JP2018071630A - V-ribbed belt and power transmission mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel saving (torque loss reduction) while maintaining transmission performance and sound generation resistance, in a V-ribbed belt having a groove which traverses a belt width direction at a compression layer.SOLUTION: A V-ribbed belt 1 which is used by being wound to a pulley comprises: an elongation layer 11; a compression layer 12 having a plurality of ribs 13 which extend in parallel with one another along a V-ribbed belt longitudinal direction M; and a core body 14 which is embedded between the elongation layer 11 and the compression layer 12 along the V-ribbed belt longitudinal direction M. The compression layer 12 has a plurality of grooves 18 extending to a V-ribbed belt width direction N, the grooves 18 are formed obliquely at angles θ=10 to 30° with respect to the V-ribbed belt width direction N, and intervals P of the grooves 18 are irregularly set within a periphery of a V-ribbed belt. The grooves 18 are formed into U-shapes, and satisfy conditions that of groove depths are within a range of 65 to 90% of rib heights i, that groove widths are within a range of 1.2 to 1.6 mm, and that values of groove depths/groove widths are within a range of 0.81 to 2.2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a V-ribbed belt used for driving an automobile engine accessory (power transmission mechanism) and the like, and more specifically, durability (heat resistance) while maintaining the transmission performance and sound resistance (silence) of a friction transmission surface. ), A V-ribbed belt capable of improving fuel economy (reducing torcross) and a power transmission mechanism using the V-ribbed belt.

  In general, an auxiliary machine such as an alternator, a water pump, and a power steering pump is attached to an internal combustion engine (engine) for automobiles, etc., and these auxiliary machines have a power transmission mechanism in which a transmission belt is suspended by an engine crankshaft. Generally, it is mechanically driven via

  In recent years, in an automobile engine, not only transmission performance and durability, but in particular, a demand for a technology that achieves both fuel saving and sound proofing (silence) has been increasing.

  With regard to fuel efficiency, from the viewpoint of reducing engine friction loss and improving fuel efficiency, it is desirable to reduce the torque cross in the power transmission mechanism (the difference between the drive torque on the crankshaft and the driven torque on the driven shaft (auxiliary)). It is rare.

  In particular, in a portion where the pulley diameter is small, such as an alternator that is a power generation device, the amount of bending of the wound belt is large, and the torque loss is insufficient. Since the part where such a large torque cross is generated greatly affects the friction loss of the engine, further reduction of the torque cross is a major issue.

  In order to solve the above-mentioned problems, a V-ribbed belt is used as a transmission belt used in an engine accessory drive system, and means for reducing torcross with respect to the V-ribbed belt has been proposed. For example, Patent Document 1 proposes a V-ribbed belt that reduces torcross by means of reducing internal loss (self-heating) (using a rubber composition having a small loss tangent tan δ). In Patent Document 2, the bending loss is reduced by focusing on the reduction of the stress (compression stress) required to bend the compression layer of the belt (the position of the core wire is arranged on the inner peripheral side, and the bending of the core wire is performed). V-ribbed belts have been proposed that reduce torcross by means of reducing stress.

  Although a certain degree of torque reduction can be achieved by these means, it is still inadequate and a big problem for the torque reduction with a small-diameter pulley.

  As another means for reducing the bending loss, a groove (slit) crossing the belt width direction is provided in the compression layer located on the inner peripheral side of the V-ribbed belt to improve the flexibility and bend the compression layer. A means for reducing the stress (compressive stress) required for this is conceivable. Patent Literature 3, Patent Literature 4, and Patent Literature 5 disclose V-ribbed belts having grooves (slits).

JP 2010-276127 A JP 2013-177967 A JP 7-208559 A JP 2003-21196 A Japanese Patent No. 4584612

  However, V-ribbed belts with grooves (slits) have problems such as reduced transmission performance due to the reduced frictional transmission surface depending on how the grooves (slits) are inserted, and periodic noise (noise) during belt running. Is concerned. In Patent Documents 3, 4, and 5, although a design means for reducing noise is taken into consideration, a groove that can achieve improved fuel efficiency (reduced torcross) while maintaining transmission performance and sound resistance (quietness). The design philosophy of (slit) has not been studied.

  Therefore, the present invention also achieves improved fuel efficiency (reduced torcross) while maintaining transmission performance and sound resistance (quietness) even in a V-ribbed belt having a groove (slit) across the belt width direction in the compression layer. A V-ribbed belt is provided.

One of the present invention for solving the above problems is a V-ribbed belt used by being wound around a pulley,
A stretch layer forming the back surface;
A compression layer provided on one surface of the stretch layer and having a plurality of ribs extending in parallel with each other along the longitudinal direction of the V-ribbed belt;
A core body embedded along the longitudinal direction of the V-ribbed belt between the stretch layer and the compression layer,
The compression layer has a plurality of grooves extending in the width direction of the V-ribbed belt,
The groove is disposed obliquely at an angle θ = 10 to 30 ° with respect to the width direction of the V-ribbed belt,
The grooves are arranged at irregular intervals within the circumference of the V-ribbed belt,
The shape of the groove is a U shape having a circular arc at the bottom and a uniform groove width over the depth direction,
The depth of the groove is in the range of 65 to 90% of the rib height;
The groove has a width of 1.2 to 1.6 mm,
The groove depth / the groove width value is in the range of 0.81 to 2.2;
A V-ribbed belt characterized by satisfying the following conditions.

As described above, by inserting a groove (slit) in the compression layer on the inner peripheral side of the V-ribbed belt, the flexibility of the V-ribbed belt is improved, and the stress (compression stress) required to bend the compression layer can be reduced. it can. As a result, bending loss is reduced, which contributes to the reduction of torque cross.
However, by providing grooves in the compression layer, the ribs provided in the compression layer discontinuously move in and out of the pulley, so that a distinctive operating sound due to entering and exiting (the peak of the harmonic noise of the discontinuous ribs) is the groove interval period. Depending on the situation, it may be a big noise. In particular, when the groove is arranged parallel to the width direction of the V-ribbed belt (θ = 0 °), the plurality of discontinuous ribs existing in the width direction of the V-ribbed belt simultaneously enter and exit the pulley, so that the overall noise is reduced. Although the level is increased, the discontinuity of the discontinuous ribs proceeds in order from one end to the other (discontinuous) by disposing with an inclination (θ = 10 to 30 °) with respect to the width direction. The movement of the ribs into and out of the pulleys is dispersed), and the overall noise level can be reduced.
Although the overall noise level is reduced by arranging the grooves so as to be inclined with respect to the width direction of the V-ribbed belt, harmonic peak noises of discontinuous ribs may still remain. Therefore, by making the groove interval (pitch pattern) irregular (random) within the circumference of the V-ribbed belt, the peak noise of the harmonic sound can also be reduced.
Further, by making the groove shape U-shaped instead of V-shaped, it is possible to reduce the compressive stress generated near the rib base (rib bottom) when bent. As a result, internal heat generation of the V-ribbed belt can be reduced.
If the groove width is too narrow, the bending loss of the V-ribbed belt is insufficiently reduced. On the other hand, if the groove width is too wide, the noise level becomes high. Also, if the groove depth is too small, the bending loss of the V-ribbed belt will be insufficiently reduced. On the other hand, if the groove depth is too large, the strain energy applied to the vicinity of the cord will increase when the V-ribbed belt is bent. , It may lead to a pop out of the heart. Therefore, the groove depth is in the range of 65 to 90% of the rib height, the groove width is in the range of 1.2 to 1.6 mm, and the groove depth / the groove width value is 0.81 to 2. By maintaining the range of 2, the transmission performance is maintained, while the torcross reduction, noise reduction, distortion energy reduction (pop-out resistance), and internal heat generation of the belt (suppression of increase in rubber hardness are suppressed) Improvement can be realized.

