CN120303497A

CN120303497A - Synchronous transmission belt and assembly comprising the belt and associated pulleys

Info

Publication number: CN120303497A
Application number: CN202380083533.8A
Authority: CN
Inventors: 埃尔韦·瓦林
Original assignee: Hutchinson SA
Current assignee: Hutchinson SA
Priority date: 2022-12-08
Filing date: 2023-12-07
Publication date: 2025-07-11
Also published as: EP4630704A1; FR3143077A1; WO2024121319A1; FR3143077B1

Abstract

The timing belt (100) has an elastomeric-based body (102) comprising an assembly of a back side portion (104), a side portion (106), and a tensile cord (110) between the back side portion (104) and the side portion (106), the side portion having a plurality of transverse teeth (112, 112 '), each transverse tooth (112, 112 ') having a first profile (116) in cross section with two inclined sides (117) connected by at least one rounded portion, each transverse tooth having a tooth height H1, and a plurality of longitudinal teeth (114, 114 '), each longitudinal tooth extending substantially perpendicular to the transverse tooth between the two transverse teeth, and each longitudinal tooth having a second profile (118) in cross section with two inclined sides (119) connected by at least one rounded portion, each longitudinal tooth having a non-zero tooth height H2 that is less than or equal to tooth height H1.

Description

Synchronous drive belt and assembly comprising such a belt and associated pulley

Technical Field

The invention relates to a synchronous transmission belt. The invention also relates to an assembly comprising a belt and at least one associated pulley. The invention also relates to a method of manufacturing such a belt.

Background

In general, power transmission by belts is very common and covers a wide range of applications, such as the automotive industry, the transmission of objects or bicycles (commonly referred to as bicycles).

Some applications require the transmission of very high torque. Not all types of belts (e.g.,I.e. ridged in the longitudinal direction of the belt) must possess the level of performance required for such applications. A synchronous system is preferred, i.e. a synchronous belt with transverse teeth and corresponding pulleys is preferred. This is especially true for bicycle applications.

However, these synchronous drive systems require that the axes of rotation be perfectly parallel and that the pulleys be properly aligned. Otherwise, there is a risk that the belt moves laterally over the pulley, resulting in damage and/or the belt falling off the pulley.

To avoid these lateral movements, it may be useful for the drive train to comprise guiding means. Some solutions involve providing flexible elements (flasques) on pulleys on both sides of the belt. However, the belt tends to rub against these elements, thereby accelerating wear and preventing the discharge of foreign objects such as water or gravel.

Other solutions propose to machine the teeth of the synchronous belt centrally, defining a groove to be placed on a corresponding web of material provided in the centre of the pulley with which the belt cooperates. This is proposed, for example, in the document EP-B1-3 478 561.

However, this principle has limitations in the design of the pulley and in the machining of the teeth of the belt. Furthermore, the grooves formed in the belt by such machining may be damaged by the entry of foreign matter during operation. When such a system is used in a bicycle application, these foreign bodies may be mud or gravel, for example.

Other solutions are contrary to the first one, i.e. the belt comprises, in addition to the synchronizing teeth, at least one web engaging in a groove provided in the corresponding pulley. This arrangement is proposed in particular in document WO-A1-2021/180678.

Furthermore, documents EP-B1-3 478 561 and WO-A1-2021/180678 each propose a synchronous belt whose transverse teeth each have a rounded top, in particular with an overall arcuate profile. The web only acts as a lateral stop for the belt, either positive (on the pulley) or negative (on the belt).

The document CN-U-208 651 535 proposes a synchronous belt whose transverse teeth all have a right trapezoid profile. The document also proposes V-shaped longitudinal teeth between the individual transverse teeth.

In general, in order to maximize torque transmission between two pulleys, the belt must be placed on the pulley with as large a contact surface as possible, while limiting mechanical stresses associated with, in particular, belt winding and tooth shape.

This stress contributes to the deformation of the teeth of the belt and even to the appearance of cracks, in particular at the tooth root, which accelerates the degradation of the belt.

Another object of the present invention is to provide a synchronous drive belt that does not have at least one of the above-mentioned drawbacks.

It is a further object of the present invention to provide a synchronous drive belt having improved performance in terms of torque transmitted between two pulleys.

