Camshaft and manufacturing method therefor

A method for manufacturing a camshaft for opening and closing engine valves provided respectively in a plurality of cylinders of an internal combustion engine, comprising:

• a fixing step of fixing inner cams with respect to an inner shaft, which is disposed rotatably in interior of an outer shaft on which outer cams are provided on an outer circumference thereof, the inner cams being fixed by pins through notches that are formed in the outer shaft;
• wherein the inner shaft is provided with a plurality of pin holes therein which extend along diametrical directions of the inner shaft, the pin holes are disposed at intervals along an axial direction of the inner shaft, and the directions in which adjacent pin holes extend are arranged at an angle obtained by dividing 360 degrees by the number of cylinders;
• the inner cams are formed with insertion holes having an inner diameter into which the pins are loosely fitted;
• and
• in the fixing step, the inner cams are fixed to the inner shaft by press-fitting the pins respectively through the insertion holes and the notches simultaneously with respect to all of a plurality of the pin holes.

A method for manufacturing a camshaft for opening and closing engine valves provided respectively in a plurality of cylinders of an internal combustion engine, comprising:

• fixing step of fixing inner cams with respect to an inner shaft, which is disposed rotatably in interior of an outer shaft on which outer cams are provided on an outer circumference thereof, the inner cams being fixed by pins through notches that are formed in the outer shaft;
• wherein the pins each comprise a small diameter portion and a large diameter portion which is larger in diameter than the small diameter portion;
• the inner shaft is provided with a plurality of pin holes therein which extend along diametrical directions of the inner shaft, the pin holes are disposed at intervals along an axial direction of the inner shaft, and the directions in which adjacent pin holes extend are arranged at an angle obtained by dividing 360 degrees by the number of cylinders;
• each of the pin holes has an inner diameter so that the small diameter portion is loosely fitted, and the large diameter portion is press-fitted therein;
• the inner cams are formed with insertion holes having an inner diameter into which the large diameter portion is loosely fitted, the insertion holes being coaxial with the pin holes;
• and
• in the fixing step, the inner cams are fixed to the inner shaft, at first, by loosely fitting the small diameter portions respectively through the insertion holes and the notches simultaneously with respect to all of a plurality of the pin holes, and thereafter, by press-fitting the large diameter portions respectively into the pin holes.