Toothed belt

Abstract

The toothed belt 1 of the present invention has a back portion 11 and belt teeth 12. The belt teeth 12 include a tooth portion 22 made of a cross-linked rubber composition, and a reinforcing cloth 4 covering the surface of the tooth portion 22. The reinforcing cloth 4 is a woven fabric 41 including warp yarns 42 and weft yarns 43. The warp yarns 42 are arranged in the circumferential direction, and the weft yarns 43 are arranged in the width direction. When the product of the fineness and yarn density of the warp yarns 42 is the unit fiber weight of the warp yarns 42, and the product of the fineness and yarn density of the weft yarns 43 is the unit fiber weight of the weft yarns 43, the ratio of the unit fiber weight of the weft yarns 43 to the unit fiber weight of the warp yarns 42 is 2.0 or more, the unit fiber weight of the weft yarns 43 is 80,000 dtex / 5 cm or more and 400,000 dtex / 5 cm or less, and the unit fiber weight of the warp yarns 42 is 15,000 dtex / 5 cm or more and 65,000 dtex / 5 cm or less.

Description

[Technical Field]

[0001] The present invention relates to a toothed belt. This application claims priority from Japanese Application No. 2024-056559, filed March 29, 2024, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Toothed belts are suitable for applications requiring synchronous rotation and are used in a variety of fields, including as a power transmission means for motorcycles (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-290467 Summary of the Invention [Problem to be solved by the invention]

[0004] Considering the impact on the environment, there is a growing trend toward electrification of transportation vehicles such as motorcycles and automobiles. Since batteries are installed in the vehicle body along with the motor, the vehicle mass increases compared to vehicles with internal combustion engines. Therefore, it is expected that the load on toothed belts will increase. Since motorcycles often do not have belt covers, toothed belts are exposed to dust. Therefore, improved dust abrasion resistance is required for applications where they are exposed to dust. The belt teeth of a toothed belt mesh with the pulley grooves of a toothed pulley. The surface of the belt teeth includes a reinforcing fabric. Until now, post-processing such as dipping and sizing have been used to increase the strength of the reinforcing fabric and improve the dust abrasion resistance of toothed belts. However, even if the reinforcing fabric strength is increased by this post-processing, toothed belts may not be able to withstand the expected high loads in dusty environments. [Means for solving the problem]

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a toothed belt that can achieve improved dust abrasion resistance.

[0006] (1) The toothed belt of the present invention is used in a transmission system having a transmission capacity of 0.75 kW or more and 90 kW or less, and comprises an endless belt-like back portion and belt teeth provided on the inner circumferential side of the back portion, the belt teeth comprise tooth portions made of a cross-linked rubber composition and a reinforcing cloth covering the surface of the tooth portions, the reinforcing cloth being a woven fabric containing warp yarns and weft yarns, each of the warp yarns and weft yarns being a cord formed by twisting together a plurality of filaments, the warp yarns being arranged in the circumferential direction of the toothed belt, and the weft yarns being arranged in the circumferential direction of the toothed belt. The warp yarns are arranged in the width direction of the belt, and when the product of the fineness of the warp yarn and the thread density of the warp yarn in the woven fabric is defined as the unit fiber amount of the warp yarn and the product of the fineness of the weft yarn and the thread density of the weft yarn in the woven fabric is defined as the unit fiber amount of the weft yarn, the ratio of the unit fiber amount of the weft yarn to the unit fiber amount of the warp yarn is 2.0 or more, the unit fiber amount of the weft yarn is 80,000 dtex / 5 cm or more and 400,000 dtex / 5 cm or less, and the unit fiber amount of the warp yarn is 15,000 dtex / 5 cm or more and 65,000 dtex / 5 cm or less.

[0007] This toothed belt can effectively prevent exposure of warp yarns due to wear of the reinforcing fabric, and can improve dust wear resistance.

[0008] (2) In the toothed belt of (1) above, it is preferable that the fineness of each of the filaments contained in the weft is 4.5 dtex or less. In this case, the weft yarns are densely packed in the reinforcing fabric, which more effectively prevents the warp yarns from being exposed due to wear of the reinforcing fabric, and the toothed belt can improve its dust wear resistance.

[0009] (3) The toothed belt of (1) or (2) above has an air permeability of 30 cm or less, as determined in accordance with the air permeability test method specified in JIS L1096. 3 / (cm 2 ·s) or less is preferable. In this case, exposure of the warp yarns due to wear of the reinforcing fabric is more effectively suppressed, and the toothed belt can be improved in dust wear resistance.

[0010] (4) In any one of the toothed belts (1) to (3) above, when the ratio of the mass per unit area of ​​the fabric to the thickness of the fabric is defined as the packing degree, the packing degree of the fabric is 300 μg / (mm 2 ·mm) or more 500μg / (mm) 2 It is preferable that the thickness is less than 1 / 4 mm. In this case, exposure of the warp yarns due to wear of the reinforcing fabric is more effectively suppressed, and the toothed belt can be improved in dust wear resistance. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a toothed belt that can achieve improved dust abrasion resistance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a side view schematically illustrating an example of a transmission system. [Figure 2] FIG. 2 is a perspective view schematically showing a toothed belt. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. [Figure 5] FIG. 2 is a perspective view schematically showing a reinforcing cloth. [Figure 6] FIG. 10 is a diagram illustrating the structure of a code. [Figure 7] 1A to 1C are diagrams illustrating a method for manufacturing a toothed belt. [Figure 8] 1A to 1C are diagrams illustrating a method for manufacturing a toothed belt. [Figure 9]1A to 1C are diagrams illustrating a method for manufacturing a toothed belt. [Figure 10] FIG. 1 is a diagram showing the pulley layout of a transmission system used to evaluate dust wear resistance properties. BEST MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments described below.

