Toothed belt and transmission system

Abstract

To provide a transmission system with noise suppressed.SOLUTION: A toothed belt has a back part in which a core wire is embedded, and belt teeth provided on an inner peripheral side of the back part and meshing with a pulley groove of a toothed pulley. In the toothed belt, a tooth tip compression ratio Y (%) of the belt teeth calculated by formula (1) and a void ratio X (%) in a tooth width direction of the belt teeth calculated by formula (2) satisfy the relation of formula (3): 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); Y≥-0.45X-4 ... (3).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to toothed belts and power transmission systems. This application claims priority to Japanese Application No. 2023-033765, filed on March 6, 2023, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] A transmission system equipped with a toothed belt and a toothed pulley is known as a power transmission system. A transmission system equipped with 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, the above-mentioned transmission system has a problem in that the sound (running sound) generated during driving becomes noisy.

[0003] Several methods have been proposed to reduce noise generated when a toothed belt and a toothed pulley mesh together. For example, Patent Document 1 proposes a toothed belt capable of reducing noise, which comprises a back portion, a plurality of helical teeth arranged in the belt length direction, and a core wire made of fibers that is embedded in the back portion in a spiral shape along the belt length direction, wherein the helical teeth have tooth cloth provided on the inner circumference side, the angle between the direction in which the tooth traces of the helical teeth extend and the belt width direction is 8 degrees or more and 16 degrees or less, the fibers that make up the core wire are made of single-twisted yarn, the twist direction of the yarn is inclined in the opposite direction to the direction in which the tooth traces of the helical teeth extend with respect to the belt width direction, and the winding direction of the core wire is inclined in the same direction as the direction in which the tooth traces of the helical teeth extend with respect to the belt width direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2014 / 091672 issue Summary of the Invention [Problem to be solved by the invention]

[0005] In a transmission system consisting of a toothed belt and toothed pulleys, there is a need to reduce the running noise (noise suppression), and this need will never go away. In particular, in applications where quietness is required, it is important to suppress noise. [Means for solving the problem]

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a transmission system with reduced noise.

[0007] (1) A toothed belt according to 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 a pulley groove of a toothed pulley, The tooth tip compression ratio Y (%) of the belt tooth calculated by formula (1), and The toothed belt has a void ratio X (%) in the tooth width direction of the belt tooth calculated by formula (2) that satisfies the relationship of formula (3). 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) Y≧-0.45X-4 (3)

[0008] This toothed belt has a low running noise because the tooth tip compression ratio Y of the belt teeth and the void ratio X of the belt teeth in the tooth width direction satisfy a predetermined relationship. This toothed belt has reduced 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 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 one of the toothed belts (1) to (3) above, the core wire is preferably a carbon core wire or a steel core wire. In this case, the toothed belt has good tension maintaining properties, and the belt length of the toothed belt is less likely to change, making it suitable for use in high load transmission applications.

[0011] (5) In any one of the toothed belts (1) to (4) above, The belt teeth are helical teeth, The angle of the tooth trace of the helical teeth with respect to the belt width direction is preferably 3 degrees or more and 16 degrees or less. In this case, it is possible to reduce the impact noise generated when the belt teeth and the pulley grooves mesh with each other, thereby further suppressing noise.

[0012] (6) In the toothed belt of (5) above, A ratio B of the thickness Sb of the back portion to the tooth height Hb of the helical teeth is preferably 1.75 or more and 2.40 or less. In this case, the toothed belt further suppresses noise, and 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] (7) A transmission system according to the present invention is a transmission system having a toothed belt and a toothed pulley that meshes with the toothed belt, The toothed belt is the toothed belt according to any one of (1) to (6). This power transmission system has a toothed belt according to any one of (1) to (6) as a toothed belt, and therefore has low running noise. Noise is suppressed in this power transmission system. Effect of the Invention

