3噸柴油動(dòng)力貨車(chē),柴油,動(dòng)力,貨車(chē) fuel electronics As oil gets more expensive, carmakers are looking at engine management systems that can cope with increasing levels of ethanol. Oil production could peak between 2010 and 2020.When it happens ,oil consumption will become more important than new discoveries ;and crude oil prices will rise and rise .Transport is the dominant sector in terms of oil use and motor vehicles will have to become more fuel-efficient. Vehicles are the largest source of pollution. Regulations have addressed the problem for transportation and real improvements have been achieved ,particularly in lead and carbon monoxide levels .But some long-term emissions have not been considered .This is particularly eve case for greenhouse gas emissions ;carbon dioxide in particular. To protect their livelihoods ,carmakers are investigating technologies and alternative fuels that either reduce oil consumption or cut emissions .Ethanol is starting to become more attractive as it can be used flexibly .The driver can run on standard gasoline or on The engine management system is an essential part of such systems’ success ,says French Tier One supplier Valeo :“They control Torque, ancillary systems ,diagnose servicing issues and ,most importantly ,emissions.” Torque control features deliver engine responses with levels of drivability and acceleration in agreement with users’ requests .Engine torque control also co-prorates functions such as traction control, cruise control, transmissions and brakes. Emissions break down into three main areas: those from the exhaust tailpipe; refueling losses and evaporative emissions .The issue is to comply with emission regulations and minimize fuel consumption .This is achieved through dedicated after-treatment components such as catalytic converters, sensors and electro-mechanical actuators. The way the engine management system controls torque and emission is complex .The quantities of air and recycled exhaust gases entering the engine are precisely managed with dedicated sensors and actuators .The right air/fuel mix for the catalyst to work properly .The mix has to ignite at the right time .The three-way catalyst then has to keep final pollutant emissions at acceptable levels. All these functions need to cooperate with other electronic units through data buses and eventually wired connections .Feedback from them allows the system to ignore any irrelevant disturbances and variations. Fuel efficient driving and reduction of greenhouse gas emissions can be achieved by using engine technologies or different fuels .Which prevails will depend on cost ,market acceptance ,and political and fiscal incentives. A vehicle fuelled with E85 fuel ,which contains 85 percent ethanol and 15 percent gasoline ,produces just 79percent of the emissions produced by pure gasoline .The interest in ethanol as an alternative fuel comes mainly from its clean burning qualities .Ethanol contains less carbon than gasoline. Compared with gasoline, most ethanol cars produce lower carbon monoxide and carbon dioxide emissions and the same or lower levels of hydrocarbon and non-methane hydrocarbon hydro carton emissions Oxides of nitrogen emissions are about the same for ethanol and gasoline vehicles. Ethanol fuel has fewer highly volatile components than gasoline and so has emissions. Moreover it can be produced from crops and so qualifies renewable fuel .Bio-ethanol produces no fossil carbon dioxide because the plants used to make ethanol take CO2 out of the air in order to grow . There is a net increase of zero. There is no need, however, to fit a specific ethanol conductivity sensor .The stoichometric air-fuel ratio of ethanol is very different to gasoline .For E100 it is 9:1, for E85 is it 10:1,for gasoline it is 14.7:1.Because of this ,it is possible to recognize the amount of ethanol and gasoline by using the standard oxygen sensor already found in gasoline architectures. Although the ethanol content of the blend at a refueling pump is specified ,the content of the vehicle tanks may be different because it may mix with any fuel already in the vehicle’ stank .It is the job of the engine management system to make the adjustments the vehicle needs to operate optimally. The energetic content of ethanol is around 30 percent less than the same volume of gasoline .Fuel consumption is potentially increased in the same proportion .To deal with the decline in fuel efficiency, carmakers install larger fuel tanks, so the vehicle’s range is not compromised .Injectors’ flow ranges have to be increased too. Ethanol has fewer highly volatile components than gasoline ,so Cole starting problems may occur .To solve this issue two kinds of solutions ate used ;In the US and Sweden ,a fuel with a minimal amount of gasoline is used ,the amount of gasoline can be as high as 30 percent in the winter .In Sweden ,where cold starts at -10℃ are common in the winter ,the vehicle is plugged in to an electric source to keep it warm. In Brazil, pure hydrated ethanol is used but with a small additional gasoline reserve tank and fuel line that is used only for cold starts .Starters can also be modified to increase the cranking speed. In Brazilian flex-fuel vehicle architectures, the engine management system must manage inputs from the cold start tank, recognizing when fuel is low .Its outputs must manage gasoline supply for cold start via an electric gasoline pump relay and a cold-start injection solenoid valve. Optional driver display information includes indicators to show the type of fuel in use and when the cold start tank is low .These features require hardware that is usually available as spares on standard gasoline ECUs .so no specific ECU has to be designed. In cold weather ,the engine management system orders a wall-wetting ,full-group pre-injection is performed using gasoline ,by simultaneously activating the dedicated electric pump and the solenoid valve .As soon as the engine speed is high enough the injectors inject the ethanol .Gasoline injection is then phased out within a few seconds. How does it know that the fuel blend is? Not by constantly measuring the mix .A standard upstream oxygen sensor recognizes the amount of ethanol and gasoline. This sensor measures the difference between the air/fuel ratio required for optimal catalyst efficiency and those effectively achieved. “Slight errors are directly cancelled with the lambda feedback correction performed on injection timing, while large ones are arreibuted to changes in fuel characteristic.” says Valeo .The new air/fuel ratio is then estimated and translated into gasoline ethanol ratio .This translation is gassed on the experimental relationship between air/fuel and gasoline/ethanol ratios. To improve robustness, estimating the ethanol ratio is triggered as far as possible by information indicating that it is likely that there has been a fuel change. When available, information on the main tank level is used. The translation of torque requests into engine management requests for the air, fuel and ignition has to take into account differences in physical parameters such as the stoichometric ratio, calorific power and combustion efficiency. For blend fuels, engine management parameters and behaviors are obtained by using the estimated ethanol/gasoline ratio as an interpolating parameter. Says Valeo .The same is used to calculate injection masses and spark advance values. Air loads differ too .There are significant differences between gasoline and ethanol’s latent heat vaporization. Roughly speaking ,the ethanol cools down the intake air and thus increases its density .The air mass admitted into the cylinders is higher as a result .Because of this ,air load calibrations have to cater for both 100 percent ethanol and 100 percent gasoline. “We expect ethanol to be blended with gasoline in most European and US fuel in the next few years,” sys Valeo. “Whether E85 will become the rule is more difficult to say, but we are ready for it.”