Showing papers on "Spark-ignition engine published in 1990"

A model for hydrocarbon emissions from si engines

Abstract: A model which calculates the hydrocarbon emissions from an SI engine is presented. The model was developed in order to obtain a better understanding of experimental results from an engine operating on different fuels and lubricants. The model is based on the assumptions that fuel is stored in crevices and oil film during intake and compression followed by desorption during expansion and exhaust. The model also calculates the amount of desorbed material that undergoes in-cylinder oxidation and exhaust port oxidation. The model successfully predicts the trends followed by varying different engine parameters. The effect of changing the lubricant is of the same order of magnitude as found experimentally, but the effect of changing the fuel could not be predicted very well by the model. A possible explanation is that the lubricant film thickness varies due to viscosity variations of the oil film, when the fuel is dissolved in the film. (A) For the covering abstract see IRRD 851463.

Cylinder direct-injection type spark ignition engine

Abstract: PURPOSE:To optimize an interval between fuel injection timing of fuel injection and ignition timing in compression stroke and obtain excellent ignition and combustion by delaying the ignition timing when knocking is occurred, and also delaying the injection timing of the fuel injection in the compression stroke. CONSTITUTION:In the case of operating an engine, in the first place, the total fuel injection volume Q is calculated by means of an ECU 30 according to engine rotation speed and accel opening, and next, compression stroke fuel injection volume Qc is calculated according to the total fuel injection volume Q. Furthermore, according to a map, map ignition timing thetaigM is calculated. Next, a judgment is made on whether or not knocking is occurred, and when the knocking has been occurred, actual ignition timing thetaig is decreased by theta. Next, a judgment is made on whether or not Qc>0 is realized, and when Qc>0 is realized, that is, when compression stroke injection is carried out, compression stroke fuel injection timing thetac is calculated so that the compression stroke fuel injection timing can be delayed. Furthermore, a judgment is made on whether or not the compression stroke fuel injection volume Qc exceeds the maximum value QcMAX, and in the case of Qc>QcMAX, Qc is set as QcMAX.

Method for controlling a spark-ignition engine without a throttle flap

Abstract: A method for controlling a spark-ignition engine without a throttle flap is carried out with variable inlet valve opening durations. The method includes the steps of: detecting a speed signal having a value dependent upon the engine speed; detecting an accelerator pedal signal having a value dependent upon the accelerator pedal position; determining the intake valve opening durations as well as the fuel quantity in dependence upon the particular values of the engine speed signal and the accelerator pedal signal; and, determining the ignition angle in the dependence upon the particular values of the engine speed and fuel quantities. The method affords the advantage that for all driving conditions and even for sudden changes of the accelerator pedal signal, the masses of air and fuel are optimally adapted to each other in order to obtain high driving comfort without misfirings and with low toxic gas exhaust.

Mixture Nonuniformity Effects on S.I. Engine Combustion Variability

Abstract: For some time, spatial nonuniformities in the unburned mixture within a spark ignition engine have been suspected of contributing to cycle-by-cycle variations in combustion. In this work, and experimental structure has been developed that allowed the effects of fuel/air nonuniformity and residual gas/fresh charge nonuniformity to be separately addressed, with special regard given to their impact on the flame development process and combustion rate. Under the conditions of light loads and low speed, it was found that a decrease in fuel-air nonuniformity caused a slight reduction in the variation of the early flame development angle but had no significant impact on the statistics of the main combustion phase of IMEP. Eliminating residual gas nonuniformity by skip firing the engine and adding equivalent residual to the fresh mixture prior to entry to the cylinder had no detectable impact on the flame development process. In fact all evidence showed that the in-cylinder residual gas present under the continuous-firing conditions tested was well mixed with the fresh charge by the time of spark discharge.

Inner-cylinder direct jet type spark ignition engine

Abstract: PURPOSE:To perform satisfactory combustion by jetting the total required fuel jet amount when it is not more than a first jet amount, that is, under a low load, and jetting the fuel jet amount while being distributed to intake and compression processes when it is less than a second and not less than a third jet amount, that is, under a medium load. CONSTITUTION:In a control unit 20, a fuel pressure detected by a sensor 27, an engine speed obtained from a crank angle signal of a sensor 29, accelerator opening angle detected by a sensor 30, etc., are input to compute a fuel jet amount. When the required fuel jet amount is not more than a first jet amount which is a sum of a minimum compression process jet amount for an ignition plug 65 enough to form ignitable air fuel mixture and a minimum intake process jet amount enough to propagate frame, a fuel jet valve 5 is controlled such that the total amount is jet during compression process. When the required jet amount is not less than a third jet amount which is less than a second jet amount enough to form an even air-fuel mixture and not less than the first amount, the total amount is jet while being distributed to the intake and compression processes. Satisfactory ignition and combustion are thus performed.

