Volkswagen small car prospects picking Up

  • 20-Dec-2011 04:00 EST
VW11-11 Up cutaway.jpg

Revealing image of the production VW Up: mainly for reasons of cost and economies of scale, the radical rear-engined, rear-drive 2007 concept design gave way to a conventional front-engine, front-drive configuration early in the program.

Pragmatism is a word that dominates almost the entire auto industry—particularly when applied to high-volume production. Volkswagen’s new Up (VW adds an exclamation mark (up!) and uses lower case in its designation) is a classic example. When first shown at the 2007 Frankfurt Motor Show, it promised a step-change in city car design, with an engine mounted horizontally beneath the rear seat, and it used an entirely new platform. The configuration had echoes of the original Beetle.

VW Chief Designer Walter de Silva said at the time that the rear engine configuration changed everything: space, mood, and design, adding: “Absolute harmony of the basic technological concept and the emotional aspects of the design can only be achieved in a hard clash of ideas between engineers and designers.”

That clash has been a “win some, lose some” business, and the upshot is that the production version of the Up looks much as it did in concept form, but the engine is now traditionally positioned at the front. It could be interpreted as a 1-1 draw between designers vs. engineers. But in reality it needs to be seen as a pragmatic acceptance by both sides of the realities of component and systems sharing.

Gunnar Wagner, Technical Project Manager for the Up, said: “During development it was found that more potential could be achieved for the car if we put the engine in the front. That production powertrain (1.0-L, three-cylinder, all-aluminum block, open deck without a balancer shaft) could be used in other applications including the Polo. But a rear-mounted powertrain would have been unique to the Up. This is the first of a generation of engines. It is possible to produce it with four cylinders and build both versions down the same production line.”

The 1.0-L engine, designated EA211, resulted from a very extensive NVH program that included integrated calculations based on both the power unit and gearbox. Transmission choice is a five-speed manual (MQ100) having a mass of just 25 kg (55 lb) including transmission fluid or five-speed robotized manual (SQ100) at just under 30 kg (66 lb) with D, N, and R selection and manual shifting when required. Both were assessed together with the engine before components were optimized. An interesting detail that emerged during the car’s development program was that the auto made twice as many shifts as the manual.

The engine is initially available with outputs of 44 and 55 kW (60 and 74 hp). The best fuel consumption is for the BlueMotion-technology-equipped Up with 44 kW, stop/start, and brake energy regeneration at 4.2 L/100 km. A compressed natural gas (CNG) version will have a 50-kW (67-hp) output and emit only 79 g/km of CO2.

Although described by VW as being all-new, the three-cylinder engine does have a minor link with the company’s established four-cylinder (EA111) unit in the use of 82-mm (3.23-in) cylinder spacing. Bore and stroke are 74.5 and 76.4 mm (2.93 and 3.01 in). Gasoline engines have a 10.5:1 compression ratio; the natural gas has 11.5:1.

The CNG version of the Up has two underfloor gas tanks of 34.5 and 37.5 L (1.22 and 1.32 ft³), respectively, positioned close to the rear axle, one just ahead of the axle abutting a 10-L (2.6-gal) reserve gasoline tank, while the second is positioned in the spare wheel recess.

The engine’s downward guided conrods and the pistons are claimed by VW to be so successfully weight-optimized that no balancer shaft is needed and that there is no sacrifice of NVH quality.

In fact, minimizing NVH throughout the car was a particular target for the Up team. For the concept, space was set aside in the area of the engine bulkhead for what VW terms “relatively expensive” firewall insulation. But for the production car, a molded part was substituted for a stamped, lightweight type. VW also applied careful tuning of structural damping as it interacts with other acoustic elements, and particular focus was placed on sealing of the body to minimize ingress of noise into the cabin, which in turned has reduced the need for sound deadening materials, saving weight and cost over the car's service life.

The cylinder is cast in aluminum alloy with four valves per cylinder and has an integrated exhaust manifold, and the crankshaft has six counterweights that help reduce internal forces. Toothed belts drive the new engine’s two overhead camshafts, the intake is variable, and the valves activated by low-friction cam followers.

A pure electric Up will be in production in 2013. VW is also researching—probably initially as a technology demonstrator—a two-cylinder diesel example of the car. No formal statement has been made, but it would probably be the basis of a plug-in hybrid system very similar to that in the VW XL1, which is also due for production in 2013.

The Up’s packaging remains a strong point, with room for four adults thanks to its wheel-at-each-corner design. The body has minimal 585-mm (23.0-in) front and 535-mm (21.1-in) rear overhangs in a vehicle that is 3540 mm (139.4 in) long. Its 1641-mm (64.6-in) width without mirrors is only 10 mm (0.4 in) wider than the concept's. Other specs include a 1478-mm (58.2-in) height, 2420-mm (95.3-in) wheelbase, and luggage volume that spans 251 L (8.9 ft³) with the rear seats in place and 951 L (33.6 ft³) with them folded.

A significant safety element is the fitment of a laser-based City Emergency Braking system operating at speeds from 5 to 30 km/h (3 to 19 mph). A sensor is integrated into the top of the windshield scanning 10 m (33 ft) ahead of the vehicle. If the driver fails to react sufficiently quickly in the event of an impending collision, maximum braking effort—a deceleration of 10 m/s²—is applied if necessary. The Up is claimed by VW to be the first car in its class worldwide to have such a system.

Chassis aspects include a subframe to which the single-shell transverse link is attached. It is designed to absorb forces of the stabilizer bar which is joined directly to the MacPherson strut tower plus the (electromechanical) steering unit and swivel mount of the engine bearer. The subframe uses high-strength steel of 1.8-mm (0.07-in) thickness to save weight. An optional sport suspension lowers the Up by 15 mm (0.6 in). Wheels are a choice of 14, 15, or 16 in.

The car is available with a maps+more portable touch-screen module. It includes a navigation system, hands-free Bluetooth, display of information about the vehicle, and a media player.

For its size, the Up has a very good Cd value of 0.32 and a CdxA of 0.67 m².

EU curb weight is 929 kg (2050 lb) for the 40-kW car, and torsional rigidity of the 270-kg (595-lb) bodyshell (complete with add-on parts) is 19,800 N·m (14,600 lb·ft) per degree. VW opted to use hot-formed steel for the front floorpan and B-pillar shells. The production process for the steel includes heating the blanks in a continuous furnace before quenching in a water-cooled press tool to gain a hardness of more than 1000 MPa (145 ksi). Hot-formed steel makes up 8.1% of overall bodyshell weight.

Initially on sale as a three-door, a five-door will come in 2012. Although the production Up is not the technological departure from the norm that the concept indicated and does not echo the Beetle’s rear-engine configuration, it is a car designed to achieve a huge production volume across the world.

Said VW Development boss, Dr. Ulrich Hackenberg: “Adapted and localized for regions like China, India, or South America, it absolutely has the potential to bring mobility to broad swathes of the (world’s) population. The Up can become our next icon.”

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