JP3307253B2 - chain - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chain,
In particular, the present invention relates to a timing chain for transmitting a driving force of a camshaft, an oil pump, and the like of an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, a timing chain is used as means for transmitting the rotational force of a crankshaft to an oil pump or a camshaft.

The timing chain has a pair of inner plates having a first hole at one end in a longitudinal direction and a second hole at the other end, a first hole and a second hole of each of the inner plates. And an outer plate having a first insertion hole at one end in the longitudinal direction and a second insertion hole at the other end.

[0004] The one outer plate, the inner link and the other outer plate are alternately shifted and overlapped to form a second insertion hole of the one outer plate, an inner cylinder of a first hole side bush of the inner link, and The pins were inserted by aligning the second insertion holes of the other outer plate, and both ends of the pins were pressed into the second insertion holes of the one outer plate and the second insertion holes of the other outer plate. A plurality of units are formed.

Further, a first insertion hole of one outer plate of one unit and a second insertion hole of an inner link of another unit are provided.
The inner cylinder of the hole-side bush and the first insertion hole of the other outer plate of the one unit are aligned with each other to insert a pin, and both ends of the pin are connected to the first outer plate of the one outer plate of the one unit. A timing chain is formed by press-fitting the insertion hole and the first insertion hole of the other outer plate of the one unit to connect the one unit and the other unit, and repeating this connection.

When a load is applied to the timing chain thus formed, each outer plate receives a tension from the pin on the first insertion hole side (or the second insertion hole side), and releases the tension from the second insertion hole. To the pin on the side (or the first insertion hole side).

Similarly, when each inner plate receives the tension from the bush on the first hole side (or the second hole side), the tension is transmitted to the bush on the second hole side (or the first hole side).

[0008]

By the way, a portion located between each insertion hole of the outer plate of the conventional chain and the end in the short direction, or each hole of the inner plate and the end in the short direction. The portion located between the outer and inner plates has the narrowest width in the short direction of the outer plate and inner plate, and is the weakest in terms of strength.If a large tensile stress is applied to this portion, the outer plate or inner plate will be deformed. This leads to problems such as reduced fatigue life and durability of the chain.

[0009] The present invention has been made in view of the above problems, and has been made in consideration of the weakest inner plate of a chain.
An object of the present invention is to suppress the stress applied to a part and improve the durability and fatigue life of a chain.

[0010]

According to the present invention, a chain is constructed.
The stress on the weakest part of the inner plate
For this purpose, the following measures were adopted.

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

That is, the chain according to the present invention has a pair of inner plates having a first hole at one end in the longitudinal direction and a second hole at the other end, and a space between the first holes of each of the inner plates. And an outer plate having a first insertion hole at one end in the longitudinal direction and an outer plate having a second insertion hole at the other end. In a chain formed by alternately stacking one outer plate, the inner link and the other outer plate, and inserting a pin into each of the insertion holes of the one outer plate and the inner cylinder of each bush of the inner link. The bush has both ends press-fitted into the respective holes of the inner plate, and the stress at the time of press-fitting the end of the bush is longer than that in the short direction of the inner plate. Characterized in that larger in countercurrent.

[0020] The present invention, stress applied to the weak portion located between each hole and a lateral direction end portion of the Lee emissions toner plate,
Based on the inventor's knowledge that the stress is suppressed by accumulating compressive stress in a portion located between the first hole and the second hole of the inner plate . That is, each of the inner plates
When the end of the bush is pressed into the hole,
When a large stress occurs in the longitudinal direction,
The stress from the first hole side to the second hole side and the stress from the second hole side
The stress toward the first hole side becomes a compressive stress, and the first hole and the
Because it accumulates in the site located between the two holes, the inner
Relaxes the compressive stress when tension is applied to the plate
The first hole side bush and the second hole side bush
The tension transmission between the
To the part located between each hole of the
Stress is suppressed.

