JPH0544607Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to a toothed belt used, for example, to drive an overhead camshaft of an automobile internal combustion engine, and has particularly excellent bending fatigue resistance.
This invention relates to a toothed belt that has a long service life. (Prior technology) Unlike flat belts, V-belts, etc., toothed belts have excellent transmission efficiency because they do not slip, and they also have the advantage of being extremely low noise compared to transmission devices such as gears and chains. have. For this reason, the use of toothed belts has been expanding recently, such as in the synchronous drive of overhead cam (OHC) shafts in automobiles. The toothed belt for driving the OHC shaft runs at high speed and under high load in the high temperature environment of the engine room of an automobile. Moreover, as the performance of internal combustion engines increases, toothed belts are disposed in narrow spaces and run around small-diameter pulleys. Inside a toothed belt, core wires are usually arranged at predetermined intervals in the width direction, but as the pulley diameter becomes smaller, the core wires are forced to run along the pulleys. Therefore, if it does not have sufficient flexibility and pliability, it may break after running for a short time. Conventionally, the core wire of a toothed belt has been used by bundling and twisting E-glass fiber (general-purpose non-alkali glass fiber) filaments, as disclosed in, for example, Japanese Patent Application Laid-Open No. 159827/1982. Conventional core wires typically have a diameter of 9μm
The E glass fiber filament is usually mixed with a resorcinol/formalin resin latex mixture (hereinafter referred to as
The strands obtained by impregnating with REL are twisted under the conditions 3/13 (three strands of glass fiber filaments are first twisted to form a strand, and 13 strands are then twisted). The ropes are twisted at a ratio of 1/13 (twisting together 13 ropes formed by one strand), or strands are used. (Problem that the invention aims to solve) These conventional toothed belts using core wires are no longer able to meet the harsh conditions brought about by the high performance of internal combustion engines in recent years, and the lifespan of toothed belts is shortened. There is a tendency. For this reason, in recent years, the performance of internal combustion engines themselves has improved and their lifespans have become longer, but the lifespan of toothed belts has not improved that much, and for example, it is difficult to replace toothed belts used for OHC shaft drives. Must be done more frequently than before. Furthermore, if a toothed belt is rotated at high speed under high temperature along the outer diameter of a pulley with a small diameter, heat generated by friction between the fibers that make up the core wires will accumulate inside the toothed belt, causing the canvas and rubber to separate. Adhesion,
There is also the problem that the service life of the toothed belt is significantly reduced due to adhesion between the core wire and the rubber, adverse effects on the canvas itself, and adverse effects on the rubber itself. The present invention solves the above-mentioned conventional problems, and its purpose is to use a core wire that has excellent flexibility and bending fatigue resistance, so that it can be used in harsh environments. It is an object of the present invention to provide a toothed belt that can have a long service life even when used in OHC shaft drives of automobiles used in automobiles. (Means for Solving the Problems) The inventors of the present application replaced the conventional core wire made by twisting E-glass fiber filaments (general-purpose non-alkali glass fiber filaments) with a composition different from that of the E-glass fibers. High-strength glass fiber filaments with a diameter of 6 to 8 μm are used similarly to E-glass fibers.
After RFL treatment, by twisting them together to form a core wire under the following conditions, even though the rigidity of the high-strength glass fiber itself is higher than that of conventional E-glass fiber itself, it can be used as a core wire. It has been found that when used, the durability of the toothed belt is significantly improved and the service life of the toothed belt can be extended. The present invention was made based on such knowledge. The toothed belt of this invention has a diameter of 6~
8 μm high-strength glass fiber filaments are bundled to form a strand, and a given strand is
2. Pre-twist with the number of twists of 2 twists/25 mm to form a child rope having 500 to 800 filaments, and the child rope 9 to
It has a core wire formed by twisting 12 core wires in opposite directions at a twist rate of 1.8 to 2.2 times/25 mm, thereby achieving the above object. To explain the toothed belt of the present invention in more detail, as shown in FIG. 1, the toothed belt includes a main body 1 made of rubber, for example, and
It has teeth portions 2 extending in the width direction and arranged at predetermined intervals in the longitudinal direction. The tooth portion 2 has a trapezoidal shape, for example, as shown in FIG. The tooth portion 2
The shape of the tooth is not limited to the trapezoidal tooth ZA, but may be formed of a circular arc, for example. A plurality of core wires 4, 4, .
