JPH0797904A - Adjusting shim - Google Patents

Abstract

PURPOSE:To enable an adjusting shim to be used in combination of a cam in the valve system mechanism of an internal combustion engine for automobile capable of obtaining good sliding characteristic by reducing a friction coefficient between a cam and the shim and improving surface roughness of the cam without simultaneously applying any difficult, and high-cost special ultra-precision finish machining on the cam having complicated shape. CONSTITUTION:It is an adjusting shim 3 which is used in combination with a cam 1 in a gear system mechanism of an internal combustion engine for automobile and consists of ceramic material whose main components are silicon nitride whose surface roughness on a slide face between the cam 1 and the adjusting shim 3 is 0.1mum or less as a ten-point average roughness or a sialon and a composite material film which is provided on the ceramic material and at least on the slide face between the cam and the adjusting shim and in which powdered particles of MoS2 are dispersed in polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam follower adjusting shim which constitutes a valve train of an internal combustion engine such as an automobile engine.

[0002]

2. Description of the Related Art In recent years, it has been strongly desired to improve fuel efficiency by improving the efficiency of an automobile engine, and as one of effective measures against this, reduction of friction loss of an internal combustion engine has been studied.
In particular, even in internal combustion engines such as automobile engines, the low sliding speed and high load reduce wear between the cam and adjusting shim in the valve train mechanism, which is one of the most severe sliding parts. It is said to be extremely effective.

Generally, it is said that the minimum gap or the minimum oil film thickness between the facing sliding parts and the property of the sliding surface of the sliding parts have a great influence on the sliding characteristics. For example, "Hydraulic and Pneumatic" Vol. 18, No. 4, No. 247, 1987-
As described in p. 258, or "Technical Lecture Preprint 924" edited by the Society of Automotive Engineers of Japan, pp. 85-88, 1992, the oil film parameter defined by the following equation 1 as a value indicating the scale of lubrication. Λ is often used.

[0004]

[Formula 1] Λ = h _min / σ = h _min / (R _rms1 ² + R _rms2 ² ) ^1/2 where h _min is the minimum clearance or the minimum oil film thickness between the facing sliding parts, and σ is the facing sliding Composite surface roughness of moving parts, R
_rms1 represents the root mean square roughness of the surface of one sliding component, and R _rms2 represents the root mean square roughness of the surface of the other sliding component.

When the value of the oil film parameter Λ is 3 or more, it is in a fluid lubrication state, when it is 1 or less, it is in a boundary lubrication state, and when it is 1
In the case of 3 to 3, it is considered to be a mixed lubrication state in which fluid lubrication and boundary lubrication are mixed, and it is said that as the value of Λ is larger, the contact between the sliding surfaces is alleviated and the sliding characteristics are improved. Therefore, under the same sliding condition, the minimum clearance or minimum oil film thickness h
_{Since min} is constant, reducing the surface roughness of the two sliding surfaces is effective in reducing the friction coefficient.

Therefore, the sliding surface of the sliding component is subjected to high-precision ultra-precision finishing to reduce the surface roughness as much as possible. Since it is difficult to perform high-precision ultra-precision finishing on surfaces with complicated shapes and the processing cost is extremely high due to the large amount of time and labor required, surface finishing by ordinary grinding is the mainstream. The present situation is that the reduction of the friction coefficient between the cam and the shim cannot be maintained.

[0007]

SUMMARY OF THE INVENTION In view of such conventional circumstances, the present invention reduces the friction coefficient between the cam and the shim,
At the same time, it is possible to improve the surface roughness of the cam without performing special ultra-precision finishing that is difficult and costly for the cam having a complicated shape. The present invention relates to an adjuster shim used in combination with a cam in a valve train mechanism.

[0008]

In order to achieve the above object, an adjusting sigsim used in combination with a cam in a valve train mechanism of an internal combustion engine for an automobile provided by the present invention has a surface roughness of a sliding surface with the cam. Having a ten-point average roughness of 0.1 μm or less and a ceramic material mainly composed of silicon nitride or sialon, and MoS ₂ powder particles provided on the sliding surface of at least the cam of the ceramic material dispersed in the polymer. It is characterized by comprising a composite material coating.

The ceramic material used for the adjusting shim of the present invention has a surface roughness of 0.1 μm in ten-point average roughness.
If it is the following and has silicon nitride (Si ₃ N ₄ ) or sialon as a main component, it is a composite material reinforced by any of fibers, whiskers or dispersed particles, even if it is a sintered body. Is also good. In both cases of the sintered body and the composite material, the content of Si ₃ N ₄ or sialon as the main component is 60% by volume or more in consideration of hardness and durability required as an adjusting shim. preferable.