In order to increase the stress at the time of press-fitting the end portion of the bush in the longitudinal direction as compared with the short direction of the inner plate, for example, the peripheral portion of the end portion of the bush is positioned in the short direction of the inner plate. A gap may be provided at the portion where the heat is applied. The gap may be used as an oil inlet for introducing lubricating oil between the inner wall surface of the bush and the pin. In the chain of the present invention, one outer plate, the inner link and the other outer plate are alternately shifted and overlapped with each other, the second insertion hole of the one outer plate, the inner cylinder of the first hole side bush of the inner link, And a plurality of units each having a pin inserted into the second insertion hole of the other outer plate, and the first insertion hole of one outer plate of one unit and the second hole side bush of the inner link of the other unit. A pin is inserted into the first insertion hole of the cylinder and the other outer plate of the one unit to connect the one unit and the other unit, and the present invention can be applied to a chain formed by repeating this connection.

Further, the chain of the present invention further comprises an intermediate plate having a first through hole at one end in the longitudinal direction and a second through hole at the other end, wherein one outer plate and one inner link are provided. And the intermediate plate, the other inner link, and the other outer plate are alternately shifted and overlapped, and the second insertion hole of the one outer plate, the inner cylinder of the first hole side bush of the one inner link, the intermediate plate A plurality of units formed by inserting pins into the second through hole, the inner cylinder of the first hole side bush of the other inner link, and the second insertion hole of the other outer plate, and forming one outer unit of one unit. A first insertion hole of a plate, an inner cylinder of a second hole side bush of one inner link of another unit, a first through hole of an intermediate plate of the one unit, another inner ring of the other unit A pin is inserted into the inner cylinder of the second hole side bush and the first insertion hole of the other outer plate of the one unit to connect the one unit and the other unit, and this connection is repeatedly formed. It can also be applied to double-row chains.

In short, the present invention can be generally applied to a chain in which a pin is pressed into an insertion hole of the outer plate, and a chain in which a bush is pressed into a hole of the inner plate.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a chain according to the present invention will be described below with reference to FIGS.

In the present embodiment, a timing chain will be described as an example of the chain. As shown in FIGS. 3 and 4, the timing chain is a unit 14 formed by alternately displacing the first outer plate 8, the inner link 7, and the second outer plate 9 and superimposing them.
Are connected to each other.

The first and second outer plates 8 and 9
Is a plate having a first insertion hole 10 formed at one end in the longitudinal direction and a second insertion hole 11 formed at the other end, as shown in FIG.

The inner link 7 includes a first inner plate 1, a second inner plate 2, and two bushes 5 and 6. As shown in FIG. 6, the first and second inner plates 1 and 2 are plates in which a first hole 3 is formed at one end in a longitudinal direction and a second hole 4 is formed at the other end. The first hole 3 and the second hole 4 are formed such that two opposite edges 22 located in the short direction are formed in a straight line along the longitudinal direction, and two opposite edges located in the long direction. The portion 21 is formed by an arc connecting between the base ends and the ends of the linear edge portion 22.

As shown in FIG. 7, the two bushes 5, 6 are formed in a cylindrical shape, and have two gap portions 18 formed by removing two opposing peripheral edges at both ends. In addition, it has a projection 19 rising from the base end of the gap 18. The length from the base end to the end of the gap 18 is not more than the thickness of the first and second inner plates 1 and 2.

Then, both ends of the bushes 5, 6 are
The gap 18 is located in the lateral direction of the first and second inner plates 1, 2 and the protrusion 19
Are press-fitted so as to be located in the longitudinal direction of the first and second inner plates 1 and 2. At this time, as shown in FIGS. 8 and 9, only the protrusions 19 of the bushes 5 and 6 are press-fitted into the first holes 3 and the second holes 4, and the protrusions 1 are formed.
9 is an arc-shaped edge 21 of the first hole 3 and the second hole 4
Press against

Next, as shown in FIG. 10, the unit 14 includes the first outer plate 8 and the inner link 7.
And the second outer plate 9 are alternately displaced and overlapped with each other, so that the second insertion hole 11 of the first outer plate 8 and the inner cylinder of the first hole side bush 5 of the inner link 7, and the second outer plate 9 The pin 13 is inserted by aligning the second insertion hole 11.

Subsequently, the first insertion hole 10 of the first outer plate 8 of one unit 14, the inner cylinder of the second hole side bush 6 of the inner link 7 of the other unit 14, First insertion hole 10 of second outer plate 9
And the pin 12 is inserted.

