Cog-equipped V-belt and belt drive mechanism

Abstract

To provide a cog-type V-belt that maintains resistance to lateral pressure and transmission performance, while suppressing crack formation in the cog valleys and / or peeling of the core wires. [Solution] In a cogged V-belt 1 having a cog portion on at least the inner circumference side in which cog peaks 1a and cog valleys 1b are alternately arranged in the longitudinal direction of the belt, the cog portion is formed of at least a compression rubber layer 2. The compression rubber layer 2 includes a first rubber layer 2a which is the outermost layer on the inner circumference side and a second rubber layer 2b which is on the outer circumference side of the belt than the first rubber layer 2a. The first rubber layer 2a contains first short fibers oriented in the belt width direction, and the bending modulus of elasticity in the direction parallel to the short fibers in the first rubber layer 2a is 1.4 to 3 MPa.

Description

Technical Field

[0001] The present invention relates to a cogged V-belt and a belt transmission mechanism used in a belt-type continuously variable transmission.

Background Art

[0002] The transmission belt used in a power transmission mechanism such as a mechanical device is roughly classified into a friction transmission belt and an engagement transmission belt according to the form of power transmission. As the friction transmission belt, a V-belt, a V-ribbed belt, a flat belt, etc. are known, and as the engagement transmission belt, a toothed belt is known.

[0003] The V-belt includes a Raw-Edge type V-belt (Raw-Edge V-belt) in which a rubber layer with a friction transmission surface (V-shaped side surface) is exposed, and a Wrapped type V-belt (Wrapped V-belt) in which the friction transmission surface is covered with a cover cloth. They are used properly according to the application due to the difference in the surface properties of the friction transmission surface (the friction coefficient between the rubber layer and the cover cloth). The Raw-Edge V-belt includes a Raw-Edge V-belt without cogs, a Raw-Edge cogged V-belt with cogs provided only on the inner peripheral surface of the belt to improve flexibility, and a Raw-Edge double cogged V-belt with cogs provided on both the inner peripheral surface and the outer peripheral surface of the belt to improve flexibility. There is a cogged V-belt called a Raw-Edge double cogged V-belt.

[0004] One application of these cog-type V-belts is a belt-type continuously variable transmission (CVT). As shown in Figure 1, the belt-type CVT 30 is a device that continuously changes the gear ratio by winding a V-belt 31 around a drive pulley 32 and a driven pulley 33. Each pulley 32, 33 consists of fixed sheaves 32a, 33a whose axial movement is restricted or fixed, and movable sheaves 32b, 33b that can move in the axial direction, and has a structure that allows the width of the V-groove of the pulley 32, 33 formed by these fixed sheaves 32a, 33a and movable sheaves 32b, 33b to be continuously changed. The V-belt 31 has tapered surfaces at both ends in the width direction that match the inclination of the opposing surfaces of the V-grooves of each pulley 32, 33, and fits into any position in the pulley radial direction according to the adjusted width of the V-groove. For example, by narrowing the width of the V-groove on the drive pulley 32 and widening the width of the V-groove on the driven pulley 33, the state shown in Figure 1(a) is changed to the state shown in Figure 1(b). This causes the V-belt 31 to move towards the outer circumference in the radial direction of the pulley on the drive pulley 32 side and towards the inner circumference in the radial direction of the pulley on the driven pulley 33 side. As a result, the winding radius around each pulley 32 and 33 changes continuously, allowing for stepless adjustment of the gear ratio. A V-belt used in such a CVT is called a gear shift belt (CVT belt).

[0005] For V-belts, increasing the overall thickness of the belt (i.e., increasing the surface area of ​​the friction transmission surface) is required to improve lateral pressure resistance and transmission capacity. On the other hand, from the perspective of improving bending fatigue resistance and transmission efficiency, it is required to maintain good flexibility by reducing the overall thickness of the belt. The cogs of a cog-type V-belt are designed to meet these conflicting requirements. In other words, in a cog-type V-belt, the cog peaks ensure a large friction transmission surface to improve lateral pressure resistance and transmission capacity, while the cog valleys are designed to maintain good flexibility.

[0006] In a cog-type V-belt, a series of bending and unbending movements (bending deformation) of the belt before and after wrapping around the pulley are continuously repeated. Specifically, when the belt is wrapped around the pulley, it bends around the core wire, so bending stress occurs on the outer circumference side of the core wire due to bending deformation, and compressive stress occurs on the inner circumference side of the core wire due to compressive deformation, causing the belt to deform. Then, as the belt moves away from the pulley, this deformation is released. In other words, in a cog-type V-belt, this deformed state (curved shape) and unbending state (planar shape) are repeated during belt movement, but in this series of movements (bending deformation), the bending of the cog valleys is greater than the bending of the cog peaks. As a result, the fatigue of the compression rubber layer that is repeatedly bent in the cog valleys is greater, and cracks are more likely to occur in the compression rubber layer of the cog valleys compared to the cog peaks. In particular, stress due to bending deformation tends to concentrate at the bottom of the cog valleys (including the deepest part of the cog valleys), and various methods have been proposed to alleviate the stress at the bottom of the cog valleys and suppress cracks in the cog valleys.

[0007] Typically, in belt-type transmissions used in small-scale environments, priority is given to ensuring high flexibility to accommodate winding around small-diameter pulleys. On the other hand, in belt-type transmissions used in large-scale environments, while ensuring adequate flexibility, it is necessary to ensure high levels of lateral pressure resistance and transmission performance to withstand the load levels of the power transmission mechanism. In particular, in large-scale environments, the lateral pressure from the pulleys becomes enormous, and to ensure sufficient lateral pressure resistance, a high level of rigidity (high modulus of elasticity) of the rubber layer is required. Therefore, in belt-type transmissions (especially those used in large-scale environments), means that can ensure resistance to cog valley cracks while maintaining lateral pressure resistance and transmission performance are considered important.

[0008] For example, Japanese Patent Publication No. 7048824 (Patent Document 1) discloses a large cog-type V-belt to be mounted in power transmission mechanisms (particularly belt-type continuously variable transmissions) for the largest agricultural machinery. This document discloses a cog-type V-belt in which the cross-sectional shape of the cog valleys in the longitudinal direction of the belt comprises a bottom made up of a combination of a plurality of continuous circular arcs and side walls of the cog valleys that are inclined with respect to the belt thickness direction, and the plurality of circular arcs constituting the bottom have a specific shape in which the radius of curvature decreases as they move away from the deepest part of the cog valley. Furthermore, this document states that this cog-type V-belt can ensure high resistance to lateral pressure and transmission force, and can also alleviate and disperse stress at the bottom of the cog valleys where stress tends to concentrate due to bending deformation, thereby suppressing the occurrence of cracks in the cog valleys. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 7048824 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, the size of the cog-equipped V-belt used in the power transmission mechanism of the largest agricultural machinery, etc., disclosed in Patent Document 1 (especially the belt-type continuously variable transmission), is very large. For example, it corresponds to a belt of HL to HQ (designation as described in ISO 3410:1989) in the American Association of Agricultural and Biotechnology Engineers (ASABE) standard product category. In addition to standard products with belt widths (top widths) of 44.5 to 76.2 mm and belt thicknesses of 19.8 to 30.5 mm, ASABE also offers non-standard products with a belt thickness of 36 mm. Thus, although a high load level is required in the power transmission mechanism described in Patent Document 1, if the rigidity (high modulus of elasticity) of the rubber layer is at a high level, even if the method for relieving stress at the bottom of the cog grooves disclosed in Patent Document 1 is adopted, it is impossible to avoid stress concentration at the bottom of the cog grooves when the belt bends, and the occurrence of cracks in the cog grooves cannot be sufficiently suppressed. Therefore, in order to balance lateral pressure resistance and flexibility (resistance to cog valley cracking), it is necessary to appropriately adjust the elastic modulus (stiffness) of the compression rubber layer along with the shape near the cog valleys. This will alleviate the stress at the bottom of the cog valleys (including the deepest part of the cog valleys), where stress tends to concentrate due to bending deformation, and suppress the occurrence of cracks in the cog valleys.

[0011] Therefore, the object of the present invention is to provide a cog-type V-belt and its applications that can maintain lateral pressure resistance and transmission performance, and suppress crack formation in the cog valleys and / or peeling of the core wires. [Means for solving the problem]

[0012] As a result of diligent research to achieve the above objectives, the inventors have found that, as a compression rubber layer for a cogged V-belt having a cog section on at least the inner circumference side in which cog peaks and cog valleys are alternately arranged in the longitudinal direction of the belt, by combining a first rubber layer which is the outermost layer on the inner circumference side and contains first short fibers oriented in the width direction, has a bending modulus of 1.4 to 3 MPa in the direction parallel to the short fibers, and a second rubber layer which is on the outer circumference side of the belt than the first rubber layer, and by forming the cog valleys in a specific shape, it is possible to maintain lateral pressure resistance and transmission performance, and suppress the occurrence of cracks in the cog valleys and / or peeling of the core wires, thereby completing the present invention.

[0013] In other words, the present invention includes the following embodiments.

[0014] Appearance [1]: A cogged V-belt having cog sections on at least the inner circumference side, in which cog peaks and cog valleys are arranged alternately in the longitudinal direction of the belt, The cog portion comprises at least a compressed rubber layer, The compression rubber layer includes a first rubber layer which is the outermost layer on the inner circumferential surface side, and a second rubber layer which is on the outer circumferential side of the belt than the first rubber layer. The first rubber layer and the second rubber layer are exposed to form a friction transmission surface. The cross-sectional shape of the cog valley in the thickness direction along the longitudinal direction of the belt is a shape comprising a bottom portion formed by combining a plurality of continuous arcs and a side wall portion extending from the bottom portion inclined with respect to the belt thickness direction or along the belt thickness direction, As the plurality of arcs move away from the deepest part of the cog valley, the radius of curvature decreases. Of the plurality of arcs, the radius of curvature of the first arc passing through the deepest part is larger in diameter than the virtual circle tangent to the deepest part and the side walls on both sides. The first rubber layer includes first short fibers oriented in the belt width direction, A cog-type V-belt in which the first rubber layer has a bending modulus of elasticity in the direction parallel to the short fibers of 1.4 to 3 MPa.

[0015] Embodiment [2]: A V-belt with cogs according to Embodiment [1], wherein the ratio of the radius of curvature R1 of the first arc to the height H1 of the cog portion [(R1 / H1) × 100] is 45 to 55%.

[0016] Embodiment [3]: A cogged V-belt according to Embodiment [1] or [2], wherein the plurality of arcs are a combination of the first arc and a pair of second arcs interposed between the first arc and the side wall portion, and the ratio of the radius of curvature R2 of the second arc to the height H1 of the cog portion [(R2 / H1) × 100] is 10 to 20%.

[0017] Aspect [4]: The cogged V-belt according to any one of the aspects [1] to [3] above, wherein the overall thickness H of the belt is 18 mm or more and less than 27 mm.

[0018] Aspect [5]: The cogged V-belt according to any one of the aspects [1] to [4] above, wherein the overall thickness H of the belt is 18 mm or more and less than 21 mm, and the ratio [(H2 / H)×100] of the valley thickness H2 to the thickness H is 11 to 34%.

[0019] Aspect [6]: The cogged V-belt according to any one of the aspects [1] to [4] above, wherein the overall thickness H of the belt is 21 mm or more and less than 24 mm, and the ratio [(H2 / H)×100] of the valley thickness H2 to the thickness H is 14 to 34%.

[0020] Aspect [7]: The cogged V-belt according to any one of the aspects [1] to [4] above, wherein the overall thickness H of the belt is 24 mm or more and less than 27 mm, and the ratio [(H2 / H)×100] of the valley thickness H2 to the thickness H is 21 to 41%.

[0021] Aspect [8]: The cogged V-belt according to any one of the aspects [1] to [7] above, which is a low-edge cogged V-belt.

[0022] Aspect [9]: A belt drive mechanism comprising the cogged V-belt according to any one of the aspects [1] to [8] above and a pulley, and provided in a belt-type continuously variable transmission.

[0023] Aspect

[10] : The belt drive mechanism according to the aspect [9] above, provided in a belt-type continuously variable transmission in large agricultural machinery.

