WO2006077914A1

WO2006077914A1 - Rotary assembly

Info

Publication number: WO2006077914A1
Application number: PCT/JP2006/300712
Authority: WO
Inventors: Tamotsu Yamamoto; Mitsuyoshi Teramura
Original assignee: Otics Corporation
Priority date: 2005-01-20
Filing date: 2006-01-19
Publication date: 2006-07-27

Abstract

A rotary assembly, wherein the cam piece (3) of a camshaft (1) comprises a circular base circle part (31) surrounding a drive shaft (2) in a mounted state. A pair of sleeve parts (33) extending from both end faces of the base circle part (31) in its insertion direction are formed on the cam piece. Inner holes (34) are formed in the sleeves (33) at the contact parts on the outer peripheral surface of the drive shaft (2), and a plurality of grooves (35) extending in a drive shaft (2) insertion direction are formed in the inner hole (34). Also, projected lines (37) extending in the drive shaft (2) insertion direction are formed in the inner hole (34), and a keyway (21) engaged with one of the projected lines (37) is formed in the outer peripheral surface of the drive shaft (2). By engaging the projected line (37) with the keyway (21) in the enlarged state of the inner hole (34) by heating the cam piece (3), the drive shaft (2) is inserted into the inner hole (34) while positioning in its rotating direction to firmly fix the cam piece (3) onto the drive shaft (2).

Description

Specification

Rotating assembly

Technical field

The present invention relates to a rotary assembly in which a rotary member is fixed on a shaft.

Background art

[0002] An inner hole having a stepped portion is formed in a cam piece, and a pipe-shaped shaft is inserted into the inner hole, and then a high-pressure fluid is injected into the shaft to bulge outwardly. There has been a related art related to a camshaft in which a cam piece is fixed on a shaft by being accommodated in a stepped portion of a hole (see, for example, Patent Document 1). According to this technique, the portion accommodated in the stepped portion of the shaft serves as a pulling force, and the fixing strength between the cam piece and the shaft can be improved.

Patent Document 1: Japanese Patent Laid-Open No. 2003-314576

Disclosure of the invention

Problems to be solved by the invention

[0003] However, in order to form the camshaft according to the above-described prior art, a high-pressure fluid must be injected into the shaft, and a high-pressure fluid source or a shaft sealing device is required for manufacturing. And the like, as well as a lot of labor and man-hours. There was a method to heat the camshaft and expand the inner hole without injecting high pressure, and then insert the shaft into the inner hole to cool and fix it, but the inner hole was pressed from the shaft after fixing. As a result, the surface shape of the cam piece was affected and changed, and in order to correct this, the surface of the cam piece had to be polished.

In addition, in the conventional camshaft described above, it is necessary to use a precise jig in the process of fixing both the positioning means in the rotational direction between the cam piece and the shaft. It included problems in performance and manufacturing cost.

[0004] The present invention has been completed based on the above situation, and an object thereof is to provide a rotating assembly capable of easily fixing a rotating member on a shaft.

Means for solving the problem As a means for achieving the above object, the rotating body according to the present invention includes a rotating assembly in which the rotating member is fixed on the shaft by inserting the shaft into the inner hole of the rotating member. The diameter of the hole is made smaller than the outer diameter of the insertion portion of the shaft, and a plurality of grooves and protrusions extending in the insertion direction are formed on one side of the inner hole and the outer peripheral surface of the shaft. On the other side, a key groove that engages with the protrusion is formed, and after heating the rotating member to expand the diameter of the inner hole, the protrusion and the key groove are engaged with each other. While positioning in the rotational direction, the shaft is inserted into the inner hole, and after that, the shaft is cooled to reduce the diameter of the inner hole again, and the other side of the outer surface of the inner hole and the shaft is the other side. Pressed from the side and raised It enters in the groove by, characterized in was constructed in which both are fixed.

