JP3465011B2 - Connecting rod for internal combustion engine and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting rod for an internal combustion engine and a method for manufacturing the connecting rod.

[0002]

2. Description of the Related Art Fretting wear (fine movement wear) is likely to occur between a large end portion of a connecting rod of an internal combustion engine and a bearing metal mounted in the large end hole. With the recent development of high-speed, high-load engines, and with the decrease in the rigidity of aluminum connecting rods for weight reduction, this tendency is increasing. When fretting occurs, the connecting rod is cracked from the starting point, and the crack develops during long-term use, which may eventually lead to breakage. Japanese Utility Model Laid-Open No. 53-146840 discloses a connecting rod in which a synthetic resin layer is formed on the surface of a bearing metal made of SPCC on the side of the connecting rod in order to reduce the hitting sound. It has been confirmed by the present inventors that the formation of the synthetic resin layer on the back surface of the bearing metal is effective in reducing fretting, although it is insufficient.

[0003]

However, the fretting suppressing effect is small only by forming the synthetic resin layer on the back surface of the bearing metal. Further, the synthetic resin is separated from the bearing metal relatively early during operation, and the synthetic resin is washed away by the lubricating oil invading between the bearing metal and the connecting rod and is lost, so that the fretting suppressing effect is reduced at an early stage. Therefore, in the conventional technique, the fretting suppression is insufficient, and a technique capable of almost completely preventing this has not been established. An object of the present invention is to provide a connecting rod for an internal combustion engine that can suppress fretting sufficiently and over a long period of use, and a method for manufacturing the connecting rod.

[0004]

Connecting rod and its manufacturing method for an internal combustion engine of the present invention to achieve the above object, according to an aspect of the following (1), (2) or Ranaru. (1) In a connecting rod of an internal combustion engine including a connecting rod body, a cap, and a bearing metal, both the bearing metal mounting surface of the connecting rod body and the cap, and the contact surface of the bearing metal with the connecting rod body and the cap, Each side
Forming a synthetic resin layer forming surface having different roughness directions,
A connecting rod for an internal combustion engine, characterized in that a synthetic resin layer is formed on the surface on which the synthetic resin layer is formed. (2) A method for manufacturing a connecting rod, wherein a synthetic resin layer is formed on both the bearing metal mounting surface of the connecting rod body and the cap and the contact surface of the bearing metal with the connecting rod body and the cap. A method for manufacturing a connecting rod for an internal combustion engine, comprising: processing a surface on which a layer is formed into different surface roughness directions, and then forming a synthetic resin layer.

[0005]

In the connecting rod of (1), since the synthetic resin layer is present both on the back surface of the bearing metal and on the inner surface of the connecting rod and the cap, the synthetic resin layers are in contact with each other and rub against each other, which makes it difficult to peel off. , Slight movement of metal surfaces → Adhesion → Fretting wear is greatly suppressed compared to the conventional case. Also, along the surface roughness of one side
Even if the synthetic resin tries to peel for a long time, the other surface
Because it is cut short due to the surface roughness of
It is difficult for large peeling to occur. In the connecting rod manufacturing method of (2), even if the synthetic resin is attempted to be peeled along the surface roughness of one surface for a long time, the synthetic resin is cut into short pieces due to the surface roughness of the other surface. It is difficult for large peeling to occur. Further, even if the synthetic resin layers on the respective surfaces are worn out for a long period of time, the synthetic resin layers remaining in the recesses are prevented from further wearing, and fretting wear at the time of metal contact is also prevented. Therefore, it has durability.

[0006]

1 to 5 show an embodiment of the present invention. In FIG. 1, a connecting rod of an internal combustion engine is composed of a connecting rod body 1, a cap 2 at a large end portion, and a bearing metal 3 split in two that is fitted in a large end hole. The cap 2 is connected by a bolt 4 to the connecting rod body. It is fixed at 1. The connecting rod body 1 and the cap 2 are made of aluminum alloy or steel,
The backing material of the bearing metal 3 is a mild steel plate, which is a cold rolled steel plate (SP
CC).

