JP2002089631A - Belt for power transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt for power transmission that is most suitable for heavy load transmission by virtue of excellent flexibility and of an improved belt travel life by the prevention of early cracking from a cog trough. SOLUTION: The belt 1 for power transmission has cog portions 11 and 12 in which cog crests 9 and cog troughs 8 alternate with each other in an extended rubber layer 6 and a compressed rubber layer 7, and has a core wire 3 buried in an adhesive rubber layer 2. The following three relations are all satisfied: 0.28<=Z/Y<=0.43, 0.55<=X/Z<=0.80, and (Z-X)<2.5 mm, where X is the height of the cog crests of the extended rubber layer 6 of the belt, Y is the belt thickness, and Z is the distance between the pitch line of the core wire 3 and the top of the cog crests 11 of the extended rubber layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission belt used for a heavy duty transmission belt used as a transmission belt for snowmobiles, scooters and general industries.

[0002]

2. Description of the Related Art Conventionally, in a driving system for a scooter, a buggy, a snowmobile (snowmobile) or a general industrial machine field, a power transmission belt is suspended between a driving pulley and a driven pulley, and the effective diameter of the pulley is changed. A belt-type transmission that shifts the gears is used. The power transmission belt used here has at least one of a compression rubber layer and an extension rubber layer having a cog portion in which cog peaks and cog valleys are alternately arranged, and a core wire is provided inside the adhesive rubber layer. And is known as a low edge cog belt such as a low edge single cog belt or a low edge double cog belt.

[0003] In the above-mentioned low edge cog belt, the demand for longer life has been increasingly severe. In particular, when used for a continuously variable transmission belt that transmits power while changing the diameter of the loop wound around the variable-width pulley in a stepless manner, because of the excessive lateral pressure received from the pulley, Bending resistance, abrasion resistance, heat resistance and the like are required. For this purpose, the shapes and dimensions of the upper cog and the lower cog have been studied.

[0004] Further, as a method of manufacturing the above-mentioned low-edge cog belt, an unvulcanized rubber sheet is placed on a flat-shaped mother die with a goku longer than the belt circumference prepared in advance, and heated and pressed by a press to form a cog shape. A cog pad is prepared. This cog pad is fitted into the concave and convex ridges of the cylindrical mother die mounted on the forming drum, the cut surfaces of the cog pads are butt-joined, and the core wire is wound. The molding was completed by winding from the top and moving to the vulcanization process.

The cog pad is a laminate of one to several plies of reinforcing cloth and an unvulcanized rubber sheet, and has cog peaks and cog valleys alternately at a constant pitch in the length direction.

Conventionally, the cutting of the cog pad has been performed manually by a skilled worker, and the worker has previously counted the number of cogs according to the belt circumference and marked the cog portion to be cut with chalk. Later, one cog peak (top of cog)
Was cut by a cutter, and the other cog peak was similarly cut. The most important thing in this cutting work is to cut the cog peak, which is the top of the cog, straight in the width direction and in a biased manner in the thickness direction, and cut each cut surface of the cut cog pad along the width direction. To join joints in a straight line.

[0007]

However, as described above, the load on the actual machine has increased in recent years, and the lateral pressure on the belt has been greatly increased for the purpose of preventing slip. Therefore, stress concentrates around the center line of the belt. In addition, early breakage of the belt due to peeling of the upper cog and / or peeling of the lower portion of the adhesive rubber layer is a serious problem.

In the cog pad cutting operation, the cog crest, which is the top of the cog pad, is cut straight in the width direction and biased in the thickness direction, and each cut surface of the cut cog pad is cut along the width direction. But when the cog part is cut off from the cog peak, it is difficult to join the two ends of the cog pad in a straight line to join, and a gap occurs at the butted part In some cases, a volume crack occurred due to the occurrence of a spot, and a defect sometimes occurred in the joint of the joint portion. As a result, in the obtained belt, there is a possibility that a crack may be generated from a joint portion due to a load variation or a heat generation phenomenon during the running of the belt.

Therefore, the present invention solves the above-mentioned problems, and is excellent in bending resistance and prevents the generation of early cracks from cog valleys, thereby being suitable for high load transmission in which belt running life is improved. The purpose of the present invention is to provide a power transmission belt.

