WO2023090423A1 - Transmission belt - Google Patents

Abstract

The present invention provides a transmission belt 1 including a compression rubber layer 2 and an adhesion rubber layer 4 provided on one side of the compression rubber layer 2 in a thickness direction and in which a core wire 5 extending in a belt length direction is buried. In the transmission belt 1, at least a portion of the adhesion rubber layer 4 is made of a first rubber composition, and the portion of the adhesion rubber layer 4 made of the first rubber composition has a modulus of 4.0 MPa or more at 50% elongation at 120°C.

Description

transmission belt

The present invention relates to transmission belts.

A transmission belt is conventionally known as a means of transmitting power from the driving side to the driven side. As such a transmission belt, for example, Patent Document 1 discloses an adhesive rubber layer in which a core wire extending in the belt length direction is embedded, and a compression rubber layer provided on the belt bottom side of the adhesive rubber layer, A transmission belt is disclosed in which the adhesive rubber layer is composed of a highly elastic rubber composition in which short fibers are mixed and dispersed and which has an elastic modulus substantially equal to that of the compression rubber layer.

Japanese Patent No. 3721220

By the way, the power transmission belt is subjected to a high load due to large stress and distortion during use, and heat-generating parts may be arranged around it, so it tends to become hot. In particular, transmission belts tend to become hot when used in areas with high temperatures. It is desired that the transmission belt has durability so that the transmission efficiency of the transmission belt does not decrease even under such circumstances.

Also, in transmission belts, the adhesive rubber layer is prone to damage. This is because the adhesive rubber layer exists between the compressed rubber layer that mainly performs the function of power transmission and the core wire that does not elastically deform like the compressed rubber layer, so that the stress generated by the function of power transmission is absorbed by the adhesive rubber layer. As a result, the adhesive rubber layer tends to become the starting point of fracture.

Based on the above, the object of the present invention is to improve the durability of the adhesive rubber layer of the transmission belt under high load and high temperature.

The present invention is a power transmission belt comprising a compressed rubber layer and an adhesive rubber layer provided on one side in the thickness direction of the compressed rubber layer and having core wires embedded therein extending in the longitudinal direction of the belt, At least part of the rubber layer is composed of the first rubber composition, and the part composed of the first rubber composition has a modulus of 4.0 MPa or more at 50% elongation at 120°C.

According to the present invention, at least part of the adhesive rubber layer is composed of the first rubber composition, and the part composed of the first rubber composition has a modulus of 4.0 MPa or more at 50% elongation at 120°C. so that the adhesive rubber layer has high durability under high load and high temperature.

1 is a perspective view including a cross section of a V-ribbed belt according to an embodiment; FIG. FIG. 4 is a belt layout diagram for running durability tests in each example and each comparative example. 3D images showing the results of a belt model and stress-strain distribution analysis in Example 2. FIG. FIG. 3 is a view corresponding to FIG. 3 in Comparative Example 1;

The embodiment will be described in detail below.

(embodiment)
<Configuration of V-ribbed belt>
A V-ribbed belt 1 (transmission belt) according to the embodiment is formed in a ring shape. As shown in FIG. 1, the inner peripheral side of the V-ribbed belt 1 contacts the pulley in the belt thickness direction.

The V-ribbed belt 1 includes a compression rubber layer 2. A plurality of ribs 3 extending in the belt length direction are provided on the inner peripheral side of the compression rubber layer 2 . As shown in FIG. 1, each rib 3 is formed in a trapezoidal shape that becomes narrower toward the inner peripheral side in a cross-sectional view taken perpendicularly to the belt length direction.

The V-ribbed belt 1 also includes an adhesive rubber layer 4 provided on the outer peripheral side (one side in the thickness direction) of the compression rubber layer 2 . A plurality of core wires 5 extending in the belt length direction are embedded in the adhesive rubber layer 4 . The plurality of core wires 5 are arranged side by side at regular intervals in the belt width direction. Each center of the plurality of core wires 5 is positioned at the center in the thickness direction of the adhesive rubber layer 4 as shown in FIG. The core wires 5 are made of resin fibers such as polyethylene terephthalate, polyethylene naphthalate, aromatic polyamide, 4,6 nylon, 6 nylon, and 6,6 nylon, for example.

The V-ribbed belt 1 also includes a back rubber layer 6 provided on the outer peripheral side of the adhesive rubber layer 4 . Each of the layers 2, 4, and 6 described above are formed continuously over the entire belt length direction and belt width direction.

