TWI697634B - Helical belt and belt transmission device - Google Patents

Abstract

The present invention relates to a helical toothed belt, which is characterized by having: a back part in which a core wire is embedded; and a plurality of teeth parts, which are arranged on one surface of the back part at specific intervals along the length of the belt, and are each relative to the belt width. The direction is inclined; and a part of the surface of the tooth part and the one surface of the back part is made of tooth cloth, the tooth pitch of the plurality of teeth is 2 mm or more but less than 4 mm, if the tooth pitch of the plurality of teeth If it is 2 mm or more but less than 3 mm, the thickness of the back is 0.4 mm or more and 1.2 mm or less. If the tooth pitch of the plurality of teeth is 3 mm or more and less than 4 mm, the thickness of the back is 0.6 mm or more and 1.8 mm or less, the aforementioned core wire is a twisted wire containing high-strength glass fiber or carbon fiber with a wire diameter of 0.2 mm or more and 0.6 mm or less, and the pitch of each core wire between the aforementioned core wire and the core wire falls within the range of 0.45 mm or more and 0.6 mm or less The way to arrange.

Description

Helical belt and belt drive

The present invention relates to a helical toothed belt, and particularly relates to a helical toothed belt and a belt transmission device applied to a belt transmission device driven by high load or high-speed rotation.

For example, like the deceleration device of an electric power steering device, in a belt drive driven by high load or high-speed rotation, when a straight-toothed belt with teeth extending parallel to the belt width direction is used, the teeth and the belt At the beginning and end of the meshing of the teeth of the belt pulley, loud noise and vibration will be generated. As a countermeasure to this problem, a helical belt in which the teeth are arranged obliquely with respect to the belt width direction is used. The meshing of the tooth part of the belt of the helical toothed belt and the tooth part of the pulley is carried out sequentially from one end of the respective tooth part to the other end. Therefore, it can reduce noise and vibration compared with a belt drive using a straight toothed belt.

However, even if a helical toothed belt is used, it may not be able to sufficiently reduce noise and vibration. In contrast to this, for example, Patent Document 1 and Patent Document 2 propose a technology for further reducing noise and vibration in a belt transmission device that uses a helical toothed belt to drive at high load or high-speed rotation.

In Patent Document 1, the tooth pitch is Pt, the belt width is W, and the tooth intersection angle θ is set to a value that satisfies -0.2≦1-W·tanθ/Pt≦0.75. In addition, the tooth gap (gap) between the tooth part of the helical belt and the tooth part of the pulley is set to 1.6% to 3% of the tooth pitch Pt.

In Patent Document 2, the tooth intersection angle θ is set to 7 degrees or more and 10 degrees or less. In addition, the thickness of the back portion is referred to as tb, and the tooth height of the tooth portion is referred to as hb, and the ratio of the thickness tb to the tooth height hb (100×tb/hb) is set to 120% or more and 240% or less.

In recent years, due to the promotion of quieter cars, belt transmission devices such as deceleration devices of electric power steering devices are required to further reduce noise. However, the techniques of Patent Document 1 and Patent Document 2 may not be able to reduce noise and vibration to a satisfactory level. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2004-308702 [Patent Document 2] Japanese International Publication No. 2014/024377

[The problem to be solved by the invention]

At this point, in order to reduce noise and vibration, consider increasing the rigidity (elasticity) of the helical belt. As a method of increasing the rigidity, a method of increasing the thickness of the helical belt (especially the thickness of the back) can be cited. However, in this method, even if vibration and noise can be suppressed, the buckling of the helical belt becomes worse, which increases buckling fatigue on the pulley, and cracks are likely to occur especially in a low temperature environment.

Therefore, the object of the present invention is to provide a helical toothed belt that improves rigidity without increasing the thickness of the helical toothed belt, and can further reduce noise and vibration when used in a belt drive driven by high load or high-speed rotation. [Technical means to solve the problem]

One aspect of the present invention is a helical toothed belt, which is characterized by having: a back part in which a core wire is embedded; and a plurality of teeth parts, which are arranged on one surface of the back part at specific intervals along the length of the belt, and are respectively opposed to The belt width direction is oblique; and a part of the surface of the tooth portion and the one surface of the back portion is made of tooth cloth, and the tooth pitch of the plurality of teeth is 2 mm or more but less than 4 mm, if the plurality of teeth If the tooth pitch is 2 mm or more but less than 3 mm, the thickness of the back is 0.4 mm or more and 1.2 mm or less. If the tooth pitch of the plurality of teeth is 3 mm or more and less than 4 mm, the thickness of the back is 0.6 mm or more and 1.8 mm or less, the aforementioned core wire contains high-strength glass fiber or carbon fiber and has a twisted wire with a wire diameter of 0.2 mm or more and 0.6 mm or less, and the pitch of each core wire between the aforementioned core wire and the core wire falls within 0.45 mm or more and 0.6 mm The following ranges are arranged.

According to the above-mentioned structure, since the surface on the side of the tooth portion of the back is made of tooth cloth, it is reinforced to increase rigidity. In addition, the core wire embedded in the back is a twisted yarn containing high-strength glass fiber or carbon fiber as a high-strength (high elastic modulus) fiber material, and the diameter of the twisted yarn is 0.2 mm or more and 0.6 mm or less. Therefore, the flexibility of the back can be ensured, and the rigidity of the back can be further improved by the core wire. By improving the rigidity of the back in this way, even if the helical toothed belt is used in a belt drive driven by high load or high-speed rotation, it can also suppress the skew generated when the tooth part of the helical tooth belt meshes with the tooth part of the pulley. The core line of the toothed belt is the vibration (string vibration) at the center. In this way, the noise caused by vibration can be reduced.

In addition, the core wires buried in the back are arranged in such a way that the pitch of each core wire between the core wires falls within the range of 0.45 mm to 0.6 mm. Thereby, without further increasing the thickness of the back, or further increasing the wire diameter of the core wire (without sacrificing flexibility), the rigidity of the helical belt can be further improved.

Also, if the tooth pitch is 2 mm or more but not 3 mm, the thickness of the back is 0.4 mm or more and 1.2 mm or less. If the tooth pitch is more than 3 mm but less than 4 mm, the thickness of the back is 0.6 mm or more and 1.8 mm or less. These thicknesses are, for example, the same level as the thickness of the back of the previous helical belt used in the deceleration device of the electric power steering device for automobiles. The helical tooth belt of the present invention can improve the rigidity of the back without increasing the thickness of the back. Therefore, the flexural fatigue resistance can be sufficiently ensured, and vibration and noise can be further suppressed.

In addition, an aspect of the present invention is the above-mentioned helical toothed belt, wherein the core wire embedded in the back is from one end to the other end in the belt width direction of the helical toothed belt, and the pitch of each core wire becomes 0.45 mm or more Arrange in a certain value in the range below 0.6 mm.

According to the above structure, without further increasing the thickness of the back or the wire diameter of the core wire (without sacrificing flexibility), the rigidity of the helical belt can be further improved, and vibration and noise can be further suppressed.

