WO2014091672A1 - Toothed belt - Google Patents

Abstract

A toothed belt (16) is provided with the following: a backing member (24); a plurality of helical teeth (20) arranged in the lengthwise direction of the belt; and a spiral fiber core embedded in the backing member (24) in the lengthwise direction of the belt. The helical teeth (20) have a tooth facing fabric (26) provided on the inside of the belt. The angle between the direction in which the traces of the helical teeth (20) extend and the widthwise direction of the belt is between 8° and 16°, inclusive. The fiber core (22) comprises single strands of thread that are braided in a direction that, in relation to the widthwise direction of the belt, is opposite the direction in which the traces of the helical teeth (20) extend. The fiber core (22) is wrapped in a direction that, in relation to the widthwise direction of the belt, is the same as the direction in which the traces of the helical teeth (20) extend.

Description

Toothed belt

The technology disclosed in this specification relates to a toothed belt having so-called helical teeth.

Toothed belts are used for power transmission in general industrial applications and electric power steering. This toothed belt has a problem that noise is generated when meshing with a pulley during driving.

In response to this problem, the timing belt described in Patent Document 1 attempts to reduce noise by providing so-called helical teeth in which tooth traces are inclined with respect to the belt width direction.

JP-A-10-184808 JP 2004-308702 A JP 2009-014023 A JP 2005-29145 A

According to the examination by the inventors of the present application, it was considered that the noise reduction effect becomes higher as the angle formed by the direction in which the tooth traces of the helical teeth extend and the belt width direction (also referred to as twist angle) is increased. However, as the twist angle is increased, the force that is shifted toward one side in the belt width direction during driving increases, and the pulley flange and the belt side surface come into contact with each other and wear easily. For this reason, if the twist angle is set to a certain level or more, the noise reduction effect is reduced, and the belt is liable to be damaged due to side wear.

This invention is made in view of this point, and it aims at providing the toothed belt which can reduce a noise, without producing a malfunction.

A toothed belt according to an embodiment of the present disclosure includes a back portion made of an elastic body, a plurality of helical teeth provided on the inner peripheral side of the back portion and arranged at a predetermined pitch in the belt length direction, and a belt length. It is a toothed belt provided with a core wire embedded in the back portion spirally along a direction and made of fiber. The helical tooth has a tooth cloth provided on the inner peripheral side, and an angle formed by a direction in which the tooth trace of the helical tooth extends and a belt width direction is 8 degrees or more and 16 degrees or less, and the core wire The fibers constituting the yarn are made of single twisted yarn, and the twist direction of the yarn is inclined in a direction opposite to the direction in which the helical teeth of the helical teeth extend with respect to the belt width direction, and the core wire The winding direction is inclined in the same direction as the direction in which the helical traces of the helical teeth extend with respect to the belt width direction. Here, “the same direction as the direction in which the helical tooth trace extends” does not mean that the winding direction of the core wire and the direction in which the helical tooth extension extends are completely the same direction, This means that the winding direction of the core wire and the inclination direction (downward to the left or downward) in the direction in which the tooth traces of the helical teeth extend in the width direction are the same.

With this configuration, even if the angle formed by the direction in which the tooth traces of the helical teeth extend and the belt width direction is increased, the offset force acting in the belt width direction can be offset, so the belt side surface can be damaged while reducing noise. Can be suppressed.

The toothed belt according to an embodiment of the present disclosure can reduce noise while preventing damage to the belt.

FIG. 1 is a perspective view illustrating a part of a toothed belt according to an embodiment of the present disclosure. Fig.2 (a) is a side view which shows a part of toothed belt which concerns on one Embodiment of this indication, (b) is a top view at the time of seeing a part of toothed belt from a helical tooth side. It is. FIG. 3 shows the direction in which the tooth traces of the helical teeth extend, the spiral direction (winding direction) of the core wire, the twist direction of the yarn constituting the core wire, and the teeth when a part of the toothed belt is viewed from the helical tooth side. It is a top view which shows the cross-hair direction of cloth. FIG. 4A is a diagram illustrating a cross section taken along line IVa-IVa of FIG. 2A of a toothed belt according to an embodiment of the present disclosure, and FIG. 4B is a toothed belt in the belt length direction. It is a figure which expands and shows the cross section of a belt. Fig.5 (a) is a figure which shows the result of a noise measurement test, (b) is the schematic which shows the noise measurement method. FIG. 6A is a diagram showing the results of the durability test, and FIG. 6B is a diagram schematically showing an apparatus used for the durability test. FIG. 7A is a diagram showing the results of the belt offset test, and FIG. 7B is a diagram schematically showing an apparatus used for the belt offset test. FIG. 8 is a diagram showing the result of the belt deviation test when the twist angle of the lotus teeth is made constant. FIG. 9 is a diagram showing the measurement results when the helical angle of the tooth cloth is changed after the twist angle of the helical teeth is made constant and the configuration of the core wire is aligned by SZ winding.

