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The Rotating Liner Engine (RLE) is an engine design concept where the cylinder liner rotates in order to reduce piston assembly friction and liner/ring wear. The reduction is achieved by the elimination of the mixed and boundary lubrication regimes that occur near TDC. Prior engines for aircraft developed during WW2 with partly rotating liners (Sleeve Valve Engines or SVE) have exhibited reduction of bore wear by factor of 10 for high BMEP operation, which supports the elimination of mixed lubrication near the TDC area via liner rotation. Our prior research on rotating liner engines experimentally proved that the boundary/mixed components near TDC are indeed eliminated, and a high friction reduction was quantified compared to a baseline engine. The added friction required to rotate the liner is hydrodynamic via a modest sliding speed, and is thus much smaller than the mixed and boundary friction that is eliminated.

EmiSense Technologies, LLC (www.emisense.com) is commercializing its electronic particulate matter (PM) sensor that is based on technology developed at the University of Texas at Austin (UT). To demonstrate the capability of this sensor for real-time PM measurements and on board diagnostics (OBD) for failure detection of diesel particle filters (DPF), independent measurements were performed to characterize the engine PM emissions and to compare with the PM sensor response. Computational fluid dynamics (CFD) modeling was performed to characterize the hydrodynamics of the sensor's housing and to develop an improved PM sensor housing with reproducible hydrodynamics and an internal baffle to minimize orientation effects. PM sensors with the improved housing were evaluated in the truck exhaust of a heavy duty (HD) diesel engine tested on-road and on a chassis dynamometer at the University of California, Riverside (UCR) using their Mobile Emissions Laboratory (MEL).

Pneumatic hybridization of internal combustion engines may prove to be a viable and cost-efficient alternative to electric hybridization. This paper evaluates the effects of pneumatic hybridization of various engine concepts using the criteria of fuel efficiency, driveability, emissions, and cost efficiency. The most promising engine concept is found to be the pneumatic hybridization combined with downsizing and supercharging spark-ignited engines. With this concept, a fuel consumption reduction of over 30% compared to a standard engine with the same rated power can be achieved. The poor driveability usually associated with heavily downsized and supercharged engines is completely overcome by injecting additional air during transients. The most important design issues for this new concept are discussed and several possible solutions are presented. Following these considerations, the first fully functional hybrid pneumatic engine was realized.

The selection and configuration of sensors can strongly influence the closed-loop dynamics of a system. Therefore a methodology for finding the best sensor placement is a valuable tool. This paper deals with this problem by formulating an optimization problem and applies the new method on an SI engine. The best sensor configuration is one that minimizes the overall system costs, yet still meets the system constraints. Before solving the optimization problem, the system is modeled, different sensor configurations are defined, the appropriate controller and the feedback term are developed, and the locations and size of the various errors present in the model are determined. Then, the objective function and the system constraints are defined and the optimization problem is solved considering the worst-case combination of modeling errors, which is computed using genetic algorithms. The objective function is defined as the sum of the sensor costs and of a penalty term.

In practical applications of ammonia SCR aftertreatment systems using urea as the reductant storage compound, one major difficulty is the often constrained packaging envelope. As a consequence, complete mixing of the urea solution into the exhaust gas stream as well as uniform flow and reductant distribution profiles across the catalyst inlet face are difficult to achieve. This paper discusses a modeling approach, where a combination of 3D CFD and a lumped parameter SCR model enables the prediction of system performance, even with non-uniform exhaust flow and ammonia distribution profiles. From the urea injection nozzle to SCR catalyst exit, each step in the modeling process is described and validated individually. Finally the modeling approach was applied to a design study where the performance of a range of urea-exhaust gas mixing sections was evaluated.

Cylinder liner rotation (Rotating Liner Engine, RLE) is a new concept for reducing piston assembly friction in the internal combustion engine. The purpose of the RLE is to reduce or eliminate the occurrence of boundary and mixed lubrication friction in the piston assembly (specifically, the rings and skirt). This paper reports the results of experiments to quantify the potential of the RLE. A 2.3 L GM Quad 4 SI engine was converted to single cylinder operation and modified for cylinder liner rotation. To allow examination of the effects of liner rotational speed, the rotating liner is driven by an electric motor. A torque cell in the motor output shaft is used to measure the torque required to rotate the liner. The hot motoring method was used to compare the friction loss between the baseline engine and the rotating liner engine. Additionally, hot motoring tear-down tests were used to measure the contribution of each engine component to the total friction torque.

