Valve operating apparatus for internal combustion engine

Abstract

A valve operating apparatus includes: a first intermediate arm and a first rocker arm that are interposed between a first cam unit and a first valve; a second intermediate arm and a second rocker arm that are interposed between a second cam unit and a second valve; and hydraulic lash adjusters that rockably support the rocker arms. The intermediate arms are rockably supported by a rocker shaft. In the axial direction of the rocker shaft, the distance between the first transmission part and a bearing nearest thereto is shorter than the distance between the first pressure receiving part and a bearing nearest thereto, and likewise, the distance between the second transmission part and a bearing nearest thereto is shorter than the distance between the second pressure receiving part and a bearing nearest thereto.

What is claimed is: 
     
         1 . A valve operating apparatus for an internal combustion engine, comprising:
 a first cam unit and a second cam unit configured to respectively drive a first valve and a second valve that are installed in a cylinder;   a first intermediate arm interposed between the first cam unit and the first valve, and including a first pressure receiving part that is pressed by the first cam unit and a first transmission part that transmits a pressing force of the first cam unit to a side of the first valve;   a second intermediate arm interposed between the second cam unit and the second valve, and including a second pressure receiving part that is pressed by the second cam unit and a second transmission part that transmits a pressing force of the second cam unit to a side of the second valve;   a rocker shaft configured to support the first intermediate arm and the second intermediate arm to be rockable between bearings that are respectively installed at both sides of the cylinder;   a first rocker arm interposed between the first intermediate arm and the first valve, and configured to transmit a pressing force from the first transmission part to the first valve;   a second rocker arm interposed between the second intermediate arm and the second valve, and configured to transmit a pressing force from the second transmission part to the second valve;   a first hydraulic lash adjuster configured to rockably support the first rocker arm, and act to eliminate a gap between the first valve and the first rocker arm, and a gap between the first rocker arm and the first intermediate arm; and   a second hydraulic lash adjuster configured to rockably support the second rocker arm, and act to eliminate a gap between the second valve and the second rocker arm, and a gap between the second rocker arm and the second intermediate arm,   wherein, in an axial direction of the rocker shaft, a distance between the first transmission part and the bearing that is nearest to the first transmission part is shorter than a distance between the first pressure receiving part and the bearing that is nearest to the first pressure receiving part, and a distance between the second transmission part and the bearing that is nearest to the second transmission part is shorter than a distance between the second pressure receiving part and the bearing that is nearest to the second pressure receiving part.   
     
     
         2 . The valve operating apparatus according to  claim 1 ,
 wherein the first pressure receiving part and the second pressure receiving part, and the first transmission part and the second transmission part are disposed on a same side with respect to the rocker shaft, seen from an axial direction of the cylinder.   
     
     
         3 . The valve operating apparatus according to  claim 1 ,
 wherein the first cam unit is configured by a first cam group including a plurality of cams having different profiles, and   wherein the valve operating apparatus further comprises a device that switches a cam that gives a pressing force to the first intermediate arm among the cams of the first cam group.   
     
     
         4 . The valve operating apparatus according to  claim 1 ,
 wherein the second cam unit is configured by a second cam group further includes a plurality of cams having different profiles, and   wherein the valve operating apparatus further comprises a device that switches a cam that gives a pressing force to the second intermediate arm among the cams of the second cam group.