Variable valve actuation apparatus for internal combustion engine

Abstract

A variable valve actuation apparatus for an internal combustion engine includes a first link arm which has a projected portion that is engageable with and disengageable from a guide rail, and which is displaceable in the axis direction of a camshaft, and a link shaft linked to the first link arm in such a manner as to allow rotation but constrain movement in the axis direction. When an electro-magnetic solenoid is electrified, the first link arm rotates about the link shaft so that the projected portion engages with the guide rail. In association with the displacement of the link arms that occurs during the engagement, the state of motion of second rocker arms changes, so that the opening characteristic of valves provided for each cylinder is switched.

1 . A variable valve actuation apparatus for an internal combustion engine comprising:
 transfer members that are disposed between cams and valves and that transfer operating force of the cams to the valves;   a camshaft on which the cams are provided;   a guide rail provided on an outer peripheral surface of a cylindrical portion that is provided on the camshaft;   a main displacement member which has an engagement portion that is engageable with and disengageable from the guide rail and which is displaceable in an axis direction of the camshaft;   a member-linked shaft which is linked to the main displacement member in such a manner that, relative to the member-linked shaft, the main displacement member is allowed to rotate and is constrained from moving in the axis direction; and   an actuator that produces drive force for engaging the engagement portion of the main displacement member with the guide rail, wherein when the actuator operates, the main displacement member rotates about the member-linked shaft so that the engagement portion engages with the guide rail, and in association with displacement of the main displacement member and the member-linked shaft that occurs when the engagement portion and the guide rail are engaged, state of motion of the transfer member changes so that opening characteristic of the valves that are provided for at least two cylinders is switched.   
     
     
         2 . The variable valve actuation apparatus according to  claim 1 , wherein the main displacement member, the guide rail and the actuator are provided corresponding to at least one but not all of the cylinders of the internal combustion engine, and the variable valve actuation apparatus further comprising:
 a subsidiary displacement member which is provided for at least one other cylinder that is not provided with the main displacement member, and which is displaced in operative connection with the main displacement member via the member-linked shaft, wherein the state of motion of the transfer member provided for the cylinder that is provided with the main displacement member changes in association with the displacement of the main displacement member that occurs when the engagement portion and the guide rail are engaged, and the state of motion of the transfer member provided for the at least one other cylinder that is provided with the subsidiary displacement member changes in association with the displacement of the subsidiary displacement member which is in operative connection with the displacement of the main displacement member.   
     
     
         3 . The variable valve actuation apparatus according to  claim 2 , wherein the transfer member, for each of the at least two cylinders, includes a first rocker arm that is oscillatable synchronously with the cams, and a second rocker arm that is able to push the valves, the variable valve actuation apparatus further comprising:
 a switch pin that is disposed movably in a pin hole formed in the first rocker arm and in a pin hole formed in the second rocker arm, wherein the switch pin for the cylinder provided with the main displacement member is displaced in operative connection with the displacement of the main displacement member, and the switch pin for the at least one other cylinder that is provided with the subsidiary displacement member is displaced in operative connection with the displacement of the subsidiary displacement member, and wherein for the cylinder provided with the main displacement member, the first rocker arm and the second rocker arm are switched via the switch pin between a linked state in which the first rocker arm and the second rocker arm are linked together and an unlinked state in which linkage between the first rocker arm and the second rocker arm is removed, in operative connection with the displacement of the main displacement member, and for the at least one other cylinder provided with the subsidiary displacement member, the first rocker arm and the second rocker arm are switched via the switch pin between the linked state in which the first rocker arm and the second rocker arm are linked together and the unlinked state in which the linkage between the first rocker arm and the second rocker arm is removed, in operative connection with the displacement of the subsidiary displacement member.   
     
     
         4 . The variable valve actuation apparatus according to  claim 3 , wherein the member-linked shaft is disposed within a rocker shaft that supports the first rocker arms and the second rocker arms. 
     
     
         5 . The variable valve actuation apparatus according to  claim 3 , wherein the second rocker arm is used for a plurality of the valves that are provided for a cylinder. 
     
     
         6 . The variable valve actuation apparatus according to  claim 1 , wherein an outer peripheral surface of the member-linked shaft is provided with a groove that has an annular or arcuate shape, and the member-linked shaft penetrates an interior of the main displacement member, and the variable valve actuation apparatus further comprising:
 a pin that penetrates the main displacement member and that engages with the groove.