JP3464868B2 - Belt cords and transmission belts - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt core wire and a transmission belt, and more particularly to measures for reducing both dimensional changes of the belt itself and elongation during belt running.

[0002]

2. Description of the Related Art For example, a V-ribbed belt has become popular in place of a V-belt in a transmission belt used for driving an auxiliary machine such as an air conditioner or an alternator of an automobile by a rotational driving force of an engine. This V-ribbed belt has, as its basic configuration, an adhesive rubber layer and a rib rubber layer integrally laminated on the bottom surface side of the adhesive rubber layer, and the bottom surface side of the rib rubber layer is respectively in the belt length direction. A plurality of ribs provided so as to extend at a predetermined pitch are formed in the belt width direction.
A core wire is embedded in the adhesive rubber layer in a spiral shape so as to extend substantially in the belt length direction and have a predetermined pitch interval in the belt width direction. As the above-mentioned core wire, for example, as described in JP-B-55-50578, a polyester fiber having an automatic tension function (hereinafter, referred to as
PET) is commonly used.

By the way, in recent years, in a drive device for an automobile accessory, a multi-axis drive transmission called a serpentine drive has attracted attention for the purpose of reducing the number of belts and reducing the installation space of the accessory.
This serpentine drive is configured to drive a large number of auxiliary machines via one belt, and as shown in FIG. 2, each pulley 11 connected to each auxiliary machine is used.
~ 16 are arranged on the same plane, and the pulleys 1
While running one belt B wound in a serpentine shape (meandering shape) between 1 to 16, the tension of the belt B is adjusted by an auto tensioner (17 in the figure is a belt pressing pulley of the auto tensioner). ) Is a system that is always controlled. This system is 19
With the advent of the V-ribbed belt in the first half of the 1970s, its development, including research on the auto tensioner, was started, and in addition to improving the maintainability and reliability of the belt, the reliability of auxiliary equipment Due to this increase, its use as an accessory drive system is being considered.

As a belt suitable for such a serpentine drive, the dimensional change of the belt itself is small, the elongation of the belt during running is small, that is, the dimensional change of the belt is small under any circumstances. is important. That is, the smaller the belt dimensional change, the easier it is to design the belt tension margin by the tensioner, and the smaller the operating space of the tensioner, the smaller the space of the serpentine drive in the engine room. By adopting such a serpentine drive, it is possible to save space in the engine room itself and also to reduce the overall weight.

[0005]

However, it is difficult to say that the dimensional change of the conventional V-ribbed belt is sufficiently small, and thus it is not sufficient to make the engine room compact by adopting the serpentine drive. Is.

That is, when the dimensional change of the belt is large,
The working space of the tensioner increases accordingly,
The space for the serpentine drive occupying the engine room is correspondingly increased, and as a result, the compactness of the engine room is hindered.

The present invention has been made in view of the above points, and its main object is to clarify the characteristics of the core wire used for a transmission belt such as a V-ribbed belt, which influences the dimensional change of the belt. By appropriately setting the characteristic values of the belt, it is possible to suppress both the dimensional change of the belt itself over time and the belt elongation after running, and to impart excellent dimensional stability to the belt. Especially.

With respect to the V-ribbed belt used in the serpentine drive, the working space of the tensioner can be made small so that the space of the serpentine drive occupying the engine room can be made smaller by that much. The purpose is to make a large contribution to the compactness of the engine room by adoption.

[0009]

In order to achieve the above-mentioned object, in the present invention, the dry heat shrinkage ratio and the dry heat shrinkage ratio of the core wire in the twisted state, that is, in the state of the raw cord are set. Based on the knowledge that the three characteristic values of thermal shrinkage stress and initial tensile resistance (initial modulus) greatly influence the dimensional stability of the power transmission belt, dimensional changes over time can be achieved by setting these characteristic values appropriately. Also, the elongation when the belt is running can be reduced.

