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Mercedes-Benz has shown details of its new V12 engine which is stated to be intended to go into the S-Class.

The technical features of this 5,789 cc powerplant are known to have a power output of 367 ps (270 kW) at 5,500 rpm and an impressive torque of 530 Nm available from 4,250 rpm. These technical features are reported to include dual ignition, three-valve technology, automatic cylinder shut-off, low-friction cylinder liners and modern lightweight design. It is sure to have a significant improvement on fuel economy.

The principle of lightweight design of Mercedes cars is certain to be evident: the new V12 weighs 222 kg. This is known to have been achieved by modern construction processes and intelligent material selection. The crankcase is made of aluminium, with magnesium used for the intake manifold, while the exhaust manifold is made of laser-welded, high-pressure formed sheet steel. Cylinder liners are said to use a special aluminium-silicon alloy and connect rods manufactured in the so-called cracking process. They are also claimed to provide additional weight savings.

The three-valve technology is also known to have helped in weight loss, although its main advantages really revolve around fuel consumption and exhaust emissions.

One camshaft in each of the two cylinder banks operates the valves via low-friction roller-type rocker arms. A microcomputer-controlled adjustment mechanism is suggested to adapt camshaft control times to the appropriate road conditions, so help harmonious torque development, which is further followed by the complex geometry of the innovative ram pipe. Removing one of the outlet valves helps reduce heat loss inside the engine and creates the space to introduce two spark plugs for each combustion chamber.

The new engine proves to be controlled by an innovative alternating current ignition system. It can instantly identify and cure any misfiring, which helps protect the catalytic converters.

The V12 engine's standard cylinder shut-off system is mentioned to deactivate valve actuation and fuel injection for an entire cylinder bank when only part of the maximum output of torque is needed. During part-load operation this cures the inherent drawbacks of large-displacement engines, namely inadequate filling of the cylinder, low cylinder pressure and greater friction, which in turn adversely affect efficiency and fuel consumption. So smooth is the shut-off due to the electronic engine management system changing the throttle valve position and adjusting the ignition timing to prevent any sudden jump in torque, that it remains totally unnoticeable by the passengers. The deactivated combustion chambers are noticed to become fully operational once the accelerator is pushed.

Smoothness and low noise emissions are proved to be fully retained during cylinder shut-off. A valve in the mixing tube, leading to the underfloor catalytic converters, closes immediately when six of the 12 cylinders are shut off to prevent higher pressure waves occurring in the exhaust system. Automatic cylinder shut-off is expected to interrupt the link between the valves and camshaft hydraulically by locking the valve control arms. At the same time fuel supply and ignition on the left cylinder bank seem to be shut off.

Another technical feature of the new VI2 engine is considered to be its exhaust system: a total of six catalytic converters - four bulkhead catalysts plus two underfloor catalysts - and eight oxygen sensors reliably ensure that exhaust gas pollutants are purified.

Each cylinder bank has two bulkhead catalytic converters. Because of the three-valve technology and the air-gap insulated exhaust manifold the bulkhead catalytic converters is certain to reach their operating temperature just a few seconds after the engine is started from cold. Oxygen sensors are expected to monitor emissions going to and from the bulkhead converters. The data they provide is evaluated not only by the engine control unit but also by a special onboard diagnostic system. Emissions for the engine are concluded to comply with Euro 4.





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