Disclosure of Invention

Thus, a synchronous drive belt is proposed, comprising an elastomer-based body comprising an assembly of a back-side portion, a flank portion and a tensile cord between the back-side portion and the flank portion, the flank portion having on the one hand a plurality of transverse teeth, each transverse tooth having a first profile in cross section, the first profile having two inclined sides converging towards each other in the top direction of the transverse tooth, the sides of the transverse teeth being connected by at least one rounded portion, each transverse tooth having a tooth height H1, and the flank portion having on the other hand a plurality of longitudinal teeth, each longitudinal tooth extending substantially perpendicular to the transverse tooth between the two transverse teeth and having in cross section a second profile, the sides of the longitudinal teeth being connected by at least one rounded portion, the longitudinal teeth having a height H2, the non-zero height H2 being smaller than or equal to the tooth height H1.

The invention thus ensures an improvement in the torque that can be transmitted by the belt and its stability. In fact, in use, the contact surface between the belt and the pulley configured to receive the belt is high due to the profile of the teeth, in particular due to the longitudinal teeth which not only have the function of guiding the belt on the pulley, but also, by the shape of their profile, participate in the transmission of torque together with the transverse teeth. The presence of the cords increases the tensile modulus of the belt and thus allows control of the transmissible torque.

According to the invention, the belt may comprise one or more of the following features, which may be used alone or in combination with each other:

The non-zero tooth height H2 of each longitudinal tooth is strictly smaller than the tooth height H1 of each transverse tooth,

The tooth height H2 of each longitudinal tooth is 0.4XH21≤H2≤0.8XH2,

Each transverse tooth has in cross section a trapezoidal profile with rounded corners,

The first profile of each transverse tooth comprises two convex top portions, which are located on either side of the top portion, and two concave portions, which are located on either side of the base of the transverse tooth,

Each male top portion of the first profile has an approximate radius of curvature of between 0.6mm and 1.4mm, and each female portion has a radius of curvature of between 0.6mm and 1.4mm,

The second profile of each longitudinal tooth comprises two concave portions, which are located on either side of the base of the longitudinal tooth, and a tooth tip, which is convex,

Each concave portion of the second profile has a radius of curvature between 0.8mm and 1.6mm, and the top of the second profile has a radius of curvature between 0.8mm and 1.6mm,

The second profile of each longitudinal tooth is a trapezoidal profile with rounded corners,

The timing belt comprises a coating arranged at the level of the outer surfaces of the plurality of transverse teeth and the plurality of longitudinal teeth,

The elastomeric-based body of the belt is made of a material selected from ethylene-alpha-olefins or polyurethanes, and the coating is a textile material or an elastomeric thermoplastic film,

Each cord of the assembly of drawn cords is made of aramid, polyester, glass or carbon fibers or a combination thereof,

The transverse teeth are distributed at a pitch of 11 mm.

The invention also relates to an assembly comprising at least one pulley and a synchronous drive belt as described above, each pulley comprising:

-two rows of circumferential teeth parallel to each other and configured to receive a tooth recess of a plurality of transverse teeth of the belt, and

-A circumferential groove separating the two rows of circumferential teeth, the circumferential groove being configured to receive a plurality of longitudinal teeth of the belt.

According to the invention, the assembly may comprise one or more of the following features, which may be used alone or in combination with each other:

The assembly comprises a first pulley having a given size and a second pulley having a size different from the size of the first pulley,

The assembly comprises the same first pulley and second pulley,

Each row of circumferential teeth comprises tooth recesses, the depth P1 of which is greater than the height H1 of the transverse teeth of the belt,

The depth P2 of the longitudinal grooves is greater than the height H2 of the longitudinal teeth of the belt,

Each pulley is made of a material selected from steel, aluminum or plastic.

The invention also relates to a method of manufacturing a synchronous drive belt as described above, comprising the steps of:

-forming a strip blank from the strip material around a cylindrical mandrel;

-removing the blank from the mandrel;

-inserting the blank into a cylindrical mould comprising on the inner cylindrical wall a female pattern of transverse and longitudinal teeth to be formed on the belt;

-pressing the blank against the mould by means of an expandable rubber bladder and heating the mould in order to vulcanize the tape blank;

demolding the vulcanized blank, and

-Cutting the vulcanized blank so as to form a tape.

