JP2015224704A - Sprocket and transmission mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sprocket and a transmission mechanism that transmit power while evenly contacting the sprocket and a chain in a width direction and suppresses an unbalanced load in the width direction of the chain, and suppresses occurrence of power eccentric to one side in the width direction due to deviation of alignment, suppresses occurrence of vibration or noise and prevents engagement from being released.SOLUTION: In a sprocket 100, a plurality of teeth 110 are formed on the peripheral surface of a body. An engaging part 111 of the tooth 110 is formed at a predetermined height position so that a circumferential thickness continuously changes in a width direction.

Description

  The present invention relates to a transmission mechanism having a sprocket having a plurality of teeth formed on a peripheral surface of a main body, a plurality of sprockets, and a chain wound around the plurality of sprockets.

As a transmission mechanism that reliably transmits rotation, a transmission mechanism that hangs a chain around a sprocket having a plurality of teeth formed on the peripheral surface of a main body is commonly used.
When the sprocket teeth mesh with the chain, the timing and rotational force are reliably transmitted between the plurality of sprockets, but noise and vibration are inevitably generated due to the meshing.
As a chain for reducing this noise and vibration, a silent chain is known in which a large number of link plates are connected so as to be able to bend in the width direction, and the teeth provided on the link plates mesh with the teeth of the sprocket.
Conventionally, as shown in FIGS. 7 and 8, the meshing portions 511 of the teeth 510 of the sprocket 500 around which the silent chain is wound are evenly meshed with all the link plates in the width direction. In the position (in FIG. 8, three positions t1, t2, and t3 are shown from the side closer to the tooth tip), each is formed into a shape having the same circumferential thickness in the width direction, that is, shown in FIG. In the t1, t2, and t3 cross sections, the meshing portions 511 on both sides in the circumferential direction are formed in parallel to each other, and are configured to mesh with the silent chain uniformly and transmit force.

JP 2010-265996 A

In the initial state, the conventional sprocket 500 is configured so that the force is transmitted by uniformly meshing with the silent chain. However, when tension is applied to the silent chain, the connection pin of the silent chain is bent or In the conventional sprocket, the rotating shaft is bent, and the meshing part of the sprocket teeth and the silent chain are obstructed from uniformly transmitting in the width direction to transmit force, increasing vibration and noise. There is a problem that a large load is applied to a partial region in the width direction of the chain.
Also, when the sprocket is cantilevered, the sprocket's rotating shaft is likely to bend, and the silent chain and the sprocket are misaligned, generating a force that biases the silent chain to one side in the width direction. In addition to this, the guide links of the silent chain strongly contacted the side surfaces of the sprocket teeth to further increase vibration and noise, and in the worst case, there was a risk of disengagement.

In order to suppress an increase in vibration and noise when the alignment between the chain and the sprocket is deviated, a device in which the shape of the side surface of the sprocket tooth is devised is known (see Patent Document 1, etc.).
However, when the connecting pin of the silent chain is bent or the rotating shaft of the sprocket is bent, the sprocket tooth meshing part and the silent chain should contact uniformly in the width direction to transmit the force. Does not contribute to the problem, nor does it directly prevent the occurrence of a force that deviates to one side in the width direction due to misalignment.

  The present invention solves these problems. The sprocket and the chain are uniformly contacted in the width direction to transmit the force, thereby suppressing the uneven load in the width direction of the chain, and due to misalignment. It is an object of the present invention to provide a sprocket and a transmission mechanism that suppress the generation of a force that deviates to one side in the width direction, suppress the generation of vibration and noise, and prevent disengagement.

The sprocket according to the present invention is a sprocket in which a plurality of teeth are formed on the peripheral surface of the main body, and the meshing portion of the teeth continuously has a circumferential thickness in the width direction at a predetermined height position. By being formed in a changing shape, the transmission mechanism according to the present invention is a transmission mechanism having a plurality of sprockets and a chain wound around the plurality of sprockets,
The at least one sprocket is the aforementioned sprocket, thereby solving the above-mentioned problem.

