JPH0676817B2 - Timing belts and belt transmissions - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timing belt and a timing belt transmission which combines the timing belt with a timing pulley.

[0002]

2. Description of the Related Art In a timing belt, the belt pitch (pitch between teeth; hereinafter the same) is set to the design pitch of the pulley, and the belt pitch line pitch is set so that the belt can be accurately meshed with a timing pulley having any number of teeth. Accurate matching of each reference to the design pitch line difference of the pulley is practiced.

On the other hand, it has been known from the research and experiment to date that the life of the tooth lacking of the belt becomes the longest when the pitch difference between the belt and the pulley is slightly minus. When a load torque is applied to the belt, the belt is stretched and the belt pitch increases in the vicinity of the belt tension side where the belt teeth bear the largest tooth load. As a result, the belt pitch and the pulley pitch deviate from each other and the load cannot be evenly shared by the teeth, and an excessive tooth load is applied to one tooth.

Therefore, if the belt pitch is made small in consideration of the fact that the belt is stretched in advance, when the load torque is applied to the belt, the belt pitch is substantially equal to the pulley pitch near the belt tension side. In unison, the load can be shared substantially evenly, which can prolong the life of the belt without teeth.

However, in a pulley with a small number of teeth,
If the belt pitch is shortened to make the pitch difference negative, the pitch difference is accumulated between the number of meshing teeth and the belt tooth portion and the pulley tooth are combined for the combination of the belt and the pulley with a large number of meshing teeth. The parts will not mesh.

That is, as a specific example, for two types of timing belts having a standard pitch of 14 mm and belt widths of 15 mm and 12 mm, for example, the pitch difference of the tooth portion with respect to the pulleys (pulley tooth number 28 ^T -28 ^T _O ). Is changed, and FIG. 5 shows the change in the durability life of the missing teeth of the belt at that time. The damage mode is all due to the shearing of the teeth. In order to eliminate other factors affecting the durable life, the pitch difference is changed by changing the outer diameter of the pulley. As shown in the figure, the belt's durable life is
It becomes maximum around 0.05 mm and increases about 3 times as compared with the case where the pitch difference is zero. Furthermore, when the pitch difference is near 0,
Since the slope of the line showing the life characteristics is large, the durability life changes by about 30% just by changing the pitch difference by 0.01 mm, but there is only about 5% change when the pitch difference is around -0.05 mm. . By making the belt pitch difference negative with respect to the pulley having a small number of teeth in this way, the durability life of the belt can be improved and its variation can be reduced.

[0007]

However, in order to make the pitch difference −0.05 mm, the belt pitch is 13.9.
In the case of 5 mm, for example, if a belt having a tooth portion of 80 ^T meshes with a 120 ^T pulley, a pitch difference is accumulated and a deviation of 4.0 mm (= 0.05 mm × 80) occurs at 80 ^T , and the belt The teeth do not mesh with the pulley. Therefore, it is common practice to match the belt and pulley pitches and pitch line differences at the expense of reduced tooth life.

Further, in the timing belt, the fabric is reinforced along the surface of the tooth portion from the lower portion of the core body.
Reinforcement with woven cloth is indispensable for improving the life of missing teeth. At this time, since the belt pitch line is located substantially in the center of the core body, the pitch line difference is determined by the diameter of the core body and the compressed thickness of the woven fabric. However, the thickness of the woven fabric at the time of compression varies greatly depending on the thickness of the woven fabric itself, the compression rate variation due to the core winding tension, and the like. Therefore, in the belt reinforced with the woven cloth, a considerable variation occurs in the pitch line difference, and the variation in the pitch line difference causes the variation in the pitch difference with respect to the pulley.

As described above, since the tooth gap life of the belt greatly changes due to the change in the pitch difference, it is unavoidable that the life of the timing belt reinforced by the conventional woven fabric becomes large. , The reliability of the transmission was insufficient.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above various problems all at once, to extend the life of a toothless belt even for a timing belt reinforced with a woven cloth, and improve the reliability of the belt transmission. It is in.

[0011]

In order to achieve the above object, in the present invention, the pitch line difference and the pitch of the timing belt are positively different from the pulleys by a predetermined amount.