[0014] According to the present invention, it is possible to provide a toothed belt capable of suppressing noise, and also to provide a noise-suppressing transmission system including this toothed belt. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a side view showing a schematic diagram of the transmission system. [Diagram 2] FIG. 2 is a perspective view showing a schematic diagram of a toothed belt. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is an end view taken along line BB in FIG. [Diagram 5] FIG. 4 is a diagram illustrating the shape of a pulley groove. [Figure 6] 4A to 4C are diagrams illustrating a method for manufacturing a toothed belt. [Figure 7] 4A to 4C are diagrams illustrating a method for manufacturing a toothed belt. [Figure 8] 4A to 4C are diagrams illustrating a method for manufacturing a toothed belt. [Figure 9] FIG. 4 is a diagram showing the dimensions of belt teeth. [Figure 10] FIG. 4 is a diagram showing dimensions of a pulley groove. [Figure 11] FIG. 2 is a diagram showing the pulley layout of the transmission systems prepared in the examples and the comparative examples. [Figure 12] 1 is a graph showing the evaluation results of Examples and Comparative Examples. BEST MODE FOR CARRYING OUT THEINVENTION

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

[0017] (Transmission System) FIG. 1 is a side view that illustrates a schematic diagram of a transmission system 1 according to an embodiment of the present invention. The transmission system 1 is suitable for use in general industrial machines such as machine tools, printing machines, textile machines, and injection molding machines, and in electric power steering devices. As shown in FIG. 1, the transmission system 1 includes a drive 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 has a plurality of belt teeth 12 (see FIG. 2) on its inner periphery that mesh with the pulley grooves 21. The toothed belt 10 has a core wire 13 embedded therein. The toothed belt 10 is wound around the drive pulley 22 and the driven pulley 24.

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

[0019] The transmission system 1 transmits power from a driving source to a 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) 2 is a perspective view showing a part of a toothed belt 10 according to an embodiment of the present invention. The toothed belt 10 constitutes a transmission system 1. FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is an end view taken along line BB in FIG. 2, the toothed belt 10 is an endless meshing power transmission belt, and is a single-sided toothed belt.

[0021] The belt length of the toothed belt 10 (the belt length at the belt pitch line BL) is, for example, not less than 100 mm and not more than 400 mm. The belt width Wb of the toothed belt 10 is, for example, not less than 4 mm and not more than 30 mm. 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 toothed belt 10 at its thickest portion. 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, not less than 0.50 mm and not more than 3.0 mm. The belt teeth 12 have, for example, a circular 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 that mesh with the belt teeth 12 of the toothed belt 10 provided at a predetermined pitch along the outer periphery. The outer diameter of the toothed pulley 20 is, for example, not less than 8 mm and not more than 144 mm. The number of teeth of the toothed pulley 20 is, for example, 10 to 150. The tooth profile of the pulley groove 21 is, for example, a circular arc tooth profile. The toothed pulley 20 may, for example, be provided with a flange.

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

[0025] The tooth tip compression ratio Y (%) of the belt tooth 12 is an index indicating the compression state of the tooth tip of the belt tooth 12 when the belt tooth 12 meshes with the pulley groove 21. The tooth tip compression ratio Y (%) of the belt tooth 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 base line in a cross section of the toothed belt 10 along the longitudinal direction (see Hb in FIG. 4). The tooth height Hb of the toothed belt 10 is, for example, not less than 0.50 mm and not more than 2.0 mm.

[0027] The pulley tooth groove bottom depth Hp in formula (1) 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 FIG. 5). The tooth groove bottom depth Hp of the toothed pulley 20 is, for example, not less than 0.40 mm and not more than 2.20 mm.

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

[0029] The belt tooth width β in formula (2) is the distance between P1 and P2, where P1 and P2 are the intersections between a virtual straight line VL1 that passes through a portion at half the height of the belt tooth height Hb in a cross section along the longitudinal direction of the toothed belt 10 and is perpendicular to the direction of the belt tooth height Hb, and the pressure surface of the belt tooth 12. The belt tooth width β is, for example, not less than 0.50 mm and not more than 3.00 mm.

[0030] The pulley tooth width γ in equation (2) is the distance between P3 and P4, where P3 and P4 are the intersections between a virtual arc VL2, which is part of a concentric circle of the tooth tip circle Cp and passes through a portion that is half the depth Hp of the pulley tooth groove bottom in a cross section along the circumferential direction of the toothed pulley 20, and the tooth flank of the toothed pulley 20. The pulley tooth width γ is, for example, not less than 0.50 mm and not more than 3.00 mm.