It is a very challenging problem to reliably ignite extremely lean mixtures, especially for the low speed, high load conditions of large-bore natural gas engines. If these engines are to be use for the distributed power generation market, it will require operation with higher boost pressures and even leaner mixtures. Both place greater demands on the ignition system. The railplug is a very promising ignition system for lean burn natural gas engines with its high-energy deposition and high velocity plasma arc. It requires care to properly design railplugs for this new application, however. For these engines, in-cylinder pressure and mixture temperature are very high at the time of ignition due to the high boost pressure. Hot spots may exist on the electrodes of the ignitor, causing pre-ignition problems. A heat transfer model is proposed in this paper to aid the railplug design. The electrode temperature was measured in an operating natural gas engine.

Instantaneous in-cylinder pressure, a key variable in the improvement of engine performance and reduction of emissions, is not likely to be measured directly in production type engines in the near future. As a countermeasure, a pressure estimation method based on physical first principles for the estimation of the instantaneous in-cylinder pressure of an SI engine using measured crankshaft angular velocity is presented here. The approach consists of (a) mapping the model parameters at nominal operating conditions and (b) adapting the model parameters to current operating conditions using the instantaneous crankshaft angular velocity. The model reflects all essential effects on in-cylinder pressure, while the simulation time was reduced to 6 milliseconds per cycle on a standard PC. This makes it possible to estimate a cylinder-averaged pressure for each cycle up to an engine speed of more than 6000 rpm. The estimated in-cylinder pressure is available with a delay of one engine cycle.

In this paper a novel IC engine load-control device is described which actively throttles the intake air and thereby produces electric power. The main component is a small axial turbine that replaces the conventional throttle. This turbine is connected with an electric generator and an appropriate electric load control system. This paper describes the complete system including the turbine, the control system, and the necessary auxiliary parts. A prototype of the proposed system has been realized. The paper shows the results in electric power generation obtained with this prototype in steady-state driving conditions and in standard test cycles. Moreover, extrapolations of the expected benefits in other engine-vehicle combinations are computed using mathematical models of the main parts of the system.

A railplug is a new type of ignitor for SI engines. A model for optimizing energy deposition in a railplug ignition system is developed. The model is experimentally validated using a low voltage railplug ignition circuit. The effect of various ignition circuit parameters on the energy deposition and its rate are discussed. Durability of railplugs is an important factor in railplug circuit design. As for all spark ignitors, durability of a railplug decreases as energy deposition is increased. Therefore recommendations are made to minimize wear and increase durability, while depositing sufficient energy to attain ignition, using a railplug.

Compressed Natural Gas (CNG) engines have become a promising alternative to classical IC engines because of low pollutant and carbon dioxide emissions. This paper will first briefly summarize these advantages and then concentrate on the modeling and the control of CNG engines. In the modeling part, it will be shown which effects are similar to those observed in gasoline SI engines and what new sub-models are necessary. In the control part, the problem of sudden A/F ratio changes (for instance during the regeneration of NOx trap catalysts) will be considered. In order to avoid excessive NOx engine-out emission in these transients it is important to switch from lean to rich conditions within very few combustion cycles while keeping the engine torque constant (for comfort reasons). The paper presents a model of the most important phenomena associated with those transients and a feedforward control that meets the mentioned requirements.

The use of a fuzzy logic controller for an active suspension system on a wheeled vehicle is investigated. Addressing the opposing goals of ride quality and bump stop avoidance are integrated into one control algorithm. Construction of the fuzzy rules base will be discussed comprehensively along with the membership function setup for both the input and output variables. Numerous quarter-car simulation comparisons will be performed of the fuzzy controller versus the standard skyhook damper controller. The comparisons will include a variety of terrain inputs. Laboratory testing of the fuzzy controller on a single wheel station system is also included.

Coming along with the present movement towards the ultimately variable engine, the need for clear and simple models for complex engine systems is rapidly increasing. In this context Common-Rail-Systems cause a special kind of problem due to of the high amount of parameters which cannot be taken into consideration with simple map-based models. For this reason models with a higher amount of complexity are necessary to realize a representative behavior of the simulation. The high computational time of the simulation, which is caused by the increased complexity, makes it nearly impossible to implement this type of model in software in closed loop applications or simulations for control purposes. In this paper a method for decreasing the complexity and accelerating the computing time of automotive engine models is being evaluated which uses an optimized method for each stage of the diesel engine process.

