Automotive Gasoline Engine Research Articles

Development and Validation of a Variable Displacement Variable Compression Ratio Miller Cycle Technology on an Automotive Gasoline Engine

At partial load, traditional automotive gasoline engines have high pumping losses due to the throttling of the intake charge for load control. Variable Valve Timing (VVT) and the introduction of externally cooled EGR could reduce the pumping losses but only with a very limited effect. On the other hand, in the medium to full load range, the engine cannot utilize a high compression ratio due to limitations in knocking. A variable displacement, variable compression ratio device which utilizes an asymmetric camshaft to realize the different closure times of the two intake valves is discussed in this paper. The large-scale change in the intake valve timing leads to the large-scale change in the effective cylinder volume at the intake valve closure, which realizes a variable cylinder volume and a variable effective compression ratio. The device is utilized to reduce the pumping losses and to increase the in-cylinder thermal efficiency at the same time. Engine dyno test results indicate that, in the low to medium load range, a later closure of the intake valve could reduce the effective cylinder volume, and the intake pressure could be significantly increased, and therefore pumping losses reduced. However, the reduced effective cylinder volume due to a later intake valve closure would lead to reduction in the effective compression ratio (ECR) and a drop in in-cylinder thermal efficiency. Therefore, there is a balance point between the pumping loss reduction and the drop in in-cylinder thermal efficiency. On the other side, in the medium to full load range, when avoiding knocking becomes the major controlling factor of the combustion phasing (degree of constant-volume combustion) and the effective expansion ratio (EER), too high of an effective compression ratio would lead to significant drop in the effective expansion ratio EER and also the in-cylinder thermal efficiency. Therefore, there exists a best compromise between the ECR and EER, and the best system would be one with a moderate ECR but an EER as high as possible. The quantitative equations which include both ECR and EER in the thermal efficiency calculations captured the above observations pretty well and can be utilized to optimize for the best compromise of IVC, EVO, ECR, EER and engine performances during the concept stage and/or the calibration stage of an engine.

The study of the spark ignition engine performance at fueling with n-butanol-gasoline mixture

The actual challenges regarding renewable energy sources, pollution and climate changes have pushed industries sectors (including the automotive sector) to find sustainable solutions for long-term. Numerous studies have been conducted for to find the alternative fuels sources to solve the energetic and pollution problems. A special attention was given to alcohols use (ethanol, butanol, methanol) in mixture with the conventional fuels like gasoline or diesel. Butanol has a great advantage comparative with other alcohols due its better miscibility properties, allowing a butanol higher percentages use in mixture with gasoline or diesel fuel. Butanol is also less corrosive VS ethanol or methanol, which makes it ideal for the spark-ignition engines. An automotive gasoline engine with a 1.5L displacement was fueled with butanol in mixture with gasoline in deferent percentages, deferent dosages and deferent engine operation regimes. In the paper the effects are presented of the engine fueling with B15 fuel (15%-vol. n-butanol in mixture with 85%-vol. gasoline) on the combustion, on the engine energetic performances and pollutants. The experimental investigations (engine load 55% and 2500 rpm engine speed) showed the brake specific energetic consumption and the level of the pollutants emissions decrease at the butanol and the lean mixtures use, at the same engine power, comparative to engine gasoline. Another advantage of n-butanol is the stable engine operation at lean mixtures use.

Simulating the Misting of Lubricant in the Piston Assembly of an Automotive Gasoline Engine: The Effect of Viscosity Modifiers and Other Key Lubricant Components

The presence of lubricant droplets in the gas that flows through the piston assembly and crankcase of an internal combustion engine (generically termed oil misting) has important implications for performance, particularly lubricant supply to the upper piston assembly, oil consumption and lubricant degradation. A significant source of these droplets is thought to be oil shearing and blow-through by blow-by gas flows in the piston assembly. An experimental rig was developed to simulate the high velocity gas and lubricant film interactions at a top piston ring gap where the flow conditions are most severe. Flows of lubricant droplets were produced and characterised in terms of the proportion of the oil flow that formed droplets in the gas flow and the size distribution of the droplets produced. Considering various aspects of a commercial automotive crankcase formulation, the effect of lubricant viscosity was found to be particularly important. Of the lubricant additives evaluated, viscosity modifiers were found to have the greatest effect on the tendency to form droplets: Detailed study on a range of viscosity modifiers identified that the influence of their molecular architectures on viscoelasticity was the key mechanism.

