WO2003044330A1

WO2003044330A1 - Cam follower with sheet metal rocker arm

Info

Publication number: WO2003044330A1
Application number: PCT/JP2002/012061
Authority: WO
Inventors: Masayo Shimizuya
Original assignee: Nsk Ltd.
Priority date: 2001-11-21
Filing date: 2002-11-19
Publication date: 2003-05-30
Also published as: CN1589364A; US20040255717A1; AU2002366024A1; EP1447526A1; EP1447526A4; JPWO2003044330A1

Abstract

A cam follower with a sheet metal rocker arm, wherein the outside faces (17) of a pair of side wall parts (4) are not formed parallel with each other since the amounts of elongation thereof at the time of elastic deformation are different from each other, when in use, a load is applied to a pivot shaft (3) in a direction from a side on which an interval between the outside faces (17) is small to a side on which the interval is large, and crimped parts (13a) formed at the outer peripheral edge parts on both end faces of the pivot shaft (3) are formed on the half parts thereof on the side where the interval between the outside faces (17) is small, whereby the both end part outer peripheral surfaces of the pivot shaft (3) are allowed to abut on the inner peripheral surface of a through hole (11) on the side for pivotally supporting the load, and the load can be sufficiently pivotally supported on the contact surface, and rattling can be prevented from occurring on the both end support parts of the pivot shaft (3) against the pair of side wall parts (4) even if the cam follower is used for a long period.

Description

Description Cam follower with rocker arm made of sheet metal

The present invention relates to an improvement of a cam follower provided with a sheet metal rocker arm made by pressing a metal plate. Background art

Except for some two-stroke engines, reciprocating engines (reciprocating piston engines) have intake and exhaust valves that open and close in synchronization with the rotation of the crankshaft. The rocker arm is used in a cam follower that is incorporated into the valve operating mechanism of the engine and converts the rotation of the camshaft into reciprocating motion of the valve body (intake and exhaust valves). In such a reciprocating engine, the movement of the camshaft, which rotates in synchronization with the rotation of the crankshaft (in the case of a four-stroke engine, at a rotation speed of 1 to 2), is controlled by the rocker arm to the intake and exhaust valves. And the valve bodies of the intake valve and the exhaust valve are reciprocated in the axial direction.

It has been considered that a rocker arm to be incorporated in such a valve operating mechanism of an engine is manufactured by pressing a metal plate such as a steel plate in order to reduce the weight while securing the strength. With regard to a force mufloor with a rocker arm made of sheet metal considered in such a situation, FIGS. 4 to 7 show what is described in US Pat. No. 5,048,475. This cam follower includes a sheet metal rocker arm 1, a roller 2, and a pivot 3. The roller 2 is rotatably supported by the pivot 3 with respect to the sheet metal rocker arm 1.

As shown in FIG. 7, the cam follower comprises a cam 9 of a cam shaft, a lash adjuster, a plunger 8 serving as a swing center of the rocker arm 1 made of sheet metal, and a valve element 7 of an intake valve or an exhaust valve. Associated with. The rocker arm 1 made of a sheet metal of the cam follower is made of, for example, a metal plate such as a steel plate having a thickness of about 2 to 4 mm. It is formed by punching to remove unnecessary parts and plastic working such as drawing to obtain a desired shape, and connects a pair of side walls 4 and these side walls 4 to each other. And two connecting portions 5 and 6. As shown in FIG. 7, the first connecting portion 5 functions as a pressing portion for displacing the valve body 7 by abutting the base end face of the valve body 7 against the first connecting portion 5, and The connecting portion 6 functions as a fulcrum for abutting the tip surface of the plunger 8. For this reason, in the illustrated example, as shown in the lower surface of FIG. 6, a spherical concave portion is formed on one surface of the second connecting portion 6. It should be noted that, unlike the example shown in the drawing, a structure in which a screw hole is provided in a portion corresponding to the second connecting portion, and an Asian screw having a spherical portion at an end portion is screwed and fixed to the screw hole portion has been conventionally used. Are known.

On the other hand, the roller 2 rotatably supported by the pivot 3 is disposed in a space surrounded by the connecting portions 5 and 6 and the pair of side walls 4. In order to support the roller 2 on the pair of side walls 4 with the pivots 3, both ends of the pivots 3 are fitted in through holes formed at positions where the pair of side walls 4 are aligned with each other. Further, outer peripheral edges of both end faces of the pivot 3 are swaged toward the peripheral edges of these through holes (see FIG. 10). With this configuration, both ends of the pivot 3 are fixed to the pair of side walls 4 in a state of being bridged between the side walls 4. The roller 2 is rotatably supported directly or via a radial needle bearing around the intermediate portion of the pivot 3 spanned between the side walls 4 in this way.

