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This session covers topics regarding new CI and SI engines and components. This includes analytical, experimental, and computational studies covering hardware development as well as design and analysis techniques. Presenter Sung Hoon Lee, Hyundai Motor Co.

A variety of methodologies to use embedded multicore controllers efficiently has been discussed in the last years. Several assumptions are usually made in the automotive domain, such as static assignment of tasks to the cores. This paper shows an approach for efficient task allocation depending on different system modes. An engine management system (EMS) is used as application example, and the performance improvement compared to static allocation is assessed. The paper is structured as follows: First the control algorithms for the EMS will be classified according to operating modes. The classified algorithms will be allocated to the cores, depending on the operating mode. We identify mode transition points, allowing a reliable switch without neglecting timing requirements. As a next step, it will be shown that a load distribution by mode-dependent task allocation would be better balanced than a static task allocation.

Since the amount of emitted CO2 is directly related to car fuel economy, attention is being drawn to DISI (Direct-Injection Spark-Ignition) engines, which have better fuel economy than conventional gasoline engines. However, it has been a problem that the rich air-fuel mixtures associated with fuel films during cold starts due to spray impingement produce particulate matter (PM). In predicting soot formation, it is important to predict the mixture field precisely. Thus, accurate spray and film models are a prerequisite of the soot model. The previous models were well matched with low-speed collision conditions, such as those of diesel engines, which have a relatively high ambient pressure and long traveling distances. Droplets colliding at low velocities have an order of magnitude of kinetic energy similar to that of the sum of the surface tension energy and the critical energy at which the splash occurs.

As the original engine sound is usually not enough to satisfy the driver’s desire for a sporty and fascinating sound, Active Noise Control (ANC) and Active Sound Design (ASD) have been great technologies in automobiles for a long time. However, these technologies which enhance the sound of vehicles using loud speakers or electromagnetic actuators etc. lead to the increase of cost and weight due to the use of external amplifiers or actuators. This paper presents a new technology for generating a target sound by the active control of a permanent magnet synchronous motor (PMSM) of a mass-production steering system. The existing steering hardware or motor is not changed, but only additional software is added. Firstly, an algorithm of this technology, called Active Sound Generation (ASG), is introduced which is compiled and included in the ECU target code. Then the high frequency noise issue and its countermeasures are presented.

In order to extend the operability limit of the gasoline compression ignition (GCI) engine, as an avenue for low temperature combustion (LTC) regime, the effects of parametric variations of engine operating conditions on the performance of six-stroke GCI (6S-GCI) engine cycle are numerically investigated, using an in-house 3D CFD code coupled with high-fidelity physical sub-models along with the Chemkin library. The combustion and emissions were calculated using a skeletal chemical kinetics mechanism for a 14-component gasoline surrogate fuel. Authors’ previous study highlighted the effects of the variation of injection timing and split ratio on the overall performance of 6S-GCI engine and the unique mixing-controlled burning mode of the charge mixtures during the two additional strokes. As a continuing effort, the present study details the parametric studies of initial gas temperature, boost pressure, fuel injection pressure, compression ratio, and EGR ratio.

The combustion process using two fuels with different reactivity, known as dual-fuel combustion or RCCI is mainly studied to reduce emissions while maintaining thermal efficiency compared to the conventional diesel combustion. Many studies have proven that dual-fuel combustion has a positive prospect in future combustion to achieve ultra-low engine-out emissions with high indicated thermal efficiency. However, a limitation on high-load expansion due to the higher maximum in-cylinder pressure rise rate (mPRR) is a main problem. Thus, it is important to establish the operating strategy and study the effect of in-cylinder flow motion with dual-fuel combustion to achieve a low mPRR and emissions while maintaining high-efficiency. In this research, the characteristics of gasoline-diesel dual-fuel combustion on different hardware were studied to verify the effect of the in-cylinder flow motion on dual-fuel combustion.

A new approach to achieve better customer perception of overall vehicle quietness is the sound balance improvement of vehicle interior sound during driving. Interior sound is classified into 3 primary sound source shares such as engine sound relative to revolution speed, tire road noise and wind noise relative to vehicle speed. Each interior sound shares are classified using the synchronous time-domain averaging method. The sound related to revolution order of engine and auxiliaries is considered as engine sound share, tire road noise and wind noise shares are extracted by multiple coherent output power analysis. Sound balance analysis focuses on improving the relative difference in interior sound share level between the 3 primary sound sources. Virtual sound simulator which is able to represent various driving conditions and able to adjust imaginary sound share is built for several vehicles in same compact segment.

