JP2010196888A - Power transmitting belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmitting belt surely securing side pressure resistance of the belt, deformed little even when a side pressure is applied from a pulley, and suppressing failure such as cutting of the belt caused by cracks without degrading flexibility. <P>SOLUTION: In the power transmitting belt having an expansion rubber layer 3 and a compression rubber layer 5, and a spiral core wire 2 buried between the rubber layers, and having a V-shaped side surface, the compression rubber layer 5 includes at least an upper layer 5a near the core wire and a lower layer 5b on a belt inner peripheral surface side, and hardness of the upper layer 5a is set higher than the lower layer 5b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power transmission belt which is a V-belt used in snowmobiles, scooters, buggy cars, and general industrial transmission belts, and more specifically, while maintaining the high lateral pressure resistance required for the above-mentioned applications. The present invention also relates to a power transmission belt in which the belt thickness is reduced to improve bending fatigue resistance.

  2. Description of the Related Art Conventionally, in a drive system in the mechanical field for scooters or general industries, a belt-type transmission that suspends a power transmission belt between a drive pulley and a driven pulley and changes the effective diameter of the pulley is used. . The power transmission belt used here does not have a cog part, or has a cog part in which a cog crest part and a cog valley part are alternately arranged in the compression rubber layer among the compression rubber layer and the stretch rubber layer, Examples include a configuration in which a core wire is embedded in an adhesive rubber layer, and is commercialized as a low edge belt such as a low edge belt, a low edge single cogged belt, or a low edge double cogged belt.

  In these belts, especially in applications such as buggy cars and snowmobiles, rapid acceleration and deceleration are often repeated, and it can be said that there are many situations where high torque is applied at low speed. Therefore, since a high load is applied to the belt that transmits the belt, a high side pressure resistance is required.

  In order to give the belt high side pressure resistance, a device has been devised in which short fibers made of polyamide fiber or aramid fiber are oriented and embedded in the belt width direction in the rubber. By blending the short fiber, the side pressure resistance of the rubber is improved, but the bending resistance is lowered. In particular, when used with a small-diameter pulley, it is repeatedly bent under fairly severe conditions, which leads to bending fatigue and cracking.

  Patent Document 1 discloses a belt in which the flexibility of the belt is improved by using a cover canvas disposed on the upper and lower surfaces of the belt that does not inhibit the bending of the belt. Cover canvas is used as a cover canvas with stretchable upper surface partly made of woolen processed yarn, and a cover canvas made of non-woven fabric or non-woven paper is laminated on the lower surface. By making it easier to bend out, the flexibility is improved and the occurrence of slip during running is suppressed without hindering the bending of the belt, thereby reducing problems such as cracking and cutting.

  In Patent Document 2, a bottom rubber layer (compression rubber layer) in a cogged V belt is composed of two layers, a first bottom rubber layer on the belt back side and a second bottom rubber layer on the belt inner surface side. A belt in which the elastic modulus of the second bottom rubber layer is set larger than 1 is disclosed. In Cited Document 2, even if the first bottom rubber layer having a relatively low elastic modulus gives the belt sufficient flexibility and the first bottom rubber layer having a high elastic modulus is arranged to receive a side pressure from the pulley. By suppressing the deformation in the belt width direction and reducing the movement of each cog in the belt length direction, the occurrence of cracks in each cog is prevented.

JP-A-8-303529 JP 2000-18338 A

  In the belt of Patent Document 1, it is possible to prevent the cover canvas from obstructing the flexibility of the belt, but if the flexibility of the rubber constituting the main body is not improved, the flexibility of the belt is drastically improved. It will not occur, and cracks in the cogs will also occur.

  Further, in Patent Document 2, although it has flexibility and can suppress deformation in the width direction of the cog due to side pressure from the pulley, the belt is bent because the elastic modulus of the rubber forming the inner peripheral surface of the belt is high. The occurrence of cracks on the inner circumferential surface of the belt due to this is apt to occur.

  Therefore, in the present invention, the belt has excellent bendability and can be used with a small-diameter pulley, and even when it is repeatedly bent, the belt surface is not cracked, and failure such as cutting of the belt can be prevented. The issue is to provide a belt that does not easily occur.