Drawings

The invention will be better understood by means of the following description, which is given by way of example only and with reference to the accompanying drawings, in which:

Figure 1 shows a partially schematic perspective view of a belt according to the invention,

Figure 2 shows a schematic cross-section of the belt shown in figure 1,

Figure 3 shows a schematic cross-section of another embodiment of a synchronous drive belt according to the invention,

Figure 4 shows a schematic cross-sectional view of the belt of figure 1,

Figure 5 shows a schematic cross-sectional view of another embodiment of a synchronous drive belt according to the invention,

Fig. 6 shows a schematic view of a step in the method of manufacturing a belt according to the invention, in particular positioning the belt blank in a mould,

Figure 7 shows a schematic view in longitudinal section of a detail of a step of the method in figure 6,

Fig. 8 shows a schematic view of another step in the method of manufacturing a belt according to the invention, in particular positioning an inflatable bladder inside a blank,

Figure 9 shows a schematic view in longitudinal section of a detail of a step of the method in figure 8,

Fig. 10 shows a schematic view of another step in the method of manufacturing a belt according to the invention, in particular printing a mould pattern on a blank,

Figure 11 shows a schematic view in longitudinal section of a detail of a step of the method in figure 10,

Fig. 12 shows a schematic view of another step in the method of manufacturing a belt according to the invention, in particular with the molded blank removed,

Figure 13 shows a schematic drawing of a tensile strength test of a belt according to the invention,

Fig. 14 shows a schematic perspective view of an assembly according to the invention comprising at least one pulley and a timing belt.

FIG. 15 is a schematic side view of the assembly shown in FIG. 14, and

Fig. 16 shows a schematic cross-sectional view of the assembly shown in fig. 14.

Detailed Description

Fig. 1 shows a perspective view of an embodiment of a timing belt 100 according to the present invention.

The timing belt 100 includes an assembly of tensile cords 110 and an elastomer-based body 102.

The elastomer-based body 102 includes a backside portion 104. The elastomer-based body 102 also includes a ventral portion 106 formed from a plurality of teeth 112, 112', 114'. The plurality of teeth 112, 112', 114' includes a plurality of transverse teeth 112, 112 'on the one hand and a plurality of longitudinal teeth 114, 114' on the other hand. The plurality of transverse teeth 112, 112 'and the plurality of longitudinal teeth 114, 114' each include an outer surface configured to at least partially mate with a tooth recess of a pulley.

Each transverse tooth 112, 112' also has, in cross section, a first profile 116 with two inclined sides 117 converging towards each other in the direction of the top of the tooth, these two sides 117 also being connected at the level of the top by at least one rounded portion.

By "rounded" is meant that the first profile 116 of the transverse teeth 112, 112' has a shape defining at least one curvature.

In one embodiment, as shown in fig. 2-4, the first profile 116 may be trapezoidal with rounded corners.

"Trapezoidal" is understood to mean that the first profile 116 of the transverse teeth 112, 112' has a trapezoidal shape, i.e. a deformed trapezoid or trapezoid. Thus, the top of each transverse tooth 112, 112 'defines a non-zero sized top portion 116a that is parallel or non-parallel to an imaginary base 116b (shown in phantom in fig. 2) of the transverse tooth 112, 112' that is itself parallel to the back portion 104 of the belt 100. In other words, the top of each transverse tooth 112, 112' defines a non-zero sized top portion 116a that is parallel or non-parallel to the back portion 104 of the belt 100. It should be appreciated that the back portion 104 of the strap 100 is substantially flat and the top portion 116a is also substantially flat.

"Rounded" is understood to mean that the first profile 116 of the transverse teeth 112, 112 'comprises, on the one hand, at least one angle describing a convex curvature at the level of the top of the transverse teeth 112, 112', referred to as convex top portion 116c, and/or, on the other hand, at least one angle describing a concave curvature at the level of the tooth recess 120, referred to as concave portion 116d.

In other words, the first profile 116 of the transverse teeth 112, 112' advantageously comprises a substantially flat top portion 116a of the teeth, at least one convex top portion 116c and at least one concave portion 116d of the bottom tooth recess 120.

Typically, the top portion 116a of the transverse teeth 112, 112' may have a non-zero dimension between 3mm and 6 mm.