A specific example of such a composite material is S
i ₃ N ₄ or sialon carbon fiber, silicon carbide fiber, fiber-reinforced composite material reinforced with alumina fibers, Si ₃ N ₄ or sialon whisker-reinforced composite material reinforced with silicon carbide whiskers or the like, Si ₃ N ₄ or sialon Examples thereof include a particle dispersion strengthened composite material in which titanium nitride particles, silicon carbide nanoparticles and the like are reinforced.

At least one of polyamideimide, polyimide, polytetrafluoroethylene, polyphenylene sulfide, and diallyl phthalate resin is preferable as the polymer for holding the powder particles of MoS ₂ and constituting the composite material film. However, depending on the type of polymer other than the above, the composite material coating film may become soft and wear resistance may be reduced. Therefore, care must be taken in selecting the polymer.

The manufacturing of the adjusting shim of the present invention comprises:
For example, the following method can be used. First Si ₃
The surface of the ceramic material containing N ₄ or Sialon as a main component is ground to a predetermined surface roughness, degreased and dried to form fine irregularities on the surface as necessary. Next, powder particles of MoS ₂ are applied to the surface of the ceramic material as a liquid polymer (uncured resin or resin precursor or a solution thereof).
The paint suspension is dispersed by spraying, dipping, brushing, etc., and then baked or air-dried to form a MoS ₂ / polymer composite material film.

On the other hand, the cam, which is a mating member of the adjusting shim of the present invention, is subjected to surface treatment such as ordinary cast iron, alloy cast iron, cast steel, or chilling, which is a constituent material of sliding parts in general mechanical parts. In addition to ordinary cast iron and cast materials, alloy steels such as bearing steels and high speed steels, all sliding metal materials currently in practical use such as aluminum alloys, titanium alloys and magnesium alloys can be used.

[0014]

When the value of the oil film parameter Λ in the above formula 1 becomes less than 3, the contact between the sliding member and the mating member starts at the tip of the protrusion on the sliding surface, and the fluid lubrication breaks at the contact portion, resulting in boundary lubrication. The entire lubrication state is a mixed lubrication state in which fluid lubrication and boundary lubrication are mixed. The friction coefficient between the members increases rapidly with the increase of the boundary lubrication portion. However, in the adjusting shim of the present invention, in addition to the extremely small surface roughness of the ceramic material, the surface of the solid lubricant is added to the solid lubricant in the polymer. As described above, since the composite material film in which the powder particles of MoS ₂ are dispersed is present, the friction coefficient between the cam and the shim in the boundary lubrication portion can be reduced, and good sliding characteristics can be obtained.

Further, in the lubrication region where the value of the oil film parameter Λ is small, the friction coefficient value in unlubricated sliding determined by the material of the sliding member is dominant in the overall friction loss. In the adjusting shim, the friction coefficient is reduced by using a ceramic material and making the surface roughness extremely small. Moreover, the use of a ceramic material has effects such as wear resistance due to the high hardness of ceramics and prevention of a seizure phenomenon due to low surface activity. In addition, since it is relatively lightweight compared to steel, etc. Overall weight reduction can be expected.

Further, in the adjusting shim of the present invention, the composite material coating formed on the sliding surface of the ceramic material is easily peeled off and dropped during sliding with the cam as the mating member. The MoS ₂ particles in the fallen composite material coating are cam-
The sliding surface, which is interposed between the sliding surfaces of the shim and is made of a metal of the cam having a hardness lower than that of MoS ₂ , is polished to improve the surface roughness. Therefore, even if the cam, which is the mating member, does not undergo precision finishing, the surface is naturally polished by sliding with the adjusting shim of the present invention to improve the surface roughness, which is extremely economically advantageous. At the same time, it is possible to reduce the coefficient of friction by improving the surface roughness.

In this way, when the sliding surface of the metal cam, which is the mating member, is polished and becomes smooth during the break-in operation and / or the initial sliding stage, the fluid lubricated portion in the mixed lubrication state is removed. Since it increases, the progress of further wear or uneven wear is stopped, and the surface accuracy of the cam can be maintained and at the same time, a good lubrication state can be maintained. Moreover, since the adjusting shim is made of ceramics and has a lower surface activity than a combination of metal-metal cam-shim, seizure with the cam and abnormal wear in this state can be prevented.