Further, both ends of the pins 12 and 13 are connected to the first and second pins as shown in FIGS.
The first plate is caulked by a die 17 having a groove 20 having a V-shaped cross section formed along the lateral direction of the outer plates 8 and 9.
And the second outer plates 8 and 9. In this way, the one unit 14 and the other unit 14 are connected, and the connection is repeated to form a timing chain. Hereinafter, the operation and effect of the timing chain according to the present embodiment will be described.

The first and second outer plates 8 and 9 of each unit 14 are provided with pins 12 and 13 in insertion holes 10 and 11 respectively.
Out of the stresses when the end portions are press-fitted, the compression stress is composed of a stress from the first insertion hole 10 side to the second insertion hole 11 side and a stress from the second insertion hole 11 side to the first insertion hole 10 side. Is accumulated in a portion located between the first insertion hole 10 and the second insertion hole 11.

Furthermore, when the first and second outer plates 8 and 9 are caulked by the dies 17 at the ends of the pins 12 and 13, the first and second outer plates 8 and 9 receive greater stress in the longitudinal direction than in the lateral direction. Among the stresses, the stress from the first insertion hole 10 side to the second insertion hole 11 side and the stress from the second insertion hole 11 side to the first insertion hole 10 side are compatible with the compressive stress accumulated at the time of press-fitting the pin end. In addition, a larger compressive stress is generated, and is accumulated in a portion located between the first insertion hole 10 and the second insertion hole 11.

The inner link 7 of each unit 14
When the ends of the bushes 5 and 6 are press-fitted into the first hole 3 and the second hole 4, the first and second inner plates 1 and 2 have protrusions 19 at both ends of the bushes 5 and 6. , But not in the short direction. Then, of the stress in the longitudinal direction, the first hole 3 of the first and second inner plates 1
Between the first hole 3 and the second hole 4 of the first and second inner plates 1, 2. Is accumulated at the site located at

When a load is applied to the timing chain formed as described above and the first and second outer plates 8 and 9 of each unit 14 receive a tension from the first insertion hole side pin 12, the tension is reduced to the second level. The compression stress accumulated in the portion of the first and second outer plates 8 and 9 located between the first insertion hole 10 and the second insertion hole 11 is relaxed and transmitted to the second insertion hole side pin 13. .

Similarly, when the first and second inner plates 1, 2 of the inner link 7 of each unit 14 receive tension from the first hole side bush 5, the tension is applied to the first and second inner plates 1. 2 is transmitted to the second hole side bush 6 by relaxing the compressive stress accumulated in the portion located between the first hole 3 and the second hole 4.

Here, the pins are press-fitted into the first and second insertion holes, and the ends of the pins are crimped as shown in FIGS. FIG. 11 shows the result of measuring the stress applied to the portion located between the two insertion holes. This measurement has a thickness of 1.60 mm
In the outer plate described above, stress was applied to a portion located on a vertical bisector of a line connecting the center of the first insertion hole and the center of the second insertion hole. The vertical axis in the figure represents the distance (mm) from the midpoint of the line connecting the center of the first insertion hole and the center of the second insertion hole to the measurement point, and the horizontal axis represents the longitudinal direction at the measurement point (in the figure). X direction) (kg / mm).

In FIG. 11, the graph shows the measurement result when no tension is applied to the outer plate, the graph shows the measurement result when the tension of 80 kgf is applied to the outer plate, and the graph shows the measurement result when the outer plate is not tensioned. 23
The graph shows the measurement results when a tension of 2 kgf was applied, and the graph shows the measurement results when a tension of 400 kgf was applied to the outer plate.

According to the above graphs, a large compressive stress is accumulated in a portion near the intermediate point, that is, in a portion located between the first insertion hole and the second insertion hole. You can see that it has been alleviated.

Next, when a tension of 400 kgf is applied to the outer plate having a thickness of 1.60 mm, the longitudinal direction of the weakest portion located between the second insertion hole and the lateral end (in the drawing) FIG. 12 shows the result of measuring the amplitude of the stress in the (X direction). The horizontal axis in the figure indicates the amplitude (kg / mm ² ) of the longitudinal stress acting on the weakest part, and the vertical axis indicates the distance Y (mm) from the center of the second insertion hole to the measurement point. .

