Transmission v-belt and belt transmission mechanism

Abstract

To provide a transmission V-belt that can suppress exothermic heat even when being used for a small-sized belt type stepless speed change device, and can suppress peeling of a core wire and generation of cracks in a compressed rubber layer.SOLUTION: A core wire of a transmission V-belt is formed by Lang' lay cords obtained by doubling and ply-twisting a plurality of aramid fiber-containing first twist yarns, and a total fineness of the core wire is adjusted to 1,000-3,500 dtex. Tensile strength per wire of the core wire may be 500-1,000 N. A pitch of the core wire may be larger by 0.05-0.25 mm than an average diameter of the core wire, and an average diameter of the core wire may be 0.4-1 mm. An elongation rigidity per mm pitch width of the belt may be 6,500-20,000 N, and a flexural rigidity per mm pitch width of the belt may be 40-260 N (mm)2. A thickness of the transmission V-belt may be 5-12 mm, and a pitch width may be 10-25 mm. The transmission V-belt may be a low edge V-belt having a cog at least on the inner peripheral surface side, and the transmission V-belt may be a gear change belt to be used for a small-sized belt type stepless speed change device.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a transmission V-belt used in a small belt-type continuously variable transmission or the like, and a belt transmission mechanism including the transmission V-belt.

Background Art

[0002] Transmission belts used in power transmission mechanisms of mechanical devices and the like are roughly classified into friction transmission belts and meshing transmission belts according to the form of power transmission. As friction transmission belts, V-belts, V-ribbed belts, flat belts, etc. are known, and as meshing transmission belts, toothed belts are known.

[0003] As an example of V-belts, there is a low-edge type belt (low-edge V-belt) in which a rubber layer with a friction transmission surface (V-shaped side surface) is exposed. Among low-edge type belts, in addition to the low-edge V-belt without cogs, there are low-edge cogged V-belts in which cogs are provided only on the inner peripheral surface of the belt to improve flexibility, and low-edge cogged V-belts (low-edge double-cogged V-belts) in which cogs are provided on both the inner and outer peripheral surfaces of the belt to improve flexibility, that is, cogged V-belts.

[0004] Examples of applications of these V-belts (especially low-edge cogged V-belts) include belt-type continuously variable transmissions. As shown in FIG. 1, a belt-type continuously variable transmission 30 is a device that wraps a V-belt 1A around a driving pulley 31 and a driven pulley 32 to continuously change the transmission ratio. Each pulley 31, 32 consists of a fixed sheave 31a, 32a whose axial movement is restricted or fixed, and a movable sheave 31b, 32b that is axially movable, and has a structure that can continuously change the width of the V-groove of the pulleys 31, 32 formed by these fixed sheaves 31a, 32a and movable sheaves 31b, 32b. The V-belt 1A has tapered surfaces on both end faces in the width direction that match the inclination of the opposing surfaces of the V-grooves of the respective pulleys 31, 32, and fits into an arbitrary 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 of the driving pulley 31 and widening the width of the V-groove of the driven pulley 32, when changing from the state shown in FIG. 1(a) to the state shown in FIG. 1(b), the V-belt 1A moves to the outer peripheral side in the pulley radial direction on the driving pulley 31 side and to the inner peripheral side in the pulley radial direction on the driven pulley 32 side, and the winding radius around each pulley 31, 32 continuously changes, enabling stepless adjustment of the transmission ratio.

[0005] V-belts (transmission belts) used in such applications are required to have high lateral pressure resistance (high width-direction rigidity) to suppress belt deformation due to lateral pressure received from the pulleys, high flexibility (low bending rigidity) to reduce the winding radius around the pulleys, and low elongation (high elongation rigidity) of the belt to suppress slip and obtain the desired transmission ratio, in addition to the winding rotation running between the two shafts of the driving pulley and the driven pulley, and also to cope with movements in the pulley radial direction and repeated bending operations caused by continuous changes in the winding radius.

[0006] As a proposal for these requirements, Japanese Patent Application Laid-Open No. 2010-196888 (Patent Document 1) discloses a transmission belt in which the compression rubber layer is composed of two layers, an upper layer close to the core wire and a lower layer on the inner peripheral surface side, and the hardness of the upper layer is in the range of 93 to 99 and the hardness of the lower layer is in the range of 80 to 88. Further, this document describes that when the upper width of the belt is W and the thickness of the belt is T, these relationships may be 0.3W ≦ T ≦ 0.6W. Furthermore, as the effect of the invention, this document describes that the upper layer with high hardness improves the deformation resistance of the belt, the lower layer with low hardness is excellent in flexural fatigue resistance and hardly generates cracks, and reducing the thickness of the belt reduces the deformation during bending and suppresses the generation of cracks.

[0007] Japanese Patent Application Laid-Open No. 2005-265106 (Patent Document 2) aims to provide a double cogged V-belt that does not promote the fatigue of a core wire made of para-aramid fiber and is excellent in flexural fatigue resistance. It has a core wire made of para-aramid fiber, and the belt bending rigidity is 600 to 1200 N / mm 3 and a double cogged V-belt having a dynamic compression spring constant in the belt width direction of 15000 N / mm or more is disclosed.

[0008] Japanese Patent Application Laid-Open No. 2014-209029 (Patent Document 3) discloses a transmission belt in which the core wire is formed of aramid fiber, the strain when compressed with a stress of 2.0 N / mm 2 in the width direction is 0.5 to 0.8%, and the strain when pulled with a load of 2 kN in the length direction is 0.35 to 0.7%. As the effect of the invention, this document describes that compared with conventional products, the rigidity in the belt width direction is slightly smaller and the elongation in the belt longitudinal direction is slightly larger, so that even if a large misalignment occurs during gear shifting, the occurrence of pop-out in which the core wire pops out from the belt body is suppressed.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

[0010] The belt configurations disclosed in Patent Documents 1 to 3 show certain effects on the performance required for V-belts. However, the requirements for miniaturization of belt-type continuously variable transmissions and improvement of the durability of transmission belts are becoming more stringent, and further improvements are demanded. In particular, when the winding radius around the pulley becomes small, the heat generation when the belt is bent and stretched increases, which promotes the thermal degradation of the rubber, easily causes cracks in the rubber and peeling of the core wire, and there is a problem that the durability of the belt is likely to decrease.

[0011] Therefore, an object of the present invention is to provide a transmission V-belt that can suppress heat generation even when used in a small belt-type continuously variable transmission, and can also suppress the occurrence of peeling of the core wire and cracks in the compression rubber layer, and a belt transmission mechanism including this transmission V-belt. Means for Solving the Problems

[0012] As a result of intensive studies to achieve the above problems, the present inventors have formed the core wire of a transmission V-belt with a lang lay cord obtained by combining and twisting multiple lower-twisted yarns containing aramid fibers, and by adjusting the total fineness of the core wire to 1000 to 3500 dtex, it has been found that heat generation can be suppressed even when used in a small belt-type continuously variable transmission, and the occurrence of peeling of the core wire and cracks in the compression rubber layer can also be suppressed, and the present invention has been completed.

[0013] That is, the present invention includes the following aspects.

[0014] Aspect [1]: A V-belt for transmission, formed of a lang lay cord that is formed by combining and twisting multiple lower-twisted yarns containing aramid fibers, and having a core wire with a total fineness of 1000 to 3500 dtex.

[0015] Aspect [2]: The V-belt for transmission according to Aspect [1], wherein the tensile strength per single core wire is 500 to 1000 N.

[0016] Aspect [3]: The V-belt for transmission according to Aspect [1] or [2], wherein in the core wire, the twist coefficient of the lower-twisted yarn is 0.5 to 3, and the twist coefficient of the lang lay cord is 0.5 to 5.

[0017] Aspect [4]: The V-belt for transmission according to any one of Aspects [1] to [3], wherein the pitch of the core wire is 0.05 to 0.25 mm larger than the average diameter of the core wire.

[0018] Aspect [5]: The V-belt for transmission according to any one of Aspects [1] to [4], wherein the average diameter of the core wire is 0.4 to 1 mm.

[0019] Aspect [6]: The V-belt for transmission according to any one of Aspects [1] to [5], wherein the elongation stiffness per 1 mm of the pitch width of the V-belt for transmission is 6500 to 20000 N.

[0020] Aspect [7]: The V-belt for transmission according to any one of Aspects [1] to [6], wherein the bending stiffness per 1 mm of the pitch width of the V-belt for transmission is 40 to 260 N(mm) 2 and is the V-belt for transmission according to any one of Aspects [1] to [6].

