Toothed belts and transmission systems

Abstract

This toothed belt has a back part in which a core wire is buried, and belt teeth that are provided to the inner peripheral side of the back part and mesh with pulley grooves of a toothed pulley. In the toothed belt, a tooth tip compression ratio Y (%) of the belt teeth calculated by formula (1), and a porosity X (%) in the tooth width direction of the belt teeth calculated by formula (2) satisfy the relationship of formula (3).　(1): Y (%) = ((tooth height Hb of belt - tooth groove bottom depth Hp of pulley) / (tooth height Hb of belt) × 100; (2): X (%) = ((pulley tooth width γ - belt tooth width β) / pulley tooth width γ) × 100; (3): Y ≥ -0.45X - 4

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. 2023-033765 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 the toothed belt and the 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 embedded in the back portion in a spiral shape 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 twisting 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

[0005] In power transmission systems consisting of toothed belts and toothed pulleys, there is a constant need to reduce running noise (noise suppression). This requirement will never disappear. Noise suppression is especially important in applications where quiet operation is required. [Means for solving the problem]

[0006] This invention has been made in view of these circumstances, and aims to provide a noise-reducing transmission system.

[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 circumference side of the back portion that mesh with the pulley groove of a toothed pulley, The tooth tip compression ratio Y (%) of the belt teeth calculated by formula (1), and The void ratio X (%) in the tooth width direction of the belt teeth, calculated by equation (2), is a toothed belt that satisfies the relationship in equation (3). Y(%) = ((Belt tooth height Hb - Pulley tooth groove depth Hp) / Belt tooth height Hb) × 100 ... (1) X(%) = ((Pulley tooth width γ - Belt tooth width β) / Pulley tooth width γ) × 100 ... (2) Y≧-0.45X-4···(3)

[0008] This toothed belt produces less noise because the compression ratio Y of the belt teeth and the void ratio X in the width direction of the belt teeth satisfy a predetermined relationship. This toothed belt suppresses noise.

[0009] (2) The toothed belt in (1) above is It is preferable that the tooth tip compression ratio Y (%) is -2 ≤ Y ≤ 10 and the void ratio X (%) is -30 ≤ X ≤ 0. (3) The toothed belt described in (1) above is It is more preferable that the tooth tip compression ratio Y(%) is 0≦Y≦8 and the void ratio X(%) is -20≦X≦-10. In these cases, the noise can be reduced.

[0010] (4) In any of the toothed belts described in (1) to (3) above, it is preferable that the core wire is a carbon core wire or a steel core wire. In this case, the tension retention of the toothed belt is improved. Furthermore, the belt length of the toothed belt is less prone to change. Therefore, it can be suitably used in high-load transmission applications.

[0011] (5) In any of the toothed belts described in (1) to (4) above, The teeth of the belt described above are serrated teeth. Preferably, the angle of the tooth trace of the above-mentioned serrated teeth with respect to the belt width direction is 3 degrees or more and 16 degrees or less. In this case, the impact noise when the belt teeth and pulley grooves engage can be reduced. Therefore, noise is further suppressed.

[0012] (6) In the toothed belt described in (5) above, The ratio B of the thickness Sb of the back portion to the tooth height Hb of the above-mentioned hash tooth is preferably 1.75 or more and 2.40 or less. In this case, the toothed belt further reduces noise. In addition, the toothed belt's flexural fatigue resistance is ensured, making it less prone to cracking on the back of the toothed belt.

[0013] (7) The power transmission system of the present invention is a power transmission system comprising a toothed belt and a toothed pulley that meshes with the toothed belt, The toothed belt mentioned above is the toothed belt described in any of (1) to (6). This transmission system is equipped with a toothed belt as described in (1) to (6), resulting in low running noise. This transmission system has reduced noise. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a toothed belt capable of suppressing noise. Further, it is possible to provide a transmission system provided with this toothed belt and having suppressed noise.

