Toothed belt and belt drive mechanism

Abstract

A sprocket belt has a back, a core wire embedded in the back, a plurality of tooth portions arranged at a predetermined interval along a belt length direction on one side of a surface of the back, and a tooth cloth covering a surface of the tooth portions and a part of the surface of the back on one side, the core wire is a twisted rope including a high-strength glass fiber yarn, a pitch (Pt) between the tooth portions is 2.0 mm or more and 2.5 mm or less, a diameter (D) of the core wire is 0.15 mm or more and less than 0.30 mm, a ratio of a thickness of the back with respect to a thickness of the sprocket belt is 22.0% or more and 38.5% or less, the tooth portions are composed of a rubber composition, a hardness of the rubber composition at 23°C is 73° or more and 83° or less, and the tooth portions are formed in a shape in which a tooth top portion and two or more curved surfaces having a certain curvature connected to two side surfaces across the tooth top portion in the belt length direction are connected.

Description

Technical Field

[0001] This invention relates to toothed belts, such as toothed belts suitable for drive units of electrically powered sliding door (PSD) systems and belt drive mechanisms. Background Technology

[0002] Existing technical documents

[0003] The Powered Sliding Door (PSD) system (hereinafter referred to as PSD system) is a system that enables the sliding door of a passenger car (such as a hatchback or station wagon) to open and close electrically. The PSD system includes a drive unit (actuator) with a drive source (drive motor) located on the floor or side of the vehicle, and the sliding door is opened and closed via a tension body (cable or belt).

[0004] Recently, in order to meet the demands of users and the diversification of vehicle models, which have led to further requirements for smaller, lighter, more energy-efficient, quieter (reduced operating noise) devices and higher output of drive motors (increased drive torque with increased door weight), the PSD system, which replaces the gear-type reduction mechanism (first stage) of the drive unit with a belt-type reduction mechanism, has been adopted in various vehicle models with sliding doors, from light vehicles to ordinary cars.

[0005] The belt reduction mechanism of this drive unit includes: a drive pulley, which is disposed within the unit (housing) of the device and connected to the rotating shaft of the drive motor (capable of forward and reverse rotation); a driven pulley, which is connected to the driven shaft and has a diameter larger than that of the drive pulley; and a relatively small toothed belt (e.g., with a tooth pitch of about 2-3 mm) wound in a loop between the two pulleys. Furthermore, the distance between the shafts of the pulleys is relatively short (e.g., about 50 mm), and the shafts of both are fixed. Therefore, the toothed belt is mainly wound between the pulleys in a tension-free state (zero installation tension) to facilitate the assembly (belt installation) of the device (see reference). Figure 2 ).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 6096239

[0009] Patent Document 2: Japanese Patent No. 6641513

[0010] Patent Document 3: Japanese Patent No. 6748131

[0011] Patent Document 4: Japanese Patent Application Publication No. 2018-165514

[0012] Patent document 5: Japanese Patent No. 6324336. Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] (Topic 1)

[0015] The PSD system requires not only the ability to open and close the sliding door electrically, but also the ability to open and close the sliding door smoothly and manually to the same degree as the operability in vehicles without the PSD system (manual operability).

[0016] In particular, recently, due to the diversification of vehicle models equipped with PSD systems and the expansion of their application areas, it is also necessary to consider their use in extremely cold regions (such as continents) (see Patent Document 1, which describes a toothed belt with cold resistance). Therefore, it is required that even in extremely low temperature environments (-30 to -40°C), the flexibility (flexibility, winding towards the pulleys) of the belt wound between the pulleys in a tension-free state (zero installation tension) will not be excessively reduced, so as not to affect the manual operation of the sliding door.

[0017] Specifically, in the small toothed belts used in the drive unit (belt reduction mechanism) of the PSD system and wound in a tension-free state, it is necessary to ensure flexibility (flexibility, winding towards the pulley) even in extremely low temperature environments, and to ensure that the starting torque of the driven pulley of the belt reduction mechanism is sufficiently low even when the sliding door is opened and closed manually in extremely low temperature environments.

[0018] That is, compared with conventional belts designed for use in extremely low temperature environments (-30 to -40°C), the flexibility of the belt is further improved, and compared with the application of the conventional toothed belt to the reduction mechanism, the starting torque of the driven pulley of the belt reduction mechanism is required to be at a lower level when the sliding door is opened and closed manually in extremely low temperature environments.

[0019] (Topic 2)

[0020] Furthermore, in the small toothed belt that is wound in a tension-free state in the drive unit (belt reduction mechanism) of the PSD system, it is required that, along with the diversification of the models in which the PSD system is adopted, the transmission performance (without tooth skipping, etc.) can be ensured even when the drive motor torque is increased by an amount corresponding to the increase in the weight (load) of the sliding door (for example, from about 0.8 N·m in the past to about 1.5 N·m).

[0021] That is, compared with conventional belts designed to correspond to relatively low drive motor torque (e.g., around 0.8 N·m), it is required to ensure a higher level of belt transmission performance (such as resistance to tooth skipping).

[0022] Therefore, the purpose of this invention is to provide a toothed belt and a belt drive mechanism that can ensure the belt's flexibility in extremely low temperature environments and its drive performance, even when wound between pulleys in a tension-free state.

[0023] Technical solutions for solving the problem

[0024] This invention relates to a toothed belt, comprising: a backing; a core wire embedded in the backing; a plurality of teeth arranged at predetermined intervals on one side of the backing along the belt length direction; and a toothed cloth covering the surface of the teeth and a portion of the surface of the backing on one side. The core wire is a twisted rope comprising high-strength glass fiber filaments. The tooth pitch between the teeth is 2.0 mm or more and 2.5 mm or less. The diameter of the core wire is 0.15 mm or more and less than 0.30 mm. The thickness of the backing relative to the thickness of the toothed belt is 22.0% or more and 38.5% or less. The teeth are made of a rubber composition having a hardness of 73° or more and 83° or less at 23°. The teeth are formed in a shape where the tooth tip and two sides separated by the tooth tip in the belt length direction are connected by one or more curved surfaces with a certain curvature.

[0025] By making the core wire a twisted rope containing high-strength glass fiber filaments, a predetermined elastic modulus can be ensured in the toothed belt, taking into account both the bending and transmission performance of the toothed belt (especially its resistance to impact loads).

[0026] Furthermore, the pitch value, representing the interval between adjacent teeth (multiple tooth sections) along the belt length direction, corresponds to the scale of the belt teeth (the length of the teeth along the belt length direction and the tooth height). That is, the larger the pitch value, the larger the scale of similar belt teeth. By setting the pitch to a range of 2.0 mm to 2.5 mm, even when wound between pulleys under no tension, it is easy to balance the belt's bending and transmission performance (such as resistance to tooth skipping) in extremely low temperature environments.

[0027] In addition, by making the diameter of the core wire within the range of 0.15 mm or more and less than 0.30 mm, the flexibility of the strip in extremely low temperature environments can be ensured.

[0028] Furthermore, in relatively small toothed belts (tooth pitch of 2.0 mm or more and 2.5 mm or less), by suppressing the ratio of the thickness of the back to the thickness of the toothed belt (back thickness ratio) to a relatively low level of 22.0% or more and 38.5% or less, the belt's flexibility in extremely low temperature environments can be ensured.

[0029] In addition, by setting the hardness of the teeth, which are made of rubber composition, to a relatively high level of 73° or higher and 83° or lower, it is easy to ensure the transmission performance of the belt (especially the resistance to tooth skipping) when it is driven in a tension-free state.

[0030] Furthermore, by setting the shape of the teeth to an H-shaped tooth with a roughly semi-circular cross-section (so-called a circular tooth shape), it is possible to maximize, for each tooth pitch, the maximum length (Lbt) of the portion of the tooth that contacts the pulley groove on the side of the tooth (hereinafter referred to as the power transmission portion) in the belt length direction and the maximum height (Hbt) from the power transmission portion to the tooth tip. That is, it is possible to maximize the volume of the part of each tooth that contributes to power transmission.

[0031] Therefore, compared to the case where the tooth shape is formed as an S-shaped tooth (so-called STPD tooth shape), that is, a shape in which two sides are formed by two convex curved surfaces (arc surfaces) that bulge outwards and the tooth top as a flat surface are connected, the volume of the part of each tooth that helps to transmit power can be further increased. Accordingly, the rigidity of the tooth is further improved, and the transmission performance of the belt (especially the resistance to tooth skipping) can be easily ensured when it is driven in a tension-free state.

[0032] In addition, the present invention may also be characterized in that the diameter of the high-strength glass fiber filaments in the toothed belt is 6 to 9 micrometers.

[0033] By using high-strength glass fiber filaments (wires) with a diameter of 6 to 9 micrometers in the core wire, it is easy to produce high-strength glass core wires with a diameter ranging from 0.15 mm to less than 0.30 mm.

[0034] In addition, the present invention may also be characterized in that, in the above-mentioned toothed belt, the core wire is a single-twisted twisted rope.

[0035] By producing single-twisted core wires, it is easy to manufacture high-strength glass core wires with diameters ranging from 0.15 mm to less than 0.30 mm.

[0036] In addition, the present invention may also be characterized in that, in the toothed belt described above, the core wires are arranged in the belt width direction and embedded in the back, and the total value of the interval between adjacent core wires in the belt width direction is 20% or more and 35% or less relative to the belt width.

[0037] By setting the ratio of the total spacing between adjacent core wires in the belt width direction to the belt width to 20% or more and 35% or less, adequate rigidity (modulus of elasticity) can be ensured on the back of the toothed belt. Furthermore, even when the toothed belt is wound between pulleys without tension, it can reliably balance ensuring both the flexural strength of the toothed belt in extremely low-temperature environments and its transmission performance (durability, vibration resistance, and resistance to tooth skipping, etc.).

[0038] In addition, the present invention may also be characterized in that, in the above-mentioned toothed belt, the belt elastic modulus, defined by the belt tension (N) per 1 mm belt width relative to the belt elongation (%), is 30 N / % or more and less than 60 N / %.

[0039] If the elastic modulus of the belt is within the above range, it is easy to balance the belt's bending performance and its transmission performance (especially its resistance to impact loads).

[0040] In addition, the present invention may also be characterized in that, in the toothed belt described above, the back and the teeth are made of a rubber composition, the rubber composition comprising at least chloroprene rubber.

[0041] Based on the above structure, cold resistance can be ensured and relatively inexpensive neoprene rubber can be used to manufacture toothed belts.

[0042] In addition, the present invention may also be characterized in that the toothed belt described above is used such that the load on the pulleys when it is wound between the pulleys is 3 N·m or less.

[0043] To meet the drive motor torque required by the applied drive unit, the toothed belt can be specifically designed so that the load on the pulleys when wound between them is set to 3 N·m or less (equivalent to a safety factor of 2 times the drive motor torque (approximately 1.5 N·m)). Furthermore, when the toothed belt is used within the aforementioned load range, even when driven without tension, the belt's transmission performance (especially its resistance to tooth skipping) can be reliably ensured.

