JP2001090784A - Low noise toothed belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise by a stroke when belt teeth abut to a pulley groove when the belt teeth of a toothed belt meshes with the pulley groove. SOLUTION: A toothed belt has belt teeth arranged at a prescribed pitch in the belt lengthwise direction and conductors arranged in a spiral shape by forming a pitch in the belt width direction by extending in the belt lengthwise direction. The center of the respective conductors appearing on a belt cross section is not on a straight line in the belt cross section in the belt width direction of a belt tooth bottom part existing between the belt teeth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a toothed belt.

[0002]

2. Description of the Related Art A toothed belt in which belt teeth are provided at equal pitches in a belt length direction at a portion where synchronous driving is required, such as an automobile, a general industrial machine, and OA equipment, and a peripheral edge of the belt is engaged with the belt teeth. And a pulley provided with a groove in the toothed belt transmission system.

As shown in FIG. 21, the toothed belt has a tooth rubber portion a constituting a belt tooth and a back rubber portion b on the back of the belt.
A spiral cord d extending in the belt length direction and forming a pitch in the belt width direction, and a canvas d covering the surface having the belt teeth.

A plurality of cords c appear in the belt section in the belt width direction at the bottom portion of the belt between the belt teeth, and the cords c are arranged on the belt body side of the canvas d. The center of the cords are aligned in the width direction, and the pitch line differential (hereinafter referred to as “PLD”), which is the shortest distance from the center of each cord to the outer surface of the belt of the canvas d, is at any point in the belt width direction. Are the same. Accordingly, when the toothed belt is wound around the pulley and operated, the belt teeth mesh with the pulley groove while the belt teeth in the belt width direction simultaneously contact the pulley groove.

[0005]

However, the toothed belt having the above-described structure has a problem that when the belt teeth mesh with the pulley grooves, the belt teeth hit the pulley grooves and generate a remarkable noise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a toothed belt having a low noise when the toothed belt is wound around a pulley and operated. It is to provide a manufacturing method.

[0007]

In order to achieve the above object, according to the present invention, in a belt cross section of a belt tooth bottom in a belt width direction, a center of a plurality of cores appearing in the belt cross section is measured from the center of the core to the surface of the tooth bottom. The shortest distance to, ie PL
D was assumed to be non-uniform.

Specifically, the invention according to claim 1 is a toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, the belt extending in the belt length direction and forming a pitch in the belt width direction. In the belt cross section in the belt width direction of the belt tooth bottom between the belt teeth, the center of each of the plurality of cores appearing in the belt cross section is aligned with a straight line. It is characterized by not having.

According to a second aspect of the present invention, in a toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, the belt extends in the belt length direction and forms a pitch in the belt width direction to form a spiral. In the belt cross section in the belt width direction of the bottom portion of the belt between the belt teeth in the belt width direction, at least one set of a plurality of the core wires appearing in the belt cross section is provided at the center of each core wire. , The shortest distance from the belt tooth bottom surface on the outer side of the belt is different.

According to a third aspect of the present invention, in a toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, the belt extends in the belt length direction and forms a pitch in the belt width direction to form a spiral. A belt covering the belt surface on the side where the belt teeth are provided, and appearing in the belt cross section in the belt width direction at the bottom of the belt teeth between the belt teeth. At least one set of the plurality of cores has a different minimum distance from the center of each core to the canvas surface on the outer side of the belt.

According to the configuration of each toothed belt described above, the toothed belt has at least two PLDs in the belt width direction. Therefore, when the belt is wound around the pulley and operated, each part of the belt teeth in the belt width direction comes into contact with the pulley groove in multiple stages, and each part of the belt teeth in the belt width direction is pulled by the pulley as in the related art. Noise is reduced as compared to the case where the grooves are simultaneously contacted.

According to a fourth aspect of the present invention, in a toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, the belt extends in the belt length direction and forms a pitch in the belt width direction to form a spiral. It is provided with a provided core wire and a canvas covering the belt surface on the side where the belt teeth are provided, and at the bottom of the belt teeth between the belt teeth, the canvas has a single portion and a double portion. Provided, the canvas is a double part, the canvas on the belt body side forms a protrusion,
On the belt body side of the belt tooth bottom, a part of the plurality of core wires is in contact with a single portion of the canvas, and another portion of the plurality of core wires is the belt body in a double portion of the canvas. It is characterized by being in contact with the canvas on the side.

According to a fifth aspect of the present invention, in a toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, the belt extends in the belt length direction and forms a pitch in the belt width direction to form a spiral. A first cord covering the provided core wire, the surface of the belt on which the belt teeth are provided, and a protrusion protruding from the belt body side of the first canvas at the bottom of the belt teeth between the belt teeth; A second canvas forming a portion and having a smaller dimension in the belt width direction than the width of the first canvas, wherein a part of the plurality of core wires is provided on the side of the belt main body at the bottom of the belt teeth. The other part of the plurality of core wires is in contact with the second canvas.

According to the configuration of each of the above-described toothed belts, the centers of a plurality of cords appearing in the belt cross section in the belt width direction at the bottom portion of the belt are not on a straight line, and the toothed belt has at least two PLDs in the belt width direction. Is more specific. In other words, a plurality of buried core sections appear in the belt section in the belt width direction at the bottom of the belt teeth, but since these cores contact the canvas covering the belt surface on the surface of the belt body, As the canvas has a single part and a double part, each core is buried in the belt thickness direction with the core line where the canvas touches the single part and the core line where the canvas touches the double part Will be different. Therefore, the PLD is different between the portion where the canvas is single and the portion where the canvas is double. As a result, when the toothed belt is wound around the pulley and operated, each portion of the belt tooth in the belt width direction comes into contact with the pulley groove in multiple stages, and the belt tooth is generated at that time to the pulley groove of the belt tooth. Is reduced as compared with the prior art.

According to a sixth aspect of the present invention, in the toothed belt according to the fourth aspect, the width of the double portion of the canvas in the belt width direction is not less than 5% and not more than 50% of the belt width. It is characterized by.

According to a seventh aspect of the present invention, in the toothed belt according to the fifth aspect, the width of the second canvas in the belt width direction is not less than 5% and not more than 50% of the belt width. I do.

