4.5.6.c The essence of the system
The essence of this system is simple. A special mechanism, on the outside of which there is a sprocket for the drive chain from the crankshaft, is installed on the camshaft (or shafts). This mechanism is installed so that it can turn the camshaft in the direction of advance or retard, depending on the operating mode of the engine. In more detail, the operation of the variable valve timing mechanism (phase shifter) occurs as described below.
The crankshaft through the drive chain rotates the phase shifter, which is installed on the camshaft. At the moment when it is necessary to shift the opening time of the valves in the direction of delay or advance, the phase shifter turns the camshaft in the appropriate direction.
Figure 4.12 Phase shifter appearance.
Phase shifters are mainly mounted on the intake camshaft (the shaft that only opens the intake valves). But nowadays these mechanisms are often mounted on both camshafts - intake and exhaust ones.
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