-Configuration of toothed belt-
Hereinafter, the configuration of the toothed belt according to the embodiment of the present disclosure will be described with reference to the drawings.

FIG. 1 is a perspective view showing a part of a toothed belt according to the present embodiment. As shown in the figure, the toothed belt 16 of this embodiment includes a back portion 24 made of an elastic body, and a plurality of helical teeth provided on the inner peripheral side of the back portion 24 and arranged at a predetermined pitch in the belt length direction. 20 and a core wire 22 embedded in the back portion 24 in a spiral shape along the belt length direction and made of fiber. The plurality of helical teeth 20 includes a tooth rubber 28 and a tooth cloth 26 which is provided on the inner peripheral side and is made of, for example, a twill cloth.

FIG. 2A is a side view showing a part of the toothed belt 16 according to the embodiment of the present disclosure, and FIG. 2B shows a part of the toothed belt 16 on the helical tooth 20 side (inner peripheral side). It is a top view at the time of seeing from. The direction in which the tooth trace of the helical tooth 20 extends may be inclined with respect to the belt width direction, but in FIGS. 2 (a) and 2 (b), the tooth trace of the helical tooth 20 has the belt traveling direction as the upward direction. An example of rising to the right is shown. 3 shows a direction 1 in which the tooth trace of the helical tooth 20 extends when a part of the toothed belt 16 is viewed from the helical tooth 20 side, a spiral direction (winding direction) 3 of the core wire 22, and a core wire 22. It is a top view which shows the twist direction 5 of the thread | yarn to comprise, and the cross direction 7 of the tooth cloth 26. FIG. 4A is a diagram illustrating a cross-section of the toothed belt 16 according to an embodiment of the present disclosure, taken along line IVa-IVa illustrated in FIG. 2A, and FIG. 4B is a diagram illustrating teeth in the belt length direction. It is a figure which expands and shows the cross section of the attached belt.

It is preferable that the angle θ formed by the direction 1 in which the teeth of the helical teeth 20 extend and the belt width direction is 8 degrees or more and 16 degrees or less. Further, it is more preferable that the angle θ is 9 degrees or more and 15 degrees or less.

The fiber constituting the core wire 22 is made of a single twisted yarn, and the twisting direction 5 of the yarn is inclined in the direction opposite to the direction 1 in which the tooth traces of the helical teeth 20 extend with respect to the belt width direction. . When the tooth trace of the lotus tooth 20 is rising to the right, the yarn is S-twisted (or SS twisted when there are two yarns).

The winding direction 3 of the core wire 22 is inclined in the same direction as the direction 1 in which the helical teeth of the helical teeth extend with respect to the belt width direction. In the example shown in FIG. 3, the winding direction 3 of the core wire 22 is rising to the right with respect to the belt width direction. Here, depending on the angle θ formed by the direction 1 in which the tooth trace of the helical tooth 20 extends and the belt width direction, the number of threads constituting the core 22 is changed from two to one, or the winding pitch of the core 22 It is also possible to make adjustments such as changing the diameter or changing the diameter of the core wire 22.

The cross stitch direction 7 of the tooth cloth 26 is inclined in the direction opposite to the direction 1 in which the tooth traces of the helical teeth 20 extend with respect to the belt width direction. In the example shown in FIG. 3, the crosswise direction 7 of the tooth cloth 26 is inclined downward (in other words, upward to the left) with respect to the belt width direction.

