JP2005265106A - Double cogged v-belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double cogged V-belt excellent in bending fatigue resistance not promoting fatigue of core wire of para-group aramid fiber. <P>SOLUTION: A double cogged V-belt B is provided with an endless core wire embedding part 10 including the para-group aramid fiber core wire 12 embedded to form a spiral of a predetermined pitch in a belt width direction, a lower cogged shaped part 20 including lower cogs 24 provided on an inner circumference side of the core wire embedding part 10 as one piece and formed along a belt longitudinal direction with a constant pitch, and a upper cogged shaped part 30 including upper cogs 24 provided on an outer circumference side of the core wire embedding part 10 as one piece and formed along the belt longitudinal direction with a constant pitch. Belt bending stiffness of the double cogged V-belt is 600-1,200 N/mm<SP>3</SP>and dynamic compression spring constant in a belt width direction is 15,000 N/mm or more. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes an endless core wire embedded portion having a core wire embedded so as to form a spiral having a predetermined pitch in the belt width direction, and an inner peripheral side of the core wire embedded portion, which is integrally provided along the belt longitudinal direction. A lower cog forming portion having a lower cog formed at a constant pitch, and an upper cog forming portion having an upper cog integrally formed on the outer peripheral side of the core wire embedded portion and formed at a constant pitch along the belt longitudinal direction To a double cogged V belt.

  Rubber transmission belts are used for transmission devices (automatic transmission devices) of motorcycles (scooters) and ATVs (All Terrain Vehicles). In recent years, while the capacity of the engine has increased, it has been required to make the transmission device compact, and therefore, this type of transmission belt is required to have a higher transmission capability. Specifically, for an engine whose displacement exceeds 400 cc, a transmission capacity of a level of 10000 N / m or more is required as an ST value described later.

  By the way, as a rubber transmission belt, a low-edge V-belt (a surface in contact with a pulley is made of rubber mixed with fibers (short fiber reinforced rubber)) is generally applied. The low edge V belt has a short fiber orientation direction of short fiber reinforced rubber (hereinafter referred to as “below”) that can withstand a lateral pressure acting on the belt even if an aspect ratio, which is a ratio of a belt width to a belt thickness, is large. The direction of cutting ”) is the belt width direction and the direction perpendicular to the cutting direction (hereinafter referred to as“ reverse direction ”) is the belt longitudinal direction, thereby increasing the elastic modulus in the belt width direction. Yes. In order to improve the transmission capability of the belt, it is known that the elastic modulus in the direction of the train should be increased. However, in general, increasing the elastic modulus in the direction of travel will also increase the elastic modulus in the reverse direction, which increases the bending rigidity of the belt and generates heat when the belt is run at high speed. Remarkably, this causes cracks in the belt and shortens the life of the belt. It is also possible to increase the amount of short fibers mixed with the rubber in order to increase the elastic modulus in the direction of machining. However, if this is done, the extensibility in the anti-direction direction is lowered and the belt is subjected to repeated bending strain. In this case, the bending resistance (hardness of cracking) will be lowered. In other words, it is desirable that the ratio of the elastic modulus in the line direction to the elastic modulus in the reverse direction is large, but there is a limit to this.

  Therefore, a cogged V belt (single cogged V belt) in which cogs are formed at an equal pitch in the belt longitudinal direction on the inner peripheral side of the belt is used as a means for reducing the bending rigidity of the belt and the bending strain received. The cogged V belt has low bending rigidity of the belt due to the formation of cogs, thereby suppressing self-heating of the belt and reducing the bending strain received by the belt, thereby suppressing the occurrence of cracks. As a result, it has high bending resistance.

  Furthermore, a double cogged V belt in which cogs are formed at an equal pitch in the longitudinal direction of the belt is also used on the outer peripheral side of the belt as an improvement in transmission capability without reducing the bending resistance of the belt. The double cogged V belt has upper and lower cogs on both the inside and outside of the belt, preventing buckling deformation due to the side pressure of the belt, thereby increasing the transmission capacity and lowering the bending rigidity of the belt. The bending resistance is maintained, and as a result, it has both high transmission ability and high bending resistance.

  In Patent Document 1, the distance from the cog bottom to the core wire on the side of the belt on the side of contact with the moving surface of the driving pulley is the distance from the cog bottom on the side of the belt on the side of contact with the fixed surface of the driving pulley. It is disclosed that the side area of the side surface of the belt that comes into contact with the moving surface of the driving pulley is increased by increasing the distance by 5% to 50% from the distance up to. According to this, it is described that both the ease of bending and the resistance to side pressure can be obtained, and the engine can be started up smoothly without causing overshoot or hunting.