Valve Event Optimization in a Spark-Ignition Engine

Abstract: A computer simulation has been developed to study the effects of valve event parameters (lift, duration, and phasing) on spark–ignition engine performance. The zero–dimensional model employs polynomial and dynamic techniques to generate cam profiles for valve event optimisation. The model was calibrated and validated against data from a General Motors 2.5 litre engine. The simulation was then used to determine optimum valve events under different engine conditions. This insight was used to improve the cam design. Subsequent engine testing confirmed that a 3 per cent improvement in peak torque could be obtained with the optimised cam.

Method and device for adjusting the ignition phase in the operation of a spark ignition engine

Abstract: The invention relates to a method and a device for adjusting the ignition phase in the operation of a spark ignition engine, especially in the case of high air ratios. In order to stabilise the combustion sequence, it is proposed according to the invention that shortly prior to the spark discharge into the ignition area a small quantity of a gaseous additive is injected at a pressure in excess of the combustion chamber pressure at the time of ignition, the additive or the additive-air mixture having a high diffusion rate, wide ignition limits and a high flame propagation speed.

Non-intrusive tachometer for spark ignition autos

Abstract: An non-intrusive tachometer for measuring engine RPM includes a hand-held probe having an antenna for sensing radio frequency electromagnetic signals radiated from an operative spark ignition engine. The probe includes means for providing a pulse signal indicative of plug firing events to signal processing means which executes a statistical algorithm to determine the time between spark plug firings and engine RPM. A visual display displays engine RPM. Automatic gain contol means provides the pulse signal with a relatively constant amplitude by compensating for the inherently wide variation in amplitude of the electromagnetic signals among different automobile ignition systems. The signal processing means and display are located separate from the probe in an emissions testing system, or the signal processing means and display are integrated within the probe.

An Experimental and Theoretical Evaluation of the Onboard Decomposed Methanol Spark-Ignition Engine

Abstract: The possibility of obtaining high efficiency and low emissions of hazardous compounds by using decomposed methanol, i.e., hydrogen and carbon monoxide, as a fuel for spark-ignition engines has been investigated theoretically and experimentally. A cycle simulation predicts that the most important advantage with the system is the opportunity to run the engine on lean air/fuel mixtures. In the experiments, bottled gas was used instead of gas from a decomposition reactor. The results indicate that the efficiency gain, relative to neat methanol, is 15-20% in the torque interval 10-60 Nm. Detected NO, emissions are very low. A control system for the onboard decomposed methanol engine has been developed, which uses engine speed as the governing parameter.

A miniaturized high-temperature pressure sensor for the combustion chamber of a spark ignition engine

Abstract: We have developed a miniaturized ‘lowcost’ pressure sensor, based on a piezoceramic tube as the sensing element, for series application in the combustion chamber of a spark ignition engine. The tube is radially polarized, so that the combustion pressure which acts along the tube axis produces a charge signal via the transverse piezoelectric effect. As the pressure sensitivity of the sensor exceeds that of a quartz transducer by nearly two orders of magnitude, it can be further miniaturized without deterioration of performance. To determine the mechanical and thermal behaviour of the sensor and to optimize its function, it has been subjected to extensive tests and numerical simulations (e.g., finite-element calculations). Bench tests on various test and production engines will help to give further information about the performance of our sensor, above all about its long-term stability.

Improved two stoke cycle spark ignition internal combustion engine

Abstract: This invention relates to a two stroke spark ignition engine having improved fuel and lubricant efficiencies achieved by decreased consumption of fuel and lubricant. The flow of air toward the cylinder (15) for combustion in the engine is divided between two passageways. One passageway (10, 30) through which a major portion of the air flows from the crankcase into the cylinder (15). Another passageway (20) directs a minor portion of the flow of air, while valve (21, 22) in the passageway admit a flow of air into the passageway, prevent a backward flow of air from the passageway, and operate in timed relation to rotation of the crankshaft (11) for admitting a flow of air into the cylinder during a limited arc of rotation of the crankshaft while fuel is delivered into that minor portion of the air flow.

