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| 2000-01-26 | |
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January 26, 2000
Rüsselsheim. In spring 2000 an all-new, 2.2 liter, four-valve gasoline engine will be premiered in the equally new Opel Astra Coupé. The efficient 2.2 16V is the first European representative of a new generation of four-cylinder ECOTEC engines with an aluminum cylinder head and engine block. The powerful unit develops 108 kW (147 hp) and already complies with the stringent Euro IV emission standards that will come into effect from 2005. In the Astra Coupé, the refined, ultra-modern engine develops maximum torque of 203 Nm. It features low fuel consumption and exhaust emissions together with exemplary noise and vibration suppression. Minimum maintenance is another significant step forward: Oil and filter renewal is the only routine service required. The new engine features a modular design principle which allows for a number of future applications such as turbo-charging, variable valve timing by means of camshaft control and gasoline direct injection. Next in Line: Opel Speedster also Powered by New Lightweight Engine After its premiere in the Astra Coupé, the innovative new unit will be used as a dynamic, refined power source for other Opel models, too. The next car to feature the 2.2 16V aluminum engine will be the Opel Speedster / Vauxhall VX220 – the lightweight, mid-engined two-seater which goes into production in summer 2000. Production of the new engines got under way early in 1999 at the world's largest engine plant in Tonawanda, near Buffalo, New York State. The 2.2-liter version of the engine will also be produced at the Opel's Kaiserslautern plant in Germany, where a new production line is due to go on stream in spring 2001. The planning and construction of the new Kaiserslautern facility is in the capable hands of Rita Forst, Opel's chief engineer in charge of production planning for engines and transmissions. The only female chief engineer at General Motors was instrumental in the integration of the new 2.2 16V in Opel's new Astra Coupé and involved in the associated, exhaustive testing. "We have already installed 65 percent of the plant at Kaiserslautern," she says. "We are right on schedule." World Engine Family: Opel and GM Powertrain Join Forces The 2.2-liter unit is a member of a new engine generation developed by an international team including engineers at Opel's International Technical Development Center in Rüsselsheim, Germany, and their colleagues at GM Powertrain in the USA. GM Powertrain bears global responsibility for all of General Motors' engines. The new four-cylinder gasoline engines cover the popular size range from 1.8 to 2.2 liters and will propel a wide variety of cars from every General Motors brand around the world in the years to come. Opel project chief, Walter Schnittger, says: "Cooperation with our colleagues in the global General Motors alliance gave us access to many synergy effects for the new engine generation which will be installed in numerous cars worldwide. To satisfy the requirements of the relevant markets and car platforms effectively, we made the basic engine as versatile as possible." More than 230 engineers and technicians joined forces to develop the new generation. For the first time, they modelled the engines entirely on the computer screen using GM's state-of-the art Unigraphics design software. Creating a three-dimensional electronic model had the significant advantage of reducing the number of time-consuming physical models required to an absolute minimum and accelerating numerous phases of the development process. Within hours, it was possible to transmit electronic models of complete engines or single modules from one development center to another by satellite, shortening the work process by days or even weeks. Built to Last: Most Demanding Validation Process in GM History Before going into production, the new engine family was subjected to the toughest and most comprehensive validation process ever instigated at General Motors. In addition to exhaustive testing on public roads under normal traffic conditions, the engines had to stand up to 650 consecutive hours of standard durability testing (as opposed to 450 hours with previous engines) and 1000 hours of deep thermal cycle testing in which the engine is run up to maximum operating temperature, then flushed with ice-cold coolant, shocking the components into contraction. The test program also included real-world road tests in extreme climates. The engine was run at 40 degrees Celsius in the sand and dust of the Australian Outback and had to tow trailers on inclines at GM's Arizona Proving Grounds. Cold-weather validation was conducted near the Arctic Circle in Sweden and at the winter proving grounds in Kapuskasing in Ontario, Canada. As a result of the arduous testing, customers will benefit from extended engine life, a high standard of reliability and, consequently, lower costs of ownership. Compact and Efficient: Lightweight Engine with Chain Drive Both the cylinder head and engine block of the new engine are made of lightweight aluminum. Thanks also to the application of modern design principles, the 2.2 liter unit weighs only 138 kilograms, making it about ten percent lighter than the 2.0 liter, 100 kW/136 hp engine familiar from the Astra and Vectra models (figures according to German Industrial Standard DIN 70020A – that is without engine oil and coolant). The new engine family is as compact in construction as the 2.0 16 V despite a cylinder spacing of 96 millimeters (3 millimeters larger). The reason: The two overhead camshafts which activate the inlet and exhaust valves via needle roller bearing cam followers are driven by a single roller chain which is only 12.5 millimeters wide and not by the more common, wider toothed belt. The 2.2 liter version is of slightly long-stroke design with a bore of 86 millimeters and a stroke of 94.6 millimeters. Low Maintenance: Service Limited to New Spark Plugs and Oil Change Extremely easy servicing is another advantage of this construction. Dr. Otto Willenbockel, the GM Powertrain director responsible for the worldwide development of all engines at General Motors says: "In addition to a reduced space requirement, the timing chain with hydraulic tensioner requires no maintenance over its entire working life." The same applies to the high-performance ignition module, which is mounted directly in the cylinder head cover and has two individual ignition coils located directly above the platinum spark plugs. This arrangement makes spark plug leads superfluous, resulting in greater operating reliability and lower maintenance requirements. Thanks to hydraulic valve clearance