JP5332642B2 - Cam follower device - Google Patents

Description

  The present invention relates to a cam follower device that is incorporated in a valve mechanism of an engine used for driving an automobile, etc., and reduces the friction of the valve mechanism to reduce the fuel consumption rate during engine operation. Regarding improvements. Specifically, a structure with a light alloy rocker arm that achieves a structure with excellent reliability and durability by reducing the flow resistance of the lubricating oil and improving the wear resistance. Is.

  For example, a cam follower device described in Patent Documents 1 to 3 is incorporated in the valve mechanism of the engine. FIG. 4 shows an example of the conventional structure described in Patent Document 2 among them. FIG. 4 shows a part of a valve mechanism that reciprocates the valve body 2 (intake valve or exhaust valve) based on the reciprocal swing of the rocker arm 3 as the camshaft 1 rotates. The rocker arm 3 supports a middle portion in the length direction (left-right direction in FIG. 4) by a support shaft 4 so as to be swingable and displaceable. A cylindrical roller 5 is rotatably supported at one end in the length direction of the rocker arm 3 (right end in FIG. 4). For this purpose, a pivot 6 parallel to the support shaft 4 is provided at one end of the rocker arm 3 in the longitudinal direction, and the roller 5 is rotated around the pivot 6 via a radial bearing 7 such as a needle bearing. Supports freely. When the engine is in operation, the rocker arm 3 reciprocally swings around the support shaft 4 as the camshaft 1 rotates, and the other end of the rocker arm 3 in the longitudinal direction is abutted against the valve. The body 2 reciprocates in the axial direction.

  A portion that rotatably supports the roller 5 at one end portion in the lengthwise direction of the rocker arm 3 is configured as shown in FIGS. That is, a pair of support plate portions 8, 8 are provided at one end in the length direction of the rocker arm 3 so as to be separated in the width direction of the rocker arm 3. These support plate portions 8 and 8 have their respective tip portions as free ends that are not restrained by other portions. Then, both end portions of the pivot 6 are fitted into the concentric support holes 9 and 9 formed in the both support plate portions 8 and 8, and further, the portions closer to the outer diameter of the both end portions are plastically deformed outward in the diameter direction. The caulking portions 10, 10 formed in this manner are pressed against the chamfered portions 11, 11 formed at the peripheral edges of the support holes 9, 9, and the pivot 6 is placed between the support plate portions 8, 8. It is fixed in a state of hanging. Further, the roller 5 is rotatably supported around the pivot 6 via the radial bearing 7.

  The rocker arm 3 is made of a light alloy such as an aluminum alloy for weight reduction, while the needles 12 and 12 constituting the roller 5, the pivot 6 and the radial bearing 7 are for ensuring strength. In addition, it is made of an iron-based alloy such as bearing steel. In order to prevent the inner surfaces of the support plate portions 8, 8 facing each other from being worn by friction with the needles 12, 12 and the axial end surface of the roller 5. Washers 13a and 13b are provided as shown in 5-6. Of these, the washers 13a and 13a shown in FIG. 5 prevent only wear by the end surfaces of the needles 12 and 12, and the washers 13b and 13b shown in FIG. This also prevents wear due to the end face of the steel.

  When assembling the cam follower device as described above, harmful deformation occurs in the support plate portions 8 and 8 along with the caulking and fixing of the pivot 6, and as a result, from the aspect of ensuring the reliability and durability of the cam follower device. It can be disadvantageous. This point will be described with reference to FIG. In order to fix the pivot 6 in a state where it is spanned between the support plate portions 8 and 8, first, as shown in FIG. It is located inside the support holes 9, 9 provided in both support plate portions 8, 8. In addition, this pivot 6 hardens and hardens the outer peripheral surface in the axial direction intermediate portion which becomes the inner ring raceway of the radial bearing 7, and both end portions to be caulked and fixed are left without being hardened. Then, caulking punches are pressed against the outer diameter portions of both ends of the pivot 6, and the outer diameter portions of both ends of the pivot 6 are plastically deformed radially outward to form the caulking portions 10, 10. And the outer peripheral surface of these both crimping parts 10 and 10 is pressed on the chamfering parts 11 and 11 formed in the opening peripheral part of the said both support holes 9 and 9. FIG.

