Blue Motion Technology - Seminar Paper

blue motion technology
Human activities are affecting the environment much more and so that every automation company is busy to make its products and projects very efficient and involving many important steps to achieve this target. And Blue motion Technology is one of them that is used by Volks Wagen group of industries and it tries to decrease the impact of human activity on the environment. Blue motion Technology based cars are known as most cleanest cars and very much Eco-friendly in the world. [More...] Volkswagen group of industry is not depending on the old or space age technology. They are making the car engines more efficient by including the electronic circuitry and by modifying some basic cycle parts of the car engine. By using blue motion technology the car engine gets various useful features like TDI, TSI, DSG, automatic start/stop, Recuperation, usage of taller gear ratios, better aerodynamics etc.The products made by using both blue motion technology and electronic circuitry, are very much efficient and reliable rather than other products.

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.
The first idea was to use a hybrid system; generally an electric hybrid is preferred over other kinds of hybrid due to its feasibility in the compact dimensions of a car. But there is a problem with hybrid electric vehicle (HEV). The weakest links are the batteries which stores the electric energy to be used by the electric motor. They are naturally heavy and quick acceleration and deceleration can severely affect the life of the batteries moreover the mining of nickel is a highly polluting process. This is why VolksWagen, which is one of the biggest automakers of the world, has preferred to go without hybrid systems. The strategy of VolksWagen is to take the conventional internal combustion engine and make them as efficient as it’s possible so that the environmental impact of these cars will be greatly reduced.
BlueMotion is a trade name (developed externally by UK's Origin Brand Consultants) for fuel-efficient automobile models from the Volkswagen Group. Volkswagen introduced the name in 2006 on the Mk4 Polo BlueMotion, and in 2007 a version based on the current Passat was released. More recently, the technology has been used in SEAT's models like the SEAT Ibiza or the SEAT León under the name Ecomotive, and in the Škoda Fabia and Superb, where the technology is called Greenline. BlueMotion versions of the Golf and Touran were released in 2008. The name refers to VW's corporate colour, blue, and echoes DaimlerChrysler's BlueTec.
BlueMotion Volkswagens use existing technology to improve on the standard engine/vehicle. Currently, Volkswagen Group focuses in three areas of improvement:

Revised engine mapping, and including diesel particulate filters help the fuel consumption and lower NOx levels.

On the Polo, Golf and Passat the last two gear ratios are longer than on standard Turbocharged Direct Injection (TDI) engine gearboxes.

On the Polo, Golf and Passat, Volkswagen have lowered the suspension, redesigned the spoilers, and performed additional enhancements underneath each car - so the air is channeled better giving less drag which produces better fuel consumption.
Why the name bluemotion? Blue - the Volkswagen colour - symbolises the elements water and air, while Motion represents a move forwards towards the future. BlueMotion Technologies have one very important aim that is to reduce the impact of cars on the environment for future generations.
Bluemotion cars are not only cleaner, more efficient cars but also offer greater performance. The result is an impressive range of refinements and innovations that save fuel and cut CO2 emissions. All the technologies have been grouped together under the badge of BlueMotion Technologies. So the environmental technologies of today are meeting the driving challenges of tomorrow. At the heart of BlueMotion Technologies are advanced TDI & TSI engines and DSG dual-clutch gearbox.
Volkswagen has not only made the car more efficient and eco-friendly but it has made the whole manufacturing process a lot more cleaner and greener making use of modern highly fuel efficient boilers and furnaces. Preaparing a life cycle assessment(LCA) is a method of understanding the amount of resources going into a car. Volkswagen has many years of experience with Life Cycle Assessments for product and process optimisation. They have even assumed a leading role in implementing and publishing life cycle inventories of complete vehicles. For instance, in 1996 they were the first car manufacturer in the world to prepare a Life Cycle Inventory study (for the Golf III) and publish it [Schweimer and Schuckert 1996]. Since then they have drawn up Life Cycle Assessments for other cars and also published some of the results [Schweimer 1998; Schweimer et al. 1999; Schweimer and Levin 2000; Schweimer and Roßberg 2001]. 
These LCAs primarily describe and identify environmental „hot spots“ in the life cycle of a car. Since then they have broadened the assessments to include production processes as well as fuel production and recycling processes [Bossdorf-Zimmer et al. 2005; Krinke et al. 2005b]. Since 2007, they have been usuing environmental commendations to inform customers and the public about the environmental properties of their vehicles [Volkswagen AG 2007a, Volkswagen AG 2007b, Volkswagen AG 2008]. 
Volkswagen is also making long-term investments in further developing and optimising Life Cycle Assessment methods. Thanks to their intensive research they have succeeded in considerably reducing the workload involved in preparing Life Cycle Inventories. Their research resulted in the development of the VW slimLCI interface system [Koffler et al. 2007]: this interface not only significantly cuts the workload involved in preparing Life Cycle Assessments of complete vehicles by automating the process, but also further improves the consistency and quality of the LCA models produced. This represents substantial progress, since preparing a complete LCA for a vehicle involves registering thousands of components, together with any related upstream supply chains and processes. Fig. 1 shows the variety of parts involved in an entire vehicle taking the Golf V as an example. All these data has helped Volkswagen to improve the manufacturing process and to reduce the use of conventional fossil fuels in the manufacturing of its cars. Hence the idea of greener cars doesent only starts at the car but it starts from the whole process of manufacturing it.