In addition, an aspect of the present invention is the helical tooth belt, wherein it is feasible that if the tooth pitch of the plurality of teeth is 2 mm or more and less than 3 mm, the tooth height of the teeth is 0.7 mm or more 2.0 mm or less, and if the tooth pitch of the aforementioned plural teeth is 3 mm or more but less than 4 mm, the tooth height of the aforementioned tooth is 1.0 mm or more and 2.3 mm or less.

According to the above configuration, vibration and noise can be further suppressed.

In addition, one aspect of the present invention is a belt such as the above-mentioned helical toothed belt, wherein it is possible that the back portion contains a rubber component, and the rubber component contains an ethylene-propylene-diene terpolymer or hydrogenated nitrile rubber.

According to the above configuration, vibration and noise can be further suppressed.

In addition, an aspect of the present invention is the helical tooth belt, wherein it is possible that the tooth cloth is composed of a woven fabric including warp yarns and weft yarns, the warp yarns or weft yarns are arranged to extend in the belt length direction, and the arrangement is The warp or weft extending in the length direction of the belt contains elastic yarns with stretchability.

According to the above configuration, vibration and noise can be further suppressed.

In addition, an aspect of the present invention is a belt such as the above-mentioned helical toothed belt, wherein the fiber constituting the tooth cloth may contain selected from the group consisting of Nylon, aromatic polyamide, polyester, polybenzoxazole, and cotton At least one fiber.

According to the above configuration, vibration and noise can be further suppressed.

In addition, an aspect of the present invention is a belt such as the above-mentioned helical toothed belt, wherein it is possible that the other surface of the back is composed of a backing cloth, and the fiber constituting the backing cloth contains a fiber selected from the group consisting of Nylon and aromatic polyamide , And at least one fiber in the polyester group.

According to the above configuration, since the other side of the back is composed of a back cloth, and the fibers constituting the back cloth contain at least one fiber selected from the group consisting of Nylon, aromatic polyamide, and polyester, the back is covered Further reinforcement to increase rigidity.

In addition, in one aspect of the present invention, the belt elastic modulus of the helical toothed belt may be 0.96 MPa or more per 1 mm of the belt width.

According to the above structure, it is possible to ensure the rigidity of the helical belt that is sufficient to suppress vibration and obtain sufficient quietness.

In addition, one aspect of the present invention may also be a belt transmission device comprising: a drive pulley which is rotatably driven by a drive source; a driven pulley; and the above-mentioned oblique wound on the drive pulley and the driven pulley Toothed belt.

According to the above configuration, it is possible to reduce noise and vibration in the belt transmission device that transmits the driving force of the driving pulley to the driven pulley.

Furthermore, an aspect of the present invention is the belt transmission device described above, wherein the rotation speed of the driving pulley may be 1000 rpm or more and 4000 rpm or less.

According to the above configuration, it is possible to sufficiently reduce noise and vibration in a belt drive driven at high speed.

In addition, an aspect of the present invention is the belt transmission device described above, wherein the load of the driven pulley may be 0.5 kW or more and 3 kW or less.

According to the above structure, it is possible to sufficiently reduce noise and vibration in a belt drive driven by a high load.

In addition, an aspect of the present invention is the belt transmission device described above, wherein it is feasible that the outer diameter of the driven pulley is larger than the outer diameter of the driving pulley, and the belt transmission device is the deceleration of the electric power steering device for automobiles Device.

According to the above structure, it is possible to sufficiently reduce noise and vibration in the deceleration device of an electric power steering device for automobiles. [Effects of Invention]

The present invention can provide a helical toothed belt which can improve rigidity without increasing the thickness of the helical toothed belt, and can further reduce noise and vibration when used in a belt transmission device driven by high load or high-speed rotation.

Hereinafter, an example of the embodiment of the present invention will be described. The helical belt 30 of this embodiment is used, for example, in the reduction gear 20 of the electric power steering system 1 for an automobile as shown in FIG.

[Configuration of Electric Power Steering Device] The electric power steering (EPS) device 1 has: a steering shaft 3, which is connected to the steering wheel 2, an intermediate shaft 4, which is connected to the steering shaft 3, and a steering mechanism 5, which is connected to the intermediate shaft 4. In conjunction with the rotation of the steering wheel 2, the wheels 9 are steered.

The steering mechanism 5 includes a pinion shaft 6 connected to the intermediate shaft 4 and a rack shaft 7 that meshes with the pinion shaft 6. The rack shaft 7 extends in the left-right direction of the vehicle. At the midway portion of the rack shaft 7 in the axial direction, a rack 7a meshing with a pinion 6a provided on the pinion shaft 6 is formed. Wheels 9 are connected to both ends of the rack shaft 7 via tie rods 8 and knuckle arms (not shown). The rotation of the steering wheel 2 is transmitted to the pinion shaft 6 via the steering shaft 3 and the intermediate shaft 4. The rotation of the pinion shaft 6 is converted into movement in the axial direction of the rack shaft 7. Thereby, the wheels 9 are turned.

The electric power steering device 1 obtains a steering assist force based on the steering torque applied to the steering wheels 2. To this end, as the mechanism, the electric power steering device 1 includes: a torque sensor 13 that detects steering torque; a control device 14; an electric motor 15 (drive source) for steering assist; and a deceleration device 20 that serves as The driving force of the electric motor 15 is transmitted to the transmission device of the steering mechanism 5.

In order to detect the steering torque by the torque sensor 13, the steering shaft 3 has an input shaft 10, a torsion bar 11, and an output shaft 12. If the steering wheel 2 is operated and a steering torque is input to the input shaft 10, the torsion bar 11 is twisted and deformed, and the input shaft 10 and the output shaft 12 rotate relatively. The torque sensor 13 detects the steering torque input to the steering wheel 2 based on the relative rotational displacement between the input shaft 10 and the output shaft 12. The detection result of the torque sensor 13 is input to the control device 14. The control device 14 controls the electric motor 15 based on the steering torque detected by the torque sensor 13 and the like.

The deceleration device 20 has a drive pulley 21, a driven pulley 22, and a helical belt 30 wound around the drive pulley 21 and the driven pulley 22. The driven pulley 22 has a larger outer diameter than the driving pulley 21. The driving pulley 21 is fixed to the rotating shaft of the electric motor 15. The driven pulley 22 is fixed to the pinion shaft 6. As shown in FIG. 2, a plurality of helical teeth 21 a are formed on the outer peripheral surface of the driving pulley 21. A plurality of helical teeth 22 a are formed on the outer peripheral surface of the driven pulley 22. The rotation speed of the driving pulley 21 is, for example, 1000 rpm or more and 4000 rpm or less. The load of the driven pulley 22 is, for example, 0.5 kW or more and 3 kW or less.

When the steering wheel 2 is operated, the steering torque is detected by the torque sensor 13 and the control device 14 drives the electric motor 15. When the electric motor 15 rotates the driving pulley 21, the helical belt 30 travels and the driven pulley 22 and the pinion shaft 6 rotate. The rotational force of the electric motor 15 is reduced by the reduction gear 20 and transmitted to the pinion shaft 6. Also, as described above, the rotation of the steering wheel 2 is transmitted to the pinion shaft 6 via the steering shaft 3 and the intermediate shaft 4. In addition, the rotation of the pinion shaft 6 is converted into the axial movement of the rack shaft 7, thereby turning the wheels 9. In this way, the electric motor 15 assists the rotation of the pinion shaft 6 and assists the driver's steering.

