JP2001027307A - Sprocket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To substantially suppress noise resulting from collision between rollers of various kinds of roller chains and tooth bottoms with a common specification. SOLUTION: In a sprocket formed with a plurality of teeth 3 engaging with a roller chain at its outer periphery, respective tooth bottoms of the teeth 3 are respectively formed with, in the extending direction of the teeth 3, grooves 7, each having an opening with a circumferential width smaller than the outside diameter of each roller of the roller chain, and an elastic body 10 is housed in each groove 7 so as to protrude from the opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sprocket provided on a drive shaft or a driven shaft and transmitting power by meshing with a roller chain.

[0002]

2. Description of the Related Art As is well known, a chain transmission using a roller chain transmits power by meshing between a roller chain and a sprocket.
It is widely used as a power transmission means in various motors such as various pumps, blowers, belt conveyors, motorcycles, and internal combustion engines because it has no slip and can obtain a constant speed ratio.

[0003]

By the way, the chain transmission using the roller chain and the sprocket of this kind has an advantage that a large power can be transmitted reliably even when the distance between the shafts is relatively long. However, when the roller of the roller chain is bitten by the teeth formed on the outer periphery of the sprocket with the rotation of the sprocket, the roller collides with the tooth bottom of the sprocket, generating a high sound, This results in noise pollution. For this reason, in a motorcycle in which a certain noise regulation is performed, and in particular, in the above-described chain transmission device used for a device arranged in a room where the above-mentioned noise is a problem, it is strongly required to take some noise reduction measures for the above-mentioned sprocket. Has been requested.

[0004] Therefore, as a conventional sprocket provided with such noise reduction measures, a step is formed by attaching an elastic body such as hard rubber to both end surfaces of the sprocket, and when the roller chain is engaged. Before the roller of the cola chain reaches the tooth bottom, the side surface of the link plate is received by the step portion of the elastic body, thereby alleviating the collision of the roller with the tooth bottom and reducing the generation of the noise. There is a known suppression.

However, in the above-mentioned conventional sprocket, since the thickness of the link plate is smaller than the length of the roller, the contact surface with the elastic body is small, and the surface pressure on the elastic body becomes extremely high. . As a result, there has been a problem that the elastic body which is continuously subjected to impacts is severely worn, and the above-described noise reduction effect is attenuated in a short time.
In addition, although the outer diameter of the link plate generally used is specified by JIS, the special plate of the special specification has various outer dimensions of the link plate. On the other hand, there is also a problem that the same silencing effect cannot be expected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a sprocket capable of greatly suppressing the generation of noise due to the collision between the rollers of various roller chains and the tooth bottom with common specifications. The purpose is to provide.

[0007]

According to a first aspect of the present invention, there is provided a sprocket in which a plurality of teeth meshing with a roller chain are formed on an outer peripheral portion. A groove having an opening whose width is smaller than the outer diameter of the roller of the roller chain is formed in the extending direction of the teeth, and an elastic body is stored in the groove so as to protrude from the opening. Is a sprocket. Here, the invention described in claim 2 is that the opening is
The tooth bottom is formed at a position outside the range of the pressure angle of the tooth where the circumferential driving force acts from the roller.

[0008] The invention described in claim 3 is the first invention.
Alternatively, the elastic body according to claim 2 is formed in a hollow shape, and the invention according to claim 4 is characterized in that the groove has an opening in a circumferential direction in the groove. It is formed so as to be larger than the width dimension of the portion.

The invention described in claim 5 is the first invention.
In the invention described in any one of the above items (4) to (4), the groove is formed so as to open at an axial end face of the sprocket, and the opening at the end face prevents movement of the elastic body in the axial direction. The locking member is detachably attached.

According to the sprocket according to any one of the first to fifth aspects, a groove in which the circumferential width of the opening is smaller than the outer diameter of the roller of the roller chain is formed in the tooth bottom in the direction in which the teeth extend. That is, the sprocket is formed in the axial direction, and the elastic body is housed in the groove so as to protrude from the opening, so that when the roller chain meshes, the roller first protrudes from the opening in the tooth bottom. By contacting the elastic body, its collision energy is reduced. Therefore, the roller does not directly collide with the tooth bottom, and the impact at the time of contacting the tooth bottom is buffered by the elastic body, so that the generation of noise due to this is greatly reduced. .

