JPS63270944A - Toothed belt - Google Patents

Abstract

PURPOSE:To aim at improvement in durability under the severe condition by constituting the surface covered canvas of a tooth profile part from a woven forming elastic yarn into wadding and setting double-covering yarn down to warp, and setting up the warp in a belt longitudinal direction. CONSTITUTION:Surface covered canvas being installed on the surface of a tooth profile part is made up in the following process that a polyurethane fabric large in elasticity, polybutyleneterephtalate, rubber yarn or the like are formed into wadding, and double covering yarn composed of winding an aromatic polyamide fiber excellent in heat resistance and abrasion resistance in the circumference in the same direction or the different direction doubly with each other is set down to warp, and twisting or monofilament yarn to weft, respectively. In addition, the warp is arranged so as to go along a belt longitudinal direction. Thus, even in case of a press-in process in toothed belt manufacture, it is manufacturable without any strain and, what is more, tooth profile part shearing strength, heat resistance and crackproofing are all improved, thus durability under the severe condition is improvable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toothed belt, and more particularly to a toothed belt used under severe conditions such as high loads and high temperatures.

[Conventional technology]

Toothed belts are widely used because they are capable of synchronous transmission, are quieter than gears, and require less space for installation, and are also widely used as belts for driving automobile camshafts. be.

However, in addition to high-load conditions, the belt for driving the camshaft of an automobile as described above is exposed to high-temperature conditions that reach 100 to 130 degrees Celsius due to the heat of the engine, and due to these harsh conditions. There was a problem that the service life was shortened.

One of the ways in which the service life of toothed belts is shortened is that the teeth of the belt are damaged, which often leads to belt breakage. Cracks in the surface canvas layer ■ PLD due to abrasion and settling of the canvas between the peaks and valleys
It is thought that the value changes, causing poor engagement and stress concentration at the root of the tooth.

Therefore, in order to increase the durability of the toothed heald under severe conditions, an important factor is to improve the wear resistance, bending resistance, etc. of the canvas layer covering the surface of the teeth.

Therefore, in the past, the strength of the surface canvas layer itself was improved by increasing the thickness of the surface canvas (1983).
3-98275), heat-resistant synthetic fibers such as highly blended polyester fibers or aromatic polyamide fibers to improve heat resistance, and woven fabrics made of mixed threads of these fibers and nylon (Japanese Patent Laid-Open No. 55-47034). ) have been proposed and implemented.

[Problems with conventional technology]

However, with the former method of increasing the thickness of the woven fabric, the PLO changes immediately when the canvas is worn during traveling, so although the initial strength is improved, the durability under harsh conditions is not improved. Furthermore, the latter method using heat-resistant fibers has a problem in that the woven fabric has poor elasticity, making it impossible to use the regular forming method, which is a known toothed belt forming method.

In addition, in order to make the canvas thicker and more stretchable, woolly processing of polyamide fibers, woven or knitted fabrics made of covering yarn, or woven fabrics of low-oriented polyester synthetic fibers with an elongation of 80% or more are used. However, they generally have poor abrasion resistance and heat resistance, and are not sufficient to increase the durability of toothed belts under severe usage conditions.

However, in order to solve this problem, the woven fabric is composed of thick warps with a large twist coefficient and thin wefts made of twisted yarns, and the warp of the woven fabric is Although it has been proposed to increase the elasticity in the direction (Japanese Patent Publication No. 62-7414), it is said that this is still not sufficient to achieve the elongation of the woven fabric required for the regular forming method using toothed belts. There are drawbacks.

[Problems solved by the invention]

In view of the above-mentioned problems, the present invention has been developed to provide a toothed belt that has excellent heat resistance and abrasion resistance, has sufficient strength even under severe usage conditions, and is covered with a surface coating layer that has appropriate elasticity. This was done for the purpose of obtaining.

[Technology to solve problems]

That is, the toothed belt of the present invention has tooth profiles at a constant pitch on the inner surface, a tensile strength member is embedded along the pitch line, and a rubber toothed belt has a covering canvas layer on the surface of the tooth part.
The surface-covered canvas provided on the surface of the toothed part has a synthetic fiber elastic yarn as the core yarn, and a double covering yarn made of aromatic polyamide fibers wound in double layers in the same or different directions around the core yarn as the warp yarn. The canvas is woven with twisted yarn or monofilament as the weft, and is characterized in that the warp is arranged along the length direction of the belt.

[Effect]

In this invention, the tooth surface covering woven fabric does not use a crimped elastic canvas as in the past, but uses highly elastic polyurethane fiber, polybutylene terephthalate, rubber thread, etc. as a core thread, and uses heat-resistant Since the woven fabric is woven with a covering yarn made of aromatic polyamide fibers wound with excellent abrasion resistance as the warp and twisted yarn or monofilament yarn as the weft, the woven fabric has sufficient elasticity and at the same time is suitable for covering. The ring thread surface provides wear resistance and heat resistance.

This covering yarn is made by first winding twisted aromatic polyamide fibers in the S or Z direction around a stretchable core yarn, and then wrapping the same type of twisted yarn on top of it in the same direction or in a different direction. Because it is double-covered, the woven fabric is easily stretched during full-size forming during belt manufacturing. Furthermore, when stretched, the winding yarns of the covering yarn are pulled together, creating a twisting effect similar to that of twisted yarn.

For this reason, it is sufficient that the twist coefficient of the aromatic polyamide fiber yarn wound around the core yarn is 50 or more.

Further, in connection with the above-mentioned twisting effect, it is preferable that the amount of winding of the aromatic polyamide fibers around the core yarn is 20 times/10 cm or more for both the inner and outer layers.

