JP2005076704A - V-ribbed belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a V-ribbed belt, in particular applicable favorably to a multi-shaft driving device, free of a steep drop of its tension and excellent in the dimensional stability with the time even in case an elongation is generated in the belt owing to its wear etc. <P>SOLUTION: The multi-shaft driving device whereto the V-ribbed belt is applied is equipped with a generator 13 using the crank shaft of an engine as its drive shaft 11 and having a large rotary inertia in at least one of the follower shafts 14 and used upon being suspended on a drive pulley 16 of a multi-shaft driving device 10 free of equipment of any auto-tensioner and at least one follower pulley 17/18, wherein the V-ribbed belt 1 is composed of an elongation part 2, a cushion rubber layer 5 in which a core wire 4 is embedded stretching in the belt longitudinal direction, and a compression part 6 having a plurality of ribs 7 extending in the belt circumferential direction in such a fashion as adjoining to the cushion rubber layer 5, and the core wire 4 is made from a twisted yarn cord formed by twisting together filaments of poly-trimethylene terephthalate fibers and having a total fineness of 4,000-12,000 dtex. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a V-ribbed belt that is suitably mounted on a drive device, particularly a multi-axis drive device.

  The V-ribbed belt has a core wire embedded in a cushion rubber layer, a cover canvas is laminated on the cushion rubber layer as necessary, and a plurality of rib portions are provided below the cushion rubber layer. This V-ribbed belt has been widely used to drive auxiliary equipment such as automobile air compressors and alternators in place of the V-belt. In recent years, the pulley diameter has become smaller due to the downsizing of the engine room and the weight reduction of the engine. At the same time, serpentine driving is being attempted.

  In the serpentine drive, a plurality of pulleys connected to an auxiliary machine are arranged on the same plane, and a single belt is hung on these pulleys.Because the belt is arranged in a large and winding state, the belt is It will be used in extremely severe conditions, and higher power transmission and higher performance are required.

  In order to meet such demands, V-ribbed belts with improved belt modulus and improved transmission performance are used for general purposes. Specifically, there is a V-ribbed belt in which the belt modulus is increased by using a cord made of a highly elastic fiber, for example, polyethylene terephthalate fiber (PET fiber), as the belt core. (See Patent Document 1)

  However, when belt elongation occurs due to wear of the rib rubber or the like, the belt may fall into the pulley, and the tension applied to the belt may drop rapidly. This is due to the characteristics of the polyethylene terephthalate fiber constituting the core wire, that is, the crystal elastic modulus is high and the molecule has a structure that is difficult to deform. In the conventional apparatus, this was dealt with by adjusting the tension with an auto tensioner. However, in recent years, there are many layouts in which an auto tensioner is not installed in the drive device, and PET fibers having poor elasticity recovery cannot cope with this decrease in tension.

On the other hand, there is known a V-ribbed belt in which the core is made of polyamide 6.6 fiber to lower the modulus of the belt and suppress the decrease in tension. (See Patent Document 2)
Japanese Patent Laid-Open No. 7-127690 US Patent Application Publication No. 2002/0165058

  When such a low-modulus polyamide fiber cord was used, a sudden drop in tension as seen with a PET fiber cord was not found, and it was expected as a belt that does not require an autotensioner. However, the polyamide fiber has a high hygroscopic property, causing a shrinkage with time due to the humidity and greatly changing the belt size, which causes a problem in practical use.

  The present invention improves such problems, and even when elongation occurs due to belt wear or the like, the tension does not drop sharply and is excellent in dimensional stability over time, particularly in a multi-axis drive device. An object is to provide a suitable V-ribbed belt.

  That is, the invention according to claim 1 of the present application is a belt in which a core wire is embedded along the longitudinal direction of the belt between the extension portion and the compression portion having a plurality of ribs extending in the belt circumferential direction. A V-ribbed belt comprising polytrimethylene terephthalate fibers.

  The invention according to claim 2 of the present application is the V-ribbed belt according to claim 1, wherein the total fineness of the core wire is 4,000 to 12,000 dtex.