Specifically, according to the invention of claim 1, the pitch line difference is designed as a timing belt having a tooth portion which meshes with the outer peripheral tooth portion of the timing pulley on the inner periphery and is wound around the timing pulley. 10 to 20% higher than the pitch line difference and 0.02 to 0.15 pitch to the design pitch of the pulley
It is characterized by being increased.

According to another aspect of the present invention, there is provided a timing belt comprising a timing pulley having teeth on the outer circumference and a timing belt having teeth on the inner circumference that mesh with the teeth of the timing pulley and wound around the timing pulley. As a transmission, the timing belt pitch line difference is 10 to 20% higher than the pulley design pitch line difference, and the timing belt pitch is 0.02 to 0.15% higher than the pulley design pitch. It is characterized by having done.

[0014]

With the above construction, in the invention of claim 1 or 2, the belt pitch line difference is 10 to 20% higher than the pulley design pitch line difference, and the belt pitch is higher than the pulley design pitch. Since it is 0.02 to 0.15% larger, the belt pitch is 0.2 to 0.5% shorter than the pulley pitch when meshed with a pulley with a small number of teeth, and the belt pitch and the pulley pitch when meshed with a pulley with a large number of teeth. Is almost the same as. As a specific example, for a pulley with a design pitch of 14.00 mm and a pitch line difference of 1.4 mm, the belt pitch is 14.003 mm (up 0.02%) and the belt pitch line difference is 1.54 mm ( Suppose you wrap a 10% up timing belt. In this case, when wound around the 28 ^T pulley, the pitch difference is-
It becomes 0.028 mm (0.2% shorter), and when wound on a 120 ^T pulley, the pitch difference becomes -0.004 mm (0.003% shorter).

For a pulley having a design pitch of 8.00 mm and a pitch line difference of 0.686 mm, a belt pitch of 8.012 mm (up 0.15%) and a belt pitch line difference of 0.823 mm (20 %
If you wrap up the timing belt (up), 1
8 ^T when wound around the pulley, the pitch difference -0.0
It becomes 36 mm (0.45% shorter), and when it is wound on a 156 ^T pulley, the pitch difference becomes -0.006 mm (0.08% shorter).

As described above, the pitch difference is negative with respect to the small pulley, and the large pulley is sufficiently meshed.

In most of the timing belt transmissions, at least one of the driving and driven pulleys is a small pulley. Since the number of meshing teeth is small on the small pulley side, the belt always fatigues on the small pulley side and reaches the end of its life. However, in the present invention, the fatigue of the belt is reduced by making the pitch difference in the small pulley negative, so that the belt life can be extended.

Further, even if there is a large variation in the pitch line difference and the pitch difference of the belt with respect to the pulley, if the pitch difference is negative by an appropriate amount as described above, the variation in the belt life will be small. Credibility increases.

Furthermore, since the diameter of the core is the same and the belt pitch line difference is increased, the area of the reinforcing portion of the belt below the core is increased. As a result, even if a crack is generated at the root of the belt tooth portion, the crack is prevented from propagating, so that the life of the tooth lacking of the belt can be extended.

At this time, if the pitch line difference of the belt is at least 10% larger than the design pitch line difference of the pulley, the pitch difference does not become so negative even with a small pulley, so that the durability is improved. The effect is small. On the contrary, when the pitch line difference of the belt becomes larger than the designed pitch line difference of the pulley by more than 20%, the pitch difference in the small pulley becomes too negative, and the problem of abrasion occurs during long-term belt running. . From this, the belt pitch line difference is increased by 10-20% relative to the pulley design pitch line difference.

Further, in order to make the pitch difference in the large pulley close to zero, the belt pitch is made about 0.02 to 0.15% larger than the design pitch of the pulley.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a timing belt transmission A according to Embodiment 1 of the present invention.
Is composed of a timing pulley P and a timing belt B wound around the outer circumference thereof. The timing pulley P has a plurality of tooth portions 2, 2, ...
.. are formed with a constant pitch PP, and the height from the tip of each of them to the pitch line LP is the pitch line difference PLDP.