  Moreover, one of the present invention is characterized in that in the V-ribbed belt, the number of grooves is 15 to 16 per 100 mm in the longitudinal direction of the V-ribbed belt.

If the number of grooves arranged in the compression layer of the V-ribbed belt is too small, a sufficient torque reduction effect may not be obtained. On the other hand, if the number of grooves arranged in the compression layer of the V-ribbed belt is too large, the pulley The area (transmission surface) of the compressed layer that can come into contact with the surface is reduced, and sufficient transmission performance may not be obtained.
Therefore, by setting the number of grooves to 15 to 16 per 100 mm in the longitudinal direction of the V-ribbed belt, a sufficient torque loss reduction effect and transmission performance can be obtained.

Moreover, one of the present invention is the V-ribbed belt described above,
A plurality of pulleys around which the V-ribbed belt is wound,
At least one of the plurality of pulleys is a power transmission mechanism having an outer diameter of 65 mm or less.

  In particular, in a power transmission mechanism having a pulley having an outer diameter of 65 mm or less, the amount of bending of the wound V-ribbed belt increases, and the torque cross increases. Therefore, by using the V-ribbed belt having the above characteristics, a power transmission mechanism with reduced torque cross can be obtained.

  Providing V-ribbed belts that can improve fuel efficiency (reducing torcross) while maintaining transmission performance and sound-proofing (quietness) even for V-ribbed belts with grooves (slits) that cross the belt width direction in the compression layer can do.

It is a schematic explanatory drawing of the V-ribbed belt which concerns on this embodiment. It is sectional drawing of the width direction of the V-ribbed belt which concerns on this embodiment. It is explanatory drawing of the internal peripheral surface of the V-ribbed belt which concerns on this embodiment. It is explanatory drawing of the internal peripheral surface of the V-ribbed belt which concerns on this embodiment. It is explanatory drawing of the groove | channel of the V-ribbed belt which concerns on this embodiment. It is a simplified sectional view of the width direction of the V ribbed belt concerning this embodiment. It is explanatory drawing regarding the measuring method of the simulation analysis of the bending stress of the V ribbed belt which concerns on an Example. It is a FEM analysis result of the bending stress of the V ribbed belt which concerns on an Example. It is a FEM analysis result of the bending stress of the V ribbed belt which concerns on an Example. It is explanatory drawing regarding the measuring method of the friction loss (torcross) of the V-ribbed belt which concerns on an Example. It is the temperature measurement result of the rib surface of a V ribbed belt in the measurement test of the friction loss which concerns on an Example. It is explanatory drawing regarding the high temperature low tension reverse bending test which concerns on an Example. It is a result of the high temperature low tension reverse bending test which concerns on an Example. It is explanatory drawing regarding the transmission performance test method which concerns on an Example. It is a result of the transmission performance test which concerns on an Example. It is a result of the sound-proofing test which concerns on an Example.

(Embodiment)
Hereinafter, embodiments of a V-ribbed belt and a power transmission mechanism using the V-ribbed belt according to the present invention will be described with reference to the drawings.

  The V-ribbed belt 1 according to this embodiment is used by being wound between, for example, a drive pulley 2 and a driven pulley 3 in a power transmission mechanism (system) such as an engine accessory drive system (see FIG. 1). .

(Configuration of V-ribbed belt 1)
As shown in FIG. 2, the V-ribbed belt 1 of the present embodiment is made of a rubber composition, and is provided on one surface of the stretch layer 11 that forms the back surface 1A of the V-ribbed belt, and in the longitudinal direction M of the V-ribbed belt M. A compression layer 12 having a plurality of ribs 13 extending in parallel to each other along the core, a core 14 embedded along the longitudinal direction M of the V-ribbed belt between the extension layer 11 and the compression layer 12, and the extension layer 11. And an adhesive layer 15 provided between the compression layer 12. The adhesive layer 15 is not essential, and is provided for the purpose of improving the adhesiveness of the core body 14, the stretch layer 11, and the compressive layer 12. As in the present embodiment, the adhesive layer 15 and the stretch layer are provided. 11, the core body 14 may be embedded in the adhesive layer 15, or the core body 14 may be embedded between the compression layer 12 and the adhesive layer 15. May be.

  Also, the V-ribbed belt 1 shown in FIG. 2 is formed of a rubber composition containing a stretch layer 11, an adhesive layer 15 disposed below the stretch layer 11, and a short fiber 16 disposed below the stretch layer 11. The compression layer 12 is provided. In other words, in the V-ribbed belt 1, a rubber layer is constituted by three layers of an extension layer 11, an adhesive layer 15, and a compression layer 12, and the compression layer 12 constitutes an inner layer. Note that the adhesive layer 15 and the compression layer 12 may be defined as constituting an inner layer. Further, the core body 14 is disposed so as to be embedded in the main body of the V-ribbed belt 1 along the longitudinal direction M of the V-ribbed belt, half of which is embedded in the stretched layer 11 and the other half is embedded in the adhesive layer 15. It is arranged in the state. The compressed layer 12 is provided with a plurality of ribs 13 having a substantially trapezoidal cross section in the V-ribbed belt width direction N and extending in the longitudinal direction M of the V-ribbed belt. Here, the short fibers 16 contained in the compressed layer 12 are contained in a state oriented in the V-ribbed belt width direction N, which is a direction orthogonal to the V-ribbed belt longitudinal direction M. Further, the surface of the rib 13 is a polished surface.