[0031] In the toothed belt 10, the tooth tip compression ratio Y (%) of the belt tooth 12 and the void ratio X (%) in the tooth width direction of the belt tooth 12 satisfy the relationship of formula (3). Y≧-0.45X-4 (3) In this embodiment, the noise is suppressed by adjusting the relationship between the compression state of the tooth tips of the belt teeth 12 when the belt teeth 12 mesh with the pulley grooves 21 and the amount of backlash. The reason that noise is suppressed by satisfying the above formula (3) is that it is possible to simultaneously suppress the meshing impact noise that occurs when the belt teeth and pulley grooves come into contact with each other and the resonance noise in the air column. The air column resonance noise refers to the noise generated by the air being compressed when the teeth mesh. By adjusting the backlash amount to satisfy equation (3), it is possible to suppress the sudden formation of an air column and ensure an escape route for the air, thereby suppressing the noise.

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

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

[0034] The tooth tip compression ratio Y (%) is more preferably −2≦Y≦10. The void ratio X (%) is more preferably −30≦X≦0. In these cases, when the belt teeth 12 mesh with the pulley groove 21, 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. This distributes the vibration source and makes the meshing smoother. As a result, noise can be further reduced. The vibration source refers to a location where meshing impact sound, which is one element of noise, or string vibration sound occurs. The location where the belt teeth 12 and the pulley grooves 21 come into contact with each other when they mesh corresponds to the vibration source.

[0035] If 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 not dispersed but is concentrated at the tooth bottom portion 15 of the toothed belt 10. Therefore, noise from the transmission system 1 is difficult to suppress. Furthermore, when the tooth tip compression ratio Y (%) exceeds 10, the tooth bottom portion 15 of the toothed belt 10 is in a floating state when meshing with the toothed pulley. In this case as well, the vibration source is not dispersed but is concentrated on the tooth tips of the toothed belt 10. Therefore, noise from the transmission system 1 is difficult to suppress.

[0036] If the void ratio X (%) is less than -30, interference of the pressure surface increases when the toothed belt 10 meshes with the toothed pulley 20. Therefore, noise of the transmission system 1 is difficult to suppress. Furthermore, when the void ratio X (%) is greater than 0, the toothed belt 10 is in a state where only the pressure surface on one side of the belt tooth 12 contacts the pulley groove 21 when meshing with the toothed pulley. In this case, the vibration source is concentrated on the pressure surface on one side of the belt tooth 12. Therefore, the noise of the transmission system 1 is difficult to suppress.

[0037] The tooth tip compression ratio Y (%) is particularly preferably 0≦Y≦8. Also, the void ratio X (%) is particularly preferably −20≦X≦−10. In this case, in addition to dispersing the vibration source, the interference state between the pressure surface of the belt tooth 12 and the tooth surface of the toothed pulley can be optimized. In other words, the two pressure surfaces of the belt tooth 12 are in contact with the tooth surface of the toothed pulley at the same time, but are not compressed too much. As a result, the noise of the transmission system 1 is further reduced.

[0038] The belt teeth 12 of the toothed belt 10 are helical teeth. The angle of the tooth trace of the belt teeth 12, which are helical teeth, is preferably 3 degrees or more and 16 degrees or less. In this case, when the toothed belt 10 and the toothed pulley 20 mesh with each other, the belt teeth 12 gradually mesh with the pulley groove 21 from one side to the other along the tooth trace, so that the meshing impact sound can be reduced. Therefore, the noise of the transmission system 1 is suppressed. On the other hand, if the tooth trace angle is less than 3 degrees, the impact noise generated when the teeth mesh together is not significantly reduced. Also, if the tooth trace angle exceeds 16 degrees, the toothed belt is likely to become misaligned while in motion, which can lead to increased noise and reduced durability. The toothed pulley 20 that meshes with the toothed belt 10 also has helical teeth.