  In this way, when the pivot 6 is fixed so as to be spanned between the two support plate portions 8, 8, forces are applied to the support plate portions 8, 8 in a direction approaching each other. Since these support plate portions 8 and 8 are so-called cantilever support structures in which the tip portions are not constrained, the tip portions of the support plate portions are based on the above force by δ in FIG. It may be deformed in the approaching direction. As a result, the thickness of the gaps 14 and 14 between the inner surfaces of the front ends of the support plate portions 8 and 8 and both end surfaces in the axial direction of the roller 5 is reduced. If the thicknesses of both the gaps 14 and 14 are reduced, there is a possibility that the lubricating oil for lubricating the cam follower device may not be smoothly distributed. For example, when supplying this lubricating oil through the lubricating oil supply path provided inside the rocker arm 3 and having a downstream end opened to the portion 15 between the both support plate portions 8, 8, both the gaps 14, 14 When the thickness of the lubricant becomes small, the back pressure related to the flow path of the lubricating oil becomes large, and the flow rate of the lubricating oil passing through the cam follower device may be insufficient.

  As a technique for solving such a problem, Patent Document 2 discloses that the distance between the inner side surfaces of a pair of support plate portions is in a state before the both end portions of the pivot are caulked and fixed. A technique for inclining in a direction that widens toward the tip is described. According to such improved prior art, by properly regulating the inclination angle, the inner side surfaces of the two support plate portions can be made substantially parallel to each other in a state where both ends of the pivot shaft are fixed. The above problem can be solved. However, only the conventional technique described in Patent Document 2 cannot suppress wear on the inner side surfaces of the two support plate portions based on friction with the axial end surfaces of the needle and the roller. In order to suppress this wear, it is necessary to provide washers 13a and 13b as shown in FIGS. The operation of assembling these washers 13a and 13b together with the roller and needle around the pivot is troublesome, and increases the manufacturing cost of the cam follower device. In addition, although the structure which connects a right and left washer is described in patent document 3, this washer is a function which prevents that a pair of support plate part becomes non-parallel based on the caulking fixation of a pivot. Do not have.

JP-A-6-129433 Japanese Patent Laid-Open No. 10-176509 A microfilm of Japanese Utility Model No. 63-161507 (Japanese Utility Model Application No. 2-80703)

  In view of the circumstances as described above, the present invention has a structure including a light alloy rocker arm, and has excellent reliability and durability by reducing the flow resistance of the lubricating oil and improving the wear resistance. The present invention was invented to realize a cam follower device having the characteristics.

The cam follower device of the present invention includes a rocker arm, a pair of support plate portions, a pivot, and a roller, like the conventionally known cam follower device.
Of these, the rocker arm is made of a light alloy such as an aluminum alloy and swings and displaces around a support shaft provided in the middle portion in the length direction.
Further, the both support plate portions are provided at one end portion in the length direction of the rocker arm in a state of being separated in the width direction of the rocker arm, and the respective tip portions are used as free ends that are not restrained by other portions. Yes.
Further, the pivot is parallel to the support shaft, and both ends are fitted into concentric support holes formed in the both support plate portions, and the outer diameter portions of the both ends are radially outward. It is fixed in a state of being stretched between the two support plate portions by being plastically deformed in the direction and pressing it toward the opening peripheral edge portions of the two support holes.
Further, the roller is cylindrical and is rotatably supported around the pivot shaft.

In particular, in the cam follower device of the present invention, a reinforcing bracket is assembled between the two support plate portions.
This reinforcing bracket is made of a metal having higher rigidity than the light alloy constituting the rocker arm, such as an iron-based alloy, and a pair of holding plate portions provided in a state of being separated from each other in the width direction of the rocker arm. The end portions are connected by a connecting plate portion.
Such a reinforcing bracket is assembled in a state in which the opposite outer surfaces of the holding plate portions are pressed against the mutually opposing inner surfaces of the supporting plate portions.
Furthermore, the downstream end opening of the lubricating oil supply path provided inside the rocker arm is present in the portion between the two support plate portions in the lengthwise end surface of the rocker arm, and the reinforcement bracket is connected. A through hole is formed in a part of the plate portion that matches the downstream end opening.

