WO2019013232A1

WO2019013232A1 - Helical belt and belt transmission gear

Info

Publication number: WO2019013232A1
Application number: PCT/JP2018/026105
Authority: WO
Inventors: 弘晃池上; 吉田　正邦
Original assignee: 三ツ星ベルト株式会社
Priority date: 2017-07-11
Filing date: 2018-07-10
Publication date: 2019-01-17
Also published as: TWI697634B; CN110869640B; TW201908619A; CN110869640A

Abstract

The present invention pertains to a helical belt having a back part in which a core wire is embedded, and a plurality of teeth parts that are provided to one surface of the back part at prescribed intervals along a belt longitudinal direction and are each inclined relative to a belt width direction, wherein the helical belt is characterized in that: the surfaces of the teeth parts and part of the one surface of the back part are configured from tooth cloth; the tooth pitch of the plurality of teeth parts is at least 2 mm and less than 4 mm; when the tooth pitch of the plurality of teeth parts is at least 2 mm and less than 3 mm, the thickness of the back part is 0.4-1.2 mm; when the tooth pitch of the plurality of teeth parts is at least 3 mm and less than 4 mm, the thickness of the back part is 0.6-1.8 mm; the core wire is a twisted cord containing high-strength glass fibers or carbon fibers, the diameter of the cord being 0.2-0.6 mm; and the core wire is arranged so that the core wire pitch between two parts of the core wire is in a range of 0.45-0.6 mm.

Description

Spiral tooth belt and belt transmission

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

For example, in a belt transmission driven at high load or high speed as in a reduction gear of an electric power steering apparatus, when a straight toothed belt having teeth extending parallel to the belt width direction is used, the belt teeth and At the start and end of meshing with the teeth of the pulleys, loud noises and vibrations occur. As a countermeasure against this problem, a helical tooth belt is used in which the teeth are arranged obliquely to the belt width direction. In the helical belt, meshing of the teeth of the belt and the teeth of the pulley sequentially advances from one end of each tooth to the other end. Therefore, noise and vibration can be reduced as compared to a belt transmission using a straight toothed belt.

However, even with helical belts, noise and vibration may not always be reduced sufficiently. On the other hand, for example, Patent Document 1 and Patent Document 2 propose a technology for further reducing noise and vibration in a belt transmission driven by high load or high speed rotation using a helical belt. There is.

In Patent Document 1, assuming that the tooth pitch is Pt and the belt width is W, the tooth ridge angle θ is set to a value that satisfies −0.2 ≦ 1−W · tan θ / Pt ≦ 0.75. In addition, the backlash (gap) between the teeth of the helical tooth belt and the teeth of the pulley is set to 1.6% to 3% of the tooth pitch Pt.

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

In recent years, since the quietness of automobiles has progressed, for example, belt transmission devices such as a reduction gear of an electric power steering device are required to further reduce noise. However, with the techniques of Patent Document 1 and Patent Document 2, there is a possibility that noise and vibration can not be reduced to a satisfactory level.

Japanese Patent Application Laid-Open No. 2004-308702 International Publication No. 2014/024377

In this regard, in order to reduce noise and vibration, it is conceivable to increase the rigidity (elastic modulus) of the helical belt. As a method of increasing the rigidity, there is a method of increasing the thickness of the helical tooth belt (especially the thickness of the back). However, even if vibration and noise can be suppressed by this method, the flexibility of the helical tooth belt is deteriorated, so that the bending fatigue on the pulley is increased, and in particular, the crack is likely to occur in a low temperature environment.

Therefore, the present invention can increase the rigidity without increasing the thickness of the helical belt, and can further reduce noise and vibration when used in a belt transmission driven by high load or high speed rotation. Intended to provide a belt.

One of the modes of the present invention is a back in which a core wire is embedded,
A helical tooth belt having a plurality of tooth portions provided on one surface of said back along the longitudinal direction of the belt at predetermined intervals and each inclined with respect to the belt width direction,
The surface of the teeth and a portion of the one surface of the back are made of a tooth cloth,
The tooth pitch of the plurality of teeth is 2 mm or more and less than 4 mm,
When the tooth pitch of the plurality of teeth is 2 mm or more and less than 3 mm, the thickness of the back is 0.4 mm or more and 1.2 mm or less,
When 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 core wire is a twisted cord containing high-strength glass fiber or carbon fiber and having a diameter of 0.2 mm or more and 0.6 mm or less, and each core wire pitch between the core wire and the core wire is 0.45 mm. It is characterized in that it is arranged in the range of not less than 0.6 mm.

According to the above configuration, the surface on the tooth side of the back portion is reinforced by the tooth cloth, and the rigidity is enhanced. Moreover, the core wire embedded in the back is a twisted cord containing high strength glass fiber or carbon fiber which is a high strength (high elastic modulus) fiber material, and the diameter of the twisted cord is 0.2 mm or more. It is 6 mm or less. Therefore, the rigidity of the back can be further enhanced by the core wire while securing the flexibility of the back.
Thus, even if the helical gear belt is used for a belt transmission driven by high load or high speed rotation, the teeth of the helical gear belt mesh with the teeth of the pulley because the rigidity of the spine is enhanced. Vibration (chord vibration) centered on the center line of the helical belt can be suppressed. Thereby, the noise generated by the vibration can be reduced.

The cords embedded in the back are arranged such that each core pitch between the cores is in the range of 0.45 mm or more and 0.6 mm or less. Thereby, the stiffness of the helical tooth belt can be further enhanced without further increasing the thickness of the back or increasing the diameter of the core wire (without sacrificing the flexibility).

When the tooth pitch is 2 mm or more and less than 3 mm, the thickness of the back is 0.4 mm or more and 1.2 mm or less. When the tooth pitch 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 thicknesses of these are, for example, about the same as the thickness of the back of a conventional helical tooth belt used for a reduction gear of an electric power steering apparatus for automobiles. The helical belt of the present invention can increase the rigidity of the back without increasing the thickness of the back. Therefore, vibration and noise can be further suppressed while securing sufficient bending fatigue resistance.

Further, according to one aspect of the present invention, in the above-mentioned helical belt, the above-mentioned core wire embedded in the above-mentioned back portion extends from one end to the other end of the helical belt in the belt width direction. The core line pitch may be arranged to be a constant value in the range of 0.45 mm or more and 0.6 mm or less.

