JP2002286098A - Toothed belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothed belt capable of maintaining an automobile engine in normal operation by improving the modulus of elasticity to restrain the elongation of the belt thereby effecting an autotensioner to operate normally, thus applying a proper load to the belt. SOLUTION: The toothed belt is formed by providing a plurality of toothed parts 3 on a toothed belt 5 with core wires embedded therein along the longitudinal direction and covering the toothed part 3 with tooth facing cloth 4. The tensile elastic modulus of the toothed belt 5 thus obtained has a modulus of elasticity at least >=850 N/mm with a width of 30 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothed belt covered with a cloth, for example, for driving a camshaft of an automobile engine or a camshaft and an injection pump, and for synchronous transmission of a general industrial machine. Things. In particular, the present invention relates to a high-load belt, in which the abrasion resistance and the tooth chipping resistance are maintained while the belt is particularly improved to prevent elongation of the belt.

[0002]

2. Description of the Related Art Toothed belts for driving a camshaft, an injection pump, an oil pump, a water pump and the like of an automobile engine are designed to increase the load on the belt and reduce the size of the engine room as the engine output increases. The use environment of the toothed belt, such as an increase in the ambient temperature, has become particularly severe in recent years, so that further improvement in durability is required. Also, with regard to toothed belts used for general industry, it is required to extend a replacement cycle for driving a high load of an injection molding machine or the like.

[0003] The failure mode of the toothed belt is as follows: Belt cutting due to bending fatigue of the core wire and cracking due to insufficient heat resistance of rubber, overload, insufficient heat resistance of tooth cloth and tooth rubber, chipping due to wear of tooth cloth. Are roughly divided into With respect to the belt fatigue due to the bending fatigue of the cord and the lack of heat resistance of the rubber, improvements such as reduction in the cord material and cord configuration, and improvement in the heat resistance of the cord treatment agent have been carried out. Also, with respect to the improvement of the heat resistance of rubber, failures have been reduced due to the use of hydrogenated nitrile rubber and the like.

[0004]

In particular, a toothed belt for driving an engine or an industrial drive device in which a high load is applied to the belt causes the pulley shaft to bend due to the high load or the belt to run off-center. Abnormal wear on the side of the belt due to friction with the pulley flange and the like, and cutting and chipping due to damage to the side are likely to occur.

In addition, the belt is stretched due to a high load, the auto tensioner does not operate, an appropriate load is not applied to the belt, and a phenomenon that hinders normal operation of the engine occurs. If the mesh of the weave becomes large and the rubber of the belt body is exposed, the exposed rubber will be worn between the toothed pulley and scattered as rubber powder.

[0006] For the belt side wear, damage, and belt elongation, the cloth material on the surface of the toothed belt meshing with the pulley teeth is subjected to a treatment in which a fluorine resin or a layered graphite having a frictional coefficient reducing action is added, Although examination of the core material has been carried out, no sufficient improvement has been found yet.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention increases the elasticity of a toothed belt so as to suppress the elongation of the belt, allow the auto-tensioner to operate normally, and apply an appropriate load to the belt. Provides a belt that maintains normal operation of the engine.

According to the present invention, there are provided a plurality of rubber-based tooth portions arranged at predetermined intervals along a longitudinal direction;
In a toothed belt having a back made of rubber as a base material in which a core wire is embedded, and having a tooth cloth covered with a tooth cloth, the toothed belt has a tensile modulus of elasticity of 850 N / mm or more in a width of 30 mm. In a toothed belt having:

According to the first aspect of the present invention, since the toothed belt is a toothed belt having a tensile elastic modulus of 30 mm width and an elastic modulus of 850 N / mm or more, by improving the tensile elastic modulus of the belt, The belt tension can be suppressed, and the movement of the auto tensioner can be suppressed to the proper movable range of the auto tensioner itself.

According to a second aspect of the present invention, there is provided the toothed belt according to the first aspect, wherein 1 to 20 parts by mass of short fibers are blended in at least the rubber layer on the back.