[0021] Aspect [8]: The V-belt for transmission according to any one of Aspects [1] to [7], having a thickness of 5 to 12 mm and a pitch width of the V-belt for transmission of 10 to 25 mm.

[0022] Aspect [9]: The V-belt for transmission according to any one of Aspects [1] to [8], which is a low-edge V-belt having cogs at least on the inner circumferential surface side.

[0023] Aspect

[10] : A transmission V-belt according to any one of Aspects [1] to [9], which is a variable-speed belt used in a small belt-type continuously variable transmission.

[0024] Aspect

[11] : A belt transmission mechanism including a transmission V-belt according to any one of Aspects [1] to

[10] and a pulley.

[0025] Aspect

[12] : The belt transmission mechanism according to Aspect

[11] , wherein the transmission V-belt is a low-edge V-belt having cogs at least on the inner circumferential surface side and is a variable-speed belt used in a small belt-type continuously variable transmission.

Advantages of the Invention

[0026] In the present invention, a core wire of a transmission V-belt is formed of a lang lay cord obtained by combining and twisting a plurality of lower-twisted yarns containing aramid fibers, and the total fineness of the core wire is adjusted to 1000 to 3500 dtex. Therefore, even when used in a small belt-type continuously variable transmission, heat generation can be suppressed, and the occurrence of core wire peeling and cracks in the compression rubber layer can also be suppressed.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0028] [V-belt for Transmission] The V-belt for transmission of the present invention is not particularly limited as long as it is a V-belt for transmission formed of a lang twist cord obtained by combining and twisting a plurality of lower-twisted yarns containing aramid fibers and having a core yarn with a total fineness of 1000 to 3500 dtex. Further, the V-belt for transmission of the present invention is a friction transmission belt having a V-shaped friction transmission surface, and such a V-belt may be a raw-edge type belt (raw-edge V-belt) in which the friction transmission surface (V-shaped side surface) is an exposed rubber layer, or may be a wrapped type belt (wrapped V-belt) in which the friction transmission surface is covered with a covering cloth (cover cloth). Among these, a raw-edge V-belt is preferable from the viewpoint of excellent transmission performance.

[0029] The low-edge V-belt includes a low-edge V-belt without cogs and a low-edge cogged V-belt with cogs. Further, the low-edge cogged V-belt includes a low-edge cogged V-belt having cogs formed only on the inner peripheral side of the low-edge V-belt and a low-edge double-cogged V-belt having cogs formed on both the inner peripheral side and the outer peripheral side of the low-edge V-belt. In the present application, the low-edge V-belt without cogs, the low-edge cogged V-belt, and the low-edge double-cogged V-belt are collectively referred to as the low-edge V-belt. Among these, from the viewpoint of the great effect of the present invention, the low-edge cogged V-belt and the low-edge double-cogged V-belt used for a variable-speed belt (CVT belt) are preferable.

[0030] FIG. 2 is a schematic partial cross-sectional perspective view showing an example of the low-edge cogged V-belt of the present invention, and FIG. 3 is a schematic cross-sectional view obtained by cutting the low-edge cogged V-belt of FIG. 2 in the belt longitudinal direction.

[0031] In this example, the low-edge cogged V-belt 1 has a cog portion formed on the inner peripheral surface of the belt body, in which cog peaks 1a and cog valleys 1b are alternately arranged along the longitudinal direction of the belt (direction A in the figure). The cross-sectional shape of the cog peak 1a in the longitudinal direction is substantially semi-circular (curved or wavy), and the cross-sectional shape in the direction orthogonal to the longitudinal direction (width direction or direction B in the figure) is trapezoidal. That is, each cog peak 1a protrudes substantially semi-circularly from the cog valley 1b in the cross-section in the A direction in the belt thickness direction. The low-edge cogged V-belt 1 has a laminated structure, and a reinforcing cloth 2, an extension rubber layer 3, a core layer (adhesive rubber layer) 4, a compression rubber layer 5, and a reinforcing cloth 6 are sequentially laminated from the outer peripheral side to the inner peripheral side of the belt (the side where the cog portion is formed). The cross-sectional shape in the belt width direction is trapezoidal with the belt width decreasing from the outer peripheral side to the inner peripheral side of the belt. Further, a core wire 4a is embedded in the adhesive rubber layer 4, and the cog portion is formed on the compression rubber layer 5 by a cogged molding die.

[0032] FIG. 4 is a schematic partial cross-sectional perspective view showing an example of the low-edge double-cogged V-belt of the present invention, and FIG. 5 is a schematic cross-sectional view of the low-edge double-cogged V-belt of FIG. 4 cut in the longitudinal direction of the belt.

[0033] In this example, the low-edge double-cogged V-belt 11 has an inner circumferential cog portion in which inner circumferential cog teeth 11a and inner circumferential cog grooves 11b are alternately arranged along the longitudinal direction of the belt (direction A in the figure) on the inner circumferential surface of the compression rubber layer 15. The cross-sectional shape of each inner circumferential cog tooth 11a in the longitudinal direction is substantially semicircular (curved or wavy), and the cross-sectional shape in the direction orthogonal to the longitudinal direction (width direction or direction B in the figure) is trapezoidal. That is, each inner circumferential cog tooth 11a protrudes substantially semicircularly from the inner circumferential cog groove 11b in the cross-section in the A direction in the belt thickness direction.

[0034] Furthermore, the outer circumferential surface also has an outer circumferential cog portion in which outer circumferential cog teeth 11c and outer circumferential cog grooves 11d are alternately arranged along the longitudinal direction of the belt. The cross-sectional shape of each outer circumferential cog tooth 11c in the longitudinal direction is substantially trapezoidal, and the cross-sectional shape in the direction orthogonal to the longitudinal direction (width direction or direction B in the figure) is substantially rectangular. That is, each outer circumferential cog tooth 11c protrudes substantially trapezoidally from the outer circumferential cog groove 11d in the cross-section in the A direction in the belt thickness direction.

[0035] The low-edge double-cogged V-belt has a laminated structure, and an extension rubber layer 13, a core layer (adhesive rubber layer) 14, a compression rubber layer 15, and a reinforcing cloth 16 are sequentially laminated from the outer circumferential side to the inner circumferential side of the belt. The cross-sectional shape in the belt width direction is substantially trapezoidal with the belt width decreasing from the outer circumferential side to the inner circumferential side of the belt. Furthermore, a core wire 14a is embedded in the core layer 14, and the inner circumferential cog portion and the outer circumferential cog portion are formed in the compression rubber layer 15 and the extension rubber layer 13, respectively, by a cogged molding die.

[0036] (Overall thickness of the transmission V-belt) In the V-belt for transmission of the present invention (particularly, a low-edge V-belt), the thickness (average thickness) of the entire belt is, for example, 5 to 12 mm, preferably 7 to 11.5 mm, and more preferably 8 to 11 mm. In the present invention, when the thickness of the V-belt for transmission is within such a range, the bending rigidity of the belt can be reduced, and even when it is used in a small belt-type continuously variable transmission, heat generation, peeling of the core wire, and generation of cracks in the rubber can be suppressed.

[0037] FIG. 6 shows the definition of the overall thickness of the low-edge double-cogged V-belt in the present invention based on FIG. 5. Specifically, in FIG. 6, in the low-edge double-cogged V-belt 11, the outer peripheral cog height H5 indicates the height of the outer peripheral cog portion formed on the outer peripheral surface, and the outer peripheral pitch height H4 indicates the distance from the center portion of the core wire to the outer peripheral surface (the top of the cog portion). Further, the inner peripheral cog height H2 indicates the height of the inner peripheral cog portion formed on the inner peripheral surface, and the core-valley thickness H3 indicates the distance from the center portion of the core wire to the deepest part of the inner peripheral cog valley. On the other hand, the overall thickness H1 means the thickness obtained by summing the inner peripheral cog height H2, the core-valley thickness H3, and the outer peripheral pitch height H4, and means the thickness at the top of the cog portion (the maximum thickness of the belt).

[0038] In the present application, the overall thickness of the V-belt for transmission (particularly, a low-edge V-belt) means the thickness from the outer peripheral surface to the inner peripheral surface (the thickness at the thickest part of the belt thickness), and when having cogs, as shown in FIG. 6, the top of the cog becomes the inner peripheral surface or the outer peripheral surface. Therefore, in a low-edge cogged V-belt having cogs only on the inner peripheral surface, the distance from the outer peripheral surface to the top of the cog portion on the inner peripheral surface is the overall thickness. That is, the overall thickness means the distance from the top of the cog of the compression rubber layer (the convex top on the inner peripheral side) to the back surface of the belt in the case of a low-edge cogged V-belt, and the distance from the top of the cog of the compression rubber layer (the convex top on the inner peripheral side) to the top of the cog of the extension rubber layer (the convex top on the outer peripheral side) in the case of a low-edge double-cogged V-belt.