As fuel injection strategies in spark-ignition (SI) engines have been diversified, inhomogeneous mixing of the fuel-air mixture can occur to varying extents during mixture preparation. In this study, we analyzed the effect of inhomogeneous mixing on the knocking characteristics of iso-octane and air mixture under a standardized fuel testing condition for research octane number (RON), based on ASTM D2699. For this purpose, we assumed that both lean spots and rich spots existed in unburned gas during compression stroke and flame propagation and calculated the thermodynamic state of the spots by using an in-house multi-zone, zero-dimensional SI engine model. Then, the ignition delay was measured over the derived thermodynamic profiles by using rapid compression machine (RCM), and we calculated ξ, the ratio of sound speed to auto-ignition propagation speed, based on Zel’dovich and Bradley’s ξ − ε theory to estimate knock intensity.

This paper introduces a systematic wiring guideline which includes coupling noise calculation, wire layout design, and wire type selection methodologies. The coupling theory between wires has been introduced long time ago but it was not successfully applied to real automotive wiring design due to the complexity in the theory such as large number of parameters and many different conditions in automotive wiring environment. In this paper, the complexity is reduced by separating physical parameters and electrical parameters and identifying controllable parameters and given parameters. This paper first introduces parameters which are used in the coupling equations and automotive wiring design, then the coupling noise calculation method which uses the coupling equations is introduced. The systematic automotive wiring guideline which prevents noise problem in various design stage such as system filter design, wire layout design, wire type selection is introduced.

The series-parallel hybrid electric vehicle(HEV), which employs a planetary gear set to combine one internal combustion engine(ICE) and two electric motors(EMs), can take advantages of both series and parallel hybrid system. The efficient powertrain operating point of the system can be obtained by the instantaneous optimization of equivalent fuel consumption. However, heavy computational requirements and variable constraints of the optimization process make it difficult to build real-time control strategy. To overcome the difficulty, this study suggests the control strategy which divides the optimization process into 2 stages. In the first stage, a target of charge/discharge power is determined based on equivalent fuel consumption, then in the second stage, an engine operating point is determined taking power transfer efficiency into account.

Modeling of unburned hydrocarbon oxidation in an SI engine was performed in engine condition using modified one-step oxidation model. The new one-step equation was developed by modifying the Arrhenius reaction rate coefficients of the conventional one-step model. The modified model was well matched with the results of detailed chemical reaction mechanism in terms of 90 % oxidation time of the fuel. In this modification, the effect of pressure and intermediate species in the burnt gas on the oxidation rate investigated and included in developed one-step model. The effect of pressure was also investigated and included as an additional multiplying factor in the reaction equation. To simulate the oxidation process of piston crevice hydrocarbons, a computational mesh was constructed with fine mesh density at the piston crevice region and the number of cell layers in cylinder was controlled according to the motion of piston.

Characteristics of syngas combustion at various reforming ratios were studied numerically. The syngas was formed by the partial oxidation of methane to mainly hydrogen and carbon monoxide and cooled to ambient temperature. Stiochiometric and lean premixed flames of the mixtures of methane and the syngas were compared at the atmospheric temperature and pressure conditions. The adiabatic flame temperature decreased with the reforming ratio. The laminar burning velocity, however, increased with the reforming ratio. For stretched flames in a counterflow, the high temperature region was broadened with the reforming ratio. The maximum flame temperature decreased with the reforming ratio for the stoichiometric case, but increased for the lean case except for the region of very low stretch rate. The extinction stretch rate increased with the reforming ratio, implying that the syngas assisted flame is more resistance to turbulence level.

In order to investigate the characteristics of top ring groove deposit formation in gasoline and diesel engine, engine test and simulation test were performed. From component analysis of used oils sampled from actual running engines, oxidation and nitration for gasoline engine and soot content for diesel engine were selected as main parameters for evaluating oil degradation. In gasoline engine, deposit formation increases linearly with oxidation and nitration, and especially, oil oxidation is a dominant factor on the deposit formation rather than nitration. And, deposit formation increases gradually in low temperature ranges below 260°C even if oils are highly oxidized, but it increases rapidly if piston top ring groove temperature is above 260°C. In diesel engine, deposit formation is highly related to soot content in lubricating oils.

