• Title/Summary/Keyword: Exhaust variable valve

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A Study on the Suitable Number of the Exhaust Variable Valve Spring for Semi-active Muffler (반능동형 머플러의 배기가변밸브 스프링 적정상수에 관한 연구)

  • Park Se-Jong;Seo Ho-Chul;Son Sung-Man;Park Kyoung-Suk
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.5 s.182
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    • pp.137-142
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    • 2006
  • The muffler which reduce the exhaust noise and vibration from engine influence on the engine performance. Recently, exhaust variable valve has set up in the muffler controls the backpressure in the exhaust system. And the backpressure variation according to the exhaust variable valve opening has developed the engine performance. First, the preceding of structural analysis is needed and simulation experiment is requested for the study on the design factor to influence on the operation of the exhaust variable valve. In this study, setting up the various variables according to each composition element needed for the structural analysis of the exhaust variable valve, it is experimented the analysis on the influence of each design factor with the calculation of stress distribution and the displacement to cause about the backpressure for the valve through parameter study.

A Study on the Exhaust Variable Valve for Automobile Muffler (자동차 머플러용 EVV에 관한 연구)

  • Park D.U.;Park K.S.;Park S.J.;Son S.M.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.661-665
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    • 2005
  • The muffler reducing the exhaust noise and vibration from the engine influence on the engine performance. Recently the semi-active muffler was developed and adopted to the actual use in consideration of the cost and technical side for noise and vibration. This study is about the recently developed semi-active muffler. This paper attempt to analyze the dynamic stress field on the gate plate by using the finite element methods. According to the analysis of the Exhaust Variable Valve, its spring has the most influence on its operation compare with effects of other components. The design parameters of the Exhaust Variable Valve such as the spring displacement, diameter, coil number, free angle and so forth were used.

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Effect of Valve Lift and Timing on Internal Exhaust Gas Recirculation and Combustion in DME Homogeneous Charge Compression Ignition Engine (DME 예혼합 압축 착화 엔진에서 밸브 양정과 개폐시기가 내부 배기가스 재순환과 연소에 미치는 영향)

  • Jang, Jin-Young;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.4
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    • pp.93-100
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    • 2009
  • Intake/exhaust valve timing and exhaust cam lift were changed to control the internal exhaust gas recirculation (IEGR) and combustion phase of homogeneous charge compression ignition (HCCI) engine. To measure the IEGR rate, in-cylinder gas was sampled during from intake valve close to before ignition start. The lower exhaust cam made shorter valve event than higher exhaust cam and made IEGR increase because of trapping the exhaust gas. IEGR rate was more affected by exhaust valve timing than intake valve timing and increased as exhaust valve timing advanced. In-cylinder pressure was increased near top dead center due to early close of exhaust valve. Ignition timing was more affected by intake valve timing than exhaust valve timing in case of exhaust valve lift 8.4 mm, while ignition timing was affected by both intake and exhaust valve timing in case of exhaust valve 2.5 mm. Burn duration with exhaust valve lift 2.5 mm was longer than other case due to higher IEGR rate. The fuel conversion efficiency with higher exhaust valve lift was higher than that with lower exhaust valve lift. The late exhaust and intake maximum open point (MOP) made the fuel conversion efficiency improve.

Study on distributing Pressure and Velocity on Exhaust Variable Valve Face of Back Pressure (배기압력이 배기가변밸브 면에 분포하는 압력과 속도에 관한 연구)

  • Kim, Kwon-Se;Choi, Doo-Seuk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.4
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    • pp.1825-1830
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    • 2014
  • Environmental emission of recent automobile is drastically enhanced that it is one of the obvious assignments of exhaust system. This study is a purpose to establish of influence distribution on maxima and minima through the location of pressure on exhaust variable valve. The experiment are checked with real angles using camera which exhaust variable valve is opened side of point. Data has extracted to opening angles with internal flow, pressure. Exhaust variable valve through the floating analysis was analyzed the characteristic of location point about pressure and velocity. The pressures indicated the reduced results internal pressure within muffler. The velocity indicated an opposite results and vibration state of valve was verified to be operated as high speed from lower section. The conclusion to obtain from this study was found out the result to make the optimum back pressure condition as more increasing pressure distribution on valve face if the velocity location attracted by bottom point in order to improve for engine performance.

Study on Analytic of Opening Angles for Muffler Variable Valve of Automobile (자동차 머플러 내의 가변밸브의 열림 각에 관한 해석적 연구)

  • Park, Chungyeol;Kim, Kwonse;Kim, Jongil;Choi, Dooseuk
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.2
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    • pp.190-196
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    • 2014
  • Exhaust system by reinforcement of environment regulation came to the foe study necessity. And Exhaust system has necessary to increase the engine performance and silence. From this cause, Automobile has significantly considered production expense. this study makes process for checking the characteristics about Exhaust variable valve within muffler. Variable valve might reduce the baffle within muffler, It was possible to remove the front muffler. Therefor, To miniaturize a size of muffler might be increased by performance through cost-cutting effect and controling of back pressure. Because the Study on Variable valve installed within muffler, to measure the real data was hardly resulted one of the assignments. From manufactured conduct device, might measure data one of piece which was up-graded of problem. Considering to these point, stressed pressure distribution has analyzed on cross section, floating characteristics about velocity distribution around variable valve using analysis as computational fluid dynamics of Ansys with completed measurement data.