[0024] In the present application, the numerical range represented by "A to B" means "A or more and B or less", and is used in the sense of including the numerical values A and B at both ends. [[ID=2憨9]]

Advantages of the Invention

[0025] In the present invention, the cogged V-belt has a cog section on at least the inner circumference side in which cog peaks and cog valleys are alternately arranged in the longitudinal direction of the belt. The compression rubber layer of the cogged V-belt includes a first rubber layer which contains first short fibers oriented in the width direction and has a bending modulus of 1.4 to 3 MPa in the direction parallel to the short fibers, and is the outermost layer on the inner circumference side. This is combined with a second rubber layer which is on the outer circumference side of the belt than the first rubber layer. Furthermore, the cog valleys are formed in a specific shape, thereby maintaining lateral pressure resistance and transmission performance, and suppressing the occurrence of cracks in the cog valleys. In addition, the cogged V-belt of the present invention can also suppress delamination between the core wire and the rubber layer. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating the transmission mechanism of a belt-type continuously variable transmission. [Figure 2] Figure 2 is a schematic partial cross-sectional perspective view showing an example of a cog-type V-belt according to the present invention. [Figure 3] Figure 3 is a schematic cross-sectional view of the cog-equipped V-belt shown in Figure 2, cut along the longitudinal direction of the belt in the thickness direction. [Figure 4] Figure 4 is an enlarged view of Figure 3 to illustrate the shape of the Cog Valley. [Figure 5] Figure 5 is a schematic perspective view illustrating the method for measuring the flexural modulus (in the direction parallel to the short fibers) of the cross-linked rubber molded article obtained in the example. [Figure 6] Figure 6 shows the layout of the test machine used in the transmission performance test of the low-edge cogged V-belt obtained in the example. [Figure 7] Figure 7 shows the layout of the testing machine used in the deformation resistance test of the raw-edge cogged V-belt obtained in the example. [Modes for carrying out the invention]

[0027] [Structure of a cog-type V-belt] The cog-equipped V-belt of the present invention has a cog portion at least on the inner circumference side in which cog peaks and cog valleys are arranged alternately in the longitudinal direction of the belt, and the compression rubber layer forming the cog portion has a specific structure. Specifically, the compression rubber layer is multilayered into a laminated structure including a first rubber layer which is the outermost layer on the inner circumference side and a second rubber layer which is on the outer circumference side of the belt than the first rubber layer, the area near the bottom of the cog valley is formed into a specific shape, and the elastic modulus (rigidity) of the first rubber layer forming the area where the bottom of the cog valley is located is adjusted.

[0028] The cogged V-belt of the present invention is not particularly limited as long as the compression rubber layer forming the cog portion has the above characteristics and the first and second rubber layers constituting the compression rubber layer are exposed. It may be a low-edge cogged V-belt in which cogs are formed only on the inner circumference side of the low-edge V-belt, or a low-edge double cogged V-belt in which cogs are formed on both the inner and outer circumference sides of the low-edge V-belt. Of these, the low-edge cogged V-belt is particularly preferred because it is widely used in large variable-speed belts.

[0029] Figure 2 is a schematic partial cross-sectional perspective view showing an example of the cog-covered V-belt (raw-edge cog-covered V-belt) of the present invention, Figure 3 is a schematic cross-sectional view of the cog-covered V-belt of Figure 2 cut in the thickness direction along the longitudinal direction of the belt, and Figure 4 is an enlarged view of Figure 3 to explain the shape of the cog grooves.

[0030] In this example, the raw edge cogged V-belt 1 has a cog section formed on the inner circumferential surface of the compressed rubber layer 2, in which cog peaks 1a and cog valleys 1b are alternately arranged along the longitudinal direction of the belt (circumferential direction or direction A in the figure). The cross-sectional shape of the cog peaks 1a when cut in the thickness direction along the longitudinal direction of the belt is approximately an inverted trapezoid (a roughly inverted trapezoid where the cog width decreases from the outer circumferential side to the inner circumferential side of the belt), and the cross-sectional shape in the thickness direction along the direction perpendicular to the longitudinal direction of the belt (width direction or direction B in the figure) is approximately an inverted trapezoid. That is, each cog peak 1a protrudes in a roughly trapezoidal shape from the cog valley 1b in the cross section in direction A in the belt thickness direction. In other words, in the present invention, the top portion 11 of the cog peaks 1a is formed in a shape parallel to the longitudinal direction of the belt.

[0031] The raw-edge cogged V-belt 1 has a laminated structure, in which a compression rubber layer 2, a core layer (adhesive rubber layer) 3, and a stretch rubber layer 5 are sequentially laminated from the inner circumference to the outer circumference of the belt. Furthermore, a core wire 4 is embedded in the core layer 3, and the cog portion is formed in the compression rubber layer 2 by a cogged molding die.

[0032] The definitions of the overall thickness H, the height of the cog portion (cog height) H1, and the thickness of the valley portion (core valley thickness) H2 of the raw edge cogged V-belt 1 of the present invention are shown in Figures 3 and 4.

[0033] The overall thickness H of the raw-edge cogged V-belt 1 is 18 mm or more and less than 27 mm. The overall thickness H of the cogged V-belt of the present invention may be 8 mm or more, for example 8 to 36 mm, preferably 13 to 33 mm, more preferably 15 to 30 mm, and more preferably 18 mm or more and less than 27 mm. In particular, the cogged V-belt of the present invention preferably has an overall thickness H of 18 mm or more and is a variable speed belt used in a large belt-type continuously variable transmission.

[0034] As shown in Figure 3, in this application, when the compression rubber layer 2 has a cog portion, the total belt thickness H refers to the thickness at the top of the cog portion (the maximum belt thickness). In other words, the thickness H of the raw edge cogged V belt 1 refers to the shortest distance (distance perpendicular to the thickness direction) from the top of the cog ridge 1a of the compression rubber layer 2 (the top on the inner circumference side) to the outer surface of the stretch rubber layer 5.

[0035] In other words, in this application, the overall thickness of a cog-type V-belt refers to the thickness from the outer circumferential surface to the inner circumferential surface (the thickness at the thickest point of the belt), and in the cog portion, the top of the cog is either the inner or outer circumferential surface. Therefore, in a low-edge cog-type V-belt that has cogs only on the inner circumferential surface, the distance from the outer circumferential surface to the top of the cog portion on the inner circumferential surface becomes the overall thickness. In other words, in the case of a low-edge cog-type V-belt, the overall thickness refers to the distance from the top of the cog in the compression rubber layer (the convex top on the inner circumferential side) to the back of the belt, and in the case of a low-edge double-cog-type V-belt, it refers to the distance from the top of the cog in the compression rubber layer (the convex top on the inner circumferential side) to the top of the cog in the stretch rubber layer (the convex top on the outer circumferential side).

[0036] Furthermore, in this application, the term "cog valley" in the cog portion refers to the portion that forms the thin-walled portion of the compression rubber layer having the cog portion, and usually refers to a curved valley or groove (curved groove) located between adjacent cog peaks that protrude on the inner circumference side of the belt.

[0037] In the raw-edge cogged V-belt 1, the cog height H1 (the shortest distance from the deepest part of the cog valley to the top of the cog in the belt thickness direction) is 10 to 15 mm. The cog height H1 of the cogged V-belt of the present invention is, for example, 5 to 20 mm, preferably 10 to 15 mm. If the cog height H1 is too low, the bending resistance of the belt may decrease, and if it is too high, the durability of the belt may decrease.

[0038] The cog height H1 may be appropriately selected according to the overall thickness H of the belt. When the overall thickness H is 18 mm or more and less than 21 mm, the cog height H1 is, for example, 8 to 15 mm, preferably 10 to 13 mm, and more preferably 11 to 12 mm. When the overall thickness H is 21 mm or more and less than 24 mm, the cog height H1 is, for example, 10 to 15 mm, preferably 11 to 14 mm, more preferably 12 to 14 mm, and more preferably 12 to 13 mm. Furthermore, when the overall thickness H is 24 mm or more and less than 27 mm, the cog height H1 is, for example, 11 to 16 mm, preferably 12 to 15 mm, and more preferably 13 to 14 mm.

[0039] In the raw-edge cogged V-belt 1, the core valley thickness H2 (the shortest distance from the central axis of the core wire to the deepest part of the cog valley in the belt thickness direction) is 2 to 11 mm. The core valley thickness H2 of the cogged V-belt of the present invention is, for example, 0.5 to 15 mm, preferably 1 to 13 mm, and more preferably 2 to 11 mm. If the core valley thickness H2 is too thin, the durability of the belt may decrease, and if it is too thick, the bending resistance of the belt may decrease.

[0040] The core thickness H2 may be appropriately selected according to the overall belt thickness H. When the overall thickness H is 18 mm or more and less than 21 mm, the core thickness H2 is, for example, 1 to 9 mm, preferably 2 to 8 mm, more preferably 2 to 7.5 mm, more preferably 3 to 7 mm, and most preferably 3 to 5 mm. When the overall thickness H is 21 mm or more and less than 24 mm, the core thickness H2 is, for example, 2 to 10 mm, preferably 3 to 9 mm, more preferably 3 to 7.5 mm, more preferably 4 to 7 mm, and most preferably 5 to 6 mm. Furthermore, when the overall thickness H is 24 mm or more and less than 27 mm, the core thickness H2 is, for example, 4 to 12 mm, preferably 5 to 11 mm, more preferably 6 to 10 mm, and more preferably 7 to 9 mm.

[0041] In the cog-type V-belt of the present invention, the ratio of the core valley thickness H2 to the overall thickness H [(H2 / H) × 100] is, for example, 5 to 50%, preferably 10 to 45%, more preferably 11 to 41%, more preferably 15 to 35% (particularly 25 to 35%), and most preferably 20 to 30%. If this ratio is too small, the durability of the belt may decrease, and if it is too large, the bending resistance of the belt may decrease.

[0042] The ratio of the core valley thickness H2 to the overall thickness H [(H2 / H) × 100] may be appropriately selected according to the overall thickness H of the belt. When the overall thickness H is 18 mm or more and less than 21 mm, the ratio [(H2 / H) × 100] is, for example, 5 to 40%, preferably 11 to 38% (particularly 11 to 34%), even more preferably 15 to 35%, more preferably 15 to 30%, and most preferably 17 to 28%. When the overall thickness H is 21 mm or more and less than 24 mm, the ratio [(H2 / H) × 100] is, for example, 10 to 40%, preferably 14 to 38%, even more preferably 14 to 35% (particularly 14 to 34%), and more preferably 20 to 30%. Furthermore, when the overall thickness H is 24 mm or more and less than 27 mm, the ratio [(H2 / H) × 100] is, for example, 15 to 50%, preferably 20 to 45%, more preferably 21 to 41%, more preferably 25 to 35%, and most preferably 30 to 35%.

[0043] In particular, as shown in Figures 3 and 4, in this example, the cross-sectional shape of the cog valley 1b is a bottom portion 13 which is a combination of three arcs: a first arc 13a and a pair of second arcs 13b, 13b, and side wall portions 12, 12 which extend from the bottom portion 13 and are inclined at a cog angle θ (inclination angle of one side wall) in a direction in which the diameter of the cog valley 1b expands toward the inner circumference with respect to the belt thickness direction (indicated by the dashed line in Figures 3 and 4). As shown in Figures 3 and 4, when the raw edge cogged V belt 1 is not bent, the radius of curvature of the multiple arcs (first arc 13a and second arc 13b) that constitute the bottom portion 13 decreases as they move away from the deepest part A of the cog valley 1b.

[0044] Specifically, the first arc 13a is represented by a circle C1 having its center O1 on a vertical line VL (belt thickness direction) perpendicular to the longitudinal direction of the belt. However, it has a larger diameter than a virtual circle VC (the dotted circle in Figure 4) which has its center O0, passes through the deepest part A of the cog valley 1b, and touches the deepest part A of the cog valley 1b and the side walls 12 on both sides at three points (a total of three points: the deepest part A and the contact points B on the pair of side walls). In this application, a virtual circle is defined as a circle corresponding to a virtual arc when the bottom is composed of a single arc.

[0045] Furthermore, the second arc 13b is interposed between the first arc 13a and the side wall portion 12. The radius of curvature R2 of the second arc 13b is smaller than the radius of curvature R1 of the first arc 13a.

[0046] In the present invention, the shape of the bottom of the inner circumference cog valley is not limited to a shape formed by combining a first arc and a pair of second arcs, but may be a shape formed by a single arc. However, a shape formed by combining multiple consecutive arcs is preferred in terms of improving durability (resistance to cog valley cracking), and a shape formed by combining a first arc and a pair of second arcs is particularly preferred.

[0047] When the bottom of a cog valley is formed by combining multiple continuous arcs, it is preferable to make the radius of curvature of the first arc located at the deepest part of the cog valley larger than that of the virtual arc, and to decrease the radius of curvature as it moves away from the deepest part. By using such multiple-stage arcs, the stress at the bottom of the cog valley, where stress tends to concentrate due to bending deformation, can be relaxed and dispersed, thereby suppressing the occurrence of cracks in the cog valley. In addition, the length in the belt circumferential direction of the cog section (length of the flat top) can be increased compared to when the bottom is formed by a single arc (corresponding to a virtual arc).

[0048] The radius of curvature R1 of the first arc is, for example, 1 to 10 mm, preferably 3 to 9 mm, and more preferably 4.5 to 8.3 mm. If the radius of curvature R1 is too small, durability (resistance to cog valley cracks) may decrease, and if it is too large, the area of ​​the friction transmission surface of the cog portion will decrease, which may reduce transmission performance.