Furthermore, the structure of the electric power steering device 1 to which the helical belt 30 of the present invention can be applied is not limited to the structure shown in FIG. 1. For example, the driven pulley 22 of the reduction gear 20 may also be fixed to the intermediate shaft 4 or the steering shaft 3. Moreover, for example, the driven pulley 22 of the reduction gear 20 may be connected to the rack shaft 7 via a conversion mechanism. The conversion mechanism may be, for example, a ball screw mechanism or a bearing screw mechanism, which converts the rotational force of the driven pulley 22 into the axial force of the rack shaft 7 and transmits it to the rack shaft 7.

[Construction of the helical belt] As shown in Figure 3, the helical belt 30 has: a back 31 in which a core wire 33 is helically embedded along the length of the belt; and a plurality of teeth 32, which are oriented along the length of the belt. The specific interval is provided on the inner peripheral surface of the back 31 (equivalent to a surface of the back 31). In this embodiment, a plurality of teeth 32 are integrally formed on the inner peripheral surface of the back 31. In addition, as shown in FIG. 4, the tooth portion 32 extends obliquely with respect to the belt width direction. In addition, the inner peripheral surface of the helical toothed belt 30, that is, a part of the surface of the tooth portion 32 and the inner peripheral surface of the back 31 are covered by the tooth cloth 35. Furthermore, in this embodiment, the outer peripheral surface of the back 31 (corresponding to the other surface of the back 31) is not covered with cloth or the like, but it may be covered with a back cloth.

The circumference of the helical belt 30 is, for example, 150 to 400 mm. In addition, in this specification, the numerical range represented by "X-Y" means X or more and Y or less. The width W (refer to FIG. 4) of the helical belt 30 is, for example, 4-30 mm. The pitch P of the tooth portion 32 (refer to Fig. 3) is 2 mm or more and less than 4 mm. If the tooth pitch P is 2 mm or more and less than 3 mm, the thickness tb of the back 31 (refer to FIG. 3) is 0.4-1.2 mm, preferably 0.6 mm or more and 0.9 mm or less. If the tooth pitch P is 3 mm or more and less than 4 mm, the thickness tb of the back 31 is 0.6 to 1.8 mm, preferably 0.8 mm or more and 1.2 mm or less. If the tooth pitch P is 2 mm or more and less than 3 mm, the tooth height hb (refer to FIG. 3) of the tooth portion 32 is, for example, 0.7 to 2.0 mm, preferably 0.8 mm or more and 1.0 mm or less. If the tooth pitch P is 3 mm or more and less than 4 mm, the tooth height hb of the tooth portion 32 is, for example, 1.0-2.3 mm, preferably 1.1 mm or more and 2.0 mm or less. The total thickness (maximum thickness) t (refer to FIG. 3) of the helical tooth belt 30 is the sum of the thickness tb of the back 31 and the tooth height hb. The inclination angle θ of the tooth portion 32 with respect to the belt width direction (see FIG. 4) is, for example, 2 to 7°, preferably 2 to 6°.

[Back and teeth] The back 31 and the teeth 32 are composed of a rubber composition. As the rubber component of the rubber composition, chloroprene rubber (CR), nitrile rubber, hydrogenated nitrile rubber (HNBR), ethylene-propylene copolymer can be used (EPM), ethylene-propylene-diene terpolymer (EPDM), styrene-butadiene rubber, butyl rubber, chlorosulfonated polyethylene rubber, etc. The preferred rubber component is ethylene-propylene-diene terpolymer (EPDM), and chloroprene rubber and hydrogenated nitrile rubber (HNBR) can also be preferably used. In this embodiment, the rubber composition constituting the back portion 31 and the tooth portion 32 is formed of the same rubber composition, but it may be formed of different rubber compositions.

The rubber composition constituting the back portion 31 and the teeth portion 32 may contain various conventional additives (or compounding agents) as necessary. Examples of additives include vulcanizing agents or crosslinking agents (for example, oximes (benzoquinone dioxime, etc.), guanidines (diphenylguanidine, etc.), metal oxides (magnesium oxide, zinc oxide, etc.)), vulcanization aids Agents, vulcanization accelerators, vulcanization retarders, reinforcing agents (carbon black, hydrated silica, etc.), metal oxides (for example, zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, oxide Copper, titanium oxide, alumina, etc.), fillers (clay, calcium carbonate, talc, mica, etc.), plasticizers, softeners (oils such as paraffin oil, naphthenic oil, etc.), processing agents or processing aids Agents (stearic acid, metal salts of stearic acid, wax, paraffin, etc.), anti-aging agents (aromatic amine anti-aging agents, benzimidazole anti-aging agents, etc.), stabilizers (antioxidants, ultraviolet absorbers, etc.) Heat stabilizers, etc.), lubricants, flame retardants, antistatic agents, etc. These additives can be used alone or in combination, and can be selected according to the type, use, and performance of the rubber component.

[Core wire] The core wire 33 is buried in the back 31 in a spiral shape with a certain interval (0.45 mm or more and 0.6 mm or less) in the belt width direction along the belt length direction. In more detail, the core wire 33 is shown in FIGS. 3 and 5, and the distance between the core wire 33 and the center of the core wire 33 buried in a spiral shape from one end of the belt width direction of the back 31 to the other end is each core wire The pitch SP is arranged so that it becomes a constant value in the range of 0.45 mm to 0.6 mm. Furthermore, in this specification, as shown in FIG. 5, the apparent number of core wires arranged at a specific core wire pitch SP in the belt width direction under cross-sectional observation is regarded as the "number of core wires". That is, the number of spirals of the core wires 33 buried in a spiral shape is the "number of core wires".

Here, the so-called "number of core threads" is preferably to count only the number (effective number) that has an effect on the strength (elasticity) of the belt. Therefore, it is preferable that the core wires 33 arranged on one end and the other end of the back 31 of the helical tooth belt 30 that are not circular in cross-sectional view after cutting are not included in the effective number, and will not be cut under cross-sectional observation. The cut core wire 33 is counted as the effective number. However, in fact, since the core wire 33 is buried in a spiral shape, even in a ring-shaped helical toothed belt 30, the arrangement of the core wire 33 is different depending on the location of the collection section, and after being cut, The influence of the non-circular core wire 33 on the strength (elasticity) of the belt cannot be ignored under cross-sectional observation. Therefore, practically speaking, each core wire pitch SP becomes a certain range of 0.45 mm to 0.6 mm. When the value is calculated, the calculated value from the belt width divided by the core wire pitch SP (a certain value in the range from 0.45 mm to 0.6 mm) is the value after the decimal point is rounded off as the estimated "number of core wires" (Number of valid entries). For example, if the belt width is 25 mm and the core wire pitch SP is 0.56 mm, the calculated value is 44.64, and the "number of core wires" (effective number) is regarded as 44. Also, if the belt width is 25 mm and the core wire pitch SP is 0.52 mm, the calculated value is 48.07, and the "number of core wires" (effective number) is regarded as 48. Also, if the belt width is 25 mm and the core wire pitch SP is 0.60 mm, the calculated value is 41.67, and the "number of core wires" (effective number) is regarded as 41.