Each core wire 4 is inserted between the main body part 1 and the tooth part 2. The surface of each toothed portion 2, the surface of the main body portion 1 between adjacent belt toothed portions 2, and the surface of each core wire 4 are covered with a tooth cloth 3. Therefore, each tooth portion 2 is joined to the main body portion 1 through the gap between adjacent core wires. The core wire 4 is made by twisting high-strength glass fiber filaments under predetermined conditions in place of the conventionally used E glass fiber filament. As shown in Table 1, high-strength glass fiber has an increased content ratio of SiO ₂ component, A1 ₂ O ₃ component, and MgO component compared to E glass fiber, while CaO component and B ₂ O component The content ratio of the _three components has decreased. As a result, as shown in Table 2, the tensile strength and tensile modulus of high-strength glass fibers are significantly improved compared to E-glass fibers. Such high-strength glass fibers include U glass fiber (Nippon Glass Fiber Co., Ltd.),
Examples include T glass fiber (Nitto Boseki Co., Ltd.), R glass fiber (Vetrotex Saint Gobain), and S glass fiber (Owens Corning Fiberglass).

【table】

[Table] The core wire 4 in the toothed belt of the present invention consists of 500 to 800 filaments (1 strand as a strand) made of such high-strength glass fibers and having a relatively small diameter of 6 to 8 μm, preferably 7 μm. ~8 ropes, preferably 2 to 4 ropes) are bundled and pre-twisted 1.8 to 2.2 times/25 mm to produce a rope, and then the thus obtained ropes are bundled into 9 to 12 ropes. , 1.8
Formed by twisting ~2.2 times/25mm. The number of first twists is preferably 0 to 10% less than the number of first twists. Hydrogenated nitrile rubber is suitable for the main body portion 1 and tooth portions 2, but chlorosulfonated polyethylene (CSM) rubber, chloroprene (CR) rubber, etc. may also be used. In many cases, the main body part 1 and the tooth part 2 are similar and the same compound rubber is used, but the main body part 1
It is also possible to use the same type of rubber or a different type of compounded rubber depending on the characteristics required for each of the tooth portions 2 and 2. Furthermore, the modulus of the rubber can also be varied depending on the formulation. The main body part 1 and the tooth part 2 may be made of rubber having the same modulus, or they can be made to have a relative difference, such as by giving the main body part 1 flexibility and the tooth part 2 having rigidity. It is. The main body part 1 and the toothed part 2 may be formed integrally during vulcanization, as in the case of conventional toothed belts, or the toothed part 2 alone may be formed in advance and then vulcanized together with the main body part 1. good. In this embodiment, the warp yarns of the tooth cloth 3 in the belt longitudinal direction are made stretchable, and the weft yarns in the belt width direction are made non-stretchable. Normally, in the cloth weaving process, non-stretchable fibers are used in the longitudinal direction, and stretchable fibers are used in the width direction (weft). The warp of the belt here refers to the weft of the cloth in the weaving process. The weft material is preferably nylon 6.6, but aliphatic polyamides such as nylon 6, nylon 6.9, nylon 6.10, nylon 11, nylon 12, or polyamides of copolymers thereof may be used. Further, it may be a meta-type or para-type aromatic polyamide. Furthermore, polyester fibers can also be used, but there is no particular disadvantage whether they are aliphatic or aromatic. As the warp material, the same aliphatic polyamide, aromatic polyamide, aliphatic polyester, aromatic polyester, etc. as for the weft can be used. Further, the warp material may be the same material as the warp threads or may be a different material as long as it can be crimped. The fiber diameter of the warp material may be the same as that of the weft material, or there is no particular disadvantage if they are different. Furthermore, as for the weaving method of the tooth cloth 3, twill weave is suitable, but plain weave, diagonal weave, etc. may also be used. In this case, the weft has no elasticity, and the fabric is preformed so that the elongation at break of the weft is about 120% to 140%, and in some cases about 40 to 70%. Teeth may also be made and vulcanized. The tooth cloth 3 is bonded to the main body 1 and the teeth 2 by resorcinol-formalin latex treatment (REL treatment) or rubber treatment. As for the latex, the main body rubber may be a nitrile rubber latex, a chlorosulfonated polyethylene rubber latex, or a chloroprene rubber latex, depending on the tooth rubber. . Furthermore, it may be a modified latex of these materials, and there are no particular restrictions. Similarly, there are no particular restrictions on the rubber treatment material, and it may be nitrile rubber, chlorosulfonated polyethylene rubber, or chloroprene rubber. The tooth cloth 3 may be provided with a waterproof rubber layer having a thickness of about 0.02 to 0.06 mm between the cord and the cloth.
