JP4009839B2 - Cam follower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cam follower used for an engine valve mechanism of an automobile or the like.
[0002]
[Prior art]
As an example of a cam follower used in an engine valve mechanism of an automobile or the like, a rocker arm 50 as shown in FIG. 7 is known (see, for example, Patent Document 1). This type of rocker arm 50 includes a pair of roller support walls 51 and 52 arranged substantially in parallel on the body. Support holes 53, 54 are formed by punching at intermediate positions in the longitudinal direction of the roller support walls 51, 52, and a support shaft 55 is passed between the support holes 53, 54. A roller 57 with which the cam is brought into rolling contact is provided through a roller 56.
[0003]
The rocker arm 50 having such a configuration functions to open and close a valve provided in the cylinder head by repeatedly tilting (swinging) with rotation of a cam installed at a predetermined position of the engine valve mechanism. Have
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-150910 (FIG. 1)
[0005]
[Problems to be solved by the invention]
In the conventional rocker arm 50, since the outer peripheral surface of the support shaft 55 requires a predetermined hardness, for example, induction hardening is performed to obtain the predetermined hardness. In this case, in order to prevent the support shaft 55 from rotating, the diameter of the support holes 53 and 54 formed in the support walls 51 and 52 is slightly smaller than the diameter of the support shaft 55 as shown in FIG. The support shaft 55 is press-fitted into the support holes 53 and 54 from one side. However, if it does so, the roller rolling contact surface which is the outer peripheral surface of the spindle 55 will be damaged.
[0006]
Further, in order to securely stop the support shaft 55 with the support holes 53 and 54 of the support walls 51 and 52, as shown in FIG. 9, one end of the support shaft 55 is slightly expanded in diameter. It is conceivable to form the portion 60. However, in order to form the step portion 60 on the support shaft 55 in this way, complicated processing is required.
[0007]
Therefore, as shown in FIGS. 10A, 10B, and 10C, after the support shaft 55 is inserted into the support holes 53, 54 formed in the support walls 51, 52, the end surface of the support shaft 55 is crimped to support the support shaft. It can be considered that the rotation of the support shaft 55 is prevented by pressing the end portion of the shaft 55 against the peripheral wall surface of the support hole 53.
[0008]
Specifically, as shown in FIG. 10A, the outer peripheral surface portion of the support shaft 55 where the needle rollers 56 are in rolling contact is subjected to, for example, induction hardening 61 to be cured to a predetermined hardness, thereby supporting the support. The end portion of the shaft 55 remains in an uncured state, and the support shaft 55 is inserted into the support holes 53 and 54 as shown in FIG. 10B, and the support shaft 55 is inserted as shown in FIG. Crimp the end face of. However, in this manner, the process of forming the hardened portion and the non-hardened portion on the support shaft 55 increases the number of steps and adds a caulking step, resulting in an increase in manufacturing cost.
[0009]
[Means for Solving the Problems]
The cam follower according to the present invention has a pair of support walls opposed to each other via a roller that a cam contacts and rolls, and a support hole formed in each of the support walls. A shaft, and a plurality of rollers interposed between the support shaft and the roller and rotatably supporting the roller around the support shaft, and the support shaft is formed in one support wall. The cam follower is non-rotatably provided at one end and the other end by being press-fitted into a support hole formed in the other support wall, and the one support hole is smaller in diameter than the diameter of the support shaft end. A small-diameter portion and a large-diameter portion that is larger in diameter than the end portion of the support shaft, and the large-diameter portion is provided in a portion corresponding to the load zone side on the support shaft on which the cam is disposed. In the state where the end portion of the support shaft is fitted to the small diameter portion of one of the support holes, The other support hole has a uniform diameter that is smaller than the diameter of the support shaft, and each end portion of the support shaft has a small diameter portion of one support hole. And is press-fitted into the other support hole and supported non-rotatingly around the axis.
[0010]
Specifically, the large diameter portion is provided in a portion corresponding to a load range on the support shaft in a semicircle on the load zone side.
[0011]
In manufacturing the cam follower having the above-described configuration, the support shaft is inserted from one support hole formed in one support wall toward the other support hole formed in the other support wall. At this time, since the large-diameter portion is larger than the diameter of the support shaft, the outer peripheral surface of the portion passing through the large-diameter portion on the support shaft is not damaged. And since this large diameter part is provided in the portion corresponding to the load zone side on the support shaft where the cam is arranged, the support shaft receives a load from the cam via the roller and the roller, and the roller Since the outer peripheral surface of the support shaft is not damaged in the zone, the roller can be prevented from being damaged.