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  PD(Pumpe-Düse)  design  was  a  reaction  to  the  development  of  common  rail  fuel  injection  by  competitors  -  an attempt by Volkswagen Group to create an in-house technology of comparable performance that would not require any royalties to be paid. While Pumpe-Düse engines had a significantly higher injection pressure than older engines, they were not a match with the very  latest common rail, and weren't able to control  injection timing as precisely (a major factor in improving emissions). New engines appearing in 2009 model year Volkswagens are  using  the  common-rail  technique  with  piezoelectric  injectors.  

Fuel:  TDI  engines,  like  most  diesel engines, can run on petrodiesel or B5, B20, or B99 biodiesel subject to manufacturers' prior approval. In fuel efficiency, and clean emissions when run on biodiesel or when converted vegetable oil (which should NOT be used on the later PD engines  without  prior  conversion,  since  irreparable  damage  will  result),  TDI  engines  are  among  the  best  on  the market. This is often overlooked because they do not drive on petrol. A 2007 Volkswagen Jetta 1.9L TDI with 5-speed manual, for example, achieves 5.2 L/100 km (54 mpg UK or 45 mpg US) on the European combined-cycle test while a DSG automatic reaches 5.9 L/100 km (48 mpg UK or 40 mpg US). Newer TDI engines, with higher injection pressures, are less  forgiving about poor-quality  fuel than their 1980s ancestors. VW has recently permitted mixes up to B20, and has recommended B5 be used in place of 100% petroleum-based diesel because of biodiesel's  improved  lubricating properties. No. 2 diesel  fuel  is  recommended  since  it has  a higher cetane number  than No. 1  fuel and has  lower viscosity  (better ability  to  flow)  than heavier  fuel oils. Some owners  in North America, where  cetane  levels  are  generally poor  (as  low  as 40), use  additives or premium diesel  to  get  cetane numbers  closer  to  the  standard  levels  found  in  the  European  market  (at  least  51)  where  the  engine  is  designed. 
Improved  cetane  reduces  emissions  while  improving  performance  and may  increase  fuel  economy.  New low-sulfur petroleum-only diesel recipes cause seals to shrink and can cause fuel pump failures in TDI engines; biodiesel blends are reported to prevent that failure. 

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.
A variable turbine geometry (VTG) turbocharger does this with a system of mechanical guide vanes. These vanes move to adjust the cross-section area to maximise the air flow into the exhaust turbine. Thus at lower speeds, a higher flow can be maintained, increasing the pressure to the compressor and therefore increasing power output.  

Volkswagen’s Injection Systems
 They are one of the leaders in developing advanced efficient diesel engines with lower emissions. Their innovative engines are progressively meeting the new EU 5 standard, ahead of legislation. Their range of three to ten-cylinder turbodiesel engines are based on unit injector systems, and common rail injection.
The  pressure  at which  the  diesel  is  injected  into  the  cylinder  is  the  key  factor  in  diesel  direct injection. The fuel has to mix swiftly with the compressed air in the cylinder. The higher the pressure, the more finely the diesel is atomised for an intensive mixing of the fuel and air particles. This, in turn, leads to better and more efficient combustion process. The energy from the fuel is used more effectively and emissions are reduced. We use various injection stages within one power stroke - referred to as multiple injections. Depending on the engine design, revs and load, modern diesel engines use a pilot or double pilot injection and a main injection. Pilot injection achieves smooth combustion, ensuring that the extremely high pressures necessary  for combustion  to  take place are reached more gradually. This significantly reduces combustion noise and cuts emissions.