In addition, the core wire 33 is composed of a twisted wire formed by twisting a plurality of strands. One strand can be formed by bundling filaments (long fibers) and stretching and aligning them. The wire diameter of the core wire 33 is 0.2 to 0.6 mm. There are no special restrictions on the thickness of the filaments forming the twisted yarn, the number of bundles of the filaments, the number of strands, and the twisting method. The filament is made of high-strength glass fiber or carbon fiber. High-strength glass fiber and carbon fiber are both high-strength and low elongation, and are preferable as the material of the core wire 33, but from the viewpoint of low cost, high-strength glass fiber is better.

As high-strength glass fibers, for example, those with a tensile strength of 300 kg/cm ² or more can be preferably used, especially those with more Si components than alkali-free glass fibers (E glass fibers) as shown in Table 1 below. glass fiber. In addition, the composition of E glass fiber is also described in Table 1 below for the sake of comparison. Examples of such high-strength glass fibers include K glass fiber, U glass fiber (all manufactured by Nippon Glass Fiber Co., Ltd.), T glass fiber (manufactured by Nitto Weaving Co., Ltd.), R glass fiber (manufactured by VETROTEX), and S glass fiber , S-2 glass fiber, ZENTRON glass fiber (all manufactured by Owens Corning Fiberglass), etc.

[Table 1]

Examples of carbon fibers include pitch-based carbon fibers, polyacrylonitrile (PAN)-based carbon fibers, phenolic resin-based carbon fibers, cellulose-based carbon fibers, and polyvinyl alcohol-based carbon fibers. As commercial products of carbon fiber, for example, "TORAYCA (registered trademark)" manufactured by Toray Toray Co., Ltd., "TENAX (registered trademark)" manufactured by Toho Tenax Co., Ltd., and "DIALEAD (registered trademark) manufactured by Mitsubishi Chemical Co., Ltd. )"Wait. These carbon fibers can be used alone or in combination of two or more kinds. Among these carbon fibers, pitch-based carbon fibers and PAN-based carbon fibers are preferred, and PAN-based carbon fibers are particularly preferred.

The twisted wire used as the core wire 33 may be subjected to bonding treatment in order to improve the adhesion to the back 31. As the bonding treatment, for example, a method of immersing the twisted yarn in a resorcinol-formalin-latex treatment liquid (RFL treatment liquid) and then heating and drying to form an adhesive layer uniformly on the surface is adopted. The RFL treatment liquid is a latex that mixes the initial polycondensate of resorcinol and formalin. Examples of the latex used here include chloroprene, styrene·butadiene·vinylpyridine terpolymer ( VP latex), hydrogenated nitrile, NBR, etc. Furthermore, as the subsequent treatment, there is also a method of treating with an RFL treatment liquid after the pretreatment with an epoxy or isocyanate compound.

[Tooth cloth] The tooth cloth 35 is preferably composed of a woven cloth woven by crisscrossing the warp yarn and the weft yarn in a certain regular pattern. The weaving method of weaving can be any of twill weave, satin weave, etc. The form of warp and weft can be any of filaments (long fibers) stretched and aligned, or twisted multifilament yarn, 1 long fiber monofilament yarn, or twisted short fiber spun yarn (spun yarn) One. When the warp yarn or the weft yarn is a multifilament yarn or a spun yarn, it may also be a mixed twisted yarn or a mixed yarn using a plurality of fibers. The weft yarn preferably includes elastic yarn with stretchability. As the elastic yarn, for example, it is possible to use a stretched yarn having a material itself such as spandex fiber containing polyurethane, or a processed yarn in which the fiber is stretched (for example, wool-like processing, crimp processing, etc.). Generally speaking, no elastic yarn is used on the warp yarn. Therefore it is easy to weave. Moreover, as the tooth cloth 35, it is preferable to arrange|position so that the warp of a woven fabric may extend in the belt width direction, and the weft may extend in a belt length direction. Thereby, the stretchability of the tooth cloth 35 in the belt length direction can be ensured. Furthermore, the tooth cloth 35 may also be arranged such that the weft yarns of the woven fabric extend in the belt width direction and the warp yarns extend in the belt length direction. In this case, stretchable elastic yarns can be used as warp yarns. As the material of the fiber constituting the tooth cloth 35, any one or a combination of Nylon, aromatic polyamide, polyester, polybenzoxazole, cotton, etc. can be used.

The woven cloth used as the tooth cloth 35 can be treated with bonding in order to improve the adhesion with the back 31 and the tooth 32. As the bonding treatment, generally, a method of immersing a woven fabric in resorcinol-formalin-latex (RFL liquid) and then heating and drying to uniformly form an adhesive layer on the surface. However, it is not limited to this. In addition to the method of treating the fabric with RFL liquid after pretreatment with epoxy or isocyanate compound, the rubber composition can also be dissolved in methyl ethyl A method of preparing a rubber paste using organic solvents such as base ketone, toluene, and xylene, and impregnating and adhering the rubber composition by immersing the woven fabric in the rubber paste. These methods can be performed individually or in combination, and the processing order and the number of processing times are not particularly limited.

[Backing Cloth] Furthermore, in this embodiment, the outer peripheral surface of the back 31 (corresponding to the other surface of the back 31) is not covered with cloth or the like, but can be covered with the backing 36. When the outer peripheral surface of the back 31 is covered by the backing cloth 36, the backing cloth 36 is preferably composed of a woven cloth knitted by knitting yarns, or a woven cloth woven with warp yarns and weft yarns criss-crossed by a certain rule. .

The knitted fabric is a fabric having a structure in which a mesh (loop) is made from one or two or more knitted yarns, and the next thread is hooked on the loop to continuously make new loops. That is, in knitting, the threads are not staggered linearly, but are formed by making loops. When knitting cloth is used for the back cloth 36, the knitting cloth (or the knitting of the knitting cloth) can be either weft knitting (or knitting cloth knitting by weft knitting), warp knitting (or knitting cloth knitting by warp knitting) By. The shape of the knitted fabric is not limited to a flat shape, a cylindrical shape (circular knitting), etc. Moreover, either the front eye or the back eye of the knitted fabric can be the covering surface of the belt body. Examples of weft knitting (or weft knitting structure) include plain knitting (Tianzhu knitting), rib knitting, deer knitting, double rib knitting, and jacquard knitting. Moreover, as warp knitting (or warp knitting structure), for example, single bar, single strand, tricot, half tricot, etc. can be mentioned.

When a woven cloth is used as the back cloth 36, the weaving method of the woven cloth may be any of plain weave, twill weave, satin weave, and the like. From the viewpoint of ensuring the flexibility of the helical toothed belt 30, since it is easy to bend in the belt length direction, it is preferable to adopt a form in which the weaving structure or the braiding structure is easy to expand and contract in the belt length direction. Therefore, it is preferable to use a woven fabric containing elastic yarns with stretchability in the weft yarns, and the warp yarns of the woven fabric are arranged to extend in the belt width direction and the weft yarns to extend in the belt length direction. The form of the knitting yarn, or the warp and weft yarns of the weaving fabric, can be multifilament yarns that stretch or twist filaments (long fibers), a monofilament yarn of long fibers, and twist short fibers. Any of the spinning (spinning silk). When the warp yarn or the weft yarn is a multifilament yarn or a spun yarn, it may also be a mixed twisted yarn or a mixed yarn using a plurality of fibers. As the material of the fiber constituting the back cloth 36, any one of Nylon, aromatic polyamide, polyester, etc. or a combination of these can be used. In this case, the back 31 is further reinforced, and the rigidity of the helical belt 30 is improved.

