JPH0613399Y2 - Silent chain transmission - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a silent chain transmission device capable of quietly transmitting power.

(B) Prior Art Silent chain transmissions generally have a link plate a having a pair of link teeth b and a pair of pin holes e defined by an inner flank c and an outer flank d as shown in FIG. As shown in FIG. 7, a plurality of connecting members, that is, pins, inserted in the pin holes are connected in the lateral and longitudinal directions to form an endless silent chain, and the silent chain is formed by a pair of straight teeth. It is commonly used in engagement with sprockets having sprocket teeth that are surface limited. In such a silent chain power transmission device, when the silent chain goes wound around the sprocket, the link teeth of the first link plates will enter between the sprocket teeth as shown by a ₁ in FIG. 7, the state of a ₂ After passing a ₃
When the state shown by (1) is reached, the outer flanks of the pair of link teeth are stably transmitted in a state of being engaged with the tooth surfaces of the sprocket teeth.

However, the link plate is a
It is achieved instantly when the position of ₃ is reached, so that kinetic energy is instantaneously transmitted, and large vibrations and noises occur periodically.

In order to solve such a problem, there is a conventional Japanese Patent Laid-Open No. 62-159829.
As shown in the publication, a structure has been developed in which the inner flanks that define the link teeth of the link plate are convexly bulged. Although such a structure can reduce noise and vibration to some extent, it is not always sufficient.

The present inventor has conducted various experiments on periodic noise and vibration in the silent chain, and as a result, when the silent chain winds around the sprocket, the noise and vibration first become stable with respect to the sprocket. It has been found that the two link plates that follow the link plate are related to the angle of rotation of the two link plates with respect to the plate that has become stable by the time it contacts the corresponding sprocket teeth of each sprocket.

(C) Problems to be solved by the invention The problem to be solved by the present invention is to make the shape of the link plate of the silent chain or the shape of the sprocket teeth of the sprocket satisfy the newly found relationship. The noise of the silent chain transmission,
It is to further reduce vibration than before.

(D) Means for Solving the Problem The main invention of the present application is to have at least a part of first, second and third link plates pivotally connected in series so as to be rotatable with respect to each other. A first link plate in a silent chain transmission comprising a silent chain having a pair of link teeth defined by an inner flank and an outer flank, and a sprocket having sprocket teeth that mesh with the link teeth of the silent chain. The second and third link plates with the first link plate and the second link plate with the outer flanks of the pair of link teeth meshing with the corresponding sprocket teeth of the sprocket and no relative movement therebetween. When the pivot points of the three link plates are rotated about the pivot points of the The angle until the contact between the inner flank of the second link plate and the sprocket tooth is completed is θ ₁ , and the angle until the inner flank of the third link plate starts contact with the sprocket tooth is θ ₂ . At this time, the shape of the inner flanks of the link teeth of the second and third link plates is determined so that θ ₁ −θ ₂ ≧ 0.

According to another invention of the present application, in the above main invention, the inner flank of the link tooth has a convex curved surface, the tooth surface of the sprocket tooth has a convex curved surface, and the tooth surface of the sprocket tooth has a convex surface. It has a structural feature in that it is formed of a flat surface, or that the continuous first, second and third link plates are irregularly arranged in a silent chain.

(E) Action In the above configuration, when the silent chain is hung on the sprockets and power is transmitted between them, relative movement between the outer flanks of the pair of link teeth of the first link plate and the corresponding sprocket teeth does not occur. The inner flanks of the link teeth of the second link plate rest against the tooth flanks of the sprocket teeth before meshing in the absence. When the second link plate relatively rotates with respect to the first link plate as the sprocket rotates, the engagement between the link teeth of the second link plate and the sprocket teeth is released, and the pair of first link plates The outer flanks of the link teeth mesh with the corresponding sprocket teeth without relative movement between them, while the third link plate has its inner flanks sprocketed before disengagement from the link teeth of the second link plate. It is in contact with your teeth. Therefore, the transmission of power between the silent chain and the sprocket is dispersed, and the magnitude of noise and vibration is reduced.

