JP2001090789A - V ribbed belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a V ribbed belt improving transmission capacity of the belt without thickening a conductor diameter, enabling the belt to self-adjust it even if tensile force reduces by abrasion and requiring no automatic tensioner. SOLUTION: This V ribbed belt is arranged in a spiral shape at a prescribed pitch in the belt width direction so that a conductor 4 formed of polyethylene-2,6-naphthalate fiber or polyvinyl alcohol fiber extends in the almost belt lengthwise direction. The conductor 4 is arranged so that the total denier number becomes 5000 to 8000 and an elastic modulus of the belt when extending the belt up to 3% from 1% becomes 1800 to 4500 kgf per one rib.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a V-ribbed belt.

[0002]

2. Description of the Related Art In recent years, V-belts have been replaced with V-ribbed belts because the auxiliary drive transmission belts of automobiles have a high transmission capacity and a long life. However, even with the use of V-ribbed belts, there is a demand in the market for smaller pulleys and a narrower belt by reducing the number of ribs. The required load tends to increase year by year. That is, there is a demand for a V-ribbed belt having higher transmission and higher transmission capacity.

In order to meet such demands, there is a method of improving the belt transmission capability by increasing the tension applied to the belt. However, if the external force exerted by the belt on the shaft of the accessory increases, the service life of the bearing of the accessory decreases, or the belt itself generates heat. For example, the belt may be damaged early.

There is also a method of reducing the thickness of a belt. That is, this means that the height of the rib is reduced. However, according to this method, the surface pressure applied to the portion where the rib contacts the pulley is increased, and the wear of the rib is increased.

Further, there is a method of increasing the total denier of polyethylene terephthalate fiber (hereinafter referred to as "PET") mainly used as a core wire of a V-ribbed belt to make the core wire thicker. There is also a method of using aramid fiber having higher elasticity than PET as a core wire.

[0006]

However, thickening the core leads to an increase in the thickness of the belt, which increases the rigidity of the belt and deteriorates the bending fatigue resistance. In addition, when the aramid fiber is used as the core wire, the belt elasticity becomes too high, and when the ribs are worn, the belt falls into the pulley and the tension applied to the belt is reduced at once. There is a problem that tension cannot be recovered due to lack of a contracting function, and an auto tensioner must be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to improve the power transmission capacity of a belt without increasing the diameter of a core wire and to reduce the tension of the belt due to wear or the like. Another object of the present invention is to provide a V-ribbed belt which does not require an auto-tensioner by adjusting itself.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a V-ribbed belt having a highly elastic and heat-shrinkable polyvinyl alcohol (hereinafter referred to as "PVA") fiber or polyethylene-2,6-naphthalate (hereinafter referred to as "PVA"). Afterwards, "PEN"
) Fibers. Specifically, the invention of the present application is a V-ribbed belt spirally provided at a predetermined pitch in a belt width direction such that a cord formed of PVA fiber or PEN fiber extends substantially in the belt length direction. The above core wire has a total denier of 50
The belt elasticity at the time of stretching the belt from 1% to 3% is 1800 to 450 per rib.
It is characterized by being provided so as to be 0 kgf.

According to the above configuration, the core wire of the V-ribbed belt is formed of PEN fiber or PVA fiber, and these fibers have higher elasticity than PET fiber.
The transmission capacity of the belt can be improved. In addition, these fibers also have a heat shrinkage property, although not as much as PET fibers, so that even if the tension on the belt decreases due to the wear of the ribs, the fibers thermally contract and the tension on the belt recovers, and the aramid There is no need to use an auto-tensioner as in the case where a fiber core is used. That is, the V-ribbed belt according to the present invention has an advantage that the transmission capacity can be improved by the fixed tension applying method.

Here, if the total denier of the PVA fiber or the PEN fiber constituting the core wire is smaller than 5000, the strength and the elastic modulus of the belt cannot be maintained at a high level. The diameter becomes large, and the bending fatigue resistance of the belt becomes poor. Therefore, the total denier number of the cord is 5,000 to 80.
00 is better.

