REPORT CONTINUED The
REPORT CONTINUED The one-cylinder, 0.3-liter internal combustion engine supplies 26kW of power and is directly connected to the 30-kW Brusa generator. Photos: Swissauto Wenko AG The crankshaft (left) and camshafts of the 300-cc range extender engine are equipped with lowfriction roller bearings. Turbocharged reduced-displacement gasoline engines also have great potential for the future. The photo shows a c ombustion chamber test bench built by SWISSAUTO in collaboration with AVL. REX PROVIDES 800 KM RANGE The range extender directly addresses a weakness of electric vehicles. Although the battery’s 100 km range is enough to meet the average driver’s daily mobility needs on electric power alone, the vehicle must be capable of longer trips as well. When necessary, the SWISS- AUTO POLO REX uses the range extender to generate electric power for recharging its own batteries. “The SWISSAUTO team worked closely with the specialists at MOTOREX to minimize engine friction” The newly designed one-cylinder gasoline engine was engineered for maximum fuel efficiency right from the outset. This was primarily achieved by using roller bearings rather than slide bearings throughout and employing a special dry sump lubrication system to reduce friction. The SWISSAUTO team worked closely with the lubrication technology specialists at MOTO- REX to minimize engine friction. The SWISSAUTO engine consumes only the equivalent of about three liters of fuel per 100 km, fully meeting SWISS- AUTO’s goal of charging the batteries with a small and economical 26 kW (35 hp) range extender. This achievement is proof that the combustion engines used in today’s mass-market hybrid vehicles are still too large. The REX’s quick-filling 27-liter fuel tank gives it a total range of about 800 km and the car can accelerate its 1,245 kilograms from zero to 100 kph in just 8.5 seconds. HIGH EFFICIENCY, LOW EMISSIONS The extremely compact fuel injection intake manifold engine boasts an efficiency of 37%, which is astonishingly high for a gasoline engine. Its specific consumption values are comparable to those of a modern direct-injection engine. The mini-motor will also run on ethanol. This means that, depending on the source of electricity and fuel, the POLO REX can be operated on a completely CO 2 -neutral basis. The REX always runs on electric power; the range extender’s one-cylinder gasoline engine is used only to charge the batteries. This means that the combustion engine continuously runs within its optimum operating range. This clever design, with no constantly changing loads, yields outstanding engine efficiency. The combustion engine’s catalytic converter is also pre-heated after the electric motor starts. Once the converter has reached operating temperature, combustion can start and continue with low emissions from the first turn of the crankshaft. This feat of engineering lowers pollution emissions by as much as 80% compared to a conventional modern gasoline-powered passenger car! SWISS HIGH TECH IS IN DEMAND In conventional automotive engineering, Swiss precision is in especially high demand when it comes to safety and 12
Photo: BRUSA AG BRUSA Elektronik AG supplied the high-efficiency performance electronics for the POLO REX; testing on the electric motor test bed. Fredy Barth took the SWISSAUTO POLO REX for a test run for MOTOREX magazine and clearly enjoyed himself. dependability. Examples include components for highpressure fuel injection systems (common rail systems) in the latest generation of economical, low-emission diesel engines, safety features such as airbag igniters and ABS sensors, dependable locking systems, noise-muffling interior linings and corrosion-resistant chassis. A COMPACT BUNDLE OF INNOVATION The SWISSAUTO POLO REX combines a number of futuristic features. For once, the expression “high tech” is apt. The POLO REX offers • a full-featured, highly comfortable electric drivetrain • sophisticated engineering • extremely high efficiency • low emissions • everyday practicality In building the POLO REX, SWISSAUTO received support from the Swiss Federal Office for Energy and worked closely with Brusa Elektronik AG (www.brusa.biz). The Sennwald-based electronics company supplied the lithium polymer battery (135 kg), the electric motor and the power electronics. The POLO REX was converted, tuned and tested by SWISSAUTO (www.swissauto.com). Remarkable how Swiss inventors and manufacturers, after the many automotive achievements of the past hundred years, are now playing a pioneering role in alternative mobility technologies. • HOW THE POLO REX DRIVES Fredy Barth, racer (WTCC series, SEAT SWISS RACING Team) and test driver, drove the SWISSAUTO POLO REX exclusively for MOTOREX magazine. Fredy Barth: “It looks almost like a normal VW Polo, aside from the wheel covers, modified front end and rear spoiler. The SWISSAUTO POLO’s zippy performance compared to other alternative propulsion systems is an absolute highlight given its range. In D gear, the electric motor’s 50kW output sends it gliding along effortlessly. In the sporty S position, the front wheels receive a full 85 kW (115 hp) from standstill. The perfectly tuned power electronics function without jolts and in just the right dosage. In stop-start mode, the REX range extender can be activated manually or electronically. The driver would have to listen very closely to hear any difference in noise levels from having the REX on or off. The SWISSAUTO one-cylinder engine is perfectly well-behaved; it produces absolutely no vibrations and runs smoothly even at a full 7,000-rpm load. When the range extender is on, the combustion engine switches off below 25 kph and back on at around 50 kph. Power is transmitted by a one-gear continuously variable transmission. Top speed is limited to about 130 kph for optimum energy efficiency. But when braking, you first have to get used to the response and feedback from the brake pedal. The energy recovery system in the brakes gives them a significantly different feel from conventional brakes. The fine-tuning of the vehicle and the successful redesign of the drive train make SWISSAUTO’s POLO REX not only extremely good for the environment, but also a lot of fun to drive!” MOTOREX MAGAZINE I DECEMBER 2010 13
