188.8.131.52. System of change of phases of a gazoraspredeleniye
The system of change of phases of a gazoraspredeleniye continuously modifies phases of the executive mechanism of change of phases of a gazoraspredeleniye and a cam-shaft of a drive of inlet valves under the influence of hydraulic pressure which the oil operating valve (OCV) operates so that phases of opening and closing of valves optimum corresponded to operating conditions of the engine. Work of the oil managing director of the valve (OCV) is based on signals from the sensor of provision of a cam-shaft according to operating conditions of the engine. It operates the hydraulic pressure operating on the executive mechanism of change of phases of a gazoraspredeleniye.
Work according to traffic conditions: idling, small loadings
Thanks to overlapping reduction, less products of combustion come back to the cylinder. It stabilizes frequency of rotation of idling, improving fuel profitability, and also guarantees stability of operation of the engine at small loadings.
|Fig. 2.30. The chart of change of phases of a gazoraspredeleniye at various ranges of operation of the engine: 1–loading; 2–frequency of rotation of the engine; 3–idling range; 4–range of small loadings; 5–range of average loadings; 6–range of big loadings of small and average speeds; 7–range of big loadings and high speeds; 8–work at full loading
Overlapping increases, and EGR relation – grows in the cylinder. Losses thus decrease by a friction (pump losses), the temperature of combustion goes down and the quantity of CO in the fulfilled gases decreases. The number of emissions of hydrocarbons also decreases owing to repeated reburning of not ignited gas.
Big loading, low and average speeds
Inlet valves are closed early that provides high volume to. item, thus improves a torque in a range of low and average speeds.
Big loading, range of big speeds
Inlet valves are closed later, high volume to. the item of provides the maximum capacity.
At low temperature
Overlapping is minimized for prevention of hit of products of combustion in cylinders and reduction of amount of fuel in addition injected into cylinders. Fuel profitability thus improves and the raised turns of idling are stabilized.
At start-up or stop the engine
Starting qualities improved owing to overlapping reduction as products of combustion do not come back to the cylinder.
Table 2.12 Elements and their functions