JP5215274B2 - Toothed belt - Google Patents

Description

  The present invention relates to a toothed belt that is used in a high load environment, particularly in an internal combustion engine of an automobile, and in which an intermediate canvas is embedded.

  In an internal combustion engine such as an automobile, a toothed belt is widely used to transmit power from a crankshaft to a camshaft. Since a high load is generally applied to a toothed belt used in an internal combustion engine, the life of the toothed belt tends to be relatively short. In particular, when operating at a high rotational speed, the effective tension of the belt increases and the load on the belt becomes higher, so the life of the toothed belt may be significantly reduced.

  Conventionally, in a toothed belt, as disclosed in Patent Document 1, it is known that an intermediate canvas is disposed between a tooth surface and a tensile cord. In such a toothed belt, the intermediate canvas improves the wear resistance at the root portion, and the tooth root portion has high rigidity, so that the occurrence of cracks at the tooth root portion is prevented.

Japanese Patent Publication No. 6-60667

  However, since the toothed belt of Patent Document 1 has high belt tooth rigidity, when it is operated under a high load and a high rotational speed, the effective tension becomes high, and its life cannot be sufficiently improved. In a toothed belt, it is conceivable to soften the tooth rubber in order to lower the effective tension. However, if the tooth rubber is softened, the rigidity of the belt tooth itself is lowered, so that the belt life cannot be sufficiently extended.

  The present invention has been made in view of the above problems, and reduces the effective tension of the belt without softening the belt teeth and improves the durability of the belt used under high load and high rotation. It is an object to provide a toothed belt that can be used.

  In the toothed belt according to the present invention, tooth portions and tooth bottom portions are alternately provided along the longitudinal direction on one surface, a belt main body formed of an elastomer, and embedded in the belt main body, in the belt longitudinal direction. An extending core wire element; and an intermediate canvas embedded in the belt body on the other surface side of the belt body from the core wire element, and the elastic modulus in the belt width direction of the intermediate canvas is 100 GPa or more. It is characterized by that.

  The intermediate canvas is preferably a woven fabric woven by yarns extending in the belt width direction and yarns extending in the belt longitudinal direction. Examples of the yarn extending in the belt width direction include aramid fibers, PBO fibers, and carbon fibers. Including at least one. The yarn extending in the longitudinal direction of the belt is preferably an elastic yarn, and the elastic yarn is, for example, a crimped nylon yarn.

  The intermediate canvas is preferably disposed substantially parallel to the core element. The tooth portion of the belt main body is formed by, for example, a core rubber layer constituting the inside of the tooth portion and a tooth rubber layer disposed along the outer periphery of the tooth portion and laminated on the one surface side of the core rubber layer. The The modulus of the core rubber layer is preferably higher than that of the tooth rubber layer. For example, toothed belts are used in internal combustion engines.

  In the present invention, by embedding the intermediate canvas on the back side of the toothed belt, the effective tension of the belt can be reduced without reducing the rigidity of the tooth portion of the belt, and the durability performance of the belt can be improved.

It is a side view of a toothed belt concerning this embodiment. It is sectional drawing which shows the manufacturing method of a toothed belt typically. It is sectional drawing which shows the manufacturing method of a toothed belt typically. It is a schematic diagram which shows the test method for confirming the torsional rigidity of a belt. It is a graph which shows the test result of torsional rigidity. It is a schematic diagram which shows the layout of the transmission system used by a durability performance test. It is a graph which shows the result of an endurance performance test. It is a graph which shows the result of the maximum effective tension.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a toothed belt according to an embodiment of the present invention. The toothed belt 10 is an endless belt used in, for example, an internal combustion engine of an automobile, and is, for example, a power transmission belt used for transmitting power from a crankshaft to a camshaft.

  The toothed belt 10 includes a belt body 11 formed of an elastomer and a core element 18 embedded in the belt body 11 and extending along the longitudinal direction of the belt. For example, a plurality of core elements 18 are arranged in the width direction by spirally winding a pair of core wires along the longitudinal direction of the toothed belt 10. Become. On one surface (tooth surface) 11A of the belt body 11, tooth portions 15 and tooth bottom portions 16 are alternately provided along the longitudinal direction. A tooth cloth 17 is coated on one surface 11 </ b> A of the belt body 11, that is, on the outer periphery of the tooth portion 15 and the tooth bottom portion 16.