  The invention according to claim 3 of the present application is the V-ribbed belt according to claim 1 or 2, wherein the tensile force required to stretch the V-ribbed belt by 2% is 100 to 250 N / rib, and the belt has 147 N / The belt has a shrinkage force of 50 to 150 N / 5 cords generated when the belt is heated for 30 minutes under an initial load of 5 cords and left in a 100 ° C. atmosphere for 30 minutes.

  A fourth aspect of the present invention is the V-ribbed belt according to any one of the first to third aspects, and is used in a multi-axis drive device.

  The invention according to claim 5 of the present invention is the V-ribbed belt according to claim 4, wherein the crankshaft of the engine is a drive shaft, and at least one of the driven shafts has a generator having a large rotational inertia, and an auto tensioner is provided. It is characterized by being used by being suspended on a drive pulley of at least one multi-axis drive device and at least one driven pulley.

  V-ribbed belts using polytrimethylene terephthalate fiber cords as the core wire have a low modulus and are elastic. Can be maintained. The belt of the present invention is also suitable for use under harsh conditions in a multi-axis drive device, and since the heat shrinkage force is set to a specific value, self-adjustment of tension is possible, and no auto tensioner is installed. It can also be used in the apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic view showing a multi-axis drive device using a V-ribbed belt according to the present invention, and FIG. 2 is a cross-sectional perspective view showing a V-ribbed belt used in the multi-axis drive device.

  In FIG. 1, in the multi-axis drive device 10 used here, a crankshaft of an engine is used as a drive shaft 11, a generator 13 having a large rotational inertia, for example, on one driven shaft 12, and an air compressor, for example, on another driven shaft 14. 15, pulleys 16, 17 and 18 are mounted on these shafts, respectively, the V-ribbed belt 1 is suspended on these pulleys 16, 17 and 18, and the tension pulley 19 is brought into contact with the back surface of the V-ribbed belt 1. .

  The V-ribbed belt 1 used here includes an extension portion 2 made of a cover canvas 3, a cushion rubber layer 5 in which a cord 4 made of a cord is embedded, and a compression portion 6 that is an elastic layer below the cord rubber layer 5. . The compression portion 6 has a plurality of trapezoidal ribs 7 having a substantially triangular cross section extending in the belt longitudinal direction.

  For the rib 7, hydrogenated nitrile rubber, chloroprene rubber, natural rubber, CSM, ACSM, SBR, ethylene-α-olefin elastomer is used, and the hydrogenated nitrile rubber has a hydrogenation rate of 80% or more, In order to exhibit the ozone resistance characteristic, 90% or more is preferable. Hydrogenated nitrile rubber having a hydrogenation rate of less than 80% has extremely low heat resistance and ozone resistance. Considering oil resistance and cold resistance, the amount of bound acrylonitrile is preferably in the range of 20 to 45%. Among these, an ethylene-α-olefin elastomer having oil resistance and cold resistance is preferable.

  A typical example of the ethylene-α-olefin elastomer is EPDM, which refers to an ethylene-propylene-diene monomer. Examples of diene monomers include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and the like.

  For crosslinking the rubber, sulfur or organic peroxide is used. Specific examples of the organic peroxide include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 1.1-t-butylperoxy-3.3.5-trimethylcyclohexane, and 2. 5-di-methyl-2.5-di (t-butylperoxy) hexane, 2.5-di-methyl-2.5-di (t-butylperoxy) hexane-3, bis (t-butylperoxydi-isopropyl) benzene, Examples include 2.5-di-methyl-2.5-di (benzoylperoxy) hexane, t-butylperoxybenzoate, and t-butylperoxy-2-ethyl-hexyl carbonate. This organic peroxide is usually used alone or as a mixture in the range of 0.005 to 0.02 mol g with respect to 100 g of the ethylene-α-olefin elastomer.

  A vulcanization accelerator may be blended. Examples of vulcanization accelerators include thiazole, thiuram, and sulfenamide vulcanization accelerators. Specific examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole, 2-mercaptothiazoline, dibendiazyl, Disulfide, zinc salt of 2-mercaptobenzothiazole, and the like, and thiuram vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, N, N'-dimethyl. -N, N'-diphenylthiuram disulfide and the like, and specific examples of sulfenamide vulcanization accelerators include N-cyclohexyl-2-benzothiazylsulfenamide, N, N'-cyclohexyl-2 -Benzothiazylsulfenamide and the like. As other vulcanization accelerators, bismaleimide, ethylenethiourea, and the like can be used. These vulcanization accelerators may be used alone or in combination of two or more.

