JPH06229443A - Silent chain - Google Patents

Abstract

PURPOSE:To restrain chord vibration without increasing power loss. CONSTITUTION:The position where parts 32, 34 faced to respective contact parts of a first pin fixed to a connecting hole 30 out of inner peripheral edges of the connecting hole 30 is deviated to a second pin side loosely fitted into the connecting hole 30 from a projecting circular-arc back surface of the first pin is taken as the center of curvature O1 and also as the circular arc having the radius of curvature R equal to that of respective contact parts. The part 33 facing to the contact part on the outer peripheral side to an annular body formed by respective link plates endlessly connected to each other on the second pin equal to that of the circular arc is taken as the circular arc having the curvature R and the center of curvature O1 equal to the circular arc, and the part 35 facing to the contact part on the inner peripheral surface to the annular body in the second pin takes the position where the second pin is deviated to the first pin side from the projecting circular-arc back surface as the center of curvature O2 and as the circular arc having the radius of curvature equal to that of the circular arc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silent chain in which a large number of link plates having teeth engaging with a sprocket are connected endlessly.

[0002]

2. Description of the Related Art Silent chains of this type are widely used in transmissions such as vehicle transmissions and four-wheel drive systems. The basic structure is that a number of link plates forming a pair of teeth are arranged in the longitudinal direction and the plate thickness direction, respectively, and they are connected endlessly by pins. Is a circular cross section similar to the pin in the roller chain, excessive sliding contact occurs at the contact portion between the pin and the inner peripheral edge of the connecting hole in each link plate into which the pin is fitted, and as a result, Friction and wear of this portion cause inconveniences such as a reduction in power transmission efficiency and a reduction in durability.

Therefore, conventionally, when the power to be transmitted is large, a pair of pins rolling each other are inserted into the connecting holes of each link plate to endlessly connect the link plates. One example is shown in FIG. This is proposed by the present applicant in Japanese Utility Model Laid-Open No. 2-51747, and in the silent chain 1 shown here, the teeth 2
A large number of link plates 3 formed in the longitudinal direction and the plate thickness direction, and the toothless guide plates 4 are arranged at both ends in the plate thickness direction, and symmetrically at both ends of the link plates 3. A pair of pins 6 and 7 are inserted into the formed connecting hole 5 and one of the pins 6 is fixed to the guide plate 4, and in each link plate 3, pins located at both ends in the longitudinal direction thereof are provided. , Fixed to its link plate.

The cross-sectional shape of the pins 6 and 7 is shown in FIG. 5, and the shape of the connecting hole 5 is shown in FIG.
FIG. 7 shows a state in which the pair of pins 6 and 7 are fitted to each other. Each of the pins 6 and 7 has a substantially arcuate cross section as a whole, and the convex arcuate back surface is the rolling surface 10, and both ends following this are outside the rolling surface 10 by a predetermined dimension ΔS. The contact surface 12 forms an arc centered on the offset position 11, and the portion on the opposite side of the rolling surface 10 forms a detent arc-shaped detent portion 13. On the other hand, the connecting hole 5 has a cylindrical surface 20 having the same radius of curvature R as that of the contact surface 12, and is substantially in close contact with the anti-rotation portion 13 at the end portions of each link plate 3 in the longitudinal direction. The locking portion 21 is formed so as to be convex toward the center.

Therefore, as shown in FIG. 7, one of the pair of pins 6, 7 inserted into the connecting hole 5 has its contact surface 12 in contact with the cylindrical surface 20 of the connecting hole 5 and rotates. The stop portion 13 engages with the locking portion 21, and as a result,
The pin 6 is fixed in the connecting hole 5. On the other hand, the contact surface 12 of the other pin 7 is the contact surface 1 of each pin 6, 7.
Since the center of curvature of 2 is offset with respect to the rolling surface 10 as described above, it is separated from the cylindrical surface 20 of the connecting hole 5 by a predetermined dimension ΔC, and the rolling surface 10 of the pin 6 of the one side. It is in contact with the rolling surface 10. As a result, the other pin 7 which is not fixed to the connecting hole 5 can move within the connecting hole 5, so that the link plates 3 can be bent, and the silent chain 1 is sprockets (not shown).
And the teeth 2 mesh with the sprocket.

