Abstract:
A variable valve system includes a variable valve lifter for changing a first lift amount of one or more valves at a predetermined engine speed; a variable valve timing portion for controlling opening and closing timing of one or more valves; and a cylinder deactivation portion that changes a second lift amount of two or more valves in an alternating pattern.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to, and the benefit of, Korean Patent Application No. 10-2007-0131664 filed in the Korean Intellectual Property Office on Dec. 14, 2007, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a variable valve system. 
     (b) Description of the Related Art 
     A variable valve lift (VVL) system changes a lift amount of an intake/exhaust valve of an engine according to driving conditions. Intake amount can be maximized at high speed/load and minimized at other times, to improve fuel efficiency and reduce exhaust gas. 
     A variable valve timing portion is provided at one end of each of the intake camshaft and the exhaust camshaft. Cylinder deactivation portions are provided at some of the cylinders. One hydraulic pressure line is provided for the cylinder deactivation portions and another hydraulic pressure line is provided for the variable valve timing portions. 
     However, when the cylinder deactivation portion continuously operates in a particular cylinder, an electric spark cannot be formed securely. Also, when the cylinder deactivation portion continuously operates in particular cylinder, the bore of the cylinder can be transformed. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     A variable valve system includes a variable valve lifter for changing a first lift amount of one or more valves at a predetermined engine speed; a variable valve timing portion for controlling opening and closing timing of one or more valves; and a cylinder deactivation portion that changes a second lift amount of two or more valves in an alternating pattern. 
     The variable valve lifter may control a rotation angle of a first control shaft to control a moving amount of a swing, arm, and/or control a rotation angle of a second control shaft to control a moving amount of a rocker arm. 
     The first lift amount may be high, low, or medium. The second lift amount may be on or off. 
     Two cylinder deactivation portions may be provided: a first one in a first cylinder, and a second one in a second cylinder. The system may alternately perform a first mode and a second mode. In the first mode, the first cylinder deactivation portion is operated, and the second is not. In the second mode, the first cylinder deactivation portion is not operated, and the second is. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a first schematic diagram of a variable valve system according to an exemplary embodiment of the present invention. 
         FIG. 2  is a second schematic diagram of a variable valve system according to an exemplary embodiment of the present invention. 
         FIG. 3  is a third schematic diagram of a variable valve system according to an exemplary embodiment of the present invention. 
         FIG. 4  is an arrangement table of a variable valve system according to an exemplary embodiment of the present invention. 
         FIG. 5  is a drive mode arrangement table of a variable valve system according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art will realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
     As shown in  FIG. 1 , an engine  105  includes a first cylinder (cyl. # 1 ) a second cylinder (cyl. # 2 ), a third cylinder (cyl. # 3 ), and a fourth cylinder (cyl. # 4 ). Also, an exhaust camshaft  115  and an intake camshaft  120  arc disposed to the cylinders. 
     A first cylinder deactivation portion  217   a  for exhaust and a second cylinder deactivation portion  217   b  for intake are provided in the first cylinder (cyl. # 1 ). A third cylinder deactivation portion  217   c  for exhaust and a fourth cylinder deactivation portion  217   d  for intake are provided the second cylinder (cyl. # 2 ). A fifth cylinder deactivation portion  217   e  and a sixth cylinder deactivation portion  217   f  are provided in the third cylinder (cyl. # 3 ). A seventh cylinder deactivation portion  217   g  and an eighth cylinder deactivation portion  217   h  are provided in the fourth cylinder (cyl. # 4 ). 
     A first hydraulic pressure line is provided to cylinder deactivation portions  217   a  to  217   h.  A check valve  100  is provided in the first hydraulic pressure line. Control valves (e.g., solenoid valves) are disposed on branch lines that are extended to the cylinder deactivation portions  217   a  to  217   h.    
     A variable valve timing portion  112  is disposed at one end of each camshaft  115 ,  120 , and a second hydraulic pressure line is provided to the variable valve timing portions  112 . A control valve  110  is disposed in branch lines to each of the camshafts  115  and  120 . 
     The deactivation portions  217   a  to  217   h  arc operated alternately. This prevents spark plugs disposed in any one particular cylinder from becoming fouled by oil. Also, bore transformation of a particular cylinder is prevented. 
     Referring to  FIG. 2 , a first variable valve lifter  405   a  is provided in an exhaust port of the first cylinder (cyl. # 1 ) and a second variable valve lifter  405   b  is provided in an intake port of the first cylinder (cyl. # 1 ). A third variable valve lifter  405   c  and a fourth variable valve lifter  405   d  are provided in the second cylinder (cyl. # 2 ). A fifth variable valve lifter  405   e  and a sixth variable valve lifter  405   f  are provided in the third cylinder (cyl. # 3 ). A seventh variable valve lifter  405   g  and an eighth variable valve lifter  405   h  are provided in the fourth cylinder (cyl. # 4 ). 