  In order to achieve the above object, in claim 1 of the present invention, at least a stretch rubber layer and a compression rubber layer are provided, and a side surface in which a spiral core wire is embedded between these rubber layers has a V shape. In the power transmission presented, the compressed rubber layer is composed of at least two layers of an upper layer close to the core and a lower layer on the belt inner peripheral surface side, and the upper layer has a higher hardness than the lower layer. .

  The power transmission belt according to claim 1, wherein the hardness of the upper layer is in the range of 93 to 99 and the hardness of the lower layer is in the range of 93 to 99.

  According to claim 1, the compression rubber layer is composed of at least two layers of an upper layer and a lower layer, the upper layer has a higher hardness than the lower layer, and the lower layer has a low hardness so that the hardness is high. The upper layer can improve the deformation resistance of the belt, but it has excellent bending fatigue resistance due to the low hardness rubber placed in the lower layer of the belt, which undergoes the greatest stress when the belt is bent. Cracks are also unlikely to occur, and when subjected to side pressure from the pulley, the belt can withstand the side pressure to reduce deformation and reduce the occurrence of cracks.

  In claim 2, the hardness ranges of the upper layer and the lower layer in the compressed rubber layer are limited to predetermined ranges, respectively, and the deformation resistance and the bending fatigue resistance in claim 1 can be made higher.

  Although the ratio of the thickness to the upper width of the belt is limited to a predetermined range, the thickness of the belt is reduced by increasing the hardness of the upper layer of the compression rubber layer and reinforcing the deformation resistance as in the present invention. It is possible to increase the bending fatigue resistance by setting the hardness of the lower layer low, but by reducing the thickness of the belt, the deformation at the time of bending can be reduced and the occurrence of cracks and the like can be further suppressed. .

  FIG. 1 shows a power transmission belt which is a cogged V-belt according to the present invention. In FIG. 1, a power transmission belt 1 includes an adhesive rubber layer 3 in which a core wire 2 is embedded, and an extension rubber layer 4 in which a cover canvas is laminated on the upper part thereof. Layer 5 is laminated.

  Examples of the rubber used for the adhesive rubber layer 3 and the stretch rubber layer 4 include natural rubber, styrene-butadiene rubber, chloroprene rubber, alkylated chlorosulfonated polyethylene, nitrile rubber, hydrogenated nitrile rubber, hydrogenated nitrile rubber, and unsaturated carboxylic acid. It consists of a single known rubber material such as a polymer mixed with a metal salt or a suitable blend thereof.

  On the surface of the stretch rubber layer 4 and the compression rubber layer 5, a stretch canvas 6 with rubber made by weaving a bias canvas, a wide angle canvas, or a woolen nylon warp and a normal weft is laminated. The material may be a wide-angle canvas made of polyester fiber, nylon fiber, aramid fiber, etc., woven in plain weave, twill weave, satin weave, etc., and the crossing angle between warp and weft is about 90-120 °. The above-mentioned canvas is subjected to RFL treatment, and then the rubber composition is friction-coached to obtain a canvas with rubber. The RFL liquid is obtained by mixing an initial condensate of resorcin and formalin into a latex. Examples of the latex used here include chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile, NBR, and the like.

  The compressed rubber layer 5 has cogs 7 having a constant pitch on the lower surface. In addition, a horizontal suede canvas or the like may be embedded in the compressed rubber layer 5 with a waveform along the shape of the cog portion (not shown) for reinforcing the rigidity in the belt width direction. In the present invention, this horizontal suede canvas is not essential and may not be arranged.

  Further, the compressed rubber layer 5 may contain short fibers for reinforcement. Para-aramid fibers (trade names: Twaron, Kevlar, Technora) alone, or para-aramid fibers and nylon, polyester, vinylon, Short fibers such as cotton and meta-aramid fibers (trade name: Conex) are mixed and oriented in the belt width direction. These short fibers are mixed together with the above-mentioned horizontal suede canvas while maintaining the orientation in the width direction of the belt, thereby increasing the rigidity in the width direction of the belt and improving the abrasion resistance of the side surface of the belt.

  The addition amount of this short fiber is 5-40 mass parts with respect to 100 mass parts of rubber | gum, Preferably it is 8-15 mass parts.

