JP6001365B2 - Valve lifter for internal combustion engine and method for manufacturing the valve lifter - Google Patents

Description

  The present invention relates to a valve lifter applied to an internal combustion engine and a method for manufacturing the valve lifter.

  In recent years, a valve lifter of an internal combustion engine has a diamond-like carbon film (DLC) on the crown surface of the crown portion in order to greatly reduce the friction and wear of the crown portion, which becomes a high surface pressure region with the sliding rotation of the cam. Some have a hard carbon film.

  In this valve lifter, a chamfered portion is formed at a boundary portion between an outer peripheral edge of the crown surface and an outer periphery of one end of the cylindrical skirt portion. A hard carbon film is formed on the entire portion.

JP 2006-046123 A

  The valve lifter slides up and down to open and close the engine valve while tilting in the bore formed in the cylinder head as the cam rotates on the crown surface and contacts with high surface pressure. It has become.

  For this reason, when the valve lifter is tilted, the DLC film applied to the annular corner portion at the boundary with the skirt portion of the chamfered portion comes into contact with the inner peripheral surface of the bore, and the inside of the bore The peripheral surface may be worn.

  The present invention has been devised in view of the actual state of the conventional valve lifter, and provides a valve lifter that can sufficiently suppress the occurrence of wear on the inner peripheral surface of a bore, and a method of manufacturing the valve lifter.

The invention according to claim 1 is a cylindrical portion that slides in a bore formed inside the engine, and a crown portion that is provided on one end side in the axial direction of the cylindrical portion and integrally has a crown surface that directly contacts the cam. A tapered chamfered portion formed on the outer peripheral edge of the crown surface of the crown portion, a first annular corner portion at the boundary between the crown surface and the chamfered portion, and a boundary between the chamfered portion and the cylindrical portion an internal combustion engine valve lifters with a second annular corner, the in,
To form a diamond-like carbon film on the whole of the crown surface, the diamond-like carbon film in a predetermined range toward from said first annular corner of the first annular corner and the chamfered portion to the second annular corner On the other hand, the diamond-like carbon film is not formed on the second annular corner.

  According to this invention, the occurrence of wear on the inner peripheral surface of the bore can be sufficiently suppressed.

It is principal part sectional drawing of the internal combustion engine to which 1st Embodiment of the valve lifter which concerns on this invention was applied. It is a longitudinal cross-sectional view which shows the state which shape | molded the base material of the valve lifter provided for this embodiment. It is the A section enlarged view of FIG. It is a principal part expanded sectional view of the valve lifter which shows the state by which the DLC film | membrane was given to the crown surface of the valve lifter, and the 1st cyclic | annular corner | angular part side of the chamfering part. It is a principal part longitudinal cross-sectional view which shows the state which forms a DLC film in the predetermined location of a valve lifter with a masking jig. It is principal part sectional drawing which shows the effect | action of the valve lifter of this embodiment. It is principal part sectional drawing which shows 2nd Embodiment of this invention. It is principal part sectional drawing which shows 3rd Embodiment of this invention. It is principal part sectional drawing which shows the formation state of the DLC film with respect to the conventional valve lifter. It is principal part sectional drawing which shows the effect | action of the conventional valve lifter.

  Hereinafter, embodiments of a valve lifter for an internal combustion engine and a method for manufacturing the valve lifter according to the present invention will be described in detail.

  FIG. 1 shows a main part of an internal combustion engine to which a valve lifter according to the present invention is applied. For example, it is applied to an intake side and an exhaust side of a four-cylinder four-cycle gasoline engine.

  In FIG. 1, the left side is the intake side, the right side is the exhaust side, and 2 per cylinder, which is an engine valve that opens and closes the combustion chamber side open ends of the intake port 2 and the exhaust port 3 formed inside the cylinder head 1. Two intake valves 4 and exhaust valves 5 are slidably provided via valve guides 6a and 6b. Further, the intake valves 4 and the exhaust valves 5 are opened on the outer peripheral surfaces of the intake side and the exhaust side camshafts 7 and 8 that are rotatably supported on the upper end portion of the cylinder head 1 via cam bearings. Drive cams 9 and 10 are provided integrally.

  The intake valve 4 and the exhaust valve 5 are seated on the annular valve seats 2a and 3a provided at the opening ends of the exhaust ports 2 and 3 at the umbrella portions 4a and 5a provided on the lower end side of the valve stem. It has become. Further, valve springs 14 and 15 are respectively mounted between the spring retainers 13a and 13b fixed to the stem ends 4b and 5b at the upper ends and the bottom surfaces of the support holes 1a and 1b at the upper ends of the cylinder head 1, respectively. The spring force of each is biased in the closing direction.