[0010]

According to a first aspect of the present invention, there is provided a compression rubber layer and an extension rubber layer having a cog portion in which cog peaks and cog valleys are alternately arranged, and a core wire is bonded to an adhesive rubber layer. In the power transmission belt buried inside, the height of the cog peak of the above-mentioned stretch rubber layer is X, the thickness of the belt is Y, and the distance from the core wire pitch line to the top of the cog peak of the stretch rubber layer. To Z
(1) 0.28 ≦ Z / Y ≦ 0.43 (2) 0.55 ≦ X / Z ≦ 0.80 (3) Power transmission satisfying all of (Z−X) <2.5 mm Belt, for bending resistance,
Enables lateral pressure resistance and high load transmission.

According to a second aspect of the present invention, there is provided a power transmission belt in which a joint portion of a rubber layer disposed in a cog portion is present in a region of a cog peak portion, and the joint portion penetrates to a cog valley portion. By preventing this, in addition to the first aspect, it is possible to prevent the adhesive rubber layer from entering the region of the cog valley portion, which is a nucleus of early crack generation, and improve the bending fatigue resistance.

The invention according to claim 3 of the present invention is directed to a power transmission belt in which both sides of the stretched rubber layer are cut in an inverted V shape from the top of the cog hill to the bottom of the cog valley, and the side pressure in the pulley is reduced. The load can be applied to the compressed rubber layer below the core wire, which can delay the peeling or loss of the stretched rubber layer above the core wire.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a partial front view of a power transmission belt according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a partial front view of another power transmission belt according to the present invention, and FIG. It is a partial front view of the conventional power transmission belt.

In the power transmission belt 1 of the present invention, a cord 3 made of a cord of polyester fiber, aramid fiber, glass fiber or the like is embedded in an adhesive rubber layer 2.
Above and below, there is an expanded rubber layer 6 in which a reinforcing cloth 4 and a rubber layer 5 are laminated, and a compressed rubber layer 7 in which a reinforcing cloth 4 and a rubber layer 5 are similarly laminated. The upper cog portion 1 in which cog valley portions 8 and cog ridge portions 9 are alternately arranged along the belt longitudinal direction at a constant pitch on the extension rubber layer 6 and the compression rubber layer 7, respectively.
1, a lower cog portion 12 is provided.

As shown in FIG. 2, both sides of the stretched rubber layer 6 have an inverted V from the top of the cog peak 9 to the bottom of the cog valley 8.
It has a cut surface 10 which is cut into a shape, whereby lateral pressure in the pulley can be applied to the compressed rubber layer 7 below the core wire 3, thereby peeling the stretched rubber layer 6 above the core wire 3. And loss can be delayed.

Further, in the present embodiment, the height of the cog peak portion 9 (the height of the upper cog portion) X, the belt thickness Y, and the cog of the stretch rubber layer 6 from the pitch line P of the core wire 6 in the stretch rubber layer 6. Yamabe 9
The dimensional relationship of the distance (pitch height) Z to the top of the hologram becomes important. That is, since X, Y, and Z satisfy all of the following three relational expressions, bending resistance, lateral pressure resistance, and high load transmission can be achieved. (1) 0.28 ≦ Z / Y ≦ 0.43 (2) 0.55 ≦ X / Z ≦ 0.80 (3) (Z−X) <2.5 mm

First, 0.28 ≦ Z / Y ≦ 0.43 indicates the ratio of the pitch height to the belt thickness. If it is less than 0.28, the height of the stretched rubber layer 6 becomes small. When the effect of the double cog belt is thin and the flexibility of the belt is weakened and the bending resistance is lacking, on the other hand, when the height of the stretched rubber layer 6 exceeds 0.43, the tension due to the centrifugal force applied to the belt increases, Peeling between the core wire 3 and the adhesive rubber layer 2 occurs and progresses, and a defect that the upper cog portion 11 is lost occurs.

