JP3559278B1 - Transmission belt - Google Patents

Abstract

To suppress abnormal noise generated from a V-ribbed belt.
A V-ribbed belt has a rib rubber layer. The rib rubber layer 11 has a plurality of V ribs 15 extending in the longitudinal direction. Innumerable short fibers 20 are evenly mixed into the rib rubber layer 11. A part of the short fiber 20 protrudes from the side surface 16 of the V-rib 15. The tensile strength of the short fibers 20 is 8.6 cN / dtex to 16.2 cN / dtex. The rubber hardness of the rib rubber layer 11 is 84 to 91.
[Selection diagram] Fig. 1

Description

  The present invention relates to, for example, a power transmission belt for driving an automobile, and more specifically, to a V-ribbed belt for driving an accessory of an automobile engine.

  Conventionally, a V-ribbed belt is used to transmit the driving force of an auxiliary device of an automobile engine. The V-ribbed belt transmits power by frictional transmission between a rib and a pulley. However, when the rubber of the rib and the pulley come into direct contact with each other when the rib and the pulley perform frictional transmission, an abnormal noise may be generated because the friction coefficient of the rib with respect to the pulley becomes too high.

Therefore, for example, a configuration is known in which short fibers mixed into ribs of a V-ribbed belt are projected on the surface of the ribs (for example, Patent Document 1). According to this configuration, at the time of contact between the belt and the pulley, the short fiber contacts the pulley in addition to the rubber of the rib, so that the friction coefficient can be reduced.
Japanese Patent Publication No. 6-21607

  However, the short fibers protruding from the surface of the ribs are worn or pulled out due to the contact between the belt and the pulley, so that the amount of short fibers protruding from the rib surface decreases with the use time of the belt. That is, in a V-ribbed belt in which short fibers protrude from the rib surface, the friction coefficient increases as the belt usage time becomes longer, and abnormal noise is likely to occur.

  Generally, short fibers are projected from the surface of the ribs by grinding when forming the ribs of the V-ribbed belt. However, many of the short fibers are scraped or pulled out with the grinding of the rubber, and the short fibers protruding from the surface of the rib are limited.

  Therefore, the present invention has been made to solve the above problems, and has an object to make it easy for short fibers to protrude from a rib surface of a belt in a manufacturing process, and to prevent the protruding short fibers from being worn or pulled out. And

  The power transmission belt according to the present invention includes a lower rubber layer that comes into contact with the pulley when being wound around the pulley, and high-strength short fibers mixed into the lower rubber layer, and a part of the high-strength short fibers protrudes. Wherein the high-strength short fiber has a tensile strength of 8.6 cN / dtex to 16.2 cN / dtex, and the lower rubber layer has a hardness of 84 to 91. By setting the tensile strength of the high-strength short fiber to 8.6 cN / dtex to 16.2 cN / dtex with respect to the hardness of the lower rubber layer (84 to 91), the protruding high-strength short fiber is used during belt production. Also, when used, it is hard to be worn and hard to be pulled out.

  More preferably, the hardness of the lower rubber layer is from 86 to 91. The fineness of the high-strength short fibers is, for example, from 3.3 dtex to 6.7 dtex. The fiber length of the high strength short fiber is, for example, 1 mm to 3 mm.

  When the lower rubber layer is formed by mixing high-strength short fibers into the compounded rubber, the hardness of the compounded rubber is 81 or less, preferably 78 to 81. This is because, when a rubber compound having a rubber hardness higher than 81 when vulcanized is used, when a desired amount of high-strength short fibers is compounded, the rubber hardness of the lower rubber layer becomes too hard.

  The high-strength short fibers are, for example, polyamide short fibers. The Mooney viscosity of the rubber component of the lower rubber layer is, for example, 30 or less at 125 ° C. If the Mooney viscosity of the rubber component is too high, the rubber hardness of the lower rubber layer becomes too hard when a desired amount of high-strength short fibers is blended.

  The high-strength short fibers are preferably RFL-treated. Thereby, the high-strength short fibers have an increased adhesiveness to the rubber of the lower rubber layer, and the short fibers are more difficult to be pulled out during belt production and use.