[0049] The radius of curvature R1 of the first arc may be appropriately selected according to the overall thickness H of the belt. When the overall thickness H is 18 mm or more and less than 21 mm, the radius of curvature R1 of the first arc is, for example, 4.5 to 7.2 mm, preferably 5 to 7 mm, more preferably 5.5 to 6.5 mm, and more preferably 5.5 to 6 mm. When the overall thickness H is 21 mm or more and less than 24 mm, the radius of curvature R1 of the first arc is, for example, 4.5 to 8 mm, preferably 5 to 7.7 mm, more preferably 5.5 to 7.5 mm, and more preferably 6 to 7 mm. Furthermore, when the overall thickness H is 24 mm or more and less than 27 mm, the radius of curvature R1 of the first arc is, for example, 5.4 to 8.3 mm, preferably 6 to 8 mm, more preferably 6.5 to 7.5 mm, and more preferably 6.5 to 7 mm.

[0050] The ratio of the radius of curvature R1 of the first arc to the cog height H1 [(R1 / H1) × 100] is, for example, 40-65%, preferably 40-60%, preferably 45-55%, more preferably 47-53%, and more preferably 48-52%. If the ratio is too small, durability (resistance to cog valley cracks) may decrease, and if it is too large, transmission efficiency may decrease.

[0051] The radius of curvature R2 of the second arc is, for example, 0.1 to 5 mm, preferably 0.5 to 4 mm, and more preferably 1 to 3 mm. If the radius of curvature R2 is too small, the bending resistance may decrease and durability may be reduced, and if it is too large, the area of ​​the friction transmission surface of the cog may decrease and transmission efficiency may be reduced.

[0052] The radius of curvature R2 of the second arc may be appropriately selected according to the overall thickness H of the belt. When the overall thickness H is 18 mm or more and less than 21 mm, the radius of curvature R2 of the second arc is, for example, 0.5 to 3 mm, preferably 1 to 2.6 mm, more preferably 1.2 to 2.3 mm, and more preferably 1.4 to 2 mm. When the overall thickness H is 21 mm or more and less than 24 mm, the radius of curvature R2 of the second arc is, for example, 0.5 to 3.5 mm, preferably 1.1 to 2.8 mm, more preferably 1.3 to 2.3 mm, and more preferably 1.5 to 2 mm. Furthermore, when the overall thickness H is 24 mm or more and less than 27 mm, the radius of curvature R2 of the second arc is, for example, 0.5 to 3.5 mm, preferably 1.2 to 3 mm, more preferably 1.5 to 2.8 mm, and more preferably 1.8 to 2.5 mm.

[0053] The ratio of the radius of curvature R2 of the second arc to the cog height H1 [(R2 / H1) × 100] may be appropriately selected according to the overall thickness H of the belt. When the overall thickness H is 18 mm or more and less than 21 mm, the ratio of the radius of curvature R2 of the second arc to the cog height H1 is, for example, 5 to 30%, preferably 10 to 20%, more preferably 11 to 15%, more preferably 12 to 14%, and most preferably 12.5 to 13.5%. When the overall thickness H is 21 mm or more and less than 27 mm, the ratio of the radius of curvature R2 of the second arc to the cog height H1 is, for example, 5 to 30%, preferably 10 to 20%, and more preferably 13 to 17%.

[0054] In the cross-sectional shape of the cog valley, the side wall portion is not limited to a shape that extends from the bottom at a cog angle θ in a direction that increases the diameter of the cog valley toward the inner circumference with respect to the belt thickness direction, but may also be a shape that extends from the bottom along (parallel to) the belt thickness direction.

[0055] The cog angle θ of the side wall is, for example, 15° or less, preferably 10° or less, more preferably 8° or less, and more preferably 5° or less. If the cog angle θ is large, the area of ​​the friction transmission surface of the cog becomes smaller, which may reduce the transmission efficiency.

[0056] In the cog-type V-belt of the present invention, it is preferable to apply a chamfer of C0.5mm to C2.0mm or an R0.5mm to R2.0mm to the intersection of the flat top portion 11 and the side wall portion 12, in order to prevent chipping of the edge portion.

[0057] In the present invention, the compression rubber layer 2 is formed of a first rubber layer 2a on the inner circumference side of the belt and a second rubber layer 2b on the outer circumference side of the belt than the first rubber layer 2a. In a cross-sectional view in the thickness direction along the circumferential direction of the belt (cross-sectional shape obtained by cutting in the thickness direction along the longitudinal direction of the belt), the boundary between the first rubber layer 2a and the second rubber layer 2b is a wave shape that follows the contours of the cog peaks 1a and cog valleys 1b (contours of the inner surface of the belt). In the compression rubber layer 2, a crosslinked rubber composition with a lower elastic modulus than the second rubber layer 2b is applied to the first rubber layer 2a, and the first rubber layer 2a is positioned at the bottom of the cog valleys 1b (including the deepest part of the cog valleys 1b) where stress tends to concentrate due to bending deformation. As a result, while maintaining lateral pressure resistance and transmission performance with the cross-linked rubber composition (high modulus) of the second rubber layer 2b (core wire side), the cross-linked rubber composition (low modulus) of the first rubber layer 2a is placed at the bottom of the cog valley 1b (including the deepest part of the cog valley) to relieve stress and suppress crack formation in the cog valley.

[0058] [Compressed rubber layer] In the cog-type V-belt of the present invention, the compression rubber layer includes a first rubber layer which is the outermost layer on the inner circumferential surface side, and a second rubber layer which is located on the outer circumferential side of the belt than the first rubber layer.

[0059] (First rubber layer) The first rubber layer is formed of a first crosslinked rubber composition containing a first rubber component and first short fibers.

[0060] (1A) First rubber component As the first rubber component, vulcanizable or crosslinkable rubber may be used, for example, diene rubber [natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), hydrogenated nitrile rubber (H-NBR), etc.], ethylene-α-olefin elastomer [ethylene-propylene copolymer (EPM), ethylene-butene copolymer (EBM), ethylene-hexene copolymer (EHM), ethylene-octene copolymer (EOM), etc.], ethylene-α-C 3-8 Olefin binary copolymers; ethylene-α-C such as ethylene-propylene-nonconjugated diene copolymer (EPDM), ethylene-1-butene-nonconjugated diene copolymer (EBDM), and ethylene-1-octene-nonconjugated diene copolymer (EODM). 3-8 Examples include olefin-non-conjugated polyene terpolymers, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, and fluororubber. These rubber components can be used individually or in combination of two or more.

[0061] Of these, ethylene-α-olefin elastomer and chloroprene rubber are preferred because they can improve durability such as ozone resistance, heat resistance, cold resistance, weather resistance, and crack resistance. 3-4 Ethylene-α-olefin-diene terpolymer rubbers, such as olefin-non-conjugated diene terpolymer rubber, are preferred, and EPDM is particularly preferred.

[0062] When the first rubber component contains ethylene-α-olefin elastomer, the proportion of ethylene-α-olefin elastomer in the first rubber component may be 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more (particularly 90-100% by mass), and most preferably 100% by mass (ethylene-α-olefin elastomer only), from the viewpoint of improving the above properties and productivity.

[0063] The proportion of the first rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 40 to 70% by mass, more preferably 45 to 65% by mass, and most preferably 50 to 60% by mass in the first crosslinked rubber composition.

[0064] (1B) First short fiber Examples of first staple fibers include polyamide staple fibers (aliphatic polyamide staple fibers such as polyamide 6 staple fibers, polyamide 66 staple fibers, polyamide 46 staple fibers, etc., aramid staple fibers, etc.), polyalkylene arylate staple fibers (e.g., polyethylene terephthalate (PET) staple fibers, polyethylene naphthalate staple fibers, etc.), liquid crystal polyester staple fibers, polyarylate staple fibers (amorphous all-aromatic polyester staple fibers, etc.), vinylon staple fibers, polyvinyl alcohol-based staple fibers, poly-p-phenylene benzobisoxazole (PBO) staple fibers, and other synthetic staple fibers; cellulose staple fibers such as cotton and linen, natural staple fibers such as wool; and inorganic staple fibers such as carbon staple fibers and glass staple fibers. These first staple fibers can be used individually or in combination of two or more types. Of these, short fibers with a low modulus of elasticity, such as aliphatic polyamide short fibers, polyalkylene arylate short fibers, and cellulose short fibers, are preferred because they make it easier to make the elastic modulus of the first rubber layer smaller than that of the second rubber layer, and aliphatic polyamide short fibers are particularly preferred because they make it easier to achieve the objectives of the present invention.

[0065] The first short fibers may be short fibers obtained by cutting fibers that have been stretched into a fibrous shape to a predetermined length. The first short fibers are preferably embedded in the first rubber layer oriented substantially parallel to the belt width direction in order to suppress compressive deformation of the belt due to lateral pressure from the pulley (to improve lateral pressure resistance). Furthermore, it is preferable to allow the short fibers to protrude from the surface of the first rubber layer in order to reduce wear due to friction with the pulley.

[0066] The average fiber length of the first short fibers is, for example, 0.1 to 20 mm, preferably 0.5 to 15 mm, more preferably 0.5 to 10 mm, more preferably 1 to 6 mm, and most preferably 2 to 4 mm, in order to improve lateral pressure resistance and transmission performance without reducing flexibility. If the fiber length of the first short fibers is too short, the mechanical properties in the direction of grain cannot be sufficiently improved, which may reduce lateral pressure resistance and transmission performance. If it is too long, the orientation of the first short fibers in the first crosslinked rubber composition may decrease, which may reduce flexibility.

[0067] The average fiber diameter of the first short fibers is, for example, 1 to 100 μm, preferably 3 to 70 μm, more preferably 5 to 50 μm, more preferably 10 to 40 μm, and most preferably 20 to 30 μm, in order to provide a high reinforcing effect without reducing flexibility. If the average fiber diameter is too small, the dispersibility in the rubber may decrease, which may reduce the flexibility of the belt. Conversely, if it is too large, the lateral pressure resistance and transmission performance of the belt per unit of compounding amount may decrease.

[0068] The average fineness of the first short fibers is, for example, 1 to 12 dtex, preferably 1.2 to 10 dtex, and more preferably 1.5 to 5 dtex.

[0069] The first short fibers may be embedded in the first rubber layer, oriented substantially parallel to the belt width direction, in order to suppress compressive deformation of the belt due to pressure from the pulley.

[0070] In this application, "approximately parallel" to the belt width direction means that the angle with respect to the belt width direction is, for example, 10° or less, preferably 8° or less, more preferably 5° or less, more preferably 3° or less, and most preferably 1° or less (for example, 0 to 1°, particularly approximately 0°).

[0071] The first short fibers may be subjected to conventional bonding treatments to enhance their adhesion to the first rubber component. Conventional bonding treatments include immersion in a treatment solution containing an epoxy compound or a polyisocyanate compound, immersion in an RFL treatment solution containing resorcinol (R), formaldehyde (F), and latex (L), and immersion in rubber adhesive. These treatments may be applied individually or in combination of two or more. Of these, immersion in an RFL treatment solution and immersion in rubber adhesive are preferred, and a combination of both methods is particularly preferred.

[0072] The proportion of the first short fibers is, for example, 10 to 50 parts by mass, preferably 15 to 35 parts by mass, more preferably 20 to 33 parts by mass, more preferably 22 to 32 parts by mass, and most preferably 25 to 30 parts by mass, per 100 parts by mass of the first rubber component. If there are too few first short fibers, the lateral pressure resistance and transmission performance of the belt may decrease, and if there are too many, the processability of the belt may decrease, or the flexibility of the belt may decrease, which may reduce its durability.

[0073] (1C) Other ingredients The crosslinked rubber composition forming the first rubber layer may contain conventional additives (first additives), and the first additive may include, for example, crosslinking agents or vulcanizing agents (sulfur-based crosslinking agents, organic peroxides, etc.), co-crosslinking agents (bismaleimides, etc.), crosslinking aids or crosslinking accelerators (thiuram-based accelerators, sulfenamide-based accelerators, thiomorpholine-based accelerators, etc.), crosslinking retarders, metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), fillers [reinforcing agents such as carbon black, silicon oxide (hydrated silica, etc.) (reinforcing fillers); bulking agents such as clay, calcium carbonate, talc, mica (non-reinforcing fillers or non-reinforcing fillers)]. Examples of additives include active fillers, plasticizers (or softeners) [oils (paraffin oil, naphthenic oil, etc.), aliphatic carboxylic acid plasticizers, aromatic carboxylic acid ester plasticizers, oxycarboxylic acid ester plasticizers, phosphate ester plasticizers, ether plasticizers, ether ester plasticizers, etc.], processing agents or processing aids (stearic acid, metal stearic acid salts, waxes, paraffin, fatty acid amides, etc.), anti-aging agents (antioxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), adhesion improvers, colorants, tackifiers, coupling agents (silane coupling agents, etc.), stabilizers (UV absorbers, heat stabilizers, etc.), flame retardants, and antistatic agents. These additives can be used individually or in combination of two or more. Metal oxides may also act as crosslinking agents.