Brief Description of the Drawings

[0015] [Figure 1] It is a side view schematically showing a transmission system. [Figure 2] It is a perspective view schematically showing a toothed belt. [Figure 3] It is a sectional view taken along line A-A of FIG. 2. [Figure 4] It is an end view taken along line B-B of FIG. 2. [Figure 5] It is a diagram for explaining the shape of a pulley groove. [Figure 6] It is a diagram for explaining a method of manufacturing a toothed belt. [Figure 7] It is a diagram for explaining a method of manufacturing a toothed belt. [Figure 8] It is a diagram for explaining a method of manufacturing a toothed belt. [Figure 9] It is a diagram showing the dimensions of belt teeth. [Figure 10] It is a diagram showing the dimensions of a pulley groove. [Figure 11] It is a diagram showing the pulley layout of the transmission systems prepared in the examples and comparative examples. [Figure 12] It is a graph showing the evaluation results of the examples and comparative examples.

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 in general industrial machinery such as machine tools, printing machines, textile machines, and injection molding machines, as well as in electric power steering devices. The transmission system 1, as shown in Figure 1, comprises a drive pulley 22, a driven pulley 24, and a toothed belt 10. The drive pulley 22 and the driven pulley 24 each have multiple pulley grooves 21 formed therein. The toothed belt 10 has multiple belt teeth 12 (see Figure 2) on its inner circumference that mesh with the pulley grooves 21. The toothed belt 10 has a core wire 13 embedded in it. The toothed belt 10 is stretched over the drive pulley 22 and the driven pulley 24.

[0018] Both the drive pulley 22 and the driven pulley 24 have pulley grooves 21 that mesh with the belt teeth 12 of the toothed belt 10, provided at a predetermined pitch and evenly spaced along the outer circumference. The pulley grooves 21 of the drive pulley 22 and the pulley grooves 21 of the driven pulley 24 are identical in shape. Hereinafter, both the drive pulley 22 and the driven pulley 24 will be simply referred to as the toothed pulley 20.

[0019] The transmission system 1 transmits power from the drive source to the driven side. In the transmission system 1, the belt travel speed is, for example, between 0 rpm and 6000 rpm. In the transmission system 1, the transmission capacity is, for example, between 0.1 kW and 10 kW.

[0020] (Toothed belt) Figure 2 is a perspective view showing a part of a toothed belt 10 according to an embodiment of the present invention. This toothed belt 10 constitutes a power transmission system 1. Figure 3 is a cross-sectional view taken along line AA in Figure 2. Figure 4 is an end view of line BB in Figure 2. Figure 2 shows only a portion of the toothed belt 10, but the toothed belt 10 is an endless interlocking transmission belt. Furthermore, the toothed belt 10 is a single-sided toothed belt.

[0021] The belt length of the toothed belt 10 (belt length in 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, between 1.1 mm and 3.0 mm. 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 limited to this range.

[0022] The toothed belt 10 has a plurality of belt teeth 12 on its inner circumferential 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 has pulley grooves 21 along its outer circumference that mesh with the belt teeth 12 of the toothed belt 10 at a predetermined pitch. The outer diameter of the toothed pulley 20 is, for example, between 8 mm and 144 mm. The number of teeth on the toothed pulley 20 is, for example, between 10 and 150 teeth. The tooth profile of the pulley groove 21 is, for example, an arc tooth profile. The toothed pulley 20 may, for example, have a flange.

[0024] (Relationship between toothed belts and toothed pulleys) The teeth 12 of the toothed belt 10 are configured to smoothly mesh with the pulley groove 21. The toothed belt 10 satisfies a predetermined relationship between the tooth tip compression ratio Y (%) of the belt teeth 12 and the void ratio X (%) in the tooth width direction of the belt teeth 12.

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

[0026] In equation (1), the tooth height Hb of the belt is the distance between the apex of the tooth tip and the root line of the tooth in a cross-section along the length of the toothed belt 10 (see Hb in Figure 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] In equation (1), the tooth groove bottom depth Hp of the pulley is defined by 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 tooth groove depth Hp of the toothed pulley 20 is, for example, 0.40 mm or more and 2.20 mm or less.

