JPH04331844A - Timing belt and belt transmission device - Google Patents

Abstract

PURPOSE:To prolong the tooth cut life of a belt by setting the pitch difference of a timing belt for the designed pitch difference of a timing pulley and the belt pitch for the set pitch of the pulley to each specific rate. CONSTITUTION:As for the pulley P of a transmission device A, a plurality of tooth parts 2 are formed in a certain set pitch PP on the outer periphery of a pulley body 1, and the height from each top edge to a pitch line LP is set equal to a designed pitch line difference PLDP. While, as for a belt B, a number of tooth parts 12 are formed in a certain pitch PB on the bottom part of a belt body 11. In this case, the pitch line difference PLDB as the height from the pitch line PB of the center of the center body 13 of the belt body 11 to the surface of a woven fabric between each tooth part 12 is set larger by 10-20% than the set difference PLDP. Further, the pitch PB is set larger by 0.02-0.15% than the designed pitch PP.

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 device combining the same with a timing pulley.

0002

[Prior Art] In a timing belt, in order to accurately mesh with a timing pulley of any number of teeth, the pitch of the belt (pitch between teeth; hereinafter the same) is adjusted to the designed pitch of the pulley, and the pitch line of the belt is adjusted. The difference is precisely matched to the design pitch line difference of the pulley.

On the other hand, research and experiments conducted to date have revealed that the life of the belt without tooth loss is longest when the pitch difference between the belt and the pulley is slightly negative. When a load torque is applied to the belt, the belt is stretched and the belt pitch increases near the belt tension side where the belt teeth bear the largest tooth load. As a result, the belt pitch and the pulley pitch deviate, making it impossible to distribute the load equally to each tooth, and an excessive tooth load is applied to one tooth.

[0004] Therefore, if the belt pitch is made smaller in advance by taking into consideration that the belt will be stretched, when a load torque is applied to the belt, the belt pitch near the belt tension side will be reduced to a pulley pitch. At the same time, the load can be shared approximately equally, thereby increasing the tooth chipping life of the belt.

However, in a pulley with a small number of teeth,
If the belt pitch is shortened to make the pitch difference negative, for combinations of the belt and pulleys with other numbers of teeth that have a large number of meshing teeth, the pitch difference will accumulate between the number of meshing teeth and the belt teeth and pulley teeth will be reduced. The parts do not mesh together.

That is, as a specific example, for two types of timing belts with a standard pitch of 14 mm and belt widths of 15 mm and 12 mm, the pitch difference of the tooth portion with respect to the pulley (number of pulley teeth 28T - 28T O ) is changed. Figure 5 shows the changes in the tooth chipping durability life of the belt at that time. Note that the failure mode is all due to shearing of the teeth. In order to eliminate other factors that affect the durability life, the variation of the pitch difference is done by changing the outer diameter of the pulley. As shown in the figure, the durable life of the belt reaches its maximum when the pitch difference between the belt and the pulley is around -0.05 mm, which is approximately three times longer than when the pitch difference is 0. Furthermore, when the pitch difference is around 0, the slope of the line indicating the life characteristics is large, so if the pitch difference changes by, for example, 0.01 mm, the durability life changes by about 30%, but when the pitch difference is around -0.05 mm, There is only a change of about 5%. In this way, by making the belt pitch difference negative for pulleys with a small number of teeth,
It is possible to improve the durability life of the belt and reduce its variation.

[0007]

However, in order to set the pitch difference to -0.05 mm, the pitch of the belt must be set to 13.
If you set it to 95mm, for example, 80T to a 120T pulley.
If a belt with teeth of
0), and the teeth of the belt no longer mesh with the pulley. Therefore, it is common practice to match the pitch and pitch line difference of the belt and pulley at the expense of reducing tooth chipping life.

Furthermore, in the timing belt, the core is reinforced with fabric along the tooth surface from the bottom. Reinforcement with woven fabric is essential for improving tooth chipping life. At this time, since the belt pitch line is located approximately at the center of the core, the pitch line difference is determined by the diameter of the core and the thickness of the woven fabric when compressed. However, the thickness of the woven fabric when compressed varies widely due to the thickness of the woven fabric itself and variations in compression rate due to core winding tension. Therefore, in belts reinforced with woven fabric, there is considerable variation in pitch line difference, and this variation in pitch line difference causes variation in pitch difference between pulleys.