[0074] The proportion of the crosslinking agent (first crosslinking agent) is, for example, 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, more preferably 0.7 to 2 parts by mass, and most preferably 0.8 to 1.5 parts by mass, per 100 parts by mass of the first rubber component.

[0075] The proportion of the crosslinking aid (first crosslinking aid) is, for example, 0.2 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 1 to 7 parts by mass, more preferably 2 to 6 parts by mass, and most preferably 3 to 5 parts by mass, per 100 parts by mass of the first rubber component.

[0076] The proportion of the filler (first filler) is, for example, 10 to 200 parts by mass, preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass, more preferably 30 to 70 parts by mass, and most preferably 40 to 60 parts by mass, per 100 parts by mass of the first rubber component. Carbon black is preferred as the first filler.

[0077] The proportion of the metal oxide (first metal oxide) is, for example, 0.5 to 30 parts by mass, preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass, per 100 parts by mass of the first rubber component. Zinc oxide is preferred as the first metal oxide.

[0078] The proportion of the plasticizer (first plasticizer) may be 20 parts by mass or less per 100 parts by mass of the first rubber component, for example, 0.1 to 20 parts by mass, preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass.

[0079] The proportion of the anti-aging agent (first anti-aging agent) is, for example, 0.2 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 1 to 7 parts by mass, more preferably 2 to 6 parts by mass, and most preferably 3 to 5 parts by mass, per 100 parts by mass of the first rubber component.

[0080] The total proportion of the first additive is, for example, 5 to 300 parts by mass, preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and more preferably 50 to 100 parts by mass, per 100 parts by mass of the first rubber component.

[0081] (1D) Characteristics of the first rubber layer In this invention, the first rubber layer is the outermost layer on the inner circumferential surface, and the bottom of the cog valley (including the deepest part of the cog valley) is formed by the first rubber layer. Therefore, by adjusting the elastic modulus of the first rubber layer to a specific range, the stress at the bottom of the cog valley can be relieved, and the occurrence of cracks in the cog valley can be suppressed. In this application, the elastic modulus of the first and second rubber layers are evaluated based on the flexural modulus (8% flexural modulus in the direction parallel to the short fibers) as an indicator of how easily the belt can be bent in the circumferential direction.

[0082] The flexural modulus of the first rubber layer (first crosslinked rubber composition) is, for example, 1.4 to 3 MPa (particularly 2 to 2.5 MPa), preferably 1.9 to 2.7 MPa (particularly 2.1 to 2.4 MPa), more preferably 2 to 2.6 MPa, more preferably 2.1 to 2.6 MPa, and most preferably 2.2 to 2.5 MPa. If the flexural modulus is too low, the lateral pressure resistance of the belt may decrease, and if it is too high, the stress concentrated due to the bending deformation of the belt may not be relieved, and the crack resistance of the belt may decrease.

[0083] In this application, the flexural modulus is the 8% flexural modulus (or 8% flexural stress) in the direction parallel to the short fibers. Specifically, it can be measured by arranging the pressing member so that its longitudinal direction is the orientation direction (length direction) of the short fibers. More specifically, it can be measured by the method described in the embodiments below.

[0084] Furthermore, in this application, "direction parallel to the short fibers" may refer not only to the longitudinal direction of the short fibers, but also to directions within a range of ±5° from the longitudinal direction.

[0085] Preferably, the elastic modulus of the first rubber layer (first crosslinked rubber composition) is lower than that of the second rubber layer (second crosslinked rubber composition).

[0086] The area ratio of the first rubber layer is, in a cross-sectional view along the thickness direction of the belt circumferential direction (cross-sectional shape obtained by cutting along the thickness direction of the belt longitudinal direction), for example, 10 to 90% (particularly 40 to 70%), preferably 30 to 80%, more preferably 40 to 75%, more preferably 50 to 70%, and most preferably 55 to 65% of the total area of ​​the compression rubber layer. If the area ratio is too small, the crack resistance of the belt may decrease, and conversely, if it is too large, the lateral pressure resistance of the belt may decrease.

[0087] In this application, the area ratio of each rubber layer in the compressed rubber layer is considered to be the ratio calculated from the thickness ratio of the raw material, the uncrosslinked rubber sheet.

[0088] The shape of the first rubber layer is not particularly limited as long as it is located on the outermost surface of the inner circumferential surface and has the aforementioned area ratio. As shown in Figures 2 and 3, the interface with the second rubber layer may have a layer shape that follows the inner circumferential surface of the belt (the boundary with the second rubber layer is wavy in the cross-section in the thickness direction along the longitudinal direction of the belt), or the interface may have a layer shape that follows the flat outer circumferential surface of the cog-equipped V-belt shown in Figure 2 (the boundary with the second rubber layer is straight in the cross-section in the thickness direction along the longitudinal direction of the belt).

[0089] The average thickness of the first rubber layer is, for example, 1 to 15 mm, preferably 3 to 10 mm, more preferably 4 to 9 mm, more preferably 5 to 8 mm, and most preferably 6 to 8 mm. If the average thickness is too thin, the crack resistance of the belt may decrease, and if it is too thick, the lateral pressure resistance of the belt may decrease.

[0090] In this application, the average thickness of the first rubber layer is the sum of the thickness measured at five locations in the center of each cog peak and cog valley, divided by 10.

[0091] (Second rubber layer) The second rubber layer is formed of a second crosslinked rubber composition containing a second rubber component and second short fibers.

[0092] (2A) Second rubber component The second rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The second rubber component may be a different rubber component from the first rubber component, but is usually the same rubber component as the first rubber component.

[0093] The proportion of the second rubber component in the second crosslinked rubber composition can be selected from the proportion of the first rubber component in the first crosslinked rubber composition, including a preferred range.

[0094] (2B) Second staple fiber Examples of the second short fiber include the short fibers exemplified as the first short fiber. The short fibers can be used alone or in combination of two or more types. Among the short fibers, high modulus short fibers such as aramid short fibers and PBO short fibers are preferred as the second short fiber, as they make it easier to make the modulus of elasticity of the second rubber layer greater than that of the first rubber layer and thus easier to achieve the objectives of the present invention. Aramid short fibers are particularly preferred.

[0095] The second short fiber may be a short fiber obtained by cutting a fibrously stretched fiber to a predetermined length. The second short fiber is preferably embedded in the second rubber layer oriented substantially parallel to the belt width direction in order to suppress compressive deformation of the belt due to lateral pressure from the pulley. Furthermore, it is preferable to have the short fiber protrude from the surface of the second rubber layer in order to reduce wear due to friction with the pulley.

[0096] The average fiber length of the second short fibers is, for example, 0.1 to 20 mm, preferably 0.5 to 15 mm, more preferably 0.5 to 10 mm, more preferably 1 to 6 mm, and most preferably 2 to 4 mm, in order to improve lateral pressure resistance and transmission performance without reducing flexibility. If the fiber length of the second short fibers is too short, the mechanical properties in the direction of grain cannot be sufficiently improved, which may reduce lateral pressure resistance and transmission performance. Conversely, if the fiber length is too long, the orientation of the second short fibers in the crosslinked rubber composition may decrease, which may reduce flexibility.

[0097] The average fineness of the second staple fiber is, for example, 1 to 12 dtex, preferably 1.2 to 10 dtex, more preferably 1.5 to 5 dtex, more preferably 1.8 to 3 dtex, and most preferably 2 to 2.5 dtex, in order to provide a high reinforcing effect without reducing flexibility. If the average fineness is too low, the flexibility of the belt may decrease due to reduced dispersibility in the rubber, and conversely, if it is too high, the lateral pressure resistance and transmission performance of the belt per unit amount may decrease.

[0098] The average fiber diameter of the second short fiber is, for example, 1 to 100 μm, preferably 3 to 70 μm, more preferably 5 to 50 μm, more preferably 7 to 40 μm, and most preferably 10 to 30 μm.

[0099] The second short fibers may be embedded in the second rubber layer, oriented substantially parallel to the belt width direction, in order to suppress compressive deformation of the belt due to pressure from the pulley.

[0100] The second short fiber may be subjected to a conventional bonding treatment to enhance its adhesion to the second rubber component. The conventional bonding treatment can be selected from the bonding treatments exemplified for the first short fiber, including preferred embodiments.

[0101] The proportion of the second short fibers is, for example, 5 to 50 parts by mass (particularly 10 to 30 parts by mass), preferably 13 to 29 parts by mass, more preferably 15 to 28 parts by mass, more preferably 18 to 27 parts by mass, and most preferably 20 to 25 parts by mass, per 100 parts by mass of the second rubber component. If there are too few second short fibers, the lateral pressure resistance and transmission performance of the belt may decrease, and conversely, if there are too many, the processability of the belt may decrease, or the flexibility of the belt may decrease, which may reduce its durability.

[0102] (2C) Other ingredients The second crosslinked rubber composition forming the second rubber layer may contain conventional additives (second additives), and the second additive can be selected from the additives exemplified as first additives, including preferred embodiments. The ratio of each second additive to 100 parts by mass of the second rubber component can also be selected from the ratio of each first additive to 100 parts by mass of the first rubber component, including preferred ranges. The total ratio of the second additives to 100 parts by mass of the second rubber component can also be selected from the total ratio of the first additives to 100 parts by mass of the first rubber component, including preferred ranges.

[0103] (2D) Characteristics of the second rubber layer The flexural modulus of the second rubber layer (second crosslinked rubber composition) is, for example, 2.5 to 4 MPa (particularly 3.1 to 3.4 MPa), preferably 2.9 to 3.5 MPa, more preferably 3 to 3.3 MPa, more preferably 3.1 to 3.3 MPa, and most preferably 3.2 to 3.3 MPa. If the flexural modulus is too low, the lateral pressure resistance of the belt may decrease, and conversely, if it is too high, the flexibility of the belt may decrease.

[0104] The second rubber layer may have a structure in which multiple rubber layers with different flexural moduli are laminated, but a single-layer structure is preferred from the standpoint of productivity and other factors.

[0105] The area ratio of the second rubber layer is, in a cross-sectional view in the thickness direction along the circumferential direction of the belt, for example, 10 to 90% (particularly 10 to 70%), preferably 15 to 60%, more preferably 20 to 55%, more preferably 30 to 50%, and most preferably 35 to 45% of the total area of ​​the compression rubber layer. If the area ratio is too small, the lateral pressure resistance of the belt may decrease, and conversely, if it is too large, the crack resistance of the belt may decrease.

[0106] The shape of the second rubber layer is not particularly limited as long as it is interposed between the first rubber layer and the core layer and has the aforementioned area ratio. As shown in Figures 2 and 3, the interface with the first rubber layer may be a layer shape along the inner circumferential surface of the belt (the boundary with the first rubber layer is wavy in the cross-section in the thickness direction along the longitudinal direction of the belt), or the interface may be a layer shape along the flat outer circumferential surface of the belt (the boundary with the first rubber layer is linear in the cross-section in the thickness direction along the longitudinal direction of the belt).

[0107] The average thickness of the second rubber layer is, for example, 1 to 12 mm, preferably 1.5 to 10 mm, more preferably 2 to 9 mm, more preferably 3 to 8 mm, and most preferably 4 to 6 mm. If the average thickness is too thin, the lateral pressure resistance of the belt may decrease, and conversely, if it is too thick, the flexibility of the belt may decrease.

[0108] In this application, the average thickness of the second rubber layer is defined as the sum of the thickness measured at the center of each cog peak and the thickness measured at the center of each cog valley, divided by 10.

[0109] (Characteristics of the compressed rubber layer) The flexural modulus of the first rubber layer may be 0.5 to 0.9 times that of the flexural modulus of the second rubber layer, preferably 0.6 to 0.8 times, more preferably 0.62 to 0.8 times, more preferably 0.63 to 0.75 times, and most preferably 0.65 to 0.7 times. If the ratio of the flexural modulus of the first rubber layer is too small, the crack resistance of the belt may decrease, and if it is too large, the lateral pressure resistance of the belt may decrease.

[0110] The compression rubber layer may further include other rubber layers in addition to the first and second rubber layers, as long as it does not impair the effects of the present invention. The other rubber layer may be an adhesive rubber layer (first adhesive rubber layer) interposed between the reinforcing fabric and the first rubber layer when the inner circumferential surface of the cog portion is covered with the reinforcing fabric. The thickness of the first adhesive rubber layer should be such that it improves the adhesion between the reinforcing fabric and the first rubber layer. The average thickness of the first adhesive rubber layer is preferably 0.5 mm or less, and more preferably 0.3 mm or less. If the thickness of the first adhesive rubber layer is too thick, the lateral pressure resistance of the belt may decrease.

