JP2563845B2 - Belt vibration suppressor - Google Patents

Description

The present invention relates to a device for suppressing vibration of a timing belt provided in an internal combustion engine, a rear wheel drive mechanism of a motorcycle, a machine tool, a textile machine, or the like.

[Conventional technology]

A timing belt of this type is usually formed of rubber, and the surfaces of the belt teeth that engage with the pulleys are covered with canvas to prevent wear, but the rubber is exposed on the back surface of the belt.

Now, when the timing belt is installed in the internal combustion engine,
There is a natural frequency in the span formed between the pulleys, and when the meshing frequency matches the natural frequency due to the rotation speed of the internal combustion engine, span resonance occurs and the span vibration becomes severe, which causes noise. It gets particularly large. Therefore, conventionally, for the purpose of preventing the noise generation of the belt, there has been proposed one in which a roller is engaged with the back surface of the belt and the vibration of the belt is suppressed by the roller. The rolling mechanism such as the roller is adopted as the mechanism for suppressing the vibration in order to prevent the back rubber of the belt from being worn due to the contact with the vibration suppressing mechanism.

[Problems to be Solved by the Invention]

However, such a conventional device has a problem that the structure is complicated and expensive because it has a rolling mechanism.

The present invention has been made for the purpose of reliably suppressing the vibration of the timing belt with a simple configuration.

[Means for solving the problem]

The belt vibration suppression device according to the present invention includes a vibration isolating member having a smooth surface that is in sliding contact with the tooth crests of the belt teeth, and the vibration isolating member is in sliding contact with only part of the entire width of the belt teeth. I am trying.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows a schematic configuration of a belt vibration suppressing device according to an embodiment of the present invention. The belt vibration suppressing device 20 is provided in an internal combustion engine, and is arranged inside the endless timing belt 14 wound around a plurality of pulleys 11, 12, and 13, that is, on the belt tooth side. Also, belt vibration suppression device 20
Is provided between the pulleys 11 and 12 in this figure. Each pulley rotates clockwise in the figure, and the timing belt 14 rotates in the direction of arrow A.

FIG. 1 shows a belt vibration suppressing device 20 and a timing belt 14. The timing belt 14 has a conventionally known structure. That is, the belt main body is formed of rubber, and the surface of the belt teeth 15 is covered with canvas, but the rubber is exposed on the back surface of the belt. In the present embodiment, the rubber includes synthetic rubber and urethane rubber,
Natural rubber is also included. Now, the canvas is toothed pulleys 11 and 12
It is provided in order to prevent wear due to meshing with (FIG. 2), and is formed of, for example, nylon 66 or the like, and has a friction coefficient smaller than that of the rubber surface on the back surface of the belt.

The belt vibration suppression device 20 is attached to a support mechanism (not shown) and is supported so as to be displaceable in the direction in which it comes in contact with and separates from the belt 14, that is, in the direction of the arrow B. Fixed. The belt vibration suppressing device 20 has a mounting portion 21 connected to the support mechanism and a plate-shaped vibration damping member 22 fixed to the lower surface of the mounting portion 21. The anti-vibration member 22 is made of metal such as iron, stainless steel, aluminum alloy, and is made of synthetic resin or FR.
It may be molded from P or the like. Further, the surface of the vibration isolating member 22 may be subjected to a treatment for reducing frictional resistance such as chrome plating. The upper surface of the vibration isolator 22 is formed in a flat shape, and the lower surface of the vibration isolator 22 has a special shape in order to effectively suppress the vibration of the belt 14.

The shape of the bottom surface of the vibration isolating member 22 will be described with reference to FIGS. 3 to 5.

The lower surface of the vibration isolating member 22 engages with the tooth top surface 15a of the belt tooth 15 and does not contact the side surface or the tooth bottom surface of the belt tooth 15.
As shown in FIG. 3, among the both ends of the vibration isolator 22,
In the front end portion 23 located on the front side in the traveling direction of the belt 14 and the rear end portion 24 located on the rear side in the traveling direction, the portions in contact with the belt teeth 15 each have a roundness, and the curvature thereof. The radius of the rear end portion 24 is larger than that of the front end portion 23. That is, the lower surface of the vibration isolating member 22 is a smooth surface that makes smooth sliding contact with the belt 14.