Piezo crystal injectors. To control the injection process precisely and cut fuel consumption and emissions significantly, they use piezo inline injectors instead of solenoid valves.  They are lighter and respond  twice  as  fast.  This enables the injector valve to switch five times faster to meter the fuel and control the injection curve far more precisely, resulting in a smoother, quieter and more efficient combustion process. A post injection phase is also possible with this type of injector, which helps the exhaust emissions system to be more efficient and results in lower emissions. Common rail - third-generation diesel direct injection. Common rail is the latest diesel engine technology and is used in many VW vehicles already.  The  common  rail  system  stores  the  injection  pressure  in  a  high-pressure  fuel  reservoir referred  to as  the  ‘common  rail’ as  it  supplies all  the  injectors.  In this system the generation of pressure and the fuel injection processes are separate.

Lines connect all the cylinder injectors to the common rail in parallel, ensuring they all have an uninterrupted supply of constant pressure. The injection quantity and timing are controlled using solenoid valves.  
The advantage of common rail is that fuel can be delivered at higher pressure, giving better mixing with air for a more efficient and cleaner combustion. This gives higher performance combined with improved fuel consumption. 
The ever-higher injection pressures that make diesel engines cleaner and more efficient than before place big demands on the common rail system. Their latest generation of diesel engines reaches injection pressures as high as 1,800 bars. For this reason they make the rail themselves, and they are the first car maker to do so.  

Diesel Particulate Filters (DPF)
The main problem with diesel engine is the amount of soot emission. This is why diesel particulate filter is an integral part of any diesel engine. The  diesel  particulate  filter:  Legislation  is  continually  driving  car  manufacturers  to  produce  cleaner  and  more environmentally  friendly vehicles. Their advanced diesel engines meet this challenge and are cleaner than ever before. One important factor is their diesel particulate filters (DPF), which are very effective in cutting particulate emissions, trapping even the finest soot particles that are produced as the engine burns diesel fuel.
The  latest generation of filters operate without additives. This makes them maintenance-free for an exceptionally long time: an initial inspection is usually carried out only after 150,000 km. The filter's lifespan is dependent on factors such as fuel quality, driving style, use and oil consumption.

 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:

Smaller Engines
At the heart of TSI is a smaller engine.  It's more efficient, as there is less power loss resulting from friction.  It's also lighter, so the engine has less weight to shift in the car. Direct petrol injection with charging. Direct petrol  injection  is  combined with  a  turbocharger or with  a  turbocharger  and  a  supercharger working  in  tandem.  This enhances the engine's combustion efficiency so the TSI engine power output is much higher than that of conventional, naturally aspirated engines. 
Hunting down every gram: The 140 PS and 170 PS TSI engines are already lightweight. Even then consistent efforts were made to reduce the weight of the new TSI even more. Its pistons and valve reliefs were designed as lightweight castings, and the geometries of the asymmetrical stem and wall thicknesses were also optimized to handle their loads. That is how weight was trimmed gram for gram. On the cylinder head, whose fundamental concept is also based on the stronger TSIs, it was possible to reduce weight by about 600 grams with a structure-optimized design. The Volkswagen engineers also reconfigured the intake port. Based on the large TSI, it was further developed with the goal of achieving a level of swirl or tumble that would not require charge movement flaps, as already mentioned. In addition, the new intake port was modified substantially. The advantage: In broad sections of the engine's operating range, it was possible to achieve quicker and even more efficient combustion with better fuel economy and a smoother engine characteristic. Valves on the TSI are actuated by two camshafts also further optimized with inlet-side adjustment. Various modifications enabled weight savings here too: The camshafts each weigh 304 grams less. Every gram counts. That is why even the cylinder head cover is 150 grams lighter. Overall, the 90-kW TSI is 14,000 grams, or 14 kilograms, lighter than a TSI with 125 kW. 