[0028] The void ratio X(%) in the tooth width direction of the belt teeth 12 is an indicator of the amount of backlash when the belt teeth 12 mesh with the pulley groove 21. The void ratio X(%) in the tooth width direction of the belt teeth 12 is calculated by the following formula (2). X(%) = ((Pulley tooth width γ - Belt tooth width β) / Pulley tooth width γ) × 100 ... (2)

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

[0030] In equation (2), the pulley tooth width γ is the distance between P3 and P4, where P3 and P4 are the intersection points of a virtual arc VL2, which is part of the concentric circle of the tip circle Cp, passing through a portion of the tooth groove bottom depth Hp of the toothed pulley 20 in a cross-section along the circumferential direction of the toothed pulley 20, and the tooth surface of the toothed pulley 20. The pulley tooth width γ is, for example, between 0.50 mm and 3.00 mm.

[0031] The toothed belt 10 satisfies the relationship given by equation (3) between the tooth tip compression ratio Y (%) of the belt teeth 12 and the void ratio X (%) in the tooth width direction of the belt teeth 12. Y≧-0.45X-4···(3) In this embodiment, noise is suppressed by adjusting the relationship between the compression state of the tooth tips of the belt teeth 12 and the amount of backlash when the belt teeth 12 and the pulley groove 21 engage. The reason why noise is suppressed by satisfying equation (3) above is that it is possible to suppress both the meshing impact noise generated when the belt teeth and pulley grooves come into contact and the resonant noise of the air column. The resonant sound of the air column refers to the noise generated when the air is compressed when the teeth bite together. By adjusting the amount of backlash to satisfy equation (3), it is possible to suppress the rapid formation of the air column and ensure an escape route for the air, thereby reducing the noise.

[0032] On the other hand, if the tooth tip compression ratio Y (%) and the porosity X (%) do not satisfy the relationship in equation (3), and Y is smaller than "-0.45X-4", it is not possible to suppress both the meshing impact noise generated when the belt teeth and pulley grooves come into contact and the resonance noise of the air column, making it difficult to suppress noise. This is because, if equation (3) is not satisfied, the meshing impact noise becomes excessive, and / or the resonance noise becomes louder due to the rapid formation of the air column and the small escape route for the air.

[0033] In the above formula (3), the tooth tip compression ratio Y (%) is preferably 15 or less, and more preferably 12 or less. Also, the void ratio X (%) in the tooth width direction is preferably 20 or less, and more preferably 15 or less. In these cases, noise is easily suppressed.

[0034] The tooth tip compression ratio Y(%) is more preferably -2 ≤ Y ≤ 10. Furthermore, the void ratio X(%) is more preferably -30 ≤ X ≤ 0. In these cases, when the belt teeth 12 and the pulley groove 21 engage, the 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. As a result, the vibration source is dispersed, and the engagement becomes smoother. Consequently, noise can be further reduced. The vibration source refers to the point where the meshing impact noise or string vibration noise, which is a component of noise, originates. The point where the belt teeth 12 and pulley groove 21 come into contact when they mesh together is the vibration source.

[0035] When the tooth tip compression ratio Y(%) is less than -2, the tooth tips of the toothed belt 10 do not come into contact with the pulley groove 21 when meshing with the toothed pulley. In this case, the vibration source is concentrated at the tooth roots 15 of the toothed belt 10 without being dispersed. Therefore, the transmission system 1 is not good at suppressing noise. Furthermore, if the tooth tip compression ratio Y(%) exceeds 10, the tooth roots 15 of the toothed belt 10 will be in a floating state when meshing with the toothed pulley. In this case as well, the excitation source will not be dispersed but will be concentrated on the tooth tips of the toothed belt 10. Therefore, the transmission system 1 will not be able to suppress noise effectively.