  The belt body 11 includes a tooth rubber layer 12 provided on the tooth surface 11 </ b> A side of the belt body 11, a back rubber layer 13 provided on the other surface (back surface) 11 </ b> B side of the belt body 11, and these tooth rubber layers 12. And the core rubber layer 14 provided between the back rubber layer 13 and the back rubber layer 13 are integrally formed. The core element 18 is disposed on the boundary surface between the back rubber layer 13 and the core rubber layer 14, and the boundary surface between the back rubber layer 13 and the core rubber layer 14 substantially matches the pitch surface of the belt 10. That is, in the present embodiment, the belt body 11 on the back side of the core element 18 is formed by the back rubber layer 13, and the belt body 11 on the tooth surface side of the core element 18 has the tooth rubber layer on the core rubber layer 14. 12 are laminated.

  The boundary surface between the core rubber layer 14 and the tooth rubber layer 12 has a shape corresponding to the shape of the tooth surface 11A, and is farthest from the pitch surface (core element 18) at the center of the tooth portion 15 in the belt longitudinal direction. At the same time, it approaches the pitch surface (core element 18) as it approaches the tooth bottom 16. That is, the core rubber layer 14 swells upward in accordance with the shape of the tooth portion 15 inside the tooth portion 15 and constitutes a central portion inside the tooth portion 15. Further, the tooth rubber layer 12 in the tooth portion 15 is laminated so as to surround the tooth surface 11A side of the core rubber layer 14, and is disposed along the tooth surface 11A. On the other hand, in the vicinity of the tooth bottom portion 16 and the tooth bottom portion 16, both the core rubber layer 14 and the tooth rubber layer 12 are thin layers.

  The tooth rubber layer 12, the back rubber layer 13, and the core rubber layer 14 are formed by vulcanizing a rubber composition. The rubber components of the rubber layers 12 to 14 include HNBR (hydrogenated nitrile rubber), fluorine rubber, NBR (nitrile rubber), a mixture thereof, or a mixture of one or more rubbers with other types of rubber, etc. Among these rubber components, HNBR is preferably used. Moreover, it is preferable that the same kind of rubber is used as the rubber component of the rubber layers 12 to 14.

  The rubber composition of each of the rubber layers 12 to 14 includes various additives such as a vulcanizing agent, an anti-aging agent, a vulcanization aid, and carbon black in addition to the rubber component. Further, the rubber composition of the rubber layers 12 to 14 contains a metal salt of an α, β-ethylenically unsaturated carboxylic acid such as zinc (meth) acrylate in order to improve these strengths. Is preferred.

  The core rubber layer 14 has a large number of short fibers 20 mixed in substantially uniformly, and has a higher modulus than the tooth rubber layer 12 and the back rubber layer 13 in which the short fibers 20 are not mixed. As the short fiber 20, an aramid short fiber having a relatively high modulus is preferably used. In the present embodiment, by increasing the modulus of the core rubber layer 14 over the tooth rubber layer 12, the tooth surface portion can be softened while suppressing the rigidity of the entire tooth portion 15 from being lowered. Therefore, it is possible to improve the durability performance of the tooth portion 15 while suppressing cracks on the tooth surface and bottom of the tooth, generation of abnormal noise during belt operation, and the like.

  The modulus of the rubber layer refers to the stress when a test piece obtained by vulcanizing the same rubber composition as the rubber layer is stretched by 20% as measured according to JIS K6251. In addition, when the short fiber is mixed in the rubber layer, the modulus measured when the short fiber is oriented in one direction in the test piece and the test piece is pulled in the orientation direction. The test piece was vulcanized rubber collected using JIS K6251 dumbbell No. 5 type.

  In the core rubber layer 14, the short fibers 20 are regularly distributed. Specifically, the short fibers 20 are oriented substantially in the thickness direction of the belt in the central region of the tooth portion 15, and with respect to the thickness direction so as to follow the tooth surface as the tooth surface is approached from the central region. In the vicinity of the top portion of the tooth portion 15 and in the vicinity of the tooth bottom portion 16, it is oriented substantially along the longitudinal direction of the belt.

  An intermediate canvas 21 is embedded in the back rubber layer 13 at a position away from the core wire element 18 and substantially parallel to the pitch surface (core wire element 18). The intermediate canvas 21 spreads in a planar shape along the longitudinal direction and the width direction of the belt, and is provided throughout the longitudinal direction and the width direction of the belt. The intermediate canvas 21 is a canvas having high rigidity in the belt width direction and stretchable in the belt longitudinal direction. As the intermediate canvas 21, a canvas having an elastic modulus of 100 GPa or more in the belt width direction is used, and a canvas having an elastic modulus of 180 to 240 GPa is preferably used. The elastic modulus is measured based on the initial tensile resistance of JIS L1095 9.13.