On the TSI 1.4 160PS the engine-driven supercharger operates at lower revs, with the turbocharger - powered by the exhaust gases - joining in as engine speed rises. The supercharger is powered via a belt drive directly from the crankshaft. This provides maximum pulling power on demand, even at very low engine speeds. TSI engines are designed to deliver maximum torque from engine speeds as low as 1500 or 1750 rpm. And that has the twin benefit of not only increasing your driving pleasure but also cutting fuel consumption.
The turbochargers are compact and therefore weight-optimized in design too. In keeping with the overall concept, the best dynamics and lowest fuel consumption were top priorities. The very quickly responding turbocharger and the very narrow intake and exhaust cams, together with intake camshaft adjuster, are also responsible for making 80 percent of the 200 Newton-meter maximum torque available at a low 1,250 rpm. The refined flow optimization of the integral exhaust manifold and a very carefully optimized exhaust turbine also deliver excellent, low-loss charger operation, even at high speeds. The maximum speed of the turbocharger is 220,000 rpm. Integrated directly in the compressor housing of the charger is the electrically-controlled divert-air valve. Its advantage compared to a pneumatic valve: Its construction is more compact and less complex. In addition, it produces significantly shorter switching response times, so that the turbocharger always operates optimally, even with abrupt throttle adjustments. An electrically-controlled divert-air valve was introduced for the first time on the turbo engine on the current Golf GTI. 
An innovation on the new TSI is its water-flow intercooler, which is positioned right in the intake port. It is part of a low-temperature circulation loop that is independent of engine cooling. The advantage here: The charge air system exhibits a lower volume than in conventional approaches that use a front intercooler. Numerically speaking, it was possible to reduce the volume from about 11.0 to 4.8 liters. This significantly shortens the time required to reach a charge pressure of 1,800 millibar in the intake port. The results: Improved dynamics due to minimal delays in filling the combustion chamber to its maximum. And the driver of a Volkswagen equipped with the 122-PS TSI can experience this dynamic gain.
Latest developments: They never stopped refining their TSI technology. Some of their latest ideas for the 1.4 122 PS  include: More ways to save weight. These range from a lightened cylinder head cover and a weight saving per camshaft to the refined design of the cylinder head itself. A new injector with six fuel bores for electronic direct injection helps achieve this. The injector jets have been realigned to give more efficient distribution of the fuel mixture in the combustion chamber.  
Supercharger boosts pressure at low end: To increase torque at low engine speeds, engine developers selected a supercharger that is mechanically-driven by a belt. This charger is based on the Roots principle. A special feature of the supercharger being used is its internal gearing stage located in front of the synchronization gear pair, which enables high supercharger boost performance at low engine speeds. 
Turbocharger kicks in at the upper end: At higher engine speeds the turbocharger (with wastegate control) kicks in. The supercharger and turbocharger are arranged in series here. The supercharger is actuated by a magnetic clutch integrated in a module within the water pump. A control flap ensures that the necessary fresh air is supplied to the turbocharger or supercharger for the given operating point. In pure turbocharger operation the control flap is open. The air then takes the route of conventional turbo engines, via the front intercooler and throttle valve and into the intake port. The maximum charge pressure of the twincharger is approx. 2.5 bar at 1,500 rpm. Only in the lower speed range below 2,400 rpm is the supercharger needed to generate the necessary charge pressure. The turbocharger is designed for optimal efficiency in the upper performance range, and it also supplies sufficient charge pressure in the middle speed range.

Charge-Air Intercooling  
The turbocharger has a water-cooled intercooler with a low-temperature circuit independent of the engine cooling system. As a result we've cut the volume of the charge air system by more  than  half,  allowing  a  high  charge  pressure  to  build  up much more  quickly.  This gives improved dynamics because it reduces the time it takes to achieve maximum charge in the combustion chambers.  
The first car in the world to have TSI on board was the Golf GT. The 125 kW / 170 PS power and 240 Newton-meters of torque on this small brother of the Golf GTI contrast with a low 7.2 liters per 100 kilometers average fuel consumption. This sporty Golf races to the 100 km/h mark from a standstill in just 7.9 seconds. And at 220 km/h it has reached its top speed. Standard equipment on the Golf GT includes a six-speed transmission, but available as an option on this Volkswagen too is the technically unique DSG dual clutch transmission. 
Meanwhile, the large TSIs paired with DSG are not just reserved for the Golf; the engine and transmission are available today on the Golf Plus, Golf Variant, Jetta and Touran too. Representing the technical foundation of the TSI on the new, small TSI with 90 kW, for example is a 1,390 cm 3 displacement four-cylinder engine, whose dynamics, in the case of the GT, match those of a 2.5-liter naturally aspirated engine. 
The TSI already develops its maximum torque at 1,750 rpm, which is then constantly in reserve up to 4,500 rpm. The second TSI is the engine version debuting in 2006 on the Golf, Jetta and Touran with 103 kW / 140 PS. TSI stands for a new type of downsizing: For less displacement, less fuel consumption, lower emissions, yet more power, more torque and more driving fun. The 140-PS TSI develops 220 Newton-meter torque at a low 1,500 rpm and holds this value constant up to 4,000 rpm. To ensure that driving fun is not spoiled when refueling, all TSI engines are designed to operate with economical, super 95 ROZ fuel. 