[0036] When the void ratio X (%) is less than -30, the toothed belt 10 experiences increased pressure surface interference when meshing with the toothed pulley 20. Therefore, noise from the transmission system 1 is difficult to suppress. Furthermore, if the void ratio X (%) is greater than 0, when the toothed belt 10 engages with the toothed pulley, only one side of the pressure surface of the belt teeth 12 contacts the pulley groove 21. In this case, the vibration source is concentrated on one side of the pressure surface of the belt teeth 12. Therefore, noise from the transmission system 1 is difficult to suppress.

[0037] The tooth tip compression ratio Y(%) is particularly preferably 0 ≤ Y ≤ 8. Furthermore, the void ratio X(%) is particularly preferably -20 ≤ X ≤ -10. In this case, in addition to dispersing the excitation source, the interference state between the pressure surface of the belt teeth 12 and the tooth surface of the toothed pulley can be properly controlled. In other words, the two pressure surfaces of the belt teeth 12 are in contact with the tooth surface of the toothed pulley simultaneously, while the two pressure surfaces of the belt teeth 12 are not overcompressed. As a result, the noise of the transmission system 1 is further reduced.

[0038] The teeth 12 of the toothed belt 10 are serrated teeth. The angle of the tooth traces of the toothed belt teeth 12 is preferably between 3 degrees and 16 degrees. In this case, when the toothed belt 10 and the toothed pulley 20 mesh, the belt teeth 12 gradually mesh with the pulley groove 21 from one side to the other along the tooth trace, thus reducing the meshing impact noise. As a result, the noise of the transmission system 1 is suppressed. On the other hand, if the angle of the tooth groove is less than 3 degrees, the impact noise when the teeth mesh will not be significantly reduced. Also, if the angle of the tooth groove exceeds 16 degrees, the toothed belt is more likely to shift during operation, and this shifting of the toothed belt can lead to increased noise and reduced durability. The toothed pulley 20 that meshes with the toothed belt 10 also has a hexagonal tooth pattern.

[0039] In the toothed belt 10, the ratio B (Sb / Hb) of the thickness Sb of the back surface (see Figure 4) to the tooth height Hb of the helical teeth is preferably 1.75 or more and 2.40 or less. The toothed belt 10 is more effective at suppressing noise when the thickness Sb of the back is thicker. This is because a thicker back thickness Sb can dampen the vibration of the toothed belt, which is one of the causes of noise. On the other hand, if the thickness Sb of the back portion is made too thick, the rigidity of the toothed belt 10 becomes too large, resulting in poor engagement with the pulley groove 21 when the toothed belt 10 is wrapped around the toothed pulley 20. In addition, the bending fatigue resistance of the toothed belt decreases, and as a result, cracks are more likely to form on the back side, etc. Cracks are particularly likely to form in low-temperature environments. For these reasons, in the toothed belt 10, the above ratio B(Sb / Hb) is preferably within the range described above.

[0040] (Mechanism of toothed belt) The toothed belt 10 comprises a belt body 11, a core wire 13, and a reinforcing fabric 14, as shown in Figure 2. The belt body 11 has a strip shape and comprises a base portion 11a with a rectangular cross-section perpendicular to the longitudinal direction of the belt, and a plurality of teeth 11b provided on the inner circumference of the base portion 11a. These plurality of teeth 11b are integrated with the base portion 11a. The plurality of teeth 11b are provided at equal intervals along the length of the belt, with predetermined spacing between them. In the toothed belt 10, the reinforcing fabric 14 is provided to cover the inner circumferential surface of the teeth 11b. In the toothed belt 10, the belt teeth 12 are composed of the teeth 11b and the reinforcing fabric 14.

[0041] The belt body 11 is made of a rubber composition in which an uncrosslinked rubber composition containing rubber components and rubber compounding agents is crosslinked by heating and pressurizing. Examples of the rubber components mentioned above include ethylene-α-olefin elastomers such as hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), and ethylene-propylene-diene rubber (EPDM), as well as chlorosulfonated polyethylene rubber, styrene-butadiene rubber, and epichlorohydrin rubber. Among these, HNBR and EPDM are preferred.