In FIG. 12, the graph shows the result of measurement on the outer plate in which pins smaller in diameter than the respective insertion holes were inserted into the first insertion hole and the second insertion hole, and the graph shown in FIG. FIG. 9 shows the results of measuring the outer plate by press-fitting the pin end into the hole and the second insertion hole and crimping the press-fit pin end as shown in FIGS.

According to the above graph, it can be seen that the amplitude of the tensile stress applied to the weakest portion of the outer plate in which the compressive stress is accumulated is smaller than that of the outer plate in which the compressive stress is not accumulated. According to the timing chain according to the present embodiment, the first insertion hole and the second insertion hole are not applied to the weakest portion located between each insertion hole of the outer plate and the end in the short direction. Since a large compressive stress can be accumulated in a portion located between the insertion plate and the insertion hole, a stress applied to the weakest portion of the outer plate during a tension load can be suppressed.

Also, the inner plate is located between the first hole and the second hole without applying unnecessary stress to the weakest portion located between each hole and the end in the short direction. Since a large compressive stress can be accumulated in the portion, it is possible to suppress the stress applied to the weakest portion of the inner plate when a tension is applied.

Further, the first hole and the second hole of the inner plate are formed by the straight edge portion 22 located in the short direction and the arc-shaped edge portion 21 located in the long direction, so that a perfect circle is formed. The width of the portion located between each hole and the lateral end is wider than that of the plate having the shape of the hole, and the strength of the weakest portion can be improved.

The first and second holes of the inner plate are, as shown in FIG.
Are extended in the lateral direction, and the extended end and the end of the linear edge 22 are rounded and curved edge 23.
May be connected. According to the first hole and the second hole formed as described above, it is possible to prevent stress from being concentrated on a connection portion between the linear edge portion 22 and the arc-shaped edge portion 21.

Therefore, according to the present embodiment, the stress applied to the weakest portions of the outer plate and the inner plate is suppressed, the fatigue life and durability of the outer plate and the inner plate are improved, and the durability of the timing chain is improved. Can be improved. <Other Embodiments> As means for increasing the stress at the time of press-fitting the pin end into the outer plate in the longitudinal direction as compared with the short direction, as shown in FIG. The first insertion hole 10 and the second insertion hole 11 of 9 may be formed in an elliptical shape whose major axis is formed along the shorter direction. In this case, both ends of the pins 12 and 13 are formed so that the cross section thereof is a perfect circle. Note that the difference between the major axis length l1 and the minor axis length l2 of the first insertion hole 10 and the second insertion hole 11 is preferably about 50 μm.

When the ends of the pins 12 and 13 are press-fitted into the first and second insertion holes 10 and 11 of the first and second outer plates 8 and 9, the first insertion holes are inserted. The peripheral portions located in the longitudinal direction of 10 and the second insertion hole 11 receive greater stress from the pins 12 and 13 than the peripheral portions located in the lateral direction. Among these stresses, the stress from the first insertion hole 10 side toward the second insertion hole 11 side and the stress from the second insertion hole 11 side toward the first insertion hole 10 side become the compression stress, and It is accumulated in the first and second outer plates 8 and 9 at a portion located between the first insertion hole 10 and the second insertion hole 11.

Further, similarly to the first and second outer plates 8 and 9, the first and second inner plates 1, 2
Even if the first hole 3 and the second hole 4 are formed in an elliptical shape whose major axis is along the shorter direction, and both ends of the bushes 5 and 6 are formed so that their cross-sections form a perfect circle. Good. Next, as another means for increasing the stress at the time of press-fitting the pin end into the outer plate in the longitudinal direction as compared with the transverse direction, FIG.
As shown in FIG. 5, the pin 1 press-fitted into the first insertion hole 10 and the second insertion hole 11 of the first and second outer plates 8 and 9.
The major axes of the cross-sections of both ends of the second and the 13th are the first and the second.
The outer plates 8 and 9 may be formed in an elliptical shape along the longitudinal direction. In this case, the first and second insertion holes 10 and 11 of the first and second outer plates 8 and 9 are formed in a perfect circle. The length l3 of the major axis of the cross section of the both ends of the pin
Is preferably about 50 μm.

