used commonly in commercial vehicle steering systems. Then the lifetime of the pump is tested in a contaminated hydraulic fluid. After the lifetime tests, surfaces of the coatings are characterized with scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The thickness of the coating after the process is measured between 30 and 40 microns, and the hardness of the coating is between 360 and 440 Hv. This experiment proved that the resistance of the valve seat increased by between 30 and 40% after the coating process.

자동변속기용 가변 용량 베인 펌프의 파워 절감 효과 평가에 대한 실험적 연구

Abstract : A variable displacement vane pump is possible to improve the fuel economy by varying the pump capacity with a vane mechanism according to the engine operating speed range and reducing its driving torque. In general the experimental evaluation of the vane pump for the transmission has been performed mainly not with the vehicle or dynamometer test rig but with component test rig due to the implementation and safety problems. In this paper, in order to evaluate the performance of the developed vane pump as well as the compatibility with other rotary and hydraulic components of the target transmission, the transmission dynamometer based test rig is implemented where the developed pump is built into it and then the variable pump capacity and effect of power reduction are investigated experimentally. Key words : Lubrication(윤활), Vane pump(베인 펌프), Variable displacement(가변용량), Automatic transmission(자동 변속기), Transmission dynamometer test( 변속기 다이나모미터 평가), Discharge flow rate control( 토출 유량 제어)

On the wear and lubrication regime in variable displacement vane pumps

This paper proposes an experimental methodology for the analysis of the lubrication regime and wear that occur between vanes and pressure ring in variable displacement vane pumps. The knowledge of the lubrication regime is essential for the improvement of the performance of high pressure vane pumps by reducing wear, increasing the volumetric efficiency and decreasing maintenance costs. Tests using pressure rings of different materials were carried out in order to identify the best material in terms of wear and friction. The proposed methodology is based on Archard's law and takes advantage of wear experimental measurements, an empirical model for the estimation of contact pressure forces and hardness standard tests. The results of the analysis state that low wear and reduced friction can be obtained if elasto-hydrodynamic lubrication between vanes and pressure ring is established. Results have been also verified by an analytical elasto-hydrodynamic model.

Modelling and simulation of a dual-clutch transmission vehicle to analyse the effect of pump selection on fuel economy

Positive displacement pumps are used in automotive transmissions to provide pressurised fluid to various hydraulic components in the transmission and also lubricate the mechanical components. The output flow of these pumps increases with pump/transmission speed, almost linearly, but the transmission flow requirements often saturate at higher speeds, resulting in excess flow capacity that must be wasted by allowing it to drain back to the sump. This represents a parasitic loss in the transmission leading to a loss in fuel economy. To overcome this issue, variable displacement pumps have been used in the transmission, where the output flow can be reduced by controlling the displacement of the pump. The use of these pumps in automatic transmissions has resulted in better fuel economy as compared with some types of fixed displacement pumps. However, the literature does not fully explore the benefits of variable displacement pumps to a specific type of transmission namely, dual-clutch transmission (DCT), which has different pressure and flow requirements from an epicyclic gear train. This paper presents an analysis of the effect of pump selection on fuel economy in a five-speed DCT of a commercial vehicle. Models of the engine, transmission, and vehicle are developed along with the models of two different types of pumps: a fixed displacement gerotor pump and a variable displacement vane pump. The models are then parameterised using experimental data, and the fuel economy of the vehicle is simulated on a standard driving cycle. The results suggest that the fuel economy benefit obtained by the use of the variable displacement pump in DCTs is comparable to the benefit previously shown for these pumps in automatic transmissions.