In Patent Document 2, a compressed rubber layer is provided with a lower cog portion formed by alternately arranging a plurality of cogs and cogs in a constant pitch along the longitudinal direction of the belt, and the stretched rubber layer is provided along the longitudinal direction of the belt. It is a double cogged belt provided with an upper cog portion formed by arranging a number of cog mountains and cog valleys alternately at a constant pitch, the deepest part of the cog valley in the lower cog part and the deepest part of the cog valley in the upper cog part It is disclosed that the lower cog portion and the upper cog portion are formed so as to be inconsistent with each other in the belt thickness direction. And according to this, the belt thickness at the deepest part of the cog valley of the lower cog part and the cog valley of the upper cog part is not extremely reduced, and the curvature when bending is extremely increased. Since it is possible to prevent a large stress from acting on the cog valley in the lower cog part and the cog valley in the upper cog part, it is possible to prevent the occurrence of cracks at an early stage and maintain a long belt life. It is described.
JP 2001-99235 A JP 2002-31192 A

  In the transmission belt, since it is desired that the belt dimensional change is small, a core wire made of para-aramid fiber having a high elastic modulus and low heat shrinkage is often used. On the other hand, in the double cogged V-belt, as a means of improving the bending fatigue resistance, it is possible to reduce the belt bending rigidity and improve the flexibility by reducing the thickness between the cog bottom of the upper and lower cogs. Can do.

  However, in the double cogged V belt having a core made of para-aramid fiber, when the thickness between the cog bottoms of the upper cog and the lower cog is reduced, the belt is wound around the pulley in a state where the core is refracted into a polygonal shape. As a result, fatigue of the core wire is promoted, and there is a problem that the bending fatigue resistance of the belt is impaired.

  The present invention has been made in view of the above points, and the object of the present invention is to provide a double cogged V-belt that is excellent in bending fatigue resistance without promoting fatigue of a core wire made of para-aramid fiber. It is to provide.

The present invention provides an endless core wire embedded portion having a para-aramid fiber core wire embedded so as to form a spiral of a predetermined pitch in the belt width direction, and an inner peripheral side of the core wire embedded portion. A lower cog forming portion having a lower cog formed at a constant pitch along the belt longitudinal direction, and an upper portion integrally formed on the outer peripheral side of the core wire embedded portion and formed at a constant pitch along the belt longitudinal direction A double cogged V-belt having an upper cog forming portion having cogs,
The belt bending rigidity is 600 to 1200 N / mm ³ , and the dynamic compression spring constant in the belt width direction is 15000 N / mm or more.

The present invention also provides an endless core wire embedded portion having a core wire made of para-aramid fiber embedded so as to form a spiral having a predetermined pitch in the belt width direction, and an inner peripheral side of the core wire embedded portion. A lower cog forming portion having a lower cog formed integrally at a constant pitch along the belt longitudinal direction, and formed at a constant pitch along the belt longitudinal direction integrally provided on the outer peripheral side of the core wire embedded portion. A double cogged V belt provided with an upper cog forming portion having an upper cog,
The belt bending rigidity is 600 to 1200 N / mm ³ , and the static spring constant in the belt width direction is 4000 N / mm or more.

  According to the above configuration, as will be described later in the embodiment, the balance between the belt bending rigidity and the dynamic or static spring constant in the belt width direction is appropriate, so that the belt is polygonally wound around the pulley. Therefore, the fatigue of the core wire made of para-aramid fiber is not promoted, and the bending fatigue resistance is improved.

  The belt bending rigidity and the dynamic or static spring constant in the belt width direction are defined in the examples described later.

  In the present invention, the lower cog forming part is formed of a rubber composition in which 15 to 25 parts by mass are mixed and dispersed with respect to 100 parts by mass of the rubber component so that short fibers having a tensile modulus of 40 GPa or more are oriented in the belt width direction. It may be what has been done.

  In that case, in the present invention, the rubber composition forming the lower cog forming portion may be one in which the rubber component is mainly chloroprene rubber and the short fibers are para-aramid fibers.

  In the present invention, the arrangement pitch of the upper cogs may be shorter than the arrangement pitch of the lower cogs.

  In the present invention, the total belt thickness may be 13 mm or more.

  In the present invention, the ratio of the cog height of the lower cog to the cog height of the upper cog may be 1.7 or more.

  In the present invention, the ratio of the total belt thickness to the thickness between the bottom of the upper cog and the lower cog may be 2.5 or more.

  As described above, according to the present invention, fatigue of the core wire made of para-aramid fiber is not promoted, and good bending fatigue resistance can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 and 2 show a double cogged V-belt B according to an embodiment of the present invention. This double cogged V-belt B is used for shifting a two-wheeled vehicle.

  This double cogged V-belt B is a kind of V-belt having a total belt thickness T of 13 mm or more, and is an endless core wire embedded portion 10 and a lower portion integrally provided on the inner peripheral side of the core wire embedded portion 10. It comprises a cog forming portion 20 and an upper cog forming portion 30 provided integrally on the outer peripheral side of the core wire burying portion 10.

  The core wire embedded portion 10 includes a core wire embedded portion main body 11 formed of a rubber composition and a core wire 12 embedded therein so as to form a spiral having a predetermined pitch in the belt width direction. The rubber composition constituting the core wire embedded body is chloroprene rubber (CR), ethylene / propylene / diene / terpolymer rubber (EPDM), alkylated chlorosulfonated polyethylene rubber (ACSM), hydrogenated NBR (H-NBR). ), And chloroprene rubber is preferably used. The core wire 12 has a predetermined outer diameter d (for example, d = 0.8) obtained by dipping a para-aramid fiber having a thickness of 5000 to 10000 dtex and dipping in a resorcin / formalin / latex aqueous solution and then drying. ~ 1.5mm).

