Method of controlling internal combustion engine

Abstract

The invention provides a control method of intending to improve a heat efficiency by an Atkinson cycle, improve a charging efficiency, improve an efficiency of a supercharger and increase a freedom of cam design. In particular, the invention relates to a control method of opening and closing a valve in an internal combustion engine with supercharger. An effective compression ratio is decreased by temporarily re-opening an exhaust valve in a compression stroke first stage, whereby a heat efficiency is improved without excessively increasing a cylinder internal pressure. Preferably, an exhaust valve re-opening time is set such that the effective compression ratio/expansion ratio is within a range from 0.5 to 0.9. Further, an exhaust valve is not temporarily opened in a compression stroke first stage, at a time of starting or driving under a low load, and the Atkinson cycle in accordance with the re-opening of the exhaust valve is achieved at a time of driving under a high load.

1 . A method of controlling an internal combustion engine, wherein an effective compression ratio is decreased by temporarily opening an exhaust valve in a compression stroke first stage while driving which is not while starting or driving under a low load.  
     
     
         2 . A method of controlling an internal combustion engine as claimed in  claim 1 , wherein an effective compression ratio is changed by a range from 0.5 to 0.9 times of the expansion ratio.  
     
     
         3  (Cancelled)  
     
     
         4 . A method of controlling an internal combustion engine as claimed in any one of claims  1  or  2 , wherein the internal combustion engine is provided with a first exhaust cam having only a cam crest for an exhaust stroke, and a second exhaust cam having a cam crest for the exhaust stroke and a cam crest for again opening the exhaust valve in the compression stroke first stage, and both the exhaust cams are arranged so as to be freely switched.  
     
     
         5 . A method of controlling an internal combustion engine as claimed in any one of claims  1  or  2 , wherein the internal combustion engine is provided with a first exhaust cam having only a cam crest for an exhaust stroke, and an auxiliary exhaust cam having only a cam crest for again opening the exhaust valve in the compression stroke first stage, and the method freely switches a single drive by means of the first exhaust cam, and a parallel drive by means of the first exhaust cam and the auxiliary exhaust cam.  
     
     
         6 . A method of controlling an internal combustion engine as claimed in  claim 4 , wherein the internal combustion engine is provided with a first exhaust cam having only a cam crest for an exhaust stroke, and an auxiliary exhaust cam having only a cam crest for again opening the exhaust valve in the compression stroke first stage, and the method freely switches a single drive by means of the first exhaust cam, and a parallel drive by means of the first exhaust cam and the auxiliary exhaust cam.