  As shown in FIG. 1, the drive cams 9 and 10 are general ones, are formed in an egg shape when viewed from the side, and are set to a predetermined cam width.

  Further, valve lifters 11 and 12 are interposed between the intake valves 4 and the exhaust valves 5 and the drive cams 9 and 10, respectively.

  Each of the valve lifters 11 and 12 is a linear motion type integrally formed of carbon steel, which is an iron-based metal, and is a guide formed as a bore formed at the upper end portion of the cylinder head 1 as shown in FIG. The skirt portions 17 and 17 are cylindrical cylindrical portions that are slidably held in the holes 16a and 16b, and the skirt portions 17 and 17 are formed integrally with an upper end portion that is one end portion in the axial direction. Mainly composed of crown portions 18 and 18 and circular boss portions 19 and 19 that are integrally provided at substantially the center of the lower surface of the crown portions 18 and 18 and contact the stem ends 4b and 5b. .

  Since the intake side and the exhaust side have the same structure, the intake side valve lifter 11 will be described in detail below for convenience of explanation.

  That is, in the valve lifter 11, as shown in FIGS. 1 and 2, the skirt portion 17 is formed in a thin cylindrical shape, and the outer peripheral surface 17a slides on the inner peripheral surface of the guide hole 16a with a predetermined friction. Guided.

  The crown portion 18 is formed to be relatively thick, and a circular crown surface 20 on which the outer peripheral surface 9a of the drive cam 9 slides is formed on the upper surface.

  As shown in FIG. 3, a tapered chamfered portion 21 is formed at the boundary position between the skirt portion 17 and the crown surface 20 as shown in FIG. Has been.

  As shown in FIG. 3, the chamfered portion 21 has a taper angle θ of about 45 ° ± 3 °, that is, an angle of 42 ° to 48 ° with respect to the axial extension line P of the outer peripheral surface 17a of the skirt portion 17. In this embodiment, the angle is set to about 45 °.

  Further, a first annular corner portion 21 a is formed over the entire circumference at the boundary position between the chamfered portion 21 and the crown surface 20, and the boundary between the chamfered portion 21 and the outer peripheral surface 17 a of the skirt portion 17. At the position, the second annular corner portion 21b is formed over the entire circumference.

  As shown in FIG. 4, the crown portion 18 has a hard coating formed over the entire crown surface 20 and the periphery thereof, that is, the entire surface of the crown surface 20 and the first annular corner portion 21 a of the chamfered portion 21. However, no hard coating is formed on the second annular corner portion 21b. This hard film is constituted by a diamond-like carbon film (hereinafter referred to as a DLC film) 22 that has been surface-treated by a vapor deposition method such as arc ion plating, which is a well-known surface treatment technique. As a result, the entire crown surface 20 and the first annular corner portion 21a of the chamfered portion 21 are covered with the DLC film 22 having high hardness and low frictional resistance.

  The DLC film 22 has a film thickness W set to 0.5 to 3.0 μm, and in this embodiment, for example, about 1.0 μm.

[Manufacturing method of valve lifter]
Hereinafter, a method for manufacturing the valve lifter 11 will be described. First, the base material of the carbon steel valve lifter 11 is formed by forging, and the skirt portion 17, the crown portion 18 and the boss portion 19 are integrally formed as shown in FIG. 2 (first step).

  Thereafter, the annular chamfered portion 21 is formed on the outer peripheral edge of the crown surface 20 of the crown portion 18 by cutting. As shown in FIG. 3, the chamfered portion 21 is formed in a tapered surface shape of about 45 ° (second step).

  Subsequently, the DLC film 22 is subjected to a surface treatment on the crown surface 20 by a vapor deposition method such as arc ion plating (third step).

  That is, as shown in FIG. 5, carbon atoms 22a, which are film raw materials, are radiated and attached in the vertical direction (arrow direction) from above the crown surface 20. At this time, since the entire chamfered portion 21 faces the crown surface 20 in the direction in which the carbon atoms 22a fly, the entire chamfered portion 21, that is, the first and second annular angles are formed. There is a possibility that the DLC film 22 is formed on the entire chamfered portion 21 including the portions 21a and 21b.