A 1998 Toyota Corona passenger car with a direct injection spark ignition (DISI) engine was tested at constant engine speed (2000 rpm) over a range of loads. Engine-out and tailpipe emissions of gas phase species were measured each second. This allowed examination of the engine-out emissions for late and early injection. Seven fuels were used for these tests: five blended fuels and two pure hydrocarbon fuels. These seven fuels can be divided into groups for examination of the effects of volatility, MTBE, and structure (an aromatic versus an i-alkane). Correlations between the fuel properties and their effects on emissions are presented. Use of steady state tests rather than driving cycles to examine fuel effects on emissions eliminates the complications resulting from accelerations, decelerations, and changes of injection timing but care had to be taken to account for the periodic regenerations of the lean NOx trap/catalyst.

This paper compares the fuel consumption of a lightweight passenger car for three different SI engine concepts, all with rated power of about 40 kW: a classical SI engine with moderate maximum speed, a low-displacement but high-speed engine that exploits the maximum allowed mean-piston speed and a low-displacement but highly supercharged engine with moderate maximum speed. All engines are simulated with a thermodynamic process simulator, the results of the supercharged version are validated with experiments. For each engine, a CVT and an automated gearbox is considered. Fuel consumption is estimated with a quasi-static driving cycle simulator which is based on engine fuel consumption maps and physical models of the vehicle with all its relevant subsystems. The simulations are performed for constant vehicle speed as well as for US and European driving cycles.

This paper presents a control-oriented mean-value model of a pressure wave supercharger (PWS) which is coupled to an SI-engine. The model is able to predict the engine's intake pressure and other main process variables. The model is validated by stationary and transient measurements on an engine dynamometer.

The mixture preparation process was investigated in a direct-injected, 4-valve, SI engine under motored conditions. The engine had a transparent cylinder liner that allowed the fuel spray to be imaged using laser sheet Mie scattering. A fiber optic probe was used to measure the vapor phase fuel concentration history at the spark plug location between the two intake valves. The fuel injector was located on the cylinder axis. Two flow fields were examined; the stock configuration (tumble index 1.4) and a high tumble (tumble index 3.4) case created using shrouded intake valves. The fuel spray was visualized with the engine motored at 750 and 1500 RPM. Start of injection timings of 90°, 180° and 270° after TDC of intake were examined. The imaging showed that the fuel jet is greatly distorted for the high tumble condition, particularly at higher engine speeds. The tumble was large enough to cause significant cylinder wall wetting under the exhaust valves for some conditions.

The effect of combustion chamber wall-wetting on the emissions of unburned and partially-burned hydrocarbons (HCs) from gasoline-fueled SI engines was investigated experimentally. A spark-plug mounted directional injection probe was developed to study the fate of liquid fuel which impinges on different surfaces of the combustion chamber, and to quantify its contribution to the HC emissions from direct-injected (DI) and port-fuel injected (PFI) engines. With this probe, a controlled amount of liquid fuel was deposited on a given location within the combustion chamber at a desired crank angle while the engine was operated on pre-mixed LPG. Thus, with this technique, the HC emissions due to in-cylinder wall wetting were studied independently of all other HC sources. Results from these tests show that the location where liquid fuel impinges on the combustion chamber has a very important effect on the resulting HC emissions.

A liquid-phase port injection system for liquefied petroleum gas (LPG) generally consists of a fuel storage tank with extended capability of operating up to 600 psi, a fuel pump, and suitable fuel lines to and from the LPG fuel injectors mounted in the fuel rail manifold. Port injection of LPG in the liquid phase is attractive due to engine emissions and performance benefits. However, maintaining the LPG in the liquid phase at under-hood conditions and re-starting after hot soak can be difficult. Multiphase behavior within a liquid-phase LPG injection system was investigated computationally and experimentally. A commercial chemical equilibrium code (ASPEN PLUS™) was used to model various LPG compositions under operating conditions.

The design of an air to fuel ratio (AFR) control system is substantially facilitated by a suitable mathematical model of the mixture formation process. Such a model has to be a compromise between short simulation times and good prediction capabilities. Well-known simple “linear” wall-wetting models are easy to use but require substantial calibration time to experimentally determine the operating point dependent model parameters. Full 3D simulations of all physical effects are still computationally not tractable. In this work a control oriented mathematical model of the mixture formation phenomena has been built, which tries to find a middle way between these two extremes. Computation times for one engine cycle are less than half a minute on a standard Pentium-PC. Nevertheless, the model is able to predict nonlinear effects that cannot be described by conventional wall-wetting models.