The pitch P of the lotus teeth 20 (see FIG. 2A) is not particularly limited, but is preferably 3 mm or less. The belt width W (see FIG. 2B) is not particularly limited, but is preferably 15 mm or more. The toothed belt 16 has an endless ring shape, and the circumferential length is, for example, about 300 mm to 400 mm.

The thickness t of the toothed belt 16 is, for example, about 1.0 mm to 2.6 mm, and the thickness tb of the back portion 24 is, for example, about 0.2 mm to 1.85 mm. The tooth height hb of the helical tooth 20 is, for example, about 0.5 mm to 1.2 mm. The width Wt of the helical teeth 20 in the belt length direction is, for example, about 1.0 mm to 2.0 mm.

As a constituent material of the back portion 24 and the tooth rubber 28, for example, a rubber that can withstand a low temperature of about −40 ° C. to a high temperature of about 120 ° C. is used, and hydrogenated nitrile rubber (HNBR) is preferably used. In addition, chloroprene rubber (CR), ethylene-propylene-diene rubber (EPDM), styrene butadiene rubber, epichlorohydrin rubber, polyurethane rubber, or the like may be used as the constituent material of the back portion 24 and the tooth rubber 28. These rubbers may be blended with known reinforcing fibers and additives.

For the core wire 22, a material having high elasticity is preferably used, and for example, glass fiber is preferably used. An aramid fiber or the like may be used as the core wire 22.

As the material for the tooth cloth 26, for example, nylon fiber or nylon fiber added with aramid fiber is preferably used. The thickness of the tooth cloth 26 is, for example, about 0.1 mm to 0.3 mm. As a material for the tooth cloth 26, nylon fibers such as 6,6-nylon and 4,6-nylon, aramid fibers, polyparaphenylene benzobisoxazole (PBO) fibers, and the like can be used.

The toothed belt 16 of this embodiment transmits power by being wound between a driving pulley and a driven pulley in which a helical tooth meshing with the helical tooth 20 is formed. The toothed belt 16 is used, for example, in an electric power steering (EPS) device.

For example, in the case of an exemplary electric power steering apparatus (not shown), when the handle is operated, the rotation is transmitted to the input shaft, and the rotation is transmitted to the pinion through this while twisting the torsion bar. . When the rotation of the pinion is transmitted to the rack shaft, the rack shaft moves in the axial direction. If the torsion amount of the torsion bar is detected by the torque detection device, the output signal of the torque detection device is input to the control device, and the control device rotates the assist motor. The rotational force of the assist motor is transmitted from the driving pulley to the toothed belt 16 and the driven pulley. By this operation, the handle operation is assisted by the assist motor.

-Action and effect of toothed belt according to an example of the present disclosure-
According to the toothed belt 16 of the present embodiment, the angle θ formed by the direction in which the tooth trace of the helical tooth 20 extends and the belt width direction is 8 degrees or more. Are successively and smoothly advanced from one end of the tooth to the other end. Therefore, noise generated when the helical teeth of the pulley and the helical teeth 20 of the toothed belt 16 are engaged can be reduced. On the other hand, by setting the angle θ formed by the direction in which the tooth trace of the helical tooth 20 extends and the belt width direction to 16 degrees or less, the thrust force (deviation force) generated by the helical tooth 20 is suppressed to an adjustable range. Can do.

Further, if the angle θ formed by the direction in which the teeth of the helical teeth 20 extend and the belt width direction is 9 degrees or more and 15 degrees or less, the thrust force can be more easily canceled while the noise reduction effect is maintained at a high level. This is preferable because the durability of the toothed belt 16 can be further improved.

Further, in the toothed belt 16 of the present embodiment, the fibers constituting the core wire 22 are made of single-twisted yarns, and the twisted direction of the yarns of the helical teeth 20 extends with respect to the belt width direction. It is tilted in the opposite direction. For this reason, when the toothed belt 16 rotates, a thrust force in a direction opposite to the thrust force (shift force) generated by the helical teeth 20 can be generated. As a result, the thrust force generated by the helical teeth 20 can be offset, and the flange of the pulley and the side surface of the toothed belt 16 can be made difficult to contact. For this reason, in the toothed belt 16 of this embodiment, even when the inclination of the tooth trace of the helical tooth 20 is increased, side surface wear is less likely to occur, and the effect of rubbing between the belt side surface and the flange is effective. Can be reduced.