[0111] A preferred structure for the compression rubber layer is one consisting of a first rubber layer on the inner circumference of the belt and a second rubber layer on the outer circumference of the belt.

[0112] The average thickness of the compression rubber layer is, for example, 5 to 30 mm, preferably 10 to 25 mm, more preferably 12 to 20 mm, and more preferably 15 to 18 mm. In this application, the thickness of the compression rubber layer refers to the maximum thickness (thickness at the top of the cog portion).

[0113] [Core layer] The core layer only needs to include a core wire as a core, and may be a core layer formed only of core wires. However, a combination of a core wire and an adhesive rubber layer (third adhesive rubber layer) formed of a third crosslinked rubber composition containing a third rubber component is preferred in order to suppress delamination between layers and improve belt durability. When forming a core layer by combining a core wire and a third adhesive rubber layer, at least a part of the core wire needs to be in contact with the third adhesive rubber layer, and it may be in any of the following forms: the third adhesive rubber layer embeds the core wire, the core wire is embedded between the third adhesive rubber layer and the stretch rubber layer, or the core wire is embedded between the third adhesive rubber layer and the compression rubber layer. Of these, the form in which the third adhesive rubber layer embeds the core wire is preferred in order to improve durability (i.e., the third adhesive rubber layer is interposed between the stretch rubber layer and the compression rubber layer to bond the stretch rubber layer and the compression rubber layer, and the entire core wire is embedded in the third adhesive rubber layer).

[0114] (Third adhesive rubber layer) The third adhesive rubber layer is formed from a third crosslinked rubber composition containing a third rubber component.

[0115] (3A) Third rubber component The third rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The third rubber component may be a different rubber component from the first rubber component, but is usually the same rubber component as the first rubber component.

[0116] (3B) Other ingredients The third adhesive rubber layer may contain conventional additives (third additives). Examples of third additives include those exemplified as first additives. These additives can be used alone or in combination of two or more.

[0117] The proportion of the third crosslinking agent is, for example, 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, more preferably 0.7 to 2 parts by mass, and most preferably 0.8 to 1.5 parts by mass, per 100 parts by mass of the third rubber component.

[0118] The proportion of the third crosslinking aid is, for example, 0.2 to 10 parts by mass, preferably 0.3 to 7 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, and most preferably 1.5 to 2.5 parts by mass, per 100 parts by mass of the third rubber component.

[0119] The proportion of the third filler is, for example, 10 to 200 parts by mass, preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass, more preferably 30 to 70 parts by mass, and most preferably 40 to 60 parts by mass, per 100 parts by mass of the third rubber component. A combination of carbon black and silica is preferred as the third filler.

[0120] The proportion of the third metal oxide is, for example, 0.5 to 30 parts by mass, preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass, per 100 parts by mass of the third rubber component. Zinc oxide is preferred as the third metal oxide.

[0121] The proportion of the third plasticizer may be 20 parts by mass or less (particularly 10 parts by mass or less) per 100 parts by mass of the third rubber component, for example, 0.1 to 20 parts by mass, preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass.

[0122] The proportion of the third anti-aging agent is, for example, 0.2 to 10 parts by mass, preferably 0.3 to 7 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, and most preferably 1.5 to 2.5 parts by mass, per 100 parts by mass of the third rubber component.

[0123] The total proportion of the third additive is, for example, 5 to 300 parts by mass, preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and more preferably 50 to 100 parts by mass, per 100 parts by mass of the third rubber component.

[0124] The third adhesive rubber layer may contain short fibers (third short fibers). The third short fibers can be selected from the short fibers exemplified as the first short fibers, including preferred embodiments.

[0125] The proportion of the third short fibers is, for example, 50 parts by mass or less, preferably 30 parts by mass or less, more preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and most preferably 1 part by mass or less, per 100 parts by mass of the third rubber component. The third adhesive rubber layer does not need to contain short fibers.

[0126] The average thickness of the third adhesive rubber layer is, for example, 0.8 to 5 mm, preferably 1.5 to 4 mm, more preferably 2 to 3.5 mm, and more preferably 2.5 to 3 mm.

[0127] (Core wire) The core wires are not particularly limited, but typically, core wires (twisted cords) arranged at predetermined intervals in the belt width direction can be used. The core wires may be embedded at equal intervals (or pitches) from one end to the other in the belt width direction of the core layer.

[0128] The core wires are arranged extending in the longitudinal direction (circumferential direction) of the belt, and multiple core wires may be arranged parallel to the longitudinal direction of the belt. However, from the standpoint of productivity, they are usually arranged spirally, extending in parallel at a predetermined pitch, approximately parallel to the longitudinal direction of the cogted V-belt. When arranged spirally, the angle of the core wires with respect to the longitudinal direction of the belt may be, for example, 5° or less, and from the standpoint of belt running performance, it is preferable that the angle is as close to 0° as possible.

[0129] The core wire pitch (the distance between the centers of adjacent core wires) should be greater than the core wire diameter and is set in the range of approximately 0.5 to 3.5 mm depending on the core wire diameter, preferably 1.5 to 3 mm, more preferably 2 to 2.5 mm, and more preferably 2.2 to 2.4 mm.

[0130] Examples of fibers constituting the core wire include those exemplified as fibers constituting the first short fibers. Among these fibers, synthetic fibers such as polyester fibers (polyalkylene arylate fibers) and aramid fibers, and inorganic fibers such as carbon fibers are often used from the viewpoint of high modulus, with polyalkylene arylate fibers and aramid fibers being preferred, and aramid fibers being particularly preferred.

[0131] The fiber may be a multifilament yarn. The fineness of the multifilament yarn is, for example, 300 to 10000 dtex, preferably 500 to 5000 dtex, and more preferably 1000 to 3000 dtex. The multifilament yarn may contain, for example, about 100 to 5000 monofilament yarns, preferably 500 to 4000 monofilament yarns, and more preferably about 1000 to 3000 monofilament yarns.

[0132] Typically, twisted cords using multifilament yarn (e.g., multi-ply, single-ply, Lang-ply, etc.) can be used as the core wire. The average wire diameter of the core wire (diameter of the twisted cord) may be, for example, 0.5 to 3 mm, preferably 1 to 2.5 mm, more preferably 1.5 to 2.3 mm, more preferably 1.7 to 2.1 mm, and most preferably 1.8 to 2 mm. If the core wire is too thin, the flexibility will improve, but the tension of the belt may decrease, and conversely, if it is too thick, the bending resistance of the belt may decrease.

[0133] The core wire may be bonded (or surface-treated) in the same manner as the first short fiber in order to improve its adhesion to the third rubber component. Preferably, the core wire is bonded with at least RFL liquid.

[0134] [Stretchable rubber layer] The stretchable rubber layer is formed from a fourth crosslinked rubber composition containing a fourth rubber component.

[0135] The fourth rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The fourth rubber component may be a different rubber component from the first rubber component, but is usually the same rubber component as the first rubber component.

[0136] The fourth crosslinked rubber composition forming the stretchable rubber layer also preferably contains fourth short fibers, as this can further improve lateral pressure resistance and transmission performance. Including fourth short fibers as short fibers not only in the compression rubber layer but also in the stretchable rubber layer further improves lateral pressure resistance and transmission performance. The fourth short fibers can be selected from the short fibers exemplified in the second short fibers, including preferred embodiments. The fourth short fibers may be different from the second short fibers, but are usually the same as the second short fibers. The proportion of the fourth short fibers can be selected from the proportion of the second short fibers, including preferred proportions.

[0137] The rubber composition forming the stretchable rubber layer may further contain other components as exemplified in the second crosslinked rubber composition forming the second rubber layer of the compression rubber layer.

[0138] The average thickness of the stretched rubber layer is, for example, 0.5 to 3 mm, preferably 0.8 to 2.5 mm, and more preferably 1.1 to 2.2 mm.

[0139] [Reinforcement fabric] The cog-equipped V-belt of the present invention may include a reinforcing fabric. Examples of the reinforcing fabric include being laminated on the surface of the stretchable rubber layer and / or the compression rubber layer, or being embedded in the stretchable rubber layer and / or the compression rubber layer (for example, the form described in Japanese Patent Application Publication No. 2010-230146).

[0140] The reinforcing fabric may be made of conventional fabrics. Examples of conventional fabrics include woven fabrics, knitted fabrics (weft knitted fabrics, warp knitted fabrics), and nonwoven fabrics. Of these, woven fabrics such as plain weave, twill weave, and satin weave, and woven or knitted fabrics with intersection angles exceeding 90° but not exceeding 120° are preferred. Woven fabrics commonly used as cover fabrics for transmission belts in general industrial and agricultural machinery [plain weave fabrics with right-angle intersections, and plain weave fabrics with intersection angles exceeding 90° but not exceeding 120° (wide-angle canvas)] are particularly preferred. Furthermore, in applications where durability is required, the fabric may be wide-angle canvas.

[0141] Examples of fibers constituting the fabric include the fibers exemplified as constituting the first short fibers of the first rubber layer. The fibers may be single yarns using only one type of fiber, or composite yarns (such as blended yarns) combining two or more types of fibers. Among the fibers, polyalkylene arylate short fibers and cellulose short fibers are preferred.

[0142] The reinforcing fabric may be treated with adhesive, for example, with RFL solution (such as immersion treatment), or with friction treatment, where adhesive rubber is rubbed into the stretchable rubber layer and / or the fabric, or the adhesive rubber and the fabric may be laminated and then laminated or embedded in the compression rubber layer in a laminated form.

[0143] The average thickness of the reinforcing fabric is, for example, 0.1 to 1.5 mm, preferably 0.2 to 1 mm, and more preferably 0.3 to 0.7 mm.

[0144] [Manufacturing method for cog-type V-belts] The method for manufacturing a cogged V-belt according to the present invention is not particularly limited, and conventional methods can be used for the lamination process of each layer (manufacturing method of the belt sleeve) depending on the type of belt. Below, two representative manufacturing methods for raw-edge cogged V-belts will be described.

[0145] (1st manufacturing method) When manufacturing a low-edge cogged V-belt in which a cog portion is formed at least on the inner circumference of the belt, a cylindrical mold such as a cogged mold can be used, in which a surface with irregularities corresponding to the cog shape is engraved on the outer surface of the cylinder.

[0146] First, a laminate of an uncrosslinked sheet for the first rubber layer and an uncrosslinked sheet for the second rubber layer is placed with the uncrosslinked sheet for the first rubber layer facing downwards, in contact with a flat cog mold having alternating teeth and grooves corresponding to the inner circumference cog portion. The mold is then pressed at a temperature of 60-120°C (especially 80-100°C) to create a cog pad (a pad that is not completely crosslinked, but in a semi-crosslinked state) with the inner circumference cog portion molded into it. Then, both ends of this cog pad are cut vertically at appropriate points (especially the tops of the cog peaks) to obtain the required length.

[0147] Next, an inner mold having teeth and grooves arranged alternately to correspond to the inner cog portion is placed over the outer circumference of the cylindrical mold (cog mold), and the cog pad is wrapped around it by engaging with the teeth and grooves of the inner mold and joined at both ends (especially the tops of the cog peaks). An uncrosslinked sheet for the first adhesive rubber layer (lower adhesive rubber) is wrapped around the outer circumference of the cog pad and laminated, and then a core wire (twisted cord) that will become the core body is spun in a spiral shape, and an uncrosslinked sheet for the second adhesive rubber layer (upper adhesive rubber), which is the same as the uncrosslinked sheet for the first adhesive rubber layer, an uncrosslinked sheet for the stretch rubber layer, and a reinforcing fabric precursor for the outer circumference are wrapped around its outer circumference in this order to obtain an uncrosslinked laminate.

[0148] Subsequently, the mold with the laminate attached is placed in a known crosslinking device (such as a vulcanizing can) with a jacket covering the outer circumference of the laminate, and crosslinking is performed at a temperature of approximately 120-200°C (especially 150-180°C). This causes the rubber components of each rubber layer to crosslink and the laminate to bond and integrate, thereby preparing a belt sleeve (crosslinked sleeve) with a cog portion formed on the inner circumference. The obtained crosslinked sleeve is cut to a predetermined width using a cutter or the like, and the sides are further cut into a V-shape to obtain a predetermined V-angle, thereby forming a low-edge cogged V-belt with a cog portion formed on the inner circumference.

[0149] Furthermore, an uncrosslinked laminate can be obtained without using an uncrosslinked sheet for the second adhesive rubber layer. Also, when the adhesive rubber layer is formed with multiple uncrosslinked sheets for the adhesive rubber layer, the core wire can be spun in relation to the lamination order of the multiple adhesive rubber layer sheets, depending on the embedding position in the adhesive rubber layer.

[0150] Furthermore, as a means of forming the cog portion, as described in Japanese Patent Application Publication No. 2018-35939, a belt sleeve (bridged sleeve) without a cog portion formed on its inner circumferential surface may be prepared using a flat cylindrical mold without engraved uneven surfaces corresponding to the cog shape, and then the cog portion may be formed by removing the cog portion from the bridged sleeve using a cutting tool or a water jet machine.

