Transmission system

Abstract

A transmission system comprising a toothed belt, a first toothed pulley, and a second toothed pulley having a larger diameter than the first toothed pulley, wherein the toothed belt is wound around the first toothed pulley and the second toothed pulley, the nominal pitch of the belt teeth is 2 mm, the belt teeth are diamond teeth with a tooth flank angle of 5.0 degrees or more and 9.0 degrees or less, the speed ratio is 2.0 or more and less than 5.0, and each of the toothed belt and the first toothed pulley, and the toothed belt and the second toothed pulley satisfies the following formula (1). 1.5X - 0.31 < Y < X - 0.03 ···(1) In formula (1), X is the PLD of the toothed belt, and Y is a value calculated by the following formula (2). Y = ((nominal pitch of the toothed belt × number of pulley teeth T / π) - tip circle diameter) / 2 ···(2)

Description

Technical Field

[0001] The present invention relates to a transmission system. This application claims priority based on Japanese Patent Application No. 2024-012996 filed on January 31, 2024, and incorporates by reference 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] Conventionally, methods for reducing the noise when a toothed belt and a toothed pulley mesh have been proposed. For example, in Patent Document 1, a toothed belt having a back portion in which a core wire is embedded and a plurality of tooth portions provided at predetermined intervals along the belt longitudinal direction on one surface of the back portion, each of which is inclined with respect to the belt width direction, wherein a part of the surface of the tooth portion and the above one surface of the back portion is composed of a tooth cloth, the tooth pitch of the plurality of tooth portions is 2 mm or more and less than 4 mm, the thickness of the back portion is 0.4 mm or more and 1.8 mm or less, the core wire includes high-strength glass fiber or carbon fiber, is a twisted cord having a diameter of 0.2 mm or more and 0.6 mm or less, and the core wire pitches between the core wires are arranged so as to be in the range of 0.45 mm or more and 0.6 mm or less.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0006] An object of the present disclosure is to provide a transmission system with suppressed noise, which is specified from a new perspective different from the conventional one.

[0007] A transmission system according to an aspect of the present invention includes a toothed belt having a plurality of belt teeth provided on the inner peripheral side, a first toothed pulley having a plurality of pulley grooves engaged with the belt teeth provided on the outer periphery, a second toothed pulley having a plurality of pulley grooves engaged with the belt teeth provided on the outer periphery and having a larger diameter than the first toothed pulley, a transmission system in which the toothed belt is wound around the first toothed pulley and the second toothed pulley, the nominal pitch of the belt teeth is 2 mm, the belt teeth are arrowhead teeth with a tooth flank angle of 5.0 degrees or more and 9.0 degrees or less, the speed ratio is 2.0 or more and less than 5.0, each of the toothed belt and the first toothed pulley, and the toothed belt and the second toothed pulley satisfy the following formula (1). 1.5X - 0.31 < Y < X - 0.03 ··· (1) In formula (1), X is the pitch length between adjacent teeth of the toothed belt, and Y is a value calculated by the following formula (2). Y = ((nominal pitch of the toothed belt × number of pulley teeth T / π) - tip circle diameter) / 2 ··· (2)

Advantages of the Invention

[0008] According to the present disclosure, a transmission system with suppressed noise can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0010] The outline of the embodiments of the present invention will be listed and described. [1] A toothed belt provided with a plurality of belt teeth on the inner peripheral side, A first toothed pulley provided with a plurality of pulley grooves engaging with the belt teeth on the outer periphery, A second toothed pulley provided with a plurality of pulley grooves engaging with the belt teeth on the outer periphery and having a larger diameter than the first toothed pulley. The toothed belt is a transmission system wound around the first toothed pulley and the second toothed pulley, The nominal pitch of the belt teeth is 2 mm, The belt teeth are bamboo teeth with a tooth flank angle of 5.0 degrees or more and 9.0 degrees or less, The speed ratio is 2.0 or more and less than 5.0, A transmission system in which each of the toothed belt and the first toothed pulley, and the toothed belt and the second toothed pulley satisfies the following formula (1). 1.5X - 0.31 < Y < X - 0.03 ··· (1) In formula (1), X is the PLD of the toothed belt, and Y is a value calculated by the following formula (2). Y = ((nominal pitch of toothed belt × number of pulley teeth T / π) - tip circle diameter) / 2 ··· (2)

[0011] Since this transmission system satisfies formula (1), smooth meshing between the toothed belt and the toothed pulley is ensured, and noise is suppressed.