Furthermore, in the toothed belt 16 of the present embodiment, the winding direction of the core wire 22 is inclined in the same direction as the direction in which the tooth traces of the helical teeth 20 extend with respect to the belt width direction. This also makes it possible to generate a thrust force in a direction opposite to the thrust force generated by the helical teeth 20 when the toothed belt 16 rotates. As a result, the thrust force generated by the helical teeth 20 can be offset, and the flange of the pulley and the side surface of the toothed belt 16 can be made difficult to contact.

Further, in the toothed belt 16 of the present embodiment, the cross direction of the tooth cloth 26 is inclined in the direction opposite to the direction in which the tooth traces of the helical teeth 20 extend with respect to the belt width direction. According to this configuration, it is possible to generate a thrust force in a direction opposite to the thrust force generated by the helical teeth 20 when the toothed belt 16 rotates. As a result, the thrust force generated by the helical teeth 20 can be offset, and the flange of the pulley and the side surface of the toothed belt 16 can be made difficult to contact.

In particular, the greater the angle formed between the crosswise direction of the tooth cloth 26 and the belt width direction, the greater the thrust force by the tooth cloth 26. Therefore, the angle in the crosswise direction is set according to the direction in which the tooth trace of the helical tooth 20 extends. By appropriately adjusting, it is possible to cancel out the force of the belt being offset.

As described above, in the toothed belt 16 according to the present embodiment, the twist direction of the yarn constituting the core wire 22, the winding direction of the core wire 22, and the cross direction of the tooth cloth 26 are appropriately set according to the inclination of the helical tooth 20. By adjusting, it is difficult to cause breakage while reducing noise during driving.

The toothed belt 16 described above is an example of the embodiment, and the constituent material, belt shape, size, and the like can be appropriately changed without departing from the gist of the present invention. For example, when the direction in which the helical teeth 20 are inclined is reversed, the noise can be reduced by reversing the winding direction of the core wire 22, the twisting direction of the yarn, and the cross direction of the tooth cloth 26 with respect to the toothed belt 16, respectively. However, it is possible to effectively prevent the belt from being damaged.

Further, depending on the inclination of the helical teeth 20, any one of the winding direction of the core wire 22, the twisting direction of the yarn, and the crosswise direction of the tooth cloth 26 is reversed from the toothed belt 16 of the present embodiment. Is also possible.

-Manufacturing method of toothed belt-
Next, an example of a method for manufacturing the toothed belt 16 will be described. In this manufacturing method, a cylindrical mold and a vulcanizing can capable of being fitted therein are used. In addition, grooves for forming a plurality of helical teeth 20 are provided on the outer peripheral surface of the cylindrical mold at equal pitches in the circumferential direction so as to extend with an inclination angle θ with respect to the axial direction.

First, a fiber material such as nylon to be used as the tooth cloth 26 is prepared, and a process of applying a rubber paste on one side using a knife coater or a roll coater is performed. And a fiber material is shape | molded in a cylindrical shape so that it may arrange | position so that the surface which apply | coated the rubber paste which consists of HNBR etc. may become an outer side.

Separately, a non-crosslinked rubber sheet for forming the back portion 24 of the toothed belt 16 and a glass fiber twisted yarn for forming the core wire 22 are prepared. As the twisted yarn, an S-twisted yarn is used when the formed tooth trace of the helical tooth 20 rises to the right, and a Z-twisted yarn is used when the helical stripe of the helical tooth 20 falls downward.

Next, a fiber material is put on a cylindrical mold, and a twisted yarn is wound in a spiral shape at an equal pitch from above. At this time, the winding direction of the core wire 22 is inclined in the same direction as the direction in which the tooth traces of the helical teeth 20 extend with respect to the belt width direction. Further, an unvulcanized rubber composition sheet is wound thereon. At this time, the fiber material, the twisted yarn, and the uncrosslinked rubber sheet are set in layers on the cylindrical mold peripheral surface in this order from the mold side.

Next, the cylindrical mold set with the material is put into a vulcanizing can, and a predetermined temperature and pressure are applied. At this time, the unvulcanized rubber composition flows and is pressed into the groove provided in the cylindrical mold so as to press the canvas, whereby the lotus teeth 20 are formed.