[0039] (Belt pitch width of the V-belt for transmission) In the V-belt for transmission of the present invention (particularly, a low-edge V-belt), the belt pitch width is, for example, 10 to 25 mm, preferably 12 to 24.5 mm, more preferably 15 to 24 mm. In the present invention, when the belt pitch width of the V-belt for transmission is within such a range, the bending rigidity of the belt can be reduced, and even when it is used in a small belt-type continuously variable transmission, heat generation, peeling of the core wire, and generation of cracks in the rubber can be suppressed. In particular, when the overall thickness of the belt is within the above range and the belt pitch width is within such a range, since the thickness is thin and the pitch width is narrow, the effect of the present invention is particularly enhanced, which is preferable.

[0040] FIG. 7 shows the definition of the belt pitch width of the low-edge cogged V-belt in the present invention. That is, FIG. 7 is a schematic cross-sectional view of a low-edge cogged belt 1 in which a reinforcing cloth 2, an extension rubber layer 3, a core layer 4, a compression rubber layer 5, and a reinforcing cloth 6 are sequentially laminated. The belt pitch width W means the width of the belt at the belt pitch line L (a position on the line connecting the centers of the core wires 4a buried at equal intervals in the core layer 4).

[0041] (Elongation rigidity of the V-belt for transmission) In the V-belt for transmission of the present invention (particularly, a low-edge V-belt), the elongation rigidity per 1 mm of the belt pitch width (belt elongation rigidity EA) is, for example, 6200 to 25000 N, preferably 6500 to 20000 N, more preferably 7000 to 18000 N, still more preferably 7500 to 15000 N, and most preferably 8000 to 12000 N. In the present invention, since the belt elongation rigidity EA is within such a range, heat generation caused by slip can be suppressed. If the belt elongation rigidity EA is too small, there is a risk that the belt elongation will be large and it will be easy to slip when the load is large. On the other hand, if the belt elongation rigidity EA is too large, it will be difficult to absorb load fluctuations due to the elongation of the belt, and there is a risk that it will be easy to slip.

[0042] In the present application, the belt elongation rigidity EA represents the relationship between the tensile force and the strain (elongation rate) when the belt is stretched in the length direction. When the belt elongation rigidity is high, it is difficult to elongate, and when the belt elongation rigidity is low, it is easy to elongate.

[0043] In the present application, the elongation rigidity EA of the belt is defined as the proportionality constant of the belt tension with respect to the belt length change rate in the range where the belt tension is 200 to 600 N. That is, in the present application, the elongation rigidity EA of the belt can be obtained as the slope of the approximate straight line of the measured values every 100 N between 200 N and 600 N of the belt tension in a graph obtained by plotting the measured values with the belt length change rate (%) on the horizontal axis and the belt tension (N) on the vertical axis, and specifically, it can be measured by the method described in the examples below.

[0044] (Bending rigidity of V-belt for transmission) In the V-belt for transmission (particularly, low-edge V-belt) of the present invention, the bending rigidity per 1 mm of the pitch width of the belt (belt bending rigidity EI) is, for example, 40 to 260 N(mm) 2 , preferably 60 to 250 N(mm) 2 , more preferably 80 to 240 N(mm) 2 , still more preferably 100 to 235 N(mm) 2 , most preferably 120 to 230 N(mm) 2 is. In the present invention, since the bending rigidity EI of the belt is in such a range, heat generation due to bending can be suppressed. If the bending rigidity EI of the belt is too small, there is a risk that the vibration and noise of the belt will increase. Conversely, if it is too large, there is a risk that the internal heat generation due to the bending elongation of the belt will increase.

[0045] In the present application, the bending rigidity EI of the belt represents the relationship between the compression force required when compressing the annular belt from the outer peripheral side to deform it into a rice-bale shape and the pitch diameter (the diameter of the arc drawn by the pitch line connecting the center lines of the core wires) when the bent portion of the belt is regarded as an arc. When the bending rigidity of the belt is high, the belt is difficult to bend, and when the bending rigidity of the belt is low, the belt is easy to bend.

[0046] In the present application, the bending rigidity EI of the belt can be measured using an autograph, and specifically, it can be measured by the method described in the examples below.

[0047] Core wire In the V-belt for transmission of the present invention, the core wire is formed of a Lang lay cord in which a plurality of lower-twisted yarns containing aramid fibers are combined and upper-twisted, and the total fineness is 1000 to 3500 dtex. In the present invention, since the core wire has such characteristics, heat generation during the use of the V-belt for transmission can be suppressed, and peeling of the core wire and generation of cracks in the compression rubber layer can be suppressed. However, it is particularly effective when used in a small-sized belt-type continuously variable transmission with a relatively small load as a transmission belt. The reason why it is particularly effective when used as a transmission belt can be presumed as follows.

[0048] As failure modes of the transmission belt, cog valley cracking and core wire peeling can be mentioned, and both failures are likely to occur when the temperature of the belt becomes high. Therefore, it can be said that suppressing the heat generation of the belt is the key to improving the durability of the transmission belt. The causes of the heat generation of the belt include slip (frictional heat due to friction between the belt and the pulley) and bending (internal heat generation due to bending and stretching of the belt).

[0049] Based on the idea that it is basically desirable for the transmission belt to have a high elongation rigidity, materials with a high tensile elastic modulus such as aramid fibers and carbon fibers are used for the core wire, and the core wire diameter also tends to be thick. On the other hand, in the V-belt for transmission of the present invention, the core wire is characterized by a small diameter, but it can be presumed that by using aramid fibers with a high tensile elastic modulus as the core wire, the elongation rigidity of the belt can be ensured even with a small diameter. In addition, since the elongation rigidity of the belt can be maintained relatively high, the elongation of the belt can be suppressed, slip can be reduced, and heat generation can be suppressed. Furthermore, since the bending rigidity of the belt can be reduced due to the small diameter, it can be presumed that heat generation caused by bending can also be suppressed.

[0050] That is, in the present invention, since the core wire contains aramid fibers and has a small diameter, the elongation rigidity of the belt is increased due to the high elastic modulus of aramid, heat generation caused by slip can be suppressed, and the bending rigidity of the belt is decreased due to the small diameter, and heat generation caused by bending can be suppressed.

[0051] In such a Lang lay-twist cord forming the core wire, the lower-twist yarn may be an aramid multifilament yarn containing a plurality of aramid fibers. The aramid multifilament yarn may contain other fibers (such as polyester fibers) if necessary. The proportion of aramid fibers may be 50% by mass or more (particularly 80 to 100% by mass) with respect to the entire multifilament yarn, and preferably, all filaments are composed of aramid fibers. In the present invention, since the core wire contains aramid fibers, the elongation rigidity of the belt can be improved, and heat generation due to slip can be suppressed. Therefore, if the proportion of aramid fibers is too small, there is a risk of easy heat generation.

[0052] The aramid multifilament yarn only needs to contain a plurality of aramid filaments. For example, it may contain 100 to 5000 filaments, preferably 300 to 2000 filaments, more preferably 600 to 1500 filaments, and even more preferably 800 to 1200 filaments. The average fineness of the aramid filaments is, for example, 0.8 to 10 dtex, preferably 1 to 5 dtex, more preferably 1.1 to 2 dtex, and even more preferably 1.5 to 1.7 dtex.

[0053] Para-aramid fibers are preferred for aramid fibers because of their excellent mechanical strength. Specifically, it may be a para-aramid fiber of a single repeating unit (for example, "Twaron (registered trademark)" manufactured by Teijin Limited, which is polyparaphenylene terephthalamide fiber, "Kevlar (registered trademark)" manufactured by Toray DuPont Co., Ltd., etc.), or a copolymer para-aramid fiber containing a plurality of repeating units (for example, "Technora" manufactured by Teijin Limited, which is a copolymer aramid fiber of polyparaphenylene terephthalamide and 3,4'-oxydiphenylene terephthalamide, etc.). Among these, copolymer para-aramid fibers are particularly preferred.

[0054] The tensile modulus of the aramid fiber can be selected from the range of about 50 to 100 GPa, for example, 50 to 90 GPa, preferably 60 to 90 GPa, more preferably 65 to 85 GPa, and even more preferably 70 to 80 GPa. In applications where high flexural fatigue resistance is required, the aramid fiber may be a high-elongation aramid fiber with a tensile modulus of about 50 to 70 GPa. If the tensile modulus is too small, the elongation stiffness of the belt may decrease, resulting in heat generation due to slip. Conversely, if it is too large, the flexural fatigue resistance may decrease.

