Showing papers on "Spark-ignition engine published in 2014"

Spark Ignition Feedback Control by Means of Combustion Phase Indicators on Steady and Transient Operation

Abstract: In order to reduce fuel cost and CO2 emissions, modern spark ignition (SI) engines need to lower as much as possible fuel consumption. A crucial factor for efficiency improvement is represented by the combustion phase, which in an SI engine is controlled acting on the spark advance. This fundamental engine parameter is currently controlled in an open-loop by means of maps stored in the electronic control unit (ECU) memory: suchkind of control, however, does not allow running the engine always at its best performance, since optimal combustion phase depends on many variables, like ambient conditions, fuel quality, engine aging, and wear, etc. A better choice would be represented by a closed-loop spark timing control, which may be pursued by means of combustion phase indicators, i.e., parameters mostly derived from in-cylinder pressure analysisthat assume fixed reference values when the combustion phase is optimal. As documented in literature, the use of combustion phase indicators allows the determination of the best spark advance, apart from any variable or boundary condition. The implementation of a feedback spark timing control, based on the use of these combustion phase indicators, would ensure the minimum fuel consumption in every possible condition. Despite the presence of many literature references on the use combustion phase indicators, there is no evidence of any experimental comparison on the performance obtainable, in terms of both control accuracy and transient response, by the use of such indicators in a spark timing feedback control. The author, hence, carried out a proper experimental campaign comparing the performances of a proportional-integral spark timing control based on the use of five different in-cylinder pressure derived indicators. The experiments were carried out on a bench test, equipped with a series production four cylinder spark ignition engine and an eddy current dynamometer, using two data acquisition (DAQ) systems for data acquisition and spark timing control. Pressure sampling was performed by means of a flush mounted piezoelectric pressure transducer with the resolution of one crank angle degree. The feedback control was compared to the conventional map based control in terms of response time, control stability, and control accuracy in three different kinds of tests: steady-state, step response, and transient operation. All the combustion phase indicators proved to be suitable for proportionalintegral feedback spark advance control, allowing fast and reliable control even in transient operations. [DOI: 10.1115/1.4026966]

An investigation on effect of in-cylinder swirl flow on performance, combustion and cyclic variations in hydrogen fuelled spark ignition engine

Abstract: This study investigates how engine performance, cyclic variations and combustion parameters are affected by swirling flow in hydrogen spark ignition (SI) engine. Swirling flow was produced in the cylinder during the induction stroke by intake port having entry angles of 0°, 10°, 20° and 30°. In addition, tumble angle of 8° was positioned for given entry angles. The engine was operated under lean mixture ( ϕ = 0.6) conditions and engine speeds of 1400, 1600 and 1800 rpm. As a result, it was found that swirling flow enhances performance of hydrogen SI engine around 3% when operating engine with entry angle of 20°. The combustion duration and the cyclic variation in hydrogen SI engine can be reduced with optimum swirling flow. The stability of combustion in hydrogen SI engine is mainly dependent on cyclic variations in the flame initiation period and the cyclic variations in this period can be reduced with controlled swirling flow.

Performance and Emissions of Acetone-Butanol-Ethanol (ABE) and Gasoline Blends in a Port Fuel Injected Spark Ignition Engine

Abstract: Acetone-Butanol-Ethanol (ABE), an intermediate product in the ABE fermentation process for producing bio-butanol, is considered a promising alternative fuel because it not only preserves the advantages of oxygenated fuels which typically emit fewer pollutants, but also lowers the cost of fuel recovery for each individual component during fermentation. An experiment was conducted using a Ford single-cylinder spark-ignition (SI) research engine to investigate the potential of ABE as an SI engine fuel. Blends of pure gasoline and ABE, ranging from 0% to 80% vol. ABE, were created and the performance and emission characteristics were compared with pure gasoline as the baseline. Measurements of brake torque and exhaust gas temperature along with in-cylinder pressure traces were used to study the performance of the engine and measurements of emissions of unburned hydrocarbons, carbon monoxide, and nitrogen oxides were used to compare the fuels in terms of combustion byproducts. Experiments were performed at a constant engine speed and a comparison was made on the basis of similar power output (Brake Mean Effective Pressure (BMEP)). In-cylinder pressure data showed that the peak pressure of all the blends was slightly lower than that of gasoline, except for ABE80 which showed a slightly higher and advanced peak relative to gasoline. ABE showed an increase in brake specific fuel consumption (BSFC); while exhaust gas temperature and nitrogen oxide measurements show that ABE combusts at a lower peak temperature. The emissions of unburned hydrocarbons were higher compared to those of gasoline but the CO emissions were lower. Of particular interest is the combined effect of the higher laminar flame speed (LFS) and higher latent heat of vaporization of ABE fuels on the combustion process.Copyright © 2014 by ASME

