JPH03265739A - Timing belt - Google Patents

Abstract

PURPOSE:To lengthen the life of a belt by making up tooth canvas out of one-way unwoven fabric, making fiber density at each trough section higher than that at each tooth section, and thereby arranging the intermediate canvas of high tension bias canvas in a space between each tooth canvas of the insides of tooth section and trough sections and a tension member. CONSTITUTION:A tension member 5 is embedded in a spiral shape in the lower section of a belt base band 2, tooth canvas 6 covering each tooth section 3 and each trough section 4 is fitted onto the lower surface of a belt, and intermediate canvas 7 is embedded in a space between the tension member 5 and the tooth canvas 6. The tooth canvas 6 is made up out of one-way unwoven fabric where fiber filaments 6a are arranged in one direction, and each trough section 4 is made higher in fiber density than each tooth section. In the intermediate canvas 7, both each warp 7a and each weft 7b are inclined against the longer direction of the belt, and the canvas is made up out of high tension fabric in a bias shape with high porocity where a specified angle theta is formed by both each warp 7a and each weft 7b. This thereby permits each trough section to be increased in wear resistance, and also permits each tooth section and each tooth root section in particular to be increased in stiffness, so that the occurrence of cracks at each tooth root section is thereby restrained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a belt base belt in which tooth portions and tooth valley portions are alternately arranged in the longitudinal direction of the belt under a belt base belt in which a mandrel is embedded in a spiral shape.
A timing belt in which the tooth portion and the tooth valley portion are covered with a tooth canvas, in particular, a tooth canvas material, an intermediate canvas material, a core material, and an unvulcanized rubber sheet are laminated in order on a molding mold, and in that state. This invention relates to a timing belt that is vulcanized and molded by heating and pressurizing.

(Prior Art) In general, timing belts are suitable for applications that require synchronous rotation, and are used as belts for synchronously transmitting power between the crankshaft and cam of automobile engines, as well as for cameras, computers, and copying machines. It is used in all belt transmission systems that require synchronous transmission, such as precision machinery and general industrial machinery.

In particular, in recent years, automobiles have increasingly been equipped with multi-valve, V-type engines for the purpose of high output, low noise, and low vibration, so the timing belt used for synchronous drive of the cam has been bent more frequently. Due to increased belt speeds, smaller pulleys, etc., they are now being used under extremely harsh conditions.

By the way, timing belts usually have fine coarse cloth attached to the surface of the teeth in order to reinforce the teeth (
For example, Utility Model Application Publication No. 58-181042, Utility Model Application Publication No. 61-
(Refer to Publication No. 543 and Japanese Utility Model Application Publication No. 136649/1983)
. In addition, such a timing belt is made by laminating a fine canvas material, an intermediate canvas material, a core material, and an unvulcanized rubber sheet in order in a molding die, heating and pressurizing it in this state, and vulcanizing it. There are some products that are cut to a width of Conventionally, stretcher-pull yarn has been used for the fine coarse cloth material, which has a very large elongation in the longitudinal direction of the belt, and this elongation is used to make the fine coarse cloth material conform to the tooth shape by press-fitting during vulcanization. It has become.

(Problem to be Solved by the Invention) However, since stretcher-pull yarn is spun and wound once, it is usually heated to give it elasticity, so it has lower strength than the original yarn and has poor bending fatigue resistance. It has the disadvantage that it becomes worse. As a result, shearing force is repeatedly applied to the teeth of the timing belt, and as the teeth are shaken, cracks occur in the fine cloth at the roots of the teeth, and cracks are generated in the grooves of the teeth of the timing belt. In this case, the timing belt reaches the end of its lifespan due to wear of the fine cloth due to repeated slipping with the pulley (the teeth of the belt).

An object of the present invention is to provide a timing belt with improved belt life without using stretchable yarns having low strength.

(Means for Solving the Problems) The present invention provides a method in which tooth portions and tooth valley portions are alternately arranged in the longitudinal direction of the belt below the belt base belt in which the mandrel is embedded in a spiral shape.
The teeth and tooth valleys are covered with fine canvas cloth, and the fine coarse cloth material, intermediate canvas material, core material, and unvulcanized rubber sheet are laminated in order on the molding die, and the state is This is based on a timing belt that is vulcanized and molded using heat and pressure.

In order to achieve the above object, the invention of claim (1) provides that the fine coarse cloth is made of a unidirectional nonwoven fabric with excellent wear resistance, and that the fiber density is thicker in the tooth troughs than in the tooth portions. and
Further, an intermediate canvas made of a high-tensile bias canvas with excellent fatigue resistance is continuously disposed inside the tooth portion and between the south canvas of the tooth valley and the mandrel.

In the invention of claim (2), the unidirectional nonwoven fabric is composed of meta-aramilad m fibers, polyphenylene sulfide fibers, polyester ether ketone fibers, or para-aramit fibers.