  The intermediate canvas 21 is a woven fabric woven by warp yarns 22 extending in the belt width direction and weft yarns 23 extending in the belt longitudinal direction, and is woven, for example, in a twill weave or a plain weave. As the warp yarn 22 of the intermediate canvas 21, a high-rigidity non-stretchable yarn is used. For example, a yarn composed of aramid fiber, polyparaphenylene benzobisoxazole (PBO) fiber, carbon fiber, or a mixed fiber thereof is used. Is done. Further, as the weft thread 23, an elastic thread is used, for example, a crimped nylon thread such as woolly nylon.

  In the present embodiment, the torsional rigidity of the toothed belt 10 is improved by embedding the intermediate canvas 21 having high rigidity in the belt width direction in the back rubber layer 13. Thereby, the stress concentration in the width direction of the teeth during the belt operation can be reduced, and the durability performance of the belt can be improved. Furthermore, it is possible to reduce the effective tension during belt operation without lowering the rigidity by increasing the viscoelasticity (tan δ) of the rubber used for the tooth portion 15. When the effective tension is reduced, the load acting on the belt is suppressed and the durability of the belt can be improved. Further, by using the stretchable yarn as the yarn extending in the longitudinal direction of the belt of the intermediate canvas 21, the intermediate canvas 21 can be easily attached to the toothed mold in the manufacturing process described later, and the formability of the belt is improved. be able to.

  In the present embodiment, the rubber composition of the tooth rubber layer 12 is preferably blended with high density polyethylene. As the high-density polyethylene added to the rubber composition, for example, a particulate or fibrous one may be used, and the surface may be surface-treated by adding an OH group and / or a COOH group. In the present specification, the high density polyethylene means a specific gravity of 0.92 or more, and the specific gravity is preferably 0.92 to 0.96. Moreover, the deflection temperature under load (according to ASTM-D648) of the high-density polyethylene added to the rubber composition is, for example, about 100 to 130 ° C., and the average molecular weight by the viscosity method is about 300,000 to 400,000. Note that high-density polyethylene does not have a crosslinkable portion with other molecules.

  When the high-density polyethylene is included in the tooth rubber layer 12, the tan δ at 100 to 120 ° C. of the tooth rubber layer 12 measured by the dynamic viscoelasticity measurement method is in the range of 0.100 to 0.120. It is preferable. Note that tan δ is a loss tangent (= E ″ / E ′) that is a ratio of a storage elastic modulus (E ′) corresponding to elasticity and a loss elastic modulus (E ″) corresponding to viscosity. Since the tan δ of the tooth rubber layer 12 falls within the above range under a high temperature environment, it becomes easy to absorb the load energy applied to the meshing surface (tooth surface 11A) of the belt under a high temperature environment. Even if it is used, the generation of abnormal noises that occur when meshing is prevented. In addition, by including high-density polyethylene in the tooth rubber layer 12, the adhesiveness between the tooth rubber layer 12 and the tooth cloth 17 can be increased while keeping tan δ within the above range, thereby improving the durability of the belt. it can. The high-density polyethylene having the above properties can be well mixed and compatible with the rubber composition by the method described later.

  Tan δ is a thickness of 1.9 to 2.7 mm, a width of 6 mm, and a length of 5 mm made from a sample obtained by vulcanizing the same rubber composition as the tooth rubber layer at a temperature of 120 ° C. for 20 minutes. This is what was measured using a sample. In addition, as a measuring device, a viscoelasticity spectrometer manufactured by Shimadzu Corporation (trade name: viscoelasticity testing machine, Triton 2000 made by Triton) is used for measurement under the measurement conditions of amplitude ± 2.5% and frequency 1 Hz. To do.

  In the rubber composition of the tooth rubber layer 12, the high-density polyethylene is blended in an amount of 10 parts by weight or less, preferably 3 to 10 parts by weight, particularly preferably 5 to 10 parts by weight based on 100 parts by weight of the matrix rubber. If less than 3 parts by weight of high-density polyethylene is blended, the improvement in durability and sound performance is limited. If more than 10 parts by weight is blended, the durability and sound performance are not substantially improved. Moreover, when 5-10 weight part is mix | blended, durability performance can be improved especially effectively. “100 parts by weight of matrix rubber” means that rubber and α, β-ethylenically unsaturated carboxylic acid are used when a metal salt of α, β-ethylenically unsaturated carboxylic acid is blended in the rubber composition. This indicates that the total amount with the metal salt is 100 parts by weight, and when the metal salt of the α, β-ethylenically unsaturated carboxylic acid is not blended, it indicates that the rubber alone is 100 parts by weight.