[0055] In the present application, the tensile modulus means the value of the apparent Young's modulus measured according to the measurement method of the initial tensile resistance described in Section 8.10 of JIS L 1013 (2021).

[0056] The fineness of each lower-twisted yarn is 2000 dtex or less, preferably 500 to 2000 dtex, more preferably 1000 to 1900 dtex, even more preferably 1300 to 1800 dtex, and most preferably 1500 to 1700 dtex. If the fineness is too small, the elongation will increase, and the tensile strength and tensile modulus will decrease, which may also reduce the economic efficiency. Conversely, if it is too large, the flexural fatigue resistance may decrease.

[0057] The number of lower-twisted yarns may be a plurality of strands, but preferably 2 to 6 strands, more preferably 2 to 4 strands, even more preferably 2 to 3 strands, and most preferably 2 strands. If the number is too large, the flexural fatigue resistance may decrease.

[0058] The twist coefficient (lower twist coefficient) of each lower-twisted yarn can be selected from the range of about 0.3 to 5, for example, 0.5 to 3, preferably 0.6 to 2.5, more preferably 0.7 to 2, even more preferably 0.8 to 1.5, and most preferably 0.9 to 1.2. If the lower twist coefficient is too small, the bending stiffness of the belt may increase or the flexural fatigue resistance may decrease. Conversely, if it is too large, the elongation stiffness of the belt may decrease.

[0059] In the present invention, the lower-twisted yarn is produced by adding twist in one direction to a multifilament yarn. However, the twisted cord obtained by aligning and applying upper twist to a plurality of the obtained lower-twisted yarns is a Lang twist cord in which the upper twist is applied in the same direction as the direction of the lower twist. Since the Lang twist cord has a large inclination angle of the filaments with respect to the longitudinal direction of the twist cord, it has excellent flexibility and can reduce the bending rigidity of the belt.

[0060] The twist coefficient (upper twist coefficient of the upper-twisted yarn) of the Lang twist cord can be selected from the range of about 0.5 to 5, for example, 1 to 4.5, preferably 1.5 to 4, more preferably 2 to 3.8, still more preferably 2.5 to 3.5, and most preferably 2.8 to 3.2. If the upper twist coefficient is too small, the bending rigidity of the belt may increase or the flexural fatigue resistance may decrease. Conversely, if it is too large, the elongation rigidity of the belt may decrease.

[0061] The ratio of the upper twist coefficient to the lower twist coefficient (upper twist coefficient / lower twist coefficient) is, for example, 0.5 to 10, preferably 1 to 8, more preferably 1.5 to 5, still more preferably 2 to 4, and most preferably 2.5 to 3.5.

[0062] In the present application, each twist coefficient of the lower twist coefficient and the upper twist coefficient can be calculated based on the following formula.

[0063] TF = TN × D 0.5 / 960 [In the formula, TF: twist coefficient, TN: number of twists per meter, D: fineness (tex) of the yarn]

[0064] The total fineness of the Lang twist cord is 1000 to 3500 dtex. In the present invention, since the total fineness of the core wire formed by the Lang twist cord is relatively small, the bending rigidity of the belt is low and heat generation due to bending can also be suppressed. If the total fineness is less than 1000 dtex, the elongation rigidity of the belt may decrease. If the total fineness exceeds 3500 dtex, the bending rigidity of the belt may increase. The total fineness of the Lang twist cord is preferably 2000 to 3450 dtex, and more preferably 3000 to 3400 dtex.

[0065] The S-twisted Lang lay cord may be subjected to an adhesion treatment (or surface treatment) in order to improve the adhesion to the rubber component. As the adhesion treatment method, a conventional method can be used. For example, a method described in Japanese Patent No. 6349369 including a step of treating with a first treating agent composed of a rubber composition (a) containing a condensate (a1) of resorcinol and formaldehyde, a rubber component (a2) containing a carboxyl-modified latex, and a curing agent (a3) containing a polycarbodiimide resin having a plurality of carbodiimide groups and a hydrophilic solvent (b) can be mentioned. Among them, a first treatment step of treating with a first treating agent composed of a rubber composition (a) containing a curing agent (a3) containing a polycarbodiimide resin having a plurality of carbodiimide groups and a hydrophilic solvent (b), a second treatment step of treating the first treated yarn treated in the first treatment step with a second treating agent containing resorcinol, formaldehyde, and latex, and a third treatment step of treating the second treated yarn treated in the second treatment step with a third treating agent containing rubber are preferably included. When an adhesive component penetrates between the Z-twisted yarns or between the fibers of the single fibers constituting the Z-twisted yarn and the adhesive component adheres to the surface of the fibers, the bundling property of the fibers can be improved.

[0066] The adhesion rate (solid content adhesion rate) of the adhesive component is, for example, 1 to 50% by mass, preferably 3 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 10 to 20% by mass with respect to the Lang lay cord before the adhesion treatment. If the proportion of the adhesive component is too small, the adhesion between the fibers is insufficient, and rubbing between the fibers may occur during bending, resulting in a decrease in flex fatigue resistance. If the proportion of the adhesive component is too large, there is a risk that the core wire diameter becomes too large.

[0067] The average diameter of the core wire (Lang lay cord after the adhesion treatment) is, for example, 0.1 to 1.2 mm, preferably 0.3 to 1.1 mm, more preferably 0.4 to 1 mm, even more preferably 0.5 to 0.9 mm, and most preferably 0.6 to 0.8 mm.

[0068] In the present application, the average diameter of the core wire means the average value of the diameters of the core wires in the belt. The average diameter of the core wire is obtained by photographing a cross-section in the belt width direction with a scanning electron microscope (SEM), measuring the lengths in the belt width direction of all the core wires included in the belt in the photographed image, and calculating the arithmetic average value. However, when a part of the core wire is missing on the side surface of the belt, it is excluded from the measurement target.

[0069] In the present invention, for example, compared with the tensile strength of the core wire in the example of Patent Document 2 (the tensile strength of an aramid core wire with a total fineness of 9900 dtex is 1300 N), etc., the total fineness of the core wire is relatively small, and the tensile strength per core wire is low. Therefore, by reducing the core wire pitch and arranging them densely, the elongation rigidity of the belt can be improved. From the viewpoint of increasing the elongation rigidity of the belt, it is considered preferable that the tensile strength per core wire is high. However, if the core wire is thickened to increase the tensile strength per core wire, there is a risk that the flexibility will decrease, and since it is necessary to increase the core wire pitch, the elongation rigidity of the belt will not be increased significantly. In the present invention, while preventing the tensile strength per core wire from becoming excessively low, the core wire diameter is reduced and arranged densely, and the bending rigidity can be reduced while ensuring the elongation rigidity of the belt.

[0070] The tensile strength per core wire is, for example, 300 to 1200 N, preferably 500 to 1000 N, more preferably 550 to 800 N, still more preferably 580 to 700 N, and most preferably 600 to 650 N. If the tensile strength per core wire is too low, there is a risk that the elongation rigidity of the belt will be low, and if the tensile strength per core wire is too high, there is a risk that the bending rigidity of the belt will be high.

[0071] In the present application, the tensile strength per core wire can be measured in accordance with JIS L 1017 (2002).

[0072] The core wires are arranged at a predetermined interval in the belt width direction, extend along the belt length direction (circumferential direction), and are embedded in the core layer. This core wire acts as a tensile member and may be arranged to extend in parallel at a predetermined pitch in the belt length direction, but from the viewpoint of productivity, it is usually arranged in a spiral shape extending in parallel at a predetermined pitch substantially in the belt length direction. When arranged in a spiral shape, the angle of the core wire with respect to the belt length direction may be, for example, 5° or less, and from the viewpoint of belt running performance, the closer to 0° the better.

[0073] The pitch of the core wire (the average value of the distance between the centers of adjacent core wires in the cross-section in the belt width direction) is preferably larger than the average diameter of the core wire within a predetermined range. Specifically, the value obtained by subtracting the core wire diameter from the core wire pitch (the value of "core wire pitch - average core wire diameter", which means the width per portion where there is no core wire in the cross-section in the belt width direction) can be selected from the range of about 0.03 to 0.3 mm, for example, 0.05 to 0.25 mm, preferably 0.08 to 0.23 mm, more preferably 0.1 to 0.22 mm, and still more preferably 0.15 to 0.21 mm. If the above value is too small, there is a risk that the core wires will ride on each other or rub against each other, resulting in a decrease in the tensile strength of the belt. Conversely, if it is too large, there is a risk that the elongation rigidity of the belt will be low. That is, from the viewpoint of increasing the elongation rigidity of the belt, the smaller the above value is, the better, but if it is too small, there is a risk that the core wires will ride on each other or rub against each other, and the strength will be easily reduced.