Typically, the convex top portion 116c is the result of a cubic spline of several points or nodes of the first contour 116. In this way, equal convexities are defined on both sides of each point. The approximate radius of curvature R1 of the convex top portion 116c may also be determined.

Typically, the convex top portion 116c has an approximate radius of curvature R1 that may be between 0.6mm and 1.4 mm.

The concavity of the concave portion 116d is directly dependent on the spline obtained and described above. In other words, the radius of curvature R2 of the concave portion 116d depends on the spline.

Typically, the radius of curvature R2 of the concave portion 116d may be between 0.6mm and 1.4 mm.

Each transverse tooth 112, 112 'has an axis of symmetry Y, it being understood that when the first profile 116 of each transverse tooth 112, 112' is trapezoidal with rounded corners, it comprises two convex top portions 116c on either side of the top portion 116a and two concave portions 116d on either side of the base portion 116 b.

In one embodiment, the first profile 116 of each transverse tooth 112, 112 'may be defined as a component of a line segment between two points, a radius double tangent between the line segment and the base 116b of the tooth, in other words, the first profile 116 may be defined as a concave portion 116d and a spline tangent to both the line segment and a line tangent to the top of the transverse tooth 112, 112'.

In use, this type of profile allows the belt 100 to transmit higher torque, but may result in reduced engagement quality. This may also reduce stress on the transverse teeth 112, 112' and deformation of the transverse teeth.

Each longitudinal tooth 114, 114 'of the plurality of longitudinal teeth 114, 114' also extends between two transverse teeth 112,112', extending substantially perpendicular to, and advantageously between, the two transverse teeth 112, 112'.

Each longitudinal tooth 114, 114' also has in cross section a second profile 118, which second profile 118 has two inclined sides 119 converging towards each other in the direction of the top of the tooth, which sides 119 are also connected by at least one rounded portion at the level of the top. In general, the sides 119 may be, for example, generally V-shaped or U-shaped.

As previously mentioned, "rounded" is understood to mean that the second profile 118 of the longitudinal teeth 114, 114' has a shape defining at least one curvature.

The second profile 118 of each longitudinal tooth 114, 114' may have a top defining a zero-sized top portion 118 a. In this case, the tops of the longitudinal teeth 114, 114' are convex and take on an arc of a circle.

In this case, the second profile 118 of the longitudinal teeth 114, 114' advantageously comprises at least one concave portion 118d of the bottom tooth concave portion 120 and a convex tooth top 118c.

Typically, the radius of curvature R2' of the concave portion 118d of the bottom tooth concave portion 120 is between 0.8mm and 1.6 mm.

Typically, the radius of curvature R3 of the convex tip 118c is between 0.8mm and 1.6 mm.

Each longitudinal tooth 114, 114' has an axis of symmetry. It will thus be appreciated that the second profile 118 of each longitudinal tooth 114, 114' includes a convex tip 118c and two concave portions 118d on either side of the base 118 b.

Alternatively, not shown, the second profile 118 of each longitudinal tooth 114, 114' may be trapezoidal with rounded corners, i.e., substantially similar to the first profile 116 described above. In this case, the top of each longitudinal tooth 114, 114 'defines a top portion 118a of non-zero dimension, parallel or non-parallel to an imaginary base 118b of the longitudinal tooth 114, 114', which itself is parallel to the back portion 104 of the belt 100. In other words, the top of each longitudinal tooth 114, 114' defines a non-zero sized top portion 118a that is parallel or non-parallel to the back side portion 104 of the belt 100. It should be appreciated that the back portion 104 of the belt 100 is substantially flat and the top portion 118a is also substantially flat. While at least one curvature is defined by at least one angle describing the curvature in a convex manner at the level of the top of the longitudinal teeth 114, 114' on the one hand and/or at least one angle describing the curvature in a concave manner at the level of the tooth recess 120 on the other hand. Since the second profile 118 of the longitudinal teeth 114, 114' has an axis of symmetry Y ', it will be appreciated that the second profile 118 of each longitudinal tooth 114, 114' includes two convex top portions on either side of the top portion 118a and two concave portions 118d on either side of the base portion 118 b.