The lower cog forming part 20 includes a lower cog forming part main body 22 formed of a rubber composition mixed and dispersed so that the short fibers 21 are oriented in the belt width direction, and a canvas 23 covering the surface thereof. The thickness is 5.0 to 8.0 mm. The rubber components of the rubber composition forming the lower cog forming body 22 are chloroprene rubber (CR), ethylene / propylene / diene / terpolymer rubber (EPDM), alkylated chlorosulfonated polyethylene rubber (ACSM), hydrogenated NBR. (H-NBR) or the like, and chloroprene rubber is preferably used. The short fibers 21 are, for example, high-strength polyvinyl alcohol (PVA) fibers, para-aramid fibers, aromatic polyester fibers, heterocycle-containing aromatic fibers having a tensile modulus of 40 GPa or more, and 100 parts by mass of the rubber component. 15 to 25 parts by mass are mixed. Among these, para-aramid fibers (for example, DuPont brand names: Kevlar 29, Kevlar 119, Teijin brand name: Technora) have excellent cutting resistance when short fibers are kneaded into a rubber component ( From the viewpoint that the elastic modulus can be increased with a small amount). The canvas 23 is made of a nylon fiber, cotton, a mixed fiber thereof, a mixed fiber of cotton and polyester fiber, an woven fabric having extensibility made of aramid fiber, and the like and subjected to an adhesive treatment for drying after being immersed in rubber paste. Become. This canvas 23 suppresses the occurrence of cracks at the bottom of the lower cog 24, and when the belt is used as a clutch (for example, when the pulley is fully opened when the vehicle is stopped and the belt is slipped). Generation of adhesion is prevented. The lower cog forming portion 20 has lower cogs 24 arranged at a constant pitch P ₁ (for example, P ₁ = 6 mm) along the belt longitudinal direction, and in the belt width direction between the adjacent lower cogs 24. An extending groove 25 is formed. The outer profile of the lower cog 24 has a substantially sinusoidal waveform with a cog height D ₁ of 4 to 6 mm, and a radius R ₁ (for example, R ₁ = 2. 0 mm).

The upper cog forming part 30 is formed of a rubber composition in which the short fibers 31 are mixed and dispersed so as to be oriented in the belt width direction, and the thickness thereof is 1.5 to 3.0 mm. The rubber components of the rubber composition forming the upper cog forming portion 30 are chloroprene rubber (CR), ethylene / propylene / diene / terpolymer rubber (EPDM), alkylated chlorosulfonated polyethylene rubber (ACSM), hydrogenated NBR ( H-NBR), and chloroprene rubber is preferably used. The short fiber 31 is, for example, a high-strength polyvinyl alcohol (PVA) fiber, para-aramid fiber, aromatic polyester fiber, heterocycle-containing aromatic fiber or the like having a tensile modulus of 40 GPa or more, and 100 parts by mass of the rubber component. 15 to 25 parts by mass are mixed. Among these, para-aramid fibers (for example, DuPont brand names: Kevlar 29, Kevlar 119, Teijin brand name: Technora) have excellent cutting resistance when short fibers are kneaded into a rubber component ( From the viewpoint that the elastic modulus can be increased with a small amount). The upper cog forming portion 30 has upper cogs 34 disposed at a constant pitch P ₂ (for example, P ₂ = 6 mm) along the longitudinal direction of the belt, and between the adjacent upper cogs 34 in the belt width direction. An extending groove 35 is formed. The vertical cross-sectional outline of the upper cog 34 is formed in a substantially trapezoidal shape with a predetermined cog height D ₂ (for example, D ₂ = 2.2 mm), and the radius R ₂ (for example, the bottom of the groove 35 is concave outward) , R ₂ = 1.2 mm). Note that the upper cog forming portion 30 may be covered with a reinforcing cloth.

This double cogged V-belt B has the following shape parameters. First, the arrangement pitch P ₁ of the lower cogs 24 is shorter than the arrangement pitch P ₂ of the upper cogs 34. Further, the ratio D ₁ / D ₂ of the cog height D ₁ of the lower cog 24 to the cog height D ₂ of the upper cog 34 is 1.7 or more. Further, the distance between the bottom of the groove 25 of the lower cog forming part 20 and the bottom of the groove 35 of the upper cog forming part 30, that is, the thickness between the cog bottoms T _t (T _t is the groove of the lower cog forming part 20 25 is the sum of the distance T ₁ from the bottom of 25 to the center of the core 12 and the distance T ₂ from the bottom of the groove 35 of the upper cog forming portion 30 to the center of the core T) / T _t is 2.5 or more. These shape parameters are necessary conditions for the double cogged V-belt B to realize excellent lateral pressure resistance and bending resistance. Further, the ratio of the belt width W at the center position in the belt thickness direction of the core wire 12 to the belt thickness T is 1.5 to 4.0. If this ratio is smaller than 1.5, the aspect ratio is not established as a transmission belt. If this ratio is larger than 4.0, buckling deformation in the belt width direction due to lateral pressure becomes large, and the transmission capability becomes low.

The double cogged V belt B has the following mechanical characteristics. First, the belt bending rigidity is 600 to 1200 N / mm ³ . The dynamic compression spring constant in the belt width direction is 15000 N / mm or more. Furthermore, the static spring constant in the belt width direction is 4000 N / mm or more. By having these mechanical characteristics, the belt is not wound around the pulley in a polygonal manner, and therefore, fatigue of the core wire 12 made of para-aramid fiber is not promoted, and excellent bending fatigue resistance. Sex can be obtained.