According to the above configuration, the rigidity of the helical tooth belt can be further enhanced without further increasing the thickness of the back or increasing the diameter of the core wire (without sacrificing flexibility). , Vibration and noise can be suppressed more.

In one aspect of the present invention, in the helical tooth belt, when 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,
When the tooth pitch of the plurality of tooth portions is 3 mm or more and less than 4 mm, the tooth height of the tooth portions may be 1.0 mm or more and 2.3 mm or less.

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

In one embodiment of the present invention, in the above-mentioned helical belt, the back may include a rubber component, and the rubber component may include an ethylene-propylene-diene terpolymer or a hydrogenated nitrile rubber.

Further, according to one aspect of the present invention, in the above-mentioned helical belt, the tooth cloth is made of a woven fabric including warp and weft, and the warp or weft is arranged to extend in the longitudinal direction of the belt. The warp or weft disposed so as to extend in the longitudinal direction of the belt may include an elastic yarn having elasticity.

Further, according to one aspect of the present invention, in the above-mentioned helical belt, at least one fiber selected from the group consisting of nylon, aramid, polyester, polybenzoxazole, and cotton, which constitutes the tooth cloth May be included.

Further, according to one aspect of the present invention, in the helical belt described above, the other surface of the back is made of a backing cloth,
The fibers constituting the back fabric may include at least one fiber selected from the group consisting of nylon, aramid, and polyester.

According to the above configuration, the other side of the back is made of the back cloth, and the fibers constituting the back cloth include at least one type of fiber selected from the group consisting of nylon, aramid, and polyester. It is further reinforced to increase its rigidity.

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

According to the above configuration, it is possible to secure the rigidity of the helical tooth belt that can suppress vibration and obtain sufficient quietness.

Further, according to one aspect of the present invention, there is provided a drive pulley rotationally driven by a drive source,
Driven pulley,
It may be a belt transmission provided with the above-mentioned helical tooth belt wound on the above-mentioned driving pulley and the above-mentioned driven pulley.

According to the above configuration, noise and vibration can be reduced in the belt transmission that transmits the driving force of the driving pulley to the driven pulley.

In one aspect of the present invention, in the above-described belt transmission, the rotational speed of the drive pulley may be 1000 rpm or more and 4000 rpm or less.

According to the above configuration, noise and vibration can be sufficiently reduced in the belt transmission driven at high speed.

In one aspect of the present invention, in the above-described belt transmission, the load of the driven pulley may be 0.5 kW or more and 3 kW or less.

According to the above configuration, noise and vibration can be sufficiently reduced in a belt drive driven at high load.

Further, according to one aspect of the present invention, in the above-described belt transmission, an outer diameter of the driven pulley is larger than an outer diameter of the drive pulley.
The belt transmission may be a reduction gear of an electric power steering apparatus for a car.

According to the above configuration, noise and vibration can be sufficiently reduced in the reduction gear of the electric power steering apparatus for a car.

To provide a helical tooth belt capable of further reducing noise and vibration when it is used for a belt transmission driven by high load or high speed rotation without increasing the thickness of the helical tooth belt. it can.

FIG. 1 is a schematic view showing a schematic configuration of an electric power steering apparatus to which the helical belt of the present embodiment is applied. FIG. 2 is a side view of the reduction gear of the electric power steering apparatus. FIG. 3 is a partial perspective view of the helical tooth belt. FIG. 4 is a view of the helical tooth belt as viewed from the inner peripheral side. FIG. 5 is a cross-sectional view in the belt width direction of the helical tooth belt.

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

[Configuration of Electric Power Steering Device]
The electric power steering (EPS) device 1 is connected to the steering shaft 3 connected to the steering wheel 2, the intermediate shaft 4 connected to the steering shaft 3, and the intermediate shaft 4 and interlocked with the rotation of the steering wheel 2. And a steering mechanism 5 for steering the wheels 9.

The steering mechanism 5 includes a pinion shaft 6 connected to the intermediate shaft 4 and a rack shaft 7 meshing with the pinion shaft 6. The rack shaft 7 extends in the left-right direction of the vehicle. A rack 7 a that meshes with a pinion 6 a provided on the pinion shaft 6 is formed in the middle of the rack shaft 7 in the axial direction. The 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 the axial movement of the rack shaft 7. Thereby, the wheel 9 is steered.

The electric power steering apparatus 1 can obtain a steering assist force according to the steering torque applied to the steering wheel 2. As means for that purpose, the electric power steering apparatus 1 includes a torque sensor 13 for detecting a steering torque, a control device 14, an electric motor 15 (drive source) for steering assistance, and a driving force of the electric motor 15 as a steering mechanism 5. And a speed reduction gear 20 as a transmission gear.

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. When the steering wheel 2 is operated and a steering torque is input to the input shaft 10, the torsion bar 11 is torsionally deformed and the input shaft 10 and the output shaft 12 rotate relative to each other. 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 and the like detected by the torque sensor 13.

The reduction gear 20 has a drive pulley 21, a driven pulley 22, and a helical tooth belt 30 wound around the drive pulley 21 and the driven pulley 22. The driven pulley 22 has an outer diameter larger than that of the drive pulley 21. The drive pulley 21 is fixed to the rotation 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 drive pulley 21. A plurality of helical teeth 22 a are formed on the outer peripheral surface of the driven pulley 22. The rotational speed of the drive 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, a 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 drive pulley 21, the helical tooth belt 30 travels, and the driven pulley 22 and the pinion shaft 6 rotate. The rotational force of the electric motor 15 is decelerated by the reduction gear 20 and transmitted to the pinion shaft 6. Further, 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. Then, the rotation of the pinion shaft 6 is converted into the axial movement of the rack shaft 7, whereby the wheels 9 are steered. Thus, the steering of the driver is assisted by the rotation of the pinion shaft 6 being assisted by the electric motor 15.