Furthermore, the inclined sides 119 of each longitudinal tooth 114, 114' connected by a rounded portion form an angle between them, which angle is between 30 ° and 50 °. Advantageously, the value of this angle is between 30 ° and 45 °, and preferably between 35 ° and 45 °.

In addition, the transverse teeth 112, 112 'have a tooth height H1 and the longitudinal teeth 114, 114' have a tooth height H2. The non-zero tooth height H2 of the longitudinal teeth 114, 114 'is less than or equal to the tooth height H1 of the transverse teeth 112, 112'.

Advantageously, the non-zero tooth height H2 of the longitudinal teeth 114, 114 'is strictly less than the tooth height H1 of the transverse teeth 112, 112'.

The tooth heights H2 of the longitudinal teeth 114, 114' are lower than the tooth heights H1 of the transverse teeth, which increases the flexural flexibility of the belt 100. The increased flexibility allows the belt 100 to be more easily wound onto small diameter pulleys. For example, small diameter pulleys are particularly popular for bicycle applications.

Typically, the tooth height H1 of the transverse teeth 112, 112' may be between 2.5mm and 5 mm.

Typically, when the tooth height H2 of the longitudinal teeth 114, 114 'is strictly less than the tooth height H1 of the transverse teeth 112, 112', the tooth height H2 of the longitudinal teeth may satisfy 0.4H 1. Ltoreq.H2≤1.0H 1. Advantageously, the tooth height H2 satisfies 0.4 XH 1. Ltoreq.H2≤0.9 XH 1, even more advantageously satisfies 0.4 XH 1. Ltoreq.H2≤0.8 XH 1, and preferably satisfies 0.5 XH 1. Ltoreq.H2≤0.8 XH 1.

It was also observed that when the tooth height H2 is greater than or equal to 0.4×h1, good lateral guidance of the belt is improved, while when the tooth height H2 is less than or equal to 0.8×h1, good winding of the belt on the pulley is ensured.

In use, the transverse teeth 112, 112' are used to transmit torque and this torque transmission is greater due to the presence of the inclined sides 117 connected to each other by the at least one rounded portion. The longitudinal teeth 114, 114' transmit torque in addition to self-centering the belt 100. As previously mentioned, the angle formed by the sides 119 introduced by the profile 118 of the longitudinal teeth 114, 114' facilitates torque transmission. Furthermore, the rounded shape of profile 118 allows belt 100 to be more quickly self-centering on the pulley on which it is mounted in the event of its lateral displacement, thereby improving its guidance. The presence of the longitudinal teeth 114, 114 'also limits the deformation of the transverse teeth 112, 112'. Because the tooth height H2 of the longitudinal teeth 114, 114 'is less than or equal to the tooth height H1 of the transverse teeth 112, 112', torque transmission and steering are improved. If the tooth height H2 is greater than the tooth height H1, constraints may occur, particularly reduced flexibility of the belt 100 and mismatch with the pulley with which the belt 100 is configured to mate.

The transverse teeth 112, 112' of the belt 100 may be distributed at a pitch of 8mm, 11mm or 14 mm. Advantageously, the transverse teeth 112, 112' of the belt 100 are distributed at a pitch of 11 mm.

The belt 100 also includes an assembly of tensile cords 110. The cord 110 is embedded in the body 102 between the back side portion 104 and the abdominal side portion 106 of the body 102. The cords 110 increase the tensile modulus of the belt 100. Thus, the cords extend along the length of the belt and are disposed adjacent to one another across the width of the body 102. In particular, the cords 110 of the cord assembly may be made of a material selected from the group consisting of aramid, polyester, fiberglass, or carbon fiber, or combinations thereof. Thus, for the application in question, the cords allow greater torque transmission while maintaining a very limited elongation of the belt 100.

The configuration of each cord 110, the number of cords 110 disposed across the width of the belt 100, and the choice of materials comprising the cords are variable and depend on the tensile modulus required for the belt 100 to ensure torque transmission while limiting elongation of the belt 100. The general effect of such a cord 110 is to allow for higher torque transmission.

Advantageously, the tensile modulus of the belt 100 is selected between 10000N/mm belt width (Newton per millimeter of belt width) and 30000N/mm belt width, measured linearly between 0% and 1% elongation of the belt.