[0012]
Since the concavo-convex portion in the radial direction is formed on the peripheral wall surface of the small-diameter portion, and the support shaft is press-fitted into the support hole so as to plastically deform the concavo-convex portion, the concavo-convex portion is plastically deformed by the shaft. The support shaft can be reliably prevented from rotating in the small-diameter portion by the amount that the portion where the large diameter portion is formed cannot prevent the support shaft from rotating.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a cam follower according to an embodiment of the present invention will be described with reference to the drawings, taking a rocker arm as an example.
[0014]
FIG. 1 is an exploded perspective view of a rocker arm, FIG. 2 is a side view of the rocker arm, and FIG. 3 is an enlarged side view of a main part.
[0015]
The rocker arm 1 is of an end pivot type and is provided in an OHC valve mechanism of an engine as shown in FIGS. Reference numeral 2 denotes a cam disposed at a predetermined position of the engine valve mechanism. The rocker arm 1 includes a roller 3 that a cam 2 contacts and rolls, and a pair of support walls 4 that face each other via the roller 3. And 5.
[0016]
A body 22 is formed by the support walls 4 and 5 and connecting walls 20 and 21 connecting the support walls 4 and 5 on both sides in the longitudinal direction. One connecting wall 20 is used as a pivot receiving portion with which the upper end portion of the lash adjuster 23 abuts, and the other connecting wall 21 is used as a valve stem inserting portion into which the upper end portion of the valve stem 24 is fitted.
[0017]
Both support walls 4 and 5 are formed with support holes 6 and 7 at intermediate portions in the longitudinal direction, respectively. The support shaft 8 is inserted into the support holes 6 and 7 so that the end portions 10a and 10b are supported in a non-rotating manner. The support shaft 8 is formed in substantially the same cross section in the axial direction. Further, the roller 3 is externally mounted on the support shaft 8 via a plurality of needle rollers 9 so as to be rotatable about the axis. The spindle 8 is set to a predetermined hardness so that the entire surface is hardened and is not damaged even when the roller 3 rolls.
[0018]
As shown in the enlarged side view of FIG. 3, one support hole 6 includes a small diameter portion 11 having a diameter R2 slightly smaller than a diameter R1 of the support shaft 8 (end portion 10a) with respect to the center O, and the support shaft 8. And a large diameter portion 12 having a slightly larger diameter R3. The other support hole 7 has a uniform diameter and is slightly smaller than the diameter of the support shaft 8.
[0019]
The difference between the diameter R2 of the small-diameter portion 11 and the diameter R3 of the large-diameter portion 12 is very small. In particular, the difference between the diameter R1 of the support shaft 8 and the diameter R3 of the large-diameter portion 12 is as described below. When the support shaft 8 is inserted into the support hole 6, the difference is set to a slight difference, for example, 50 μm to 0.1 mm, as long as the load zone 13 on the support shaft 8 does not have to contact.
[0020]
The large diameter portion 12 is provided at a portion corresponding to the load zone 13 side on the support shaft 8 where the cam 2 is disposed. More specifically, the large-diameter portion 12 includes a horizontal line 14 that passes through the center of the support hole 6 and is located above the support holes 6 and 7 and is centered on a vertical line 15 that passes through the center of the support holes 6 and 7. The left and right arc angles θ are each formed in a range corresponding to the load zone 13 of 30 ° to 90 °.
[0021]
That is, in the case of the rocker arm 1 provided in the OHC valve mechanism, the range in which the large diameter portion 12 is formed is from the cam 2 through the roller 3 and the needle roller 9 to the outer peripheral surface of the support shaft 8 where the load is substantially applied. The corresponding part in the axial direction. In addition, the continuous part of the small diameter part 11 and the large diameter part 12 is made into the stepped surface 16 which diameter-expands substantially along a radial direction.
[0022]
Next, a method for manufacturing the rocker arm 1 having the above configuration will be described. First, a single metal plate is punched into a predetermined shape, and portions corresponding to the support walls 4 and 5 are bent to form the support walls 4 and 5 and the connecting walls 20 and 21.
[0023]
Subsequently, both support holes 6 and 7 are formed in the support walls 4 and 5 by punching. At this time, a processing tool (punch) (not shown) having a different shape for each of the support holes 6 and 7 is used. That is, the shape of the tip of the processing tool for punching out one support hole 6 is such that one half circumference side has a larger diameter than the other half circumference side so that the shape of the support hole 6 becomes the above shape. . The shape of the tip of the processing tool for punching the other support hole 7 is formed in a substantially perfect circle.
[0024]
Then, in a state where the roller 3 having the needle rollers 9 mounted on the inner peripheral surface is disposed at the center position in the longitudinal direction between the support walls 4, 5, the support shaft 8 is formed from the support hole 6 formed in one support wall 4 to the other. The roller 3 is inserted through the inner diameter side of the roller 3 toward the support hole 7 formed in the support wall 5.