The configuration of the electric power steering apparatus 1 to which the helical tooth belt 30 of the present invention can be applied is not limited to the configuration shown in FIG. For example, the driven pulley 22 of the reduction gear 20 may be fixed to the intermediate shaft 4 or the steering shaft 3. Also, for example, the driven pulley 22 of the reduction gear 20 may be coupled to the rack shaft 7 via the conversion mechanism. The conversion mechanism is, for example, a ball screw mechanism or a bearing screw mechanism, and may convert the rotational force of the driven pulley 22 into a force in the axial direction of the rack shaft 7 and transmit it to the rack shaft 7.

[Configuration of helical tooth belt]
As shown in FIG. 3, the helical belt 30 has a back 31 in which a core wire 33 is embedded in a spiral along the longitudinal direction of the belt and an inner peripheral surface of the back 31 (corresponding to one surface of the back 31) And a plurality of teeth 32 provided at predetermined intervals along the longitudinal direction of the belt. In the present embodiment, the plurality of teeth 32 are integrally formed on the inner peripheral surface of the back 31. Further, as shown in FIG. 4, the teeth 32 extend obliquely with respect to the belt width direction. Further, the inner circumferential surface of the helical tooth belt 30, that is, the surface of the tooth portion 32 and a part of the inner circumferential surface of the back portion 31 are covered with a tooth cloth 35. In the present embodiment, the outer peripheral surface of the back 31 (corresponding to the other surface of the back 31) is not covered with a cloth or the like, but may be covered with a back cloth.

The circumferential length of the helical belt 30 is, for example, 150 to 400 mm. In the present specification, the numerical range represented by “X to Y” means X or more and Y or less. The width W (see FIG. 4) of the helical belt 30 is, for example, 4 to 30 mm. The tooth pitch P (see FIG. 3) of the tooth portion 32 is 2 mm or more and less than 4 mm. When the tooth pitch P is 2 mm or more and less than 3 mm, the thickness tb (see FIG. 3) of the back 31 is 0.4 to 1.2 mm, preferably 0.6 mm or more and 0.9 mm or less. When 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. When the tooth pitch P is 2 mm or more and less than 3 mm, the tooth height hb (see 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 is there. When 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 to 2.3 mm, preferably 1.1 mm or more and 2.0 mm or less. The total thickness (maximum thickness) t (see FIG. 3) of the helical belt 30 is the sum of the thickness tb of the back portion 31 and the tooth height hb. The inclination angle θ (see FIG. 4) of the teeth 32 with respect to the belt width direction 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, and as a rubber component of this rubber composition, chloroprene rubber (CR), nitrile rubber, hydrogenated nitrile rubber (HNBR), ethylene-propylene copolymer (EPM) And ethylene-propylene-diene terpolymer (EPDM), styrene-butadiene rubber, butyl rubber, chlorosulfonated polyethylene rubber and the like. Particularly preferred rubber components are ethylene-propylene-diene terpolymers (EPDM), and chloroprene rubber and hydrogenated nitrile rubber (HNBR) are also suitably used. In this embodiment, although the rubber composition which constitutes back part 31 and tooth part 32 is formed with the same rubber composition, it may be formed with different rubber compositions.

The rubber composition that constitutes the back 31 and the teeth 32 may contain various conventional additives (or compounding agents) as needed. As an additive, a vulcanizing agent or a crosslinking agent (for example, oximes (such as quinone dioxime), guanidines (such as diphenyl guanidine), metal oxides (such as magnesium oxide and zinc oxide)), a vulcanization assistant, and a vulcanizing agent Vulcanization accelerator, vulcanization retarder, reinforcing agent (carbon black, silicon oxide such as hydrous silica), metal oxide (eg 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 (oils such as paraffin oil, naphthenic oil etc.), processing agents or processing aids (stearic acid, stearin, etc) Acid metal salt, wax, paraffin etc., anti-aging agent (aromatic amine anti-aging agent, benzimidazole based aging) Etc. sealant), stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), lubricants, flame retardants, etc. can be exemplified antistatic agent. These additives can be used alone or in combination, and can be selected according to the type of rubber component, application, performance and the like.

[Heart]
The core wire 33 is spirally embedded in the back portion 31 at a predetermined interval (0.45 mm or more and 0.6 mm or less) in the belt width direction along the belt longitudinal direction. More specifically, as shown in FIG. 3 and FIG. 5, cords 33 spirally embedded

cords

33 and 33 from one end to the other end in the belt width direction of spine 31. Each core pitch SP which is the distance between the centers of may be arranged so as to have a constant value in the range of 0.45 mm or more and 0.6 mm or less. In this specification, as shown in FIG. 5, the apparent number in a cross sectional view of the cords arranged at a predetermined cord pitch SP in the belt width direction is treated as "the number of cords". . That is, the number of spirals of the core wire 33 embedded in a spiral shape is taken as the “number of core wires”.

Here, it is desirable to count only the number (effective number) having an influence on the strength (elastic modulus) of the belt, as the "number of core wires". Therefore, the core wire 33 which is disposed at one end and the other end of the spine 31 of the helical belt 30 and is not cut in a circular cross-sectional view is not included in the effective number and is not cut in a cross sectional view It is desirable to count the core wire 33 as an effective number.
However, in fact, since the core wire 33 is embedded in a spiral shape, the arrangement of the core wire 33 differs depending on the portion where the cross section is collected among the endless helical tooth belts 30, which is cut. Since the influence of the non-circular cross section view 33 on the strength (elastic modulus) of the belt can not be ignored, practically, each core pitch SP is constant in the range of 0.45 mm or more and 0.6 mm or less In the case of the value of, the value obtained by dividing the belt width by the core wire pitch SP (a constant value in the range of 0.45 mm to 0.6 mm) and rounding off the decimal point value is roughly calculated. It is regarded as "the number of cores" (the number of effective lines). 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” (the number of effective wires) is regarded as 44. If the belt width is 25 mm and the core pitch SP is 0.52 mm, the calculated value is 48.07, and the “number of cores” (the number of effective cores) is considered to be 48. Further, if the belt width is 25 mm and the core pitch SP is 0.60 mm, the calculated value is 41.67, and the “number of core wires” (the number of effective wires) is regarded as 41.

