Cylinder management system
Cylinder control system (other names – system shutdown cylinders, cylinder deactivation system) is designed to change the working volume of the engine by disengaging from the work of the cylinder. The application of the system provides a reduction in fuel consumption by up to 20% and the reduction of harmful emissions with exhaust gases.
A prerequisite for the development of a cylinder control system was a typical vehicle operation mode in which the maximum power is used up to 30% for the entire period of operation. Thus, most of the time the engine runs at part load. Under these conditions, the throttle is almost closed, and the engine must draw in the required amount of air for operation. This leads to the so-called pumping losses and further decrease inefficiency.
The cylinder management system allows you to turn off part of the cylinders with a small engine load, while the throttle opens to provide the necessary power. In most cases, the cylinder shutdown system is used on multi-cylinder powerful engines (6, 8, 12 cylinders), the operation of which is especially ineffective at light loads.
In order to turn off a specific cylinder from work, two conditions must be met – to block air access and exhaust emissions (close the inlet and outlet valves) and to shut off the fuel supply to the cylinder.
Fuel supply control in modern engines is carried out using electronically controlled electromagnetic injectors. Keeping the intake and exhaust valves in a particular cylinder closed is a rather complicated technical task that different automakers solve in their own way. Among the variety of technical solutions, three approaches can be distinguished:
- the use of a pusher of a special design (Multi-Displacement System, Displacement on Demand);
- the ability to turn off the rocker arm (Active Cylinder Control, Variable Cylinder Management systems );
- use of camshafts of various shapes (Active Cylinder Technology ).
Forced cylinder deactivation, in addition to the undeniable advantages, has several disadvantages, including additional engine loads, vibration and unwanted noise.
To prevent additional loads on the engine, the exhaust gas charge from the previous duty cycle remains in the combustion chamber of the engine off. Gases are compressed when the piston moves up and press on the piston when it moves down, thereby ensuring an equalizing effect.
To reduce vibration, special hydraulic engine mounts and a two-mass flywheel are used. The noise level is reduced in the exhaust system, in which the lengths of the pipes are selected and the front and rear silencers with resonators of different sizes are used.
The cylinder management system was first used in 1981 on Cadillac vehicles. The system had electromagnetic coils mounted on rocker arms. The operation of the coil ensured the immobility of the rocker arm, while the valves were closed under the action of the springs. In the system, opposing pairs of cylinders were turned off. The coil was controlled by an electronic unit. Information on the number of cylinders in operation was displayed on the instrument panel. The system was not widely recognized, as it had problems with the supply of fuel to all cylinders, including those turned off.
The system of the Active Cylinder the Control, the ACC applied at Mercedes-Benz cars from 1999. Closing the cylinder valves provided a rocker of a special design, consisting of two levers connected by a latch. In the working position, the latch connects the two levers into a single unit. When deactivated, the latch releases the connection and each of the levers gets the opportunity to move independently. The valves, however, are closed by the action of the springs. The clamp is moved by oil pressure, which is regulated by a special solenoid valve. No fuel is supplied to switchable cylinders.
To preserve the characteristic sound of the operation of a multi-cylinder engine with the cylinders turned off, an electronically controlled valve is installed in the exhaust system, which, if necessary, changes the size of the section of the exhaust tract.
System Multi-the Displacement the System, the MDS is installed on Chrysler vehicles, Dodge, Jeep since 2004. The system is activated (turns off the cylinders) at speeds above 30 km / h and an engine speed of up to 3000 rpm.
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