  The high-strength short fibers are preferably blended in an amount of 10 to 25 parts by weight based on 100 parts by weight of the rubber component of the lower rubber layer. The transmission belt is, for example, a V-ribbed belt.

  The method for manufacturing a power transmission belt according to the present invention includes a lower rubber layer that comes into contact with the pulley when being wound around the pulley, and high-strength short fibers mixed into the lower rubber layer, and a part of the high-strength short fibers. Is a method of manufacturing a power transmission belt, which comprises projecting a part of high-strength short fibers by grinding a lower rubber layer, wherein the tensile strength of the high-strength short fibers is 8.6 cN / dtex. -16.2 cN / dtex, and the hardness of the lower rubber layer is 84-91.

  The particle size of the abrasive grains of the grinding stone for grinding the lower rubber layer is, for example, 80 mesh to 170 mesh.

  According to the present invention, the protruding high-strength short fibers are likely to remain in the lower rubber layer during belt running, thereby suppressing an increase in the coefficient of friction even after using the power transmission belt for a long time. Therefore, generation of abnormal noise can be prevented.

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

  FIG. 1 is a sectional view of a V-ribbed belt 10 according to an embodiment of the present invention. The V-ribbed belt 10 includes a rib rubber layer 11 (lower rubber layer) on the bottom side and an adhesive rubber layer 12 on the back side. A core 13 extending in the longitudinal direction of the belt is embedded in the adhesive rubber layer 12. A canvas 14 is attached to the back of the adhesive rubber layer 12.

  A plurality of V-ribs 15 extending in the longitudinal direction of the belt are provided on the rib rubber layer 11 in the width direction of the belt. The side surface 16 and the bottom surface 17 of the V-rib 15 serve as contact surfaces with the pulley when the belt 10 is wound around the pulley. The rib rubber layer 11 and the adhesive rubber layer 12 are made of, for example, EPDM (ethylene-propylene-diene copolymer), chloroprene rubber, EPM (ethylene-propylene copolymer), H-NBR (hydrogenated nitrile rubber), or the like as a rubber component. It is formed.

  Innumerable short fibers 20 are almost uniformly mixed in the rib rubber layer 11, and the short fibers 20 are oriented in the width direction of the belt. The short fibers 20 are blended in an amount of 10 to 25 parts by weight, preferably 15 to 20 parts by weight, based on 100 parts by weight of the rubber component of the rib rubber layer 11. The countless short fibers 20 partially project from the side surface 16 of the rib rubber layer 11. That is, a part of the short fiber 20 protrudes from the contact surface with the pulley, and when the V-ribbed belt 10 is wound around the pulley, the short fiber 20 contacts the pulley together with the rubber constituting the rib rubber layer 11. Therefore, the coefficient of friction between V-ribbed belt 10 and the pulley is lower than when only rubber contacts the pulley.

  The short fibers 20 are high strength short fibers, for example, polyamide short fibers, and the polyamide is, for example, nylon 66. The high-strength short fibers are, for example, short fibers for tire cords. The fineness of the short fibers is preferably, for example, from 3.3 dtex to 6.7 dtex. The fiber length of the short fibers is, for example, 1 mm to 3 mm, and preferably 1 mm to 2 mm. Further, the tensile strength of the high-strength short fiber is from 8.6 cN / dtex to 16.2 cN / dtex (8 g / d (denier) to 15 g / d), and particularly preferably about 11 cN / dtex (10 g / d). .

  The short fibers 20 are preferably RFL-treated. The latex used in the RFL (resorcin-formaldehyde-latex) treatment is 7: 3 of VP latex (vinyl pyridine-styrene-butadiene copolymer rubber latex) and SBR latex (styrene-butadiene copolymer rubber latex). The weight ratio of RF (resorcinol: formaldehyde) / L (latex) is, for example, 10/100 to 30/100.

  The rubber component (eg, EPDM) of the compounded rubber that forms the rib rubber layer 11 has a Mooney viscosity (125 ° C.) of 30 or less, preferably 25 or less, and more preferably 24 to 25.

