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Nowadays stringent emission regulations are pushing towards new air management strategies like LP-EGR and HP/LP mix both for passenger car and heavy duty applications, increasing the engine control complexity. Within a project in collaboration between Kohler Engines EMEA, Politecnico di Torino, Ricardo and Denso to exploit the potential of EGR-Only technologies, a 3.4 liters KDI 3404 was equipped with a two stage turbocharging system, an extremely high pressure FIS and a low pressure EGR system. The LP-EGR system works in a closed loop control with an intake oxygen sensor actuating two valves: an EGR valve placed downstream of the EGR cooler that regulates the flow area of the bypass between the exhaust line and the intake line, and an exhaust flap to generate enough backpressure to recirculate the needed EGR rate to cut the NOx emission without a specific aftertreatment device.

A 2200 cc engine head for marine applications has been analysed and optimized by means of decoupled CFD and FEM simulations in order to assess the fatigue strength of the component. The fluid distribution within the cooling jacket was extensively analysed and improved in previous works, in order to enhance the performance of the coolant galleries. A simplified methodology was then proposed in order to estimate the thermo-mechanical behaviour of the head under actual engine operation [1, 2]. As a consequence of the many complex phenomena involved, an improved approach is presented in this paper, capable of a better characterization of the fatigue strength of the engine head under both high-cycle and low-cycle fatigue loadings. The improved methodology is once again based on a decoupled CFD and FEM analysis, with relevant improvements added to both simulation realms.

The aim of this paper is the analysis of a Diesel engine lubrication circuit with a tri-dimensional CFD technique. The simulation model was built using Pumplinx®, a commercial code by Simerics Inc.®, developed and optimized for predicting oil flow rates and cavitation phenomena. The aim of this paper is, also, to show that this code is able to satisfactorily model, in a very “economic” way, an unsteady hydraulic system such as the lubrication circuit First of all, an accurate model of a lubrication circuit oil pump will be described. The model was validated with data from an experimental campaign carried out in the hydraulic laboratory of the Industrial Engineering Department of the University of Naples. Secondly, the oil pump model was coupled with a tri-dimensional model of the entire lubrication circuit, in order to compute all the hydraulic resistances of the network and the oil consumption rate of the circuit components

Although the use of Exhaust Gas Recirculation (EGR) is nowadays mandatory for automotive diesel engines to achieve NOx emissions levels complying with more and more stringent legislation requirements, electronically controlled EGR systems still represent an expensive technology, often unsuitable for small diesel engines for off-road applications or for two/three wheelers. An interesting option for these categories of small diesel engines is the so-called “internal EGR”, which is obtained by modifying the intake or the exhaust valve lift profile, in order to increase the fraction of exhaust residuals at the end of the intake stroke. Different valve lift profiles were therefore evaluated for a 2 cylinders, 700 cc, Lombardini IDI diesel engine, equipping a light 4 wheelers vehicle.

A methodology has been developed by the authors, in which non-intrusive measurements (engine block vibration) are used for diagnostic purposes of combustion process in Diesel engines. A previous paper of the authors has been devoted to demonstrate the direct relationship between in-cylinder pressure and accelerometer signals, when the vibration transducer is placed in sensitive location. Moreover, in the engine block vibration a frequency band in which such a relationship is very strong has been selected. The aim of this work is to provide a deeper insight into the effects of injection parameters on engine block vibration, in order to investigate the possibility of detecting modification of the in-cylinder pressure evolution by means of the accelerometer signal with the final objective of optimizing the combustion process by means of non-intrusive transducer.

An engine head of a common rail direct injection engine with three in line cylinders for Light Transportation Vehicle (LTV) applications has been analyzed and optimized by means of uncoupled CFD and FEM simulations in order to assess the strength of the components. This paper deals with a structural stress analysis of the cylinder head considering the thermal loads computed through an CFD simulation and a detailed FV heat-transfer analysis. The FE model of the cylinder head includes the contact interaction between the main parts of the cylinder head assembly and it is subjected to the gas pressure, thermal loads and the effects of bolts tightening and valve springs. The results, in term of temperature field, are validated by comparing with those obtained by means of experimental analyses. Then a fatigue assessment of the cylinder head has been performed using a multi-axial fatigue criterion.

This paper presents the results of an experimental analysis on a multi-cylinder diesel engine, in which in-cylinder pressure and accelerometer transducers are used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive measurements. Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals, as well as the sensitivity of the engine surface vibration to variation of injection parameters when the accelerometer is placed in sensitive location of the engine block. Moreover, the accelerometer trace has revealed to be able to locate in the crank-angle domain important phenomena characterizing the combustion process (the start of pre-mixed combustion, the crank angle value corresponding to the beginning of diffusive combustion and to the in-cylinder pressure maximum value).