Moreover, the core wire 33 is comprised by the twist cord formed by twisting a plurality of strands. One strand may be formed by bundling filaments (long fibers) and aligning them. The diameter of the core wire 33 is 0.2 to 0.6 mm. There are no particular limitations on the thickness of the filaments that form the twist cord, the number of converged filaments, the number of strands, and the twist configuration such as how to twist. The material of the filament is high strength glass fiber or carbon fiber. Both high strength glass fibers and carbon fibers have high strength and low elongation, and are suitable as a material of the core wire 33, but high strength glass fibers are more preferable from the viewpoint of low cost.

As high-strength glass fibers, for example, those having a tensile strength of 300 kg / cm ² or more, particularly glass fibers having a composition shown in the following Table 1 having more Si components than alkali-free glass fibers (E glass fibers) are suitably used. it can. The composition of E glass fiber is also described in Table 1 below for comparison. As such high-strength glass fibers, K glass fiber, U glass fiber (both manufactured by Nippon Glass Fiber Co., Ltd.), T glass fiber (manufactured by Nitto Boseki Co., Ltd.), R glass fiber (manufactured by VETROTEX), S glass fiber, S glass fiber -2 Glass fiber, ZENTRON glass fiber (all manufactured by Owens Corning Fiberglass) and the like.

Examples of the carbon fiber include pitch-based carbon fiber, polyacrylonitrile (PAN) -based carbon fiber, phenol resin-based carbon fiber, cellulose-based carbon fiber, polyvinyl alcohol-based carbon fiber and the like. As a commercial item of carbon fiber, for example, Toray Industries, Inc. "Toreca (registered trademark)", Toho Tenax Corporation "Tenax (registered trademark)", Mitsubishi Chemical Corporation "Dialed (registered trademark)" Can be used. These carbon fibers can be used alone or in combination of two or more. Among these carbon fibers, pitch-based carbon fibers and PAN-based carbon fibers are preferable, and PAN-based carbon fibers are particularly preferable.

The twist cords used as the core wire 33 may be subjected to an adhesion treatment in order to improve the adhesion to the back 31. As the adhesion treatment, for example, a method is employed in which a twist cord is dipped in a resorcinol-formalin-latex treatment solution (RFL treatment solution) and then dried by heating to form an adhesion layer uniformly on the surface. The RFL treatment solution is a mixture of an initial condensation product of resorcin and formalin in a latex, and as the latex used here, chloroprene, styrene butadiene vinylpyridine terpolymer (VP latex), hydrogenation A nitrile, NBR, etc. are mentioned. In addition, as a bonding process, after pre-processing with an epoxy or an isocyanate compound, there also exists a method etc. which process with a RFL process liquid.

Tooth cloth
The tooth cloth 35 is preferably made of a woven fabric in which warp yarns and weft yarns are longitudinally and transversely crossed according to a predetermined rule. The weave of the woven fabric may be twill weave, satin weave, or the like. The form of warp yarn and weft yarn is any of multifilament yarns in which filaments (long fibers) are aligned and twisted, monofilament yarn which is one long fiber, and spun yarn (spun yarn) in which short fibers are twisted together. May be When the warp or weft is a multifilament yarn or a spun yarn, it may be a mixed twist yarn or mixed yarn using a plurality of types of fibers. The weft yarn preferably includes an elastic yarn having stretchability. As the elastic yarn, for example, a material having stretchability such as spandex made of polyurethane, or a processed yarn obtained by stretching (for example, wooly processing, crimping and the like) of a fiber is used. Normally, elastic yarns are not used for warp yarns. Therefore, weaving is easy. As the tooth cloth 35, it is preferable to arrange the warp of the woven fabric in the belt width direction and the weft so as to extend in the belt longitudinal direction. Thereby, the stretchability of the tooth cloth 35 in the belt longitudinal direction can be secured. The tooth cloth 35 may be arranged so that the weft of the woven fabric extends in the belt width direction and the warp extends in the belt longitudinal direction. In this case, an elastic yarn having stretchability may be used as a warp. As a material of the fiber which comprises the tooth cloth 35, nylon, an aramid, polyester, polybenzoxazole, cotton etc. can use either or these combination.

The woven fabric used as the tooth cloth 35 may be subjected to an adhesion treatment in order to improve the adhesion to the back 31 and the teeth 32. As a bonding treatment, a method is generally used in which a woven fabric is dipped in resorcinol-formalin-latex (RFL solution) and then dried by heating to form a bonding layer uniformly on the surface. However, without being limited to this, after the pretreatment with an epoxy or isocyanate compound, the rubber composition is dissolved in an organic solvent such as methyl ethyl ketone, toluene, xylene, etc. besides the method of treating the woven fabric with an RFL solution. It is also possible to employ a method of preparing a rubber paste, and subjecting the woven fabric to an immersion treatment to impregnate and adhere the rubber composition. These methods may be performed alone or in combination, and the order of treatment and the number of treatments are not particularly limited.

[Back cloth]
In the present embodiment, the outer peripheral surface of the back 31 (corresponding to the other surface of the back 31) is not covered by a cloth or the like, but may be covered by a back cloth 36. When covering the outer peripheral surface of the back 31 with the back fabric 36, the back fabric 36 is a knitted fabric knitted with knitting yarn, or a woven fabric in which warp and weft yarns are intertwined longitudinally and laterally according to a certain rule It is preferred to be configured.

A knitted fabric is a fabric having a structure in which one or more yarns form a mesh (loop), and the next yarn is hooked on the loop to continuously form a new loop. That is, in a knitted fabric, it is formed by making a loop without crossing yarns in a straight line. When a knitted fabric is used as the back fabric 36, the knitted fabric (or knitting of the knitted fabric) may be either weft knitting (or knitted fabric knitted by weft knitting) or warp knitting (or knitted fabric knit by warp knitting) It may be The shape of the knitted fabric is not limited to a flat shape, a cylindrical shape (round knitting), and the like, and either the front or back stitch of the knitted fabric may be the adhesion surface of the belt body. Examples of the weft knitting (or weft knitting) include plain knitting (tendon knitting), rubber knitting, deer knitting, smooth knitting, jacquard knitting and the like. Moreover, as a warp knitting (or knitting structure of warp knitting), a single denby, a single cord, a tricot, a half tricot etc. are mentioned, for example.