  Further, by adding a co-agent, it is possible to increase the degree of cross-linking and prevent problems such as adhesive wear. Examples of the crosslinking aid include TIAC, TAC, 1,2 polybutadiene, metal salt of unsaturated carboxylic acid, oximes, guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN′-m- Usually used for peroxide crosslinking such as phenylene bismaleimide and sulfur.

  In addition, other rubber compounds such as silica, carbon black, reinforcing agents such as calcium carbonate, fillers such as calcium carbonate, talc, plasticizers, stabilizers, processing aids, and coloring agents are used as necessary. What is used is used.

  Further, the rib 7 is mixed with short fibers made of nylon 6, nylon 66, polyester, cotton, and aramid to improve the side pressure resistance of the rib 7, and on the surface of the rib 7 serving as a surface in contact with the pulley. The short fiber is protruded, the friction coefficient of the rib 7 is lowered, and the noise during belt running is reduced. Of these short fibers, it is desirable to use an aramid fiber having rigidity, strength and abrasion resistance, and other fibers in combination.

  In order for the aramid short fibers to sufficiently exhibit the above-described effects, the fiber length of the aramid fibers is 1 to 20 mm, and the amount added is 1 to 30 parts by mass with respect to 100 parts by mass of rubber. This aramid fiber has an aromatic ring in its molecular structure, for example, trade names Conex, Nomex, Kevlar, Technora, Twaron, etc. If the added amount of short aramid fiber is less than 1 part by mass, the rubber of the rib 7 tends to stick and wear, and if it exceeds 30 parts by mass, the short fiber is uniformly in the rubber. Will not disperse.

  In order to improve the adhesion of the aramid short fiber to the rubber of the rib 7, it is preferable that the short fiber is subjected to an adhesive treatment with a treatment liquid selected from an epoxy compound and an isocyanate compound.

  The core wire 4 is made of polytrimethylene terephthalate (PTT) fiber. PTT is a polyester obtained by polycondensation of terephthalic acid and 1,3-propanediol, and has a bent crystal structure because the alkylene chain has an odd number (three) of methylene groups. That is, the PTT fiber exhibits characteristics such that the molecule is easily deformed and thus has a low crystal elastic modulus, and the molecule expands and contracts, so that the stretch property is excellent. A belt using a core wire made of this PTT fiber has a low modulus and is elastic. On the other hand, PET fibers having an even number of alkylene chains (two) have a high crystal elastic modulus and poor stretchability, so that a transmission belt using a PET fiber cord has a high modulus.

  As a specific configuration of the core 4, a cord having a total fineness of 4,000 to 12,000 dtex obtained by twisting together PTT fiber filament groups is preferably used. It is desirable that the number of upper twists of this cord is 4 to 20/10 cm and the number of lower twists is 9 to 39/10 cm. When the total fineness is less than 4,000 dtex, the modulus and strength of the cord are too low. When the total fineness is more than 12,000 dtex, the belt becomes thick and the bending fatigue property is deteriorated.

  The core wire 4 is preferably subjected to an adhesive treatment. For example, (1) After impregnating a pretreated dip with a tank containing a treatment liquid selected from an epoxy compound and an isocyanate compound, (2) It was dried by passing it through a drying oven set at a temperature of 160 to 200 ° C. for 30 to 600 seconds, (3) subsequently immersed in a tank containing an adhesive solution made of RFL, and (4) set at a temperature of 160 to 220 ° C. There is a method of passing through a stretching heat setting processor for 30 to 600 seconds and stretching by 1 to 6% to obtain a stretching treatment cord.

  Examples of the epoxy compound include reaction products of polyhydric alcohols such as ethylene glycol, glycerin and pentaerythritol, polyalkylene glycols such as polyethylene glycol and halogen-containing epoxy compounds such as epichlorohydrin, resorcin, bis (4- It is a reaction product with polyhydric phenols such as (hydroxyphenyl) dimethylmethane, phenol-formaldehyde resin, resorcinol-formaldehyde resin, and halogen-containing epoxy compounds. This epoxy compound is used by mixing with an organic solvent such as toluene or methyl ethyl ketone.