[0012] [2] In the transmission system of [1] above, it is preferable that the PLD of the toothed belt is 0.280 mm or more and 0.360 mm or less. [3] In the transmission system of any one of [1] or [2] above, It is preferable that the PLD of the first toothed pulley and the second toothed pulley is 0.180 mm or more and 0.280 mm or less.

[0013] [4] In the transmission system of any one of [1] to [3] above, It is preferable that the belt width of the toothed belt is 20 mm or more.

[0014] [5] In the transmission system of any one of [1] to [4] above, It is preferable that the overlapping ratio ε of the belt teeth of the toothed belt is 0.80 or more.

[0015] [6] In the transmission system of any one of [1] to [5] above, It is preferable that the toothed belt has an arc-shaped tooth profile for the belt teeth.

[0016] [7] In any of the transmission systems [1] to [6] above, It is preferable that the toothed belt has a width of the belt teeth of 0.8 mm or more and 1.8 mm or less.

[0017] [8] In any of the transmission systems [1] to [7] above, The toothed belt has a belt shape, and includes a belt body having a rectangular base portion with a cross-sectional shape perpendicular to the longitudinal direction of the belt and a plurality of tooth portions provided at equal intervals on the inner peripheral side of the base portion at a predetermined interval and integrated with the base portion, a core wire embedded in the belt body, and a reinforcing cloth provided so as to cover the inner peripheral surface of the tooth portion. The toothed belt has a belt thickness of 1.1 mm or more, the thickness of the base portion is 0.30 mm or more and 1.6 mm or less, and it is preferable that the tooth height of the belt teeth is 0.50 mm or more and 1.0 mm or less.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. (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 (first toothed pulley) 22, a driven pulley (second toothed pulley) 24, and a toothed belt 10. The driving pulley 22 is a small-diameter pulley with a relatively small diameter, and the driven pulley 24 is a large-diameter pulley with a relatively large diameter.

[0019] 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 mesh 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.

[0020] Both the drive pulley 22 and the driven pulley 24 are provided with pulley grooves 21 that mesh 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.

[0021] The speed ratio of the transmission system 1 (number of teeth of the driven pulley 24 / number of teeth of the drive pulley 22) is 2.0 or more and less than 5.0. In this case, it is suitable for reducing noise while reducing the size of the motor. On the other hand, if the above speed ratio is less than 2.0, it may not be possible to ensure the desired assist force without increasing the size of the motor. Therefore, it becomes difficult to miniaturize the device provided with the transmission system 1. Also, if the above speed ratio exceeds 5.0, it becomes easy to increase the rotational speed of the motor, and it becomes difficult to suppress noise.

[0022] 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 m / s or more and 33 m / s or less. In the transmission system 1, the transmission capacity is, for example, 0.1 kW or more and 10 kW or less.

[0023] (Toothed Belt) FIG. 2 is a perspective view showing a part of the toothed belt 10. This toothed belt 10 constitutes the transmission system 1 according to the embodiment of the present invention. 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. FIG. 5 is a plan view showing a part of the inner peripheral surface of the toothed belt 10 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. The toothed belt 10 is a single-sided toothed belt.

[0024] The belt length of the toothed belt 10 (the belt length on the belt pitch line BL) is, for example, 400 mm or less. The preferred belt length is 100 mm or more and 400 mm or less. A more preferred belt length is 150 mm or more and 380 mm or less. The belt width Wb of the toothed belt 10 is, for example, 20 mm or more and 45 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 limited to this range.

[0025] The toothed belt 10 has a plurality of belt teeth 12 on its inner peripheral surface. The belt teeth 12 of the toothed belt 10 have a nominal pitch of 2 mm. Here, the nominal pitch has the same meaning as the "nominal pitch" used in JIS B 1857-1 etc. In the embodiment of the present invention, the range of the nominal pitch (tooth pitch Pb) of the toothed belt 10 is 2 ± 0.005 mm. The tooth profile of the belt teeth 12 is, for example, an arc tooth profile.