The woven or knitted fabric used as the back cloth 36 may be subjected to an adhesive treatment in order to improve the adhesion with the back 31. As the adhesive treatment, it is preferable to immerse the cloth in resorcinol-formalin-latex (RFL liquid) and heat and dry it as in the case of the tooth cloth 35 to form an adhesive layer uniformly on the surface. However, it is not limited to this. In addition to the method of treating the cloth with RFL liquid after pre-treatment with epoxy or isocyanate compound, the rubber composition can also be dissolved in methyl ethyl A method of preparing a rubber paste with organic solvents such as ketone, toluene, and xylene, and impregnating and attaching the rubber composition to the rubber paste by impregnating a cloth. These methods can be performed individually or in combination, and the processing order and the number of processing times are not particularly limited. Furthermore, when the backing fabric 36 is a knitted fabric, in the method of manufacturing the helical belt 30 described later, the unvulcanized rubber sheet wound on the knitted fabric in the heating/pressurizing step is impregnated with the knitted fabric. No subsequent treatment may be applied.

[Belt elasticity rate of helical tooth belt] The belt elasticity rate of the helical tooth belt 30 in the belt length direction is preferably 0.96 MPa or more per 1 mm of belt width, and more preferably in the range of 0.96 MPa to 1.4 MPa. For example, in the case of a helical belt with a width of 25 mm, it is preferably 24 MPa or more, and furthermore, it is more preferably in the range of 24 MPa to 35 MPa. By setting the belt elasticity rate of the helical toothed belt 30 to be 0.96 MPa or more per 1 mm of the belt width, when the helical toothed belt 30 is wound between the pulleys, it can be ensured that the vibration of the helical toothed belt 30 is sufficiently suppressed. Obtain the rigidity of the helical belt with sufficient silence.

[Method of Manufacturing Helical Tooth Belt] The helical belt 30 is manufactured by the following procedure, for example. First, on a cylindrical mold (not shown) having a plurality of grooves corresponding to the plurality of teeth 32 of the helical toothed belt 30, the woven fabric subjected to the bonding process for forming the tooth cloth 35 is wound. Next, the twisted yarn constituting the core yarn 33 is spirally spun onto the outer peripheral surface of the wound woven fabric. Furthermore, an unvulcanized rubber sheet for forming the back portion 31 and the teeth portion 32 is wound around the outer peripheral side thereof to form an unvulcanized belt molded body.

Moreover, when covering the back cloth 36, after winding the unvulcanized rubber sheet for forming the back part 31 and the teeth part 32, the braid or woven cloth forming the back cloth 36 is wound. When a woven cloth is used as the back cloth 36, the woven cloth is subjected to an adhesive treatment in advance before winding. On the other hand, when a knitted cloth is used as the back cloth 36, no adhesive treatment may be applied.

Next, in a state where the unvulcanized belt molded body is arranged on the outer periphery of the cylindrical mold, a rubber jacket as a steam blocking material is further covered on the outside. Then, the belt molded body covered with the jacket and the cylindrical mold are housed in the vulcanizing tank. Then, the belt molded body is heated and pressurized inside the vulcanizing tank to vulcanize the rubber sheet. Thereby, the rubber composition of the rubber sheet is pressed into the groove of the mold to form the teeth 32. Then, a plurality of helical tooth belts 30 are obtained by cutting the sleeve-shaped molded body after demolding to a specific width.

According to the above-mentioned helical toothed belt 30, since the surface of the back portion 31 on the side of the tooth portion 32 is constituted by the tooth cloth 35, it is reinforced to increase the rigidity. In addition, the core wire 33 embedded in the back 31 is a twisted yarn containing high-strength (high elastic modulus) fiber material, that is, high-strength glass fiber or carbon fiber, and the wire diameter of the twisted yarn is 0.2 mm or more and 0.6 mm or less. Therefore, the flexibility of the back 31 can be ensured, and the rigidity of the back 31 can be further improved by the core wire 33.

By increasing the rigidity of the back 31 in this way, even if the helical toothed belt 30 is used in the deceleration device 20 driven by high load or high-speed rotation, the teeth 32 can be prevented from meshing with the teeth of the driving pulley 21 or the driven pulley 22 The vibration (string vibration) centered on the core wire 33 of the helical tooth belt 30 is generated. In this way, the noise caused by vibration can be reduced.

In addition, the core wires 33 embedded in the back 31 are arranged such that the pitch SP of each core wire between the core wires falls within a range of 0.45 mm or more and 0.6 mm or less. In this way, the rigidity of the helical belt 30 is further improved without further increasing the thickness of the back 31 or further increasing the wire diameter of the core wire 33 (without sacrificing flexibility).

Also, if the tooth pitch P is 2 mm or more and less than 3 mm, the thickness of the back 31 is 0.4 mm or more and 1.2 mm or less. If the tooth pitch P is 3 mm or more but less than 4 mm, the thickness of the back 31 is 0.6 mm or more and 1.8 mm or less. These thicknesses are, for example, the same degree as the thickness of the back of the previous helical belt used in the reduction gear 20 of the electric power steering device 1 for automobiles. The helical tooth belt 30 of the present invention can increase the rigidity of the back 31 without increasing the thickness of the back 31. Therefore, the flexural fatigue resistance can be sufficiently ensured, and vibration and noise can be further suppressed.

In addition, by using the above-mentioned helical belt 30 in the reduction gear 20 of the electric power steering system 1 for automobiles whose outer diameter of the driven pulley 22 is larger than the outer diameter of the driving pulley 21, noise and vibration can be sufficiently reduced.

As mentioned above, the preferred embodiment of the present invention has been described, but the present invention is not limited to the above-mentioned embodiment, and various changes can be made within the scope of the described patent application. [Example]

Next, the helical belts of Examples 1 to 17 and Comparative Examples 1 to 6 were produced, and the measurement of the belt elasticity, the sound pressure measurement test, and the cold resistance test described later were performed.

Twisted yarns of A1 to A4 having the configurations shown in Table 2 below were produced as core yarns used in the helical belts of Examples 1 to 17 and Comparative Examples 1 to 6.

The twisted yarn of A1 is made using the following procedure. The filament bundles of glass fiber named KCG150 described in JIS R 3413 (2012) are assembled and stretched to form 3 strands. The three strands were immersed in RFL liquid (18-23°C) with the composition shown in Table 3 below for 3 seconds, and then heated and dried at 200-280°C for 3 minutes to form a uniform adhesive on the surface. Floor. After this subsequent treatment, the three strands were twisted at a number of twists of 12 times/10 cm, and no upper twist was applied, and a twisted yarn with a wire diameter of 0.35 mm was prepared with a single twist. The twisted yarns of A2 and A3 were produced in the same manner as A1 except that the glass fibers were changed to UCG150 and ECG150. The A4 twisted yarn is produced by the same procedure as the core yarn of A1～A3, except that the strand used is a strand of carbon fiber (3K) bundled and stretched in alignment. A twisted wire with a wire diameter of 0.53 mm is formed.