  The rubber hardness of the rib rubber layer 12 mixed with the short fibers 20 is 84 to 91, preferably 86 to 91, and more preferably about 90. On the other hand, the rubber hardness when the compounded rubber constituting the rib rubber layer 12 is vulcanized, that is, the rubber hardness of the rib rubber layer when short fibers are not mixed is preferably 81 or less, more preferably 78 or less. Or 81. That is, the rubber hardness of the rib rubber layer 11 has increased from 81 or less to 84 to 91 due to the mixing of the short fibers 20.

  Here, if the protruding short fibers 20 are relatively soft relative to the hardness of the belt, that is, if the tensile strength is too low, the short fibers 20 are likely to be worn due to contact with the pulley during belt running. If the tensile strength is too high relative to the belt hardness, the force from the pulley tends to act on the short fibers 20 during running, and the protruding short fibers 20 are easily pulled out.

  That is, the short fibers 20 preferably have a certain range of tensile strength relative to the belt hardness so that they are not worn or pulled out. Here, when the rubber hardness of the rib rubber layer 12 is 84 to 91, as described above, the tensile strength of the short fiber is preferably 8.6 cN / dtex to 16.2 cN / dtex.

  If the rubber hardness of the rib rubber layer 11 is higher than 91, the flexibility of the belt decreases, and the life of the belt is significantly reduced. Further, when the rubber hardness of the rib rubber layer 11 is lower than 84, if short fibers having an appropriate tensile strength are mixed with the rubber hardness, the strength of the belt will be lowered. Therefore, the rubber hardness of the belt is preferably 84 to 91.

  Next, a method for manufacturing the V-ribbed belt 10 will be described with reference to FIGS. As shown in FIG. 2, in the present manufacturing method, a cylindrical drum 21 is prepared, and a canvas 14 ', an adhesive rubber sheet 12', a core wire 13 ', and a rib rubber sheet 11' are sequentially wound around the cylindrical drum 21. In the rib rubber sheet 11 ', the short fibers 20 are oriented perpendicular to the circumferential direction of the drum.

  Here, the rib rubber sheet 11 ′ is composed of 100 parts by weight of a rubber component (for example, EPDM), a known vulcanizing agent, a vulcanization aid, an antioxidant, carbon black and the like are mixed in a predetermined part by weight. 10 to 25 parts by weight, preferably 15 to 20 parts by weight, is blended with 100 parts by weight of the rubber component.

  The short fibers 20 are formed by immersing the long fibers in an RFL solution before being mixed with the rib rubber sheet 11 ', drying the long fibers, and then cutting the long fibers into a predetermined length.

  The cylindrical drum 21 around which the rubber sheet or the like is wound is put into a vulcanizing pot (not shown), and is heated under pressure at a predetermined temperature and pressure. The core wire 13 ′ is pushed inward by the rib rubber sheet 11 ′ by pressing and heating, and is embedded in the adhesive rubber sheet 12 ′. The adhesive rubber sheet 12 'and the rib rubber sheet 11' are vulcanized by heating under pressure, and the canvas 14 'and the rib rubber sheet 11' are joined by the adhesive rubber sheet 12 '. Thereby, the canvas 14 ', the adhesive rubber sheet 12', the core wire 13 ', and the rib rubber sheet 11' are integrally formed, and a flat belt-shaped vulcanized sleeve is obtained. The vulcanization sleeve is cut to a predetermined width according to the belt width. The adhesive rubber sheet 12 'and the rib rubber sheet 11' correspond to the adhesive rubber layer 12 and the rib rubber layer 11 in the V-ribbed belt 10, respectively.

  FIG. 3 shows a V-ribbed belt polishing apparatus 29. The polishing device 29 has a driving pulley 30, a driven pulley 31, and a grinding wheel 32. A vulcanization sleeve 10 ′ cut to a predetermined width is wound around the driving pulley 30 and the driven pulley 31, and a grinding wheel 32 is provided at a position facing the driving pulley 30. On the peripheral surface of the grinding wheel 32, diamond abrasive grains are provided as a grindstone. The particle size of the diamond abrasive is from 80 mesh to 170 mesh, preferably from 120 mesh to 140 mesh. When the particle size is 120 mesh or more, the side surface 16 of the rib rubber layer 11 is formed smoothly.