As shown in FIG. 3, a synthetic resin layer 5 is formed on the bearing metal mounting surfaces of the connecting rod body 1 and the cap 2. Also, of the bearing metal 3,
As shown in FIG. 2, a synthetic resin layer 6 is also formed on the contact surface (bearing metal back surface) with the connecting rod body 1 and the cap 2. PAI is used as the synthetic resin of the synthetic resin layers 5 and 6, and it has excellent wear resistance and load resistance against the lubricating oil temperature, and also has excellent adhesion to the base material surface. The synthetic resin layer 5 and the synthetic resin layer 6 have a pencil hardness of 1H to 4H, and MoS ₂ as a solid lubricant,
A resin coating layer containing one or more of PTFE (polytetrafluoroethylene) and graphite in a total weight ratio of 27% or less, preferably 5 to 16% by weight,
Preferably used. Further, among these types of solid lubricants, PTFE is most suitable because it has a small friction coefficient and shows excellent slip characteristics in combination with a synthetic resin.

A lining 7 made of an aluminum alloy or a copper bearing alloy is formed on the inner surface of the bearing metal 3 (contact surface with the crank pin). The aluminum-based bearing alloy is not particularly limited, but for example, Al
3 to 20 wt% Sn and 10 wt% or less Si,
2.5% wt% or less Cu and / or Mg, 5 wt
The one containing Pb of not more than% is used. As the copper-based bearing alloy, Sn-Pb-Cu-based Babbitt metal and Cu-Pb-based Kelmet metal are used, and the Kelmet metal is usually used by overlay plating.

As a method for forming the synthetic resin layer 6 on the back metal of the back metal 3, the surface of the back metal is first roughened with paper (paper containing ceramics, etc.), then degreased, and then spray coating or dipping. A resin having a predetermined film thickness is coated by dipping (in this case, masking is required on the lining surface) or by printing or the like. Then, the resin coating layer can be completed by baking at 160 ° C. to 220 ° C. for about 30 minutes. Also, regarding the formation of the synthetic resin layer 5 on the large end surfaces of the connecting rod body 1 and the cap 2,
Almost the same as forming the resin layer on the back surface of the bearing metal 3, before and after processing, the inner surface of the large end is roughened by streaking,
After degreasing, a synthetic polymer layer having a predetermined thickness is coated by spray coating or the like, and then 160 ° C to 220 ° C.
The synthetic resin layer 5 is completed by baking for about 30 minutes. The coating thickness should be slightly thicker than the base roughness, the bearing metal resin layer thickness is 3-5 μm, and the connecting rod large end hole resin layer thickness is 4-10 μm. It is desirable that the thickness is 7 to 15 μm.

In the above manufacturing method, the surface roughness is
Bearing metal 3 side is 1 to 4 μm Rz (Rz is JIS 10
(Point average roughness) is desirable, and the connecting rod large end hole surface is desirably 3 to 5 μmRz. Further, as the direction of the surface roughness, the direction of surface roughness of the surface of the back metal 3 on which the synthetic resin layer 6 is formed and the direction of surface roughness of the surface of the connecting rod body 1 and the surface on which the synthetic resin layer 5 of the cap 2 is formed. , As shown in FIG. 4, are different from each other, for example, orthogonal,
Is desirable.

A synthetic resin layer 6 formed on the back surface of the bearing metal 3, a connecting rod body 1 and a cap 2
The synthetic resin layers 5 formed on the surface of the large end hole may be made of the same material or different materials, but it is desirable that the sliding characteristics be made different from each other.
For example, the synthetic resin layer 6 of the bearing metal 3 is made of PTFE.
A PAI (polyamide imide) -based resin layer containing 5 to 16 wt% of a solid lubricant made of (polytetrafluoroethylene) is used, and the synthetic resin layer 5 of the connecting rod body 1 and the cap 2 does not contain a fixed lubricant.
The combination of the different resin layers having different sliding characteristics is excellent in fretting suppression. This relationship may be reversed, and the synthetic resin layer 6 of the bearing metal 2 is set to P
The resin layer of only AI may be used, and the synthetic resin layer 5 of the connecting rod body 1 and the cap 2 may be PAI containing a fixed lubricant.

