JPH04214912A - Rocker arm having roller - Google Patents

Abstract

PURPOSE:To avoid effects of a part of a caulk worked part overhanging toward the outer side on other members around a rocker arm, and reduce the weight of the rocker arm itself for the rocker arm having a roller in which an outer end of a roller shaft for supporting the roller freely rotatably is caulked and bound to a roller holding part. CONSTITUTION:An outer side surface of at least one support wall W1, W2 of a roller holding part 1a is recessed inward from an outer side surface of a rocker arm main body bearing part 1b on the same side of the above- mentioned outer side surface, and an outer end edge of a roller shaft hole 12 of the upper wall W1, W2 is caulked 17 with an outer end surface of a roller shaft 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm with rollers incorporated into a valve train of an internal combustion engine.

0002

2. Description of the Related Art The above-mentioned rocker arm includes, for example, a pair of support walls that face each other across a space for inserting a roller in contact with the cam surface of a cam, and a bearing portion that connects these support walls and inserts and supports a rocker shaft. A structure in which the rocker arm main body is provided with at least the following, and both ends of the roller shaft are fitted and supported in roller shaft holes penetrating each support wall is conventionally known (for example, see Japanese Utility Model Application No. 88016/1983).

0003

[Problems to be Solved by the Invention] In such conventional cam followers with rollers, at least one outer end surface of the roller shaft and the corresponding outer end edge of the roller shaft hole are caulked and bonded. The processed part may protrude outward from the outer surface of the support wall. By the way, in a valve train etc. in which such a cam follower is incorporated, functional parts are arranged close to each other in order to make the mechanism compact, but in this case, the overhanging part of the caulked part may come into contact with other parts. There was a risk that the rocker arm would come into contact with it and be damaged, or that it would interfere with the smooth operation of the rocker arm.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a roller-equipped rocker arm that can solve the above-mentioned problems of the conventional devices and is lightweight and compact.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises a rocker arm body and a roller attached to the rocker arm body and in contact with a cam surface of a cam, and the rocker arm body The roller shaft hole is provided with at least a pair of support walls facing each other with a roller insertion space in between, and a bearing portion that connects these support walls and inserts and supports a rocker shaft, and is provided in a roller shaft hole that passes through each of the support walls. In a rocker arm with a roller, in which both ends of a roller shaft that rotatably supports the roller are supported, the outer surface of at least one support wall, where the roller shaft hole opens, is located on the same side as the outer surface. It is characterized in that it is recessed inward from the outer surface of the bearing part, and the outer edge of the roller shaft hole of the one support wall and the outer end surface of the roller shaft are caulked together.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a valve mechanism for a four-stroke internal combustion engine will be described below with reference to the drawings.

In the valve train chamber C shown in FIG. 1, a rocker arm main body 1 is swingably supported by a rocker shaft 4 supported by an engine main body (not shown), and the rocker arm main body 1 is swingably supported by a rocker shaft 4 supported by an engine main body (not shown). Thus, the rotational movement of the valve operating cam 10 below the roller 9 can be converted into a reciprocating movement, that is, an opening/closing movement, of the intake valve or exhaust valve 7 of the internal combustion engine. Thus, the rocker arm main body 1 and the rollers 9 constitute the rocker arm with rollers of the present invention.

The rocker arm main body 1 is formed by forging carbon steel, and includes a roller holding portion 1 on the front side.
a, a valve engaging portion 1c on the base side, and a bearing portion 1b that is located between the two and integrally connects the two. The rocker shaft 4 is rotatably fitted into a shaft hole 2 formed in the bearing portion 1b via a metal bearing 3 that is integrally fitted to the inner peripheral surface of the hole 2. Further, an adjustment screw 5 is screwed into the valve engaging portion 1c, and the screwing position of the adjustment screw 5 is locked by a lock nut 6, and the upper end of the intake valve or exhaust valve 7 is connected to the valve spring 8 at its lower end. It is contacted with an elastic force of .

The roller holding portion 1a includes the valve spring 8.
A roller 9 whose outer peripheral surface is brought into pressure contact with the cam surface of the valve operating cam 10 by the elastic force of is pivotally supported. Next, the mounting structure of this roller 9 will be explained with reference to FIG. 2. The roller holding portion 1a includes a pair of support walls w that face each other across the insertion space 11 for the roller 9 and are integrally connected to each other via the bearing portion 1b.
1 and w2, and a roller shaft 13 is caulked and fixed to each roller shaft hole 12 passing through each of the supporting walls w1 and w2, as will be described in detail later. A roller 9 inserted into the insertion space 11 is rotatably supported at the center of the outer peripheral surface of the roller shaft 13 via a needle bearing 15 having a plurality of needles 15a. It protrudes outward from the tip surfaces of the walls w1 and w2.