In the assembled state to the engine, as shown in FIG. 7, the base end of the valve body 7 abuts against one surface (the lower surface in FIG. 7) of the first connection portion 5, and The distal end surface of the plunger 8 is brought into contact with the spherical concave portion provided on one side, and the outer peripheral surface of the roller 2 is brought into contact with the outer peripheral surface of the cam 9 fixed to the intermediate portion of the cam shaft. During operation of the engine, the rocker arm 1 made of sheet metal swings around the contact portion between the tip surface of the plunger 8 and the spherical recess as a center (fulcrum) as the cam 9 rotates. The body 7 is reciprocated in the axial direction by the pressing force of the first connecting portion 5 and the elasticity of the return spring 10. Although not shown in the drawings, Japanese Patent Publication No. 6-81892 and the like also disclose a force mufflor having a sheet metal rocker arm having a similar structure.

The sheet metal rocker arm 1 made by plastic working a metal plate Since the thickness of the metal plate changes, sufficient durability may not be ensured unless the shape and structure of each part is devised. Regarding this point, Figs.

This will be explained by adding 10.

When the sheet metal rocker arm 1 as shown in FIGS. 4 to 7 is manufactured by drawing a metal plate such as a steel plate, the width direction of the pair of side wall portions 4 (vertical direction in FIGS. 6 and 7). Of the two end portions, the end of the first and second connecting portions 5 and 6 (upper side in FIGS. 6 and 7) is more planar than the end portion on the opposite side (lower side in FIGS. 6 and 7). 6 and 7, the thickness of the side wall portion 4 becomes thinner as going upward. For this reason, as shown in FIGS. 8 and 10, the cross-sectional shape of the both side wall portions 4 in the width direction is a wedge shape that is inclined in a direction that becomes thicker as the distance from each of the connecting portions 5 and 6 increases. On the other hand, the inner surfaces of the side walls 4 need to be parallel to each other. The reason for this is to prevent the inner surfaces of the side wall portions 4 and the roller 2 disposed between the side wall portions 4 from hitting each other, so that the rotation of the roller 2 is performed smoothly. To do that.

As described above, when the inner surfaces of the side walls 4 each having a wedge-shaped cross-section are arranged parallel to each other, the outer surfaces of the side walls 4 are arranged as shown in FIG.

They are non-parallel to each other as shown at 10. Specifically, the distance between the outer surfaces of the side wall portions 4 gradually increases as the distance from the connecting portions 5 and 6 increases (downward in FIG. 8, 10). In this way, the distance between the outer surfaces of the side walls 4 gradually changes because the through holes 11 for fixing the both ends of the pivot 3 are formed at the widthwise intermediate portions of the side walls 4. But the same is true. For example, as a result of experiments and measurements performed by the inventor, the thickness of the side walls 4 is approximately l Mi at the edges of the two connecting portions 5 and 6 (the upper edge of 10 in FIG. 8). At the opposite edge (lower edge in Fig. 8), about 3 marauders were found. In this case, the thickness of the peripheral portion of each of the through holes 11 was 2.3 mm on the both connecting portions 5 and 6 side, and 2.9 mm on the opposite side. This difference in thickness is directly the non-parallelism of the outer surfaces of both side walls 4.

As described above, the outer peripheral edges of both end faces of the pivot 3 are swaged and fixed to the chamfered portions 12 formed on the peripheral edges of the openings of the through holes 11. However, in a state where the outer surfaces of the side wall portions 4 are not parallel to each other, the both end portions of the pivot 3 cannot be crimped and fixed to the chamfered portion 12 uniformly over the entire circumference. That is, both end surfaces of the pivot 3 Exists in a direction perpendicular to the axis of the pivot 3, so that the positional relationship between the both end faces and the chamfered portion 12 in the axial direction is not uniform in the circumferential direction. In order to secure sufficient caulking strength, it is necessary to make the axial positional relationship between the above-mentioned both end faces and the above-mentioned chamfered portions 12 appropriate, but as long as the outer surfaces of the above-mentioned both side walls 4 are not parallel to each other. However, it is not possible to make the above positional relationship appropriate over the entire circumference. It should be noted that it is impractical to make the axial end faces of the pivot 3 non-parallel with the outer faces in view of mass productivity.