[0026] In FIG. 4, the double-headed arrow Wt is the width of the belt teeth 12. The width of the belt teeth 12 is defined by the dimension between the ends of a pair of adjacent tooth bottoms 15 sandwiching the belt teeth 12 in the belt circumferential direction. The width Wt of the belt teeth 12 is, for example, 0.8 mm or more and 1.8 mm or less.

[0027] (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 along its outer periphery at a predetermined pitch. In the toothed pulley 20, the number of teeth of the driving pulley 22 is, for example, 20 or more and 50 or less. Also, the number of teeth of the driven pulley 24 is, for example, 100 or more and 150 or less. The tooth profile of the pulley groove 21 is, for example, an arc tooth profile. The tooth profile of the pulley groove 21 corresponds to the tooth profile of the belt teeth 12. The toothed pulley 20 may, for example, be provided with a flange.

[0028] (Relationship between toothed belt and toothed pulley) In the transmission system 1, the belt teeth 12 of the toothed belt 10 are configured to mesh smoothly with the pulley grooves 21 of the toothed pulley 20. In the transmission system 1, each of the toothed belt 10 and the driving pulley 22, and the toothed belt 10 and the driven pulley 24 satisfies the following formula (1). 1.5X - 0.31 < Y < X - 0.03 ··· (1)

[0029] In formula (1), X is the PLD (PITCH LINE DIFFERENTIAL) of the toothed belt 10. The PLD of the toothed belt 10 is the distance between the pitch line and the bottom surface of the teeth in the toothed belt 10. The preferable PLD of the toothed belt 10 is 0.280 mm or more and 0.360 mm or less. In this case, smooth meshing between the toothed belt 10 and the toothed pulley 20 is easily ensured, and it is more suitable for suppressing noise. On the other hand, when the PLD of the toothed belt 10 is less than 0.280 mm, the interference becomes strong on the belt traveling direction side when the belt teeth and the pulley teeth engage, and the noise deteriorates. Also, when the PLD of the toothed belt 10 exceeds 0.360 mm, the interference becomes strong on the side opposite to the belt traveling direction when the belt teeth and the pulley teeth engage, and the noise deteriorates. The PLD of the toothed belt 10 is more preferably 0.300 mm or more and 0.340 mm or less.

[0030] In formula (1), Y is a value calculated by the following formula (2). Y = ((Nominal pitch of toothed belt × Number of pulley teeth T / π) - Tip circle diameter) / 2 ··· (2) Y represented by the above formula (2) is a value similar to the PLD of the toothed pulley 20. Since in the transmission system 1, X which is the PLD of the toothed belt 10 and Y which is similar to the PLD of the toothed pulley 20 are in a predetermined relationship, smooth meshing between the toothed belt 10 and the toothed pulley 20 is ensured and noise is suppressed.

[0031] The nominal pitch of the toothed belt 10 is 2 mm. Therefore, the above formula (2) can be rewritten as the following formula (2′). Y = ((2 × pulley tooth number T / π) - tip circle diameter) / 2 ··· (2′)

[0032] In the above formula (2), the value of Y is preferably 0.180 mm or more and 0.280 mm or less. In this case, smooth meshing between the toothed belt 10 and the toothed pulley 20 is easily ensured, and it is more suitable for noise suppression.

[0033] In the transmission system 1, the PLD of each of the drive pulley 22 and the driven pulley 24 is preferably 0.180 mm or more and 0.280 mm or less. In this case, smooth meshing between the toothed belt 10 and the toothed pulley 20 is easily ensured, and it is more suitable for noise suppression. On the other hand, if the PLD of the toothed pulley 20 is less than 0.180 mm, the tooth groove of the pulley becomes narrow, the interference position during meshing between the toothed belt 10 and the toothed pulley 20 becomes high, and the interference state deteriorates. Also, if the PLD of the toothed pulley 20 exceeds 0.280 mm, the tooth groove of the pulley expands, the interference position during meshing between the toothed belt 10 and the toothed pulley 20 becomes low, and the interference state deteriorates. The PLD of the toothed pulley 20 is more preferably 0.200 mm or more and 0.260 mm or less.