The surface of each support wall w1, w2 facing the side surface of the roller 9 is provided with a load acting direction l-l of the valve drive cam 10 on the roller 9 (that is, the axis of the roller shaft 13, the roller 9 and the valve drive cam 10). A notch 20 is provided in a direction substantially perpendicular to the axial direction of the roller 9 (the direction in which the line segment extending between the contact portions between the cams 10 and the axial direction of the roller 9 extends), and the cross section is A substantially V-shaped groove g is formed. As is clear from FIG. 2, this groove g is open in the load acting direction l-l and at the tip end face of each support wall w1, w2, so that the valve mechanism can be moved inside the valve chamber C. A large amount of lubricating oil that is scattered around the rocker arm body 1 due to the operation of each functional part is transferred to the upper side or the tip side (the right side in FIG. 1) of the rocker arm body 1 without being obstructed by the valve cam 10.
The scattered lubricating oil can be taken into the groove g more efficiently, and as a result, the scattered lubricating oil can be sufficiently supplied to the needle bearing 15 of the roller shaft 13 through the groove g, so that the bearing 15 can be efficiently lubricated. It will be done. Further, since the cutout portion 20 is located in a direction substantially perpendicular to the load acting direction l-l of the valve drive cam 10 on the roller 9, the valve drive cam 10
This will not cause a large decrease in the support rigidity of the support walls w1 and w2 for the roller shaft 13, which is repeatedly hit and loaded by the roller shaft.Furthermore, with the special provision of this notch 20, the inertial mass of the tip of the rocker arm body 1 can be reduced. reduced,
The high-speed followability of the rocker arm body 1 to the valve operating cam 10 is improved.

The roller shaft 13 is made of high carbon chromium bearing steel, and its outer peripheral surface is induction hardened to obtain a hardness distribution as described below. Further, both outer end surfaces of the roller shaft 13 are not hardened and are easily caulked, and both outer edges thereof are caulked into chamfered portions 16 pre-formed on both outer edges of each roller shaft hole 12. It is concluded 17 times. It is preferable to perform this caulking 17 over the entire circumference of the roller shaft 13.
As a result, the roller shaft 13 is firmly fixed in the roller shaft hole 12.

The outer surface of each of the support walls w1 and w2, where the roller shaft hole 12 opens, is recessed inwardly than the outer surface of the bearing portion 1b on the same side as the outer surface, so that the bearing A stepped portion s is formed between the adjacent outer surfaces of the portion 1b and the support walls w1 and w2. According to this structure,
The processed portion for the caulking connection 17 is the support wall w1, w
2. Even if it were to protrude outward from the outer surface of the rocker arm body 1, the protruding portion can be accommodated inside the bearing portion 1b of the rocker arm body 1, so that the protruding portion may not be connected to other functional parts of the valve mechanism. In addition, the outer surfaces of the support walls w1 and w2 can be connected to the bearing part 1b.
By recessing the outer surface of the rocker arm body 1, the rocker arm body 1 itself can be made smaller and lighter.

By the way, as shown in FIG. 3, the hardness distribution of the outer peripheral surface of the roller shaft 13 obtained by the above-mentioned quenching treatment is highest near the center point C, Hv=697 to 832, and outside of it at points B and D. The hardness is 653 to 832 in the vicinity, and 192 to 336 in the vicinity of points A and E on the outside. Furthermore, the hardness of both end surfaces of the roller shaft 13 that is not hardened is H.
v=200-280.

Therefore, on the outer circumferential surface of the roller shaft 13, at least the area between the BD becomes a high hardness area H that includes the entire contact area with the needle 15a, and the area between the shaft end surface and each of the A and E The region is a low hardness region L that includes the entire area facing the chamfered portion 16, and in particular, the outer end of the high hardness region H is formed by the corresponding roller shaft hole 12.
The inner end portion of the low hardness region L extends further inward than the inner end edge 16e of the corresponding chamfer 16. Further, between AB and DE, a medium hardness region M is included, which has a hardness intermediate between the high hardness region H and the low hardness region L and is in contact with the inner circumferential surface of the intermediate portion of the roller shaft hole 12. Even in this medium hardness region M, a hardness sufficiently higher than that of the unhardened region can be obtained, so that it is effective in preventing deformation of the roller shaft 13 in this region M.