The thickness of the tooth cloth 3 is determined as appropriate depending on the purpose of the toothed belt. The toothed belt of the present invention has core wires 4 made of relatively small-diameter high-strength glass fiber filaments twisted together under predetermined conditions, so it has excellent flexibility and pliability. Even when wrapped around a pulley, it can run stably at high speed for a long period of time.
The use of small-diameter, high-strength glass fiber filaments allows for a wide selection of canvas thicknesses that can satisfy Pitch Line Difference (PLD). (Example) The present invention will be described below with reference to an example. Example 1 An endless nylon tooth cloth was wound around a cylindrical mold having 127 belt tooth grooves in the circumferential direction in close contact with the outer peripheral surface of the mold. On the other hand, 200 high-strength glass fiber filaments each having a diameter of about 7 μm were subjected to RFL treatment and then bundled to form three strands. Repeat these three strands 2.0 times/25mm
A child rope having 600 filaments was produced by pre-twisting with a twist number of . 11 such ropes,
Ply-twisting was performed at a twist count of 2.0 times/25 mm to produce core wire 4. That is, the twisting condition is 3/11.
Such a core wire was wound while rotating a cylindrical mold on a winding device at a rate of 20 core wires per inch while continuously shifting the winding position. Furthermore, a sheet made of hydrogenated nitrile rubber (HSN) is wrapped around the core wire and vulcanized under pressure.
The main body and belt teeth were made from After completion of vulcanization, the belt was cut to a widthwise dimension of 19.1 mm to obtain a toothed belt of the present invention. The obtained toothed belt was subjected to a multi-bending running test shown in FIG.
Toothed pulleys 21, 2 used for multi-bending running test
Pulleys 3, 25, and 27 are of the 14ZA standard, and the other pulleys 22, 24, and 26 are flat pulleys with a diameter of 52 mm. The initial tension of the toothed belt (19.1 mm width) was 15 kg・f, the pulley 25 was rotated at 6000 rpm, and the belt was run under no load at room temperature.
The time until the core wire broke was measured. As a result, the core wire broke after 2500 hours. Table 3 shows the results of the running test. A comparative example is shown below. In Comparative Examples 1 to 11 below, running tests were conducted using belts whose initial tensile strength was approximately the same as that of the toothed belt of Example 1 by adjusting the number of core wires. Comparative Example 1 In Example 1, the filament twisting conditions were set to 3/13. In order to match the initial strength of the belt with that of the example, the number of core wires was set at 18 per inch. A toothed belt was manufactured under the same conditions as in Example 1 except for the following conditions. When the toothed belt was subjected to the same multi-bending running test as in Example 1, the core wire broke after 1500 hours. Table 3 shows the results of the running test (the same applies below). Comparative Example 2 In Example 1, the core wire using high-strength glass fiber filament with a diameter of 9 μm was
A toothed belt was manufactured by driving 16 pieces. Other conditions are the same as in Example 1. When the toothed belt was subjected to the same multi-bending running test as in Example 1,
The core wire broke after 940 hours. Comparative Example 3 In Comparative Example 2, the filament twisting conditions were 3/13 and the number of core wires was 14 per inch.
I made it into a book. Other conditions were the same as in Comparative Example 2. The toothed belt was subjected to the same multi-bending test as in the example. The core wire broke after 1000 hours. Comparative Example 4 In Comparative Example 1, the core wire was made of high-strength glass fiber filament with a diameter of 5 μm.
A toothed belt was produced by driving 28 pieces per inch. Other conditions were the same as in Comparative Example 1. As a result of the multi-bending running test, the core wire broke after 1490 hours. Comparative Example 5 In Comparative Example 4, a toothed belt was produced by driving 25 core wires per inch with the twisting condition of high-strength glass fiber filaments set to 3/13.
Other conditions are the same as in Comparative Example 4. As a result of the multi-bending running test, the core wire broke after 1250 hours. Comparative Example 6 A toothed belt was produced in Example 1 by using the conventional E-glass fiber filament as the core wire and setting the number of core wires to 25 per inch.
