Valve mechanism for multi-cylinder internal combustion engine and assembling method of valve mechanism therefor

Abstract

Valve mechanism for a multi-cylinder internal combustion engine and iassembling method of the valve mechanism therefor are disclosed in which a swing camshaft is selectively assembled for each of the cylinders on the basis of at least an inner diameter of an inserting hole of the swing camshaft to make a lift difference between two engine valves (for example, two intake valves per cylinder) which is involved in a radial inclination of the swing camshaft with respect to a supporting shaft such as a drive shaft uniform between each of the cylinders.

1 . A valve mechanism for a multi-cylinder internal combustion engine, comprising:
 a drive shaft rotationally driven by means of a crankshaft of the engine and on an outer periphery of which a drive cam is installed;   a swing camshaft swingably and axially supported on an outer periphery of a supporting shaft via an inserting hole thereof with a predetermined clearance and on outer peripheries of axial both end portions of which two swing cams per cylinder are installed;   two engine valves operated to be open and closed by taking swing motions of the two swing cams via the swing camshaft; and   a transmitting mechanism linked to one axial end portion of the swing camshaft to convert a rotational motion of the drive cam into the swing motion to transmit the swing motion to the two swing cams, wherein the swing camshaft is selectively assembled for each of the cylinders on the basis of at least an inner diameter of the inserting hole to make a lift difference between the two engine valves which is involved in a radial inclination of the swing camshaft with respect to the supporting shaft uniform between each of the cylinders.   
   
   
       2 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein a lift adjusting section configured to simultaneously adjust lift quantities of the two engine valves is installed in the transmitting mechanism. 
   
   
       3 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein the valve mechanism further comprises a lift adjustment mechanism configured to adjust an average lift quantity of lift quantities of the two engine valves or the lift quantity or a lift position of at least one of the two engine valves after the swing camshaft is selectively assembled to adjust the radial inclination of the swing camshaft between each of the cylinders to a predetermined value. 
   
   
       4 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein a cam lift quantity of one of the two swing cams is set to be larger than that of the other of the two swing cams. 
   
   
       5 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein a cam clearance of one of the two swing cams is set to be smaller than that of the other of the two swing cams. 
   
   
       6 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein the valve mechanism further comprises a lash adjuster interposed between the two swing cams and the two engine valves corresponding to the two swing cams to adjust a cam clearance to be zero. 
   
   
       7 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein the supporting shaft on which the swing camshaft is swingably and axially supported is the drive shaft. 
   
   
       8 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 1 , wherein the valve mechanism further comprises a control shaft configured to vary a posture of the transmitting mechanism when it is revolved to simultaneously vary lift quantities of the two engine valves. 
   
   
       9 . The valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 8 , wherein cam profiles of the two swing cams are set in order for a difference in the lift quantities of the two engine valves when both of a clearance between an outer peripheral surface of the supporting shaft and an inner peripheral surface of the inserting hole of the swing camshaft and a cam clearance on the two swing cams are supposed to be zero, respectively, to fall within a predetermined range irrespective of a rotational angle of the control shaft. 
   
   
       10 . An assembling method of a valve mechanism for a multi-cylinder internal combustion engine, the valve mechanism comprising:
 a drive shaft rotationally driven by means of a crankshaft of the engine and on an outer periphery of which a drive cam is installed;   a swing camshaft swingably and axially supported on an outer periphery of a supporting shaft via an inserting hole thereof with a predetermined clearance and on outer peripheries of axial both end portions of which two swing cams per cylinder are installed;   two engine valves operated to be open and closed by taking swing motions of the two swing cams via the swing camshaft; and   a transmitting mechanism linked to one axial end portion of the swing camshaft to convert a rotational motion of the drive cam into the swing motion to transmit the swing motion to the two swing cams, and the assembling method comprising:   measuring an outer diameter of the supporting shaft and an inner diameter of the inserting hole of the swing camshaft; and   selectively assembling the swing camshaft for each of the cylinders on the basis of the measured inner diameter of the inserting hole to make a lift difference between the two engine valves which is involved in a radial inclination of the swing camshaft with respect to the supporting shaft uniform between each of the cylinders.   
   
   
       11 . An assembling method of a valve mechanism for a multi-cylinder internal combustion engine, the valve mechanism comprising:
 a drive shaft rotationally driven by means of a crankshaft of the engine and on an outer periphery of which a drive cam is installed;   a swing camshaft swingably and axially supported on an outer periphery of a supporting shaft via an inserting hole thereof with a predetermined clearance and on outer peripheries of axial both end portions of which two swing cams per cylinder are installed;   two engine valves operated to be open and closed by taking swing motions of the two swing cams via the swing camshaft; and   a transmitting mechanism linked to one axial end portion of the swing camshaft to convert a rotational motion of the drive cam into the swing motion to transmit the swing motion to the two swing cams, and the assembling method comprising:   measuring an outer diameter of the supporting shaft and an inner diameter of the inserting hole of the swing camshaft; and   selectively assembling the transmitting mechanisms whose lengths are different from each other onto the swing camshaft for the respective cylinders on the basis of the measured inner diameter of the inserting hole to make a lift difference between the two engine valves which is involved in a radial inclination of the swing camshaft with respect to the supporting shaft uniform between each of the cylinders.   
   
   
       12 . The assembling method of the valve mechanism for the multi-cylinder internal combustion engine as claimed in  claim 11 , wherein the assembling method further comprises adjusting an average lift quantity of lift quantities of the two engine valves or a lift quantity or a lift position of at least one of the two engine valves to a predetermined value through a lift adjustment mechanism installed in the transmitting mechanism after the radial inclination of the swing camshaft with respect to the supporting shaft is made uniform between each of the cylinders in the selective assembling of the transmitting mechanisms.