In this way, the other side force of the inner hole and the outer peripheral surface of the shaft is pressed from the other side and rises to enter the groove, and both are fixed. Thus, the rotating member can be easily fixed firmly on the shaft. Also, when attaching the rotating member to the shaft, it is possible to perform positioning in the rotating direction by engaging the ridge with the keyway, so no jig etc. is required, and its assembly workability The manufacturing cost can be reduced. Further, the shaft and the rotary member are firmly fixed in the rotation direction by the engagement between the protrusion and the key groove.

The following configuration is preferable as an embodiment of the present invention.

(1) In the rotating member, a drive shaft is inserted into the inner hole in which the groove is formed, and a base circle that surrounds the drive shaft in an attached state, and is continuous with the base circle. The cam piece has a cam profile projecting outward, and the cam shaft is formed by fixing a plurality of the cam pieces on the drive shaft.

As a result, when the cam piece is fixed to the drive shaft, the drive shaft enters the groove, so that the pressing force received by the cam piece from the drive shaft is relieved, and the shape change of the cam profile can be prevented.

(2) In the device described in (1), the cam piece is attached to the drive shaft from the both ends of the base circle and the cam profile. A pair of sleeve portions extending in the longitudinal direction of the shaft, and the inner holes having the grooves are formed in contact portions of the sleeve portions with the outer peripheral surface of the drive shaft, and the base circle portion and the base portion It is assumed that a large-diameter relief portion is formed at a portion located inside the cam profile so as not to contact the outer peripheral surface of the drive shaft. As a result, the cam piece is firmly fixed to the drive shaft by the inner hole of the sleeve portion, and the cam profile for controlling the operation amount of the valve member of the engine by the relief portion formed inside the cam blower. The shape of the cam can be prevented from changing due to the cam piece being fixed to the drive shaft.

(3) In the structure described in (1) or (2), a plurality of key grooves are formed continuously in the length direction on the outer peripheral surface of the drive shaft, and the protrusions are provided at different positions. Each of the cam pieces is fixed to the drive shaft so that each of the protrusions engages with the key groove.

As a result, it is possible to easily form a key groove that engages with a plurality of protrusions on the drive shaft, and the drive shaft has a single rotation of the phase in the rotational direction with respect to the drive shaft. A plurality of different cam pieces can be attached.

Moreover, you may comprise as another related rotary body as follows. In the rotating assembly in which the rotating member is fixed on the shaft by inserting a shaft into the inner hole of the rotating member, the rotating member surrounds the shaft in a state in which the rotating member is attached; and the rotating unit A pair of sleeve portions extending in the length direction of the shaft is provided from both end surfaces of the shaft, the inner hole is formed in the contact portion of the sleeve portion with the outer peripheral surface of the shaft, and the rotating portion A large-diameter relief portion is formed at a portion located inward of the shaft so as not to contact the outer peripheral surface of the shaft, and the diameter of the inner hole is formed smaller than the outer diameter of the insertion portion of the shaft. A plurality of grooves extending in the insertion direction are formed on one side of the inner hole and the outer peripheral surface of the shaft,

After the rotating member is heated to expand the diameter of the inner hole, the shaft is inserted into the inner hole, and thereafter, the shaft is cooled to reduce the diameter of the inner hole again. It is characterized in that the other side of the outer peripheral surface of the foot is pressed from the other side and rises to enter the groove, and both are fixed. Furthermore, as an embodiment of another related rotating body, the following configuration is preferable.

(1) The groove is formed in the inner hole, and the rotating part is configured by a base circle part that surrounds the shaft in an attached state, and a cam profile that is continuous with the base circle part and protrudes outward. Thus, the rotating member is a cam piece, and the cam shaft is formed by fixing a plurality of the cam pieces on the shaft. Thereby, the shape of the rotating part can be prevented from changing due to the fixing of the rotating member to the shaft.