  The grinding wheel 32 is rotated clockwise at 1000 rpm to 1800 rpm. On the other hand, the driving pulley 30 is rotated clockwise at 2 rpm, and the vulcanization sleeve 10 'and the driven pulley 31 are also rotated. Here, the driving and driven pulleys 30 and 31 are approached to the grinding wheel 32 while being rotated, whereby the planar rib rubber layer of the vulcanized sleeve 10 ′ is ground by diamond abrasive grains, and V The rib 15 (see FIG. 1) is formed, and the V-ribbed belt 10 (see FIG. 1) is obtained.

  When the rib rubber layer is ground, the short fibers 20 are ground at the same time. However, since the short fibers 20 have relatively high strength compared to the rubber forming the rib rubber layer, the rubber is easily ground, while the short fibers 20 are hard to be ground. Therefore, countless short fibers 20 protrude from the side surface 16 of the rib rubber layer 11 when grinding is completed (see FIG. 1).

  Here, as described above, when the tensile strength of the short fibers is low, the short fibers 20 are easily worn, so that the amount of the short fibers 20 projecting to the surface is reduced. Further, even when the strength of the short fibers is high, the short fibers 20 are easily pulled out, and the amount of the short fibers 20 projecting to the surface is reduced. Therefore, also in the manufacturing process, when the hardness of the rib rubber layer 11 is 84 to 91, the tensile strength of the short fiber is preferably 8.6 cN / dtex to 16.2 cN / dtex.

  Hereinafter, the present invention will be described in more detail with reference to Examples. In Examples and Comparative Examples, the following compounded rubber A and compounded rubber B were used.

  The compounded rubber A is a well-known carbon black, an organic metal salt, an antioxidant, an anti-scorch agent, paraffin oil, vulcanized with respect to 100 parts by weight of EPDM (rubber component) having a Mooney viscosity of 24 to 25 at 125 ° C. It was a compounded rubber to which a predetermined amount of an agent was added. Rubber hardness when vulcanizing compounded rubber A containing no short fibers was 78 to 81.

  Compounded rubber B is 100 parts by weight of EPDM (rubber component) having a Mooney viscosity of about 60 at 125 ° C., and is based on well-known carbon black, organic metal salt, antioxidant, scorch inhibitor, paraffin oil, vulcanizing agent. Was added in a predetermined amount. Rubber hardness when vulcanizing compounded rubber B containing no short fibers was 81.

[Modulus test]
4 and 5 show the results of the modulus test of the test pieces of the examples and the comparative examples. In this test, the tensile stress with respect to the elongation of the test piece was measured. The test piece was manufactured by vulcanizing each raw rubber obtained by blending short fibers with the compounded rubber A or B. Here, the short fibers were oriented in one direction, and the tensile stress was applied in the orientation direction of the short fibers. In addition, this test was performed by the test method of JISK6251.

[Example 1]
In the raw material rubber of Example 1, in addition to the compounded rubber A, 20 parts by weight of high-strength nylon 66 short fiber was further mixed with 100 parts by weight of the compounded rubber (EPDM). The high-strength nylon 66 short fiber had a fiber length of 1.0 mm, a fineness of 6.7 dtex, a tensile strength of 10.8 cN / dtex (10 g / d), and had been subjected to RFL treatment. In the RFL treatment, the RF / L ratio was 16.5 / 100. The rubber hardness after vulcanization of the compounded rubber containing the short fibers was 91.

[Examples 2 to 10]
The raw rubbers of Examples 2 to 10 are examples in which the length, blending number, and fineness of the short fibers are changed from those of Example 1. Table 1 shows the short fiber length, fineness, and the number of blended parts of the short fiber with respect to 100 parts by weight of the compounded rubber (EPDM) in each example. Other conditions of Examples 2 to 10 were the same as those of Example 1.

[Comparative Example 1]
In the raw rubber of Comparative Example 1, 5.3 parts by weight of aramid short fibers were further added to 100 parts by weight of EPDM in addition to the compounded rubber B. The aramid short fiber had a fiber length of 1 mm, a tensile strength of 24.8 cN / dtex (23 g / d), and had been epoxy-treated. The rubber hardness of the raw rubber of Comparative Example 1 after vulcanization was 85.

