JP2006226184A - Camshaft device and its assembling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camshaft device capable of reducing torque, preventing reduction of service life of a bearing, and reducing dimension in the radial direction centered on a camshaft. <P>SOLUTION: This camshaft device is provided with the camshaft 1, a cam 2 being separate from the camshaft 1, having a through hole, and attached to the camshaft 1 in an externally fitting manner, and a rolling bearing 3 having an inner ring and an outer ring composed of an annular integrated object and supporting the camshaft 1 rotatably. In this camshaft 1, a section where the cam 2 is attached and a section where the rolling bearing 3 is attached have the same diameter and are linear. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camshaft device in which a shaft having a cam is supported by a bearing and an assembling method thereof.

In an engine of an automobile, all the bearings are slipped as shown in FIG. 7 in what is conventionally known as a device that rotatably supports a camshaft having a cam for operating a valve for supplying and exhausting air. There is a bearing 42 (see, for example, Patent Document 1). However, in order to improve the fuel consumption of the engine, a structure has been proposed in which the camshaft is supported by a rolling bearing having a low frictional resistance.
Further, as shown in FIG. 7, the conventional camshaft is manufactured by integrating the shaft body 44 and the cam 43. That is, the camshaft is cast so that, for example, the shaft body 44 and the plurality of cams 43 are integrated.
Further, when the number of cylinders in the engine is increased and the camshaft becomes longer, it is necessary to support the camshaft at the intermediate portion by the bearing. The annular bearing provided between the pair of cams and supporting the intermediate portion of the camshaft is divided into two so as to have an axially divided surface. This is because the cam portion 43 is integrated with the shaft main body portion 44, and the cam portion 43 has an outer diameter larger than that of the shaft main body portion 44. This is because it is necessary to assemble so as to sandwich 44.

As a thing provided with the sliding bearing in the intermediate part of the camshaft, there exists a thing as shown, for example in patent document 2, In the case of a sliding bearing, it is possible to employ | adopt a 2 division structure, and it is generally performed. ing.
Moreover, as what is provided with the rolling bearing, there exists a thing as shown in patent document 3, for example, This rolling bearing is a ball bearing structure, and the outer ring | wheel is divided into 2 parts. However, since this ball bearing having a divided structure has a joint (cut line) on the raceway surface, vibration and noise are generated when the ball passes through the joint, and the life of the bearing is further reduced. There is a problem. Therefore, it is considered difficult to put a camshaft device using a ball bearing into practical use.
Other examples of rolling bearings in which the race rings are divided are cylindrical roller bearings and needle bearings having linear raceways, but cylindrical roller bearings have a very large radial dimension and increase the size of the device. The needle bearing has a problem that the rolling element does not follow the deflection of the shaft and an edge load is generated, thereby shortening the life.
Therefore, a structure that can be assembled without dividing the raceway into two parts as shown in Patent Document 4 is conceivable. That is, in order to provide the rolling bearing between the pair of cams, a flange portion (journal portion) having a diameter larger than the maximum outer diameter of the cam is provided on the shaft, and the rolling bearing is provided on the outer peripheral side of the flange portion.

JP-A-8-218817 JP-A-4-12102 Japanese Utility Model Publication No. 5-6104 Japanese Utility Model Publication No. 6-8704

The apparatus described in Patent Document 4 can be assembled by moving the rolling bearing in the axial direction from the end portion of the shaft and fitting it to the flange portion without being affected by the cam. However, in this case, since the diameter of the flange portion is larger than the maximum outer diameter of the cam, it is necessary to wastefully widen the space for accommodating the cam, and the entire engine housing becomes large. have.
In other words, when a camshaft is supported by a bearing between a pair of cams, it is necessary to make the bearing a split structure in order to reduce the radial dimension around the camshaft. There are problems such as vibration, noise, and life reduction. On the other hand, if a bearing having an annular ring is used to eliminate joints in the bearing, the overall dimensions are increased for assembly.

  Accordingly, the present invention has been made in view of the above problems, and by using a rolling bearing, the torque can be reduced, and further, the radial dimension centered on the camshaft without reducing the bearing life. It is an object of the present invention to provide a camshaft device and an assembling method thereof.