According to the configuration of each of the toothed belts described above, the width of the double portion of the canvas in the belt width direction is set to an appropriate range with respect to the belt width. The effect of the invention of the toothed belt provided is more appropriately performed. That is, if the width is smaller than 5%, the function of contacting the belt teeth with the pulley grooves in multiple stages becomes sparse, and if the width exceeds 50%, poor engagement between the belt teeth and the pulley grooves is reduced. This may cause the belt to bend easily, resulting in impaired bending fatigue resistance of the belt.

As a method of manufacturing the toothed belt, the invention of a method of manufacturing a toothed belt according to claim 8 is as follows.
A first canvas setting step of covering a cylindrical first canvas on a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with a cylindrical axis, and a plurality of annular second canvases on the first cylindrical canvas; A second canvas setting step in which the sum of the width of the annular second canvas and the distance between adjacent annular second canvases at that time is equal to or less than the width of the toothed belt to be manufactured; A core wire setting step of spirally winding a core wire from both canvases to form a core layer, an unvulcanized rubber setting step of covering unvulcanized rubber on the core layer, heating and pressing And vulcanizing the unvulcanized rubber.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a toothed belt, wherein a plurality of annular second canvases are externally fitted to a cylindrical first canvas at intervals, and the width of the annular second canvas at that time is adjusted. A canvas preparing step of making the sum of the interval between the adjacent annular second canvases equal to or less than the width of the toothed belt, and a cylindrical mold having a number of tooth-shaped grooves extending in parallel with the cylindrical axis on the peripheral surface. A canvas setting step of covering the cylindrical first canvas onto which the annular second canvas is fitted, a core setting step of spirally winding a core from both the canvases to form a core layer, An unvulcanized rubber setting step of coating the unvulcanized rubber on the core layer, and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing are provided.

According to each of the above-described manufacturing methods, in the belt cross section at the bottom of the toothed belt of the toothed belt to be manufactured, the core wire where the canvas is in contact with the single portion (the first canvas) and the canvas have the double portion (the second portion). 2), and a toothed belt having a plurality of PLDs in the belt width direction can be manufactured.

Further, since the sum of the width of the annular second canvas and the interval between the adjacent second canvases is equal to or less than the width of the toothed belt to be manufactured, the canvas has a single portion and a double portion over the entire circumference of the belt. Parts can be provided. In addition, when the rubber-like cylindrical body obtained in the vulcanization process is sequentially cut into a ring by the width of the toothed belt, any toothed belt has a double portion of canvas and a single portion of canvas. In the resulting toothed belt, there may be a mixture of a toothed belt that has a portion where the canvas is doubled over the entire width of the belt and a toothed belt that has a portion where the canvas is single over the entire width of the belt. There is no.

According to a tenth aspect of the present invention, there is provided a method for manufacturing a toothed belt according to the eighth or ninth aspect, wherein the annular second canvas adjacent to the width of the annular second canvas is provided. It is characterized in that an integral multiple of the sum of the intervals between the canvases is equal to the width of the toothed belt to be manufactured.

With the above arrangement, when the rubber-like cylindrical body obtained in the vulcanization step is sequentially cut into the width of the toothed belt, all the toothed belts have the same position in the belt width direction. In this case, a plurality of toothed belts having the same configuration can be manufactured.

An eleventh aspect of the present invention is directed to a method of manufacturing a toothed belt, comprising: a first canvas setting step of covering the first cylindrical canvas with a cylindrical mold having a plurality of tooth-shaped grooves extending parallel to the cylindrical axis. And spirally winding the belt-shaped second canvas on the cylindrical first canvas at intervals, and calculating the sum of the width of the belt-shaped second canvas and the space between the adjacent belt-shaped second canvases. A second canvas setting step of not more than the width of the toothed belt to be manufactured, a core setting step of spirally winding a core from both the canvases to form a core layer, An unvulcanized rubber setting step of covering the unvulcanized rubber, and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing are provided.

According to a twelfth aspect of the present invention, there is provided a method of manufacturing a toothed belt, wherein a belt-shaped second canvas is spirally mounted on a cylindrical first canvas at intervals, and the width of the belt-shaped second canvas at that time is adjusted. A canvas preparing step of making the sum of the distance between the adjacent strip-shaped second canvases and the width of the toothed belt equal to or less than the width of the toothed belt; and a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with the cylindrical axis on the peripheral surface. A canvas setting step of covering the cylindrical first canvas on which the annular second canvas is mounted, a core setting step of spirally winding a core from both the canvases to form a core layer, An unvulcanized rubber setting step of covering the unvulcanized rubber on the wire layer, and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing are provided.

According to each of the above-described manufacturing methods, in the belt cross section at the bottom of the toothed belt of the toothed belt to be manufactured, the core wire where the canvas is in contact with the single portion (the first canvas) and the canvas have the double portion (the first canvas). 2), and a toothed belt having a plurality of PLDs in the belt width direction can be manufactured.

Further, since the sum of the width of the second belt-like canvas and the distance between the adjacent second belt-like canvases is equal to or less than the width of the toothed belt to be manufactured, the canvas has a single portion and a double portion over the entire circumference of the belt. Can be provided. In addition, when the rubber-like cylindrical body obtained in the vulcanization process is sequentially cut into a ring by the width of the toothed belt, any toothed belt has a double portion of canvas and a single portion of canvas. In the resulting toothed belt, there may be a mixture of a toothed belt that has a portion where the canvas is doubled over the entire width of the belt and a toothed belt that has a portion where the canvas is single over the entire width of the belt. There is no.

According to a thirteenth aspect of the present invention, there is provided a method for manufacturing a toothed belt according to the eleventh or twelfth aspect, wherein the belt-like second canvas adjacent to the width of the belt-like second canvas is provided. It is characterized in that an integral multiple of the sum of the intervals between the canvases is made substantially equal to the width of the toothed belt to be manufactured.

According to the above configuration, when the rubber-like cylindrical body obtained in the vulcanizing step is sequentially cut into a ring by the width of the toothed belt, all the toothed belts have the same position in the belt width direction. And a plurality of toothed belts having the same configuration can be manufactured.