[0039] In the toothed belt 10, the ratio B (Sb / Hb) of the thickness Sb of the back portion to the tooth height Hb of the helical teeth (see FIG. 4) is preferably 1.75 or greater and 2.40 or less. The thicker the back thickness Sb of the toothed belt 10, the easier it is to suppress noise. This is because a thicker back thickness Sb can attenuate 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 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 toothed belt 10 does not mesh well with the pulley groove 21. Also, the toothed belt has a reduced resistance to bending fatigue, which makes the back side and other parts more susceptible to cracking. In particular, cracking occurs more easily in a low-temperature environment. For these reasons, in the toothed belt 10, the ratio B (Sb / Hb) is preferably in the above-mentioned range.

[0040] (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 fabric 14. The belt body 11 has a band shape, a base 11a having a rectangular cross section perpendicular to the belt longitudinal direction, and a plurality of teeth 11b provided on the inner periphery of the base 11a. The teeth 11b are integrated with the base 11a. The teeth 11b are provided at equal intervals at predetermined intervals along the belt longitudinal direction. In the toothed belt 10, the reinforcing cloth 14 is provided so as to cover the inner peripheral surface of the toothed portion 11b. In the toothed belt 10, the belt tooth 12 is composed of the toothed portion 11b and the reinforcing cloth 14.

[0041] The belt body 11 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 application of heat and pressure. 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, epichlorohydrin rubber, and the like. Of these, HNBR and EPDM are preferred.

[0042] As the rubber compounding agent, a conventionally known rubber compounding agent can be used, and examples of the rubber compounding agent include a vulcanization accelerator, an antioxidant, a reinforcing agent, a plasticizer, a co-crosslinking agent, and a crosslinking agent. Examples of the vulcanization accelerator include metal oxides, metal carbonates, fatty acids and derivatives thereof, etc. Examples of the metal oxide include zinc oxide (zinc oxide), magnesium oxide, etc. These vulcanization accelerating aids may be used alone or in combination of two or more kinds. The content of the vulcanization accelerating aid 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 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 kinds. 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 3.5 parts by mass or less.

[0044] 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. The carbon black may be used alone or in combination of two or more kinds.

[0045] When carbon black 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. 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.

[0046] Examples of the plasticizer include dialkyl sebacate, dialkyl phthalate, and dialkyl adipate. Examples of the dialkyl sebacate include polyether ester, dioctyl sebacate (DOS), and the like. Examples of the dialkyl phthalate include dibutyl phthalate (DBP) and dioctyl phthalate (DOP). An example of the dialkyl adipate is dioctyl adipate (DOA). These plasticizers may be used alone or in combination of two or more kinds. The amount 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 the rubber component.

[0047] 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 kinds. The content of the co-crosslinking agent is, for example, 3 parts by mass or more and 8 parts by mass or less based on 100 parts by mass of the rubber component.

[0048] Examples of the crosslinking agent include sulfur, organic peroxides, etc. Sulfur and organic peroxides may be used in combination. Of course, only one of them may be used. 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 0.7 parts by mass or less of sulfur and 1 part by mass or more and 5 parts by mass or less of the organic peroxide per 100 parts by mass of the rubber component.

[0049] Examples of the core wire 13 include a glass core wire, an aramid core wire, a carbon core wire, a steel core wire, etc. These core wires are preferably made of twisted yarn. The core wire 13 is preferably a carbon core wire or a steel core wire. Carbon and steel are materials with high elasticity. Therefore, a toothed belt having 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 having a carbon core wire or a steel core wire is more likely to maintain a good meshing state with a toothed pulley.

[0050] The outer diameter φT in the belt thickness direction and the outer diameter φW in the belt width direction of the core wire 13 are preferably 0.15 mm to 0.80 mm, more preferably 0.25 mm to 0.50 mm. 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 be composed of two threads, an S twisted thread and a Z twisted thread, which are arranged to form a double spiral.

[0052] The core wires 13 are arranged to extend in parallel with each other at intervals 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. The toothed belt 10 having the core wires 13 arranged in this manner is suitable for ensuring excellent durability in high load transmission and excellent tension maintenance in high load transmission. From the same viewpoint, the number of core wires 13 is more preferably 14 wires / 10 mm or more and 24 wires / 10 mm or less. The dimension of the gap between adjacent core wires 13 is, for example, not less than 0.1 mm and not more than 0.7 mm.

