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This paper reports on an experimental investigation of an SI single cylinder engine cycle-to-cycle variations. Two different ignition devices are studied: a spark plug and a non conventional ignition device, PJC (Pulsed Jet Combustion). In-cylinder pressure is analyzed via a complete heat release rate computation. A significant decrease in IMEP cycle-to-cycle variations can be achieved only when the initial burning rate is enhanced with PJC device for example. The cycle-to-cycle combustion variations (CA01, PMax, IMEP) are not improved in the same proportions. The PJC is a firing device which meets the objective of repeatable ultra-lean mixture ignition and development of combustion, but slightly lowers the global efficiency due to the increase of heat losses for high load running points.

It is well known that diesel particulate filters can be subjected to incomplete regeneration which can lead to DFP failure when a severe regeneration follows several partial regenerations. The following study concentrates on C-DPF (Catalyzed Diesel Particulate Filter) filters made of R-SiC (Re-crystallized Silicon Carbide) from Saint-Gobain and aims at studying the spatial soot distribution in the filter as a function of soot loading and regeneration efficiency. The soot distribution is deduced from a radial velocity profile at the rear of the filter which is measured using a specific test bench. In this work, an experimental protocol is designed to produce a controlled partial regeneration. This protocol allows the desired regeneration efficiency to be obtained. It can be observed that the better the regeneration efficiency is, the more the radial distribution of remaining soot in the filter is homogeneous. Consequently, regeneration is more efficient where the filter is more loaded.

To meet future pollutant emissions standards, it is crucial to be able to estimate the cycle by cycle in-cylinder mass and the composition of the combustion chamber charge. This charge consists of residual gases from the previous cycle, fresh air and fuel. Consequently, the estimation of the fresh air mass based on total in-cylinder mass is a function of residual gas fraction. This estimation is essential to compute the fuel mass to be injected. This paper proposes an algorithm, based on physical equations, which estimates the in-cylinder total mass based on cylinder pressure. A residual gas model, which computes the burned gas fraction, is then used to determine the fresh air mass. The paper shows that the algorithm, tested on a Spark Ignited engine, is very robust to noise. To test the estimator several parameters are varied: valve timing, cylinder pressure sampling period, residual gas fraction, cylinder pressure offset and exhaust gas temperature.

To meet future pollutant emissions standards, it is crucial to be able to estimate not only the cycle by cycle mass, but also the cycle by cycle composition of the combustion chamber charge. This charge consists of fresh air, fuel and residual gas from the previous cycle. Unfortunately, the residual gas fraction cannot be directly measured. Therefore, an experimental method has been designed to determine the residual gas fraction. The method is based on an in-cylinder sampling method coupled with CO2 analysis. A residual gas fraction model as a function of engine parameters and operating parameters has been developed. The parameters of the model have been fitted on the experimental results.

This paper follows a former one (Robinet [1]) which underlined the spark kernel hazardous development due to residual gas in the spark plug vicinity. A new igniter called FSP (Fueled Spark Plug) has been designed and compared to conventional spark plug. Its purpose is to sweep away the residual gas from the spark vicinity. This investigation has been performed in a standard research engine and an optical accesses engine. A faster heat release development and a more repeatable combustion for low-load operating conditions have been observed when firing with the FSP. The lean operating range is extended. The idle performances (IMEP covariance, ISC) have been improved as well as the emissions (CO and NOX). Unburned hydrocarbons emissions are raised due to non-optimal feed line design. Contrary to previous alternative igniter designs, residual gas sweeping can be switched on or off at will: in the latter case the FSP falls back to conventional spark plug operation.

Porous honeycombs filters have been widely used for diesel particulates filtration in passenger cars applications. In all current DPF applications, filter lifetime and design are dictated by the need to store non combustible ash generated at the exhaust. Therefore, improving the ash storage capacity of a filter appears as a major step towards the development of maintenance free DPF systems. This paper describes a new filter design that was developed to optimize ash storage volume. Numerical simulations and roller bench tests have been performed in order to compare the performances of this new filter to commercial honeycomb filters.

This paper presents a new firing concept for internal combustion engines called APIR and its performances. This concept attempts to merge the best of both Compression Ignition (CI) and Spark Ignition (SI) engine worlds. The application of this concept to a standard SI engine, leads to a consequent improvement of the firing and combustion performances. Initiation and combustion develop with a speed and a repeatability incomparable with the spark plug firing case. The use of the APIR device leads to an increase of the engine operating range in terms of lean operating limit and thus lean burn torque range. This paper points out that the APIR device has a lower knock sensitivity and isn't much affected by the in-cylinder aerodynamics. Thus, it can be shown that to take full advantage of the APIR concept in terms of efficiency and pollutants emissions, the SI engine must be redesigned in terms of compression ratio and in-cylinder aerodynamics.

