Search Results

The development of powertrains with DI diesel Engines as primary drive demands accurate analytic specification of the cylinder process, with sufficient consideration taken of gas-exchange, turbo charging, and - especially - combustion. Until now, engine-process simulation has proved to be a powerful tool for satisfaction of these requirements. In addition to simple modeling of the heat-release rate with Vibe functions, complex heat-release models based on injection-rate profiles have been developed and implemented in existing simulation tools such as GT Power. To calibrate the parameters to achieve satisfactory agreement between experimental data and three-dimensional Computational Reactive Fluid Dynamics Models (CRFD) simulations, an appreciable amount of expertise and time is required. This paper deals with a universal method that automatically identifies and calibrates the relevant model parameters to the experimental data.

The evolution of automotive engines calls for the design of electronic control systems optimizing the engine performance in terms of reduced fuel consumption and pollutant emissions. However, the opportunities provided by modern engines have not yet completely exploited, since the adopted control strategies are still largely developed in a very heuristic way and rely on a number of SISO (Single Input Single Output) designs. On the contrary, the strong coupling between the available actuators calls for a MIMO (Multi Input Multi Output) control design approach. To this regard, the availability of reliable dynamic engine models plays an important role in the design of engine control and diagnostic systems, allowing for a significant reduction of the development times and costs. This paper presents a control-oriented model of the air-path system of today's gasoline internal combustion engines.

In a gasoline engine, the unswept in-cylinder residual gas and introduction of external EGR is one of the important means of controlling engine raw NOx emissions and improving part load fuel economy via reduction of pumping losses. Since the trapped in-cylinder Residual Gas Fraction (RGF, comprised of both internal, and external) significantly affects the combustion process, on-line diagnosis and monitoring of in-cylinder RGF is very important to the understanding of the in-cylinder dilution condition. This is critical during the combustion system development testing and calibration processes. However, on-line measurement of in-cylinder RGF is difficult and requires an expensive exhaust gas analyzer, making it impractical for every application. Other existing methods, based on measured intake and exhaust pressures (steady state or dynamic traces) to calculate gas mass flowrate across the cylinder ports, provide a fast and economical solution to this problem.

The paper describes the tool of ICE transient response simulation suitable for incorporation into a predictive engine controller. The model is simplified, thus enhancing the simulation speed but keeping its predictive capability at a reasonable level. The main modules of a code suitable for the near-real-time simulation of engine thermodynamics are described in the paper. They include engine cylinder (incl. simplified pressure trace prediction), fuel injection system, main controllers, both inlet and exhaust manifolds, turbocharger and engine dynamics. The laws of conservation are used to describe any of the thermodynamic/hydrodynamic modules of a model. The method of algebraic re-construction of a pressure trace inside a cylinder has been developed and tested for prediction of engine speed variation. The modular structure of a model allows for the implementation of the current operating principles of ICEs.

In the current work, a heat release model, based on the First Law of the Thermodynamics, has been implemented using a genetic approach. Using this approach, the evaluation procedure of the calibration's constants becomes automatic and accurate. The more accurate is the evaluation of the calibration's constants, the more precise will be the calculation of the heat exchange between charge and cylinder walls, the evaluation of the gross heat release inside internal combustion engines, the evaluation of the rate of heat release, the mass fraction burned, as well as the combustion efficiency.

An investigation was conducted to evaluate the elimination of the bronze bushing in the connecting rod of an automotive piston assembly by utilizing a cost effective break in lubricant applied to the piston pin. The typical automotive piston assembly consists of a piston having pin bosses formed with pin bores for the piston pin. The hardened steel piston pin connects the piston through the pin bores to the connecting rod, which also has a pin bore (See Figure 1). Typically, internal to the pin bore in the connecting rod is a press fit bronze bushing. The purpose of the bronze bushing is to reduce friction, material transfer and scuffing by providing a compatible bearing type mating surface with the pin under low lubrication conditions.

