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A comprehensive cycle analysis has been developed for four-stroke spark-ignited engines from which the indicated performance of a single cylinder engine was computed with a reasonable degree of accuracy. The step-wise cycle calculations were made using a digital computer. This analysis took into account mixture composition, dissociation, combustion chamber shape (including spark plug location), flame propagation, heat transfer, piston motion, engine speed, spark advance, manifold pressure and temperature, and exhaust pressure. A correlation between the calculated and experimental performance is reported for one engine at a particular operating point. The calculated pressure-time diagram was in good agreement with the experimental one in many respects. The calculated peak pressure was 10 per cent lower and the thermal efficiency 0.8 per cent higher than the measured values. Thus this calculational procedure represents a significant improvement over constant volume cycle approximations.

The fierce competition and shifting consumer demands require automotive companies to be more efficient in all aspects of vehicle development and specifically in the area of embedded engine control system development. In order to reduce development cost, shorten time-to-market, and meet more stringent emission regulations without sacrificing quality, the increasingly complex control algorithms must be transportable and reusable. Within an efficient development process it is necessary that the algorithms can be seamlessly moved throughout different development stages and that they can be easily reused for different applications. In this paper, we propose a flexible engine control architecture that greatly boosts development efficiency.

This paper presents a comprehensive Matlab/Simulink-based framework that affords a rapid, systematic, and efficient engine control system development process including automated code generation. The proposed framework hinges on three essential pillars: 1 ) an accurate model for the target engine, 2) a toolset for systematic control design, and 3) a modular system architecture that enhances feature reusability and rapid algorithm deployment. The proposed framework promotes systematic model-based algorithm development and validation in virtual reality. Within this context, the framework affords integration and evaluation of the entire control system at an early development stage, seamless transitions across inherently incompatible product development stages, and rapid code generation for production target hardware.

This work provides an effective engineering method of building a part-load engine simulation model from a wide-open throttle (WOT) engine model and available dynamometer data. It shows how to perform part-load engine simulation using optimizer for targeted manifold absolute air pressure (MAP) on a basic matrix of engine speed and MAP. Key combustion parameters were estimated to cover the entire part-load region based on affordable assumptions and limitations. Engine rubbing friction and pumping friction were combined to compare against the motoring torque. The emission data from GM dynamometer laboratory were used to compare against engine simulation results after attaching the RLT sensor to record emission data in the engine simulation model.

When pickup trucks are driven on concrete paved freeways, freeway hop shake is a major complaint. Freeway hop shake occurs when the vehicle passes over the concrete joints of the freeway which impose in-phase harmonic road inputs. These road inputs excite vehicle modes that degrade ride comfort. The worst shake level occurs when the vehicle speed is such that the road input excites the vehicle 1st bending mode and/or the rear wheel hop mode. The hop and bending mode are very close in frequency. This phenomenon is called freeway hop shake. Automotive manufacturers are searching for ways to mitigate freeway hop shake. There are several ways to reduce the shake amplitude. This paper documents a new approach using hydraulic body mounts to reduce the shake. A full vehicle analytical model was used to determine the root cause of the freeway hop shake.

Model-based design is a collection of practices in which a system model is at the center of the development process, from requirements definition and system design to implementation and testing. This approach provides a number of benefits such as reducing development time and cost, improving product quality, and generating a more reliable final product through the use of computer models for system verification and testing. Model-based design is particularly useful in automotive control applications where ease of calibration and reliability are critical parameters. A novel application of the model-based design approach is demonstrated by The Ohio State University (OSU) student team as part of the Challenge X advanced vehicle development competition. In 2008, the team participated in the final year of the competition with a highly refined hybrid-electric vehicle (HEV) that uses a through-the-road parallel architecture.

During a new engine development program, or the adaptation of an existing engine to new platform architectures, testing is performed to determine the durability characteristics of the basic engine structure. Such testing helps to uncover High Cycle durability-related issues that can occur at the bulkhead walls as well as cap bolt thread areas in an aluminum cylinder block. When this class of issues occurs, an Elastohydrodynamic (EHD) bearing simulation capability is required. In this study, analytical methods and processes are established to calculate the localized distributed load on the bulkhead. The complexity in performing a system analysis is due to the nonlinear coupling between the bearing hydrodynamic pressure distribution and the crankshaft and block deformation. A system approach for studying the crankshaft-block interaction requires a crankshaft flexible body dynamics model, an engine block assembly flexible body dynamics model and a main bearing lubrication model.

