Camshaft (camshaft) - a key element of the gas distribution mechanism, which is responsible for the timely opening and closing of the inlet or outlet valve for the supply of fuel-air working mixture or the release of exhaust gases.
The rod is used to synchronize the input and output on the stroke of the internal combustion engine. The detail provides functioning of all gas-distributing mechanism taking into account the order of work of cylinders and phases of gas-distribution concerning this or that concrete engine..
The camshaft is a shaft with cams located on it. The rod rotates in plain bearings, which are made in the form of supports. The engine oil under pressure from the lubrication system enters the distribution channels through the channels. The number of cams on the camshafts corresponds to the number of intake and exhaust valves of the engine. One valve gets its cam, which opens it by pressing the pusher. At that moment, when the camshaft cam comes off the pusher, then the valve closes under the powerful influence of the return spring.
Gas distribution phases depend on the shape of the camshaft cams. Such phases are understood as moments of opening and closing of valves, and the length of time the valve is open or closed. Modern power units also have a system of changing the phases of the gas distribution to increase the overall efficiency of the timing belt and improve the characteristics of the internal combustion engine.
In modern car engines, the camshaft is located at the top of the cylinder head. The camshaft is connected to the sprocket or crankshaft pulley by a belt or chain drive. The camshaft is the drive of the camshaft.
On four-stroke engines, the entire timing speed rotates twice as slow, than the crankshaft, since the full operating cycle of such internal combustion engines is carried out in two turns of the crankshaft. During these two turns, the inlet and outlet valves must open only once. It turns out so, that camshaft, controlling the opening of the valves, must make only one revolution per duty cycle.
In the design of the timing belt may be present more than one camshaft. This is most often due to the number of valves per cylinder. Today, the most widely used scheme of four valves per cylinder and two-shaft timing (one camshaft is the drive of the intake valves, and the other interacts with graduation). Four camshafts are installed for V-shaped internal combustion engines, since each row of cylinders has a separate cylinder head with two shafts. The single shaft timing system is called SOHC (English. Single OverHead Camshaft), two-shaft was named DOHC (English. Double OverHead Camshaft).