As a feature of the present invention, the adhesive rubber layer 4 has a modulus of 4.0 MPa or more at 50% elongation at 120° C., preferably 4 .3 MPa or more, it is composed of the first rubber composition. In the present embodiment, the entire adhesive rubber layer 4 is made of the first rubber composition, but part of the adhesive rubber layer 4 is made of the first rubber composition as in the first to fourth modifications described later. may be composed of

In addition, from the viewpoint of ensuring high durability under high temperature and high load, the adhesive rubber layer 4 preferably has a durometer hardness (Shore A) of 86 or more according to JIS K 6253, preferably 89 or more. is more preferable.

The compression rubber layer 2 and the back rubber layer 6 may be composed of the first rubber composition, and if the rubber composition is normally used for the power transmission belt 1, the rubber composition is different from the first rubber composition. It may be composed of a composition.

The first rubber composition will be described below.

<First rubber composition>
The first rubber composition contains a rubber component and a cross-linking agent for cross-linking the rubber component. The rubber component preferably contains an ethylene-α-olefin elastomer from the viewpoint of ensuring high durability under high temperature and high load. Examples of ethylene-α-olefin elastomers include ethylene-propylene copolymers, ethylene-propylene-diene-terpolymers, ethylene-octene copolymers, ethylene-butene copolymers, and the like. Ethylene-propylene-diene-terpolymers are preferred.

Examples of cross-linking agents include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,5- Dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate, t-butylperoxy-2- ethyl-hexyl carbonate, α,α'-di-(t-butylperoxy)diisopropylbenzene, 1,1-di-(t-butylperoxy)cyclohexane and the like.

In addition, the first rubber composition may contain compounding agents other than the rubber component and the cross-linking agent. Examples of such compounding agents include fillers such as carbon black, silica, calcium carbonate, and talc. and silica. Examples of carbon black include furnace black, channel black, thermal black, acetylene black and the like. Compounding agents other than fillers include zinc oxide, stearic acid, processing aids, anti-aging agents, hydrolysis stabilizers, paraffin-based process oils, co-crosslinking agents, and the like. The first rubber composition may contain other compounding agents commonly used in rubber compositions for power transmission belts.

A modified example of this embodiment will be described below. In addition, in the following description, the description of the configuration common to this embodiment will be omitted.

(First modification of the embodiment)
In the above-described embodiment, the adhesive rubber layer 4 is entirely composed of the first rubber composition, but in the first modified example, the adhesive rubber layer 4 is the first layer composed of the first rubber composition. and a second layer made of a second rubber composition. The first layer is provided directly above the compression rubber layer 2, and the second layer is provided directly above the first layer.

The second rubber composition differs from the first rubber composition in at least one of the types of constituent components and the content of each constituent component. Also, the second rubber composition may be such that the modulus of the second layer at 50% elongation at 120° C. is less than 4.0 MPa, unlike the first layer.

As shown in Examples described later, the adhesive rubber layer 4 tends to be more distorted on the side of the compression rubber layer 2 than on the side of the back rubber layer 6 . Therefore, if the first layer provided on the side of the compression rubber layer 2 is composed of the first rubber composition as in this modification, high durability can be obtained under high temperature and high load of the adhesive rubber layer 4. be done. On the other hand, the types and contents of the components constituting the second rubber composition of the second layer can be freely selected from various viewpoints such as manufacturing cost. That is, according to this embodiment, the degree of freedom in selecting the second rubber composition to be used on the back rubber layer 6 side of the adhesive rubber layer 4 is increased.

For example, the second rubber composition may be selected as follows. It is believed that the second layer is less strained during use than the first layer, as shown in the examples below. Therefore, the material of the second rubber composition may be selected such that the second layer has a lower elastic modulus than the first layer. By doing so, the V-ribbed belt 1 can be highly durable in the first layer, and the energy loss due to the stress caused by the bending of the V-ribbed belt 1 can be reduced in the second layer. As a result, further improvement in transmission efficiency can be obtained, and power consumption can be reduced.

By the way, it is conceivable that the adhesive rubber layer 4 is greatly distorted at the portion in contact with the core wire 5 due to the difference in material between the adhesive rubber layer 4 and the core wire 5 . Further, as will be described later in Examples, the adhesive rubber layer 4 tends to be more distorted particularly on the side of the compression rubber layer 2 that mainly serves to transmit power than on the side of the back rubber layer 6 . Considering the above, from the viewpoint of achieving extremely high durability under high temperature and high load, the first layer should be placed on the inner peripheral side (i.e., , compression rubber layer 2 side). In this case, in the configuration of FIG. 1, the interface between the first layer and the second layer is the center of the adhesive rubber layer 4 in the belt thickness direction.