When a woven fabric is used as the back fabric 36, the weave of the woven fabric may be any of plain weave, twill weave, satin weave, and the like. From the viewpoint of securing the bendability of the helical belt 30, in order to make it easy to bend in the longitudinal direction of the belt, it is preferable to make the weave configuration or the knitting configuration easy to stretch in the longitudinal direction of the belt. Therefore, it is preferable to use a woven fabric containing elastic yarn having stretchability as the weft, and arrange the warp of the woven fabric to extend in the belt width direction and the weft to extend in the belt longitudinal direction. In the form of warp yarns and weft yarns of knitted fabrics or woven fabrics, multifilament yarns in which filaments (long fibers) are aligned and twisted, single filament monofilament yarn, and short fibers are twisted It may be any of the spun yarns (spun yarns). When the warp or weft is a multifilament yarn or a spun yarn, it may be a mixed twist yarn or mixed yarn using a plurality of types of fibers. As a material of the fiber which comprises the back fabric 36, any one of nylon, an aramid, polyester etc., or these combination is employable. In this case, the back portion 31 is further reinforced to increase the rigidity of the helical tooth belt 30.

The woven or knitted fabric used as the back fabric 36 may be subjected to an adhesion treatment to enhance the adhesion to the back 31. As the adhesion treatment, as in the case of the tooth cloth 35, it is preferable to immerse the cloth in resorcinol-formalin-latex (RFL solution) and then heat and dry to form an adhesion layer uniformly on the surface. However, the rubber composition is dissolved in an organic solvent such as methyl ethyl ketone, toluene, xylene, etc., in addition to a method of treating the cloth with an RFL solution after pretreatment with an epoxy or isocyanate compound without being limited thereto. A method of impregnating and adhering the rubber composition by dipping the cloth in the rubber paste may be employed. These methods may be performed alone or in combination, and the order of treatment and the number of treatments are not particularly limited. In the case where the back cloth 36 is a knitted cloth, the unvulcanized rubber sheet wound on the knitted cloth is impregnated in the knitted cloth in the heat and pressure step in the method of manufacturing the helical tooth belt 30 described later. Therefore, it is not necessary to carry out the adhesion process.

Belt elastic modulus of helical tooth belt
The elastic modulus of the belt in the longitudinal direction of the helical belt 30 is preferably 0.96 MPa or more per 1 mm of the 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 having a width of 25 mm, it is preferably 24 MPa or more, and more preferably in the range of 24 MPa to 35 MPa. When the helical tooth belt 30 wound between the pulleys is made to travel by making the belt elastic modulus of the helical tooth belt 30 be 0.96 MPa or more per 1 mm of belt width, the vibration of the helical tooth belt 30 is The rigidity of the helical tooth belt can be secured such that sufficient quietness can be obtained by suppression.

[Method of manufacturing helical tooth belt]
The helical belt 30 is manufactured, for example, in the following procedure.
First, a woven fabric which has been subjected to adhesion processing for forming the tooth cloth 35 is wound around a cylindrical mold (not shown) having a plurality of grooves corresponding to the plurality of teeth 32 of the helical tooth belt 30. Subsequently, the twisted cords constituting the core wire 33 are helically spun on the outer circumferential surface of the wound woven fabric. Furthermore, an unvulcanized rubber sheet for forming the back portion 31 and the tooth portion 32 is wound around the outer periphery side to form an unvulcanized belt molded body.

When the back cloth 36 is covered, an unvulcanized rubber sheet for forming the back 31 and the teeth 32 is wound, and then a knitted cloth or a woven cloth forming the back cloth 36 is wound. In the case of using a woven fabric as the back cloth 36, the woven fabric is subjected to an adhesion treatment before being wound. On the other hand, in the case of using a knitted fabric as the back fabric 36, the bonding process may not be performed.

Next, in a state where the unvulcanized belt molded body is disposed on the outer periphery of the cylindrical mold, a rubber jacket that is a vapor blocking material is further covered on the outer side thereof. Subsequently, the jacketed belt molded body and the cylindrical mold are housed inside the vulcanized can. Then, the belt molded body is heated and pressurized inside the vulcanized can 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 belts 30 are obtained by cutting the demolded sleeve-like molded body into a predetermined width.

According to the helical tooth belt 30, the surface of the back portion 31 on the side of the tooth portion 32 is reinforced by the tooth cloth 35, so that the rigidity is enhanced. Moreover, the core wire 33 embedded in the back portion 31 is a twisted cord containing high strength glass fiber or carbon fiber which is a high strength (high elastic modulus) fiber material, and the diameter of the twisted cord is 0.2 mm or more It is 0.6 mm or less. Therefore, the rigidity of the back 31 can be further enhanced by the core wire 33 while securing the bendability of the back 31.

Thus, even if the helical tooth belt 30 is used for the reduction gear 20 driven by high load or high speed rotation by increasing the rigidity of the back portion 31, the tooth portion 32 of the drive pulley 21 or the driven pulley 22 Vibration (chord vibration) around the center line 33 of the helical tooth belt 30 which occurs when meshing with the tooth portion can be suppressed. Thereby, the noise generated by the vibration can be reduced.

The cords 33 embedded in the back 31 are arranged such that each core pitch SP between the cores is in the range of 0.45 mm or more and 0.6 mm or less. Thereby, the rigidity of the helical belt 30 can be further enhanced without further increasing the thickness of the back portion 31 or increasing the diameter of the core wire 33 (without sacrificing flexibility). .

Moreover, when 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. When the tooth pitch P is 3 mm or more and less than 4 mm, the thickness of the back 31 is 0.6 mm or more and 1.8 mm or less. The thickness of these is, for example, about the same as the thickness of the back of the conventional helical tooth belt used for the reduction gear 20 of the electric power steering apparatus 1 for automobiles. The helical belt 30 of the present invention can increase the rigidity of the back 31 without increasing the thickness of the back 31. Therefore, vibration and noise can be further suppressed while securing sufficient bending fatigue resistance.

Further, by using the helical belt 30 for the reduction gear 20 of the electric power steering apparatus 1 for an automobile, in which the outer diameter of the driven pulley 22 is larger than the outer diameter of the drive pulley 21, noise and vibration are sufficiently made. It can be reduced.

As mentioned above, although the preferred embodiment of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims.

Next, helical tooth belts according to Examples 1 to 17 and Comparative Examples 1 to 6 were manufactured, and measurement of a belt elastic modulus, a sound pressure measurement test, and a cold resistance test described later were performed.