[0074] In the present application, the number of core wires means the apparent number in the cross-sectional view of the core wires arranged at a predetermined core wire pitch in the belt width direction as shown in FIG. 2. That is, the number of core wires means the number of spirals when a single core wire is embedded in a spiral shape. However, in reality, since the core wire is embedded in a spiral shape, the arrangement pattern of the core wires is different depending on the part where the cross-section is taken in a single endless transmission V-belt. Therefore, practically, when each core wire pitch is a constant value, the value obtained by truncating the decimal part from the calculated value obtained by dividing the belt width by the core wire pitch is regarded as the approximate "number of core wires" (effective number).

[0075] [Compression rubber layer] In the V-belt for transmission of the present invention, the compression rubber layer is formed of a rubber composition (vulcanized rubber composition) containing a first rubber component.

[0076] (A1) First rubber component As the first rubber component, a rubber that can be vulcanized or crosslinked may be used. For example, diene rubbers [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 elastomers [ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.], chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluorine rubber, etc. may be mentioned. These rubber components can be used alone or in combination of two or more.

[0077] Among these, ethylene-α-olefin elastomers and chloroprene rubber are preferable, and chloroprene rubber is particularly preferable from the viewpoint of excellent balance of heat resistance, abrasion resistance, oil resistance, etc. and high productivity.

[0078] When the first rubber component contains chloroprene rubber, the proportion of chloroprene rubber 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 to 100% by mass) from the viewpoint of improving the above characteristics and productivity, and 100% by mass (only chloroprene rubber) is most preferable. The proportion of the ethylene-α-olefin elastomer in the first rubber component when the first rubber component contains an ethylene-α-olefin elastomer is also the same as the proportion of the chloroprene rubber.

[0079] (A2) First short fiber The rubber composition for forming the compression rubber layer may further contain first short fibers. Examples of the first short fibers include polyamide short fibers (aliphatic polyamide short fibers such as polyamide 6 short fibers, polyamide 66 short fibers, and polyamide 46 short fibers; aramid short fibers, etc.), polyester short fibers [polyalkylene arylate fibers such as polyethylene terephthalate (PET) short fibers and polyethylene naphthalate (PEN) short fibers; liquid crystal polyester short fibers; polyarylate short fibers (such as amorphous wholly aromatic polyester short fibers), etc.], vinylon short fibers, polyvinyl alcohol-based short fibers, synthetic short fibers such as poly(paraphenylene benzobisoxazole) (PBO) short fibers; natural short fibers such as cotton, hemp, and wool; inorganic short fibers such as carbon short fibers, etc. These short fibers can be used alone or in combination of two or more. Among these, polyamide short fibers such as aramid short fibers and aliphatic polyamide short fibers are preferred, and a combination of aramid short fibers and aliphatic polyamide short fibers is particularly preferred.

[0080] The average fiber diameter of the first short fibers is 2 μm or more, for example, 2 to 100 μm, preferably 3 to 50 μm, more preferably 7 to 40 μm, and even more preferably 10 to 30 μm. The average fiber length of the first short fibers is, for example, 1 to 20 mm, preferably 1.3 to 15 mm, more preferably 1.5 to 10 mm, even more preferably 2 to 5 mm, and most preferably 2.5 to 4 mm.

[0081] The first short fibers may be embedded in the compression rubber layer in orientation substantially parallel to the belt width direction in order to suppress the compression deformation of the belt against the pressure from the pulley.

[0082] The first short fiber may be subjected to a conventional adhesion treatment to enhance the adhesion to the first rubber component. As the method of the adhesion treatment, conventional methods can be used. For example, a treatment liquid containing an initial condensate of phenols and formalin (such as a prepolymer of novolak or resole type phenol resin); a treatment liquid containing a rubber component (or latex), a treatment liquid containing the initial condensate and a rubber component (latex); a treatment liquid containing a reactive compound (adhesive compound) such as a silane coupling agent, an epoxy compound (such as an epoxy resin), an isocyanate compound, a bismaleimide compound, etc. Examples of the treatment method include treating with these treatment liquids. These methods can be used alone or in combination of two or more. Among these methods, the method of treating with a treatment liquid containing the initial condensate and a rubber component (latex) is preferred, and the method of treating with at least a resorcinol - formalin - latex (RFL) liquid is particularly preferred.

[0083] The proportion of the first short fiber is, for example, 5 to 50 parts by mass, preferably 5 to 40 parts by mass, more preferably 10 to 35 parts by mass, and still more preferably 20 to 30 parts by mass with respect to 100 parts by mass of the first rubber component.

[0084] (A3) Other components The rubber composition for forming the compression rubber layer may contain conventional additives as other components (first other components). Examples of the additives include crosslinking agents or vulcanizing agents (such as sulfur-based crosslinking agents, organic peroxides, etc.), co-crosslinking agents (such as bismaleimides, etc.), crosslinking aids or crosslinking accelerators (such as thiuram-based accelerators, etc.), crosslinking retardants, metal powders (such as zinc dust, etc.), metal oxides (such as zinc oxide, magnesium oxide, lead oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), fillers [reinforcing agents (reinforcing fillers) such as carbon black, silicon oxide (such as hydrated silica, etc.); extenders (non-reinforcing fillers or inert fillers) such as clay, calcium carbonate, talc, mica, etc.], plasticizers (or softening agents) [oils (such as paraffin oil, naphthenic oil, etc.), aliphatic carboxylic acid-based plasticizers, aromatic carboxylic acid ester-based plasticizers, oxycarboxylic acid ester-based plasticizers, phosphate ester-based plasticizers, ether-based plasticizers, ether ester-based plasticizers, etc.], processing agents or processing aids (such as stearic acid, metal salts of stearic acid, wax, paraffin, fatty acid amide, etc.), anti-aging agents (such as antioxidants, heat anti-aging agents, flex crack inhibitors, ozone degradation inhibitors, etc.), adhesion improvers, colorants, tackifiers, coupling agents (such as silane coupling agents, etc.), stabilizers (such as ultraviolet absorbers, heat stabilizers, etc.), flame retardants, antistatic agents, etc. These additives can be used alone or in combination of two or more. Note that the metal oxide may act as a crosslinking agent.

[0085] The proportion of the crosslinking agent (first crosslinking agent) is, for example, 1 to 20 parts by mass, preferably 2 to 15 parts by mass, more preferably 3 to 12 parts by mass, and even more preferably 4 to 10 parts by mass with respect to 100 parts by mass of the first rubber component.

[0086] The proportion of the filler (first filler) such as carbon black is, for example, 10 to 200 parts by mass, preferably 20 to 100 parts by mass, more preferably 30 to 80 parts by mass, and even more preferably 40 to 70 parts by mass with respect to 100 parts by mass of the first rubber component.

[0087] The proportion of the metal powder is, for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the first rubber component.

[0088] The total proportion of the other components (the first other components) is, for example, 5 to 300 parts by mass, preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, even more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the first rubber component.

[0089] [Stretching rubber layer] The V-belt for transmission of the present invention may further include a stretching rubber layer formed of a rubber composition (vulcanized rubber composition) containing a second rubber component.

[0090] As the second rubber component, it can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The second rubber component may be a rubber component different from the first rubber component, but usually it is the same as the first rubber component.

[0091] The rubber composition may further include short fibers (second short fibers), and as the second short fibers, it can be selected from the short fibers exemplified as the first short fibers, including preferred embodiments. The average fiber diameter and average fiber length of the second short fibers can also be selected from the range of the first short fibers, including preferred embodiments. The second short fibers may be short fibers different from the first short fibers, but usually they are the same as the first short fibers.

[0092] The rubber composition may further include other components (second other components), and as the second other components, it can be selected from the other components exemplified as the first other components, including preferred embodiments. The second other components may be other components different from the first other components, but usually they are the same as the first other components.

[0093] [Core layer] The core layer only needs to contain the core wire as the core, and it may be a core layer formed only of the core wire. However, from the viewpoint of suppressing delamination between layers and improving belt durability, it is preferably a core layer (adhesive rubber layer) formed of a crosslinked rubber composition in which the core wire is embedded. The adhesive rubber layer is interposed between the stretch rubber layer and the compression rubber layer main body to bond the stretch rubber layer and the compression rubber layer, and the core wire is embedded in the adhesive rubber layer.