According to a fourteenth aspect of the present invention, there is provided a method of manufacturing a toothed belt, wherein a belt-shaped canvas is spirally wound around a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with a cylindrical axis while overlapping a predetermined width. At this time, the width of the overlapping portion of the band-shaped canvas is made smaller than 1/2 of the width of the band-shaped canvas, and the sum of the width of the single portion of the band-shaped canvas and the width of the double portion of the band-shaped canvas is manufactured. A cloth setting step of not more than the width of the toothed belt to be formed, a core setting step of spirally winding a core from above the canvas to form a core layer, and an unvulcanized rubber on the core layer. And a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressurizing.

According to a fifteenth aspect of the present invention, there is provided a method of manufacturing a toothed belt, wherein a belt-like canvas is spirally wound while being overlapped at a constant width to form a cylindrical canvas, and the width of the overlapping portion of the belt-like canvas at that time is reduced. A canvas preparing step of making the width of the single section of the belt and the width of the double section of the belt equal to or less than the width of the toothed belt to be manufactured; ,
A canvas setting step of covering the cylindrical canvas on a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with the cylindrical axis on a peripheral surface, and a core layer spirally wound around the cylindrical canvas from above the cylindrical canvas. A core setting step of forming an unvulcanized rubber on the core layer, and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing. It is characterized by the following.

According to each of the above manufacturing methods, in the belt cross section at the bottom of the toothed belt of the toothed belt to be manufactured, there are a core wire where the canvas touches the single part and a core wire where the canvas touches the double part. And a plurality of Ps in the belt width direction
A toothed belt having an LD can be manufactured.

Further, since the width of the double portion of the band-shaped canvas is smaller than 1/2 of the width of the band-shaped canvas, there is no portion where the overlap of the canvas becomes triple or more.

Further, since the width of the canvas is equal to or less than the width of the toothed belt for producing the sum of the width of the single portion and the width of the double portion of the canvas, the canvas has a single portion and a double width over the entire circumference of the belt. Can be provided. In addition, when the rubber-like cylindrical body obtained in the vulcanization process is sequentially cut into a ring by the width of the toothed belt, any toothed belt has a double portion of canvas and a single portion of canvas. In the resulting toothed belt, there may be a mixture of a toothed belt that has a portion where the canvas is doubled over the entire width of the belt and a toothed belt that has a portion where the canvas is single over the entire width of the belt. There is no.

According to a sixteenth aspect of the present invention, there is provided a method of manufacturing a toothed belt according to the fourteenth or fifteenth aspect, wherein the width of a single portion of the belt-shaped canvas and the width of the belt-shaped canvas are determined. Is made substantially equal to the width of the toothed belt to produce an integral multiple of the sum of the width of the double part.

With the above configuration, when the rubber-like cylindrical body obtained in the vulcanization step is sequentially cut into a ring at the width of the toothed belt, all the toothed belts manufactured have the same form. And a plurality of toothed belts having the same configuration can be manufactured.

[0037]

As described above, according to the first to fifth aspects of the present invention, the toothed belt has at least two PLDs in the width direction of the belt. Each portion of the tooth in the belt width direction comes into contact with the pulley groove in multiple stages, so that noise generated by the belt tooth hitting the pulley groove can be reduced.

According to the sixth and seventh aspects of the present invention, the width of the double portion of the canvas in the belt width direction is set to an appropriate range with respect to the belt width. The function of the invention described in claim 4 or claim 5 to be brought into contact is more appropriately performed.

Further, claims 8, 9, 11, 12, 1
In each of the inventions of Nos. 4 and 15, the canvas covering the belt surface can be provided with a single portion and a double portion, and a toothed belt having a plurality of PLDs in the belt width direction can be manufactured. And, since the width of the canvas is less than the width of the toothed belt that produces the sum of the width of the single part and the width of the double part, the canvas has the double part and the double cloth over the entire circumference of the belt. A toothed belt having a section is manufactured.
Further, when the rubber-like cylindrical body obtained in the vulcanization step is sequentially cut into round pieces, any toothed belt has a single portion of canvas and a double portion of canvas over the entire circumference of the belt. can do.

In each of the tenth, thirteenth and sixteenth aspects of the present invention, the width of the belt for producing the integral multiple of the width of the single portion of the canvas and the width of the double portion for the canvas is adjusted. Therefore, when the rubber-like cylindrical body obtained in the vulcanization process is sequentially cut into a ring by the width of the toothed belt, the position where the canvas becomes double in the belt width direction is the same for all the toothed belts. It is possible to manufacture a plurality of toothed belts having the same configuration.

[0041]

Embodiments of the present invention will be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 shows a toothed belt A according to Embodiment 1 of the present invention. The toothed belt A has a tooth rubber portion 1 which forms belt teeth protruding at a predetermined pitch in the belt length direction;
Back rubber portion 2 constituting the belt back portion, core wire 3 extending in the belt length direction and spirally formed with a pitch in the belt width direction, and first canvas covering the surface on the belt tooth side As a feature of the present invention, the second canvas 5 is laminated at the center portion of the first canvas 4 on the belt body side at the bottom of the belt teeth to form a protrusion. A part of the plurality of cords 3, 3,... Appearing in the belt cross section in the belt width direction at the bottom of the belt teeth is in contact with the first canvas 4, and the other part is in contact with the second canvas 5. Further, the width of the second canvas in the belt width direction is about 32% with respect to the belt width. FIG.
As shown in FIG. 2, the second canvas 5 is buried in the center of the belt along the belt length direction.

The tooth rubber portion 1 and the back rubber portion 2 form the main body of the toothed belt A. These are made of the same rubber composition, and the main rubber to be applied is not particularly limited, and includes chloroprene rubber (CR), hydrogenated nitrile rubber (H-NBR), ethylene-propylene-diene terpolymer rubber (EPDM) and the like. Is used.

