Toothed belt and transmission system

Abstract

This toothed belt includes: a back part in which a core wire is embedded; and belt teeth which are provided to the inner-circumferential side of the back part and which engage with a pulley groove of a toothed pulley. The tooth tip compressibility Y (%) of the belt teeth, as calculated using a formula (1), is －２≦Ｙ≦１０. The tooth width-direction porosity X (%) of the belt teeth, as calculated using a formula (2), is －３０≦Ｘ≦０.　Formula 1: Ｙ（％）＝（（belt tooth-height Ｈｂ－pulley tooth-groove bottom depth Ｈｐ）／belt tooth-height Ｈｂ）×１００. Formula 2: Ｘ（％）＝（（pulley tooth width γ－belt tooth width β）／pulley tooth width γ）×１００.

Description

Technical Field

[0001] The present invention relates to a toothed belt and a transmission system. This application claims priority based on Japanese Application No. 2023-033896 filed on March 6, 2023, and incorporates all the descriptions described in the above Japanese application.

Background Art

[0002] As a system for transmitting power, a transmission system including a toothed belt and a toothed pulley is known. A transmission system including a toothed belt can perform stable synchronous transmission with low tension. Therefore, it can be suitably used in general industrial machines such as machine tools and textile machines, and electric power steering devices. On the other hand, in the above-described transmission system, there is a problem that the noise generated during driving (running noise) becomes a nuisance.

[0003] So far, several methods for reducing the noise when a toothed belt and a toothed pulley mesh have been proposed. For example, in Patent Document 1, as a toothed belt capable of reducing noise, a toothed belt including a back portion, a plurality of husk teeth arranged in the belt length direction, a core wire made of fiber and spirally embedded in the back portion along the belt length direction, the husk teeth having a tooth cloth provided on the inner peripheral side, the angle formed by the direction in which the tooth ribs of the husk teeth extend and the belt width direction being 8 degrees or more and 16 degrees or less, the fiber constituting the core wire being composed of a single-twisted yarn, the twist direction of the yarn being inclined in the direction opposite to the direction in which the tooth ribs of the husk teeth extend with respect to the belt width direction, and the winding direction of the core wire being inclined in the same direction as the direction in which the tooth ribs of the husk teeth extend with respect to the belt width direction, has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a transmission system composed of a toothed belt and a toothed pulley, reduction of running noise (noise suppression) is required, and this requirement never disappears. Particularly in applications where quietness is required, suppressing noise becomes important.

Means for Solving the Problems

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a transmission system with suppressed noise.

[0007] (1) The toothed belt of the present invention is a toothed belt having a back portion in which a core wire is embedded, and belt teeth provided on the inner peripheral side of the back portion and meshing with pulley grooves of a toothed pulley, wherein the tooth tip compression rate Y (%) of the belt teeth calculated by formula (1) is -2 ≦ Y ≦ 10, and the porosity X (%) in the tooth width direction of the belt teeth calculated by formula (2) is -30 ≦ X ≦ 0. Y (%) = ((tooth height Hb of the belt - bottom depth Hp of the pulley tooth groove) / tooth height Hb of the belt) × 100 ··· (1) X (%) = ((pulley tooth width γ - belt tooth width β) / pulley tooth width γ) × 100 ··· (2)

[0008] Since each of the tooth tip compression rate Y of the belt teeth and the porosity X in the tooth width direction of the belt teeth is within a predetermined range, this toothed belt has a small running noise. This toothed belt has suppressed noise.

[0009] (2) The toothed belt of (1) above is preferably such that the tooth tip compression rate Y (%) is 0 ≦ Y ≦ 8 and the porosity X (%) is -20 ≦ X ≦ -10. In this case, the noise can be made smaller.

[0010] (3) In the toothed belt of the above (1) or (2), it is preferable that the core wire is a carbon core wire or a steel core wire. In this case, the tension maintenance property of the toothed belt is improved. Also, the belt length of the toothed belt is less likely to change. Therefore, it can be suitably used for high-load transmission applications.

[0011] (4) In the toothed belt of any one of the above (1) to (3), the belt teeth are sawtooth teeth, and it is preferable that the angle of the tooth ribs of the sawtooth teeth with respect to the belt width direction is 3 degrees or more and 16 degrees or less. In this case, the impact sound when the belt teeth mesh with the pulley groove can be reduced. Therefore, the noise is further suppressed.