Finally, the cylindrical belt precursor formed on the peripheral surface is removed from the cylindrical mold taken out from the vulcanization can, and the toothed belt 16 is obtained by cutting it into a predetermined width.

In addition, the manufacturing method of the toothed belt 16 is not limited to the above method, and may be appropriately replaced by other methods.

-Configuration of toothed belt-
Hereinafter, the results of various tests performed on the toothed belt will be described. Here, in the toothed belt according to each of the examples and comparative examples, the back, the tooth rubber, the core wire, and the material constituting the tooth cloth are the same, the tooth pitch of the helical tooth is 2 mm, and the tooth height is Toothed belts having the following parameters were prepared after setting to 1.31 mm. However, the twist direction of the yarn constituting the core wire was appropriately changed. Tables 1 and 2 summarize the configurations of the toothed belts according to Examples and Comparative Examples. Further, the durability test test described later is performed using a toothed belt having a width of 6 mm manufactured by the same method.

(Example 1)
As shown in Table 2, the torsion angle of the right rising helical teeth is set to 8 degrees, and the twill of the tooth cloth is raised to the left and the twill angle (that is, the angle formed by the belt width direction and the twill direction) is 41. The winding direction of the core wire was raised to the right. Both cores consisted of two S-twisted yarns.

The toothed belts according to Examples 1 to 4 and the following comparative examples were produced by the method described above. HNBR was used as the constituent material of the back of the toothed belt and the tooth rubber, and glass fiber was used as the core wire. As a tooth cloth, a cloth using 66 nylon as warp and weft was used. Further, in the toothed belts according to Examples 1 to 4 and the following comparative example, the belt width was 24 mm, and the circumferential length of the belt was 332 mm.

(Example 2)
As shown in Table 2, the torsion angle of the right rising helical teeth was set to 9 degrees, the twill of the tooth cloth was increased to the left, and the twill angle was set to 41 degrees. The winding direction of the core wire was raised to the right, and the core wire was composed of two S-twisted yarns.

(Example 3)
As shown in Table 2, the torsion angle of the right rising helical teeth was set to 12 degrees, the twill of the tooth cloth was increased to the left, and the twill angle was set to 41 degrees. The winding direction of the core wire was raised to the right, and the core wire was composed of two S-twisted yarns.

Example 4
As shown in Table 2, the torsion angle of the right rising lotus teeth was set to 15 degrees, the twill of the tooth cloth was increased to the left, and the twill angle was set to 41 degrees. The winding direction of the core wire was raised to the right, and the core wire was composed of two S-twisted yarns.

(Example 5)
As shown in Table 2, the torsion angle of the right rising helical teeth was set to 16 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 41 degrees, and the winding direction of the core wire was increased to the right. Both cores consisted of two S-twisted yarns.

(Comparative Example 1)
As shown in Table 1, the toothed belt according to Comparative Example 1 had straight teeth, the tooth cloth's twill was raised to the left and the twill angle was 41 degrees. The winding direction of the core wire was raised to the right, and the core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 2)
As shown in Table 1, the torsion angle of the right rising helical teeth was set to 5 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 41 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 3)
As shown in Table 1, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 31 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 4)
As shown in Table 1, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 36 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 5)
As shown in Table 1, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 41 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 6)
As shown in Table 1, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 46 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 7)
As shown in Table 1, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 51 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

(Comparative Example 8)
As shown in Table 2, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 41 degrees, and the winding direction of the core wire was increased to the right. Both cores consisted of two S-twisted yarns.

(Comparative Example 9)
As shown in Table 2, the torsion angle of the right rising helical teeth was set to 7 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 41 degrees, and the winding direction of the core wire was increased to the right. Both cores consisted of two Z-twisted yarns.

(Comparative Example 10)
As shown in Table 2, the torsion angle of the right rising lotus teeth was set to 9 degrees, the twill of the tooth cloth was increased to the left and the twill angle was set to 41 degrees, and the winding direction of the core wire was increased to the right. The core wire was composed of S-twisted yarn and Z-twisted yarn.

-Noise measurement method-
FIG. 5B is a schematic diagram illustrating a noise measurement method.