  Further, as shown in FIGS. 3 and 4, the V-ribbed belt 1 is formed with a plurality of grooves 18 (slits) extending in the V-ribbed belt width direction N in the compression layer 12 (the inner peripheral surface side of the V-ribbed belt 1). Yes.

  As shown in FIG. 4, each groove 18 is formed to have an inclination in the range of an angle θ = 10 to 30 ° with respect to the V-ribbed belt width direction N. The grooves 18 may all be inclined at the same angle θ, or may be inclined at irregular (irregular) angles θ in the range of angle θ = 10 to 30 °.

  Further, as shown in FIG. 4, the interval P (pitch pattern) between the groove 18 and the groove 18 is formed at irregular (random) intervals in the longitudinal direction M of the V-ribbed belt (each groove 18 is a V-ribbed belt 1). Are irregularly spaced around the circumference of the

  Here, the number of grooves 18 is preferably 15 to 16 per 100 mm in the length direction M of the V-ribbed belt. The reason for this is that if the number of grooves 18 arranged in the compression layer 12 of the V-ribbed belt 1 is less than 15, sufficient torque loss reduction effect may not be obtained, while the compression layer 12 of the V-ribbed belt 1 may not be obtained. If the number of the grooves 18 arranged in the space is more than 16, the area (transmission surface) of the compression layer 12 that can come into contact with the driving pulley 2 and the driven pulley 3 is reduced, and sufficient transmission performance is obtained. This is because it may disappear.

  For example, when 16 grooves 18 are arranged at irregular intervals per 100 mm length in the longitudinal direction M of the V-ribbed belt M, each interval P (pitch pattern) of the 16 grooves 18 is 8 mm, 6 mm, 4 mm, It can be exemplified to form 10 mm, 6 mm, 4 mm, 8 mm, 10 mm, 4 mm, 6 mm, 10 mm, 4 mm, 4 mm, 8 mm, and 8 mm (the value of each pitch pattern P can be freely set).

  Further, as shown in FIG. 5, the shape of the groove 18 is U-shaped in a cross-sectional view having a circular arc at the bottom and a uniform groove width (the same width as the maximum width of the bottom) in the depth direction of the groove 18. I am doing.

  And it is preferable that the depth of the groove | channel 18 is 65 to 90% of range of the height of the rib 13 (refer rib height i of FIG. 6). For example, when the rib height i is 2.9 mm, the depth of the groove 18 is in the range of 1.88 to 2.61 mm, and when the rib height i is 2.7 mm, the depth of the groove 18 is 1. When the rib height i is 2.5 mm, the depth of the groove 18 is 1.63 to 2.25 mm, and when the rib height i is 2.0 mm. The depth of the groove 18 is in the range of 1.30 to 1.80 mm. The width of the groove 18 (groove width) is preferably in the range of 1.2 to 1.6 mm. Furthermore, the value of (depth of groove 18) / (groove width) is preferably in the range of 0.81 to 2.2.

(Compressed layer 12)
Examples of the rubber component of the rubber composition forming the compression layer 12 include vulcanizable or crosslinkable rubbers such as diene rubbers (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene / butadiene rubber (SBR), acrylonitrile). Butadiene rubber (nitrile rubber), hydrogenated nitrile rubber, etc.), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluorine rubber Etc. can be exemplified. These rubber components may be used alone or in combination of two or more. Preferred rubber components are ethylene-α-olefin elastomers (ethylene-α-olefin rubbers such as ethylene-propylene copolymer (EPM) and ethylene-propylene-diene terpolymer (EPDM)), and chloroprene rubber. . A particularly preferable rubber component is an ethylene-α-olefin elastomer which is excellent in durability against chloroprene rubber and does not contain a halogen. Examples of the diene monomer of EPDM include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like.

  In particular, in view of heat resistance and wear resistance, EPDM which is a copolymer of ethylene, α-olefin and non-conjugated diene is preferable. Among them, ethylene content is 51 to 68% by mass, and double bond (Diene content) is preferably 0.2 to 7.5% by mass. As this EPDM, it is preferable to use one having an iodine value of 3 to 40. If the iodine value is less than 3, the rubber composition is not sufficiently vulcanized, and there is a possibility that problems of abrasion, adhesion, and pronunciation may occur. In addition, when the iodine value exceeds 40, the scorch of the rubber composition becomes short and difficult to handle, and the heat resistance may be deteriorated.

  The energy applied when the V-ribbed belt 1 bends generates internal heat of the compressed rib rubber (compressed layer 12) and causes torcross. In the rubber composition forming the compression layer 12, the content ratio of the ethylene-α-olefin elastomer in the rubber composition is set to 45% by mass or more, and the content ratio of carbon black is set to less than 35% by mass. The dynamic viscoelasticity tan δ (loss tangent) of the compression layer 12 formed by curing the rubber composition is decreased by increasing the content ratio of the ethylene-α-olefin elastomer and decreasing the content ratio of the carbon black. be able to. When the content ratio of the ethylene-α-olefin elastomer is 45% by mass or more and the content ratio of the carbon black is less than 35% by mass, the dynamic viscoelasticity of the compression layer formed using this rubber composition is reduced to the initial value. When measured under conditions of a strain of 1.0%, a frequency of 10 Hz, and a dynamic strain of 0.5%, the maximum value of tan δ in the range of 25 to 120 ° C. can be adjusted to less than 0.150. When the content ratio of the ethylene-α-olefin elastomer is less than 45% by mass or when the content ratio of carbon black is 35% by mass or more, tan δ becomes a large value of 0.150 or more, and the internal loss of the compressed rubber layer is Increases and increases torque cross.

  The upper limit of the content ratio of the ethylene-α-olefin elastomer in the rubber composition is not particularly set, but in practice, the content ratio of the ethylene-α-olefin elastomer is desirably 55% by mass or less. Further, the lower limit of the carbon black content ratio is not particularly set, but if the carbon black content ratio is less than 20% by mass, the wear resistance of the rubber composition is deteriorated and the durability of the V-ribbed belt 1 is reduced. Therefore, the content ratio of carbon black is preferably 20% by mass or more. Since the durability tends to decrease when the content ratio of carbon black is reduced in this way, it is preferable to use graphite together to reduce the content ratio of carbon black while suppressing the decrease in durability.

  Further, the rubber composition forming the compression layer 12 may further include a crosslinking agent such as sulfur and organic peroxide, N, N′-m-phenylene dimaleimide, and quinone, which are usually blended in the rubber, if necessary. Co-crosslinking agents such as dioximes, vulcanization accelerators, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids, colorants, short fibers, and the like may be blended. Short fibers include cotton, polyester (PET, PEN, etc.), nylon (6 nylon, 66 nylon, 46 nylon, etc.), aramid (p-aramid, m-aramid), vinylon, polyparaphenylene benzobisoxazole (PBO) A fiber etc. can be used. These short fibers can be used alone or in combination of two or more. These various blends can be formed into a sheet by kneading them using commonly used means such as a Banbury mixer or a kneader.