Energy Management and Control of a Hybrid Electric Vehicle With an Integrated Low Temperature Combustion (LTC) Engine

Abstract: Low Temperature Combustion (LTC) provides a promising solution for clean energy-efficient engine technology which has not yet been utilized in Hybrid Electric Vehicle (HEV) engines. In this study, a variant of LTC engines, known as Homogeneous Charge Compression Ignition (HCCI), is utilized for operation in a series HEV configuration. An experimentally validated dynamic HCCI model is used to develop required engine torque-fuel consumption data. Given the importance of Energy Management Control (EMC) on HEV fuel economy, three different types of EMCs are designed and implemented. The EMC strategies incorporate three different control schemes including thermostatic Rule-Based Control (RBC), Dynamic Programming (DP), and Model Predictive Control (MPC). The simulation results are used to examine the fuel economy advantage of a series HEV with an integrated HCCI engine, compared to a conventional HEV with a modern Spark Ignition (SI) engine. The results show 12.6% improvement in fuel economy by using a HCCI engine in a HEV compared to a conventional HEV using a SI engine. In addition, the selection of EMC strategy is found to have a strong impact on vehicle fuel economy. EMC based on DP controller provides 15.3% fuel economy advantage over the RBC in a HEV with a HCCI engine.Copyright © 2014 by ASME

Model Predictive Control of Engine Speed During Vehicle Deceleration

Abstract: We consider the speed control of a spark ignition engine during vehicle deceleration When the torque converter bypass clutch is open, the engine speed needs to be kept close to the turbine speed to guarantee responsiveness of the vehicle for subsequent accelerations However, to maintain vehicle drivability, undesired crossing between engine speed and turbine speed must not occur, despite the presence of significant torque disturbances Hence, the engine speed during vehicle decelera- tions needs to be precisely controlled by feedback control, which has to coordinate airflow and spark timing and enforce several constraints including engine stall avoidance, combustion stability, and actuator limits We develop a model predictive controller that manipulates airflow and spark to track the reference signal for engine speed while enforcing constraints, and synthesize it in the form of a feedback law The controller is evaluated in simulations and in a vehicle, and it is shown to achieve a responsive and consistent deceleration and the potential for reducing fuel consumption

Emission characteristics of iso-propanol/gasoline blends in a spark-ignition engine combined with exhaust gas re-circulation

Abstract: Experiments were carried out in a spark-ignition engine fueled with iso-propanol/gasoline blends. Emission characteristics of this engine were investigated experimentally, including gaseous emissions (HC, CO, NOx) and particulate matter emission in term of number and size distributions. The effects of different iso-propanol percentages, loads and exhaust gas recirculation rates on emissions were analyzed. Results show that the introduction of exhaust gas recirculation reduces the NOx emission and NOx emission gives the highest value at full load condition. HC and CO emissions present inconspicuous variations at all the loads except the load of 10%. Additionally, HC emission shows a sharp increase for pure propanol when the exhaust gas recirculation rate is up to 5%, while little variation is observed at lager exhaust gas recirculation rates. Moreover, the particulate matter number concentration increases monotonically with the increase of load and the decrease of exhaust gas recirculation rate. There exists a critical spark timing that produces the highest particulate matter number concentration at all the blending ratios.