Exhaust Gas Temperature Pulsations of a Gasoline Engine and Its Stabilization Using Thermal Energy Storage System to Reduce Emissions

Modern automotive gasoline engines have highly efficient after-treatment systems that reduce exhaust gas emissions. However, this efficiency greatly depends on the conditions of the exhaust gas, mainly the temperature and air–fuel ratio. The temperature instability during transient conditions may cause a reduction in the efficiency of the three-way catalyst (TWC). By using a thermal energy storage system before TWC, this negative effect can be suppressed. In this paper, the effects of the temperature stabilization on the efficiency of the three-way catalyst were investigated on a 1-D turbocharged gasoline engine model, with a focus on fuel consumption and emissions. The thermal energy storage system (TESS) was based on PCM materials and was built in the exhaust between the turbine and TWC to use the energy of the exhaust gas. Three different materials were picked up as possible mediums in the storage system. Based on the results, the usage of a TESS in a gasoline after-treatment system has shown great potential in improving TWC efficiency. This approach can assist the catalyst to operate under optimal conditions during the drive. In this study, it was found that facilitating the heat transfer between the PCM and the catalyst can significantly improve the emissions’ reduction performance by avoiding the catalyst to light out after the cold start. The TESS with PCM H430 proved to reduce the cumulative CO and HC emissions by 8.2% and 10.6%, respectively, during the drive. Although a TES system increases the after-treatment cost, it can result in emission reductions and fuel consumption over the vehicle’s operating life.

Theoretical and experimental research of an automotive gasoline engine fuelled with butanol

Among alcohols used for spark ignition engine fuelling, butanol can be a viable alternative fuel due to its very good combustion proprieties. Butanol has a high miscibility with the gasoline and stable blends can be assured. The higher oxygen content and the higher combustion speed of butanol comparative with gasoline are proprieties which may improve the combustion process and may lead to the reduction of greenhouse gases level such as CO2 and pollutants like CO, HC, and NOx. A theoretical and experimental study was conducted on a spark-ignition engine with 1.5L displacement fuelled with n-butanol-gasoline blends at different volume percentages and different excess air coefficients at the 55% engine load of and 2500 min-1 engine speed. Starting from a predefined model in AMESim was developed and calibrated a physical-mathematical model for the process’s simulation from the engine cylinder. The objective of the paper is to get a good representation of the real engine in numeric to have a better prediction of the engine performance at the different operating conditions. The theoretical and experimental investigations show important advantages of n-butanol in blend with gasoline: the increase of the thermal efficiency due to the stable engine operation at lean mixtures use.

Influence of engine load on piston ring pack operation of an automotive IC engine

A piston-rings-cylinder (PRC) assembly determines the blowby, engine oil consumption, and friction and wear processes accompanying the system's operation. Thus, it is crucial for the whole IC engine efficiency and lifetime. A lot of research effort is put into increasing the performance of this complex and highly dynamic system. Advanced, comprehensive models play an important role in understanding and improving the PRC system. In the presented work, the effect of load on the operation of the ring pack of an automotive gasoline engine is analyzed. A comprehensive model that covers the gas flow through the crevices of the PRC system, ring displacements in the groove, and ring lubrication was used for this analysis. The results of the simulations show that the local thickness of the oil film, especially near the piston top dead center is compared to the height of the combined surface roughness of a cylinder liner and piston rings, and friction-related asperity contact strongly increases as the engine load increases. The simulations also show that the engine load affects the axial displacements of the rings in the grooves but practically does not affect the thickness of the oil film left by the ring pack on the cylinder liner.

Transient characteristic evaluation and optimization of supercritical CO2 Brayton cycle driven by waste heat of automotive gasoline engine

Under the severe situation of low energy efficiency and strict emission standards, waste heat recovery, is considered to be a feasible technology, to achieve fuel economic in automobile industry. Among them, supercritical CO2 Brayton cycle has become one of the most promising technology owing to its high efficiency and compactness. Besides, the exhaust temperature and flow of automobile engine change dramatically in practice, resulting in a negative impact on the thermodynamic performance of the power cycle. Therefore, this paper develops a dynamic model of waste heat recovery system, carries out operating parameters analysis, transient response characteristics research and performance optimization, and finally proposes an improved method to adjust turbine inlet temperature to obtain higher output power. The change trend displays that the influence of turbine inlet pressure on thermodynamic performance is opposite to the dynamic response characteristics, and similar results also occur under engine start-up conditions. The numerical results indicate that the optimized output power and electric production cost reach 2.97 kW and 0.38 USD/kW·h, compared with the previous method, an improvement of 3.48% and 5.00% are achieved, respectively, reflecting the significance of energy conservation and emission reduction.