As described above, in the silent chain 1 of the type in which the pins 6 and 7 roll relative to each other, the pin 7 that is not fixed with respect to the connecting hole 5 can move in either the vertical direction of FIG. The chain as a whole is capable of bending both in the direction around the sprocket and in the opposite direction. Therefore, when rotating at a speed equal to or higher than a predetermined speed, string vibration occurs in which the chain vibrates between contact points (span) with the sprocket. Such string vibration not only causes noise, but also causes an increase in oil temperature due to friction, and also causes a decrease in power transmission efficiency and a decrease in durability.

Therefore, in the silent chain 1 described in the above-mentioned publication, a leaf spring 9 for pressing the link plate 3 in the plate thickness direction is bound together with the link plate 3,
In addition, the leaf spring 9 has a spring constant that decreases as the temperature rises, and as a result, the string vibration is suppressed by the frictional force generated between the link plates 3.

[0008]

In the above-described silent chain 1, since the link plates 3 adjacent to each other are pushed in the plate thickness direction and the contact surface pressure becomes high, the link plates 3 relatively move to each other. The frictional force at the time of turning increases, and the stringing vibration of the chain is suppressed by the frictional force. However, the frictional force between the link plates 3 due to the use of the leaf springs 9 is also generated by the relative rotation of the link plates 3 when the chain 1 is wound around the sprocket. Therefore, in the conventional silent chain 1, there is a problem that a part of the power to be transmitted between the sprockets is consumed by the large friction between the link plates 3 and the power loss becomes large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silent chain capable of suppressing string vibration without increasing power loss.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a pair of pins having the same cross-sectional shape, in which convex arcuate back surfaces are rollably contacted with each other, at both ends of each link plate. Part of the first link plate is fixed to the connecting hole of the first link plate and is loosely fitted in the connecting hole of the second link plate, and the other pin is In a silent chain in which a large number of link plates are connected endlessly by being loosely fitted in the connection hole of the first link plate and fixed in the connection hole of the second link plate, An arc-shaped contact portion having a constant curvature is formed in a portion facing the inner peripheral edge of the connecting hole, and a portion of the inner peripheral edge of the connecting hole facing each contact portion of the first pin fixed to the connecting hole,
An arc having the same radius of curvature as the center of curvature as the center of curvature at a position displaced to the second pin side loosely fitted in the connecting hole with respect to the convex arcuate back surface of the first pin, and further A portion of the inner peripheral edge of the connecting hole facing the contact portion on the outer peripheral side with respect to the annular body formed by the endlessly connected link plates of the second pin has the same curvature and the same center of curvature as the arc. A portion of the second pin facing the contact portion on the inner peripheral side with respect to the annular body of the second pin has a curvature center at a position displaced from the convex arc-shaped rear surface of the second pin to the first pin side, and An arc having the same radius of curvature as the arc is characterized.

[0011]

In the silent chain of the present invention as well, a pair of pins are inserted into connecting holes symmetrically formed at both ends of the link plate, and the link plates are connected endlessly by these pins. The pair of pins inserted into the connecting hole of the link plate are in contact with each other on the convex arcuate back surface and are relatively rollable, and the first pin of the pins is fixed to the connecting hole and The contact portions at both ends are in contact with the inner peripheral portion of the connecting hole. On the other hand, the second pin is loosely fitted in the connection hole,
Of the contact portions, the contact portion located on the inner peripheral side of the annular body formed by the link plate contacts the inner peripheral portion of the connecting hole, and the other contact portion, that is, the outer peripheral contact portion is the inner peripheral portion of the connecting hole. Away from. Such a state is a so-called linear portion between the sprockets, and when winding around the sprocket from this so-called linear state, it is not fixed to the connecting hole due to the relative bending of the link plate. Since the pin moves to the outer peripheral side with respect to the fixed pin, the chain smoothly winds around the sprocket. On the other hand, when a load that relatively bends the link plates in the opposite direction is applied, the contact portion on the inner peripheral side of the contact portion of the non-fixed pin is in contact with the connecting hole, Movement of this non-fixed pin is restricted, and as a result, bending of the chain in the direction opposite to the direction in which the sprocket is wound is prevented. That is, the linear portion between the sprockets can be curved so as to bulge outward, but cannot be curved so as to be depressed inward, so that the string vibration at this portion is suppressed.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows the shape of a connecting hole 30 formed in a link plate that constitutes the silent chain according to the present invention. The connecting hole 30 is different from the connecting hole in the conventional silent chain except for the engaging portion. The centers of curvature of the parts are not the same.

