Camshaft and manufacturing method therefor

Patent metadata

Field	Value
Publication number	US-10047639-B2
Application number	US-201715458455-A
Country	US
Kind code	B2
Filing date	Mar 14, 2017
Priority date	Mar 18, 2016
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A camshaft is equipped with an inner shaft which is arranged rotatably inside a cylindrical outer shaft. Further, in the inner shaft, a plurality of pin holes extend along diametrical directions thereof, and are disposed at intervals along the axial direction of the inner shaft. The directions in which adjacent pin holes extend are arranged at angles obtained by dividing 360 degrees by the number of cylinders. The inner shaft and the inner cams are fixed in a state in which large diameter portions of pins, each of which is provided with a small diameter portion and a large diameter portion, are press-fitted through insertion holes of the inner cams and notches of the outer shaft, and are press-fitted into the pin holes.

First claim

What is claimed is:

1. A camshaft for opening and closing engine valves provided respectively in a plurality of cylinders of an internal combustion engine, comprising:
a cylindrical outer shaft on which outer cams are provided on an outer circumference thereof;
an inner shaft disposed rotatably in the interior of the outer shaft; and
inner cams, which are fixed to the inner shaft by pins, through notches of the outer shaft, whereby the inner cams are rotated together with the inner shaft, and slide along a circumferential direction on an outer circumferential surface of 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; and
the inner shaft and the inner cams are fixed in a state in which the large diameter portions are press-fitted into the pin holes through the insertion holes and the notches.

2. The camshaft according to claim 1 , wherein:
the inner cams are C-shaped in cross section, in which an opening is provided between both ends in the circumferential direction thereof that enables the outer shaft to be passed therethrough along a diametrical direction, and are mounted to locations adjacent to the outer cams of the outer shaft slidably along a circumferential direction thereof; and
a distance between both end portions that form the opening of the inner cams is less than an outer diameter of locations of the outer shaft where the inner cams are mounted.

3. The camshaft according to claim 2 , wherein:
each of the inner cams has defined as a boundary thereof a diametrical direction, which is perpendicular to a direction in which the outer shaft is passed through the opening, and when the circumferential direction is partitioned respectively into two half-circumferences on a side of the opening and on a side opposite to the opening, a single one of the insertion holes is formed on a cam surface of the half-circumference on the side opposite to the opening including the boundary; and
the pins, which are inserted into the pin holes through the insertion holes and the notches, do not pass through the inner shaft.

4. 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.

5. 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.

6. The method for manufacturing the camshaft according to claim 5 , wherein, in the fixing step, the large diameter portions are press-fitted, respectively, simultaneously with respect to all of the plurality of pin holes.

7. The method for manufacturing the camshaft according to claim 5 , wherein, in the fixing step, the large diameter portions are press-fitted, at first, from pin holes disposed on respective sides nearer to both ends in the axial direction of the inner shaft than a pin hole disposed at a center side in the axial direction of the inner shaft.

Assignees

• Honda Motor Co Ltd

Inventors

• Sato Fumio
• Takeda Hiroshi
• Yoshimura Takuro
• Daimon Yuta

Classifications

• F01L2303/00

  Manufacturing of components used in valve arrangements · CPC title

• F01L2001/0476

  Camshaft bearings · CPC title

• F01L1/053 Primary

  overhead type · CPC title

• F01L1/34

  characterised by the provision of means for changing the timing of the valves without changing the duration of opening {and without affecting the magnitude of the valve lift} · CPC title

• F01L2001/0473

  Composite camshafts, e.g. with cams or cam sleeve being able to move relative to the inner camshaft or a cam adjusting rod · CPC title