A Recent Electronic Control Circuit to a Throttle Device

The main objective of this paper was to conceive a new electronic control circuit to the throttle device. The throttle mechanical actuator is the most important part in an automotive gasoline engine. Among the different control strategies recently reported, an easy to implement control scheme is an open research topic in the analog electronic engineering field. Hence, we propose using the nonlinear dwell switching control theory for an analog electronic control unit, to manipulate an automotive throttle plate. Due to the switching mechanism commuting between a stable and an unstable controllers, the resultant closed-loop system is robust enough to the control objective. This fact is experimentally evidenced. The proposed electronic controller uses operational amplifiers along with an Arduino unit. This unit is just employed to generate the related switching signal that can be replaced by using, for instance, the timer IC555. Thus, this study is a contribution on design and realization of an electronic control circuit to the throttle device.

An Internal Model Control-Based Approach for Characterization and Controller Tuning of Turbocharged Gasoline Engines

This brief develops a method for system characterization and controller tuning for the boost control system of automotive turbocharged gasoline engines. The method utilizes the relay feedback technique for system characterization, followed by the internal model control (IMC) technique for controller tuning. The novelty is that instead of a high fidelity plant model, an ultrasimplified gain-integrator-delay model is employed in the IMC controller. As we show, our method leads to a time-efficient calibration process, assigns a desired closed-loop bandwidth exactly , and leads to good stability margins. A detailed and thorough analysis of the method, including its fundamental limitations, is provided. The method is experimentally applied to the boost control system of a turbocharged gasoline engine, where it is shown that the controller gains can be reliably computed at various engine operating points. The method identifies turbocharger speed as the best scheduling parameter for the controller gains, and the resulting controller is experimentally shown to yield good tracking performance.

Energy efficiency of automotive gasoline engine: current approaches

Introduction. To meet the promising requirements fuel consumption and CO 2 emissions of passenger cars and commercial vehicles of 2025-2030 further improvement of the design and workflowof a gasoline internal combustion engine (ICE) is required in the full range of the working map, especially at high loads. The purpose of the study was to review and analyze ways to improve the indicator efficiency of a gasoline ICE and approaches aimed at increasing efficiency by reducing heat losses. Methodology and research methods . The review of barriers to increasing the indicator efficiency of a gasoline ICE was based on the analysis of the ideal and real Otto cycle and the results of experimental and calculated foreign and domestic studies of recent years aimed at increasing fuel efficiency by reducing heat losses. Scientific novelty and results . It was shown that effective new approaches to reduce the heat losses of the ICE of the future were: organization of combustion of a stoichiometric mixture diluted with a large amount of cooled recirculated exhaust gases (up to 25-35%) at high loads; increasing the ratio of the piston stroke to the cylinder diameter S/D to a value of the order of 1.5; the use of thin thermal barrier coatings that provide a “temperature swing” of the combustion chamber surface. Combined with proven modern technologies (direct fuel injection, variable valve drive, etc.), they can significantly increase the optimal geometric compression ratio, significantly reduce heat loss to the walls of the combustion chamber and the tendency of the ICE to detonate, and provide an increase in the indicator efficiency up to 49-53%. The practical significance lies in the possibility of using the results of the work when choosing a scheme and design solutions for a promising gasoline ICE with reduced fuel consumption and CO 2 emissions.

Efficiency, Productivity, and Congestion Performance: Analysis of the Automotive Cluster in Mexico

By using data envelopment analysis and productivity measures obtained via Malmquist index, this paper investigates the patterns and dynamics of efficiency, productivity, and technological change of the automotive sector in Mexico. Particularly, we examine five subclusters (automotive parts, gasoline engines and engine parts, motor vehicles, small vehicles, and metal mills and foundries) and four regions (border, center, Bajio, and others) over the period 2003–2013. It is also studied the impact of the Great Crisis on the automotive cluster and subclusters efficiency and productivity performance before and after 2009. We also identify input congestion, and distinguish its source. Among other results, we find congestion in the center and border regions and various degrees of resilience to the Great Crisis.

Fault Prediction via Symptom Pattern Extraction Using the Discretized State Vectors of Multisensor Signals

Fault prediction and early degradation detection have received considerable attention in many engineering disciplines. Fault symptoms can be identified by abnormal values or unusual trends in the monitored sensor signals over a certain period prior to fault occurrence. However, how to extract abnormal pattern, particularly those with conditional relations among multiple sensor signals, remains unclear. Pattern extraction is further difficult particularly when there is no gradient relationship between measurements and operational states due to highly scattered data and unclear boundaries for distinguishing operational states. Additionally, defining the time period for symptom periods is challenging. To resolve these issues, we define the terms symptom pattern and symptom period, and then present a symptom pattern extraction method that collects all evidence of potential fault occurrence from multiple sensor signals. We postulate that, given time markers of fault occurrences, a symptom period precedes the occurrence of a fault. Symptom patterns are defined as either only found in the symptom periods or not found in the given time series, but similar to fault patterns. We further discuss an iterative search procedure for determining the length of symptom periods and propose a severity assessment method for symptom patterns. Finally, we apply the symptom pattern extraction and severity assessment methods to an online fault prediction procedure. By assessing the total severity of patterns in the monitoring window, early warning decision can be made. The procedure is tested in the early detection of abnormal cylinder temperature in a marine diesel engine and automotive gasoline engine knocking.