(Containing rubber for belts)
Rubber blends for belts 1 to 7 were prepared. Each configuration is also shown in Table 1.

<Formulation 1>
Chloroprene rubber (CR), 48 parts by mass of carbon black, 5 parts by mass of magnesium oxide, 5 parts by mass of zinc oxide, and 2.5 parts by mass of anti-aging for 100 parts by mass of chloroprene rubber (CR) The agent, 9 parts by mass of processing aid and plasticizer were put into an internal mixer and kneaded, and then divided into pieces. Next, 3 parts by mass of a crosslinking accelerator and 20 parts by mass of 6,6-nylon short fibers having a fiber length of 3 mm are added to and kneaded with 100 parts by mass of chloroprene rubber (CR). A rubber composition was formed. Subsequently, this was rolled with a calender roll to a thickness of 1.0 mm, and the short fibers were oriented in the longitudinal direction. Subsequently, this was cut | judged for every predetermined length, and they were joined so that a short fiber might orientate in the width direction. This was designated as rubber composition 1.

<Formulation 2>
The same rubber composition as that of Compound 1 was used as Compound 2 except that meta-aramid short fibers (trade name: Conex, manufactured by Teijin Limited) having a fiber length of 3 mm were used instead of the 6,6-nylon short fibers.

<Formulation 3>
The same rubber composition as compounding 1 except that 10 mass parts of para-aramid short fibers having a fiber length of 3 mm (trade name: Technora manufactured by Teijin Ltd.) were used instead of 20 mass parts of 6,6-nylon short fibers. The product was designated Formulation 3.

<Formulation 4>
Compound 4 is the same rubber composition as Compound 3 except that the amount of para-aramid short fibers (trade name: Technora manufactured by Teijin Limited) is 15 parts by mass with respect to 100 parts by mass of chloroprene rubber (CR). did.

<Formulation 5>
Compound 5 is the same rubber composition as Compound 3 except that the amount of para-aramid short fibers (trade name: Technora manufactured by Teijin Ltd.) is 20 parts by mass with respect to 100 parts by mass of chloroprene rubber (CR). did.

<Formulation 6>
Compound 6 is the same rubber composition as Compound 3 except that the amount of para-aramid short fibers (trade name: Technora manufactured by Teijin Ltd.) is 25 parts by mass with respect to 100 parts by mass of chloroprene rubber (CR). did.

<Formulation 7>
The same rubber composition as compounding 3 was blended with 7 except that the mixed amount of para-aramid short fibers (trade name: Technora manufactured by Teijin Ltd.) was 28 parts by mass with respect to 100 parts by mass of chloroprene rubber (CR). did.

<Formulation 8>
Compound 8 is the same rubber composition as Compound 3 except that the amount of para-aramid short fibers (trade name: Technora manufactured by Teijin Ltd.) is 23 parts by mass with respect to 100 parts by mass of chloroprene rubber (CR). did.

(Belt cord)
Two para-aramid fibers (trade name: Technora made by Teijin Limited) with a thickness of 1650 dtex are collected and twisted with a twisting factor of 4.3, and three twisted twists are collected and opposite to the twisting direction. A core wire having a total thickness of 9900 dtex, which was twisted in the direction with a twist coefficient of 3.6, was prepared. The core wire had a tensile strength of 1300 N / bar. In addition, a twist coefficient is shown in the following relational expression.

(Canvas)
A stretchable nylon fiber canvas was prepared.

(Double cogged V belt for testing)
Test double cogged V belts for belts 1 to 10 were prepared. Each configuration is also shown in Table 2.

<Belt 1>
A sheet-like rubber composition of Formulation 1 jointed so that the short fibers are oriented in the width direction, a core wire and a stretchable nylon canvas are set in a cylindrical mold, and a cylindrical slab is then formed into a cylindrical mold. The belt 1 is a double cogged V-belt which is molded and vulcanized on the outer periphery, cut into a predetermined width, and then cut and polished so that the belt cross section has a wedge angle of 32 °. The belt 1 has a belt thickness T of 14.8 mm and a belt width W at the center in the belt width direction of the core wire of 23.0 mm. The ratio of the belt width W is 1.55. The lower cog arrangement pitch P ₁ is 11.0 mm and the upper cog arrangement pitch P ₂ is 9.5 mm. Therefore, the ratio P of the lower cog arrangement pitch P _{1 to} the upper cog arrangement pitch P _{2 is} P. ₁ / P ₂ is 1.16. The radius R ₁ of the cross-sectional shape of the groove bottom of the lower cog forming portion is 1.5 mm, and the radius R ₂ of the cross-sectional shape of the groove bottom of the upper cog forming portion is 1.5 mm. The lower cog height D ₁ is 7.1 mm and the upper cog height D ₂ is 3.6 mm, so the ratio D of the lower cog height D _{1 to} the upper cog height D _{2 is} D. ₁ / D ₂ is 1.97. The distance T ₁ from the bottom of the lower cog forming portion groove to the center of the core is 2.9 mm, and the distance T ₂ from the bottom of the upper cog forming portion to the center of the core is 1.2 mm. the distance T _t between the bottom of the groove of the bottom and upper cog forming part of the groove of the lower cog forming part at T ₁ + T ₂ 4.1 mm, also with respect to the cog Sokokan thickness T _t of the belt total thickness T The ratio T / T _t is 3.61.

