JPH10153239A - Toothed belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothed belt capable of affording the long life without generating cracks on the back surface and adhesion friction, in a toothed belt for an automobile, to be used under high load and high-temperature atmosphere. SOLUTION: In a toothed belt 1 composed of a plurality of tooth parts 2 arranged along the longitudinal direction and a tooth cloth 5 covering the back surface part in which core wires 3 are embedded, the front surfaces of the toothed parts 2, and the front surface of the tooth bottom part, elastomer for constituting the tooth parts 2 and the back surface part is formed into a two- layer structure, the toothed parts 2 and a part positioned on the back surface part and on the upper parts of the tooth parts 2 are formed of elastomer having high hardness, and the other back surface part is formed of elastomer having heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothed belt for an automobile engine driving device, and more particularly, to an OHC driving toothed belt used in a high-temperature atmosphere such as an engine room using an idler pulley and a back tensioner. Related to belts and the like.

[0002]

2. Description of the Related Art In a toothed belt for an automobile engine drive device, generally, a back portion and a tooth portion of the belt are formed of the same elastomer. To drive an automobile engine, a high load is applied to the belt, but to transmit the high load, the teeth must have sufficient rigidity and a high hardness elastomer is required. The back side must maintain sufficient flex crack resistance to repeated bending stress. As described above, since the required physical properties of the belt rear portion and the belt tooth portion are different, rather than forming these with the same elastomer,
It may be advantageous to form them from a different kind of elastomer suitable for each.

[0003] Toothed belts for automobile engine drive devices are often used in a high-temperature atmosphere, but the high-temperature atmosphere causes the rubber to age and cracks easily. The aging is caused by an ozone atmosphere and also in normal air for a long period of time. Therefore, it would be advantageous if a toothed belt having a long service life could be obtained by using an elastomer having high heat resistance in a part that easily ages. In order to satisfy the demand, Japanese Patent Application Laid-Open No. 57-12145 discloses that at least a portion of the belt rear portion closer to the rear side than the tensile member is formed of hydrin rubber having good heat resistance, and other belt rear portions and belt tooth portions are formed. Is made of synthetic rubber NBR or CR or SBR or natural rubber. In addition, there was an example in which the back surface portion used an elastomer in which reinforcing short fibers were contained in a low-hardness elastomer, and the tooth portion contained reinforcing short fibers in a high-hardness elastomer.

[0004]

However, when a heat-resistant elastomer is used for the rear part, the heat-resistant elastomer having a low hardness is also used for the rear part located above the teeth, so that the reverse bending is performed. As a result, the back of the belt contacted the idler pulley, and the back of the upper part of the teeth strongly contacted the pulley. On the other hand, when an elastomer containing reinforcing short fibers in a low-hardness elastomer is used for the back, even if a low-hardness elastomer is used, if the elastomer is exposed to a high-temperature atmosphere in an engine room or the like for a long time, the hardness of the elastomer is reduced. And the short fibers were restricted and the back was cracked due to the nuclei.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a long life without causing cracks and adhesive wear on the back surface of a toothed belt for automobiles used under a high load and a high temperature atmosphere. The object of the present invention is to provide a toothed belt that can obtain the following.

[0006]

That is, a feature of the present invention conforming to the above-mentioned invention is that a plurality of teeth arranged along the length direction, a back surface in which a core wire is embedded, and a surface of a tooth bottom are covered. In the toothed belt made of a tooth cloth, the elastomer constituting the tooth portion and the back portion has a two-layer structure, and the portion of the tooth portion and the back portion located above the tooth portion is formed of a high-hardness elastomer. It is a toothed belt whose back part other than the upper part is formed of a heat-resistant elastomer. In the invention according to claim 1,
Since the elastomer forming the tooth portion and the back portion of the belt has a two-layer structure, and the back portion of the tooth portion and the upper portion of the tooth portion are formed of a high-hardness elastomer, the back portion located above the tooth portion causes adhesive wear. There is nothing. In addition, since the other back surface is formed of a heat-resistant elastomer, even if the back surface is bent by the back idler and the tensioner pulley in a high-temperature atmosphere, the back surface cracks hardly occur.

Further, the present invention is characterized in that the high hardness elastomer and the heat resistant elastomer are made of the same kind of elastomer. By using the high-hardness elastomer and the heat-resistant elastomer as the same type of elastomer, the adhesive strength of the first and second layers is improved, and there is no occurrence of interface delamination between the first and second layers.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a toothed belt 1 according to the present invention.
FIG. 2 is a cross-sectional perspective view showing an example, in which a toothed belt has a plurality of tooth portions 2 and a plurality of core wires 3 arranged along a belt longitudinal direction, and a back portion 4 located above the embedded tooth portion and another back surface. And a tooth cloth 5 covering the tooth surface 8 and the bottom surface.