(2) In the one described in (1), a protrusion extending in the insertion direction is provided in the inner hole, and a key groove that engages with the protrusion is formed on the outer peripheral surface of the shaft. When the shaft is inserted into the inner hole, the protrusion and the key groove are engaged to perform positioning in the rotational direction.

Thus, by positioning in the rotational direction, a jig or the like is not required, the assembly workability can be improved, and the manufacturing cost can be reduced. Further, the shaft and the cam piece are firmly fixed in the rotational direction by the engagement between the protrusion and the key groove.

(3) In the device described in (2), a plurality of the cam pieces in which the key grooves are continuously formed in the length direction on the outer peripheral surface of the shaft and the protrusions are provided at different positions. Each of the protrusions is fixed to the shaft so as to engage with the keyway.

As a result, a key groove that engages with a plurality of protrusions can be easily formed on the shaft, and there are a plurality of key grooves on the shaft, but the shaft has a plurality of different rotational phases. A cam piece can be attached.

The invention's effect

[0007] According to the rotating body of the present invention, the rotating member can be easily fixed on the shaft.

Brief Description of Drawings

FIG. 1 is a partial external view of a camshaft.

2 is a cross-sectional view of FIG.

FIG. 3 is a front view of the cam piece shown in FIG. 1. FIG. 4 is a perspective view showing a place where a drive shaft is inserted into a cam piece.

FIG. 5 is a cross-sectional view taken along the line AA in FIG.

FIG. 6 is an enlarged view of the main part of FIG.

FIG. 7 is a main part enlarged view (A) showing a first modification, a main part enlarged view (B) showing a second modification, and a main part enlarged view (C) showing a third modification.

Explanation of symbols

1 ... 'Camshaft

2 'drive shaft

3 '

21-… Keyway

31-… Base circle

32-… Cam Profi

33-… Sleeve part

34-… Inner hole

35-… Groove

37-… Projections

38-… Relief

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to FIGS. 1 to 7. As shown in FIG. 1, a camshaft 1 that is a rotating assembly according to this embodiment is formed by fixing a plurality of cam pieces 3 on a drive shaft 2. The drive shaft 2 is made of a pipe material made of carbon steel or alloy steel such as STKM material, and a pulley 4 on which an engine timing belt (not shown) is stretched is attached to one end of the drive shaft 2. The pulley 4 may be integrally formed with the drive shaft 2. Further, a key groove 21 having a substantially rectangular cross section is formed on the outer peripheral surface of the drive shaft 2 in a continuous manner in the length direction.

[0011] The cam piece 3 is formed of a sintered material obtained by press-molding metal powder of carbon steel or alloy steel containing Cr and V in a mold and sintering at high temperature. As shown in FIGS. 1 to 3, a part of the drive shaft 2 is attached to the cam piece 3 while being attached to the drive shaft 2. A circumferential base circle 31 is formed so as to surround it, and a cam profile 32 protruding outward is formed so as to be continuous with the base circle 31 (the base circle 31 and the cam). The rotating part is constituted by the profile 32). Each cam piece 3 has a pair of sleeve portions 33 extending from both end surfaces of the base circle portion 31 and the cam profile 32 in the length direction of the drive shaft 2. An inner hole 34 passes through a portion of the sleeve portion 33 that contacts the outer peripheral surface of the drive shaft 2, and the inner diameter d (shown in FIG. 3) of the inner hole 34 is the insertion portion of the drive shaft 2. It is formed smaller than the outer diameter.

[0012] In the inner hole 34, a plurality of grooves 35 are formed over the entire circumference so as to extend in a direction in which the drive shaft 2 is inserted into the cam piece 3 (described later). The grooves 35 are formed so as to be evenly arranged on the inner hole 34. In the cam piece 3 shown in FIG. 3, since the cross section of each protrusion 36 arranged between the grooves 35 is formed in a rectangular shape, the cross section of the groove 35 is also formed in a rectangular shape. Projection 36A with trapezoidal cross section as shown in Fig. 7 (A), Projection 36B with triangular cross section as shown in Fig. 7 (B), or Projection with circular cross section as shown in Fig. 7 (C) By adopting 36C, even if the cross-sectional shapes of the grooves 35A, 35B, and 35C disposed between them are appropriately changed, the same effect described later can be obtained.