In the invention of claim (3), the high-tensile bias canvas is composed of high-strength nylon fibers, high-strength Tetoron fibers, high-strength vinylon fibers, or rose-based aramid m-fibers.

(Function) According to the inventions of claims (1) to (3), the fiber density of the fine fabric made of unidirectional nonwoven fabric is arranged to be higher in the tooth valley, thereby increasing the resistance of the tooth valley. Improves abrasion resistance. In addition, the intermediate canvas is continuously positioned between the fine canvas at the center of the tooth and the root of the tooth and the mandrel, increasing the rigidity of the tooth, especially the root, and preventing cracks at the root. is suppressed.

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

In FIG. 1 showing the overall configuration, reference numeral 1 denotes an endless timing belt, in which toothed portions 3 are disposed on the lower side of the belt base band 2 at predetermined pitch intervals in the longitudinal direction of the belt. The portions 4 (land portions) are arranged alternately.

A mandrel 5 is spirally embedded in the lower part of the belt base band 2, and a fine coarse cloth 6 covering the toothed portions 3 and 4 is attached to the lower surface of the belt. Further, an intermediate canvas 7 is embedded between the mandrel 5 and the coarse cloth 6, and the intermediate canvas 7 penetrates into the tooth 3 at a portion corresponding to the tooth portion 3, and at a portion corresponding to the tooth portion H4. In this case, it is configured so as to come into contact with the mandrel 5 and the fine coarse cloth 6.

The fine coarse cloth 6 is made of a unidirectional nonwoven fabric (see FIG. 2) in which fiber filaments 6a are arranged in one direction, and the toothed portion 4 has a higher fiber density than the toothed portion 3. As shown in FIG. 2, the filaments of the unidirectional nonwoven fabric are oriented in the belt width direction at the toothed portions and in the belt longitudinal direction at the toothed portions. On the other hand, in the intermediate canvas 7, the warp threads 7a and the weft threads 7b are inclined with respect to the longitudinal direction of the belt,
It is made of a bias-like high tensile strength woven fabric (see FIG. 4) with a high void ratio in which both threads 7a and 7b form a predetermined angle θ.

The specific configuration when the present invention is applied to a ZB type timing belt (number of teeth: 125) is as follows.

■Fine coarse cloth 6 Unidirectional nonwoven fabric made of 2 denier meta-aramid fiber (Conex, manufactured by Kijin Co., Ltd.) (Weight: Jt 100g
/rrr) is coated with a normal rubber compound containing ethylene unsaturated nitrile-conjugated diene highly saturated copolymer rubber as the main component, and the fiber filaments are oriented in a direction perpendicular to the belt length direction. It is equipped with non-woven fabric.

■Intermediate canvas 7 A bias canvas with a bias angle of 120 degrees is made using a plain weave fabric in which 25 strands of high-strength 420-denier nylon are twisted per inch in the usual manner, and the above-mentioned material containing phenolic adhesive is made. A coating treated with the rubber compound (2) was placed in the center of the tooth and between the mandrel and the nonwoven fabric in the tooth.

■The rubber mandrel for the belt base band and teeth is made of glued glass fiber (ECG1503/11), and the rubber for the belt base band and teeth is made of the above ■
A rubber compound of

In order to manufacture the timing belt 1, as shown in FIGS. 5 to 7, a fine coarse cloth is placed in a mold 21 in which toothed portions 21a and toothed portions 21, b are arranged alternately. A fine canvas material 22 (unidirectional non-woven fabric), an intermediate canvas material 23 (high tensile bias canvas), and a container material 24
and unvulcanized rubber sheets 25 are laminated in order from the bottom, and in this state are heated and pressurized to be vulcanized.

Due to this heating and pressurization, the unvulcanized rubber of the unvulcanized rubber sheet 25 flows out through the space of the intermediate canvas material 23 to the fine canvas material 22 side. Since the fine coarse cloth material 22 is composed of a unidirectional nonwoven fabric that easily stretches when stretched in the anti-fiber direction in which fiber filaments are not arranged, it is pressed by the unvulcanized rubber that flows out, and the tooth portion 21b of the molding die 21 is pressed. The fine canvas material 22 located in
Since it is also pressed against the molding die 21 (teeth portion 21b), the portion of the timing belt 1 that will become the tooth portion 4 does not change during vulcanization molding, and the other portions are stretched. It extends along the inner surface of the tooth portion 21b of the molding die 21.

In this way, since the fine canvas material 22 (non-woven fabric) which becomes the tooth portion 4 of the timing belt 1 is pressed together with the intermediate canvas material 23 by the container material 24, the tooth portion of the timing belt 1 is Since the fine coarse cloth material 22 in the portion 4 does not change and only the other portions are stretched, the fine coarse cloth material 22 (non-woven fabric) in the tooth portion 4 of the timing belt 1 where wear is the most problematic. It has a higher density and is advantageous in terms of wear resistance.