The core 3 bears the tension applied to the belt. In addition, in the meshing transmission by the toothed belt, a high degree of dimensional stability is required for the belt because it is necessary to avoid poor meshing between the belt teeth and the pulley grooves, and the core wire 3 has a high elastic modulus such as glass fiber and aromatic polyamide. Twisted yarns such as fibers and metal fibers are preferably used. Then, the core wire 3 is subjected to an adhesive treatment with resorcinol-formalin latex (RFL), rubber glue, or both for bonding with rubber.

The first canvas 4 covers and protects the surface of the toothed belt A on the side of the belt teeth, and reduces wear of the belt due to contact with the pulley. The material of the first canvas 4 is not particularly limited, and a woven fabric or a knitted fabric such as a nylon fiber or an aromatic polyamide fiber is used. Stretched yarn is used for the yarn extending in the length direction. Also,
The first canvas is subjected to an adhesive treatment with a rubber paste or the like in order to improve the adhesiveness with rubber and the abrasion resistance.

The second canvas 5 is laminated on the belt body side of the first canvas 4. By the way, generally, in a toothed belt,
A cord is arranged on the belt body side of the canvas at the bottom of the belt teeth. Therefore, as a feature of the present invention, the toothed belt A
Is provided with the second canvas 5, so that the core wire 3 located on the belt body side of the first canvas 4 at the bottom of the belt teeth and the core wire 3 located on the second canvas 5 have a belt thickness. The embedding position in the direction will be different. That is, the center of each core is not aligned, and the PLD of the portion where the core 3 is located on the first canvas 4 is different from the PLD of the portion where the core 3 is located on the second canvas 5. Thus, the toothed belt A has a plurality of PLDs in the belt width direction. Therefore, when the toothed belt A is wound around the pulley and operates, the belt teeth come into contact with the pulley groove in two stages, and the noise generated by the impact of the belt teeth on the pulley groove is as follows. The number of belt teeth is reduced as compared with the case where the respective portions of the belt teeth in the belt width direction simultaneously contact the pulley grooves as in the related art. Further, since the width of the second canvas 5 in the belt width direction is about 32% of the belt width and is in the range of 5% to 50%, the above noise can be reduced without impairing the bending fatigue of the toothed belt. . The material of the second canvas 5 is not particularly limited, and a woven fabric or a knitted fabric such as nylon fiber or aromatic polyamide fiber is used as in the case of the first canvas 4, and is subjected to an adhesive treatment with rubber glue or the like. Is done. However,
In order not to hinder the flow of rubber during belt vulcanization molding, it is desirable to have elasticity in the belt length direction.

In the first embodiment, the toothed belt A has the belt teeth on one surface of the belt. However, the present invention is not limited to this. It may be a belt. In this regard, the same applies to the following embodiments 2 to 4, 6, and 8. (Embodiment 2) FIG. 3 shows a toothed belt B according to Embodiment 3 of the present invention. In addition, the toothed belt A according to the first embodiment.
The same reference numerals are used for the same parts. The toothed belt B includes a tooth rubber portion 1 that forms belt teeth protruding at a predetermined pitch in the belt length direction, a back rubber portion 2 that forms a belt back portion, a belt length direction extending and a belt width. A core wire 3 formed in a spiral with a pitch in the direction;
A first canvas 4 covering the surface of the belt teeth, and as a feature of the present invention, a second canvas 5 is laminated on one belt end of the first canvas 4 on the belt body side at the bottom of the belt teeth. A projection is formed. Then, a plurality of cords 3, which appear in the belt cross section in the belt width direction at the bottom of the belt teeth,
A part of 3,... Is in contact with the first canvas 4, and another part is in contact with the second canvas 5. Further, the width of the second canvas in the belt width direction is about 32% with respect to the belt width. As shown in FIG. 4, the second canvas 5 is embedded at one belt end along the belt length direction.

Other configurations, operations, and effects are the same as those of the first embodiment. (Embodiment 3) FIG. 5 shows a toothed belt C according to Embodiment 3 of the present invention. In addition, the toothed belt A according to the first embodiment.
The same reference numerals are used for the same parts. The toothed belt C has a tooth rubber portion 1 forming belt teeth protruding at a predetermined pitch in the belt length direction, a back rubber portion 2 forming a belt back portion, and a belt width extending in the belt length direction and having a belt width. A core wire 3 formed in a spiral with a pitch in the direction;
A first canvas 4 covering the surface of the belt tooth side, and as a feature of the present invention, second canvases 5 and 5 are laminated on both ends of the belt body side of the first canvas 4 at the bottom of the belt teeth. A projection is formed. Then, a plurality of cords 3, which appear in the belt cross section in the belt width direction at the bottom of the belt teeth,
A part of 3,... Is in contact with the first canvas 4, and another part is in contact with the second canvas 5, 5. Also, the second in the belt width direction
The width of the canvas is about 68% of the width of the belt. As shown in FIG. 6, the second canvas 5, 5 is embedded at both ends of the belt along the belt length direction.

Here, the two second canvases 5, 5 may have the same thickness or different thicknesses. For example, if the thicknesses of the two canvases are different from each other, the embedded core will be divided into three parts depending on the position in the belt thickness direction in the cross section of the belt tooth bottom in the belt width direction.
That is, such a toothed belt has three PLDs in the belt width direction. Therefore, when the toothed belt is wound around the pulley and operated, the belt teeth come into contact with the pulley groove in three stages, and the noise caused by the impact generated when the belt teeth contact the pulley groove is further reduced. Reduced.

Other constructions, operations and effects are the same as those of the first embodiment except that the width and width of the second canvas in the belt width direction are 5% to 50% of the belt width and thus have no effect. Are identical. (Embodiment 4) FIG. 7 shows a toothed belt D according to Embodiment 3 of the present invention. In addition, the toothed belt A according to the first embodiment.
The same reference numerals are used for the same parts. The toothed belt D has a tooth rubber portion 1 that forms belt teeth protruding at a predetermined pitch in the belt length direction, a back rubber portion 2 that forms a belt back portion, a belt width direction extending in the belt length direction, and a belt width. A core wire 3 formed in a spiral with a pitch in the direction;
A first canvas 4 that covers the surface of the belt teeth, and a feature of the present invention is that three second canvases 5 are provided at the center and both ends of the belt body side of the first canvas 4 at the bottom of the belt teeth. 5, 5 are laminated to form a protruding portion. A part of the plurality of cords 3, 3,... Appearing on the belt cross section in the belt width direction at the bottom of the belt tooth is in contact with the first canvas 4, and the other part is in contact with the second canvas 5, 5, 5. I have. The width of the second canvas in the belt width direction is about 69% of the belt width. As shown in FIG. 8, the second canvas 5, 5, 5 is buried at the center and both ends of the belt along the belt length direction.

