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Technical Paper

A Numerical and Experimental Study Towards Possible Improvements of Common Rail Injectors

2002-03-04
2002-01-0500
The aim of this work is to propose modifications to the managing of the 1st generation Common Rail injectors in order to reduce actuation time towards multiple injection strategies. The current Common Rail injector driven by 1st ECU generation is capable of operating under stable conditions with a minimum dwell between two consecutive injections of 1.8 ms. This limits the possibility in using proper and efficient injection strategies for emission control purposes. A previous numerical study, performed by the electro-fluid-mechanical model built up by Matlab-Simulink environment, highlighted different area where injector may be improved with particular emphasis on electronic driving circuit and components design. Experiments carried out at injector Bosch test-bench showed that a proper control of the solenoid valve allowed reducing drastically the standard deviation during the pilot pulses.
Technical Paper

Achieving the Max - Potential from a Variable Compression Ratio and Early Intake Valve Closure Strategy by Combination with a Long Stroke Engine Layout

2017-09-04
2017-24-0155
The combination of geometrically variable compression (VCR) and early intake valve closure (EIVC) proved to offer high potential for increasing efficiency of gasoline engines. While early intake valve closure reduces pumping losses, it is detrimental to combustion quality and residual gas tolerance due to a loss of temperature and turbulence. Large geometric compression ratio at part load compensates for the negative temperature effect of EIVC with further improving efficiency. By optimizing the stroke/bore ratio, the reduction in valve cross section at part load can result in greater charge motion and therefore in turbulence. Turbocharging means the basis to enable an increase in stroke/bore ratio, called β in the following, because the drawbacks at full load resulting from smaller valves can be only compensated by additional boosting pressure level.
Technical Paper

Analysis of the Mixture Formation at Partial Load Operating Condition: The Effect of the Throttle Valve Rotational Direction

2015-09-06
2015-24-2410
In the next incoming future the necessity of reducing the raw emissions leads to the challenge of an increment of the thermal engine efficiency. In particular it is necessary to increase the engine efficiency not only at full load but also at partial load conditions. In the open literature very few technical papers are available on the partial load conditions analysis. In the present paper the analysis of the effect of the throttle valve rotational direction on the mixture formation is analyzed. The engine was a PFI 4-valves motorcycle engine. The throttle valve opening angle was 17.2°, which lays between the very partial load and the partial load condition. The CFD code adopted for the analysis was the FIRE AVL code v. 2013.2. The exhaust, intake and compression phases till TDC were simulated: inlet/outlet boundary conditions from 1D simulations were imposed.
Technical Paper

Dynamic Evolution of the 3-D Flow Field During the Latter Part of the Intake Stroke in an IC Engine

1998-02-23
980485
Measurements of the temporal evolution of the 3-D velocity field were performed in an IC engine during the latter part of the intake stroke using a Water Analog Engine Simulation Rig and the 3-D Particle Tracking Velocimetry technique (3-D PTV). The engine head tested was a typical 4 valve, pent-roof type combustion chamber shape with slightly asymmetric intake passages to favor a preferred swirl with one intake valve almost deactivated to reinforce the swirling flow pattern. This study was aimed at characterizing the dynamic development of the flow field resulting from this head geometry and asymmetric valve event during the latter part of the intake stroke. The most salient feature of this flow field is that this final, highly organized and energetic vortex does not emerge until relatively late in the intake stroke. Even as late at 60° BBDC, the flow field is still characterized by smaller (of the order of 1/4 or 1/3 of the bore size) structures, particularly in the tumble plane.
Technical Paper

Investigations on the Potential of a Variable Miller Cycle for SI Knock Control

2013-04-08
2013-01-1122
A promising combustion technology for DISI downsizing engines is the Miller cycle. It is based on an early intake valve closing for the separation of effective and geometric compression ratio. Therefore IAV has prepared a turbocharged DISI test engine with a high geometric compression ratio. This engine is equipped with the Schaeffler “UniAir” variable valve train in order to investigate a variable Miller cycle valve timing in the turbocharged map area. The goal is to investigate whether and how a rapidly variable Miller cycle can influence the knocking behavior. Therefore its potential for a SI knock control can be evaluated. The investigated parameters in a steady-state engine dyno mode were the intake valve closing timing, the intake camshaft phasing and the ignition timing. A variable intake valve closing Miller cycle strategy, a variable intake camshaft phasing Miller cycle strategy and a state-of-the- art ignition timing strategy have been investigated.
Technical Paper