Piloted Displacement Controls for ICE Lubricating Vane Pumps

The paper brings to evidence critical issues in the design of variable displacement vane pump controls for ICE lubrication. Tight packaging, high rotational speed and variable pressure setting are key aspects influencing the selection of pump geometric parameters as well as its displacement controls. A specific layout, where the pump displacement control is carried out by two linear actuators and a two-way pilot control valve, has been analysed. The paper focuses on the dimensioning of the front areas of the actuators considering two kinematic solutions, linear and rotational, for the external ring. Through a simulation model, validated by experimental tests, the influence of different pressure control strategies on the dimensioning has been investigated

Experimental Procedure for Measuring the Energy Consumption of IC Engine Lubricating Pumps during a NEDC Driving Cycle

The paper presents an experimental procedure for comparing different families of IC Engine lubricating pumps in terms of total consumed energy in a NEDC driving cycle. Measures are performed on a test rig able to reproduce the oil temperature profile, the lubrication circuit permeability and its variation during the engine warm-up. The pump under test is driven by a variable speed electric motor supplying the engine velocity profile of the driving cycle. The load on the pump is generated by means of a variable restrictor controlled in a closed loop by a proper combination of speed, temperature, flow rate and pressure signals in order to replicate the typical permeability of the lubricating circuit. The method has been applied to a 15 cc/rev crankshaft mounted gerotor pump for a medium displacement Diesel engine; the flow-pressure characteristics of the lubricating circuit at different temperatures and the oil heating rate measured on the engine have been supplied to the test rig control system. The reference pump has been contrasted with a crankshaft mounted variable displacement vane pump with absolute pressure limiter device and an off-axis external gear pump with the same displacement and pressure setting. Experimental tests bring to evidence the advantage of the variable displacement pump during short trips with cold start, while the external gear pump prevails at the end of NEDC cycle where highest engine speeds and oil temperatures are reached.

Geometry Assessment of Variable Displacement Vane Pumps

The paper brings to evidence the effect that geometry of the stator ring of variable displacement radial pumps bears on performance characteristics of these units. The type of motion of the stator ring (linear or rotational), the location of the center of rotation, the porting plate integral with the casing or with the stator ring all have remarkable effects on the pump steady state and dynamic performance. At steady state, an influence exists on the attainable minimum displacement and on the deviation of discharge pressure from the desired setting when displacement is being controlled. In turn, dynamic performance is affected by changes in port plate timing as stator position and displacement undergo transitions. Specific attention is then committed to variable displacement vane pumps for internal combustion engines lubrication where an additional and foremost effect is investigated concerning the issues entailed by internal forces distribution on the stator ring that originate from incomplete chambers filling at high rotational pump speed.

Development of a Quieter Variable-Displacement Vane Pump for Automotive Hydraulic Power Steering System

In an automotive hydraulic power steering system a variable-displacement vane pump that is equipped with a control device for adjusting the eccentricity of the cam ring and thus pump delivery flow rate according to the pump rotational speed (i.e. vehicle speed) is gradually being used for energy saving in place of a fixed-displacement vane pump. However, fluid-borne noise radiating into the passenger compartment has greatly increased following this replacement, and, therefore, countermeasures to reduce pump source flow ripple have been required more than anything else to further spread its usage. This paper reports on development research of a quieter (low fluid-borne noise level) varia-ble-displacement vane pump for HPS systems. First, it is indicated based on both experimental measurements and sim-ulation analysis of pump source flow ripple that the excessive increase of fluid-borne noise produced by existing varia-ble-displacement vane pumps equipped with a cylindrical cam ring is mainly caused by vane bounce occurring in the trapping sections near the bottom dead center, which is difficult to prevent when a conventional cylindrical (completely round profile) cam ring is used. Next, a new cam ring profile for preventing vane bounce called a “modified profile cam ring” is proposed and its effectiveness is examined by noise tests in the passenger compartment of a real car as well as measurements of pump source flow ripple in a bench test circuit. The proposed cam ring is found to be successful in reducing fluid-borne noise to at least the level of a fixed pump. The newly developed types of pumps have already been put into practice in several kinds of automobiles.