As cords for use in the helical tooth belts of Examples 1 to 17 and Comparative Examples 1 to 6, twist cords of A1 to A4 having the configurations shown in Table 2 below were prepared.

The twist cord of A1 was created in the following procedure. The glass fiber filaments of the designation KCG150 described in JIS R 3413 (2012) were bundled and aligned to form three strands. The three strands are immersed in an RFL solution (18-23 ° C.) having a composition shown in Table 3 below for 3 seconds and then dried by heating at 200-280 ° C. for 3 minutes to uniformly adhere to the surface A layer was formed. After this adhesion treatment, the three strands were pretwisted with 12 twists / 10 cm, no overtwisting was given, and a twist cord having a diameter of 0.35 mm was prepared by single twisting. The twist cords of A2 and A3 were prepared in the same manner as A1, except that the glass fibers were changed to UCG150 and ECG150. The twist cord of A4 is prepared in the same procedure as the core wire of A1 to A3 except that the used strand is one strand obtained by bundling and aligning carbon fiber filaments (3K), and the diameter is single-twisted. Is a 0.53 mm twisted cord.

(Elastic modulus of core wire)
Here, the method of measuring the elastic modulus (tensile modulus) of the core wire (longitudinal direction) shown in Table 2 will be described. Attach a chuck to the lower fixed part and the upper load cell connection part of Autograph ("AGS-J10kN" manufactured by Shimadzu Corporation) and fix the core wire. Next, the upper chuck was raised and stressed (about 10 N) to the extent that the core did not loosen. With the upper chuck position in this state as the initial position, the upper chuck was raised at a speed of 250 mm / min, and immediately after the stress of the core wire reached 200 N, the upper chuck was lowered and returned to the initial position. The slope (average slope) of the straight line in the region (100 to 200 N) having a relatively linear relationship in the stress-strain curve measured at this time was calculated as the tensile modulus of elasticity of the core.

The tooth cloth used for the helical tooth belts of Examples 1 to 17 and Comparative Examples 1 to 6 was one type. As the tooth cloth, twill woven fabric was used, and the warp yarn of the woven fabric was disposed in the belt width direction and the weft yarn was extended in the belt longitudinal direction. As the weft of the woven fabric, a multifilament yarn of fineness of 155 dtex of 66 nylon and a multifilament yarn of fineness of 122 dtex of spandex (polyurethane elastic fiber) were used. The warp of the woven fabric was a 66 nylon multifilament yarn having a fineness of 155 dtex. In addition, dtex (decitex) is what expressed the mass of the thread of 10000 meters in a gram unit.

The woven fabric used for tooth cloth is dipped in RFL solution (18-23 ° C) shown in Table 10 for 10 seconds and then dried by heating at 150-170 ° C for 3 minutes to uniformly adhere the adhesive layer on the surface. Were treated to form an adhesive.

An unvulcanized rubber sheet having a composition C1 shown in Table 4 below was prepared as an unvulcanized rubber sheet for forming the spine and the tooth portion of the helical tooth belts of Examples 1 to 17 and Comparative Examples 1 to 6.

* 1 "EPT" manufactured by Mitsui Chemicals, Inc.
※ 2 Nocchi MB manufactured by Ouchi Shinko Chemical Co., Ltd.
* 3 "N-Cyclohexyl-2 benzothiazole sulfenamide" manufactured by Ouchi Shinko Chemical Co., Ltd.
※ 4 "Seast 3" manufactured by Tokai Carbon Co., Ltd.
※ 5 “Zinc oxide 3” manufactured by Shodo Chemical Industry Co., Ltd.

Using the unvulcanized rubber sheet of twist cord (core) A1 to A4, tooth cloth and composition C1, the procedure of Examples 1 to 17 and Comparative Examples 1 to 6 is carried out according to the procedure described in the above embodiment. I made a tooth belt. The vulcanization was carried out at 161 ° C. for 25 minutes. The structures of the helical tooth belts of Examples 1 to 17 and Comparative Examples 1 to 6 are shown in Tables 5 to 8 below. The belt widths of the helical belts of Examples 1 to 17 and Comparative Examples 1 to 6 were all 25 mm, and the inclination angles of the tooth portions with respect to the belt width direction were all 5 °.

(Measurement of belt elastic modulus)
The belt elastic modulus (tensile elastic modulus) was measured for the helical tooth belt (belt longitudinal direction) of Examples 1 to 17 and Comparative Examples 1 to 6. The method of measuring the belt elastic modulus will be described. A pair of pulleys (30 teeth outer diameter 18.6 mm) were attached to the lower fixed part and upper load cell connection part of Autograph ("AGS-J10kN" manufactured by Shimadzu Corporation), and the helical tooth belt was hooked on the pulleys . The upper pulley was then raised and stressed (about 10 N) to the extent that the helical belt did not loosen. Taking the position of the upper pulley in this state as the initial position, raise the upper pulley at a speed of 50 mm / min. Immediately after the stress of the helical tooth belt reaches 500 N, lower the upper pulley and return it to the initial position. The The slope (average slope) of the straight line in the region (100 to 500 N) having a relatively linear relationship in the stress-strain curve measured at this time was calculated as the tensile modulus of elasticity of the belt. And when the belt elastic modulus is 24 MPa or more (0.96 MPa or more per 1 mm of belt width), it was evaluated that the rigidity of the helical tooth belt is high.