[0034] The PLD of the toothed pulley 20 is the radial distance between the pitch circle diameter and the tip circle diameter. In the transmission system 1, the PLD of each of the drive pulley 22 and the driven pulley 24 is preferably the same value.

[0035] The belt teeth 12 of the toothed belt 10 are lotus root teeth as shown in Fig. 5. In Fig. 5, θ is the angle of the tooth flanks of the belt teeth 12. The angle θ of the tooth flanks of the belt teeth 12, which are lotus root teeth, is 5.0 degrees or more and 9.0 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 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 5.0 degrees, the noise reduction effect by adopting lotus root teeth is poor. Also, vibration of the toothed belt is likely to occur. When the angle of the tooth flanks exceeds 9.0 degrees, the biasing force by the lotus root teeth becomes excessive, and the side surface of the toothed belt may wear due to contact between the side surface of the toothed belt and the flange of the pulley. Also, due to the increase in the biasing force, the rubbing noise between the flange and the meshing rubbing noise while receiving the biasing force become larger, so the noise becomes larger. The toothed pulley 20 that meshes with the toothed belt 10 also has lotus root teeth.

[0036] The overlapping ratio ε of the belt teeth 12 of the toothed belt 10, which are lotus root teeth, is preferably 0.80 or more. The reason for this is that in the case of a lotus root tooth belt, since the tooth flanks of the belt teeth are oblique (not 90°) with respect to the belt running direction, the lotus root teeth mesh sequentially from the teeth at the belt end, and before the meshing ends, the next tooth starts to mesh, so that the running state of the belt is stabilized.

[0037] The overlapping ratio ε of the above belt teeth refers to the ratio of the overlapping period between the period when one belt tooth meshes with the tooth groove of the pulley and the period when the next belt tooth meshes with the tooth groove of the pulley, and is calculated by the following formula (3). ε = Wb·tanθ / Pb ···(3) (In the formula, Wb is the width of the toothed belt, θ is the angle of the tooth flanks, and Pb is the tooth pitch of the toothed belt.)

[0038] (Configuration of the 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.

[0039] In Fig. 4, the double-headed arrow Sb represents the thickness of the base portion 11a. The thickness of the base portion 11a is, for example, 0.30 mm or more and 1.6 mm or less. A preferable thickness of the base portion 11a is 0.50 mm or more and 1.40 mm or less.

[0040] 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.

[0041] In Fig. 4, the double-headed arrow Hb represents the tooth height (tooth height of the belt teeth 12) of the belt teeth 12. The tooth height Hb of the belt teeth 12 is, for example, 0.50 mm or more and 1.0 mm or less. Here, the tooth height Hb of the belt teeth 12 refers to the distance in the belt thickness direction from the adjacent tooth bottom portion 15 to the apex of the tooth tip of the belt teeth 12 (see Hb in Fig. 4). In the toothed belt 10, at the tooth bottom portion 15, the core wire 13 embedded in the inner peripheral side portion of the base portion 11a of the belt body 11 is disposed immediately inside (belt outer peripheral side) of the reinforcing cloth 14.

[0042] The belt body 11 is composed of, for example, a rubber composition (crosslinked rubber composition) obtained by crosslinking an uncrosslinked rubber composition containing a rubber component and a rubber compounding agent by heating and pressurization. Examples of the rubber component include ethylene-α-olefin elastomers such as hydrogenated nitrile rubber (HNBR), chlorosulfonated polyethylene rubber, chloroprene rubber (CR), and ethylene-propylene-diene rubber (EPDM).

[0043] 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, etc. Examples of the above metal oxides include, for example, zinc oxide (zinc white), magnesium oxide, etc. 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.

[0044] 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, etc. These anti-aging agents may be used alone or in combination of two or more. It is preferable to use the above anti-aging agent in combination with a benzimidazole-based anti-aging agent and an aromatic secondary amine-based anti-aging agent. 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.

[0045] Examples of the above reinforcing materials include carbon black, silica, etc. It is preferable to use carbon black and silica in combination. Examples of the above carbon black include, for example, channel black, furnace black, thermal black, acetylene black, etc. Examples of the above furnace black include, for example, SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, N-234, etc. Examples of the above thermal black include, for example, FT, MT, etc. Carbon black may be used alone or in combination of two or more. It is preferable to use the carbon black alone or in combination with other carbon blacks.