[0042] Conventional known rubber compounding agents can be used as the rubber compounding agents mentioned above. Examples of rubber compounding agents include vulcanization accelerators, antioxidants, reinforcing agents, plasticizers, co-crosslinking agents, and crosslinking agents. Examples of the above-mentioned vulcanization accelerators include metal oxides, metal carbonates, fatty acids, and their derivatives. Examples of the above-mentioned metal oxides include zinc oxide (zinc oxide) and magnesium oxide. These vulcanization accelerators may be used individually or in combination of two or more types. The amount of the above-mentioned vulcanization accelerator is, for example, 3 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the rubber component.

[0043] Examples of the above-mentioned anti-aging agents include benzimidazole-based anti-aging agents, aromatic secondary amine-based anti-aging agents, and amine-ketone-based anti-aging agents. These anti-aging agents may be used individually or in combination of two or more types. The amount of the above-mentioned anti-aging agent is, for example, 1.5 parts by mass or more and 3.5 parts by mass or less per 100 parts by mass of the rubber component.

[0044] Examples of the reinforcing materials mentioned above include carbon black and silica. The reinforcing materials may also include carbon black and silica in combination. Examples of the carbon blacks mentioned above include channel black, furnace black, thermal black, and acetylene black. Examples of furnace blacks mentioned above include SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234. Examples of the above-mentioned thermal blacks include FT and MT. You may use only one type of carbon black, or you may use two or more types in combination.

[0045] When carbon black is used, its content is, for example, 10 to 30 parts by mass per 100 parts by mass of rubber component. When silica is used, its content is, for example, 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of rubber component.

[0046] Examples of the plasticizers mentioned above include dialkyl sebacate, dialkyl phthalate, and dialkyl adipate. Examples of the above-mentioned dialkyl sebacates include polyether esters and dioctyl sebacate (DOS). Examples of the above-mentioned dialkyl phthalates include dibutyl phthalate (DBP) and dioctyl phthalate (DOP). Examples of the above-mentioned dialkyl adipates include dioctyl adipate (DOA). These plasticizers may be used individually or in combination of two or more types. The content of the plasticizer is, for example, 5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of rubber component.

[0047] Examples of the above-mentioned co-crosslinking agents include trimethylolpropane trimethacrylate, m-phenylenedimaleimide, zinc dimethacrylate, and triallyl isocyanurate. These co-crosslinking agents may be used individually or in combination of two or more. The content of the above-mentioned co-crosslinking agent is, for example, 3 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the rubber component.

[0048] Examples of the crosslinking agents mentioned above include sulfur and organic peroxides. Sulfur and organic peroxides may be used in combination. Of course, either one may be used alone. When sulfur and organic peroxide are used in combination as the crosslinking agent, it is preferable that the total amount of the crosslinking agent is, for example, 0.1 parts by mass or more and 0.7 parts by mass or less of sulfur and 1 part by mass or more and 5 parts by mass or less of organic peroxide per 100 parts by mass of rubber component.

[0049] Examples of the core wire 13 include glass core wire, aramid core wire, carbon core wire, and steel core wire. These core wires are preferably made of twisted yarn. As the core wire 13, carbon wire and steel wire are preferred. Carbon and steel are materials with high elastic modulus. Therefore, toothed belts with carbon wire or steel wire are less prone to length changes and tooth pitch changes when a load is applied. As a result, toothed belts with carbon wire or steel wire are more likely to maintain a good meshing state with toothed pulleys.

[0050] The outer diameter of the core wire 13 is preferably such that the outer diameter φT in the belt thickness direction and the outer diameter φW in the belt width direction are both 0.15 mm or more and 0.80 mm or less. More preferably, the 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.

[0051] The core wire 13 has a pitch in the belt width direction and is arranged to form a spiral. The core wire 13 may consist of two strands, an S-twisted yarn and a Z-twisted yarn, arranged to form a double helix.