Effect of N/C Ratio on Precipitation Behavior of (Cr,Fe)23C6 Carbide in Novel Cast Austenitic Heat-Resistant Steels during Directional Solidification

The precipitation of (Cr,Fe)23C6 carbide could significantly degrade the mechanical properties of Nb-bearing cast austenitic heat-resistant steels, designed for exhaust components of automotive gasoline engines at 1000 °C. In the current research, the precipitation behavior of (Cr,Fe)23C6 carbide in these alloys, with great variations in N/C (Nitrogen/Carbon) ratio, was investigated through the liquid metal cooling directional solidification method, combined with thermodynamic calculations. Microstructural characterization suggested that the (Cr,Fe)23C6 carbide formed in the steady-state zone and the competitive zone, upon cooling to room temperature, after the solidification ended. It grew in the colony of the δ-ferrite, through the eutectoid reaction and showed different concentrations of C and Si from the δ-ferrite. Its precipitation temperature decreased significantly with increasing the N/C ratio, thereby retarding its precipitation. Therefore, the quantity of (Cr,Fe)23C6 carbide could be limited though increasing the N/C ratio of this type of alloys.

The dual-port fuel injection system for fuel economy improvement in an automotive spark-ignition gasoline engine

The purpose of the present study was to investigate the performance of the dual-port injection (DPI) system in an automotive spark-ignition engine. The DPI system utilizes two port fuel injection (PFI) injectors per cylinder, i.e., one injector at each intake port. An original 4-cylinder PFI engine head was modified to accommodate total 8 PFI injectors. In the present study, three spray angles and two install configurations were investigated in the intake port visualization, steady-state part-load experiments, and cold-start experiment. The intake port spray visualization experiment showed that the wider fuel spray provided better fuel distribution, but also more wall wetting. The steady-state engine experiment at the several critical part-load conditions showed that the DPI system in combination with the open-valve-injection strategy achieved the most brake specific fuel consumption (BSFC) reduction of 4.6%. The average BSFC reduction of the 9-point experiment was 2.8%. The cold-start experiment also showed a fuel economy gain by the DPI system. In the cold-start experiment the wider spray angle exhibited higher total hydrocarbon emission likely due to the greater wall wetting observed in the intake port spray images.

Control-Oriented Cyclic Modeling Method for Spark Ignition Engines

Automotive engine is a sophisticated dynamical control system involving both continuous-time dynamic behavior and event-based cyclic state transition. To grasp the engine dynamics accurately, this paper proposes a hybrid model structure for automotive gasoline engines that not only consists of the continuous air path model, actuator response model, but also includes the cyclic residual gas mass model and combustion process model. The proposed model adopts an extended Kalman filter to on-line estimate the cyclic state and it has the potential to be applied for the real-time optimal control design to improve the transient control performance. The precision of the model has been evaluated by comparing with the measurement data and the validation results demonstrate the satisfactory model matching behavior.

The impact of running-in on the friction of an automotive gasoline engine and in particular on its piston assembly and valve train

Generally, mating surfaces that are in tribological contact undergo a running-in process at the beginning of their operational lifetime. During this running-in phase, the tribological operating condition changes significantly leading ideally to long-term operation with a minimum of continuous wear. While this process and its duration are rather well understood for single machine elements like journal bearings, it is the aim of this work to investigate the running-in behaviour of more complex systems like an internal combustion engine and its sub-assemblies. To gain insight into the influence and duration of this running-in phase, a series of tests have been performed under realistic engine operating conditions. To be able to separate the running-in processes for the individual subsystems’ piston assembly, valve train and journal bearings of the crank train, a large series of tests have been conducted for a conventional gasoline passenger car engine. The results show a strong influence of the running-in process on total engine friction, which can be attributed mostly to the direct acting valve train and to a considerably lesser extent to the piston assembly.