(Second modification of the embodiment)
In the second modification, the adhesive rubber layer 4 includes first portions provided along both ends in the belt width direction and second portions provided along the central portion in the belt width direction. The first part is composed of the first rubber composition and the second part is composed of the second rubber composition.

As shown in Examples described later, the adhesive rubber layer 4 is likely to be greatly distorted at both ends in the belt width direction. For this reason, if the first portions provided at both ends in the width direction of the belt are made of the first rubber composition as in this modified example, the durability of the V-ribbed belt 1 under high temperature and high load can be obtained. The types and contents of the components constituting the second rubber composition can be freely selected from various viewpoints such as manufacturing cost. That is, according to this embodiment, the degree of freedom in selecting the second rubber composition to be used in the central portion of the adhesive rubber layer 4 in the belt width direction is increased. For example, the second rubber composition may be used so that the second part has a lower elastic modulus than the first part for the same reason as in the first modified example.

(Third modification of the embodiment)
Instead of the above-described first and second modifications, for example, only the portions along both ends in the belt width direction in the adhesive rubber layer 4 (that is, the portions corresponding to the first portions in the second modification) are doubled. It has a layered structure, and the layer on the side of the compression rubber layer 2 (that is, the layer corresponding to the first layer in the first modification) of the two layers is composed of the first rubber composition, and the other parts are composed of the second rubber It may be composed of a composition. In this case, as described in the first modified example, the layer on the side of the compression rubber layer 2 is composed of the embedded core wires 5 from the viewpoint of achieving extremely high durability under high temperature and high load. It is preferable that it is provided on the entire inner peripheral side (that is, the compression rubber layer 2 side) of the central portion of the cross section. In this case, in the configuration of FIG. 1, the interface between the first layer and the second layer is the center of the adhesive rubber layer 4 in the belt thickness direction.

(Fourth modification of the embodiment)
Instead of the above-described first to third modifications, for example, only the portion along the belt width direction central portion of the adhesive rubber layer 4 (that is, the portion corresponding to the second portion of the second modification) has a two-layer structure. Of the two layers, the layer on the back rubber layer 6 side (that is, the layer corresponding to the second part of the first modification) is composed of the second rubber composition, and the other parts are composed of the first rubber composition may be configured with

(Other embodiments)
In the above-described embodiments, the power transmission belt is a V-ribbed belt, but the power transmission belt according to the present invention is not limited to this, and may be any power transmission belt such as a V-belt or toothed belt.

Examples 1 and 2 and Comparative Examples 1 and 2 are described below.

<Manufacture of V-ribbed belt>
In Example 1, a rubber component, a cross-linking agent, a filler and other compounding agents were put into a closed kneader according to the formulation shown in Table 1 and kneaded to obtain a first composition for the uncrosslinked adhesive rubber layer 4. prepared the product. Further, each rubber composition for the compression rubber layer 2 and the back rubber layer 6 was also prepared in the same procedure.

Each rubber composition for forming the compression rubber layer 2, the adhesive rubber layer 4, and the back rubber layer 6 was formed into a sheet in an uncrosslinked state, and these were sequentially wound around a molding drum. At that time, the core wire 5 that has been subjected to the adhesion treatment is wound around the sheet for the adhesive rubber layer 4 from one end to the other end of the molding drum while being stretched with a constant tension so as not to loosen, and the adhesive rubber is further applied from above. A sheet for layer 4 was wound, thereby embedding core wire 5 in adhesive rubber layer 4 .

Finally, the molding drum around which the layers 2, 4, and 6 were wound was press-vulcanized at about 170°C for about 20 minutes to crosslink at once to form a cylindrical belt (slab). The slab was then cut to belt width to produce a V-ribbed belt. The number of ribs in the manufactured V-ribbed belt was three.

In Example 2 and Comparative Examples 1 and 2, the V-ribbed belt 1 was produced in the same manner as in Example 1, except that the rubber composition constituting the adhesive rubber layer 4 was formulated as shown in Table 1. . That is, in the V-ribbed belts 1 according to Examples 1 and 2 and Comparative Examples 1 and 2, the adhesive rubber layer 4 is composed of the rubber composition that constitutes the compression rubber layer 2, the rubber composition that constitutes the back rubber layer 6, and the like. All configurations, except for the rubber composition, are all identical to each other.