Particularly in the case of an adjusting shim, since the contact surface pressure with the cam, which is a sliding member, is high, the frictional resistance during sliding is reduced and the aggression of the cam surface due to the unevenness of the shim surface (cam Taking into consideration the prevention of (abnormal wear), the surface roughness of the ceramic material in the adjusting shim of the present invention must be 0.1 μm or less in terms of ten-point average roughness R _Z.

Further, in order to maintain a state where the friction coefficient is reduced for a long time and prevent an attack by a cam that causes surface roughness, it is desirable that the adjusting shim has a high hardness. Since the adjusting shim has high hardness, local deformation due to contact with the cam is unlikely to occur,
Uneven friction due to local deformation does not occur. In order to obtain these effects, the hardness of the ceramic material of the adjusting shim is 1000 kgf in Vickers hardness H _V.
/ Mm ² or more is preferable.

The powder particles of MoS ₂ forming the composite material film have a property as a solid lubricant and reduce the wear resistance between the cam and the shim. The film thickness of the composite material film in which the powder particles of MoS ₂ are dispersed in the polymer is 5 to 30 μm.
It is preferably in the range of m. The reason is that if the thickness of the composite material film is less than 5 μm, sufficient lubricity cannot be obtained, and conversely, if it exceeds 30 μm, sufficient effects in durability and sliding resistance cannot be obtained.

The polymer constituting the composite material coating is M
As the binder of the oS ₂ particles, the polyamide imide, polyimide, polytetrafluoroethylene, polyphenylene sulfide, diallyl phthalate resin and the like are preferable. These polymers can be expected to be self-lubricating as well as binders, and are considered to form an effective lubricating film together with the lubricity of MoS ₂ .

The volume content of the polymer in the composite material coating is preferably in the range of 50 to 95% by volume. The reason is,
When the volume content of the polymer is less than 50% by volume, the effect of the MoS ₂ particles as a binder is reduced, so that the durability of the composite coating decreases, and when it exceeds 95% by volume, the lubricity of the composite coating becomes insufficient. Because.

[0023]

EXAMPLES Example 1 A Si ₃ N ₄ sintered body having a Vickers hardness of 1400, a sialon sintered body, and a SiC fiber reinforced Si ₃ N ₄ composite material (30% by volume of SiC fiber) having a predetermined size. The surface roughness of each ceramic material is 0.1 μ in terms of ten-point average roughness R _Z.
The surface of each of two types, one having a diameter of m or less and one having a thickness of more than 0.1 μm (comparative example) was ground, degreased and dried.

On the other hand, MoS ₂ powder was mixed and dispersed in a polyamide-imide liquid polymer to obtain a paint suspension having a volume content of the polymer of 75% by volume with respect to the total amount of the polymer and MoS ₂ . This coating suspension was spray-coated on the sliding surface of each ceramic material to a film thickness of about 10 μm, heated to 170 to 180 ° C. and baked to form a composite material film on the surface of the adjuster. Got Sting Sim.

Each of the obtained adjusting shims is shown in FIG.
The cam follower adjusting shim 3 was attached to the valve system of a 4-cylinder 16-valve commercial vehicle engine having an outer shim type direct drive valve system with a displacement of 2000 cc shown in FIG. That is, by the action of the cam 1 rotating around the cam shaft 2 and the valve spring 5, the valve lifter 4 moves in the axial direction to open / close the intake / exhaust valve 6 of the cylinder head 7. The adjusting shim 3 was mounted on the top of the cam 1 so as to slide relative to the cam 1.
A chill-hardened cast iron alloy was used for the cam 1.

A motor for driving the cam shaft is added to the valve system.
A pump for supplying oil and a torque meter for measuring camshaft drive torque are attached to configure a camshaft drive torque measurement tester, and the crankshaft rotation speed is converted to 2000 r
The cam shaft 2 was actually driven by a motor at pm. The camshaft drive torque was measured 1 hour and 100 hours after the start of driving, and the ten-point average roughness R _Z of the sliding surface of the adjusting shim 3 before measurement and after 100 hours of operation was measured, and The results are shown in Table 1.

Further, as a comparative example, an adjusting shim made of Cr-Mo steel having a surface roughness equivalent to that of the genuine product of the commercial vehicle engine is also the same as that obtained by using the camshaft drive torque measuring tester. Was measured and the results are also shown in Table 1.