  The back rubber layer 13 and the core rubber layer 14 are preferably substantially free of high density polyethylene. The back rubber layer 13 and the core rubber layer 14 are separated from the meshing surface (tooth surface 11A) with the pulley, and it is not necessary to absorb the load energy applied to the meshing surface of the belt. This is because when high-density polyethylene is blended, it is difficult to improve the durability of the teeth.

  When the rubber composition of the tooth rubber layer 12 (that is, the tooth rubber sheet 12 '(see FIG. 2)) contains high-density polyethylene, it is prepared as follows. First, additives other than the vulcanizing agent including high density polyethylene are kneaded together with rubber (matrix rubber) (primary kneading). At this time, the kneading temperature is equal to or higher than the deflection temperature under load of the high-density polyethylene. Therefore, the high-density polyethylene is mixed with the rubber in a softened state, and is well mixed and compatible with the rubber. After the primary kneading, the rubber composition is further added with a vulcanizing agent, kneaded at a temperature lower than the vulcanizing temperature of the vulcanizing agent (lower than the kneading temperature of the primary kneading) (secondary kneading), and then toothed by calendaring. Sheet 12 'is obtained. If the rubber composition of the tooth rubber layer 12 is kneaded with the rubber component at a temperature equal to or higher than the deflection temperature under load, and the vulcanizing agent is kneaded with the rubber component at a temperature lower than the vulcanization temperature. For example, it is not necessary to knead by the above method. For example, additives other than the vulcanizing agent may be added by secondary kneading.

  The tooth cloth 17 preferably includes polyarylate fibers. For example, the tooth cloth 17 is composed of a warp yarn extending in the width direction of the belt and a woven fabric woven by a weft yarn extending in the longitudinal direction of the belt, and the weft yarn preferably includes polyarylate. For example, the weft yarn is a composite yarn including a yarn made of polyarylate fiber and a yarn made of fiber having higher stretchability than polyarylate fiber (hereinafter referred to as high stretch fiber yarn). For example, the composite yarn is constituted by using a highly stretchable fiber yarn as a core yarn, a polyarylate fiber yarn is wound around the core yarn, and a cover yarn is wound around the polyarylate fiber yarn.

  As the highly stretchable fiber yarn, for example, urethane elastic yarn or the like is used, and as the cover yarn, for example, a yarn composed of nylon fiber, polyester fiber or the like is used. The polyarylate fiber used for the weft is made of a so-called wholly aromatic polyester, and specific examples thereof include Vectran (trade name, manufactured by Kuraray Co., Ltd.). The material of the warp yarn of the tooth cloth 17 is not particularly limited, but is composed of nylon fiber or polyester fiber.

  The tooth cloth 17 is preferably impregnated with rubber paste by being dipped in rubber glue and dried before being bonded to the tooth surface 11A of the belt body 11. Thereby, rubber paste is vulcanized at the time of vulcanization molding, and the tooth cloth 17 is easily bonded to the tooth rubber layer 12. The rubber paste preferably contains high-density polyethylene in addition to the rubber component. As the high density polyethylene, the same one as blended in the tooth rubber layer 12 is used. Since the rubber paste contains high-density polyethylene, the adhesion between the tooth rubber layer 12 and the tooth cloth 17 can be further improved, and the friction coefficient of the tooth surface can be reduced, so that the life of the belt 10 is further increased. It can be extended. Furthermore, since the high density polyethylene having the above properties can be sufficiently mixed and compatible with the rubber component of the rubber paste, it is prevented from being detached from the tooth cloth as the belt is operated.