Here, the tooth portion 2 and the upper rear portion 4 are formed of a high-hardness elastomer, and the other rear portion 6 is formed of a heat-resistant elastomer. Further, it is preferable that a portion of the back surface portion 4 exposed on the back surface is from half the root width of the tooth portion 2 to the same width. Here, when the portion exposed to the back of the back portion 4 is smaller than half the root width of the tooth portion 2, the other back portion 6 made of a low-hardness elastomer comes into strong contact with the back tension. When the back portion 6 is larger than the root width of the tooth portion 2, the portion exposed on the rear surface of the rear portion 4 becomes larger than the root width of the tooth portion 2. Cracks are likely to occur in the back rubber.

The elastomer used for the tooth part 2 and the back part 4 located on the tooth part is hydrogenated nitrile rubber,
Rubbers such as chlorosulfonated polyethylene (CSM), alkylated chlorosulfonated polyethylene (ACSM), and chloroprene rubber are used. Elastomers used as the heat-resistant elastomer for the back part 6 are hydrogenated nitrile rubber, chlorosulfonated polyethylene (C
SM), alkylated chlorosulfonated polyethylene (A
Rubbers having improved heat aging resistance, such as CSM), chloroprene rubber and acrylic rubber, are preferred. The hydrogenated nitrile rubber has a hydrogenation rate of 80% or more, and preferably 90% or more in order to exhibit heat resistance and ozone resistance. A hydrogenated nitrile rubber having a hydrogenation rate of less than 80% has extremely low heat resistance and ozone resistance. In the present invention, it is preferable to use the same type of high hardness elastomer and heat resistant elastomer.

Among the above rubbers, carbon black, zinc white, stearic acid, a softener, a plasticizer, an antioxidant, etc. are added as compounding agents, and sulfur and organic peroxides are used as vulcanizing agents. These compounding agents and vulcanizing agents are not particularly limited.

The core wire 3 is obtained by twisting filaments of 5 to 9 μm of E glass or high-strength glass and treating them with an RFL solution or the like which is a protective agent or an adhesive made of a rubber compound. . Further, as an organic fiber, a filament of 0.5 to 2.5 denier of a para-aramid fiber (trade name: Kevlar, Technora) having a small elongation with respect to stress and a large tensile strength is twisted, and an RFL solution, an epoxy solution A twisted cord treated with an adhesive of an isocyanate solution and a rubber compound is used. However, the present invention is not limited to these. The diameter of the core wire 3 is set in the range of 0.6 to 1.10 mm. If the diameter is less than 0.6 mm, the tensile strength of the core wire 3 is low and the core wire 3 cannot withstand high load transmission. on the other hand,
If it exceeds 1.10 mm, it does not hold due to the belt dimensions.

The canvas used as the tooth cloth 5 is made of 6 nylon, 66 nylon, polyester, aramid fiber or the like, and may be used alone or in combination. Warp (belt width direction) and weft (belt length direction) of tooth cloth 5
Is a filament yarn or a spun yarn of the above-mentioned fiber, and the woven structure may be any of a plain woven fabric, a twill woven fabric, and a satin woven fabric. In addition, it is preferable to partially use elastic wooly nylon or urethane elastic yarn as the weft.

The above-mentioned tooth cloth 5 is treated with an RFL solution, an isocyanate solution or an epoxy solution. RFL
The liquid is prepared by mixing a latex with an initial condensate of resorcinol and formalin, such as styrene butadiene-vinylpyridine terpolymer, hydrogenated nitrile rubber, chlorosulfonated polyethylene, and epichlorohydrin. Is latex.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. Examples 1 and 2 First, a rubber compound of a toothed belt was prepared according to the compounding shown in Table 1, and formed into a sheet.

[0016]

[Table 1]

On the other hand, as the lower cover cloth, a warp yarn composed of five deniers of 40 denier Woolly 6 nylon and a warp yarn composed of 210 denier 6 nylon having a warp density of 84 (lines / 3 cm) and a weft density of 118 (Book / 3cm), total denier number 414 including warp and weft
After weaving with twill woven canvas at 80 denier / 3cm ² , RF
L solution [11.0 parts by weight of resorcinol, formalin (37
%) 8.0 parts by weight, 0.2 parts by weight of caustic soda, terpolymer of styrene / butadiene / vinylpyridine (40%)
%) 84.0 parts by weight, chlorosulfonated polyethylene rubber latex (40%) 56.0 parts by weight, water 121.
5 parts by weight], dried, heat-treated at 200 ° C. for 3 minutes, further immersed in rubber paste (680 parts by weight of methyl ethyl ketone, 20 parts by weight of PAPI in 100 parts by weight of the rubber compound shown in Table 1), and air-dried. Tooth cloth.

Next, three ECG 150 glass fibers are aligned as core wires, immersed in the RFL treatment solution, and air-dried.
Heat-treated at 280 ° C for 1.5 minutes, S direction, Z
In each of the directions, 11 small ropes each obtained as a ply twist at a rate of 12 times / 10 cm are separately prepared in the direction, and the ply twist in the S direction is set in the Z direction, and the set twist is set in the Z direction in the Z direction. Glass cords that were twisted in each direction at a rate of 8 times / 10 cm were used as core wires. Further, as the material of the tooth portion 2 and the back surface portion 4, a rubber compound shown in Table 1 was used as a 1.8 mm sheet.

