汽车外文翻译半机电性气门在一台单缸火花点火发动机排放影响

毕业设计外文翻译Effect of a semi electro-mechanical engine valve on performanceand emissions in a single cylinder spark ignited engine(Department of Automotive Education, Karabuk University, Karabuk 78050, Turkey)E-mail: ozdalyan@; dogan_oguzhan@yahoo.co.ukReceived Feb. 25, 2009; Revision accepted July 7, 2009; Crosschecked Nov. 8, 2009Abstract: In this study, an electro-mechanical valve (EMV) system for the intake valve of a four stroke, single cylinder, overhead valve and spark ignition (SI) engine was designed and constructed. An engine with the EMV system and a standard engine were tested to observe the effects of the EMV on engine performance and emissions at different speeds under full load. The EMV engine showed improved engine power, engine torque and break specific fuel consumption (BSFC). A 66% decrease in CO emissions was also obtained with the EMV system, but hydrocarbons (HC) and NOx emissions increased by 12% and 13% respectively. Key words: Semi electro-mechanic, Camless engine, Electro-mechanic engine valve, Engine performance, Emissions doi:10.1631/jzus.A0900119 Document code: A CLC number: TH131.Introduction All internal combustion engines (ICE) have mechanically actuated systems for opening intake and exhaust valves. Traditional valve systems have con-stant valve timing which restricts engine performance especially at low and at high engine speeds. Control-ling valve operation in ICE’s effective method for improving engine performance and emissions over a range of engine speeds. Parameters such as cam shape, valve timing, valve opening duration and valve lifting have a major impact on engine performance and emissions (Barkan and Dresner, 1989; Krauter et al., 1992; Hatano et al., 1993; Cinar, 1998; Akba, 2000; Pischinger et al., 2000; Stein et al., 1995). To increase torque and reduce fuel consumption in gasoline engines, manufacturers are increasingly using variable valve timing systems in production engines. Most valve timing systems used for improving engine performance are dependent on the camshaft. The mechanical variable valve timing systems are complex but greatly reduce the limitations of traditional valve systems, especially in regard to volumetric efficiency (Barkan and Dresner, 1989). However, except for BMW’s Valvetronic system, they cannot control all parameters such as valve timing, valve lifting and valve opening duration simultane-ously, continuously and completely independently. Lotus Engineering has developed research and production versions of their fully variable valve system that are not dependent on camshafts. The Lotus system can also independently control valve timing, valve lifting and the duration of valve opening. The power and torque increase obtained by using variable intake valve timing is between 5% and 21% The improvement in fuel consumption obtained by variable intake valve timing is between 6% and 30% (Ahmad and Theobald, 1989; Barkan and Dresner, 1989; Dresner and Barkan, 1989; Asmus, 1991; Demmelbauer et al., 1991; Gould et al., 1991; Hatano et al., 1993; Urata et al., 1993; Lee et al., 1995; Levin and Schlecter, 1996; Moriya et al., 1996; Pischinger et al., 2000). The improvement in CO emissions obtained using variable intake valve timing is between 5% and 60% (Dresner and Barkan, 1989; Gould et al., 1991; Lee et al., 1995; Moriya et al., 1996). In some studies, hydrocarbon (HC) emissions were shown to increase with the use of variable valve timing (e.g., Lee et al., 1995). Other studies showed that HC emissions were reduced by between 4% and 40% (Dresner and Barkan, 1989; Gould et al., 1991; Lancefield et al., 1993; Moriya et al., 1996). Nox emissions were reported to decrease by from 30% to 90% (Dresner and Barkan, 1989; Gould et al., 1991; Lee et al., 1995; Moriya et al., 1996). The opening speed of the valve increases the volumetric efficiency of the engine and the reduction in valve lifting decreases the friction arising in the valves (Levin and Schlecter, 1996). With a variable valve timing system employing the EMV system, all relevant parameters can be controlled simultaneously and completely independently. Therefore, in addition to improvements in fuel economy and emissions, engine performance is greatly improved (Levin and Schlecter, 1996; Pischinger et al., 2000). The variable valve timing system, which is a completely electro-mechanical system, does not need a camshaft and therefore enables the production of a camless engine. A semi electro-mechanical camless engine is one in which only intake or only exhaust valves are driven electro-mechanically. Camless engine systems have a great potential as they have the advantages of a mechanically working variable valve timing system and because the control of valve performance parameters is easier. There is a considerable collection of literature on camless engines. Recent studies have focussed on the control of the