[0009] As mentioned above, a change in the pitch difference greatly changes the tooth loss life of the belt, so it is inevitable that a timing belt reinforced with conventional woven fabric will have a wide variation in life. However, the reliability of the transmission was insufficient.

The purpose of the present invention is to solve the above-mentioned problems all at once, to extend the life of a timing belt reinforced with woven fabric, and to improve the reliability of a belt transmission device. It is in.

[0011]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, the pitch line difference and the pitch of the timing belt are made to differ from each other by a predetermined amount in advance with respect to the pulley.

Specifically, in the invention of claim 1, the timing belt has teeth on the inner circumference that mesh with the outer circumferential teeth of the timing pulley and is wound around the timing pulley, and the pitch line difference is adapted to the design of the pulley. 10 to 20% higher than the pitch line difference, and the pitch is 0.02 to 0.15 higher than the pulley design pitch.
It is characterized by increasing the percentage.

[0013] According to the second aspect of the invention, there is provided a timing belt comprising a timing pulley having teeth on the outer periphery and a timing belt having teeth on the inner periphery that mesh with the teeth of the timing pulley and being wound around the timing pulley. As a transmission device, the pitch line difference of the timing belt is made 10 to 20% higher than the designed pitch line difference of the pulley, and the pitch of the timing belt is made larger than the designed pitch of the pulley by 0.02 to 0.15%. It is characterized by what it did.

[0014]

[Operation] With the above configuration, in the invention according to claim 1 or 2, the pitch line difference of the belt is 10 to 20% higher than the designed pitch line difference of the pulley.
And the belt pitch is 0.0 with respect to the pulley design pitch.
Since it is 2 to 0.15% larger, when meshing with a pulley with a small number of teeth, the belt pitch is 0.2% larger than the pulley pitch.
When the belt is short by ~0.5% and meshes with a pulley having a large number of teeth, the belt pitch and pulley pitch substantially match. To give 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 (0.02% increase) and the belt pitch line difference is 1.54 mm ( 10% increase). In this case, when wrapped around a 28T pulley, the pitch difference is -0.028 mm (0.2% shorter), and 120
T When wrapped around the pulley, the pitch difference is -0.00
4mm (0.003% shorter).

[0015] Also, for a pulley with a design pitch of 8.00 mm and a pitch line difference of 0.686 mm, the belt pitch is 8.012 mm (0.15% increase).
, belt pitch line difference is 0.823mm
If a timing belt (20% increase) is wound around an 18T pulley, the pitch difference will be -0.036mm (0.45% shorter), and 1
When wrapped around the 56T pulley, the pitch difference is -0.
006 mm (0.08% shorter).

[0016] In this way, the pitch difference is negative with respect to the small pulley, and there is sufficient meshing with the large pulley.

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

Furthermore, even if there is a large variation in the pitch line difference and 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 belt life will be reduced. reliability increases.

Furthermore, since the belt pitch line difference is increased while the diameter of the core is the same, the area of the reinforced portion of the belt below the core increases. As a result, even if a crack occurs at the tooth base of the belt tooth portion, the crack is prevented from progressing, and the life of the belt with missing teeth can be extended.

[0020] At this time, unless the pitch line difference of the belt is made at least 10% larger than the designed pitch line difference of the pulley, the pitch difference will not be so negative even with a small pulley, so it is difficult to improve durability. The effect is small. Conversely, if the pitch line difference of the belt becomes larger than 20% of the designed pitch line difference of the pulleys, the pitch difference between the small pulleys becomes too negative, causing problems with wear during long-term belt running. . From this, the pitch line difference of the belt is increased by 10 to 20% relative to the designed pitch line difference of the pulley.

Furthermore, in order to make the pitch difference between the large pulleys close to 0, the pitch of the belt is set approximately 0.02 to 0.15% larger than the designed pitch of the pulleys.