  As shown in FIGS. 4 and 5, in the case of the elongation percentage of 20%, the tensile stress of Comparative Example 1 was 5 Mpa or less, whereas the tensile stress of Examples 1 to 10 was all 5 Mpa or more. 5 to 20 MPa. That is, the test piece in this example is higher than the modulus of the test piece in Comparative Example 1. In the case of an elongation of 20%, rubber mixed with short fibers under the conditions of a fineness of 1.7 dtex to 6.7 dtex, a fiber length of 1.0 to 3.0 mm, and a blending number of 10 to 25 parts by weight, particularly a fineness Rubber mixed with short fibers under the conditions of 3.7 dtex to 6.7 dtex, a fiber length of 1.0 to 2.0 mm, and a blending number of 10 to 20 parts by weight has a belt and rubber modulus of Example 1 described later. It was equivalent.

[Comparison of Example Belt and Comparative Example Belt]
Next, the belt of the example is compared with the belt of the comparative example. First, FIG. 6 shows the results of measuring the friction coefficients of the V-ribbed belts of Example 1 and Comparative Examples 1 and 2.

  The belt of Example 1 is a V-ribbed belt using the raw rubber of Example 1 described above for a rib rubber layer. That is, it is a belt obtained by vulcanizing and molding the raw rubber of Example 1 for a rib rubber sheet. The belt of Comparative Example 1 is a V-ribbed belt using the raw rubber of Comparative Example 1 described above for the rib rubber layer.

  The belt of Comparative Example 2 is a V-ribbed belt in which, in addition to the compounded rubber A, a raw rubber in which 20 parts by weight of nylon 66 short fiber is added to 100 parts by weight of EPDM is used as a raw rubber. The nylon 66 short fiber used in Comparative Example 2 had a fiber length of 1 mm, a fineness of 6.7 dtex, and a tensile strength of 7.0 cN / dtex (6.5 g / d). The rubber hardness of the compounded rubber containing the short fibers after vulcanization, that is, the rubber hardness of the rib rubber layer was 85. In addition, the belt of the Example and the comparative example had a belt width of 10.68 mm and a belt length of 1035 mm.

The coefficient of friction was measured three times each, and the measurement results are shown in a range in the graph of FIG. The measurement of the friction coefficient was performed by a friction coefficient measuring device 35 as shown in FIG. This test was performed by cutting the example and comparative example belts to a predetermined length. In the friction coefficient measuring device 35, the diameter of the V-ribbed pulley 36 was 60 mm, and the contact angle α between the V-ribbed pulley 36 and the V-ribbed belt 38 was π / 2 rad (90 degrees). In the V-ribbed belt 38, the V-rib from which the short fibers protruded meshed with the V-ribbed pulley 36. When the rotation speed of the V-ribbed pulley 36 was 42 rpm and the vertical load T2 applied to the V-ribbed belt 38 was 17.2 N, the measuring device 37 measured the horizontal tension T1. By applying T1 and T2 to equation (1), the friction coefficient μ of the V-ribbed belt 38 was determined.
μ = {ln (T1 / T2)} / α (1)

  The friction coefficient was measured after running for 48 hours under the following conditions and before running the belt (0 hours of running). That is, the V-ribbed belt runs around a driven pulley, and runs for 48 hours at room temperature (17 to 30 ° C.) while a load is applied to the outside of the belt by a tensioner pulley provided on the tension side of the belt. I was made to. Here, the rotation ratio between the driving pulley and the driven pulley was adjusted so that the driven pulley slipped at a rate of 4%. The driving pulley was rotated at 2000 rpm, and the load applied per rib by the tensioner pulley was 180N.

  As shown in FIG. 6, the friction coefficient of the V-ribbed belt of Example 1 was around 1 both at 0 hours and 48 hours. In contrast, the V-ribbed belt of Comparative Example 1 was around 1 at 0 hours, but was around 1.85 at 48 hours. In addition, the V-ribbed belt of Comparative Example 2 was around 1.6 after 0 hour and around 1.9 after 48 hours.