In addition, in the inner hole 34 of each cam piece 3, a protrusion 37 protruding inward extends in the insertion direction of the drive shaft 2. One protrusion 37 is arranged between the grooves 35, and the cross section is formed in a substantially rectangular shape so as to engage with the key groove 21 formed on the drive shaft 2 described above. It protrudes inward higher than the protruding part 36 of. In FIG. 1, the cam piece 3 located at the center and the cam piece 3 located at the left end are provided with the same protrusions 37 on the inner hole 34. It is formed at a different position from the two. As a result, while the number of the keyway 21 on the drive shaft 2 is one, the cam piece 3 at the right end is fixed to the other two things while being fixed to the drive shaft 2. This makes it possible to change the timing of operation of the intake and exhaust valves of the abutting engine relative to the others.

[0014] Further, as shown in FIG. 2, the cam piece 3 has a large diameter so that it does not come into contact with the outer peripheral surface of the drive shaft 2 at a portion positioned inward of the base circle portion 31 and the cam blow feel 32 of each cam piece 3. An escape portion 38 is formed over the entire circumference of the drive shaft 2. The hardness of at least the inner hole 34 of the cam piece 3 is not limited to this, but is Hv 350 or higher, and is higher than the hardness (Hvl 50 to 200) of the outer peripheral surface of the drive shaft 2. The grooves 35 and the protrusions 37 may be formed simultaneously with the outer shape when the cam piece 3 is formed, but may be formed by machining after the outer shape of the cam piece 3 is formed, and then the cam piece 3 may be sintered. .

Next, a method for fixing the cam piece 3 on the drive shaft 2 will be described. First, the inner diameter d of the inner hole 34 is expanded by heating the cam piece 3 in which the plurality of grooves 35 are formed in the inner hole 34 to a high temperature of 200 ° C. or more. In this state, as shown in FIG. 4, by engaging the protrusion 37 of each cam piece 3 and the key groove 21 of the drive shaft 2, the inner holes 34 are positioned while positioning both in the rotational direction. Insert the drive shaft 2 in its length direction (shrink fit). Since the inner hole 34 is expanded in diameter by heating, the drive shaft 2 can be inserted smoothly.

Here, after considering the position of each cam piece 3 on the drive shaft 2 and setting the length of the sleeve portion 33 in the insertion direction, as shown in FIG. When inserting the force piece 3, the end of the sleeve 33 on the left side of the pulley 4 is brought into contact with the end surface of the pulley 4 via, for example, a spacer 5A formed of a synthetic resin material to a predetermined thickness. Insert the cam piece 3 located at the left end. Next, the end portion of the left sleeve portion 33 of the cam piece 3 located at the center is disposed on the end surface of the right sleeve portion 33 of the cam piece 3 through a spacer 5B formed of the same synthetic resin material. Insert the cam piece 3 in the center so that the Similarly, by inserting each cam piece 3 into the drive shaft 2 with the spacer 5B interposed between the sleeve portions 33 of adjacent cam pieces 3, the sleeve portions 33 of the respective cam portions 3 are inserted. Depending on the length, the cam piece 3 can be accurately positioned on the drive shaft 2 in the axial direction. The spacers 5A and 5B described above are fixed to each other between the sleeve portions 33 of adjacent cam pieces 3 by removing each cam piece 3 from the drive shaft 2 after the cam pieces 3 are fixed on the drive shaft 2. A gap is formed to prevent the same contact between the sleeve 33 and the stress between them.

