JPH03107654A - Power transmission mechanism - Google Patents

Abstract

PURPOSE:To reduce noise and belt vibration by differing the tooth pitches of a plurality of continued gear tooth parts provided on a toothed belt and a toothed pulley, and forming the tooth parts of the toothed belt and the toothed pulley by the repeat with this unequal pitch group as a unit pitch. CONSTITUTION:When a toothed pulley 10a on drive side is rotated, its rotating force is transmitted to a toothed pulley 10b on driven side through a toothed belt 20. As an unequal pitch group of the same mode is regularly repeated at a unit pitch P0 in the toothed pulleys 10a and 10b and the toothed belt 20, no unconformity in tooth pitch between the pulley 10a and the belt 20 and between the belt 20 and the pulley 10b is caused even if the pulley 10a is rotated, and the pulley 10b is rotated synchronously with the rotation of the pulley 10a. At that time, the unit pitch P0 is the aggregation of pitches P1-P3, and the engagement is synchronized between the pitches P0, but the engagement is not synchronized between the unequal pitches P1-P3 within the individual unit pitch P0.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power transmission mechanism using a toothed belt.

(Prior Art) In this type of power transmission mechanism, a toothed belt is provided with a constant tooth pitch, and tooth portions are formed by regularly repeating the tooth pitch. The toothed pulley that meshes with the toothed belt also meshes accurately.

It has the same constant tooth pitch as a toothed bed.

(Problems to be Solved by the Invention) In such a conventional power transmission mechanism, noise and belt vibration are inevitably generated due to the meshing between the toothed belt and the toothed pulley. The frequency of the noise vibration generated here is called the meshing frequency, and is expressed by the following formula. The noise vibration level at this meshing frequency Fm is.

This is because the larger the transmitted energy, the more noticeable it becomes, and because the meshing of each individual tooth is all in sync.

Harmonics with respect to the meshing frequency Fm are also likely to occur. Therefore,
Depending on the usage conditions and required performance of the power transmission mechanism,
Noise and belt vibration have become major problems.

Fm-N-n/60 where Fm: meshing frequency (Hz) N: number of pulley teeth n: number of rotations The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to achieve the same performance. The object of the present invention is to provide a power transmission mechanism with less noise and belt vibration than conventional ones.

(Means for Solving the Problems) The power transmission mechanism of the present invention includes a toothed belt having a large number of teeth, and a toothed pulley having a large number of teeth meshing with the teeth of the toothed belt. The toothed belt and the toothed pulley are provided with a power transmission mechanism in which the tooth pitches of a plurality of consecutive teeth provided on the toothed belt and the toothed pulley are different, and the toothed belt and the toothed pulley are The present invention is characterized in that the toothed portion of the toothed pulley is formed, thereby achieving the above object.

(Function) The toothed belt and the toothed pulleys combined with it are given a constant unit pitch.

Synchronous rotation of the toothed belt and toothed pulley is guaranteed. Since unit pitch is a set of unequal pitches.

The meshing of each tooth portion is not synchronized within each unit pitch. Therefore, the noise and vibration level at the meshing frequency is reduced without reducing the number of teeth, and harmonics relative to the meshing frequency are less likely to occur. As a result, the overall level of noise and vibration is reduced. Furthermore, angular velocity fluctuations caused by synchronization of one polygonal meshing are also suppressed.

(Example) The present invention will be explained below based on examples thereof.

The power transmission mechanism of the present invention is as shown in FIG.

- A pair of toothed boots Oa and 10b and an annular toothed belt 20 stretched between the two.

One toothed pulley 10a is a drive-side pulley that is directly driven by a motor or the like. The other toothed pulley 10b is a driven-side pulley that rotates in synchronization with the driving-side toothed pulley 10a by the toothed belt 20.

Both of the pulleys 10a and 10b have teeth portions 11a and llb in which peaks and valleys are alternately repeated on the outer peripheral edge.
It has many.

The annular toothed belt 20 is a resin molded product reinforced with a core material such as a steel cord.

Teeth 2 that mesh with the teeth of toothed pulleys 10a and 10b
1. This tooth portion 21 has three consecutive sets of peak portions 21a and valley portions 21b as one unit.

■In the unit, its tooth pitch p,, P2. Ps
is P.

It is considered to be an unequal pitch group having the relationship: > P + > P z. The entire tooth portion is constructed by regularly repeating units, with the pitch of this one unit being a unit pitch P0. Therefore, the total length of the toothed belt 20 is an integral multiple of the unit pitch P0. Moreover, the regularity of PI+Pg and Pal is maintained in all units.

Toothed boo! Similarly for J 10a and 10b.