0.55 ≦ X / Z ≦ 0.80 indicates the ratio of the height of the upper cog portion to the pitch height. If it is less than 0.55, the height of the upper cog portion 11 becomes small. The effect as a double cog belt is thin, and the flexibility of the belt is weakened and the bending resistance is lacking. On the other hand, when it exceeds 0.80, when the height of the upper cog portion 11 becomes large, the upper cog portion 11 keeps the side pressure property. It is necessary to increase the pitch width, but if the pitch width is large, the cog valley 8 bends only at the deepest part, so that peeling or cracking occurs at the corner, and the upper cog 11 is damaged. Leads to.

(ZX) <2.5 mm corresponds to the upper cog portion 11
Is the interval between the deepest part of the cog valley 8 at the height 11 and the pitch line P of the core wire 3 and affects the flexibility of the belt. If it is 2.5 mm or more, the flexibility of the belt decreases. Lack of bending resistance and cannot be used for high-load speed change belts.

Further, in the lower cog portion 12 shown in FIG. 1, the joint portion 14 exists in the area a of the cog peak portion 9, and the angle with the core wire is a right angle. Since the joint portion 14 is a vertical surface, the rubber of the adhesive rubber layer 2 easily flows into the joint portion 14, but this flow also occurs only in the cog peak portion 9 and does not penetrate deep. , Does not significantly affect flex fatigue.

In the lower cog portion 12 of the other power transmission belt 1 shown in FIG.
And the angle θ with respect to the core wire 3 is in a bias of 60 to 90 °, preferably 65 to 90 °, so that the rubber of the adhesive rubber layer 2 hardly flows into the joint portion 14 and the crack The number of locations that are likely to occur is reduced and the running life of the belt is improved. That is, the bias joint 14
Plays a role of preventing the adhesive rubber layer 2 from flowing.

On the other hand, as shown in FIG.
Is invaded to the cog valley portion 8 beyond the region a of the cog valley portion 9, the rubber of the adhesive rubber layer 2
As a result, the region b of the cog valley 8 is susceptible to bending fatigue and cracks occur in a short time.

Needless to say, even in the case of the upper cog portion 11, it is necessary to prevent the joint portion 14 from entering the region b of the cog valley portion 8 as in the case of the lower cog portion 12.

The rubbers to be used as the compression rubber layer 6 and the extension rubber layer 7 include natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfanated polyethylene, hydrogenated nitrile rubber, and hydrogenated hydrogen. A rubber material such as a mixed polymer of a nitrile rubber and an unsaturated metal carboxylate alone or a mixture thereof is used.

The compression rubber layer 6 and the extension rubber layer 7 are made of fibers such as aramid fiber, polyamide fiber, polyester fiber, cotton, etc. The length of the fiber varies depending on the type of fiber, but is as short as about 1 to 10 mm. Fiber is used,
For example, about 3 to 5 mm is used for aramid fiber, and about 5 to 10 mm is used for polyamide fiber, polyester fiber, and cotton. When the direction of the short fibers in the rubber layer is 90 ° that is perpendicular to the longitudinal direction of the belt, most of the short fibers are 70 ° to 1 °.
Desirably, the orientation is within a range of 10 °. The above-mentioned short fibers may be included in the adhesive rubber layer 2, but are preferably not included.

The reinforcing cloth 4 is made of cotton, polyester fiber, nylon, or the like, and is woven in plain weave, twill weave, satin weave, or the like.
A wide-angle canvas in which the crossing angle between the warp and the weft is about 90 to 120 ° may be used. After the reinforcement cloth 4 is subjected to the RFL treatment, the rubber composition is subjected to fiction coating to obtain a canvas with rubber.
The RFL solution is obtained by mixing a latex with an initial condensate of resorcinol and formalin, and the latex used herein includes chloroprene, styrene-butadiene-vinylpyridine terpolymer, hydrogenated nitrile, NBR and the like.

FIG. 5 shows an example of a method of manufacturing the power transmission belt 1 (double cog belt), showing a state in which a molded body composed of a compressed rubber layer, a core wire, and an extended rubber layer is formed on a mold. First, a mold 20 having tooth portions 21 and groove portions 22 alternately is prepared. Further, as shown in FIG.
A flat metal in which several reinforcing cloths, an unvulcanized rubber sheet to be a compressed rubber layer and an unvulcanized rubber sheet to be an adhesive rubber layer are laminated, and separately prepared teeth and grooves are alternately arranged. The cog pad 29 having the cog peaks 29 and the cog valleys 28 is finished by applying the pressure on the mold. Of course,
In the present invention, instead of the mold 20 having the tooth portions 22 and the groove portions 23 alternately, it is also possible to use a mold provided with an inner matrix having grooves at predetermined intervals along the circumferential direction.

