JPH018759Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a toothed belt that comes into pressure contact with the groove surface of a toothed pulley when its teeth mesh with the groove of the toothed pulley.

(Prior Art) In general, toothed belts are known in which, when the teeth of the belt mesh with the grooves of a toothed pulley, they come into pressure contact with the groove surfaces of the grooves and receive compressive force.

Conventionally, such a toothed belt is a power transmission belt made of a polymeric material such as natural rubber or synthetic rubber, reinforced with a tension member, as described in Japanese Patent Publication No. 56-29141. A flexible toothed belt drive having a belt and at least one pair of pulleys, the belt having alternating teeth and grooves configured to engage alternating teeth and grooves of the pulley. , the belt is adapted to compressively engage the pulleys, i.e. the height of the teeth of the belt within the longitudinal extent of the belt between the pair of pulleys is greater than the depth of the grooves of the pulleys. and, when the belt runs around the pulley, a radially inner end portion of the teeth of the belt facing the pulley contacts a portion between the teeth of the pulley that defines a bottom of a groove of the pulley. and at the same time the teeth of the belt are compressed to reduce their height such that the radially outwardly facing outermost portions of the teeth of the pulley define the bottom of the grooves of the belt. It is known that the toothed belt is configured so as to come into contact with the toothed belt, and the toothed belt is caused to perform circular motion, thereby reducing noise and improving bending fatigue resistance.

However, in such a toothed belt, the teeth are elastically compressed by about 1 to 20% in the tooth height direction, so permanent compressive strain is generated during use, which prevents the toothed belt from performing circular motion. As a result, the above-mentioned effect disappears, and excessive pressure is applied to the tooth valley between adjacent teeth, causing early wear and cracks, resulting in a short belt life. Such defects are a problem because they are particularly accelerated under high-temperature atmospheric conditions such as those found in automobiles.

By the way, it is known that short fibers are used for reinforcement in toothed belts. for example,
In Japanese Utility Model Application Publication No. 53-162256, a main rubber is closely attached to the upper surface of a low-elongation, high-strength tensile member, tooth-shaped rubber is provided at a constant pitch on the lower surface of the tensile member, and the lower surface of the tensile member is Furthermore, a toothed power transmission belt is disclosed in which a protective layer in which short fibers are oriented in the width direction of the belt is adhered to the outer surface of toothed rubber, and the outer surface is further covered with canvas to which rubber is attached. JP-A-55-68735 describes a toothed belt in which a nonwoven fabric is used in place of the canvas and short fibers are mixed on the surface of the teeth. Furthermore, JP-A No. 55-57741 discloses a toothed body made of a hard elastic material provided on one side of the tensile body and a backing layer made of an elastic material provided on the other side of the tensile body. , the hard elastic material and the backing layer are in contact with each other forming a wavy interface centered on the tensile body,
A toothed belt is described in which the surfaces of the tooth bodies, including the valleys between adjacent tooth bodies, are covered with a woven fabric layer, and the hard elastic material contains reinforcing fibers, and US Pat.
No. 4,235,119 describes a toothed belt in which short fibers oriented in the longitudinal direction of the belt are provided inside a canvas covering the surface of the teeth.

However, although the rigidity of the teeth in all of the above belts is improved, the reinforcement in the height direction of the teeth is not sufficient. However, there is a problem in that the belt life is shortened.

In addition, Japanese Utility Model Application Publication No. 54-150052 discloses that a short fiber material is uniformly mixed into a rubber-like elastic base material, and a low-elongation, high-strength twisted rope is used as a tension body and is arranged in parallel in the longitudinal direction of the belt. A toothed belt formed by embedding and molding is described, and in Japanese Utility Model Application No. 55-68735, tensile members are embedded in parallel in a heat-resistant rubber base material, and only toothed parts are embedded in the rubber base material. A toothed belt is described in which a heat-resistant short fiber material is mixed and a heat-resistant and abrasion-resistant canvas is adhered to the surface of the teeth and molded, and US Pat. A toothed belt is included in the regulations.

However, although it is thought that the above-mentioned belt exhibits a certain degree of rigidity when used with the teeth elastically compressed in the tooth height direction, it is actually impractical to uniformly disperse the short fibers. However, there is a problem in that lumps are formed locally, the compressive strain becomes non-uniform, cracks occur, and the belt life ends prematurely.

(Purpose of the invention) The present invention provides a toothed belt as described above.
The main purpose is to suppress the occurrence of permanent deformation due to elastic compression deformation of the teeth and to improve belt life.

