Pic. 2.29. Diagram of the valve timing mechanism: 1 - torque; 2 – engine speed; 3 - low and medium speed engine; 4 - high-speed engine; 5 - engine with a mechanism for changing the valve timing
The variable valve timing mechanism ensures the optimum opening and closing of the valves according to the operating conditions of the engine by continuously changing the timing of the intake camshaft and crankshaft (pic. 2.29).
Pic. 2.30. Diagram of changes in valve timing for different ranges of engine operation: 1 - load; 2 - engine speed; 3 - idle range; 4 - range of small loads; 5 - range of average loads; 6 - range of large loads of low and medium speeds; 7 - range of large loads and high speeds; 8 - work at full load