(Extension layer 11)
The stretch layer 11 is formed of an outer cloth (reinforcing cloth) or a rubber composition. When the stretch layer 11 is formed of a cover cloth, the cover cloth may be a cloth material (preferably a woven cloth) such as a woven cloth, a wide-angle sail cloth, a knitted cloth, or a non-woven cloth. When the stretch layer is formed of a rubber composition, the rubber composition constituting the stretch layer may be formed of the same rubber composition that forms the compression layer 12. The thickness of the stretch layer is, for example, about 0.6 to 4 mm, preferably about 0.7 to 3 mm, and more preferably about 0.8 to 2 mm.

(Adhesive layer 15)
The adhesive layer 15 uses, as a rubber composition, a blend rubber obtained by mixing EPDM, which is a copolymer of ethylene, α-olefin, and non-conjugated diene, or a partner rubber made of other types of rubber. As the other rubber to be blended with EPDM, which is a copolymer of ethylene, α-olefin and non-conjugated diene, butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), hydrogenated nitrile rubber ( H-NBR), chloroprene rubber (CR), butyl rubber (IIR), and natural rubber (NR). As described above, the adhesive layer 15 is not essential, and is provided for the purpose of improving the adhesiveness of the core body 14, the stretch layer 11, and the compression layer 12, and is bonded as in this embodiment. In addition to the form in which the core body 14 is embedded between the layer 15 and the stretched layer 11, the core body 14 may be embedded in the adhesive layer 15, and the core body 14 is disposed between the compression layer 12 and the adhesive layer 15. The form to embed may be sufficient.

(Core 14)
Although it does not specifically limit as the core body 14, Usually, the core wire (twisted cord) arranged at predetermined intervals in the belt width direction N can be used. As the core wire, for example, polybutylene terephthalate (PBT) fiber, polyethylene terephthalate (PET) fiber, polytrimethylene terephthalate (PTT) fiber, polyester fiber such as polyethylene naphthalate (PEN) fiber, 6 nylon fiber, 66 nylon fiber, Nylon fiber such as 46 nylon fiber, copolyparaphenylene 3,4'oxydiphenylene terephthalamide fiber, aramid fiber such as poly-p-phenylene terephthalamide fiber, polyarylate fiber, glass fiber, carbon fiber, PBO fiber, etc. Can be used. These fibers can be used alone or in combination of two or more. The fiber may be a multifilament yarn, for example, a multifilament yarn having a fineness of 2000 to 10000 denier (particularly 4000 to 8000 denier).

  As the core wire, a twisted cord using multifilament yarn (for example, various twists, single twists, rung twists, etc.) can be used. The average wire diameter (fiber diameter of the twisted cord) of the core wire may be, for example, about 0.5 to 3 mm, preferably about 0.6 to 2 mm, and more preferably about 0.7 to 1.5 mm. The core wire may be embedded in the V-ribbed belt longitudinal direction M, and one or more core wires may be embedded in parallel at a predetermined pitch in parallel to the V-ribbed belt longitudinal direction M.

  The core wire used for the core body 14 is preferably subjected to an adhesion treatment for the purpose of improving the adhesion to the stretch layer 11 and the compression layer 12. As such an adhesion treatment, the core wire is immersed in a resin-based treatment solution in which epoxy or isocyanate is dissolved in an organic solvent, dried by heating, and then immersed in a treatment solution such as resorcin-formalin-latex solution (RFL solution). Can be carried out by heating and drying. If necessary, after the RFL treatment, an overcoating treatment may be performed with a treatment solution in which the rubber composition is dissolved in an organic solvent (toluene, xylene, methyl ethyl ketone, etc.).

(Manufacturing method of V-ribbed belt 1)
The manufacturing method in particular of the V-ribbed belt 1 of this invention is not restrict | limited, A well-known or usual method is employable. For example, the compression layer 12, the adhesive layer 15 in which the core body 14 is embedded, and the stretch layer 11 are each formed from an unvulcanized rubber composition and laminated, and this laminate is molded into a cylindrical shape with a molding die. Each V-ribbed belt 1 can be formed by vulcanizing to form a sleeve and cutting the vulcanized sleeve to a predetermined width. More specifically, the V-ribbed belt 1 can be manufactured by the following method.

(First manufacturing method)
First, a stretch layer sheet is wound around a cylindrical molding mold having a smooth surface, and a core wire (twisted cord) that forms the core body 14 is spirally spun onto the sheet, and further, an adhesive layer sheet, compressed The rubber layer sheets are sequentially wound and laminated to produce a cylindrical unvulcanized molded body. Thereafter, a jacket for vulcanization is placed on the molded body, the mold (molding die) is accommodated in a vulcanizing can, vulcanized under predetermined vulcanization conditions, and then removed from the molding mold to form a cylindrical shape. Get a vulcanized sleeve. Then, the outer surface (compressed rubber layer) of the vulcanized sleeve is polished by a grinding wheel to form a plurality of ribs 13, and then the vulcanized sleeve is cut into a predetermined width in the longitudinal direction M of the V-ribbed belt using a cutter. Thus, the V-ribbed belt 1 is finished. By reversing the cut V-ribbed belt 1, the V-ribbed belt 1 including the compression layer 12 having the ribs 13 on the inner peripheral surface is obtained.

  In addition, regarding the method of forming the groove 18 that is inclined in the width direction N of the V-ribbed belt provided in the compressed layer 12 according to the present invention, a known machine is used in the vulcanized sleeve or the V-ribbed belt 1 that is cut and finished to a predetermined width. Alternatively, the groove may be cut by a general processing method. Alternatively, a cylindrical mother die (rubber die) provided with protrusions corresponding to a predetermined groove shape on the inner peripheral surface in advance is formed, and the cylindrical mother die is placed on the outer peripheral side of the unvulcanized molded body, A method of obtaining a vulcanization sleeve having a predetermined groove shape transferred to the outer peripheral surface by covering with a vulcanization jacket and vulcanizing may be used.