  Therefore, in order to prevent the carbon atoms 22a from adhering to the second annular corner 21b of the chamfered portion 21, the skirt portion 17 and the second annular corner other than the crown surface 20 and the first annular corner 21a of the chamfered portion 21 are used. A masking jig 23, which is a masking member that covers the entire outer peripheral surface of 21b, is provided in advance.

  As shown in FIG. 5, the masking jig 23 is formed of, for example, a metal material made of stainless steel and has a holding hole 23a in which the valve lifter 11 is accommodated and held, and an upper end opening 23c of the holding hole 23a. An annular protrusion 23b is integrally provided at the hole edge.

  The holding hole 23a is set to have an inner diameter d slightly larger than the outer diameter of the skirt portion 17, and can accommodate the entire valve lifter 11 from below to the inside with a slight friction. Further, inside the holding hole 23a, there is a support member (not shown) that holds the valve lifter 11 accommodated therein from below.

  The protrusion 23b is formed in an annular plate shape and protrudes inward in a substantially horizontal direction, and the amount of inward protrusion α is from the inner peripheral surface of the holding hole 23a to the chamfered portion 21. It is set to a length up to approximately the center position in the radial direction. That is, the lower end edge 23d of the projecting portion 23b is in contact with the substantially central position in the radial direction of the chamfered portion 21, and is set to a length that covers the entire outer peripheral surface 17a of the skirt portion 17 and the second annular corner portion 21b. Has been.

  Therefore, as shown in FIG. 5, first, when the masking jig 23 is placed and set from above the valve lifter 11 via the holding hole 23a (third step), the protrusion 23b of the masking jig 23 is set. The lower end edge 23d of the lower end of the chamfer 21 is in contact with the substantially central position in the radial direction of the chamfered portion 21, and covers the outer peripheral side, that is, the second annular corner portion 21b and the outer peripheral surface 17a of the skirt portion 17.

  Therefore, in this state, the carbon atoms 22a are emitted in the vertical direction from the upper side of the upper end opening 23c of the masking jig 23 toward the crown surface 20 (fourth step).

  Then, as shown in FIG. 4, the carbon atoms 22a adhere to only the entire crown surface 20 and the surface of the first annular corner portion 21a of the chamfered portion 21, and the DLC film 22 is formed only on this portion. The DLC film 22 is not formed on the surface of the second annular stepped portion 21b of the chamfered portion 21 or the outer peripheral surface 17a of the skirt portion 17.

  Thereafter, the entire outer peripheral surface 17a of the skirt portion 17 of the valve lifter 11 is polished and finished with a predetermined grindstone (fifth step), and finally the dimensional accuracy of the outer diameter of the outer peripheral surface 17a of the skirt portion 17 is increased. Thus, the outer diameter of the skirt portion 17 is adapted to the inner diameter of the guide hole 16a.

  Therefore, according to this embodiment, when the engine is driven and the drive cam 9 presses the crown surface 20 of the valve lifter 11 with high surface pressure, the valve lifter 11 slides up and down while tilting in the guide hole 16a. Therefore, as shown in FIG. 6, the second annular corner portion 21b of the chamfered portion 21 near the skirt portion 17 slides directly on the inner peripheral surface of the guide hole 16a and is not in contact with the DLC film 22 become. For this reason, it is possible to sufficiently suppress the occurrence of wear on the inner peripheral surface of the guide hole 16a.

  That is, as shown in FIG. 9, when the DLC film 22 is formed not only on the entire crown surface 20 of the valve lifter 11 but also on the entire chamfered portion 21, the valve lifter 11 tilts in the guide hole 16a. When sliding up and down, as shown in FIG. 10, the highly rigid DLC film 22 formed on the outer surface of the second annular corner portion 21b slidably contacts the inner peripheral surface of the guide hole 16a so that the inner peripheral surface is There is a risk of wear over time.

  However, since the DLC film 22 is not formed on the second annular corner portion 21b of the chamfered portion 21 by using the masking jig 23 as in the present embodiment, the valve lifter 11 is guided to the guide hole during operation. Even when tilted within 16a, the iron-based metal base material of the second annular corner portion 21b slides directly on the inner peripheral surface of the guide hole 16a, not the DLC film 22, Can be sufficiently suppressed.