[0044] In addition, the present invention is a belt drive mechanism, comprising: a drive pulley driven to rotate by a drive source, a driven pulley, and the toothed belt described above wound around the drive pulley and the driven pulley in such a way that the load on the driven pulley is less than 3 N·m.

[0045] According to the above belt drive mechanism, even when the toothed belt is wound between the drive pulley and the driven pulley in a tension-free state, the belt's flexibility in extremely low temperature environments can be ensured, and the belt's transmission performance can be reliably guaranteed.

[0046] Invention Effects

[0047] This invention provides a toothed belt and a belt drive mechanism that can ensure the belt's flexibility in extremely low temperature environments and its drive performance, even when wound between pulleys without tension. Attached Figure Description

[0048] Figure 1 This is a cross-sectional perspective view of the toothed band involved in the implementation method.

[0049] Figure 2 This is an explanatory diagram of the belt drive mechanism involved in the implementation method.

[0050] Figure 3 This is an explanatory diagram of the toothed portion (H-shaped tooth) involved in the embodiment.

[0051] Figure 4 This is an explanatory diagram of a tooth section (H2M) with a pitch of 2.0 mm.

[0052] Figure 5 This is an explanatory diagram of a tooth section (H2.5M) with a pitch of 2.5mm.

[0053] Figure 6 This is an explanatory diagram illustrating the transmission performance of the teeth of the toothed belt according to the embodiment.

[0054] Figure 7 This is a cross-sectional view of the toothed belt in the width direction according to the embodiment.

[0055] Figure 8 This is an explanatory diagram of a biaxial torque measuring test machine used for starting torque measurement tests.

[0056] Figure 9 This is an explanatory diagram of a tooth with an S-shaped tooth profile (STPD tooth profile).

[0057] Figure 10 This is an illustration of the transmission performance of the toothed belt with S-shaped teeth. Detailed Implementation

[0058] The toothed belt 1 and belt drive mechanism 10 according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0059] (toothed band 1)

[0060] like Figure 1As shown, the toothed belt 1 has: a back 3, with a core wire 2 embedded in a spiral along the belt length direction; and a plurality of teeth 4 arranged at predetermined intervals along the belt length direction on the inner circumferential surface of the back 3 (corresponding to one side of the back 3). In this embodiment, the plurality of teeth 4 are integrally formed on the inner circumferential surface of the back 3. In addition, the teeth 4 extend along the belt width direction (i.e., the teeth 4 are straight teeth). Furthermore, the inner circumferential surface of the toothed belt 1, i.e., the surface of the teeth 4, and a portion of the inner circumferential surface of the back 3 (the portion where the teeth 4 are not provided) are formed (covered) by toothed fabric 5. In addition, the outer circumferential surface of the back 3 (corresponding to the other side of the back 3) is not covered by fabric or the like (backing fabric).

[0061] In addition, such as Figure 1 As shown, the spacing (tooth pitch Pt) between adjacent teeth 4 in the belt length direction is 2.0 mm or more and 2.5 mm or less. Furthermore, the value of the tooth pitch Pt also corresponds to the size of the scale of the tooth 4 (the length of the tooth 4 in the belt length direction and the tooth height Ht of the tooth 4). That is, the larger the tooth pitch Pt, the larger the scale of the tooth 4 is. For example, Figure 4 It refers to the tooth section with a pitch Pt of 2.0 mm. Figure 5 This refers to the tooth section with a pitch Pt of 2.5 mm. When the pitch Pt is between 2.0 mm and 2.5 mm, the tooth height Ht is approximately 0.88 mm to 1.10 mm.

[0062] In addition, with Figure 1 The "back thickness ratio," defined as the percentage of the thickness Tb of the back 3 relative to the thickness T of the toothed belt 1, is 22.0% to 38.5% when the tooth pitch Pt is 2.0 mm or more and 2.5 mm or less. Here, in this invention, the aforementioned "back thickness ratio" is defined as an indicator (substitute characteristic) representing the flexibility of the toothed belt.

[0063] When the tooth pitch Pt is 2.0 mm, the back thickness ratio is preferably 26.1% or more and 38.5% or less, more preferably 27.9% or more and 29.0% or less. When the tooth pitch Pt is 2.5 mm, the back thickness ratio is preferably 22.0% or more and 38.5% or less, more preferably 22.0% or more and 23.6% or less.

[0064] For example, when the tooth pitch Pt is 2.0 mm and the tooth height Ht is 0.88 mm, the thickness Tb of the back 3 is in the range of 0.31 to 0.55 mm.

[0065] In addition, with a tooth pitch Pt of 2.5 mm and a tooth height Ht of 1.10 mm, the thickness Tb of the back 3 is in the range of 0.31 to 0.69 mm.

[0066] In addition, the thickness Tb of the back 3 (the lower limit) must take into account the thickness of the toothed cloth 5 (e.g., the thickness in the cross section of the toothed strip 1 is 0.01 mm), and ensure that the thickness of the portion of the back 3 that is closer to the outer periphery than the core wire 2 is such that it will not become a manufacturing defect (defect of the back rubber) (at least ensure that the thickness is 0.04 mm).

[0067] In addition, the length (circumference) of the toothed belt 1 in the longitudinal direction is, for example, 200mm to 250mm. The length (width) of the toothed belt 1 in the width direction is, for example, 5mm to 15mm.

[0068] (Back 3 and Teeth 4)

[0069] The back portion 3 and the teeth portion 4 are composed of a rubber composition. The rubber components used in this composition include chloroprene rubber (CR), nitrile rubber, hydrogenated nitrile rubber (HNBR), ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), styrene-butadiene rubber, butyl rubber, and chlorosulfonated polyethylene rubber. These rubber components can be used alone or in combination. The rubber components constituting the back portion 3 and the teeth portion 4 are preferably polymers with good cold resistance. Chloroprene rubber is particularly preferred from the viewpoint of low cost. Furthermore, the same rubber composition can be used for both the teeth portion 4 and the back portion 3, or different rubber compositions can be used.

[0070] The rubber composition constituting the back 3 and the teeth 4 may contain various conventional additives (or compounding agents) as needed. Examples of additives include vulcanizing agents or crosslinking agents (e.g., oximes (quinone dioxime, etc.), guanidines (diphenylguanidine, etc.), vulcanizing aids, vulcanizing accelerators, vulcanizing retarders, reinforcing agents (carbon black, hydrated silica, etc.), metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), fillers (clay, calcium carbonate, talc, mica, etc.), plasticizers, softeners (paraffin oil, naphthenic oils, etc.), processing agents or processing aids (stearic acid, metal stearate salts, waxes, paraffin, etc.), anti-aging agents (aromatic amines, benzimidazole anti-aging agents, etc.), stabilizers (antioxidants, UV absorbers, heat stabilizers, etc.), lubricants, flame retardants, and antistatic agents. These additives can be used alone or in combination, and can be selected according to the type, purpose, and properties of the rubber component.

[0071] In addition, as plasticizers, ether-based, ester-based, ether-ester-based, phthalic acid-based, and adipic acid-based plasticizers can be used. Among them, adipic acid-based plasticizers that can impart a degree of softness to the rubber composition at extremely low temperatures that is not significantly different from that at room temperature when added in small amounts are the most preferred.

[0072] The hardness of the rubber composition (tooth rubber) constituting the tooth 4 is 73-83° according to JIS K 6253 (2012) and measured using a type A hardness tester at an ambient temperature of 23°C (23±2°C).

[0073] (The shape of tooth 4)

[0074] like Figure 3 and Figure 4 As shown, the tooth portion 4 is formed such that the tooth tip 41 is connected to the side surface 42 and side surface 43, which are separated by the tooth tip 41 in the belt length direction, by one or more curved surfaces (arc surfaces) with a certain curvature. That is, the cross-sectional shape of the tooth portion 4, including the belt length direction, is formed by the side surface 42, tooth tip 41, and side surface 43 of the tooth portion 4 being connected by one or more curves (arc lines) with a certain curvature. Specifically, the cross-sectional shape of the tooth portion 4 is a roughly semi-circular H-shaped tooth (round tooth shape). Furthermore, Figure 3 The tooth portion 4 is formed as a shape where the tooth tip 41 and the side surface 42 are connected by two curved surfaces having curvatures R2 and R3. Furthermore, in Figure 3 In the middle, the root portion 44 of the tooth portion 4 is connected to the bottom portion 45 of the tooth portion 4 by a curved surface with curvature R1.

[0075] Therefore, as Figure 3 and Figure 6 As shown, the maximum length (Lbt) of the portion of the tooth 4 that contacts the pulley groove 11b of the drive pulley 11 and the pulley groove 12b of the driven pulley 12 (hereinafter, the power transmission portion) in the side 42 of the tooth 4 in the belt length direction and the maximum height (Hbt) from the power transmission portion to the tooth tip 41 can both be set to the maximum per tooth pitch Pt. That is, the volume of the part of each tooth 4 that contributes to power transmission can be set to the maximum.

[0076] Therefore, instead of setting the shape of the teeth as Figure 9 and Figure 10 Compared to the S-shaped tooth (so-called STPD tooth), which is formed by connecting two side surfaces (arc surfaces) that bulge outwards and the tooth tip as a flat surface, the volume of the part of each tooth 4 that contributes to power transmission can be further increased. Figure 6 (The shaded part), accordingly, the rigidity of the tooth 4 is further improved, which can easily ensure the transmission performance of the belt (especially the anti-skid performance) when driven in a tension-free state.

[0077] (Core 2)

[0078] Core 2 is composed of a twisted rope formed by twisting multiple strands together. A single strand can be used to bundle and align filaments (long fibers). The filaments are made of high-strength glass fiber, and the diameter of core 2 is 0.15 mm or more and less than 0.30 mm. High-strength glass fiber is suitable as a material for core 2 because it has high strength, low elongation, and relatively low cost. There are no particular restrictions on the thickness of the filaments forming the twisted rope, the number of bundles of filaments, the number of strands, and the twisting method, but in order to obtain a high-strength glass core with a diameter of 0.15 mm or more and less than 0.30 mm, it is preferable to set the diameter of the high-strength glass fiber filament (wire diameter) to 6-9 micrometers and the twisting method to single twist.

[0079] As a high-strength glass fiber, a tensile strength of 300 kg / cm² is preferred. 2 The glass fibers mentioned above, especially those with a higher Si content than alkali-free glass fibers (E glass fibers), are shown in Table 1 below. Furthermore, the composition of E glass fibers is also listed in Table 1 below for comparison. Examples of such high-strength glass fibers include K glass fibers, U glass fibers (all manufactured by Nippon Glass Fiber Co., Ltd.), T glass fibers (manufactured by Nitto Bosho Co., Ltd.), R glass fibers (manufactured by Vetrotex Co., Ltd.), S glass fibers, S-2 glass fibers, and ZENTRON glass fibers (all manufactured by Owens Corning Fiberglass Co., Ltd.).