  Examples of the isocyanate compound include 4,4'-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, P-phenyl diisocyanate, and polyaryl polyisocyanate. This isocyanate compound is also used by mixing with an organic solvent such as toluene or methyl ethyl ketone.

  The RFL liquid is obtained by mixing an initial condensate of resorcin and formalin into a latex. Examples of the latex used here include chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile, NBR, and the like.

  It is desirable that the cord subjected to the stretching heat setting treatment has a spinning pitch, that is, a winding pitch of the core wire, of 0.7 to 1.7 mm. If the length is less than 0.7 mm, the cord cannot ride on the adjacent cord and cannot be wound. On the other hand, if it exceeds 1.7 mm, the modulus of the belt gradually decreases.

  The cover canvas 3 is a fabric woven into plain weave, twill weave, satin weave, or the like using yarn made of cotton, polyamide, polyethylene terephthalate, aramid fiber or the like.

  In the V-ribbed belt using the core 4, the tensile force necessary to extend the V-ribbed belt by 2% is 100 to 250 N / rib, more preferably 130 to 210 N / rib. Even when belt elongation occurs due to wear of rib rubber or the like, stable tension can be maintained without causing a rapid drop in tension. If it exceeds 250 N / rib, a rapid drop in tension is observed when the belt is stretched, and if it is less than 100 N / rib, the belt tension is greatly lowered due to the core elongation.

  In addition, if the belt is subjected to an initial load of 147N / 5 cords and left to stand in a 100 ° C atmosphere for 30 minutes, the belt contracts when it is heated to give a characteristic of 50-150N / 5 cords. Even if the tension is self-adjustable, a belt with a low belt slip ratio and a long belt life can be obtained without installing an auto tensioner. When the belt shrinkage force is less than 50 N / 5 cords, the performance of adjusting the belt tension is poor and the slip ratio tends to increase. Further, when the belt shrinkage force is 150 N / 5 cords, the belt length shrinkage tends to increase, and the effect of reducing the slip ratio is small.

In the following, the present invention will be described in more detail with reference to specific examples.
Examples 1 and 2 and Comparative Examples 1 and 2
As core wires, 1,100 dtex polytrimethylene terephthalate fiber (PTT), 940 dtex nylon 6.6 fiber (N6.6), and 1,220 denier polyethylene terephthalate fiber (PET) in a 2 × 3 twist configuration. Then, an untreated cord twisted in a cord with an upper twist coefficient of 3.0 and a lower twist coefficient of 3.1 was prepared.

  Each untreated cord was pre-diped with 90 g of toluene and an adhesive composed of 10 g of PAPI (polyisocyanate compound manufactured by Kasei Upjohn Co., Ltd.), and then passed through a drying oven set at 200 ° C. for 2 minutes and dried. Subsequently, the adhesive comprising the RFL liquid shown in Table 1 was impregnated, and the PTT cord was heat treated at 190 ° C. for 2 minutes, and the N6.6 cord and PET cord were heat treated at 230 ° C. for 2 minutes. Heat stretched and fixed at a set stretch rate. Further, each cord was immersed in rubber paste diluted with the compounded rubber shown in Table 2 so as to have a solid content concentration of 10%, and then heat treated at 160 ° C. for 4 minutes to obtain an adhesive treatment cord.

The manufacturing method of the V-ribbed belt in the present embodiment is as follows.
First, a plain fabric made of cotton yarn of warps and wefts is wound around a cylindrical mold with 1 ply of a canvas with rubber coated with chloroprene rubber and then an adhesive rubber sheet made of a chloroprene rubber composition shown in Table 2 is wound. The cord was spun on top, and a rubber sheet in which short fibers were dispersed in the chloroprene rubber composition shown in Table 2 was wound to finish the molding. This was vulcanized at 160 ° C. for 30 minutes by a known method to obtain a cylindrical vulcanized rubber sleeve. In addition, the short fiber disperse | distributed to the rubber sheet which forms a compression part and a cushion rubber layer was previously immersed in the processing liquid which consists of 10g of PAPI (polyisocyanate compound by Kasei Upjohn) in 90g of toluene.