Here, the three second canvases 5, 5, 5
May have the same thickness or different thicknesses. For example, if the thicknesses of the three canvases are different from each other, in the cross section of the belt tooth bottom in the belt width direction, the embedded core wire is divided into four parts depending on the position in the belt thickness direction. That is, such a toothed belt has four PLDs in the belt width direction. Therefore, when this toothed belt is wound around the pulley and operated, the belt teeth come into contact with the pulley groove in four stages, and the noise caused by the impact generated when the belt teeth contact the pulley groove is further reduced. Reduced. Therefore, as the thicknesses of the second canvases 5, 5, 5 become various, the noise can be further reduced.

Other constructions, functions and effects are the same as those of the first embodiment except that the width and width of the second canvas in the belt width direction are 5% to 50% of the belt width and thus have no function and effect. Are identical. (Embodiment 5) <First canvas setting step> As shown in FIG. 9, a cylindrical mold 11 having a plurality of tooth-shaped grooves extending in parallel to a cylindrical axis on a peripheral surface.
A first cylindrical canvas 12 having elasticity in the circumferential direction. <Second canvas setting step> A plurality of annular second canvases 13, 13,... Having substantially the same circumferential length as the first canvas 12 (FIG. 10A)
As shown in FIG. 10 (b), the cylindrical first canvas is fitted over the first canvas at a predetermined interval.

At this time, the sum of the width of the annular second canvas 13 and the interval between adjacent second canvases 13 is made equal to the width of the toothed belt to be manufactured. In this way, the canvas can have a single portion and a double portion over the entire circumference of the belt. In addition, when the rubber-like cylindrical body obtained in the vulcanization process is sequentially cut into a ring by the width of the toothed belt, the position where the canvas becomes double in the belt width direction is the same for all the toothed belts. It is possible to manufacture a plurality of toothed belts having the same configuration. When the rubber-like cylindrical body obtained in the vulcanization process is cut into a ring by the width of the toothed belt, each toothed belt has a portion where the canvas is double and a portion where the canvas is single Things.
When the rubber-like cylindrical body obtained in the vulcanization step is sequentially cut into a ring by the width of the toothed belt, the second canvas 13 is embedded at the same position in the belt width direction for each toothed belt. It is possible to manufacture a plurality of toothed belts having the same configuration. <Core wire setting step> As shown in FIG.
After setting the second canvas 13, the S-twisted and Z-twisted cores 14 are wound in a double spiral so that they are alternately arranged and are arranged one by one at intervals. <Unvulcanized rubber setting step> As shown in FIG.
4 is set, and an unvulcanized rubber sheet 15 is wound around several times, and a release paper 16 is put thereon as shown in FIG. The release paper is for facilitating removal from the vulcanization can after vulcanization molding. <Vulcanization Step> A cylindrical mold in which the above members are set is put into a vulcanization vessel, and rubber is vulcanized at a predetermined temperature and pressure for a predetermined time to obtain a cylindrical rubber composite. <Grinding Step> The rubber on the outer peripheral surface of the rubber composite is ground together with the release paper 16 so that the obtained belt has a uniform thickness. <Width cutting step> The ground rubber composite is cut into a predetermined width to obtain a toothed belt.

In the fifth embodiment, the second canvas 13
The sum of the width of the second canvas 13 and the distance between the adjacent second fabrics 13 is assumed to be equal to the belt width of the toothed belt to be manufactured. It may be equal. (Embodiment 6) FIG. 14 shows a toothed belt E according to Embodiment 3 of the present invention. The same parts as those of the toothed belt A according to the first embodiment are denoted by the same reference numerals. The toothed belt E has a tooth rubber portion 1 forming belt teeth protruding at a predetermined pitch in the belt length direction, a back rubber portion 2 forming a belt back portion, a belt width direction extending in the belt length direction, and a belt width. Helical wire 3 with a pitch in the direction
And a first canvas 4 that covers the surface on the side of the belt teeth.
As a feature of the present invention, the first canvas 4 at the bottom of the belt tooth is provided.
The second canvas 5 is laminated on the belt body side of the belt to form a protruding portion. A part of the plurality of cords 3, 3,... Appearing in the belt cross section in the belt width direction at the bottom of the belt teeth is in contact with the first canvas 4, and the other part is in contact with the second canvas 5. Further, the width of the second canvas in the belt width direction is about 32% with respect to the belt width. As shown in FIG. 15, the second canvas 5 is embedded in the belt body at an angle to the belt length direction. Therefore, the position of the second canvas in the belt width direction is not constant.

Other configurations, operations, and effects are the same as those of the first embodiment. Embodiment 7 A method for manufacturing the toothed belt E according to Embodiment 6 will be described as Embodiment 7 of the present invention. The same parts as those in the fifth embodiment are denoted by the same reference numerals. <First canvas setting step> A cylindrical first canvas 12 having elasticity in the circumferential direction is put on a cylindrical mold 11 having a plurality of tooth-shaped grooves extending in parallel with the cylindrical axis on the peripheral surface. <Second Canvas Setting Step> As shown in FIG. 16, a belt-shaped second canvas 21 is spirally wound at predetermined intervals on a cylindrical first canvas 12 covering a cylindrical mold 11.

At this time, the sum of the width of the second belt-like canvas 21 and the interval between the adjacent second belt-like canvases 21 is made substantially equal to the width of the toothed belt to be manufactured. In this way, the canvas can have a single portion and a double portion over the entire circumference of the belt. In addition, when the rubber-like cylindrical body obtained in the vulcanization process is cut into rounds with the width of the toothed belt, each toothed belt has a portion where the canvas is double and a portion where the canvas is single. Having the following. Further, when the rubber-like cylindrical body obtained in the vulcanization process is sequentially cut into a ring by the width of the toothed belt, the belt-like second canvas 21 is embedded at the same position in the belt width direction in each toothed belt. It is possible to manufacture a plurality of toothed belts having the same configuration.

