As Director of Powertrain for the Volkswagen Group and Head of Development for the VW brand, Hans-Jakob Neusser is never short of new technology projects. To make the point, his company has revealed a list of innovations, many of which will enter production across VW’s broad model range. Spanning a new DSG (dual-clutch) transmission to an energy-saving infrared reflecting dashboard material, the developments underline the Group’s aim to become the world’s most sustainable car manufacturer by 2018, with emissions reduced by 25% in each of its business areas.
When VW Group Chairman Dr. Martin Winterkorn revealed in 2012 that the company was developing a 10-speed gearbox, he did not give any details; neither did Neusser earlier this year when he simply confirmed that it was a DSG: “We will stay with DSG technology, but we will improve it and we will have 10 gears!”
Now, VW has released those details, although some esoteric friction-reducing solutions remain to be fully revealed. The gearbox, which will eventually find applications in many models across the Group’s brands, is expected to enter production in 2016. It comes 11 years after VW’s first 6-speed DSG. So far, DSG production applications globally total 12 million units.
New 10-speed DSG
The new 10-speed is aimed specifically at transverse powertrain configurations via the VW Group’s increasingly ubiquitous modular MQB platform. Although still not officially confirmed, a variant may also be applied to longitudinal powertrains such as ones used by Audi. The new DSG’s torque limit is currently 550 N·m (406 lb·ft) but this may need to be increased as diesel engine power and torque levels rise. Even the latest 2.0-L bi-turbo with electric compressor already achieves 176 kW (236 hp) output and 500 N·m (367 lb·ft). (See http://articles.sae.org/13421/.)
Designated internally as DQ511, the 10-speed is closely based on the current 7-speed DSG (DQ500), which also has a 550-N·m peak torque capability.
The existing 7-speeds-plus-reverse gear cluster is retained but additional drive paths were created through the gearbox (via modification of the process of locking the gears to their shafts, or to each other) to achieve the required appropriately spaced 10 ratios.
For coasting (or “sailing” as the Germans call it) the gearbox is decoupled from the engine, which is automatically switched off by the power unit’s management system as the driver releases the accelerator pedal. A stop-start system has also been developed that operates when the vehicle is stationary and also when speed falls below 7 kph (4.3 mph).
Packaging was an essential design criterion for the new transmission. The unit had to be as compact as that of the 7-speed and should not bring the weight and cost penalties of a separate transfer case for all-wheel drive applications, engineers noted. And to help achieve VW's CO2 reduction targets, a “super overdrive” 10th high-ratio option was a must.
To meet the program's packaging and weight targets, VW’s transmissions team decided to reverse the power flow within the gearbox without using additional pairs of gearwheels. They achieved this by adding "two shifting elements and a reversing wheel"—part of the new configuration that facilitates the use of 10 progressively stepped gears.
As well as the ultra-high 10th gear, VW also went to the opposite extreme and shortened 1st and 2nd ratios to improve both low-speed creep and drive-away performance—each typically less than stellar without use of a torque converter. There is also an option for first gear to receive a super-low crawler ratio to suit specific on/off-road models.
VW engineers note that as a vehicle using the new gearbox accelerates, the “finely graduated” steps of 3rd through 9th gears enable efficiency gains. Further general efficiency improvements are achieved via friction reduction actions including special coatings on the gearwheels, lower friction bearings, and a “specially developed” transmission lubricant. Full details of each of these have yet to be revealed.
The new 10-speed gearbox is expected to achieve marked improvements to emissions and fuel consumption in the range of vehicles (not yet revealed) scheduled to use it.
IR-reflecting dashboard materials
Complementing the performance and economy advances of the new gearbox are clever material applications to new models, which VW plans to take into high production volumes.
The new lightweight hood of the Polo R WRC (World Rally Championship) repli-racer road car comprises a three-layer sandwich panel, a thermoplastic layer placed between two steel sheets. VW claims it reduces weight by 30% with no strength compromise compared to a conventional steel hood, and represents a further step towards greater emissions efficiency for high-volume vehicles.
Also in the pipeline is an infrared (IR) reflecting dashboard that helps negate the heat-absorbing effect of the use of dark-colored plastics necessary to reduce windshield reflections. VW is using specially developed metallic oxide pigmentation to dye the slush-molded skin of the dashboard (instead of the conventional dying technique that uses soot), to absorb UV (ultra-violet) light and NIR (near-IR).
According to VW, the pigmentation “largely” reflects the NIR to achieve what it describes as “significantly lower” temperature of the dashboard in strong sunlight. The effect of lower temperature takes some of the load off the air conditioning system compressor, thus reducing energy consumption—particularly useful for hybrids and EVs.
Complementing this is a new "Low-E" (low emissivity) glass sunroof which receives, via vapor deposition, a 400 nm (15.7 µin) film of indium oxide (alternatively, fluorine-doped tin oxide), to reflect long-wave IR but allow short-wave radiation (light) into the cabin.
Not only does it keep IR out in hot ambient conditions, but in cold it reflects body warmth of the cabin’s occupants, so reducing heat loss and also providing them with a perception of warmth, notably around their head and shoulders. The company claims that overall, the excess heat load (in warm weather) or heat demand (in cold weather) can be reduced by as much as 15% by using a Low-E glass sunroof. Again, this reduces air conditioning load and no sunshade is needed, another weight saving plus.
All this is particularly significant for EVs in winter and supports other energy saving systems. For example, the new e-Golf has a heat pump developed specifically for the car but which could be the basis for similar systems in other EVs. The e-Golf’s thermal system is sufficiently intelligent to know which seat is unoccupied, subsequently computing cabin heat requirements.
VW puts the heat pump’s efficiency at a level which cuts electric heating needs by around 50%, with a subsequent increase of driving range, depending on conditions, of up to 30%. The system is described as providing “optimal heating comfort.”
As a further aid to maximizing range (and reducing range anxiety, the Achilles heel of almost all pure EVs), VW is now developing tools that act as range managers and monitors. Integrated with intelligent GPS systems, these will analyze route, reported traffic conditions, environment (including weather) and the driving style being applied to the vehicle.
Driver displays show range potential, and flag up optimization choices—including reducing cabin heating levels.Continue reading »