JP7014678B2 - Rocker arm and its manufacturing method - Google Patents

Description

The present invention relates to a rocker arm of an internal combustion engine.

A rocker shaft type rocker arm is known as one of the valve operating system parts for opening and closing a valve of an internal combustion engine (Patent Document 1). The rocker shaft type rocker arm has a hole (also referred to as a wrapping portion) having an inner diameter slightly larger than the outer diameter of the rocker shaft penetrating in the width direction. By being passed through with a clearance based on it, it is rotatably attached to the shaft. That is, it is a plain bearing that receives the rocker shaft at the winding portion that is the slip surface. Lubricating oil must be interposed between the wrapping part and the rocker shaft so that they do not stick together.

Many of the rocker shaft type rocker arms are manufactured by forging, and there is little sheet metal bending.

As shown in FIG. 3, the intermediate portion of the forged rocker arm 51 is solid in the width direction, and the winding portion 56 is formed in the intermediate portion. Therefore, the contact width between the rocker arm 51 and the rocker shaft 50 (also referred to as “wet length” because lubricating oil is interposed) is the length of the winding portion 56, that is, the width of the intermediate portion, and is sufficiently large. Therefore, the surface pressure between the winding portion 56 and the rocker shaft 50 becomes low, and it is easy to improve the wear reliability. Further, the winding portion 56 can be easily provided with an oil sump 59 for storing the lubricating oil or an oil hole (not shown) for passing the lubricating oil.

As shown in FIG. 4, the rocker arm 61 formed by bending a sheet metal includes two side walls 63 and a bottom wall 64 made of the bent sheet metal, and a winding portion 66 is formed in an intermediate portion between the two side walls 63. Therefore, the contact width (wet length) between the rocker arm 61 and the rocker shaft 60 is only the plate thickness of the two side walls 63, and is short, so that the surface pressure between the winding portion 66 and the rocker shaft 60 increases and wear occurs. It is difficult to increase reliability. Further, it is difficult to provide an oil pool or an oil hole in the winding portion 66. However, the rocker arm 61 formed by bending the sheet metal has the advantages of good manufacturability, low cost, and easy weight reduction.

Japanese Unexamined Patent Publication No. 2011-247090

Therefore, as shown in FIG. 5, a partially concave cylindrical surface 68 having a radius of curvature equal to the radius of the wrapping portion 66, which is continuous with the lower part of the wrapping portion 66, is machined on the bottom wall 64 of the rocker arm 61 by bending the sheet metal. It is conceivable that the rocker shaft 60 is supported even on the partially concave cylindrical surface 68, and the surface pressure between the winding portion 66 and the rocker shaft 60 is lowered. It is possible to continuously perform drilling of the winding portion 66 and cutting of the partially concave cylindrical surface 68 at the same time with a drill, but it is difficult to accurately cut the partially concave cylindrical surface 68 with a drill, and the portion Since the processing length of the concave cylindrical surface 68 is long, the processing time is long, the cost is increased, and it is difficult to secure the accuracy.

Therefore, an object of the present invention is to form a ridge in the center of the bottom wall in the width direction in a rocker arm by bending a sheet metal so that a partially concave cylindrical surface can be accurately formed on the bottom wall in a short processing time. By supporting the rocker shaft at three points, the wrapping portion of the two side walls and the partially concave cylindrical surface, the surface pressure between the wrapping portion and the rocker shaft is reduced, and the wear reliability is improved. Further, the oil pool is set on both ends in the width direction of the bottom wall to ensure the lubricity between the winding portion and the rocker shaft.

[1] Rocker arm An internal combustion engine provided with two side walls extending in the rearward direction and separated from each other in the width direction, and a bottom wall connecting the lower portions of the two side walls, and a winding portion through which a rocker shaft is passed is formed on the two side walls. In the rocker arm of
A ridge that protrudes upward and extends in the rear direction is integrally formed at the center of the bottom wall in the width direction, and an oil pool sandwiched between the ridge and the side wall is formed above both ends of the bottom wall in the width direction.
At the top of the ridge, the contact width with the rocker shaft, which is located on the extension of the lower part of the inner peripheral surface of the wrapping part and has a radius of curvature equal to the radius of the wrapping part , is larger than the contact width between each wrapping part and the rocker shaft. A rocker arm characterized in that a short partially concave cylindrical surface is formed, and the rocker shaft is supported at three points, two winding portions and a partially concave cylindrical surface.

