• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.242-247
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• 2003

An experimental study presents characteristics of combustion in a combustion chamber by port deactivation valve for economy and emissions standards. In order to use combustion properties data it is necessary to build some data base, which use cylinder pressure sensor, etc. Port deactivation valve has been developed to satisfy requirement of achieving sufficient swirl generation to improve the combustion. A feasibility and necessity of combustion pressure based cylinder spark timing control has been examined. So, this was obtained the Coefficient of Variation(COV) and the mass-burned(MFB). The characteristics of pressure ratio fraction is similar to that of mass-burned fraction. Using the results of the test, the effects of the combustion chamber can be improved combustion stability by port deactivation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.878-883
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• 2008

The spray characteristics of a high pressure 6-hole injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing, in-cylinder charge motion, fuel injection pressure and coolant temperature were investigated using the 2-dimensional Mie scattering technique. It was confirmed that the in-cylinder charge motion played a major role in the fuel spray distribution during the induction stroke while the propagation of fuel spray was restrained during the compression stroke by the increasing pressure and the upward moving piston. In additions, it was confirmed that the liquid fuel droplets existing at the sprays edges were vaporized by the increase of the coolant temperature.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.57-64
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• 1991

Spart-ignition engine knock is an abnormal combustion phenomenon originated from auto- ignition of a portion of or the entire end-gas during the later stage of combustion process. And engine knock is accompanied by a vibration of engine cylinder block and a high-pitched metallic noise. Engine knock is characterized in terms of its intensity, its occurrence crank angel and the percentage of engine knock cycles. To characterize engine knock, a precise measurements of cylinder pressure and a statistical analysis of cylinder pressure data are needed. The purpose of this study is to develope a technique to measure engine knock and its characteristics as a function of ignition timing change. A 4-cylinder spark-ignition engine and unleaded gasoline, whose octane number was 94, were used for experiments. To measure engine knock and to analyze engine knock characteristics, cylinder pressure data were sampled by a high speed data acquisition system which was developed in this study. Cylinder pressure data were sampled at each 0.1.deg. crank angle and the number of cycles continuously sampled was 80.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.183-191
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• 1997

For the improvement of ignitability we need ignition energy and its discharge characteristics which are suitable for a part distribution of the mixture density around the ignition spark plug and the flow characteristics of the mixture in the combustion. Especially, for the solving of the instability of initial ignition and lean ignitability limit in the case of lean-burn combustion, the more powerful ignition energy is required. The conclusions from the observation can be summarized as follows: 1) The ignitability limit for HIS expands wider and the combustion is more stable than for CDI. 2) The combustion duration and ignition timing depend upon the distribution of local mixture density in the vicinity of ignition spark plug.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.66-73
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• 2004

This paper presents characteristics of combustion and exhaust gas properties according to variation of the combustion chamber for economy and emissions standards. In order to use combustion and exhaust gas properties data, it is necessary to build some data base, which use cylinder pressure sensor and emission tester. A feasibility and necessity of combustion pressure based cylinder spark timing control has been examined. So, this was obtained the coefficient of variation(COV) and the specific fuel consumption(sfc). Using the results of the test, the effects of the variable combustion chamber can be improved combustion stability and be reduced exhaust emission.

• Journal of Mechanical Science and Technology
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• v.16 no.11
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• pp.1457-1469
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• 2002

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an Sl engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it Is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swir and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.5
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• pp.1148-1160
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• 2001

An electronic control system of the automobile engine for optimal start and idle speed control has been developed. This system employs the microcoputer-based electronic control unit and crank angle sensor for precise control on fuel injection, ignition timing, and idle speed more quickly and accurately at the start and idling. Consequently, the number of misfire can be reduced during been affected by air flow rate, idle quality(roughness), spark timing, fuel injection, water temperature, and load, Thus, this electronic control system strivers to reach the optimal idle operating point, defined the lowest idle speed(fuel economy) and idle quality(roughness), under any engine operating conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.104-112
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• 1999

An experimental study for reducing the exhaust hydrocarbon emission at spark ignition engine using timed secondary air injection is carried out . In this study, secondary air injection timings and durations are controlled to decrease the hydrocarbon emission and to increase exhaust gas temperature at cold and warm-up engine conditions. The hydrocarbon reduction rate and exhaust gas temperature are compared between timed secondary air injection and continuous air injection. The optimum secondary air injection timing for reducing the hydrocarbon emission is at the exhaust valve open timing. At some engine conditions , the hydrocarbon emissions are decreased to 10% of engine raw values and exhaust gas temperatures increase by 20$0^{\circ}C$ with times secondary air injection . Timed secondary air injection has more hydrocarbon reduction rate that continuous secondary air injection except some engine conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.67-74
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• 2001

A synchronized secondaty air injection method has been developed to hydrocarbon emission by injecting secondary air intermittently into exhaust port. The method has been tested in a single cylinder spark-ignition engine operating at cold-steady / cold-start conditions. Effects of air injection timing, intake pressure and engine air-fuel ratio have been investigated at cold-steady condition. Also, hydrocarbon emission and exhaust gas temperature with catalytic conberter are compared with a continuous SAI method and base condition at cold-start condition. Resules show that hydrocarbon reduction rate and exhaust gas temperature are sensitive to the timing of synchronized SAI. At cold-steady condition, HC emission is minimum at engine air-fuel ratio of 10. At cold-start condition, the accumulated hydrocarbon emission during the first 120 s decreases about 56% and 22% with the synchronized and continuous SAI, respectively, compared to that of base condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.198-210
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• 1998

A crank angle-based engine control system has been developed for use as an engine research tool to provide precise control of the fuel injection(timing and duration) and ignition(timing and dwell) in real-time. The engine event information is provided by the engine shaft encoder, and the engine control system uses this information to generate spark and injector control signals for relevant cylinders. Eight different engine types and four different rotary encoder resolutions can be accommodated by this system. Also this system allows a user to individually control the ignition and fuel injection for each cylinder in a simple manner such as through a keyboard or in a real-time operation from a closed-loop control program.