Modeling and Identification of a Gasoline Common Rail Injection System

2014-04-01
2014-01-0196
The precision of direct fuel injection systems of combustion engines is crucial for the further reduction of emissions and fuel consumption. It is influenced by the dynamic behavior of the fuel system, in particular the injection valves and the common rail pressure. As model based control strategies for the fuel system could substantially improve the dynamic behavior, an accurate model of the common rail injection system for gasoline engines - consisting of the main components high-pressure pump, common rail and injection valves - that could be used for control design is highly desirable. Approaches for developing such a model are presented in this paper. For each key component, two models are derived, which differ in temporal resolution and number of degrees of freedom. Experimental data is used to validate and compare the models. The data was generated on a test bench specifically designed and built for this purpose.
Technical Paper

Modeling and Simulation of a Shift Hydraulic System for a Stepped Automatic Transmission

2003-03-03
2003-01-0314
It is well-known that the shift hydraulic system plays a major role in the operation of stepped automatic transmissions. The main functions of the hydraulic system are to generate and maintain adequate fluid pressures for transmission operation, as well as to initiate gear shifts and control shift quality. Therefore, quantitative understanding of the dynamic behavior of the hydraulic system is critical to the improvement of automatic transmission performance. This paper presents the development of a nonlinear dynamic model for the shift hydraulic system of a stepped automatic transmission. The model includes all necessary dynamics, namely, hydraulic line pressure dynamics, solenoid valve dynamics, pressure control valve dynamics, as well as clutch and accumulator dynamics. The model is developed and implemented using Matlab/Simulink®, and is validated against experimental data.
Technical Paper

Nonlinear Modeling of an Electromagnetic Valve Actuator

2006-04-03
2006-01-0043
This paper presents the modeling of an Electromagnetic Valve Actuator (EMV). A nonlinear model is formulated and presented that takes into account secondary nonlinearities like hysteresis, saturation, bounce and mutual inductance. The uniqueness of the model is contained in the method used in modeling hysteresis, saturation and mutual inductance. Theoretical and experimental methods for identifying parameters of the model are presented. The nonlinear model is experimentally validated. Simulation and experimental results are presented for an EMV designed and built in our laboratory. The experimental results show that sensorless estimation could be a possible solution for position control.
Technical Paper

The Controlled Vane-Type Oil Pump for Oil Supply on Demand for Passenger Car Engines

2002-03-04
2002-01-1319
The oil supply of combustion engines today is typically realized by oil pumps with constant displacement. To secure the operational safety in hot idling these pumps are oversized, what causes low efficiency in most of operating speeds. IAV developed a vane-type oil pump, which allows to infinitely regulate the delivery rate. Because of no oil release over a pressure limiting valve the pump achieves a higher efficiency in a wide range of operation. The design of the theoretical delivery characteristic allows the calculated and particular increase of oil pressure to avoid critical operating conditions and to support hydraulically operated functions as variable camshaft timing.
Technical Paper

The Effect of the Throttle Valve Rotational Direction on the Tumble Motion at Different Partial Load Conditions

2015-04-14
2015-01-0380
In PFI and GDI engines the tumble motion is the most important charge motion for enhancing the in-cylinder turbulence level at ignition time close to the spark plug position. In the open literature different studies were reported on the tumble motion, experimental and not. In the present paper the research activity on the tumble generation at partial load and very partial load conditions was presented. The added value of the analysis was the study of the effect of the throttle valve rotational direction on the tumble motion and the final level of turbulence at the ignition time close to the spark plug location. The focus was to determine if the throttle rotational direction was crucial for the tumble ratio and the turbulence level. The analyzed engine was a PFI 4-valves motorcycle engine. The engine geometry was formed by the intake duct and the cylinder. The CFD code was FIRE AVL code 2013.1.
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