For this reason, conventionally, as shown in FIG. 8, the chamfered portion 12 formed on the periphery of each through hole 11 on the opposite side (the lower side in FIG. 8) to the connecting portions 5 and 6 is used. However, the positional relationship with respect to the axial direction between the both end surfaces of the pivot 3 is made appropriate. Then, as shown by a chain line in FIG. 9, a caulking jig (punch) is pressed against an intermediate portion of both end surfaces of the pivot 3 or a portion opposite to the connecting portions 5 and 6, and the intermediate portion or the opposite portion is pressed. Was crimped outward in the radial direction. Therefore, as shown in FIG. 10, the outer peripheral surfaces of both ends of the pivot 3 and the inner peripheral surfaces of the through holes 11 are in contact with each other on the two connecting portions 5 and 6 (upper side in FIG. 10). Touch On the side where the caulked portion 13 is formed, that is, on the side opposite to the connecting portions 5 and 6 (the lower side in FIG. 10), the outer peripheral surfaces of both ends of the pivot 3 and the through holes 11 are provided. A gap 14 is interposed between the inner peripheral surface and the inner peripheral surface.

As shown in FIG. 10, a gap 14 is formed between the outer peripheral surface of both ends of the pivot 3 and the inner peripheral surface of each through hole 11 on the side opposite to the first and second connecting portions 5 and 6. In the interposed state, the swaged portions 13 formed at both ends of the pivot 3 support the load applied to the pivot 3 from the cam 9 shown in FIG. 7 via the roller 2 (and also the radial needle bearing). It will be. That is, a load is applied to the pivot 3 from above to below in FIG. 10 (corresponding to the elasticity of the return spring 10) during the operation of the engine. In the direction in which this load acts, a gap 14 is interposed between the outer peripheral surfaces of both ends of the pivot 3 and the inner peripheral surfaces of the through holes 11, so that the load is applied to both ends of the pivot 3. There is no direct transmission from the outer peripheral surface to the inner peripheral surface of each through hole 11, and the caulked portion 13 bears the load.

However, the contact area between the caulked portion 13 and the chamfered portion 12 is small. Easy to do. For this reason, with the use over a long period of time, Plastic deformation may occur inward in the radial direction, and the contact pressure between the caulked portion 13 and the chamfered portion 12 may decrease. In the state where the contact pressure is reduced in this manner, the pivot 3 and the roller 2 supported around the intermediate portion of the pivot 3 rattle against the rocker arm 1 made of sheet metal, which is generated when the engine is operated. It is not preferable because vibration and noise increase.

The cam follower of the present invention has been invented to solve such inconvenience. Disclosure of the invention

The cam follower of the present invention includes a rocker arm made of sheet metal, a pivot, and a roller.

The sheet metal rocker arm is formed by subjecting a metal plate such as a steel plate to plastic working, and includes a pair of side walls and a connecting portion connecting the side walls to each other.

In addition, the pivot is formed by crimping the outer peripheral edges of both end faces toward the inner peripheral faces of a pair of through holes formed at positions where these two side walls are aligned with each other, so that the pair of side walls are connected to each other. It is fixed in a state of being bridged between.

Further, the roller is rotatably supported around the intermediate portion of the pivot, directly or via a rolling bearing such as a radial needle bearing or a sliding bearing.

The thickness of the side wall portion of the rocker arm made of sheet metal gradually changes in the width direction such that it is thinner on the side closer to the connecting portion and thicker on the side farther from the connecting portion.

Further, the distance between the outer surfaces of the pair of side wall portions increases as the distance from the connection portion increases.

Then, in use, a load is applied to the pivot from the side of the connecting portion.

In particular, in the cam follower provided with the sheet metal rocker arm of the present invention, the outer peripheral edges of the axially opposite end surfaces of the pivot are located at the half of the peripheral edge of the through hole closer to the connecting portion. It is crimped. The outer peripheral surfaces of both ends of the pivot and the inner peripheral surfaces of the respective through holes are in contact with each other at a portion far from the connection portion.

Preferably, a portion located on the inner diameter side of the roller in the intermediate portion of the pivot is quenched and hardened, and portions to be swaged at both ends of the pivot are hardened and hardened. It is left raw without being transformed.

More preferably, among the openings at both ends of each of the through holes, a peripheral edge of the opening on the outer side surface of the side wall portion is chamfered, and formed at an outer peripheral edge of both axial end surfaces of the pivot. The outer peripheral surface of the caulking portion is in contact with this chamfered portion.