[Table 2] Table 2 (Composition of core wire)

(The modulus of elasticity of the core wire) Here, the measuring method of the modulus of elasticity (tensile modulus) of the core wire (length direction) shown in Table 2 will be described. Install a chuck on the lower fixing part and the upper load cell connection part of Autograph ("AGS-J10 kN" manufactured by Shimadzu Corporation) to fix the core wire. Next, raise the upper chuck and apply stress (about 10 N) to the extent that the core wire is not loosened. Taking the position of the upper chuck in this state as the initial position, the upper chuck is raised at a speed of 250 mm/min. After the core wire stress reaches 200 N, the upper chuck is immediately lowered and returned to the initial position. The slope (average slope) of the straight line in the region (100-200 N) with a relatively straight line relationship on the stress-deflection curve measured at this time is calculated as the tensile elastic modulus of the core wire.

[Table 3] Table 3 (RFL liquid)

The tooth cloth used for the helical tooth belts of Examples 1-17 and Comparative Examples 1-6 was made into one type. A twill weave fabric is used for the tooth cloth, and it is arranged so that the warp yarns of the fabric extend in the belt width direction and the weft yarns extend in the belt length direction. As the weft yarn for weaving, we use 66-nylon multifilament yarn with a fineness of 155 dtex, and spandex (polyurethane elastic fiber) multifilament yarn with a fineness of 122 dtex. The weaving warp uses 66-nylon multifilament yarn with a fineness of 155 dtex. In addition, dtex (Decitex, decitex) is a unit that expresses the mass of 10,000 meters of thread in grams.

The woven fabric used for the tooth cloth was immersed by passing it through the RFL solution (18-23°C) shown in Table 3 for 10 seconds, and then heated and dried at 150-170°C for 3 minutes to give a uniform surface Adhesive processing to form an adhesive layer.

The unvulcanized rubber sheet with the composition C1 shown in Table 4 below was produced as an unvulcanized rubber sheet for forming the back and teeth of the helical belt of Examples 1-17 and Comparative Examples 1-6.

[Table 4] Table 4 (Composition of unvulcanized rubber sheet)

*1 "EPT" manufactured by Mitsui Chemicals Co., Ltd. *2 "NOCRAC MB" manufactured by Ouchi Shinko Chemical Industries Co., Ltd. *3 "N-cyclohexyl-2-benzothiazole sulfenamide" manufactured by Ouchi Shinko Chemical Industries Co., Ltd. *4 "Tokai" "SEAST 3" manufactured by Carbon Corporation ※5　"Zinc Oxide 3 Types" manufactured by Zhengdo Chemical Industry Co., Ltd.

The helical belts of Examples 1 to 17 and Comparative Examples 1 to 6 were produced using twisted wires (core wires) A1 to A4, tooth cloth, and an unvulcanized rubber sheet of composition C1 using the procedures described in the above embodiment. The vulcanization system was carried out at 161°C for 25 minutes. The following Tables 5 to 8 show the structure of the helical belts of Examples 1 to 17 and Comparative Examples 1 to 6. The belt widths of the helical toothed belts of Examples 1 to 17 and Comparative Examples 1 to 6 were all set to 25 mm, and the inclination angles of the teeth with respect to the belt width direction were all set to 5°.

[Table 5] Table 5 (Comparison with a tooth pitch of 2 mm)

[Table 6] Table 6 (Comparison between tooth pitch 2 mm and back thickness 0.4~1.2 mm)

[Table 7] Table 7 (Comparison with a tooth pitch of 3 mm)

[Table 8] Table 8 (Comparison between tooth pitch 3 mm and back thickness 0.6~1.8 mm)

(Measurement of Belt Elastic Modulus) The belt elastic modulus (tensile elastic modulus) was measured for the helical toothed belts (belt length direction) of Examples 1 to 17 and Comparative Examples 1 to 6. The measurement method of belt elasticity is explained. Install a pair of pulleys (30 teeth, 18.6 mm outer diameter) on the lower fixing part and upper load cell connection part of Autograph ("AGS-J10 kN" manufactured by Shimadzu Corporation), and hang the helical belt on the pulley. Secondly, raise the upper pulley and apply stress (about 10 N) to the extent that the helical tooth belt does not loosen. Taking the position of the upper pulley in this state as the initial position, make the upper pulley rise at a speed of 50 mm/min. After the stress of the helical belt reaches 500 N, immediately lower the upper pulley and return to the initial position. The slope (average inclination) of the straight line in the region (100-50 N) with a relatively straight line relationship on the stress-deflection curve measured at this time is calculated as the tensile elastic modulus of the belt. In addition, when the belt elasticity is 24 MPa or more (0.96 MPa or more per 1 mm of belt width), it is estimated that the rigidity of the helical belt is high.

(Sound pressure measurement test) Furthermore, a sound pressure measurement test was performed on the helical toothed belts of Examples 1 to 17 and Comparative Examples 1 to 6, and the noise during belt running was evaluated. In the experiment, a two-axis walking testing machine was used. This biaxial traveling tester adopts a structure having a driving pulley 21 and a driven pulley 22 having a larger diameter than the driving pulley 21 as in the reduction gear shown in FIG. 2. For the driving pulley 21, a pulley with 40 teeth is used, and for the driven pulley 22, a pulley with 107 teeth is used. Wrap the helical belt 30 on two pulleys, adjust the distance between the pulleys so that the belt tension becomes 90 N, apply a load of 5 Nm to the driven pulley 22, and make the driving pulley 21 rotate at a rotation speed of 1200 rpm. The helical tooth belt 30 travels. The ambient temperature is set to 23°C. Then, the sound pressure (noise level) is measured by the sound collection microphone M of the noise meter. In addition, in order to explain the position of the sound collecting microphone M, the sound collecting microphone M is displayed in the deceleration device shown in FIG. 2. Specifically, the sound collecting microphone M is arranged such that the straight line A passing through the center position S of the driving pulley 21 and perpendicular to the straight line T passing through the center position S of the driving pulley 21 and the center position K of the driven pulley 22 moves toward the driven The direction of the pulley 22 moves in parallel by 25 mm, and the outer peripheral surface of the helical belt 30 is separated from the outer peripheral surface of the helical belt 30 by 30 mm from the outer peripheral surface of the belt 30 in parallel. The measurement results measured by the sound-collecting microphone M are shown in Tables 5 to 8. If the sound pressure is less than 63 dBA, it is evaluated as a pass as the noise level of the helical toothed belt without practical problems.