(Structure of the invention) The present invention provides a toothed belt as described above.
The toothed portion is characterized in that short fibers are arranged in the direction in which the toothed portion receives force from the groove surface of the groove of the toothed pulley against which the toothed portion is pressed, that is, in the direction in which the compressive force is received the most.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In the toothed belt 1 shown in Fig. 1, which has a toothed portion 1a and whose tooth tip surface 1b is elastically pressed against the lower groove surface of the groove of the toothed pulley, 2 is made of glass, steel, aromatic polyamide, which is in charge of power transmission. 3 and 4 are an upper rubber layer and toothed rubber layer made of an elastic material such as neoprene rubber forming a belt shape, and 5 is a toothed surface. This is a reinforced canvas layer made of canvas with a low coefficient of friction such as nylon that protects the

The upper rubber layer 3 and the tooth rubber layer 4 are made of cotton, polyester, polyamide, aramid, etc.
The short fibers 6 cut in the range of ~10 mm are the rubber component.
Only 5 to 50 parts by weight are mixed per 100 parts by weight. The short fibers 6 are arranged approximately in the belt width direction S ₁ in the upper rubber layer 3 and approximately in the tooth height direction S ₂ in the toothed rubber layer 4.
are arranged in

Further, the tooth tip surface 1 has a tooth portion 11a shown in FIG.
The toothed belt 11, in which 1b is pressed against the lower groove surface of the groove of the toothed pulley, has no short fibers mixed in the upper rubber layer 12, and the upper rubber layer 12 has heat resistance and cold resistance depending on the purpose. This is a uniform elastomer material with excellent ozone resistance. This toothed belt 11 has a toothed rubber layer 4 similar to the toothed belt 1 shown in FIG. Each is illustrated.

Next, an example of a method for manufacturing the toothed belt 11 shown in FIG. 1 will be explained based on FIG. 3.

First, a cylindrical mold 21 having a groove 21a with a uniform cross-section in the axial direction on its outer surface is covered with at least one layer of cylindrical canvas 22 that is elastic in the circumferential direction and has been adhesively treated in advance. fit.

On top of that, a cord 2 made of a material with low elongation such as glass, steel, or aromatic polyamide, which serves as a tensile material, is wound in a spiral shape, and then unvulcanized rubber is formed to form the tooth rubber layer 4. The sheet 23 is wound to a predetermined thickness. In addition, this rubber sheet 23
is a well-known rubber compound such as neoprene rubber 100
5 to 50 parts by weight of short fibers 6 (1 to 10 mm), which have been subjected to adhesive treatment as required, are mixed with respect to the parts by weight.

After wrapping the rubber sheet 23, it is pressure-vulcanized using a well-known vulcanizer. After completion of vulcanization, the cylindrical vulcanizate with teeth formed on the inner periphery is removed from the mold 21 and cut into a predetermined width depending on the application, thereby obtaining a predetermined toothed belt. Note that during vulcanization, when the rubber flows into the groove 21a of the mold 21 through the spaces between the cords 2, the short fibers 6 are rearranged in the tooth height direction due to the inflow.

In the above-mentioned toothed belts 1, 11, the short fibers 6 are arranged in the tooth height direction _S2 to improve compression resistance in this direction. Even if the tooth portions 1a, 11a are compressed in the tooth height direction _S2 , the absolute amount of deformation is reduced, making it possible to suppress the occurrence of permanent strain near the tips of the tooth portions 1a, 11a. As a result, the teeth 1a, 1
1a is elastically compressed and deformed over a long period of time, resulting in low running noise, less bending fatigue of cord 2, improved cold resistance, heat resistance, and ozone resistance, and makes it difficult for cracks to occur in the upper rubber layers 3 and 12. , exhibits excellent properties such as increased shear resistance of the tooth portions and reduced wear of the tooth root portions (hereinafter referred to as land portions) between adjacent tooth portions 1a or 11a.

Next, the toothed belt of the present invention shown in Fig. 2 (belt designation: 190S8M896, circumference: 896 mm, width: 19 mm) was manufactured.
We will explain the results of a comparative test conducted on a belt with 112 teeth (number of teeth 112) and a conventional toothed belt (same as the invented belt except that short fibers were not mixed in the teeth).

Sample The teeth of the toothed belt of the present invention were made by mixing 8 parts by weight of RFL-treated short fibers (3 denier 66 nylon cut into 2 mm pieces) with 100 parts by weight of a neoprene rubber compound. Become. The orientation angle of the short fibers 6 is set so that the angle α in the belt width direction and the angle β in the belt length direction with respect to the tooth height direction are within 5 degrees near the center of the tooth part (No. (See Figures 4 and 5). In addition, l ₁ is the vertical line, l ₂ is the short fiber 6
This is a line that coincides with the arrangement direction of .

Test Method The sample belt 31 was subjected to a running test using a simulator for an automobile camshaft drive shown in FIG. In other words, crankshaft pulley 3
2 (24 teeth, 6000rpm) and camshaft pulley 3
3 (48 teeth), and press it with a tension pulley 34 (diameter 60 mm), and leave it at room temperature.
A driving test was conducted under conditions of 80℃.

Evaluation method The permanent compressive strain of the tooth portion was evaluated by the amount of permanent compressive strain Δt ₁ of the tooth tip of the tooth portion 11a, as shown in FIG.