[0012] (5) In the toothed belt of the above (4), it is preferable that the ratio B of the thickness Sb of the back portion to the tooth height Hb of the sawtooth teeth is 1.75 or more and 2.40 or less. In this case, the noise of the toothed belt is further suppressed. In addition, since the flexural fatigue resistance of the toothed belt is ensured, cracks are less likely to occur on the back surface of the toothed belt.

[0013] (6) The transmission system of the present invention is a transmission system having a toothed belt and a toothed pulley that meshes with the toothed belt, wherein the toothed belt is the toothed belt according to any one of (1) to (5). Since this transmission system includes the toothed belt according to any one of (1) to (5) as the toothed belt, the running sound is small. This transmission system has suppressed noise.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a toothed belt capable of suppressing noise. Also, it is possible to provide a transmission system with suppressed noise, which includes this toothed belt.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to these embodiments.

[0017] (Transmission system) FIG. 1 is a side view schematically showing a transmission system 1 according to an embodiment of the present invention. The transmission system 1 is suitably used for general industrial machines such as machine tools, printing machines, textile machines, injection molding machines, etc., and electric power steering devices. As shown in FIG. 1, the transmission system 1 includes a driving pulley 22, a driven pulley 24, and a toothed belt 10. The drive pulley 22 and the driven pulley 24 each have a plurality of pulley grooves 21 formed therein. The toothed belt 10 is provided with a plurality of belt teeth 12 (see FIG. 2) that engage with the pulley grooves 21 on the inner peripheral side. The toothed belt 10 has a core wire 13 embedded therein. The toothed belt 10 is looped around the drive pulley 22 and the driven pulley 24.

[0018] Both the drive pulley 22 and the driven pulley 24 are provided with pulley grooves 21 that engage with the belt teeth 12 of the toothed belt 10 at a predetermined pitch and at equal intervals along the outer periphery. The pulley grooves 21 of the drive pulley 22 and the pulley grooves 21 of the driven pulley 24 have the same shape. Hereinafter, both the drive pulley 22 and the driven pulley 24 are collectively referred to simply as the toothed pulley 20.

[0019] The transmission system 1 transmits the power from the drive source to the driven side. In the transmission system 1, the belt running speed is, for example, 0 rpm or more and 6000 rpm or less. In the transmission system 1, the transmission capacity is, for example, 0.1 KW or more and 10 KW or less.

[0020] (Toothed Belt) FIG. 2 is a perspective view showing a part of the toothed belt 10 according to an embodiment of the present invention. This toothed belt 10 constitutes the transmission system 1. FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2. FIG. 4 is an end view taken along line B-B of FIG. 2. Although only a part of the toothed belt 10 is shown in FIG. 2, the toothed belt 10 is an endless meshing transmission belt. Also, the toothed belt 10 is a single-sided toothed belt.

[0021] The belt length of the toothed belt 10 (the belt length on the belt pitch line BL) is, for example, 100 mm or more and 400 mm or less. The belt width Wb of the toothed belt 10 is, for example, 4 mm or more and 30 mm or less. The belt thickness Tb of the toothed belt 10 is, for example, 1.1 mm or more and 3.0 mm or less. The belt thickness Tb of the toothed belt 10 is the thickness of the thickest part of the toothed belt 10. The dimensions of the toothed belt according to the embodiment of the present invention are not necessarily limited to this range.

[0022] The toothed belt 10 has a plurality of belt teeth 12 on its inner peripheral surface. The pitch Pb of the belt teeth 12 is, for example, 0.50 mm or more and 3.0 mm or less. The tooth profile of the belt teeth 12 is, for example, an arc tooth profile.

[0023] (Toothed pulley) The toothed pulley 20 is made of, for example, stainless steel. The toothed pulley 20 is provided with pulley grooves 21 that mesh with the belt teeth 12 of the toothed belt 10 at a predetermined pitch along its outer circumference. The outer diameter of the toothed pulley 20 is, for example, 8 mm or more and 144 mm or less. The number of teeth of the toothed pulley 20 is, for example, 10 teeth or more and 150 teeth or less. The tooth profile of the pulley grooves 21 is, for example, an arc tooth profile. The toothed pulley 20 may be provided with a flange, for example.