  Further, since the inclination angle of the chamfered portion 21 is set to about 45 °, the right-angled lower tip edge 23d (corner edge) of the projection 23b of the masking jig 23 is in relation to the chamfered portion 21. Thus, the second annular corner portion 21b and the outer peripheral surface 17a side of the skirt portion 17 are securely covered and closed in a close contact state. For this reason, the emitted carbon atoms 22a are effectively blocked by the projections 23b, and can sufficiently prevent the second annular corners 21b and the skirt 17 from adhering to the outer peripheral surface 17a.

  Therefore, the occurrence of wear on the inner peripheral surface of the guide hole 16a due to the sliding of the second annular corner portion 21b can be further suppressed, and in the fifth step, the entire outer peripheral surface 17a of the skirt portion 17 is predetermined. When the polishing finish is performed with a grindstone, the grindstone is not in contact with the DLC film 22.

  That is, the DLC film 22 applied to the chamfered portion 21 is formed only on the first annular corner portion 21a and not on the outer peripheral surface 17a of the second annular corner portion 21b or the skirt portion 17. The grinding stone does not come into contact with the DLC film 22 during the polishing of the outer peripheral surface 17a.

As a result, the occurrence of partial wear of the grindstone is suppressed, and the life of the grindstone can be increased. In addition, the occurrence of clogging of the grindstone due to the polished hard carbon film powder can be sufficiently avoided, so that the occurrence of poor polishing can be suppressed.
[Second Embodiment]
FIG. 7 shows a second embodiment of the present invention, in which the configuration of the masking jig 23 is changed. The annular projection 23b is formed in a substantially triangular shape in cross section, and the lower surface 23e of the projection 23b. Is formed in an inclined shape, and the entire lower surface 23e is brought into contact with the outer surface of the chamfered portion 21 in a surface contact state.

  That is, the protrusion 23b is set so that the protrusion amount α is set to a substantially central position in the radial direction of the chamfered portion 21 as in the first embodiment, and the lower surface 23e follows the outer surface of the chamfered portion 21. An inclination angle of about 45 ° is set.

  Accordingly, when the DLC film 22 is formed, if the masking jig 23 is placed on the valve lifter 11 through the holding hole 23a, the inclined lower surface 23e of the protrusion 23b is in the radial direction of the upper surface of the chamfered portion 21. It is hung from the substantially center position to the skirt portion 17 side and comes into close contact.

  For this reason, since the projecting portion 23b covers the second annular corner portion 21b and the outer peripheral surface 17a side of the skirt portion 17 in close contact with each other, the carbon atoms 22a emitted from above the crown surface 20 are absorbed by the crown surface 20. Although it adheres to the whole and only the first annular corner 21a side of the chamfered portion 21, adhesion to the outer peripheral surface 17a of the second annular corner 21b and the skirt portion 17 is further suppressed.

As a result, the formation of the DLC film 22 on the second annular corner portion 21b and the outer peripheral surface 17a of the skirt portion can be further suppressed as compared with the case of the first embodiment, so that the wear of the guide hole 16a occurs when the valve lifter 11 is tilted. Can be more effectively suppressed.
[Third Embodiment]
FIG. 8 shows a third embodiment in which the masking jig 23 is further modified. The masking jig 23 includes a metal frame-like main body 24 that can accommodate a plurality of valve lifters 11 therein, and the frame. It is comprised by the thin-plate-shaped masking member 25 mounted in the shape of a lid on the upper end opening edge of the main body 24.

  The frame-shaped main body 24 is formed in a substantially cylindrical shape, and the size thereof is arbitrarily set according to the number of valve lifters 11 to be processed.

  The masking member 25 is integrally formed of a metal material, and circular openings 25a are respectively formed at locations where the valve lifters 11 are arranged. The inner diameter d1 of the opening 25a is formed slightly smaller than the outer diameter d2 of the valve lifter 11, and the opening edge 25b is formed so as to be positioned at the substantially center in the radial direction of the chamfered portion 21 of the valve lifter 11. ing.

  Therefore, when the DLC film 23 described above is formed on the crown surface 20 side, the valve lifters 11 are first arranged at predetermined positions inside the frame-shaped main body 24 of the masking jig 23, and then the masking member 25 is attached to the frame. It is placed and fixed between the upper end of the main body 24 and each valve lifter 11.

  In this state, the opening edge 25 b of the masking member 25 is in contact with the substantially central position in the radial direction of each chamfered portion 21 to cover the first annular corner portion 21 b and the skirt portion 17 of each chamfered portion 21.