[0080] Table 1

[0081]

[0082] To improve adhesion to the backing 3, it is preferable to perform an adhesive treatment on the twisted rope used as the core wire 2. As an adhesive treatment, for example, a method is to immerse the twisted rope in a resorcinol-formaldehyde-latex treatment solution (RFL treatment solution), followed by heating and drying to uniformly form an adhesive layer on the surface. The RFL treatment solution is obtained by mixing an initial condensate of resorcinol and formalin with a latex. Examples of latexes used here include chloroprene, styrene-butadiene-vinylpyridine terpolymer (VP latex), hydrogenated nitrile, and NBR. Alternatively, another adhesive treatment method is to pretreat with an epoxy or isocyanate compound and then treat with the RFL treatment solution.

[0083] (Regarding the density of the core wire arrangement)

[0084] The core wire 2 is spirally embedded on the back 3, spaced at predetermined intervals d along the length of the tape and in the width direction. That is, as shown... Figure 7As shown, the core wires 2 are arranged on the back 3 at predetermined intervals d along the width direction. More specifically, the core wires 2 are preferably embedded in the back 3 such that the total value of the intervals d between adjacent core wires 2 in the width direction is a percentage (%) of 20% or more and 35% or less relative to the width W. Furthermore, the total value of the intervals d between adjacent core wires 2 in the width direction also includes the interval between the end of the toothed strip 1 and the core wire 2 (both ends). That is, the total value of the intervals d between adjacent core wires 2 in the width direction can be said to be obtained by subtracting the value of "the total core wire diameter D (core wire diameter D × number of core wires)" from the value of "width". Therefore, the percentage (%) of the total value of the intervals d between adjacent core wires 2 in the width direction relative to the width W can be replaced by the "relationship between core wire diameter D and core wire spacing SP" (refer to "Mathematical Formula 1" below). Here, the smaller the ratio (%) of the total distance d between adjacent core wires 2 in the width direction to the width W, the smaller the distance d between core wires 2, and thus it can be said that the density of the core wire arrangement becomes denser.

[0085] In addition, such as Figure 7 As shown, the core wires 2 are arranged in a spiral pattern from one end of the back 3 to the other, with the distance between the centers of the core wires 2, i.e., the spacing SP between each core wire, being a constant value. Furthermore, in this specification, as... Figure 7 As shown, the apparent number of core wires 2 arranged at a predetermined core wire spacing SP in the width direction is treated as the "number of core wires". That is, in the case where a core wire 2 is buried in a spiral shape, its spiral number is set as the "number of core wires".

[0086] Here, the "number of core wires" preferably only counts the number of wires that affect the strength (modulus of elasticity) of the belt (effective number of wires). Therefore, it is preferable not to count the core wires 2 that are cut and not circular when viewed in cross-section, which are located at one end and the other end in the width direction of the back 3 of the toothed belt 1, as the effective number of wires, and to count the core wires 2 that are not cut when viewed in cross-section as the effective number of wires.

[0087] Specifically, the calculated value obtained by dividing the wire spacing SP by the tape width W, rounded down to the nearest decimal, is considered a rough estimate of the "number of wires" (effective number of wires). For example, if the tape width W is 8.5mm and the wire spacing SP is 0.28mm, the calculated value is 30.36, and the "number of wires" (effective number of wires) is considered to be 30. Conversely, if the tape width W is 8.5mm and the wire spacing SP is 0.33mm, the calculated value is 25.76, and the "number of wires" (effective number of wires) is considered to be 25.

[0088]

Mathematical Formula 1

[0089]

[0090] (tooth cloth 5)

[0091] The toothed fabric 5 is preferably made of a woven fabric in which warp and weft yarns are interwoven in a certain regular pattern. The weaving method can be any of twill weave, satin weave, etc. The form of the warp and weft yarns can be any of the following: multifilament yarn (made by pulling and twisting long fibers together), monofilament yarn (a single long fiber), or short fiber yarn (spun yarn) (made by twisting short fibers together). When the warp or weft yarn is multifilament or short fiber yarn, it can be a mixed-twist yarn or a blended yarn using multiple fibers. The weft yarn preferably includes an elastic yarn with stretchability. For example, elastic yarn made of a material such as spandex composed of polyurethane, which has inherent stretchability, or processed yarn that has undergone stretching treatment (e.g., wool-like processing, crimping processing, etc.). Generally, elastic yarn is not used for the warp. Therefore, weaving is easy. Furthermore, as the toothed fabric 5, it is preferable to arrange the warp yarns of the woven fabric so that they extend in the width direction and the weft yarns extend in the length direction. This ensures the stretchability of the toothed fabric 5 in the length direction. Furthermore, the toothed cloth 5 can also be configured such that the weft yarns extend in the width direction of the belt and the warp yarns extend in the length direction of the belt. In this case, elastic yarn with stretchability can also be used as the warp yarns. The material of the fibers constituting the toothed cloth 5 can be any one or a combination of nylon, aramid, polyester, polybenzoxazole, cotton, etc.

[0092] To improve adhesion to the backing 3 and teeth 4, the fabric used as toothed cloth 5 can also undergo an adhesive treatment. As an adhesive treatment, a common method is to impregnate the fabric with resorcinol-formalin-latex (RFL solution), then heat and dry it to uniformly form an adhesive layer on the surface. However, this is not limited to this method. Besides pretreatment with epoxy or isocyanate compounds followed by treatment with RFL solution, a method can also be used where a rubber composition is dissolved in organic solvents such as methyl ethyl ketone, toluene, or xylene to prepare a rubber paste, and the fabric is impregnated and adhered to this rubber paste. These methods can be performed individually or in combination, and there are no particular limitations on the order or number of treatments.

[0093] (with elastic modulus)

[0094] Furthermore, details will be described later in the embodiments. The “belt elastic modulus” of the toothed belt 1, defined by the belt tension (N) per 1 mm belt width relative to the belt elongation (%), is preferably 30 N / % or more and less than 60 N / % (e.g., expression of the unit of belt elastic modulus: N / % / 1 mm width).

[0095] (Manufacturing method of toothed belt)

[0096] The toothed belt 1 according to this embodiment is manufactured, for example, by the following method (press-in process). First, a fiber fabric forming the toothed cloth 5 is wound around the outer peripheral surface of a cylindrical mold having a plurality of grooves (recesses) corresponding to the teeth 4 of the toothed belt 1. Next, a twisted rope constituting the core wire 2 is spirally wound around the outer peripheral surface of the wound fiber fabric at a predetermined interval (so that there is a predetermined interval in the axial direction of the cylindrical mold). Then, an unvulcanized rubber sheet forming the back 3 and the teeth 4 is wound around its outer peripheral side to form an unvulcanized belt forming body (unvulcanized laminate).

[0097] Next, with the uncured strip formed body positioned on the outer periphery of the cylindrical mold, a rubber sheath, serving as a vapor barrier material, is further applied to its outer side. Then, the strip formed body covered with the sheath and the cylindrical mold are housed inside a vulcanizing apparatus such as a vulcanizing tank. Inside the vulcanizing apparatus, the strip formed body is heated and pressurized, and the rubber composition of the uncured rubber sheet and the fibrous fabric are pressed into the groove (recess) of the cylindrical mold, forming teeth 4 of the desired shape. The rubber composition of the uncured rubber sheet is then vulcanized, forming a sleeve-shaped vulcanized formed body (vulcanized strip sleeve) integrating the rubber composition, fibrous fabric, and core wire 2. At this time, the fibrous fabric elongates along the contour shape of the teeth 4, becoming toothed cloth 5 disposed on the surface of the teeth 4. The vulcanized strip sleeve, after being demolded from the cylindrical mold, is cut to a predetermined width, thereby obtaining multiple toothed strips 1. In this process (press-in process), the same rubber composition is used to form the back 3 and the teeth 4.

[0098] Alternatively, the toothed belt 1 can also be manufactured by a preforming method according to the following steps.

[0099] First, fibrous fabric and unvulcanized rubber sheet are sequentially wound onto a cylindrical mold with multiple grooves (recesses). The mold is heated and pressurized to a temperature that softens the rubber composition (e.g., around 70–90°C), pressing the rubber composition and fibrous fabric into the grooves (recesses) of the cylindrical mold to form teeth 4, thus obtaining a preform. Next, a core wire 2 is spirally wound onto the outer circumferential surface of the obtained preform. Then, an unvulcanized rubber sheet constituting the back 3 is wound onto its outer circumferential surface to form an unvulcanized strip (unvulcanized laminate).

[0100] Furthermore, a vulcanized molded body (vulcanized belt sleeve) is then formed using the same steps as the manufacturing method described above. In addition, in this preforming method, since the teeth 4 are pre-formed before vulcanization, it is not necessary to flow or extrude the unvulcanized rubber from the back side to the tooth side through the gaps between the core wires 2 arranged at a predetermined spacing to form the teeth 4 during vulcanization. Therefore, the distance (spacing) between adjacent core wires can be reduced. In this preforming method, the rubber compositions constituting the back 3 and the teeth 4 can be the same rubber composition or different rubber compositions. For example, if the rubber composition constituting the back 3 is a rubber composition whose hardness after vulcanization is lower than that of the rubber composition constituting the teeth 4, and the toothed belt 1 is manufactured using this preforming method, the rigidity of the back 3 is further reduced, and the flexibility of the toothed belt 1 can be further improved.

[0101] (Belt drive mechanism 10)

[0102] like Figure 2 As shown, the belt drive mechanism 10 mainly consists of a drive pulley 11 connected to the rotating shaft (capable of forward and reverse rotation) of the drive motor (drive source), a driven pulley 12 connected to the driven shaft with a pitch diameter approximately 5 times larger than the drive pulley 11 at a reduction ratio of approximately 5, and a toothed belt 1 wound in an annular shape between the drive pulley 11 and the driven pulley 12.

[0103] The distance between the shafts of the drive pulley 11 and the driven pulley 12 is fixed, for example, about 50 mm. In addition, in order to ensure the installability of the toothed belt 1, the toothed belt 1 is wound between the drive pulley 11 and the driven pulley 12 in a tension-free state, so the toothed belt 1 will have some slack after installation.

[0104] In order to prevent the toothed belt 1 from falling off when it is wound in a tensionless state, both the drive pulley 11 and the driven pulley 12 are provided with flanges on one side of the width direction of the pulley groove (flange 11a of the drive pulley 11 and flange 12a of the driven pulley 12).

[0105] The drive motor torque is set to approximately 1.5 N·m. The toothed belt 1 is designed (configured) so that when the toothed belt 1 is wound without tension between the drive pulley 11 and the driven pulley 12 of the belt drive mechanism 10, it can be used within a range of less than 3 N·m (safety factor 2 times).

[0106] (The effect of the above structure)

[0107] (High-strength glass core wire)

[0108] In the aforementioned toothed belt 1, the core wire 2 is a twisted rope containing high-strength glass fiber. This ensures a belt elastic modulus of 30 N / % or more and less than 60 N / % . Furthermore, it allows for a balance between the flexibility and transmission performance (especially the impact load resistance) of the toothed belt 1.

[0109] (tooth pitch Pt)

[0110] In addition, by setting the tooth pitch Pt of the toothed belt 1 to 2.0 mm or more and 2.5 mm or less, even when wound between the drive pulley 11 and the driven pulley 12 in a tensionless state, the belt's bending and transmission performance (such as resistance to tooth skipping) in extremely low temperature environments can be improved.