In the case of a cam follower having a rocker arm made of sheet metal having the above-described configuration, the outer peripheral surfaces of both ends of the pivot and the inner peripheral surface of each through hole are provided on the load bearing side, that is, on the load bearing portion. Abut on a large area. Also, since the outer peripheral surface portions of both ends of the pivot shaft which come into contact with the inner peripheral surfaces of these through holes at this load bearing portion are not plastically deformed portions like caulked portions, a large surface pressure is applied. Plastic deformation is difficult. For this reason, even when used for a long period of time, rattling of the support portions at both ends of the pivot with respect to the side walls constituting the sheet metal rocker arm is less likely to occur. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an example of an embodiment of the present invention in a state before crimping both ends of a pivot.

FIG. 7 is a diagram corresponding to the II section of FIG. 6, which exaggerates the thickness of each side wall portion and the gap between the outer peripheral surface of both ends of the pivot and the inner peripheral surface of the through hole.

FIG. 2 is a view taken in the direction of the arrow II in FIG. 1 showing a position where a caulking jig is pressed to caulk both ends of the pivot.

FIG. 3 is a view similar to FIG. 1, showing a state after caulking both ends of the pivot. FIG. 4 is a perspective view showing an example of a cam follower provided with a conventionally known rocker arm made of sheet metal.

FIG. 5 is a view from above of FIG.

FIG. 6 is a sectional view taken along the line VI-VI of FIG.

FIG. 7 is a cross-sectional view showing a state of being assembled to the engine.

FIG. 8 is a view similar to FIG. 1 showing a conventional structure.

FIG. 9 is a view taken in the direction of the arrow IX in FIG. 8, showing a position where a caulking jig is pressed in order to caulk both ends of the pivot.

FIG. 10 is a view similar to FIG. 1, showing a state after swaging both ends of the pivot. BEST MODE FOR CARRYING OUT THE INVENTION

1 to 3 show an example of an embodiment of the present invention. The feature of the present invention lies in the structure of a portion that supports both ends of the pivot 3 with respect to a pair of side walls 4 having a wedge-shaped cross-sectional shape and non-parallel outer surfaces. The structure and operation of the entire cam follower having a rocker arm made of sheet metal have been described in the prior art, including the aforementioned US Pat. No. 5,048,475 and Japanese Patent Publication No. 6-81892. Since the structure is the same as a widely known structure, the illustration and the description are omitted or simplified, and the following description will focus on features of the present invention. Throughout the drawings, the same reference numerals are given to the same members.

The cam follower of the present embodiment includes a rocker arm 1 made of sheet metal, a roller 2 and a pivot 3, similarly to the conventional cam follower.

The sheet metal rocker arm 1 is made by subjecting a metal plate such as a steel plate to a drawing process, which is a plastic working process, and includes a pair of side wall portions 4 and a connecting portion that connects the side wall portions 4 to each other (for example, FIG. And first and second connecting portions 5, 6) as shown in FIG. A pair of through-holes 11 is formed in a portion where the two side walls 4 are aligned with each other in the middle. Both ends of the pivot 3 are fitted and supported in these two through holes 11, and the pivot 3 is bridged between the side walls 4. A quenched layer 15 is formed over the entire circumference on the outer peripheral surface of the intermediate portion of the pivot 3 by induction hardening. In the illustrated example, the length of the quenched layer 15 in the axial direction is slightly longer than the distance between the inner surfaces of the side wall portions 4. Therefore, both ends of the quenched layer 15 enter the both through holes 11. The outer peripheral surface of such an intermediate portion of the pivot 3 functions as an inner raceway of a radial needle bearing for supporting the roller 2 (see FIGS. 4 to 7). However, the both ends of the pivot 3 are left raw without quenching, and the caulked portions 13a for fixing the both ends to the respective through holes 11 are formed so that they can be easily processed. I have.

The cross-sectional shape of the side walls 4 in the width direction (vertical direction in FIGS. 1 and 3) is wedge-shaped. It gradually changes in the width direction, with the upper side being thinner and the farther side from this connection (lower side in Figs. 1 and 3) becoming thicker. The inner side surfaces 16 of the side wall portions 4 are at least parallel to each other in the width direction. Along with this, the outside of the above both side walls 4 The distance between the surfaces 17 increases as the distance from the connecting portion increases. In use, a load is applied to the pivot 3 from the side of the connecting portion, that is, from the top to the bottom in FIGS.

