23-07-2012, 05:01 PM
VOLKSWAGEN BLUEMOTION TECHNOLOGIES
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ABSTRACT
Due to increasing impact of human activities on the environment all the major automakers are trying to improve the efficiency and emission of their products. Bluemotion is the step taken by VW group of industries to lessen the impact on environment. Bluemotion cars are identified as the cleanest, most eco-friendly cars in the segment. For attaining the good results they don’t depend on some space age technology but the employ some small modifications to the basic cycle parts along with integration of electronic circuitry to improve the efficiency of the engine the main innovative features are: TDI, TSI, DSG, automatic start/stop, Recuperation, usage of taller gear ratios, better aerodynamics, and much more. All these technologies together make the whole system a lot more efficient.
INTRODUCTION
Today the world is become more and more polluted with harmful gases and pollutants like NOx, SOx, HC, CO2, CO... to name a few. The main cause of the atmospheric pollution is our very own automobiles which now have become an integral part of our lives. At this moment replacing all the automobiles with some other alternative is simply not feasible. Due to the increasing pressure from the government and other NGO’s the automobile manufacturers are feeling the pressure which is motivating them to come with some very good ideas to make our future greener, cleaner and much more efficient tan it is today.
The adverse affects that atmospheric pollutants have on humans are: Carbon Monoxide (CO) – reduces the blood’s ability to carry oxygen, aggravates lung and heart disease, and causes headaches, fatigue, and dizziness. Sulfur Dioxides (SOx) – when combined with water vapor in the air become the major contributor to acid rain. Nitrogen Oxides (NOx) – cause the yellowish-brown haze over dirty cities, and when combined with oxygen becomes a poisonous gas that can damage lung tissue. Hydrocarbons (HC) are a group of pollutants that react to form ozone (O3), some HCs cause cancer and others can irritate mucous membranes. Ozone (O3) is the white haze or smog seen over many cities. Ozone can irritate the respiratory system, decrease lung function, and aggravate chronic lung diseases (such as asthma). Carbon Dioxide (CO2), although naturally occurring, can cause problems. In large quantities it allows more sunlight to enter the atmosphere than can escape – trapping excess heat that can lead to the “greenhouse effect” and cause global warming.
TDI (TURBOCHARGED DIRECT INJECTION)
TDI identifies all the VW advanced diesel engines using direct injection and a turbocharger. TDI engines are economical and smooth with high levels of torque (pulling power) and good energy efficiency. Fuel needs oxygen to burn and the engine has to be supplied with huge quantities of air to be effective. This problem is solved using a bigger engine - or by using a turbocharger - as in the TDI. Driven by the exhaust gases, it squeezes air more tightly into the cylinders. The air is then cooled (cool air takes up less space than hot air) and diesel is injected directly into the cylinders at very high pressure through a nozzle. It’s this intensive mixing of highly atomised fuel with the compressed air that leads to better, more efficient combustion. Makng the driving experience quiet and refined because effective sound insulation keeps noise to a minimum, while hydraulic engine mounts ensure smooth, low-vibration running. The great advantage of TDI engines is that they are very powerful, even at low revs, and economical across the entire speed range. This efficiency also means that one save on fuel costs and emit less CO2, so helping to minimise his/her impact on the environment.
The Technology
The engine uses direct injection, where a fuel injector sprays atomised fuel directly into the main combustion chamber of each cylinder, rather than the pre-combustion chamber prevalent in older diesels which used indirect injection. The engine is coupled with a turbocharger to increase the amount of air going into the engine cylinders, and an intercooler to lower the temperature (and therefore increase the density) of the air from the turbo, thereby increasing the amount of fuel that can be injected and combusted. These, in combination, allow for greater engine performance (from a more complete combustion process compared to indirect injection), while also decreasing emissions and providing more torque than its petrol engined counterpart. Similar technology has been used by other companies but "TDI" refers to these Volkswagen Group engines. Normally-aspirated engines (those without a turbocharger) made by Volkswagen Group use the label Suction Diesel Injection (SDI). The reduced material volume of the direct injection diesel engine reduces heat losses, and thereby increases engine efficiency, at the expense of increased combustion noise. A direct injection engine is also easier to start when cold, due to more efficient placing and usage of glowplugs.
The Turbocharger
To boost power output and torque, VW fitted their TDI engines with exhaust turbochargers featuring variable turbine geometry. They compress the air required for combustion, letting the engine draw in more air while its displacement and revs stay the same. A turbocharger is powered by the energy in the exhaust gas. It has two connected turbines. The turbine wheel in the exhaust stream drives the intake compressor, which sucks in air through the intake system. The compressed air is cooled by a charge air cooler before entering the combustion chamber. Because cool air is denser than hot air, more oxygen can be fed into the cylinder boosting the efficiency of the combustion process.
Overcoming turbo lag: The main disadvantage of a turbocharger is that it needs a certain gas pressure to work which are only available when engine revs are high enough. To avoid 'turbo lag' - a delay in available power - the turbocharger needs to be able to control the exhaust pressure at low engine revs.
TSI (REVOLUTIONARY PETROL ENGINE)
What is TSI? TSI is VW’s pioneering technology for petrol engines. TSI engines are compact, high-powered and use less fuel. TSI technology blends the best of their TDI diesel and FSI (Direct Injection) engines. One can enjoy excellent drivability and outstanding fuel economy. Acceleration is instant, whichever gear one is using. So overtaking is safer and one can power smoothly up hills with no delay. TSI technology is available on an increasing number of VW’s cars, from Golf to Passat.
As responsible car makers VW wanted to make its petrol engines even cleaner and more efficient, while still being fun to drive. Their aim was to create engines that used less fuel and produced lower CO2 emissions without sacrificing power. The solution their engineers came up with was both elegant and ingenious: an engine that combines petrol direct injection with twincharging – a turbocharger and a supercharger working together. The TSI engine was born. Volkswagen is the only car manufacturer in the world to offer an engine with this feature. The effect is to combine the benefits of both petrol and diesel power units: smooth and quiet on the road, TSI delivers high torque - pulling power - throughout the acceleration range with no turbo lag. The successful TSI formula combines a number of different elements.