In order to achieve the above object, a camshaft device according to the present invention includes a camshaft, a cam which is a separate body from the camshaft and has a through-hole and is attached to the camshaft in an outer fitting manner, and an annular shape And a rolling bearing that rotatably supports the camshaft.
According to such a configuration, by supporting the camshaft by the rolling bearing, the frictional resistance in the bearing can be reduced and the friction loss during rotation can be reduced. In particular, the frictional resistance at the time of starting rotation and during low-speed rotation can be reduced.
Since the cam is separated from the camshaft, the rolling bearing can be moved from the end of the camshaft as an external fitting shape and attached to a predetermined position. Therefore, it is not necessary to make the bearing ring of the rolling bearing have a divided structure, and no joint is formed on the raceway surface. Furthermore, a rolling bearing can be provided directly on the outer peripheral surface that is linear in the axial direction in the camshaft, and a flange portion that is larger in diameter than the cam portion for externally fitting the rolling bearing is required. do not do. As a result, the radial dimension around the camshaft can be reduced.

  Moreover, it is preferable that the cam is fitted and fixed to the camshaft with a tightening margin. According to this configuration, the cam can be easily and firmly attached, and a separate fixing member is not required and the number of parts can be reduced.

  In the camshaft, it is preferable that a portion where the cam is attached and a portion where the rolling bearing is attached have the same diameter. By making the camshaft straight (straight), centerless machining of the camshaft becomes possible. Furthermore, the cam and the rolling bearing can be attached by moving in the axial direction from the end of the camshaft to a predetermined position as an external fit.

The rolling bearing is a deep groove ball bearing. According to this, even if the camshaft is bent and a deflection angle is generated in the bearing portion, it occurs in the needle bearing because it has a followability between the ball that is a rolling element of the rolling bearing and the raceway surface that is a curved surface. Such edge loading does not occur.
Further, it is possible to receive an axial load acting on the camshaft in the bearing. That is, the axial displacement and movement of the camshaft can be regulated without using a member that receives an axial load.

  Further, it is preferable that an inner ring raceway groove of the rolling bearing is formed on an outer peripheral surface of the camshaft. Thereby, the camshaft can be used as an inner ring of a rolling bearing, the number of parts can be reduced, and the load capacity can be increased.

  Moreover, it is preferable that the ring member which has elasticity is attached to the outer peripheral surface of the outer ring | wheel of the said rolling bearing. According to this configuration, the elastic ring member is interposed between the outer peripheral surface of the outer ring of the rolling bearing and the inner peripheral surface of the housing that houses the camshaft, so that the radial heat between the rolling bearing and the housing can be obtained. A gap due to a difference in expansion can be eliminated. This is particularly effective for a rolling bearing having a larger radial dimension than a sliding bearing, and more effective for an aluminum housing. Furthermore, vibration and sound in the rolling bearing that supports the camshaft can be suppressed.

In addition, it is preferable that a cam shaft rotation drive disc is attached to the cam shaft, and the vicinity of the disc of the cam shaft is supported by a roller bearing.
According to this, a large radial load acts on a portion where a disc (for example, a pulley) for rotating the camshaft around its axis is applied, but by using a roller bearing having a large load capacity, , Can be supported stably. Note that the camshaft rotation drive disk includes a pulley, a sprocket, and a gear.

Furthermore, in the method of assembling a camshaft device, wherein a plurality of cams and a plurality of rolling bearings are respectively disposed at predetermined positions in the axial direction of the camshaft, the cams are separated from the camshaft and have a through hole. The rolling bearing is moved in the axial direction sequentially from the end portion of the linear camshaft to each predetermined position, and the cam and the rolling bearing are attached to the camshaft.
According to this, since the rolling bearing is moved along the axial direction of the camshaft and attached at a predetermined position, it is not necessary to make the raceway of the rolling bearing have a split structure. Therefore, there is no seam on the raceway surface of the rolling bearing. And since it can attach to a camshaft after attaching a rolling bearing to a camshaft, it is not necessary to set it as the rolling bearing which has the inner ring | wheel of the internal diameter exceeding the maximum outer diameter of a cam like the past. Therefore, the camshaft device assembled by this assembling method can reduce the radial dimension.
Further, since the standardized cam and rolling bearing can be provided at any axial position of the camshaft, it is possible to easily cope with changes in the specifications of the camshaft (changes in the position and number of engine cylinders).