(Action)
Since a ridge is formed at the center of the bottom wall in the width direction and a partially concave cylindrical surface is formed at the top of the ridge, the width direction length (processed length) of the partially concave cylindrical surface is larger than the width of the bottom wall. It is short, and shorter than the contact width between each winding part and the rocker shaft . Therefore, a partially concave cylindrical surface can be accurately formed on the bottom wall in a short processing time. By supporting the rocker shaft at three points, the two winding portions and the partially concave cylindrical surface, the surface pressure between the winding portion and the rocker shaft is reduced. Further, the lubricating oil collected in the oil pools at both ends in the width direction of the bottom wall is supplied between the winding portion and the partially concave cylindrical surface and the rocker shaft.

[2] Manufacturing method of rocker arm A two side wall extending in the front-rear direction and separated from each other in the width direction and a bottom wall connecting the lower portions of the two side walls are provided, and a winding portion through which a rocker shaft is passed is formed on the two side walls. In the manufacturing method of the rocker arm of the internal combustion engine
By bending the sheet metal, the two side walls and the bottom wall are integrally formed, and at the center of the bottom wall in the width direction, a ridge that protrudes upward and extends in the rearward direction is integrally formed, and above both ends of the bottom wall in the width direction. Is an oil pool sandwiched between the ridge and the side wall.
With a rocker shaft, the wrapping part is drilled in the two side walls by a drill, and the top of the ridge is located on the extension of the lower part of the inner peripheral surface of the wrapping part and has a radius of curvature equal to the radius of the wrapping part. A partially concave cylindrical surface whose contact width is shorter than the contact width between each winding part and the rocker shaft is machined so that the rocker shaft can be supported at three points, the two winding parts and the partially concave cylindrical surface. A characteristic method of manufacturing a rocker arm.

(Action)
The drilling of the wrapping portion 6 and the cutting of the partially concave cylindrical surface can be continuously performed at one time. Since a ridge is formed in the center of the bottom wall in the width direction and a partially concave cylindrical surface is formed at the top of the ridge, the width direction length (processed length) of the partially concave cylindrical surface is shorter than the width of the bottom wall. Moreover, it is shorter than the contact width between each winding part and the rocker shaft . Therefore, a partially concave cylindrical surface can be accurately formed on the bottom wall in a short processing time.

According to the present invention, in a rocker arm by bending a sheet metal, by forming a ridge at the center in the width direction of the bottom wall, a partially concave cylindrical surface can be accurately formed on the bottom wall in a short processing time. By supporting the rocker shaft at three points, the winding portion and the partially concave cylindrical surface, the surface pressure between the winding portion and the rocker shaft can be reduced and the wear reliability can be improved. Further, the oil pool is formed on both ends in the width direction of the bottom wall, and the lubricity between the winding portion and the partially concave cylindrical surface and the rocker shaft can be ensured.

1A and 1B show a rocker arm of an embodiment, FIG. 1A is a perspective view, FIG. 1B is a sectional view taken along line Ib-Ib, FIG. 1C is a sectional view taken along line Ic-Ic, and FIG. Is. FIG. 2A is a cross-sectional view when a winding portion and a partially concave cylindrical surface are formed on the rocker arm, and FIG. 2B is a cross-sectional view when the rocker arm is mounted on an internal combustion engine. 3A and 3B show a conventional forged rocker arm, FIG. 3A is a perspective view, FIG. 3B is a sectional view, and FIG. 3C is a sectional view taken through a rocker shaft. 4A and 4B show a rocker arm obtained by bending a conventional sheet metal, FIG. 4A is a perspective view, FIG. 4B is a sectional view taken along line IVb-IVb, FIG. 4C is a sectional view taken along line IVc-IVc, and FIG. It is a cross-sectional view of the time. 5A and 5B show an improvement plan of a rocker arm by bending a sheet metal of a conventional example, FIG. 5A is a perspective view, FIG. 5B is a cross-sectional view of Vb-Vb, FIG. 5C is a cross-sectional view of Vc-Vc, and FIG. It is a cross-sectional view when it is passed through.

1. 1. Wrapped portion The wrapping portion may be formed in the middle portion in the front-rear direction of the side wall, or may be formed in the rear portion (so-called swing arm type).

2. 2. The portion that abuts on the cam The portion that abuts on the cam is preferably a roller rotatably mounted on the side wall (which is a so-called roller arm), but may be a slipper fixed to the side wall.

