TDI (engine technology)
TDI (abbreviation for Turbocharged Direct Injection or Turbocharged Diesel Injection) is the brand name for diesel engines from the Volkswagen automotive group . These engines have direct injection and a turbocharger . The TDI engine family is installed in vehicles of the Volkswagen , Audi , Seat and Škoda brands . They were also used in the earlier VW-Ford joint project Ford Galaxy and the Volvo 850 TDI. Other users were Mitsubishi ( Grandis and Lancer ) and Chrysler (among others in the Sebring ).
In contrast, the diesel engines offered by Volkswagen under the acronym SDI also work with direct injection, but without turbocharging ( naturally aspirated diesel ). The technical equivalent of the TDI for gasoline engines is called TSI .
features
The cylinders of the TDI engines have no prechambers or vortex chambers ; the glow plugs are arranged in the combustion chamber, which is located in a mostly circular depression in the piston crown. The smaller combustion chamber surface in comparison to the prechamber / vortex chamber engine enables lower heat losses and thus better efficiency; In addition, there is no throttled (lossy) overflow from the pre- or vortex chambers into the cylinder. This is why these engines have particularly low consumption. The principle requires steeper pressure rises and thus significantly louder engine noise. In general, all turbodiesel engines have a certain starting weakness that is due to the turbocharger's charging boost that does not start immediately. This property, known as turbo lag , is noticeable between the engine idling speed of almost 1000 min −1 and the effect of the turbocharger at around 1300 min −1 engine speed. The TDI engines, the maximum torque is usually about 1,800 to 2,200 min -1 achieved.
origin
The Volkswagen Group's TDI engines go back to a development by Richard van Basshuysen , who implemented the TDI engine against resistance in the Volkswagen Group. The engine with direct injection and turbocharging had a 20% lower consumption than the previous engine with indirect injection and was additionally equipped with an oxidation catalytic converter for exhaust gas detoxification.
First generation TDI with distributor injection pump
After the Fiat Croma 2000 Turbo D id (1986) and the Austin Montego MDi (1988), the Audi 100 2.5 TDI presented at the 1989 IAA was the world's third car with direct diesel injection. The Audi five-cylinder diesel engine was based on the Audi / VW four-cylinder type 827 engine used for the first time in the Audi 80 in 1972 . The first swirl chamber diesel engine for the VW Golf was created on this basis in 1976 . The engine of the first Audi 100 TDI has an output of 88 kW (120 hp). The maximum torque of 265 Nm is already from 2250 min -1 to. The vehicle reaches a top speed of approx. 200 km / h and consumes almost 6 liters per 100 km according to DIN 70030. The first TDI engines had an electronically controlled distributor injection pump from Bosch (VP36 or VP37, axial piston distributor injection pumps). They inject at a pressure of up to 950 bar at nominal output. The Audi 80 followed in 1991 with a slightly smaller 1.9-liter four-cylinder engine with an output of 66 kW (90 hp) and 182 Nm maximum torque.
In 1993, the first Golf III TDI with a largely identical 1.9-liter engine, also with an output of 66 kW, came onto the market. The problem with the first TDIs was, on the one hand, the still hard running behavior. The TDI in the Golf III was therefore only ready for series production with a long delay, as the possibilities for soundproofing in its relatively small engine compartment are much less favorable. In addition, the efficiency of around 38%, which was very good for the time, resulted in low and late cooling water heating. Therefore, the winter operating properties, in particular the effect of the interior heating and thus the defrosting of the windows, were unsatisfactory. In order to still be able to cope with winter conditions, an electrical heating element was integrated in the cooling water duct. This so-called " auxiliary heater " in the supply line to the heating cooler accelerates the heating of the cooling water and the heating air. The alternative is a diesel-powered heating device on the Audi TDI. Word got around very quickly that this additional equipment from Eberspächer could be expanded into a fully-fledged parking heater with little effort.
Even the first generation of TDI engines were targets of chip tuning that often overwhelmed the engine mechanics. That is why VW and Audi later brought more powerful versions onto the market. In 1996 came the 81 kW TDI (recognizable by the red I). This not only has a different engine software, but also stronger connecting rods and pistons . This engine, installed for the first time in the Audi A4 B5, was the first series car engine with an efficiency of over 40%. In addition, a six-cylinder V-engine with distributor pump (radial piston distributor injection pump) was on offer for years.
Second generation TDI with pump-nozzle technology
The first vehicles with pump-nozzle technology ( VW EA188 ) came onto the market in 1998 in what was then the VW Passat (3B5). These vehicles do not have a separate injection pump. This was replaced by a cylinder-piston element, which is combined with the injection nozzle to form one component, the pump-nozzle element. It sits in the cylinder head. There is no pressure line between the pump and nozzle. The camshaft exerts force on the pump nozzle with a third cam per cylinder (between those for the intake and exhaust valves) so that it builds up fuel pressure.
This system is already known from the commercial vehicle industry. Pump-nozzle engines operate at nominal power with a pressure of up to 2050 bar, which for a long time was the highest possible pressure in passenger car diesel engine construction. The efficiency and consumption values improved accordingly. The three-liter Lupo from VW and the one-liter vehicle are equipped with such a system. The efficiency of these engines is 45% in a three-liter car. VW hoped for the big breakthrough from this technology, but it did not succeed because the system requires very tight manufacturing tolerances. Such a motor is correspondingly expensive. However, since the Volkswagen Group also sells many company vehicles, the pump-nozzle technology meant a certain competitive advantage due to the lower consumption, which then led to the spread of the technology. This type of engine was gradually phased out by 2010.