[0024] (Relationship between toothed belt and toothed pulley) The belt teeth 12 of the toothed belt 10 are configured to mesh smoothly with the pulley grooves 21. In the toothed belt 10, the tip compression rate Y (%) of the belt teeth 12 and the porosity X (%) in the tooth width direction of the belt teeth 12 are within a specific range.

[0025] The tip compression rate Y (%) of the belt teeth 12 is an index indicating the compression state of the tips of the belt teeth 12 when the belt teeth 12 mesh with the pulley grooves 21. The tip compression rate Y (%) of the belt teeth 12 is calculated by the following formula (1). Y (%) = ((belt tooth height Hb - pulley tooth groove bottom depth Hp) / belt tooth height Hb) × 100 ··· (1)

[0026] The belt tooth height Hb in formula (1) is the distance between the apex of the tooth tip and the tooth bottom line in the cross section along the length direction of the toothed belt 10 (refer to Hb in FIG. 4). The tooth height Hb of the toothed belt 10 is, for example, 0.50 mm or more and 2.0 mm or less.

[0027] The pulley tooth groove bottom depth Hp in Equation (1) is defined as the radial distance between the tooth tip circle Cp and the tooth groove bottom circle Cq in a cross-section along the circumferential direction of the toothed pulley 20 (see Figure 5). The pulley tooth groove bottom depth Hp of the toothed pulley 20 is, for example, 0.40 mm or more and 2.20 mm or less.

[0028] The porosity X (%) in the tooth width direction of the belt teeth 12 is an index indicating the amount of backlash when the belt teeth 12 mesh with the pulley groove 21. The porosity X (%) in the tooth width direction of the belt teeth 12 is calculated by the following Equation (2). X (%) = ((pulley tooth width γ - belt tooth width β) / pulley tooth width γ) × 100 ··· (2)

[0029] The belt tooth width β in Equation (2) is the distance between P1 and P2 when the intersection points of the virtual straight line VL1, which is perpendicular to the direction of the belt tooth height Hb and passes through the portion at half the height of the belt tooth height Hb, and the pressure surface of the belt teeth 12, are set as P1 and P2 in a cross-section along the length direction of the toothed belt 10. The belt tooth width β is, for example, 0.50 mm or more and 3.00 mm or less.

[0030] The pulley tooth width γ in Equation (2) is the distance between P3 and P4 when the intersection points of the virtual circular arc VL2, which is a part of a concentric circle of the tooth tip circle Cp and passes through the portion at half the depth of the pulley tooth groove bottom depth Hp, and the tooth surface of the toothed pulley 20, are set as P3 and P4 in a cross-section along the circumferential direction of the toothed pulley 20. The pulley tooth width γ is, for example, 0.50 mm or more and 3.00 mm or less.

[0031] The toothed belt 10 has a tooth tip compression rate Y (%) of the belt teeth 12 such that -2 ≤ Y ≤ 10, and a porosity X (%) in the tooth width direction of the belt teeth 12 such that -30 ≤ X ≤ 0. In this embodiment, when the belt teeth 12 and the pulley groove 21 are engaged, the compression state of the tooth tips of the belt teeth 12 and the backlash amount are each set within a predetermined range. In this case, the toothed belt 10 can smoothly engage with the toothed pulley 20. Therefore, the toothed belt 10 can reduce noise.

[0032] This will be described in more detail. In the transmission system 1 of this embodiment, when the belt teeth 12 and the pulley groove 21 are engaged, the tooth tips of the belt teeth 12 and the pressure surfaces on both sides of the belt teeth 12 come into contact with the pulley groove 21. Therefore, the excitation sources are dispersed and the engagement becomes smooth. As a result, noise can be further reduced. Note that the excitation source means the location where the meshing impact sound or the string vibration sound, which is an element of noise, is generated. The contact location between the belt teeth 12 and the pulley groove 21 during meshing corresponds to the excitation source.