(Sound pressure measurement test)
In addition, sound pressure measurement tests were conducted on the helical tooth belts of Examples 1 to 17 and Comparative Examples 1 to 6 to evaluate noise during running of the belts. A two-axis running test machine was used for the test. Like the reduction gear shown in FIG. 2, this two-axis running test machine is configured to have a drive pulley 21 and a driven pulley 22 larger in diameter than the drive pulley 21. As the drive pulley 21, a pulley having 40 teeth was used, and for the driven pulley 22, a pulley having 107 teeth was used. The helical belt 30 is wound around two pulleys, the distance between the shafts is adjusted so that the belt tension is 90 N, a load of 5 Nm is applied to the driven pulley 22, and the driving pulley 21 has a rotational speed of 1200 rpm. The helical tooth belt 30 was run by rotating. The ambient temperature was 23 ° C. Then, the sound pressure (noise level) was measured with the sound collection microphone M of the sound level meter. In addition, in order to demonstrate the position of the sound collection microphone M, the sound collection microphone M was displayed on the deceleration apparatus shown in FIG. Specifically, the sound collection microphone M is a straight line A which passes through the center position S of the drive pulley 21 and is perpendicular to a straight line T passing the center position S of the drive pulley 21 and the center position K of the driven pulley 22. Are parallelly moved in the direction of the driven pulley 22 by 25 mm, and are disposed at a position spaced 30 mm vertically outward from the outer peripheral surface of the helical tooth belt 30 from the portion B in contact with the outer peripheral surface of the helical tooth belt 30 . Tables 5 to 8 show the measurement results measured by the sound collection microphone M. When the sound pressure was 63 dBA or less, it was evaluated as acceptable as a noise level that causes no problem in the helical tooth belt.

(Cold resistance test)
Moreover, the test of cold resistance (low temperature durability) was implemented using the 2-axis driving test machine of the same layout as the said sound pressure measurement test. The driving pulley 21 was rotated at a rotational speed of 2000 rpm with no load and an atmospheric temperature of -40.degree. After running for 6 seconds, an operation of stopping for 10 minutes was performed for 1000 cycles as one cycle. Then, at the 500th and 1000th cycles, it was visually confirmed whether or not the surface of the back of the helical tooth belt had a crack.
The confirmation results are shown in Tables 5 to 8 using ranks A, B, and C. Rank A is a case where no crack has occurred even at the 1000th cycle. Rank B is a case where the crack did not occur at the 500th cycle and the crack occurred at the 1000th cycle. Rank C is a case where a crack has occurred at the 500th cycle. As an indicator of cold resistance (low temperature durability), when using a belt in a cold area where the lowest temperature reaches -40 ° C, the crack life tends to reach crack life in the order of ranks B and C in comparison with rank A belt It is positioned as a grade that is less durable. From the viewpoint of appropriate use in cold regions where the lowest temperature reaches -40.degree. C., belts of ranks A and B are preferred, and belts of rank A are particularly preferably used.

(Verification when core pitch is changed with 2 mm tooth pitch)
In Examples 1 to 5, 7 and 8 shown in Table 5, the rigidity (belt elastic modulus: 24 MPa or more) of the belt is sufficient to suppress vibration and obtain sufficient quietness (sound pressure is 63 dBA or less). It was secured. In Comparative Example 1, in the case of a glass fiber having a dense core pitch but a small modulus of elasticity of the core wire, the belt elastic modulus enough to suppress the vibration can not be secured (less than 24 MPa). It was not enough. In addition, Comparative Example 2 is a high strength glass fiber having a large elastic modulus of core, but the core pitch is large (0.64 mm), so it is not possible to secure a belt elastic modulus that can suppress vibration (less than 24 MPa ), The effect of reducing the sound pressure was not enough. Therefore, it can be judged that the lower limit of the elastic modulus (tensile elastic modulus in the longitudinal direction) of the belt having an effect of suppressing the vibration is 24 MPa (0.96 MPa per 1 mm of the belt width).

Further, Comparative Example 1 is an example using the same configuration as that of Example 2 except for the material of the core wire, and using the core wire A3 of E glass fiber which is not high strength glass fiber, and the sound pressure is 64 dBA. Exceeded.
The comparative example 2 is an example which has the same configuration as the comparative example 1 except for the material of the core and the core pitch SP (0.64 mm) is larger than that of the comparative example 1. In this case, the sound pressure was larger than the determination criterion (pass at 63 dBA or less).

In all of the examples 1 to 5, 7 and 8, the sound pressure was 63 dBA or less, which is the criterion.
The second, third, and seventh embodiments have the same configuration as the first embodiment, and the core pitch is smaller (0.52 mm) than the first embodiment (0.56 mm), and the seventh embodiment is the sixth embodiment. Example 3 is an example (0.60 mm) which is smaller than Example 2 (0.48 mm), and Example 3 is larger than Example 1, and Example 7 has the lowest sound among Examples 7, 2, 1 and 3. Pressure (58 dBA).

Example 4 differs from Example 2 only in the type of fibers constituting the cord (U glass), and Example 5 differs from Example 1 only in the type of fibers constituting the cord ( Carbon) Example 8 differs from Example 3 only in the type of fibers constituting the cord (carbon). In Examples 4, 5 and 8, no significant difference was found in the sound pressure.

From the above, it has been confirmed that noise can be suppressed in the core wire pitch range of 0.45 to 0.6 mm in the case of a tooth pitch of 2 mm.

(Verification when changing back thickness with 2 mm tooth pitch)
As shown in Table 6, in Example 9 (0.45 mm) in which the back thickness is smaller than Example 1 (back thickness 0.85 mm), since the rigidity of the helical tooth belt is small, the sound pressure is the acceptance criterion. It has increased to 63dBA. On the other hand, in Example 10 (1.15 mm) in which the back thickness was large, the sound pressure was reduced and the quietness was improved, but the cold resistance was lowered (judgment B). Furthermore, in Comparative Example 3 (1.30 mm) having a large back thickness, the sound pressure was further reduced, but the cold resistance was further reduced (judgment C). Overall, the back thickness (0.85 mm) of the well-balanced Example 1 was the best.

In addition, a fall of cold resistance is that it becomes easy to produce malfunctions, such as a crack, when it uses (bending driving | running | working) in a low temperature environment. When using helical belts in automotive applications, cold resistance for use in cold regions (eg -40 ° C) is also important. According to the above Examples 1, 9, 10 and Comparative Example 3, the sound pressure increases and the quietness decreases as the back thickness decreases, but on the other hand, the stiffness of the helical tooth belt decreases (flexibility improves). The cold resistance is improved, while the sound pressure is reduced and the quietness is improved if the back thickness is increased, but the cold resistance is lowered due to the increase in rigidity (flexibility) of the helical tooth belt. Therefore, the upper limit and the lower limit of the thickness of the back become important, and according to Examples 1, 9, 10 and Comparative Example 3, when the tooth pitch is 2 mm or more and less than 3 mm, the thickness of the back is 0.4 to 1 2 mm is preferable, and 0.6 mm to 0.9 mm is considered to be preferable.