  In this assembling method, it is preferable that the cam is fitted to the camshaft with a tightening margin in the through hole of the cam and fixed to the camshaft. According to this configuration, the cam can be easily and firmly attached, no separate fixing member is required, and the number of parts can be reduced.

  According to the present invention, by adopting a rolling bearing, the torque of the camshaft can be reduced, and when used in an engine such as an automobile, it can contribute to an improvement in fuel consumption. Since the joints can be eliminated from the raceway grooves of the rolling bearing, the bearing life can be extended. Further, the radial dimension around the camshaft can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a partial cross-sectional side view showing a camshaft device according to an embodiment of the present invention. This camshaft device can be used, for example, in a camshaft mechanism for operating an air supply / exhaust valve of an automobile engine. In this apparatus, a plurality of cams 2 and a plurality of rolling bearings 3 are arranged on a camshaft 1 at predetermined positions in the axial direction of the camshaft 1. One rolling bearing 3 is provided between a pair of cams 2 that form a pair.
FIG. 2 is an enlarged cross-sectional view showing the main part of FIG. 1, and this apparatus is a linear camshaft 1, and is separate from the camshaft 1 and attached to the camshaft 1 in an outer fitting manner. An egg-shaped cam 2 and a plurality of rolling bearings 3 that rotatably support the camshaft 1 are provided.

  That is, the camshaft 1 in this apparatus is not an integral structure of the shaft body 44 and the cam 43 by casting as in the conventional example shown in FIG. 7, but as shown in FIGS. This is due to the assembly structure in which the camshaft 1 and the cam 2 are assembled after being manufactured separately. The camshaft 1 is a rod member having a circular cross section, and the cam 2 is formed with a through-hole 10 for fitting to the camshaft 1. Thus, the cam 2 is fitted from the end of the camshaft 1 and can move in the axial direction along the camshaft 1, and is attached to a predetermined axial position (cam mounting portion 14) of the camshaft 1. It is done.

  In addition, the rolling bearing 3 is attached to the camshaft 1 as an outer fitting shape and rotatably supports the camshaft 1 and is a deep groove ball bearing. As shown in FIG. 2, the rolling bearing 3 includes an inner ring 4 and an outer ring 5 provided radially outward of the inner ring 4, and a raceway groove 6 of the inner ring 4 and a raceway groove of the outer ring 5. A rolling element composed of a plurality of balls 7 is interposed between the two and 12. These balls 7 are held by a cage 13. An inner ring 4 is externally fitted and fixed to the outer peripheral surface 1 a of the camshaft 1.

  FIG. 3 is a partially sectional side view showing another embodiment of the camshaft device of the present invention, and FIG. 4 is an enlarged sectional view showing an essential part of FIG. 3 and FIG. In the rolling bearing 3 provided in the apparatus, an inner ring raceway groove 6 of the rolling bearing 3 is formed on the outer peripheral surface 1 a of the camshaft 1. That is, the inner ring 4 in the apparatus of FIG. 2 is omitted, and the camshaft 1 is the inner ring. Thereby, the number of parts can be reduced and the load capacity can be increased.

  In each of the above-described embodiments, the bearing ring of the rolling bearing 3 is not a divided structure (is formed of a one-piece structure) having an annular shape (no joints on the raceway surface). In other words, in the case of the apparatus shown in FIGS. 1 and 2, the inner ring 4 and the outer ring 5 are not formed in a divided structure, but are formed as a single ring. In the case of the apparatus shown in FIGS. 3 and 4, the outer ring is not a split structure, but is formed of an annular one. The rolling bearing 3 is fitted externally from the end of the camshaft 1 and can move in the axial direction along the camshaft 1. The rolling bearing 3 can be moved to a predetermined axial position (rolling bearing mounting portion 15) of the camshaft 1. It is attached.

  The cam 2 may be configured to rotate integrally with the camshaft 1 using a key member or the like (not shown), but it is preferable that the cam 2 is fitted and fixed to the camshaft 1 with a tightening margin in the through hole 10 of the cam 2. . Therefore, the cam 2 may be attached to the camshaft 1 by shrink fitting, for example. Further, in the embodiment shown in FIGS. 1 and 2, the inner ring 4 of the rolling bearing 3 is also fitted and fixed to the camshaft 1 with a tightening margin. As a result, the cam 2 and the rolling bearing 3 can be easily and firmly attached, no separate fixing member is required, and the number of parts can be reduced.

