Variable valve apparatus for internal combustion engine

Abstract

In order to simultaneously exert a plurality of functions such as execution of internal EGR, application of engine braking, improvement in fuel consumption and purification of exhaust gas, a variable valve apparatus for an internal combustion engine of the invention includes a cam shaft arranged to be rotatable on a cylinder head of the internal combustion engine, a rocker shaft arranged to be capable of oscillation in the internal combustion engine, a continuous variable rocker arm mechanism which is driven by a cam formed on the cam shaft, opens or closes air intake valves and exhaust valves, and continuously makes a lift of the valves variable, and a switching rocker arm mechanism which is driven by the cam formed on the cam shaft, opens or closes the air intake valves and the exhaust valves, and switches the lift of the valves in a stepwise manner.

1 . A variable valve apparatus for an internal combustion engine, comprising:
 a cam shaft arranged to be rotatable on a cylinder head of the internal combustion engine;   a rocker shaft arranged to be capable of oscillation in the internal combustion engine;   a continuous variable rocker arm mechanism which is driven by a cam formed on the cam shaft, opens or closes at least one of an air intake valve and an exhaust valve, and continuously makes a lift of the valve variable; and   a switching rocker arm mechanism which is driven by the cam formed on the cam shaft, opens or closes at least one of the air intake valve and the exhaust valve, and switches the lift of the valve in a stepwise manner.   
     
     
         2 . The variable valve apparatus for an internal combustion engine according to  claim 1 , wherein
 the switching rocker arm mechanism comprises:   a shared rocker arm which is supported on the rocker shaft to be capable of oscillation and configured to drive the valve;   a switching rocker arm which is driven by the cam and arranged to be capable of oscillation on the rocker shaft; and   a transmission mechanism which selectively transmits displacement from the switching rocker arm to the shared rocker arm.   
     
     
         3 . The variable valve apparatus for an internal combustion engine according to  claim 1 , wherein
 the continuous variable rocker arm mechanism comprises:   a shared arm supported on the rocker shaft to be capable of oscillation and configured to drive the valve;   a continuous variable arm driven by the cam and arranged to be capable of oscillation about a fulcrum arranged on the rocker shaft side;   an intermediate arm supported by the rocker shaft to be capable of oscillation and arranged between the shared arm and the continuous variable arm;   a transformation member which is arranged between the intermediate arm and the continuous variable arm and transmits oscillation displacement of the continuous variable arm to the shared arm through the intermediate arm; and   a drive mechanism which causes the rocker shaft to oscillate to displace the fulcrum.   
     
     
         4 . The variable valve apparatus for an internal combustion engine according to  claim 1 , wherein
 the internal combustion engine comprises the continuous variable rocker arm mechanism on an intake side and the switching rocker arm mechanism on an exhaust side, and   when the internal combustion engine is in an intake stroke, the exhaust valve is opened by the switching rocker arm mechanism, and the air intake valve is closed early by the continuous variable rocker arm mechanism.   
     
     
         5 . The variable valve apparatus for an internal combustion engine according to  claim 1 , wherein
 the internal combustion engine comprises at least one of the exhaust valves driven by the switching rocker arm mechanism and at least one of the exhaust valves driven by the continuous variable rocker arm mechanism per cylinder, and   when the internal combustion engine is near a compression top dead center, the exhaust valve is opened by the switching rocker arm mechanism, and the exhaust valve is opened early by the continuous variable rocker arm mechanism.