[0033] When the tooth tip compression ratio Y (%) is less than -2, the toothed belt 10 is in a state where the tooth tips do not contact the pulley groove 21 when engaging with the toothed pulley. In this case, the excitation source does not disperse and concentrates on the tooth bottom 15 of the toothed belt 10. Therefore, the noise of the transmission system 1 is not sufficiently suppressed. Also, when the tooth tip compression ratio Y (%) exceeds 10, the toothed belt 10 is in a state where the tooth bottom 15 floats when engaging with the toothed pulley. In this case as well, the excitation source does not disperse and concentrates on the tooth tips of the toothed belt 10. Therefore, the noise of the transmission system 1 is not sufficiently suppressed.

[0034] When the porosity X (%) is less than -30, the interference of the pressure surface becomes large when the toothed belt 10 engages with the toothed pulley 20. Therefore, the noise of the transmission system 1 is not sufficiently suppressed. Also, when the porosity X (%) is greater than 0, the toothed belt 10 is in a state where only one pressure surface of the belt teeth 12 contacts the pulley groove 21 when engaging with the toothed pulley. In this case, the excitation source concentrates on one pressure surface of the belt teeth 12. Therefore, the noise of the transmission system 1 is not sufficiently suppressed.

[0035] The toothed belt 10 preferably has a tooth tip compression ratio Y (%) satisfying 0 ≦ Y ≦ 8 and a porosity X (%) satisfying -20 ≦ X ≦ -10. In this case, in addition to the vibration sources being dispersed, the interference state between the pressure surface of the belt teeth 12 and the tooth surface of the toothed pulley can be optimized. In other words, while the two pressure surfaces of the belt teeth 12 are simultaneously in contact with the tooth surface of the toothed pulley, the two pressure surfaces of the belt teeth 12 are not overly compressed. As a result, the noise of the transmission system 1 is further reduced.

[0036] The toothed belt 10 of the present embodiment preferably satisfies the relationship of formula (3) between the tooth tip compression ratio Y (%) and the porosity X (%). Y ≧ -0.45X - 4 ··· (3) In this case, the toothed belt 10 is particularly unlikely to generate noise.

[0037] The belt teeth 12 of the toothed belt 10 are sawtooth teeth. The angle of the tooth flanks of the belt teeth 12 that are sawtooth teeth is preferably 3 degrees or more and 16 degrees or less. In this case, when the toothed belt 10 meshes with the toothed pulley 20, the belt teeth 12 gradually mesh with the pulley groove 21 from one side to the other side along the tooth flanks, so that the meshing impact noise can be reduced. Therefore, the noise of the transmission system 1 is suppressed. On the other hand, when the angle of the tooth flanks is less than 3 degrees, the impact noise during meshing does not decrease significantly. Also, when the angle of the tooth flanks exceeds 16 degrees, the toothed belt is likely to shift during running, and the shift of the toothed belt causes an increase in noise and deterioration of durability. The toothed pulley 20 that meshes with the toothed belt 10 also has sawtooth teeth.

[0038] In the toothed belt 10, the ratio B (Sb / Hb) of the thickness Sb of the back (see FIG. 4) to the tooth height Hb of the sawtooth teeth is preferably 1.75 or more and 2.40 or less. The toothed belt 10 is more likely to suppress noise when the thickness Sb of the back is thicker. This is because when the thickness Sb of the back is thicker, the vibration of the toothed belt, which is one of the causes of noise, can be attenuated. On the other hand, if the thickness Sb of the back is made too thick, the rigidity of the toothed belt 10 becomes too large, and when the toothed belt 10 is wound around the toothed pulley 20, the meshing with the pulley groove 21 deteriorates. In addition, the flexural fatigue resistance of the toothed belt decreases, and as a result, cracks are likely to occur on the back side or the like. In particular, cracks are likely to occur in a low-temperature environment. For these reasons, in the toothed belt 10, the above ratio B(Sb / Hb) is preferably within the above range.

[0039] (Configuration of toothed belt) As shown in FIG. 2, the toothed belt 10 includes a belt body 11, a core wire 13, and a reinforcing cloth 14. The belt body 11 has a belt shape and includes a base portion 11a having a rectangular cross-section perpendicular to the belt longitudinal direction, and a plurality of tooth portions 11b provided on the inner peripheral side of the base portion 11a. These plurality of tooth portions 11b are integrated with the base portion 11a. The plurality of tooth portions 11b are provided at equal intervals with a predetermined interval along the belt length direction. In the toothed belt 10, the reinforcing cloth 14 is provided so as to cover the inner peripheral surface of the tooth portion 11b. In the toothed belt 10, the belt teeth 12 are composed of the tooth portion 11b and the reinforcing cloth 14.

