Direct-shift gearbox
A direct-shift gearbox is an electronically controlled, dual-clutch, multiple-shaft, automatic gearbox, in either a transaxle or traditional transmission layout, with automated clutch operation, and with fully-automatic or semi-manual gear selection. The first dual-clutch transmissions were derived from Porsche in-house development for the Porsche 962 in the 1980s.
In simple terms, a DSG automates two separate "manual" gearboxes contained within one housing and working as one unit. It was designed by BorgWarner and is licensed to the Volkswagen Group, with support by IAV GmbH. By using two independent clutches, a DSG can achieve faster shift times and eliminates the torque converter of a conventional epicyclic automatic transmission.
Overview
Transverse DSG
At the time of launch in 2003, it became the world's first automated dual-clutch transmission in a series-production car, in the German-market Volkswagen Golf Mk4 R32, and shortly afterwards worldwide, in the original Audi TT 3.2. and the 2004+ New Beetle TDI. For the first few years of production, this original DSG transmission was only available in transversely oriented front-engine, front-wheel-drive and Haldex Traction-based four-wheel-drive vehicle layouts. All transverse DSG have an internal code starting with DQ and are coupled to the engine via a dual-mass flywheel.DQ250
The first DSG transaxle that went into production for the Volkswagen Group mainstream marques had six forward speeds and used wet/submerged multi-plate clutch packs. It has been paired to engines with up to of torque. The two-wheel-drive version weighs. It is manufactured at Volkswagen Group's Kassel plant, with a daily production output of 1,500 units.
DQ200
At the start of 2008, another world-first seven-speed DSG transaxle became available. It differs from the six-speed DSG, in that it uses two single-plate dry clutches. This clutch pack was designed by LuK Clutch Systems, Gmbh. This seven-speed DSG is used in smaller front-wheel-drive cars with smaller-displacement engines with lower torque outputs, such as the Volkswagen Golf Mk6, Volkswagen Polo Mk5, and the new SEAT Ibiza. It has been paired to engines with up to. This new DQ200 uses just 1 litre of specialised DSG fluid for the hydraulics and 1.7 litres of gearbox oil. In contrast, the DSG gearboxes with wet clutches use 7 litres for both hydraulics and gearbox lubrication.
DQ200e
The DQ200e is a variation of the DQ200 transmission that first appeared in 2008 in the Golf V TwinDrive prototype. It is based on the standard DQ200, but modified to accommodate components of a hybrid system. The clutch housing was extended by 83 mm to allow space for an additional disengagement clutch, its hydraulics, and a hybrid module. This module was mounted between the crankshaft and the dual-mass flywheel, functioning as a motor-generator unit and starter.
The Golf V TwinDrive combined a pre-production version of the DQ200e with a 20–30 hp electric motor and a 2.0 PD TDI engine. This plug-in hybrid featured a 12 kWh lithium-ion battery for about 30-50 km of electric range. About twenty prototypes were produced and publicly tested in Lower Saxony, Germany. The diesel–hybrid pairing proved unsuccessful: the system was overly complex, cold-running diesels in start/stop traffic created emission issues, and reliability was poor. After two years the programme was halted in favour of a petrol-hybrid approach. The project was partially funded by the German Federal Ministry for the Environment under its Förderprogramm Elektromobilität.
In 2010 Volkswagen trialled the plug-in Golf VI TwinDrive prototype, pairing the DQ200e hybrid transmission with a 1.4 TSI petrol engine. As with the Golf V, it featured a 12 kWh lithium-ion battery for about 30-50 km of electric range. Around 20–30 cars were tested, leading to the production version introduced in the Volkswagen Jetta VI Hybrid.
The Jetta VI Hybrid appeared in 2013, using the EA211 1.4 TSI engine rated at 110 kW, combined with a 20 kW electric motor and a 1.1 kWh lithium-ion battery providing about 1–2 km of electric range. In contrast to the earlier TwinDrive models, it was not a plug-in hybrid. Sales remained limited, with total production estimated between 20,000 and 40,000 units worldwide, mainly in North America and China. Although conceptually close to the later Golf GTE, the use of the dry-clutch DQ200e limited durability, and the project was eventually superseded by the more powerful wet-clutch DQ400e system introduced in 2014.
DQ500
In September 2009, VW launched a new seven-speed DSG built to support up to, the DQ500. Like the DQ250, it features a wet multi-plate clutch pack. This gearbox premiered in the Transporter T5 2.0 TDI. It later became available in the Tiguan 2.0 TDI 4Motion, the BiTDI models of the VW Passat, VW Tiguan and Skoda Superb. It premiered in petrol-powered cars in the 2010 Audi TTRS 8J as a 7-speed S-Tronic gearbox. It later appeared in other top sports editions cars like the Arteon R and Tiguan R, coupled to a Magna torque-splitting rear differential to facilitate an all-wheel drive system. The two-wheel drive version weighs ; the four-wheel drive version is heavier.