(Cold resistance test) In addition, a cold resistance (low temperature resistance) test was performed using a biaxial traveling tester with the same configuration as the above sound pressure measurement test. The ambient temperature is set to -40°C, and the driving pulley 21 is rotated at a rotation speed of 2000 rpm under no load. After walking for 6 seconds, stop for 10 minutes as 1 cycle, and perform 1000 cycles. In addition, during the 500th cycle and the 1000th cycle, visually confirm whether there are cracks on the back surface of the helical tooth belt. The results of this confirmation are shown in Tables 5 to 8 using levels A, B, and C. Level A is not cracked even in the 1000th cycle. Grade B is a situation in which no cracks are produced in the 500th cycle, but cracks are produced in the 1000th cycle. Level C is a situation where cracks occur in the 500th cycle. As an indicator of cold resistance (low temperature resistance), if the belt is used in a cold area where the lowest temperature reaches -40℃, compared with the belt of grade A, it is positioned in the order of grade B and C to easily reach the life of cracks. Poor low temperature grade. Based on the point of view that it is suitable for practical use in cold areas where the lowest temperature reaches -40℃, belts of grades A and B are suitable, especially belts of grade A are suitable for use.

(Verification when the pitch of the core wire is changed at a tooth pitch of 2 mm) In Examples 1 to 5, 7, and 8 shown in Table 5, sufficient vibration suppression can be ensured and sufficient quietness can be obtained (sound pressure is 63 The rigidity of the belt (below dBA) (belt elasticity: 24 MPa or more). Although the core wire pitch is dense in Comparative Example 1, in the case of a glass fiber with a small elastic modulus of the core wire, the belt elastic modulus (less than 24 MPa) that can suppress vibration cannot be ensured, and the effect of reducing the sound pressure is not full. In addition, although Comparative Example 2 is a high-strength glass fiber with a large elastic modulus of the core wire, because the core wire pitch is large (0.64 mm), the elastic modulus (less than 24 MPa) of the belt that can suppress vibration cannot be ensured, and it is lowered The effect of sound pressure is not sufficient. Therefore, it can be judged that the lower limit of the elastic modulus (tensile elastic modulus in the longitudinal direction) of the belt with the effect of suppressing vibration is 24 MPa (0.96 MPa per 1 mm of belt width).

In addition, Comparative Example 1 has the same configuration as Example 2 except for the material of the core wire. It is an example of core wire A3 using E glass fiber, which is not high-strength glass fiber. The sound pressure is 64 dBA, which exceeds the criterion. Comparative Example 2 has the same structure as Comparative Example 1 except for the material of the core wire, and the core wire pitch SP (0.64 mm) is larger than Comparative Example 1. In this case, the sound pressure is greater than the criterion (63 dBA or less is qualified).

In any of Examples 1 to 5, 7, and 8, the sound pressure is below 63 dBA of the judgment criterion. Examples 2, 3, and 7 have the same configuration as Example 1. Example 2 sets the core wire pitch (0.52 mm) to be smaller than Example 1 (0.56 mm), and Example 7 (0.48 mm) is set It is smaller than Example 2, and Example 3 (0.60 mm) is set as a larger example than Example 1. Among Examples 7, 2, 1, and 3, Example 7 has the lowest sound pressure (58 dBA).

Example 4 and Example 2 differ only in the type of fiber constituting the core wire (U glass), Example 5 and Example 1 only differ in the type of fiber constituting the core wire (carbon), Example 8 and Example 3 It differs only in the type of fiber constituting the core (carbon). In Examples 4, 5, and 8, there was no significant difference in sound pressure.

Based on the above, it can be confirmed that if the tooth pitch is 2 mm, noise can be suppressed within the range of 0.45 to 0.6 mm core wire pitch.

(Verification when the back thickness is changed at a tooth pitch of 2 mm) As shown in Table 6, in Example 9 (0.45 mm), where the back thickness is smaller than Example 1 (the back thickness is 0.85 mm), Due to the low rigidity of the helical belt, the sound pressure is barely as large as 63 dBA, which is a qualified benchmark. On the other hand, in Example 10 (1.15 mm) in which the back thickness was large, although the sound pressure was lowered and the quietness was improved, the cold resistance was lowered (determined as B). In Comparative Example 3 (1.30 mm) in which the back thickness is larger, although the sound pressure is further reduced, the cold resistance is further reduced (determined as C). In short, the back thickness (0.85 mm) of the balanced embodiment 1 is the best.

In addition, the so-called decrease in cold resistance refers to problems such as cracks and the like when used in a low-temperature environment (buckling walking). When using a helical toothed belt in automotive applications, it is important to assume cold resistance for use in cold regions (for example, -40°C). According to the above-mentioned Examples 1, 9, 10 and Comparative Example 3, although the sound pressure increases and the quietness decreases if the thickness of the back is reduced, the opposite side is that the rigidity of the helical toothed belt decreases (flexibility is improved) and the cold resistance On the other hand, if the thickness of the back is increased, the sound pressure decreases and the quietness improves. On the other hand, the rigidity of the helical belt increases (flexibility decreases) and the cold resistance decreases. Therefore, the upper and lower limits of the thickness of the back become important. According to the above-mentioned Examples 1, 9, 10 and Comparative Example 3, it is considered that if the tooth pitch is 2 mm or more and less than 3 mm, the thickness of the back can be 0.4-1.2 mm. , Preferably 0.6 mm～0.9 mm.

(Verification when the pitch of the core wire is changed at a tooth pitch of 3 mm) In Examples 6, 11 to 15 shown in Table 7, sufficient vibration suppression can be ensured and sufficient quietness can be obtained (sound pressure is 63 dBA or less ) The rigidity of the belt (belt elasticity: 24 MPa or more). In Comparative Example 4, although the core wire pitch is dense, in the case of a glass fiber with a small elastic modulus of the core wire, the belt elastic modulus (less than 24 MPa) that can suppress vibration cannot be ensured, and the effect of reducing the sound pressure is not full. In addition, although Comparative Example 5 is a high-strength glass fiber with a large elastic modulus of the core wire, because the core wire pitch is large (0.64 mm), the elastic modulus (less than 24 MPa) of the belt that can suppress vibration cannot be ensured, and it is reduced The effect of sound pressure is not sufficient. Therefore, it can be judged that the lower limit of the elastic modulus (tensile elastic modulus in the longitudinal direction) of the belt with the effect of suppressing vibration is 24 MPa (0.96 MPa per 1 mm belt width).

In addition, Comparative Example 4 has the same configuration as Example 6 except for the material of the core wire. It is an example of core wire A3 using E glass fiber that is not high-strength glass fiber. The sound pressure is 66 dBA, which exceeds the criterion. Comparative Example 5 has the same configuration as Comparative Example 4 except for the material of the core wire, and the core wire pitch SP (0.64 mm) is larger than Comparative Example 4. In this case, the sound pressure is greater than the criterion (63 dBA or less is qualified).

In any of Examples 6, 11-15, the sound pressure is below 63 dBA of the judgment criterion. Examples 6, 13, and 11 have the same configuration as Example 12. Example 6 sets the core wire pitch (0.52 mm) to be smaller than Example 12 (0.56 mm), and Example 11 (0.48 mm) is set It is smaller than Example 6, and Example 13 (0.60 mm) is set to be larger than Example 12. Among Examples 6, 11-13, Example 11 has the lowest sound pressure (60 dBA).

Example 14 and Example 12 differ only in the type of fiber constituting the core wire (carbon), and Example 15 and Example 13 differ only in the type of fiber constituting the core wire (carbon). In Examples 14 and 15, there was no significant difference in sound pressure, and any of them had the same low sound pressure as in Example 11.