  The vulcanized rubber sleeve was mounted on a driving roll and a driven roll of a polishing machine, and was rotated after applying tension. A polishing wheel equipped with 150 mesh diamond on its surface was rotated at 1,600 rpm, and this was brought into contact with the vulcanization sleeve to polish the rib portion. The sleeve taken out from the polishing machine was placed in a cutting machine and then cut while rotating.

  In the manufactured V-ribbed belt, a cord made of each of the above-mentioned stretched and fixed processing cords is embedded in a cushion rubber layer, and one ply of a cotton canvas with rubber is laminated on the upper side, while a compression part is on the lower side of the cushion rubber layer. There were 3 ribs in the longitudinal direction of the belt. This V-ribbed belt was a K-type three-ribbed belt having a length of 1,100 mm according to the RMA standard, and had a rib pitch of 3.56 mm, a rib height of 2.9 mm, and a rib angle of 40 °.

  Next, the V-ribbed belt was evaluated. The results are shown in Table 3. The test method is as follows.

(1) Tensile force when the belt is stretched 2.0% The belt is pulled at a speed of 50 mm / min. The tensile force required to stretch the belt by 2.0% is measured, and the tension per rib (3.56 mm) is measured. Converted to force.

(2) Shrinkage force when the belt is dry Heat Remove the cushion rubber layer with the core wire embedded from the belt. Excess cords are removed from both sides of the cushion rubber layer, and a measurement sample consisting of five cords is prepared. An initial load of 147 N was applied to this measurement sample, and the sample was allowed to stand for 30 minutes in an atmosphere at 100 ° C., and then the generated shrinkage force was determined.

(3) Belt dry heat shrinkage rate The belt was allowed to stand in a 120 ° C. atmosphere for 30 minutes with no load, and the change rate of the belt outer circumference length before and after being left was determined.

(4) Belt tension retention rate The belt tension after 1 hour was measured by performing the running test shown in FIG. 3 while applying an initial tension of 391 N / rib to the belt and measuring the belt tension after 1 hour and 1,000 hours. The belt tension retention after 1,000 hours was calculated.

(5) Belt shrinkage with time The belt outer peripheral rate change rate after the belt was allowed to stand for 10 days at 40 ° C. and 90% humidity was examined.

  From the results shown in Table 3, it was found that the V-ribbed belt of the present invention had a lower modulus than the conventional V-ribbed belt and a high tension retention even after running. It was also found that the belt length shrinkage with time was small even when stored under wet heat, and the dimensional stability over time was excellent.

  A V-ribbed belt that is preferably used in a belt drive device, particularly in a car servantine drive, and is expected to reduce slip and reduce the belt life by suppressing belt elongation and tension drop.

It is the schematic which shows the multi-axis drive device using the V-ribbed belt which concerns on this invention. It is a cross-sectional perspective view which shows the V-ribbed belt used for the multi-axis drive device of this invention. It is a layout of a running test in evaluation of belt tension retention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 V ribbed belt 2 Expansion part 3 Cover canvas 4 Core wire 5 Cushion rubber layer 6 Compression part 7 Rib 10 Multi-axis drive device 11 Drive shaft 12 Drive shaft 13 Generator 14 Drive shaft 16 Drive pulley 17 Drive pulley 18 Drive pulley

Claims (5)

A belt in which a core wire is embedded along the longitudinal direction of the belt between the extension portion and a compression portion having a plurality of ribs extending in the belt circumferential direction, and the core wire is made of polytrimethylene terephthalate fiber. V-ribbed belt characterized by The V-ribbed belt according to claim 1, wherein the total fineness of the core wire is 4,000 to 12,000 dtex. The tensile force required to stretch the V-ribbed belt by 2% is 100 to 250 N / rib, and the belt was generated after the initial load of 147 N / 5 cords was applied to the belt and left at 100 ° C. for 30 minutes. The V-ribbed belt according to claim 1 or 2, wherein the hot contraction force is 50 to 150 N / 5 cords. The V-ribbed belt according to any one of claims 1 to 3, which is used in a multi-axis drive device. An engine crankshaft is used as the drive shaft, and at least one of the driven shafts is provided with a generator having a large rotational inertia, and is suspended on at least one driven pulley of a multi-shaft drive device that does not have an auto tensioner. The V-ribbed belt according to claim 4, which is used.

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