JPH0439491Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to a sound-dampening sprocket serving as a sound-dampening (shock-reducing) chain mechanism.

<Prior Art> Generally, when a roller chain engages with a sprocket during transmission, the chain collides with the bottom of the sprocket, producing high-pitched noise, which is one of the causes of noise pollution. In particular, noise regulations for motorcycles are limited to 75 dB or less for vehicles with a displacement of 250 c.c. or more. The amount of noise generated from the chain on this motorcycle only accounts for 20 to 30% of the total noise, but
In order to reduce the noise level from the current noise regulation value of 78db or less to the revised regulation value of 75db or less, it is necessary to improve the meshing of the chain and sprocket as much as possible. Conventionally, as a means for alleviating this collision noise, steps have been formed on both sides of the tooth bottoms of the sprocket body to receive the end surfaces of the link plates of the roller chain when they are engaged, as shown in FIGS. 6A and 6B, for example. A cushion rubber is placed on the step surface that serves as the pedestal (cross section in the figure), and just before the roller part of the roller chain reaches the bottom of the sprocket,
The structure is such that the end surface of the link plate is brought into contact with the cushion rubber. In other words, it is a simple structure in which the ring plate portion is supported by rubber against the tooth bottom, so that the ring plate portion is soft-attached, and the collision noise generated between the tooth bottoms is alleviated.

<Problems to be solved by the invention> However, even though cushion rubber is simply placed on the cushion step (boss) formed on the sprocket body, cushion rubber is actually made of rubber or urethane. It is merely made of an elastic material. Therefore, during use, the cushion rubber wears out or peels off within a short period of time, and the roller portion immediately comes into contact with the bottom of the tooth, producing the original collision noise. Therefore, this is merely a noise reduction measure that only needs to withstand noise control inspections.

In view of the above-mentioned circumstances, the present invention aims to provide a sound-muffling sprocket that eliminates the above-mentioned defects by disposing a buffer sandwich plate on the side of the sprocket body that mechanically expands when the roller chain is caught. be.

<Problems to be Solved> The present invention provides a sprocket for a chain that transmits power to a roller chain.The present invention is based on a sprocket for a chain that transmits power through a roller chain. With buffer sandwich plate,
The base of the buffer sandwich plate is supported by a support shaft inserted into the sprocket body, and the buffer sandwich plate can be freely pushed out to the left and right against elastic force when the chain is engaged.

<Function> Due to the above structure, when the roller chain engages with the sprocket, the end face of the ring plate of the roller chain first comes into contact with the inclined surface of the buffer sandwich plate, and while sliding on the inclined surface, the tooth bottom part As it moves forward, the buffer sandwiching plate itself is pushed outward against the force of a spring or the like. That is, just before the roller chain engages with the bottom of the teeth of the sprocket, it comes into contact with and slides on the buffer sandwiching plate that retreats outward, thereby providing primary buffering of the impact energy. It avoids this and adheres softly to the bottom of the tooth, drastically reducing the noise generated during meshing. After that, when the roller chain moves to the return side and releases from the sprocket, the link plate of the roller chain slides backward on the inclined surface as it separates from the bottom of the tooth, and as a result, a constant pinching action occurs due to spring repulsion, etc. The buffer clamping plate having the above-mentioned structure automatically returns to the clamping standby position in the forward dimension.
The muffling sprocket in this case is particularly effective for use as a drive sprocket.

<Example> Hereinafter, the present invention will be explained based on the drawings of the example.

Figures 1 to 4 show an example in which a coil spring attached to a support shaft is used for elastic movement of the buffer sandwich plate.
1 is a sprocket body for a chain formed of tooth portions 1a and tooth bottoms 1b having a predetermined pitch, and the sprocket body 1 has sloped surfaces on the inside (tooth side) at positions 1c on both sides of the teeth. A buffer sandwiching plate 3 which is divided into at least the same number of teeth as shown in FIG. At the same time, a penetrating support shaft 5 is supported at a predetermined location of the annular groove 4, and one end of the support shaft 5 is attached to the outer periphery of the support shaft, and a coil spring 6 is fixed to the end of the shaft hole 3b of the hooked portion 3a. It is received by a set screw 7 attached to the fifth end, and the buffer sandwich plate 3 itself can be slid outwardly, forming a sound-reducing sprocket 8 as a whole. In this case, the distance a between the inclined upper ends of the concave portions 9, which have an upward U-shape as a whole, of the pair of left and right buffer sandwich plates 3, 3 in the normal state (when they are not engaged with the chain) is set to be wider than the full chain width b of the roller chain 10. , and the interval c on the extension line of the tooth bottom 1b is set narrower than the full chain width b. Further, the height of the buffer sandwich plate is such that it covers the tooth portion.