The belt to be evaluated was wrapped around the biaxial pulley of the driving pulley 33 and the driven pulley 31, and the noise level when the rotational speed of the driving pulley 33 was changed from 1000 rpm to 5000 rpm was measured. The number of teeth of the driving pulley 33 was 45, the number of teeth of the driven pulley 31 was 138, and the tooth pitch of each pulley was 2 mm. The diameters of the driving pulley and the driven pulley were 28.14 mm and 87.35 mm, respectively. The twist angle of the teeth of each pulley was the same as that of the belt to be evaluated. The belt tension was 100 N, and the noise level was measured using a precision sound level meter (product name: LA-5560, manufactured by Ono Sokki Co., Ltd.). The sound collecting microphone was installed at a position 30 mm laterally (belt width direction) from the belt end face and 20 mm away from the center of the driving pulley toward the center of the driven pulley. Measurement was performed at 1000 rpm to 5000 rpm for each belt at 300 to 400 points, and an average value of the measurement results at the 300 to 400 points was taken.

-Durability test-
FIG. 6B is a diagram schematically showing an apparatus used for the durability test.

The belt to be evaluated was wound around the biaxial pulley of the driving pulley 35 and the driven pulley 37, and the rotational speed of the driving pulley 35 was set to 1800 rpm. At this time, the time until a crack having a length of 1/2 or more of the tooth width occurred was measured. Both the drive pulley 35 and the driven pulley 37 have 45 teeth, and the tooth pitch is 2 mm. Both the driving pulley 35 and the driven pulley 37 had a diameter of 28.14 mm. The twist angle of the teeth of each pulley was the same as that of the belt to be evaluated. The initial belt tension was 80N. This measurement was performed in an environment of 125 ° C.

-Belt offset test-
FIG. 7B is a diagram schematically showing an apparatus used for the belt deviation test.

The belt to be evaluated was wound around the biaxial pulley of the driving pulley 41 and the driven pulley 39, and the rotational speed of the driving pulley 41 was set to 1000 rpm. The force in the belt width direction (belt shift force) generated at this time was measured by the sensor 43.

The drive pulley 41 has 45 teeth, the driven pulley 39 has 138 teeth, and each pulley has a tooth pitch of 2 mm. The diameters of the driving pulley and the driven pulley were 28.14 mm and 87.35 mm, respectively. The twist angle of the teeth of each pulley was the same as that of the belt to be evaluated.

-Test results-
FIG. 5A shows the result of the noise measurement test. From the results shown in the figure, it has been found that the noise level decreases as the helical angle of the helical teeth increases in the range where the helical angle of the helical teeth ranges from 0 degrees to 7 degrees (Comparative Examples 1, 2, and 5). However, when the core wire is SZ winding, even if the helical angle of the helical tooth is 9 degrees, the noise level is the same as when the helical angle is 7 degrees, and the noise level cannot be reduced (Comparative Examples 5 and 10). ). This was presumed to be because when the torsion angle of the helical tooth becomes too large, the belt is displaced and the belt and the flange are rubbed to generate noise.

On the other hand, it was confirmed that when the core wire was wound with SS (Example 2), the noise level could be greatly reduced even with the same helical twist angle. It was confirmed that the noise level could be reduced even when the helical angle of the helical teeth was 8 degrees (Example 1). Further, it was confirmed that when the core wire was made of SS winding, the noise level could be kept low within the range where the helical angle of the helical tooth was 16 degrees or less (Examples 2, 3 and 5).

FIG. 6 (a) shows the results of the durability test. From the results shown in the figure, it was found that the durability of the belt gradually decreased as the helical angle of the helical teeth increased.

This is considered to be because the belt side surface is strongly pressed against the flange as the helical angle of the helical teeth increases, and the belt temperature rises, resulting in belt chipping. From the results of Comparative Examples 2, 5, and 10, when the core wire is wound in SZ, the belt side surface rubs against the flange when the helical angle of the helical teeth is 9 degrees or more, and the belt durability is remarkably increased. It turns out that it falls.