The land wear was evaluated by the land wear depth Δt ₂ as shown in FIG.

The bending fatigue resistance of the tensile body was evaluated by the tensile strength retention rate, where the tensile strength of the conventional type (or the invented type) before running was taken as 100.

The shear fatigue resistance of the tooth portion was evaluated using the tooth shear force retention ratio, which is the tooth shear force of the conventional type (or the invented type) before running, multiplied by 100.

Running noise is 10mm from camshaft pulley 33.
Proximity noise was measured by placing microphones at separate locations and evaluated accordingly.

Test results are as shown in Figures 9 to 13. In other words, the inventive type has less permanent compressive strain on the teeth than the conventional type (see Figure 9), less wear on the land area (see Figure 10), and the strength of the cord, which is a tensile member, is lower. It was found that the belt has excellent resistance to bending fatigue (see Fig. 11) and excellent resistance to shear fatigue of the teeth (see Fig. 12), and the belt life is improved. In addition, the inventive type produces less running noise than the conventional type (see Fig. 13) and is superior in terms of noise.

In addition to the above embodiments, as shown in FIGS. 14 and 15, the trapezoidal tooth portion 31 of the toothed belt 31
The flank surface 31b of a is the groove 3 of the toothed pulley 32.
In the case of the toothed belt 31 that is pressed against the side groove surface 32b of the toothed portion 2a and receives compressive force, the short fibers 33 are approximately placed against the flank surface 31b of the toothed portion 31a where the largest shearing force acts on the toothed portion 31a. By arranging in orthogonal directions, as in the above embodiment,
Deformation of the teeth and generation of permanent compressive strain can be suppressed.

To manufacture the toothed belt 31, first, a woven fabric that has been adhesively or rubber-coated in advance is placed in a cylindrical mold having grooves with a uniform cross-section in the axial direction on the outer surface so as to fit into the grooves. Wrap it in one or more layers in the circumferential direction while shaping it as shown. Then, rod-shaped rubber mixed with short fibers is filled into each groove gap of the mold so that the short fibers are substantially perpendicular to the tooth flank surface. After filling, one layer of thin unvulcanized adhesive rubber sheet is wrapped around it, and then a cord serving as a tensile body is wrapped in a spiral shape. Then, if necessary, wrap an unvulcanized adhesive rubber sheet, wrap the unvulcanized rubber sheet that will become the upper rubber layer on top of that, fit the vulcanizing sleeve on the outside, and vulcanize it with a well-known vulcanizer. Pressure vulcanization is carried out in the same manner as in the above-mentioned example.
Obtain the desired toothed belt.

Furthermore, as an example applied to a belt with a trapezoidal tooth profile, the above-mentioned short fibers are arranged in a substantially vertical direction, so that the effect of improving the tooth shear force can also be obtained, as shown in Fig. 16. A toothed belt 41 having a structure may also be used. That is, in the tooth portion 41a, the short fibers 42 are placed on the flank surface 41.
The short fibers 44 are arranged in a direction substantially perpendicular to b, and the short fibers 44 are arranged substantially in the tooth height direction above and below the cord 43, which is a tensile member.

(Effects of the Invention) Since the present invention is constructed as described above, the generation of permanent compressive strain in the teeth is suppressed, the belt life is extended, and various other excellent effects are achieved.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a perspective view of a toothed belt according to one embodiment, FIG. 2 is a perspective view of another embodiment, and FIG. 3 is a perspective view of the toothed belt of FIG. 1. An explanatory diagram of the manufacturing method, Figures 4 and 5 are diagrams of the orientation angle of short fibers in the teeth, Figure 6 is a schematic configuration diagram of the test system, and Figures 7 and 8 are diagrams of the evaluation method in the test. The explanatory diagrams, FIGS. 9 to 13 are graphs showing test results, and FIGS. 14 to 16 are explanatory diagrams of modified examples. 1, 11... Toothed belt, 1a, 11a... Teeth, 6... Short fiber, 31... Toothed belt, 31a
... tooth portion, 31b ... flank surface, 33 ... short fiber.

Claims (1)

[Claims for Utility Model Registration] (1) A toothed belt that presses against the groove surface of a groove of a toothed pulley when the teeth mesh with the groove, wherein the teeth press against the groove surface of the groove that presses against the groove. A toothed belt characterized by short fibers arranged in the direction that receives more force. (2) The toothed portion is such that the tooth tip surface is in pressure contact with the lower groove surface of the grooved portion of the toothed pulley, and the short fibers are arranged approximately in the height direction of the toothed portion.
Toothed belt as described in section. (3) A utility model registration in which the teeth have a trapezoidal tooth shape, the flank surface is in pressure contact with the side groove surface of the groove of the toothed pulley, and the short fibers are arranged in a direction approximately perpendicular to the flank surface. A toothed belt according to claim 1.