[0151] (Second manufacturing method) Using a flat cylindrical mold without any grooves or protrusions corresponding to the cog shape as the mold, a reinforcing fabric precursor, an uncrosslinked sheet for the stretchable rubber layer, an uncrosslinked sheet for the second adhesive rubber layer (upper adhesive rubber), a core wire, an uncrosslinked sheet for the first adhesive rubber layer (lower adhesive rubber), and a cog pad are wound around the mold in the reverse order of the first manufacturing method to obtain an uncrosslinked laminate.

[0152] A cylindrical rubber mold with an uneven surface corresponding to the cog shape formed on its inner surface is placed over the outer circumference of the laminate. Then, with the jacket placed over the outer circumference of the rubber mold, it is placed in a vulcanizing apparatus and cross-linked molding is performed at a temperature of approximately 120-200°C (especially 150-180°C) to prepare a belt sleeve (cross-linked sleeve) with a cog shape formed on its outer circumference. The obtained cross-linked sleeve is cut to a predetermined width using a cutter or the like, and then the sides are cut into a V shape to obtain a predetermined V angle. Finally, the outer and inner circumferences are reversed to obtain a raw edge cogged V belt with a cog portion formed on the inner circumference. [Examples]

[0153] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. Details of the materials used in the examples, the method for producing the uncrosslinked rubber sheet, and the methods for measuring or evaluating each physical property are shown below.

[0154] [Materials used] EPDM: DowDuPont "NORDEL® IP4640", ethylene content 55% by mass, ethylidene norbornene content 4.9% by mass Aramid short fiber: "Twaron®" manufactured by Teijin Limited, modulus 88 cN, fineness 2.2 dtex, fiber length 3 mm Nylon staple fibers: "Leona" (registered trademark) manufactured by Asahi Kasei Corporation, average fiber diameter 27 μm, average fiber length 3 mm Naphthenic oil: "Diana® Process Oil NS-90S" manufactured by Idemitsu Kosan Co., Ltd. Silica: Manufactured by Evonik Japan Co., Ltd., "ULTRASIL® VN3", BET specific surface area 175 m² 2 / g Carbon Black HAF: "Seast (registered trademark) 3" manufactured by Tokai Carbon Co., Ltd. Zinc Oxide: "Zinc Oxide 3 Types" manufactured by Seido Chemical Industry Co., Ltd. Anti-aging agent: "Nocrac® AD-F" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Crosslinking accelerator DM: Dibenzothiadyl disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar (registered trademark) DM" Crosslinking accelerator TT: Tetramethylthiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar (registered trademark) TT" Crosslinking accelerator CZ: N-cyclohexyl-2-benzothiadylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar® CZ" Sulfur: "Sulfur" manufactured by Migen Chemical Co., Ltd.

[0155] [Heart wire] Two strands of aramid fiber multifilament yarn (fineness 1,680 dtex) were held together and under-twisted. Three of these were then combined and over-twisted in the opposite direction to the under-twist to create a multi-twist cord with a total fineness of 10,080 dtex (average wire diameter 1.81 mm). This cord was then further treated with adhesive to create a processed cord.

[0156] [Preparation of uncrosslinked rubber sheets for rubber layers] The rubber compositions for forming the compression rubber layer, the stretch rubber layer, and the adhesive rubber layer were prepared according to the mixing ratios shown in Table 1. Each rubber composition for forming each layer was mixed using a Banbury mixer, and the resulting mixed rubber was passed through a calender roll to produce a rolled rubber sheet (uncrosslinked rubber sheet). In this specification, each rubber composition is denoted by R1 to R7.

[0157] [Table 1]

[0158] [Reinforcement fabric] Woven fabric made from a blend of polyester and cotton fibers (polyester fiber / cotton = 50 / 50 by mass ratio) (120° wide-angle weave, 20 count warp and 20 count weft, warp and weft yarn density 75 threads / 50mm, basis weight 280g / m²) 2 A reinforcing fabric precursor was prepared by coating the fabric with the rubber composition R7, which had been pre-mixed, by passing it through a calender roll simultaneously, thereby laminating and adhering the rubber composition R7 to the woven fabric.

[0159] [Flexural modulus] An uncrosslinked rubber composition having the composition shown in Table 1 was press-heated at a temperature of 160°C and a pressure of 2 MPa for 20 minutes to produce a crosslinked rubber molded body (60 mm × 25 mm × 6.5 mm thick). The short fibers were oriented perpendicular to the length direction of the crosslinked rubber molded body. As shown in Figure 5, this crosslinked rubber molded body 21 was supported on a pair of rotatable rolls (6 mm in diameter) 22a and 22b spaced 20 mm apart, and a metal pressing member 23 was placed on the center of the upper surface of the crosslinked rubber molded body in the width direction (parallel to the orientation direction of the short fibers). The tip of the pressing member 23 has a semicircular cross-section with a diameter of 10 mm, and the crosslinked rubber molded body 21 can be smoothly pressed with its tip. In addition, when pressed, a frictional force acts between the lower surface of the crosslinked rubber molded body 21 and the rolls 22a and 22b due to the compression deformation of the crosslinked rubber molded body 21, but the effect of friction is reduced by making the rolls 22a and 22b rotatable. The initial position was defined as the tip of the pressing member 23 in contact with the upper surface of the cross-linked rubber molded body 21, but without pressing down. From this position, the pressing member 23 was pressed downwards at a speed of 100 mm / min against the upper surface of the cross-linked rubber molded body 21, and the flexural modulus at a bending strain of 8% was measured. The measurement temperature was set to 120°C, assuming the belt temperature during operation. A smaller flexural modulus in the direction parallel to the short fibers (8% flexural modulus) indicates better belt flexibility, with 1.5 to 3 MPa being considered good.

[0160] [Area ratio of the first rubber layer] The area ratio of the first rubber layer refers to the ratio of the total area of ​​the compression rubber layer in a cross-sectional view along the thickness direction in the circumferential direction of the belt, and the thickness of the uncrosslinked rubber sheet for the first rubber layer is considered to be the area ratio of the first rubber layer to the total thickness of the uncrosslinked rubber sheet for the first rubber layer and the uncrosslinked rubber sheet for the second rubber layer.

[0161] [Transmission performance (slip ratio) test] The test was conducted by motor-driven a continuously variable transmission. Figure 6 shows the layout of the test machine, which is a two-axis running test machine consisting of a drive (Dr.) pulley connected to the drive shaft and a driven (Dn.) pulley connected to the driven shaft. The driven pulley applies a clamping force to the belt using a spring, while the groove width of the drive pulley is fixed. The pitch diameter of the drive pulley, the pitch diameter of the driven pulley, and the distance between the shafts were adjusted to the values ​​shown in Table 2 so that the no-load gear ratio (the value obtained by dividing the pitch diameter of the driven pulley by the pitch diameter of the drive pulley) is 0.58 even if the overall thickness of the belt differs. Digital tachometers and torque meters were mounted on the drive shaft and driven shaft. The rotational speed of the drive pulley was recorded at 1398 rpm, the rotational speed of the driven pulley under no load was recorded at 2419 rpm, and the load on the driven pulley was varied between 80 and 180 kW while recording the rotational speed and torque of the drive shaft and driven shaft. The ambient temperature was set to 25°C.

[0162] [Table 2]

[0163] As shown in the following formula, the slip ratio S is determined by the rotational speed ratio i0 when driven without load and the rotational speed ratio i when driven with load. In this embodiment, it was determined from the rotational speed ratio when the rotational speed of the drive shaft was 1398 rpm and the load on the driven pulley was 180 kW.

[0164] S(%) = (1 - i / i0) × 100

[0165] The slip ratio is a value that represents transmission loss, and a smaller slip ratio indicates better transmission power and better fuel efficiency. Also, since insufficient surface area of ​​the friction transmission surface reduces transmission power and increases the slip ratio, in this evaluation, the slip ratio during driving was used as an indicator of the superiority of transmission power (transmission performance) based on the surface area of ​​the friction transmission surface, and a slip ratio of 1.6% or less was considered an acceptable level for transmission performance.

[0166] (Judgment criteria) a: Slip ratio is 1.0% or less (Pass) b: Slip ratio is greater than 1.0% but less than or equal to 1.3% (Pass) c: Slip ratio is greater than 1.3% but less than or equal to 1.6% (Pass) d: Slip ratio exceeds 1.6% (failure)

[0167] [Deformation resistance test] The deformation resistance test was conducted using a two-axis running test machine with a layout consisting of a drive (Dr.) pulley and a driven (Dn.) pulley, as shown in Figure 7. The pitch diameter of the drive pulley, the pitch diameter of the driven pulley, and the distance between the axes were adjusted to the values ​​shown in Table 3 so that the gear ratio remained constant even if the overall thickness of the belt differed. A raw edge cogged V-belt was mounted on these two pulleys, and the belt was run for 30 minutes at an ambient temperature of 25°C with an axle load of 15000N, a drive pulley rotation speed of 1398rpm, and a driven pulley rotation speed of 2419rpm under no load. A high load of 400kW was applied to the driven pulley for a short time, and the surface temperature of the belt during running was measured with a non-contact thermometer and judged according to the following criteria. The deformation referred to is buckling deformation called dishing during belt operation. Since a large buckling deformation causes the belt temperature to rise, the belt surface temperature was used as an indicator of deformation resistance, and a belt surface temperature of 165°C or lower was considered an acceptable level for deformation resistance.

[0168] [Table 3]

[0169] (Judgment criteria) a: Belt temperature 125℃ or less (pass) b: Belt temperature between 125°C and 145°C (pass) c: Belt temperature between 145°C and 165°C (pass) d: Belt temperature exceeds 165℃ (failed)

[0170] [Cog Valley Crack Resistance Test] In the deformation resistance test method described above, a load of 160 kW was applied to the driven pulley, and the belt was run for 150 hours at an ambient temperature of 25°C. The sides of the belt were then visually inspected to check for delamination between the adhesive rubber layer and the core wire, and for cracks in the cog valleys. The results were then judged according to the following criteria.

[0171] (Judgment criteria) a: If no cracks or peeling are observed at all (Pass) b: Slight cracks or peeling may be observed (Pass) c: If minor cracks or peeling are observed (to the extent that it does not affect the belt's performance), it is considered acceptable. d: If cracks, delamination, or other damage occurs to a degree that impairs the belt's performance (failure)

[0172] [Overall assessment] The criteria for overall evaluation (ranking) of a cog-type V-belt capable of solving this problem were determined based on the results of the evaluations of the three evaluation items (transmission performance, deformation resistance, and cog valley crack resistance) as shown in Table 4, with a rank of C or higher being considered acceptable.

[0173] [Table 4]

[0174] [Manufacturing of V-belts with cogs] (Example 1) Using the above-mentioned core wire and reinforcing fabric precursor, an uncrosslinked rubber sheet for the first rubber layer (R4, sheet thickness 7.2 mm), an uncrosslinked rubber sheet for the second rubber layer (R1, sheet thickness 4.8 mm), a crosslinked rubber sheet for the stretch rubber layer (R1, sheet thickness 1.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R7, sheet thickness 1.0 mm), a raw edge cogged V-belt of Example 1 was manufactured by the manufacturing method described as (Second Manufacturing Method) in the above-mentioned [Modes for Carrying Out the Invention]. Crosslinking was performed at 180°C and 0.9 MPa for 30 minutes to produce a crosslinked belt sleeve with a predetermined cog portion formed on the outer circumference. The obtained crosslinked belt sleeve was cut to a width of 50.8 mm with a cutter, and the sides were further cut into a V shape at a V angle of 28°. Then, the inner and outer circumferences were reversed to obtain a low-edge cogged V-belt (size: top width 50.8 mm, thickness 21.0 mm, belt length 2113 mm) with cogs formed on the inner circumference. The thickness of the compression rubber layer was 16.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.6 mm (total thickness 21.0 mm).

[0175] (Examples 2-9 and 14-18) A raw edge cogged V-belt was manufactured in the same manner as in Example 1, except that the uneven shape of the cylindrical rubber matrix corresponding to the cog shape and the thickness of each uncrosslinked rubber sheet were changed. In Examples 14 to 18, the thickness of each layer differed from that of Example 1. Specifically, in Example 14, the thickness of the compression rubber layer was 17.8 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 0.4 mm. In Example 15, the thickness of the compression rubber layer was 17.7 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 0.5 mm. In Example 16, the thickness of the compression rubber layer was 17.1 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.1 mm. In Example 17, the thickness of the compression rubber layer was 15.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 2.6 mm. Furthermore, in Example 18, the thickness of the compression rubber layer was 15.9 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 2.3 mm.

[0176] (Example 10) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R2.

[0177] (Example 11) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R3.

[0178] (Example 12) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R5.

[0179] (Example 13) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6.