Furthermore, when performing double covering, the I! of the bottom winding thread and the top winding thread! If the amount of twisting is the same, the alignment of the 1@twisted yarns after stretching will be poor, and there is a risk that the twisting effect will not be fully exerted.

Therefore, depending on the degree of elongation of the woven fabric, it is desirable that the winding amount of the upper winding yarn is 100 to 70% of the winding amount of the lower winding yarn.

Furthermore, there is no particular restriction on the winding direction of the top and bottom threads, but the winding directions can be reversed for the top and bottom, that is, if the bottom thread is Z-winding, the top winding is S16, or vice versa. desirable. By using such a winding direction, distortion of the woven fabric when elongation is applied to the woven fabric is eliminated, which is convenient.

Further, the weft of the woven fabric of the present invention is not particularly limited, but nylon, polyester, or aromatic polyamide fibers can be used, and the texture can be plain weave, twill weave, satin weave, etc.

〔Example〕

Next, this invention will be explained in detail.

180 D polyurethane fiber is used as the core thread, and 13
0D, Conex, aromatic polyamide fiber yarn with twist coefficient = 570 is wound 1 to 100 times between 10 cm of core yarn, and then the same aromatic polyamide fiber yarn is wound 1 to 10 times on top of this.
0 times, winding in the same direction and in different directions, double winding is a structure in which the governing yarn is used as the warp, and the monofilament of aromatic polyamide fiber is used as the weft to form a woven fabric, so that the warp is along the length direction of the belt. A toothed belt having a tooth surface coating was molded by a conventional press-fitting method, and the circumference was 89.
Obtain a toothed belt with a diameter of 6 mm and a medium diameter of 10 mm, which has 18 teeth.
The wear rate of the surface canvas layer was measured after running for 100 hours with a load of 4 horsepower on the driven pulley and 6000 rpm+ in a temperature atmosphere of 100°C.

The results were as shown in Table 1.

The wear rate was calculated from the canvas thickness tl before running and the thickness tx after running, which were measured from an electron micrograph of the cross section of the belt, as follows: wear rate=(L-b)/l+xloo (%).

In addition, when the running time until tooth cracking occurred was measured in the same load running test as above, the results shown in Table 2 were obtained.

In addition, the comparative examples listed in Tables 1 and 2 have a warp of 40
This figure shows a toothed belt of the same shape made of a fabric woven using D15 nylon 6.6 wool crimped yarn and molded into a surface-covered canvas.

Table 1 Table 2 A tooth shear force test was also conducted and the results shown in Table 3 were obtained.

Table 3 Next, the correlation between tooth shear force, wear rate, and running life was tested for each warp yarn made of aromatic polyamide fiber wound around an elastic core yarn, with the number of windings per 10 cm of core yarn being 1 to 100 times. As a result, the results shown in Figures 1, 2, and 3 were obtained.

Furthermore, using aromatic polyamide fibers with a twist coefficient (K) of θ ~ 200 to be wound around the elastic core yarn, the number of windings per 10 cn+ was set to 50 times, and a woven fabric was formed in the same manner. An attached belt was molded.

Regarding these, the toothed shear force of the toothed belt, the canvas wear rate,
When testing the tooth crank generation time, Fig. 4~
The results shown in FIG. 6 were obtained.

In addition, the twist coefficient (K) was calculated from K = r (5) (
K: twist coefficient, T: number of twists per 10 cs (D=total cord denier).

〔effect〕

As explained above, this invention is made by arranging a woven fabric with an elastic thread as a core thread and a double covering thread as a warp thread so that the warp threads run along the length direction of the belt. The elasticity along the edges is fully demonstrated, and therefore it can be easily manufactured by the press-fitting method used in manufacturing toothed belts, and the surface of the toothed belt is also made of double covering yarns that make up the warp of the woven fabric. It has various effects such as significantly improved shear strength, heat resistance and crack resistance, and extremely excellent durability under harsh conditions.

[Brief explanation of the drawing]

FIGS. 1 to 6 are graphs showing test results of examples of the present invention. IIEJ γ2I2] Tai7 IIJλ% - γ4 diagram (Relationship between ζWari number and ■cut) Twisted Ko Samurai number (K)

Claims (7)

[Claims] (1) In a rubber toothed belt that has tooth profiles at a constant pitch on the inner surface, a tensile strength member is embedded along the pitch line, and a covering canvas layer on the tooth surface, the surface covering canvas is provided on the surface of the tooth part. However, it is woven with a synthetic fiber elastic yarn as the core yarn, a double covering yarn made by wrapping aromatic polyamide fibers around the core yarn twice in the same or different directions as the warp yarn, and twisted yarn or monofilament as the weft yarn. 1. A toothed belt, characterized in that the canvas is made of canvas, and the warp threads are arranged along the length direction of the belt. (2) The toothed belt according to claim 1, wherein the aromatic polyamide fiber yarn wound around the core yarn is twisted with a twist coefficient of 50 or more. (3) The toothed belt according to claim 1 or 2, wherein the amount of winding of the aromatic polyamide fiber yarn around the core yarn is 20 times/10 cm or more for both the inner and outer layers. (4) The ratio of the amount of lower winding and the amount of upper winding of the aromatic polyamide fiber that is double wound around the core yarn is 100: (100 to 70)
A toothed belt according to claim 1, 2 or 3, comprising: (5) Claims 1, 2, 3, or 4, wherein the aromatic polyamide fibers wound twice around the core thread are wound in opposite directions in the inner and outer layers. toothed belt. (6) Claims 1, 2, 3, 4, or 5, wherein the weft twist or monofilament is made of nylon, polyester, aromatic polyamide fiber, or cotton. Toothed belt. (7) Claims 1, 2, 3, 4, 5, or 6, wherein the surface-covered canvas has a plain weave, twill weave, or satin weave. toothed belt