  Thereafter, when carbon atoms 22a are radiated from the position vertically above the crown surface 20 of each valve lifter 11 toward the crown surface 20, the DLC film 23 is formed around the entire crown surface 20 and the first annular stepped portion 21a of the chamfered portion 21. However, the DLC film 23 is not formed on the first annular step portion 21b and the outer peripheral surface 17a of the skirt portion, and the metal base material is exposed.

  As a result, similar to the first and second embodiments, the occurrence of wear on the guide hole 16a by the first annular corner portion 21b can be suppressed.

  In addition, since the masking jig 23 can be manufactured relatively easily by the frame-shaped main body 24 and the masking member 25, the manufacturing cost can be reduced.

  In addition, since a large number of DLC film 22 forming operations of the valve lifter 11 can be taken, the efficiency of the film forming operation is improved.

  The present invention is not limited to the configuration of each of the embodiments described above. For example, the structure of the masking jig 23 can be further changed.

  The base material of the valve lifter 11 may be an aluminum alloy material in addition to the iron-based metal.

  In addition to the DLC film 22, the hard film may be, for example, a titanium nitride film, or an amorphous carbon material may be used.

  Furthermore, it can be applied not only to the intake-side valve lifter 11 but also to the exhaust-side valve lifter 12, and can also be applied to any internal combustion engine having a different displacement.

The technical ideas of the invention other than the claims ascertained from the embodiment will be described below.
[Claim a] In the valve lifter for an internal combustion engine according to claim 1,
The valve lifter for an internal combustion engine, wherein the chamfered portion is formed at an angle of about 45 ° with respect to the cylindrical portion.
[Claim b] In the valve lifter of the internal combustion engine according to claim 1,
The valve lifter for an internal combustion engine, wherein the hard coating is constituted by a diamond-like carbon coating.
[Claim c] In the method of manufacturing a valve lifter for an internal combustion engine according to claim 3,
A method for manufacturing a valve lifter for an internal combustion engine, wherein an outer peripheral surface of the cylindrical portion is polished by a grindstone.
[Claim d] In the method of manufacturing a valve lifter for an internal combustion engine according to claim 3,
The method of manufacturing a valve lifter for an internal combustion engine, wherein the masking member has an inclined surface in surface contact with the inclined chamfered portion on an inner peripheral surface of the opening.

DESCRIPTION OF SYMBOLS 1 ... Cylinder head 4 ... Intake valve 5 ... Exhaust valve 7/8 ... Cam shaft 9/10 ... Drive cam 11/12 ... Valve lifter 17 ... Skirt part (cylindrical part)
16 ... Guide hole (bore)
DESCRIPTION OF SYMBOLS 18 ... Crown part 20 ... Crown surface 21 ... Chamfer part 21a ... 1st cyclic | annular corner | angular part 21b ... 2nd cyclic | annular corner | angular part 22 ... DLC film 22a ... Carbon particle 23 ... Masking jig | tool 23a ... Holding hole 23b ... Protrusion part 23c ... Tip Edge θ… Taper angle

Claims (2)

A cylindrical portion that slides in a bore formed inside the engine; a crown portion that is provided on one end side in the axial direction of the cylindrical portion and that directly contacts the cam; and a crown portion of the crown portion. A tapered chamfered portion formed on the outer peripheral edge, a first annular corner portion at the boundary between the crown surface and the chamfered portion, and a second annular corner portion at the boundary between the chamfered portion and the cylindrical portion, , a valve lifter of an internal combustion engine equipped with a,
To form a diamond-like carbon film on the whole of the crown surface, the diamond-like carbon film in a predetermined range toward from said first annular corner of the first annular corner and the chamfered portion to the second annular corner while forming, the the second annular corner valve lifter of an internal combustion engine, characterized in that does not form the diamond-like carbon film. A cylindrical portion that slides in a bore formed inside the engine; a crown portion that is provided on one end side in the axial direction of the cylindrical portion and that directly contacts the cam; and a crown portion of the crown portion. A chamfered portion formed at an outer peripheral edge , a first annular corner portion at the boundary between the crown surface and the chamfered portion, and a second annular corner portion at the boundary between the chamfered portion and the cylindrical portion. A valve lifter for an internal combustion engine,
A diamond-like carbon film is formed on the entire crown surface, and the diamond-like carbon film is formed in a predetermined range from the first annular corner of the first annular corner and the chamfered portion toward the second annular corner. The valve lifter for an internal combustion engine is characterized in that a base material of the valve lifter is exposed at the second annular corner portion .

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