     The variable valve lifters  405   a  to  405   h  control a swing arm (not shown) so as to control a lift amount of the valve in  FIG. 2 . The valve controlled by the swing arm is adjusted in three steps of high, low, or medium. 
     A first control shaft  410   a  and a second control shaft  410   b  are provided so as to control the variable valve lifters  405   a  to  405   h.  The first control shaft  410   a  is provided at the exhaust side adjacent to the exhaust camshaft  115 , and the second control shaft  410   b  is provided at the intake side adjacent to the intake camshaft  120 . 
     Lifting distances of the exhaust valve and the intake valve are adjusted sequentially according to rotating positions of the first and second control shafts  410   a  and  410   b.    
     A third hydraulic pressure line is provided to the first and second control shafts  410   a  and  410   b.  A check valve  402  is provided in the third hydraulic pressure line. 
     The first control shaft  410   a  simultaneously controls valves of the exhaust side and the second control shaft  410   b  simultaneously controls valves of the intake side. 
     A first rotation angle control motor  400   a  is provided at one end of the first control shaft  410   a,  and a second rotation angle control motor  400   b  is provided at one end of the second control shaft  410   b.    
     Referring to  FIG. 3 , a ninth variable valve lifter  505   a  is provided in an exhaust port of the first cylinder (cyl. # 1 ), and a tenth variable valve lifter  505   b  is provided in an intake port of the first cylinder (cyl. # 1 ). A eleventh variable valve lifter  505   c  and a twelfth variable valve lifter  505   d  are provided in the second cylinder (cyl. # 2 ). A thirteenth variable valve lifter  505   c  and a fourteenth variable valve lifter  505   f  are provided in the third cylinder (cyl. # 3 ). A fifteenth variable valve lifter  505   g  and a sixteenth variable valve lifter  505   h  are provided in the fourth cylinder (cyl. # 4 ). 
     The ninth to sixteen variable valve lifters  505   a  to  505   h  control a rocker arm (not shown) so as to control a lift amount of a valve in  FIG. 3 . The valve controlled by the rocker arm is adjusted in three steps of high, low, or medium. 
     A third control shaft  510   a  and a fourth control shaft  510   b  are provided so as to control the variable valve lifters  505   a  to  505   h.  The third control shaft  510   a  is provided at an exhaust side and adjacent to the exhaust camshaft  115 , and the fourth control shaft  510   b  is provided at an intake side and adjacent to the intake camshaft  120 . 
     Lifting distances of the exhaust valve and the intake valve are adjusted continuously according to rotating positions of the third and fourth control shafts  510   a  and  510   b.    
     A fourth hydraulic pressure line is provided to the third and fourth control shafts  510   a  and  510   b.  A check valve  502  is provided in the fourth hydraulic pressure line. The third control shaft  510   a  simultaneously controls valves of the exhaust side and the fourth control shaft  510   b  simultaneously controls valves of the intake side. 
     A third rotation angle control motor  500   a  is provided at one end of the third control shaft  510   a,  and a fourth rotation angle control motor  500   b  is provided at one end of the fourth control shaft  510   a.    
     As shown in  FIG. 4 , an 14 engine has four cylinders (cyl. # 1 ,  2 ,  3 ,  4 ), where the second and third cylinders (cyl. # 2 ,  3 ) are classified into a first group, and the first and fourth cylinders (cyl. # 1 ,  4 ) are classified into a second group. The first group and the second group are alternately deactivated in the 14 engine. 
     The variable valve lift system can be operated in different cylinders when cylinders are alternately deactivated. The variable valve lift system includes systems that are operated by a rocker arm or a swing arm. 
     The first, third, and fifth cylinders (cyl, # 1 ,  3 ,  5 ) and the second, fourth, and sixth cylinders (cyl, # 2 ,  4 ,  6 ) are alternately deactivated in a V6 engine. The first, fourth, sixth, and seventh cylinders (cyl, # 1 ,  4 ,  6 ,  7 ) and the second, third, fifth, and eighth cylinders (cyl, # 2 ,  3 ,  5 ,  8 ) are alternately deactivated in a V8 engine. 
     Referring to  FIG. 5 , all cylinder deactivation portions (CDA) in group  1  and group  2  are operated in a fuel cut state. 
     When the cylinder deactivation portions (CDA) in group  1  are operated in a range from 2000 to 3500 rpm, the variable valve lifter (VVL) can be operated in three steps of high, low, or medium in group  2 . Also, when cylinder deactivation portions (CDA) of group  2  are operated in a range from 2000 to 3500 rpm, the variable valve lifter (VVL) can be operated in three steps of high, low, or medium in group  1 . The variable valve lifters (VVL) of groups  1  and  2  are operated and the cylinder deactivation portions (CDA) of groups  1  and  2  are not operated from idle to 2000 rpm. 
     At full load, the variable valve lifter (VVL) is operated in medium at a low speed and the variable valve lifter (VVL) is operated in high at a high speed. The cylinder deactivation portion (CDA) does not operate at a full load. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.