[0040] The belt body 11 is composed of, for example, a rubber composition in which an unvulcanized rubber composition containing a rubber component and a rubber compounding agent is cross-linked by heating and pressurization. Examples of the rubber component include ethylene-α-olefin elastomers such as hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), ethylene-propylene-diene rubber (EPDM), chlorosulfonated polyethylene rubber, styrene-butadiene rubber, and epichlorohydrin rubber. Among these, HNBR and EPDM are preferable.

[0041] As the above rubber compounding agent, conventionally known rubber compounding agents can be adopted. Examples of the rubber compounding agent include, for example, vulcanization accelerator aids, anti-aging agents, reinforcing materials, plasticizers, co-crosslinking agents, crosslinking agents, and the like. Examples of the above vulcanization accelerator aids include, for example, metal oxides, metal carbonates, fatty acids and their derivatives, and the like. Examples of the above metal oxides can include, for example, zinc oxide (zinc white), magnesium oxide, and the like. These vulcanization accelerator aids may be used alone or in combination of two or more. The content of the above vulcanization accelerator aid is, for example, 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0042] Examples of the above anti-aging agents include, for example, benzimidazole-based anti-aging agents, aromatic secondary amine-based anti-aging agents, amine-ketone-based anti-aging agents, and the like. These anti-aging agents may be used alone or in combination of two or more. The content of the above anti-aging agent is, for example, 1.5 parts by mass or more and 3.5 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0043] Examples of the above reinforcing materials include carbon black, silica, and the like. The above reinforcing materials may use carbon black and silica in combination. Examples of the above carbon black include, for example, channel black, furnace black, thermal black, acetylene black, and the like. Examples of the above furnace black can include, for example, SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, N-234, and the like. Examples of the above thermal black can include, for example, FT, MT, and the like. Carbon black may be used alone or in combination of two or more.

[0044] When using carbon black, its content is, for example, 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the rubber component. When using silica, its content is, for example, 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0045] Examples of the plasticizer include dialkyl sebacate, dialkyl phthalate, dialkyl adipate, and the like. Examples of the dialkyl sebacate include polyether ester, dioctyl sebacate (DOS), and the like. Examples of the dialkyl phthalate include dibutyl phthalate (DBP), dioctyl phthalate (DOP), and the like. Examples of the dialkyl adipate include dioctyl adipate (DOA), and the like. These plasticizers may be used alone or in combination of two or more. The content of the plasticizer is, for example, 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0046] Examples of the co-crosslinking agent include trimethylolpropane trimethacrylate, m-phenylene dimaleimide, zinc dimethacrylate, triallyl isocyanurate, and the like. 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 8 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0047] Examples of the crosslinking agent include sulfur, organic peroxides, and the like. Sulfur and organic peroxides may be used in combination. Of course, either one of them may be used alone. When sulfur and an organic peroxide are used in combination as the crosslinking agent, the total blending amount of the crosslinking agent is preferably, for example, 0.1 part by mass or more and 0.7 part by mass or less of sulfur and 1 part by mass or more and 5 parts by mass or less of the organic peroxide with respect to 100 parts by mass of the rubber component.

[0048] Examples of the core wire 13 include glass core wire, aramid core wire, carbon core wire, steel core wire, and the like. These core wires are preferably composed of twisted yarns. As the core wire 13, a carbon core wire and a steel core wire are preferable. Carbon and steel are materials with a high elastic modulus. Therefore, a toothed belt provided with a carbon core wire or a steel core wire is less likely to change in length when a load is applied, and the change in tooth pitch is small. Therefore, a toothed belt provided with a carbon core wire or a steel core wire is likely to maintain a good meshing state with the toothed pulley.

[0049] It is preferable that the outer diameter of the core wire 13 is such that the outer diameter φT in the belt thickness direction and the outer diameter φW in the belt width direction are each 0.15 mm or more and 0.80 mm or less. More preferable outer diameters φT and φW are 0.25 mm or more and 0.50 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.