[0180] (Examples 19 and 21) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6, and the uneven shape of the cylindrical rubber matrix corresponding to the cog shape was changed.

[0181] (Examples 20 and 22) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was set to R2, and the uneven shape of the cylindrical rubber matrix corresponding to the cog shape was changed.

[0182] (Example 23) A low-edge cogged V-belt (size: top width 44.5 mm, thickness 18.0 mm, belt length 2168 mm) was obtained in the same manner as in Example 1, except that an uncrosslinked rubber sheet for the first rubber layer (R4, sheet thickness 6.0 mm), an uncrosslinked rubber sheet for the second rubber layer (R1, sheet thickness 4.0 mm), a crosslinked rubber sheet for the stretch rubber layer (R1, sheet thickness 1.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R7, sheet thickness 1.0 mm) were used. The thickness of the compression rubber layer was 13.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.6 mm (total thickness 18.0 mm).

[0183] (Examples 24-31 and 36-39) A raw edge cogged V-belt was manufactured in the same manner as in Example 23, except that the uneven shape of the cylindrical rubber matrix corresponding to the cog shape and the thickness of each uncrosslinked rubber sheet were changed. Note that the thickness of each layer differs between Example 23 (Example 25) and Examples 36-39. Specifically, in Example 23, the thickness of the compression rubber layer was 13.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.6 mm. In Example 36, the thickness of the compression rubber layer was 14.8 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 0.4 mm. In Example 37, the thickness of the compression rubber layer was 14.7 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 0.5 mm. In Example 38, the thickness of the compression rubber layer was 13.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.6 mm. Furthermore, in Example 39, the thickness of the compression rubber layer was 14.2 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.0 mm.

[0184] (Example 32) A low-edge cogged V-belt was prepared in the same manner as in Example 25, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R2.

[0185] (Example 33) A low-edge cogged V-belt was prepared in the same manner as in Example 25, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R3.

[0186] (Example 34) A low-edge cogged V-belt was prepared in the same manner as in Example 25, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R5.

[0187] (Example 35) A low-edge cogged V-belt was prepared in the same manner as in Example 25, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6.

[0188] (Example 40) A low-edge cogged V-belt (size: top width 50.8 mm, thickness 26.0 mm, belt length 2118 mm) was obtained in the same manner as in Example 1, except that an uncrosslinked rubber sheet for the first rubber layer (R4, sheet thickness 7.8 mm), an uncrosslinked rubber sheet for the second rubber layer (R1, sheet thickness 5.2 mm), a crosslinked rubber sheet for the stretch rubber layer (R1, sheet thickness 2.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R7, sheet thickness 1.0 mm) were used. The thickness of the compression rubber layer was 20.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 2.6 mm (total thickness 26.0 mm).

[0189] (Examples 41-48 and 53-56) A low-edge cogged V-belt was manufactured in the same manner as in Example 40, except that the uneven shape of the cylindrical rubber matrix corresponding to the cog shape and the thickness of each uncrosslinked rubber sheet were changed. Note that the thickness of each layer differs between Example 40 (Example 42) and Examples 53-56. Specifically, in Example 40, the thickness of the compression rubber layer was 20.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 2.6 mm. In Example 53, the thickness of the compression rubber layer was 21.2 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 2.0 mm. In Example 54, the thickness of the compression rubber layer was 21.6 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 1.6 mm. In Example 55, the thickness of the compression rubber layer was 19.2 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 4.0 mm. Furthermore, in Example 56, the thickness of the compression rubber layer was 20.4 mm, the thickness of the adhesive rubber layer was 2.8 mm, and the thickness of the stretch rubber layer was 2.8 mm.

[0190] (Example 49) A low-edge cogged V-belt was prepared in the same manner as in Example 42, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R2.

[0191] (Example 50) A low-edge cogged V-belt was prepared in the same manner as in Example 42, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R3.

[0192] (Example 51) A low-edge cogged V-belt was prepared in the same manner as in Example 42, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R5.

[0193] (Example 52) A low-edge cogged V-belt was prepared in the same manner as in Example 42, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6.

[0194] (Comparative Example 1) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the shape of the irregularities in the cylindrical rubber matrix corresponding to the cog shape was changed.

[0195] (Comparative Example 2) A low-edge cogged V-belt was prepared in the same manner as in Comparative Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R3.

[0196] (Comparative Example 3) A low-edge cogged V-belt was prepared in the same manner as in Comparative Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R5.

[0197] The evaluation results of the belts obtained in the examples and comparative examples are shown in Tables 5 to 17.

[0198] [Table 5]

[0199] [Table 6]

[0200] [Table 7]

[0201] [Table 8]

[0202] [Table 9]

[0203] [Table 10]

[0204] [Table 11]

[0205] [Table 12]

[0206] [Table 13]

[0207] [Table 14]

[0208] [Table 15]

[0209] [Table 16]

[0210] [Table 17]

[0211] <Verification results for Tables 5-9 (belts with a total thickness of 21mm)> (Comparative Examples 1-3) Comparative Example 1 is an example in which multiple consecutive arcs are not combined at the bottom of the cog valley, that is, an example in which only the first arc is provided and no second arc is given. Comparative Examples 2 and 3 are examples in which the flexural modulus of the first rubber layer is varied compared to Comparative Example 1. In all cases, the transmission performance and deformation resistance were at an acceptable level (a or b rating), but the cog valley crack resistance was unacceptable (d rating), possibly due to insufficient stress distribution around the cog valley, resulting in an overall unacceptable rating (D rank).

[0212] (Examples 1-5) In contrast, the belt in the embodiment is an example in which multiple consecutive arcs are combined at the bottom of the cog valley, that is, an example in which a first arc and a second arc are provided. Embodiments 1 to 5 are examples in which the radius of curvature R1 of the first arc is varied, while the second arc R2 = 1.6 mm (R2 / H1 = 13%) is constant. In Example 1, R1 was varied to 5.0 mm (R1 / H1=40%), in Example 2 to 5.7 mm (R1 / H1=45%), in Example 3 to 6.4 mm (R1 / H1=51%), in Example 4 to 6.9 mm (R1 / H1=55%), and in Example 5 to 7.6 mm (R1 / H1=60%). The results showed that as the ratio of the radius of curvature R1 of the first arc to the cog height H1 (R1 / H1) increased, resistance to cog valley cracks improved, while transmission performance and deformation resistance tended to decrease. In particular, the case of R1=6.4 mm (R1 / H1=51%) (Example 3) showed excellent balance, with transmission performance, deformation resistance, and cog valley crack resistance all receiving an "a" rating (overall A rank). In Examples 1, 2, 4, and 5, the overall rating was at an acceptable level (B and C ranks).

[0213] (Examples 6-9) Examples 6-9 show variations in the radius of curvature R2 of the second arc, relative to a constant first arc R1 = 6.4 mm (R1 / H1 = 51%). In Example 6, R2 = 0.6 mm (R2 / H1 = 5%); in Example 7, R2 = 1.3 mm (R2 / H1 = 10%); in Example 3, R2 = 1.6 mm (R2 / H1 = 13%); in Example 8, R2 = 2.5 mm (R2 / H1 = 20%); and in Example 9, R2 = 3.2 mm (R2 / H1 = 25%). The results showed that as the ratio of the radius of curvature R2 of the second arc to the cog height H1 (R2 / H1) increased, resistance to cog valley cracks improved, while transmission performance and deformation resistance tended to decrease. In particular, the case with R2=1.6mm (R2 / H1=13%) (Example 3) showed excellent balance, with transmission performance, deformation resistance, and cog valley crack resistance all receiving an "a" rating (overall A rank). Even in Examples 6-9, the overall rating was at an acceptable level (B and C ranks).

[0214] From the results of Examples 1 to 9 above, the effectiveness of combining multiple consecutive arcs (providing a first and second arc) at the bottom of the cog valley was confirmed. Based on these results, it can be said that the preferred range for the ratio of R1 to the cog height H1 is R1 / H1 = 45-55% and R2 / H1 = 10-20%.

[0215] (Examples 10-13) In Examples 1 to 9, Example 3 [First arc R1 = 6.4 mm (R1 / H1 = 51%), Second arc R2 = 1.6 mm (R2 / H1 = 13%)] showed the best balance of transmission performance, deformation resistance, and cog valley crack resistance. Examples 10 to 13, on the other hand, are examples of belts in which the elastic modulus (flexural modulus) of the first rubber layer was varied. The variation in elastic modulus was adjusted by changing the proportion of short fibers contained in the first rubber layer to 5 parts by mass (Example 10), 15 parts by mass (Example 11), 25 parts by mass (Example 3), 35 parts by mass (Example 12), and 40 parts by mass (Example 13). When the flexural modulus of the first rubber layer was varied to 1.4 MPa (Example 10), 1.9 MPa (Example 11), 2.2 MPa (Example 3), 2.7 MPa (Example 12), and 3.0 MPa (Example 13), it was observed that as the flexural modulus of the first rubber layer increased, the transmission performance and deformation resistance improved, while conversely, the resistance to cog valley cracking tended to decrease. In particular, when the flexural modulus of the first rubber layer was around 2.2 MPa (2.0~2.5 MPa), the transmission performance, deformation resistance, and cog valley cracking resistance all received an "a" rating (overall A rank), showing excellent balance. Even when the flexural modulus of the first rubber layer was at other levels, the overall rating was at an acceptable level (B, C rank). From these results, it can be said that the optimal range for the elastic modulus of the first rubber layer is 1.4~3.0 MPa (especially 1.9~2.7 MPa) in terms of flexural modulus (parallel to short fibers). Furthermore, the proportion of short fibers contained in the first rubber layer is preferably in the range of 5 to 40 parts by mass (particularly 15 to 35 parts by mass).

[0216] (Examples 14-18) In Examples 1-9, Example 3 [First arc R1 = 6.4 mm (R1 / H1 = 51%), Second arc R2 = 1.6 mm (R2 / H1 = 13%), First rubber layer flexural modulus 2.2 MPa] showed the best balance of transmission performance, deformation resistance, and cog valley crack resistance. Examples 14-18, on the other hand, are examples of belts with varying core valley thickness H2. The variation in core valley thickness H2 was adjusted by varying the cog height H1. When the ratio of core valley thickness H2 to belt thickness H (H2 / H) was varied to 39% (Example 14), 34% (Example 15), 26% (Example 16), 14% (Example 17), and 11% (Example 18), it was observed that as H2 / H decreased, transmission performance and deformation resistance improved, while cog valley crack resistance tended to decrease. In particular, when the ratio of core valley thickness H2 (H2 / H) was around 26%, the transmission performance, deformation resistance, and cog valley crack resistance all received an "a" rating (overall A rank), indicating excellent balance. Even when the ratio of core valley thickness H2 (H2 / H) was at other levels, the overall rating was at an acceptable level (B, C rank). Therefore, these results suggest that the ratio of core valley thickness H2 to belt thickness H (H2 / H) is in the range of 14-34% (especially 20-30%), which is the optimal range.

[0217] (Examples 19-22) Examples 19 and 20 are examples that examine the relationship (combination) between the radius of curvature R1 of the first arc, the radius of curvature R2 of the second arc, the core valley thickness H2, and the elastic modulus of the first rubber layer (the proportion of short fibers contained in the first rubber layer).

[0218] Cog valley crack resistance is greatly influenced by the decrease in flexibility, and the decrease in flexibility reaches its limit when the following conditions are met: small radii of curvature R1 and R2, large core valley thickness H2, and high elastic modulus of the first rubber layer. Example 19 combines the following conditions: minimum radii of curvature R1 = 5.0 mm (R1 / H1 = 45%) and R2 = 1.1 mm (R2 / H1 = 10%), close to the maximum core valley thickness H2 = 7.0 mm (H2 / H = 33%), and maximum elastic modulus of the first rubber layer at 3.0 MPa, which represents the limiting conditions described above. Even under these conditions, the transmission performance and deformation resistance were good (rated a), and the cog valley crack resistance was rated c (pass), confirming that the overall rating is at a passing level (rank C).

[0219] Conversely, transmission performance and deformation resistance are greatly affected by insufficient surface area and rigidity of the friction transmission surface, and the limits are reached when conditions are combined with large radii of curvature R1 and R2, small core valley thickness H2, and low elastic modulus of the first rubber layer. Example 20 is an example that combines the following conditions: radii of curvature R1 = 7.7 mm (R1 / H1 = 55%) and R2 = 2.8 mm (R2 / H1 = 20%), both of which are the minimum, core valley thickness H2 = 4.0 mm (H2 / H = 19%), which is close to the minimum, and the elastic modulus of the first rubber layer is 1.4 MPa, which is the minimum, and thus represents the limit conditions described above. Even under these conditions, resistance to cog valley cracking was good (rating a), transmission performance and deformation resistance were rated c (pass), and it was confirmed that the overall rating was at a passing level (rank C).