[0017] Next, when the drive shaft 2 is cooled in a state of being inserted into the inner holes 34 of the plurality of cam pieces 3, The diameter of the inner hole 34 that has been expanded is reduced again, and the outer peripheral surface of the drive shaft 2 starts to be pressed inward. Accordingly, the outer peripheral surface force of the drive shaft 2 having a hardness lower than that of the inner hole 34 is pressed by the inner hole 34, and the portion facing the groove 35 not restrained by the inner hole 34 rises outward, and each of the parts moves into the groove 35. Enter (shown in Fig. 5 and Fig. 6). Thereby, the drive shaft 2 and the plurality of cam pieces 3 are firmly fixed to each other, and the camshaft 1 is completed. The camshaft 1 is rotatably fixed at a cylinder head (not shown) of the internal combustion engine, and controls the operation of a supply / exhaust valve that contacts the cam profile 32 by rotating.

[0018] According to the present embodiment, the outer peripheral surface of the drive shaft 2 is pressed from the inner hole 34 and rises, and both enter the groove 35 to be fixed. The cam piece 3 can be firmly fixed on the drive shaft 2 by a simple method. Further, when the cam piece 3 is fixed to the drive shaft 2, the drive shaft 2 enters the groove 35, so that the pressing force received by the cam piece 3 from the drive shaft 2 is relaxed, and the shape of the cam profile 32 may change. Wow!

In addition, the cam piece 3 includes a base circular portion 31 and a pair of sleeve portions 33 extending in the length direction of the drive shaft 2 from both end surfaces of the cam profile 32 in a state of being attached to the drive shaft 2, and this sleeve portion An inner hole 34 having a groove 35 is formed in a contact portion of the drive shaft 2 with the outer peripheral surface of the drive shaft 2, and a portion of the drive shaft 2 is located inward of the base circle portion 31 and the cam profile 32. Since the large-diameter relief portion 38 is formed so as not to contact the outer peripheral surface, the cam piece 3 is firmly fixed to the drive shaft 2 by the inner hole 34 of the sleeve portion 33 and the cam profile 32 By the relief part 38 formed on the side, the cam profile 32's shape force for controlling the operation amount of the engine valve member can be further prevented from changing due to the cam piece 3 being fixed to the drive shaft 2. wear.

[0020] Further, when the cam piece 3 is attached to the drive shaft 2, the protrusion 37 and the key groove 21 can be engaged to perform positioning in the rotation direction, so that a jig or the like is not required. The assembling workability can be improved and the manufacturing cost can be reduced. Further, due to the engagement between the protrusion 37 and the key groove 21, the drive shaft 2 and the cam piece 3 are firmly fixed in the rotation direction. Further, on the outer peripheral surface of the drive shaft 2, a plurality of cam pieces 3 each having a key groove 21 formed continuously in the length direction and protrusions 37 at different positions are respectively provided. The key groove 21 that engages with the plurality of protrusions 37 can be easily formed on the drive shaft 2 by being fixed to the drive shaft 2 so that the protrusions 37 of the protrusion are engaged with the key groove 21. . In addition, a single cam groove 21 on the drive shaft 2 can be mounted on the drive shaft 2 with a plurality of cam pieces 3 having different rotational phases.

The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and are within the scope not departing from the gist other than the following. Various modifications can be made.

(1) The grooves and protrusions may be formed on the outer peripheral surface side of the drive shaft.

(2) The present invention can be applied to all types of rotating assemblies such as a steering shaft or a transmission counter gear that is not limited to a camshaft.

(3) A member separate from the cam piece may be attached to the cam piece to form a protrusion.

(4) If a plurality of key grooves are formed on the outer peripheral surface of the drive shaft for each cam piece to be attached, the strength of each key groove can be reduced.

(5) The present invention may be applied to a journal tube fixed on a drive shaft that includes only a cam piece and engaged with a bearing.