Preferably, when carrying out the present invention as described above, it is preferable to harden a nitride layer or the like on at least the inner side surfaces of the holding plate portions facing each other, as in the invention described in claim 2. Form a layer.
Alternatively, as in the invention described in claim 3, the mutually opposing inner side surfaces of the both holding plate portions of the reinforcing bracket and the axial end surface of the roller are directly opposed to each other.

According to the present invention configured as described above, the structure including the rocker arm made of light alloy has excellent reliability and durability by reducing the flow resistance of the lubricating oil and improving the wear resistance. Can be realized.
First, the flow resistance of the lubricating oil can be reduced by restraining the pair of support plate portions provided on the rocker arm so as not to be displaced toward each other by the pair of restraint plate portions constituting the reinforcing bracket. . With this configuration, when plastically deforming both end portions of the pivot shaft so as to fix the pivot shaft between the two support plate portions, the tip portions of the both support plate portions are deformed in a direction approaching each other. I can suppress things. As a result, it is possible to prevent the flow resistance from being reduced by preventing the gap between the inner side surfaces of the front end portions of both the support plate portions and both end surfaces in the axial direction of the rollers from becoming too narrow.
In particular, in the structure for circulating the lubricating oil through hole formed in the connecting plate portion of the reinforcing bracket from the lubricating oil supply path provided inside said rocker arm, back against the flow of the lubricating oil discharged from the through hole The effect of suppressing the pressure and reducing the flow resistance is great.

In addition, the wear resistance is improved by reducing the inner surface of the both support plates made of light alloy, which is higher in rigidity than light alloys such as ferrous metals, and therefore harder and less likely to wear. It can be achieved by covering with a plate part.
For this reason, as in the invention described in claim 3, even if the washer for preventing wear is omitted and the inner side surfaces of the both pressing plate portions and the axial end surface of the roller are directly opposed to each other, sufficient resistance is obtained. Abrasion can be secured.
In particular, the wear resistance can be further improved by forming a hardened layer such as a nitrided layer on the inner side surfaces of the two restraining plate portions as in the invention described in claim 2.

The figure equivalent to the II cross section of FIG. 4 which shows the 1st example of embodiment of this invention. The reinforcement bracket is taken out and shown, (A) is a view as seen from the side of FIG. 1, (B) is a cross-sectional view of (A), (C) is an enlarged view of section C of (B). The figure similar to FIG. 1 which shows the 2nd example of embodiment of this invention. The partial cutaway side view of the valve mechanism of the engine incorporating the cam follower device used as the object of the present invention. 4 is a sectional view of the knee of FIG. 4 showing a first example of a conventional structure. The figure similar to FIG. 5 which shows the 2nd example. The figure similar to FIG. 1 which shows the state (A) before the caulking fixation of a pivot, and the state (B) after fixation for demonstrating the problem which arises in the case of a conventional structure.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to all claims. The feature of the present invention including this example is that a rocker arm 3 made of a light alloy such as an aluminum alloy has a cantilevered one of a pair of support plate portions 8 and 8 provided at one end in the longitudinal direction. The present invention relates to a structure of a portion in which a roller 5 is rotatably supported by a pivot 6 between side surfaces (side surfaces facing each other). Since the structure and operation of the other parts are the same as those of the conventional structure described with reference to FIGS. 4 to 7 described above, the illustration and description of the equivalent parts are omitted or simplified, and the following description will focus on the characteristic parts of this example. To do.

  In the cam follower device of this example, a reinforcing bracket 16 made of an iron-based alloy is assembled between the support plate portions 8 and 8. The reinforcement bracket 16 is formed in a U shape as a whole by using a steel alloy plate such as a carbon steel plate or a stainless steel plate. That is, the reinforcing bracket 16 is formed by connecting the ends of a pair of holding plate portions 17 and 17 provided in a state of being separated from each other in the width direction of the rocker arm 3 (left and right direction in FIG. 1). Concatenated by Of these holding plate portions 17 and 17, circular holes 19 and 19 are formed in portions matching the support holes 9 and 9 formed in the both support plate portions 8 and 8, respectively. The inner diameters of the circular holes 19 and 19 are slightly larger than the inner diameters of the support holes 9 and 9. A through hole 20 is formed in the central portion of the connecting plate portion 18.