On the other hand, the timing belt B is provided with a belt main body 11 and a large number of tooth portions 12, 12, ...
Are formed side by side, and the tooth portions 12, 12, ... Are meshed with the tooth portions 2, 2, ... On the outer periphery of the timing pulley P, so that rotational power is transmitted in synchronization with the pulley P. I am trying. The belt body 11 is made of chloroprene rubber (neoprene), styrene butadiene rubber, epichlorohydrin rubber, polyurethane rubber, hydrogenated acrylonitrile butadiene rubber, etc., and is formed of a known rubber compound suitable for the purpose of use of the belt B. To be done.

Inside the belt main body 11, a plurality of endless core bodies 13, 13, ... (Reinforcement body) are arranged in parallel in the belt width direction at regular intervals and are inclined with respect to the belt length direction. It is buried in a spiral shape. This each body 13
Is disposed so as to be exposed from the lower surface of the belt body 11 at the bottom surface between the tooth portions 12, 12, and, for example, aramid fiber (aromatic polyamide fiber) or polyarylate fiber,
It consists of fibers with high strength and high elastic modulus.

Further, a reinforcing woven cloth 14 extends from the surface (tooth surface) of each tooth portion 12 of the belt body 11 to the lower surface of the core body 13.
Are covered. This reinforcing woven fabric 14 is made of 6 nylon, 6
6 nylon, 46 nylon, aromatic polyester, tetoron, cotton, rayon, Teflon type yarns or blended yarns are used alone or in combination, and satisfy abrasion resistance and friction coefficient required as a reinforcing fabric for belts. Is woven as follows.

In the belt B, the core body 1 is
3 The pitch line difference PLDB, which is the height from the center pitch line LB to the surface of the woven cloth 14 at the groove bottom surface between the teeth 12 and 12, is 10 to 20% larger than the designed pitch line difference PLDP of the pulley P. Is set (PLDB = 1.1 to 1.2PLDP), and the pitch PB of the tooth portions 12, 12, ...
It is made larger in the range of 0.02 to 0.15% than the design pitch PP of 2, ... (PB = 1.0002 to 1.0
015PP).

When the increasing variable of the pulley P of the pitch line difference PLDB of the belt B with respect to the design pitch line difference PLDP is less than 10%, the pitch difference does not become so negative even for the small pulley P, and the durability is improved. While the effect of improving the property is small, if it exceeds 20%, the pitch difference in the small pulley becomes too negative,
Since the problem of wear arises when the belt B runs for a long time,
It is necessary to increase by 10 to 20%.

Further, in order to make the pitch difference in the large pulley close to 0, the pitch PB of the belt B needs to be larger than the design pitch PP of the pulley P by about 0.02 to 0.15%.

Therefore, in this embodiment, the pitch line difference PLDB of the belt B is 10 to 20 with respect to the designed pitch line difference PLDP of the pulley P.
% Higher and belt B against pulley P design pitch PP
Since the pitch PB of the belt is 0.02-0.15% larger, the belt pitch PB becomes smaller when meshed with the pulley P having a small number of teeth.
Is 0.2 to 0.5% shorter than the pulley pitch PP, and when meshed with a pulley P having a large number of teeth, the belt pitch PB and the pulley pitch PP are substantially the same, and the pitch difference is small with respect to the small pulley P. It also meshes well with the large pulley P. Therefore, by making the pitch difference in the small pulley P negative, the fatigue of the belt B can be reduced and the belt life in the timing belt transmission can be extended.

Even if there is a great variation in the pitch line difference PLDB and the pitch difference of the belt B with respect to the pulley P, if the pitch difference is negative by an appropriate amount as described above, the variation of the belt life becomes small. Therefore, the reliability of the belt B can be improved.

Furthermore, since the core 13 has the same diameter and the belt pitch line difference PLDB is increased,
The area of the reinforced portion of the belt B at the bottom of the core bodies 13, 13, ... As a result, even if cracks occur at the roots of the tooth portions 12 of the belt B, they do not progress, so that the life of the tooth lacking of the belt B can be extended and the reliability of the transmission A can be improved.