[0046] The content of the carbon black 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. The content of the silica 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.

[0047] 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. It is preferable to use the polyether ester alone or in combination with other plasticizers. 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.

[0048] Examples of the co-crosslinking agent include trimethylolpropane trimethacrylate, m-phenylenedimaleimide, 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.

[0049] 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 alone may be used. When sulfur and an organic peroxide are used in combination as the above crosslinking agent, the total content of the above 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.

[0050] Examples of the core wire 13 include a glass core wire, an aramid core wire, a carbon core wire, and a steel core wire. These core wires are preferably composed of twisted yarns.

[0051] 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 each 0.15 mm or more and 0.80 mm or less. More preferably, the outer diameter φT and the outer diameter 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.

[0052] 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 provided so as to form a double helix.

[0053] The core wire 13 is arranged at intervals in the belt width direction and extends 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 with the core wire 13 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, the 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.

[0054] The core wire 13 may be subjected to an adhesion treatment to enhance 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.

[0055] Before the above-mentioned adhesion treatment, the core wire 13 may be subjected to a primer treatment. Examples of the primer treatment include a treatment in which the material is immersed in an epoxy solution and then heated, and a treatment in which the material is immersed in an isocyanate solution and then heated. These adhesion treatments and primer treatments are performed before the core wire is wound around the mold in the manufacturing method of the toothed belt described later.

[0056] 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.

[0057] The reinforcing fabric 14 preferably has elasticity. For example, a woven fabric using a woolly-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 0.3 mm or less.

[0058] An adhesion treatment for enhancing the adhesion force with the belt body 11 may be performed on the reinforcing fabric 14. 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 of these may be performed, or two or more may be performed.

[0059] Before the bonding treatment, the reinforcing fabric 14 may be subjected to a base treatment of being immersed in an epoxy solution and then heated, or a base treatment of being immersed in an isocyanate solution and then heated. These bonding treatments and base treatments are performed before the reinforcing fabric 14 is wound around the mold in the method for manufacturing the toothed belt described below.

[0060] (Method for manufacturing a toothed belt) The method for manufacturing the toothed belt 10 will be described in the order of steps. FIGS. 6 to 8 are diagrams for explaining the method for manufacturing the toothed belt 10. FIGS. 6 to 8 show only a part of the mold 30 for belt forming and the belt (including the belt material).

[0061] 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.

[0062] (1) Prepare the materials. The rubber component is kneaded, and further a rubber compounding agent is added and kneaded to obtain an uncrosslinked rubber composition. The obtained uncrosslinked rubber composition is molded to produce an uncrosslinked rubber composition sheet 111. At this time, as a molding method of the uncrosslinked rubber composition sheet 111, for example, calender molding or the like can be adopted.

[0063] Prepare the core wire 13 and the reinforcing fabric 14, and if necessary, perform a bonding treatment on each of them. Furthermore, the reinforcing fabric 14 is formed into a cylindrical shape.

[0064] (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. The unvulcanized rubber composition sheet 111 is wound in a plurality of sheets (two sheets in FIG. 6). As a result, 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 so that the alignment direction corresponds to the belt length direction.

[0065] (3) As shown in FIG. 7, a rubber sleeve 34 is placed over the unvulcanized slab 135 on the mold 30, 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. As a result, the unvulcanized slab 135 is pressed and heated on the mold 30 side. At this time, the unvulcanized rubber composition sheet 111 passes between the core wires 13, flows into each of the plurality of recesses 31 of the mold 30 while pressing the reinforcing cloth 14, and is crosslinked, thereby forming a crosslinked rubber composition 11 that constitutes the belt body. At the same time, the core wire 13, the reinforcing cloth 14, and the crosslinked rubber composition 11 are integrated. As a result, as shown in FIG. 8, a cylindrical belt slab 35 is formed.

[0066] (4) The inside of the vulcanizing kettle is depressurized to release the seal. Subsequently, the belt slab 35 formed between the mold 30 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.

[0067] (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, flange attachment, etc. as necessary.