[0111] If the tooth pitch Pt is less than 2.0 mm, the scale (volume) of tooth 4 becomes too small and is unrelated to the shape of tooth 4 (even if the shape of tooth 4 is set to the H tooth shape described later), the rigidity of tooth 4 becomes too low, and the transmission performance may not be guaranteed (easily causing tooth skipping and missing teeth).

[0112] On the other hand, if the tooth pitch Pt exceeds 2.5 mm, the proportion of the belt portion (the thinnest part of the belt, including the tooth bottom 45) in the meshing portion of the toothed belt 1 with the drive pulley 11 and driven pulley 12 (the winding portion of the toothed belt 1 relative to the drive pulley 11 and driven pulley 12) is too small, which may make it impossible to ensure the belt's flexibility in extremely low temperature environments. In addition, it is difficult to correspond with small-diameter pulleys (drive pulley 11), making it difficult to apply the toothed belt 1 to belt drive mechanisms 10 (belt reduction mechanisms) designed with relatively large reduction ratios (e.g., around 5).

[0113] (Diameter of core wire 2)

[0114] If the diameter of the core wire 2 of the toothed belt 1 is greater than 0.15 mm and less than 0.30 mm, the belt's flexibility in extremely low temperature environments can be ensured.

[0115] When the diameter of the core wire 2 is less than 0.15 mm (for example, in the case of high-strength glass core wire, filament diameter of 9 micrometers, single twist of twist structure 1 / 0, and core wire diameter of 0.14 mm), the core wire strength is insufficient, and the core wire 2 may break when the core wire 2 is subjected to tension accompanied by impact during the manufacturing process of the belt.

[0116] On the other hand, when the diameter of the core wire 2 is 0.30 mm or more (for example, in the case of high-strength glass core wire, wire diameter of 9 micrometers, twisted structure 3 / 0 single twist, and core wire diameter of 0.30 mm), the core wire itself has poor flexibility compared to the core wire 2 with a diameter of less than 0.30 mm, so it may not be possible to ensure the flexibility of the belt in extremely low temperature environments.

[0117] (Back thickness ratio)

[0118] The ratio of the thickness Tb of the back 3 to the thickness T of the toothed belt 1 (back thickness ratio) is set to 22.0% to 38.5% when the tooth pitch Pt is 2.0 mm or more and 2.5 mm or less.

[0119] The flexibility (softness) of a small toothed belt 1 (tooth pitch Pt of 2.0 mm or more and 2.5 mm or less) when wound without tension between the drive pulley 11 and the driven pulley 12 (especially small-diameter pulleys) is related not only to the softness of the portion including the tooth base 45 (the thinnest part of the belt), but also to the ease of elastic deformation in the bending direction of the portion including the tooth portion 4. Therefore, a "back thickness ratio" is set as an indicator (substitute characteristic) for representing the flexibility of the belt.

[0120] By suppressing the back thickness ratio to a relatively low level within the aforementioned range (a low level not found in conventional (Patent Documents 1 to 5) belts), the flexibility of the belt in extremely low temperature environments can be ensured.

[0121] Furthermore, the portion of the back 3 that is closer to the outer periphery than the core wire 2 must also have a minimum thickness of 0.04 mm. If the thickness is less than 0.04 mm, defects such as cracks may occur on the back side of the strip after manufacturing.

[0122] When the back thickness ratio is less than 22.0%, considering the thickness of the toothed cloth 5 (e.g., 0.1 mm in the cross section), even if the diameter of the core wire 2 is at the lower limit level (e.g., 0.17 mm), it is impossible to ensure that the thickness of the portion of the back 3 that is closer to the outer periphery of the core wire 2 is not to the point of being a manufacturing defect (defective back rubber) (at least 0.04 mm). It may be impossible to manufacture the toothed belt 1 using core wire 2 with a wire diameter of 0.15 mm or more.

[0123] On the other hand, when the back thickness ratio exceeds 38.5%, the rigidity of the back 3 becomes too large, and depending on the diameter of the core wire 2 and the hardness of the rubber composition constituting the back 3, it may be impossible to ensure the flexibility of the belt in extremely low temperature environments.

[0124] (Hardness of the rubber composition constituting tooth 4)

[0125] The portion of the toothed part 4, excluding the toothed cloth 5, is made of a rubber composition (toothed rubber) with a hardness of 73° or higher and 83° or lower as measured at 23°C (using a type A hardness tester).

[0126] By suppressing the hardness of the toothed rubber to a relatively high level within the aforementioned range, it is easy to ensure the belt's transmission performance (especially its resistance to tooth skipping) when driven under tension-free conditions.

[0127] If the rubber hardness of tooth 4 is less than 73° at 23°C, the rigidity of tooth 4 is too low. Even if the shape of tooth 4 is H-shaped (round tooth), the transmission performance may not be guaranteed (it is easy to cause tooth skipping).

[0128] On the other hand, when the rubber hardness of the tooth 4 exceeds 83° at 23°C, in the toothed belt 1 (which is made of the same rubber composition as the tooth 4 and the back 3) manufactured by the usual method (so-called pressing method), the rigidity of the back 3 becomes too high in the extremely low temperature environment, depending on the diameter of the core wire 2 and the back thickness ratio, which may not be able to ensure the flexibility of the belt in the extremely low temperature environment.

[0129] (The shape of tooth 4)

[0130] The cross-sectional shape of the tooth portion 4, which includes the tooth portion 4, along its length direction is formed by connecting the side 42, the tooth tip 41, and the side 43 of the tooth portion 4 with one or more curves (arcs) having a certain curvature (the shape of the tooth portion 4 is set as follows). Figure 3 and Figure 6 The cross-sectional shape shown is an approximately semi-circular H-shaped tooth (the so-called round tooth shape).

[0131] Therefore, the shape of the tooth 4 is set as Figure 9 and Figure 10 Compared to the S-shaped tooth (so-called STPD tooth), which is formed by connecting two side surfaces (arc surfaces) that bulge outwards and the tooth tip as a flat surface, the volume of the part of each tooth 4 that contributes to power transmission can be further increased. Figure 6 (The shaded part), accordingly, the rigidity of the tooth 4 is further improved, which can easily ensure the transmission performance of the belt (especially the anti-skid performance) when driven in a tension-free state.

[0132] (Diameter of core wire 2)

[0133] By using high-strength glass fiber filaments (wires) with a diameter of 6 to 9 micrometers in core wire 2, it is easy to produce high-strength glass core wires with a diameter of 0.15 mm or more and less than 0.30 mm.

[0134] (Twisting method of core wire 2)

[0135] By producing a single-twisted core wire 2, it is easy to manufacture high-strength glass core wires with a diameter of 0.15 mm or more and less than 0.30 mm.

[0136] (Density of core wire arrangement)

[0137] By setting the ratio (%) of the total value of the spacing d between adjacent core wires 2 in the belt width direction to the belt width W (the density of the core wire arrangement) to be more than 20% and less than 35%, appropriate rigidity (modulus of elasticity) can be ensured on the back 3 of the toothed belt 1. Furthermore, even when the toothed belt 1 is wound between the drive pulley 11 and the driven pulley 12 in a tension-free state, it is possible to reliably balance ensuring the belt's flexibility in extremely low temperature environments and ensuring the belt's transmission performance (durability, vibration resistance, and resistance to tooth skipping, etc.).

[0138] Furthermore, in this specification, the ratio (%) of the total value of the spacing d between adjacent core wires 2 in the width direction to the width W is expressed as the "core wire arrangement density". The smaller the value of the core wire arrangement density (%), the denser the core wire arrangement.

[0139] If the density of the core wire arrangement is less than 20%, the density of the core wire arrangement becomes too dense, and the spacing d between adjacent core wires becomes too narrow (e.g., less than 0.05 mm). When manufacturing the tape, it is difficult for the rubber to flow around the core wire, which may result in poor molding (the core wire is not supported by the rubber).

[0140] On the other hand, if the density of the core wire arrangement exceeds 35%, the density of the core wire arrangement becomes too sparse. Depending on the diameter of core wire 2 (which is close to the upper limit), the elastic modulus is insufficient, which may impair the synchronous (meshing) transmission (anti-skipping tooth performance) and may fail to ensure durability and vibration resistance.

[0141] (with elastic modulus)

[0142] If the elastic modulus of the toothed belt 1, defined by the belt tension (N) per 1 mm belt width relative to the belt elongation (%), is greater than 30 N / % and less than 60 N / %, it is easy to balance the belt's flexibility and its transmission performance (especially its resistance to impact loads).

[0143] If the elastic modulus is below 30 N / %, the impact load resistance performance decreases. Even when the toothed belt 1 is wound without tension between the drive pulley 11 and the driven pulley 12, when an impact load (tension) is applied to the toothed belt 1 (e.g., when a sliding door is opened or closed forcefully by hand), belt failures such as missing teeth (tooth damage) may easily occur. Furthermore, as will be clear from the evaluation of the embodiments described later, regarding ensuring the resistance to tooth skipping, when the toothed belt 1 is wound without tension between the drive pulley 11 and the driven pulley 12, increasing the rigidity of the teeth 4 of the toothed belt 1 (the relationship between the rubber hardness of the teeth 4 and the shape of the teeth 4) is more effective than increasing the level of the elastic modulus of the belt.

[0144] On the other hand, when the elastic modulus of the belt is 60 N / % or more, the bending stress (flexural elastic modulus) of the toothed belt 1 becomes too large along with the elastic modulus (tensile elastic modulus) of the toothed belt 1. Therefore, it may be impossible to ensure the bending properties of the belt that is wound between the drive pulley 11 and the driven pulley 12 in a tension-free state under extremely low temperature conditions.

[0145] (Rubber composition)

[0146] The rubber composition constituting the back 3 and the teeth 4 contains at least neoprene rubber, thereby ensuring cold resistance, and using relatively inexpensive neoprene rubber to manufacture the toothed belt 1.

[0147] (Load on driven pulley 12)

[0148] In the belt drive mechanism 10, the toothed belt 1 is used such that the load on the driven pulley 12 when it is wound between the drive pulley 11 and the driven pulley 12 is less than 3 N·m.

[0149] In order to correspond to the required drive motor torque in the belt drive mechanism 10, the load of the driven pulley 12 when the toothed belt 1 is wound between the drive pulley 11 and the driven pulley 12 is set to less than 3 N·m (in other words, the target value of the skipped tooth torque is more than 3 N·m) based on a safety factor of 2 times the drive motor torque (about 1.5 N·m). The toothed belt can be specifically designed.

[0150] Furthermore, when the toothed belt 1 is used within the aforementioned load range, even when driven without tension, the belt's flexibility in extremely low temperature environments can be ensured, and the belt's transmission performance can be reliably guaranteed.

[0151] Example

[0152] In this invention, even when applied to a belt drive mechanism in which the toothed belt is wound in a tension-free state, it is necessary to take into account both the bending properties of the toothed belt (rotational operability of the manual driven pulley) and the transmission performance of the toothed belt (resistance to tooth skipping, etc.) in extremely low temperature environments.