  The high-density polyethylene is preferably blended in an amount of 15 to 40 parts by weight with respect to 100 parts by weight of the rubber component in the rubber paste. If less than 15 parts by weight of high-density polyethylene is blended, the effect of reducing the friction coefficient of the belt is limited, and the adhesive force of the tooth cloth 17 to the tooth rubber layer 12 cannot be sufficiently increased. On the other hand, when the amount is more than 40 parts by weight, the friction coefficient, particularly the friction coefficient in a high temperature environment increases due to the sticking caused by softening of the high density polyethylene, and the durability of the belt cannot be sufficiently improved. In order to further enhance the durability of the belt, the high-density polyethylene is particularly preferably blended in an amount of 24 to 40 parts by weight with respect to 100 parts by weight of the rubber component of the rubber paste, and the friction coefficient is sufficiently reduced. In order to sufficiently increase the adhesive strength between the tooth 17 and the tooth rubber layer, it is most preferably 24 to 32 parts by weight.

  Rubber paste is a rubber composition in which various additives such as high density polyethylene, vulcanizing agent, anti-aging agent, vulcanization aid, carbon black, etc. are blended with rubber, organic reinforcing agent such as phenol resin, and solvent Is added. As the rubber component of the rubber paste, the same rubber component as exemplified in the rubber layers 12 to 14 is used, but HNBR is used and / or the same kind of rubber as the tooth rubber layer 12 is used. preferable. Moreover, when the rubber composition of rubber paste contains high-density polyethylene, it is preferably obtained by kneading by the same method as the rubber composition of the tooth rubber layer 12.

  Next, the manufacturing process of the toothed belt 10 will be described with reference to FIGS. FIG. 2 shows a toothed mold 31 with a pre-formed rubber tooth cloth 32, a core wire 18 ′, an intermediate canvas 21 ′ having a first back rubber sheet 13A ′ affixed thereto, and a second back rubber sheet 13B ′. The winding process is shown. Note that the tooth rubber sheet 12 ′, the core rubber sheet 14 ′, and the back rubber sheets 13 A ′ and 13 B ′ in FIG. 2 are respectively formed in the belt 10 after the vulcanization molding in the tooth rubber layer 12, the core rubber layer 14, and the back rubber layer 13. It will be. Each of the rubber sheets is obtained by forming an unvulcanized rubber composition into a sheet, and the core rubber sheet 14 'is blended with short fibers 20. Further, the tooth cloth 17 ′, the core wire 18 ′, and the intermediate canvas 21 ′ become the tooth cloth 17, the core wire element 18, and the intermediate canvas 21 in the belt 10.

  In this method, a tooth cloth 17 'impregnated with rubber glue is first preformed into a corrugated shape, and tooth parts 15' and tooth bottom parts 16 'are alternately provided along a predetermined direction on the tooth cloth 17'. It is done. Next, the tooth rubber sheet 12 ′ and the core rubber sheet 14 ′ are pressure-bonded and integrated with the pre-formed tooth cloth 17 ′ in this order to prepare a tooth cloth 32 with a pre-formed rubber. At this time, the tooth rubber sheet 12 ′ and the core rubber sheet 14 ′ are pressed against each other to be thickly bonded to the tooth portion 15 ′ of the tooth cloth 17 ′, whereas the tooth rubber sheet 12 ′ and the core rubber sheet 14 ′ Is thinly bonded. Further, in the core rubber sheet 14 ′, the short fibers 20 are oriented in the predetermined direction before crimping, but when they are crimped to the tooth cloth 17 ′, they are inclined so as to follow the tooth shape inside the tooth portion 15 ′. It is done.

  Next, a toothed mold 31 used for vulcanization molding of the toothed belt 10 is prepared. The toothed mold 31 has a cylindrical shape, the outer peripheral surface thereof has a shape that matches the shape of the tooth surface of the belt 10, and concave portions 33 and convex portions 34 are alternately provided along the circumferential direction. A tooth cloth 32 with a pre-molded rubber is first wound around the outer peripheral surface of the toothed mold 31 so that each tooth portion 15 ′ is disposed inside each recess 33. Each tooth portion 15 ′ does not normally have a shape that completely coincides with the concave portion 33, and there is a gap between the tooth portion 15 ′ and the concave portion 33.

  Next, the core wire 18 ′ is spirally wound on the core rubber sheet 14 ′ of the pre-formed rubber tooth cloth 32. An intermediate canvas 21 ′ having a predetermined thickness of the first back rubber sheet 13A ′ affixed on the wound core 18 ′, the back rubber sheet 13A ′ is located inside the mold 31 (on the side of the core 18 ′). ). However, the first back rubber sheet 13A ′ is separate from the intermediate canvas 21 ′, and the first back rubber sheet 13A ′ and the intermediate canvas 21 ′ are wound around the core 18 ′ in this order. Also good. At this time, the warp yarn 22 is arranged along the axial direction of the mold 31 and the weft yarn 23 is arranged along the circumferential direction of the mold 31. A second back rubber sheet 13B 'is further wound on the wound intermediate canvas 21'. The toothed mold 31 around which the pre-formed rubber tooth cloth 32 and the like are wound is accommodated in a vulcanizer (not shown). In the vulcanizer, the pre-formed rubber tooth cloth 32 wound around the toothed mold 31 is heated by, for example, steam and vulcanized from the outside to the inside by a vulcanization bag or the like provided in the vulcanizer. Pressed.