Example

[0068] Hereinafter, embodiments of the present invention will be described more specifically with reference to examples, but the embodiments of the present invention are not limited to the following examples. Here, a transmission system including a toothed belt and a toothed pulley was manufactured, and a noise test was conducted on this transmission system.

[0069] (Toothed belt) Toothed belts (A) to (J) having the same configuration as the toothed belt 10 shown in FIGS. 2 to 5 and a pitch diameter of 2 mm were manufactured. Each toothed belt was manufactured by the method described above (see FIGS. 6 to 8). The toothed belt (A) has a belt width Wb of 22 mm and a belt circumference of 330 mm in a state where the compression ratio is 0%. The toothed belt (A) includes arrowhead teeth with a tooth rib angle of 6.7 degrees as belt teeth. In the toothed belt (A), the overlap ratio ε of the arrowhead teeth is 1.29.

[0070] The toothed belt (A) has a tooth height Hb of 0.76 mm and a total thickness Tb (Hb + Sb) of 2.1 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 1.300 mm, A is 0.172 mm, r bb is 1.300 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).

[0071] In the toothed belts (A) to (J), the belt body 11 has an EPDM rubber component. In the toothed belts (A) to (J), the core wire 13 is a glass core wire. This glass 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.

[0072] In the toothed belts (A) to (J), the reinforcing fabric 14 is a woven fabric. The warp and weft of this woven fabric are polyamide 66 fibers. By adjusting the thickness of this reinforcing fabric 14 or the strength of the winding load of the core wire, the PLD of the toothed belt 10 is adjusted. In the toothed belts (A) to (J), the materials constituting the belt body 11, the core wire 13, and the reinforcing fabric 14 were made the same.

[0073] (Toothed pulley) Toothed pulleys (A1) to (F1) and toothed pulleys (A2) to (F2) with different pulley groove shapes were manufactured. Toothed pulleys with the same alphabetical notation, such as toothed pulley (A1) and toothed pulley (A2), are paired toothed pulleys. Also, the toothed pulley with the number 1 after the alphabet is the driving pulley, and the toothed pulley with the number 2 after the alphabet is the driven pulley.

[0074] The toothed pulleys (A1) to (F1) and the toothed pulleys (A2) to (F2) were manufactured through a manufacturing process including gear cutting using a dedicated hob cutter made according to the shape of the pulley groove of each pulley. Here, the groove shapes of the paired driving pulley and driven pulley are the same.

[0075] The toothed pulleys (A1) to (F1) have the tip circle diameters described in Table 1 and have 40 teeth (40T). The toothed pulleys (A2) to (F2) have the tip circle diameters described in Table 1 and have 110 teeth (40T). The width of each toothed pulley is belt width + 4 mm. Each toothed pulley is made of stainless steel.

[0076] The dimensions of the pulley grooves of the toothed pulley (A1) and the toothed pulley (A2) are such that in the dimensions of the pulley groove shown in Fig. 10, Hp is 0.760 mm, R1 is 1.325 mm, A is 0.172 mm, and B g has dimensions of 1.300 mm. In Fig. 10, "Hp", "R1", and "B g」 corresponds to "H" described 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). Also, the toothed pulleys (B1) to (F1) are pulleys with the PLD of the toothed pulley (A1) changed, and the toothed pulleys (B2) to (F2) are pulleys with the PLD of the toothed pulley (A2) changed.

[0077] (Examples 1 to 8, Comparative Examples 1 to 7) Using the toothed belt 48, drive pulley 42, and driven pulley 44 of the combinations shown in Table 1, the transmission system 40 was configured. Figures 11A and 11B show the pulley layout of the transmission system 40. Figure 11A is a top view of the transmission system 40, and Figure 11B is a front view of the transmission system 40. The transmission system 40 was configured by winding the toothed belt 48 around a two-axis pulley having a drive pulley 42 and a driven pulley 44. In this transmission system 40, the SW (set weight) was fixed so that the belt tension would be 100 N. The speed ratio of this transmission system 40 is 2.75.