  The camshaft 1 is configured as a straight line that allows the cam 2 and the rolling bearing 3 to be fitted on the camshaft 1 from the end side and moved in the axial direction so that they can be attached to predetermined positions. Yes. That is, in order to move the cam 2 and the rolling bearing 3 axially from the end of the camshaft 1 to predetermined positions, respectively, the cam mounting portion 14 and the rolling bearing mounting portion 15 have the same outer diameter, and these The linear camshaft 1 is configured so as to have a circular cross section having a maximum outer diameter in the portion. Specifically, in the camshaft 1 shown in FIGS. 2 and 4, the outer diameter D1 of all the cam mounting portions 14 and the outer diameter D2 of all the rolling bearing mounting portions 15 have the same value. In the case of FIG. 4, the raceway groove 6 is formed in the rolling bearing mounting portion 15, and the outer diameter D2 of the rolling bearing mounting portion 15 is the diameter at the shoulder.

Accordingly, the camshaft device assembly method of each of the above embodiments is such that the cam 2 separated from the camshaft 1 is externally fitted to the camshaft 1 from the end (one end side) of the linear camshaft 1. In the through hole 10 of the cam 2, the cam shaft 1 is fitted and fixed with a tightening margin. 1 and 2, the inner ring 4 is fitted on the camshaft 1 from the end (one end side) of the camshaft 1 to a predetermined rolling bearing mounting portion 15. Move it in the axial direction and fix it with a tightening margin. 3 and 4, the camshaft 1 is inserted into the outer ring 5 from the end (one end side) of the camshaft 1, and the outer ring 5 is connected to a predetermined rolling bearing mounting portion 15. Move it axially until it is fixed.
That is, in each embodiment, according to the arrangement of the cam 2 and the rolling bearing 3 as a whole, the cam 2 or the rolling bearing 3 is inserted into the camshaft 1 sequentially from the end of the camshaft 1 to the predetermined position in the axial direction. It is moved and attached. Thereby, the layout of the cam 2 and the rolling bearing 3 can be made free, and the number of parts can be reduced.

  As shown in FIG. 2 or 4, an elastic ring member 8 is attached to the outer peripheral surface 5 a of the outer ring 5 of the rolling bearing 3. The ring member 8 is attached to a circumferential concave groove 16 formed on the outer peripheral surface 5 a of the outer ring 5. The ring member 8 can be made of, for example, resin or rubber. According to the ring member 8, a temperature difference occurs in the housing in the engine provided with the camshaft device, and a gap or stress due to a radial expansion difference generated between the bearing mounting portion 17 on the housing side and the rolling bearing 3 is reduced. Can be suppressed. In addition, although two ring members 8 are provided side by side in the axial direction, the number may be one or three or more.

As shown in FIGS. 1 and 3, a camshaft 1 is attached with a pulley mounting portion 9 for driving rotation of the camshaft on one end side. A belt (not shown) is hung on the pulley mounting portion 9, and the camshaft 1 is rotated around its central axis via the belt and the pulley mounting portion 9 by a rotational drive source (not shown). Yes.
The vicinity of the pulley mounting portion 9 on the end side of the camshaft 1 is supported by a cylindrical roller bearing 11 as shown in FIG. Although a large radial belt load acts on the pulley mounting portion 9, one end portion of the camshaft 1 can be stably supported by using the cylindrical roller bearing 11 having a large load capacity. The cylindrical roller bearing 11 has a supporting shaft (camshaft 1) as an inner ring, and an outer peripheral surface of the shaft as a raceway surface for the cylindrical roller 19.
Further, a circumferential concave groove 21 is also formed on the outer peripheral surface 20 a of the outer ring 20 of the cylindrical roller bearing 11, and an elastic ring member 22 is provided in the concave groove 21 in the same manner as the ring member 8. It has been.