DQ400e
Taking the concept of the DQ200e, the DQ250 was further developed into the DQ400e for the plug-in hybrid models of the VW Group. It debuted in July 2014 in the Golf mk7 GTE. It is combined with the 1.4 and later with 1.5 TSI engines. It is broadly used in the plug-in hybrids like the Golf GTE and Passat GTE, the Arteon, Tiguan and Transporter T7 e-Hybrid and the equivalent versions of the Audi A3 and Audi Q3, Seat Leon and Skoda Octavia and Superb iV. The electric motor is included in the DSG assembly, between the combustion engine and the gearbox. Unlike the DQ200e, the flywheel is mounted to the engine. There are a total of three clutches on this DSG: two connecting the engine to the gearbox and a disengagement clutch to connecting the electric drive to the engine.
As per VW Self Study Programme 538: The disengagement clutch K0 is engaged:
- When the electric drive motor V141 starts the combustion engine.
- When the vehicle is being driven by the combustion engine.
- When both power units drive the vehicle.
DQ380 and DQ381
The seven-speed DQ380 appeared in 2015 for the Chinese market, i.e. in the VW Golf and VW Magotan. It is based on the DQ500, sharing many of its mechanical and electrical components like the mechatronic. It is lighter and smaller, can handle torque up to 420Nm and is only available in front-wheel drive configuration. The DQ380 was produced in China. The addition of the seventh gear adds a 3gr/km of CO2 reduction compared to the DQ250.
The DQ380 was further developed into the DQ381, to meet the requirements of the European market. It was introduced in 2017 and replaces the outgoing DQ250 worldwide. It saves 5 to 10 gr/km of CO2 compared to the 0DE due to taller gearing, low friction bearings and seals and a new concept of its hydraulics. In contrary to the DQ380, which is front-wheel drive only, the DQ381 comes in both a front-wheel drive version DQ381-7F version and a DQ381-7A version, combined with a Haldex rear differential, to provide all-wheel drive. The only exception to this are cars with the electronic VAQ differential; these front-wheel drive cars employ an all-wheel drive gearbox casing and differential to facilitate the VAQ system.
Audi longitudinal DSG
In late 2008, an all-new seven-speed longitudinal S tronic version of the DSG transaxle went into series production. Initially, from early 2009, it is only used in certain Audi cars, and only with longitudinally mounted engines. Like the original six-speed DSG, it features a concentric dual wet multi-plate clutch. However, this particular variant uses notably more plates – the larger outer clutch uses 10 plates, whereas the smaller inner clutch uses 12 plates. Another notable change over the original transverse DSGs is the lubrication system – Audi now utilise two totally separate oil circuits. One oil circuit, consisting of, lubricates the hydraulic clutches and mechatronics with fully synthetic specialist automatic transmission fluid, whilst the other oil circuit lubricates the gear trains and front and centre differentials with of conventional hypoid gear oil. This dual circuit lubrication is aimed at increasing overall reliability, due to eliminating cross-contamination of debris and wear particles. It has a torque handling limit of up to, and engine power outputs of up to. It has a total mass, including all lubricants and the dual-mass flywheel of.This was initially available in their quattro all-wheel-drive variants, and is very similar to the new ZF Friedrichshafen-supplied Porsche Doppel-Kupplung.
List of DSG variants
Operational introduction
The internal combustion engine drives two clutch packs. The outer clutch pack drives gears 1, 3, 5, and reverse – the outer clutch pack has a larger diameter compared to the inner clutch, and can therefore handle greater torque loadings. The inner clutch pack drives gears 2, 4, and 6. Instead of a standard large dry single-plate clutch, each clutch pack for the six-speed DSG is a collection of four small wet interleaved clutch plates. Due to space constraints, the two clutch assemblies are concentric, and the shafts within the gearbox are hollow and also concentric. Because the alternate clutch pack's gear-sets can be pre-selected, un-powered time while shifting is avoided because the transmission of torque is simply switched from one clutch-pack to the other. While the DSG has one of the fastest shift times on the market, the claim that the DSG takes only about 8 milliseconds to upshift is un-proven with 3-party data nor claimed by the manufacturer.The variant of DSG fitted to plug-in hybrid vehicles also have a third clutch - its function is connect the electric motor to the combustion engine when both power sources are required simultaneously to propel the vehicle - it also is engaged to bump start the combustion engine from the electric motor whenever the transmission is in the "N" position - this is due to the engine not having a conventional starter motor.