3. 3. The part that presses the valve The part that presses the valve is usually formed at the tip of the side wall in the front-rear direction. The portion that presses the valve is not particularly limited, and an embodiment of an action portion that connects between the lower portions of the tips of the two side walls can be exemplified. This working portion is preferably integrally formed with the two side walls. Further, the working portion may be exemplified in a mode in which the lower surface thereof is a valve pressing surface (pad surface) or a mode in which an adjuster pin as a pressing member is screwed into the working portion.

The rocker arm 1 of the embodiment shown in FIGS. 1 and 2 includes a rocker arm body 2 rotatably attached to the rocker shaft 21 and a roller 10 rotatably attached to the rocker arm body 2. It is a so-called roller arm.

The rocker arm main body 2 has two side walls 3 extending in the front-rear direction and separated from each other in the width direction, a bottom wall 4 connecting between the two side walls 3 below the winding portion 6, and the tip portions of the two side walls 3. It includes a working portion 5 that connects the lower parts, and these are integrally formed of a steel material. More specifically, they consist of bent steel sheet metal.

A wrapping portion 6 (hole) having an inner diameter slightly larger than the outer diameter of the rocker shaft 21 is formed in the middle portion in the front-rear direction of the two side walls 3 in the width direction, and the rocker shaft 21 is outside the wrapping portion 6. The rocker arm 1 main body is rotatably pivotally attached by being passed through with a clearance based on the difference between the diameter and the inner diameter. That is, it is a slide bearing that receives the rocker shaft 21 at the winding portion 6 that is the slide surface.

The tip of the upper surface of the bottom wall 4 is on the front side of the tip of the winding portion 6 and on the rear side of the tip of the rocker arm 1 (in this example, the rear end of the working portion 5). The rear end of the upper surface of the bottom wall 4 is on the rear side of the rear end of the winding portion 6 and on the front side of the rear end of the rocker arm 1 (in this example, the lower portion of the roller 10).

At the center of the bottom wall 4 in the width direction, a ridge 7 having a mountain-shaped cross section that protrudes upward from the upper surface and extends in the rearward direction is integrally formed. The ridge 7 is formed during bending, which will be described later. At the top of the middle portion in the front-rear direction of the ridge 7, the contact width with the rocker shaft 21 located on the extension of the lower part of the inner peripheral surface of the wrapping portion 6 and having a radius of curvature equal to the radius of the wrapping portion 6 is wound. A partially concave cylindrical surface 8 shorter than the contact width between the portion 6 and the rocker shaft 21 is formed, and the rocker shaft 21 can be supported at three points of the two winding portions 6 and the partially concave cylindrical surface 8. ..

Above both ends of the bottom wall 4 in the width direction is an oil sump 9 sandwiched between the ridge 7 and the side wall 3. Since the upper surface of the bottom wall 4 has a shape in which the front end and the rear end are higher than the intermediate portion, the lubricating oil tends to collect in the oil sump 9. It should be noted that there is a groove on the lower surface of the central portion of the bottom wall 4 in the width direction, and this groove is formed along with the formation of the ridge 7 during the bending process described later.

The working portion 5 is also bent at the same time as the bottom wall 4, so that a ridge is formed on the upper surface (there is no special function) and a groove is formed on the lower surface. The lower surface of the working portion 5 is a valve pressing surface.

The roller 10 is rotatably axially mounted between the front and rear rear portions of the two side walls 3. More specifically, a stop hole 11 is formed in the rear portion of the two side walls 3 in the front-rear direction, the pin 12 is passed through the stop hole 11 and attached by caulking, and a roller 10 is inserted in the middle portion of the pin 12 via, for example, a needle 13. It is rotatably attached to the shaft.

The rocker arm 1 configured as described above is manufactured by the following method.
(1) By bending the sheet metal, the two side walls 3 and the bottom wall 4 are integrally formed, and the ridges 7 are formed in the central portion in the width direction of the bottom wall 4, and both ends in the width direction of the bottom wall 4 are formed. The top is an oil sump 9.

(2) As shown in the change from FIG. 2 (a) to FIG. 1 (b), a winding portion 6 is drilled around the two side walls 3 by a drill 15, and a partially concave cylindrical surface is formed on the top of the ridge 7. 8 is machined. The drilling of the winding portion 6 and the cutting of the partially concave cylindrical surface 8 by the drill 15 can be continuously performed at one time.
Since the ridge 7 is formed at the center of the bottom wall 4 in the width direction and the partially concave cylindrical surface 8 is formed at the top of the ridge 7, the length (processed length) of the partially concave cylindrical surface 8 in the width direction is the bottom wall. It is shorter than the width of 4 , and further shorter than the contact width between each winding portion 6 and the rocker shaft 21 . Therefore, the partially concave cylindrical surface 8 can be accurately formed on the bottom wall 4 in a short processing time.