<Belt 2>
A double cogged V belt having the same configuration as that of belt 1 except that the rubber composition of compounding 2 was used was used as belt 2.

<Belt 3>
A belt 3 is a double cogged V belt having the same structure as the belt 1 except that the rubber composition of compound 3 is used.

<Belt 4>
A sheet-like rubber composition of compounding 4 jointed so that the short fibers are oriented in the width direction, a core wire and a stretchable nylon canvas are set in a cylindrical mold, and a cylindrical slab is then formed into a cylindrical mold. The belt 4 is a double cogged V belt which is molded and vulcanized on the outer periphery, cut into a predetermined width, and then cut and polished so that the belt cross section has a wedge angle of 32 °. The belt 4 has a belt thickness T of 14.8 mm and a belt width W at the center in the belt width direction of the core wire of 23.0 mm. The ratio of the belt width W is 1.55. The lower cog arrangement pitch P ₁ is 11.0 mm and the upper cog arrangement pitch P ₂ is 9.5 mm. Therefore, the ratio P of the lower cog arrangement pitch P _{1 to} the upper cog arrangement pitch P _{2 is} P. ₁ / P ₂ is 1.16. The radius R ₁ of the cross-sectional shape of the groove bottom of the lower cog forming portion is 1.5 mm, and the radius R ₂ of the cross-sectional shape of the groove bottom of the upper cog forming portion is 1.5 mm. The lower cog height D ₁ is 5.5 mm and the upper cog height D ₂ is 2.3 mm, so the ratio D of the lower cog height D _{1 to} the upper cog height D _{2 is} D. ₁ / D ₂ is 2.39. The distance T ₁ from the bottom of the groove of the lower cog forming part to the center of the core is 4.5 mm, and the distance T ₂ from the bottom of the groove of the upper cog forming part to the center of the core is 2.5 mm. The distance T _t between the bottom of the lower cog forming part and the bottom of the upper cog forming part is 8.0 mm as T ₁ + T ₂ , and the belt total thickness T with respect to the cog bottom thickness T _t The ratio T / T _t is 1.85.

<Belt 5>
A double cogged V belt having the same configuration as that of the belt 1 except that the rubber composition of compound 4 was used was designated as a belt 5.

<Belt 6>
A double cogged V-belt having the same configuration as the belt 1 was used as the belt 6 except that the rubber composition of Formulation 5 was used.

<Belt 7>
A double cogged V-belt having the same configuration as that of the belt 1 except that the rubber composition of Formulation 6 was used was designated as the belt 7.

<Belt 8>
A double cogged V-belt having the same configuration as that of the belt 1 except that a rubber composition 7 was used was designated as a belt 8.

<Belt 9>
A sheet-like rubber composition of compounding 5 jointed so that the short fibers are oriented in the width direction, a core wire and a stretchable nylon canvas are set in a cylindrical mold, and a cylindrical slab is made of the cylindrical mold The belt 9 was a double-cogged V-belt that was molded and vulcanized on the outer periphery, cut into a predetermined width, and then cut and polished so that the belt cross-section had a wedge angle of 32 °. The belt 9 has a belt thickness T of 14.8 mm and a belt width W at the center of the core wire in the belt width direction of 23.0 mm. The ratio of the belt width W is 1.55. The lower cog arrangement pitch P ₁ is 11.0 mm and the upper cog arrangement pitch P ₂ is 9.5 mm. Therefore, the ratio P of the lower cog arrangement pitch P _{1 to} the upper cog arrangement pitch P _{2 is} P. ₁ / P ₂ is 1.16. The radius R ₁ of the cross-sectional shape of the groove bottom of the lower cog forming portion is 1.5 mm, and the radius R ₂ of the cross-sectional shape of the groove bottom of the upper cog forming portion is 1.5 mm. The lower cog height D ₁ is 7.1 mm and the upper cog height D ₂ is 3.6 mm, so the ratio D of the lower cog height D _{1 to} the upper cog height D _{2 is} D. ₁ / D ₂ is 1.97. The distance T ₁ from the bottom of the groove of the lower cog forming part to the center of the core is 1.3 mm, and the distance T ₂ from the bottom of the groove of the upper cog forming part to the center of the core is 0.7 mm. the distance T _t between the bottom of the groove of the bottom and upper cog forming part of the groove of the lower cog forming part at T ₁ + T ₂ 2.0 mm, also with respect to the cog Sokokan thickness T _t of the belt total thickness T The ratio T / T _t is 5.92.