Direct cylinder injection spark ignition engine

Abstract: PURPOSE: To heat a catalyst quickly to an active temperature by operating again a fuel injection valve of an engine to inject additionally fuel and mixing the fuel in exhaust to again ignite the fuel while an intake valve is closed in an expansion or exhaust stroke of the engine. CONSTITUTION: Tips of fuel injection valves 47-50 are provided in an engine body 10 to open to the insides of respective combustion chambers 24-30. Also, the combustion chambers 24-30 are provided respectively near the tops with ignition plugs 51-54. While an ECU 22 receives the signals showing loads of an engine such as the rotational frequency Ne of the engine, accelerator opening θA, etc., from respective sensors, it receives the input of catalyst temperature Tcat from a temperature sensor 55 provided in a catalyst converter 20. When the catalyst temperature is lower than a predetermined desired one, additional fuel is injected into the combustion chambers 24-30 to be mixed with exhaust in an expansion or exhaust stroke and the exhaust mixed with additional fuel is reignited for combustion upstream of the catalyst converter 20 to heat the catalyst to the desired temperature. COPYRIGHT: (C)1992,JPO&Japio

Spark ignition engine combustion process analysis

Abstract: Cylinder pressure analysis is widely used in the experimental investigation of combustion processes within gasoline engines. A pressure record can be processed to reveal detail of charge burning, which is a good indicator of combustion quality. The thesis describes the evaluation of an approximate technique for calculating the mass fraction of the charge that has burnt; a novel approach for determining heat loss to the block; the development of a powerful system for combustion analysis; and the investigation of the correlation between the crank angle location of the 50% mass burnt and minimum timing advance necessary to obtain the maximum engine torque. A detailed examination has been carried out into the uncertainties in the determination of the mass fraction burnt as suggested by Rassweiler and Withrow. A revised procedure has been developed which does not require a priori identification of the combustion end point, and a new approach is suggested to calculate the polytropic indices necessary for the pressure processing. This particular implementation of the analysis is able to identify late burning and misfiring cycles, and then take appropriate steps to ensure their proper analysis. The problems associated with the assumption of uniform pressure; alignment of the pressure changes to the volume changes; pressure sampling rate; clearance volume estimation; and calibrating the acquired pressure to absolute are also evaluated. A novel method is developed to ascertain, directly from the pressure history, the heat loss to the cylinder block. Both experimental and simulated data are used to support the accuracy of the suggested heat loss evaluation, and the sensitivity of the method to its inputs is examined. The conversion of procedures for combustion analysis into a format suitable for undertaking high speed analysis is described. The analysis techniques were implemented so that the engine can be considered to be on-line to the analysis system. The system was entitled Quikburn. This system can process an unlimited number of cycles at a particular running condition, updating the screen every 1.5 seconds. The analysis system has been used to study the potentially beneficial correlation between the location of the 50% mass burnt and MBT. The correlation is examined in detail, and found to be valid except under lean fueling conditions, which is seen to be caused by slow flame initiation. It is suggested that the optimum location of the 50% mass burnt can be used as a reference setting for the ignition timing, and as an indicator of combustion chamber performance. An engine simulation was employed to verify that changes in bum shape account for the small variation seen in the optimum 50% bum locations at different operating conditions of the engine. The bum shape changes also account for the range of optimum locations of the 50% mass burnt encountered in different engines.

Cylinder direct-injection of fuel type spark ignition engine

Abstract: PURPOSE: To obtain a good degree of firing and a good level of combustion by causing an increase in the injection amount of fuel in the compression stroke injection when the interior of the cylinder is at a low temperature. CONSTITUTION: In an internal combustion engine, during a cold period thereof, the temperature in a cylinder 4, e.g., the wall temperature of a combustion chamber 20, is low. For this reason, evaporation of a fuel injected into the cylinder 4 is deteriorated with the result that the formation of a air-fuel mixture necessary for firing or fire-flame propagation becomes insufficient. When the temperature in the cylinder 4 is low, therefore, the injecting amount of fuel in the compression stroke is increased. The Figure shows a fuel injection pattern during an intracylinder low-temperature time period. As indicated by a hatched portion, even in a region of load higher than QH a compression stroke injection is executed to an increased injecting amount of fuel. This enables the formation of a fuel-air mixture necessary for firing and simultaneously enables not only obtaining a good degree of firing but promoting the evaporation of the fuel by transfer of heat from a generated fireflame to obtain a good level of burning. COPYRIGHT: (C)1992,JPO&Japio

Spark ignition engines

Abstract: There is described a motor vehicle having a spark ignition engine in an engine compartment and having automatic advance and retard device to advance or retard the angle of the firing of the spark relative to the top dead center of the pistons in the cylinders of the spark ignition engine. The engine has a control device including a microphone carried on a vibration damping mounting on the vehicle close to the engine to detect sounds emitted during the running of the vehicle. A frequency filter is connected to the microphone connected to the detector to permit transmission of sound only in a narrow band of sound frequencies between 4,000 and 20,000 Hz which correspond to the sound range of sounds caused by knock. The output from the filter is compared with a datum and when this exceeds such datum, the automatic advance and retard is retarded to prevent knock continuing.

Method for reducing exhaust gas emissions of a spark-ignition engine with exhaust gas processor for cold starting

Abstract: In order to reduce exhaust gas emissions of a spark-ignition engine with exhaust gas processor for cold starting, the combustion air is briefly intensively electrically heated before entering the combustion space of the engine.