The rocker arm 1 of this embodiment is mounted on an internal combustion engine, for example, as shown in FIGS. 2 (b) and 1 (d). A rocker shaft 21 fixed to a cylinder head (not shown) is passed through both winding portions 6, a cam 22 is in contact with the roller 10 from below, for example, and a valve is contacted with the valve pressing surface of the acting portion 5 from below. The stem ends of 23 come into contact with each other.

When the base circle 22a of the cam 22 abuts on the roller 10, the difference between the outer diameter of the rocker shaft 21 and the inner diameter of the winding portion 6 between the lower portion of the winding portion 6 and the partially concave cylindrical surface 8 and the rocker shaft 21. There is a clearance based on. Since the lubricating oil accumulated in the oil sump 9 is supplied to this clearance, the lubricity between the winding portion 6 and the partially concave cylindrical surface 8 and the rocker shaft 21 can be ensured.

When the nose 22b of the cam 22 comes into contact with the roller 10, the rocker arm 1 swings forward and downward, the acting portion 5 presses the valve 23, and the valve face (not shown) opens the cylinder with a predetermined lift amount. do. At this time, since the entire rocker arm 1 is lifted by the load received from the nose 22b and the stress received from the valve 23, the lower portion of the winding portion 6 and the partially concave cylindrical surface 8 and the rocker shaft 21 come into contact with each other without the clearance. By supporting the rocker shaft 21 at three points of the two winding portions 6 and the partially concave cylindrical surface 8, the surface pressure between the winding portion 6 and the rocker shaft 21 can be reduced, and the wear reliability can be improved.

1 Rocker arm 2 Rocker arm body 3 Side wall 4 Bottom wall 5 Acting part 6 Wrapped part 7 Protrusion 8 Part concave cylindrical surface 9 Oil pool 10 Roller 11 Stop hole 12 pin 13 Needle 15 Drill 21 Rocker shaft 22 Cam 22a Base circle 22b Nose 23 Valve

Claims (2)

It is provided with two side walls (3) extending in the front-rear direction and separated from each other in the width direction, and a bottom wall (4) connecting the lower portions of the two side walls (3), and a rocker shaft (21) is provided on the two side walls (3). In the rocker arm of the internal combustion engine in which the winding portion (6) through which the) is passed is formed.
A ridge (7) that protrudes upward and extends in the rearward direction is integrally formed at the center of the bottom wall (4) in the width direction, and the ridge (7) and the side wall (3) are above both ends of the bottom wall (4) in the width direction. ) And the oil pool (9)
At the top of the ridge (7), the contact width with the rocker shaft (21), which is located on the extension of the lower part of the inner peripheral surface of the wrapping portion (6) and has a radius of curvature equal to the radius of the wrapping portion (6). A partially concave cylindrical surface (8) shorter than the contact width between each winding portion (6) and the rocker shaft (21) is formed, and the two winding portions (6) and the partially concave cylindrical surface (8) are formed at three locations. A rocker arm characterized in that it supports the rocker shaft (21). It is provided with two side walls (3) extending in the front-rear direction and separated from each other in the width direction, and a bottom wall (4) connecting the lower portions of the two side walls (3), and a rocker shaft (21) is provided on the two side walls (3). In the method of manufacturing a rocker arm of an internal combustion engine in which a winding portion (6) through which is formed is formed.
By bending the sheet metal, the two side walls (3) and the bottom wall (4) are integrally formed, and the ridge (7) that protrudes upward and extends in the rearward direction is integrally formed at the center of the bottom wall (4) in the width direction. Then, above both ends of the bottom wall (4) in the width direction, an oil sump (9) sandwiched between the ridge (7) and the side wall (3) is formed.
A wrapping portion (6) is drilled in the two side walls (3) by a drill (15), and the wrapping portion (6) is located at the top of the ridge (7) on an extension of the lower part of the inner peripheral surface of the wrapping portion (6). A partially concave cylindrical surface (8) having a radius of curvature equal to the radius of the winding portion (6) and having a contact width with the rocker shaft (21) shorter than the contact width between each winding portion (6) and the rocker shaft (21). A method for manufacturing a rocker arm, which comprises cutting a rocker arm so that the rocker shaft (21) can be supported at three points of two winding portions (6) and a partially concave cylindrical surface (8).

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