On the other hand, if the belt elastic modulus at the time of extending the belt from 1% to 3% is smaller than 1800 kgf per rib, the transmission capacity of the belt cannot be maintained high. The drop on the pulley greatly reduces the tension,
Transmission becomes impossible due to slip. Therefore, the above-mentioned belt elastic modulus is 1800-4500 kg per one rib.
It is good to be f.

Here, the belt elastic modulus when the belt is stretched from 1% to 3% is the belt elasticity obtained from the proportional relationship between the tension and the elongation in a region where the elongation of the belt is 1 to 3%. The rate is converted per rib.

The core wire has an apparent belt elastic modulus when the belt is stretched by 3% and the apparent belt elastic modulus per rib is 2000 to 50.
Desirably, it is provided so as to be 00 kgf. Also in this case, the apparent belt elastic modulus when the belt is stretched by 3% is 2,000 kgf per rib as in the above case.
If it becomes smaller, the transmission capacity of the belt cannot be maintained high, and if it becomes larger than 5000 kgf,
The drop into the pulley when the belt rib is worn causes a great decrease in the tension, and the transmission becomes impossible due to the slip.
Therefore, the apparent belt elastic modulus when the belt is stretched by 3% is preferably set to 2000 to 5000 kgf per rib.

Here, the apparent belt elastic modulus when the belt is stretched by 3% is obtained by dividing the tension required to stretch the belt by 3% by the distortion amount of 0.03 (3%). It is obtained by dividing by the number of ribs of the belt and converting to one rib.

[0015] In the V-ribbed belt configured as described above, when the core is held in a dryer at 150 ° C for 30 minutes, the core is extracted with respect to the length of the core extracted from the belt. The dry heat shrinkage, expressed as a percentage of the shrinkage length, is 0.1%.
It becomes 3 to 1.0%. Here, if the dry heat shrinkage is less than 0.3%, even if the tension applied to the belt decreases, self-adjustment due to belt shrinkage cannot be sufficiently achieved. on the other hand,
If it is larger than 1.0%, the daily size of the belt becomes too short, and it becomes difficult to mount the belt.

[0016]

Thus, according to the invention of the present application, the core wire of the V-ribbed belt is formed of PEN fiber or PVA fiber, and these fibers have higher elasticity than PET fiber. The transmission capacity can be improved. In addition, since these fibers also have heat shrinkage characteristics like PET fibers, even if the tension applied to the belt decreases due to the wear of the ribs, the fibers thermally shrink and the tension applied to the belt recovers, and the aramid fiber It is not necessary to use an auto-tensioner as in the case where the core wire is used. That is, the V-ribbed belt according to the present invention has an advantage that the transmission capacity can be improved by the fixed tension applying method.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a V-ribbed belt B according to an embodiment of the present invention. The V-ribbed belt B has a belt main body portion formed by an adhesive rubber layer 1, and a back canvas 2 is affixed to an upper surface of the adhesive rubber layer 1 which is a back side of the belt. Further, a rib rubber layer 3 is formed on the lower surface side of the adhesive rubber layer 1, and three ribs 3 are provided on the bottom surface side of the rib rubber layer 3 so as to extend in the belt length direction.
a, 3a, 3a are formed at a predetermined pitch in the belt width direction. At the center of the adhesive rubber layer 1 in the belt thickness direction, there is provided a core wire 4 extending substantially in the belt length direction and spirally provided at a predetermined pitch in the belt width direction.

The adhesive rubber layer 1 is made of chloroprene rubber (C
R), ethylene propylene diene monomer (EPD)
M), a rubber composition such as hydrogenated nitrile rubber (H-NBR), etc., which serves as a rubber layer that forms the belt body and holds the core wire 4.

The back canvas 2 is attached to the back of the belt by applying a bonding process using a rubber paste obtained by dissolving rubber in a solvent to a woven fabric of nylon, cotton, or the like, and is attached to the back of the belt so that the back of the belt abuts a flat pulley. When it is wound, it plays a part in power transmission.