(Second manufacturing method)
First, a cylindrical inner mold having a flexible jacket attached to the outer peripheral surface is used as the inner mold, an unvulcanized stretch layer sheet is wound around the outer peripheral flexible jacket, and the core body 14 is placed on the sheet. The core wire to be formed is spun into a spiral shape, and an unvulcanized compression layer sheet is wound around to produce a laminate. Next, as an outer mold that can be attached to the inner mold, a cylindrical outer mold in which a plurality of rib molds are engraved on the inner peripheral surface is used, and an inner mold in which the laminate is wound is provided in the outer mold. Install concentrically. Thereafter, the flexible jacket is expanded toward the inner peripheral surface (rib type) of the outer mold, and the laminate (compressed rubber layer) is press-fitted into the rib mold and vulcanized. Then, after removing the inner mold from the outer mold and removing the vulcanized sleeve having the plurality of ribs 13 from the outer mold, the vulcanized sleeve is cut to a predetermined width in the longitudinal direction M of the V-ribbed belt using a cutter. Finish to V-ribbed belt 1. Also in this method, the inclined groove 18 traversing in the V-ribbed belt width direction N is cut by a known mechanical processing method to form the groove 18 in the vulcanized sleeve or the V-ribbed belt 1 finished by cutting to a predetermined width. To do.

(Power transmission mechanism)
Further, the present invention includes the V-ribbed belt 1 described above and a plurality of pulleys (for example, two of a driving pulley and a driven pulley) around which the V-ribbed belt 1 is wound, and at least one of the plurality of pulleys is The power transmission mechanism 10 having an outer diameter of 65 mm or less is also implemented (see FIG. 1). In addition, since one of the pulleys should just be 65 mm or less in outer diameter, the number of pulleys is not restrict | limited (refer the test machine of FIG. 12).

  In particular, in the power transmission mechanism 10 having a pulley having an outer diameter of 65 mm or less, the amount of bending of the wound V-ribbed belt 1 increases, and the torque cross increases. Therefore, by using the V-ribbed belt 1 having the above characteristics, the power transmission mechanism 10 with reduced torque cross can be obtained.

[Production of V-ribbed belt]
Below, based on an Example, the V-ribbed belt 1 which concerns on this invention is demonstrated in detail, This invention is not limited by these Examples. In the following examples, the raw materials used for the V-ribbed belt 1 according to the examples, measurement methods and evaluation methods for each physical property are shown below. Unless otherwise specified, “part” and “%” are based on mass.

[material]
EPDM: “EPT2060M” manufactured by Mitsui Chemicals, Inc.
Nylon short fiber: 66 nylon, average fiber diameter 27 μm, average fiber length 3 mm
Cotton short fiber: Denim, average fiber diameter 13μm, average fiber length 6mm
Zinc oxide: “Zinc oxide 3 types” manufactured by Shodo Chemical Industry Co., Ltd.
Stearic acid: Tsubaki stearic acid manufactured by NOF Corporation
Carbon black HAF: “Seast 3” manufactured by Tokai Carbon Co., Ltd., average particle size 28 nm
Hydrous silica: “Nippil VN3” manufactured by Tosoh Silica Corporation
Paraffinic oil (softener): “Diana Process Oil PW-90” manufactured by Idemitsu Kosan Co., Ltd.
Organic peroxide: NOF Corporation "Park Mill D-40"
Vulcanization accelerator A: Tetramethylthiuram disulfide (TMTD)
Vulcanization accelerator B: N-cyclohexyl-2-benzothiazyl-sulfenamide (CBS)
Co-crosslinking agent: p, p′-dibenzylquinone dioxime, “Barunok DGM” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Core wire: a twisted yarn cord obtained by adhering a cord of total denier 6,000, which is a 2 × 3 twisted configuration of 1,000 denier PET fiber, and twisted at an upper twist factor of 3.0 and a lower twist factor of 3.0, Core wire diameter 1.0mm.

[Manufacture of V-ribbed belt]
The rubber composition for forming the compression layer and the rubber composition for forming the adhesive layer shown in Table 1 are each kneaded using a known method such as a Banbury mixer, and the kneaded rubber is passed through a calender roll to obtain a predetermined composition. A compressed layer forming sheet and an adhesive layer forming sheet having a thickness were prepared.

  Further, as the covering fabric used for the stretch layer 11, a wide-angle plain woven canvas (thickness: 0.63 mm) using a mixed yarn of 50:50 by weight of cotton fiber and polyethylene terephthalate fiber was used. This canvas was immersed in an RFL solution, and then heat treated at 150 ° C. for 2 minutes to obtain an adhesion-treated canvas. Furthermore, a stretched layer laminate was prepared by laminating an adhesive layer forming sheet (thickness 0.5 mm) on this adhesion-treated canvas.

  Next, the V-ribbed belt 1 was produced using the following known methods. First, a cylindrical mother mold (rubber mold) in which protrusions corresponding to a predetermined groove shape were previously provided on the inner peripheral surface was molded. Next, a laminate for stretch layer (so that the outer cover cloth is located on the mold side and the sheet for forming the adhesive layer is located on the outer periphery side) is wound around a cylindrical molding mold having a smooth surface. A core wire (twisted cord) forming a core body on the outer periphery was spun into a spiral shape, and an adhesive layer forming sheet and a compressed layer forming sheet were sequentially wound to form an unvulcanized molded body. Then, the molding die is vulcanized in a state where the cylindrical mother die (rubber die) is placed on the outer peripheral side of the unvulcanized molded body, and further the vulcanization jacket is placed on the outer peripheral side from above the molded body. And then removed from the molding mold for 30 minutes under the conditions of a temperature of 180 ° C. and a pressure of 0.9 MPa to obtain a cylindrical vulcanization sleeve having a predetermined groove shape (groove 18) transferred to the outer peripheral surface. It was. Then, the outer peripheral surface (compressed layer 12) of the vulcanized sleeve is ground at a predetermined interval by a grinding wheel to form a plurality of ribs 13, and then is cut with a predetermined width in the longitudinal direction M of the V-ribbed belt using a cutter. Thus, individual V-ribbed belts 1 were finished.

(V-ribbed belt dimensions)
As shown in FIG. 6 and Table 2, the obtained V-ribbed belt 1 has a distance a from the center of the core [2] to the back of the V-ribbed belt [1] of 1.00 mm, and the bottom of the core [3] to the back of the V-ribbed belt. The distance b from [1] to 1.50 mm, the distance c from the rib bottom [4] to the V-ribbed belt back [1] is 2.30 mm, and the distance d from the rib tip [5] to the V-ribbed belt back [1] 4.30 mm, the rib pitch e is 3.56 mm, the distance h from the core bottom [3] to the rib bottom [4] is 0.80 mm, and the distance i from the rib tip [5] to the rib bottom [4] is The distance j from the rib tip [5] to the core bottom [3] was adjusted to 2.00 mm and 2.80 mm.

  Further, the compression layer 12 (inner peripheral surface) of the V-ribbed belt 1 used in each test described later has a U-shape at random intervals so that the inclination angle θ is 20 ° and the belt length is 15 per 100 mm. Groove 18 was provided.