At this time, since the width of the opening in the circumferential direction is smaller than the outer diameter of the roller, the roller does not enter the groove, and the rotation is accompanied by the rotation of the sprocket. Smooth insertion and removal of the roller is ensured.
Also, unlike the link plate, the outer diameter dimension of the above rollers is generally in accordance with JIS even if it is a special specification, so the same noise reduction by the sprocket of the common specification can be applied to the roller chain of various specifications. The effect can be expected. In addition, even if the silencing effect is attenuated due to damage or wear to the elastic body before the service limit due to wear of the sprocket teeth itself, only the damaged or worn elastic body is taken out of the groove and replaced with a new one. The sound-absorbing effect can be easily restored simply by replacing the sound-absorbing material.

According to the second aspect of the present invention, the opening from which the elastic body protrudes is formed at the bottom of the tooth at a position outside the range of the pressure angle of the tooth. Will be subjected only to the compressive force and will not be damaged by shearing. As a result, a stable silencing effect can be obtained over a long period of time.

Further, as in the invention according to claim 3,
If the elastic body is formed hollow, the impact from the roller can be absorbed by the deformation of the hollow part, not by the compression of the elastic body itself, so that the material deterioration of the elastic body due to repeated compression load can be reduced. Will be possible.

Further, the elastic body thus housed in the groove may be pulled out of the groove due to the centrifugal force acting with the rotation of the sprocket. As a means for preventing this, a method of bonding the elastic body to the groove can also be adopted, but as in the invention according to claim 4,
If the width in the circumferential direction in the groove is formed to be larger than the width of the opening, a projection is formed between the groove and the tooth bottom, so that the elastic body is not bonded. In addition, the protrusions can prevent the elastic body from coming out of the opening, and do not need to be adhered. As a result, the replacement operation when the above-described elastic body is deteriorated is further facilitated.

According to the fifth aspect of the present invention, the groove is formed so as to open at an axial end face of the sprocket, and the opening at the end face prevents the elastic body from moving in the axial direction. Since the locking member is detachably attached,
The elastic body can be housed in the groove from the open end face side, so that the assembling and replacement work becomes easy, and there is no possibility that the elastic body falls off from the groove toward the end face during operation.

[0016]

1 to 4 show an embodiment of a sprocket according to the present invention. In the drawings, reference numeral 1 denotes a sprocket main body. The sprocket body 1 is a disc-shaped member made of steel or the like,
A through hole 1b having a key groove 1a is formed, and a drive shaft or a driven shaft is inserted into the through hole 1b so as to be integrally rotated. A plurality of (in the figure, 17) teeth 3 meshing with the roller chain 2 are formed on the outer peripheral portion of the sprocket body 1 in the circumferential direction.

The roller chain 2 includes a number of inner links 4 and outer links 5. Each inner link 4 is formed by press-fitting two bushes 4b between a pair of link plates 4a, and a roller 6 is rotatably provided on the outer periphery of the bush 4b. The outer link 5 is formed by press-fitting and integrating two pins 5b between a similar pair of link plates 5a. In the roller chain 2, the inner links 4 and the outer links 5 are alternately arranged, and the pins 5b of the outer links 5 are inserted into the bushes 4b of the adjacent inner links 4 and connected to each other. It is formed endless.

In the present embodiment, the teeth 3 of the sprocket body 1 are formed in a U-shape, and a groove 7 having a circular cross section is formed in the bottom of the teeth in the extending direction of the teeth 3, that is, the sprocket. It is formed in the axial direction of the main body 1. The groove 7 is formed so as to open to the tooth bottom side and both end surfaces of the sprocket body 1.
Are formed such that the width in the circumferential direction in the groove is larger than the width of the opening 8 on the tooth bottom side.
Thereby, between the groove 7 and the bottom of the tooth 3, the protrusion 7
a is formed.