solenoids used in the EMV system and computer modeling of such control systems (Stubbs, 2000; Boie, 2001; Wang, 2001; Chang et al., 2002; Tai, 2002; Wang et al., 2002; Hoffmann and Stefanopoulou, 2003; Nitu et al., 2004; Peterson and Stefanopoulou, 2004; Kamis and Yuksel, 2005; Copeet al., 2008). However, a mass production camless engine has not yet been produced.n this study an EMV system was designed based on systems built by other engineers. The EMV engine (a semi electro-mechanical camless engine), which enables electro-mechanical operation of the intake valve, and a standard engine were tested to understand the effect of EMVs on engine performance and emissions at different engine speeds under load. During the engine tests engine valve timing, valve opening duration and ignition timing were kept constant to observe the effects of the EMV system alone. 2. Electro-mechanical valve system The components that comprised the electro- mechanic valve actuator (EMVA) were similar to those of other systems (Stubbs, 2000; Boie, 2001; Wang, 2001; Chang et al., 2002; Tai, 2002; Wang et al., 2002; Hoffmann and Stefanopoulou, 2003; Nitu et al., 2004; Peterson and Stefanopoulou, 2004; Kamis and Yuksel, 2005; Copeet al., 2008). They included an engine valve, two electro-magnets, an actuator spring and a valve spring. The diagram of an EMVA that is commonly used is given in Fig. 1. Principally, the actuator is like an oscillating mass-spring combination and is activated by an electro-magnetic force. The potential energy is transferred between two springs via the core and the valve throughout normal operation. The voltage is applied to the relevant coil during the transition. The magnetic force formed overcomes the spring, friction and gas flow forces. The upper coil closes the valve and the lower coil opens it. The EMV system works in three different positions: voltage is applied to the lower coil to open the valve. The magnetic traction force formed moves the core and opens the valve. When no voltage is applied to the coils, the core is centered exactly in the middle of two coils and in a neutral position. In this position, the valve spring and the actuator spring are compressed equally and the valve is half open. Voltage is applied to the upper coil to close the valve. The core moves upwards under the effect of the magnetic force and closes the valve. In some studies, the electrical power requirement of the EMV system is given as about 3 kW and the operating voltage that can meet this requirement would be 42 V (Trevett, 2002; Kassakian et al., 2005). An E-shaped electro-magnet is recommended as the most suitable magnet type for the EMV driving system (Nitu et al., 2004). The springs are very important to the continuous operation of the valve and they also influence the valve transition time (Wang et al., 2002; Kamis and Yuksel, 2003). The moving core completesmost of its movements with the help of the energy stored in the springs. The spring force adds to the magnetic force until the point at which half of the movement length is reached for the effective coil. After that point, it imposes a force against the magnetic force. Therefore, the selection of the springs in EMV systems is of paramount importance. 3. Electro-mechanical valve system design The appearance of the designed EMV system on the engine cylinder head is given in Fig. 2 and a block diagram of the system in Fig. 3. The EMV control system consists of a timing disc installed on the camshaft, an inductive sensor used for sensing the valve timing on the timing disk, a control unit that controls the actuator with sensor signals, a power supply that feeds the EMV control unit (18 V), an actuator that opens and closes the valve by forming magnetic force, an actuator spring and a valve spring, and a power supply with 33 V rated voltage, which feeds the EMV system (Fig. 4). The sensor that senses the valve timing on the disc which rotates with the camshaft, transmits the signal to the EMV control unit. In accordance with the signals received from the sensor, the EMV control unit directs the 33 V voltage to the lower solenoid coil. With the activation of the lower solenoid coil, the core (armature) inside the solenoid coil overcomes the valve spring force with the help of the magnetic force and opens the valve completely (Fig. 3). Thus, the EMV control unit provides opening and closing of the valve according to the timing signals received from the sensor. The EMV control system consists of two units that have the same structure: one of the units controls the lower solenoid coil, the other controls the upper solenoid coil. Upon receiving the sensor output signal, the unit that controls the solenoid coil switches the current by saturating the Darlington connected transistors and transmits the current to the lower solenoid coil via the power transistor. The same signal is used for the control of the upper solenoid coil. After the sensor output signal is inverted by a “NOT” gate, thupper solenoid coil is activated via a power transistor, as described above. 