[0014] (Transmission System) FIG. 1 is a side view that schematically shows an example of a transmission system 7 in which a toothed belt 1 according to an embodiment of the present invention is used. The transmission system 7 basically comprises a drive pulley 71, a driven pulley 72, a prime mover 73, and a toothed belt 1. The drive pulley 71 and the driven pulley 72 each have a pulley groove 74. The drive pulley 71 and the driven pulley 72 are toothed pulleys. The prime mover 73 is, for example, a motor or an engine. The toothed belt 1 has belt teeth 12.

[0015] The toothed belt 1 is wound around a drive pulley 71 and a driven pulley 72. The belt teeth 12 mesh with the pulley grooves 74. The drive pulley 71 is fixed to a drive shaft 75 of a prime mover 73. The driven pulley 72 is fixed to a driven shaft 76. When the prime mover 73 starts and the drive shaft 75 rotates, the drive pulley 71 rotates. The toothed belt 1 moves, causing the driven pulley 72 to rotate. This causes the driven shaft 76 to rotate. The driven shaft 76 is rotated by the prime mover 73. The toothed belt 1 transmits the power of the prime mover 73 to the driven shaft 76. The speed ratio of the transmission system 7 (number of teeth of the driven pulley 72 / number of teeth of the drive pulley 71) is determined appropriately according to the specifications of the device to which it is applied.

[0016] The transmission system 7 is applied to, for example, vehicles such as two-wheeled automobiles and four-wheeled automobiles, and general industrial machines such as machine tools, printing machines, textile machines, and injection molding machines. The toothed belt 1 of the present invention described below is used in a transmission system 7 having a transmission capacity of 0.75 kW or more and 90 kW or less. Examples of such transmission systems 7 include rear-wheel drive devices for motorcycles, electric power steering devices for passenger cars, and drive devices for industrial robots. The transmission capacity of the transmission system 7 is set based on the rated output of the prime mover 73 .

[0017] (toothed belt) FIG. 2 is a perspective view showing an example of a toothed belt 1 according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a cross-sectional view taken along line BB in FIG. FIG. 2 shows a portion of a toothed belt 1. The toothed belt 1 is an endless meshing power transmission belt. The toothed belt 1 is a single-sided toothed belt. The toothed belt 1 is used in the rear wheel drive system of a two-wheel electric vehicle. 2 to 4, the direction indicated by the double-headed arrow X is the width direction of the toothed belt 1. The direction indicated by the double-headed arrow Y is the circumferential direction of the toothed belt 1. The belt circumferential direction is also the length direction of the toothed belt 1. The direction indicated by the double-headed arrow Z is the thickness direction of the toothed belt 1. The upper side of each page is the outer circumferential side of the toothed belt 1, and the lower side is the inner circumferential side.

[0018] The belt length of the toothed belt 1 is, for example, 225 mm or more and 6000 mm or less. The belt width Wb of the toothed belt 1 is, for example, 10 mm or more and 120 mm or less. The belt thickness Tb of the toothed belt 1 is, for example, 3.5 mm or more and 9.0 mm or less. The belt thickness Tb of the toothed belt 1 is the thickness of the toothed belt 1 at its thickest portion. The dimensions of the toothed belt according to the embodiment of the present invention are not limited to this range.

[0019] The toothed belt 1 has a back portion 11 and a plurality of belt teeth 12 . The back portion 11 extends in the circumferential direction of the belt. The back portion 11 is in the form of an endless belt. In a cross section of the toothed belt 1 perpendicular to the circumferential direction of the belt, the cross section of the back portion 11 is rectangular. A plurality of belt teeth 12 are provided on the inner circumferential side of the back portion 11. The plurality of belt teeth 12 are arranged at equal intervals in the circumferential direction of the belt. Each belt tooth 12 extends in the width direction of the belt. The pitch Pb of the belt teeth 12 is, for example, not less than 8 mm and not more than 14 mm. The belt teeth 12 have a tooth profile, for example, a circular arc tooth profile.

[0020] (Configuration of toothed belt) The toothed belt 1 includes a belt body 2, a core wire 3, and a reinforcing cloth 4. The belt body 2, the core wire 3, and the reinforcing cloth 4 will be described below.

[0021] (Belt body) The belt body 2 has a belt shape. The belt body 2 is made of, for example, a rubber composition obtained by crosslinking an uncrosslinked rubber composition containing a rubber component and a rubber compounding agent through heating and pressure, i.e., a crosslinked product of the rubber composition. Examples of the rubber component include hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), ethylene-α-olefin elastomers such as ethylene-propylene-diene rubber (EPDM), chlorosulfonated polyethylene rubber, styrene-butadiene rubber, and epichlorohydrin rubber. Of these, HNBR and EPDM are preferred.

[0022] As the rubber compounding agent, conventionally known rubber compounding agents can be used, examples of which include a vulcanization accelerator, an antioxidant, a reinforcing agent, a plasticizer, a co-crosslinking agent, and a crosslinking agent. Examples of the vulcanization accelerator aid include metal oxides, metal carbonates, fatty acids and derivatives thereof, etc. Examples of the metal oxides include zinc oxide (zinc white), magnesium oxide, etc. These vulcanization accelerators may be used alone or in combination of two or more. The content of the vulcanization accelerator aid is, for example, 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the rubber component.