[0094] (Adhesive rubber layer) The V-belt for transmission of the present invention may further include an adhesive rubber layer formed of a cured product of a rubber composition containing a third rubber component (crosslinked rubber composition).

[0095] As the third rubber component, it can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The third rubber component may be a rubber component different from the first rubber component, but is usually the same as the first rubber component.

[0096] The rubber composition may further contain other components (third other components), and the third other components can be selected from the other components exemplified as the first other components.

[0097] The ratio of the crosslinking agent (third crosslinking agent) is, for example, 1 to 20 parts by mass, preferably 2 to 15 parts by mass, more preferably 3 to 12 parts by mass, and even more preferably 4 to 10 parts by mass with respect to 100 parts by mass of the third rubber component.

[0098] The ratio of the filler (third filler) such as carbon black or silica is, for example, 10 to 200 parts by mass, preferably 20 to 100 parts by mass, more preferably 30 to 80 parts by mass, and even more preferably 40 to 70 parts by mass with respect to 100 parts by mass of the third rubber component.

[0099] The ratio of the adhesion improver is, for example, 1 to 20 parts by mass, preferably 2 to 15 parts by mass, and more preferably 3 to 10 parts by mass with respect to 100 parts by mass of the third rubber component.

[0100] The total proportion of the third other component 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 even more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the third rubber component.

[0101] The average thickness of the adhesive rubber layer is, for example, 0.8 to 3 mm, preferably 1.2 to 2.8 mm, and more preferably 1.5 to 2 mm.

[0102] [Reinforcing fabric] The V-belt for transmission of the present invention may further include a reinforcing fabric. Examples of the form of the reinforcing fabric include a form of laminating on the inner peripheral surface of the compression rubber layer, a form of laminating on the outer peripheral surface of the extension rubber layer, and a form of embedding in the compression rubber layer and / or the extension rubber layer.

[0103] The reinforcing fabric can be formed of, for example, a fabric material such as a woven fabric, a wide-angle canvas, a knitted fabric, or a non-woven fabric (particularly, a woven fabric). If necessary, it can be treated with an adhesive treatment, for example, treated (dipped, etc.) with an RFL solution, or subjected to a friction treatment of kneading an adhesive rubber into the fabric material, or after laminating the adhesive rubber and the fabric material, it can be laminated or embedded in the compression rubber layer and / or the extension rubber layer in the above form.

[0104] [Manufacturing method of V-belt for transmission] The manufacturing method of the V-belt for transmission of the present invention (particularly, a low-edge V-belt) is not particularly limited. For example, the manufacturing method of the low-edge cogged V-belt of the present invention is also not particularly limited. Regarding the lamination process of each layer (manufacturing method of the belt sleeve), a conventional method can be used according to the type of the belt. For example, a typical manufacturing method of the low-edge cogged V-belt will be described below.

[0105] First, a laminate of a reinforcing cloth (lower cloth) and a sheet for a compression rubber layer body (uncured rubber sheet) is placed with the reinforcing cloth on the lower side and brought into contact with a flat cogged mold in which teeth and grooves corresponding to the inner peripheral cog portions (the cog peak portions 1a and cog bottom portions 1b shown in FIG. 2) are alternately arranged, and pressurized at a temperature of 60 to 100°C (particularly 70 to 80°C) to mold the inner peripheral cog portions, thereby producing a cog pad (a pad that is not completely crosslinked and is in a semi-crosslinked state). Then, both ends of this cog pad are vertically cut from appropriate positions (particularly the top of the cog peak portion) to obtain the required length.

[0106] Next, an inner female mold in which teeth and grooves corresponding to the cog portions are alternately arranged is placed on the outer periphery of a cylindrical mold, and the cog pad is wound around by engaging with the teeth and grooves of the inner female mold and joined at both ends (particularly the top of the cog peak portion). After laminating a sheet for a first adhesive rubber layer (lower adhesive rubber: uncured rubber sheet) on the outer periphery of this cog pad, a core wire (twisted cord) forming a core is spirally spun, and a sheet for a second adhesive rubber layer (upper adhesive rubber: uncured rubber sheet) and a sheet for an extension rubber layer (uncured rubber sheet) are sequentially wound around it to produce an uncured molded body. Further, if necessary, a reinforcing cloth (upper cloth) may be laminated on the extension rubber layer.

[0107] Thereafter, with the uncured molded body covered with a jacket, it is placed in a known crosslinking device (such as a vulcanizing kettle), and crosslinking molding is performed at a temperature of 120 to 200°C (particularly 150 to 180°C) to produce a crosslinked belt sleeve. Then, using a cutter or the like, it is cut in a V shape to obtain an endless low-edge cogged V-belt.

[0108] In the case of a low-edge double cogged V-belt, with an outer female mold in which teeth and grooves corresponding to the outer peripheral cog portions are alternately arranged placed on the outer periphery of the uncured molded body and covered with a jacket, crosslinking molding is performed to obtain a crosslinked belt sleeve having cog portions also formed on the outer peripheral surface, and it is cut in a V shape to obtain a low-edge double cogged V-belt.

[0109] Incidentally, the adhesive rubber layer can be formed of a plurality of sheets for the adhesive rubber layer, and the core wire (twisted cord) forming the core body may be spun in association with the lamination order of the plurality of sheets for the adhesive rubber layer according to the embedding position in the adhesive rubber layer.

Example

[0110] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Details of the materials used in the examples and comparative examples, and the evaluation methods of the examples and comparative examples are shown below.

[0111] [Materials Used] (Rubber Component) Chloroprene rubber: "PM-40" manufactured by Denka Co., Ltd. Carboxyl-modified NBR latex (COOH-modified NBR): "Nipol 1571CL" manufactured by Nippon Zeon Co., Ltd., active ingredient 38% by mass, high-nitrile type

[0112] (Hardener) Polycarbodiimide dispersion: "Carbodilite E-02" manufactured by Nisshinbo Chemicals Inc., active ingredient 40% by mass, NCN (carbodiimide) equivalent 445 Polymeric isocyanate (polymeric MDI): "Millionate (registered trademark) MR-200" manufactured by Tosoh Corporation, NCO content 30% by mass

[0113] (Short Fibers) The following short fibers were used for the short fibers. For each short fiber, an adhesion treatment of dipping in an RFL solution [a mixed solution of 2.6 parts by mass of resorcinol, 1.4 parts by mass of 37% formalin, 17.2 parts by mass of vinyl pyridine-styrene-butadiene copolymer latex (manufactured by Nippon Zeon Co., Ltd.), and 78.8 parts by mass of water] and drying was performed. The adhesion rate of the adhesion component (solid content) was adjusted to 6% by mass with respect to the short fibers before the treatment.

[0114] Para-aramid short fiber: "Twaron" manufactured by Teijin Limited, fiber length 3 mm Nylon 66 short fiber: "Leona" manufactured by Asahi Kasei Corporation, fiber length 3 mm

[0115] (Filler) Carbon black FEF: "Seast SO" manufactured by Tokai Carbon Co., Ltd. Silica: "Nipsil VN3" manufactured by Tosoh Silica Corporation

[0116] (Additive) Naphthenic oil: "Diana Process Oil NS-90S" manufactured by Idemitsu Kosan Co., Ltd. Adhesion improver A (resorcinol formaldehyde co-condensate): "POWERPLAST PP-1860" manufactured by Singh Plasticisers & Resins Adhesion improver B (hexamethoxymethylmelamine): "POWERPLAST PP-1890S" manufactured by Singh Plasticisers & Resins Magnesium oxide: "Kyowa Mag 150" manufactured by Kyowa Chemical Industry Co., Ltd. Vulcanization accelerator MBTS (dibenzothiazyl disulfide): "Nocceler DM" manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization accelerator TMTD (tetramethylthiuram disulfide): "Nocceler TT" manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Antioxidant A (octyldiphenylamine): "Nonflex OD-3" manufactured by Seiko Chemical Co., Ltd. Antioxidant B (4,4'-bis(α,α-dimethylbenzyl)diphenylamine): "Nonflex DCD" manufactured by Seiko Chemical Co., Ltd. Antioxidant C (microcrystalline wax): "Santite C" manufactured by Seiko Chemical Co., Ltd. Zinc powder: "M-11" manufactured by Sakai Chemical Industry Co., Ltd. Softening agent: "Adeka Sizer C-8" manufactured by ADEKA Corporation Stearic acid: "Bead Stearic Acid Camellia" manufactured by NOF Corporation Zinc oxide: "Zinc Oxide (JIS Standard Type 2)" manufactured by Hakusui Tech Co., Ltd. Co-crosslinking agent (N,N'-m-phenylenedimaleimide): "Barnock PM" manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0117] (Core wire) The core wire used was as follows. All core wires were subjected to an adhesion treatment using the following treatment method. The adhesion rate (final adhesion rate after the third treatment step) of the adhesion component (solid content) was adjusted to 15% by mass with respect to the core wire before treatment (before the first treatment step).

