Camshaft
A camshaft is a mechanical device making it possible to transform a rotary movement into longitudinal movement and reciprocally.
The tree with cams is a discovery of the Middle Ages during which it was mainly used in the water mills specialized in the beating of iron or the tanning of leather (transformation of the rotary movement, resulting from the drive of the paddle wheel by water, moving longitudinal).
Today, the camshaft is an essential part of the automobile engine: it transforms the rotary movement from the engine moving longitudinal actuating the valves.
The camshaft in the automobile engine
The camshaft is a machine element used in Moteur S thermics with internal combustion at 4 times for the synchronized order of the Soupape S. It is composed of a cylindrical stem having as many cam S that valves to be ordered independently or by group, slipping on the tail of valve, or a mechanical reference (e.g.: the shoe of a Tumbler).It is placed on the level of the crankshaft (Moteur collapsed or Moteur with side valves) or above the cylinder head (Camshaft at the head).
Driving collapsed
Initially gone up on the motor bikes of factory of competition, one assists with the generalization of the engines with valves “ in dessus ”, which authorizes a better filling of the engine. The camshaft being still located in bottom of the engine, because bound, for its synchronization, by a Gears with the Crankshaft or a chain, the ordering of the valves then requires long stems of recall to reach the Culbuteur S.Camshaft at the head
By laying out the camshaft at the head , i.e. in top of the engine, these stems are not necessary any more, but the synchronization of the tree is done by transmission, authorizing a shift of the axis of rotation. The camshaft, can be pulled by chain, Courroie notched, tree or cascades of pinion S and even by connecting rod-crank movement (mark motor bike NSU), to attack the valves directly, or via tumblers.Initially adopted in competition, this solution spread gradually with all the engines of vehicles of tourism.
Double camshaft at the head
At beginning of the year 70, in order to allow a good centering of the candle in the cylinder head, as well as an easy adjustment of the laws of distribution, one placed a camshaft for the inlet valves, and another for the exhaust. Space between the trees makes it possible to place the candle in the center of the combustion chamber.
Future
Various systems were created in order to be able to change the laws of distribution according to the driving mode and the action on the accelerator. Thus, one saw systems of shift of camshaft (Toyota VVTI) or of passage from 2 to 4 valves per cylinder (Honda 800 VFR). The future is with the variable Distribution, the valves being ordered not by a camshaft, but by electromagnetic systems (i.e technology Camless). This technology makes it possible via a calculator to order independently the valves according to the driving mode and of the request of acceleration.
| Random links: | Euclide | Grupo aeronaval | Transrapid | Vartan Malakian | Cryme nursery | District of Dongshan (Ürümqi) | Fairfield,_Iowa |