As shown in FIG. 4, a pair of pressing portions 25 and 26 that engage with both edges of the belt teeth 15 are formed on the lower surface of the vibration isolating member 22. That is, the pressing portions 25 and 26 are not provided over the entire width of the belt teeth 15, but are formed so as to engage only a part of the entire width of the belt teeth 15, and the pressing portions 25 and 26 are formed.
A space 27 is formed between them. Further, the pressing portions 25 and 26 extend along the longitudinal direction of the vibration isolating member 22, that is, the traveling direction of the belt 14, and the lower surface thereof protrudes in an arc shape as shown in FIG. Therefore, the presser portions 25 and 26 are provided with the belt teeth 15
It has a roundness at the portion that comes into contact with the tooth tip surface of the belt tooth 15 only at its tip.

As described above, the pressing portions 25 and 26 have a shape that engages with both edge portions (see FIG. 4) of the belt teeth 15. If the pressing portions 25 and 26 are configured to press the entire tooth top surface of the belt tooth 15, the tooth top surface of the belt tooth 15 may be deformed over its entire width and may be worn.
This deformation and wear deteriorate the meshing state between the pulley and the belt, which causes an increase in noise and a decrease in belt durability. In order to prevent such deformation and wear of the belt teeth 15, the pressing portions 25 and 26 may be those that press a part of the belt teeth 15. Therefore, the structure of the pressing portion is, for example, only the central portion of the belt tooth 15 or only one side of the belt tooth 15 is engaged, instead of the configuration of engaging both edge portions of the belt tooth 15 as in the present embodiment. May be

As described above, in the present embodiment, the pressing portion 25 of the vibration damping member 22,
Since 26 is configured to press only a part of the belt tooth 15, there is no risk of deformation and wear of the belt tooth 15, and therefore the belt 14 meshes well with the pulley, and noise is effective. Is reduced.

Further, in this embodiment, as described with reference to FIG. 3, the front end portions 23 and the rear end portions 24 of the pressing portions 25 and 26 are formed as curved surfaces, and refer to FIG. As described above, the portions of the pressing portions 25 and 26 that come into contact with the belt teeth 15 have roundness. That is, the contact portions between the pressing portions 25 and 26 and the tooth crests of the belt teeth 15 are not angular and have a smooth shape. Therefore, the tooth top surface of the belt 14 is brought into smooth sliding contact with the vibration isolating member 22, and the occurrence of wear is reliably prevented.

FIG. 6 shows another example of the sectional shape of the pressing portion 25. In this example, the lower surface of the pressing portion 25 does not project in an arc shape as in the example of FIG. 5, but is in surface contact with the belt teeth 15 and has a rounded corner 25a. Also with this configuration, the same effect as that of the configuration of FIG. 5 can be obtained.

Now, when the anti-vibration member 22 is separated from the belt 14, the belt 14 vibrates and hits the anti-vibration member 22 while the belt 14 is being driven, which causes noise. On the contrary, if the vibration isolating member 22 presses the belt 14 with too much force, deformation and wear of the belt teeth 15 increase, noise may occur, and the durability of the belt may decrease. Therefore, the anti-vibration member 22 has a proper strength.
It is necessary to press 14 and it must be pushed into the belt 14 by a predetermined amount to engage the tooth crests of the belt teeth 15. More specifically, the anti-vibration member 22 moves the belt 14 to the outside (downward in FIG. 2) from the state of touching the tooth crest surface of the belt 14.
It is fixed at the position where it is pushed in by 2 mm to 1.0 mm.