The width W of the opening 8 in the circumferential direction (see FIG. 4) is
Is formed so as to be smaller than the outer diameter dimension D. The groove 7 is the bottom of the tooth, and the roller 6
Are formed at positions out of the range of the pressure angle α of the teeth 3 on which the circumferential driving force acts. And this groove 7
, An elastic body 10 is housed therein.

The elastic body 10 is made of nitrile rubber (NB)
R) or a synthetic rubber such as urethane rubber, and is formed into a column shape having an outer diameter substantially equal to the inner diameter of the groove 7. The elastic body 10 is housed in the groove 7 with its side protruding from the opening 8 of the groove 7 toward the tooth bottom. An annular guide ring (locking member) 11 is provided on both end surfaces of the sprocket body 1.
Are detachably attached by bolts 12. The guide ring 11 is made of a thin iron plate, an aluminum plate, or a synthetic resin plate, and is attached so that an outer peripheral portion of the guide ring 11 covers approximately half of an end face opening of the groove 7.

In the sprocket having the above-described configuration, the width W in the circumferential direction of the opening 8 is set to the outer diameter D of the roller 6 of the roller chain 2 at the bottom of the tooth 3 formed on the outer periphery of the sprocket body 1. A narrower groove 7 is formed in the direction in which the teeth 3 extend, and the elastic body 10 is stored in the groove 7 so as to protrude from the opening 8, so that when the roller chain 2 meshes, the rollers 6 First, the opening 8 in the tooth bottom
By contacting and compressing the elastic body 10 protruding from the elastic body 10, its collision energy is reduced.

As a result, since the roller 6 does not directly collide with the tooth bottom and the impact when the roller 6 comes into contact with the tooth bottom is buffered by the elastic body 10, the generation of noise due to this is greatly reduced. Can be relaxed. Moreover, the outer diameter D of the roller 6 is generally JIS even if it is a special specification.
Since it complies with the regulations, the same noise reduction effect can be obtained with respect to the roller chain 2 of various specifications by the sprocket having the above-mentioned configuration of the common specification. Further, since the opening 8 from which the elastic body 10 protrudes is formed at the bottom of the tooth 3 and at a position outside the range of the pressure angle α,
Only the compressive force acts on the elastic body 10.
Therefore, no shearing force acts on the elastic body 10, and a stable noise reduction effect can be obtained for a long period of time.

Further, since the width W in the circumferential direction of the opening 8 is formed smaller than the outer diameter of the roller 6,
The roller 6 does not enter the groove 7, so that the roller chain 2 can be smoothly inserted and removed with the rotation of the sprocket body 1. Conversely, the protrusion 7a is formed between the groove 7 and the bottom of the tooth 3 as a result of forming the width in the circumferential direction in the groove to be larger than the width W of the opening 8. For this reason, the sprocket main body 1 is not
The elastic body 10 can be prevented from coming out of the opening 8 due to the centrifugal force caused by the rotation of the elastic member 10.

In addition, the groove portion 7 is formed so as to open at both axial end surfaces of the sprocket main body 1, and a guide ring 11 for preventing the elastic body 10 from moving in the axial direction is formed in the opening at this end surface by a bolt 12. Since it is detachably attached, there is no danger that the elastic body will fall off from the groove toward the end face during operation.

Further, the elastic member 10 is simply inserted into the groove 7 from the open end face side, and the elastic member 10 is not adhered to the groove 7.
Because it can be housed in the device, assembly becomes easy.
In addition, the teeth 3 of the sprocket body 1 are worn out due to long-term use, and before the use limit is reached, the elastic body 10
Even if the noise reduction effect is attenuated due to damage or wear, the elastic ring 10 is not bonded, so the bolt 12 is loosened and the guide ring 11 is removed.
By simply taking out only the damaged or worn elastic body 10 from the groove portion 7 and replacing it with a new one, the above-mentioned sound deadening effect can be easily restored.

