Variable Valve Drive Device, Engine, and Motorcycle

Abstract

In a variable valve drive device, a cam sprocket made to rotate by a driving force transmitted from a crankshaft. An eccentric plate is arranged at one end side of the cam sprocket in the rotation axis direction thereof, and is made to rotate around an axis in the same direction as the rotation axis of the cam sprocket. The axis of the eccentric plate is shiftable from the axile center of the rotation axis to an eccentric position. A variable camshaft is made to rotate around its rotation axis by the eccentric plate, and when the eccentric plate rotates the variable camshaft at the eccentric position, the rotational phase difference thereof with respect to the cam sprocket periodically fluctuates. An intake cam block is arranged at the other end side of the cam sprocket in the rotation axis direction thereof, and is made to rotate by the variable camshaft with the same phase as that of the variable camshaft to drive an intake valve.

1 . A variable valve drive device, comprising:
 a cam drive member that is made to rotate by a driving force transmitted from a crankshaft;   an eccentric member that is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position;   a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position;   a cam block that is made to rotate by the camshaft with the same rotational phase as that of the camshaft so as to drive an exhaust valve or an intake valve; characterized in that   the eccentric member is arranged at one end of the cam drive member in the rotation axis direction thereof, and   the cam block is arranged at the other end of the cam drive member in the rotation axis direction thereof.   
   
   
       2 . The variable valve drive device according to  claim 1 , characterized by further comprising:
 a member-shifting part that shifts the axis of the eccentric member from the axis position to an eccentric position with respect to the rotation axis of the cam drive member.   
   
   
       3 . The variable valve drive device according to  claim 1 , characterized by further comprising:
 another cam block that is made to rotate by the cam drive member with the same rotational phase as that of the cam drive member, and is arranged at a position neighboring the cam block.   
   
   
       4 . The variable valve drive device according to  claim 3 , wherein the cam block rotates to drive an intake valve, while another cam block rotates to drive an exhaust valve. 
   
   
       5 . The variable valve drive device according to  claim 3 , characterized in that the cam block rotates to drive an exhaust valve, while another cam block rotates to drive an intake valve. 
   
   
       6 . A variable valve drive device, characterized by comprising:
 a cam drive member that is made to rotate by a driving force transmitted from a crankshaft;   an eccentric member that is arranged at one end of the cam drive member in the rotation axis direction thereof, and is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position;   a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position;   a first valve-driving cam block that is arranged at the other end of the cam drive member in the rotation axis direction thereof, and is made to rotate with the same rotational phase as that of the camshaft, and has its duration made invariable; and   a second valve-driving cam block that is arranged at a position neighboring the first valve-driving cam block, and has its duration made variable.   
   
   
       7 . An engine, comprising:
 a variable valve drive device, including:   a cam drive member that is made to rotate by a driving force transmitted from a crankshaft;   an eccentric member that is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position;   a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position;   a cam block that is made to rotate by the camshaft with the same rotational phase as that of the camshaft so as to drive an exhaust valve or an intake valve; characterized in that   the eccentric member is arranged at one end of the cam drive member in the rotation axis direction thereof,   the cam block is arranged at the other end of the cam drive member in the rotation axis direction thereof,   the crankshaft is arranged substantially in parallel with the rotation axis of the cam drive member, and   the cam drive member rotates in conjunction with the rotation of the crankshaft through a driving force transmission part that is arranged in a direction substantially perpendicular to the crankshaft.   
   
   
       8 . An engine, comprising:
 a variable valve drive device, including:   a cam drive member that is made to rotate by a driving force transmitted from a crankshaft;   an eccentric member that is arranged at one end of the cam drive member in the rotation axis direction thereof, and is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position;   a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position;   a first valve-driving cam block that is arranged at the other end of the cam drive member in the rotation axis direction thereof, and is made to rotate with the same rotational phase as that of the camshaft, and has its duration made invariable; and   a second valve-driving cam block that is arranged at a position neighboring the first valve-driving cam block, and has its duration made variable; characterized in that the crankshaft is arranged substantially in parallel with the rotation axis of the cam drive member, and   the cam drive member rotates in conjunction with the rotation of the crankshaft through a driving force transmission part that is arranged in a direction substantially perpendicular to the crankshaft.   
   
   
       9 . The engine according to  claim 7 , characterized in that the engine is of the single cylinder type. 
   
   
       10 . A motorcycle that has mounted thereto an engine according to  claim 7 , such that the crankshaft is arranged in a direction of the vehicle width. 
   
   
       11 . The engine according to  claim 8 , characterized in that the engine is of the single cylinder type. 
   
   
       12 . A motorcycle that has mounted thereto an engine according to  claim 8 , such that the crankshaft is arranged in a direction of the vehicle width.