CFD method for the calculation of flow rate and air re-circulation at vehicle idle conditions is described. A small velocity is added to the ambient airflow in order to improve the numerical stability. The flow rate passing through the heat exchangers is insensitive to the ambient velocity, since the flow rate is largely determined by the fan operation. The air re-circulation, however, is quite sensitive to the ambient air velocity. The ambient velocity of U=-1m/s was found to be the more critical case, and is recommended for the air re-circulation analysis. The CFD analysis can also lead to design modifications improving the air re-circulation.

Development and integration of the cooling system for an automotive vehicle requires a balancing act between several performance and styling objectives. The cooling system needs to provide sufficient air for heat rejection with minimal impact on the aerodynamic drag, styling requirements and other criteria. An optimization of various design parameters is needed to develop a design to meet these objectives in a short amount of time. Increase in the accuracy of the numerical predictions and reduction in the turn-around time has made it possible for Computational Fluid Dynamics (CFD) to be used early in the design phase of the vehicle development. This study shows application of the CFD for robust design of the engine cooling system.

The concept of condenser, fan, and radiator power train cooling module (CFRM) was further evaluated via three-dimensional computational fluid dynamics (CFD) studies in the present paper for vehicle at idle conditions. The analysis shows that the CFRM configuration was more prone to the problem of front-end air re-circulation as compared with the conventional condenser, radiator, and fan power train cooling module (CRFM). The enhanced front-end air re-circulation leads to a higher air temperature passing through the condenser. The higher air temperature, left unimproved, could render the vehicle air conditioning (AC) unit ineffective. The analysis also shows that the front-end air re-circulation can be reduced with an added sealing between the CFRM package and the front of the vehicle, making the CFRM package acceptable at the vehicle idle conditions.

Condenser, fan, radiator power train cooling module (CFRM) proposed by Delphi Automobile Systems was evaluated in the context of vehicle thermal system analysis. The results from the CFRM configuration were compared with those from the conventional condenser, radiator, and fan power train cooling module (CRFM). The analysis shows that for a typical passenger vehicle, the underhood temperature for the CFRM configuration is more than 10°C lower than its CRFM counterpart when the fan is operating at the same speed of 2500 rpm. This is due mainly to the higher mass flow rate impelled by the fan in the CFRM configuration. At the equal mass flow condition, both the CFRM and the CRFM configurations give similar underhood temperatures; but the fan in the CFRM configuration uses 19% less power, due mainly to the reduction in the fan speed needed to impel the same amount of mass flow rate.

Experimentally obtained combustion responses of a typical reverse-tumble wall-controlled direct-injection stratified-charge engine to operating variables are described. During stratified-charge operation, the injection timing, ignition timing, air-fuel ratio, and levels of exhaust gas recirculation (EGR) generally determine the fuel economy and emissions performance of the engine. A detailed heat-release analysis of the experimental cylinder-pressure data was conducted. It was observed that injection and ignition timings determine the thermal efficiency of the engine by controlling primarily the combustion efficiency of the stratified charge. Hence, combustion phasing is determined by a compromise between work-conversion efficiency and combustion efficiency. To reduce nitric-oxide (NOx) emissions, a reduction in overall air-fuel ratio as well as EGR addition is required.

This work describes an experimental investigation on the stratified combustion and engine-out emissions characteristics of a single-cylinder, spark-ignition, direct-injection, spray-guided engine employing an outward-opening injector, an optimized high-squish, bowled piston, and a variable swirl valve control. Experiments were performed using two different outward-opening injectors with 80° and 90° spray angles, each having a variable injector pintle-lift control allowing different rates of injection. The fuel consumption of the engine was found to improve with decreasing air-swirl motion, increasing spark-plug length, increasing spark energy, and decreasing effective rate of injection, but to be relatively insensitive to fuel-rail pressure in the range of 10-20 MPa. At optimal injection and ignition timings, no misfires were observed in 30,000 consecutive cycles.

General Motors recently demonstrated two driveable test vehicles powered by a Homogeneous Charge Compression Ignition (HCCI) engine. HCCI combustion has the potential of a significant fuel economy benefit with reduced after-treatment cost. However, the biggest challenge of realizing HCCI in vehicle applications is controlling the combustion process. Without a direct trigger mechanism for HCCI's flameless combustion, the in-cylinder mixture composition and temperature must be tightly controlled in order to achieve robust HCCI combustion. The control architecture and strategy that was implemented in the demo vehicles is presented in this paper. Both demo vehicles, one with automatic transmission and the other one with manual transmission, are powered by a 2.2-liter HCCI engine that features a central direct-injection system, variable valve lift on both intake and exhaust valves, dual electric camshaft phasers and individual cylinder pressure transducers.