The rib rubber layer 3 is made of a rubber composition such as chloroprene rubber (CR), ethylene propylene diene monomer (EPDM), or hydrogenated nitrile rubber (H-NBR), like the adhesive rubber layer, and has an elastic modulus in the belt width direction. , Short fibers 3b, 3b,..., Such as nylon fibers and aramid fibers, oriented in the belt width direction are mixed in order to improve the performance. Then, when the belt is wound around the pulley, the rib rubber layer 3 comes into contact with the pulley and becomes a main body of power transmission.

The core 4 is made of PEN fiber or PVA.
Consists of fibers. The total denier number of the core wire 4 is 5000 to 80
00, and the configuration is not particularly limited. For example, a 1000 de / 2 × 3 configuration twisted yarn or the like is used. The structure of the core wire 4 is not particularly limited, such as a twisted yarn or a braid. In addition, the core wire 4 has a belt of 1% to 3%.
% When stretched to 180% per rib
It extends substantially in the belt length direction so as to be 0 to 4500 kgf and is helically embedded at a predetermined pitch in the belt width direction. Further, the apparent belt elastic modulus when the belt is stretched by 3% is set to be 2000 to 5000 kgf per rib. In addition, the core wire 4 is resorcinol-formalin-latex (RF
L) An adhesive treatment with a liquid or the like is performed, and a stretching heat fixing treatment is performed.

As described above, in the V-ribbed belt B, the core 4
Is made of PVA fiber or PEN fiber, and these fibers have higher elasticity than PET fiber, so that the transmission capacity of the belt can be improved. In addition, since these fibers also have heat shrinkage properties like PET fibers, even if the tension applied to the belt decreases due to wear of the ribs 3a, 3a, 3a, the fibers thermally shrink and the tension applied to the belt decreases. It recovers and does not require the use of an auto-tensioner as in the case of using an aramid fiber core. That is, the V-ribbed belt B can improve the transmission capacity by the fixed tension applying method.

In the V-ribbed belt B constructed as described above, the length of the core wire 4 extracted from the belt when the core wire 4 is held in a dryer at 150 ° C. for 30 minutes is used. Dry heat shrinkage expressed as a percentage of shrinkage length of 0.3 to
1.0%.

Needless to say, the V-ribbed belt B
Exhibits high transmission performance even in a layout using an auto tensioner.

[0026]

EXAMPLES V-ribbed belts according to the following Examples 1 to 4 were prepared for various test evaluations, and the test evaluations of Tests 1 to 3 were performed. (Preparation of Test Evaluation Belt) Example 1 A cylindrical mold having a circumference of 1000 mm is covered with a nylon canvas which has been subjected to an adhesive treatment with rubber glue, and a first adhesive rubber sheet made of a chloroprene rubber composition is wound thereon. Was. Then, the adhesive and stretch heat-set 1
The core of PVA fiber of 000 de / 2 × 3 configuration is 1.15
It was wound spirally at a pitch of mm. Further, a second adhesive rubber sheet made of the same material as the first adhesive rubber sheet was wound from above the core wire, and a rib rubber sheet made of a chloroprene rubber composition containing short fibers was wound thereon.

The cylindrical mold in which the above-mentioned materials were set was put into a vulcanizing can, and a predetermined temperature and a predetermined pressure were applied for a predetermined time to obtain a rubber cylinder.

Next, the outer peripheral surface of the rubber cylinder is ground with a grindstone.
A plurality of ridges extending in the circumferential direction and formed at a predetermined pitch in the cylindrical axis direction were provided.

Then, a V-ribbed belt according to Example 1 was obtained by cutting the rubber cylinder into a ring having a width corresponding to the three ridges. The obtained belt has a total belt thickness of 4.3 mm,
The rib height was 2.0 mm. This belt is called 3pk1000, which means that the number of ribs is 3 and the belt circumference is 1000 mm.