As shown in fig. 3 and 5, the timing belt 100 may further include a coating 122 disposed at a level of the outer surfaces of the plurality of teeth 112, 112', 114'. The coating 122 is particularly useful for reinforcing the feet, i.e., the concave portions 116d of the transverse teeth 112, 112 'and the concave portions 118d of the longitudinal teeth 114, 114'.

The coating 122 may generally be made of a textile material selected from, but not limited to, knitted fabrics, woven fabrics, or nonwoven fabrics. In this case, the coating 122 may be made of a material generally selected from Polyamide (PA) or polyamide-elastic fiber mixture.

Alternatively, the coating 122 may be an elastomeric thermoplastic film having a polymer matrix that is a combination of a thermoplastic matrix and an elastomeric matrix. The elastomeric portion of the elastomeric thermoplastic is advantageously an ethylene-alpha-olefin, such as ethylene-propylene-monomer (EPM) or ethylene-propylene-diene monomer (EPDM). The thermoplastic matrix of the elastic thermoplastic is advantageously an olefinic thermoplastic, such as a low density polyethylene.

The thickness of such thermoplastic elastomer films may be between 50 μm (micrometers) and 200 μm

The elastomer-based body 102 of the belt 100 may be made of a material selected from, but not limited to, ethylene-alpha-olefins such as ethylene-propylene-monomer (EPM) or ethylene-propylene-diene monomer (EPDM), hydrogenated butadiene-acrylonitrile copolymer (HNBR), or Polyurethane (PU).

Example of embodiment of synchronous Belt according to the invention

Hereinafter, referring to fig. 2 to 5, fig. 2 to 5 show specific examples of the embodiment of the belt 100.

The elastomer-based body 102 is made of peroxide-cured Ethylene Propylene Diene Monomer (EPDM), in this example, having a shore a hardness of 85.

In an example of this embodiment, the belt 100 has a geometry as defined below and shown in fig. 2 and 4. The body 102 has a thickness T of 6.5mm and a width of 12mm measured from the backside portion 104 to the top of the transverse teeth 112, 112'.

The height H1 of each transverse tooth 112, 112' is 5mm. Furthermore, in the example of the present embodiment, the first profile 116 of each transverse tooth 112, 112' is trapezoidal with rounded corners. The first profile 116 has a top portion 116a of 2mm and a convex top portion 116c with an approximate radius of curvature R1 of 1.2 mm.

The height H2 of each longitudinal tooth 114, 114' is 2.2mm. Further, the rounded second profile 118 of each longitudinal tooth 114, 114 'has a concave portion 118d with a bottom tooth concave portion 120 having a radius of curvature R2' of 1.2mm and a convex tooth top 118c with a radius of curvature R3 of 1.6 mm. Furthermore, the inclined sides 119 connected by at least one rounded portion of the second profile 118 of each longitudinal tooth 112, 112' form an angle of 40 ° with each other.

The assembly of cords 110 embedded within the body 102 includes 13 cords 110. The diameter d of the cords 110 is 0.8mm and the centers of the individual cords are laterally separated by a spacing p of 0.92 mm. The center of each cord 110 is also located at a distance of about 0.7mm from the back portion 104 of the belt 100.

Each cord 110 is made of an aramid, in particular 1100 x 1 x 4 aramid, i.e. each cord has a titer of 1100dtex (decitex), i.e. 1100 x 10 ^-7 kg/m (kilograms per meter), and each cord is first twisted individually before four strands are twisted. Each cord 110 also has a young's modulus of 30000MPa (megapascals) or 30000N/mm ² (newtons per square millimeter).

Thus, the tensile modulus of the belt can be calculated and expressed as the Young's modulus of the cord 110 multiplied by the cross-sectional area of the cord 110. In the example of the embodiment shown, the belt 100 has 13 cords 110, wherein each cord 110 has a diameter d of 0.8mm and a total cross-sectional area of about 6.53mm ². Thus, the assembly of cords 110 allows the tensile modulus of the belt 100 to be defined as a value of about 195900N.

In an example of this embodiment, the drive belt 100 includes a coating 122, as shown in fig. 3 and 5. The coating 122 is a polyamide knitted fabric, particularly polyamide 66 having a gram weight of 150g/m ² (grams per square meter).