FIG. 7 shows the result of an experimental determination of the relationship between the engine speed and the noise level of the belt provided with the vibration suppressing device according to the present embodiment and the belt having no vibration suppressing device. The solid line P shows the noise level of the meshing primary sound in the belt having no vibration suppressing device, and the alternate long and short dash line Q shows the noise level of the meshing primary sound in the belt having the vibration suppressing device. A solid line R indicates a belt having no vibration suppressing device, and a one-dot chain line S indicates an adding value (overall) of the noise level in each frequency region in the belt having the vibration suppressing device. The resonance of the belt occurs at an engine speed of 1100 rpm (the portion indicated by the symbols T and U), but as can be easily understood from the comparison of the solid lines P and R and the dashed line Q and S, vibration suppression By providing the device, the noise level is effectively reduced especially at an engine speed of 1100 rpm.

FIG. 8 and FIG. 9 show the results of frequency analysis of the noise level when the belt resonance occurs (when the engine speed is 1100 rpm). FIG. 8 shows the noise level in the belt provided with the vibration suppressing device according to the present embodiment,
Further, FIG. 9 shows the noise level in the belt having no vibration suppressing device. In this embodiment, the number of teeth on the drive pulley is
Since it is 24, the meshing primary frequency is 1100 rpm × 24 ÷ 60 seconds = 440 Hz. Therefore, the secondary meshing frequency is 880 Hz and the tertiary meshing frequency is 1320 Hz. The noise levels of the primary meshing frequency, the secondary meshing frequency and the tertiary meshing frequency in the case where the vibration suppressing device is provided are indicated by reference numerals E, F and G, respectively, and in the case where the vibration suppressing device is not provided, the meshing 1
The noise levels of the secondary frequency, the secondary meshing frequency and the tertiary meshing frequency are indicated by the symbols H, I and J, respectively. As can be understood from these, the noise levels of the primary meshing frequency, the secondary meshing frequency, and the tertiary meshing frequency are significantly reduced.

As described below, according to this embodiment, the vibration of the belt is effectively suppressed, and the noise level of the primary sound, the secondary sound, and the tertiary sound generated from the belt is significantly reduced. Further, the vibration suppressing device according to the present embodiment does not have a complicated mechanism such as a roller as in the conventional case, has a very simple structure, and can be obtained at low cost.

When the belt 14 is a so-called double-toothed belt having belt teeth on both inner and outer sides, the vibration suppressing device 20 may be provided on the inner side and the outer side of the belt. It may be provided only in. In short, the vibration suppressing device according to the present invention is for engaging the belt teeth and suppressing the vibration of the belt, and is arranged on the side where the belt teeth are provided.

In addition, although the above-mentioned embodiment applied the present invention to an internal combustion engine, the present invention is not limited to this,
It can also be applied to suppress vibration of a timing belt provided in a rear wheel drive mechanism of a motorcycle, a machine tool, a textile machine or the like.

〔The invention's effect〕

As described above, the vibration suppressing device of the present invention can surely suppress the vibration of the timing belt with a simple structure and can be obtained at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a schematic configuration view showing a belt provided with the belt vibration suppressing device of FIG. 1, and FIG. 3 is a side view of the belt vibration suppressing device. FIG. 4 is a vertical sectional view of the belt vibration suppressing device, FIG. 5 is an enlarged sectional view showing a holding portion, FIG. 6 is an enlarged sectional view showing another example of the holding portion, and FIG. FIG. 8 is a diagram showing a relationship between an engine speed and a noise level in the device, FIG. 8 is a diagram showing a frequency analysis result of a noise level in the device of the embodiment, and FIG. 9 is a diagram showing a frequency analysis result of a noise level in the conventional device. . 14 …… Belt 15 …… Belt teeth 20 …… Belt vibration suppressor 22 …… Vibration isolator 25, 26 …… Holder

Claims (3)

(57) [Claims] 1. A device for suppressing vibration of a timing belt, wherein a belt main body is formed of rubber, comprising a vibration isolating member having a smooth surface in sliding contact with the tooth crests of the belt teeth, wherein the vibration isolating member is A belt vibration suppressing device, which is in sliding contact with only a part of the entire width of a belt tooth. 2. The belt vibration suppressing device according to claim 1, wherein the vibration isolating member is pushed into the belt by a predetermined amount and comes into sliding contact with the tooth crest surface. 3. The belt vibration suppressing device according to claim 1, wherein the vibration isolating member has a rounded portion in contact with the belt teeth.