Next, the operation of the embodiment described above will be explained. Now, if the valve operating cam 10 rotates in conjunction with the crankshaft of the internal combustion engine, the roller 9 that is in pressure contact with the cam surface of the cam 10 will move on the roller shaft 13. The outer circumferential surface of the roller shaft 13 has the hardness distribution as described above as a result of induction hardening. (corresponding to the main part of the hardness region H) can be sufficiently hardened to increase its wear resistance, and also the inner end of the outer circumferential surface of the roller shaft 13 that straddles the inner and outer edges of the inner edge 12e of the roller shaft hole The region near the edge (corresponding to both end portions of the high hardness region H) can also be sufficiently hardened, and the region near the edge where the roller shaft 13 receives the greatest shearing force due to the pounding load from the valve drive cam 10 can be cured sufficiently. Since the rigidity of the region near the inner edge can be increased, deformation and breakage of the roller shaft 13 caused by the shearing force can be effectively prevented.

Furthermore, a low hardness region L is provided on the outer circumferential surface of the roller shaft 13 in contact with the outer edge of the roller shaft hole 12, and
By caulking 17 the outer end surface of the roller shaft 13 to the outer end edge of the roller shaft hole 12 in an unhardened state, the outer end edge of the roller shaft 13 can be easily plastically deformed during the caulking process. The workability of caulking is good. Moreover, the above-mentioned low hardness region L and medium hardness region M, which have relatively low hardness, are defined by the length of the roller shaft hole 12, that is, the support walls w1, w.
2. Since the roller shaft can be formed relatively wide in the same direction according to the thickness of the roller shaft in the same direction, the roller shaft in the intermediate region between the high hardness region H which is sufficiently hardened and the unhardened outer end surface of the roller shaft 13. 13 rapid tissue changes can be avoided as much as possible.

In particular, the escape space for the material that is plastically deformed during the caulking process is provided by the chamfered portion 16 on the outer edge of the roller shaft 13.
In addition, since the outer peripheral surface of the roller shaft 13 corresponding to the chamfered portion 16 is included in the low hardness region L, the outer edge of the roller shaft 13 is secured by the chamfered portion 16 during the caulking process.
Plastic deformation to the side can be easily and accurately performed, further improving the workability of caulking and increasing machining accuracy. Moreover, since the chamfered portion 16 can be used as an insertion guide surface when inserting the roller shaft 13 into the roller shaft hole 12, the insertion operation is easy.

[0018]

As described above, according to the present invention, the rocker arm main body connects the pair of support walls facing each other with the roller insertion space in between, and also supports the rocker shaft by inserting the rocker arm body. In the rocker arm with rollers, the rocker arm has at least a bearing part, and both ends of the roller shaft are supported in roller shaft holes penetrating each of the supporting walls, the outer surface of at least one of the supporting walls having the roller shaft hole open therein. , it is recessed inwardly from the outer surface of the bearing part on the same side as the outer surface thereof, and the outer edge of the roller shaft hole of the one support wall and the outer end surface of the roller shaft are caulked together. Even if the caulked portion should protrude outward from the outer surface of the support wall, the protruding portion can be accommodated inside the bearing portion of the rocker arm main body, and the protruding portion will not affect other members. This is effective in preventing damage to other members and ensuring smooth operation of the rocker arm itself. Furthermore, by making the outer surface of the support wall more concave than the outer surface of the bearing portion, the rocker arm body itself can be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a side view of a main part of a valve train in which the present invention is implemented.

FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is an explanatory diagram showing the correspondence between the outer circumferential surface of the roller shaft and its hardness region.

[Explanation of symbols]

1 Rocker arm body 1b
Bearing part 4 Rocker shaft 9
Roller 10 Valve drive cam 11 as a cam
Insertion space 12 Roller shaft hole 13 Roller shaft 17 Caulking connections w1, w2 Support wall

Claims (1)

[Claims] 1. The rocker arm body (1) is composed of a rocker arm body (1) and a roller (9) attached to the rocker arm body (1) and in contact with the cam surface of the cam (10). 9) a pair of support walls (w1, w2) facing each other across the insertion space (11), and a bearing portion that connects these support walls (w1, w2) and inserts and supports the rocker shaft (4). (1b), and both ends of a roller shaft (13) rotatably supporting the roller (9) are located in the roller shaft hole (12) passing through each of the supporting walls (w1, w2). In the supported rocker arm with rollers, the outer surface of at least one of the support walls (w1, w2) where the roller shaft hole (12) opens is connected to the bearing portion (1) on the same side as the outer surface.
b) Concave inward from the outer surface and caulk and connect the outer edge of the roller shaft hole (12) of one of the supporting walls (w1, w2) and the outer end surface of the roller shaft (13). (17
) A rocker arm with rollers.