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

Further, Comparative Example 4 is an example using the core A3 of E glass fiber which is not the high strength glass fiber in the same configuration as Example 6 except for the material of the core, and the sound pressure is determined to be 66 dBA Exceeded.
The comparative example 5 is an example which has the same configuration as the comparative example 4 except for the material of the core and the core pitch SP (0.64 mm) is larger than that of the comparative example 4. In this case, the sound pressure was larger than the determination criterion (pass at 63 dBA or less).

In all of the sixth and eleventh to fifteenth embodiments, the sound pressure was 63 dBA or less, which is the criterion.
The sixth, thirteenth, and eleventh embodiments have the same configuration as the twelfth embodiment, and the core pitch is smaller (0.52 mm) than the twelfth embodiment (0.56 mm), and the eleventh embodiment is the sixth embodiment. Example 13 is an example (0.60 mm) larger than Example 12 (0.40 mm), and Example 11 has the lowest sound pressure (Example 11 and Example 11 to 13). It became 60dBA).

Example 14 differs from Example 12 only in the type of fibers constituting the core wire (carbon), and Example 15 differs from Example 13 only in the type of fibers constituting the core line (carbon ). In Examples 14 and 15, a large difference was not found in the sound pressure, but the sound pressure was as low as that in Example 11.

From the above, it has been confirmed that noise can be suppressed in the core wire pitch range of 0.45 to 0.6 mm when the tooth pitch is 3 mm.

(Verification when changing back thickness with 3 mm tooth pitch)
As shown in Table 8, in Example 16 (0.65 mm) in which the thickness of the back is smaller than Example 6 (back thickness 1.00 mm), the rigidity of the helical tooth belt is small and therefore the sound pressure is the acceptance criterion. It has increased to 63dBA. On the other hand, in Example 17 (1.75 mm) in which the back thickness was large, the sound pressure was reduced and the quietness was improved, but the cold resistance was lowered (judgment B). Furthermore, in Comparative Example 6 (1.90 mm) having a large back thickness, the sound pressure was further reduced, but the cold resistance was further reduced (judgment C). Overall, the back thickness (1.00 mm) of the well-balanced Example 6 was the best.

Therefore, according to Examples 6, 16, 17 and Comparative Example 6, when the tooth pitch is 3 mm or more and less than 4 mm, the thickness of the back is preferably 0.6 to 1.8 mm, 0.8 mm to 1.2 mm. Is considered preferable.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made within the scope of the claims. It is. The present application is based on Japanese Patent Application No. 2017-135270 filed on Jul. 11, 2017, Japanese Patent Application No. 2018-073854 filed on Apr. 6, 2018, and Japanese Patent Application filed on Jun. 27, 2018. No. 2018-121700, the contents of which are incorporated herein by reference.

1 Electric Power Steering Device 15 Electric Motor (Drive Source)
20 Reduction gear (belt transmission)
21 drive pulley 22 driven pulley 30 helical tooth belt 31 back 32 tooth portion 33 center line 35 tooth cloth P tooth pitch SP center line pitch

Claims

With the back where the heart cord is buried,
A helical tooth belt having a plurality of tooth portions provided on one surface of said back along the longitudinal direction of the belt at predetermined intervals and each inclined with respect to the belt width direction,
The surface of the teeth and a portion of the one surface of the back are made of a tooth cloth,
The tooth pitch of the plurality of teeth is 2 mm or more and less than 4 mm,
When the tooth pitch of the plurality of teeth is 2 mm or more and less than 3 mm, the thickness of the back is 0.4 mm or more and 1.2 mm or less,
When 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 core wire is a twisted cord containing high-strength glass fiber or carbon fiber and having a diameter of 0.2 mm or more and 0.6 mm or less, and each core wire pitch between the core wire and the core wire is 0.45 mm. A helical tooth belt characterized in that it is arranged to be in the range of not less than 0.6 mm.
The core wires embedded in the back have a constant core pitch in the range of 0.45 mm to 0.6 mm from one end to the other end in the belt width direction of the helical belt. The helical tooth belt according to claim 1, characterized in that it is arranged to be a value.
When the tooth pitch of the plurality of tooth portions is 2 mm or more and less than 3 mm, the tooth height of the tooth portions is 0.7 mm or more and 2.0 mm or less,
The tooth height of the tooth portion is 1.0 mm or more and 2.3 mm or less when the tooth pitch of the plurality of tooth portions is 3 mm or more and less than 4 mm. Lotus tooth belt.
The helical tooth belt according to any one of claims 1 to 3, wherein the back portion contains a rubber component, and the rubber component contains an ethylene-propylene-diene terpolymer or a hydrogenated nitrile rubber.
The tooth cloth is made of a woven fabric including warps and wefts, and the warps or wefts are arranged to extend in the longitudinal direction of the belt, and the warps or wefts arranged to extend in the longitudinal direction of the belt are elastic. The helical tooth belt according to any one of claims 1 to 4, comprising an elastic yarn having
The fiber according to any one of claims 1 to 5, wherein the fiber constituting the tooth cloth comprises at least one fiber selected from the group consisting of nylon, aramid, polyester, polybenzoxazole, and cotton. Tooth belt.
The other surface of the back is made of a backing cloth,
The helical tooth belt according to any one of claims 1 to 6, wherein the fibers constituting the back fabric include at least one fiber selected from the group consisting of nylon, aramid and polyester.
The helical tooth belt according to any one of claims 1 to 7, wherein a belt elastic modulus of the helical tooth belt is 0.96 MPa or more per 1 mm of belt width.
A drive pulley rotationally driven by a drive source;
Driven pulley,
A helical transmission according to any one of the preceding claims, wherein the helical belt is wound around the drive pulley and the driven pulley.
The belt transmission according to claim 9, wherein a rotational speed of the drive pulley is 1000 rpm or more and 4000 rpm or less.
The belt transmission according to claim 9, wherein a load of the driven pulley is 0.5 kW or more and 3 kW or less.
The outer diameter of the driven pulley is larger than the outer diameter of the drive pulley,
The belt transmission according to any one of claims 9 to 11, wherein the belt transmission is a reduction gear of an electric power steering apparatus for a car.