According to the second aspect of the present invention, by blending at least 1 to 20 parts by mass of short fibers into the rubber layer at the back portion, friction with an idler or tensioner pulley surface which comes into contact with the back surface of the belt on the belt layout. The coefficient can be reduced, the stress at the time of friction between the belt side surface and the pulley flange contacting during running can be reduced, and the side surface can be prevented from being worn or damaged.

The invention according to claim 3 is the toothed belt according to claim 1, wherein the rubber is obtained by adding 15 to 40 parts by mass of a metal salt of unsaturated carboxylic acid to hydrogenated nitrile rubber based on the total polymer. .

According to a third aspect of the present invention, in the toothed belt according to the first aspect, the rubber is obtained by adding 15 to 40 parts by mass of a metal salt of an unsaturated carboxylic acid to a hydrogenated nitrile rubber based on the total polymer. Because of this, the backside hardness of the belt is moderate, the rubber is not easily deformed when a constant stress is applied, heat is hardly generated, and the resistance under high load does not increase, so elongation occurs during belt running do not do.

[0014] The invention according to claim 4 is the toothed belt according to claim 2, wherein the rubber is obtained by adding 5 to 15 parts by mass of a metal salt of unsaturated carboxylic acid to hydrogenated nitrile rubber based on the total polymer. .

According to a fourth aspect of the present invention, in the toothed belt according to the second aspect, the rubber is obtained by adding 5 to 15 parts by mass of a metal salt of an unsaturated carboxylic acid to a hydrogenated nitrile rubber based on the total polymer. Because of this, the backside hardness of the belt is moderate, the rubber is not easily deformed when a constant stress is applied, heat is hardly generated, and the resistance under high load does not increase, so elongation occurs during belt running do not do.

The invention according to claim 5 is the toothed belt according to any one of claims 1 to 4, wherein the back surface hardness of the toothed belt is 80 degrees or more (JISA type hardness meter) or more.

According to the fifth aspect of the present invention, the back hardness of the toothed belt is at least 80 degrees (JISA hardness meter),
Since it is preferably at least 85 degrees, deformation of the rubber can be suppressed even when a stress is applied. For this reason, heat generation during running of the belt is suppressed, and resistance during friction can be reduced. As a result, wear and damage on the side surface of the belt during running of the belt can be reduced.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is an overall perspective schematic view of the toothed belt according to the present embodiment. In FIG. 1, a toothed belt 5 includes a plurality of tooth portions 3 arranged at predetermined intervals along a longitudinal direction, and a plurality of tooth portions 3.
, A core wire 1 embedded in the back portion 2, and a tooth cloth 4 coated on the surface of the tooth portion 3.
The back part 2 and the tooth part 3 constitute a belt body formed of the rubber layer 9. Further, the tooth cloth 4 is configured using a fiber material formed by weaving a weft 7 extending in the longitudinal direction of the belt and a warp 8 extending in the width direction of the belt.

Here, the tensile elastic modulus of the toothed belt has an elastic modulus of 850 N / mm or more in a width of 30 mm,
More preferably, an elastic modulus of 880 N / mm or more with a width of 30 mm is preferable. Here, the tensile modulus of the belt, cord species used for the belt, Kokorosen径, is affected by the cord pitch. Therefore, by these combinations, the tensile modulus of the toothed belt is at least 850 N for a width of 30 mm.
/ Mm or more.

Generally, a glass core wire or an aramid core wire is used as the core wire. In addition, polybenzoxazole, polyparaphenylene naphthalate, polyester,
Any of twisted cords composed of acrylic, carbon, and steel can be used. The composition of the glass core wire is E glass, S
Any glass (high-strength glass) may be used and is not limited by the thickness of the filament, the number of converging filaments, and the number of strands. Further, a sizing agent used as a bonding agent and a protective material for a glass filament at the time of bending, R
It is not limited to FL, overcoat agent and the like. On the other hand, the aramid core wire is not limited by the difference in the molecular structure of the material, the core wire configuration, the size of the filament, or the adhesive treatment agent.