Based on the above, it can be confirmed that if the tooth pitch is 3 mm, the noise can be suppressed in the range of 0.45 to 0.6 mm core wire pitch.

(Verification when the back thickness is changed at a tooth pitch of 3 mm) As shown in Table 8, in Example 16 (0.65 mm) where the back thickness is smaller than Example 6 (back thickness 1.00 mm), due to The rigidity of the helical toothed belt is small, so the sound pressure is barely as large as 63 dBA, which is a qualified benchmark. On the other hand, in Example 17 (1.75 mm) where the back thickness was large, although the sound pressure was lowered and the quietness was improved, the cold resistance was lowered (determined as B). Furthermore, in Comparative Example 6 (1.90 mm) in which the back thickness was larger, although the sound pressure was further reduced, the cold resistance was further reduced (determined as C). In short, the back thickness (1.00 mm) of the balanced embodiment 6 is the best.

Therefore, according to the foregoing Examples 6, 16, 17 and Comparative Example 6, it can be considered that if the tooth pitch is 3 mm or more and less than 4 mm, the thickness of the back can be 0.6-1.8 mm, preferably 0.8 mm-1.2 mm.

As mentioned above, the preferred embodiment of the present invention has been described, but the present invention is not limited to the above-mentioned embodiment, and various design changes can be made as long as it is within the scope of the described patent application. This application is based on Japanese Patent Application No. 2017-135270 filed on July 11, 2017, Japanese Patent Application No. 2018-073854 filed on April 6, 2018, and Japanese Patent Application 2018 filed on June 27, 2018 It was created under No. -121700, and its content is incorporated into this application as a reference.

1‧‧‧Electric Power Steering (EPS) device 2‧‧‧Steering wheels 3‧‧‧Steering shaft 4‧‧‧Intermediate shaft 5‧‧‧Steering mechanism 6‧‧‧Pinion shaft 6a‧‧‧Pinion 7‧ ‧‧Rack shaft 7a‧‧‧Rack 8‧‧‧Tie rod 9‧‧‧Wheel 10‧‧‧Input shaft 11‧‧‧Torsion bar 12‧‧‧Output shaft 13‧‧‧Torque sensor 14‧ ‧‧Control device 15‧‧‧Electric motor (drive source) 20‧‧‧Deceleration device (belt drive) 21‧‧‧Drive pulley 21a‧‧‧Helical tooth 22‧‧‧Driven pulley 22a‧‧‧Heltic tooth 30‧‧‧Heltic tooth belt 31‧‧‧Back 32‧‧‧Tooth part 33‧‧Core wire 35‧‧‧Tooth cloth A‧‧‧Line B‧‧‧The part that meets the outer peripheral surface of the helical belt hb ‧‧‧Tooth height K‧‧‧Center position M‧‧‧Sound microphone P‧‧‧Tooth pitch S‧‧‧Center position SP‧‧‧Core pitch t‧‧‧Total thickness (maximum thickness)tb‧‧ ‧Back thickness T‧‧‧Straight line W‧‧‧Width θ‧‧‧Intersection angle of teeth

Fig. 1 is a schematic diagram showing the schematic configuration of an electric power steering device to which the helical belt of this embodiment is applied. Figure 2 is a side view of the deceleration device of the electric power steering device. Figure 3 is a partial perspective view of the helical belt. Figure 4 is a view of the oblique tooth belt viewed from the inner peripheral side. Figure 5 is a cross-sectional view of the helical tooth belt in the belt width direction.

30‧‧‧Bevel belt

31‧‧‧Back

32‧‧‧tooth

33‧‧‧Core

35‧‧‧Tooth cloth

hb‧‧‧tooth height

t‧‧‧Total thickness (maximum thickness)

tb‧‧‧The thickness of the back

P‧‧‧tooth pitch

SP‧‧‧Core pitch

Claims (13)

A helical toothed belt, characterized by having: a back part in which a core wire is embedded; and a plurality of teeth parts, which are arranged on one surface of the back part at specific intervals along the length direction of the belt, and are each inclined with respect to the width direction of the belt; And a part of the surface of the tooth part and the one surface of the back part are made of tooth cloth, the tooth pitch of the plurality of teeth is 2mm or more but less than 4mm, if the tooth pitch of the plurality of teeth is 2mm or more and less than 3mm, the thickness of the back is 0.4mm or more and 1.2mm or less. If the tooth pitch of the plurality of teeth is 3mm or more and less than 4mm, the thickness of the back is 0.6mm or more and 1.8mm or less. The core wire contains high strength The twisted wires of glass fiber or carbon fiber with a wire diameter of 0.2mm or more and 0.6mm or less are arranged in such a way that the pitch of each core wire between the aforementioned core wire and the core wire falls within the range of 0.45mm to 0.6mm. Such as the helical tooth belt of claim 1, wherein the core wire embedded in the back is from one end to the other end in the belt width direction of the helical tooth belt, and the pitch of each core wire is within the range of 0.45mm or more and 0.6mm or less Arranged by a certain value. For example, the helical tooth belt of claim 1 or 2, wherein if the tooth pitch of the plurality of teeth is 2mm or more and less than 3mm, the tooth height of the tooth is 0.7mm or more and 2.0mm or less. If the tooth pitch is 3mm or more but less than 4mm, the tooth height of the aforementioned tooth part is 1.0mm or more and 2.3mm or less. The helical tooth belt of claim 1 or 2, wherein the back portion contains a rubber component, and the rubber component contains ethylene-propylene-diene terpolymer or hydrogenated nitrile rubber. For example, the helical tooth belt of claim 1 or 2, wherein the tooth cloth is composed of a woven cloth including warp yarns and weft yarns, the warp yarns or weft yarns are arranged to extend in the belt length direction, and the warp yarns or weft yarns arranged in the belt length direction contain Stretchable elastic yarn. The helical tooth belt of claim 1 or 2, wherein the fiber constituting the tooth cloth contains at least one fiber selected from the group consisting of nylon, aromatic polyamide, polyester, polybenzoxazole, and cotton . The helical tooth belt of claim 1 or 2, wherein the other surface of the back is composed of a back cloth, and the fiber constituting the back cloth contains selected from the group consisting of Nylon, aromatic polyamide, and polyester At least one fiber. Such as the oblique tooth belt of claim 1 or 2, wherein the belt elasticity of the aforementioned oblique tooth belt is 0.96 MPa or more per 1 mm of belt width. Such as the oblique tooth belt of claim 1 or 2, wherein the belt elasticity of the aforementioned oblique tooth belt is 0.96MPa or more and 1.4Mpa or less per 1mm of belt width. A belt transmission device is provided with: a driving pulley, which is rotated by a driving source Drive; driven pulley; and helical toothed belt wound on any one of claims 1 to 8 of the aforementioned drive pulley and the aforementioned driven pulley. Such as the belt transmission device of claim 10, wherein the rotation speed of the aforementioned driving pulley is 1000 rpm or more and 4000 rpm or less. Such as the belt drive of claim 10 or 11, wherein the load of the aforementioned driven pulley is 0.5kW or more and 3kW or less. Such as the belt transmission of claim 10 or 11, wherein the outer diameter of the driven pulley is greater than the outer diameter of the driving pulley, and the belt transmission is a reduction gear of an electric power steering device for automobiles.

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