That is, the upper side in FIG. 1 is the outer peripheral side of the annular body formed by the endlessly connected link plates, while the lower side is the inner peripheral side of the annular body, and this connecting hole 30 The pair of pins inserted into is the same as the conventional pins 6 and 7 shown in FIG. Therefore, the locking portion 31 formed as a part of the connecting hole 30 has the pin 6
It projects toward the central portion of the connecting hole 30 so as to be in close contact with the detent portion 13 formed in (7). This locking part 3
The upper substantially quadrant portion 32 continuing from 1 and the subsequent substantially quadrant portion 33 and the substantially quadrant portion 34 continuing from the locking portion 31 to the lower side are the contact surfaces 12 of the pins 6 fixed to the connecting holes 30. Is formed as an arc surface having the same radius of curvature R and the same center of curvature O1. On the other hand, a substantially quarter circle portion 35 following the lower half circle portion 34
Has the same radius of curvature R as the above-described quadrants 32, 33, 34, but a predetermined dimension Δ on the left side of FIG. 1 with respect to the center of curvature O1, that is, on the side of the pin 6 fixed in the connecting hole 30.
It is an arc having a position offset by A as the center of curvature O2. This offset amount ΔA is equal to 2 of the displacement amount ΔS of the center of curvature O1 (11) from the rolling surface 10 of the pin 6.
Double the value. Further, since the position of the center of curvature is partially changed as described above, the portion 36 on the side opposite to the locking portion 31 is
It is a straight line part or an arc part close to a straight line.

FIG. 2 shows a state in which a pair of pins 6 and 7 are inserted into a connecting hole 30 in which adjacent link plates are in a so-called linear state, and the end plates of the link plates formed by these pins 6 and 7 are endless. Although not specifically shown, the connection mode is the same as that of the conventional silent chain. One of the pins 6 and 7 is connected by engaging the locking portion 31 with the detent portion 13 and contacting the contact surfaces 12 with the quadrants 32 and 34. Hole 30
Is fixed against. Further, the other pin 7 has an inner surface which is in contact with the rolling surface 10 of the one pin 6 and has a lower contact surface 12 in FIG. The contact surface 12 located on the circumferential side is in contact with the semicircular portion 35 whose center of curvature is O2 at a position offset to the one pin 6 side. On the other hand, the contact surface 12 on the outer peripheral side is separated from the opposing semicircular portion 33, and a clearance ΔC1 of a predetermined dimension is set.

That is, the other pin 7 is fixed to the connecting hole 30a of the other link plate connected to the link plate to which the one pin 6 is fixed. This connecting hole 30a is shown in FIG. As shown by the broken line, it is symmetric with the connecting hole 30 shown by the solid line, and therefore the centers of curvature O1 and O2 in the connecting holes 30a of the other link plates are left and right with respect to the center of curvature O1 and O2 of the connecting hole 30 shown by the solid line. Is the opposite. Therefore, the lower quadrants 34, 35, 34a, 35a of the connecting holes 30, 30a overlap each other, while the upper quadrants 32, 33, 3 of the connecting holes 30, 30a overlap.
A shift corresponding to the gap ΔC1 occurs in 2a and 33a. As a result, the pin 7 that is not fixed to the connecting hole 30 is
The contact surface 12 on the lower side comes into contact with the inner circumference of the connecting hole 30.