4. Experimental studies An experimental study was performed to compare the performance and emissions of a spark ignited engine (SI) containing an EMV system and an electro-mechanically controlled intake valve with an engine containing a traditional valve system (standard engine). We also aimed to test the efficiency of the EMV system. The experimental conditions included six engine speeds (1600, 2000, 2400, 2800, 3200 and 3600 r/min) under full load and other relevant parameters (Table 1). The experimental set-up (Fig. 4) consisted of a test engine, dynamometer (DC dynamometer), fuel flow meter, exhaust gas analysis system, EMV system and EMV system test apparatus. The technical specifications of the test engine used in the experiments are given in Table 1. The test engine was first tested without EMV under full load, at various engine speeds. Then the same engine was equipped with the EMV system and tested under the same conditions for comparison. To test the EMV control unit and electrical parts, a Picoscope ADC 212 general purpose PC oscilloscope (UK) was used. The measurements of the EMV system and those of the engine performance were obtained simultaneously. Emissions were measured with an MRU DELTA 1600 L exhaust gas analyzer (Germany). The specifications of the exhaust gas analyzer are given in Table 2. Data were collected for engine torque, engine power, specific fuel consumption, excess air factor (λ), CO, HC and Nox emissions. In addition, the variation in the current flowing through the lower and upper coils and sensor signal data were recorded. 5. Results and discussion 5.1 Engine performance Fig. 5 shows the torque changes for the EMV engine and the standard engine. Compared with the standard engine, the EMV engine achieved a 6.4% higher torque at 1600 r/min, a mean increment of 9% between 2000 and 3200 r/min engine speed, and 2.8% higher torque at 3600 r/min. The valve opening and closing speed depends on several conditions, especially the control algorithm. However, valve opening and closing profiles are more square-shaped in EMV applications. The intake valve is fully open for a longer time in the operation of an EMV engine because the intake valve opens faster. In addition, differences in the valve cross-sectional areas have a considerable influence on engine performance and emissions (Ergeneman et al., 1998). The computed cross-sectional area under the intake valve lift curve of the standard engine used in this study was 17.7% lower than that of the EMV engine (Fig. 6). An increased valve cross-sectional area in the first half of the induction stroke has significant importance for many reasons. For example, it produces a greater flow area as the piston starts to pull in a fresh charge. The opening of the intake valve occurs faster with the EMV system, enabling the engine to have an increased valve overlap area. Valve overlap is the point near the piston top dead center (TDC) in the 4-stroke cycle where both the intake and the exhaust valves are open at the same time. In this study, the computed valve overlap cross-sectional area of the EMV engine was about 310% greater than that of the standard engine (Fig. 6). The negative work necessary to suck air into the cylinder is reduced by increased valve overlap. Also, an increase in the valve overlap amount implies an increase in the intake manifold pressure (Hammar-lund, 2008; Leroy et al., 2008). The increase in the valve overlap cross-sectional area is equivalent to extending the valve overlap period in a standard engine (Ergeneman et al., 1998). At low speed, the effect of valve overlap is to re-introduce exhaust gasses into the combustion chamber. This is known as generating internal exhaust gas re-circulation (EGR) or internal EGR. Extending the valve overlap period facilitates an internal EGR. However, extending the valve overlap period at low speeds causes a decrease in engine performance (??nar, 1998; Akba, 2000). When the engine speed was near 2000 r/min in the operation of the standard engine, the excess air factor was determined as <1 (Fig. 7). The reason that the excess air factor was higher in the EMV engine than in the standard engine at the same engine speed, was that the air mass increased because of the more rapid opening of the intake valve. Because the remaining fuel mass was the same in both engines, the mixture became poorer in the EMV engine. The torque increase attained by the EMV system was reduced at low and high engine speeds because the fresh air-fuel mixture taken inside the cylinders mixes with the exhaust gases. Some of the fresh air-fuel mixture is exhausted together with waste exhaust gases in the operation of the standard engine. However, the torque increase was minimized because of the decrease in powerlost