The code setting step, rubber sheet setting step, vulcanizing step, grinding step and width cutting step are the same as those in the fifth embodiment.

In the seventh embodiment, the cylindrical mold 11
After covering the first cylindrical canvas 12, the second belt 21 is spirally wound on the first cylindrical canvas 12, but the second canvas 21 is spirally wound on the first canvas 12 in advance. What is wound and affixed may be covered on the cylindrical mold 11.

In the seventh embodiment, the sum of the width of the second strip 21 and the distance between the second strips 21 is substantially equal to the width of the toothed belt to be manufactured.
The present invention is not particularly limited to this, and may be a case where an integral multiple of the above sum is substantially equal to the belt width. (Eighth Embodiment) FIG. 17 shows a toothed belt F according to an eighth embodiment of the present invention. The same portions as those of the toothed belt A according to the first embodiment are denoted by the same reference numerals. The toothed belt F has a tooth rubber portion 1 that forms belt teeth protruding at a predetermined pitch in the belt length direction, a back rubber portion 2 that forms a belt back portion, a belt length direction extending and a belt width. It is composed of a cord 3 spirally provided with a pitch in the direction and a canvas 4 covering the surface on the belt tooth side. As a feature of the present invention, at the bottom of the belt teeth, the canvas 4 has a single portion, and the canvas 4 forming a protrusion on the canvas surface on the belt body side has a double portion.
A part of the plurality of cords 3, 3,... Appearing on the belt cross section in the belt width direction at the bottom of the belt teeth has the canvas 4 in contact with the single part, and the other part has the canvas 4 in contact with the double part. ing. The width of the second canvas in the belt width direction is about 34% of the belt width. As shown in FIG.
The canvas 4 covers the belt surface while forming a partially overlapped portion.

The other structure, operation, and effect are the same as those of the first embodiment except that the role of the second canvas is fulfilled by the canvas portion on the belt body side where the canvas is doubled. (Embodiment 9) A method of manufacturing the toothed belt F according to Embodiment 8 will be described as Embodiment 9 of the present invention. The same parts as those in the fifth embodiment are denoted by the same reference numerals. <Reinforcing cloth setting step> As shown in FIG. 19, a cylindrical mold 11 having a large number of tooth-shaped grooves extending in parallel with the cylindrical axis on its peripheral surface.
, A belt-shaped canvas 31 is spirally wound while overlapping the predetermined width.

At this time, the sum of the width of the portion where the belt-shaped canvas 31 is doubled and the width of the portion where the belt-shaped canvas 31 is single is substantially equal to the width of the belt to be manufactured. In this way, the canvas can have a single portion and a double portion over the entire circumference of the belt. In addition, when the rubber-like cylindrical body obtained in the vulcanization process is cut into rounds with the width of the toothed belt, each toothed belt has a portion where the canvas is double and a portion where the canvas is single. Having the following. In addition, when the rubber-like cylindrical body obtained in the vulcanization step was sequentially cut into a ring by the width of the toothed belt, the belt-like canvas 31 was embedded at the same position in the belt width direction in each of the toothed belts. And a plurality of toothed belts having the same configuration can be manufactured.

The band-shaped canvas 31 is wound around the cylindrical mold 11 so that a certain width overlaps within a range of up to half of the width of the canvas 31. Thereby, the strip-shaped canvas 3 is placed on the cylindrical mold 11.
The occurrence of a triple portion of 1 is avoided.

The cord setting step, rubber sheet setting step, vulcanizing step, grinding step and width cutting step are the same as those in the fifth embodiment. Thus, the toothed belt F is manufactured.

In the ninth embodiment, the cylindrical mold 1
The belt-shaped canvas 31 is spirally wound while overlapping the predetermined width of the belt-like canvas 1. Alternatively, a cylindrical canvas formed by spirally winding the belt-shaped canvas 31 while overlapping the belt-shaped canvas 31 with a predetermined width may be put on the cylindrical mold.

In the ninth embodiment, the strip-shaped canvas 31 is used.
Although the sum of the width of the single portion and the width of the double portion of the belt-shaped canvas 31 is substantially equal to the belt width of the toothed belt to be manufactured, the present invention is not particularly limited to this. May be substantially equal to the belt width. (Other Embodiments) In each of the toothed belts according to the first to fourth, sixth, and eighth embodiments, the matrix forming the belt main body is made of rubber, and the surface on the tooth side of the belt is covered with canvas. The present invention is not particularly limited to this, and a toothed belt in which a helical cord extending in the belt length direction and forming a pitch in the belt width direction is buried, and a polyurethane resin or a thermoplastic resin is used as a matrix. It may be.

As a method for producing a toothed belt using a polyurethane resin as a matrix, for example, there is the following method.

A cylindrical mold having a number of tooth-shaped grooves extending in parallel with the cylindrical axis on the peripheral surface is prepared. This cylindrical mold has a convex portion for supporting the core wire at the top of the ridge formed between the tooth-shaped grooves, and the cross-sectional shape of the convex portion along the cylindrical mold axis is It has a wave shape with a smaller cycle than the width of the belt to be manufactured.

A core wire is spirally wound around the cylindrical mold, placed in a cylindrical outer mold, and the urethane prepolymer is filled in a gap formed between the cylindrical mold and the outer mold. Inject and defoam. Then, the prepolymer is reacted by heating for a predetermined time to form a cylindrical polyurethane-fiber composite. Furthermore, by cutting this into a predetermined width, the toothed belt made of polyurethane according to the present invention can be manufactured.