[0153] Therefore, in this embodiment, toothed belts (hereinafter referred to as each test subject) involved in Examples 1 to 33 and Comparative Examples 1 to 18 were prepared, and comparative verification was carried out by measuring the elastic modulus of the belt, testing the starting torque (-30℃, -40℃), and conducting a runout test.

[0154] Furthermore, the present invention will be described in more detail below based on embodiments, but the present invention is not limited to these embodiments.

[0155] [Materials Used]

[0156] (Core wire)

[0157] As the core wires for each test subject, twisted ropes with the structures shown in Table 2, namely A1 to A7, were fabricated.

[0158] The A1 twisted rope is made according to the following steps. 6-micron diameter strands of glass fiber (U-glass fiber) filaments, designated UCDE-300 as described in JIS R 3413 (2012), are bundled and aligned to form two strands. These two strands are then immersed for 3 seconds in an RFL solution (18–23°C) with the composition shown in Table 3 below, and then heated and dried at 200–280°C for 3 minutes to form a uniform adhesive layer on the surface. After this adhesive treatment, the two strands are initially twisted at 16 twists / 10cm without further twisting to prepare a single-twist twisted rope with a diameter of 0.17mm.

[0159] The twisted ropes of A2 to A7 have different materials for the yarn (K glass fiber and E glass fiber, except for U glass fiber), diameter of the yarn (7 micrometer, 9 micrometer, and 10 micrometer diameter, except for 6 micrometer diameter), and composition of the core yarn (3 strands and 1 strand, except for 2 strands). Otherwise, they are made in the same way as A1, as shown in Table 2, and are single-twist twisted ropes with diameters of 0.20 mm, 0.26 mm, 0.30 mm, and 0.14 mm.

[0160] Table 2

[0161] A1 A2 A3 A4 A5 A6 A7 Material U-glass fiber U-glass fiber U-glass fiber K glass fiber K glass fiber E glass fiber K glass fiber Wire diameter (μm) 6 7 6 7 9 7 10 Names of silk threads UCDE-300 UCE-225 UCDE-300 KCE-225 KCG-150 ECE-225 KCH-150 structure 2 / 0 2 / 0 3 / 0 2 / 0 3 / 0 2 / 0 1 / 0 Number of twists (per 10cm) 16 16 16 16 16 16 16 Twisting method Single twist Single twist Single twist Single twist Single twist Single twist Single twist Core wire diameter (mm) 0.17 0.20 0.26 0.20 0.30 0.20 0.14

[0162] Table 3

[0163] Quality resorcinol 1.35 Formalin (solid content concentration: 37%) 1 Vinylpyridine latex (solids concentration: 40%) 130 water 50

[0164] (Dental cloth)

[0165] The fiber fabric used in the dental cloth of each test subject has one of the following composition.

[0166] The composition consists of 66 nylon weft yarns and 66 nylon warp yarns. The yarn composition is 44 dtex wool-like processed yarn for weft yarns and 44 dtex warp yarns. The weave structure is twill weave. Furthermore, the toothed fabric with the above structure was subjected to RFL treatment using the RFL treatment solution shown in Table 3. Then, the same rubber composition as the uncured rubber sheet shown in Table 4 was bonded with rubber paste dissolved in toluene, and the rubber composition sheets with the composition shown in Table 4 were laminated and coated.

[0167] (Rubber composition)

[0168] The rubber compositions (7 types of C1 to C7) shown in Table 4 were mixed using a Banbury mixer, and the mixed rubber was passed through calendering rolls to form calendered rubber sheets of a predetermined thickness to produce uncured rubber sheets for forming the back and teeth of each test subject.

[0169] Furthermore, the components marked with ※ in Table 4 are as follows. Additionally, except for C5 (the cold-resistance grade of rubber composition using H-NBR), all C1 to C7 rubber compositions contain adipic acid-based plasticizers. Therefore, based on the results of the physical property tests on the rubber compositions described later (especially the physical property tests for low-temperature impact embrittlement temperature and Gemann torsion test temperature) (refer to Table 4), it can be seen that if the rubber composition constituting the toothed band (especially the back) is selected from the C1 to C7 compositions, the curing of the rubber composition constituting the toothed band (especially the back) can be suppressed even after prolonged exposure to extremely low temperatures. Therefore, it can be expected that the softness of the toothed band at extremely low temperatures will not differ significantly from that at room temperature (specifically, the rubber hardness at -30°C is approximately +0 to +4° compared to the rubber hardness at 23°C).

[0170] Table 4

[0171]

[0172] ※1 Mitsui Chemicals Co., Ltd. "EPT"

[0173] ※2 Denka "PM-40"

[0174] *3 "Zetpole 4310" manufactured by ZEON Corporation of Japan

[0175] *NOCRAC MB, manufactured by 4 major emerging chemical industrial companies.

[0176] *N-Cyclohexyl-2-benzothiazole sulfenamide manufactured by five major emerging chemical companies.

[0177] ※6. "SEAST3" manufactured by Tokai Carbon Co., Ltd.

[0178] ※7. Three types of zinc oxide manufactured by Zhengtong Chemical Industry Co., Ltd.

[0179] (Physical property testing of rubber compositions)

[0180] For each rubber composition comprising C1 to C7, after mixing, unvulcanized rubber sheets were prepared and vulcanized at 161°C for 25 minutes to obtain vulcanized rubber sheets. Furthermore, predetermined test pieces were prepared for the physical property tests of the rubber compositions (the rubber hardness test, low-temperature impact embrittlement test, and Giman torsion test, described later). For the rubber compositions comprising C1 to C7, the rubber hardness test, low-temperature impact embrittlement test, and Giman torsion test were conducted using the detailed methods described below as physical property tests for the rubber compositions. The test results are shown in Table 4.

[0181] (Rubber hardness test)

[0182] Here, the rubber hardness test of the rubber composition (vulcanized rubber sheet) was carried out in accordance with JIS K 6253 (2012), and the hardness was measured using a type A hardness tester at an ambient temperature of 23°C.

[0183] If the hardness of the rubber at room temperature is less than 73°, the rigidity of the toothed belt (especially the teeth) will decrease excessively in extremely low temperature environments, resulting in the inability to ensure the predetermined resistance to tooth skipping (tooth skipping torque).

[0184] On the other hand, if the temperature exceeds 83°, the rigidity of the toothed belt (especially the back) will increase excessively in extremely low temperature environments, resulting in a problem that the bending (starting torque) when the belt is wound onto pulleys, etc., cannot be guaranteed.

[0185] (Low-temperature impact embrittlement test)

[0186] The low-temperature impact embrittlement test was conducted according to JIS K 6261 (2006), and the low-temperature impact embrittlement temperature was determined. Furthermore, the smaller the expressed value of the low-temperature impact embrittlement temperature, the better the softness can be maintained at lower temperatures, and the higher the cold resistance (low-temperature softness). The samples (test pieces) for the low-temperature impact embrittlement test were strips measuring 40.0 mm × 6.0 mm × 2.0 mm.

[0187] (Giman torsion test)

[0188] In the Gemann torsion test, conducted according to JIS K 6261 (2006), the T10 of the Gemann torsion test, which is the temperature at which the torsional stiffness is 10 times the value at 23°C, was determined. The smaller the temperature value of the T10 of the Gemann torsion test, the better the flexibility can be maintained at lower temperatures, and the better the cold resistance (low-temperature flexibility).

[0189] [Manufacturing of toothed belts]

[0190] Using the core wires (bonded products) of A1 to A7 described in the above-described materials, the toothed cloth (bonded products), and the rubber compositions (uncured rubber sheets) of C1 to C7, each test subject (each toothed belt) was manufactured using the conventional pressing method described in the above embodiments. Furthermore, vulcanization was performed at 161°C for 25 minutes. In addition, to achieve a predetermined back thickness, the back of the vulcanized belt sleeve was ground to a certain thickness and then cut into a certain width to obtain each test subject (each toothed belt).

[0191] Since each test specimen (each toothed belt) was manufactured using a conventional pressing method, both the back and the teeth were made of the same rubber composition. Therefore, in each test specimen (each toothed belt), the hardness of the rubber composition constituting the back was approximately the same as the hardness of the rubber composition constituting the teeth.

[0192] The external dimensions and shape of the fabricated toothed strip (test subject)

[0193] (Common external dimensions and shape)

[0194] The belt has a width of 8.5mm, a circumference of approximately 230mm, and a toothed cloth thickness (thickness in the belt cross-section) of 0.1mm.

[0195] (Different appearance sizes and shapes)

[0196] Tooth pitch (1.5mm, 2.0mm, 2.5mm, 3.0mm), back thickness ratio (back thickness, belt thickness), tooth profile (H-shaped tooth, S-shaped tooth), number of teeth (153 teeth for 1.5mm tooth pitch, 115 teeth for 2.0mm tooth pitch, 92 teeth for 2.5mm tooth pitch, 77 teeth for 3.0mm tooth pitch)

[0197] (The shape of the teeth)

[0198] like Figure 3 and Figure 4 As shown, the shape of the teeth of each test subject in this embodiment is a shape called H-tooth (circular tooth) with a roughly semi-circular cross-sectional shape. The shape of the teeth (including the shape of the cross-section along the length direction) is such that the two sides of the teeth and the tooth tip have a certain curvature ( Figure 3 The shape is formed by connecting two curved surfaces (circular arc surfaces) (R2 and R3). Furthermore, the root of the tooth has a certain curvature ( Figure 3 The curved surface of R1 is connected to the bottom of the tooth.

[0199] like Figure 9 and Figure 10As shown, the teeth of each test specimen used as a comparison object have a shape referred to as S-tooth profile (STPD profile), which has two sides formed by curved surfaces (arc surfaces) connected by a flat surface. The tooth tip is a flat surface, and both sides are convex curved surfaces that bulge outwards. More specifically, the sides, in a cross-section including the length direction, are shaped by smoothly connecting two arcs. In addition, the tooth root is connected to the tooth base by a curved surface with a certain curvature.

[0200] [Evaluation of Toothed Belts: Items, Methods, Benchmarks]

[0201] For each test specimen shown in Tables 6 to 16, in order to confirm whether a toothed belt capable of solving the problem of this application was obtained, the belt performance (elastic modulus, starting torque (-30℃, -40℃), and skipping torque) was verified.

[0202] [With elastic modulus]

[0203] (Testing machine)

[0204] It uses Autograph (manufactured by Shimadzu Corporation, "AGS-J10kN").

[0205] (Experimental Methods)

[0206] A pair of pulleys (30 teeth) are installed on the lower fixing part and the upper force sensor connection part of the Autograph, and the toothed belt is hung between the pulleys. Next, the upper pulley is raised to apply tension (about 10 N) to the point that the toothed belt is not slack. Taking the position of the upper pulley in this state as the initial position, the upper pulley is raised at a speed of 10 mm / min. In the stress-strain curve (SS line graph) showing the relationship between the belt tension (N) and the belt elongation (%) measured at this time, the value of the belt tension (N) relative to the belt elongation (%) is calculated based on the slope (average slope) of the straight line in the region of the relatively linear relationship (N / %), and the value converted to 1 mm of belt width (N / % / 1 mm width) is taken as the belt elastic modulus (tensile elastic modulus).