  By the pressurization and heating, the rubber sheets 12 ′, 13A ′, 13B ′, and 14 ′ are pressed inward while the fluidity is increased, and the second back rubber sheet 13B ′ is the warp yarn 22 of the intermediate canvas 21 ′. Then, it flows into the inside through the gap of the weft thread 23 and is integrated with the first back rubber sheet 13A ′. As a result, the intermediate canvas 21 'is embedded in the back rubber sheets 13A' and 13B '. Furthermore, the core wire 18 'is also embedded between the back rubber sheet 13A' and the core rubber sheet 14 '. Further, the tooth cloth 17 ′ is pressed by these rubber sheets to have a shape that matches the outer peripheral surface of the mold 31, and the tooth surface of the belt is formed. Here, a part of the short fibers 20 inside the core rubber sheet is further oriented along the thickness direction, and the orientation shown in FIG. 1 is exhibited. Further, each rubber sheet is vulcanized by the pressurization and heating, and each rubber sheet, the tooth cloth 17 ′, the intermediate canvas 21 ′, and the core wire 18 ′ are integrated to form a belt slab 10 ′ as shown in FIG. Is obtained. The belt slab 10 ′ is removed from the toothed mold 31 and cut after polishing, thereby forming the toothed belt 10 (see FIG. 1).

  Examples are shown below as specific examples of the present embodiment, but the present invention is not limited to the following examples.

[Example 1]
A woven fabric woven with a twill weaving of warp and weft 2/2 was prepared as a tooth cloth. In the tooth cloth, the warp yarn is a filament yarn of 110 dtex nylon 66, and the weft yarn is a 280 dtex polyarylate fiber yarn (Vectran (trade name, manufactured by Kuraray Co., Ltd.) around a core yarn made of urethane elastic yarn of 470 dtex. ) And a cover yarn made of 110 dtex nylon 66 was further wound around the polyarylate fiber yarn. Next, the tooth cloth was immersed in a rubber paste having the rubber composition shown in Table 1 and then dried (100 ° C., 5 minutes) to be impregnated. For rubber paste, additives other than the vulcanizing agent and rubber components are kneaded at 120 ° C or higher (primary kneading), and then the vulcanizing agent is added and kneaded below the vulcanizing temperature of the vulcanizing agent to obtain a rubber composition. Obtained (secondary kneading), MEK and phenol resin were added to the rubber composition. In the rubber paste, the weight ratio of rubber composition: phenol resin: MEK was 100: 33: 500.

※ゴム成分としてZetpol 2020（商品名．日本ゼオン社製）を、ＨＤＰＥ（高密度ポリエチレン）としてインヘンス（ＩＮＨＡＮＣＥ）ＰＥＦファイバー（商品名．フルオロシール社製）を使用した。

* Zetpol 2020 (trade name, manufactured by Nippon Zeon Co., Ltd.) was used as the rubber component, and INHANCE PEF fiber (trade name, manufactured by Fluoroseal Co., Ltd.) was used as HDPE (high density polyethylene).

  Back rubber sheets (first and second back rubber sheets) having a rubber composition shown in Table 2, a core rubber sheet, and a tooth rubber sheet were prepared. The core rubber sheet was blended with aramid short fibers, and the modulus of the core rubber sheet was higher than that of the first and second back rubber sheets and the tooth rubber sheet. The tooth rubber sheet was obtained by calendering a rubber composition kneaded in the same manner as the rubber composition of rubber paste. Next, a tooth cloth impregnated with rubber paste was preformed, and a tooth rubber sheet and a core rubber sheet were pressure-bonded to the tooth cloth to obtain a tooth cloth with a pre-formed rubber.

