Method for designing asymmetric timing for continuous variable valve timing (CVVT)

Abstract

The invention discloses a method for designing asymmetric timing for continuous variable valve timing (CVVT), wherein the method belongs to a design method of a valve timing mechanism. In order to enable the variation values of an advanced angle for driving a valve to be opened and a delay angle for driving the valve to be closed to be unequal for a continuous variable valve timing (CVVT) mechanism at the premise that the rotation phase of a cam shaft is not regulated, the adopted method is that cams for driving the CVVT mechanism are designed to be asymmetric, namely the curve angle for opening the valve and the curve angle for closing the valve by the cam are unequal, the respective corresponding crank shaft angles are different respectively, the variation of valve timing for the side corresponding to the large crank shaft angle in the operation of valve timing variation is greater than that of the other side, and the specific shapes for regulating the curves of the two sides can acquire the required valve timing. The method provided by the invention can be used for designing the shape curve of the cam of the CVVT mechanism for driving an intake valve and an exhaust valve, no matter whether the two kinds of cams are positioned on the same cam shaft.

Description

technical field [0001] The invention relates to an asymmetrical timing design method of continuously variable valve timing. The asymmetrical timing design method can make the variation values ​​of the opening advance angle and the closing retardation angle of the valve unequal. Background technique [0002] Generally, the change of the valve timing of the internal combustion engine is asymmetrical, for example, the opening angle of the exhaust valve is advanced at 30-80 degrees, and the closing angle is delayed at 10-35 degrees. The usual solution is to change the camshaft rotation phase. However, the method of changing the phase of the camshaft can only change the opening advance angle and the closing delay angle in the same direction, because the general cam shape is fixed, so the time interval from valve opening to closing is constant, but such valve timing Not optimal valve timing. [0003] The invention patent of the publication number CN200810161346 continuously vari...

AI Technical Summary

Problems solved by technology

The asymmetrical design of the cam shape curve only changes the speed at which the valves open and close, not the timing

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