[0050] The core wire 13 has a pitch in the belt width direction and is provided so as to form a helix. The core wire 13 may be composed of two S-twisted yarns and Z-twisted yarns, and they may be provided so as to form a double helix.

[0051] The core wires 13 are arranged at intervals in the belt width direction and extend in parallel. At this time, the number of core wires 13 per 10 mm of the belt width is preferably 10 wires / 10 mm or more and 26 wires / 10 mm or less. The toothed belt 10 in which the core wires 13 are arranged in this way is suitable for ensuring excellent durability in high-load transmission and excellent tension maintenance in high-load transmission. From the same viewpoint, a more preferable number of core wires 13 is 14 wires / 10 mm or more and 24 wires / 10 mm or less. Also, the dimension of the gap between adjacent core wires 13 is, for example, 0.1 mm or more and 0.7 mm or less.

[0052] The core wire 13 may be subjected to an adhesion treatment for enhancing the adhesion force with the belt body. Examples of the above-mentioned adhesion treatment include RFL treatment in which the material is immersed in an RFL aqueous solution and then heated, and rubber paste treatment in which the material is immersed in a rubber paste and then dried. Only one of these adhesion treatments may be performed, or both may be performed. Before the above-mentioned adhesion treatment, the core wire 13 may be subjected to a base treatment. Examples of the base treatment include a treatment in which the material is immersed in an epoxy solution or an isocyanate solution and then heated. These adhesion treatments and base treatments are performed before the core wire is wound around the mold in the manufacturing method of the toothed belt described later.

[0053] The reinforcing fabric 14 is composed of, for example, a woven fabric, a knitted fabric, a non-woven fabric, or the like. Examples of the fibers constituting the reinforcing fabric 14 include polyamide fibers (nylon fibers), polyester fibers, aramid fibers, polyparaphenylene benzobisoxazole (PBO) fibers, cotton, and the like. As the reinforcing fabric 14, for example, a woven fabric of polyamide fibers is preferable. The reinforcing fabric 14 preferably has elasticity. For example, a woven fabric using a wooly-processed weft yarn has elasticity. In this case, it is preferable that the direction in which the reinforcing fabric 14 easily stretches coincides with the belt length direction. The thickness of the reinforcing fabric 14 is, for example, 0.05 mm or more and 0.8 mm or less.

[0054] The reinforcing fabric 14 may be subjected to an adhesion treatment for enhancing the adhesion force with the belt body 11. Examples of the above-mentioned adhesion treatment include RFL treatment in which the material is immersed in an RFL aqueous solution and then heated, soaking treatment in which the material is immersed in a low-viscosity rubber paste and then dried, and coating treatment in which a high-viscosity rubber paste is applied to the surface on the belt body side and then dried. Only one type of these treatments may be performed, or two or more types may be performed. Before the adhesion treatment, the reinforcing fabric 14 may be subjected to a base treatment in which the material is immersed in an epoxy solution or an isocyanate solution and then heated. These adhesion treatments and primer treatments are carried out before the reinforcing fabric 14 is wound around the mold in the manufacturing method of the toothed belt described later.

[0055] (Manufacturing method of toothed belt) The manufacturing method of the toothed belt 10 will be described in the order of steps. Figs. 6 to 8 are diagrams for explaining the manufacturing method of the toothed belt 10. Only a part of the mold 31 for belt forming and the belt (including the belt material) are shown in Figs. 6 to 8.

[0056] In the manufacture of the toothed belt 10, a mold 30 for belt forming is used. The mold 30 is cylindrical. On the outer periphery of this mold 30, a concave portion 31 extending in the axial direction and a convex portion 32 extending in the axial direction are provided. The concave portion 31 has a cross-sectional shape corresponding to the belt teeth 12 and is a groove extending in the axial direction (a direction perpendicular to the plane of Fig. 6). The concave portions 31 are provided at a constant pitch with an interval in the circumferential direction. The convex portion 32 is provided between adjacent concave portions 31.

[0057] (1) Prepare the materials. The rubber component is kneaded, and further a rubber compounding agent is added and kneaded to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is molded to produce an unvulcanized rubber composition sheet 111. At this time, as a molding method of the unvulcanized rubber composition sheet 111, for example, calender molding or the like can be adopted.