[Simulation analysis of bending stress]
The stress generated by bending the V-ribbed belt 1 was analyzed by FEM. Here, since the analysis is for confirming the flexibility, the groove 18 (slit) provided in the compression layer 12 is not inclined (inclination angle θ = 0 °) and includes three types including a model provided with a spacing P = 7.0 mm ( A V-ribbed belt 1 of A, B, C) was analyzed. FIG. 8 shows three types of V-ribbed belt 1.
(A) No groove 18 (B) U-shaped groove 18 (bottom R = 0.4 mm, groove depth = 2.0 mm, side surface angle (K) = 0 °) (C) When a groove 18 having a shape in which the groove width widens (bottom R = 1.0 mm, groove depth = 2.0 mm, side surface angle (K) = 15 °) is provided.

  As a method for FEM analysis of the stress generated by bending the three types (A, B, C) of the V-ribbed belt 1, as shown in FIG. 7, a pulley having an outer diameter of 55 mm and a V groove angle of 40 ° is used. Three types (A, B, C) of V-ribbed belt 1 with a portion of one rib created in a straight line are wound around the pulley at a tension of T0 by 90 ° (fixed at one end and DW load at the other end) ), The pulley is rotated to generate an effective tension, and the stress generated thereby is analyzed by FEM. In addition, the boundary surface with an adjacent rib is restrained in-plane.

  The stress generated in the V-ribbed belt 1 was analyzed from the amount of deformation in the longitudinal direction M of the V-ribbed belt when the three types (A, B, C) of the V-ribbed belt 1 were bent. As a result, as shown in FIG. 8, the stress generated in the compression layer 12 (particularly near the rib tip) is reduced when the groove 18 is inserted, compared to the case where the groove 18 is not provided. As shown in FIG. 8, the deformation amount is large and stress remains in the vicinity of the rib bottom even if the groove 18 is inserted. However, the (B) type U-shaped is better than the (C) type groove 18. The degree of stress is reduced (* The wide groove 18 has the same effect if it is U-shaped).

  Therefore, by providing the U-shaped groove 18, stress due to belt bending is reduced. As a result, the internal heat generation of the V-ribbed belt 1 is suppressed, and the durability of the V-ribbed belt 1 is improved due to the effect of suppressing the deterioration of rubber due to the heat generation.

[Simulation analysis of strain energy applied near the lower side of the core]
As described above, by providing the U-shaped groove 18 (type B), the stress generated in the compression layer 12 (especially near the tip of the rib) due to the belt bending is reduced, but there is a portion where the stress due to bending deformation is concentrated. It moves near the bottom of the groove 18 (near the bottom R). In particular, deformation stress (strain stress) concentrates near the lower side of the core body 14 of the adhesive layer 15 near the bottom R of the groove 18. When the vicinity of the core body 14 is subjected to deformation stress (strain stress), peeling tends to occur at the interface between the core body 14 and the adhesive layer 15, and in the core body 14 exposed at the end of the V-ribbed belt 1, There is a possibility that a pop-out phenomenon that escapes from the V-ribbed belt 1 occurs.

  Therefore, regarding the width and depth of the groove 18, it is necessary to consider the resistance of the core body 14 to pop-out. Therefore, for the V-ribbed belt 1 in which the width and depth of the groove 18 are varied, the strain stress generated near the lower side of the core body 14 (particularly, the core body 14 at both ends) of the adhesive layer 15 when the belt is bent is calculated by FEM analysis. (See FIG. 9).

  Table 3 shows the relative index with the strain stress when the U-shaped groove 18 having a width of 1.4 mm and a depth of 1.5 mm is provided as 100.

  As a result, the strain stress generated below the core body 14 is reduced as the width of the groove 18 is increased, and is reduced as the depth of the groove 18 is decreased. The degree of the reduction effect is greater in the depth of the groove 18 than in the width of the groove 18.

  In the combination of the width of the groove 18 and the depth of the groove 18, in Table 3, since the strain stress is large in the range of the groove width 1.1 mm to 1.6 mm and the groove depth 2 mm, the depth of the groove 18 is It was judged that 1.8 mm or less was preferable. When the groove depth was 2 mm, it was determined that the groove width was preferably 1.7 mm.

[Measurement of friction loss (torcross)]
As shown in FIG. 10, a V-ribbed belt 1 (six number of ribs 13, length 1100 mm) is added to a two-axis running test machine composed of a driving (Dr) pulley having a diameter of 55 mm and a driven (Dn) pulley having a diameter of 55 mm. Is applied to the V-ribbed belt 1 within a tension range of 100 to 900 N / one belt, and the difference between the driving torque and the driven torque when the driving pulley is rotated at 2000 rpm with no driven pulley loaded. Was calculated as Torcross. Table 4 shows the torque cross when the initial tension of 675N / one belt was applied.

  In addition, the torque cross calculated | required by this measurement contains the torque cross resulting from the bearing of a testing machine other than the torque cross by the bending loss of the V-ribbed belt 1. FIG. Therefore, a metal belt (material: maraging steel) in which the torque cross as the V-ribbed belt 1 is considered to be substantially zero is run in advance, and the difference between the driving torque and the driven torque at this time is a torque loss due to the bearing (bearing loss). The value obtained by subtracting the torque cross due to the bearing from the torque cross calculated by running the V-ribbed belt 1 (the torque cross resulting from the V-ribbed belt 1 and the bearing) was obtained as the torque cross resulting from the V-ribbed belt 1 alone. . Here, the torcross (bearing loss) to be subtracted is the torcross when the metal belt is run with a predetermined initial tension (for example, when the V-ribbed belt 1 is run with an initial tension of 500 N / one belt, the metal belt with this initial tension. (Torcross when driving). The smaller the torque cross of this V-ribbed belt 1, the better the fuel economy. From the viewpoint of fuel economy in an automobile engine, it is preferable that the torque is reduced to 0.29 N · m or less as a guideline for torque cross.

  The torcross of the V-ribbed belt 1 without the groove 18 was 0.375 N · m. With respect to the V-ribbed belt 1 of Table 4 having the grooves 18, the torque cross was large in the frame showing 0.30 N · m or more, and the effect of reducing the torque cross was not sufficient. Torcross is reduced to a level of 0.28 to 0.29 N · m because the groove width is 1.7 mm, the groove depth is 1.2 mm, the groove width is 1.2 mm or more, and the groove depth is 1. The V-ribbed belt 1 had a range of 3 to 1.8 mm, a groove width of 1.6 mm or more and a groove depth of 2.0 mm. This range was determined to be the optimum range of the depth and width of the groove 18 (slit) having a torcross reduction effect.