In the above embodiment, the case where the elastic body 10 is formed in a cylindrical shape by synthetic rubber has been described. However, the present invention is not limited to this. The elastic body 10 has various predetermined elastic forces. A material can be used, and the above-mentioned elastic body may be formed hollow. By the way, if the elastic body is formed as a hollow body, the impact from the roller 6 can be absorbed by the deformation of the hollow part without depending on the compression of the elastic body itself. It becomes possible to reduce. Also, the shape of the groove 7 is not limited to a circular cross section,
It can be formed in various cross-sections such as a rectangular cross-section and a trapezoidal cross-section. In any case, as described above, it is preferable to form the opening such that the width in the groove is larger than the width in the circumferential direction of the opening.

Further, an annular guide ring 11 is provided on the end face of the sprocket body 1 so as to be detachable from the bolt 12. However, the present invention is not limited to this. For example, the end face may be provided for each groove 7 or over a plurality of grooves 7. A plurality of strip-shaped locking members for preventing the elastic body 10 from falling off from the opening may be provided separately from each other. In this case, when replacing the elastic body, the elastic body can be easily replaced by removing only the locking member at the position of the worn elastic body.
Further, the present invention provides not only the above-described U-shaped tooth 3 but also
For example, the present invention can be similarly applied to a sprocket having S-shaped teeth.

[0028]

As described above, according to the sprocket according to any one of claims 1 to 5, when the roller chain meshes, the collision energy of the roller is increased by the elastic body projecting from the opening at the bottom of the tooth. By alleviating the noise, the noise generated when the roller collides with the tooth bottom can be significantly reduced, and the roller does not enter the groove, ensuring smooth insertion and removal with the rotation of the sprocket. Therefore, the same noise reduction effect can be obtained for the roller chains of various specifications by the sprockets of the common specification. In addition, even when the noise reduction effect is attenuated due to damage or wear of the elastic body, the noise reduction effect can be easily recovered simply by removing only the damaged or worn elastic body from the groove and replacing it with a new one. Can be done.

In addition, according to the second aspect of the present invention, since only the compressive force acts on the elastic body, the elastic body is not damaged by shearing, and is stable for a long period of time. According to the third aspect of the present invention, since the noise from the roller can be absorbed by the deformation of the hollow portion without depending on the compression of the elastic body itself, the elastic body due to the repeated compression overload can be obtained. Material degradation can be reduced.

Further, according to the invention described in claim 4,
It is possible to prevent the elastic body from coming out of the opening without bonding the elastic body, and to facilitate the replacement work when the elastic body is deteriorated. According to this, the elastic body can be housed in the groove from the end face opening side, so that it is easy to assemble and replace, and there is an effect that there is no possibility that the elastic body falls off from the groove in the end face direction during operation. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a sprocket of the present invention.

FIG. 2 is a partially sectional front view showing a state where a roller chain is engaged with the sprocket of FIG. 1;

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a front view showing a main part of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sprocket main body 2 Roller chain 3 Teeth 6 Roller 7 Groove 7a Projection 8 Opening 10 Elastic body 11 Guide ring (locking member) 12 Bolt W Width of opening in circumferential direction D Outer diameter of roller α Pressure angle

Claims (5)

[Claims] 1. A sprocket in which a plurality of teeth meshing with a roller chain is formed on an outer peripheral portion, an opening having a width in a circumferential direction smaller than a roller outer diameter of the roller chain is formed in a tooth bottom portion of the tooth. A sprocket having a groove formed in the direction in which the teeth extend, and an elastic body protruding from the opening and housed in the groove. 2. The method according to claim 1, wherein the opening is formed at the bottom of the tooth and at a position outside a range of a pressure angle of the tooth on which a circumferential driving force acts from the roller. The sprocket according to claim 1, wherein 3. The sprocket according to claim 1, wherein the elastic body is formed hollow. 4. The groove according to claim 1, wherein the width of the groove in the circumferential direction in the groove is larger than the width of the opening. The sprocket according to 1. 5. The sprocket is formed so as to open at an axial end face of the sprocket, and the opening at the end face is provided with a locking member for preventing the elastic body from moving in the axial direction. The sprocket according to any one of claims 1 to 4, wherein the sprocket is freely mounted.