[0207] (Judgment Criteria)

[0208] As an indicator for judging whether the belt has both flexibility (and thus the manual operation of the sliding door) and transmission performance (especially impact resistance), the value of the belt's elastic modulus is used (if the value is too small, the impact resistance of the belt cannot be guaranteed; if the value is too large, the flexibility of the belt cannot be guaranteed).

[0209] When the value of the elastic modulus (N / % / 1mm width) is 30 or more and less than 60, it is evaluated as being able to balance the bending and transmission performance (especially the impact load resistance) of the toothed belt, and is judged as 'a'.

[0210] When the value of the elastic modulus (N / % / 1mm width) is 25 or higher but less than 30, from the point of view of balancing the bending and transmission performance (especially the impact load resistance) of the toothed belt, it is evaluated as slightly worse and is judged as b.

[0211] If the value of the elastic modulus (N / % / 1mm width) is less than 25 or greater than 60, it is evaluated as being unable to balance the bending performance and transmission performance (especially the impact load resistance) of the toothed belt, and is judged as c.

[0212] From the perspective of suitability for actual use in this application (taking into account both the manual operation of the sliding door and the impact load resistance of the belt), belts that meet criteria a and b are considered to be at the acceptable level.

[0213] [Starting torque (-30℃, -40℃)]

[0214] (Test Name) Starting Torque Measurement Test

[0215] (Testing machine)

[0216] Not shown (in) Figure 8 (The different types of torque meters are inserted into the shaft of the driven pulley in different ways).

[0217] A biaxial torque measuring machine was used in the experiment. The pulley layout is similar to the aforementioned belt drive mechanism. Figure 2 The same applies. That is, the pulley layout of this testing machine has a driving pulley and a driven pulley, with a fixed shaft distance of 50mm.

[0218] (Number of teeth on the pulley)

[0219] For a toothed belt with a pitch of 1.5mm, the drive pulley has 24 teeth and the driven pulley has 108 teeth.

[0220] For a toothed belt with a pitch of 2.0 mm, the drive pulley has 14 teeth and the driven pulley has 69 teeth.

[0221] For a toothed belt with a pitch of 2.5mm, the drive pulley has 15 teeth and the driven pulley has 75 teeth.

[0222] For a toothed belt with a pitch of 3.0 mm, the drive pulley has 12 teeth and the driven pulley has 60 teeth.

[0223] (Experimental Methods)

[0224] The toothed belt was wound between pulleys with zero tension (fixed shaft distance). After being placed at ambient temperatures (-30°C and -40°C) for 90 minutes each, the driven pulley was manually rotated at its respective ambient temperature (-30°C and -40°C) to measure the starting torque (at the start of rotation). Furthermore, if the toothed belt has excellent flexibility, the operating force (starting torque) can be kept lower.

[0225] (Judgment Criteria)

[0226] As a criterion for determining the belt's flexibility (and consequently, the manual operability of the sliding door), the starting torque value is used as an indicator (the smaller the torque value, the better the belt's flexibility). Regarding the starting torque value at -30℃...

[0227] Cases with a value less than 5.0 cN·m are used as criterion a.

[0228] Cases with values ​​above 5.0 cN·m but less than 10.0 cN·m are considered as criterion b.

[0229] Cases above 10.0 cN·m are used as the c criterion.

[0230] Regarding the starting torque value at -40℃

[0231] Cases less than 12.4 cN·m are used as criterion a.

[0232] Cases with a concentration above 12.4 cN·m but below 24.8 cN·m are considered as criterion b.

[0233] Cases above 24.8 cN·m are used as the c criterion.

[0234] From the perspective of suitability for actual use in this application (manual operability of the sliding door), the bands of judgment a and judgment b are considered to be at the qualified level.

[0235] [Skipping torque]

[0236] (Test Name) Jumping Test

[0237] (Testing machine)

[0238] The biaxial torque measuring machine was used in the experiment (see reference). Figure 8 The pulley layout is similar to the aforementioned belt drive mechanism. Figure 2 The same applies. That is, the pulley layout of this testing machine has a driving pulley and a driven pulley, with a fixed shaft distance of 50mm.

[0239] (Number of teeth on the pulley)

[0240] For a toothed belt with a pitch of 1.5mm, the drive pulley has 24 teeth and the driven pulley has 108 teeth.

[0241] For a toothed belt with a pitch of 2.0 mm, the drive pulley has 14 teeth and the driven pulley has 69 teeth.

[0242] For a toothed belt with a pitch of 2.5mm, the drive pulley has 15 teeth and the driven pulley has 75 teeth.

[0243] For a toothed belt with a pitch of 3.0 mm, the drive pulley has 12 teeth and the driven pulley has 60 teeth.

[0244] (Experimental Methods)

[0245] At room temperature, the toothed belt is wound between pulleys (with a fixed shaft distance) under no tension (zero installation tension). Furthermore, as... Figure 8 As shown, with the driven pulley fixed in a non-rotating manner, the drive pulley is manually rotated via a torque meter connected to the shaft of the drive pulley, and the load torque applied to the drive shaft when tooth skipping (runaway) occurs is measured as the tooth skipping torque.

[0246] (Judgment Criteria)

[0247] As the most important performance indicator for belt transmission in this application is resistance to tooth skipping (the difficulty of tooth skipping), the value of the tooth skipping torque is used as an indicator (the larger the torque value, the less likely tooth skipping is to occur). A tooth skipping torque value of 3.0 N·m or higher is considered as criterion a.

[0248] Cases with values ​​above 2.5 N·m and below 3.0 N·m are classified as b, and cases with values ​​below 2.5 N·m are classified as c.

[0249] From the perspective of appropriate (anti-skipping performance) for actual use in this application, the belts that meet the a and b criteria are considered to be at the qualified level.

[0250] The judgment criteria for the above four performance-related test items (elastic modulus, starting torque (-30℃, -40℃), and skip torque) are summarized in Table 5.

[0251] Table 5

[0252] <![CDATA[ Judgment Criteria ]]> a b c With elastic modulus (N / % / 1mm width) 30 and above and less than 60 25 and above but less than 30 Less than 25 or more than 60 Judgment Criteria a b C Starting torque (cN·m) -30℃ Less than 5.0 5.0 or higher but less than 10.0 10.0 or above Starting torque (cN·m) -40℃ Less than 12.4 Above 12.4 and below 24.8 24.8 or above Tooth skipping torque (N·m) 3.0 or above 2.5 or higher and less than 3.0 Less than 2.5

[0253] (Comprehensive judgment)

[0254] The criteria for comprehensively judging (grading) toothed belts that can solve this problem are based on the results of the judgments in the test items related to the above four belt performance (belt elastic modulus, starting torque (-30℃, -40℃), and skipped tooth torque), as described below.

[0255] Level A: If all the above test items are judged as 'a', it is determined that there are no practical problems and is set as the best level.

[0256] Grade B: In the above test items, the judgment of "with elastic modulus" is grade a, and there is no grade c among the three judgments of "tooth skipping torque", "starting torque at -30℃" and "starting torque at -40℃". However, even if one of them is grade b, or if the judgment of "with elastic modulus" is grade b, and all three judgments of "tooth skipping torque", "starting torque at -30℃" and "starting torque at -40℃" are grade a, there is no problem in practice, but it is set as a slightly worse grade.

[0257] Grade C: In the above test items, even if one of the judgments is a C judgment, or if the judgment for "with elastic modulus" is a B judgment and there is no C judgment among the three judgments for "tooth skipping torque", "starting torque at -30℃" and "starting torque at -40℃", but even if one of them is a B judgment, it is set as an insufficient grade (unqualified) as a solution to this problem.

[0258] (Verification Results and Investigation)

[0259] [Verification at a tooth pitch of 2.5mm]

[0260] The verification results are shown in Tables 6-12.

[0261] (Comparison using core wire diameter as a variable)

[0262] Table 6

[0263]

[0264] (Examples 1-3, Comparative Examples 1-2)

[0265] Using high-strength glass (U glass, K glass) fiber cores, comparisons were made with core diameter as the variable in toothed tapes with a fixed back-to-thickness ratio of 29.0%, rubber hardness of 75°, H-tooth shape, and core density of 29.0%.

[0266] It was found that the larger the core wire diameter, the greater the tendency for the starting torque (-30℃, -40℃) to increase, but under these conditions, the predetermined elastic modulus and skip torque (a judgment) can be ensured.

[0267] When the core wire diameter is 0.17 mm (Example 1), 0.20 mm (Example 2), and 0.26 mm (Example 3), the starting torque (-30°C, -40°C) is determined as either a or b (the overall determination is also level A or B). However, if the core wire diameter is increased to 0.30 mm (Comparative Example 1), the starting torque (-30°C, -40°C) is determined as c (the overall determination is also level C).

[0268] On the other hand, if the core wire diameter is reduced to 0.14 mm (Comparative Example 2), it is impossible to manufacture the tape by cutting the core wire during manufacturing.

[0269] Based on the above results, it can be said that the preferred range for the core wire diameter is 0.15 mm or more and less than 0.30 mm, which ensures the predetermined (acceptable level) starting torque at any ambient temperature (-30℃, -40℃).

[0270] (Comparison of glass fiber (thread material) has been changed)

[0271] Table 7

[0272]

[0273] (Examples 2, 4, and Comparative Example 3)

[0274] Based on the toothed tape of Example 2 (with a core diameter of 0.20 mm, a back thickness ratio of 29.0%, a rubber hardness of 75°, an H-shaped tooth, and a core arrangement density of 29.0%), the high-strength glass (U-glass) fibers constituting the core were changed and compared.

[0275] In Example 4, which uses other high-strength glass (K glass) fibers, the predetermined (acceptable level) elastic modulus can be ensured in the same way as in Example 2, resulting in a grade A in the overall assessment.

[0276] On the other hand, in Comparative Example 3, which used E-glass fiber that was not high-strength glass fiber, the elastic modulus was determined to be b, the starting torque (-30°C, -40°C) was also determined to be b, and the overall determination was grade C.

[0277] (Comparison using back thickness ratio as a variable)

[0278]

[0279] (Examples 2, 5-6)

[0280] Based on the toothed belt of Example 2 (rubber hardness of 75°, H-tooth shape, core wire arrangement density of 29.0%) with a core wire diameter of 0.20 mm, a comparison was made by changing the back thickness ratio to 29.0%.

[0281] It was found that the larger the back thickness ratio, the greater the tendency for the starting torque (-30℃, -40℃) to increase, but under these conditions, the predetermined elastic modulus and skip torque (a judgment) can be ensured.

[0282] Compared to Example 2, in Example 5, where the back thickness ratio is reduced to 23.6%, it is classified as Grade A, the same as in Example 2. However, in Example 6, where the back thickness ratio is increased to 38.5%, the starting torque (-40°C) is determined as Grade B.

[0283] (Examples 1, 7-8, and Comparative Example 4)

[0284] Based on the toothed belt of Example 1 with a core wire diameter of 0.17 mm (rubber hardness of 75°, H-shaped, core wire arrangement density of 29.0%), a comparison was made by changing the back thickness ratio to 29.0%.