[0023] Examples of the antiaging agent include benzimidazole-based antiaging agents, aromatic secondary amine-based antiaging agents, amine-ketone-based antiaging agents, etc. These antiaging agents may be used alone or in combination of two or more. The content of the antioxidant relative to 100 parts by mass of the rubber component is, for example, 1.5 parts by mass or more and 5.0 parts by mass or less.

[0024] Examples of the reinforcing material include carbon black, silica, etc. Carbon black and silica may be used in combination as the reinforcing material. Examples of the carbon black include channel black, furnace black, thermal black, and acetylene black. Examples of the furnace black include SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234. Examples of the thermal black include FT and MT. Only one type of carbon black may be used, or two or more types may be used in combination.

[0025] When carbon black is used, the content thereof is, for example, 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the rubber component. When silica is used, the content thereof is, for example, 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber component.

[0026] Examples of the plasticizer include dialkyl sebacate, dialkyl phthalate, and dialkyl adipate. Examples of the dialkyl sebacate include polyether ester and dioctyl sebacate (DOS). Examples of the dialkyl phthalate include dibutyl phthalate (DBP) and dioctyl phthalate (DOP). Examples of the dialkyl adipate include dioctyl adipate (DOA). These plasticizers may be used alone or in combination of two or more. The amount of the plasticizer is, for example, 5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the rubber component.

[0027] Examples of the co-crosslinking agent include trimethylolpropane trimethacrylate, m-phenylenedimaleimide, zinc dimethacrylate, triallyl isocyanurate, etc. These co-crosslinking agents may be used alone or in combination of two or more. The content of the co-crosslinking agent is, for example, 3 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.

[0028] Examples of the crosslinking agent include sulfur and organic peroxides. Sulfur and organic peroxides may be used in combination, or, of course, either one may be used alone. When sulfur and an organic peroxide are used in combination as the crosslinking agent, the total compounding amount of the crosslinking agents is preferably, for example, 0.1 part by mass or more and 3 parts by mass or less of sulfur and 1 part by mass or more and 8 parts by mass or less of organic peroxide per 100 parts by mass of the rubber component.

[0029] The belt body 2 includes a base portion 21 and a plurality of teeth 22 . The base portion 21 extends in the circumferential direction of the belt. The core wire 3 is embedded in the base portion 21. The plurality of tooth portions 22 are provided on the inner circumferential side of the base portion 21. The plurality of tooth portions 22 are integral with the base portion 21. The plurality of tooth portions 22 are arranged at equal intervals in the circumferential direction of the belt. The surfaces of the tooth portions 22 are covered with a reinforcing cloth 4. As described above, the belt body 2 is a cross-linked product of a rubber composition. The base portion 21 and the tooth portion 22 are each made of a cross-linked product of a rubber composition. 2, the base portion 21 and the toothed portion 22 are made of the same rubber composition. The rubber composition for the base portion 21 and the rubber composition for the toothed portion 22 may be different rubber compositions.

[0030] (core wire) As described above, the core wire 3 is embedded in the base portion 21. Examples of the core wire 3 include a glass core wire, an aramid core wire, a carbon core wire, and a steel core wire. These core wires are preferably made of twisted yarn. Carbon and steel core wires are preferred as the core wire 3. Carbon and steel are materials with high elastic moduli. Therefore, toothed belts equipped with carbon or steel core wires are less likely to change in length when a load is applied, and the tooth pitch changes only slightly. Therefore, toothed belts equipped with carbon or steel core wires can easily maintain a good meshing state with toothed pulleys.

[0031] The outer diameters of the core wire 3, φT in the belt thickness direction and φW in the belt width direction, are preferably 0.90 mm or more and 1.70 mm or less, and more preferably 1.00 mm or more and 1.60 mm or less. The outer diameter φT in the belt thickness direction and the outer diameter φW in the belt width direction may be the same or different.

[0032] The core wires 3 are arranged to form a spiral with a pitch in the belt width direction. For example, a core wire pair composed of an S-twisted core wire 3 and a Z-twisted core wire 3 may be arranged to form a spiral with a pitch in the belt width direction.

[0033] The core wires 3 are arranged so as to extend in parallel at intervals in the belt width direction. A plurality of core wires 3 appear to be arranged side by side in the belt width direction. In this case, the number of core wires 3 per 10 mm of belt width is preferably 5 / 10 mm or more and 20 / 10 mm or less. A toothed belt 1 with core wires 3 arranged in this manner is suitable for ensuring excellent durability and excellent tension retention in high load transmission. From the same perspective, the number of core wires 3 is more preferably 6 / 10 mm or more and 10 / 10 mm or less. The dimension of the gap between adjacent core wires 3 is, for example, not less than 0.1 mm and not more than 0.7 mm.

[0034] The cords 3 may be subjected to an adhesive treatment to increase the adhesive strength between the cords 3 and the belt body 2. Examples of the adhesive treatment include an RFL treatment in which the substrate is immersed in an RFL aqueous solution followed by heating, a rubber cement treatment in which the substrate is immersed in rubber cement followed by drying, etc. Either one of these adhesive treatments may be performed, or both may be performed. Prior to the bonding treatment, the core wire 3 may be subjected to a surface treatment, such as immersion in an epoxy solution or an isocyanate solution followed by heating. These adhesive treatments and surface treatments are carried out before winding the core wire around a mold in the method of manufacturing a toothed belt, which will be described later.

