Camshaft Support Structure of an Internal Combustion Engine and Assembly Method Thereof

Abstract

A lash adjuster support portion is integrally formed with a lower cam carrier. The lower cam carrier is fixed onto a cylinder head into which an intake valve and an exhaust valve have been fitted. After a lash adjuster is set in the lash adjuster support portion, a rocker arm is placed on the intake side and a rocker arm is placed on the exhaust side. Camshafts are then placed on the lower cam carrier such that the rocker arm contacts an intake cam and the rocker arm contacts an exhaust cam. An upper cam carrier is then assembled to the lower cam carrier, thus completing the camshaft support structure.

1 - 12 . (canceled) 
   
   
       13 . A camshaft support structure of an internal combustion engine, comprising:
 a cylinder head;   a camshaft;   a cam;   a rocker arm that abuts against the cam;   a lash adjuster that supports the rocker arm;   a lower cam carrier that supports the camshaft from the cylinder head side;   an upper cam carrier that supports the camshaft from the side opposite the lower cam carrier; and   a lash adjuster support portion which is provided separately from the cylinder head and connected to the lower cam carrier and supports the lash adjuster, wherein the lash adjuster support portion is not directly connected to the cylinder head.   
   
   
       14 . The camshaft support structure of an internal combustion engine according to  claim 13 , wherein the internal combustion engine is provided with a plurality of the lower cam carriers, and the plurality of lower cam carriers are connected together by a frame to form a ladder frame type lower cam carrier. 
   
   
       15 . The camshaft support structure of an internal combustion engine according to  claim 13 , wherein the lash adjuster support portion is integrally formed with the lower cam carrier. 
   
   
       16 . The camshaft support structure of an internal combustion engine according to  claim 13 , wherein the lash adjuster support portion is made of material that is lighter than aluminum. 
   
   
       17 . The camshaft support structure of an internal combustion engine according to  claim 16 , wherein the lash adjuster support portion is made of one of magnesium and resin composite. 
   
   
       18 . The camshaft support structure of an internal combustion engine according to  claim 13 , wherein the internal combustion engine has a plurality of cylinders arranged inline, a plurality of the lash adjusters are provided corresponding to the plurality of cylinders, and the lash adjuster support portion extends so as to support all of the lash adjusters and is provided with a first oil passage for supplying oil to the lash adjusters. 
   
   
       19 . The camshaft support structure of an internal combustion engine according to  claim 18 , wherein the internal combustion engine is provided with an intake valve and an exhaust valve for each cylinder, and the lash adjuster support portion is arranged in between the intake valve and the exhaust valve. 
   
   
       20 . The camshaft support structure of an internal combustion engine according to  claim 19 , wherein the first oil passage is formed such that the distance from a predetermined position in the first oil passage to the lash adjuster on the intake side of a given cylinder is the same as the distance from the predetermined position in the first oil passage to the lash adjuster on the exhaust side of the given cylinder. 
   
   
       21 . The camshaft support structure of an internal combustion engine according to  claim 18 , further comprising:
 a second oil passage for supplying oil to a bearing portion formed by the lower cam carrier and the upper cam carrier,   wherein the second oil passage is formed in a connecting body that includes the lash adjuster support portion, the lower cam carrier, and the upper cam carrier, and communicated with the first oil passage.   
   
   
       22 . The camshaft support structure of an internal combustion engine according to  claim 18 , further comprising:
 a third oil passage for supplying oil to sliding surfaces of the cam and the rocker arm,   wherein the third oil passage is formed in a connecting body that includes the lash adjuster support portion, the lower cam carrier, and the upper cam carrier, and communicated with the first oil passage.   
   
   
       23 . An assembly method of a camshaft support structure of an internal combustion engine, comprising the steps of:
 fixing a lower cam carrier having a lash adjuster support portion onto a cylinder head into which an intake valve and an exhaust valve have been fitted;   setting a lash adjuster in the lash adjuster support portion;   placing a rocker arm on the intake side and a rocker arm on the exhaust side;   placing camshafts on the lower cam carrier so that the rocker arm on the intake side contacts an intake cam and the rocker arm on the exhaust side contacts an exhaust cam; and   assembling an upper cam carrier to the lower cam carrier.