  The reinforcing bracket 16 as described above is manufactured by stamping and bending the plate material, and the direction of punching is from the inner surface side to the outer surface side of the plate portions 17 and 18. The direction is toward (the surface facing the rocker arm 3). For example, as shown in FIG. 2C, a shearing surface 21 is formed on the entry side of the punching punch and a fracture surface 22 is formed on the protruding side at the inner peripheral edge portions of the circular holes 19 and 19, respectively. However, the fracture surface 22 is positioned on the outer surface side of the both holding plate portions 17 and 17. The reason for restricting the punching direction in this way is that the burrs generated at the edges in the punching process are directed toward the outer surface, and this burrs hinder the rotation of the roller 5 and the rotation and revolution of the needles 12 and 12. This is to prevent things. If a burr is generated, the burr abuts against the inner side surfaces of the support plate portions 8 and 8 in a state where the reinforcing bracket 16 is assembled to the rocker arm 3. Since the reinforcing bracket 16 and the rocker arm 3 are not displaced relative to each other after assembly, the presence of the burr does not cause any trouble.

  Further, a hardened layer such as a nitride layer is formed on the surface of the reinforcing bracket 16. In addition, what is necessary is just to form this hardened layer at least on the inner surface of the both holding plate portions 17 and 17. However, the process for forming only on the inner surface (masking the remaining surface) is troublesome, and even if a hardened layer is formed on the remaining surface, no particular inconvenience arises. Forms a hardened layer on the entire surface of the reinforcing bracket 16.

In the cam follower device of the present example, the reinforcing bracket 16 as described above is opposed to the rocker arm 3, the outer side surfaces of the holding plate portions 17, 17 opposite to each other, and the support plate portions 8, 8 are opposed to each other. It is assembled while pressed against the inner surface. For this purpose, the distance D ₁₇ between the outer surfaces of the two holding plate portions 17, 17 in the free state of the two holding plate portions 17, 17 (before being assembled between the two supporting plate portions 8, 8). {Refer to (B) in FIG. 2} is slightly larger (D ₁₇ > d ₈ ) than the distance d ₈ (see FIG. 1) between the inner side surfaces of the support plate portions 8 and 8. In addition, the holding plate portions 17 and 17 in the free state are slightly parallel to each other or slightly inclined in a direction in which the distance between the holding plate portions 17 and 17 increases toward the tip {upper end of FIGS. 2A and 2B}. Let Therefore, in a state where the reinforcing bracket 16 is pushed between the support plate portions 8 and 8, the outer side surfaces of the holding plate portions 17 and 17 elastically deform the inner side surfaces of the support plate portions 8 and 8. Press. Further, in this state, the circular holes 19 and 19 are formed in the support holes 9 and 9, and the through hole 20 is formed in the downstream end opening of the lubricating oil supply passage 23 provided in the rocker arm 3. Align.

  As described above, in the case of the structure of this example, the both support plate portions 8 and 8 of the rocker arm 3 are displaced in a direction approaching each other by the both holding plate portions 17 and 17 constituting the reinforcing bracket 16. It is suppressed so as not to. Therefore, in order to fix the pivot 6 so as to be spanned between the support plate portions 8 and 8, both ends of the pivot 6 are made plastic as shown in FIG. 7 (A) → (B). When making it deform | transform, it can suppress that it deform | transforms in the direction in which the front-end | tip parts of both said support plate parts 8 and 8 approach. For this reason, it is possible to prevent the gaps 14 between the inner end surfaces of the support plate portions 8 and 8 and both end surfaces in the axial direction of the roller 5 from becoming too narrow. Therefore, the lubricating oil discharged from the downstream end opening of the lubricating oil supply passage 23 into the space between the inner side surfaces of the support plate portions 8 and 8 can be easily discharged through the gaps 14 and 14. Therefore, the flow resistance against the flow of the lubricating oil can be reduced. As a result, the flow rate of the lubricating oil flowing through the rotation support portion of the roller 5 can be secured, the temperature rise of the rotation support portion can be suppressed, and the reliability and durability of the rotation support portion can be improved.