[0285] Compared to Example 1, Example 7, which reduced the back thickness ratio to 22.0%, and Example 8, which increased the back thickness ratio to 38.5%, were both classified as Grade A, equivalent to Example 2.

[0286] In Comparative Example 4, where the back thickness ratio was reduced to 21.4%, defects in the back rubber occurred during belt manufacturing, making it impossible to manufacture. Therefore, from the viewpoint of whether a belt bundle can be manufactured, it can be said that the lower limit of the back thickness ratio is 22.0%.

[0287] (Examples 3, 9-12, and Comparative Example 5)

[0288] Based on the toothed tape of Example 3 (rubber hardness of 75°, H-tooth shape, core wire arrangement density of 29.0%) with a core wire diameter of 0.26 mm, a comparison was made by changing the back thickness ratio to 29.0%.

[0289] Compared to Example 3, Example 9, which reduced the back thickness ratio to 26.7%, and Example 10, which increased the back thickness ratio to 38.5%, are equivalent to Example 3 (Grade B).

[0290] In addition, the starting torque value is an indicator of the belt's flexibility (the smaller the torque value, the better the belt's flexibility). Regarding the flexibility of the backing, the hardness of the rubber constituting the backing, the density of the core wires embedded in the backing, and the backing thickness ratio also have an impact.

[0291] Therefore, to confirm its effect, Example 11 is an example in which the core wire arrangement density is increased to 20.0% (making the core wire arrangement denser) relative to the toothed belt of Example 10, but is equivalent to Example 10 (Grade B). Example 12 is an example in which the rubber hardness is further increased to 81° relative to Example 11, but is equivalent to Example 10 (Grade B). However, in Comparative Example 5, where the back thickness ratio is increased to 38.9% under the conditions of high core wire arrangement density (20.0%) and high hardness (81°) of Example 12, the starting torque (-30°C, -40°C) is determined to be c, and it is grade C.

[0292] Based on this result, the upper limit of the back thickness ratio can be said to be 38.5% in terms of ensuring the predetermined (acceptable level) starting torque at any ambient temperature (-30℃, -40℃).

[0293] Based on the above results, in terms of whether it is feasible to manufacture and whether the predetermined starting torque can be ensured, it can be said that the preferred range for the back thickness ratio is 22.0% or more and 38.5% or less.

[0294] (Comparison using the hardness (rubber hardness) of the rubber composition constituting the back and teeth as a variable)

[0295] Table 9

[0296]

[0297] (Example 2, 14)

[0298] Based on the toothed belt of Example 2 (back thickness ratio of 29.0%, H-shaped, core wire arrangement density of 29.0%) with a core wire diameter of 0.20 mm, comparisons were made with rubber hardness of 75° as the variable.

[0299] Compared to Example 2, Example 14, in which the rubber hardness was increased to 81°, was identical to Example 2 (Grade A). When the rubber hardness increased, a tendency was observed for increased starting torque (-30°C, -40°C) and skip torque; however, under these conditions, the predetermined elastic modulus, starting torque, and skip torque (a-judgment) were maintained.

[0300] (Examples 1, 13, and Comparative Examples 6-7)

[0301] To confirm the lower limit of rubber hardness, a comparison was made based on the toothed belt of Example 1 (core wire diameter of 0.17 mm) with rubber hardness of 75° as the variable.

[0302] Compared to Example 1, Example 13, in which the rubber hardness was increased to 81°, was equivalent to Example 1 (Grade A). On the other hand, compared to Example 1, Comparative Examples 6 (61°) and 7 (71°), in which the rubber hardness was reduced, could not ensure the predetermined skip torque (c determination), and were classified as Grade C. Based on this result, it can be said that the lower limit of rubber hardness is about 73°.

[0303] (Examples 11-12, Comparative Example 8)

[0304] To confirm the upper limit of rubber hardness, a comparison was made based on the toothed belt of Example 11 (coarse core wire diameter of 0.26 mm, core wire arrangement of high density of 20.0%, and high back thickness ratio of 38.5%), which has conditions that are unfavorable to the bending of the back as described above, with rubber hardness of 75° as the variable.

[0305] Compared to Example 11, Example 12, in which the rubber hardness was increased to 81°, was equivalent to Example 11 (Grade B). Furthermore, in Comparative Example 8, in which the rubber hardness was increased to 85°, the predetermined starting torque could not be guaranteed (C determination), resulting in Grade C. Based on these results, it can be said that the upper limit of rubber hardness is approximately 83°.

[0306] Based on the above results, in terms of ensuring the predetermined skip torque and the predetermined starting torque, it can be said that the preferred range of rubber hardness is above 73° and below 83°.

[0307] (Comparison with altered tooth profiles)

[0308] Table 10

[0309]

[0310] (Example 2, Comparative Examples 9-10)

[0311] Based on the toothed belt of Example 2 (core diameter of 0.20 mm, back thickness ratio of 29.0%, rubber hardness of 75°, and core density of 29.0%), the H-tooth shape was changed and a comparison was made.

[0312] Compared to Example 2, in Comparative Example 9, where the tooth profile was changed to an S-shaped tooth profile, the predetermined (acceptable level) skipping torque (c judgment) could not be ensured, resulting in a grade C. Furthermore, compared to Comparative Example 9 with the S-shaped tooth profile, in Comparative Example 10, where the rubber hardness was increased to the upper limit level (81°), the predetermined skipping torque (c judgment) could not be ensured, resulting in a grade C.

[0313] Based on the above results, setting the tooth profile to H-shaped tooth profile can ensure the predetermined skip torque even when the rubber hardness is at the lower limit level (75°), so it can be said to be the preferred tooth profile.

[0314] (A comparison using the total value of the interval d as a ratio to the band width (density of the core wire arrangement) as a variable)

[0315] Table 11

[0316]

[0317] (Examples 2, 15-18, Comparative Example 11)

[0318] Based on the toothed tape of Example 2 (core wire diameter of 0.20 mm, back thickness ratio of 29.0%, rubber hardness of 75°, H-tooth shape), the density of the core wire arrangement was changed to 29.0%, and a comparison was made.

[0319] A higher percentage (%) of the core wire density (the total value of the spacing d relative to the band width) indicates a sparser core wire density.

[0320] If the core wire arrangement density is set to 20.0% (Example 15), 29.0% (Example 2), 33.3% (Example 16), and 35.0% (Example 17), it is found that as the core wire arrangement becomes sparse, the elastic modulus and starting torque tend to decrease, but under these conditions, it is classified as Grade A. Moreover, in the belt with a sparse core wire arrangement density of 38.5% (Example 18), the elastic modulus is at a low level (judgment b), and therefore it is classified as Grade B.

[0321] On the other hand, regarding the lower limit level (the limit level of density) of the core wire arrangement density, in Comparative Example 11, where the core wire arrangement density was reduced to 16.7%, the spacing between adjacent core wires was too small. During the manufacture of the belt, it was difficult for the rubber to flow around the core wires, resulting in poor forming. Therefore, from the viewpoint of whether the belt can be manufactured, it can be said that the lower limit level of the core wire arrangement density is about 20.0%.

[0322] Based on the above results, regarding the density of the core wire arrangement, from the viewpoint of ensuring formability (manufacturability) and the predetermined (acceptable level) elastic modulus, it can be said that a range of 20.0% or more and 35.0% or less is preferred.

[0323] (Comparison of rubber composition variations)

[0324] Table 12

[0325]

[0326] (Examples 14, 19-20)

[0327] Based on the toothed belt of Example 14 (core diameter of 0.20 mm, back thickness ratio of 29.0%, rubber hardness of 81°, H-shaped, core density of 29.0%), the rubber composition was changed and comparisons were made.

[0328] In this comparison, in order to observe the effect of the rubber composition constituting the back and teeth on cold resistance, it was verified from the point of view that even if the rubber hardness of the back is at the upper limit level (81°), the predetermined (acceptable level) starting torque can be ensured.

[0329] As a result, compared to Example 14 which used CR as the rubber component, Example 19 which used EPDM and Example 20 which used H-NBR were also equivalent to Example 14 (Grade A).

[0330] In Example 19, where EPDM was used in the rubber composition, the cold resistance (low-temperature flexibility) was improved compared to the case where CR or H-NBR was used. Correspondingly, the starting torque showed a slightly lower value at any ambient temperature (-30°C, -40°C).

[0331] [Verification at a tooth pitch of 2.0mm]

[0332] The verification results are shown in Tables 13-15.

[0333] (Comparison using back thickness ratio as a variable)

[0334] Table 13

[0335]

[0336] (Examples 21-23)

[0337] A toothed belt with a pitch of 2.0 mm, equivalent to the toothed belt of Example 2 (core diameter 0.20 mm, rubber hardness 75°, H-shaped tooth, core density of 29.0%, back thickness ratio of 29.0%) used in the verification at a tooth pitch of 2.5 mm, was designated as Example 22. Example 2 was classified as Grade A, but in Example 22, the skipped tooth torque was at a low level (judgment b), therefore it was classified as Grade B.

[0338] Next, a comparison was made with the back thickness ratio changed to 29.0% compared to Example 22. Furthermore, the lower limit of the back thickness ratio that can be manufactured under this condition is 27.9%.

[0339] Compared to Example 22, in Example 21, which reduces the back thickness ratio to 27.9% (lower limit level), and in Example 23, which increases the back thickness ratio to 38.5%, the skip torque is determined to be b, which is level B, similar to Example 22.

[0340] (Examples 24-26)

[0341] Example 25 uses a toothed belt with a pitch of 2.0 mm, which is equivalent to the toothed belt of Example 1 with a tooth pitch of 2.5 mm (core diameter of 0.17 mm, rubber hardness of 75°, H-shaped tooth, core density of 29.0%, and back thickness ratio of 29.0%). Example 1 is classified as Grade A, but in Example 25, the skipped tooth torque is at a low level (judgment b), therefore it is classified as Grade B.

[0342] Next, a comparison was made with the back thickness ratio changed to 29.0% compared to Example 25. Furthermore, the lower limit of the back thickness ratio that can be manufactured under this condition is 26.1%.

[0343] Compared to Example 25, the toothed belts of Example 24, which reduces the back thickness ratio to 26.1% (lower limit level), and Example 26, which increases the back thickness ratio to 38.5%, are equivalent to those of Example 25 (Grade B).

[0344] (Examples 27-28)

[0345] In a toothed belt with a pitch of 2.0 mm and a core wire diameter of 0.26 mm, the lower limit of the back thickness ratio that can be manufactured is 31.3%.

[0346] Therefore, since it was impossible to manufacture a toothed belt comparable to the toothed belt of Example 3 with a tooth pitch of 2.5 mm (rubber hardness of 75°, H-shaped tooth, core wire arrangement density of 29.0%, and back thickness ratio of 29.0%), toothed belts with back thickness ratios of 31.3% (lower limit) and 38.5% were designated as Examples 27 and 28, respectively. Both had low skip torque (judgment b) and low starting torque (judgment b), classifying them as Grade B.

[0347] Based on the above results, in toothed belts with a pitch of 2.0 mm, a grade B toothed belt capable of solving this problem was obtained within the range of core wire diameter being 0.15 mm or more and less than 0.30 mm, and back thickness ratio being 26.1% or more and less than 38.5%.