Next, to explain this action, first, the buffer sandwiching plate 3 of the sprocket body 1 immediately before the meshing position of the roller chain 10 hooked on the noise-reducing sprocket 8
The hooked portion 3a is located at the inner end of the annular groove 4 due to the elasticity of the internal coil spring 6, and the recess 9 is narrowed.

Here, this predetermined buffer sandwiching plate 3 moves the roller chain 10 as the sprocket main body 1 rotates.
When approaching the meshing position of the roller chain 10,
The ends of the link plate 10a on both sides of the buffer sandwich plate 3
The buffer sandwiching plate 3 comes into contact with the inclined surface 2, slides on the inclined surface 2, and enters the recess 9 while pushing the buffer sandwiching plate 3 outwardly against the elastic force of the coil spring 6. Here, for the first time, the roller Chain 10 is tooth bottom 1b
It will fit in and become soft. That is, the link plate 10a slides on the inclined surface 2 and the buffer sandwich plate 3
It spreads out and cushions the escape, alleviating the direct impact.
After this, the tooth portion 1a engages with the tooth portion 1a, thereby minimizing noise generation.

After this, as the sprocket body 1 rotates, the roller chain 10 also rotates and heads toward the return side.
During engagement of this chain 10, the pair of buffer sandwich plates 3, 3 on both sides are connected to the link plates 10, respectively.
A and 10a are maintained in a spread state by contact between inclined surfaces 2 and 2. When the chain 10 faces the return side and starts to disengage from the teeth 1a of the sprocket body 1, the link plate 10a slides on the inclined surface 2 toward the release side, contrary to the above.
The buffer sandwiching plate 3, which has been in the pinching position in a stretched state at the tooth bottom 1b position, automatically returns to its original pinching standby position with its narrow width due to the elasticity of the coil spring 6. .

In this case, the elasticity of the buffer sandwich plate can be achieved by holding a coil spring as shown, or by holding the back of the buffer sandwich plate with a leaf spring (not shown), or by holding the buffer sandwich plate itself. It may also be formed of a deformable elastic member such as a disc spring to provide its restoring force.

<Effects of the invention> As mentioned above, the sound-absorbing sprocket of the present invention has a structure in which buffer sandwiching plates, which can be pushed out by the chain itself, are arranged on both sides of the teeth of the sprocket body over the entire periphery, thereby creating a damping effect when the chain engages. Since the impact is alleviated by the sliding movement of the sloped surface of the sandwich plate, the chain will fit into the bottom of the roller tooth and become soft. In other words, the noise caused by the meshing of the chain and sprocket is reduced. Of course, the height of the left and right buffer sandwich plates is high enough to cover the teeth of the sprocket body, and the buffer sandwich plates are divided at least according to the number of teeth, and have a wall structure that shields both sides of each tooth. Therefore, from this point of view as well, noise is blocked and reduced. For example, the amount of noise generated by a single conventional chain is 5 to 6 dB.
It is possible to reduce the degree of damage. In addition, since the pushing-out and pinching movements of the buffer sandwiching plates are supported by mechanical elasticity due to springs, the movement of the buffering sandwiching plates has practical effects such as being able to withstand long-term use without causing malfunction or failure. It is something to play.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; Fig. 1 is a sectional view showing the main parts, Fig. 2 is a side view of the same, Fig. 3 is a sectional view when engaged, and Fig. 4 is a side view of the same. , 5th
The figure is a side view showing the entire sprocket, Figure 6A,
B is an explanatory diagram of a non-meshing state and an explanatory diagram of an engaged state of a conventional noise-reducing sprocket. 1... Sprocket body, 1a... Teeth, 1b
... tooth bottom, 2 ... inclined surface, 3 ... buffer sandwich plate, 5
... Support shaft, 6 ... Coil spring, 9 ... Recess.

Claims (1)

[Scope of utility model registration request] In a sprocket for a chain that transmits a roller chain, ring grooves are carved on both sides of the peripheral edge near the teeth of the sprocket body, and on both sides of the support shafts that pass through the ring grooves at regular intervals, the ends of the sprocket body are attached to the sprocket body. Insert the hooked part of the buffer sandwich plate, which has a height that projects from the teeth of the plate and has an inclined surface on the inside, and attach the outer end of the coil spring attached to the support shaft inside this hooked part to the stopper at the end of the support shaft. A noise-reducing sprocket that is secured with a screw and can be slid outward by a chain that engages the opposing buffer sandwich plates.