  1 and 3, the shaft portion on the one end portion side of the camshaft 1 to which the pulley attachment portion 9 is attached is made smaller than the outer diameters of the cam attachment portion 14 and the rolling bearing attachment portion 15. Further, a projecting portion 18 having an outer diameter larger than the outer diameter of the cam mounting portion 14 and the rolling bearing mounting portion 15 is provided on the other end portion side opposite to the one end portion where the pulley mounting portion 9 is provided. It has been. However, the projecting portion 18 is not formed as a single body with the camshaft 1 but is formed as a separate body (separate member). A screw hole is formed in the other end portion of the camshaft 1, and the projecting portion 18 is formed. The male screw portion is provided on the camshaft 1 and the projecting portion 18 is attached to the camshaft 1 by screwing together. That is, the camshaft 1 is also made the same diameter or smaller than the outer diameters of the cam mounting portion 14 and the rolling bearing mounting portion 15 on the other end side. As a result, centerless machining (centerless polishing) can be performed on the cam mounting portion 14 and the rolling bearing mounting portion 15 of the camshaft 1, and the camshaft 1 can be manufactured easily and at low cost with high accuracy.

  That is, the positioning of the camshaft 1 or the attachment of other members is required, and the protruding portion 18 having a larger diameter than the cam mounting portion 14 and the rolling bearing mounting portion 15 is provided at the end of the camshaft 1. The camshaft 1 is formed by threading or forming a keyway, and the camshaft 1 has an outer diameter portion larger than the outer diameters of the cam mounting portion 14 and the rolling bearing mounting portion 15. It is configured so that there is no. Therefore, the pulley mounting portion 9 on the one end side of the camshaft 1 is also formed separately from the linear main body portion of the camshaft 1. That is, the pulley mounting portion 9 and the shaft portion for the pulley mounting portion 9 are separated from the camshaft 1, and the shaft portion is screwed into a screw hole formed on the end surface of the camshaft 1 for assembly. The pulley attachment portion 9 is attached to the camshaft 1.

  The camshaft 1 may have a linear shape with the same diameter over the entire length and an axially uniform circular cross section (that is, there is no step on the outer circumferential surface 1a over the entire length), but all the camshafts 1 have the same outer diameter. The cam mounting portion 14 and all of the rolling bearing mounting portions 15 can have a maximum diameter, and the other portions can have a slightly smaller diameter, and can be linear with small steps. That is, since the camshaft 1 has the egg-shaped cam 2 as a separate body, the camshaft 1 alone has a circular shape centered on the shaft axis over the entire axial length.

  In the present embodiment as described above, a separate bearing is first combined with the conventional camshaft in which the cam portion 43 and the shaft main body portion 44 shown in FIG. It's not that. In other words, the camshaft and the bearing are not considered as separate items, but the camshaft unit including the rolling bearing 3 and the camshaft 1 to which the cam 2 is attached is integrated. Therefore, this unit can be incorporated as it is when the engine is assembled.

By using all of the bearings supporting the camshaft 1 as rolling bearings 3 (deep groove ball bearings and cylindrical roller bearings 11), it is possible to reduce the frictional resistance particularly at the start of rotation and at the time of low speed rotation. Friction loss during rotation can be greatly reduced in the entire apparatus. Therefore, by using this camshaft device for an automobile engine, it is possible to contribute to improvement in engine fuel efficiency.
FIG. 5 shows the relationship between the rotational speed and the friction torque in the rolling bearing 3 according to the present invention and the sliding bearing used in the conventional camshaft device, which gradually increased the rotational speed. It is the test result which showed the friction torque in the case. The thing by the rolling bearing 3 is the arrow A, and the thing by the sliding bearing is the arrow B. As can be seen, the rolling bearing 3 has a constant friction torque at a low value regardless of the number of rotations, whereas the sliding bearing has a very large frictional torque because the coefficient of static friction is particularly large at the start. It can be seen that the value is large and that the value is large even at a low rotational speed. In addition, this test is based on the bearing alone, and the radial load applied to the bearing is 70 kgf and the bearing temperature is 65 ° C. in a lubrication environment with engine oil. The specification of the sliding bearing uses a cylindrical bush having an inner diameter of 28 mm, an outer diameter of 30 mm, and an axial length of 12 mm, and the rolling bearing 3 corresponds to the reference number 6903.