[0118] Aramid core wires of Examples 1 to 3: Two single-twisted yarns obtained by single-twisting an aramid fiber bundle of 1670 dtex ("Technora" manufactured by Teijin Limited) at a single-twist coefficient of 1.0 were combined and then double-twisted at a double-twist coefficient of 3.0 in the same direction as the single-twist to obtain a lang lay cord with a total fineness of 3340 dtex (the diameter of the treated cord was approximately 0.70 mm and the tensile strength per core wire was 620 N).

[0119] Polyester core wires used in Comparative Examples 1 to 3: Three single-twisted yarns obtained by single-twisting a PET fiber bundle of 1100 dex ("Tetoron" manufactured by Toray Industries, Inc.) at a single-twist coefficient of 3.0 were combined and then double-twisted at a double-twist coefficient of 3.0 in the opposite direction to the single-twist to obtain a complex lay cord with a total fineness of 6600 dtex (the diameter of the treated cord was approximately 1.00 mm and the tensile strength per core wire was 440 N).

[0120] Aramid core wires used in Comparative Examples 4, 7, and 10: Two single-twisted yarns obtained by single-twisting an aramid fiber bundle of 1670 dtex ("Technora" manufactured by Teijin Limited) at a single-twist coefficient of 1.0 were combined and then double-twisted at a double-twist coefficient of 3.0 in the opposite direction to the single-twist to obtain a complex lay cord with a total fineness of 3340 dtex (the diameter of the treated cord was approximately 0.71 mm and the tensile strength per core wire was 620 N).

[0121] Aramid core wires used in Comparative Examples 5, 8, and 11: Three single-twisted yarns obtained by single-twisting an aramid fiber bundle of 1100 dtex ("Technora" manufactured by Teijin Limited) at a single-twist coefficient of 1.0 were combined and then double-twisted at a double-twist coefficient of 3.0 in the same direction as the single-twist to obtain a lang lay cord with a total fineness of 6600 dtex (the diameter of the treated cord was approximately 0.94 mm and the tensile strength per core wire was 1300 N).

[0122] Aramid core wires used in Comparative Examples 6, 9, and 12: Two 1100 dtex aramid fiber bundles ("Technora" manufactured by Teijin Limited) were combined, and the resulting two-folded yarn was twisted in the Z-direction with a twist factor of 1.0. Then, three of these Z-twisted yarns were combined and S-twisted with a twist factor of 3.0 in the opposite direction to the Z-twist to form a multi-twisted cord with a total fineness of 6600 dtex (the diameter of the treated cord was approximately 0.95 mm, and the tensile strength per core wire was 1300 N).

[0123] The details of the core wires used in Examples 1 to 3 and Comparative Examples 1 to 12 are summarized in Table 1.

[0124]

Table 1

[0125] (Method for Adhering Core Wire) (A) Preparation of the First Treatment Agent To the RFL solution having the composition shown in Table 2, a polycarbodiimide dispersion and water were mixed at the ratios shown in Table 3, and the mixture was stirred at room temperature for 10 minutes to prepare the first treatment agent having the composition shown in Table 3.

[0126]

Table 2

[0127]

Table 3

[0128] (B) Preparation of the Second Treatment Agent The RFL solution having the composition shown in Table 2 and water were mixed at the ratios shown in Table 4, and the mixture was stirred at room temperature for 10 minutes to prepare the second treatment agent having the composition shown in Table 4.

[0129]

Table 4

[0130] (C) Preparation of the Third Treatment Agent The rubber composition for the adhesive rubber layer described below was dissolved in toluene at the ratios shown in Table 5, and polymeric isocyanate was added to prepare a third treatment agent (rubber paste).

[0131]

Table 5

[0132] (D) Adhesion treatment The untreated twisted cord was immersed in the first treatment agent for 10 seconds and dried under the conditions of 150°C for 2 minutes (first treatment step). Next, the twisted cord treated with the first treatment agent was immersed in the second treatment agent for 10 seconds and dried under the conditions of 230°C for 2 minutes (second treatment step). Finally, the twisted cord treated with the second treatment agent was immersed in the third treatment agent for 3 seconds, and the dipping and drying treatment under the conditions of 100°C for 1 minute was repeated 3 times, and then heat-treated at 230°C for 2 minutes to obtain a core wire (third treatment step).

[0133] (Reinforcing fabric) A canvas (basis weight 180 g / m 2 ) was obtained by plain weaving 10 - sized cotton yarns at a yarn density of 70 yarns / 50 mm. A treated canvas (thickness of about 0.5 mm, basis weight of about 450 g / m 2 ) in which the rubber composition for the adhesive rubber layer was kneaded into the canvas was used as the reinforcing fabric. The same reinforcing fabric was used for both the inner peripheral side and the outer peripheral side of the belt.

[0134] [Belt elongation rigidity EA] The test belt was hung on a measuring machine (belt length measuring machine) with a pair of V - grooved pulleys having the same pitch diameter arranged vertically, and a load was applied to the lower pulley in the direction in which the two pulleys separated. At this time, the belt tension (the tension acting on one - side span of the belt located between the two pulleys) was 1 / 2 of the load applied to the lower pulley.

[0135] Specifically, the belt length when the belt tension was 200 N was taken as the reference length (belt length change rate 0%), the belt tension was changed from 200 N to 600 N, and the belt length change rate with respect to the reference length was recorded. The measurement temperature was adjusted to 25°C.

[0136] Regarding the measurement results, a graph with the belt length change rate (%) on the horizontal axis and the belt tension (N) on the vertical axis was created. The values at five points where the belt tension was 200 N, 300 N, 400 N, 500 N, and 600 N were linearly approximated, and the slope of the approximate straight line was taken as the elongation stiffness EA (unit: N) of the belt. The elongation stiffness EA was expressed as the value per belt or the value per 1 mm of pitch width divided by the pitch width of the belt.

[0137] [Bending stiffness EI of the belt] By attaching the upper plate 42 and the lower plate 43 for compressing the belt of the test piece from the back to the autograph, an annular belt 41 was arranged between the upper and lower plates 42 and 43 as shown in Fig. 8. The distance between the plates was narrowed at a speed of 100 mm / min, and the compressive force (bending load) was measured and recorded at six points when the pitch diameter D was 110 mm, 100 mm, 90 mm, 80 mm, 70 mm, and 60 mm at a measurement temperature of 25°C. Regarding the measurement results, the bending stiffness EI at six points was calculated using the following formula, and the average value (arithmetic mean) was obtained.

[0138] Bending stiffness EI = (compressive force × (pitch diameter D / 2) 2 ) / 2 (unit: N(mm) 2 )

[0139] The bending stiffness EI is expressed as the value per belt or the value per 1 mm of pitch width divided by the pitch width of the belt.

[0140] [Endurance test 1 (peel resistance test)] The peel resistance test was conducted using a two-axis running test machine consisting of a driving (Dr.) pulley with a diameter of 60 mm and a driven (Dn.) pulley with a diameter of 140 mm as shown in Fig. 9. An L-edge V-belt was mounted on these two pulleys, and the shaft load was set to 700 N, the rotational speed of the driving pulley was set to 6000 rpm, the torque of the driving pulley was set to 15 N·m, and the belt was run at an ambient temperature of 80°C. While measuring the side surface temperature of the belt during running with a non-contact thermometer ("THI-500" manufactured by Ichinen TASCO Co., Ltd.), the time until peeling occurred on the lower side of the core wire (inner peripheral side of the belt) was compared.

[0141] [Endurance Test 2 (Crack Resistance Test)] The crack resistance test was conducted using a two-axis running test machine consisting of a driving (Dr.) pulley with a diameter of 120 mm and a driven (Dn.) pulley with a diameter of 80 mm as shown in Fig. 10. An L-edge V-belt was mounted on these two pulleys, and the shaft load was set to 400 N, the rotational speed of the driving pulley was set to 6000 rpm, the torque of the driving pulley was set to 12 N·m, and the belt was run at an ambient temperature of 120°C. While measuring the side surface temperature of the belt during running with a non-contact thermometer ("THI-500" manufactured by Ichinen TASCO Co., Ltd.), the time until cracks occurred in the cog valley was compared.