Variation of Exhaust Gas Temperature with the Change of Spark Timing and Exhaust Valve Timing During Cold Start Operation of an SI Engine (스파크 점화기관의 냉시동시 배기밸브 타이밍 및 점화시기 변화에 따른 배기가스의 온도변화)

  • Yang Chang-Seok;Park Young-Joon;Cho Yong-Seok;Kim Duk-Sang
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.3 s.234
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    • pp.384-389
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    • 2005
  • Experimental study of variation of exhaust gas temperature was carried out with the changes of spark timing and exhaust valve timing during the cold start operation of an SI engine. To investigate the effects of these variables on combustion stability, cylinder pressure and exhaust gas temperature were measured and analyzed. Experimental results showed that exhaust gas temperature increased when spark and exhaust valve timings were retarded from the baseline cases. However, combustion stability during cold start deteriorated under the retarded conditions. To increase exhaust gas temperature for fast warmup of catalysts while maintaining combustion stability, an optimal condition for spark and valve timing retard should be appied for the cold start period.

A Study on the Residual Gas Fraction in Cylinder by the Adjustment of Variable Valve Timing with Volumetric Efficiency (체적효율을 고려한 가변밸브 개폐시기의 조정에 의한 실린더내 잔류가스량에 관한 연구)

  • 남정길
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.82-88
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    • 2001
  • The EGR is needed fur one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated. That is a reason why we consider using the internal EGR system. The internal EGR is a system which reduces NOx by controling the residual gas fraction in cylinder by changing valve timing and valve lift of intake and exhaust. In this paper, characteristics of volumetric efficiency and residual gas fraction in cylinder were investigated for various engine speeds by changing valve timing and valve lift of intake and exhaust in the 4 stroke-cycle diesel engine. Volumetric efficiency and residual gas fraction were calculated by the method of characteristics. As the results, residual gas fraction and volumetric efficiency in cylinder by variable valve timing were visualized.

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Flow and Combustion Characteristics according Control Strategy of Variable Valve Duration System for Compression Ignition Engine (압축착화기관용 가변밸브 듀레이션(VVD)시스템의 제어전략에 따른 유동 및 연소성능 해석)

  • Cho, Insu;Kim, Wootaek;Lee, Jinwook
    • Journal of ILASS-Korea
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    • v.25 no.2
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    • pp.45-50
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    • 2020
  • Recently, global warming and environmental pollution are becoming more important, and fuel economy is becoming important. Each automobile company is actively developing various new technologies to increase fuel efficiency. CVVD(Continuously Variable Valve Duration) system means a device that continuously changes the rotational speed of the camshaft to change the valve duration according to the state of the engine. In this paper, VVT(Variable Valve Timing) and CVVD were applied to a single-cylinder diesel engine, and the characteristics of intake and exhaust flow rate and in-cylinder pressure characteristics were analyzed by numerical analysis. In order to analyze the effect of CVVD on the actual engine operation, the study was performed by setting the valve control and injection pressure as variables in two sections of the engine operating region. As a result, In the case of applying CVVD, the positive overlap with the exhaust valve is maintained, thus it is possible to secure the flow smoothness of air and increase the volumetric efficiency by improving the flow rate. The section 2 condition showed the highest peak pressure, but the pressure rise rate was similar to that of the VVT 20 and CVCD 20 conditions up to 40 bar due to the occurrence of ignition delay.

THEORETICAL FLOW ANALYSIS AND EXPERIMENTAL STUDY ON TIME RESOLVED THC FORMATION WITH RESIDUAL GAS IN A DUAL CVVT ENGINE

  • Myung, C.L.;Kwak, H.;Hwang, I.G.;Park, S.
    • International Journal of Automotive Technology
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    • v.8 no.6
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    • pp.697-704
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    • 2007
  • Recently, a variable valve timing system has been widely adopted in internal combustion engine in order to improve the fuel economy and torque at low engine speed. In addition, it is known that varying valve timing according to the various engine operations could reduce exhaust gas, especially NOx, because of residual gas by valve overlap. In this study, to improve the low exhaust gas and fuel economy at part load condition, the residual gas and back flow of exhaust gas due to valve overlap were calculated computationally. Moreover, the characteristics of engine performances and NOx formations were investigated with the experiment of combination of intake and exhaust valve timing condition. Under these various valve operating conditions, the effects of both the positive valve overlap and negative valve overlap(valve underlap) were examined simultaneously. Finally, the characteristics of cyclic THC emission were analyzed by using Fast Response FID(FR-FID) in the cylinder, intake port and exhaust port positions. Besides, the effect of the different gradients of the valve timing change on engine performance was investigated and an optimum control strategy was suggested.

IDLE PERFORMANCE OF AN SI ENGINE WITH VARIATIONS IN ENGINE CONTROL PARAMETERS

  • Kim, D.S.;Cho, Y.S.
    • International Journal of Automotive Technology
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    • v.7 no.7
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    • pp.763-768
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    • 2006
  • Emission reduction in the cold start period of SI engines is crucial to meet stringent emission regulations such as SULEV Emissoin reduction is the starting point of the study in the which the variable valve timing (VVT) technology may be one promising method to minimize cold start emissions while maintaining engine performance. This is because it is possible to change valve overlap and residual gas fraction during cold start and idle operations. Our previous study showed that spark timing is another important factor for reducing cold-start emissions since it affects warm-up time of close-coupled catalysts (CCC) by changing exhaust gas temperature. However, even though these factors may be favorable for reduction of emissions, they may deteriorate combustion stability in these operating conditions. This means that the two variables should be optimized for best exhaust emissions and engine stability. This study investigated the effects of valve and spark timings in idle performance such as combustion stability and exhaust emissions. Experiments showed that valve timings significantly affected engine stability and exhaust emissions, especially CO and $NO_x$, due to change in residual gas fraction within the combustion chamber. Spark timing also affects HC emissions and exhaust gas temperature. Yet it has no significant effects on combustion stability. A control strategy of proper valve timing and spark timing is suggested in order to achieve a reduction in exhaust emissions and a stable operation of the engine in a cold start and idle operation.