[0053] The core wires 13 may be subjected to an adhesive treatment to increase the adhesive strength with the belt body. Examples of the adhesion treatment include an RFL treatment in which the material is immersed in an RFL aqueous solution and then heated, a rubber cement treatment in which the material is immersed in rubber cement and then dried, etc. Only one of these adhesion treatments may be performed, or both may be performed. Prior to the adhesion treatment, the core wire 13 may be subjected to a surface treatment, such as a treatment of immersing the core wire 13 in an epoxy solution or an isocyanate solution and then heating the same. These adhesive treatments and surface preparations are carried out before winding the core wire around a die in the manufacturing method of the toothed belt described below.

[0054] The reinforcing fabric 14 is made of, for example, a woven fabric, a knitted fabric, a nonwoven 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. The reinforcing fabric 14 is preferably, for example, a woven fabric made of polyamide fibers. It is preferable that the reinforcing fabric 14 has elasticity. For example, a woven fabric using a weft yarn that has been subjected to a woolly finish has elasticity. In this case, it is preferable that the reinforcing fabric 14 is provided so that the direction in which it is most likely to stretch coincides with the length direction of the belt. The thickness of the reinforcing fabric 14 is, for example, not less than 0.05 mm and not more than 0.8 mm.

[0055] The reinforcing fabric 14 may be subjected to an adhesive treatment in order to increase the adhesive strength with the belt body 11 . 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 paste and then dried, and a coating treatment in which a high-viscosity rubber paste is applied to the surface of the belt body side and then dried, etc. Only one of these treatments may be performed, or two or more of them may be performed. Prior to the adhesive treatment, the reinforcing fabric 14 may be subjected to a surface preparation treatment in which the fabric is immersed in an epoxy solution or an isocyanate solution and then heated. These adhesion treatments and surface preparations are carried out before winding the reinforcing fabric 14 around a mold in the manufacturing method of the toothed belt, which will be described later.

[0056] (Manufacturing method of toothed belts) The method for manufacturing the toothed belt 10 will be described in the order of steps. 6 to 8 are diagrams for explaining the manufacturing method of the toothed belt 10. In Fig. 6 to Fig. 8, only a part of the belt (including the belt material) and a die 31 for forming the belt are shown.

[0057] In manufacturing the toothed belt 10, a belt forming die 30 is used. The mold 30 is cylindrical. On the outer periphery of the mold 30, recesses 31 extending in the axial direction and protrusions 32 extending in the axial direction are provided. The recesses 31 have a cross-sectional shape corresponding to the belt teeth 12, and are grooves extending in the axial direction (direction perpendicular to the paper surface of FIG. 6). The recesses 31 are provided at a constant pitch and spaced apart in the circumferential direction. The protrusions 32 are provided between adjacent recesses 31.

[0058] (1) Prepare the materials. The rubber component is masticated, and then rubber compounding agents are added and kneaded to obtain an uncrosslinked rubber composition. The obtained uncrosslinked rubber composition is molded to prepare an uncrosslinked rubber composition sheet 111. At this time, as a molding method for the uncrosslinked rubber composition sheet 111, for example, calendar molding or the like can be adopted.

[0059] The core wire 12 and the reinforcing cloth 14 are prepared, and if necessary, each is subjected to an adhesive treatment. Furthermore, the reinforcing fabric 14 is formed into a cylindrical shape.

[0060] (2) The materials are laminated in order. As shown in Fig. 6, first, the reinforcing cloth 14 formed in a cylindrical shape is placed on the outer circumferential surface of the mold 30. Next, the core wire 13 is wound in a spiral shape around the reinforcing cloth 14. Furthermore, an uncrosslinked rubber composition sheet 111 is wound thereon. A plurality of uncrosslinked rubber composition sheets 111 (two sheets in FIG. 6) are wound. As a result, an uncrosslinked slab 135 in which the reinforcing fabric 14, the cord 13, and the uncrosslinked rubber composition sheet 111 are laminated is formed on the mold 30. At this time, it is preferable to laminate the uncrosslinked rubber composition sheet 111 so that the grain direction corresponds to the belt length direction.