[0035] (reinforced fabric) As described above, the reinforcing cloth 4 covers the surface of the toothed portion 22. The reinforcing cloth 4 forms the inner peripheral surface of the toothed belt 1. The inner peripheral surface of the toothed belt 1 includes the reinforcing cloth 4. The reinforcing fabric 4 is a woven fabric. Examples of fibers that form the reinforcing fabric 4 include polyamide fibers (nylon fibers), polyester fibers, aramid fibers, polyparaphenylenebenzobisoxazole (PBO) fibers, and cotton. The reinforcing fabric 4 is preferably, for example, a woven fabric of polyamide fiber. The thickness of the reinforcing fabric 4 is, for example, not less than 0.5 mm and not more than 2.0 mm.

[0036] 5 shows an example of a woven fabric 41 used as the reinforcing fabric 4. The woven fabric 41 includes warp threads 42 and weft threads 43. The reinforcing fabric 4 is a woven fabric 41 including warp threads 42 and weft threads 43. In Figure 5, the direction indicated by the double arrow P is the vertical direction of the fabric 41. The vertical direction P of the fabric 41 is the direction in which the warp threads 42 extend. The direction indicated by the double arrow Q is the horizontal direction of the fabric 41. The horizontal direction Q of the fabric 41 is the direction in which the weft threads 43 extend. The direction indicated by the double arrow R is the thickness direction of the fabric 41.

[0037] 5, in the woven fabric 41, a large number of warp threads 42 are aligned in the horizontal direction Q of the woven fabric 41, and a large number of weft threads 43 are aligned in the vertical direction P of the woven fabric 41. In the woven fabric 41, a large number of warp threads 42 extending in the vertical direction P are aligned in the horizontal direction Q of the woven fabric 41. A large number of weft threads 43 extending in a meandering manner in the horizontal direction Q of the woven fabric 41 are aligned in the vertical direction P of the woven fabric 41. As will be described later, the fabric 41 is set in the toothed belt 1 with its lateral direction Q coinciding with the belt circumferential direction. This forms the reinforcing fabric 4. Therefore, in the toothed belt 1, the warp threads 42 are aligned in the belt circumferential direction, and the weft threads 43 are aligned in the belt width direction. In the toothed belt 1, the warp threads 42 extend in the belt width direction, and the weft threads 43 extend in the belt circumferential direction.

[0038] The number of warp threads 42 arranged in the horizontal direction Q of the woven fabric 41 is expressed as the thread density of the warp threads 42 (hereinafter referred to as warp thread density) expressed as the number of warp threads 42 per 5 cm length. The number of weft threads 43 arranged in the vertical direction P of the woven fabric 41 is expressed as the thread density of the weft threads 43 (hereinafter referred to as weft thread density) expressed as the number of weft threads 43 per 5 cm length. The warp density of the fabric 41 used in this toothed belt 1 is, for example, 50 threads / 5 cm or more and 150 threads / 5 cm or less, and the weft density is, for example, 20 threads / 5 cm or more and 250 threads / 5 cm or less.

[0039] The warp threads 42 and weft threads 43 each use a cord made of the above-mentioned fibers. FIG. 6 shows an example of a cord C for the weft yarn 43. The cord C shown in FIG. 6 includes three single yarns S. Each single yarn S includes a plurality of filaments F. The cord C includes a plurality of filaments F. The number of filaments F included in the cord C is set appropriately depending on the specifications of the toothed belt 1. A single yarn S is formed by twisting together multiple filaments F. Three single yarns S are further twisted together to form a cord C shown in Figure 6. The cord C may be formed from one single yarn S. The cord C may be formed from two single yarns S twisted together. The cord C may be formed from four or more single yarns S twisted together. The cord C may also be formed from twisting together single yarns S made of the same fiber but with different thicknesses. Although not shown, a plurality of single yarns S may be twisted together to form a strand, and the strands may then be further twisted together to form the cord C. In this case, the number of single yarns S contained in the cord C is expressed as the product of the number of single yarns S contained in the strand and the number of strands contained in the cord C. In either case, the cord C is formed by twisting together a plurality of filaments F. The weft yarn 43 is the cord C formed by twisting together a plurality of filaments F.

[0040] Although not shown, the cord for the warp threads 42 is configured in the same manner as the cord C for the weft threads 43. The warp threads 42 are cords C in which a plurality of filaments F are twisted together. That is, each of the warp threads 42 and the weft threads 43 is a cord C made by twisting together a plurality of filaments F.

[0041] The yarn fineness is used as an index of the thickness of the yarn. In this toothed belt 1, the yarn fineness is expressed as the product of the fineness of the single yarn S constituting the yarn and the number of single yarns S contained in this yarn. The fineness of the warp yarns 42 constituting the fabric 41 used in this toothed belt 1 is, for example, 40 dtex or more and 1500 dtex or less, and the fineness of the weft yarns 43 is, for example, 40 dtex or more and 2500 dtex or less.

[0042] In the present invention, when the specifications of the fabric 41 constituting the reinforcing fabric 4 are clear, the yarn density and fineness of the warp and weft yarns of the fabric prepared for manufacturing the toothed belt 1 are used as the yarn density and fineness of the warp and weft yarns 42 and 43 of the fabric 41. If the specifications of the woven fabric 41 constituting the reinforcing fabric 4 are not clear, the thread density and fineness of the warp threads 42 and weft threads 43 of the woven fabric 41 are specified based on the thread density and fineness of the warp threads and weft threads of the reinforcing fabric 4 of the toothed belt 1. Specifically, (1) Reinforcing fabric 4 is sampled from toothed belt 1. (2) The yarn density of the warp and weft of the sampled reinforcing fabric 4 is obtained in accordance with the method described in [8.6 Density] of JIS L1096. (3) The warp and weft yarns are disassembled, and the number of single yarns S contained in each of the warp and weft yarns and the twist structure of the warp and weft yarns are obtained. (4) The fineness of the warp and weft single yarns S is obtained in accordance with the method described in [8.3 Fineness] of JIS L1013. (5) The fineness of the warp and weft yarns is obtained based on the number of single yarns S obtained in (3) and the fineness of the single yarns S obtained in (4). The cord structure of the warp and weft yarns is determined based on the twist structure obtained in (3). (6) Based on the measured values ​​of the warp and weft thread densities obtained in (2) and the structure of the warp and weft cords identified in (5), the woven fabric used as the reinforcing fabric 4 is identified. The thread density and fineness of the warp and weft threads of the identified woven fabric are identified as the thread density and fineness of the warp threads 42 and weft threads 43 of the woven fabric 41.