In addition, since the canvas material 22 is a unidirectional woven fabric, if the filaments are completely separated from each other, the orientation will not change to 0, but in reality, the filaments are intricately intertwined, so the vulcanization process At times, they tend to be pulled together and their orientation directions are reversed. In other words, the filament orientation is in the belt width direction in the tooth troughs, but as the nonwoven fabric is stretched in the tooth regions, the filament orientation changes in the belt longitudinal direction (see FIG. 2). As a result, the strength in the longitudinal direction of the belt increases at the tooth portion. However, non-woven fabrics do not have the same strength as woven fabrics, so areas that require strength are reinforced with intermediate canvas.

In addition, during vulcanization molding, the intermediate canvas material 23 is
Since it is bias-shaped, the parts other than the parts pressed by the core material 24 are stretched as the unvulcanized rubber flows out, and enter into the tooth valley part 21b of the molding die 21.

Therefore, it is not necessary to use the conventionally known stretchable yarn for the fine canvas material 22, and it is not only possible to select fibers that take wear resistance into consideration, but also for the intermediate canvas material 1 23 in the tooth root portion 4 of the timing belt 1. is stretched during vulcanization molding (press-fitting),
In the timing belt 1 which is the final product, the intermediate canvas 7 is located within the tooth portion 3 (dedendum portion), resulting in a higher strength tooth portion 3.

Next, a wear evaluation test (biaxial load running test) conducted on the timing belt will be described.

A belt was wound around two pulleys (1838M), and a constant load of 5 PS was applied to the vehicle at an environmental temperature of 140°C.
The time required for cracks to occur at the roots of the teeth, ie, the belt life T, and the wear rate U of the tooth canvas after 100 hours were measured. In addition, as a comparative example, a well-known nylon canvas using stretcher pull yarn was used as a tooth canvas, and other conditions were the same as those of the present invention example.

The wear rate U of the tooth canvas was calculated based on the following formula by observing the cross section of the belt before and after running with an electron microscope, measuring the respective canvas thicknesses gl and p2.

U-1(II)l-42)/ρ11×1002 As the test results are shown in the following table, the examples of the present invention are excellent in both belt life and wear rate.

(Effect of the invention) According to the inventions of claims (1) to (3), since the tooth fabric made of unidirectional nonwoven fabric is arranged so that the fiber density is higher in the tooth valley, Improves wear resistance. In addition, since an intermediate canvas made of high-tension bias canvas with excellent fatigue resistance is continuously located between the tooth canvas and the center of the tooth and the tooth base, The rigidity of the teeth is increased, and the occurrence of cracks at the root of the teeth is suppressed. Therefore, belt life is extended due to improved wear resistance and crack resistance.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, in which Fig. 1 is an overall configuration diagram of a timing belt, Fig. 2 is an explanatory diagram of a tooth canvas, and Fig. 3 is an explanatory diagram of the arrangement direction of fibers of the unidirectional nonwoven fabric of the timing belt. , FIG. 4 is an explanatory diagram of the intermediate canvas, and FIGS. 5 to 7 are explanatory diagrams of the manufacturing method. 1... Timing belt 2... Belt base band 3... Teeth 4... Teeth valley 5... Mandrel 6... ... Tooth canvas 7 ... Intermediate canvas 21 ... Molding mold 22 ... Fine canvas material 23 ... Core body material 24 ...・Intermediate canvas material 25...Unvulcanized rubber sheet 4 uo'1

Claims (3)

[Claims] (1) Teeth and tooth valleys are arranged alternately in the longitudinal direction of the belt under the belt base belt in which the mandrel is embedded in a spiral shape, and the teeth and tooth valleys are covered with a tooth canvas. In a timing belt that is vulcanized and formed by laminating a tooth canvas material, an intermediate canvas material, a core material, and an unvulcanized rubber sheet in order in a molding die, and heating and pressurizing them in this state, The tooth canvas is composed of a unidirectional non-woven fabric with excellent abrasion resistance, and the fiber density is higher in the tooth valley than in the tooth. A timing belt characterized in that an intermediate canvas made of high-tension bias canvas with excellent fatigue resistance is continuously disposed between the intermediate canvas. (2) The timing belt according to claim (1), wherein the unidirectional nonwoven fabric constituting the tooth canvas is composed of meta-aramid fiber, polyphenylene sulfide fiber, polyester ether ketone fiber, or para-aramit fiber. (3) Claim (1) or claim (2) wherein the high-tensile bias canvas constituting the intermediate canvas is composed of high-strength nylon fibers, high-strength Tetron fibers, high-strength vinylon fibers, or para-aramid fibers. Timing belt as stated.