[0025]
By the way, one support hole 6 includes a horizontal line 14 passing through the center of the support hole 6 and is located above the support hole 6 so that the left and right arc angles θ about the vertical line 15 passing through the center of the support hole 6 are 30 ° to 30 ° respectively. The large-diameter portion 12 is formed with a range of 90 °. The diameter of the small diameter portion 11 is slightly smaller than the diameter of the support shaft 8.
[0026]
For this reason, when the support shaft 8 is inserted into one of the support holes 6, the outer peripheral surface of the support shaft 8 below the radial horizontal line is press-fitted into the small diameter portion 12 of the support hole 6. However, the outer peripheral surface of the substantially upper half of the support shaft 8 (the portion corresponding to the load zone 13) corresponds to the large-diameter portion 12 having a diameter larger than the diameter of the support shaft 8, so that the periphery of the large-diameter portion 12, that is, the support hole 6 The support hole 6 is inserted without contacting the wall surface. Therefore, there is no damage due to insertion in this portion.
[0027]
The support shaft 8 is further pushed in, and the other end portion 10 b of the support shaft 8 is press-fitted into the other support hole 7. By doing so, the end portions 10a and 10b of the support shaft 8 are prevented from rotating by the peripheral wall surfaces of the support holes 6 and 7, respectively, and are not rotated about the axis.
[0028]
The above is the manufacturing method of the rocker arm 1. The rocker arm 1 manufactured in this way is installed at a predetermined location in the OHC valve mechanism, and the outer peripheral cam surface of the cam 2 is brought into contact with the roller 3.
[0029]
When the cam 2 is rotated, the roller 3 rotates around the support shaft 8 via the needle roller 9 while receiving a load from the cam 2, and the rocker arm 1 swings around the upper end portion of the lash adjuster 23. Then, the valve stem 24 repeatedly moves up and down to open and close a valve (not shown).
[0030]
By the way, the support shaft 8 has a cylindrical shape, and a load zone 13 in which a load is applied to the support shaft 8 from the cam 2 through the roller 3 and the needle roller 9 is a rocker arm used for an OHC valve mechanism. 1 is considered to be the upper half of the horizontal line 14 (when the support shaft 8 and the support hole 6 are concentric) in the support shaft 8 even in the maximum range.
[0031]
Since one support hole 6 in this embodiment is formed in the shape as described above, even when the support shaft 8 is inserted into the support hole 6, the load zone 13 of the support shaft 8 is accompanied by the insertion. There is no bruising. Therefore, the needle roller 9 together with the roller 3 in a state where the load is applied rolls very smoothly in the load zone 13 of the support shaft 8.
[0032]
Further, since the outer peripheral surface of the needle roller 9 below the horizontal line 14 in the support shaft 8 is press-fitted into the support hole 6, it is considered that the outer peripheral surface of the roller 3 is damaged at that time. . However, since this region is a no-load zone, even when the needle roller 9 rolls, it is not strongly pressed against the outer peripheral surface, and therefore the outer peripheral surface of the needle roller 9 is damaged. Can be avoided. For this reason, the life of the rocker arm 1 can be extended.
[0033]
As described above, in the rocker arm 1 according to the embodiment of the present invention, the large diameter portion 12 is formed in the portion of the support hole 6 corresponding to the load zone 13 of the support shaft 8 and the support shaft 8 is inserted. In the load zone 13 of the support shaft 8, there is no generation of damage due to the insertion, and the needle roller 9 rolls smoothly on the outer peripheral surface of the support shaft 8 in the load range 13. The outer peripheral surface of the needle roller 9 below the horizontal line 14 of the support shaft 8 is press-fitted into the small diameter portion 12 of the support hole 6, so that the support shaft 8 rotates around one end 10 a by the small diameter portion 12. Stopped.
[0034]
Further, as in the prior art, the support shaft 8 is not subjected to a difficult process in which only a part thereof is cured and a part thereof is not cured, but the entire surface is subjected to a curing process, and the roller 3 rolls. Is set to a predetermined hardness so as not to be damaged, and the caulking step can be omitted. Therefore, processing is easy and the manufacturing cost of the rocker arm 1 can be reduced as compared with the conventional case.
[0035]
In the above-described embodiment, the small diameter portion 11 having a diameter R2 smaller than the diameter R1 of the support shaft 8 is formed in one support hole 6, and the one end portion 10a of the support shaft 8 has a function of preventing rotation at the small diameter portion 11. It was.
[0036]
However, since the small diameter portion 11 is a part of the peripheral wall of the support hole 6, when it is considered that the detent force with respect to the support shaft 8 is insufficient, for example, as shown in the side view of FIG. The concavo-convex portion 25 in the radial direction is formed on the peripheral surface. For example, the center of the concavo-convex portion 25 in the radial direction is formed so as to coincide with the diameter R 1 of the support shaft 8. In this case, the arrangement position and diameter of the large-diameter portion 12 and the formation range are the same as in the above embodiment.