[0052] The core wires 13 are arranged so as to extend parallel to each other with spacing in the belt width direction. In this case, the number of core wires 13 per 10 mm of belt width is preferably 10 wires / 10 mm or more and 26 wires / 10 mm or less. A toothed belt 10 with core wires 13 arranged in this manner is suitable for ensuring excellent durability and excellent tension retention in high-load transmission. From a similar viewpoint, a more preferable number of core wires 13 is 14 wires / 10 mm or more and 24 wires / 10 mm or less. Furthermore, the gap between adjacent core wires 13 is, for example, 0.1 mm or more and 0.7 mm or less.

[0053] The core wire 13 may be treated with an adhesive to enhance its adhesion to the belt body. Examples of the bonding treatments mentioned above include RFL treatment, which involves immersion in an RFL aqueous solution followed by heating, and rubber cement treatment, which involves immersion in rubber cement followed by drying. These bonding treatments may be performed individually or in combination. The core wire 13 may be subjected to a surface treatment before the above-mentioned bonding treatment. Examples of such surface treatments include immersion in an epoxy solution or an isocyanate solution followed by heating. These bonding and surface preparation processes are performed before winding the core wire onto the mold in the toothed belt manufacturing method described later.

[0054] The reinforcing fabric 14 is made of, for example, woven fabric, knitted fabric, nonwoven fabric, etc. Examples of fibers that make up the reinforcing fabric 14 include polyamide fibers (nylon fibers), polyester fibers, aramid fibers, poly(p-phenylenebenzobisoxazole) (PBO) fibers, and cotton. For the reinforcing fabric 14, a woven fabric of polyamide fibers is preferred, for example. The reinforcing fabric 14 is preferably elastic. For example, a woven fabric using woolly processed weft yarn is elastic. In this case, it is preferable that the reinforcing fabric 14 is provided such that the direction in which it stretches most easily coincides with the length direction of the belt. The thickness of the reinforcing fabric 14 is, for example, 0.05 mm or more and 0.8 mm or less.

[0055] The reinforcing fabric 14 may be treated with an adhesive to enhance its adhesion to the belt body 11. Examples of the bonding treatments mentioned above include RFL treatment, which involves immersing the belt in an RFL aqueous solution and then heating it; soaking treatment, which involves immersing the belt in a low-viscosity rubber adhesive and then drying it; and coating treatment, which involves applying a high-viscosity rubber adhesive to the surface of the belt body and then drying it. One of these treatments may be performed, or two or more may be performed. The reinforcing fabric 14 may be subjected to a pre-treatment before the bonding process, which involves immersing it in an epoxy solution or isocyanate solution followed by heating. These bonding and surface preparation processes are performed before wrapping the reinforcing cloth 14 around the mold in the toothed belt manufacturing method described later.

[0056] (Manufacturing method for toothed belts) The manufacturing method for the toothed belt 10 will be explained in order of the steps. Figures 6 to 8 are diagrams illustrating the manufacturing method of the toothed belt 10. Figures 6 to 8 show only the mold 31 for belt forming and a portion of the belt (including the belt material).

[0057] In the manufacture of the toothed belt 10, a belt molding die 30 is used. The mold 30 is cylindrical. The outer circumference of the mold 30 is provided with recesses 31 extending in the axial direction and protrusions 32 extending in the axial direction. The recesses 31 have a cross-sectional shape corresponding to the belt teeth 12 and are grooves extending in the axial direction (the direction perpendicular to the plane of the paper in Figure 6). The recesses 31 are provided at regular intervals in the circumferential direction. The protrusions 32 are provided between adjacent recesses 31.

[0058] (1) Prepare the materials. An uncrosslinked rubber composition is obtained by kneading the rubber components and then adding and kneading the rubber compounding agent. The obtained uncrosslinked rubber composition is molded to produce an uncrosslinked rubber composition sheet 111. At this time, a method such as calendering can be used to mold the uncrosslinked rubber composition sheet 111.

[0059] Prepare the core wire 12 and reinforcing fabric 14, and apply adhesive treatment to each as needed. Furthermore, the reinforcing fabric 14 is formed into a cylindrical shape.