  Short fibers protrude from the side of the compressed rubber layer 5, and the protruding fibers reduce the frictional force between the belt and the pulley to prevent rubber sticking and wear and reduce the sound produced by belt slip. Can do.

  Further, a core wire 2 is embedded in the adhesive rubber layer 3, and an aramid fiber is used as the core wire 2, but poly-p or m-benzamide, poly-p-phenylene terephthalamide, poly-m. Mention may be made of phenylene isophthalamide fibers.

  In order to embed the core wire 2 in rubber and use it as a belt tension body, the core wire and the rubber must be firmly bonded. The core wire is formed by twisting a plurality of filaments, and the plurality of filaments must be bundled. For those reasons, the rope used as the core wire is subjected to an adhesive treatment. Examples of the adhesion treatment include treatment with an RFL solution, treatment with a rubber paste, treatment with an isocyanate compound, an epoxy compound, and the like.

  In the present invention, the compressed rubber layer 5 is divided into an upper layer 5a on the side close to the belt back surface and a lower layer 5b on the belt inner peripheral surface side. The upper layer 5a is made of a material having a high elastic modulus, and the lower layer 5b is an upper layer. It is characterized by comprising a material having a lower elastic modulus than 5a. The upper layer 5a has a hardness in the range of 93 to 99, and the lower layer preferably has a hardness in the range of 80 to 88.

  If the hardness of the upper layer 5a is less than 93, the belt has little reinforcing effect and cannot sufficiently withstand the side pressure from the pulley. It can also be shortened. If the elastic modulus exceeds 99, the flexibility of the belt will be hindered, and the belt will not be able to sufficiently follow the curved surface of the pulley, resulting in reduced transmission efficiency or inferior flexibility. There is a problem that occurs and disconnects.

  If the hardness of the lower layer 5b is less than 80, the flexibility is improved, but the strength is insufficient. This is not preferable, and if the hardness exceeds 88, the flexibility is insufficient and the belt is repeatedly bent during running of the belt. This is not preferable because cracks will occur.

  As the material having a hardness in the range of 93 to 99 that can be used as the upper layer 5a, a single material such as a hydrogenated nitrile rubber, a mixed polymer of a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt, as well as polyurethane is used. Among them, it is preferable to use hard urethane because it is difficult to stretch and transmission loss is reduced. The material that can be used as the lower layer 5b is the same as that of the stretch rubber layer and the adhesive rubber layer, and is natural rubber, styrene-butadiene rubber, chloroprene rubber, alkylated chlorosulfonated polyethylene, nitrile rubber, hydrogenated nitrile rubber, hydrogen Examples thereof include a single known rubber material such as a mixed polymer of a nitrile rubber and an unsaturated carboxylic acid metal salt, or a suitable blend thereof.

  In the above description, the example of the cogged V belt has been described, but examples of the belt to which the present invention can be applied include a low edge belt having no cogs other than the cogged V belt.

  The present invention is applied to a transmission belt used for a transmission belt or the like, in which the lateral pressure resistance of the belt is sufficiently ensured, the flexibility is not impaired, and the occurrence of cracks or the like is suppressed.

It is a cross-sectional perspective view of the cogged V belt which is 1 aspect of this invention. It is a cross-sectional perspective view of the low edge belt which is another example of this invention.

DESCRIPTION OF SYMBOLS 1 Power transmission belt 2 Core wire 3 Adhesive rubber layer 4 Stretch rubber layer 5 Compression rubber layer 5a Upper layer 5b Lower layer 6 Stretch canvas 7 Cog

Claims (3)

  In the case of power transmission having at least a stretch rubber layer and a compression rubber layer, and a side surface in which a spiral core wire is embedded between these rubber layers has a V shape, the compression rubber layer is at least an upper layer close to the core wire And a belt for power transmission, characterized in that the upper layer hardness is set higher than that of the lower layer.   The power transmission belt according to claim 1, wherein the hardness of the upper layer is in the range of 93 to 99, and the elastic modulus of the lower layer is in the range of 80 to 88.   The transmission belt according to claim 1, wherein the belt thickness T is in a range of 0.3 W ≦ T ≦ 0.6 W, where W is the upper width of the belt and T is the thickness of the belt.

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