  In a V-ribbed belt, the appropriate coefficient of friction is about 1 ± 0.3. If the friction coefficient is higher than this, there is a concern that abnormal noise may occur, and if it is lower than this, power is not transmitted properly.

  According to the measurement results of the friction coefficient, the belt of the example had an appropriate friction coefficient before and after running. On the other hand, with respect to the belt of Comparative Example 1, the friction coefficient before traveling was appropriate, but the friction coefficient after traveling greatly exceeded the appropriate value. The friction coefficient of the belt of Comparative Example 2 had already exceeded the appropriate value before running, and became even larger after running.

  Considering this result, the tensile strength of the short fiber mixed into the belt of Comparative Example 2 is 7.0 cN / dtex, which is relatively lower than the rubber hardness (85) of the rib portion. Therefore, it is presumed that in the grinding process of the rib portion of the belt production, the short fibers were also worn out in large quantities at the same time as the rubber, and were pulled out, and the amount of the short fibers projecting to the side surfaces of the ribs was reduced. . Further, even during running of the belt, the short fibers are worn out and pulled out, so it is estimated that the friction coefficient further increased after running.

  The tensile strength of the short fibers mixed into the belt of Comparative Example 1 was 24.8 cN / dtex, which was too high relative to the rubber hardness (85) of the rib portion. Therefore, it is presumed that the short fibers mixed in the belt of Comparative Example 2 were pulled out during running. Thus, it is considered that the appropriate friction coefficient before traveling increased during traveling.

  On the other hand, the tensile strength of the short fibers mixed in the belt of Example 1 is 10.78 cN / dtex, which is relatively appropriate for the rubber hardness (91) of the rib rubber layer. Therefore, in Example 1, it is presumed that the amount of the drawn or worn short fibers was small at the time of manufacturing and running, and the coefficient of friction was appropriately maintained before and after running.

  8 to 11 show the results of the sound performance evaluation test of the V-ribbed belts of Example 1 and Comparative Example 1. In the sound performance evaluation test, the V-ribbed belts of Example 1 and Comparative Example 1 were wound around driving and driven pulleys, and tension was applied from the inside by tensioner pulleys on the loose side of the belts. A microphone was provided at a position 300 mm from the driving pulley, and the microphone measured the sound pressure of the sound generated by the engagement between the driven pulley and the belt.

  Here, the diameters of the driving, driven, and tensioner pulleys were 130 mm, 130 mm, and 55 mm, respectively. The initial tension of the belt was 294 N, and the load torque of the driven pulley was 10 N · m. The driving pulley was rotated at 1000 rpm. The sound performance evaluation test was performed after running under an environment of 85 ° C. for 24 hours under this condition and before running.

  The sound performance evaluation test was performed by measuring the sound pressure when water was applied to the belt for 30 seconds on the belt tight side in an environment of 25 ± 7 ° C. The watering rate was 300 ml / min. 8 and 9 show the results of the sound performance evaluation test of the belt of Example 1. FIG. 8 shows the results before running, and FIG. 9 shows the results after running for 24 hours.

  As shown in FIGS. 8 and 9, both before and after running, even when water was applied, the rotation speed of the driven pulley hardly decreased from 1000 rpm. That is, the rotational force of the driving pulley was properly transmitted to the driven pulley before and after traveling for 24 hours. The sound pressure level after running for 24 hours was slightly higher than before running, but both before and after running were within a range that was sufficiently acceptable as abnormal noise even when water was applied. . That is, it can be understood that the belt of Example 1 does not generate a loud noise even after traveling for a certain period of time.

  10 and 11 show the results of the sound performance evaluation test of the belt of Comparative Example 1. As described above, the belt of Comparative Example 1 is a belt mixed with short fibers having a tensile strength of 24.8 cN / dtex. FIG. 10 shows the results before running, and FIG. 11 shows the results after running for 24 hours. In this test, both before and after traveling (see FIG. 8) and after traveling (see FIG. 9), when the driven pulley was sprinkled with water, the number of revolutions dropped from 1000 rpm to 0 rpm, and again after a certain period of time, 1000 rpm. Recovered. That is, when water was applied, the driving pulley idled for a certain period of time, and power was not transmitted to the driven pulley.

