Instantaneous torque, energy saving and flow rate ripple analysis of a common rail pump equipped with different delivery-pressure control systems

2017 ◽  
Vol 19 (10) ◽  
pp. 1036-1047 ◽  
Author(s):  
Alessandro Ferrari ◽  
Ruggero Vitali
Keyword(s):  
High Pressure ◽  
Energy Saving ◽  
Flow Rate ◽  
Control Strategy ◽  
Pressure Control ◽  
Common Rail ◽  
Injection System ◽  
Rail Pressure ◽  
High Pressure Pump ◽  
Rail Pressure Control

A mechanical model of a high-pressure pump of a common rail fuel injection system is presented and validated by comparison with experimental instantaneous pump shaft torque and pump piston lift data. The instantaneous torque has been measured with a high-performance torque meter installed on a hydraulic rig for testing pieces of injection apparatus. In the model, the mechanics of the piston plunger and the forces exchanged between pistons and cam are simulated, and friction losses between mobile parts are taken into account. The numerical tool is used to investigate the dynamical performance of the high-pressure pump and to analyse the impact of the rail pressure control strategy on instantaneous torque, energy saving and flow rate ripple. The rail pressure control strategy, based on the application of a fuel metering valve at the pump inlet, gives rise to an improved hydraulic efficiency of the injection system at part loads and to a moderate rate of pressure increase in the pumping chamber at part loads. However, the rail pressure control strategy based on the installation of a pressure control valve at one rail extremity leads to a reduction in the pump flow rate ripple and to a diminution in the fatigue stress. Furthermore, cavitation problems can occur during intake and early compression phases of the pump cycle when the fuel metering unit is working.

Fully predictive Common Rail fuel injection apparatus model and its application to global system dynamics analyses

2016 ◽  
Vol 18 (3) ◽  
pp. 273-290 ◽  
Author(s):  
Alessandro Ferrari ◽  
Pietro Pizzo
Keyword(s):  
High Pressure ◽  
Control System ◽  
Fuel Injection ◽  
Time History ◽  
Pressure Control ◽  
Rail Pressure ◽  
High Pressure Pump ◽  
Pressure Time ◽  
Pressure Control System ◽  
Injection Apparatus

A fully predictive model of a Common Rail fuel injection apparatus, which includes a detailed simulation of rail, pump, piping system, injectors and rail pressure control system, is presented and discussed. The high-pressure pump and injector sub-models have been validated separately and then coupled to the rail and pressure control system sub-models. The complete predictive model has been validated and applied to investigate the effects of the dynamics of each component of the injection apparatus on the rail pressure time history. Variable timing of the high-pressure pump delivery phases has also been considered, and the influence of this parameter on the injection performance has been analysed for both single- and multiple-injection events. Furthermore, the injection system dynamics during the transients between steady-state working conditions has been investigated in order to highlight the role played by the dynamic response of the pressure control system on the rail pressure time history.

scholarly journals EFFECT OF ETHANOL ON PERFORMANCE AND DURABILITY OF A DIESEL COMMON RAIL HIGH PRESSURE FUEL PUMP

Transport ◽  
2015 ◽  
Vol 31 (3) ◽  
pp. 305-311 ◽  
Author(s):  
Tomas Mickevičius ◽  
Stasys Slavinskas ◽  
Raimondas Kreivaitis
Keyword(s):  
High Pressure ◽  
Diesel Fuel ◽  
Fuel Injection ◽  
Common Rail ◽  
Injection System ◽  
Fuel Injection System ◽  
Fuel Blend ◽  
High Pressure Pump ◽  
Fuel Pump ◽  
Fuel Delivery

This paper presents a comparative experimental study for determining the effect of ethanol on functionality of a high pressure pump of the common rail fuel injection system. For experimental durability tests were prepared two identical fuel injection systems, which were mounted on a test bed for a fuel injection pump. One of the fuel injection systems was feed with diesel fuel; other fuel injection system was fuelled with ethanol–diesel fuel blend. A blend with 12% v/v ethanol and 88% v/v diesel fuel and low sulphur diesel fuel as a reference fuel were used in this study. To determine the effect of ethanol on the durability of the high pressure pump total fuel delivery performance and surface roughness of pump element were measured prior and after the test. Results show that the use of the ethanol–diesel blend tested produced a negative effect on the durability of the high pressure fuel pump. The wear of plungers and barrels when using ethanol–diesel fuel blend caused a decrease in fuel delivery up to 30% after 100 h of operation.

Modal Analysis of Fuel Injection Systems and the Determination of a Transfer Function Between Rail Pressure and Injection Rate

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
A. Ferrari ◽  
F. Paolicelli
Keyword(s):  
High Pressure ◽  
Transfer Function ◽  
Modal Analysis ◽  
Flow Rate ◽  
Fuel Injection ◽  
Injection System ◽  
Rail Pressure ◽  
Hydraulic Circuit ◽  
Lumped Parameter ◽  
Injection Apparatus

A detailed analysis of a common rail (CR) fuel injection system, equipped with solenoid injectors for Euro 6 diesel engine applications, has been performed in the frequency domain. A lumped parameter numerical model of the high-pressure hydraulic circuit, from the pump delivery to the injector nozzle, has been realized. The model outcomes have been validated through a comparison with frequency values that were obtained by applying the peak-picking technique to the experimental pressure time histories acquired from the pipe that connects the injector to the rail. The eigenvectors associated with the different eigenfrequencies have been calculated and physically interpreted, thus providing a methodology for the modal analysis of hydraulic systems. Three main modal motions have been identified in the considered fuel injection apparatus, and the possible resonances with the external forcing terms, i.e., pump delivered flow rate, injected flow rate, and injector dynamic fuel leakage through the pilot valve, have been discussed. The investigation has shown that the rail is mainly involved in the first two vibration modes. In the first mode, the rail performs a decoupling action between the high-pressure pump and the downstream hydraulic circuit. Consequently, the oscillations generated by the pump flow rates mainly remain confined to the pipe between the pump and the rail. The second mode is centered on the rail and involves a large part of the hydraulic circuit, both upstream and downstream of the rail. Finally, the third mode principally affects the injector and its internal hydraulic circuit. It has also been observed that some geometric features of the injection apparatus can have a significant effect on the system dynamics and can induce hydraulic resonance phenomena. Furthermore, the lumped parameter model has been used to determine a simplified transfer function between rail pressure and injected flow rate. The knowledge obtained from this study can help to guide designers draw up an improved design of this kind of apparatus, because the pressure waves, which are triggered by impulsive events and are typical of injector working, can affect the performance of modern injection systems, especially when digital rate shaping strategies or closely coupled multiple injections are implemented.

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