[0078] In the transmission system 40, the toothed belt 48 was run, and the noise level during running was measured. The measurement of the noise level was performed using a precision noise meter (manufactured by Lion Corporation, product name NL-52) having a sound collecting microphone 45. At this time, the sound collecting microphone 45 was installed at a position 25 mm laterally (in the belt width direction) from the side surface of the toothed belt 48 and 20 mm away from the center of the drive pulley toward the center of the driven pulley. In this evaluation, the average value of the noise level of the meshing primary sound measured when the rotational speed was changed from 500 rpm to 2000 rpm was used as the measured value.

[0079] Based on the measured values, the noise level was evaluated in four levels from AA to C. AA: 64 dB or less A: Exceeding 64 dB and equal to or less than 70 dB B: Exceeding 70 dB and equal to or less than 75 dB C: Exceeding 75 dB

[0080] The results are shown in Table 1 and FIG. 12. FIG. 12 shows the results of Examples 1 to 6 and Comparative Examples 1 to 4. In FIG. 12, the examples / comparative examples showing the results of AA are plotted as "◎", the examples / comparative examples showing the results of A are plotted as "〇", the examples / comparative examples showing the results of B are plotted as "△", and the examples / comparative examples showing the results of C are plotted as "×".

[0081]

Table 1

[0082] As shown in Table 1 and FIG. 12, it has become clear that by satisfying the above formula (1), the noise of the transmission system is suppressed.

[0083] It should be considered that all the embodiments disclosed this time are illustrative and not restrictive in any way. The scope of the rights of the present invention is indicated by the scope of claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims be included.

Explanation of Signs

[0084] 1, 40 Transmission system 10, 48 Toothed belt 11 Belt body (crosslinked rubber composition) 11a Base part 11b Tooth part 12 Belt teeth 13 Core wire 14 Reinforcing cloth 15 Tooth bottom part 20 Toothed pulley 21 Pulley groove 22, 42 Driving pulley 24, 44 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 plurality of belt teeth on its inner circumferential side; a first toothed pulley having a plurality of pulley grooves formed on its outer periphery to mesh with the belt teeth; a second toothed pulley having a diameter larger than that of the first toothed pulley, the second toothed pulley having a plurality of pulley grooves on its outer periphery that mesh with the belt teeth; a transmission system in which the toothed belt is wound around the first toothed pulley and the second toothed pulley, The nominal pitch of the belt teeth is 2 mm, The belt teeth are helical teeth with a tooth trace angle of 5.0 degrees or more and 9.0 degrees or less, The speed ratio is equal to or greater than 2.0 and less than 5.0, A transmission system in which the toothed belt and the first toothed pulley, and the toothed belt and the second toothed pulley each satisfy the following formula (1): 1.5X-0.31<Y<X-0.03...(1) In formula (1), X is the PLD of the toothed belt, and Y is a value calculated by the following formula (2). Y = ((nominal pitch of toothed belt × number of pulley teeth T / π) - tip diameter) / 2 (2)

2. 2. The transmission system according to claim 1, wherein the PLD of the toothed belt is equal to or greater than 0.280 mm and equal to or less than 0.360 mm.

3. 3. The transmission system according to claim 1, wherein the PLD of the first toothed pulley and the second toothed pulley is equal to or greater than 0.180 mm and equal to or less than 0.280 mm.

4. 3. The transmission system according to claim 1, wherein the toothed belt has a belt width of 20 mm or more.

5. 3. The transmission system according to claim 1, wherein the toothed belt has an overlap ratio ε of the belt teeth of 0.80 or more.

6. 3. The transmission system according to claim 1, wherein the toothed belt has belt teeth each having an arc tooth profile.

7. 3. The transmission system according to claim 1, wherein the toothed belt has a width of the belt teeth that is equal to or greater than 0.8 mm and equal to or less than 1.8 mm.

8. The toothed belt is a belt body including a base portion having a band shape and a rectangular cross section perpendicular to the belt longitudinal direction, and a plurality of teeth portions provided at equal intervals at an inner circumferential side of the base portion and integrated with the base portion; a core wire embedded in the belt body; a reinforcing cloth provided to cover the inner circumferential surface of the tooth portion, The toothed belt has a belt thickness of 1.1 mm or more, The thickness of the base is equal to or greater than 0.30 mm and equal to or less than 1.6 mm, 3. The transmission system according to claim 1, wherein the tooth height of the belt teeth is equal to or greater than 0.50 mm and equal to or less than 1.0 mm.

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