Specifically, the invention of claim 1 is premised on a belt core wire which is twisted. In the twisted state, the dry heat shrinkage ratio at 150 ° C. is 1.0% or less and the dry heat shrinkage stress is 0.2 g / de or less. It is assumed that the resistance is 150 to 500 g / de.

According to the invention of claim 2, the above-mentioned claim 1
In the power transmission belt using the belt cord according to the invention, the cord is embedded in the belt body.

After being twisted, the above-mentioned core wire is actually subjected to, for example, an isocyanate-based or epoxy-based pretreatment, and then an adhesive such as an RFL liquid is applied, and then stretched at a high temperature. By being subjected to heat setting treatment, it becomes a belt tension member. Then, in the raw code state before performing the series of processes described above, each of the above values is taken. In addition, each of the above characteristic values is JIS L-
1017 (1983). Specifically, the dry heat shrinkage ratio is obtained by leaving it at an ambient temperature of 150 ° C. for, for example, 30 minutes. Further, the shrinkage stress during dry heat is obtained by leaving it at an ambient temperature of 150 ° C. for, for example, 3 minutes.

In the above structure, the dry heat shrinkage factor at 150 ° C. and the dry heat shrinkage stress of the core wire are 1.0 respectively.
% And 0.2 g / de or less, the dimensional change of the belt itself with time becomes smaller accordingly. When the dry heat shrinkage ratio and the dry heat shrinkage stress exceed 1.0% and 0.2 g / de, respectively, the dimensional change with time becomes large, and a transmission belt having good dimensional stability cannot be obtained. , The belt quality is significantly reduced.

On the other hand, the initial tensile resistance of the core wire is 150.
~ 500 g / de, for example, in the case of a conventional V-ribbed belt having a core made of PET, the initial tensile resistance is 10
Since it is higher than about 0 g / de, the elongation of the belt due to running can be suppressed small. If the initial tensile resistance is less than 150 g / de, the elongation during running from the time when the belt is mounted is adversely affected, and a transmission belt having good dimensional stability cannot be obtained. On the other hand, when the initial tensile resistance exceeds 500 g / de, as in the case of the conventional V-ribbed belt in which the core wire is made of aramid fiber,
There is a possibility that vibration noise may be generated when the belt is running, and therefore it is difficult to say that the transmission belt is excellent in terms of quality.

According to the invention of claim 3, in the invention of claim 2, the transmission belt is a V-ribbed belt used for a serpentine drive. In the above configuration,
In the V-ribbed belt, both the dimensional change with time and the belt elongation after running are suppressed by the core wire. As a result, in the serpentine drive in which the V-ribbed belt is used, the operating space of the autotensioner can be small, and the space of the serpentine drive in the engine room can be reduced accordingly.
Therefore, it becomes possible to contribute to the compactness of the engine room by adopting the serpentine drive.

In the invention of claim 4, the above-mentioned claim 2 or 3
In the invention, the core wire is made of polyvinyl alcohol fiber (PVA). Further, in the invention of claim 5, in each of the inventions, the core wire is polyethylene-2,
It shall consist of 6-naphthalate fibers (PEN).
In the above configuration, the core wire is made of either PVA or PEN, so that the dimensional stabilizing action by setting the respective characteristic values in the invention of claim 1 is properly and efficiently performed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a layout of a serpentine drive using a V-ribbed belt B as a transmission belt according to the embodiment of the present invention. In the figure, 11 is a pulley that is connected to the crankshaft of the engine so as to rotate integrally therewith, and around this pulley 11, a pulley 12 of an alternator, a pulley 13 of a power steering pump, an idler pulley 14, and a water pump. The pulley 15 and the pulley 16 for the air conditioner are arranged on the same plane. And those pulleys 1
One V-ribbed belt B is wound around the belts 1 to 16 so that the belt can travel, while an automatic tensioner for keeping the tension of the belt B constant is arranged.