[0022]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

(Embodiment 1) FIG. 1 shows a timing belt transmission device A according to Embodiment 1 of the present invention.
is composed of a timing pulley P and a timing belt B wrapped around the outer circumference of the timing pulley P. The timing pulley P has a plurality of teeth 2, 2, . . . on the outer periphery of the pulley main body 1.
The teeth 2, 2, . . . are formed at a constant pitch PP, and the height from the tip of each tooth to the pitch line LP is a pitch line difference PLDP.

On the other hand, as shown in enlarged detail in FIG. 2, the timing belt B includes a belt main body 11, and a large number of teeth 12, 12, .
By meshing the teeth 12, 12, ... with the teeth 2, 2, ... on the outer periphery of the timing pulley P, rotational power is transmitted synchronously with the pulley P. That's what I do. 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 from a known rubber compound suitable for the intended use of the belt B. be done.

Inside the belt main body 11, a plurality of endless core members 13, 13, ... (reinforcing members) are arranged in parallel at regular intervals in the belt width direction, and each inclined with respect to the belt length direction. It is buried in a spiral pattern. Each of these bodies 13
is arranged so as to be exposed from the bottom surface of the belt body 11 at the bottom surface between the teeth 12, 12, and is made of, for example, aramid fiber (aromatic polyamide fiber), polyarylate fiber, etc.
Consists of high strength and high modulus fibers.

Further, a reinforcing fabric 14 is provided from the surface (tooth surface) of each tooth portion 12 of the belt body 11 to the lower surface of the core body 13.
is covered. This reinforcing fabric 14 is made of 6 nylon, 6
Using yarns or blended yarns made of nylon 6, nylon 46, aromatic polyester, tetron, cotton, rayon, Teflon, etc., either singly or in combination, satisfies the abrasion resistance and friction coefficient required for reinforcing woven fabrics for belts. It is woven like this.

[0027] In the belt B, the above-mentioned core body 1
The pitch line difference PLDB, which is the height from the pitch line LB at the center of 3 to the surface of the woven fabric 14 at the bottom of the groove between the teeth 12, 12, is 10 to 20% larger than the designed pitch line difference PLDP of the pulley P. is set (PLDB = 1.1~1.2PLDP
), and the pitch PB of the teeth 12, 12, ... is 0.02 to 0 less than the design pitch PP of the teeth 2, 2, ... of the pulley P.
．． It is increased in the range of 15% (PB = 1.00
02~1.0015PP).

When the increase in the pitch line difference PLDB of the belt B with respect to the designed pitch line difference PLDP of the pulley P is less than 10%, even if the pulley P is small, the pitch difference will not be so negative, and durability will be improved. On the other hand, if it exceeds 20%, the pitch difference in the small pulleys will become too negative, causing problems with wear when belt B runs for a long period of time, so it is recommended to increase it by 10 to 20%. is necessary.

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

Therefore, in this embodiment, the pitch line difference PLDB of the belt B is 10 to 10 with respect to the designed pitch line difference PLDP of the pulley P.
20% higher, and the pitch PB of the belt B is 0.02 to 0.15% larger than the design pitch PP of the pulley P, so when it meshes with the pulley P with a small number of teeth, the belt pitch PB is 0.0 compared to the pulley pitch PP. .2-0.5
When it meshes with a pulley P that is % short and has a large number of teeth, the belt pitch PB and the pulley pitch PP substantially match, and the pitch difference is negative for the small pulley P, and it also meshes well with the large pulley P. Therefore, the fatigue of the belt B can be reduced by making the pitch difference at the small pulley P negative.
The belt life in timing belt transmission can be extended.

Furthermore, even if there is a large 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 in belt life will be reduced. Therefore, the reliability of belt B can be improved.

Furthermore, since the diameter of the core body 13 is the same and the belt pitch line difference PLDB is increased,
The area of the lower reinforcing portions of the core bodies 13, 13, . . . in the belt B increases. As a result, even if cracks occur at the root of each tooth portion 12 of the belt B, the cracks do not develop, thereby extending the life of the belt B with missing teeth and increasing the reliability of the transmission device A.