[0043] The reinforcing fabric 4 may be subjected to an adhesive treatment to enhance adhesive strength with the belt body 2. Examples of the adhesion treatment include an RFL treatment in which the belt is immersed in an RFL aqueous solution and then heated, a soaking treatment in which the belt is immersed in a low-viscosity rubber cement and then dried, and a coating treatment in which a high-viscosity rubber cement is applied to the surface of the belt body side and then dried. Only one of these treatments may be performed, or two or more of them may be performed. Before the adhesive treatment, the reinforcing fabric 4 may be subjected to a surface treatment in which the fabric is immersed in an epoxy solution or an isocyanate solution and then heated. These adhesive treatments and surface treatments are carried out before the reinforcing fabric 4 is wound around a mold in the manufacturing method of the toothed belt, which will be described later.

[0044] 2 is composed of a belt body 2, a core wire 3, and a reinforcing cloth 4. As described above, the toothed belt 1 has a back portion 11 and a plurality of belt teeth 12. The back portion 11 of the toothed belt 1 where the belt teeth 12 are provided is composed of a base portion 21 and a core wire 3. The back portion 11 where the belt teeth 12 are not provided is composed of the base portion 21, the core wire 3, and the reinforcing fabric 4. In the toothed belt 1, the belt teeth 12 are composed of a tooth portion 22 and a reinforcing cloth 4.

[0045] As mentioned above, with the electrification of transportation, it is expected that the load on toothed belts used as power transmission means will increase. Increasing the strength of reinforcing fabric through post-processing such as dipping or sizing may not be enough to withstand the expected high loads. The reinforcing fabric of the toothed belt comes into contact with pulleys (not shown), which causes wear to the reinforcing fabric. In particular, in a dusty environment, the dust damages the reinforcing fabric, making it prone to wear. When wear exposes the warp threads, they fall off, leaving some of the weft threads free. This makes the weft threads more susceptible to breakage, increasing the possibility that wear will extend to the core wire. Therefore, the inventors focused on the reinforcing fabric that comes into contact with the pulleys and conducted extensive research into means for effectively increasing the strength of the reinforcing fabric from the perspective of improving the dust abrasion resistance of toothed belts. As a result, they discovered that the dust abrasion resistance of toothed belts can be dramatically improved by controlling the unit fiber amount, which is expressed as the product of the yarn fineness and yarn density, and they developed woven fabric 41 for reinforcing fabric 4, which is the key technology of the present invention. This woven fabric 41 will be described in detail below.

[0046] First, when the product of the fineness of the warp yarn 42 of the woven fabric 41 and the thread density of the warp yarn 42 in this woven fabric 41 is defined as the unit fiber amount AR of the warp yarn 42, and the product of the fineness of the weft yarn 43 of this woven fabric 41 and the thread density of the weft yarn 43 in this woven fabric 41 is defined as the unit fiber amount EF of the weft yarn 43, the ratio (EF / AR) of the unit fiber amount EF of the weft yarn 43 to the unit fiber amount AR of the warp yarn 42 is 2.0 or more. This effectively prevents exposure of the warp yarns 42 in the reinforcing fabric 4, which is subject to wear due to contact with the pulleys. Because exposure of the warp yarns 42 is prevented, the reinforcing fabric 4 can stably maintain its shape as a woven fabric 41. Even when this toothed belt 1 is used in an atmosphere where dust is present, wear that reaches the core wires 3 is unlikely to occur. This toothed belt 1 can improve dust abrasion resistance. From this perspective, the ratio (EF / AR) is preferably 2.5 or more, more preferably 3.0 or more, and even more preferably 4.5 or more.

[0047] Furthermore, the unit fiber weight EF of the weft yarn 43 is 80,000 dtex / 5 cm or more and 400,000 dtex / 5 cm or less. Since the unit fiber weight EF of the weft yarns 43 is 80,000 dtex / 5 cm or more, exposure of the warp yarns 42 due to wear of the reinforcing fabric 4 is more effectively suppressed. This toothed belt 1 can improve the dust wear resistance. From this viewpoint, the unit fiber weight EF of the weft yarns 43 is preferably 100,000 dtex / 5 cm or more, more preferably 120,000 dtex / 5 cm or more, and even more preferably 135,000 dtex / 5 cm or more. From the viewpoint of improving dust abrasion resistance, the larger the unit fiber weight EF of the weft yarn 43, the better. If the unit fiber weight EF of the weft yarn 43 exceeds 400,000 tex / 5cm, the limit of the yarn density of the woven fabric is exceeded, making it difficult to produce the woven fabric 41. From this viewpoint, the unit fiber weight EF of the weft yarn 43 is 400,000 dtex / 5cm or less. From the viewpoint of enabling the reinforcing fabric 4 to contribute to improving dust abrasion resistance, the unit fiber weight EF of the weft yarn 43 is preferably 300,000 dtex / 5cm or less, more preferably 200,000 dtex / 5cm or less, and even more preferably 155,000 dtex / 5cm or less.