Specifically, for example, the design pitch PP is 1
4mm, design pitch line difference PLDP 1.
Belt pitch PB is 0.07% for 4mm pulley
If it is raised to 14.01 mm and the belt pitch line difference PLDB is raised by 18% to 1.65 mm, the pitch difference when meshed with the 28 ^T pulley is −0.
The pitch difference when meshed with the 046 mm and the 120 ^T pulley is -0.003 mm. At this time, 120
^{Even if} the 80 ^T belt meshes with the ^T pulley, the deviation is 0.2
It is 4mm, and it meshes well with backlash.

(Embodiment 2) FIG. 3 shows a timing belt B'according to an embodiment 2 of the present invention, in which, in addition to the core body 13 in the belt body 11, a reinforcing material 14 'made of a nonwoven fabric such as polyamide fiber is toothed. The portion 12 is located at an intermediate portion in the height direction and is embedded so as to be exposed between the tooth portions 12 and 12. Since the reinforcing material 14 'is made of nonwoven fabric, the rubber of the belt body 11 is impregnated inside. Also in this embodiment, the same operational effect as that of the above-described first embodiment can be obtained.

The inventor has found that the design pitch line difference PLDP is 1.4 mm and the design pitch PP is 14.00.
to 28 ^T -28 ^T pulleys in mm, at the pitch line Difference PLDB is 1.65 mm (18% up), the pitch PB is 14.01mm (0.007% up), the belt width is 15 mm, 12 mm 2 A variety of timing belts (examples of the present invention) were prototyped, and the pitch line difference PLDB was 1.4 mm and the pitch PB was a conventional example.
Produced a timing belt of 14.00 mm. All of these configurations were the same as in Example 2 above, the belt body was made of polyurethane rubber, aramid fiber cord was used for the core, and polyamide fiber nonwoven fabric was used as the reinforcing material. The pitch line difference PLDB was adjusted by changing the compression amount of the reinforcing material (nonwoven fabric).
In order to compare variations in durability, three lots of the present invention example and the conventional example were produced in trial lots. Table 1 shows the measurement results of the pitch line difference PLDB and the pitch PB of each of these belts.

[0036]

[Table 1]

Then, each belt is wound around the above-mentioned pulleys, the belts are run at a load of 15 kgf and at a pulley rotation speed of 1900 rpm, and the durability is compared. The results are shown in FIG. According to FIG. 4, it is confirmed that the durability life of the example of the present invention is about 5 times that of the conventional example, and the variation of the durability life is small.

[0038]

As described above, according to the invention of claim 1 or 2, the pitch line difference of the timing belt is increased by 10 to 20% with respect to the design pitch line difference of the timing pulley, and the pulley design is made. By increasing the belt pitch by 0.02 to 0.15% with respect to the pitch, even if the belt pitch varies, the timing belt life can be significantly improved and the durability life variation can be reduced. Thus, it is possible to obtain a practically excellent effect that the reliability of the timing belt transmission device can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing a main part of a timing belt transmission device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the timing belt in the length direction.

FIG. 3 is a sectional view of a timing belt according to a second embodiment.

FIG. 4 is a durability life characteristic diagram of a belt.

FIG. 5 is a characteristic diagram showing changes in the durable life of the belt with changes in the pitch difference from the pulley.

[Explanation of symbols]

 A ... Transmission device P ... Tooth portion PP ... Pitch LP ... Pitch line PLDP ... Designed pitch line difference B, B '... Belt 11 ... Belt body 12 ... Tooth portion 13 ... Core body 14 ... Reinforcing woven fabric 14' ... Reinforcing material PB ... Pitch LB ... Pitch line PLDB ... Pitch line difference

Claims (2)

[Claims] 1. A timing belt having a tooth portion meshing with an outer peripheral tooth portion of a timing pulley, which is wound around a timing pulley, wherein a pitch line difference is 1 with respect to a design pitch line difference of the pulley.
A timing belt characterized in that the pitch is made 0 to 20% higher and the pitch is made 0.02 to 0.15% larger than the designed pitch of the pulley. 2. A timing belt transmission comprising a timing pulley having teeth on the outer circumference and a timing belt having teeth on the inner circumference that mesh with the teeth of the timing pulley and wound around the timing pulley. , Timing belt pitch line difference is 10% to 20% of pulley design pitch line difference
A timing belt transmission, characterized in that the timing belt pitch is increased by 0.02 to 0.15% with respect to the design pitch of the pulley.