Frictional losses in the piston ring-pack of an engine account for approximately half of the total frictional losses within the power cylinder of an engine. Three-dimensional honing groove texture was modeled, and its effect on piston ring-pack friction and engine brake thermal efficiency was investigated. Adverse effects on engine oil consumption and durability were also considered. Although many non-conventional cylinder liner finishes are now being developed to reduce friction and oil consumption, the effects of surface finish on ring-pack performance is not well understood. A rough surface flow simulation program was developed to calculate flow and stress factors that adjust the solution of the Reynolds equation for the effects of surface roughness as has been done in the literature. Rough surface contact between the ring and liner was modeled using a previously published methodology for asperity contact pressure estimation between rough surfaces.

The urea-SCR system is one of the most promising aftertreatment systems for future automotive diesel engines. We developed a urea dosing device with twin urea injectors for onboard applications, to enhance the NOx reduction performance at low exhaust temperatures and to lower the electric power consumption of the SCR system. The injectors operate with a single-phase urea solution, without air assist. Of the injectors, one is used to supply urea to a bypass passage routing the exhaust, during low exhaust temperatures. The other injector is located on the wall of the main exhaust duct, directly supplying urea to the exhaust. This direct injection method has a uniform spray distribution problem. A set of impact plates were used to distribute the spray. Impact plates have a high potential for deposition, but use of film boiling was considered. A thermal analysis was conducted and as a result, deposit conditions were theoretically derived. This was confirmed through experiments.

The urea co-fueling approach to refilling a urea storage container onboard a vehicle is based on the design of a two-fluid dispensing nozzle. With a single refueling operation the nozzle enables an independent delivery of two fluids, diesel fuel and urea, into two separate containers. The person refueling the vehicle needs no new skills or knowledge. But most importantly, the co-fueling method eliminates a separate and a critical action of keeping up with timely refills of the urea as the condition for emissions compliance for the vehicle. However, freezing of aqueous solution of urea below -11.5°C puts additional demands on the design of the two-fluid nozzle and the vehicle fill pipe receptacle, so that a reliable co-fueling process is assured at these cold weather conditions. The paper describes the methods that prevent formation of ice in the co-fueling fill pipe, which would enable refilling of urea during continuous use of the vehicle at temperatures below urea freezing point.

The paper presents a novel method for the measurement of lubricant film thickness in the piston-liner contact. Direct measurement of the film in this conjunction has always posed a problem, particularly under fired conditions. The principle is based on capturing and analysing the reflection of an ultrasonic pulse at the oil film. The proportion of the wave amplitude reflected can be related to the thickness of the oil film. A single cylinder 4-stroke engine on a dyno test platform was used for evaluation of the method. A piezo-electric transducer was bonded to the outside of the cylinder liner and used to emit high frequency short duration ultrasonic pulses. These pulses were used to determine the oil film thickness as the piston skirt passed over the sensor location. Oil films in the range 2 to 21 μm were recorded varying with engine speeds. The results have been shown to be in agreement with detailed numerical predictions.

For the purpose of this paper the author will use VVT (Variable Valve Timing) to describe the function of these components. Other common names are VCT (Variable Camshaft Timing), cam phasers, VVT's were introduced in Japan in the late 1990,s in series production. The benefit to the end user is improved fuel economy, an increase in the power output and a reduction in emissions. Globally there are 8 major suppliers of VVT assemblies. The purpose of this paper is to compare the various systems from the selection of PM materials and the subsequent post operation processes specifically related to sprockets.

The blow-by phenomenon is seldom acquainted with diesel engines, but for a small bore HSDI optical diesel engine, the effects are significant. A difference in peak pressure up to 25% can be observed near top-dead-center. To account for the pressure differences, a 0-D crevice flow model with a dynamic ring pack model was incorporated into the KIVA code to determine the amount of blow-by. The ring pack model will take into account the forces acting on the piston rings, the position of the piston rings, and the pressure located at each region of the crevice volume at every time step. The crevice flow model takes into consideration the flow through the circumferential gap, ring gap, and the ring side clearance. As a result, the cylinder mass, trapped mass in the crevice regions, and the blow-by values are known. Validation of the crevice model is accomplished by comparing the in-cylinder motoring pressure trace with the experimental motoring data.

Variable valve timing (VVT) unit, which is able to decrease environmental load and improve fuel economy is loaded onto many automobiles recently. This unit consists mainly of sprocket, housing and rotor. These parts are requested different properties according to environment. We produce sintered parts for variable valve timing unit by selecting compact, sinter process and special treatment according to demanded properties. In this paper, demanded properties of sintered parts for variable valve timing unit and adopted technique to satisfy them are presented.