<Belt 10>
A sheet-like rubber composition of Compound 6 jointed so that the short fibers are oriented in the width direction, a core wire and a stretchable nylon canvas are set in a cylindrical mold, and a cylindrical slab is then formed into a cylindrical mold. The belt 10 is a double cogged V-belt which is formed and vulcanized on the outer periphery, cut into a predetermined width, and then cut and polished so that the belt cross section has a wedge angle of 32 °. The belt 10 has a belt thickness T of 13.0 mm and a belt width W at the center of the core wire in the belt width direction of 23.0 mm. The ratio of the belt width W is 1.92. The lower cog arrangement pitch P ₁ is 9.5 mm, and the upper cog arrangement pitch P ₂ is 6.3 mm. Therefore, the ratio P of the lower cog arrangement pitch P _{1 to} the upper cog arrangement pitch P _{2 is} P. ₁ / P ₂ is 1.51. The radius R ₁ of the cross-sectional shape of the groove bottom of the lower cog forming portion is 1.5 mm, and the radius R ₂ of the cross-sectional shape of the groove bottom of the upper cog forming portion is 1.0 mm. The lower cog height D ₁ is 5.5 mm and the upper cog height D ₂ is 2.8 mm, so the ratio D of the lower cog height D _{1 to} the upper cog height D _{2 is} D. ₁ / D ₂ is 1.96. The distance T ₁ from the bottom of the lower cog forming portion groove to the center of the core is 2.5 mm, and the distance T ₂ from the bottom of the upper cog forming portion to the center of the core is 1.2 mm. The distance T _t between the bottom of the lower cog forming portion and the bottom of the upper cog forming portion is 3.7 mm as T ₁ + T ₂ , and the belt total thickness T is _equal to the cog bottom thickness T _t . The ratio T / T _t is 3.51.

<Belt 11>
A sheet-shaped rubber composition of compounding 8 jointed so that the short fibers are oriented in the width direction, a core wire and a stretchable nylon canvas are set in a cylindrical mold, and a cylindrical slab is then formed from the cylindrical mold. The belt 11 was a double-cogged V-belt that was molded and vulcanized on the outer periphery, cut to a predetermined width, and then cut and polished so that the belt cross-section had a wedge angle of 32 °. The belt 11 has a belt thickness T of 14.6 mm and a belt width W at the center of the core wire in the belt width direction of 23.0 mm. The ratio of the belt width W is 1.58. The lower cog arrangement pitch P ₁ is 11.0 mm and the upper cog arrangement pitch P ₂ is 9.5 mm. Therefore, the ratio P of the lower cog arrangement pitch P _{1 to} the upper cog arrangement pitch P _{2 is} P. ₁ / P ₂ is 1.16. The radius R ₁ of the cross-sectional shape of the groove bottom of the lower cog forming portion is 1.5 mm, and the radius R ₂ of the cross-sectional shape of the groove bottom of the upper cog forming portion is 1.5 mm. The lower cog height D ₁ is 7.1 mm and the upper cog height D ₂ is 3.6 mm, so the ratio D of the lower cog height D _{1 to} the upper cog height D _{2 is} D. ₁ / D ₂ is 1.97. The distance T ₁ from the bottom of the lower cog forming portion groove to the center of the core is 2.7 mm, and the distance T ₂ from the bottom of the upper cog forming portion to the center of the core is 1.2 mm. The distance T _t between the bottom of the lower cog forming part and the bottom of the upper cog forming part is 3.9 mm in T ₁ + T ₂ , and the belt total thickness T is _equal to the cog bottom thickness T _t . The ratio T / T _t is 3.74.

(Test method)
<Viscoelastic properties of rubber>
About each sheet-like rubber composition in which the short fibers of Formulations 1 to 8 were oriented, a sheet-like rubber having a thickness of 1.0 mm was vulcanized.

About each sheet-like rubber of compounding 1-8, cut out the strip-shaped test piece of width 5mm so that a line direction may become a longitudinal direction, and set it to a viscoelasticity spectrometer (RSAII by Rheometrics), and a test The dynamic elastic modulus was measured by applying a static load of 29.4 N / cm ^{2 to} the test piece at a temperature of 25 ° C. and applying a dynamic strain of ± 0.1%.

Similarly, about each sheet-like rubber of compounding 1-8, cut out the strip-shaped test piece of width 5mm so that the reverse direction may become a longitudinal direction, set it to a viscoelastic spectrometer, and it is 29 on a test piece. The dynamic elastic modulus was measured by applying a load of 4 N / cm ² and applying a dynamic strain of ± 1.0%.

<Tensile properties of rubber>
About each sheet-like rubber of compounding 1-8, No. 3 dumbbell of JIS K6251 was punched out so that the reverse direction was a longitudinal direction, a tensile test was performed according to JIS K6251, and elongation at break was measured.

<Belt bending stiffness>
FIG. 3 shows a belt bending stiffness measuring device 40. The belt bending stiffness measuring device 40 includes an upper plate 41 that is movable up and down, and a lower plate 42 that is connected to a load cell, and upper cogs abut on the upper and lower plates 41 and 42, respectively. Thus, the load when the belt B is sandwiched between them and the upper plate 41 is moved downward is detected by the load cell. Then, the bending rigidity is calculated by the following relational expression. The winding diameter of the belt B is a distance between the center line center on the upper plate 41 side and the center line center on the lower plate 42 side.

  About each double cog V belt of belts 1-11, bending rigidity was calculated according to the above-mentioned method.