The present work aims at developing and setting up a methodology in which non-intrusive measurements (engine block vibration) are used for monitoring combustion characteristics (combustion diagnosis, combustion development). The engine block vibration appears as a very complex signal in which different sources can be identified, since every moving component or physical process involved in the operation of the engine produces a vibration signal (exhaust valve open/close, inlet valve open/close, fuel injection, combustion, piston slap). Aimed at monitoring the engine running condition, the information carried by the vibration signal has to be broken down into its various contributions and then they have to be related to their respective excitation sources. Concerning combustion-induced vibration, experimental measures has been at first devoted to the selection of the best location where to place the piezoelectric accelerometer.

This work fits into a research program in which the multi-cylinder diesel engine block vibration signal is used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive transducer. Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals in a fixed frequency band. It was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, the accelerometer trace has revealed to be able to locate in the crank–angle domain important phenomena characterizing the combustion process.

The present paper describes the results of an experimental activity performed on a small diesel engine for quadricycles, a category of vehicles that is spreading in Europe and is recently spreading over Indian countries. The engine is a prototype three-cylinder with 1000 cc of displacement and it is equipped with a direct common-rail injection system that reaches a maximum pressure of 1400 bar. The engine was designed to comply with Euro 4 emission standard that is a future regulation for quadricycles. It is worth underlining that the engine can meet emission limits just with EGR system and a DOC, without DPF. Various diesel/RME blends were tested; pure diesel and biodiesel fuels were also used. The investigation was carried out at the engine speeds of 1400, 2000 and 3400 rpm and full load. Combustion characteristics of both blended and pure RME were analyzed by means of in-cylinder pressure and heat released histories.

Many efforts are being currently devoted to the development of diagnostic techniques based on nonintrusive measurements aimed at defining the injection parameters able to optimize the combustion process. Previous papers of the authors have demonstrated a direct relationship between in-cylinder pressure and engine block vibration signals. Besides, it was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, in the accelerometer signal, a frequency band in which such a relationship is very strict has been selected. The aim of the present work is to establish a reliable relation between the main characteristics of the in-cylinder pressure curve and the vibration trend, by means of a deeper insight into the engine block signal. The final objective is to monitor the combustion behavior by means of a non-intrusive transducer.

To comply with Stage IV emission standard for off-road engines, Kohler Engines has developed the 100kW rated KDI 3.4 liters diesel engine, equipped with DOC and SCR. Based on this engine, a research project in collaboration between Kohler Engines, Ricardo, Denso and Politecnico di Torino was carried out to exploit the potential of new technologies to meet the Stage IV and beyond emission standards. The prototype engine was equipped with a low pressure cooled EGR system, two stage turbocharger, high pressure fuel injection system capable of very high injection pressure and DOC+DPF aftertreatment system. Since the Stage IV emission standard sets a 0.4 g/kWh NOx limit for the steady state test cycle (NRSC), that includes full load operating conditions, the engine must be operated with very high EGR rates (above 30%) at very high load.

This paper describes the design and performance development of the new Kohler / Lombardini KDI engine range which is a family of 3 and 4 cylinder, in line, water cooled engines covering the power range 37 - 56 kW. The paper covers the following aspects: Performance and economy Exhaust emissions over legislative cycles Deterioration factor test results Effect of fuel quality on emissions

In this paper, a numerical and experimental assessment of post injection potential for soot emissions mitigation in an off-road diesel engine is presented, with the aim of supporting hardware selection and engine calibration processes. As a case study, a prototype off-road 3.4 liters 4-cylinder diesel engine developed by Kohler Engines was selected. In order to explore the possibility to comply with Stage V emission standards without a dedicated aftertreatment for NOx, the engine was equipped with a low pressure cooled Exhaust Gas Recirculation (EGR), allowing high EGR rates (above 30%) even at high load. To enable the exploitation of such high EGR rates with acceptable soot penalties, a two-stage turbocharger and an extremely high-pressure fuel injection system (up to 3000 bar) were adopted. Moreover, post injections events were also exploited to further mitigate soot emissions with acceptable Brake Specific Fuel Consumption (BSFC) penalties.

An engine head for microcar applications has been analysed and optimized by means of uncoupled CFD and FEM simulations in order to assess the strength of the component. This paper deals with a structural stress analysis of the cylinder head considering the thermal loads computed through an uncoupled CFD simulations of cylinder combustion and in cooling flow passages. The FE model includes the contact interaction between the main parts of the cylinder head assembly and it also considers the effects of bolts tightening and valve springs. Temperature dependent non-linear material properties are considered. The results, in term of temperature field, are validated by comparing with those obtained by means of experimental analyses; the engine has been instrumented with thermocouples on crank case and on cylinder head.