[0048] The unit fiber amount AR of the warp yarns 42 is 15,000 dtex / 5 cm or more and 65,000 dtex / 5 cm or less. Since the unit fiber amount AR of the warp yarns 42 is 65,000 dtex / 5 cm or less, exposure of the warp yarns 42 due to wear of the reinforcing fabric 4 is more effectively suppressed. This toothed belt 1 can improve the dust wear resistance. From this viewpoint, the unit fiber amount AR of the warp yarns 42 is preferably 50,000 dtex / 5 cm or less, more preferably 40,000 dtex / 5 cm or less, and even more preferably 35,000 dtex / 5 cm or less. If the unit fiber amount AR of the warp yarns 42 is less than 15,000 dtex / 5 cm, the woven fabric 41 cannot stably maintain its shape. From the viewpoint of stably maintaining the shape, the unit fiber amount AR of the warp yarns 42 is 15,000 dtex / 5 cm or more. From the viewpoint of the reinforcing fabric 4 contributing to improving dust abrasion resistance, the unit fiber amount AR of the warp yarns 42 is preferably 20,000 dtex / 5 cm or more, and more preferably 25,000 dtex / 5 cm or more.

[0049] In this toothed belt 1, the ratio (EF / AR) of the unit fiber weight EF of the weft yarn 43 to the unit fiber weight AR of the warp yarn 42 is 2.0 or more, the unit fiber weight EF of the weft yarn 43 is 80,000 dtex / 5 cm or more and 400,000 dtex / 5 cm or less, and the unit fiber weight AR of the warp yarn 42 is 15,000 dtex / 5 cm or more and 65,000 dtex / 5 cm or less. This toothed belt 1 can achieve improved dust abrasion resistance.

[0050] In this toothed belt 1, the fineness of the warp yarns 42 is smaller than that of the weft yarns 43. Therefore, exposure of the warp yarns 42 due to wear of the reinforcing fabric 4 is more effectively suppressed. Moreover, the warp yarns 42 having a small fineness can contribute to the construction of a thin reinforcing fabric 4. This toothed belt 1 can further improve the dust wear resistance. From this perspective, it is preferable that the fineness of the warp yarns 42 is smaller than that of the weft yarns 43. In particular, in a woven fabric 41 in which the fineness of the warp yarns 42 is smaller than that of the weft yarns 43, the ratio (EF / AR) of the unit fiber weight EF of the weft yarns 43 to the unit fiber weight AR of the warp yarns 42 is 2.0 or more, the unit fiber weight EF of the weft yarns 43 is 80,000 dtex / 5 cm or more and 400,000 dtex / 5 cm or less, and the unit fiber weight AR of the warp yarns 42 is 15,000 dtex / 5 cm or more and 65,000 dtex / 5 cm or less can further improve the dust abrasion resistance of the toothed belt 1. In this case, it is more preferable that the ratio of the fineness of the warp yarns 42 to the fineness of the weft yarns 43 is 0.15 or more and 0.70 or less.

[0051] The fineness of the filaments F contained in the weft yarns 43 is preferably 4.5 dtex or less. This allows the weft yarns 43 to be densely packed in the reinforcing fabric 4. The weft yarns 43 are laid out without any gaps in the reinforcing fabric 4. This more effectively prevents the warp yarns 42 from being exposed due to wear of the reinforcing fabric 4. This toothed belt 1 can improve the dust wear resistance. From this perspective, the fineness of the filaments F contained in the weft yarns 43 is more preferably 3.5 dtex or less. The fineness of the filaments F contained in the weft yarn 43 is obtained by dividing the fineness of the single yarn S by the number of filaments F that constitute this single yarn S. When multiple weft yarns 43 are used in the reinforcing fabric 4, the fineness of the filaments F contained in the weft yarn 43 in that reinforcing fabric 4 (hereinafter also referred to as the fineness of the weft filaments F) is expressed.

[0052] As described above, the weft yarns 43 are densely packed in the reinforcing fabric 4 of the toothed belt 1. The gaps present in the reinforcing fabric 4 are quite small. This effectively prevents the warp yarns 42 from being exposed due to wear of the reinforcing fabric 4. This toothed belt 1 can improve its dust wear resistance. From this perspective, it is preferable that the reinforcing fabric 4 is made of a woven fabric 41 with low air permeability. Specifically, the air permeability of the woven fabric 41 is 30 cm 3 / (cm 2 s) or less, and 20 cm 3 / (cm 2 s) or less is more preferable, and 12 cm 3 / (cm 2 From the viewpoint of obtaining a woven fabric 41 that can be used as the reinforcing fabric 4, the air permeability of the woven fabric 41 is preferably 1.5 cm s or less. 3 / (cm 2 It is preferable that the value is equal to or greater than s.

[0053] In the present invention, the air permeability of the woven fabric 41 is measured using a Frazier type tester in accordance with the air permeability test method specified in JIS L1096. As for the fabric used in the breathability test method, if the specifications of the fabric 41 constituting the reinforcing fabric 4 are known, the fabric prepared for manufacturing the toothed belt 1 is used. If the specifications of the fabric 41 constituting the reinforcing fabric 4 are unclear, the breathability of the fabric identified based on the measured values ​​of the thread density and fineness of the warp and weft threads of the reinforcing fabric 4 sampled from the toothed belt 1 is measured.