The polybenzoxazole core wire is formed of a liquid crystal spun fiber of polyparaphenylene benzobisoxazole (hereinafter abbreviated as PBO fiber). The PBO fiber is a rigid, liquid crystal-spun fiber of polyparaphenylene benzobisoxazole having a very linear molecular structure, and has strength and elastic modulus more than twice that of known para-type aramid fiber, heat resistance, It is an organic fiber which has excellent twist resistance, low hygroscopicity (0.6%), and good dimensional stability when absorbing and desorbing moisture.

Aramid cords, which are existing tensile constituent fibers, are excellent in tensile strength constituent fibers with known strength and elastic modulus, but lack dimensional stability due to high hygroscopicity. The above PBO fiber constituting the tensile body of the present invention has strength,
Not only does the modulus of elasticity far exceed that of existing fibers, but it also has low moisture absorption and good dimensional stability, and therefore exhibits excellent performance using toothed belts for automobiles.

The material of the rubber compound forming the belt body is not particularly limited, and an appropriate material is appropriately selected according to the use conditions. In the case of toothed belts for automobile engines and various engines, H-NBR, C with heat resistance and oil resistance
R, CSM, etc. are used. Toothed belts used for general industrial machines include H-NBR, CR, CSM,
NBR, ethylene propylene diene monomer (EPD
M), ethylene propylene copolymer (EPR), SB
R, isopropylene rubber (IR), natural rubber (NR),
Any of fluorine rubber, silicon rubber and the like can be used. In the case of such a toothed belt, the use of the tooth cloth described with reference to FIG. 1 is effective.

As the material of the fibrous material forming the weft, the warp 8 and the like of the tooth cloth 4, any one of nylon, aramid, polyester, polybenzoxazole, cotton and the like or a combination thereof can be adopted. The form of the fiber may be any of a filament yarn and a spun yarn, and may be a twisted yarn of a single composition, a mixed twisted yarn, or a mixed spun yarn. Further, the weaving configuration may be any of a twill weave, a satin weave, and a plain weave.

The rubber layer 9 of the spine 2 is mixed with 1 to 20 parts by mass of the short fiber 17 based on 100 parts by mass of the rubber constituting the rubber layer 9. Here, as the short fiber 17, cotton, vinylon, aramid, inorganic fiber, or the like that does not have a high melting point or a melting point that is difficult to melt at a low temperature during friction is preferable. Its length is preferably 5 mm or less. Fiber length is 5m
If it exceeds m, the rubber is likely to be oriented when it is rolled into a rolled sheet with a calender or an extruder, and when it becomes a belt, cracks are likely to be generated early due to bending. Also, the orientation direction of the short fibers is preferably the belt width direction,
The orientation may be in the belt length direction. When the blending amount of the short fibers is less than 1 part by mass, the effect of blending the short fibers does not appear. On the other hand, when the amount of the short fibers exceeds 20 parts by mass, the hardness of the belt back portion 2 becomes too large, and the belt rigidity increases. Too much.

The belt backside hardness is at least 80 degrees or more, preferably 85 degrees or more (JISA). In order to make the back surface hardness at least 80 degrees or more, as a rubber compound, H-NBR is used, or an unsaturated carboxylic acid metal salt is added to H-NBR in an amount of 15 to 40 parts by mass, or Add 5 to 15 parts by mass. If the amount of the unsaturated carboxylic acid metal salt is less than 5 parts by mass, the rubber hardness will not be the predetermined hardness, while if it exceeds 40 parts by mass, the rubber hardness will be too large, the belt rigidity will be high, and the bending fatigue resistance will be reduced. Inferior belt life is shortened.

The above-mentioned hydrogenated nitrile rubber includes:
From the viewpoint of heat resistance, the hydrogenation rate needs to be at least 90% or more, and is preferably 92 to 98%. By blending a metal salt of an unsaturated carboxylic acid with the hydrogenated nitrile rubber, the modulus (tensile modulus) and hardness are increased, and the modulus (tensile modulus), elongation at break, and higher In order to secure the tear strength and hardness, as described above, the unsaturated carboxylic acid metal salt is added to the hydrogenated nitrile rubber in an amount of 15 to the total polymer.
When the unsaturated carboxylic acid is mixed with 5 to 15 parts by mass, the short fiber is mixed with the polymer component 100 in the rubber compounding.
1 to 20 parts by mass with respect to.