[0060] (2) The materials are layered in order. As shown in Figure 6, first, the cylindrical reinforcing cloth 14 is placed over the outer surface of the mold 30. Next, the core wire 13 is spirally wrapped over the reinforcing cloth 14. Furthermore, an uncrosslinked rubber composition sheet 111 is wrapped around it. Multiple sheets of the uncrosslinked rubber composition sheet 111 (two sheets in Figure 6) are wrapped around it. As a result, an uncrosslinked slab 135 is formed on the mold 30, in which the reinforcing fabric 14, core wire 13, and uncrosslinked rubber composition sheet 111 are laminated. At this time, it is preferable that the uncrosslinked rubber composition sheet 111 be laminated so that the row direction corresponds to the belt length direction.

[0061] (3) As shown in Figure 7, a rubber sleeve 34 is placed over the uncrosslinked slab 135 on the mold 31, and this is placed inside the vulcanizing can and sealed. Next, high-temperature and high-pressure steam is filled into the vulcanizing can. Furthermore, this state is maintained for a predetermined time. As a result, the uncrosslinked slab 135 is pressed towards the mold 31 and heated. At this time, the uncrosslinked rubber composition sheet 111 passes between the core wires 13, presses against the reinforcing fabric 14, and flows into each of the multiple recesses 32 of the mold 31, where it is crosslinked. Simultaneously, the core wires 13 and the reinforcing fabric 14 are integrated. As a result, a cylindrical belt slab 35 is formed, as shown in Figure 8.

[0062] (4) The inside of the vulcanizing can is depressurized to release the seal. Next, the belt slab 35 formed between the mold 31 and the rubber sleeve 34 is demolded. After that, the demolded belt slab 35 is cut into slices. Through these steps, a toothed belt 10 is obtained.

[0063] (Manufacturing method for toothed pulleys) The toothed pulley 20 can be manufactured by conventionally known methods. The toothed pulley 20 can be manufactured, for example, by creating a dedicated hob cutter according to the shape of the pulley groove of the toothed pulley, then performing gear cutting on a metal material using this hob cutter, and further performing drilling, external shaping, flange attachment, etc., as necessary.

[0064] (Other embodiments) The teeth of the toothed belt according to the embodiment of the present invention are not limited to beveled teeth, but may also be straight teeth. If the teeth of the toothed belt are straight, then a toothed pulley should also be selected that has straight teeth on its outer circumference. [Examples]

[0065] The embodiments of the present invention will be described in more detail below with reference to examples, but the embodiments of the present invention are not limited to the following examples. Here, we prepared transmission systems with different combinations of toothed belts and toothed pulleys and evaluated the level of noise.

[0066] (Toothed belt) A toothed belt (A) with the same configuration as the toothed belt 10 shown in Figures 2-4 was manufactured. The toothed belt (A) has a belt width Wb of 20 mm and a belt circumference of 330 mm when the compression ratio is 0%. The toothed belt (A) has bevel teeth with a tooth pitch P of 2 mm and a tooth groove 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 teeth of the toothed belt (A) are as shown in Figure 9, where S is 1.3 mm, A is 0.172 mm, and r bb The value is 1.3 mm. In Figure 9, "S" and "r bb " is "S" and "r" as listed in Table 4 of JIS B 1857-1 (2015). bb This corresponds to ", and "A" corresponds to "aY" derived from Table 4 of JIS B 1857-1 (2015).

[0067] 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 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 threads of this woven fabric are polyamide 66 fibers.

[0068] (Toothed pulley) We manufactured toothed pulleys (1) to (33) with different shapes of pulley grooves 21. The toothed pulleys (1) to (33) were manufactured by creating a dedicated hob cutter according to the shape of the pulley groove of each pulley, and then manufacturing them through a process that included tooth cutting using this hob cutter. Toothed pulleys (1) to (33) have an outside radius of 12.5 mm and 40 teeth (40T). Two of each toothed pulley (1) to (33) were manufactured. The width of toothed pulleys (1) to (33) is 22 mm. The toothed pulleys (1) to (33) are made of stainless steel.