as a result of friction in the valve system. Changes in the power of the EMV and standard engines are shown in Fig. 8. The power of the EMV engine relative to the standard engine increases inparallel with the increase in torque. The volumetric efficiency increases because of rapid valve opening and because of the increase in the valve opening cross-sectional area (Fig. 6). The valve overlap cross-sectional area has a negative impact on engine power at low speeds, inhibiting the proportional increase in engine power. At high engine speeds, the power supplied from the operation of the EMV engine and that supplied from the standard engine are almost the same. This is because when the EMV engine is operating at maximum speed, the air-fuel mixture ratio becomes leaner. However, the EMV engine power showed a small increase because of the lower number of mechanical parts in the EMV engine. Thus, the power consumed by valve friction contributes to engine performance. Fig. 9 shows the changes in the break specific fuel consumption (BSFC) for the EMV and standard engines. The EMV engine achieved an improvement in BSFC of 18.9% at 1600 r/min, a mean improvement of 26.9% between 2000 and 3200 r/min , and an improvement of 32.2% at 3600 r/min engine speed, compared to the standard engine.Since the friction losses in the operation of the EMV engine are less than those of a standard engine,the torque increase is better. Also, as a result of a leaner fuel mixture arising from the differences in valve cross-sectional area compared to the operation of a standard engine, the BSFC is improved. The decrease in the number of mechanical parts leads to an increase in mechanical efficiency and improves engine performance and fuel consumption, especially at high engine speeds. 6. Conclusion In this study, a system that enables electro- mechanical operation of the intake valve in a single cylinder SI engine was designed and manufactured, based on published research. The system with EMV was tested with the engine under full load and at various engine speeds. As a result of our experiments, we conclude that, compared with a standard engine, the EMV system has high potential to improve engine torque, can help to reduce BSFC, shows an increase in excess air factor during operation, obtains an overall decrease of 66% in CO emissions, 12% in HC emis-emissions. sions, and 13% in NOxThe EMV system designed for this study works with 33 V DC. This operating voltage is 26% lower than that of the 42 V EMV systems. In addition, the maximum engine speed increases by 4% in the operation of an EMV engine. Moreover, the electrical behavior of the components that comprise the EMV system do not change according to the engine load. Also, the response speed of the actuator used works synchronously with the engine speed and valve timing.With design optimization, especially of the solenoid coils that comprise the actuator, the electrical power requirement of the EMV system can be reduced. The EMV system can be used more efficiently with the use of stronger actuators, sensors and microcontrollers. If the EMV system is used in ICEs, the need for some mechanical parts (camshafts, rocker arms, etc.) can be eliminated. In systems with EMV, with full optimization of the control of the valve performance parameters and of the air-fuel mixture, the improvements in engine performance and emissions can be further enhanced. In future studies, the dependency of the engine on the camshaft will be completely eliminated by driving the exhaust valve as well as the intake valve electro-mechanically. 半机电性气门在一台单缸火花点火发动机排放影响（汽车教育系，卡拉比克大学，卡拉比克78050，土耳其）E-mail: ozdalyan@; dogan_oguzhan@yahoo.co.uk2009年2月25日接收;2009年7月7日修改; 2009年11月8日校核摘要: 在这项研究中, 对于一个四冲程，单缸，架空进气阀机电阀门系统阀门和火花点火（SI）的发动机设计和建造。

根据对同一个标准的EMV系统和发动机引擎进行测试，以观察在不同的速度下，满载对发动机性能和排放影响的EMV标准EMV的引擎表明改善发动机的功率、发动机扭矩那么燃油消耗将有很大改善在EMV的工作条件下，CO排放量减少66％，，但碳氢化合物（HC）和氮氧化物排放量分别上升12％和13％关键词：半电技术、无凸轮发动机、机电式发动机气门、发动机性能、排放 主页：10.1631/jzus.A0900119 文献标识码：A 图书分类号：TH131.引言几乎所有内燃机都有机械驱动的进排气阀门在较低和较高转速下，传统的阀门系统正时限制了发动机性能在ICE的领域里控制气门的运行是提高发动机性能和在宽广的速度范围里满足排放的有效方法如凸轮形状，气门开启时间对发动机性能和排放量有重大影响巴坎和德雷斯纳，1989;克劳特等，1992;波多野等人，1993;彻纳尔，1998年;阿克巴什，2000年;皮兴格等，2000年;斯坦因等人，1995年）为了提高扭矩，降低燃油消耗，制造商正在越来越多地使用可变气门正时系统大多数发动机的气门正时系统，是依靠凸轮轴来实现的但机械控制的变气门正时系统是复杂的，特别是受制于传统阀的容积效率（巴坎和德雷斯纳，1989）。

然而，除了宝马的电子管控制系统外，无法控制所有参数，如气门，阀门和阀门提升、开放时间同步，连续和完全独立莲花工程公司开发的全可变气门系统是不依赖于凸轮轴还可以独立控制气门正时、阀门提升和开放时间通过可变进气门正时功率和扭矩可以提高5％至21％，燃油消耗降低了6％和30％（Ahmad和西奥博尔德，1989;巴坎和德雷斯纳，1989;德雷斯纳和巴坎，1989;阿斯默斯，1991年; Demmelbauer等，1991;古尔德等人，1991;波多野等人，1993;浦田等人，1993 ;李等人，1995;李文和Schlecter，1996年;守等，1996;皮兴格等，2000）CO排放降低5％至60％（德雷斯纳和巴坎，1989;古尔德等人，1991; Lee等，1995;守等，1996）然而在一些研究中，使用可变气门正时，碳氢化合物（HC）排放量增加了（例如，李等人，1995年）也有其他研究显示，HC排放减少了4％至40％（德雷斯纳和巴坎，1989;古尔德等人，1991;兰斯菲尔德等人，1993;守等，1996）氮氧化物排放减少30％至90％（德雷斯纳和巴坎，1989;古尔德等人，1991年;李等人，1995年;守等人，1996年）。

阀门的开启速度增加了发动机的容积效率，减少了阀门的摩擦（李文和Schlecter，1996年）随着可变气门正时使用的EMV系统制度，所有相关参数，可同时独立控制因此，除了能改善燃油经济性和排放外，发动机性能也大大。