[0058] Prepare the core wire 12 and the reinforcing fabric 14, and perform an adhesion treatment on each of them as necessary. Furthermore, the reinforcing fabric 14 is formed into a cylindrical shape.

[0059] (2) Stack the materials in order. As shown in Fig. 6, first, cover the outer peripheral surface of the mold 30 with the reinforcing fabric 14 formed into a cylindrical shape. Next, wind the core wire 13 spirally from above the reinforcing fabric 14. Furthermore, an unvulcanized rubber composition sheet 111 is wound thereon. A plurality of sheets (two sheets in FIG. 6) of the unvulcanized rubber composition sheet 111 are wound. Thereby, an unvulcanized slab 135 in which the reinforcing cloth 14, the core wire 13, and the unvulcanized rubber composition sheet 111 are laminated is formed on the mold 30. At this time, the unvulcanized rubber composition sheets 111 are preferably laminated such that the alignment direction corresponds to the belt length direction.

[0060] (3) As shown in FIG. 7, a rubber sleeve 34 is put on the unvulcanized slab 135 on the mold 31, and this is placed in a vulcanizing kettle and sealed. Next, the vulcanizing kettle is filled with high-temperature and high-pressure steam. Further, this state is maintained for a predetermined time. Thereby, the unvulcanized slab 135 is pressed and heated on the mold 31 side. At this time, the unvulcanized rubber composition sheet 111 passes between the core wires 13, flows into each of the plurality of recesses 32 of the mold 31 while pressing the reinforcing cloth 14, and is crosslinked. At the same time, the core wire 13 and the reinforcing cloth 14 are integrated. As a result, a cylindrical belt slab 35 is formed as shown in FIG. 8.

[0061] (4) The inside of the vulcanizing kettle is depressurized to release the seal. Subsequently, the belt slab 35 formed between the mold 31 and the rubber sleeve 34 is demolded. Thereafter, the demolded belt slab 35 is cut into rings. By going through such steps, the toothed belt 10 is obtained.

[0062] (Method for manufacturing a toothed pulley) The toothed pulley 20 can be manufactured by a conventionally known method. The toothed pulley 20 can be manufactured, for example, by producing a dedicated hob cutter according to the shape of the pulley groove of the toothed pulley, then performing tooth cutting on a metal material using this hob cutter, and further performing drilling, external shape processing, attachment of a flange, etc. as necessary.

[0063] (Other embodiments) The belt teeth of the toothed belt according to the embodiment of the present invention are not limited to sawtooth teeth and may be straight teeth. When the belt teeth of the toothed belt are straight teeth, as the toothed pulley, a pulley with straight teeth provided on the outer circumference is also selected.

Example

[0064] Hereinafter, the embodiments of the present invention will be described more specifically by way of examples, but the embodiments of the present invention are not limited to the following examples. Here, transmission systems with different combinations of toothed belts and toothed pulleys were prepared, and the levels of noise were evaluated.

[0065] (Toothed belt) A toothed belt (A) having the same configuration as the toothed belt 10 shown in FIGS. 2 to 4 was manufactured. The toothed belt (A) has a belt width Wb of 20 mm and a belt circumference of 330 mm in a state where the compression ratio is 0%. The toothed belt (A) is provided with herringbone teeth as belt teeth, with a tooth pitch P of 2 mm and a tooth rib angle of 5 degrees. The toothed belt (A) has a tooth height Hb of 0.76 mm, a total thickness Tb (Hb + Sb) of 2.1 mm, and a belt tooth width β of 1.044 mm. The dimensions of the belt teeth of the toothed belt (A) are such that in the dimensions of the belt teeth shown in FIG. 9, S is 1.3 mm, A is 0.172 mm, and r bb is 1.3 mm. In FIG. 9, "S" and "r bb " correspond to "S" and "r bb " described in Table 4 of JIS B 1857-1 (2015), and "A" corresponds to "a - Y" derived from Table 4 of JIS B 1857-1 (2015).

[0066] In the toothed belt (A), the belt body 11 has an EPDM rubber component. In the toothed belt (A), the core wire 13 is a carbon core wire. This carbon core wire has an outer diameter φT in the belt thickness direction and an outer diameter φW in the belt thickness direction, both of which are 0.33 mm. In the toothed belt (A), the reinforcing fabric 14 is a woven fabric. The warp and weft of this woven fabric are polyamide 66 fibers.