Next, the operation will be described. When a synthetic resin layer was formed on both the large end hole surfaces of the connecting rod body 1 and the cap 2 and the back surface of the bearing metal 3 (the present invention), the material combinations of the resin layers 5 and 6 were changed variously. Cases (Examples 1 to 6) and cases where the resin layer is formed only on one surface of the bearing metal and the connecting rod body and the cap (comparative example, not included in the present invention)
Table 1 shows the case of not forming on both (comparative example, conventional). Then, in each case, an endurance test in which fretting occurred was conducted, and the resulting area in which fretting occurred is shown in FIG. However, the test conditions were as follows. Engine 4-cylinder 2000cc Maximum rotation speed 6000 rpm Load full load oil temperature 120 ° C time 180Hr Here, the material combination of Comparative Example 1 caused fretting at the time of about 50Hr from the end of the durability test, and the connecting rod was broken. The generated area is shown in FIG.

[0013]

[Table 1]

From the results shown in FIG. 5, in the case of Comparative Examples 2 and 3 in which the resin coating layer was formed on either the back metal or the large end face of the connecting rod, the anti-fretting resistance was significantly higher than that of Comparative Example 1 in which nothing was processed. Although the property is improved, this is not enough, and the area of the portion where the coating layer is lost reaches about 50%. Furthermore, during long-term durability, there is concern that the connecting rod may break due to fretting. In contrast to these comparative examples, when a synthetic resin layer is applied to both the bearing metal back surface and the connecting rod large end hole surface as in the present invention, the fretting resistance is significantly improved. In particular, as can be seen from Examples 4 and 5, PTF was formed on the surface of the bearing metal 3.
A combination of a PAI (polyamideimide) base resin coat layer containing 5 to 16% of E (polytetrafluoroethylene) and a PAI only resin coat layer containing no solid lubricant on the surface of the connecting rod large end hole. Was the best. Example 6 shows a case where the material of the connecting rod is changed from Al alloy to steel.

The reason why the present invention exhibits excellent fretting resistance as described above can be considered as follows. The bearing metal support mechanism at the large end of the connecting rod is held by the tension of the bearing metal. But,
When the engine is operated at high speed, there is some clearance between the back surface of the bearing metal and the large end surface of the connecting rod,
Lubricating oil enters the gap. To prevent fretting, when the resin treatment layer is formed only on either the back metal back of the bearing or the surface of the large end hole of the connecting rod (this resin treatment layer is originally transferred to the mating surface and the coating layers contact each other). It is thought that fretting will occur because the resin peeled off by the invasion of oil is washed away and the transfer to the mating surface is blocked, the coating layer disappears at an unexpected speed, and the long life can be expected. To be On the other hand, in the present invention, from the beginning, the synthetic resin layers are formed on both the back surface of the bearing metal 3 and the surface of the large end hole of the connecting rod, and the synthetic resin layers 5 and 6 are in contact with each other to form a coating layer. It is considered that the fretting resistance is significantly improved because the peeling (including both the peeling from the self surface and the one scraped by the mating surface) is unlikely to occur and is not carried away by the invading oil.

In the process of manufacturing the surface of the synthetic resin layer (base) during the manufacturing process, the direction of the surface roughness of the bearing metal 3 and the direction of the surface roughness of the surface of the connecting rod large end hole are adjusted. , If crossed with each other, against fretting occurrence after the coating layer disappears after long-term durability,
It is advantageous. This is because when one of the coating layers is to be peeled off along the streak for a long time, the coating layer is not cut off for a long time because it is cut short by the striation on the mating surface. Moreover, after the coating layer is worn, the resin remaining in the streak on one surface is
This is because the scratches on the mating surface do not come in and come off.