When the chain is bent outwardly from the state shown in FIG. 2, that is, when it is bent around a sprocket (not shown), the non-fixed pin 7 moves upward relative to the fixed pin 6. Fixing pin 6
Rolls on the rolling surface 10. Such relative movement is possible because the clearance ΔC1 is set above the non-fixed pin 7. FIG. 3 shows the relative positions of the pins 6 and 7 when the chain is curved in this way.

On the other hand, the bending of the chain in the direction opposite to the above-mentioned direction is possible by moving the non-fixed pin 7 to the lower side in the figure. As shown in FIG. 2, when the chain 12 is in the so-called straight line state, 12 is in contact with the inner circumference of the connecting hole 30 and therefore cannot move further relative to the lower side of the figure.
Therefore, the bending of the chain in the direction opposite to that described above is prevented.

As described above, in the silent chain according to the present invention, no particular resistance force acts on the bending in the direction in which the sprocket is wound, and the bending in the opposite direction is blocked by the pins 6 and 7, and As a result, power loss is small and string vibration is suppressed.

[0019]

As is clear from the above description, according to the silent chain of the present invention, it is possible to bend the sprocket in the direction in which the sprocket is wound around without causing a large amount of friction, and to bend in the opposite direction. The non-fixed pin for the connecting hole is prevented by coming into contact with the inner circumference of the connecting hole. Therefore, the friction between the link plates when they bend relative to each other is small, so that the power loss can be suppressed, and the bending in the direction opposite to the sprocket winding direction is prevented, and the string vibration between the sprockets is prevented. Can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a diagram showing a shape of a connecting hole in an embodiment of the present invention.

FIG. 2 is a side view showing a state in which a pair of pins are inserted into the connecting hole and the link plate is in a so-called linear state.

FIG. 3 is a side view showing the relative position of the pin in the connecting hole when the chain is curved in the direction in which the chain is wound around the sprocket.

FIG. 4 is a partial cross-sectional side view showing an example of a conventional silent chain.

FIG. 5 is a view showing a sectional shape of a pin.

FIG. 6 is a view showing a shape of a connecting hole in a conventional silent chain.

FIG. 7 is a side view showing relative positions of a pair of pins in a connection hole in a conventional silent chain.

[Explanation of symbols]

 6,7 pin 10 rolling surface 12 contact surface 30 connecting hole 32, 33, 34, 35 quarter circle part O1, O2 center of curvature

Claims (1)

[Claims] 1. A pair of pins having the same cross-sectional shape in which the convex arcuate back surfaces are rotatably brought into contact with each other are fitted into connecting holes symmetrically formed at both ends of each link plate, and The pin is fixed in the connection hole of the first link plate and is loosely fitted in the connection hole of the second link plate, and the other pin is loosely fitted in the connection hole of the first link plate and the second link plate In a silent chain in which a large number of link plates are connected endlessly by being fixed to the connecting hole of, the arc-shaped contact portion having a constant curvature is provided at a portion of each of the pins facing the inner peripheral edge of the connecting hole. A portion of the inner peripheral edge of the connecting hole facing the contact portion of the first pin fixed to the connecting hole is formed in the connecting hole with respect to the convex arcuate rear surface of the first pin. No loosely fitted second pin side The outer peripheral side with respect to the annular body formed by the link plates which are endlessly connected to the second pin in the inner peripheral edge of the connecting hole, with the center of curvature as the center of curvature and the same radius of curvature as the contact portions. The portion facing the contact portion of is an arc having the same curvature and the same center of curvature as the arc,
Further, a portion of the second pin facing the contact portion on the inner peripheral side of the annular body with respect to the annular body has a position displaced from the convex arc-shaped back surface of the second pin toward the first pin side as the center of curvature and is the same as the arc. A silent chain characterized by an arc with a radius of curvature.