[0067] (Toothed pulley) Toothed pulleys (1) to (21) with different pulley groove shapes were manufactured. The toothed pulleys (1) to (21) were manufactured through a manufacturing process including hobbing using a dedicated hob cutter made according to the shape of the pulley groove of each pulley. The toothed pulleys (1) to (21) have a tip circle radius of 12.5 mm and 40 teeth (40T). Two toothed pulleys (1) to (21) were manufactured respectively. The width of the toothed pulleys (1) to (21) is 22 mm. The toothed pulleys (1) to (21) are made of stainless steel.

[0068] The dimensions of the pulley grooves of the toothed pulleys (1) to (21) are Hp, R1, A, and B in the dimensions of the pulley groove shown in Fig. 10. g Each of them has the dimensions shown in Table 1. In Fig. 10, "Hp", "R1", and "B" g " are equivalent to "H" g ", "R1", and "B" g described in Table 13 of JIS B 1857-2 (2015), and "A" is equivalent to "a - Y1" derived from Table 13 of JIS B 1857-2 (2015).

[0069] (Examples 1 to 12, Comparative Examples 1 to 9) Using the toothed belts, drive pulleys, and driven pulleys in the combinations shown in Tables 1 and 2, a toothed belt was wound around a two-shaft pulley having a drive pulley and a driven pulley to form a transmission system.

[0070] Fig. 11 shows the pulley layout of the transmission system. In this transmission system, the belt tension was fixed by SW (set weight) to be 100 N. The reduction ratio was set to 1.0.

[0071] (Evaluation) The above transmission system was run at a constant speed of 3000 rpm, and the sound generated at this time was confirmed by auditory sense and ranked in five levels. The results are shown in Tables 1, 2 and Figure 12. In this evaluation, it is shown that the smaller the ranking value, the quieter it is.

[0072]

Table 1

[0073]

Table 2

[0074] As shown in Tables 1, 2 and Figure 12, it was clarified that the noise of the transmission system was suppressed by the tooth tip compression ratio Y(%) of the belt teeth and the porosity X(%) in the tooth width direction of the belt teeth satisfying a predetermined relationship.

Explanation of Signs

[0075] 1, 40 Transmission system 10 Toothed belt 11 Belt body 11a Base part 11b Tooth part 12 Belt teeth 13 Core wire 14 Reinforcing cloth 15 Tooth bottom 20 Toothed pulley 21 Pulley groove 22, 41 Driving pulley 24, 42 Driven pulley 30 Mold 31 Concave part 32 Convex part 34 Rubber sleeve 35 Belt slab 111 Unvulcanized rubber composition sheet 135 Unvulcanized slab

Claims

1. A toothed belt having a back portion in which a core wire is embedded and belt teeth provided on an inner peripheral side of the back portion and meshing with a pulley groove of a toothed pulley, a tooth tip compression ratio Y (%) of the belt tooth calculated by the formula (1) is −2≦Y≦10, A toothed belt, wherein a void ratio X (%) in a tooth width direction of the belt tooth calculated by formula (2) satisfies −30≦X≦0. Y(%)=((belt tooth height Hb−pulley tooth groove bottom depth Hp) / belt tooth height Hb)×100 (1) X(%)=((pulley tooth width γ−belt tooth width β) / pulley tooth width γ)×100 (2)

2. 2. The toothed belt according to claim 1, wherein the tooth tip compression rate Y (%) is in the range of 0≦Y≦8, and the void ratio X (%) is in the range of −20≦X≦−10.

3. 2. The toothed belt according to claim 1, wherein the core wire is a carbon core wire or a steel core wire.

4. The belt teeth are helical teeth, 2. The toothed belt according to claim 1, wherein an angle of the tooth trace of the helical teeth with respect to the belt width direction is equal to or greater than 3 degrees and equal to or less than 16 degrees.

5. 5. The toothed belt according to claim 4, wherein a ratio B of a thickness Sb of said back portion to a tooth height Hb of said helical teeth is equal to or greater than 1.75 and equal to or less than 2.

40.

6. A transmission system having a toothed belt and a toothed pulley that meshes with the toothed belt, A power transmission system, wherein the toothed belt is a toothed belt according to any one of claims 1 to 5.

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