[0068]

EXAMPLES The following examples and comparative examples were subjected to noise test evaluation. (Evaluation Belt)-Example-A cylindrical dies having a peripheral length of 840 mm and having a number of tooth-shaped grooves extending in parallel with the cylindrical axis was covered with a cylindrical first nylon canvas stretchable in the circumferential direction. Next, a second nylon canvas having a width of 10 mm and made of the same material as the nylon canvas was spirally wound thereon. At this time, the spiral pitch was 20 mm. Then, from above, the S twisted yarn and the Z twisted yarn of the glass fiber core wire that had been subjected to the adhesion treatment with a resorcinol-formalin latex (RFL) solution were wound in a double spiral as a pair. Further, a chloroprene rubber (CR) sheet was wrapped around the wrapper several times, and release paper was wrapped thereover. This was put into a vulcanization can, and a predetermined temperature and pressure were applied for a predetermined time to form a rubber-like cylinder on the periphery of the cylindrical mold. Then, the outer periphery of the cylindrical body was ground and cut into a 30 mm-wide ring to prepare a toothed belt according to the example. The toothed belt according to this embodiment has a belt circumference of 840 mm and a belt width of 30.
mm, and the pitch of the belt teeth is 8 mm.
Since the width of the second nylon canvas in the belt width direction is about 10 mm, the width of the second nylon canvas is about 33% of the belt width.

Comparative Example A toothed belt having the same configuration as the above example except that the second nylon canvas was not used was used as a comparative example. (Test Method) As shown in FIG. 20, the toothed belts of the above embodiment and the comparative example were wound around two pulleys of a driving pulley 41 and a driven pulley 42 each having 24 pulley grooves on the peripheral edge thereof, and The position of the driven pulley 42 was set such that a tension of 441 N was applied to the attached belt 43. And
The rotation speed of the driving pulley 41 was gradually increased from 300 rpm to 5000 rpm, and the noise at each rotation speed was measured. The measurement was performed at room temperature, and the microphone 44 for detecting noise was set at a position 300 mm above the driving pulley. (Test Results) The test results are shown in FIG. As shown in FIG. 21, the rotation speed of the driving pulley 41 is 300 to 50.
It can be seen that the example has a lower noise of about 5 dBA than the comparative example over the entire range of 00 rpm. That is, in the comparative example, the PLD in the belt width direction is uniform, and each part of the belt teeth in the belt width direction simultaneously contacts the pulley groove, and noise due to the impact is observed. In contrast,
In the embodiment, since the second nylon canvas is embedded, there are two PLDs of the toothed belt in the belt width direction, so that the contact of the belt teeth with the pulley grooves occurs in two stages, and the belt teeth are The noise caused by the impact generated when the abutment comes into contact with the pulley groove is reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a toothed belt A according to Embodiment 1 of the present invention.

FIG. 2 is a front view of the toothed belt A according to the first embodiment of the present invention on the side of the belt teeth.

FIG. 3 is a perspective view of a toothed belt B according to Embodiment 2 of the present invention.

FIG. 4 is a front view of a toothed belt B according to a second embodiment of the present invention, on the side of the belt teeth.

FIG. 5 is a perspective view of a toothed belt C according to Embodiment 3 of the present invention.

FIG. 6 is a front view of a toothed belt C according to a third embodiment of the present invention, on the side of the belt teeth.

FIG. 7 is a perspective view of a toothed belt D according to Embodiment 4 of the present invention.

FIG. 8 is a front view of a toothed belt D according to a fourth embodiment of the present invention on the side of the belt teeth.

FIG. 9 is a view showing a first canvas setting step according to Embodiment 5 of the present invention.

FIG. 10 is a view showing a second canvas setting step according to the fifth embodiment of the present invention.

FIG. 11 is a diagram illustrating a core wire setting step according to a fifth embodiment of the present invention.

FIG. 12 is a view showing an unvulcanized rubber setting step according to Embodiment 5 of the present invention.

FIG. 13 is a diagram showing a state in which release paper is wound around rubber in an unvulcanized rubber setting step according to Embodiment 5 of the present invention.

FIG. 14 is a perspective view of a toothed belt E according to Embodiment 6 of the present invention.

FIG. 15 is a front view of the toothed belt E according to a sixth embodiment of the present invention on the side of the belt teeth.

FIG. 16 is a view showing a second canvas setting step according to the seventh embodiment of the present invention.

FIG. 17 is a perspective view of a toothed belt F according to Embodiment 8 of the present invention.

FIG. 18 is a front view of a toothed belt F of a toothed belt F according to an eighth embodiment of the present invention.

FIG. 19 is a diagram showing a canvas setting step according to Embodiment 9 of the present invention.

FIG. 20 is a diagram showing a layout of a belt running tester for noise measurement.

FIG. 21 is a graph showing the relationship between the number of rotations of a pulley and noise.

FIG. 22 is a perspective view of a toothed belt according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tooth rubber part 2 Back rubber part 3 Core wire 4 1st canvas 5 2nd canvas 11 Cylindrical metallic mold 12 1st canvas 13 2nd canvas 14 core wire 15 Unvulcanized rubber sheet 16 Release paper 21 Band 2nd canvas 31 Belt-like canvas 41 Drive pulley 42 Follower pulley 43 Toothed belt 44 Microphone a Tooth rubber part b Back rubber part c Core wire d Canvas

Claims (16)