[0220] Furthermore, Examples 21 and 22 are presented as examples of other combinations relating to the radius of curvature R1 of the first arc, the radius of curvature R2 of the second arc, the core valley thickness H2, and the elastic modulus of the first rubber layer, and all of these also met the passing standard (B rank) in the overall evaluation.

[0221] <Verification results for belts with a total thickness of 18mm (Tables 10-13)> (Examples 23-27) The variation in the radius of curvature R1 of the first arc relative to a constant second arc R2, which was verified in Examples 1-5 where the total belt thickness H was 21.0 mm, was also verified for a belt with a total belt thickness H of 18.0 mm.

[0222] In Examples 23-27, the ratio of the radius of curvature R1 of the first arc to the cog height H1 (R1 / H1) was varied to 40% (Example 23), 45% (Example 24), 50% (Example 25), 55% (Example 26), and 60% (Example 27). As the ratio of the radius of curvature R1 to the cog height H1 (R1 / H1) increased, resistance to cog valley cracks improved, while transmission performance and deformation resistance tended to decrease. In particular, when the ratio to cog height H1 (R1 / H1) was 50% (Example 25), transmission performance, deformation resistance, and resistance to cog valley cracks all received an "a" rating (overall A rank), showing excellent balance. In Examples 23, 24, 26, and 27, the overall rating was at an acceptable level (B and C ranks).

[0223] (Examples 28-31) The variation in the radius of curvature R2 of the second arc relative to a constant first arc R1, which was verified in Examples 6-9 where the overall belt thickness H was 21.0 mm, was also verified for a belt with an overall belt thickness H of 18.0 mm.

[0224] In Examples 28-31, the ratio of the radius of curvature R2 of the second arc to the cog height H1 (R2 / H1) was varied to 5% (Example 28), 10% (Example 29), 15% (Example 25), 20% (Example 30), and 25% (Example 31). As the ratio of the radius of curvature R2 to the cog height H1 (R2 / H1) increased, resistance to cog valley cracks improved, while transmission performance and deformation resistance tended to decrease. In particular, when the ratio to cog height H1 (R2 / H1) was 15% (Example 25), transmission performance, deformation resistance, and resistance to cog valley cracks all received an "a" rating (overall A rank), indicating excellent balance. In Examples 28-31, the overall rating was at an acceptable level (B and C ranks).

[0225] From the results of Examples 23 to 31 above, the effectiveness of combining multiple consecutive arcs (providing a first and second arc) at the bottom of the cog valley was confirmed. From these results, it can be said that the preferred range for the ratio of R1 to the cog height H1 is R1 / H1 = 45-55% and R2 / H1 = 10-20%.

[0226] (Examples 32-35) The variation in the elastic modulus (flexural modulus) of the first rubber layer, which was verified in Examples 10-13 where the overall belt thickness H was 21.0 mm, was also verified for a belt with an overall belt thickness H of 18.0 mm.

[0227] In Examples 23-31, Example 25 [First arc R1 = 5.7 mm (R1 / H1 = 50%), Second arc R2 = 1.7 mm (R2 / H1 = 15%)] showed the best balance of transmission performance, deformation resistance, and cog valley crack resistance. In contrast, Examples 32-35 are examples of belts in which the elastic modulus (flexural modulus) of the first rubber layer was varied. Similar to Examples 10-13, as the flexural modulus of the first rubber layer increased, transmission performance and deformation resistance improved, while cog valley crack resistance tended to decrease. In particular, the balance of transmission performance, deformation resistance, and cog valley crack resistance was excellent when the flexural modulus of the first rubber layer was 2.0-2.5 MPa, and the range of the elastic modulus of the first rubber layer in terms of flexural modulus (parallel to short fibers) was 1.4-3.0 MPa (especially 1.9-2.7 MPa), which was also similar to Examples 10-13.

[0228] (Examples 36-39) The variation of the core thickness H2, which was verified in Examples 14-18 where the overall belt thickness H was 21.0 mm, was also verified for a belt with an overall belt thickness H of 18.0 mm.

[0229] Configuration of Example 25 [First arc R1 = 5.7 mm (R1 / H1 = 50%), second arc R2 = 1.7 mm (R2 / H1 = 15%), flexural modulus of the first rubber layer 2.2 MPa]. For Examples 36 to 39, they are examples of belts with the valley thickness H2 being a variable. As a result of varying the ratio of the valley thickness H2 to the belt thickness H (H2 / H) to 40% (Example 36), 34% (Example 37), 22% (Example 25), 11% (Example 38), and 9% (Example 39), particularly when the ratio of the valley thickness H2 (H2 / H) was about 22%, the transmission performance, deformation resistance, and cog valley crack resistance were all judged as a (A rank in the comprehensive judgment) and were excellent in balance. Even when the ratio of the valley thickness H2 (H2 / H) was at other levels, the comprehensive judgment was at the passing level (B, C ranks). From these results, it can be said that the ratio of the valley thickness H2 to the belt thickness H (H2 / H) is preferably in the range of 11 to 38% (particularly 17 to 28%).

[0230] <Verification results of Tables 14 to 17 (belt with an overall thickness of 26 mm)> (Examples 40 to 44) The variation in the radius of curvature R1 of the first arc verified in Examples 1 to 5 with a belt overall thickness H of 21.0 mm and Examples 23 to 27 with H of 18.0 mm was also verified for a belt with a belt overall thickness H of 26.0 mm.

[0231] In Examples 40 to 44, as a result of varying the ratio of the radius of curvature R1 of the first arc to the cog height H1 (R1 / H1) to 40% (Example 40), 45% (Example 41), 50% (Example 42), 55% (Example 43), and 60% (Example 44), the same tendency was observed as in the case of belts with an overall thickness H of 21.0 mm (Examples 1 to 5) or 18.0 mm (Examples 23 to 27).

[0232] (Examples 45 to 48) The variation in the radius of curvature R2 of the second arc verified in Examples 6 to 9 with a belt overall thickness H of 21.0 mm and Examples 28 to 31 with H of 18.0 mm was also verified for a belt with a belt overall thickness H of 26.0 mm.

[0233] In Examples 45-48, the ratio of the radius of curvature R2 of the second arc to the cog height H1 (R2 / H1) was varied to 5% (Example 45), 10% (Example 46), 15% (Example 42), 20% (Example 47), and 25% (Example 48). The results showed a similar trend to that observed in belts with an overall thickness H of 21.0 mm (Examples 3 and 6-9) and 18.0 mm (Examples 25 and 28-31).

[0234] From the results of the above examples 40 to 48, the effectiveness of combining multiple consecutive arcs (providing a first and second arc) at the bottom of the cog valley was confirmed. From these results, it can be said that the preferred range for the ratio of R1 to the cog height H1 is R1 / H1 = 45-55% and R2 / H1 = 10-20%.

[0235] (Examples 49-52) The variation in the elastic modulus (flexural modulus) of the first rubber layer, which was verified in Examples 10-13 with an overall belt thickness H of 21.0 mm and Examples 32-35 with an H of 18.0 mm, was also verified for a belt with an overall belt thickness H of 26.0 mm.

[0236] Based on the configuration of Example 42, Examples 49 to 52 are examples of belts in which the elastic modulus (flexural modulus) of the first rubber layer is varied. Similar trends were observed for belts with an overall thickness H of 21.0 mm (Examples 3 and 10-13) and 18.0 mm (Examples 25 and 32-35). Specifically, as the flexural modulus of the first rubber layer increased, the transmission performance and deformation resistance improved, while cog valley crack resistance decreased. In particular, when the flexural modulus of the first rubber layer was 2.0 to 2.5 MPa, the balance between transmission performance, deformation resistance, and cog valley crack resistance was excellent. The elastic modulus of the first rubber layer was also similarly favorable in the range of 1.4 to 3.0 MPa (particularly 1.9 to 2.7 MPa) in terms of flexural modulus (parallel to short fibers).

[0237] (Examples 53-56) The variation of the core thickness H2, which was verified in Examples 14-18 with an overall belt thickness H of 21.0 mm and Examples 36-39 with an H of 18.0 mm, was also verified for a belt with an overall belt thickness H of 26.0 mm.

[0238] Based on the configuration of Example 42, Examples 53 to 56 are examples of belts with varying core valley thickness H2. In particular, when the core valley thickness H2 ratio (H2 / H) was around 33%, the transmission performance, deformation resistance, and cog valley crack resistance all received an A rating (overall A rank), showing excellent balance. Even when the core valley thickness H2 ratio (H2 / H) was at other levels, the overall rating was at an acceptable level (B, C rank). From these results, it can be said that the ratio of core valley thickness H2 to belt thickness H (H2 / H) is in the range of 21-41% (especially 25-35%).

[0239] From the above results, it was found that, across a wide range of thicknesses of cog-equipped V-belts, the configuration of the present invention can suppress crack formation in the cog valleys by easing the stress at the bottom of the cog valleys (including the deepest part of the cog valleys), where stress tends to concentrate due to bending deformation, while maintaining lateral pressure resistance (deformation resistance) and transmission performance. [Industrial applicability]

[0240] The cog-equipped V-belt of the present invention can be used as a V-belt (gear belt or CVT belt) in a transmission (continuously variable transmission) in which the gear ratio changes steplessly during belt operation, for example, as a CVT belt used in continuously variable transmissions of motorcycles, ATVs (quad bikes), snowmobiles, agricultural machinery, etc. In particular, the cog-equipped V-belt of the present invention is suitable as a CVT belt for heavy-duty agricultural machinery used in Europe and the United States, such as tillers, binders, combines, vegetable harvesters, threshing machines, bean cutters, corn crushers, potato harvesters, and beet harvesters, because it can ensure resistance to cog valley cracks even when subjected to large lateral pressure from the pulley. [Explanation of symbols]

[0241] 1… Raw edge cogged V-belt 1a... Cog Mountain 1b... Cog Valley 2…Compressed rubber layer 2a...First rubber layer 2b...Second rubber layer 3…Core layer (adhesive rubber layer) 4… Core wire 5...Stretchable rubber layer

Claims

1. A cogged V-belt having cog sections on at least the inner circumference side, in which cog peaks and cog valleys are arranged alternately along the longitudinal direction of the belt, The cog portion comprises at least a compressed rubber layer, The compression rubber layer includes a first rubber layer which is the outermost layer on the inner circumferential surface side, and a second rubber layer which is on the outer circumferential side of the belt than the first rubber layer. The first rubber layer and the second rubber layer are exposed to form a friction transmission surface. The cross-sectional shape of the cog valley in the thickness direction along the longitudinal direction of the belt is a shape comprising a bottom portion formed by combining a plurality of continuous arcs and a side wall portion extending from the bottom portion inclined with respect to the belt thickness direction or along the belt thickness direction, As the plurality of arcs move away from the deepest part of the cog valley, the radius of curvature decreases. Of the plurality of arcs, the radius of curvature of the first arc passing through the deepest part is larger in diameter than the virtual circle tangent to the deepest part and the side walls on both sides. The first rubber layer includes first short fibers oriented in the belt width direction, and A cog-type V-belt in which the first rubber layer has a bending modulus of elasticity in the direction parallel to the short fibers of 1.4 to 3 MPa.

2. Height H of the aforementioned cog portion １ The radius of curvature R of the first arc relative to １ The ratio [(R １ / H １ A cog-type V-belt according to claim 1, wherein the ratio of [) × 100] is 45 to 55%.

3. The plurality of arcs are a combination of the first arc and a pair of second arcs interposed between the first arc and the side wall portion, and the height H of the cog portion. １ The radius of curvature R of the second arc relative to ２ The ratio [(R ２ / H １ A cog-type V-belt according to claim 1 or 2, wherein the ratio of [) × 100] is 10 to 20%.

4. A V-belt with cogs according to claim 1 or 2, wherein the overall thickness H of the belt is 18 mm or more and less than 27 mm.

5. The overall thickness H of the belt is 18 mm or more and less than 21 mm, and the ratio [(H ２ / H) × 100] of the thickness H of the valley to the thickness H ２ is 11 to 34%. The cogged V-belt according to claim 1 or 2.

6. The overall thickness H of the belt is 21 mm or more and less than 24 mm, and the core valley thickness H is relative to the said thickness H. ２ The ratio [(H ２ A cog-type V-belt according to claim 1 or 2, wherein the ratio of [H) x 100] is 14 to 34%.

7. The overall thickness H of the belt is 24 mm or more and less than 27 mm, and the core valley thickness H is the same as the thickness H. ２ The ratio [(H ２ A cog-type V-belt according to claim 1 or 2, wherein the ratio of [H) x 100] is 21 to 41%.

8. The cogted V-belt according to claim 1 or 2, which is a low-edge cogted V-belt.

9. A belt transmission mechanism comprising a cog-equipped V-belt according to claim 1 or 2 and a pulley, and provided in a belt-type continuously variable transmission.

10. A belt transmission mechanism according to claim 9, provided in a belt-type continuously variable transmission for large agricultural machinery.

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