[0028]

Next, the present invention will be described specifically with reference to examples. (Example) Rubber having the composition shown in Table 1 was kneaded in a usual manner, and rubber sheets A-1 to A-3 having a predetermined thickness were adjusted using a calender roll. The tooth cloth was subjected to the treatment shown in Table 2 using the fibers shown in Table 2 to obtain B-1. In the RFL treatment in Table 2, the tooth cloth was immersed in an RFL treatment solution having the composition of C-1 shown in Table 3,
And then heat treated at 180 ° C. for 2 minutes. In addition, the rubber glue treatment in Table 2 was carried out using the C-
A rubber compound of 2-C-4 was dissolved in MEK and toluene, and then treated with a polyaryl polyisocyanate (PAPI) as an isocyanate compound.
The tooth cloth is immersed and dried in a treatment liquid to which Nocrack NBC (anti-aging agent) or a lubricant such as fluororesin powder or graphite is appropriately added and mixed.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

Next, the above-mentioned tooth cloth was wound around a mold having 120 teeth of S8M tooth profile for producing a belt, and a pair of SZ twisted RFL
A core wire shown in Table 4 which was bonded with a rubber paste obtained by dissolving a hydrogenated nitrile rubber in a solvent such as toluene was wound around a spiral at a pitch shown in Table 5 with a predetermined tension. The rubber sheet of Table 1 was stuck on this core wire. Further, the mixture is put into a vulcanizing can and a tooth profile is formed by a normal press-fitting method, and then pressure-cured at 165 ° C for 30 minutes, and the back surface of the belt is polished to a constant thickness and cut to a constant width (30 mm). Thus, a running toothed belt was obtained. The back hardness of each belt is shown in Table 5.

[0033]

[Table 4]

[0034]

[Table 5]

The size of the manufactured belt was 30 belt widths.
mm, belt tooth profile S8M, number of teeth 120, usually 1
20S8M30S is displayed. As a running test device,
A test apparatus having a layout including a crank pulley 11 having 22 teeth, a cam pulley 13 having 44 teeth, a water pump pulley 15 having 19 teeth, an eccentric pulley 19 and an idler 21 shown in FIG. 2 is used. Crank pulley rotation speed 4000rpm
The running test was carried out with the effective tension applied to the belt at 3000N and the initial tension at 350N.
The push rod movable allowance 25 was investigated. Table 6 shows the results.

Next, the tensile modulus of the belt was measured. As shown in FIG. 3, the elastic modulus of the belt was measured using a measuring machine 26. The belt body 5 was hung on the pulley, the lower pulley 29 was lowered, and tension was applied to the belt body 5. As for the tension, a smooth load was applied from 98 N to 1960 N, and the SS curve of the stress applied to the belt body 5 and the measured value of the axial separation was obtained. FIG. 4 shows the stress-strain curve of the belt.

In FIG. 4, the stress at the curved portion, that is, the strain with respect to the load (588N to 1764N) was determined. That is, the measured values of the axial separation are plotted, and a first-order regression line is obtained at that point, and the gradient thereof is the tensile elastic modulus in a belt ring shape (for two belts). 1 / of this value
2 was defined as the tensile modulus of the toothed belt body. Table 6 shows the results.

[0038]

[Table 6]

The movable allowance of the auto tensioner is 4 to 18 m.
m, and if it exceeds 18 mm, no load is applied and the engine does not operate. Therefore, when continuous operation is performed,
It is advantageous that the moving allowance is small. From the results in Table 6, when the belt elasticity is 830 N / mm or less, the movable allowance of the push rod is 10 mm or more, and the movable allowance of the auto tensioner is 14 mm or more. At this time, the remaining movable allowance is less than 4 mm. When the engine is operated continuously, the remaining movable allowance approaches almost 0 mm, and it becomes difficult to start the movable engine. For this reason, the belt elastic modulus needs to be 850 N / mm or more, and preferably 880 N / mm or more. Therefore, it can be seen that the working example has an extremely small push rod moving allowance as compared with the comparative example, and is considerably effective.

