The principle of operation
Are not going to go deep, our goal is to understand how they work. Actually normal camshaft on the end of a camshaft gear, which in turn is connected with a belt or timing chain.
The camshaft with the phase shifter on the end is a little bit different, redesigned. There are two hydro or electric controlled coupling, which on one hand also rests on the timing and on the other side with the shafts. Under the influence of hydraulics or electronics (there are special mechanisms) inside of this clutch can occur shifts, so it might move slightly, thereby changing the opening or closing of valves.
It should be noted that it is not always a phase shifter is installed on the two camshaft immediately, is that one is on the intake or exhaust, and the second is just an ordinary gear.
As usual the process manages ECU, which collects data from various engine sensors, such as crankshaft position, of the hall, the engine speed, speed, etc.
Now I invite you to consider the basic design of such mechanisms (I think so you have more clearer in my head).
VVT (Variable Valve Timing), KIA-Hyundai (CVVT), Toyota (VVT-i), Honda (VTC)
One of the first proposed to turn the crankshaft (relative to the initial position), the company Volkswagen, with its VVT system (based on it has built their system many other manufacturers)
What it includes:
Shifters (hydraulic) installed on the intake and exhaust shaft. They are connected to the lubrication system of the engine (actually it's oil and is pumped into them).
If you disassemble the clutch on the inside there is a special asterisk on the outer casing, which is fixedly connected to the shaft of the rotor. Body and rotor in the pumping of oil can move relative to each other.
The mechanism is fixed in the cylinder head, it has channels for hoses oil for both clutches, are controlled by the flows of two electro-hydraulic valves. By the way they also secured on the casing head block.
In addition to these valves in the system, many sensors – frequency of the crankshaft, engine load, coolant temperature, camshaft position and knee rolls. When you need to turn to adjust phase (e.g. high or low speed), ECU data reading gives orders to the dispensers feeding oil to the clutch, they open and the oil pressure starts to pump phase shifters (thus, they turn in the right direction).
Idle – rotation occurs in such a way that the "intake" camshaft provided later opening and later closing of the valves, and the "prom" is set so that the valve is closed much earlier before the approach of the piston at top dead center.
It turns out that the amount of waste mixtures is reduced almost to a minimum and almost not stopping in the intake stroke, it is beneficial to the operation of the engine at idling speed, its stability and uniformity.
Medium and high revs – here the task is to produce a maximum power, so the "turning" occurs in this way in order to delay opening of the exhaust valves. Thus, there remains a gas pressure on the tact of the working stroke. The intake in turn open up after achieving the upper piston dead centre (TDC) and closes after BDC. Thus, we obtained the dynamic effect of "equalizing" cylinder of the engine, which resulted in the increase of power.