The powder forging (PF) process is used to produce fully dense powder metallurgy (PM) parts for high performance automotive applications. PF connecting rods have been widely accepted in the US, Japan, and other countries due to higher performance and lower manufacturing costs when compared to conventionally forged steel connecting rods [1, 2]. In order to meet and exceed requirements for higher fatigue strength and better machinability of PF connecting rods, a newly developed machinability enhancer, consisting of complex calcium oxide, named KSX, was introduced [3]. Minimal additions of KSX were found to be very effective in protecting the surface of the cutting tool during machining, with virtually no effect on mechanical properties obtained after the forging process. A comparison study between materials prepared with 0.3% MnS and with 0.1% KSX additions showed higher fatigue strength and better machinability in the case of the mix with KSX.

Durability requirements for exhaust materials have resulted in the increased use of stainless steels throughout the exhaust system. The conversion of carbon steel exhaust flanges to stainless steel has occurred on many vehicles. Ferritic stainless steels are commonly used for exhaust flanges. Flange construction methods include stamped sheet steel, thick plate flanges and powder metal designs. Flange material selection criteria may include strength, oxidation resistance, weldability and cold temperature impact resistance. Flange geometry considerations include desired stiffness criteria, flange rotation, gasket/sealing technique and vehicle packaging. Both the material selection and flange geometry are considered in terms of meeting the desired durability and cost. The cyclic oxidation performance of the material is a key consideration when selecting flange materials.

The article describes a model-based control method for idle speed of spark-ignition (SI) engines. It is based on mid-ranging, a multivariable control strategy that is more commonly used in process control. The basic building blocks of the control structure are two PI controllers.

Knock correction is the spark angle retard applied to the optimum ignition timing to eliminate knock. In adaptive knock control, this amount of spark retard at an operating point (i.e. Speed, load) is stored in a speed/load characteristic map. It will be reused when the engine is operated in this range once more. In this paper, a method to learn the knock correction values into a speed/load characteristic map is described. This method proportionally distributes the knock correction into the characteristic map according to the distance between the speed/load of these nodes and the current operating point. The distributed knock correction value is filtered and accumulated in its adjacent nodes. Simulation examples demonstrate that the retrieved values from the map by the proposed method are smoother than those produced by the method of [2][3]. The mathematical basis for this method is developed. The one and two independent variable cases are illustrated.

This paper focuses on the requirements of electronic systems in automotive applications in terms of reliability and quality. As one of the most common devices in such applications for switching electronic loads, the power MOSFET, is investigated in detail. Today's qualification procedure for discrete devices according to AEC Q101 [1] will be explained and how this correlates to the stress of the device in the application. It will be pointed out what additional tests for “extended qualification” should be made to deal with critical failure modes reducing overly conservative safety margins and preventing excessive costs on the component side. The tests will be explained and the results presented.

The number of safety critical automotive applications employing high current brushless motors continues to increase (Steering, Braking, and Transmission etc.). There are many benefits when moving from traditional solutions to electrically actuated solutions. Some of these benefits can include increased fuel economy, simplified vehicle installation and packaging, increased feature set, improved safety and/or convenience, simplified unit assembly and modular testability prior as well as during vehicle manufacturing. The trend to implement brushless motors in these applications (which require electronically controlled commutation) has also brought with it the need for powerful inverters, which primarily consist of Power MOSFETs and MOSFET Driver ICs. This paper reviews the challenges associated with the design of safety critical electronic systems which combine sensing, control and actuation.

Organizations that implement strategic energy management programs undertake a set of activities that, if carried out properly, have the potential to deliver sustained energy savings. One key management opportunity is determining an appropriate level of energy performance for a plant through comparison with similar plants in its industry. Performance-based indicators are one way to enable companies to set energy efficiency targets for manufacturing facilities. The U.S. Environmental Protection Agency (EPA), through its ENERGY STAR® program, is developing plant energy performance indicators (EPI) to encourage a variety of U.S. industries to use energy more efficiently. This paper reports on work with the automobile manufacturing industry to provide a plant-level indicator of energy efficiency.