In contrast, it was confirmed that the durability of the belt could be greatly improved when the core wire was wound with SS even when the helical angle of the helical teeth was 9 degrees. This is presumably because the thrust force (deviation force) generated by the core wire cancels out the thrust force generated by the helical teeth. From the results of Examples 1 to 3, sufficient durability is maintained when the twist angle of the lotus tooth is 9 degrees or more and 16 degrees or less. However, when the twist angle of the lotus tooth exceeds 16 degrees, the durability time is greatly increased. (Example 5). Even if the core wire is wound with SS, if the helical angle of the helical tooth exceeds 16 degrees, it is considered that the thrust force generated by the helical tooth cannot be offset. It has also been confirmed that the durability time can be further improved if the helical angle of the helical teeth is 15 degrees or less.

FIG. 7A is a diagram showing the result of the belt offset test. Here, when the core wire is SZ winding and the torsion angle of the helical teeth is 0 degree, 5 degrees, 7 degrees, and 9 degrees (Comparative Examples 1, 2, 5, and 10), the core wire is SS winding. The result when the twist angle of the helical tooth is 9 degrees (Example 1) is shown.

From the results shown in the figure, as the torsion angle of the helical teeth increases, the offset force of the belt also increases, and the twisting direction of the yarn constituting the core is inclined in the direction opposite to the helical teeth, and the winding direction of the core is changed. It was confirmed that the belt offset force could be offset by tilting in the same direction as the helical teeth.

FIG. 8 is a diagram showing the result of the belt offset test when the torsion angle of the lotus tooth is made constant. In the same figure, the measurement result of the comparative example 9 which has a core wire of ZZ winding, the comparative example 5 which has a core wire of SZ winding, and the comparative example 8 which has a core wire of SS winding is shown. From this result, when the two yarns constituting the core wire are both Z-twisted, the offset force in the same direction as the offset force generated by the helical teeth is generated, and the two yarns constituting the core wire It was confirmed that when both were twisted with S twist, an offset force in the direction opposite to the offset force generated by the helical teeth was generated.

FIG. 9 is a diagram showing a measurement result when the twist angle of the lotus teeth is made constant and the configuration of the core wire is aligned by SZ winding and the twill angle of the tooth cloth is changed. In the figure, the measurement results of Comparative Examples 3, 4, 6, and 7 are shown. From this result, it was confirmed that the offset force increases as the twill angle increases. Accordingly, if the crosswise direction of the tooth cloth is inclined in the direction opposite to the direction in which the helical traces of the helical teeth extend, the offset force generated by the helical teeth can be offset by appropriately adjusting the crosswise angle. It is considered possible.

As described above, the toothed belt according to the present disclosure is used for power transmission in various devices including power steering for automobiles.

16 toothed belt 20 helical tooth 22 core wire 24 back part 26 tooth cloth 28 tooth rubber 31, 37, 39 driven pulley 33, 35, 41 driven pulley 43 sensor

Claims (6)

A back part made of an elastic body;
A plurality of helical teeth provided on the inner peripheral side of the back portion and arranged at a predetermined pitch in the belt length direction;
A toothed belt provided with a core wire embedded in the back portion in a spiral shape along the belt length direction and made of fiber,
The lotus tooth has a tooth cloth provided on the inner peripheral side,
The angle formed by the direction in which the tooth trace of the helical tooth extends and the belt width direction is 8 degrees or more and 16 degrees or less,
The fiber constituting the core wire is made of a single-twisted yarn, and the twist direction of the yarn is inclined in a direction opposite to the direction in which the helical teeth of the helical teeth extend with respect to the belt width direction.
The toothed belt in which the winding direction of the core wire is inclined in the same direction as the direction in which the tooth trace of the helical tooth extends with respect to the belt width direction. The toothed belt according to claim 1,
The tooth cloth is composed of a twill cloth,
The toothed belt characterized in that the crosswise direction of the tooth cloth is inclined in the direction opposite to the direction in which the tooth traces of the helical teeth extend with respect to the belt width direction. The toothed belt according to claim 1 or 2,
The toothed belt, wherein an angle formed by a direction in which the tooth trace of the helical tooth extends and a belt width direction is 9 degrees or more and 15 degrees or less. The toothed belt according to any one of claims 1 to 3,
A toothed belt, wherein a plurality of the helical teeth arranged has a pitch of 3 mm or less. The toothed belt according to any one of claims 1 to 4,
A toothed belt having a belt width of 15 mm or more. The toothed belt according to any one of claims 1 to 5,
A toothed belt used for electric power steering.

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