The above-mentioned automatic tensioner has a pulley 1 for pressing a belt at the end of an arm pivotally supported at its base end so as to be rotatable about an axis orthogonal to the plane in which the pulleys 11 to 16 are arranged.
7, the pulley 17 is always urged to rotate in the belt pressing direction P by a spring, and the rotation in the direction Q opposite to the belt pressing direction P is damped to reduce the belt tension. At times, a predetermined tension can be quickly applied to the belt B, and the flapping of the belt B can be suppressed when the belt tension rapidly increases.

The following six are required for the above-mentioned auto tensioner. Maintain stable belt tension (maintain stable spring characteristics).

Maintain stable damping characteristics.

Miniaturization.

Low price.

Low noise performance.

Proper alignment.

Regarding the miniaturization of the above, FIG.
As shown in comparison with (a) and (b), if the belt wrap angle is the same and the belt tension F (axial load) is the same, the arm shown in FIG. The shorter the length, the smaller the twisting torque is (F × L
Since << F × l), it is possible to reduce the size and weight.

The V-ribbed belt B includes, as shown in an enlarged view in FIG. 1, an adhesive rubber layer 1 and a rib rubber layer 3 integrally laminated on the bottom surface side (the lower surface side in the figure) of the adhesive rubber layer 1. Is equipped with. These rubber layers 1 and 3 are NR, CR, H
-NBR, A-CSM, and other known rubbers are used.
The core wires 2 are embedded in the adhesive rubber layer 1 in a spiral shape so as to extend substantially in the belt length direction and line up at a predetermined pitch in the belt width direction. On the other hand, on the bottom surface side of the rib rubber layer 3, three ribs 4, 4, ... That are provided so as to extend in the belt length direction are formed so as to be arranged at a predetermined pitch interval in the belt width direction. ing. The rib rubber layer 3 includes natural fiber, polyester,
Short fibers 5, 5, ... Of polyamide or the like are mixed in a state of being oriented in the belt width direction.
The hardness as a whole is higher than that of the adhesive rubber layer 1. In addition, the back side of the adhesive rubber layer 1 (the top side of the figure)
Bias canvas 6 woven by both warp and weft threads made of polyester, polyamide, aramid, cotton, etc. is attached to the. Here, the above-mentioned adhesive rubber layer 1 and rib rubber layer 3
Constitute the belt main body in the present invention.

In this embodiment, the core wire 2 is
Is PVA (polyvinyl alcohol fiber) and PEN
(Polyethylene-2,6-naphthalate fiber). At that time, the core wire 2 is
The dry heat shrinkage ratio at 150 ° C. and the dry heat shrinkage stress are respectively 1. when the raw cord is not yet subjected to the dip treatment as described in the section “Means for solving the problems”. 0% or less and 0.2 g / de or less, while the initial modulus (initial tensile resistance) is 15
It is set to 0 to 500 g / de.

Therefore, according to this embodiment, in the core wire 2 of the V-ribbed belt B, the dry heat shrinkage rate and the dry heat shrinkage stress at 150 ° C. are set to 1.0% or less and 0.2 g / de or less, respectively. I tried to keep it low,
The dimensional change of the belt B itself during storage can be reduced, and the initial modulus is 150 to 500 g / de.
Since it has been made higher, the size variation when finishing the belt is small and the belt elongation due to running can also be made small, so when used in a serpentine drive, the working space of the tensioner in that serpentine drive is greatly reduced. It is possible. Therefore, the space occupied by the serpentine drive in the engine room can be reduced, and the use of the serpentine drive can greatly contribute to the compactness of the engine room and the overall weight reduction.

In the above embodiment, the core wire 2 is made of PVA.
Alternatively, it is not limited thereto.

In the above embodiment, the transmission belt is V
Although a ribbed belt has been described, the transmission belt may be any belt that is required to have dimensional stability as excellent as that in the above case.
It is not limited to the ribbed belt.