[0037]
When the support shaft 8 is press-fitted into such a support hole 6, the uneven portion 25 is plastically deformed by the support shaft 8, and even if there is a large-diameter portion 12 that does not contact the support shaft 8 on the peripheral surface of the support hole 6. The shaft 8 can be reliably prevented from rotating at the one end portion 10a.
[0038]
5 and 6 are cross-sectional views when the large-diameter portion 12 in one support hole 6 is arranged on the left side in the drawing. Both figures show a modification of the other support hole 7, and the shape of one support hole 6 in one support wall 4 is the same as that of any of the above embodiments, and therefore one support hole 6 has the same shape. With respect to the relationship between the hole 6 and one end 10a of the support shaft 8, the same operational effects as in any of the above embodiments can be obtained.
[0039]
In FIG. 5, the support hole 7 is formed in a concave shape having a diameter slightly smaller than the diameter R <b> 1 of the support shaft 8 without penetrating the other support wall 5. Like this structure, even if the support hole 7 in the other support wall 5 is a recessed shape, the other end 10b of the support shaft 8 can be reliably prevented from rotating.
[0040]
Further, the support hole 7 in the other support wall 5 shown in FIG. 6 is enlarged in diameter as it is located from one side to the other side, and the one-side minimum diameter in the support hole 7 is the diameter R1 of the support shaft 8. It is formed slightly smaller than that. In the case of this configuration, when the support shaft 8 is press-fitted into the support hole 7, the other end portion 10 b of the support shaft 8 is mainly prevented by the one peripheral surface of the support hole 7.
[0041]
In each of the above embodiments, the rocker arm 1 is shown when used in an OHC valve mechanism, and the diameter-enlarged portion 12 in one support hole 6 is formed above the horizontal line 14. However, this enlarged diameter part 12 is formed in the position according to the load zone 13 in the spindle 8, and may differ according to the type of valve operating mechanism.
[0042]
Furthermore, in each said embodiment, although the rocker arm 1 was demonstrated to the example as a cam follower, it is not limited to this, It has the supporting wall which opposes, The insertion hole by which a spindle is inserted in this each supporting wall is provided. The cam follower is applicable if it has a structure in which the roller is rotatably supported by the support shaft via the roller, the roller receives a load from the cam, and the load acts on the support shaft via the roller.
[0043]
【The invention's effect】
As is clear from the above description, according to the present invention, it is possible to prevent damage to the load range on the support shaft and to extend the life of the cam follower. Further, since the entire surface of the support shaft can be cured, the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a rocker arm showing an embodiment of the present invention.
FIG. 2 is an overall side view of the same.
FIG. 3 is an enlarged side view of the main part of the same.
FIG. 4 is an enlarged side view of a main part of a rocker arm showing another embodiment.
FIG. 5 is a cross-sectional view showing another embodiment.
FIG. 6 is a side view showing still another embodiment.
FIG. 7 is an exploded perspective view showing a conventional rocker arm.
FIG. 8 is a cross-sectional view showing the way in which the support shaft is similarly inserted into the support hole.
FIG. 9 is a cross-sectional view showing another conventional example.
FIG. 10 is an explanatory view showing still another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rocker arm 2 Cam 3 Roller 4, 5 Support wall 20, 21 Connecting wall 22 Body 6, 7 Support hole 8 Support shaft 9 Needle roller 11 Small diameter part 12 Large diameter part

Claims (3)

A pair of support walls facing each other via rollers that abut and roll on the cam; a support shaft having ends supported by support holes formed in the support walls; A plurality of rollers interposed between the roller and the roller and rotatably supporting the roller around the support shaft,
The support shaft is a cam follower that is non-rotatably provided at one and the other ends by being press-fitted from a support hole formed in one support wall into a support hole formed in the other support wall,
The one support hole includes a small-diameter portion that is smaller than the diameter of the support shaft end portion and a large-diameter portion that is larger than the support shaft end portion, and the cam is disposed in the large-diameter portion. So that a gap is formed between the end of the support shaft and the large diameter portion in a state where the end portion of the support shaft is fitted to the small diameter portion of one of the support holes. Has been
The diameter of the other support hole is uniform and smaller than the diameter of the support shaft.
Each end of the support shaft is press-fitted into a small diameter portion of one support hole and the other support hole, and is supported non-rotatingly around the axis . The cam follower according to claim 1,
The cam follower according to claim 1, wherein the large diameter portion is provided in a portion corresponding to a load range on a support shaft in a semicircle on a load zone side. The cam follower according to claim 1 or 2,
A cam follower, wherein a concavo-convex portion in a radial direction is formed on a peripheral wall surface of the small-diameter portion, and a support shaft is press-fitted into the support hole so as to plastically deform the concavo-convex portion.

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