Example 2 A V-ribbed belt manufactured in the same manner as in Example 1 except that the core material was PEN and having the same configuration was used as Example 2.

Example 3 A V-ribbed belt manufactured in the same manner as in Example 1 and having the same configuration as in Example 1 except that the core material was PET was used as Example 3.

Example 4 A core wire is made of aramid fiber (manufactured by Kevlar Dupont) with a twist of 1500 de / 1 × 3 and a pitch of 0.1 mm.
Except for setting the total belt thickness to 4.0 mm, the V was manufactured in the same manner as in Example 1 and had the same configuration.
The ribbed belt was Example 4.

Table 3 summarizes the V-ribbed belts of Examples 1 to 4.

[0034]

[Table 1] (Test 1) <Test Evaluation Method> Each of the V-ribbed belts according to Examples 1 to 4 was cut to form a strip-shaped test piece having a length of 310 mm, and marked lines were drawn at intervals of 100 mm. Was. Then, both ends of the test piece were gripped with a chuck, and a tensile test was performed at a tensile speed of 50 mm / min. Then, the belt elasticity per rib was determined from the proportional relationship between the tension and the elongation obtained in the region where the elongation of the belt was 1 to 3%. Further, the tension when the elongation rate of the belt is 3% is read, the value is divided by 3 which is the number of ribs, and the value is converted into one rib, and this is converted to 0.03 (3%) which is the distortion amount. Divided by the apparent belt elastic modulus. The measurement was performed at room temperature (25 ° C.). <Test Evaluation Results> The evaluation results are shown in FIG. 2, and the values of the belt elastic modulus obtained from FIG. As shown in the table, in the V-ribbed belt according to Example 3 to which the PET core wire was applied, the belt elastic modulus (hereinafter, referred to as “belt elastic modulus”) at a belt elongation of 1 to 3% per one rib. 1
The apparent belt elastic modulus at 633 kgf and a belt elongation of 3% (hereinafter referred to as “apparent belt elastic modulus”) was 1867 kgf per rib. In contrast, P
The V-ribbed belt according to Example 1 to which the VA core wire is applied has a belt elastic modulus of 3816 kgf per rib, the apparent belt elasticity is 4100 kgf per rib, and the V-ribbed belt according to Example 2 to which the PEN core wire is applied. Showed that the belt elastic modulus was 1917 kgf per rib and the apparent belt elastic modulus was 2611 kgf per rib, which was larger than that of Example 3 and a large belt elastic modulus and an apparent belt elastic modulus. Therefore, it can be said that the V-ribbed belt according to Example 1 or Example 2 has higher transmission capacity than the V-ribbed belt according to Example 3. On the other hand, in the V-ribbed belt according to Example 4 to which the aramid fiber cord was applied, the belt elastic modulus was 7816 k per rib.
gf, apparent belt elastic modulus is 6778k per rib
Although the value was extremely high as gf, at such a level, the belt was extremely worn.

[0035]