[0054] In the present invention, the mass per unit area of ​​the fabric (unit: g / m) relative to the thickness of the fabric (unit: mm) is 2 ) is the ratio of the filling degree (unit: μg / (mm 2 Also called woven fabric with a high density of yarns. A high density of yarns means that the gaps in the fabric are small and the yarns are packed tightly together. A low density of yarns means that the gaps in the fabric are large and the yarns are packed loosely together. When the specifications of the fabric 41 constituting the reinforcing fabric 4 are known, the thickness and mass per unit area of ​​the fabric used to obtain the filling degree are the thickness and mass per unit area of ​​the fabric prepared for manufacturing the toothed belt 1. When the specifications of the fabric 41 constituting the reinforcing fabric 4 are not known, the thickness and mass per unit area of ​​the fabric specified based on the measured values ​​of the yarn density and fineness of the warp and weft yarns of the reinforcing fabric 4 sampled from the toothed belt 1 are used.

[0055] As described above, the weft yarns 43 are densely packed in the reinforcing fabric 4 of the toothed belt 1. The gaps in the reinforcing fabric 4 are quite small. This effectively prevents the warp yarns 42 from being exposed due to wear of the reinforcing fabric 4. This toothed belt 1 can improve its dust wear resistance. From this perspective, it is preferable that the reinforcing fabric 4 is made of a woven fabric 41 with a high packing density. Specifically, when the packing density is the ratio of the mass per unit area of ​​the woven fabric 41 to the thickness of the woven fabric 41, the packing density of this woven fabric 41 is 300 μg / (mm 2 ·mm) or more, and 370 μg / (mm 2 From the viewpoint of obtaining a woven fabric 41 that can be used as the reinforcing fabric 4, the filling degree is preferably 500 μg / (mm 2 ·mm) or less, and 420 μg / (mm 2 It is more preferable that the thickness is 1 / 4 mm or less.

[0056] (Method of manufacturing toothed belt) The manufacturing method of the toothed belt 1 described above will be explained in the order of steps. 7 to 9 are diagrams for explaining the method of manufacturing the toothed belt 1. In Fig. 7 to 9, a mold 5 for forming the belt and a part of the belt (including the belt material) in the middle of being formed are shown.

[0057] In manufacturing the toothed belt 1, a belt forming mold 5 is used. The mold 5 is cylindrical. On the outer periphery of the mold 5, recesses 51 extending in the axial direction are engraved, and protrusions 52 extending in the axial direction are formed. The recesses 51 have a cross-sectional shape corresponding to the belt teeth 12, and are grooves extending in the axial direction (a direction perpendicular to the paper surface of FIG. 7). The recesses 51 are provided at regular intervals in the circumferential direction. The protrusions 52 are located between adjacent recesses 51.

[0058] (1) Preparation of materials Materials are prepared. The rubber components are masticated, and then rubber compounding agents are added and kneaded to obtain an uncrosslinked rubber composition. The uncrosslinked rubber composition is molded to produce an uncrosslinked rubber composition sheet 23. Calendar molding or the like can be used as a molding method for the uncrosslinked rubber composition sheet 23. The uncrosslinked rubber composition sheet 23 is a sheet-like molded product made of an uncrosslinked rubber composition.

[0059] Fabrics for the core wires 3 and the reinforcing cloth 4 are prepared, and if necessary, adhesive treatment is performed on each. The fabric is then formed into a cylindrical shape to form the reinforcing cloth 4. The fabric is formed into a cylindrical shape so that the horizontal direction of the fabric corresponds to the circumferential direction of the reinforcing cloth 4.

[0060] (2) Layering of materials The materials are layered in order. As shown in Figure 7, a cylindrically formed reinforcing cloth 4 is placed on the outer periphery of a mold 5. The core wire 3 is wound spirally around the reinforcing cloth 4. After the cord 3 is wound, an uncrosslinked rubber composition sheet 23 is further wound. A plurality of uncrosslinked rubber composition sheets 23 (two sheets in FIG. 7) are wound. In this way, an uncrosslinked slab 13 is formed on the outer periphery of the mold 5, in which the reinforcing fabric 4, cord 3, and uncrosslinked rubber composition sheet 23 are laminated. In laminating the materials, the uncrosslinked rubber composition sheet 23 is preferably laminated so that the grain direction corresponds to the circumferential direction of the belt.

[0061] (3) Cross-linking of uncross-linked slabs As shown in Figure 8, a rubber sleeve 6 is placed over the uncrosslinked slab 13 on the mold 5. The uncrosslinked slab 13 covered with the rubber sleeve 6 is placed inside a vulcanization can (not shown) together with the mold 5, and the vulcanization can is then sealed. High-temperature, high-pressure steam is filled into the vulcanization can. This state is maintained for a predetermined time. As a result, the uncrosslinked slab 13 is pressed against the mold 5 and heated. The uncrosslinked rubber composition sheet 23 flows within the cavity formed between the mold 5 and the rubber sleeve 6. The uncrosslinked rubber composition sheet 23 passes between the cords 3. The uncrosslinked rubber composition sheet 23 flows into each of the multiple recesses 51 formed in the mold 5 while pressing the reinforcing fabric 4. As the uncrosslinked rubber composition sheet 23 flows within the cavity in this manner, it becomes integrated with the cords 3 and the reinforcing fabric 4 and is crosslinked. As a result, a cylindrical belt slab 14 is formed, as shown in FIG. 9.