In the example of this embodiment, the transverse teeth 112, 112' of the belt 100 are distributed at a pitch of 11 mm. This spacing also has the advantage of optimizing torque transmission and optimizing overall size. The smaller the spacing, the less torque is transmitted and the larger the spacing, the larger the overall size of the teeth.

Referring now to fig. 6-12, fig. 6-12 illustrate the steps of manufacturing the belt 100 in the above-described embodiments.

The method of manufacturing the belt 100 according to the present invention includes:

forming a strip blank 10 from the strip material around a cylindrical mandrel;

-removing the blank from the mandrel;

Inserting the blank 10 into a cylindrical mold 12 comprising on the inner cylindrical wall a female pattern of transverse teeth 112, 112 'and longitudinal teeth 114, 114' to be formed on the belt 100,

Pressing the blank 10 against the mold 12 by means of an expandable rubber bladder 14 and heating the mold 12 in order to vulcanize the belt blank 10;

demolding the vulcanized blank, and

-Cutting the vulcanized blank 10 so as to form the timing belt 100.

The strip material from which the blank 10 is formed is previously placed on a cylindrical mandrel (not shown). These belt materials include the backside portion 104 of the belt body 102 (in the original state), the cords 110, and the ventral portion 106 of the belt body 102 (in the original state). These belt materials may also include a coating 122 disposed on the ventral portion 106 of the belt body 102. In fig. 6 and 7, the blank 10 has been removed from the cylindrical mandrel and has been inserted into a cylindrical mold 12 that includes at least one pattern on its inner cylindrical wall that is opposite the profile of the transverse teeth 112, 112 'and longitudinal teeth 114, 114' to be formed on the belt. It should be appreciated that the ventral portion 106 (in the original state) is positioned in contact with the mold 12.

In fig. 8 and 9, the inflatable bladder 14 is positioned within the blank 10.

In fig. 10 and 11, the inflatable bladder 14 is inflated to a pressure of 20 bar, thereby pressing the back side portion 104 of the blank 10 (in the original state) against the mold 12 (see arrow E in fig. 11). In this way, the inner wall of the mold 12 having at least one pattern (which is a negative pattern of the pattern of teeth 112, 112', 114' to be formed on the belt) forms a corresponding pattern on the outer surface of the abdominal portion 106 of the blank 10. At the same time, the mold 12 is heated to 182 ℃ to ensure vulcanization of the backside portion 104 and the abdominal side portion 106 configured to form the vulcanized elastomeric body 102. It should be appreciated that during this step, the pattern of mold 12 is printed on blank 10.

The now vulcanised blank 10 is then removed from the mould as shown in fig. 12, and the blank 10 is then cut to the desired width to obtain the belt 100 according to the invention.

Next, the synchronous belt 100 produced in this manner was tested for tensile strength. The test was performed using a variety of standards including ISO 4210-8 and French and European standards NF EN 15194.

These criteria describe the tensile strength test shown in fig. 13. In this test, a belt 100 according to the present invention was mounted on two similar or identical drive pulleys P, P'. At least one of the two pulleys P, P' is free to rotate. During testing, the tensile load was gradually increased until the tensile force applied to the belt 100 reached 4000N. In order for the force applied to the belt 100 to reach 4000N, a tensile load F of 8000N is required.

When this threshold is reached, the strip 100 does not exhibit cracking, breaking or delamination according to standard recommendations.

The example ends.

Referring to fig. 14-16, the present invention also relates to an assembly 300, the assembly 300 comprising the timing belt 100 and at least one pulley 200 as described above.

From a practical point of view, the assembly 300 may advantageously be in the form of a kit or in an already assembled form.

Preferably, the belt 100 is configured to be mounted on two pulleys 200 (i.e., a first pulley and a second pulley) in use. Each of these pulleys 200 comprises, on the one hand, two circumferential rows of teeth 210, 210 'parallel to each other and configured to receive the tooth recesses 122 of the plurality of transverse teeth 112, 112' of the belt 100, and, on the other hand, each of these pulleys 200 comprises a circumferential groove 220 separating the two circumferential rows of teeth 210, 210 'and configured to receive the plurality of longitudinal teeth 114, 114' of the belt 100.