  Torcross is related to the fuel consumption of a vehicle. For example, in the case of a light vehicle, a decrease of 0.05 N · m in torque cross contributes to an improvement of about 0.1% in fuel consumption. What leads to a decrease in Torcross of 0.01 N · m (corresponding to a decrease in fuel consumption of 0.02%) is a level worthy of contribution to fuel saving in the automotive field.

[Measurement of temperature of rib 13 surface of V-ribbed belt 1]
In the above friction loss measurement test, the temperature of the rib 13 surface of the V-ribbed belt 1 was measured. The measurement was performed using a surface thermometer (SC620 manufactured by FLIR SYSTEMS). (A) V-ribbed belt 1 having no groove, (B) 1.5 mm depth of groove 18 having a torcross reduction effect, and width 1 of groove 18 Comparison was made with a V-ribbed belt 1 of .4 mm [inclination angle θ = 20 °, random interval (15 pieces / belt 100 mm), U shape].

  The measurement results are shown in FIG. The surface temperature (46.4 ° C.) of the V-ribbed belt 1 (B) provided with the groove 18 is about 21 ° C. compared to the surface temperature (67.6 ° C.) of the V-ribbed belt 1 (A) without the groove 18. It was confirmed that the temperature decreased.

[Belt durability test]
The V-ribbed belt 1 having the dimensions and shapes used in the above test was subjected to endurance running with a high-temperature, low-tensile reverse bending tester, and the belt temperature transition and endurance life were verified (the target of life is 200 hours or more).

[Method of durability test (high temperature low tension reverse bending test)]
As shown in FIG. 12, the high-temperature low-tension reverse bending test includes a driving pulley (Dr, diameter 120 mm), an idler pulley (Id, diameter 85 mm), a driven pulley (Dn, diameter 120 mm), and a tension pulley (Ten, diameter 45 mm). ) Are placed in order on each pulley of the testing machine, and the V-ribbed belt 1 (six 6 ribs 13, length 1100 mm) is hung, the winding angle of the V-ribbed belt 1 around the tension pulley is 90 degrees, and the idler The V-ribbed belt 1 is run by applying a load to the drive pulley under the test conditions of 120 ° C., the ambient temperature of 120 ° C., the drive pulley speed of 4900 rpm, and the belt tension of 40 kgf / 3 rib. The pulley was run with a load of 12 PS.

[Results of durability test (high temperature low tension reverse bending test)]
In the above test, (A) V-ribbed belt 1 having no groove and (B) groove 18 having a torcross reduction effect, depth 1.5 mm, width 1.4 mm [inclination angle θ = 20 °, random interval (15 A book / belt 100 mm) and a U-shaped V-ribbed belt 1 were endured and compared. FIG. 13 shows the transition of the surface temperature of the rib 13 of the V-ribbed belt 1 measured with a surface thermometer (SC620 manufactured by FLIR SYSTEMS) during the endurance running. At the beginning of traveling, the pulley was wound around with a high initial tension, so the contact with the pulley was strong, and the surface temperature increased due to the effect of frictional heat. The surface temperature of the V-ribbed belt 1 provided with 18 was lower than that of the V-ribbed belt 1 without the groove 18. As a result, the V-ribbed belt 1 without the groove 18 had a life of 447 hours, but the V-ribbed belt 1 with the groove 18 traveled to 750 hours and had a life. It can be seen that the provision of the groove 18 suppresses the deterioration of the rubber of the running V-ribbed belt 1 due to heat and improves the durability life.

[Transmission performance test]
(A) V-ribbed belt 1 without grooves 18 and (B) depth 18 mm and width 1.4 mm of grooves 18 having an effect of reducing torque loss [inclination angle θ = 20 °, random interval (15 / belt 100 mm) ) And U-shaped V-ribbed belt 1 were compared for transmission performance by the following method.

[Transmission performance test method]
As shown in FIG. 14, the V-ribbed belt 1 (six number of ribs 13 and length) was added to a two-axis running tester composed of a driving (Dr.) pulley having a diameter of 120 mm and a driven (Dn.) Pulley having a diameter of 120 mm. 1100mm) and initial tension (200, 300N / two levels of one belt) is applied to the V-ribbed belt 1, and then the load (driven torque) of the driven pulley is increased under the conditions of the driving pulley speed of 2000 rpm and the room temperature atmosphere. The driven torque was measured when the slip ratio of the V-ribbed belt 1 with respect to the driven pulley reached 2%. The higher the numerical value of the driven torque, the better the transmission performance of the V-ribbed belt 1. The measurement was performed for each of the cases where water was poured into one V-ribbed belt (300 ml / min for 1 minute) (WET) and when water was not poured (DRY) (see FIG. 14).

[Results of transmission performance test]
The result of the transmission performance test is shown in FIG. According to this, it is understood that the V-ribbed belt 1 provided with the groove 18 and the V-ribbed belt 1 without the groove 18 are not greatly different in both the DRY and WET environments, and the same level of transmission performance can be maintained. It was.

[Soundproof test]
A V-ribbed belt 1 (six 6 ribs 13, length 1100 mm) is wound around a two-axis running test machine composed of a driving (Dr) pulley having a diameter of 55 mm and a driven (Dn) pulley having a diameter of 55 mm as shown in FIG. Hung, 600N / belt of initial tension was applied, and the sound produced when the drive pulley was rotated at 5000 rpm with no driven pulley loaded was measured.

  For the V-ribbed belt 1 provided with the grooves 18, U-shaped grooves 18 having a depth of 1.5 mm and a width of 1.4 mm were arranged at intervals of 15 / belt 100 mm.

Test belt: (A) No groove
(B) Right angle groove (inclination angle θ = 0 °, equidistant)
(C) Diagonal groove (inclination angle θ = 20 °, equidistant)
(D) Diagonal random groove (inclination angle θ = 20 °, random interval)

  The results of the pronunciation resistance test are shown in FIG. In the case of (D) the oblique random groove, the same result was obtained even at the inclination angle θ = 10, 30 °.

  (A) In the V-ribbed belt 1 in which the groove 18 (slit) is provided in the compression layer 12 on the inner peripheral side of the V-ribbed belt 1 with respect to the belt without the groove, a large signal (peak) corresponding to the arrangement period of the grooves 18 is generated. There is a lot of noise. This is because the rib 13 discontinuously enters and exits the pulley, so that a specific operation sound (a harmonic sound peak of the discontinuous rib) is generated due to the entry and exit.