※１ 表中において、ＨＮＢＲ／(ＨＮＢＲ＋ジメタクリル酸亜鉛)、ジメタクリル酸亜鉛／(ＨＮＢＲ＋ジメタクリル酸亜鉛)はこれらの比率を、それ以外は重量部であることを示す。
※２ ＨＮＢＲポリマーは水素添加率９９％のＨＮＢＲであった。
※３ ジメタクリル酸亜鉛含有ポリマー（１）は、ＨＮＢＲとジメタクリル酸亜鉛の配合比が５５：４５のゴムマトリックスであり、ＨＮＢＲの水素添加率は９９％であった。
※４ ジメタクリル酸亜鉛含有ポリマー（２）は、ＨＮＢＲとジメタクリル酸亜鉛の配合比が８３：１７のゴムマトリックスであり、ＨＮＢＲの水素添加率は９６％であった。
※５ ＨＤＰＥとして、インヘンス（ＩＮＨＡＮＣＥ）ＰＥＦファイバー（商品名．フルオロシール社製）を使用した。

* 1 In the table, HNBR / (HNBR + zinc dimethacrylate) and zinc dimethacrylate / (HNBR + zinc dimethacrylate) indicate these ratios, and the others are parts by weight.
* 2 HNBR polymer was HNBR with a hydrogenation rate of 99%.
* 3 Zinc dimethacrylate-containing polymer (1) was a rubber matrix having a blending ratio of HNBR and zinc dimethacrylate of 55:45, and the hydrogenation rate of HNBR was 99%.
* 4 Zinc dimethacrylate-containing polymer (2) was a rubber matrix having a mixing ratio of HNBR and zinc dimethacrylate of 83:17, and the hydrogenation rate of HNBR was 96%.
* 5 As the HDPE, INHANCE PEF fiber (trade name, manufactured by Fluoroseal) was used.

  Next, the pre-formed rubber tooth cloth, the core wire, the intermediate canvas on which the first back rubber sheet was attached, and the second back rubber sheet were wound around the tooth mold in this order. As the intermediate canvas, weaving a weft nylon of 470 dtex made of nylon 66 and a woven fabric in which warp yarn of 440 dtex made of twisted yarn of aramid fiber (trade name: Technora HM, manufactured by Teijin Techno Products Co., Ltd.) is woven in a plain weave. The weft yarn was arranged along the circumferential direction of the mold. The elastic modulus in the warp direction (corresponding to the width direction of the belt) of the intermediate canvas before being wound around the mold was 100 GPa. Next, a rubber sheet or the like attached to the mold was vulcanized and molded by heating and pressurizing in a vulcanizer to obtain a belt slab. The belt slab was polished and cut to obtain a toothed belt having a belt width of 16 mm, a circumferential length of 900 mm, and a number of teeth of 92.

[Example 2]
Example 2 is a woven fabric in which a warp yarn of 470 dtex made of nylon 66 as an intermediate canvas and a warp yarn of 550 dtex made of a twisted yarn of PBO fiber (trade name: PBO, manufactured by Toyobo Co., Ltd.) is woven in a plain weave. The same operation as in Example 1 was carried out except that it was used. The elastic modulus in the warp direction (corresponding to the width direction of the belt) of the intermediate canvas was 180 GPa.

[Example 3]
In Example 3, a weft of 470 dtex Woolley nylon yarn made of nylon 66 and a woven fabric in which 600 dtex warp yarn made of 12K carbon fiber (trade name: T300, manufactured by Toray Industries, Inc.) was woven in a plain weave was used as an intermediate canvas. Except for this, the same procedure as in Example 1 was performed. The elastic modulus in the warp direction (corresponding to the width direction of the belt) of the intermediate canvas was 240 GPa.

[Comparative Example 1]
Comparative Example 1 was the same as Example 1 except that wefts of 470 dtex Woolley nylon yarn made of nylon 66 and woven fabrics of warp nylon of 470 dtex Woolley nylon yarn made of nylon 66 were used as the intermediate canvas. Implemented. The elastic modulus in the warp direction (corresponding to the width direction of the belt) of the intermediate canvas was 3 GPa.

[Comparative Example 2]
Comparative Example 2 is a woven fabric in which a weft nylon of 470 dtex made of nylon 66 as an intermediate canvas and a warp yarn of 440 dtex made of twisted yarn of aramid fiber (trade name: Technora, manufactured by Teijin Techno Products Co., Ltd.) are woven in plain weave. This was carried out in the same manner as in Example 1 except that was used. The elastic modulus in the warp direction (corresponding to the width direction of the belt) of the intermediate canvas was 50 GPa.

