Doc: Audi A1 Concept

[Mehen]

Thoughts?

http://www.fourtitude.com/news/publish/Audi_News/article_4350.shtml

Audi is presenting another version of the innovative hybrid technology in the drive unit for the A1 Sportback concept. At work under the hood is a 1.4-litre TFSI engine developing 110 kW (150 hp), whose power is directed to the front wheels by means of the S tronic dual-clutch transmission. A 20 kW (27 hp) electric motor integrated in the drive train is able to deliver up to an additional 150 Nm of torque (110.63 lb-ft) when the vehicle is accelerating. During the boosting phase, i.e. when the TFSI engine and electric motor operate simultaneously to enable a sporty driving style, the two power packs deliver impressive propulsion. The tried-and-tested front-wheel drive – supplemented by the newly developed, ESP-controlled active front differential lock – ensures optimum transfer of power to the road.

The electric motor is furthermore capable of powering the vehicle alone for zero-emission driving in residential areas, for instance. The capacity of the lithium-ion batteries gives the vehicle a range of up to 100 km (62.14 miles) in pure electric mode; the motor can be recharged from any power socket. The automatic start/stop facility, energy regeneration and phases of purely electrical operation reduce the fuel consumption and emissions of the Audi A1 Sportback concept by almost 30 percent compared to when it is running on the combustion engine alone. Despite its sporty performance, with acceleration of 0 to 100 km/h (62.14 mph) in 7.9 seconds and a top speed of 200 km/h (124.27 mph), the Audi A1 Sportback concept requires only 3.9 liters of premium fuel per 100 km (60.31 US mpg); CO2 emissions are an efficient 92 g/km (148.06 g/mile).

[Dr Mordrid]

Very nice looking crossover.

It uses a system similar to the Peugeot Prologue HYmotion4 (latest of a series): FWD using an ICE and rear drive using electric, though the Peugeot uses in-wheel motors at the rear and not a single motor with split shafts.

My problem with such an arrangement is that it keeps the transmission and other mechanical drive components, meaning a lot of weight is retained unnecessarily, which can be a big deal in a passenger car, crossover or minivan. IMO 'tis better to go with a series hybrid (like the Volt or Chrysler systems) to lighten up the vehicle for these.

Keeping the heavy components makes sense for the GM/Chrysler/BMW/Daimler two-mode hybrid system as it allows the use high-powered gas and diesel engines for towing etc., which a passenger car just doesn't really need. All two-modes put the electric motors in the transmission, making for a lighter total assembly. NO other hybrid system can handle the power the two-mode can. GM's version uses two 60 kW electric motors in the tranny.

[Brian Ellis]

At least it IS a hybrid, with two drive systems to the wheels, which the VOLT concept is NOT, as only electric power drives it.

An inboard or two inboard motors with half-shafts makes more sense than in-wheel motors because the unsprung weight of the latter will make for poor suspension and road-holding.

Your argument about transmission weight does not apply to the HCH which does not have a gearbox but a CVT which weighs only about 1/3 of a manual and 1/4 of an automatic transmission. To anyone brought up on manual gearboxes, the CVT is disconcerting at first, when you see the rev counter doing acrobatics. All electronically controlled, of course! OYOH, the weight advantage of the CVT in a Prius is countered by the complex epicyclic transmission to distribute the power from each source to the wheels.

[Dr Mordrid]

Sorry Brian, but the Volt is a hybrid too - just a different kind than the Prius you're used to. Some are suited to or designed for plug-in charging for pure electric drive and others aren't without modification, but all are recognized as hybrids on this side of the pond by environmentalists, auto engineers and governments.

Parallel is a simpler system previously used in the Insight, Civic and Accord among others. Because of how power is distributed they get more "hybrid benefit" on the highway than in city driving, which is IMO why some of them failed in the market - most people expect the benefit in their daily city driving.

In a Series Hybrid the ICE drives a generator instead of directly driving the wheels. The generator both charges a battery and powers an electric motor that powers the wheels. Volt is a subtype of Series Hybrid known as a range extended electric vehicle, REEV, which GM has named E-REV - extended range electric vehicle - for marketing purposes. E-REV/REEV's are plug-in's by nature and adding a large battery gives you an extended no-fuel operational mode, as in Volt.

Oh....Volt has no tranny - geared or CVT.

Series Hybrids can also be made without extended range capability, and will likely be so once fuel cells or other high power systems come on line. GM (and very likely Chrysler) is ready for this as the Volt/E-Flex system is highly modular - eliminate the range extender engine/generator and drop in a fuel cell/EESTOR ESU/whatever and save for re-programming the controller and using a smaller or no LiION battery the rest of the car won't know the difference. That's what the "Flex" in E-Flex is all about- planning for their 2020 vehicles and preparing the design infrastructure for their needs.

Prius is a subtype of Combined Hybrid (AKA Series-Parallel) known as an Input-Split Hybrid. You know how it works so I won't say much other than beware the low efficiency of the electric power path vs. the mechanical - not good especially at higher speeds.

Two-mode differs from the Input-Split by of the addition of a second planetary gearset and 4 clutches (which can actually operate as one). This enables the switching (two-modes) of the percentage of mechanically vs. electrically transmitted power to cope both with both high and low speeds while the 4 fixed gears allow it to function like a conventional parallel hybrid under high power, such as high speed or during towing. Full electric boost is available in the fixed-gear modes. It's also the only hybrid system so far that can handle high powered gasoline or diesel engines in heavy vehicles like SUV's, pickups or other heavy vehicles.

A lighter version of GM's Two-Mode will be in the 2009 Saturn Vue Green Line mini-SUV with plug-in capability and a no-gas range of 10+ miles. Might not sound like much, but for someone like my wife who drives about 2 miles to work but still needs a longer range if she needs to go shopping, to the kids houses, the Dr. or to her mothers after work....

The military is showing interest in both the Two-Mode and straight diesel-electric for powering light armor, cargo and light vehicles. The Aggressor is an example - a diesel electric "jeep", for lack of a better term.