In the last decade, the drastic strengthening of engine emission regulations has conducted the automotive industry towards more and more sophisticated engine control strategies requiring more and more sensor inputs and actuator outputs. The testing and setting up of the ECUs implementing such strategies becomes more and more difficult, requiring numerous engine tests on test benches. ECUTEST is a hardware and software package from KADRA CONSULTANTS that offers the following features: Simulation of sensors including variable reluctance sensor, lambda sensor, knock sensor… Measurement of output signals (injection, ignition, EGR…) timing and amplitude. A predefined test pattern can be replayed on the ECU to perform end of line testing. A real-time model can be used for testing and setting up embedded closed loop strategies. The present paper will cover the implementation of a real-time SI engine model on ECUTEST.

Torque based engine control seems to be the trend for the future for powertrain management (automatic gearbox, hybrid vehicles). Today, torque estimation is best achieved using cylinder pressure transducers. This paper proposes a method to achieve a good accuracy of the torque using Bézier curves to reconstruct the cylinder pressure peak from the low frequency embedded pressure measurements. As is, IMEP cannot be used on a cycle to cycle basis for engine torque control, due to the very high cycle to cycle variability of SI engines. To improve the quality of the IMEP feedback data, this paper proposes a moving horizon filtering method.

To meet future pollutant emissions standards, it is crucial to be able to estimate the cycle by cycle composition of the combustion chamber charge. This charge consists of fresh air, fuel and residual gas from the previous cycle. Unfortunately, the residual gas fraction cannot be directly measured. Therefore, a model of residual gas fraction as a function of engine parameters and operating parameters has been developed. The model has been calibrated with exhaust pipe hydrocarbon measurements using a successive dilution method.

Recrystallized Silicon carbide (R-SiC) honeycombs have been widely used over the last couple of years as filtration media for diesel particulates filtration in passenger cars applications. Although such filters are very reliable thanks to SiC good properties and smart designs, existing devices can still be improved. This paper describes several new features developed for R-SiC honeycomb filters in order to increase their durability and reduce their cost. Durability improvements can be obtained through the optimization of different filter properties such as thermo-mechanical resistance and thermal diffusivity. Specific tests have been performed in order to optimize new R-SiC filters.

This SI engine research investigation extends a previous study [14] concerning one kind of non-conventional firing device: the Pulsed Jet Combustion (PJC) igniter. The PJC device was compared to a conventional spark plug during operation in a 4-valve single cylinder engine at 2000 rpm and a variety of air/fuel ratios and loads. Additionally, skip-firing was used to vary the residual gas rate. The mass fraction burned intervals were calculated from the pressure trace for each cycle via a heat release analysis that accounted for cycle-to-cycle variations in the trapped mass of fuel. Statistical analyses were performed for 100 cycles of operation for each test condition. Similar results were found for the PJC device as for the spark plug with zero residual (five skipped cycles). For both igniters, the cycle-to-cycle variability increased with increasing residual, but the variability was less pronounced for the PJC device.

To meet future pollutant emissions standards, it is crucial to be able to estimate the composition of the combustion chamber charge on a cycle by cycle basis. This charge consists of fresh air, fuel and residual gas from the previous cycle. Unfortunately, the residual gas fraction cannot be directly measured. Therefore, a model of residual gas fraction as a function of engine parameters and operating parameters has been developed. The model has been calibrated with exhaust pipe hydrocarbon measurements using a successive dilution method.

The paper presents a new firing concept for internal combustion engines. This concept attempts to merge the best of both Spark Ignition and Compression Ignition engine worlds. The concept is called APIR in French, standing for ‘Auto-inflammation Pilotée par Injection de Radicaux’, meaning Self-ignition Triggered by Radical Injection. The application of this concept to a standard SI engine, leads to a consequent improvement of the firing and combustion performances. A dramatic cycle variability decrease is pointed out. Initiation and combustion develop with a speed and a repeatability incomparable with the spark plug firing case. The use of the APIR device leads to an increase of the engine operating range in terms of Lean Operating Limit and thus Lean Burn Torque Range. An interesting gain on fuel consumption for idle and low load operating points is pointed out.

One way of improving electronic engine control is to get an insight into the combustion process, using a direct measurement method: this means the sensor must be put straight into the combustion chamber. The reference for analyzing combustion development is the cylinder pressure sensor. Due to the price of this sensor and the added complexity for cylinder head design and manufacturing, cylinder pressure sensors are not conceivable today for mass production. An alternative to the cylinder pressure sensor is the ionization sensor. It seems to be very promising for electronic engine control. Several publications have already demonstrated the benefits of ionization currents sensing for misfire detection, knock detection, closed loop ignition control, air-fuel ratio estimation. On the contrary, other publications have shown severe limitations of the ionization sensor. For example, fuel composition or additives can influence the ionization current.