[Claims] 1. A toothed belt having belt teeth provided at a predetermined pitch in a belt length direction, wherein a core wire extending in the belt length direction and forming a pitch in the belt width direction is provided in a spiral shape. A toothed belt, wherein, in a belt cross section in a belt width direction of a belt tooth bottom portion between the belt teeth, a center of each of a plurality of cores appearing in the belt cross section is not on a straight line. 2. A toothed belt having belt teeth provided at a predetermined pitch in a belt length direction, wherein a spiral core wire extending in the belt length direction and forming a pitch in the belt width direction is provided. In the belt cross section in the belt width direction at the bottom of the belt between the belt teeth, at least one set of the plurality of cores appearing in the belt cross section is located on the belt outer side from the center of each core. A toothed belt, wherein the shortest distance to the surface of the belt tooth bottom is different. 3. A toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, comprising: a core wire extending in the belt length direction and spirally provided with a pitch formed in the belt width direction. A canvas covering the belt surface on the side where the belt teeth are provided, wherein, in a belt cross section in a belt width direction of a bottom portion of the belt tooth between the belt teeth, a plurality of the core wires appearing in the belt cross section are provided. A toothed belt, wherein at least one set of core wires has a different minimum distance from the center of each core wire to the canvas surface on the outer side of the belt. 4. A toothed belt having belt teeth provided at a predetermined pitch in a belt length direction, comprising: a core wire extending in the belt length direction and spirally provided with a pitch formed in the belt width direction. A canvas covering the surface of the belt on the side on which the belt teeth are provided, wherein at the bottom of the belt teeth between the belt teeth, the canvas includes a single portion and a double portion; In the heavy portion, the canvas on the belt body side forms a protruding portion, and on the belt body side at the bottom of the belt teeth, a part of the plurality of core wires is in contact with a single portion of the canvas, and The other part of the toothed belt is in contact with the canvas on the belt body side in the double part of the canvas. 5. A toothed belt having belt teeth provided at a predetermined pitch in the belt length direction, comprising: a core wire extending in the belt length direction and spirally provided with a pitch formed in the belt width direction. A first canvas covering the surface of the belt on which the belt teeth are provided, and a protruding portion formed on the belt body side of the first canvas at the bottom of the belt teeth between the belt teeth and forming a protrusion; A second canvas having a smaller dimension in a belt width direction than a width of the first canvas, wherein a part of the plurality of core wires is in contact with the first canvas on the belt body side of the bottom portion of the belt teeth, and the plurality of cores are provided. The other part of the line is in contact with the second canvas. 6. The toothed belt according to claim 4, wherein the width of the double portion of the canvas in the belt width direction is 5% or more and 50% or less of the belt width. belt. 7. The toothed belt according to claim 5, wherein the width of the second canvas in the belt width direction is 5% of the belt width.
A toothed belt characterized by being at least 50%. 8. A first canvas setting step in which a cylindrical first mold is covered with a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with a cylindrical axis on a peripheral surface; The second canvas is externally fitted at an interval, and the sum of the width of the annular second canvas and the interval between adjacent annular second canvases is set to be equal to or less than the width of the toothed belt to be manufactured. A setting step, a core setting step of spirally winding a core from both the canvases to form a core layer, and an unvulcanized rubber setting step of covering an unvulcanized rubber on the core layer. A vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressurizing. 9. A plurality of annular second canvases are externally fitted on the cylindrical first canvas at intervals, and the width of the annular second canvas and the interval between the adjacent annular second canvases are different from each other. A canvas preparing step of reducing the width of the toothed belt for producing the sum to a value less than or equal to the width of the toothed belt; (1) a canvas setting step of covering the canvas, a core wire setting step of spirally winding a core wire from above both the canvases to form a core layer, and an uncured rubber covering an unvulcanized rubber on the core layer. A method for producing a toothed belt, comprising: a vulcanized rubber setting step; and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing. 10. The method for manufacturing a toothed belt according to claim 8, wherein an integer multiple of the sum of the width of the annular second canvas and the interval between adjacent annular second canvases is manufactured. A method for manufacturing a toothed belt, wherein the width is equal to the width of the toothed belt. 11. A first method in which a cylindrical first canvas is covered on a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with a cylindrical axis on a peripheral surface.
A canvas setting step, and a belt-shaped second canvas is spirally wound around the cylindrical first canvas at intervals, and the width of the belt-shaped second canvas at this time and the interval between the belt-shaped second canvases are adjusted. A second fabric setting step of reducing the width of the toothed belt to be equal to or less than the width of the toothed belt; a core wire setting step of spirally winding a core wire from above both canvases to form a core layer; A method for producing a toothed belt, comprising: an unvulcanized rubber setting step of covering an unvulcanized rubber on a layer; and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing. 12. A belt-shaped second canvas is spirally mounted on a cylindrical first canvas at an interval, and the width of the belt-shaped second canvas and the gap between adjacent belt-shaped second canvases are set. A canvas preparing step of reducing the width of the toothed belt for producing the sum to be less than or equal to the width of the toothed belt; A canvas setting step of covering the canvas, a core wire setting step of spirally winding a core wire from above both the canvases to form a core layer, and an unvulcanized covering of unvulcanized rubber on the core layer A method for producing a toothed belt, comprising: a rubber setting step; and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressurizing. 13. The method for producing a toothed belt according to claim 11, wherein an integral multiple of the sum of the width of the second belt-like canvas and the interval between adjacent second belt-like canvases is produced. A method for manufacturing a toothed belt, wherein the width is substantially equal to the width of the toothed belt. 14. A belt-shaped canvas is spirally wound around a cylindrical mold having a plurality of tooth-shaped grooves extending in parallel with a cylindrical axis while overlapping the belt-shaped canvas at a constant width, and the width of the overlapping portion of the belt-shaped canvas at that time is adjusted. A canvas setting step in which the width of the single part of the belt-like canvas and the width of the double part of the belt-like canvas are set to be equal to or less than the width of the toothed belt to be made smaller than half the width of the belt-like canvas; A core wire setting step of spirally winding a core wire from above the canvas to form a core layer; an unvulcanized rubber setting step of covering the unvulcanized rubber on the core layer; Vulcanizing the unvulcanized rubber by pressure. 15. A belt-shaped canvas is formed by spirally winding a strip-shaped canvas into a cylindrical shape while overlapping the strip-shaped canvas at a constant width, and the width of the overlapping portion of the strip-shaped canvas is made smaller than の of the width of the strip-shaped canvas. A canvas preparation step of making the sum of the width of the single part of the belt-like canvas and the width of the double part of the belt-like canvas less than or equal to the width of the toothed belt; and forming a plurality of tooth-shaped grooves extending parallel to the cylindrical axis. A cloth setting step of covering the cylindrical canvas on a cylindrical mold having a surface; a core setting step of spirally winding a core from above the cylindrical canvas to form a core layer; A method for producing a toothed belt, comprising: an unvulcanized rubber setting step of covering an unvulcanized rubber on a layer; and a vulcanizing step of vulcanizing the unvulcanized rubber by heating and pressing. 16. The method of manufacturing a toothed belt according to claim 14, wherein the band-shaped canvas is an integral multiple of the sum of the width of the single portion and the band-shaped canvas being the width of the double portion. A method of manufacturing a toothed belt, wherein the width of the toothed belt is made substantially equal to the width of the toothed belt.