[0028]

[Table 1] Shim surface roughness R _Z (μm) Driving torque (kgf · mm ² ) Sample ceramic material 100 hours after measurement 1 hour after 100 hours 1-1 Si ₃ N ₄ sintered body 0.08 0.08 362 359 1 -2 Sialon sintered body 0.09 0.10 359 360 1-3 Si ₃ N ₄ composite material 0.08 0.08 360 359 1-4 * Si ₃ N ₄ sintered body 0.35 0.35 383 381 1-5 * Sialon sintered body 0.42 0.43 378 380 1-6 * Si ₃ N ₄ composite material 0.40 0.41 377 380 1-7 * Cr- Mo steel 0.51 0.55 428 440 (Note) samples with * in the table are comparative examples.

As is clear from the results shown in Table 1, by using the adjusting shim having the composite material film of MoS ₂ / polymer provided on the sliding surface of the ceramic material, the cam can be used as compared with the conventional adjusting shim made of steel. It is possible to reduce the shaft driving torque, and particularly when the surface roughness of the ceramic material is 0.1 μm or less in terms of ten-point average roughness R _Z , the driving torque reducing effect is great. Further, it can be seen that the adjusting shim of the ceramic material provided with the composite material film maintains the initial surface roughness even after long-term operation, and the driving torque in that case also maintains the initial level.

[0030]Example 2  Using the same adjusting shim samples as in Example 1
Example 1 using the same camshaft drive torque measurement tester
The operation was performed for 100 hours under the same conditions as above. Then horse mackerel
Chill Hardening of Alloy Cast Iron as Counterpart of Casting Shim
The cam nose length L shown in FIG.
Measured and the cam wear from the difference with the cam nose length before the start of operation
The amount was calculated. Also, for the cam after 100 hours of operation,
And ten-point average roughness R of the sliding surface_ZAnd measure these results
Is shown in Table 2.

[0031]

[Table 2] Cam after shim surface roughness operation Cam after operation Sample ceramic material Before measurement R _Z (μm) Wear amount (μm) Surface roughness R _Z (μm) 1-1 Si ₃ N ₄ sintered body 0.08 21 0.52 1-2 Sialon sintered body 0.09 16 0.36 1-3 Si ₃ N ₄ composite material 0.08 19 0.43 1-4 * Si ₃ N ₄ sintered body 0.35 234 1.48 1-5 * Sialon sintered body 0.42 257 1.56 1 -6 * Si ₃ N ₄ composite material 0.40 243 1.65 1-7 * Cr-Mo steel 0.51 321 1.71 (Note) The samples marked with * in the table are comparative examples.

From the above results, it is possible to significantly reduce the wear amount of the cam, which is the mating member during sliding, and at the same time sliding by setting the surface roughness R _Z of the ceramic material of the adjusting shim to 0.1 μm or less. It can be seen that the cam surface is polished inside to naturally improve the surface roughness.

[0033]

According to the adjusting shim of the present invention, it is possible to reduce the frictional resistance of the portion which becomes the boundary lubrication during the running-in operation and the sliding of the cam which is the counterpart member in the lubricant. The sliding characteristic between the shims can be improved, and the camshaft drive torque can be significantly reduced compared to the conventional case.
At the same time, the cam surface can be polished to improve its surface roughness during running-in and sliding with the cam, so that no special ultra-precision finishing is required on the surface of the cam with a complicated shape. It is also possible to reduce the friction coefficient between the cam and the shim, which is economically extremely advantageous.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an outer shim type direct acting valve train of an internal combustion engine for an automobile used in an embodiment.

FIG. 2 is a schematic plan view of a cam for explaining a method for measuring a cam wear amount according to a second embodiment.

[Explanation of symbols]

 1 cam 2 cam shaft 3 adjusting shim 4 valve lifter 5 valve spring 6 intake / exhaust valve 7 cylinder head