  In the case of this example, the inner side surfaces of the support plate portions 8 and 8 made of a light alloy are covered with holding plate portions 17 and 17 made of iron-based metal and having a hardened layer formed on the surface. For this reason, the washers 13a and 13b (see FIGS. 5 to 6) for preventing wear are omitted, and the inner side surfaces of the holding plate portions 17 and 17 and the axial end surfaces of the roller 5 and the needles 12 and 12 are provided. Even if they face each other directly, sufficient wear resistance can be secured. As a result, it is possible to realize a cam follower device that suppresses the wear of the support plate portions 8 and 8 and has excellent durability without complicating the assembly work.

[Second Example of Embodiment]
FIG. 3 shows a second example of an embodiment of the present invention corresponding to all claims. In the case of this example, the thickness of the pair of holding plate portions 17a and 17a constituting the reinforcing bracket 16a is made larger (thicker) than the thickness of the connecting plate portion 18a. Such a reinforcing bracket 16a is manufactured by subjecting a metal plate, which is a raw material, to fleshing and bending, or by subjecting the raw material to forging.
According to such a structure, it is possible to share the roller 5 having the same width dimension between the rocker arms 3 having different width dimensions. Alternatively, the rollers 5 having different width dimensions can be incorporated into the rocker arm 3 having the same width dimension.
That is, even if the distance between the inner side surfaces of the pair of support plate portions 8 and 8 is larger than the width of the roller 5 by increasing the thickness of the both holding plate portions 17a and 17a, both the support plate portions It is possible to prevent the roller 5 from rattling in the axial direction between the portions 8 and 8.
Since the structure and operation of the other parts are the same as in the case of the first example of the above-described embodiment, a duplicate description is omitted.

When carrying out the present invention, it is most common to use an aluminum alloy as a light alloy constituting the rocker arm and an iron alloy as a metal having higher rigidity than the light alloy constituting the reinforcing bracket. is there. However, a magnesium-based alloy can be used as the light alloy, and a titanium-based alloy can be used as the metal having high rigidity.
In addition, as a cam follower device for an engine valve mechanism, there is a structure in which a roller is installed at an intermediate portion in the longitudinal direction of a rocker arm. However, in such a structure, a pair of support plate portions for supporting both ends of the pivot for rotatably supporting the roller has a structure in which both ends are supported (no free ends). Since the rigidity is high, there is little need to apply the present invention.

DESCRIPTION OF SYMBOLS 1 Camshaft 2 Valve body 3 Rocker arm 4 Support shaft 5 Roller 6 Pivot 7 Radial bearing 8 Support plate part 9 Support hole 10 Caulking part 11 Chamfered part 12 Needle 13a, 13b Washer 14 Gap 15 Intersection 16, 16a Reinforcement bracket 17, 17a Holding plate part 18, 18a Connecting plate part 19 Circular hole 20 Through hole 21 Shear surface 22 Fracture surface 23 Lubricating oil supply path

Claims (3)

A rocker arm made of light alloy that swings and displaces around a support shaft provided in the middle in the length direction, and provided at one end in the length direction of the rocker arm in a state separated in the width direction of the rocker arm. Both ends are fitted in a pair of support plate portions each having a free end that is not constrained by other portions, and concentric support holes formed in both support plate portions. The diametrical portion is plastically deformed outward in the diametrical direction and pressed toward the peripheral edge of the openings of the two support holes, and is fixed in a state of being spanned between the two support plate portions, and is parallel to the support shaft. In a cam follower device including a pivot and a cylindrical roller rotatably supported around the pivot, the rigidity is higher than that of the light alloy constituting the rocker arm between the support plates. Made of high metal, this low A reinforcing bracket formed by connecting ends of a pair of holding plate portions provided in a state of being spaced apart from each other in the width direction of the car arm by a connecting plate portion, The support plate portions are assembled in a state where they are pressed against the inner surfaces facing each other, and the downstream end opening of the lubricating oil supply passage provided inside the rocker arm has both of the end faces in the longitudinal direction of the rocker arm. A cam follower device characterized in that a through hole is formed in a portion of the connecting plate portion of the reinforcing bracket that is present between the supporting plate portions and is aligned with the downstream end opening .   The cam follower device according to claim 1, wherein a hardened layer is formed on at least inner surfaces of the reinforcing brackets facing each other among the reinforcing brackets.   The cam follower device according to any one of claims 1 to 2, wherein an inner side surface and an end surface in the axial direction of the roller that are opposed to each other of both holding plate portions of the reinforcing bracket are directly opposed to each other.

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