Tooth pinch p,, p2. The teeth 11a and Ilb are regular repetitions of an unequal pitch group with p as a - group.
is configured. And that repeating pitch.

That is, the unit pitch P0 is P + 10 Pz + P3. Therefore, the toothed bell 20 meshes accurately with the toothed bell Oa and 10b. Moreover, the diameter of the pitch circle is an integral multiple of the unit pinch P0, regardless of whether the toothed boots Oa and 10b have equal or unequal diameters.

It is desirable that each tooth pitch within each unit pitch P0 has a pitch difference of 10% or more even between pitches that are closest to each other. −This means that if the pitch difference is small,
This is because the effect of suppressing noise and vibration cannot be sufficiently obtained.

In the power transmission mechanism having such a configuration, when the toothed pulley 10a on the three-drive side is rotated, its rotational force is transmitted to the toothed pulley Ob on the driven side via the toothed belt 20.

Toothed pulleys 10a and 10b and toothed belt 20
, the unequal pitch group of the same mode has a unit pitch P
0 is repeated regularly, so even if the drive-side toothed boob Oa rotates.

No mismatch in tooth pitch occurs between the toothed pulley 10a and the toothed belt 20. Similarly, no tooth pitch mismatch occurs between the toothed belt 20 and the driven side toothed pulley 10b. Therefore, the driven side toothed pulley 10b continues to rotate in synchronization with the rotation of the driving side toothed pulley 10a.

At this time, noise and belt vibration are generated due to the meshing of the toothed boobies J10a and 10b with the toothed belt 20, but the main reason for this is that the meshing of the teeth is at the basic pitch P0.
The main reason is to synchronize between the teeth, and not to synchronize all the meshes. That is, the unit pitch P0 is the unequal pitch P,, P2. In the set of P, the meshing is synchronized between the unit pitches 20, but the meshing is not synchronized between the unequal pitches p,, p,, p, within each unit pitch P0. Therefore, compared to a conventional power transmission mechanism in which all tooth pitches are the same and all meshings are completely synchronized, the energy level of noise and vibration at the meshing frequency Fm is lower. Further, harmonics with respect to the meshing frequency Fm are also less likely to occur. As a result, the overall level of noise and belt vibration is greatly reduced. Furthermore, angular velocity fluctuations caused by synchronization of multilateral meshing are also suppressed.

Figures 2(a) and 2(b) show the measurement results of the noise level at the toothed pulley when the conventional power transmission mechanism and the power transmission mechanism of the present invention were operated under the same conditions. Power transmission mechanism, (b) is the power transmission mechanism of the present invention.

An example of tooth pitch is equal pitch (9,525 mm) in conventional mechanisms.
) 2 In the present invention mechanism, unequal 3 pitch (PI = 10.0
01 body, Pz=7.14.41nffl, h=11
．． Regular repetition of P, -28,575
mm). The number of teeth of the toothed pulley is adjusted to be the same in both mechanisms.

In the conventional power transmission mechanism, the peak T at meshing frequency Fm,
In addition to the peak T2 caused by its second and third harmonics. T is occurring. Against this.

In the power transmission mechanism of the present invention, the peak T at the meshing frequency Fm is low (and there are substantially no peaks due to second harmonics or third harmonics).

The noise that can actually be felt by the ears (integral value of the characteristic curve) is significantly smaller in the power transmission mechanism of the present invention. In addition, peak T. is the noise caused by the rotation of the toothed pulley.

In the above embodiment, the basic pitch is composed of three types of unequal pitches, but the number of unequal pitches within the basic pitch may be 2 pitches, or even 4 or more pitches. However, as the number of unequal pitches within the two basic pitches increases, the degree of freedom in selecting the number of pulley teeth decreases, so the number of unequal pitches is preferably 2 to 3.

(Effects of the Invention) In the power transmission mechanism of the present invention, the teeth are formed by regularly repeating groups of unequal pitches, so noise and belt vibration can be reduced without restricting the power transmission capability. It can be suppressed. Therefore, it is possible to improve the usage environment and the like, and also to improve the performance.

Figure 1 is a schematic diagram of one embodiment of the power transmission mechanism of the present invention, and Figures 2 (a) and (b) show a comparison of the noise level between the conventional example and the example of the present invention. FIG.

10a, 1. Ob...Toothed pulley, 20...Toothed belt.

that's all

Claims (1)

[Claims] 1. A power transmission mechanism comprising a toothed belt having a large number of teeth and a toothed pulley having a large number of teeth meshing with the teeth of the toothed belt, the toothed belt and the teeth A plurality of consecutive teeth provided on the toothed pulley have different tooth pitches, and the teeth of the toothed belt and the toothed pulley are formed by repeating the uneven pitch group as a unit pitch. power transmission mechanism.