According to the sprocket according to the first aspect and the transmission mechanism according to the sixth aspect, the tooth meshing portion is formed in a shape in which the circumferential thickness continuously changes in the width direction at a predetermined height position. As a result, when the chain and the sprocket start to bite, they do not contact at the same time in the width direction, the contact impact per unit time is reduced, and the total noise and vibration are reduced.
In addition, the shape of the sprocket teeth and the chain can be set so that the connecting shape of the chain and the rotation axis of the sprocket when the chain is tensioned can be complemented by the tooth shape. And evenly contact with each other in the width direction to transmit the force, suppress the eccentric load in the width direction of the chain, and suppress the generation of a force that deviates to one side in the width direction due to misalignment, generating vibration and noise Can be prevented, and the disengagement can be prevented.
Furthermore, the deflection of the rotating shaft of the connecting pin and sprocket changes according to the tension of the chain, but by setting the optimal shape according to it, the friction and noise are reduced, the uneven load in the width direction of the chain is suppressed, Various actions such as prevention of tooth skipping and disengagement can be optimized according to use conditions.

According to the configuration of the present invention, the tooth meshing portion is formed in a shape in which the amount of change in the circumferential thickness in the width direction is increased as it approaches the tooth tip, so that the chain is sprocketed. From the beginning of meshing to the seating, the uniformity in the width direction of the contact between the chain and the sprocket can be smoothly changed.
In this way, only a part of the chain in the width direction contacts at the beginning of meshing, and the shape is set so that it contacts uniformly in the width direction when seated, thereby reducing the noise and vibration during chain meshing. It is possible to suppress the eccentric load in the width direction of the chain at the time.
According to the configuration described in claim 3, the tooth meshing portion is formed in a shape in which the circumferential thickness increases from the end portion in the width direction toward the center portion at a predetermined height position. As a result, when the chain connecting pin has a small amount of deflection, the chain and teeth come into contact with each other in the center in the width direction, and contact with the entire width direction as the deflection increases. The contact reduces friction and noise, and when the load is high, the contact can be made uniformly in the width direction to suppress the eccentric load in the width direction of the chain, and the strength of the chain can be sufficiently maintained.

According to the configuration of the fourth aspect of the present invention, the tooth meshing portion is formed in a shape having the largest circumferential thickness except for the center in the width direction at a predetermined height position. It is possible to set so that the alignment is correct when the rotation shaft of the shaft is bent, it is possible to suppress the eccentric load in the width direction of the chain, and to prevent tooth skipping and disengagement Is possible.
According to the configuration of the fifth aspect, the tooth meshing portion has a circumference from the position where the circumferential thickness is the largest in the width direction toward the one end portion at a predetermined height position. Since the amount of change in the direction thickness and the amount of change in the thickness in the circumferential direction toward the other end are different, the bending of the connecting pin and the bending of the rotation shaft of the sprocket are prevented. Even when superimposed, it is possible to obtain an optimum shape.
According to the configuration of the seventh aspect, the meshing portion of each sprocket tooth has a position where the circumferential thickness becomes the largest in the width direction and a circumferential thickness at a predetermined height position. When at least one or both of the change amounts of the two are different, the contact state with the chain can be made different among the plurality of sprockets, and the total noise can be reduced by making the order of the contact sound different.

The perspective view and side view of the sprocket which concern on 1st Embodiment of this invention. FIG. 2 is a partially enlarged view of FIG. 1 and a sectional view of a tooth. The perspective view and side view of the sprocket which concern on 2nd Embodiment of this invention. FIG. 4 is a partially enlarged view of FIG. 3 and a sectional view of a tooth. The reference drawing of the transmission mechanism which has the sprocket which concerns on 2nd Embodiment of this invention. Sectional drawing of the tooth | gear of the sprocket which concerns on other embodiment of this invention. The perspective view and side view of the conventional sprocket. FIG. 8 is a partially enlarged view of FIG. 7 and a sectional view of a tooth.