From 2000 the TDI engine with 96 kW was introduced in the VW Group: among others in the VW Passat (2000) and Golf (2001), Audi A3 (2000), A4 (2000), and A6 (2001) as well as Škoda Superb ( 2001). In 2001 this TDI variant was used in the VW Sharan with 96 kW and 110 kW. Six months later, these engine versions followed in other models such as: Škoda Fabia RS, Octavia, VW Polo, Seat Leon and Ibiza. As of 2005, a TDI engine was exclusively in the Ibiza Cupra, with 1.9 liter displacement and 118 kW at 3750 min -1 offered. The maximum torque was 330 Nm at 1900 min -1 .
With the Touran and the Golf V (2003), the newer generation of the TDI came out with a displacement of 2 liters ( 2.0 TDI ). At that time it was only available with 100 kW (136 hp) and a short time later 103 kW (140 hp). As long as it was not equipped with a diesel particulate filter (DPF), this engine had 16 valves instead of the usual eight. This 2.0 TDI is now available in a performance-enhanced version with 125 kW (here with 16 valves) and is offered, for example, in the Golf V GT , Audi A3 and Seat Leon FR TDI . This no longer develops its maximum power at 4000 min −1 , but at 4200 min −1 .
Third generation TDI with common rail technology
Third generation TDIs ( VW EA189 ) have direct common rail injection . Here a constant high pressure is generated in a common line (rail) and the injection timing is controlled by solenoid valves. In 1999 a V8 diesel engine in the Audi A8 was equipped with this technology. Here, a high level of comfort spoke against a pump-nozzle injection system. Ultimately, common rail injection, which was first introduced by Fiat in 1997 in the Alfa Romeo 156 , proved to be more cost-effective, more comfortable and technically superior. The first four-cylinder engines with common rail for passenger cars in the Volkswagen Group were launched in 2007 in the Audi A4 and VW Tiguan . The Audi A6, the Phaeton and the Touareg have been equipped with a common-rail V6 engine since 2004, marking the start of the departure from pump-nozzle technology at Volkswagen. The next model, the Passat, was converted to the new technology from February 2008 . The VW LT was also offered with a common rail engine from 2002.
VW, the largest supplier of pump-nozzle vehicles, has now withdrawn from this technology for several reasons, with the four-cylinder engines recently being converted:
- In 2007, the controllable injection pressures of common rail systems (CR) reached the pump-nozzle level (PD) with pressures of 2000 to 2200 bar
- With its independent pump, the CR can inject multiple times at full pressure at any time, while PD is dependent on the camshaft contour, which is particularly disadvantageous for pre-injection (smooth running) and post-injection (regeneration of diesel particulate filter)
- The system costs of PD increase more with the number of cylinders than with CR
- Due to the widespread use of CR, including in competitor cars, the system costs may fall further in the future than with the VW-exclusive PD
In general, common rail systems are more simple and have a few components. In principle, they are similar to an L-Jetronic gasoline injection system from the 1980s.
Meaning of the colored letters in the TDI logo
The VW TDI engines have specially designed type lettering. Starting in 1996, a variant of the 66 kW (1Z, AHU, ALE) of the first generation with an increased output to 81 kW (engine codes AFN and ASV) was produced. It had a turbocharger with adjustable tubine guide vanes ( VTG ), different engine software and reinforced connecting rod bearings (sputter bearings). These vehicles were provided with a "red I" in the lettering. The pump-nozzle motors with red "D" and "I" were added later, first with 85 kW, later with 96 kW, then in the Golf IV also with 110 kW. On the Golf IV with 110 kW (code letter including ARL), completely red lettering was used. The smaller pump-nozzle motors with 85 kW, 96 kW and initially also 74 kW had a silver “T” and the letters “DI” in red in the type designation. After the VPE motors were discontinued in the 2003 model year, the 74 kW AXR only got a red "I", as there was no longer any risk of confusion with the 110 HP motor and the 74 and 96 kW motors can now finally be distinguished externally were.
It is therefore only possible to draw conclusions about the engine from the lettering if the model year is known. The “blue I” can often be seen on vans and indicates a particularly economical and small TDI without intercooler. A green “DI” can be found on the three-liter Lupo .
The Seat Leon 1M had the Topsport (TS) model, which was later renamed Formula Racing (FR). In the 110 kW engine, these also have a completely red TDI.
TDI brand
“TDI” is a registered trademark that has been registered in Germany for Audi AG since August 9, 1995 at the German Patent and Trademark Office in Nice Classification 12 (engines for land vehicles) and later as a word-image trademark in various combinations was registered for Volkswagen AG. According to a decision by the EU court , it is not a trademark, but a "technical abbreviation" and can therefore not be registered as a uniform trademark throughout Europe.
Web links
- Engine code and data table for TDI engines
- Presentation 2.0l TDI engine with common rail injection system from Volkswagen (PDF; 691 kB) by Jan-Christian Rehder, Laboratory for Piston Engines & Internal Combustion Engines at the University of Applied Sciences, Hamburg, as of January 5, 2011
Individual evidence
- ↑ Richard van Basshuysen (Ed.): Otto engine with direct injection - process · systems · development · potential , 3rd edition, Springer Vieweg, Wiesbaden, 2013, ISBN 9783658014087 , p. 7
- ↑ Register no. 39506096
- ↑ RegNr. 39540006
- ↑ RegNr. 39540031