-Experimental Example- Next, an experiment conducted for demonstrating the effect of the core wire will be described. First, as Invention Examples 1 to 3, both PVA (the product numbers are different from each other) are used for the core wires in Invention Examples 1 and 2.
In Invention Example 3, a V-ribbed belt having a belt outer peripheral length of 2260 mm was manufactured by using PEN.

In the invention example 1, the dry heat shrinkage ratio and the dry heat shrinkage stress of the raw cord are set to 0.3% and 0.07 g / de, respectively, while the initial modulus is set to 34.
It was 0.7 g / de. The dry heat shrinkage rate and the dry heat shrinkage stress when dip-treated were 0.4% and 0.29 g / de, respectively, while the initial modulus was 37.
It was 9.2 g / de.

In Invention Example 2, the dry heat shrinkage ratio and the dry heat shrinkage stress of the raw cord are 0.5% and 0.15, respectively.
g / de, while the initial modulus is 291.8 g /
It was de. The dry heat shrinkage rate and the dry heat shrinkage stress when dipping this are 0.4% and 0.27 g, respectively.
/ De, and the initial modulus is 377.8 g / d
It was e.

In Inventive Example 3, the dry heat shrinkage ratio and the dry heat shrinkage stress of the raw cord are 0.9% and 0.14, respectively.
g / de, the initial modulus is 158.0 g /
It was de. The dry heat shrinkage rate and the dry heat shrinkage stress when dipping this are 1.0% and 0.30 g, respectively.
/ De, while the initial modulus is 190.2 g / d
It was e. It should be noted that the yarn configurations of Invention Examples 1 to 3 are both 1
000 de / 2 × 3, and the numbers of upper twists and lower twists are substantially the same. Also, the processing temperature during dip processing,
The processing time and tension are the same conditions.

With respect to the invention examples 1 to 3 above, the dimensional change with time of the belt [%] and the belt elongation after running [%] were measured. Specifically, the above-mentioned dimensional change of the belt over time is equivalent to storage for a predetermined time (1097 to 2980 hours [7 to 8 LN hours]) under a constant ambient temperature (40 ° C. in this example). It was examined by the change in the outer peripheral length of the belt during the test. On the other hand, the belt elongation after running was examined by the elongation when the belt was run for a predetermined time in the serpentine drive shown in FIG.

For comparison, as shown in Table 1 below, each is made of PET and has a dry heat shrinkage factor and a dry heat shrinkage stress of 1.0% when the raw cord is used.
And a core wire having an initial modulus of less than 150 g / de while exceeding 0.2 g / de, Comparative Examples 1 to 1
No. 4 V-ribbed belts were produced, and the same items as in the above case were also measured for these, and the elapsed time + running dimension change rate was calculated. Incidentally, among these Comparative Examples 1 to 4, Comparative Example 1, Comparative Example 3 and Comparative Example 4 have the same product number, and only Comparative Example 2 has a different product number. The composition and the number of twists of the yarn are the same as those of the invention examples 1 to 1.
It is the same as the case of 3. However, the dipping process is slightly different except that the comparative example 2 is the same as the above-mentioned invention examples 1 to 3. That is, in Comparative Examples 1 and 3, the tension is a little higher, in Comparative Examples 1 and 4, the processing time is about half, and in Comparative Example 1, the processing temperature is slightly lower.

The above results are also shown in Table 1. Further, the dimensional change of the belt over time is also shown in FIG.

[0038]

[Table 1]

Considering the results of the above-mentioned elapsed time + running dimensional change rate, as can be seen from Table 1 above, invention examples 1 to 3 were obtained.
In both Comparative Examples 1 to 4, the percentages were 0.6%, while in Comparative Examples 1 to 4, even small ones (Comparative Examples 1 and 2) were 0.7%.
It is a table, and reaches 1.11% in Comparative Example 4. This is because, for example, as can be seen from Comparative Examples 1 and 3, even when the belt elongation after running is smaller than in the case of Invention Examples 1 to 3, the value of the dimensional change with time of the belt is larger than that.

