Turbocharged engine

Abstract

An object of the present invention is to improve turbine efficiency and reduce fuel consumption. A turbocharged engine according to the present invention comprises an actuator for driving an exhaust valve and control means for controlling this actuator. The actuator is controlled ( 2 ) such that the exhaust valve opens from an identical valve opening start timing to but more rapidly than a case ( 1 ) in which a mechanical cam is used. As a result of the rapid opening of the exhaust valve, a strong exhaust pulse with a large peak value is obtained, whereby turbine efficiency is improved and accordingly fuel consumption is reduced. Since valve opening begins at an identical timing to a case in which a mechanical cam is used, the exhaust gas is not unnecessarily compressed and thus fuel consumption does not increase.

What is claimed is:  
     
         1 . A turbocharged engine comprising an actuator for driving an exhaust valve and control means for controlling this actuator, 
 wherein said actuator is controlled such that said exhaust valve opens more rapidly as compared to a case in which a mechanical cam is used and in which the valve opening start timing is identical.    
     
     
         2 . The turbocharged engine according to  claim 1 , wherein said actuator is controlled such that said exhaust valve opens to a substantially maximum lift instantaneously from the start of valve opening.  
     
     
         3 . The turbocharged engine according to  claim 1 , wherein said actuator is controlled such that the internal pressure of an exhaust port reaches a maximum value within a quarter of the time period during which said exhaust valve is open from the opening start timing of said exhaust valve.  
     
     
         4 . A turbocharged engine comprising an actuator for driving an exhaust valve and control means for controlling this actuator, 
 wherein said actuator is controlled such that said exhaust valve begins to open at an identical timing to a case in which a mechanical cam is used and the valve opening speed reaches a speed at which a desired exhaust pulse can be obtained.