JPH02524Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a device that prevents the occurrence of noise by disturbing the meshing and impacting period between the silent chain and the sprocket, making the meshing and impacting sounds interfere with each other, without reducing the strength of the sprocket teeth. Regarding.

As shown in Fig. 1, a conventional silent chain has a flank surface F of a link plate L, that is, an outer meshing surface of the link plate and a sprocket tooth T.
The crotch portion C of the link plate L was not in any contact with the sprocket teeth T and was transmitting meshing transmission, so the meshing occurred at a regular cycle and the peak frequency was synchronized with the meshing cycle. It was causing noise.

In order to prevent this noise from occurring, it is necessary to disturb the periodicity of the mesh and lower the peak of the frequency component synchronized with the mesh. As disclosed in the respective specifications of No. 4,168,634, the flank meshing surface of the sprocket teeth is removed and the teeth that do not come into meshing contact with the flank surface are arranged irregularly to disturb the periodicity of meshing. sprocket,
Sprockets with irregularly arranged shallow tooth bottoms, chains with irregularly arranged link plates with long tooth tips, etc. all prevent meshing noise by disrupting the periodicity of meshing.

However, in the conventional noise prevention device mentioned above,
Irregularly arranging the sprocket teeth that do not mesh with the chain flank surface increases the transmission torque load applied to the remaining teeth that mesh with each other, resulting in excessive wear on the tooth surfaces, pitting, and teeth. Insufficient strength of the sprocket, especially the lack of strength of the missing teeth, can cause breakage accidents, and even if sprocket teeth that do not mesh are provided irregularly, the same state of meshing will occur every rotation of the sprocket. Although it is possible to reduce the level of noise without disturbing the periodicity of each rotation, it is not possible to sufficiently prevent noise, and even if the tooth tips of the chain link plates are lengthened, This method has drawbacks such as the inability to disturb the periodicity of each rotation.

In order to eliminate the above-mentioned drawbacks of the conventional art, the present invention has been developed by making the entire link plate into a link plate that engages the flank surfaces and also engages the crotch portion at the initial stage of engagement (hereinafter referred to as the crotch portion meshing link plate). Alternatively, a crotch portion meshing link plate and a flank surface meshing link plate that does not engage the crotch portion at all (hereinafter referred to as a flank surface meshing link plate)
The silent chain formed by the above is brought into contact with the crotch part by removing a part or all of the tooth surface on the side of the tooth tip from the flank surface meshing pitch circle of the sprocket tooth surface that meshes with the flank surface of all the link plates. This is a silent chain noise prevention device that meshes with a sprocket in which teeth are irregularly arranged to prevent noise from occurring.
An embodiment of the invention will be described with reference to the figures.

The outer meshing surface of the link plate of the silent chain is called the flank surface 1, the inner surface is called the crotch part 2, the flank surface 1 meshes with the sprocket teeth on the meshing pitch circle 4 of the sprocket,
The crotch portion 2 slightly protrudes so as to come into contact with the sprocket tooth 3 before the flank surface 1 of the adjacent link plate in the early stages of meshing, and the link plate recedes from the flank surface of the adjacent link plate in the final stage of meshing. If the link plate in which the crotch part 2 does not protrude and does not come into contact with the sprocket teeth 3 either in the initial or final stages of engagement is called the flank engagement link plate 6, then the silent chain shown in FIG. is composed of a crotch portion meshing link plate and a flank surface meshing link plate, and the crotch portion 2 of the crotch portion meshing link plate 5 is placed ahead of the flank surface 1 of the adjacent flank surface meshing link plate 6 at the A position. The crotch portion 2 of the flank surface meshing link plate 6 is in contact with the sprocket teeth 3 and is retracted from the flank surface 1 of the adjacent link plate at the B position and does not participate in meshing at all.

Such a crotch part meshing link plate 5
A part of the tooth surface portion 7 on the tooth tip side from the flank surface of the meshing tooth surface of the sprocket tooth 3 that meshes with the silent chain having the meshing pitch circle 4 is removed in a straight line as shown in FIG. If the missing teeth are removed in a curved line as shown in FIG. 4, or even the entire tooth surface portion 7 is removed as shown in FIG. Therefore, if these missing teeth 3a, 3b, and 3c are irregularly distributed and arranged singly or in combination as sprocket teeth, meshing collision between the missing sprocket teeth 3 and the crotch portion 2 will occur. It is possible to suppress the peak of the frequency component synchronized with the mesh due to the disturbance of the cycle, and to suppress the generation of noise.In addition to the irregularly distributed arrangement of the missing sprocket teeth, the interlocking link plate 5 of the crotch part of the silent chain If the flank surface meshing link plates 6 are arranged irregularly, the impact period of each rotation of the silent chain and the impact period of each rotation of the sprocket will interfere with each other, causing the sprocket teeth 3 and the crotch portion 2 to
The impact period with sprocket 1 becomes even more complicated and disturbed.
It is also possible to disturb the periodicity of each revolution or of each revolution of the chain, greatly increasing the noise prevention effect.

Then, as mentioned above, the teeth with missing tooth surfaces 3a, 3b, 3
Since c is missing only the tooth tip side from the pitch circle 4, the tooth thickness on the pitch circle that meshes with the flank surface 1 does not decrease, and therefore all teeth of the sprocket are missing from all link plates of the silent chain. The tooth 3 that is not missing and the missing teeth 3a, 3b, and 3c are all equally loaded with torque transmission load, and the torque transmission load is concentrated only on the tooth 3 that is not missing. Therefore, there is no risk of excessive wear on the meshing tooth surfaces, pitting, or breakage accidents due to insufficient tooth strength, and the noise caused by meshing collisions can be effectively reduced without reducing the strength of the sprocket teeth. This is an excellent thing that can be prevented.

[Brief explanation of the drawing]

Fig. 1 is an enlarged front view of main parts showing the meshing between a conventional silent chain and a sprocket, Fig. 2 is an enlarged front view of main parts showing the meshing between the silent chain of the present invention and sprocket teeth that do not come off, and Fig. 3
Figures 1 to 5 are enlarged front views of main parts of the first, second, and third embodiments showing the meshing between the silent chain of the present invention and the missing teeth, respectively. 1... flank surface, 2... crotch part, 3...
Sprocket tooth, 4...Pitch circle of sprocket that meshes with the flank surface of the link plate, 5...
Crotch part meshing link plate, 6... flank surface meshing link plate, 7... tooth surface portion on the tooth tip side from the pitch circle of the sprocket.

Claims (1)

[Scope of utility model registration request] A silent chain in which at least some of the link plates are engaged with the crotch portion of the link plate is attached to the crotch portion at least in a portion of the tooth surface portion on the tooth tip side of the flank surface meshing pitch circle of all the link plates of the chain. A silent chain noise prevention device that meshes with a sprocket that has irregularly arranged teeth that have missing parts that do not make contact.