One cut portion of the cog pad 30 has an angle α of 0 to 40 at the top 31 of the cog peak 28 as shown in FIG.
Then, the cog pad 30 is turned over, and the other cut portion is also cut at the cog peak 29 so as to be inclined in the opposite direction. When the cog pad 30 is made endless, both cut surfaces are in good contact with each other. If the bias angle α exceeds 40 °, there is a danger that the joint portion 14 will enter the cog valley region b.

A mold 20 is mounted on a molding machine (not shown), and a cog pad 30 having a predetermined length is inserted into a mold 2 while a cog peak 28 of a cog pad is fitted into a groove 22 of the mold.
After making a round contact with the cut end and making a cut contact, the core wire 34 is spirally wound. A laminate of one to several sheets of the reinforcing cloth 32 and an unvulcanized rubber sheet 33 of an expanded rubber layer is wound thereon to form a molded body 25.

In the present embodiment, the grooved mold 45 taken out of the molding machine is set on a support table, and a base made of vulcanized rubber having concave portions provided at predetermined intervals along the circumferential direction. A mold (not shown) and a jacket (not shown) are fitted.

As a final step, the molded body 47 is transferred to a vulcanizer and vulcanized by a usual method. After vulcanization, the jacket, the matrix, and then the cylindrical sleeve are added to the grooved mold 4
5, and the sleeve is cut into a predetermined width to finish the double cog belt 1 as shown in FIG.

[0032]

EXAMPLES Hereinafter, the effects of the present invention will be confirmed by more specific experimental examples. Example 1 As a core wire, a 1,100-denier polyethylene terephthalate fiber was twisted in the up-down direction at an upper twist number of 11.4 times / 10 cm and a lower twist number of 21.0 times / 10 cm in a reverse direction to obtain 2 × 3.
And an untreated cord having a total denier of 6,600 was prepared. Next, after pre-dipping the untreated cord with an isocyanate-based adhesive, about 170 to 18
After drying at 0 ° C and immersing in RFL solution,
A stretch heat setting treatment was performed at 0 ° C. to obtain a treated code.

As a reinforcing cloth, a plain woven canvas using a spun cotton yarn was used. After immersing these canvases in the RFL solution,
Heat treated at 50 ° C. for 2 minutes to obtain a treated canvas. afterwards,
The rubber composition was friction-coated on the treated canvas to obtain a canvas with rubber.

For the compression rubber layer and the extension rubber layer, a rubber composition composed of chloroprene rubber containing short fibers of aramid was used, and for the adhesive rubber layer, a rubber composition composed of chloroprene rubber containing no short fibers was used.

The cog pad is formed by laminating one reinforcing cloth, an unvulcanized rubber sheet of a compressed rubber layer and an unvulcanized rubber sheet of an adhesive rubber layer, and is set in a flat mold in which teeth and grooves are alternately arranged. Then, by pressing at 80 ° C., a cog portion was formed into a cog pad having a mold. Both ends of the cog pad were cut vertically from the top of the cog peak.

After preparing these materials, a cog pad was wrapped around the inner matrix mounted on a flat mold, and a core, a flat stretched rubber layer, and a reinforcing cloth were sequentially wrapped to form a molded body. Subsequently, after the mold was set at a predetermined position on the support base, a vulcanized rubber matrix having concave portions provided at predetermined intervals along the circumferential direction was inserted. Thereafter, the jacket was covered, the mold was placed in a vulcanizing can, and vulcanized to obtain a belt sleeve. This sleeve was cut into a V shape by a cutter to complete a low edge double cog belt for snowmobiles.

The upper cog portion height X, belt thickness Y, and pitch height Z of the obtained five types of low edge double cog belts are as shown in Table 1.

Further, the joint portion of the cog peak portion of each belt was present in the region of the cog peak portion, was perpendicular to the core wire, and the rubber of the adhesive rubber layer had entered the joint portion.