Claims

The scope of the claims

[1] By inserting the shaft into the inner hole of the rotating member, the rotating assembly having the rotating member fixed on the shaft is inserted into the rotating assembly.

A diameter of the inner hole is formed smaller than an outer diameter of the insertion portion of the shaft, and a plurality of grooves and ridges extending in the insertion direction are formed on one side of the inner hole and the outer peripheral surface of the shaft. Formed, a keyway is formed on the other side to engage with the protrusion,

After heating the rotating member to expand the diameter of the inner hole, the shaft is inserted into the inner hole while positioning the rotation direction by engaging the protrusion and the key groove, Thereafter, these are cooled to reduce the diameter of the inner hole again, and the other side of the inner hole and the outer peripheral surface of the shaft is pressed from the other side and rises into the groove, and both are fixed. A rotating assembly characterized by that.

[2] In the rotating member, a drive shaft is inserted into the inner hole in which the groove is formed, and a base circle that surrounds the drive shaft in an attached state, and is continuous with the base circle and outward 2. The rotating assembly according to claim 1, wherein the rotating shaft assembly is a camshaft having a cam profile projecting from the camshaft, wherein the camshaft is formed by fixing a plurality of the cam pieces on the driving shaft.

[3] The cam piece includes a pair of sleeve portions extending in a length direction of the drive shaft from both end surfaces of the base circle portion and the cam profile in a state of being attached to the drive shaft. The inner hole having the groove is formed in a contact portion of the drive shaft with the outer peripheral surface of the drive shaft. 3. The rotary assembly according to claim 2, wherein a large-diameter relief portion is formed so as not to contact the outer peripheral surface.

[4] On the outer peripheral surface of the drive shaft, the key grooves are formed continuously in the length direction, and a plurality of the cam pieces are provided with the protrusions at different positions. The rotary assembly according to claim 2 or 3, wherein the rotary assembly is fixed to the drive shaft so as to be engaged with a key groove.

[5] By inserting the shaft into the inner hole of the rotating member, the rotating assembly in which the rotating member is fixed on the shaft, The rotating member includes a rotating portion that surrounds the shaft in an attached state, and a pair of sleeve portions that extend in the length direction of the shaft from both end surfaces of the rotating portion, and an outer periphery of the shaft of the sleeve portion. The inner hole is formed in the abutting portion on the surface, and a large-diameter relief portion is formed in a portion located inward of the rotating portion so as not to abut on the outer peripheral surface of the shaft. The inner hole has a diameter smaller than the outer diameter of the insertion portion of the shaft, and a plurality of grooves extending in the insertion direction are formed on one side of the inner hole and the outer peripheral surface of the shaft. And

After the rotating member is heated to expand the diameter of the inner hole, the shaft is inserted into the inner hole, and thereafter, the shaft is cooled to reduce the diameter of the inner hole again. A rotating assembly characterized in that the other side of the outer peripheral surface of the foot is pressed and raised from the other side to enter the groove and both are fixed.

[6] The groove is formed in the inner hole, and the rotating portion is configured by a base circle portion that surrounds the shaft in an attached state, and a cam profile that is continuous with the base circle portion and protrudes outward. 6. The rotating assembly according to claim 5, wherein the rotating member is a cam piece, and the cam shaft is formed by fixing a plurality of the cam pieces on the shaft.

[7] The inner hole is provided with a ridge extending in the insertion direction, and a key groove that engages with the ridge is formed on the outer peripheral surface of the shaft, and the shaft is inserted into the inner hole. 7. The rotating assembly according to claim 6, wherein positioning in the rotation direction is performed by engaging the protrusion and the key groove when the protrusion is engaged.

[8] On the outer peripheral surface of the shaft, the key groove is formed continuously in the length direction, and the plurality of cam pieces are provided with the protrusions at different positions. 8. The rotating assembly according to claim 7, wherein the rotating assembly is fixed to the shaft so as to be engaged with a key groove.