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 30, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art In recent years, it has been strongly desired to improve fuel efficiency by improving the efficiency of an automobile engine, and as one of effective measures against this, reduction of friction loss of an internal combustion engine has been studied.
In particular, even in an internal combustion engine such as an automobile engine, friction loss between a cam and an adjusting shim in a valve train mechanism, which is one of the most severe sliding components because of low sliding speed and high load, is eliminated. It is said that the reduction is extremely effective.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Furthermore, the following actions are expected in the adjusting shim of the present invention. The composite material film formed on the sliding surface of the adjusting shim easily separates and falls off during sliding with the cam, which is a mating member. The MoS ₂ particles in the fallen composite material film are present between the adjusting shim and the sliding surface of the cam, and have the function of preventing adhesion and seizure during sliding. Promotes smoothing of the sliding surface between the adjusting shim and the cam due to "familiarity". Since the ceramic adjusting shim has high hardness and low surface activity, the sliding surface of the metal cam, which is a mating member, is preferentially smoothed at this time. Therefore, even if the cam is not subjected to a precise finishing process, the surface is smoothed by sliding with the ceramic adjusting shim of the present invention to improve the surface roughness, which is extremely economically advantageous and at the same time. It is possible to reduce the friction coefficient by improving the surface roughness.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

Further, in order to maintain a state where the friction coefficient is reduced for a long time and prevent an attack by a cam that causes surface roughness, it is desirable that the adjusting shim has a high hardness. Since the adjusting shim has high hardness, local deformation due to contact with the cam is unlikely to occur,
Uneven wear due to local deformation does not occur. In order to obtain these effects, the hardness of the ceramic material of the adjusting shim is 1000 kgf in Vickers hardness H _V.
/ Mm ² or more is preferable.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

The powder particles of MoS ₂ constituting the composite material film have the property of a solid lubricant and reduce the friction coefficient between the cam and the shim. The film thickness of the composite material film in which the powder particles of MoS ₂ are dispersed in the polymer is 5 to 30 μm.
It is preferably in the range of m. The reason is that if the thickness of the composite material film is less than 5 μm, sufficient lubricity cannot be obtained, and conversely, if it exceeds 30 μm, sufficient effects in durability and sliding resistance cannot be obtained.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

A motor for driving the cam shaft is added to the valve system.
A pump for supplying oil and a torque meter for measuring camshaft drive torque are attached to configure a camshaft drive torque measurement tester, and the crankshaft rotation speed is converted to 2000 r
The cam shaft 2 was actually driven by a motor at pm. The camshaft drive torque was measured 1 hour and 100 hours after the start of driving, and the ten-point average roughness R _Z of the sliding surface of the adjusting shim 3 was measured before measurement and after 100 hours of operation, and the result was obtained. Is shown in Table 1.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

According to the adjusting shim of the present invention, it is possible to reduce the coefficient of friction of a portion which becomes boundary lubrication during running-in and sliding with a cam which is a counterpart member in a lubricant. By improving the sliding characteristics between the cam and the shim, the camshaft drive torque can be reduced significantly compared to the conventional case. At the same time, the cam surface can be polished to improve its surface roughness during running-in and sliding with the cam, so that no special ultra-precision finishing is required on the surface of the cam with a complicated shape. It is also possible to reduce the friction coefficient between the cam and the shim, which is economically extremely advantageous.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display part // (C10M 111/04 103: 06 C 107: 44 107: 38 107: 46 107: 22) C10N 20:06 40:02 40:25 50:08 (72) Inventor Takao Nishioka 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Akira Yamakawa Itami City, Hyogo Prefecture Konyo Kita 1-1-1 Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Kenji Matsunuma 1-1 Kuunyo Kita 1-1-1, Itami City, Hyogo Prefecture Sumitomo Electric Industries Itami Works

Claims (6)

[Claims] A nitriding shim which is used in combination with a cam in a valve train of an internal combustion engine for an automobile, wherein a surface roughness of a sliding surface with the cam is 0.1 μm or less in ten-point average roughness. An adjusting shim comprising a ceramic material containing silicon or sialon as a main component, and a composite material film in which powder particles of MoS ₂ provided on a sliding surface of at least a cam of the ceramic material are dispersed in a polymer. . 2. The adjusting shim according to claim 1, wherein the ceramic material is a sintered body or a composite material containing 60% by volume or more of silicon nitride or sialon. 3. The adjusting shim according to claim 1, wherein the hardness of the ceramic material is 1000 kgf / mm ² or more in Vickers hardness. 4. The average particle size of the powder particles of MoS ₂ is 5 to 3.
The adjusting shim according to claim 1, wherein the adjusting shim is 0 μm. 5. The adjusting film according to claim 1, wherein the polymer of the composite material coating film is at least one of polyamideimide, polyimide, polytetrafluoroethylene, polyphenylene sulfide, and diallyl phthalate resin. Sim. 6. The content of the polymer in the composite film is 50 to 95% by volume.
Or the adjusting shim according to item 5.