Engine having variable valve timing device

Abstract

An engine having a variable valve timing device of the present invention may include a valve disposed to open/close a port, an elastic member for supporting the valve elastically to close the port, a first camshaft having a first cam formed thereon for moving the valve to open the port as the first camshaft rotates, a second camshaft having a second cam formed thereon for moving the valve to close the port as the second camshaft rotates, a first variable rotation mechanism for advancing or retarding the rotation of the first camshaft, and a second variable rotation mechanism for advancing or retarding the rotation of the second camshaft.

What is claimed is: 
     
         1 . An engine having a variable valve timing device comprising:
 a valve disposed to open or close a port;   an elastic member configured for supporting the valve elastically to close the port;   a first camshaft having a first cam formed thereon for moving the valve to open the port as the first camshaft rotates;   a second camshaft having a second cam formed thereon for moving the valve to close the port as the second camshaft rotates;   a first variable rotation mechanism for advancing or retarding the rotation of the first camshaft; and   a second variable rotation mechanism for advancing or retarding the rotation of the second camshaft.   
     
     
         2 . The engine having the variable valve timing device of  claim 1 , wherein the first variable rotation mechanism or the second variable rotation mechanism is formed at a pulley or a sprocket for having a torque forwarded thereto to rotate the first camshaft and the second camshaft. 
     
     
         3 . The engine having the variable valve timing device of  claim 1 , wherein the second camshaft is slidably inserted into the first camshaft, and the second cam penetrates the first camshaft to operate the valve. 
     
     
         4 . The engine having the variable valve timing device of  claim 1 , wherein the first variable rotation mechanism or the second variable rotation mechanism includes an advance angle chamber and a retard angle chamber for advancing rotation of the first camshaft and the second camshaft or retarding rotation of the first camshaft and the second camshaft. 
     
     
         5 . The engine having the variable valve timing device of  claim 4 , further comprising:
 first and second oil control valves matched to the first variable rotation mechanism and the second variable rotation mechanism for selective forwarding of hydraulic oil to the advance angle chamber or the retard angle chamber; and   a hydraulic pump for pumping the hydraulic oil to the first and second oil control valves.   
     
     
         6 . The engine having the variable valve timing device of  claim 4 , further comprising:
 a control unit for sensing rotation positions of the first cam and the second cam, and an RPM of a crankshaft, and determining an engine load, and sensing a position of an accelerator pedal, and   controlling the first and second oil control valves according to operation information sensed thus.   
     
     
         7 . The engine having the variable valve timing device of  claim 1 , wherein the first variable rotation mechanism is disposed to one end of the first camshaft, and the second variable rotation mechanism is disposed to the other end of the second camshaft. 
     
     
         8 . The engine having the variable valve timing device of  claim 3 ,
 wherein the first variable rotation mechanism has a torque forwarded thereto from the crankshaft to rotate the first camshaft, and   the second variable rotation mechanism rotates the second camshaft by rotation of the first camshaft to advance or retard the second camshaft with reference to the first camshaft.