Other conditions are the same as in Example 1. As a result of the multi-bending running test, the core wire broke after 1350 hours. Comparative Example 7 In Comparative Example 6, the conditions for twisting the E glass fiber filaments were 3/13, and the number of core wires was 22 per inch. Other conditions are the same as in Comparative Example 6. Multi-bending running test results 1190
The core wire broke over time. Comparative Example 8 In Comparative Example 6, a core wire was manufactured using an E glass fiber filament with a diameter of 9 μm. The number of core wires was set at 20 per inch. Other conditions are the same as in Comparative Example 6. As a result of the multi-bending running test, the core wire broke after 1000 hours. Comparative Example 9 In Comparative Example 8, the conditions for twisting the E glass fiber filaments were 3/13, and the number of core wires was 18 per inch. Other conditions are the same as in Comparative Example 8. As a result of the multi-bending running test, 800
The core wire broke over time. Comparative Example 10 In Comparative Example 6, an E glass fiber filament with a diameter of 5 μm was used, and the number of core wires was 36 per inch. Other conditions are Comparative Example 6
It is similar to As a result of the multi-bending running test, the core wire broke after 1370 hours. Comparative Example 11 In Comparative Example 10, the twisting conditions for the E glass fiber filaments were 3/13, and the number of core wires was 32 per inch. Other conditions were the same as in Comparative Example 10. As a result of the multi-bending running test,
The core wire broke after 1280 hours.

[Table] As is clear from the above examples and comparative examples, high-strength glass fiber filaments with a diameter of 7 μm were
A belt using core wires twisted under the twisting conditions of No. 11 has excellent bending fatigue resistance and significantly improved durability. The reason for this is inferred as follows. When the diameter of the high-strength glass fiber filament is 9 μm, the filament itself has high rigidity, and even when used as a core wire, the twisting conditions are as follows:
Regardless of whether it is 3/11 or 3/13, the flexibility and pliability are poor, and as a result, the durability of the belt is not improved. When the high-strength glass fiber filament has a diameter of 5 μm, the fiber diameter is small and the apparent rigidity of the filament itself is lower than that of a filament with a diameter of 9 μm. Therefore, even when used as a core wire, the twisting conditions are 3 Whether it is /11 or 3/13, flexibility and flexibility are improved. However, in order to bring the initial strength of the belt to a predetermined value, it is necessary to increase the number of core wires, and this increase in the number of cores increases the alignment of the cores (the difference in tension between the cores during winding). (and the arrangement of the core wires due to the flow of rubber during molding and vulcanization) becomes uneven, and durability does not improve. The same thing can be said when using E-glass fiber, and since the hardness of the glass surface is smaller than that of high-strength glass fiber, it is more susceptible to scratches due to friction than high-strength glass fiber, and the strength is higher than that of glass with the same diameter. Since it is inferior to high-strength glass fiber, it is thought that durability will not improve. In the case of high-strength glass fibers with a diameter of 7 μm, although the high-strength glass fibers themselves are rigid, when used in core wires, the flexibility and pliability improve, and it is possible to use core wires with a twisting condition of 3/11. The belt used has a good total balance of glass fiber strength, filament diameter, core wire alignment performance depending on the number of strokes, has excellent bending fatigue resistance, and has significantly improved durability. (Effects of the invention) The toothed belt of the invention has core wires in which high-strength glass fiber filaments of a predetermined diameter are twisted together under predetermined conditions, so it has excellent flexibility and pliability. Even when wrapped around a small-diameter pulley and run at high speed, it can run stably over a long period of time without being damaged. As a result, the toothed belt of the present invention can be used under harsh conditions.
Suitable for use in OHC shaft drive.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of the toothed belt of the present invention, and FIG. 2 is an explanatory diagram of a multi-bending running test. 1...Main body part, 2...Tooth part, 3...Tooth cloth, 4...
...heart line.

Claims (1)

[Scope of utility model registration request] High-strength glass fiber filaments with a diameter of 6 to 8 μm are bundled to form a strand, and each strand is first twisted at a twist rate of 1.8 to 2.2 times/25 mm.
Form a rope with 500 to 800 filaments, and rotate the 9 to 12 ropes in the opposite direction 1.8 to 2.2 times/25mm.
A toothed belt having core wires that are twisted with a twist count of .