Further, according to the present embodiment, since all the cams 2 are separated from the camshaft 1, a plurality of rolling bearings 3 are moved from the end of the camshaft 1 as an external fitting shape and attached at predetermined positions. be able to. Therefore, it is not necessary to make the outer ring 5 and the inner ring 4 of the rolling bearing 3 into a divided structure, and no joints are generated in the outer ring raceway groove 12 and the inner ring raceway groove 6.
Further, since the rolling bearing 3 can be provided directly on the outer circumferential surface 1a that is linear in the axial direction in the camshaft 1, the flange portion for mounting the bearing that has a larger diameter than the cam portion that has been conventionally required. Do not need. Thereby, in the housing of the engine that houses the camshaft 1, the radial dimension around the camshaft 1 can be reduced.

Further, by using the rolling bearing 3 supporting the camshaft 1 in the vicinity of the cam 2 as a deep groove ball bearing, the following effects can be obtained. A plurality of cams 2 are provided on the camshaft 1, and a load is applied to these cams 2 during the valve operation of the engine, causing periodic waviness (vibration) on the camshaft 1. However, the displacement due to the undulation of the camshaft 1 can be released by the curved track surface and the balls 7 in contact therewith.
Furthermore, an axial load acting on the camshaft 1 can be received by the rolling bearing 3, and the axial displacement of the camshaft 1 can be regulated. Therefore, in the conventional camshaft device using the sliding bearing shown in FIG. 7, the camshaft is provided with a flange portion 45 for axial restriction, and this flange portion 45 is formed by an inner flange portion (not shown) formed on the housing side of the engine. The axial displacement of the camshaft is regulated with the flange interposed therebetween, but the flange portion 45 can be made unnecessary. The conventional flange portion 45 and the inner flange portion on the housing side have friction due to sliding contact, and the friction loss has occurred during rotation. However, by using a ball bearing, loss due to such friction is eliminated. be able to.

  Further, the camshaft device of the present invention is not limited to the form shown in the figure, and may be of other forms within the scope of the present invention. In FIGS. However, these arrangements and quantities are not limited to these and can be changed.

It is a side view of the partial cross section which shows the camshaft apparatus which concerns on one Embodiment of this invention. It is an expanded sectional view which shows the principal part of FIG. It is a side view of the partial cross section which shows other embodiment of the camshaft apparatus of this invention. It is an expanded sectional view which shows the principal part of FIG. It is the graph which showed the relationship between the rotation speed of a rolling bearing and a sliding bearing, and friction torque. It is an expanded sectional view showing a roller bearing. It is sectional drawing which shows the conventional camshaft apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cam shaft 1a Outer surface 2 Cam 3 Rolling bearing 4 Inner ring 5 Outer ring 5a Outer surface 6 Inner ring raceway groove 8 Ring member 9 Pulley attachment part 10 Through hole 11 Roller bearing

Claims (9)

  A camshaft, a cam that is a separate body from the camshaft and has a through hole and is fitted on the camshaft, and a raceway ring made of an annular integral member, and rotates the camshaft A camshaft device comprising a rolling bearing that supports the camshaft.   The camshaft device according to claim 1, wherein the cam is fixed to the camshaft by fitting with a tightening margin.   3. The camshaft device according to claim 1, wherein the camshaft is configured such that a portion to which the cam is attached and a portion to which the rolling bearing is attached have the same diameter.   The camshaft device according to any one of claims 1 to 3, wherein the rolling bearing is a deep groove ball bearing.   The camshaft device according to any one of claims 1 to 4, wherein an inner ring raceway groove of the rolling bearing is formed on an outer peripheral surface of the camshaft.   The camshaft device according to any one of claims 1 to 5, wherein a ring member having elasticity is attached to an outer peripheral surface of an outer ring of the rolling bearing.   The cam according to any one of claims 1 to 6, wherein a disc for driving a camshaft is attached to the camshaft, and a portion of the camshaft near the disc is supported by a roller bearing. Shaft device.   In a method of assembling a camshaft device in which a plurality of cams and a plurality of rolling bearings are respectively disposed at predetermined positions in the axial direction of the camshaft, the cam separately from the camshaft and having a through hole, An assembly method of a camshaft device, wherein a rolling bearing is moved in an axial direction sequentially from the end portion of the linear camshaft to each predetermined position, and the cam and the rolling bearing are attached to the camshaft. .   9. The method of assembling a camshaft device according to claim 8, wherein the cam is fitted to the camshaft with a fastening margin in a through hole of the cam and fixed to the camshaft.

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