In particular, in the cam follower of the present invention, the outer peripheral edges of both end faces in the axial direction of the pivot 3 are the half of the peripheral edge of each of the through holes 11 on the side closer to the connecting portion (see FIGS. (Upper half of 3). For this purpose, as shown by a chain line in FIG. 2, a caulking jig is pressed against the intermediate portion or the side portion close to the connecting portion at a part of the both end surfaces of the pivot 3 in the circumferential direction, and the caulking portion 13 is formed. forming a. With this caulking, the outer peripheral surfaces of both ends of the pivot 3 and the inner peripheral surfaces of the through holes 11 are brought into contact with each other on the side farther from the coupling portion (the lower side in FIGS. 1 to 3). In contact. For this reason, in the illustrated example, of the openings at both ends of each through hole 11, the periphery of the opening on the outer surface 17 side of the side wall 4 is chamfered 12, and the pivot 3 The outer peripheral surface of the caulking portion 13 a formed at the outer peripheral edge of both end surfaces in the axial direction is brought into contact with the chamfered portion 12. Then, with the processing of the caulked portion 13a, both ends of the pivot 3 are strongly pushed away from the connecting portion, and the outer peripheral surfaces of both ends of the pivot 3 and the through holes 11 are formed. The inner peripheral surface is in strong contact with each other on the side farther from the connecting portion (the lower side in FIGS. 1 to 3). As is clear from FIGS. 1 and 3, in the case of the present invention, the caulking portion is used. The space between the outer side surfaces 17 of the side wall portions 4 at the portion where the 13a is to be brought into contact with the caulked portion 13 in the conventional structure shown in FIGS. 8 to 10 described above. It is smaller than the space between the outer surfaces in the power section. Along with this, the axial length of the pivot 3 constituting the cam follower of the present invention is slightly shorter than the axial length of the pivot 3 constituting the conventional structure.

In the case of the cam follower provided with the sheet metal rocker arm having the above-described configuration, the outer peripheral surfaces of both ends of the pivot 3 and the respective through holes are provided on the load bearing side, that is, on the load bearing portion. 11. The inner peripheral surface of 1 is in contact with a large area. Also, since the outer peripheral surfaces of both ends of the pivot 3 which are in contact with the inner peripheral surfaces of the through holes 11 at this load bearing portion are not plastically deformed portions like the swaged portions 13a. However, even when a large surface pressure is applied, plastic deformation is difficult. Particularly, in the illustrated example, the inner peripheral surface of each of the through holes 11 is in contact with the inner peripheral surface. The quenched layer 15 is present on a part of the outer peripheral surfaces of both ends of the pivot 3 that is in contact with the quench shaft 15. The hardened layer 15 is hard and extremely hard to deform. Therefore, even when used for a long period of time, both ends of the pivot 3 with respect to the side walls 4 constituting the rocker arm 1 made of sheet metal can be used. The support portion is less likely to rattle. Industrial applicability

Since the present invention is configured and operates as described above, it is possible to improve the durability of the cam follower which is made lightweight and at low cost.

Claims

The scope of the claims

1. a cam follower comprising a rocker arm, a pivot, and rollers,

(1) Rocker arm

(l a) Made by drawing on a metal plate,

(l b) a pair of side walls, and

(1c) having a connecting portion for connecting the pair of side wall portions,

(Id) With the connecting portion side as the upper side and the anti-connecting portion side as the lower side, the thickness of the pair of side walls gradually changes in the width direction so that the upper side is thinner and the lower side is thicker, (1 e) the distance between the outer surfaces of the pair of side wall portions increases toward the lower side, and (If) a through hole is formed at a position where the pair of side wall portions match each other,

(2) The axis is

(2 a) fit into the pair of through holes, and are bridged between the pair of side wall portions; (2 b) outer peripheral edges of both end surfaces in the axial direction of the pivot are the pair of through holes. Caulked against the upper side of

(3) The roller is rotatably supported around an intermediate portion of the pivot.

2. The cam follower according to claim 1, wherein the rocker arm is

(1) Of the openings at both ends of each through hole, the periphery of the opening on the outer surface side of the pair of side wall portions is chamfered,

(2) Both end faces in the axial direction of the pivot are located between the axial position of the uppermost point of the inner circumferential circle of the chamfer and the axial position of the lowermost point of the inner circumferential circle.

3. A portion facing the inner diameter side of the roller in the middle portion of the pivot is quenched and hardened, and portions to be swaged at both ends of the pivot are left unhardened and hardened. Cam follower according to any one of Items 1 and 2.

4. The cam follower according to claim 2, wherein outer peripheral surfaces of caulking portions formed at outer peripheral edges of both axial end surfaces of the pivot are in contact with the chamfered portion.