[0069] The dimensions of each pulley groove of toothed pulleys (1) to (33) are as follows, in the pulley groove dimensions shown in Figure 10: Hp, R1, A, and B g Each of them has the dimensions shown in Table 1. In Figure 10, "Hp", "R1", and "B g " is listed in Table 13 of JIS B 1857-2 (2015) as "H g "R1", and "B g This corresponds to "", and "A" corresponds to "a-Y1" derived from Table 13 of JIS B 1857-2 (2015).

[0070] (Examples 1-19, Comparative Examples 1-14) A power transmission system was constructed using the toothed belt, drive pulley, and driven pulley combinations shown in Tables 1 and 2, by wrapping the toothed belt around two pulleys having a drive pulley and a driven pulley.

[0071] Figure 11 shows the pulley layout of the power transmission system. In this transmission system, the set weight (SW) was fixed so that the belt tension was 100N. The reduction ratio was set to 1.0.

[0072] (evaluation) The above transmission system was run at a constant speed of 3000 rpm, and the sound generated was assessed by auditory evaluation and ranked on a five-point scale. The results are shown in Tables 1 and 2 and Figure 12. In this evaluation, a lower rank indicates quieter operation.

[0073] [Table 1]

[0074] [Table 2]

[0075] As shown in Tables 1 and 2 and Figure 12, it was found that noise in the transmission system is suppressed when the compression ratio Y (%) of the belt teeth and the void ratio X (%) in the width direction of the belt teeth satisfy a predetermined relationship. [Explanation of Symbols]

[0076] 1.40 Transmission System 10 Toothed belt 11 Belt body 11a base 11b Teeth 12 belt teeth 13 Core wires 14 Reinforcement fabric 15. Root of the tooth 20-tooth pulley 21 Pulley groove 22, 41 Drive pulley 24, 42 Driven pulley 30 molds 31 Recess 32 Convex part 34 Rubber sleeves 35 Belt Slab 111 Uncrosslinked rubber composition sheet 135 Unbridged slab

Claims

1. A transmission system comprising a toothed belt and a toothed pulley that meshes with the toothed belt, The toothed belt has a back portion in which a core wire is embedded, and belt teeth provided on the inner circumference side of the back portion that mesh with the pulley groove of the toothed pulley. The tooth tip compression ratio Y (%) of the belt teeth calculated by formula (1) is 0 ≤ Y ≤ 8, The void ratio X (%) in the tooth width direction of the belt teeth, calculated by equation (2), is -20 ≤ X ≤ -10. A transmission system in which the tooth tip compression ratio Y (%) and the void ratio X (%) satisfy the relationship given by equation (3). Y (%) = ((Belt tooth height Hb - Pulley tooth groove depth Hp) / Belt tooth height Hb) × 100 ... (1) X (%) = ((pulley tooth width γ - belt tooth width β) / pulley tooth width γ) × 100 ... (2) Y≧-0.45X-4...(3)

2. The transmission system according to claim 1, wherein the core wire is a carbon core wire or a steel core wire.

3. The aforementioned belt teeth are serrated teeth, The transmission system according to claim 1, wherein the angle of the tooth trace of the helical teeth with respect to the belt width direction is 3 degrees or more and 16 degrees or less.

4. The transmission system according to claim 3, wherein the ratio B of the thickness Sb of the back portion to the tooth height Hb of the hash teeth is 1.75 or more and 2.40 or less.

5. The transmission system according to claim 1, wherein the tooth height Hb of the belt is 0.50 mm or more and 2.0 mm or less.

6. The transmission system according to claim 1, wherein the tooth groove bottom depth Hp of the pulley is 0.40 mm or more and 2.20 mm or less.

7. The transmission system according to claim 1, wherein the belt tooth width β is 0.50 mm or more and 3.00 mm or less.

8. The transmission system according to claim 1, wherein the pulley tooth width γ is 0.50 mm or more and 3.00 mm or less.

9. The transmission system according to claim 1, wherein the tooth profile of the belt teeth is an arc tooth profile.

10. The transmission system according to claim 1, wherein the pitch of the belt teeth is 0.50 mm or more and 3.0 mm or less.

Images