Specifically, for example, if the design pitch PP is 14 mm and the design pitch line difference PLDP
For a pulley whose diameter is 1.4 mm, the belt pitch PB is increased by 0.07% to 14.01 mm, and the belt pitch line difference PLDB is increased by 18% to 1.6.
In the case of 5 mm, the pitch difference when meshing with a 28T pulley is -0.046 mm, and the pitch difference when meshing with a 120T pulley is -0.003 mm. At this time, even when the 80T belt meshes with the 120T pulley, the deviation is 0.24 mm, and the backlash ensures sufficient meshing.

(Embodiment 2) FIG. 3 shows a timing belt B' according to Embodiment 2 of the present invention, in which, in addition to the core body 13, a reinforcing material 14' made of a nonwoven fabric such as polyamide fiber is provided inside the belt body 11. It is located in the middle part in the height direction in the part 12, and is buried so as to be exposed between the tooth parts 12, 12. Since the reinforcing material 14' is made of non-woven fabric, the rubber of the belt body 11 is impregnated into the reinforcing material 14'. This embodiment also provides the same effects as those of the first embodiment.

The inventor has determined that the design pitch line difference PLDP is 1.4 mm and the design pitch PP is 14 mm.
．． 00mm 28T -28T pulley, pitch line difference PLDB is 1.65mm (1
8% increase), pitch PB was 14.01mm (0.0
07% up), and the belt width is 15mm and 12mm.
In addition to prototyping different types of timing belts (example of the present invention), pitch line difference PLDB was used as a conventional example.
A timing belt with a pitch of 1.4 mm and a pitch PB of 14.00 mm was manufactured. These structures were all the same as in Example 2, and the belt body was made of polyurethane rubber, an aramid fiber cord was used as the core, and a polyamide fiber nonwoven fabric was used as the reinforcing material. The pitch line difference PLDB was adjusted by changing the amount of compression of the reinforcing material (nonwoven fabric). In order to compare the variation in durability, three lots of prototypes ① to ① were produced for both the inventive example and the conventional example. Pitch line difference PLDB of each of these belts
Table 1 shows the measurement results for pitch and pitch PB.

[0036]

[Table 1]

[0037] Each belt was wound around the specified pulley as described above, and the belt was run under a load of 15 kgf and at a pulley rotation speed of 1900 rpm to compare the durability. The results are shown in Fig. 4. According to this figure 4,
The durability life of the example of the present invention was approximately five times that of the conventional example, and it was confirmed that the variation in durability life was also small.

[0038]

As explained above, according to the invention of claim 1 or 2, the pitch line difference of the timing belt is made 10 to 20% higher than the designed pitch line difference of the timing pulley, and the design of the pulley is improved. By making the belt pitch 0.02 to 0.15% larger than the pitch, even if the belt pitch varies, the life of the timing belt can be significantly improved, and the variation in its durability life can be reduced. Therefore, it is possible to obtain a practically excellent effect of increasing the reliability of the timing belt transmission device.

[Brief explanation of drawings]

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

FIG. 2 is a longitudinal sectional view of the timing belt.

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

FIG. 4 is a diagram showing the durability life characteristics of the belt.

FIG. 5 is a characteristic diagram showing changes in the durability life of the belt due to changes in the pitch difference between the belt and the pulley.

[Explanation of symbols]

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

Claims (2)

[Claims] 1. A timing belt that has teeth on its inner periphery that mesh with the outer teeth of the timing pulley, and is wound around the timing pulley, the pitch line difference being 10 to 10 times larger than the designed pitch line difference of the pulley. A timing belt characterized by being 20% higher and having a pitch 0.02 to 0.15% larger than the designed pitch of the pulley. 2. A timing belt transmission device comprising a timing pulley having teeth on its outer periphery, and a timing belt wound around the timing pulley and having teeth on its inner periphery that mesh with the teeth of the timing pulley. , the pitch line difference of the timing belt is 10 to 20% of the designed pitch line difference of the pulley.
A timing belt transmission device characterized in that the pitch of the timing belt is increased by 0.02 to 0.15% relative to the designed pitch of the pulley.