Further, comparing invention examples 2 and 3, it is understood that in case of invention example 3, good dimensional stability can be obtained even if the initial modulus is slightly over 150 g / de. In this regard, the present inventors have set the lower limit of the initial modulus to P in the case of PVA (Invention Examples 1 and 2).
Higher than in the case of EN (Invention Example 3) (for example, about 30)
I think it is necessary to set it to about 0 g / de).

On the other hand, considering Comparative Examples 1 to 4,
For example, as in Comparative Examples 1 and 3, even if the belt elongation after running can be reduced by increasing the tension during the dipping process, the dimensional change of the belt over time is deteriorated. It can be seen that it is difficult to greatly improve the dimensional stability as a whole apart from the properties of the raw cord (dry heat shrinkage rate, dry heat shrinkage stress and initial modulus) only by changing

In other words, if the respective characteristic values of the dry heat shrinkage, the dry heat shrinkage stress and the initial modulus are suppressed,
Regardless of some difference in conditions such as dipping treatment, it is possible to suppress both the dimensional change of the belt over time and the belt elongation after running, and it is possible to give the belt excellent overall dimensional stability. I understand.

[0043]

As described above, according to the first and second aspects of the present invention, the dry heat shrinkage factor and the dry heat shrinkage stress at 150 ° C. of the raw cord for the transmission belt are measured. The initial tensile resistance is 150 to 500 g, while it is suppressed to 1.0% or less and 0.2 g / de or less, respectively.
Since it is set to a high value such as / de, it is possible to reduce variations in the dimensions of the finished belt and dimensional changes of the belt over time during storage, and it is also possible to reduce the belt elongation during running. Stability can be imparted to the transmission belt.

According to the invention of claim 3, since the transmission belt is a V-ribbed belt, in a serpentine drive in which the V-ribbed belt is used, the working space of the tensioner for keeping the belt tension constant during running is small. The space for the serpentine drive in the engine room can be reduced accordingly. Therefore, it is possible to contribute to downsizing and weight saving of the engine room by adopting the serpentine drive.

In the invention of claim 4, the core wire is made of PVA.
(Polyvinyl alcohol fiber), and in the invention of claim 5, PEN (polyethylene-2,6-naphthalate fiber) is used. Therefore, according to any one of these inventions, The effect can be properly obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a basic structure of a V-ribbed belt according to an embodiment of the present invention, cut along a plane orthogonal to a belt length direction.

FIG. 2 is a schematic diagram showing a layout of a serpentine drive.

FIG. 3 is a schematic diagram for explaining the magnitude of torsional torque depending on the arm length in the auto tensioner.

FIG. 4 is a characteristic diagram showing changes over time in the outer circumferential length of the belt under storage at a constant ambient temperature.

[Explanation of symbols]

1 Adhesive rubber layer (belt body) 2 cores 3 Rib rubber layer (belt body) 4 ribs BV Ribbed Belt (Transmission Belt)

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-5-312237 (JP, A) JP-A-6-207338 (JP, A) JP-A-6-240531 (JP, A) JP-A-8- 60449 (JP, A) JP-A-9-236156 (JP, A) Actual development Sho 61-202472 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) D02G 3/00-3 / 02 F16G 5/20

Claims (5)

(57) [Claims] 1. A twisted belt core wire, which has a dry heat shrinkage ratio of 1.0% or less at 150 ° C. and a dry heat shrinkage stress in the twisted state. Is 0.2 g / de or less, while the initial tensile resistance is 150 to 500 g / de. 2. A transmission belt, wherein the belt cord according to claim 1 is embedded in a belt body. 3. The transmission belt according to claim 2, which is a V-ribbed belt. 4. The transmission belt according to claim 2, wherein the core wire is made of polyvinyl alcohol fiber. 5. The power transmission belt according to claim 2, wherein the core wire is made of polyethylene-2,6-naphthalate fiber.