When the ends of the pins 12 and 13 are press-fitted into the first and second insertion holes 10 and 11 of the first and second outer plates 8 and 9, the first insertion holes are inserted. The peripheral portions located in the longitudinal direction of 10 and the second insertion hole 11 receive greater stress from the pins 12 and 13 than the peripheral portions located in the lateral direction. Among these stresses, the stress from the first insertion hole 10 side to the second insertion hole 11 side and the stress from the second insertion hole 11 side to the first insertion hole 10 side become the compression stress, and It is accumulated in the first and second outer plates 8 and 9 at a portion located between the first insertion hole 10 and the second insertion hole 11.

Further, similarly to the first and second outer plates 8 and 9, the first and second inner plates 1, 2
Both ends of the bushes 5 and 6 press-fitted into the first hole 3 and the second hole 4 are formed so that the major axes of the cross-sections are elliptical along the longitudinal direction of the first and second inner plates 1 and 2. The first hole 3 and the second hole 4 may be formed in a perfect circle. As shown in FIG. 16, the gaps 18 formed at both ends of each of the bushes 5 and 6 of the inner link 7 have a length from the base end to the end of the first and second inner plates 1 and 2. May be formed to be longer than the thickness of In this case, when both ends of the bushes 5 and 6 are press-fitted into the first and second inner plates 1 and 2, a part of the end portion of the gap 18 is formed in the first insertion hole 10 and the second insertion plate 10.
A portion 18a on the proximal end side of the gap portion 18 is located inside the insertion hole 11, and is located outside the first insertion hole 10 and the second insertion hole 11. A portion 18a on the base end side of the gap 18 can be used as an oil introduction port for introducing lubricating oil into the inner cylindrical portions of the bushes 5 and 6.

According to the bushes 5 and 6 formed as described above, the same effects as those of the above-described embodiment can be obtained, and the lubricating oil introduced into the inner cylindrical portions of the bushes 5 and 6 from the oil inlet 18a. Forms an oil film between the inner cylinder wall surfaces of the bushes 5 and 6 and the pins 12 and 13 inserted into the inner cylinder,
Wear of the surfaces of the pins 12 and 13 and the inner cylinder wall surfaces of the bushes 5 and 6 is suppressed. In the embodiment described above, a single-row timing chain has been described as an example of the chain according to the present invention, but a double-row timing chain as shown in FIG. 17 may be used.

The double-row type timing chain connects a plurality of units 16 formed of the first outer plate 8, the first inner link 7a, the intermediate plate 15, the second inner link 7b, and the second outer plate 9. Formed.

The first and second outer plates 8, 9,
The first and second inner links 7a and 7b are configured in the same manner as in the above-described embodiment. The intermediate plate 15 is a plate in which a first through hole (not shown) is formed at one end in the longitudinal direction, and a second through hole (not shown) is formed at the other end.

The unit 16 includes a first outer plate 8, a first inner link 7a, and an intermediate plate 1.
5, the second inner link 7b and the second outer plate 9 are alternately shifted and overlapped, and the second insertion hole 11 of the first outer plate 8 and the inner cylinder of the first hole side bush 5 of the first inner link. And the second through hole of the intermediate plate 15, the inner cylinder of the first insertion hole side bush 5 of the second inner link 7b, and the second insertion hole 11 of the second outer plate.
The pins 13 are inserted in such a manner that both ends are fixed, and both ends of the pins 13 are fixed to the first and second outer plates 8 and 9 in the same manner as in the above-described embodiment.

Subsequently, the first insertion hole 10 of the first outer plate 8 of one unit 16 and the first
The inner cylinder of the second hole side bush 6 of the inner link 7a, the first through hole of the intermediate plate 15 of the one unit 16, and the second hole side bush 6 of the second inner link 7b of the other unit 16 The pin 12 is inserted by aligning the inner cylinder with the first insertion hole 10 of the second outer plate 9 of the one unit 16, and both ends of the pin 12 are
3, the first unit 16 is fixed to the first and second outer plates 8 and 9 of the one unit, and the one unit 16 and the other unit 16 are connected to each other. Is formed.

When a load is applied to the double-row timing chain thus formed, each of the outer plates 8 and 9
Receives the tension from the first insertion hole side pin 12, and this tension relaxes the compressive stress accumulated in the portion located between the first insertion hole 10 and the second insertion hole 11, thereby reducing the second stress. Each of the outer plates 8 and 9 is transmitted to the insertion hole side pin 13.
Can be suppressed from being applied to the weakest part of the above.