The characteristics of pressure ripple in variable displacement vane pumps: Comparison between theory and experiment

This paper reports on the theoretical and experimental study on the discharge pressure ripples in a variable displacement vane pump. The pressure ripple in the delivery port is caused by flow ripple, which is induced by variation of pumping chamber volume. The other reason is the reverse flow from the outlet volume produced by the pressure difference between the pumping chamber and the outlet volume when the pumping chamber is connected to the outlet volume. In this study, a mathematical model is presented for analysing discharge pressure ripple, which includes vane detachment, cam ring movement and fluid inertia effects in a V-groove in the side plate. The model is applied to predict the level and the waveform of the discharge pressure ripples for various operating conditions. An experiment was performed to verify the theoretical analysis. The theoretical results provided in this study show a good agreement with the experimental results. This analytical model can predict the magnitude of discharge pressure ripple in variable displacement vane pumps and thus is useful for achieving optimal design of vane pumps.

自動車油圧パワーステアリング用可変容量形ベーンポンプの流体伝ぱ騒音の低減化

In an automotive hydraulic power steering system a variable-displacement vane pump, which is equipped with a control de vice for adjusting the eccentricity of the cam ring appropriately according to the pump rotational speed (ie., vehicle speed), has gradually begun to be used for energy saving in place of a fixed-displacement vane pump. However, fluid-borne noise radiated into the passenger compartment has greatly increased following this replacement, and therefore countermeasures to reduce pump source flow ripple have been required more than anything else to further spread its usage. This paper presents development research of a quieter (low-fluid-borne noise level) variable-displacement vane pump for HPS systems. First, it is indicated based on both the measurements and simulation analysis of pump source flow ripple that the excessive increase of fluid borne noise produced by existing variable-displacement vane pumps is mainly caused by vane bounce occurring in the trapping sections near dead centers, which is difficult to prevent when conventional cylindrical (completely round profile) cam ring is used Next, a new cam ring profile for preventing vane bounce called the “modified profile cam ring” is proposed and its effectiveness is examined by noise tests in the passenger compartment of a real car as well as measurements of pump source flow ripple in the bench test circuit The proposed cam ring is found to be able to reduce fluid-borne noise at least to the level of a fixed pump. The newly developed types of pumps have already been put into practice in several kinds of automobiles.

SURGE IN A PRESSURE-COMPENSATED POSITIVE DISPLACEMENT VANE-PUMP

In this paper, we revealed a factor causing the remarkably large amplitude delivery-pressure oscillation with quite low frequency, occurring often in pressure-compensated variable displacement vane pumps under deadhead conditions. It was found experimentally and theoretically that the pump instability originates in the fact that the gradient, ∂A/∂E is significantly negative, where A is time-averaged effective area for the internal pressure compensation force and E is the cam ring eccentricity. Also this phenomenon is regarded as same as surging of the turbo-fan.

可変容量形ベーンポンプにおけるベーンの挙動 第１報 圧力上昇過程のベーン離間現象

In a variable displacement vane pump, the vane jumping phenomenon-vanes detaching from the cam ring-causes the pressure fluctuations and decreases the volumetric efficiency.This paper describes the reason why the marked detachment of vanes takes place in the process of compression from the suction port to the delivery port. We have measured the movements of the vane by an eddy current displacement sensor which was mounted in the rotor. Setting the eccentricities of the cam ring to the rotor, we could show the motion locus of the vane tip, and also obtain the angular position of the detachment and re attachment of the jumping vane. It was found that the maximum distance between the jumping vane and the cam ring reaches to about 0.8mm.By examining the pressure of the pumping chamber, it is clear that the vane jumping is caused by excess pre-compression at the dead-volume zone, not by the surge pressure due to back-flows from the delivery side. Furthermore, in order to compare with the experimental results, the pressure of the pumping chamber and the motion of the vane tip have been simulated by applying an equation of continuity to the pumping chamber and an equation of motion to its forward vane respectively. Consequently, the calculation results approximately agree with the experimental values regarding the positional deviation of the eccentricities.