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Main features of the mechanism of variable valve timing
The actuator variable valve timing has two hydraulic compartment: compartment advancing the date of opening or closing the valve and cut off the delay of opening or closing the valve. The compartments are located between the integrated body of the camshaft sprocket and the rotor camshaft. The oil pump feeds the engine oil in each compartment. The hydraulic pressure in each compartment is controlled by an oil control valve (OCV), and the relative phase of the camshaft sprocket and camshaft changed for the optimal moment to open or close valves according to engine operating conditions.
When starting the engine When the pin is in the actuator valve timing change rests on the rotor, which is under the action of the spring is at maximum delay of the opening or closing of valves, camshaft sprocket and camshaft are rotated as a single item. When the oil pressure increases, and the pin extends from the rotor, it is possible to modify the relative angular position of the camshaft sprocket and the camshaft.
Ahead of the opening or closing of valves
| Fig. 2.33. Driving oil circulation during timing of opening or closing of valves 1 - the block of PCM; 2 - oil control valve (OCV); 3 - spool valve; 4 - the oil pump; 5 - camshaft; 6 - actuator variable valve timing; 7 - a rotor; 8 - the case; 9 - the oil pan; 10 - lead to the compartment opening or closing the valves; 11 - slot timing of opening or closing the valves; 12 - from the cover opening or closing delay valve
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When the spool valve in the oil control valve (OCV) is moved to the left according to the PCM signal block, the pressurized oil enters the channel timing of opening or closing valves and advancing the compartment opening or closing the valve actuator in the valve timing change. Then the rotor combined with the camshaft rotates in the advancing direction of opening or closing the valve against the housing, which is driven by the crankshaft, and the opening or closing of valves is shifted to the advance side (Fig. 2.33).
Delay in opening or closing the valve
| Fig. 2.34. Driving oil circulation during the delay the opening or closing of valves 1 - the block of PCM; 2 - oil control valve (OCV); 3 - spool valve; 4 - the oil pump; 5 - camshaft; 6 - actuator variable valve timing; 7 - a rotor; 8 - the case; 9 - the oil pan; 10 - to delay compartment opening or closing the valves; 11 - slot delay opening or closing the valves; 12 - advance of the compartment opening or closing the valve
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When the spool valve in the oil control valve (OCV) moves to the right according to the PCM signal block, the oil from the oil pump is supplied under pressure into the channel delay the opening or closing valves and compartment retardation opening or closing the valve actuator valve timing change. Then the rotor combined with the camshaft rotates in the direction of opening or closing delay valve against the housing, which is driven by the crankshaft, and the opening or closing of valves is shifted to the delay side (Fig. 2.34).
Intermediate opening or closing of valves
| Fig. 2.35. Driving oil circulation during the intermediate opening or closing valves 1 - the block of PCM; 2 - oil control valve (OCV); 3 - spool valve; 4 - lead to the compartment opening or closing the valves; 5 - to delay the compartment opening or closing valves
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Spool valve in the oil control valve (OCV) is located in an intermediate position. Hydraulic pressure is stored in advance compartment and compartment retardation actuator valve timing change. At the same time, the relative rotation angle of the rotor and the housing is not changed, which gives a fixed time of opening or closing the valve (fig. 2.35).
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