In this study, a series of tests have been carried out to evaluate the effects of the injection rate and timing on bsfc, NOx, and PM emissions in a heavy-duty diesel engine with TICS FIE system. Injection line pressure, cylinder pressure, NOx and smoke were measured with various injection times and injection rates. The injection rate was altered at a fixed injection timing, which could be realized either by changing the TICS setting time or by using different cam profiles. The injection time was varied by using TICS timing control function at a given setting time. A parametric study of the injection rate in in-line pump system was tried to correlate injection rate variations with combustion characteristics and emission. Two parameters, the injection pressure rising rate and the initially injected fuel quantity were introduced to characterize fuel injection.

Supervisory control strategy of a hybrid electric vehicle (HEV) provides target powers and operating points of an internal combustion engine and an electric motor. To promise efficient driving of the HEV, it is needed to find the proper values of control parameters which are used in the strategy. However, it is very difficult to find the optimal values of the parameters by doing experimental tests, since there are plural parameters which have dependent relationship between each other. Furthermore variation of the test results makes it difficult to extract the effect of a specific parameter change. In this study, a model based parameter optimization method is introduced. A vehicle simulation model having the most of dynamics related to fuel consumption was developed and validated with various experimental data from real vehicles. And then, the supervisory control logic including the control parameters was connected to the vehicle model.

This paper proposes a new screening attenuation evaluation method (PHSA) for hybrid power cables. Hybrid power cables connect battery, inverter and motor. As the noise and shield characteristics of these cables are different from general communication shield wires, new method for evaluating screening attenuation is needed. We considered the radiation direction, noise current path and various load terminations to evaluate the screening attenuation which is different from standard screening attenuation measurement. Feasibility and effectiveness of the proposed method were verified with real experiment results.

A vehicle drifts due to several reasons from its intended straight path even in the case of no steering input. The multibody dynamic analysis of vehicle drift during accelerating and braking are performed. This paper focuses on modeling and evaluating effects of suspension parameters, differential friction, engine mounting and C.G. location of the vehicle under multibody dynamic simulation environment. Asymmetry of geometry and compliance between left and right side is considered cause of drift. The sensitivities of the suspension parameters are presented for each driving condition. In case of acceleration, the interaction of differential friction and driveshaft stiffness and their influence on drift are also studied. For braking condition, suspension parameters such as initial toe variation of rear coupled torsion beam axle type suspension and kingpin inclination deviation of front suspension are studied including the braking force difference.

In order to understand the relationship between the location of piston ring gap and instantaneous change of oil consumption during engine operation, the ring rotation and instantaneous oil consumption were measured simultaneously in a hydrogen fueled single cylinder spark ignition engine. A radioactive-tracer technique was used to measure the rotational movement of piston ring. Two kinds of isotopes(60Co and 192Ir) with different energy level were mounted to the top and 2nd rings to measure each ring's movement independently. The instantaneous oil consumption was obtained by analyzing CO2 concentration in exhaust gas. From the result of ring rotational movement, typical patterns of ring rotation were obtained as follows; Rotational movements are usually initiated by changing the operating conditions. Piston rings tend to rotate easily under low load condition. The rotation speed of ring usually ranged in 0.2∼0.4 rev/min for top ring and 0.5∼0.6 rev/min for 2nd ring.

A gasoline homogeneous charged compression ignition (HCCI) called the controlled auto ignition (CAI) engine is an alternative to conventional gasoline engines with higher efficiency and lower emission levels. However, noise and vibration are currently major problems in the CAI engine. The problems result from fast burning speeds during combustion, because in the CAI engine combustion is controlled by auto-ignition rather than the flame. Thus, the ignition delay of the local mixture has to vary according to the location in the combustion chamber to avoid noise and vibration. For making different ignition delays, stratification of temperature or mixing ratio was tested in this study. In charge stratification, which determines the difference between the start of combustion among charges with different properties, two kinds of mixtures with different properties flow into two intake ports.

CAI engine is well known to be advantageous over conventional SI engines because it facilitates higher engine efficiency and lower emission (NOx and smoke). However, its limited operation range, large cyclic variation, and difficulty in heat release control are still unresolved obstacles. Previous studies showed that a high load range of the CAI engine is limited mainly by the combustion noise caused by a stiff pressure rise (knock), and that a low load range is also limited by the combustion instability caused by the high dilution of residual gas. In this study, the characteristics of each cycle were analyzed to find the cause of the cycle variation at the high load limit of CAI operation. Moreover, to improve combustion stability, we tested the in-cylinder fuel stratification by applying nonsymmetrical fuel injection to the intake port. Experiments were performed on a PFI single cylinder research engine equipped with dual CVVT and low lift (2 mm) cam shaft with NVO strategy.