<Running durability test>
The V-ribbed belts 1 according to Examples 1 and 2 and Comparative Examples 1 and 2 obtained as described above were respectively stretched over pulleys 11 to 14 of a belt running tester 10 as shown in FIG. A sex test was performed. The belt running tester 10 includes a drive pulley 11 and a driven pulley 12 which are spaced apart from each other, an idler pulley 13 which is provided between the two pulleys 11 and 12, and an idler pulley 13 which is spaced apart. A tension pulley 14 is provided. The tension pulley 14 is provided at a position equidistant from the drive pulley 11 and the driven pulley 12, and is directed away from the idler pulley 13 as indicated by the arrow in FIG. configured to be movable. Both the driving pulley 11 and the driven pulley 12 have a pulley diameter of 120 mm, and a V-groove is formed on the outer periphery. The idler pulley 13 has a pulley diameter of 80 mm, and the tension pulley 14 has a pulley diameter of 55 mm.

The running durability test was performed by applying a tension of 120 kg to the V-ribbed belt 1 with the tension pulley 14 at a temperature of 120°C and rotating the drive pulley 11 at 4900 rpm.

Table 2 shows the physical properties of the adhesive rubber layer 4 and the running durability test results for Examples 1 and 2 and Comparative Examples 1 and 2. Specifically, the physical properties are 50% modulus at 120° C. and durometer hardness according to JIS K 6253. The results of the running durability test are the time it took for the V-ribbed belt 1 to break (breakage resistance time) and the visually confirmed breakage conditions (which part was broken, etc.) after the breakage resistance time. be.

As shown in Table 2, the physical properties of the adhesive rubber layer 4 are such that the 50% modulus at 120° C. is 4.0 MPa (Example 1), 4.3 MPa (Example 2), 3.0 MPa (Comparative Example 1) and 3 3 MPa (Comparative Example 2) and hardnesses of 86 (Example 1), 89 (Example 2), 85 (Comparative Example 1) and 84 (Comparative Example 2).

In addition, the breakage resistance time is 250 hours (Example 1), 350 hours (Example 2), and less than 50 hours (Comparative Examples 1 and 2), respectively. By using the first rubber composition (having a 50% modulus of 4.0 MPa or more at 120° C.) for 4, the adhesive rubber layer 4 is less likely to break and has improved durability.

As for the state of damage, in Examples 1 and 2, the adhesive rubber layer 4 was not damaged and the compression rubber layer 2 was damaged, whereas in Comparative Examples 1 and 2, the adhesive rubber layer 4 was damaged. As a result, the core wire 5 protruded outside the adhesive rubber layer 4 and was exposed. From this, it can be seen that by using the first rubber composition for the adhesive rubber layer 4 as in Examples 1 and 2, the durability of the adhesive rubber layer 4 was improved.

<Stress-strain distribution analysis>
A model of the V-ribbed belts of Example 2 and Comparative Example 1 (hereinafter referred to as a belt model) was created on a computer, and a tension pulley with a pulley diameter of 55 mm applied a tension of 120 kg to simulate the stress caused by this tension. The strain distribution generated in the belt model due to the stress was calculated (hereinafter, this analysis is referred to as stress-strain distribution analysis). For this simulation, general-purpose FEM analysis software "Abaqus" manufactured by Intermesh Japan Co., Ltd. was used.

Specifically, in the belt models of Example 2 and Comparative Example 1, the adhesive rubber layer 4 of Example 2 and Comparative Example 1 as shown in Table 1 was subjected to a tensile test (JIS K6251) and a compression test (JIS K6254) was constructed by inputting the stress-strain curve obtained by performing. The strain distribution was calculated by dividing the belt model into grid-shaped volume elements as shown in FIG. 3, and calculating the stress applied to each volume element and the resulting strain by the finite element method (FEM).

3 and 4 show a part of a 3D image showing only the adhesive rubber layer 4 in the belt model according to Example 2 and Comparative Example 1, respectively, and the magnitude of distortion (distortion value) for each volume element of the belt model. ) are displayed in grayscale, and the results of the stress-strain distribution analysis of the belt model are shown. The strain value shown in FIGS. 3 and 4 is a value obtained by dividing the dimensional deformation amount (m) of each volume element deformed under stress by the size (m) of each volume element before deformation. A (+) value means a volume increase (expansion) for each volume element, and a negative (-) value means a volume decrease (compression) for each volume element.

According to FIGS. 3 and 4, in both Example 2 and Comparative Example 1, the strain values at both ends of the adhesive rubber layer 4 in the belt width direction are larger than at the central portion in the belt width direction. In both Example 2 and Comparative Example 1, the volume element with the maximum strain value was located on the innermost side of the adhesive rubber layer 4 in the belt thickness direction (compression rubber layer 2 side).