Further, when a load is applied to the double-row timing chain, each inner plate 1
It receives tension from the hole side bush 5, but this tension is the first
Since the compressive stress accumulated in the portion located between the hole 3 and the second hole 4 is relaxed and transmitted to the second hole side bush 6, stress is applied to the weakest portion of each of the inner plates 1 and 2. Can be suppressed.

[0059]

In the chain according to the present invention, the inner
When pressing the end of the bush into the plate,
The sheet receives stress acting in the longitudinal direction, and this stress
The stress from the first hole side to the second hole side and the stress from the second hole side to the first
The stress toward the hole side becomes a compressive stress, and the
It accumulates in the site located between the second hole.

Then, tension is applied to the inner plate.
When loaded, the tension relaxes the compressive stress
Transmission of tension between the first hole side bush and the second hole side bush
Is performed, and each hole of the inner plate is
Prevents stress from being applied to the weakest part located between the ends
can do.

[0061]

[0062]

Therefore, according to the chain of the present invention , stress is prevented from being applied to the weakest portion of the inner plate.
Therefore, the fatigue life and durability of the inner plate can be improved, and the durability of the chain can be improved.

Further, by providing a gap as an oil inlet at the periphery of the end of the bush, lubricating oil is introduced into the bush, and an oil film is formed between the pin inserted into the bush and the wall surface of the bush inner cylinder. Can be formed,
The wear resistance of the bush and the pin can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram (1) for explaining a caulking direction of a pin;

FIG. 2 is a diagram (2) for explaining a caulking direction of a pin.

FIG. 3 is a plan view of the timing chain according to the embodiment;

FIG. 4 is a side view of the timing chain according to the embodiment;

FIG. 5 is a diagram showing a configuration of an outer plate.

FIG. 6 is a diagram showing a configuration of an inner plate.

FIG. 7 is a perspective view showing a configuration of a bush.

FIG. 8 is a cross-sectional view of the inner plate into which the end of the bush is press-fitted.

FIG. 9 is a plan view of the inner plate into which the end of the bush is press-fitted.

FIG. 10 illustrates a configuration of a unit.

FIG. 11 is a diagram illustrating a distribution of stress applied to a portion of the outer plate located between the first insertion hole and the second insertion hole.

FIG. 12 is a diagram illustrating the amplitude of stress applied to a portion located between a second insertion hole and a lateral end of the outer plate.

FIG. 13 shows another embodiment of the inner plate.

FIG. 14 is a diagram showing another embodiment of the outer plate.

FIG. 15 is a diagram showing another embodiment of a pin.

FIG. 16 is a diagram showing another embodiment of the inner link.

FIG. 17 is a diagram showing another embodiment of the chain according to the present invention.

[Explanation of symbols]

 1 1st inner plate 2 2nd inner plate 3 1st hole 4 2nd hole 5 bush 6 bush 7 inner link 8 1st outer plate 9th 2 outer plate 10 1st insertion hole 11 2nd insertion hole 12 pin 13 pin 14 unit 17 die 18 gap 18a oil inlet 20 groove

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16G 11/00-17/00

Claims (2)

(57) [Claims] 1. A pair of inner plates having a first hole at one end in a longitudinal direction and a second hole at the other end, and are provided between the first and second holes of each of the inner plates. And an outer plate having a first insertion hole at one end in the longitudinal direction and a second insertion hole at the other end, wherein one outer plate and the inner link In a chain formed by alternately displacing other outer plates and superimposing them and inserting a pin into each of the insertion holes of the one outer plate and the inner cylinder of each bush of the inner link, both ends of the bush are preferably The chain is press-fitted into each hole of the inner plate, and the stress at the time of press-fitting the end portion of the bush is made larger in the longitudinal direction than in the shorter direction of the inner plate. N. 2. A gap is provided at a peripheral edge of the end of the bush by removing a portion located in a short direction of the inner plate, and lubricating oil is provided between the inner wall surface of the bush and the pin by the gap. chain according to claim 1, characterized in that the introduction to the oil introduction port.