1、PDF外文：http:/ 中文4465字1 Effect of a semi electro-mechanical engine valve on performance and emissions in a single cylinder spark ignited engine (Department of Automotive Education, Karabuk University, Karabuk 78050, Turkey) E-mail: ； dogan_oguzhanyahoo.co.uk Received Feb. 25, 2009； Revision acce
2、pted July 7, 2009； Crosschecked Nov. 8, 2009 Abstract: 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
3、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 hydrocarb
4、ons (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: &nb
5、sp;TH13 1.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 operat
6、ion in ICEs 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； Hat
7、ano 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 en
8、gine 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 BMWs Valvetronic system, they
9、cannot control all parameters such as valve timing, valve lifting and valve opening duration simultane-ously, continuously and completely 2 independently. Lotus Engineering has developed research and production versions of their fully variable valve system that are not dependent on camshafts. The Lo
10、tus 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%
11、 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 C
12、O 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). Othe
13、r 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
14、., 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 c
15、ontrolled 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
16、-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 adv
17、antages 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 mode
18、ling 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 3 camless engine has not
19、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 engin
20、e 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 t
21、he 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.,
22、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
23、 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