[Table 2] (Test 2) <Test Evaluation Method> Each of the V-ribbed belts according to Examples 1 to 4 was cut into a belt shape, sliced in the belt thickness direction, and processed into a strip shape including only the adhesive rubber in which the cord was embedded. Then, one core wire is extracted from the strip-shaped material, one end thereof is fixed, and the other end has a weight of 1/20 of the total denier number constituting the core wire (the number of core wires is 100).
With a 0de / 2 × 3 configuration, the total denier is 6000d
e and a weight of 300 g). Next, the interval is 500 mm (L
Two marked lines as 1) were inserted. Subsequently, the weight was removed, and as shown in FIG. 3, the core wire was bent and placed in a dryer at 150 ° C. for 30 minutes. Thereafter, the core wire taken out of the dryer was cooled at room temperature for 10 minutes, and a weight (L2) between the marked lines was measured by suspending the same weight as above. And (L
1−L2) / L1 × 100 was calculated and taken as the dry heat shrinkage. <Test Evaluation Results> The evaluation results are shown in the middle column of Table 2. As shown in the table, the PET core of Example 3 has a large dry heat shrinkage of 2.1%. In contrast, the PVA core of Example 1 is 0.4%, and the PEN core of Example 2 is 0.8%, which is smaller than that of the PET core. That is, PVA fiber and PE
Although N fibers also have heat shrinkage properties, they do not exhibit as much shrinkage as PET fibers. Therefore, it can be said that the V-ribbed belt according to Example 1 or 2 can recover by lowering the tension applied to the belt by self-adjustment, and is superior in dimensional stability to the V-ribbed belt according to Example 3. In addition,
The V-ribbed belt according to Example 4 to which the aramid fiber core is applied has a dry heat shrinkage of 0% and is excellent in dimensional stability.
However, when the tension applied to the belt decreases, it cannot be adjusted by itself, and it is necessary to apply an auto tensioner. (Test 3) <Test evaluation method> Each of the V-ribbed belts 41 according to Examples 1 to 3 was mounted on a running tester having a layout shown in FIG.
It was wound around a 00 mm driving pulley 42 and a driven pulley 43 having a diameter of 100 mm. Next, a constant load of 45 kgf was applied to the driven pulley 43 in a direction opposite to that of the drive pulley 42 to apply tension to the belt. At first, the driven pulley 43 is set to the no-load state and the driving pulley 42 is set to 3500.
The rotation was started at rpm, and the load on the driven pulley 43 was gradually increased. At this time, the belt slips on the pulleys 42 and 43 as the load is increased. The load when the slip became 2% was converted into transmission horsepower to obtain data. A similar test was performed with a constant load of 60 kgf. <Test Evaluation Results> The evaluation results are shown in the lower column of Table 2. As shown in the table, even when a load of 45 kgf or 60 kgf was applied, the PVA core wire or the PVA core wire was lower than the V-ribbed belt according to Example 3 to which the PET core wire was applied.
It can be seen that the V-ribbed belt according to Example 1 or Example 2 to which the EN core is applied has higher transmission horsepower, that is, higher transmission capacity.

[Brief description of the drawings]

FIG. 1 shows a V-ribbed belt B according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a belt elongation and a belt tensile force per three ribs.

FIG. 3 is a perspective view of a small skein of the core wire.

FIG. 4 is a diagram showing a layout of a running test machine for a belt transmission performance test.

[Explanation of symbols]

 Reference Signs List 1 adhesive rubber layer 2 back canvas 3 rib rubber layer 3a rib 3b short fiber 4 core wire 41 V-ribbed belt 42 drive pulley 43 driven pulley

Claims (3)

[Claims] 1. A V-ribbed belt spirally provided at a predetermined pitch in a belt width direction such that a cord formed of polyvinyl alcohol fiber or polyethylene-2,6-naphthalate fiber extends substantially in the belt length direction. The core wire is provided so that the total denier is 5,000 to 8,000, and the belt elastic modulus when extending the belt from 1% to 3% is 1800 to 4500 kgf per rib. Characteristic V-ribbed belt. 2. A V-ribbed belt spirally provided at a predetermined pitch in a belt width direction such that a cord formed of polyvinyl alcohol fiber or polyethylene-2,6-naphthalate fiber extends substantially in the belt length direction. The core wire is provided so that the total denier is 5,000 to 8,000, and the apparent belt elastic modulus when the belt is stretched by 3% is 2,000 to 5,000 kgf per rib. V-ribbed belt. 3. A V-ribbed belt spirally provided at a predetermined pitch in a belt width direction such that a cord formed of polyvinyl alcohol fiber or polyethylene-2,6-naphthalate fiber extends substantially in the belt length direction. The length of the core wire extracted from the belt is 1
A V-ribbed belt having a dry heat shrinkage of 0.3 to 1.0%, expressed as a percentage of the shrinkage length of the cord when held in a dryer at 50 ° C. for 30 minutes.