adjustment, the cam follower valve gear does not require any routine maintenance either. Apart from changing the engine oil and the fully recyclable oil filter, no servicing is required. In contrast to the previous bucket-type tappets the roller cam followers in the cylinder head create five percent less friction and thus contribute to the engine's excellent fuel consumption. The minimum specific consumption of the 2.2 liter ECOTEC unit is a mere 240 grams per kilowatt/hour, and the Astra Coupé's total fuel consumption is only 8.2 liters per 100 kilometers (MVEG standard). Emissions: Engines Already Meet Stringent Euro IV Norm An engine-management computer controls ignition and fuel injection on the new ECOTEC engines. It processes signals from the two oxygen sensors, takes care of on-board diagnosis and also controls the electronic throttle butterfly. The system permits comprehensive intervention for future anti-slip control systems or direct fuel injection applications, but above all it helps to meet Euro IV emission standards. At 1.0 g/km for carbon monoxide (CO), 0.1 g/km for hydrocarbons (HC) and 0.08 g/km for nitrogen oxides (NO) these limits, which come into effect in the European Union in 2005, are once again well below the current Euro II legal limits. In addition to the electronic accelerator ("drive by wire"), various measures have been taken to ensure that the Astra Coupé engine can already outperform these stringent requirements today. They include optimum combustion, carefully coordinated exhaust after-treatment with primary and main catalytic converter and exhaust gas recirculation as a means of reducing oxides of nitrogen. Minimum gap volumes at spark plugs and valves and pistons with a top land of only three millimeters also help to reduce pollutants and reduce hydrocarbon (HC) emissions. The development priority in exhaust after-treatment has shifted increasingly to the first few seconds after a cold start, since the catalytic converter does not begin to operate efficiently until its light-off temperature of approx. 300 to 350 degrees Celsius is reached. For this reason Opel engineers have turned the cylinder head of the transverse engine in such a way that the exhaust side is located in a "sheltered area" behind the engine rather than in the direct airflow when the car is being driven. With the shorter pipes permitted by this concept the catalytic converter's light-off temperature is reached more rapidly. Catalytic Converters: Two Oxygen Sensors for Precise Control The extensive exhaust emission control equipment includes a primary metallic-monolith catalytic converter which lights off very quickly, a ceramic main catalytic converter, two lambda probes and a controlled exhaust gas recirculation system; together, these features enable the engine to comply with the tough Euro IV standard. The two catalytic converters have a special active coating permitting high conversion rates and a long service life. One oxygen sensor is arranged behind each of the exhaust purification units. The first one controls fuel injection volume, the second, located after the main catalytic converter, checks the purifying action of the converters. Precise maintenance of the pre-defined fuel-air mixture is thus checked constantly and if the actual values deviate beyond the tolerance limits the driver is informed by a warning signal in the cockpit. In this way the new engine is already prepared for the European on-board diagnosis system (EOBD). An electronically controlled exhaust recirculation system is used to reduce NOx emissions. A proportion of the exhaust gas is returned to the combustion chambers where it reduces peak temperatures. The engine warms up quickly because the thermal conductivity of aluminum is considerably higher than that of gray cast iron. Together with a lower combustion chamber wall thickness of only eight millimeters this results in particularly rapid heating of the coolant and thus ensures, among other things, that the car's heater takes effect quickly in winter. Thanks to the good heat dissipation, only 8.1 liters of coolant are required in models with manual gearshift while 7.4 liters are sufficient with automatic transmission, bringing about a worthwhile reduction in the car's weight. Refinement: Rigid Crankcase and Two Balance Shafts Another important factor in the new ECOTEC engine family's development specification was minimum noise and vibration. The smooth combustion process with a compression ratio of 10:1 and a crankcase stiffened with a bedplate are the basis for achieving this requirement. A particularly rigid assembly with minimum vibration was achieved by bolting the crankcase to the gearbox and to the aluminum oil sump. The two balance shafts with their cast iron balancing weights run directly in the engine block and make the major contribution to the new engine's exemplary smoothness. The balance shafts are arranged at half-height at the right and left of the cylinders; a drive-chain rotates them in opposite directions at twice the crankshaft speed. This eliminates effectively the typical vibrations (secondary inertial forces) which occur in all four-cylinder engines. "We have achieved standards of noise and vibration matching those of a six-cylinder engine", says Chief Engineer Walter Schnittger, head of the new engine project at the International Technical Development Center in Rüsselsheim. Lost Foam Casting: High Precision, Quality, Environmental Compatibility The engine block, which is made entirely of aluminum, is produced by what is known as the "lost foam" casting process. Developed by General Motors, this is related to the classic lost-wax process which is used by jewelers and dentists on account of its high precision. Instead of wax, a polystyrene pattern made up of several sheets cut precisely in accordance with CAD data (Computer Aided Design) is used. When the hot aluminum melt is poured into the mold it fills the space occupied by the polystyrene foam, which burns at high temperature and evaporates as a gas. The gas can be easily removed by suction and filtered without causing any problems. This "lost foam" has given the process its name. The process is noted for its exceptional environmental friendliness, since – in contrast to the common resin cores – no harmful fumes are emitted to the atmosphere. The high integration potential of this casting process, which enables channels to be cast directly into the block – for example for crankcase breathing, oil supply or coolant – is of great importance because it makes various fastenings, processing steps and external hoses unnecessary, a development that will improve service quality and simplify production. | |
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