[0040]

As described above, according to the present invention, since the toothed belt has a tensile elastic modulus of 30 mm width and an elastic modulus of 850 N / mm or more, the tensile elasticity of the belt is improved. As a result, there is an effect that the elongation of the belt can be suppressed and the movement of the auto tensioner can be suppressed to the proper movable range of the auto tensioner itself.

According to the second aspect of the present invention, by blending at least 1 to 20 parts by mass of short fibers into at least the rubber layer on the back portion, the friction coefficient with the surface of the idler or the tensioner pulley that comes into contact with the back surface of the belt on the belt layout. This reduces the stress at the time of friction between the belt side surface and the pulley flange that comes into contact with the belt during traveling, and has the effect of preventing the side surface from being worn or damaged.

According to the third aspect of the present invention, there is provided the toothed belt according to the first aspect, wherein the rubber is obtained by adding 15 to 40 parts by mass of a metal salt of an unsaturated carboxylic acid to a hydrogenated nitrile rubber based on the total polymer. Therefore, the backside hardness of the belt is moderate, the rubber is hard to deform when a constant stress is applied, hardly generates heat, and the resistance under high load does not increase, so no elongation occurs during belt running There is an effect that.

According to a fourth aspect of the present invention, in the toothed belt according to the second aspect, the rubber is obtained by adding 5 to 15 parts by mass of a metal salt of an unsaturated carboxylic acid to a hydrogenated nitrile rubber based on the total polymer. Therefore, the backside hardness of the belt is moderate, the rubber is hard to deform when a constant stress is applied, hardly generates heat, and the resistance under high load does not increase, so no elongation occurs during belt running There is an effect that.

According to the fifth aspect of the present invention, the back surface hardness of the toothed belt is at least 80 degrees (JISA hardness meter), preferably at least 85 degrees, so that even when stress is applied, Rubber deformation can be suppressed. For this reason, heat generation during running of the belt is suppressed, and resistance during friction can be reduced. Thereby, there is an effect that wear and damage of the belt side surface during belt running can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall perspective schematic view of a toothed belt according to an embodiment.

FIG. 2 is a schematic view of a running test device for a toothed belt.

FIG. 3 is a schematic view of a belt axis separation measuring device.

FIG. 4 is a stress-strain curve of a toothed belt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 core wire 2 back part 3 tooth part 4 tooth cloth 5 toothed belt 7 weft 8 warp 9 rubber layer 11 crank pulley 13 cam pulley 15 water pump pulley 17 short fiber 19 eccentric pulley 21 idler 23 auto tensioner 25 push rod movable allowance 26 measuring scale Machine 27 Upper pulley 29 Lower pulley 31 Distance between shafts

Claims (5)

[Claims] A plurality of rubber-based teeth disposed at predetermined intervals along a longitudinal direction; and a rubber-based back having a core wire embedded therein. In a toothed belt coated with cloth, the tensile elasticity of the toothed belt is 30 m.
A toothed belt having an elastic modulus of at least 850 N / mm or more in m width. 2. The toothed belt according to claim 1, wherein 1 to 20 parts by mass of short fibers are blended in at least the rubber layer on the back. 3. The toothed belt according to claim 1, wherein the rubber is obtained by adding 15 to 40 parts by mass of a metal salt of an unsaturated carboxylic acid to a hydrogenated nitrile rubber based on the total polymer. 4. The toothed belt according to claim 2, wherein the rubber is obtained by adding 5 to 15 parts by mass of a metal salt of an unsaturated carboxylic acid to a hydrogenated nitrile rubber based on the total polymer. 5. The back hardness of the toothed belt is 80 degrees (J).
The toothed belt according to any one of claims 1 to 4, which is not less than an ISA type hardness meter.