  The level of noise is particularly large in the case of (B) right-angled grooves (arranged parallel to the width direction (θ = 0 °)), and the noise level is inclined (θ = 10-30 °). (C) In the oblique groove, a large periodic signal (peak) is seen, but the overall noise level is low. (B) In the right-angled groove, the plurality of discontinuous ribs existing in the width direction N of the V-ribbed belt enters and exits the pulley at the same time. This is because the noise level as a whole is reduced because the process proceeds sequentially from one end to the other end.

  Furthermore, in the (D) V-ribbed belt 1 in which the groove interval is random (irregular) within the belt circumference, a large periodic signal (peak) is also reduced, and the grooves 18 are arranged obliquely and randomly. Can be said to be effective.

  Next, for (D) oblique random grooves (inclination angle θ = 20 °, random intervals), the difference in sound pressure level when the depth and width of the U-shaped groove were varied was measured.

  In the V-ribbed belt 1 of Table 5, the frame portion having a sound pressure level of 70.00 dB or more has a large sound pressure level, and the noise reduction effect is insufficient. Therefore, the sound pressure level is sufficiently reduced because the groove width is 1.2 mm or less and the groove depth is 1.2 mm, the groove width is 1.6 mm or less and the groove depth is 1.3 to 1.8 mm. V-ribbed belt 1 having a groove width of 1.2 mm or less and a groove depth of 2.0 mm. This range was determined to be the optimum range of the depth and width of the groove (slit) having a noise reduction effect.

[Comprehensive evaluation]
Based on the above results, the depth and width of the groove 18 (slit) can be well-balanced to meet the demands of torque cross reduction (fuel saving), noise reduction (sounding resistance), durability life, pop-out resistance, and transmission performance. For example, in the case of the V-ribbed belt 1 having a rib height i = 2.0 mm, the depth of the groove 18 is 1.3 to 1.8 mm (65 to 90% of the rib height i), and the groove 18 is designed as follows. It can be said that the width is 1.2 to 1.6 mm, and the depth / groove width value of the groove 18 is 0.81 to 1.5.

  For example, in the case of the V-ribbed belt 1 having a rib height i = 2.9 mm, the depth of the groove 18 is 1.88 to 2.61 mm (65 to 90% of the rib height i), and the width of the groove 18 is 1. It can be said that the value of the depth / groove width of the groove 18 is in the range of 1.175 to 2.175.

As described above, the groove 18 (slit) is provided in the compression layer 12 on the inner peripheral side of the V-ribbed belt 1 to improve the flexibility of the V-ribbed belt 1 and to reduce the stress (compression stress) required to bend the compression layer 12. ) Can be reduced. As a result, bending loss is reduced, which contributes to the reduction of torque cross.
However, by providing the groove 18 in the compression layer 12, the rib 13 provided in the compression layer 12 discontinuously enters and exits the pulley (the driving pulley 2 and the driven pulley 3). In some cases, the peak of the harmonic sound of the continuous ribs is generated according to the interval period of the grooves 18 and becomes a loud noise. In particular, when the groove 18 is arranged parallel to the V-ribbed belt width direction N of the V-ribbed belt 1 (θ = 0 °), the plurality of discontinuous ribs 13 existing in the V-ribbed belt width direction N enter and exit the pulley. As a result, the overall noise level becomes high. However, by disposing it at an inclination (θ = 10 to 30 °) with respect to the V-ribbed belt width direction N, the discontinuity of the discontinuous ribs 13 is at one end. Since it progresses sequentially from one part to the other end part (the entrance and exit of the discontinuous rib 13 to the pulley is dispersed), the noise level as a whole can be reduced.
Although the overall noise level is reduced by arranging the grooves 18 to be inclined with respect to the V-ribbed belt width direction N of the V-ribbed belt 1, the peak noise of the harmonics of the discontinuous ribs 13 may still remain. Therefore, by making the interval P (pitch pattern P) of the grooves 18 irregular (random) within the circumference of the V-ribbed belt, the peak noise of the harmonic sound can also be reduced.
Further, by making the shape of the groove 18 not U-shaped but U-shaped, it is possible to reduce the compressive stress generated near the rib base (rib 13 bottom) when bent. As a result, the internal heat generation of the V-ribbed belt 1 can be reduced.
If the width of the groove 18 is too narrow, the bending loss of the V-ribbed belt 1 is insufficiently reduced. On the other hand, if the width of the groove 18 is too wide, the noise level becomes high. Further, if the depth of the groove 18 is too small, the bending loss of the V-ribbed belt 1 is insufficiently reduced. On the other hand, if the depth of the groove 18 is too large, the distortion applied to the vicinity of the cord when the V-ribbed belt 1 is bent. In some cases, the energy increases, leading to pop-out of the core body 14. Therefore, the depth of the groove 18 is in the range of 65 to 90% of the rib height i, the width of the groove 18 is in the range of 1.2 to 1.6 mm, and the depth of the groove 18 / the width of the groove 18 is 0. By maintaining the transmission performance within the range of 81 to 2.2, torque cross reduction, noise reduction, distortion energy reduction (anti-pop-out), and belt internal heat generation (suppression of rubber hardness are suppressed while maintaining transmission performance. ) Can improve durability.

DESCRIPTION OF SYMBOLS 1 V ribbed belt 2 Drive pulley 3 Driven pulley 10 Power transmission mechanism 11 Stretching layer 12 Compression layer 13 Rib 14 Core 15 Adhesive layer 18 Groove (slit)
MV V-ribbed belt longitudinal direction N V-ribbed belt width direction P Interval (pitch pattern)

Claims (3)

A V-ribbed belt used by being wound around a pulley,
A stretch layer forming the back surface;
A compression layer provided on one surface of the stretch layer and having a plurality of ribs extending in parallel with each other along the longitudinal direction of the V-ribbed belt;
A core body embedded along the longitudinal direction of the V-ribbed belt between the stretch layer and the compression layer,
The compression layer has a plurality of grooves extending in the width direction of the V-ribbed belt,
The groove is disposed obliquely at an angle θ = 10 to 30 ° with respect to the width direction of the V-ribbed belt,
The grooves are arranged at irregular intervals within the circumference of the V-ribbed belt,
The shape of the groove is a U shape having a circular arc at the bottom and a uniform groove width over the depth direction,
The depth of the groove is in the range of 65 to 90% of the rib height;
The groove has a width of 1.2 to 1.6 mm,
The groove depth / the groove width value is in the range of 0.81 to 2.2;
A V-ribbed belt characterized by satisfying the following conditions.   2. The V-ribbed belt according to claim 1, wherein the number of the grooves is 15 to 16 per 100 mm in a longitudinal direction of the V-ribbed belt. The V-ribbed belt according to claim 1 or 2,
A plurality of pulleys around which the V-ribbed belt is wound,
At least one of the plurality of pulleys has an outer diameter of 65 mm or less.