<Dynamic compression spring constant in the belt width direction>
The dynamic compression spring constant in the belt width direction was measured using a servo pulser manufactured by Shimadzu Corporation. FIG. 4A shows the measuring device 50. This measuring device 50 includes an upper plate 51 connected to a load cell and a lower plate 52 that can be vibrated up and down, and is long and has a width of 10 mm as shown in FIG. A test piece S having a thickness of 40 mm is sandwiched between the upper and lower plates 51 and 52, and the lower plate is repeatedly moved up and down at 50 Hz after the lower plate is raised and an initial load is applied at an ambient temperature of 23 ± 2 ° C. It is moved to give a dynamic load. To set the load, obtain the cross-sectional area of the belt cut at right angles, and make the initial load 1.56 N / mm ² and the dynamic load ± 0.31 N / mm ² so that the load per unit area is the same. Set to. The dynamic compression spring constant (K value) in the belt width direction is obtained from the following relationship.

  The relationship of the following equation (1) is established among the load f applied to the test piece S, the deformation amount X, and the deformation speed V.

f = K · X + C · V (1)
Here, K is a dynamic compression spring constant in the belt width direction, and C is a damping coefficient. If the load is a sine wave,
F · sin (ωt + φ) = K · X · sin (ωt) + C · V · cos (ωt)
F · sin (ωt + φ) = Fx · sin (ωt) + Fv · cos (ωt)
Where Fx = F · cos (φ)... F displacement component Fv = F · sin (φ)... F velocity component K = F · cos (φ) / X
C = F · sin (φ) / (ωX)
X: displacement amplitude, F: load amplitude, φ: phase difference, ω: angular velocity (ω / 2π is a frequency)
The dynamic compression spring constant (K value) in the belt width direction was determined for each of the double cogged V belts of belts 1 to 11 according to the above method.

<Static compression spring constant in the belt width direction>
The static compression spring constant in the belt width direction was measured using an autograph manufactured by Shimadzu Corporation. A test piece similar to that for obtaining the dynamic compression spring constant in the belt width direction was cut out from the belt and compressed in the belt width direction at a speed of 1 mm / min to obtain a stress-strain curve (SS curve). The slope of the curve at the deformation amount of 0.25 to 0.30 mm (strain 0.025 to 0.030) was defined as a static compression spring constant in the belt width direction.

  The static compression spring constant (S value) in the belt width direction was determined for each of the double cogged V belts of belts 1 to 11 according to the above method.

<Belt transmission capacity and transmission efficiency>
FIG. 5 shows a belt running test machine 60. The belt running test machine 60 is a two-axis type composed of a driving pulley 61 and a driven pulley 62 arranged in the same plane. The drive pulley 61 is attached to one end of the drive shaft 63. Further, a pulley 64 is attached to the other end of the drive shaft 63, and a belt 68 is wound around the pulley 67 attached to the pulley 67 attached to the motor shaft 66 of the drive motor 65. The power of the drive motor 65 is transmitted to the drive shaft 63 via the belt 68, so that the drive pulley 61 rotates. The drive shaft 63 is provided with a torque meter 69. The driven pulley 62 is attached to one end of the driven shaft 70. A pulley 71 is attached to the other end of the driven shaft 70, and a belt 75 is wound around the pulley 71 attached to the pulley 73 attached to the shaft 73 of the load machine 72. The load of the loader 72 is transmitted to the driven shaft 70 via the belt 75. The driven shaft 70 is provided with a torque meter 76. A drive system such as the drive motor 65 is provided on a moving table 77, and by moving the moving table 77, a predetermined load can be applied to the belt B as a test piece. It comes to detect. The V-groove angle of the drive pulley 61 and the driven pulley 62 are both 30 °.

  For each of the double cogged V belts 1 to 11, as shown in FIG. 6, the drive pulley 61 has a pulley diameter of 68 mm and the driven pulley 62 has a pulley diameter of 158 mm. An axial load of 588 to 2452N was applied to the pulley 62, and the drive pulley 61 was rotated at 2000 rpm. At that time, the number of revolutions of the driving pulley 61 and the driven pulley 62 is measured, and the apparent slip ratio when the transmission torque is changed (including the slip ratio due to the belt deformation to the inside of the pulley and the belt extension). Stuff). And the transmission torque and the theoretical drive pulley diameter (the pulley diameter at the position having the same pulley width as the belt width assuming that the belt width (belt pitch width) at the center position of the core does not change), From the layout, the ST value defined by the following relational expression was obtained as a belt transmission capability index. The transmission capacity, that is, the ST value was assumed to be when the slip rate was 4%.

<High load durability of belt>
For each of the double cogged V belts 1 to 11, the driving pulley 61 has a pulley diameter of 68 mm and the driven pulley 62 has a pulley diameter of 158 mm as shown in FIG. Then, the belt B was wound around them, an axial load of 1176 N was applied to the driven pulley 62, the drive pulley 61 was rotated at 6400 rpm, and the belt B was run until it was damaged.

<High speed durability of belt>
With respect to each of the double cogged V belts of belts 1 to 11, the driving pulley 61 has a pulley diameter of 128 mm and the driven pulley 62 has a pulley diameter of 105 mm as shown in FIG. Then, the belt B was wound around them, and an axial load of 981 N was applied to the driven pulley 62, the drive pulley 61 was rotated at 6000 rpm, and the belt B was run until it was damaged. Also, the belt temperature during belt running was measured.