The tooth cloth was finished into an endless cylindrical body, which was set in a mold. From above, a pair of S, Z twisted glass core wires are alternately 1.3 m at a winding tension of about 10 kg / strand.
Wound spirally at m pitch, 1.8m from above
m, and the mold is inserted into a jacket having a semicircular concave portion shown in FIG. 3 such that the semicircular concave portion of the jacket and the tooth groove portion of the mold match,
Vulcanize and preform. Next, the mold was taken out of the vulcanizing can, and the heat-resistant rubber compound shown in Table 2 was added to the mold at 1.0 mm
The sheet was bonded to the die after the preform, and was again placed in a vulcanizing can for vulcanization.

Next, the vulcanized mold is removed and polished, and high-hardness rubber appears on the back of the belt, and polishing is performed until the exposed portion of the high-hardness rubber on the back of the belt becomes a certain amount or more. Was. Thereafter, this was cut into a predetermined width to prepare individual belts. The obtained belt has a belt tooth shape: Z
A, number of teeth: 88, belt width: 19 mm and 13 mm, tooth pitch: 9.525 mm.

In Example 2, the core wire, the tooth cloth, and the rubber constituting the tooth portion 2 and the back portion 4 are the same, and the other heat-resistant elastomer constituting the back portion 6 is an acrylic rubber compound shown in Table 3. It just changed to.

[0022]

[Table 2]

[0023]

[Table 3]

Comparative Example As Comparative Example 1, a belt was formed using only one layer of the heat-resistant rubber shown in Table 2. For the core wire and the tooth cloth, the same materials as in Examples 1 and 2 are used, vulcanization is carried out by a usual method, a belt is prepared, polished to a predetermined thickness, and then cut to a predetermined width. To make individual belts. As Comparative Example 2, a belt was formed using only one layer of high hardness rubber shown in Table 1. For the core wire and the tooth cloth, the same materials as in Examples 1 and 2 are used, and vulcanization is performed by a usual method to form a belt.
After polishing to a predetermined thickness, each belt was cut by cutting to a predetermined width.

Next, the belt is driven by a driving pulley (16 teeth), a driven pulley (32 teeth), and a back tensioner (diameter φ52).
mm), the condition 1 is that the belt width is 19 mm, the ambient temperature is 120 ° C., the rotational speed of the driving pulley is 7,200 rpm, a load of 3.7 KW is applied to the driven pulley, and the belt initial tension is applied. Was set to 150N.
Next, as condition 2, the belt width is 13 mm, the ambient temperature is 80 ° C., the number of rotations of the driving pulley is 7,200 rpm, a load of 5.1 KW is applied to the driven pulley, and the initial tension of the belt is 150.
N. The belt was run until the end of its life under the conditions 1 and 2, and in the test under the condition 2, the presence or absence of adhesive wear on the back surface of the belt after running was examined. Table 4 shows the results.

[0026]

[Table 4]

From these results, both Examples 1 and 2 have less adhesive wear of the back rubber as compared with Comparative Example 1, and have a longer life under a high-temperature atmosphere than Comparative Example 2.

[0028]

As described above, according to the first aspect of the present invention, the elastomer forming the teeth and the back of the belt has a two-layer structure, and the teeth and the back of the upper part of the teeth are made of a high-hardness elastomer. Due to the formation, the rear portion located above the tooth portion does not cause adhesive wear. In addition, since the other back surface is formed of a heat-resistant elastomer, even if the back surface is bent by the back idler and the tensioner pulley in a high-temperature atmosphere, the back surface cracks hardly occur.

[0029] The invention of claim 2 provides that the high hardness elastomer and the heat resistant elastomer are made of the same kind of elastomer, so that the adhesive strength of the first and second layers is improved, and the first and second layers are improved. Does not cause interfacial delamination.

[Brief description of the drawings]

FIG. 1 is a perspective view of a toothed belt of the present invention.

FIG. 2 is a sectional view showing only an elastomer layer of the toothed belt of the present invention.

FIG. 3 is a perspective view of a jacket for manufacturing the toothed belt of the present invention.

FIG. 4 is a sectional view showing only an elastomer layer of another toothed belt of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Toothed belt 2 Tooth part 3 Core wire 4 Back part 5 Tooth cloth 6 Other back part 9 Jacket 10 Concave part 11 Convex part

Claims (2)

[Claims] 1. A toothed belt comprising a plurality of teeth arranged along the length direction, a back part having a core wire embedded therein, and a tooth cloth covering the tooth surface and the tooth bottom surface. In addition, the elastomer that forms the back surface has a two-layer structure, the upper portion of the tooth portion between the tooth portion and the back portion is formed of a high-hardness elastomer, and the other back portion is formed of a heat-resistant elastomer. Toothed belt. 2. The toothed belt according to claim 1, wherein the high hardness elastomer and the heat resistant elastomer are made of the same kind of elastomer.