[0142] Example 1 and Comparative Examples 1 and 4 - 6 (Formation of Rubber Layer) As the rubber compositions in Table 6 (adhesive rubber layer) and Table 7 (compression rubber layer and extension rubber layer), rubber kneading was performed using a known method such as a Banbury mixer, respectively, and the obtained kneaded rubber was passed through calender rolls to produce rolled rubber sheets (sheets for adhesive rubber layer, sheets for compression rubber layer, sheets for extension rubber layer).

[0143]

Table 6

[0144]

Table 7

[0145] (Manufacture of Belt) A laminate of a reinforcing fabric (bottom fabric) and a sheet for a compression rubber layer (uncured rubber) was placed in a flat cogged mold with teeth and grooves arranged alternately corresponding to the cog portions, with the reinforcing fabric facing downwards. By pressing the laminate at 75°C, a cog pad (not fully cross-linked and in a semi-cross-linked state) with the cog portions shaped was produced. Next, both ends of this cog pad were cut vertically from the top of the cog crest portion.

[0146] Next, an internal female mold with teeth and grooves arranged alternately corresponding to the cog portions was covered with a cylindrical mold, and the cog pad was wound around by engaging with the teeth and grooves of the internal female mold and joined at the top of the cog crest portion. After laminating a first adhesive rubber layer sheet (bottom adhesive rubber, uncured rubber, the same as the adhesive rubber layer sheet) on the outer periphery of the wound cog pad, a core wire was spun spirally, and a second adhesive rubber layer sheet (top adhesive rubber, the same as the adhesive rubber layer sheet), an extension rubber layer sheet (uncured rubber), and a reinforcing fabric (top fabric) were sequentially wound around the outer periphery to produce an uncured molded body. The short fibers were oriented in the belt width direction. The core wire pitch was 0.9 mm for Example 1 and Comparative Example 4, and 1.1 mm for Comparative Examples 1 and 5 - 6.

[0147] Thereafter, a jacket was put on the uncured molded body and the mold was placed in a vulcanizing autoclave, and it was cross-linked and molded at a temperature of 160°C for 20 minutes to obtain a belt sleeve. This belt sleeve was cut with a cutter in the belt longitudinal direction into a V-shaped cross-sectional shape with a predetermined width. Then, this belt sleeve was finished into a belt having the structure shown in Figure 2, that is, a low-edge cogged V-belt (size: upper width 24 mm, thickness 11 mm, V angle 30 degrees, outer peripheral length 900 mm, pitch width 23 mm), which is a variable-speed belt having cogs on the inner peripheral side of the belt.

[0148] The evaluation results of the belts obtained in Example 1 and Comparative Examples 1 and 4 - 6 are shown in Table 8.

[0149]

Table 8

[0150] Example 2 and Comparative Examples 2 and 7 to 9 Without using the top cloth, with a jacket put on in a state where an external female mold in which tooth portions and groove portions corresponding to the outer peripheral cog portions are alternately arranged is put on the outer periphery of the crosslinked molded body, crosslinking molding is performed. A low-edge double-cogged V-belt (size: top width 25 mm, thickness 10 mm, V angle 30 degrees, outer peripheral length 900 mm, pitch width 23 mm) was obtained in the same manner as in Example 1 except that a crosslinked belt sleeve having cog portions formed on the outer peripheral surface was manufactured. The core wire pitch was 0.9 mm for Example 2 and Comparative Example 7, and 1.1 mm for Comparative Examples 2 and 8 to 9.

[0151] Table 9 shows the evaluation results of the belts obtained in Example 2 and Comparative Examples 2 and 7 to 9.

[0152]

Table 9

[0153] Example 3 and Comparative Examples 3 and 10 to 12 Without using the top cloth, with a jacket put on in a state where an external female mold in which tooth portions and groove portions corresponding to the outer peripheral cog portions are alternately arranged is put on the outer periphery of the crosslinked molded body, crosslinking molding is performed. A low-edge double-cogged V-belt (size: top width 25 mm, thickness 9 mm, V angle 30 degrees, outer peripheral length 900 mm, pitch width 23 mm) was obtained in the same manner as in Example 1 except that a crosslinked belt sleeve having cog portions formed on the outer peripheral surface was manufactured. The core wire pitch was 0.9 mm for Example 3 and Comparative Example 10, and 1.1 mm for Comparative Examples 3 and 11 to 12.

[0154] Table 10 shows the evaluation results of the belts obtained in Example 3 and Comparative Examples 3 and 10 to 12.

[0155]

Table 10

[0156] As is clear from the results in Tables 8 to 10, in belts of any type and size, the examples using the wrap-twist cords of aramid fibers with a total fineness of 3500 dtex or less had higher elongation rigidity and lower bending rigidity than the comparative examples. Also, it was confirmed that the belts of the examples maintained a low temperature on the belt side surface and were excellent in peel resistance and crack resistance.

[0157] Specifically, in Comparative Examples 1 to 3, since the core wire was formed of polyester fibers, had a large total fineness, and had a complex twist, the bending rigidity was high, the belt temperature rose, and the durability was low.

[0158] In Comparative Examples 4, 7, and 10, since the twist of the core wire was a complex twist, the bending rigidity was high, the belt temperature rose, and the durability was low.

[0159] In Comparative Examples 5, 8, and 11, since the total fineness of the core wire was large, the bending rigidity was high, the belt temperature rose, and the durability was low.

[0160] In Comparative Examples 6, 9, and 12, since the total fineness of the core wire was large and it had a complex twist, the bending rigidity was high, the belt temperature rose, and the durability was low.

Industrial Applicability

[0161] The V-belt for transmission of the present invention can be applied to a low-edge V-belt, a low-edge cogged V-belt having a cog portion, etc. In particular, it is a V-belt (variable speed belt or CVT belt) used in a transmission (continuously variable transmission) in which the speed ratio changes steplessly during belt running. For example, it can be suitably used for a low-edge cogged V-belt, a low-edge double-cogged V-belt used in continuously variable transmissions of motorcycles, ATVs (four-wheel buggies), snowmobiles, etc. In particular, it can be suitably used for a low-edge cogged V-belt, a low-edge double-cogged V-belt used in continuously variable transmissions of scooters with a small displacement (e.g., 250 cc or less, preferably 160 cc or less).

Explanation of Signs

[0162] 1…Low-edge cogged V-belt 11… Lower-edge double cogged V-belt 2, 6, 16… Reinforcing fabric 3, 13… Elastomeric extension layer 4, 14… Core layer 4a, 14a… Core wire 5, 15… Compression rubber layer

Claims

1. A V-belt for transmission, formed of a lang lay cord formed by combining and twisting multiple lower-twisted yarns containing aramid fibers and having a core yarn with a total fineness of 1000 to 3500 dtex.

2. The V-belt for transmission according to Claim 1, wherein the tensile strength per single core yarn is 500 to 1000 N.

3. The V-belt for transmission according to Claim 1 or 2, wherein in the core yarn, the twist coefficient of the lower-twisted yarn is 0.5 to 3, and the twist coefficient of the lang lay cord is 0.5 to 5.

4. The V-belt for transmission according to any one of Claims 1 to 3, wherein the pitch of the core yarn is 0.05 to 0.25 mm larger than the average diameter of the core yarn.

5. The V-belt for transmission according to any one of Claims 1 to 4, wherein the average diameter of the core yarn is 0.4 to 1 mm.

6. The V-belt for transmission according to any one of Claims 1 to 5, wherein the elongation rigidity per 1 mm of the pitch width of the V-belt for transmission is 6500 to 20000 N.

7. The bending rigidity per millimeter of pitch width of the V-belt for transmission is 40 to 260 N / mm ２ The V-belt for transmission according to any one of claims 1 to 6, which is such that

8. The V-belt for transmission according to any one of Claims 1 to 7, having a thickness of 5 to 12 mm and a pitch width of the V-belt for transmission of 10 to 25 mm.

9. The V-belt for transmission according to any one of Claims 1 to 8, being a low-edge V-belt having cogs at least on the inner circumferential surface side.

10. The V-belt for transmission according to any one of Claims 1 to 9, being a variable-speed belt used for a small belt-type continuously variable transmission.

11. A belt transmission mechanism including the V-belt for transmission according to any one of Claims 1 to 10 and a pulley.

12. The belt transmission mechanism according to Claim 11, wherein the V-belt for transmission is a low-edge V-belt having cogs at least on the inner circumferential surface side and is a variable-speed belt used for a small belt-type continuously variable transmission.

Images