(F) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a part of the silent chain transmission 1 of this embodiment is shown. In the figure, 2 is a silent chain having first, second and third link plates 3 (3 _a , 3 _b and 3 _c ) pivotally connected to each other by a connecting pin 8 and 10 is a silent chain thereof. It is a sprocket with chain 2. Each link plate 3 has a pair of link teeth 4 defined by an outer flank 5 and an inner flank 6 and a pin hole 7 for receiving a connecting pin. The connecting pin 8 is composed of two parts back to back, and the structure of this connecting pin is known.

Similar to the conventional silent chain, a large number of link plates 3 are laterally stacked by connecting pins 8 and are connected continuously in the longitudinal direction to form an endless silent chain. The first to third link plate 3 _a to 3 _c is may be coupled alternately throughout the silent chain, may be disposed on a portion of the entire length.

The sprocket 10 that meshes with the link teeth 4 of the silent chain 2 has a plurality of sprocket teeth 11 defined by a pair of tooth flanks 12. This sprocket tooth 1
In this embodiment, the tooth flank 1 has a curved surface such as an involute curve. The tooth surface 12 of the sprocket tooth may be a flat surface like the tooth surface of a conventional sprocket.

In FIGS. 1 and 2, there is a first through third 3 among the second link plates of the link plates _b and characterized by the shape of the inside flanks 6 of the third link plate 3 _c consecutive in the present invention . That is, the second link plate 3
_b and the inner flank 6 of the third link plate 3 _c (the flank on the right side in the figure) is the first link plate 3 _a.
The outer flanks 5 of the pair of link teeth 4 mesh with the corresponding sprocket teeth 11 and there is no relative movement between the two (hereinafter, referred to as stable state), the second and third link plates 3 _b , 3 _c. Is rotated about the pivot point between the first link plate and the second link plate, that is, the center O of the connecting pin 8, the pivot points of the three link plates are aligned. The angle from the state until the contact between the inner flank of the second link plate and the sprocket tooth is finished (that is, the winding end pitch line XX of the first link plate 3a and the second link plate in FIG. 1). The angle formed by the contact end pitch line of 3 _b ) is θ ₁ , and the angle until the inner flank of the third link plate starts contacting with the sprocket tooth (that is, the first angle in FIG. 2).
When the angle) between the contact start pitch line of the link plate 3 _a with the winding ends pitch line X-X and a third link plate 3 _c was theta _2, the second and third link plates of the link teeth The shape of the inner flank is determined so that θ ₁ −θ ₂ ≧ 0.

More specifically, the shape of the inner flank 6 that satisfies the above expression is created by bulging the center of the fank in a convex shape with one circular arc having a radius of curvature R.

As a method of bulging the center of the flank in a convex shape as described above, it is not a single circular arc but a combination of a plurality of continuous curves or a straight line and a curve continuous to the straight line. But it's okay.

As described above, since the silent chain transmission of the present invention is characterized by the flank shape of the second and third link plates, any shape of link plate may be used as the first link plate. It will be.
And, it is necessary that the second and third link plates are arranged adjacent to each other so as to be rotatable, but the second and third link plates are alternately arranged over the entire length of the silent chain. Alternatively, or by combining them with a link plate having another shape in a part of the entire length of the silent chain, the connection of the second and third link plates 3 _b and 3 _c may be performed once or a plurality of times. May be arranged at random).

The amount of convex protrusion of the inner flanks of the second and third link plates 3 _b and 3 _c , that is, the maximum amount of interference (the amount of protrusion from the corresponding outer flank of the first and second link plates).
An example of a preferable value of is that when the first to the third link plates are aligned in a straight line, the silent chain pitch is 9.525 mm, the number of teeth is 30, and the tool pressure angle is 30 °,
It is 0.34 mm.