The sprocket of the present invention is a sprocket having a plurality of teeth formed on the peripheral surface of the main body, and the meshing portion of the teeth continuously changes in the circumferential thickness in the width direction at a predetermined height position. The transmission mechanism of the present invention is a transmission mechanism having a plurality of sprockets and a chain wound around the plurality of sprockets, and at least one sprocket is formed into a shape (hereinafter referred to as “crowning shape”). The above-mentioned sprocket is a force that transmits the force by uniformly contacting the sprocket and the chain in the width direction to suppress the eccentric load in the width direction of the chain, and to deviate to one side in the width direction due to misalignment. Any specific configuration may be used as long as it suppresses occurrence of vibration, noise, and prevents disengagement.
The chain hung around the sprocket may be any chain such as a silent chain, a roller chain, or a bush chain, and if it has a structure that meshes with the teeth of the sprocket, it may be a flexible transmission member such as a timing belt There may be.
Note that in the drawings referred to in the following description, the dimensions in the circumferential direction are exaggerated from the dimensions in the width direction in order to make the relationship of dimensions easy to understand.

As shown in FIGS. 1 and 2, the sprocket 100 according to the first embodiment of the present invention has a plurality of teeth 110 formed on the peripheral surface, and a predetermined region between the tooth tip 112 and the tooth bottom 113 is formed with a chain. The meshing part 111 which contacts is comprised.
The meshing portion 111 of the tooth 110 has a circumferential thickness that is the largest at the center in the width direction in a region including a predetermined height position, in this embodiment, at least the tooth heights t1 to t3. It is formed in a crowning shape that becomes symmetrically thin in the same way at both ends.
Further, as shown in FIG. 2, the crowning shape of the present embodiment is formed into a shape having the following dimensional relationship in which the amount of change in the circumferential thickness in the width direction is increased as it is closer to the tooth tip.

wa1: circumferential thickness of the end in the width direction at the height t1 near the tooth tip 112 wb1: circumferential thickness at the center in the width direction at the height t1 near the tooth tip 112 wa2: near the middle Thickness in the circumferential direction at the end in the width direction at the height t2 wb2: Thickness in the circumferential direction at the center in the width direction at the height t2 near the middle wa3: Width direction at the height t3 close to the tooth bottom 113 The thickness in the circumferential direction at the end of the wb3: When the circumferential thickness at the center in the width direction at the height t3 close to the tooth bottom 113,
wb1 <wb2 <wb3
wb1-wa1>wb2-wa2> wb3-wa3
It has become a relationship.

The tooth type of the link plate (not shown) of the silent chain is first brought into contact with the height t1 portion near the tooth tip 112 of the meshing portion 111 of the tooth 110, and the contact point continuously moves toward the tooth bottom 113 side. In this case, the sprocket 100 and the silent chain are made uniform in the width direction by matching the bending of the connecting pin of the silent chain due to the chain tension and the crowning shape at the height t3. The force can be transmitted by contact.
In addition, since the amount of change in the circumferential thickness in the width direction is larger as it is closer to the tooth tip, only the center in the width direction is present at the first contact between the meshing portion 111 of the tooth 110 and the silent chain, and the width gradually increases until sitting. Since the entire direction comes into contact, the contact impact per unit time is reduced, and the total noise and vibration are reduced.

If the use condition is centered on a low load that can ignore the bending of the connecting pin of the silent chain due to the chain tension, the crowning shape does not have to be applied at the height t3 position.
Further, the curve on the side of the meshing portion 111 of the cross section of the tooth 110 constituting the crowning shape may be any shape such as an arc, a sine curve, a free curve, or a straight line portion.
Moreover, it is good also as a different shape in the both sides of the circumferential direction.

As shown in FIG. 3 and FIG. 4, the sprocket 200 according to the second embodiment of the present invention has a plurality of teeth 210 formed on the circumferential surface as in the first embodiment. A predetermined region therebetween constitutes a meshing portion 211 that contacts the chain.
The meshing portion 211 of the tooth 210 has one end portion (in the drawing, the right side in the circumferential direction) having a circumferential thickness in a region including a predetermined height position, in this embodiment, at least the tooth height t1 to t3. It is formed in a crowning shape that is thickest at the end portion and thins toward the other end portion (left end portion in the drawing).
Moreover, the crowning shape of this embodiment is formed in the shape which has the following dimensional relationships which increased the variation | change_quantity of the circumferential direction thickness in the width direction, as shown in FIG.

wa1: circumferential thickness of the other end in the width direction at the height t1 close to the tooth tip 212 wb1: circumferential thickness of one end in the width direction at the height t1 close to the tooth tip 212 wa2: circumferential thickness of the other end in the width direction at the height t2 near the middle wb2: circumferential thickness at one end in the width direction at the height t2 near the middle wa3: tooth bottom The circumferential thickness of the other end in the width direction at a height t3 close to 213 wb3: When the circumferential thickness of one end in the width direction at a height t3 close to the tooth root 213,
wb1 <wb2 <wb3
wb1-wa1>wb2-wa2> wb3-wa3
It has become a relationship.