[0062] (4) Belt slab slices The pressure inside the vulcanizer is reduced to release the seal. The belt slab 14 formed between the mold 5 and the rubber sleeve 6 is demolded. The demolded belt slab 14 is cut into slices. Through these steps, the toothed belt 1 is obtained.

[0063] (Other embodiments) The belt teeth of the toothed belt according to the embodiment of the present invention are not limited to straight teeth, but may be helical teeth. [Example]

[0064] Hereinafter, the embodiments of the present invention will be described in more detail with reference to examples, but the embodiments of the present invention are not limited to the following examples.

[0065] (toothed belt) Toothed belts of Examples 1 to 6 and Comparative Examples 1 to 4 were manufactured having the same configuration as the toothed belt 1 shown in FIGS. 2 to 4, but with different woven fabrics for the reinforcing fabric 4. The tooth type is S8M (JIS B1857-1). The belt width Wb is 20 mm, and the belt circumference is 840 mm.

[0066] In the toothed belt, the rubber component of the belt body 2 is HNBR. In the toothed belt, the core wire 3 is a carbon core wire. The outer diameter φT of the carbon core wire in the belt thickness direction and the outer diameter φW of the carbon core wire in the belt thickness direction are both 1.10 mm.

[0067] The material of the fabric 41 for the reinforcing cloth 4 is nylon 66 fiber. The specifications of the fabric 41 used for evaluation are as shown in Table 1 below. Two types of weft yarns (weft yarn A: 78 dtex 35 f / 2 / 4, weft yarn B: 235 dtex 35 f / 2 / 3) are used for the weft of fabric E. Weft yarns A and B are arranged alternately, and each has a thread density of 75 threads / 5 cm. Therefore, the weft thread density of fabric E is 150 threads / 5 cm.

[0068] [Table 1]

[0069] (Dust abrasion resistance) 10 shows the pulley layout of the transmission system 7a used in the evaluation of dust wear resistance. The transmission system 7a was constructed using a toothed belt, a driving pulley 71a, and a driven pulley 72a, with the toothed belt wound around two pulley shafts including the driving pulley 71a and the driven pulley 72a. In this transmission system 7a, the SW (set weight) was fixed so that the belt tension was 500 N. The speed ratio was 1.0. The number of pulley teeth of the drive pulley 71a and the driven pulley 72a was 24. After measuring the initial thickness Sbb of the toothed belt's tooth bottom, the toothed belt was run with the drive pulley 71a at a rotation speed of 2000 rpm. 100 g of No. 4 silica sand was added to the inlet side of the drive pulley 71a every hour. The tooth bottom thickness Sba was measured with a vernier caliper every five hours, and the wear loss, expressed as the difference between the initial thickness Sbb and the thickness Sba (Sbb - Sba), was obtained. The test time was 15 hours (411,429 cycles). A graph was created with the number of cycles on the horizontal axis and the amount of wear on the vertical axis, and the rate of change in the amount of wear (unit: mm / 10 7 The results are shown in Tables 2 and 3 below. The closer the value is to 0 (zero), the better the dust abrasion resistance is.

[0070] [Table 2]

[0071] [Table 3]

[0072] As shown in Tables 2 and 3, it is clear that the toothed belt according to the embodiment of the present invention can achieve improved dust wear resistance. [Explanation of symbols]

[0073] 1 Toothed belt 11 Back 12 belt teeth 13 Unbridged slab 14 Belt Slab 2 Belt body 21 Base 22 Tooth 23 Uncrosslinked rubber composition sheet 3 core wire 4 Reinforcement fabric 41 Textiles 42 Warp threads 43 Weft 5. Mold 51 recess 52 Convex part 6 Rubber sleeve 7, 7a Transmission system 71, 71a Drive pulley 72, 71b Driven pulley 73 Prime Mover 74 Pulley groove 75 drive shaft 76 Driven axis

Claims

1. A toothed belt used in a transmission system having a transmission capacity of 0.75 kW or more and 90 kW or less, The belt has an endless belt-like back portion and belt teeth provided on an inner circumferential side of the back portion, The belt teeth include a tooth portion made of a cross-linked rubber composition and a reinforcing cloth covering a surface of the tooth portion, the reinforcing fabric is a woven fabric including warp yarns and weft yarns, Each of the warp yarns and the weft yarns is a cord formed by twisting a plurality of filaments together, The warp yarns are arranged in the circumferential direction of the toothed belt, The weft yarns are aligned in the width direction of the toothed belt, When the product of the warp fineness and the yarn density of the warp yarn in the woven fabric is defined as the unit fiber amount of the warp yarn, and the product of the weft fineness and the yarn density of the weft yarn in the woven fabric is defined as the unit fiber amount of the weft yarn, The ratio of the unit fiber amount of the weft to the unit fiber amount of the warp is 2.0 or more, The unit fiber weight of the weft yarn is 80,000 dtex / 5 cm or more and 400,000 dtex / 5 cm or less, The unit fiber weight of the warp yarn is 15,000 dtex / 5 cm or more and 65,000 dtex / 5 cm or less. Toothed belt.

2. The fineness of each of the filaments contained in the weft yarn is 4.5 dtex or less.

2. The toothed belt according to claim 1.

3. The air permeability of the fabric is 30 cm, which is obtained in accordance with the air permeability test method specified in JIS L1096. ３ / (cm ２ s) is less than or equal to 3. The toothed belt according to claim 1 or 2.

4. When the ratio of the mass per unit area of ​​the woven fabric to the thickness of the woven fabric is defined as the filling degree, The filling degree of the fabric is 300 μg / (mm ２ ・mm) or more 500μg / (mm ２ mm) or less, 4. The toothed belt according to claim 3.

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