Critical speed induced by imbalance forces is a well-known dynamic behavior of rotating shafts. Such problems are typically found in flexible shafts or rigid shafts with flexible supports when the frequency of rotation reaches the natural frequencies of the shaft. This simple critical speed problem is well understood and formulated in many engineering texts. However, not all critical speed phenomena are induced by imbalance. A perfectly balanced shaft with certain inertial properties also reaches a critical speed condition at a rotational speed that is not equal to the natural frequency of the shaft. Several variables of the dynamic system play a role on the critical speed condition, which is mainly induced by the unstable gyroscopic moment acting on the shaft. The unstable gyroscopic moment forces the shaft bearings to deflect causing precession about the undeflected geometric centerline of the shaft, but the rotation and precession speeds remain synchronized at low speeds.

Cylinder pressure data is so completely integral to the combustion system development process that ensuring measurements of the highest possible accuracy is of paramount importance. Three main areas of the pressure measurement and analysis process control the accuracy of measured cylinder pressure and its derived metrics: 1) Association of the pressure data to the engine's crankshaft position or cylinder volume 2) Pegging, or referencing, the pressure sensor output to a known, absolute pressure level 3) The raw, relative pressure output of the piezoelectric cylinder pressure sensor Certain cylinder pressure-based metrics, such as mean effective pressures (MEP) and heat release parameters, require knowledge of the cylinder volume associated with the sampled pressure data. Accurate determination of the cylinder volume is dependent on knowing the rotational position of the crankshaft.

The new regulations to reduce emissions have resulted in the development of new techniques to maintain or enhance competitive performance. A requirement for the manifold is to help meet the reduction in cold start emissions, particularly during the transient conditions from start to 100 seconds following the Federal Test Procedures for vehicle emissions. Finite element computer models were developed to predict inner and outer wall temperatures, and to determine structural soundness. Tests were performed to assure that noise levels were minimized. Dynamometer lab and field tests were performed to verify that the manifold would meet the design requirements. From the results of these tests and analyses, modifications were made to the weld and manufacturing techniques to improve product life and reduce noise. Dual wall manifolds have proven durability to meet high exhaust gas temperatures up to 1650°F (900°C), while meeting the performance, noise, and weight reduction goals.

Combustion feedback using cylinder pressure sensors, ion current sensors or alternative sensing techniques is actively under investigation by the automotive industry to meet future legislative emissions requirements. One of the drawbacks of many rapid prototyping engine management systems is their available analog interfaces, often limited to 10-12 bits with limited bandwidth, sampling rate and very simple anti-aliasing filters. Processing cylinder pressure or other combustion feedback sensors requires higher precision, wider bandwidths and more processing power than is typically available. For these reasons, Ricardo in collaboration with GM Research has developed a custom, high precision analog input subsystem for the rCube rapid prototyping control system that is specifically targeted at development of combustion feedback control systems.

Fully flexible valve actuation (FFVA) system, often referred to as camless valvetrain, employs electronically controlled actuators to drive the intake and/or exhaust valves. This technology enables the engine controller to tailor the valve event according to the engine operating condition in real-time to improve fuel economy, emissions and performance. At GM Research and Development Center, we have developed laboratory electro-hydraulic FFVA systems for single cylinder gasoline engines. The objective of this work is to develop a FFVA system for advanced diesel combustion research. There are three major differences between gasoline and diesel engines in terms of applying the FFVA systems. First, the orientation of the diesel engine valves and the location of the fuel injection system complicate the packaging issue. Second, the clearance between the valves and the piston for diesel engines are extremely small.

Full-load operation of a small-displacement spark-ignition direct-injection (SIDI) engine was thoroughly investigated by means of computational analysis and engine measurements. The performance is affected by many different factors, which can be grouped as those pertaining to volumetric efficiency, to mixing and stratification, and to system issues, respectively. Volumetric efficiency is affected by flow losses, tuning and charge cooling. Charge cooling due to spray vaporization is often touted as the most significant benefit of direct-injection on full-load performance. However, if wall wetting occurs, this benefit may be completely negated or even reversed. The fuel-air mixing is strongly affected by the injection timing and characteristics at lower engine speeds, while at higher engine speeds the intake flow dominates the transport of fuel particles and resultant vapor distribution. A higher injector flow rate enhances mixing especially at higher engine speeds.