An outline of the transmission mechanism using the sprocket 200 of the present embodiment is shown in FIG.
In the transmission mechanism, a silent chain CH (only the other side of the sprocket 200, 500 is shown for explanation) is wound around two sprockets 200, 500 provided in the housing 220.
One sprocket 500 (left side in the drawing) is supported by the both ends of the housing 220 by a both-end rotating shaft 221, and the other sprocket 200 (right side of the drawing) is supported by the cantilever rotating shaft 222 in a cantilevered manner. Yes.

In such a transmission mechanism, the open side of the cantilever rotating shaft 222 bends due to the chain tension. Therefore, the normal sprocket 500 is misaligned with the silent chain CH. Since the sprocket 200 on the rotating shaft 222 side has the above-described shape, when the cantilever rotating shaft 222 is bent, the sprocket 200 can be uniformly contacted in the width direction. At the same time, it is possible to prevent tooth skipping and disengagement.
The left sprocket 500 shown in the figure may have the shape of the first embodiment described above.

Further, the curve on the meshing portion 211 side of the cross section of the tooth 210 constituting the crowning shape of the sprocket 200 may be any straight line, arc, sine curve, free curve, or the like.
Furthermore, as shown in FIG. 6, the circumferential thickness is greatest at one end than the center in the width direction, and from there, it becomes thinner at both ends and is formed into a crowning shape with different thicknesses at both ends. May be.
With this configuration, even when the cantilever rotary shaft 222 is bent slightly under load, it is possible to make uniform contact in the width direction, and at the time of initial contact between the tooth meshing portion and the silent chain, the width direction Since the entire width direction comes into contact until the seating, the contact impact per unit time is reduced, and the total noise and vibration are reduced.

  Each embodiment described above is a specific example of the sprocket and the transmission mechanism according to the present invention, but the sprocket according to the present invention is not limited to these, and various modifications are possible. Such a transmission mechanism may also be configured by appropriately combining various configurations of sprockets.

100, 200, 500 ... sprockets 110, 210, 510 ... teeth 111, 211, 511 ... meshing portions 112, 212, 512 ... tooth tips 113, 213, 513 ... tooth bottom 114, 214, 514 ... Center shaft hole 220 ... Housing 221 ... Both-end rotating shaft 222 ... Cantilever rotating shaft CH ... Silent chain

Claims (7)

A sprocket having a plurality of teeth formed on the peripheral surface of the main body,
The sprocket is characterized in that the tooth meshing portion is formed in a shape whose circumferential thickness continuously changes in the width direction at a predetermined height position.   2. The sprocket according to claim 1, wherein the tooth meshing portion is formed in a shape in which the amount of change in the circumferential thickness in the width direction increases as it approaches the tooth tip.   The tooth engagement portion is formed in a shape in which a circumferential thickness increases from an end portion in the width direction toward a center portion at a predetermined height position. 2. The sprocket according to 2.   4. The tooth engagement portion according to claim 1, wherein the tooth engagement portion is formed in a shape having the largest circumferential thickness except at the center in the width direction at a predetermined height position. The sprocket described in 1.   The meshing portion of the tooth has a change in the circumferential thickness toward the one end from the position where the circumferential thickness becomes the largest in the width direction and the other end at a predetermined height position. The sprocket according to any one of claims 1 to 4, wherein the sprocket is formed in a shape having a different amount of change in thickness in a circumferential direction toward the surface. A transmission mechanism having a plurality of sprockets and a chain hung around the plurality of sprockets,
The transmission mechanism, wherein at least one sprocket is the sprocket according to any one of claims 1 to 4. The at least two sprockets are the sprockets according to any one of claims 1 to 4,
Each sprocket tooth meshing portion is different in at least one or both of the position where the circumferential thickness is the largest in the width direction and the amount of change in the circumferential thickness at a predetermined height position. The transmission mechanism according to claim 6, wherein the transmission mechanism is characterized.

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