[0348] (Comparison using the hardness (rubber hardness) of the rubber composition constituting the back and teeth as a variable)

[0349] Table 14

[0350]

[0351] (Examples 22, 29, and Comparative Example 12)

[0352] Based on the toothed belt (core diameter of 0.20 mm, H-shaped, core density of 29.0%, back thickness ratio of 29.0%) of Example 22 above, a comparison was made with rubber hardness of 75° as the variable.

[0353] Compared to Example 22, the toothed belt of Example 29, in which the rubber hardness is increased to 81°, is the same as that of Example 22 (Grade B). On the other hand, in Comparative Example 12, in which the rubber hardness is reduced to 71°, the predetermined skip torque cannot be ensured (c determination), and it becomes Grade C.

[0354] (Examples 30-31, Comparative Example 13)

[0355] The back-to-thickness ratio, the hardness of the rubber constituting the back, and the thickness and density of the core wire embedded in the back affect the starting torque value, which is an indicator of belt flexibility (the smaller the starting torque value, the better the belt flexibility). Taking this effect into account, an upper limit level of rubber hardness was determined in a structure with conditions unfavorable to back flexibility (high back-to-thickness ratio of 38.5%, thick core wire diameter of 0.26 mm, and high core wire density of 20.0%).

[0356] In this structure, in Examples 30 (rubber hardness 75°) and 31 (rubber hardness 81°), the skipped torque was low (judgment b), and the starting torque was also low (judgment b), but a grade B toothed belt was obtained. However, in Comparative Example 13, where the rubber hardness was increased to 85°, the starting torque exceeded the upper limit (judgment c), and the predetermined (acceptable level) starting torque (grade C) could not be ensured.

[0357] Based on the above results, a grade B toothed belt capable of solving this problem was also obtained in the toothed belt with a pitch of 2.0 mm and a rubber hardness of 73° or higher and 83° or lower.

[0358] (Comparison of rubber composition variations)

[0359] Table 15

[0360]

[0361] (Examples 29, 32-33)

[0362] Based on the toothed belt of Example 29 (core diameter of 0.20 mm, back thickness ratio of 29.0%, rubber hardness of 81°, H-shaped, core density of 29.0%), the rubber composition was changed and comparisons were made.

[0363] In this comparison, in order to observe the effect of the rubber composition constituting the back and teeth on cold resistance, it was verified from the point of view that even if the rubber hardness of the back is at the upper limit level (81°), the predetermined (acceptable level) starting torque can be ensured.

[0364] As a result, compared to Example 29, which used CR as the rubber component, Example 32, which used EPDM, and Example 33, which used H-NBR, were also equivalent to Example 29 (Grade B).

[0365] In Example 32, where EPDM was used in the rubber composition, the cold resistance (low-temperature flexibility) was improved compared to the case where CR or H-NBR was used. Correspondingly, the starting torque showed a slightly lower value at any ambient temperature (-30°C, -40°C).

[0366] [Verification at tooth pitch of 1.5mm and 3.0mm]

[0367] The verification results are shown in Table 16.

[0368] Table 16

[0369]

[0370] (Comparative Examples 14-16)

[0371] In the verification at a tooth pitch of 2.0 mm, a toothed belt with a tooth pitch of 1.5 mm, equivalent to the toothed belt of Example 22 (core diameter of 0.20 mm, rubber hardness of 75°, H-shaped tooth, core density of 29.0%, and back thickness ratio of 29.0%), was used as Comparative Example 14. However, regarding the back thickness ratio, it was set to 34.0% of the lower limit that a belt with a tooth pitch of 1.5 mm could be manufactured. In Example 22, the skip torque was determined as b, which is grade B, but in Comparative Example 14, the predetermined skip torque could not be ensured (determined as c), resulting in grade C.

[0372] Next, for the toothed belt of Comparative Example 14, a toothed belt with a fine core wire (core wire diameter of 0.17 mm) was changed to Comparative Example 15 for verification. However, like Comparative Example 14, the predetermined skipping torque (c judgment) could not be guaranteed, and it became grade C.

[0373] Therefore, in order to improve the rigidity of the teeth, a toothed belt with a rubber hardness increased to 81° compared to the toothed belt of Comparative Example 14 was tested as Comparative Example 16. However, like Comparative Example 14, it could not ensure the predetermined skip torque (c judgment) and became grade C.

[0374] Based on these results, from the perspective of ensuring the predetermined (acceptable) skip torque, it can be said that the lower limit of the tooth pitch is 2.0 mm.

[0375] (Comparative Examples 17-18)

[0376] In the verification at a tooth pitch of 2.5 mm, the toothed belt of Example 12, which has a structure that is unfavorable to the bending of the back (high back thickness ratio of 38.5%, thick core wire diameter of 0.26 mm, high core wire density of 20.0%, and high rubber hardness of 81°), had a large starting torque (judgment b), and was classified as Grade B. A toothed belt equivalent to the toothed belt of Example 12, with a tooth pitch increased to 3.0 mm, was verified as Comparative Example 17, but the starting torque was further increased (judgment c), and it was classified as Grade C.

[0377] In addition, for the toothed belt of Comparative Example 17, a toothed belt that reduces the rubber hardness to 75° was verified as Comparative Example 18, but the starting torque increased (c judgment) just like Comparative Example 17, and it became grade C.

[0378] Based on these results, at any ambient temperature (-30℃, -40℃), from the point of view of ensuring the predetermined (acceptable) starting torque, it can be said that the upper limit of the tooth pitch is 2.5mm.

[0379] Based on the above results, from the perspective of ensuring both the predetermined skip torque and the predetermined starting torque, it can be said that the preferred range for the tooth pitch is 2.0 mm or more and 2.5 mm or less.

[0380] (Results obtained)

[0381] According to Tables 6 to 16, the toothed belts of Examples 1 to 33 correspond to Project 1 and Project 2. High-strength glass fiber is used in the core wire (the material of the filament) to ensure the predetermined elastic modulus of the belt. Furthermore, the bending performance (starting torque) and transmission performance (especially impact load resistance) of the toothed belt under extremely low temperature environments are taken into account. The spacing of the teeth is designed to be relatively small (above 2.0 mm and below 2.5 mm), thereby making it easy to ensure both the bending performance (starting torque) and transmission performance (tooth skipping torque) of the belt under extremely low temperature environments.

[0382] In addition, corresponding to Project 1, the diameter of the core wire is designed to be relatively low (between 0.15 mm and less than 0.30 mm) to make the core wire itself flexible. Of course, by designing the back thickness ratio, defined by the ratio of the back thickness to the belt thickness, to be relatively low (between 22.0% and less than 38.5% when the tooth pitch is between 2.0 mm and 2.5 mm), the flexibility of the belt can be ensured even when wound between pulleys without tension, and the bending performance (starting torque) of the belt in extremely low temperature environments (-30℃ to -40℃) can be ensured.

[0383] Furthermore, corresponding to Project 2, it can be seen that by designing the rubber composition constituting the teeth to have a relatively high hardness (above 73° and below 83°) and designing the shape of the teeth to be H-shaped, the rigidity of the teeth is improved. Thus, even when driven in a tension-free state, the transmission performance (skip-tooth torque) of the belt can be ensured.

[0384] Regarding ensuring the predetermined starting torque (belt flexibility), in toothed belts wound in a tension-free state, it can be confirmed from Table 6 that reducing the core wire diameter (i.e., making the core wire itself flexible) is the most effective (contributing the most). Then, it can be confirmed from Tables 8-9 and Tables 13-14 that reducing the back thickness ratio, the hardness of the back rubber, and the tooth pitch, and from Table 11 that increasing the core wire arrangement density (making the arrangement sparse) is effective (contributing to) reducing the belt's elastic modulus.

[0385] Regarding ensuring the predetermined skip torque (belt transmission performance), for toothed belts driven in a tension-free state, it can be confirmed from Table 9 (for example, comparison of Comparative Example 7, Example 1, and Example 13), Table 10 (comparison of Example 2 and Comparative Example 9), and Table 16 that increasing the rigidity of the teeth (the relationship between the rubber hardness of the teeth, the shape of the teeth, and the tooth pitch) is the most effective (with a large contribution rate). It can be confirmed from Table 6 (comparison of Examples 1-3 and Comparative Example 1) that increasing the level of the belt's elastic modulus has almost no effect (no contribution).

[0386] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0387] This application is based on Japanese Patent Application No. 2021-075222 filed on April 27, 2021, Japanese Patent Application No. 2021-110816 filed on July 2, 2021, and Japanese Patent Application No. 2022-066929 filed on April 14, 2022, the contents of which are incorporated herein by reference.

[0388] Explanation of reference numerals in the attached figures

[0389] 1. Toothed belt

[0390] 2-core wire

[0391] 3. Back

[0392] 4. Teeth

[0393] 41 Tooth tip

[0394] 42. Side of the tooth

[0395] 43. Side of the tooth

[0396] 44 tooth root

[0397] 5. Toothed cloth

[0398] 10. Belt drive mechanism.

Claims

1. A toothed belt, comprising: Back; The core wire is embedded in the back. Multiple teeth are arranged at predetermined intervals on one side of the back surface along the length direction of the belt; and A toothed cloth that covers the surface of the teeth and a portion of the surface of one side of the back. The core wire is a twisted rope containing high-strength glass fiber filaments. The tooth pitch between the teeth is greater than 2.0 mm and less than 2.5 mm. The diameter of the core wire is greater than 0.15 mm and less than 0.30 mm. The thickness of the back portion relative to the thickness of the toothed strip is 22.0% or more and 38.5% or less. The teeth are made of a rubber composition having a hardness of 73° or higher and 83° or lower at 23°C. The tooth is formed as a shape in which the tooth tip and two sides separated by the tooth tip in the belt length direction are connected by one or more curved surfaces with a certain curvature.

2. The toothed belt according to claim 1, wherein, The diameter of the high-strength glass fiber filament is 6 to 9 micrometers.

3. The toothed belt according to claim 1, wherein, The core wire is a single-twist twisted rope.

4. The toothed belt according to any one of claims 1 to 3, wherein, The core wires are arranged in the width direction and embedded in the back. The total value of the spacing between adjacent core wires in the width direction is more than 20% and less than 35% of the width.

5. The toothed belt according to any one of claims 1 to 3, wherein, The elastic modulus of the belt, defined by the belt tension (N) per 1 mm of belt width relative to the belt elongation (%), is greater than 30 N / % and less than 60 N / %.

6. The toothed belt according to any one of claims 1 to 3, wherein, The back and the teeth are made of a rubber composition, which contains at least neoprene rubber.

7. The toothed belt according to any one of claims 1 to 3, wherein, The toothed belt is wound between the pulleys with a load of 3N. Used for sizes below m.

8. A belt drive mechanism, comprising: A drive pulley that rotates under the influence of a drive source; Driven pulley; and To make the load on the driven pulley 3N. The toothed belt of any one of claims 1 to 7 is wound around the drive pulley and the driven pulley in a manner of less than m.

Images