From the above, the distortion of the adhesive rubber layer 4 is that both ends in the belt width direction are larger than the central portion in the belt width direction, and that the inner circumference side in the belt thickness direction It can be seen that it is larger than the outer peripheral side. That is, it can be said that the durability of the adhesive rubber layer 4 can be efficiently increased by increasing the durability of at least one of the belt width direction end portions and the belt thickness direction inner peripheral side of the adhesive rubber layer 4 .

In addition, the maximum strain value among the total volume elements of the adhesive rubber layer 4 in each belt model was +0.35 in Example 2 and +0.42 in Comparative Example 1, and Example 2 was higher than Comparative Example 1. It can be said that the strain of the adhesive rubber layer 4 in the V-ribbed belt is smaller in Example 2 than in Comparative Example 1.

The minimum strain value among the total volume elements of each belt model was +2.9×10 ⁻⁴ in Example 2 and −3.7×10 ⁻⁴ in Comparative Example 1.

The present invention is useful as a transmission belt.

1 V-ribbed belt (transmission belt)
2 compression rubber layer 3 rib 4 adhesive rubber layer 5 cord 6 back rubber layer 10 belt running tester 11 drive pulley 12 driven pulley 13 idler pulley 14 tension pulley

Claims (10)

A transmission belt,
a compression rubber layer;
an adhesive rubber layer provided on one side in the thickness direction of the compression rubber layer and embedded with a core wire extending in the length direction of the belt,
At least part of the adhesive rubber layer is composed of a first rubber composition, and the portion composed of the first rubber composition has a modulus of 4.0 MPa or more at 50% elongation at 120 ° C. belt. In the transmission belt according to claim 1,
The adhesive rubber layer is
A first layer composed of the first rubber composition and provided immediately above the compression rubber layer; and a second layer arranged immediately above said first layer. In the transmission belt according to claim 1,
The adhesive rubber layer is
A first portion made of the first rubber composition and provided along the entire belt length direction at both ends in the belt width direction;
A power transmission belt comprising: a second portion formed of a second rubber composition different from the first rubber composition in at least one of the types and contents of constituent components, and provided along the central portion in the width direction of the belt. In the transmission belt according to any one of claims 1 to 3,
The transmission belt, wherein the first rubber composition contains ethylene-α-olefin as a rubber component. In the transmission belt according to any one of claims 1 to 4,
The transmission belt, wherein the first rubber composition contains at least one of silica and carbon black as a filler. In the transmission belt according to claim 2,
The power transmission belt, wherein the first layer is provided on the entire compressed rubber layer side of the core wire with respect to the cross-sectional central portion thereof. In the transmission belt according to claim 1,
The adhesive rubber layer has a two-layer structure in the entire length direction of the belt at both ends in the width direction of the belt, and a one-layer structure in the entire length direction of the belt except for the both ends in the width direction of the belt. cage,
The adhesive rubber layer is
The layer on the side closer to the compression rubber layer at both ends in the width direction of the belt having a two-layer structure is composed of the first rubber composition,
At least one of the type and content of the constituent components of the layer on the far side from the compression rubber layer and the portion having a one-layer structure at both ends in the width direction of the belt having a two-layer structure is the first rubber composition. is composed of a different second rubber composition,
transmission belt. In the transmission belt according to claim 7,
At both ends in the width direction of the belt having a two-layer structure in the adhesive rubber layer, the layer on the side closer to the compression rubber layer is provided on the entire side of the compression rubber layer than the central portion of the cross section of the core wire.
transmission belt. In the transmission belt according to claim 1,
The adhesive rubber layer has a two-layer structure in the entire belt width direction central portion, while a portion other than the belt width direction central portion has a one-layer structure in the entire belt length direction. cage,
The adhesive rubber layer is
Except for the layer on the side far from the compression rubber layer in the central portion in the width direction of the belt having a two-layer structure, the belt is made of the first rubber composition,
The layer on the far side from the compression rubber layer in the central portion in the belt width direction, which has a two-layer structure, is a second rubber composition in which at least one of the type and content of constituent components is different from the first rubber composition. It is configured,
transmission belt. In the transmission belt according to any one of claims 2, 3, 6, 7, 8 and 9,
The power transmission belt, wherein in the adhesive rubber layer, the portion made of the second rubber composition has a lower modulus of elasticity than the portion made of the first rubber composition.

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