Advanced Injection Technology 
Electronic direct injection is marked by a newly developed high-pressure injection valve with six fuel spray holes. Background: A multi-hole high-pressure injection valve of this type was first used on the large TSI engines. However, on the small TSI the spray behavior was significantly modified. The fuel mixture is distributed more efficiently in the combustion chamber thanks to a new design of the six injection jets adapted to the specific needs of this engine. This enabled ignition timing adjustment, and one result was significantly lower HC emissions (hydrocarbons). The injector itself is arranged on the intake side between the intake port and the cylinder head gasket level; the maximum injection pressure is 110 bar. 

Their acclaimed Direct Shift Gearbox (DSG) has two clutches with electronically controlled gear selection. DSG gives: Fast, smooth gear changes; lively handling with unbroken acceleration; Safer driving with the power to get you out of tricky situations; Improved fuel economy, even compared to a manual gearbox, for many of their new 7-speed DSG ‘boxes.

DSG is a groundbreaking 'two-in-one' concept. Available in 6-speed and 7-speed versions, it's totally unlike a conventional automatic transmission.  Twin electronically controlled shafts manage gear selection, always anticipating your next shift.  When one turn the engine on and select Drive mode, one shaft selects first gear while the second shaft puts the next gear on 'standby'. As the gearbox changes to second, the second shaft is engaged and the original shaft reaches third. As you shift upwards the sequence continues in a series of seamless moves. 
Because power is  simply  switched  from one  shaft  to  another, not only  are  gearshifts  silky  smooth, but  they  are  also  very  fast: each change takes  less than  four-hundredths of a second. The DSG gearbox gives a choice of two driving programmes: normal and sport.  In sport mode, the DSG leaves it longer to shift up the gears. And if one wants to take over, he/she can control the DSG manually. Nudge the Tiptronic gearlever forwards or backwards to change gear, or use the paddle shifts mounted on the steering wheel: left for down, right for up. Both DSG gearboxes are application-specific. The 6-speed is paired with high torque engines (up to 350 Nm) while the 7-speed variant is more effective in combination with smaller engines and torque outputs of up to 250 Nm.  

The Technology:  
The 6 speed DSG gearbox is made up of two independent gearbox units. With dual-clutch technology - two clutches in a common housing - both gearboxes are connected under load to the engine in turn, depending on the current gear, via two drive shafts. Clutch 1 serves the first gearbox unit with 1st, 3rd, 5th 7th and reverse gear and clutch 2 the second gearbox unit with 2nd, 4th and 6th gear. An output shaft that applies the torque to the driven wheels via the differential gear is assigned to each gearbox unit.   Thanks  to  the  dual-clutch  design  the DSG  is more  efficient  than  conventional automatic transmission. This efficiency, together with its low weight and intelligent control, means that DSG can achieve the same, and in some instances better, fuel consumption, than a manual gearbox or even lower, depending on the style of driving. 

Electronics and mechanics in one unit.  Clutches  and  gearbox  units  are  operated  hydraulically  by  the gearbox mechatronics  (a  combination  of mechanics  and  electronics)  housed  in  the DSG.  The electronic transmission control unit, sensors and hydraulic control unit form one compact unit. 
The control unit does the thinking for you, using information such as engine speed, road speed, and accelerator position and driving mode to select the optimum gear and to determine the ideal shift point.  The  hydraulic  control  unit  then  implements  the  shift  commands  in  a  sequence  of precisely  co-ordinated  actions. 
Split-second  gear  changes:  When  one  gear  is  engaged,  another  gear  is  always preselected. Within four hundredths of a second after the system detects a gear change it opens one clutch and closes the other. The mechatronics unit ensures that this takes place fast and to a level of accuracy that would not be possible in a manual transmission. The change of gear is imperceptible to the driver who is merely conscious of the uninterrupted power.

DSG 7-Speed Gearbox
The new 7-speed DSG gearbox is a world first. What makes it so innovative  is its pair of dry  clutches  which  have  dispensed  with  the  need  for  the  oil  bath  of  conventional  ‘wet’  clutches.  They have been designed to improve fuel efficiency and driving agility further. The clutches' dry, organic-bonded friction linings need no cooling. The gearbox is also very compact and requires less power for the gear selection and clutch servo system. Ideal for motorway  driving.  Adopting  7  speeds meant  our  engineers  could  lower  1st  gear  to  improve  acceleration  from standstill and raise 7th gear to act as an overdrive function, ideal for motorway driving. This can save fuel, cut emissions, and means the car runs even more quietly. 