(Test results)
Table 3 shows the test results of each rubber composition of Formulations 1-8, and Table 4 shows the test results of belts 1-11.

  FIG. 9 shows the relationship between the belt bending stiffness and the dynamic compression spring constant, and FIG. 10 shows the relationship between the belt bending stiffness and the static compression spring constant.

  From these results, it can be seen that Examples 1 to 3 have low transmission capability. This is presumably because the elastic modulus of the rubber composition constituting the belt is low.

  It turns out that Examples 5-7 and Examples 10 and 11 are excellent in transmission capability and constant-speed durability, and also excellent in high-speed durability (bending fatigue resistance) compared with others. This is considered to be because the balance between the elastic modulus and the shape (cog bottom thickness) of the rubber composition constituting the belt is good. In particular, Example 10 has a total belt thickness of 13 mm, low heat generation during high speed running, and excellent high speed durability.

  In Example 9, the running life is short although the thickness between the cog bottoms is thinner than the others and the bending rigidity is lowered. This is presumably because the belt was wound around the pulley in a state where the core wire was refracted into a polygonal shape, and fatigue of the core wire was promoted.

From the above results, the belt bending rigidity is 600 to 1200 N / mm ³ and the dynamic compression spring constant in the belt width direction is 15000 N / mm or more, or the belt bending rigidity is 600 to 1200 N / mm ³ . When the static spring constant in the belt width direction is 4000 N / mm or more, it can be said that excellent bending fatigue resistance can be obtained without promoting fatigue of the core wire made of para-aramid fiber.

  From the viewpoint of durability, the dynamic compression spring constant in the belt width direction is preferably 20000 N / mm or less, and the static spring constant in the belt width direction is preferably 6000 N / mm or less.

  As described above, the present invention is useful as a rubber transmission belt for a two-wheeled vehicle or an ATV transmission device.

It is a perspective view of the double cogged V belt concerning the embodiment of the present invention. It is the longitudinal cross-sectional view and cross-sectional view of the double cogged V belt which concern on embodiment of this invention. It is a figure which shows the structure of a belt bending rigidity measuring apparatus. It is a figure which shows the structure of a belt width direction dynamic compression spring constant measuring apparatus. It is a figure which shows the structure of a belt running test machine. FIG. 6 is a layout diagram of a running test for obtaining the transmission capability and transmission efficiency of a belt. It is a layout diagram of a running test for testing the high load durability of the belt. FIG. 3 is a layout diagram of a running test for testing high-speed durability of a belt. It is a graph which shows the relationship between belt bending rigidity and a dynamic compression spring constant. It is a graph which shows the relationship between belt bending rigidity and a static compression spring constant.

Explanation of symbols

B Double cogged V belt 10 Core wire burying part 12 Core wire 20 Lower cog forming part 21, 31 Short fiber 24 Lower cog 30 Upper cog forming part 34 Upper cog

Claims (8)

An endless core wire embedded portion having a core wire made of para-aramid fiber embedded so as to form a spiral of a predetermined pitch in the belt width direction, and a belt longitudinally provided integrally on the inner peripheral side of the core wire embedded portion A lower cog forming portion having a lower cog formed at a constant pitch along the direction, and an upper cog formed integrally at the outer peripheral side of the core wire embedded portion and formed at a constant pitch along the belt longitudinal direction A double cogged V belt having a cog forming portion,
A double cogged V-belt having a belt bending rigidity of 600 to 1200 N / mm ³ and a dynamic compression spring constant in the belt width direction of 15000 N / mm or more. An endless core wire embedded portion having a core wire made of para-aramid fiber embedded so as to form a spiral of a predetermined pitch in the belt width direction, and a belt longitudinally provided integrally on the inner peripheral side of the core wire embedded portion A lower cog forming portion having a lower cog formed at a constant pitch along the direction, and an upper cog formed integrally at the outer peripheral side of the core wire embedded portion and formed at a constant pitch along the belt longitudinal direction A double cogged V belt having a cog forming portion,
A double cogged V-belt having a belt bending rigidity of 600 to 1200 N / mm ³ and a static spring constant in the belt width direction of 4000 N / mm or more. In the double cogged V belt according to claim 1 or 2,
The lower cog forming part is formed of a rubber composition in which 15 to 25 parts by mass of the rubber component is mixed and dispersed with respect to 100 parts by mass of the rubber component so that short fibers having a tensile modulus of 40 GPa or more are oriented in the belt width direction. Double cogged V belt. In the double cogged V belt according to claim 3,
The rubber composition forming the lower cog forming portion is a double cogged V-belt in which the rubber component is mainly chloroprene rubber and the short fibers are para-aramid fibers. In the double cogged V belt according to claim 1 or 2,
A double cogged V-belt in which the arrangement pitch of the upper cogs is shorter than the arrangement pitch of the lower cogs. In the double cogged V belt according to claim 1 or 2,
Double cogged V-belt with a total belt thickness of 13 mm or more. In the double cogged V belt according to claim 1 or 2,
A double cogged V-belt in which the ratio of the cog height of the lower cog to the cog height of the upper cog is 1.7 or more. In the double cogged V belt according to claim 1 or 2,
A double cogged V-belt in which the ratio of the total belt thickness to the thickness between the cog bottom of the upper cog and the lower cog is 2.5 or more.

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