Further, between the bearing metal 3 and the large end hole of the connecting rod, a portion where a relative slip occurs mainly (a portion far from the axial center of the connecting rod in the left-right direction).
Since there is a portion (around the portion that intersects with the axis of the connecting rod) that simply has a high surface pressure, for example, a PTFE (polytetrafluoroethylene) -containing PAI base resin having excellent sliding characteristics is provided on the bearing metal 3 side. Layers,
P with excellent peeling strength on the large end hole surface of the connecting rod
By coating a resin layer of only AI (or vice versa), both properties can be provided, and as shown in Examples 4, 5 and 6, the fretting resistance is further improved and the life is improved. Can be obtained.

[0018]

According to the first aspect of the present invention, since the synthetic resin layer is formed on both the back surface of the bearing metal and the surface of the large end hole of the connecting rod, it is difficult for the resin to come into contact with the resin and peeling off. Abrasion property can be greatly improved compared with the conventional one. In addition, synthetic resin is long along the surface roughness of one surface.
Even if you try to peel it off, depending on the surface roughness of the other surface
Since it will be cut short, large peeling of synthetic resin will not occur.
It's hard to beat. According to claim 2, since the bearing metal and the large end hole of the connecting rod have different directions of the roughness of the base for forming the resin layer, the synthetic resin layer left in the recess after the synthetic resin layer is worn Further, abrasion can be prevented, and fretting abrasion resistance after progress of abrasion can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a connecting rod of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG.

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG.

FIG. 4 is a plan view showing directions of surface roughness of a bearing metal and a large end hole of a connecting rod.

FIG. 5 is a bar graph showing the fretting occurrence area ratios in the durability tests of Examples 1 to 6 and Comparative Examples 1 to 3.

[Explanation of symbols]

1 Connecting rod body 2 cap 3 Bearing metal 4 volt 5 Synthetic resin layer 6 synthetic resin layer 7 lining

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiichi Shimazaki, 3-65 Midorigaoka, Toyota City, Aichi Prefecture, Otoyo Kogyo Co., Ltd. (72) Inventor, Hiroshi Kanayama 3-65, Midorigaoka, Toyota City, Aichi Prefecture, Oita Co., Ltd. ( 72) Inventor Masaharu Kikuchi 3-65 Midorigaoka, Toyota-shi, Aichi Otoyo Kogyo Co., Ltd. (72) Inventor Fumio Haraguchi 3-65 Midorigaoka, Toyota-shi, Aichi Otoyo Kogyo Co., Ltd. (56) Reference JP 4 -282013 (JP, A) JP-A-4-46219 (JP, A) JP-A-3-288009 (JP, A) JP-A-3-183775 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) F16C 9/04 F16C 7/00 F16C 33/12 C08L 27/18 C08L 79/08

Claims (2)

(57) [Claims] 1. A connecting rod body, a cap,
And the connecting rod of an internal combustion engine comprising a bearing metal, and the bearing metal mounting surface of the connecting rod main body and the cap, on both the contact surface between the connecting rod main body and the cap of the bearing metal, it
Forming surfaces of synthetic resin layers with different surface roughness directions
Then, a connecting rod for an internal combustion engine , wherein a synthetic resin layer is formed on a surface on which the synthetic resin layer is formed. 2. A method of manufacturing a connecting rod, wherein a synthetic resin layer is formed on both the bearing metal mounting surface of the connecting rod body and the cap and the contact surface of the bearing metal with the connecting rod body and the cap. A method for manufacturing a connecting rod for an internal combustion engine, comprising: forming a synthetic resin layer on a surface of the synthetic resin layer in different directions, and then forming the synthetic resin layer.