The recently developed dual clutch is one of the most radical developments which helped make the DSG such a ground breaking innovation. Being a dry clutch its not only better in terms of performance but is much lighter than its earlier counterpart. Figure 4 shows a cutaway diagram of the dual clutch used in the 7 speed DSG gearbox. Besides core power train and drivetrain components Volkswagen has also made improvement in other peripheral equipments related to the car as explained below. Inorder to make the car better not only in the field of performance but also helping it become more eco friendly.

Driving  in  towns  involves  a  lot of stopping  and  starting, waiting  in queues or  at  traffic  lights. And while the engine is ticking over, it’s using fuel. VW’s efficient  Start/Stop  technology,  introduced  on  the  Passat  BlueMotion,  stops  this  waste,  cutting  CO2  emissions  and saving fuel. The Start/Stop system means that the car can virtually stop its engine by itself. It works through the clutch, so when  the car  come  to  a  standstill,  one has to   just  select  neutral  gear,  release  the  clutch  and  the  engine  switches  off  with  a Start/Stop symbol appearing on the dashboard. When he/she wants to move off again he/she has to simply dip the clutch, the engine restarts and you can select first gear and pull away. The system can easily be deactivated, if one wishes, by a switch within easy reach.

When one is trying to save energy while driving it makes sense to recover it where one can. VW uses improved alternators and batteries in combination with an energy management system, to store kinetic energy that would normally be lost during slowing down or braking. The un-utilized alternator voltage during slowing down or braking  is  used  to  add  extra  charge  to  the  battery  during  this  period.  This  extra  battery  charge  can  then  be  utilised during acceleration or starting,  instead of drawing all the energy  from the alternator, thus placing  less of a burden on the engine and reducing fuel consumption. Recuperation is a feature of some of our BlueMotion cars. Along with it the car is fitted with low rolling resistance tyres. They need less engine power to move the car forward, saving fuel  and  helping  to  cut  emissions,  while  still  offering  excellent  performance.

Manual gearboxes with optimised gear ratios are another way of saving fuel. The longer gear ratios for the higher gears reduce consumption. The lower engine speed also cuts noise - both for those in the car and those outside it. Fuel saving also depends on how the car is driven and some BlueMotion models are fitted with a system that indicates a recommended gear, giving one the opportunity to adjust your driving style for greater economy.  According to the driving situation, the intelligent engine management recommends the most efficient gear in the multifunction display. An arrow pointing upwards tells you to move up a gear, and an arrow pointing down recommends a lower gear. If the gear already selected is the best one for the current speed, a dot appears.

The smoother the airflow over your car as it goes forward, the less drag there is holding it back and the less effort is needed to move the car forward. That means better performance and lower fuel consumption. That's why VW constantly optimises the aerodynamics of the cars they manufacture by:
The body is more steamlined and gaps between panels are narrower. 
Headlights and indicators are combined. 
Radiator grilles, underbody panels and spoilers are designed to reduce drag.
A very slight change in the drag coefficient of a car can help alter the performance of the car significantly, especially when travelling at high speeds on the highway most of the power produced by the cars goes on to overcoming the aerodynamic drag so it becomes essential to optimize the aerodynamic performance of the car in order to make it efficient at high speeds.the greater the speed the greater will be the affect of aerodynamics on the cars performance for example the worlds fastest car Bugati Veyron has a 1000bhp engine, out of which 250bhp is enough to propel the car to a speed of 300kmph but for the remaining 100 odd Km/H it requires the extra 750bhp. A comparison between the coefficients of drag of different Bluemotion cars and the normal cars shows the improved aerodynamics of these cars. In table 3 there is a comparison between the Cd values of different car models.

With the increase in number of vehicles on road it is becoming much important that we make them cleaner and greener. All the bluemotion technologies together increase the efficiency of an ordinary diesel engine from 38% to about 43% and of a petrol engine from 32% to 36%.
From the graph above its evident that a little change today can mean a much better tomorrow so these small changes can help in contributing a lot to the future generation. Proper, timely maintenance is essential to make the car efficient throughout its life, a VW study suggested that proper timely maintenance of simple things like tyre pressure, engine oil, etc can help save the fuel and thus reduce the emissions.

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