Analysis of the potential of a new automotive two-stroke gasoline engine able to operate in spark ignition and controlled autoignition combustion modes

The need to reduce the emissions coming from automobiles encourages the attempts to study different engine configurations and new combustion strategies. In this case, a two stroke engine able to operate in Controlled AutoIgnition (CAI) and Spark Ignition (SI) combustion modes is studied, with the purpose of getting lower NOx and CO2 emissions than with other currently employed solutions. The engine configuration retained for the research is a uniflow scavenging configuration with intake ports in the cylinder liner and exhaust valves in the cylinder head. These valves are controlled by a Variable Valve Timing (VVT) system. The scavenging is guaranteed by an external blower driven by the crankshaft. Finally, the fuel supply is performed by a direct injection (DI) air-assisted fuel injection system.Through this paper the adjusting parameters to control the engine operation, as well as their influence on the CAI and SI combustion modes have been studied, providing the most relevant information and knowledge for controlling and optimizing the engine performance. Once these controlling parameters were studied, an EGR system was introduced in order to analyze the effect of this other parameter over the combustion process, as well as to determine the potential benefits of introducing such a system in this type of engines.

Effects of lean combustion coupling with intake tumble on economy and emission performance of gasoline engine

To improve the economy and emission performance of automotive gasoline engine, the approach of lean combustion coupling with intake tumble was investigated. A port blocker was designed on intake manifold so as to generate intake tumble, and then the sweeping test of excess air coefficient was conducted under engine common conditions (2000 r/min, 2.6 bar) in two port blocker states (opening and closing). On this basis, the effects of lean combustion coupling with intake tumble on the working process, combustion and emission performance of gasoline engine were studied. The tested results indicate that lean combustion limit is obviously extended with acceptable combustion stability by utilizing intake tumble, thus the potential of energy conservation and emission reduction by lean combustion can be further enhanced. Compared with the initial state of original engine (λ = 1.0, port blocker closing), the indicated thermal efficiency can be increased by 7.2%, and the specific emissions of CO2, CO, HC and NOX can be reduced by 5.8%, 72.2%, 12.0% and 85.3% at most, respectively. In particular, the minimum specific emission of NOX is only 2.0 g/(kW·h). The results demonstrate that lean combustion coupling with intake tumble has great potential of energy conservation and emission reduction for gasoline engine.

Multi-location laser ignition using a spatial light modulator towards improving automotive gasoline engine performance

We report on a study into multi-location laser ignition (LI) with a Spatial Light Modulator (SLM), to improve the performance of a single cylinder automotive gasoline engine. Three questions are addressed: i/ How to deliver a multi-beam diffracted pattern into an engine cylinder, through a small opening, while avoiding clipping? ii/ How much incident energy can a SLM handle (optical damage threshold) and how many simultaneous beam foci could thus be created? ; iii/ Would the multi-location sparks created be sufficiently intense and stable to ignite an engine and, if so, what would be their effect on engine performance compared to single-location LI? Answers to these questions were determined as follows. Multi-beam diffracted patterns were created by applying computer generated holograms (CGHs) to the SLM. An optical system for the SLM was developed via modelling in ZEMAX, to cleanly deliver the multi-beam patterns into the combustion chamber without clipping. Optical damage experiments were carried out on Liquid Crystal on Silicon (LCoS) samples provided by the SLM manufacturer and the maximum safe pulse energy to avoid SLM damage found to be 60mJ. Working within this limit, analysis of the multi-location laser induced sparks showed that diffracting into three identical beams gave slightly insufficient energy to guarantee 100% sparking, so subsequent engine experiments used 2 equal energy beams laterally spaced by 4mm. The results showed that dual-location LI gave more stable combustion and higher engine power output than single-location LI, for increasingly lean air-fuel mixtures. The paper concludes by a discussion of how these results may be exploited.

Effect of Circuit Geometry on Steady Flow Performance of an Automotive Turbocharger Compressor

Downsizing and turbocharging are today considered an effective way to reduce CO2 emissions in automotive gasoline engines. To this aim, a deep knowledge of turbocharger behavior could be a key solution to improve the engine-turbocharger matching calculation. The influence of the intake system geometry on the surge line position is an important aspect to guide the project of the intake manifold, enlarging the compressor stable zone. This aspect has a considerable impact on engine performance, especially during transient operation. A wide experimental investigation was carried out at the turbocharger test facility of the University of Genoa on a small turbocharger compressor. Compressor characteristic curves measured considering an automotive intake circuit are compared with standard maps provided by turbocharger's manufacturer. This information allows the optimization of 1D model implementing more realistic maps of compressor. The influence of three different layouts has been investigated varying overall circuit volume and length, keeping values in a range compatible with passenger cars packaging constraints. In the paper, the main results of the experimental campaign are presented taking into account the influence of geometry variations on compressor map and surge line position.