Each of the belts was suspended on a vertical running tester comprising a driving pulley having a diameter of 120 mm and a driven pulley having a diameter of 120 mm, and a tension pulley having a diameter of 50 mm was brought into contact with the rear surface to maintain the bending angle of the belt at 160 °. Then, a load of 150 kgf was applied to the driven pulley, and the driving pulley was rotated at 3600 rpm to confirm the running life of the belt. The results are also shown in Table 1.

Embodiment 5 In this embodiment, a cog pad having one end cut at a bias angle of about 50 ° from the top of the cog crest and the other end cut at a bias angle of about 50 ° is used. It was manufactured in the same manner as described above. The obtained upper cog portion height X, belt thickness Y, and pitch height Z of the obtained low-edge double cog belt are the same as those in Example 1, and one end of the joint portion extends beyond the cog peak region and the cog valley portion. And the flow of the adhesive rubber layer into the joint was observed. Table 1 shows the results of the running test of the belt.

[0041]

[Table 1]

As a result, 0.28 ≦ Z / Y ≦ 0.43,
0.55 ≦ X / Z ≦ 0.80, and (Z−X) <2.
The low-edge double cog belt satisfying 5 mm has excellent bending resistance and lateral pressure resistance, enables high load transmission, and has a long running life. In addition, since the joint portion of the rubber layer arranged in the cog portion is present in the region of the cog peak portion, the joint portion is prevented from penetrating to the cog valley portion, and the cog valley portion which becomes a nucleus of early crack generation. Thus, it was possible to prevent the adhesive rubber layer from penetrating into the region of No. 3 and improve the bending fatigue resistance.

[0043]

As described above, according to the invention described in the present application, the height of the cog ridge of the stretched rubber layer is X, the thickness of the belt is Y, and the cog ridge of the stretched rubber layer from the pitch line of the core wire. When the distance to the top of the part is Z, 0.28 ≦ Z / Y
≦ 0.43, 0.55 ≦ X / Z ≦ 0.80, (Z−X)
<2.5mm in power transmission belt that satisfies all requirements. Enables bending resistance, lateral pressure resistance, and high load transmission. Prevents joints from penetrating to the cog valleys, resulting in early cracking. This has the effect of preventing the adhesive rubber layer from invading the region of the cog valley, which is the nucleus of, and has the effect of maintaining the bending fatigue resistance.

Furthermore, by cutting both sides of the stretched rubber layer in an inverted V shape from the top of the cog peak to the bottom of the cog valley, the side pressure in the pulley is applied to the compression rubber layer below the core wire. This has the effect of delaying the exfoliation or loss of the stretched rubber layer above the cord.

[Brief description of the drawings]

FIG. 1 is a partial front view of a power transmission belt according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a partial front view of another power transmission belt according to the present invention.

FIG. 4 is a partial front view of a conventional power transmission belt.

FIG. 5 is a diagram showing a state in which a molded body of the power transmission belt according to the present invention is formed on a mold.

FIG. 6 is a perspective view of a cog pad used by the power transmission belt according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power transmission belt 2 Adhesive rubber layer 3 Core wire 4 Reinforcement cloth 5 Rubber layer 6 Extension rubber layer 7 Compressed rubber layer 8 Cog valley 9 Cog peak 10 Cut surface 11 Upper cog 12 Lower cog 14 Joint

Claims (3)

[Claims] 1. A power transmission belt comprising a compression rubber layer and an extension rubber layer having cog portions in which cog peak portions and cog valley portions are alternately arranged, and a core wire embedded in an adhesive rubber layer. When the height of the cog peak of the layer is X, the thickness of the belt is Y, and the interval from the core wire pitch line to the top of the cog peak of the stretched rubber layer is Z, (1) 0.28 ≦ Z / Y ≦ 0.43 (2) 0.55 ≦ X / Y ≦ 0.80 (3) (Z−X) <2.5 mm 2. The power transmission belt according to claim 1, wherein the joint portion of the rubber layer disposed on the cog portion is present in the region of the cog peak portion. 3. The stretch rubber layer is cut in an inverted V shape from the top of the cog peak to the bottom of the cog valley on both sides of the stretched rubber layer.
Or the power transmission belt according to 2.