[0061] (3) As shown in Fig. 7, the uncrosslinked slab 135 on the mold 31 is covered with a rubber sleeve 34, which is then placed in a vulcanizer and sealed. Next, high-temperature, high-pressure steam is filled into the vulcanizer. This state is then maintained for a predetermined time. As a result, the uncrosslinked slab 135 is pressed against the mold 31 and heated. At this time, the uncrosslinked rubber composition sheet 111 passes between the cords 13 and flows into each of the recesses 32 of the mold 31 while pressing the reinforcing cloth 14, and is crosslinked. At the same time, the cords 13 and the reinforcing cloth 14 are integrated. As a result, a cylindrical belt slab 35 is molded as shown in Fig. 8.

[0062] (4) The pressure inside the vulcanizer is reduced to release the seal. Then, the belt slab 35 molded between the metal mold 31 and the rubber sleeve 34 is demolded. The demolded belt slab 35 is then cut into rings. Through these steps, the toothed belt 10 is obtained.

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

[0064] (Other embodiments) The belt teeth of the toothed belt according to the embodiment of the present invention are not limited to helical teeth, and may be straight teeth. When the belt teeth of the toothed belt are straight teeth, a pulley having straight teeth on its outer periphery is selected as the toothed pulley. EXAMPLES

[0065] 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. Here, transmission systems with different combinations of toothed belts and toothed pulleys were prepared and the noise levels were evaluated.

[0066] (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 when compressed by 0%. The toothed belt (A) has helical teeth with a tooth pitch P of 2 mm and a tooth trace angle of 5 degrees as belt teeth. 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 belt tooth dimensions of the toothed belt (A) shown in FIG. 9 are S 1.3 mm, A 0.172 mm, r bb In FIG. 9, "S" and "r bb " is "S" and "r" listed in Table 4 of JIS B 1857-1 (2015) bb " 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 a rubber component of EPDM. 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 made of polyamide 66 fibers.

[0068] (Toothed pulley) Toothed pulleys (1) to (33) having different shapes of the pulley groove 21 were manufactured. The toothed pulleys (1) to (33) were produced through a manufacturing process including a gear cutting process using a dedicated hob cutter produced according to the shape of the pulley groove of each pulley. The toothed pulleys (1) to (33) each have a tip radius of 12.5 mm and 40 teeth (40T). Two of each of the toothed pulleys (1) to (33) were manufactured. The width of the toothed pulleys (1) to (33) is 22 mm. The toothed pulleys (1) to (33) are made of stainless steel.

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

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

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

[0072] (evaluation) The above transmission system was run at a constant speed of 3000 rpm, and the sounds generated at this time were checked by ear and ranked into 5 levels. The results are shown in Tables 1 and 2 and Figure 12. In this evaluation, the lower the ranking number, the quieter the device is.

[0073] [Table 1]

[0074] [Table 2]

[0075] As shown in Tables 1 and 2 and FIG. 12, it has become clear that noise of the power transmission system can be suppressed by satisfying a predetermined relationship between the tooth tip compression ratio Y (%) of the belt tooth and the void ratio X (%) in the tooth width direction of the belt tooth. [Explanation of symbols]

[0076] 1, 40 Transmission system 10 Toothed belt 11 Belt body 11a base 11b Teeth 12 belt teeth 13 Core Wire 14 Reinforcement fabric 15 Tooth root 20 Toothed pulley 21 Pulley groove 22, 41 Drive pulley 24, 42 Driven pulley 30 Mold 31 Recess 32 Convex 34 Rubber sleeve 35 Belt Slab 111 Uncrosslinked rubber composition sheet 135 Unbridged 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, The tooth tip compression ratio Y (%) of the belt tooth calculated by the formula (1), and A toothed belt, wherein the void ratio X (%) in the tooth width direction of the belt tooth calculated by formula (2) satisfies the relationship of formula (3). 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) Y≧-0.45X-4...(3)

2. 2. The toothed belt according to claim 1, wherein the tooth tip compression rate Y (%) is in the range of -2≦Y≦10, and the void ratio X (%) is in the range of -30≦X≦0.

3. 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.

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

5. The belt teeth are helical teeth, 5. 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.

6. 6. The toothed belt according to claim 5, 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.

7. 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 6.

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