When starting the engine
When the pin in the camshaft actuator rests against the rotor, which is in the position of the maximum delay in opening or closing the valves under the action of the spring, the camshaft sprocket and camshaft rotate as a single part. When the oil pressure rises and the pin moves away from the rotor, it becomes possible to modify the mutual angular position of the camshaft sprocket and camshaft.
Valve opening or closing advance
Pic. 2.33. The scheme of oil circulation during advance opening or closing of valves: 1 - PCM block; 2 - oil control valve (OCV); 3 - spool valve; 4 - oil pump; 5 - camshaft; 6 - actuator for changing the valve timing; 7 - rotor; 8 - body; 9 - oil pan; 10 - to the compartment for advancing the opening or closing of valves; 11 - compartment for advancing the opening or closing of valves; 12 - from the compartment for delaying the opening or closing of valves
When the spool valve in the oil control valve (OCV) moves to the left according to the signal from the PCM, pressurized oil enters the valve opening or closing advance channel and the valve opening or closing advance chamber in the variable valve timing actuator. Then the rotor, combined with the camshaft, rotates in the direction of advancing the opening or closing of the valves, against the housing, which is driven by the crankshaft, and the moment of opening or closing the valves is shifted in the direction of advance (pic. 2.33).
Delayed opening or closing of valves
Pic. 2.34. The scheme of oil circulation during the delay of opening or closing the valves: 1 - PCM block; 2 - oil control valve (OCV); 3 - spool valve; 4 - oil pump; 5 - camshaft; 6 - actuator for changing the valve timing; 7 - rotor; 8 - body; 9 - oil pan; 10 - to the compartment for delaying the opening or closing of valves; 11 - compartment for delaying the opening or closing of valves; 12 - from the compartment for advancing the opening or closing of valves
When the spool valve in the oil control valve (OCV) moves to the right according to the signal from the PCM, oil from the oil pump under pressure is supplied to the valve opening or closing delay channel and to the valve opening or closing delay chamber of the variable valve timing actuator. Then the rotor, combined with the camshaft, turns in the direction of the delayed opening or closing of the valves, against the housing, which is driven by the crankshaft, and the moment of opening or closing the valves is shifted towards the side of delay (pic. 2.34).
Intermediate opening or closing of valves
Pic. 2.35. The scheme of oil circulation during the intermediate opening or closing of the valves: 1 - PCM block; 2 - oil control valve (OCV); 3 - spool valve; 4 - to the compartment for advancing the opening or closing of valves; 5 - to the compartment for delaying the opening or closing of valves
Spool valve in oil control valve (OCV) is in an intermediate position. Hydraulic pressure is maintained in both the advance and retard sections of the camshaft timing actuator. At the same time, the angle of mutual rotation of the rotor and the body does not change, which gives a fixed moment of opening or closing the valves (pic. 2.35).