In the silent chain transmission device 1 having the above structure, when the sprocket 10 rotates in the direction of the arrow to transmit power between the silent chain 2 and the sprocket 10, the first, second and third link plates are moved. When the sprocket is wound in order, the outer flank 5 of the right link tooth 4 of the third link plate 3 _c comes into contact with the tooth surface 12 of the sprocket tooth 11, and the second link plate 3 _c
The inner flank 6 of the link tooth on the right side of _b first contacts the tooth flank 12 of the sprocket (FIG. 1). Sprocket 10
There further rotated in FIG around the inserted connecting pin to the continuously rotating pin hole of the left first link plate 3 _a in the counterclockwise direction. Then this time the second link plate 3
The inner flank 6 of the link tooth on the right side of _b begins to move in the direction of retracting more than the outer flank 5 of the left link tooth of the first link plate 3 _a , and finally retracts more than the outer flank 5, and When the link plate rotates through θ _1, its inner flank terminates contact with the tooth flank 12 of the sprocket tooth and the outer flank comes into contact with the corresponding tooth flank 12 of the sprocket tooth.

Before the contact between the inner flank of the second link plate and the tooth surface of the sprocket tooth is completed, that is, the second and third
When the link plate of the _second link plate rotates by θ ₂ , the inner flank of the link tooth 4 on the right side of the third link plate 3 _c contacts the tooth surface of the corresponding sprocket tooth, so that the inner flank of the second link plate and the third flank of The inner flanks of the link plates temporarily contact with the tooth surfaces of the corresponding sprocket teeth at the same time, but the noise and vibration of the silent chain transmission can be reduced.

(G) Effect The silent chain transmission device according to the present invention can reduce noise and vibration as compared with the above-mentioned conventional device. That is, as is clear from the results of the noise test shown in FIGS. 3 and 4, the result of the device of the present invention shown by the solid line (a) is smaller than the result of the conventional method shown by the broken line (b).

[Brief description of drawings]

1 and 2 are enlarged views of a part of the silent chain transmission device according to the present invention, and FIGS. 3 and 4 are diagrams showing noise test results of the silent chain transmission device according to the present invention and a conventional device, FIG. 5 is a plan view showing an example of a conventional silent chain link plate, FIG. 6 is a view showing a part of the conventional silent chain, and FIG. 7 is a view for explaining a state when the silent chain is wrapped around a sprocket. It is a figure. 1: Silent chain transmission device 2: Silent chain 3: Link plate 4: Link tooth 5, Outer flank 6: Inner flank, 8: Connecting pin 10: Sprocket, 11 Sprocket tooth 12: Tooth surface

Claims (5)

[Scope of utility model registration request] 1. A first unit pivotally connected in series so as to be rotatable relative to each other.
A silent chain having at least a portion of second and third link plates, the link plate having a pair of link teeth defined by an inner flank and an outer flank, and meshing with the link teeth of the silent chain In a silent chain transmission having a sprocket having sprocket teeth, the outer flanks of the pair of link teeth of the first link plate mesh with the corresponding sprocket teeth of the sprocket and there is no relative movement therebetween. A state in which the pivot points of the three link plates are aligned when the second and third link plates are rotated about the pivot points of the first link plate and the second link plate. angle theta ₁ to the end of the contact between the inside flanks and the sprocket teeth of the second link plate from, Inside flanks of the third link plates are an angle of up to start to contact with the sprocket teeth θ
_{When 2} , the shape of the inner flanks of the link teeth of the second and third link plates is determined so that θ ₁ −θ ₂ ≧ 0, the silent chain transmission device. 2. The silent chain transmission according to claim 1, wherein the shape of the inner flank of the link tooth is a convex curved surface. 3. The silent chain transmission according to claim 1 or 2, wherein the tooth surface of the sprocket tooth is formed by a convex curved surface. 4. The silent chain transmission according to claim 1 or 2, wherein the tooth surfaces of the sprocket teeth are formed as flat surfaces. 5. A silent chain transmission according to any one of claims 1 to 4, wherein the continuous first, second and third link plates are irregularly arranged in the silent chain. .