  Here, both before and after running, the sound pressure level was close to 0 during idling, and no abnormal noise occurred. However, in both cases before traveling and after traveling for 24 hours, when the rotation was recovered from idling, the sound pressure level sharply increased and abnormal noise occurred. Before traveling, the sound pressure level of the abnormal noise was higher than that of the embodiment, but was at an allowable level as the abnormal noise. However, the sound pressure level after running for 24 hours was significantly higher than before running and in the example, and was not an acceptable sound pressure level.

  As described above, in the sound performance evaluation test, it was confirmed that the V-ribbed belt of the present invention hardly generates abnormal noise even after running for a certain period of time.

  In addition, in this specification, hardness means the hardness of the durometer type A, and is measured by the measuring method described in JISK6253. In addition, the tensile strength is measured by a measuring method described in JIS K6251.

1 shows a longitudinal sectional view of a V-ribbed belt according to an embodiment of the present invention. FIG. 4 shows a cross-sectional view of the V-ribbed belt in a manufacturing process. FIG. 4 is a schematic view of a step of forming a rib in a process of manufacturing a V-ribbed belt. The result of the modulus test of the rubber which mixed the short fiber is shown. The result of the modulus test of the rubber which mixed the short fiber is shown. The measurement result of the friction coefficient of the V-ribbed belt of an Example and a comparative example is shown. 1 shows a friction coefficient measuring device. 4 shows a sound pressure level and a rotation speed of a driven pulley of a sound performance evaluation test before traveling in the example. 7 shows a sound pressure level and a rotation speed of a driven pulley in a sound performance evaluation test after running for 24 hours in the example. 7 shows a sound pressure level and a rotation speed of a driven pulley in a sound performance evaluation test before traveling in a comparative example. 9 shows a sound pressure level and a rotation speed of a driven pulley of a sound performance evaluation test after running for 24 hours in a comparative example.

Explanation of reference numerals

10 V ribbed belt 11 rib rubber layer (lower rubber layer)
15 V rib 16 Side surface 20 Short fiber (high strength short fiber)

Claims (12)

A power transmission belt comprising: a lower rubber layer that comes into contact with the pulley when being wound around the pulley; and high-strength short fibers mixed into the lower rubber layer, wherein a part of the high-strength short fibers protrudes. hand,
The power transmission belt according to claim 1, wherein the high-strength short fiber has a tensile strength of 8.6 cN / dtex to 16.2 cN / dtex, and the lower rubber layer has a hardness of 86 to 91. Transmission belt according to claim 1, fineness of the high strength short fiber is characterized in that to not 3.3dtex is 6.7 dtex.   The power transmission belt according to claim 1, wherein the length of the high-strength short fiber is 1 mm to 3 mm.   The power transmission belt according to claim 1, wherein the lower rubber layer is formed by mixing the high-strength short fibers with a compounded rubber, and the hardness of the compounded rubber is 81 or less. The power transmission belt according to claim 4 , wherein the hardness of the compounded rubber is 78 to 81.   The power transmission belt according to claim 1, wherein the high-strength short fibers are polyamide short fibers.   The power transmission belt according to claim 1, wherein the Mooney viscosity of the rubber component of the lower rubber layer is 30 or less at 125 ° C.   The power transmission belt according to claim 1, wherein the high-strength short fibers are subjected to an RFL treatment.   The power transmission belt according to claim 1, wherein the high-strength short fibers are blended in an amount of 10 to 25 parts by weight with respect to 100 parts by weight of the rubber component of the lower rubber layer.   The power transmission belt according to claim 1, wherein the power transmission belt is a V-ribbed belt. Manufacture of a power transmission belt comprising: a lower rubber layer that comes into contact with the pulley when being wound around a pulley; The method,
By grinding the lower rubber layer, comprising a grinding step to project a portion of the high-strength short fiber,
A method for manufacturing a power transmission belt, wherein the high-strength short fiber has a tensile strength of 8.6 cN / dtex to 16.2 cN / dtex, and the lower rubber layer has a hardness of 86 to 91. The method according to claim 11 , wherein the abrasive particles for grinding the lower rubber layer have a particle size of 80 to 170 mesh.

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