[Evaluation method]
The belts of the above examples and comparative examples were evaluated for torsional rigidity, effective tension, and durability performance by the following methods.

  FIG. 4 is a schematic diagram showing a test method for confirming the torsional rigidity of the belts of Examples and Comparative Examples. As shown in FIG. 4, in this test, measurement jigs 53 and 54 having toothed pulleys 51 and 52 each having 20 teeth were prepared, and the toothed belt 10 was installed on the pulleys 51 and 52. The pulley 51 was pulled upward away from the pulley 52 by a measuring jig 53 with a load of 500 N in parallel with the center line CL connecting the centers of the two pulleys 51 and 52, and fixed in that state. Thereafter, the pulley 52 was rotated counterclockwise by 45 ° around the center line CL by the measuring jig 54, and the load required for the rotation was measured as the torsional rigidity of the belt. FIG. 5 shows the result.

  FIG. 6 is a layout showing an example of a transmission system in an internal combustion engine. Using this transmission system, a durability performance test was carried out on the toothed belts of the above examples and comparative examples. The transmission system 40 includes a pulley 41 with a driving tooth of 20 teeth and a diameter of 60 mm connected to a crankshaft, pulleys 42 and 43 with a tooth of 40 teeth and a diameter of 121 mm connected to a camshaft, and a flat tensioner having a diameter of 80 mm. It has a pulley 44. The toothed belt 10 was installed on the pulleys 41 to 43 and rotated at 4000 rpm in a state where tension was applied from the outer peripheral side by the tensioner pulley 44 on the loose side of the belt, and the time until the belt was damaged was measured. The test was performed in an atmosphere at 120 ° C. For each example and comparative example, the time when the belt is broken is shown in FIG.

  Further, in the transmission system 40, a torque detector provided with a toothed pulley having the same number of teeth and diameter instead of the driving toothed pulley 41 is provided. A toothed belt was installed on the torque detector and driven toothed pulleys 42 and 43 with a mounting tension of 170 N, and the torsional torque when the rotational speed of the belt was changed to 1000 to 6000 rpm was detected by the torque detector. The effective tension was calculated from the torsional torque, and the maximum effective tension at a rotational speed of 1000 to 6000 rpm was determined. The result is shown in FIG.

  As shown in FIGS. 5, 7, and 8, in each of the examples, the elastic modulus of the intermediate canvas provided in the back rubber layer is set to 100 GPa or more, so that the torsional rigidity is improved and the effective tension is reduced. The performance could be improved. On the other hand, in the comparative example, an intermediate canvas was provided in the same manner as in the example. However, since the elastic modulus of the intermediate canvas was low, the effective tension and durability of the belt could not be sufficiently improved.

DESCRIPTION OF SYMBOLS 10 Toothed belt 11 Belt main body 12 Tooth rubber layer 13 Back rubber layer 14 Core rubber layer 15 Tooth part 16 Tooth bottom part 17 Tooth cloth 18 Core element 20 Short fiber 21 Intermediate canvas

Claims (8)

A belt main body formed of an elastomer in which tooth portions and tooth bottom portions are alternately provided on one surface along the longitudinal direction;
A core element embedded in the belt body and extending in the belt longitudinal direction;
An intermediate canvas embedded in the other side of the belt main body than the core element,
The tooth part is formed by a core rubber layer constituting the inside of the tooth part, and a tooth rubber layer disposed along the outer periphery of the tooth part and laminated on the one surface side of the core rubber layer,
Modulus in the belt width direction of the intermediate canvas is state, and are more 100 GPa,
The toothed rubber layer includes a high density polyethylene having a specific gravity of 0.92 to 0.96 .   The toothed belt according to claim 1, wherein the intermediate canvas is a woven fabric woven by a thread extending in a belt width direction and a thread extending in a belt longitudinal direction.   The toothed belt according to claim 2, wherein the yarn extending in the belt width direction includes at least one of an aramid fiber, a PBO fiber, and a carbon fiber.   The toothed belt according to claim 2, wherein the yarn extending in the belt longitudinal direction is a stretchable yarn.   The toothed belt according to claim 4, wherein the stretchable yarn is a crimped nylon yarn.   The toothed belt according to claim 1, wherein the intermediate canvas is disposed substantially parallel to the core wire element. Toothed belt according to claim 1, before modulus of relaxin rubber layer, being higher than the modulus of the tooth rubber layer.   The toothed belt according to claim 1, wherein the toothed belt is used in an internal combustion engine.

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