Advantageously, the assembly 300 comprises a first pulley having a given size and a second pulley (not shown) having a size different from that of the first pulley. The different sizes mean that the diameter of the second pulley is larger or smaller than the diameter of the first pulley.

Advantageously, the assembly 300 comprises the same first pulley and second pulley. By identical it is meant that the two pulleys have the same dimensions, e.g. the same diameter and rows of teeth 210, 210' having the same geometry.

Each pulley 200 may be made of a selected material, but the material is not limited to steel, aluminum, or plastic. Each of these materials has properties in terms of mechanical strength, density or cost that may be suitable for the intended application.

Each row of circumferential teeth 210, 210' also includes a tooth recess 212 having a depth P1. Advantageously, this depth P1 is greater than the height H1 of the transverse teeth 112, 112' of the belt 100.

The circumferential groove 220 in each pulley 200 also has a depth P2. Advantageously, this depth P2 is greater than the height H2 of the longitudinal teeth 144.

The teeth in each row of circumferential teeth 210, 210' may be distributed at a pitch of 8mm, 11mm or 14 mm.

It will thus be appreciated that there is a gap 230 between the top of each tooth 112, 112', 114' and the tooth recess 210 of the pulley 200, on the one hand, and the top of each tooth 112, 112', 114' and the bottom of the groove 220, on the other hand. The advantage of this gap 230 is that it serves as a means of removing foreign matter, such as mud, water or stone, which may get into the assembly 300 during operation, more particularly between the pulley 200 and the belt 100. Since these foreign substances are more easily discharged, the risk of abrasion of the belt 100 is reduced.

In view of the above, it is evident that the belt according to the invention allows to improve the torque transmissible by the belt and its stability. In fact, in use, the contact surface between the transverse and longitudinal teeth of the belt and the teeth of the pulley is large, thanks to the shape of the teeth of the belt. The presence of such high contact areas and cords increases the tensile modulus of the belt and thus allows control of the transmissible torque and the degree of deformation of the belt, which reduces wear of the belt over time and thus increases the service life of the belt. Furthermore, the longitudinal teeth guide the belt over the pulley, preventing its lateral movement.

Another advantage is that when the belt is mounted on a pulley of an assembly according to the invention, external elements (e.g. water, earth, mud or stones) that may enter the tooth recesses of the pulley are allowed to be removed.

Claims

1. A synchronous drive belt (100) comprising an elastomer-based body (102) comprising an assembly of a back side portion (104), a side portion (106) and a tensile cord (110) between the back side portion (104) and the side portion (106), the side portion (106) having, on the one hand, a plurality of transverse teeth (112, 112 ') each transverse tooth (112, 112') having, in cross section, a first profile (116) with two inclined flanks (117) converging towards each other in the top direction of the transverse teeth (112, 112 '), the flanks (117) of the transverse teeth being connected by at least one rounded portion, each transverse tooth having a tooth height H1, and the side portion (106) having, on the other hand, a plurality of longitudinal teeth (114, 114'), each longitudinal tooth (114, 114 ') extending substantially perpendicular to the transverse teeth (112, 112') and having, in cross section, a second profile (118) with the longitudinal flanks (114) converging towards each other in the top direction of the top of the transverse teeth (112, 112 '), the second profile having, the longitudinal flanks (114') or the flanks (119) converging towards each other in the top direction of the at least one rounded portion having a tooth height H1.

2. The belt (100) of claim 1, wherein the tooth height H2 of each longitudinal tooth (114, 114') satisfies 0.4 x H1 ∈h2 ∈0.8 x H1.

3. The belt (100) according to any one of claims 1 or 2, wherein each transverse tooth (112, 112') has, in cross section, a first trapezoidal profile (116) with rounded corners.

4. A belt (100) according to claim 3, wherein the first profile (116) of each transverse tooth (112, 112') comprises two convex top portions (116 c) located on both sides of the top portion (116 a), and two concave portions (116 d) located on both sides of the base portion (116 b) of the transverse tooth.

5. The belt (100) of claim 4, wherein each convex top portion (116 c) of the first profile (116) has an approximate radius of curvature (R1) between 0.6mm and 1.4mm, and each concave portion (116 d) has a radius of curvature (R2) between 0.6mm and 1.4 mm.

6. The belt (100) according to any one of claims 1 to 5, wherein the second profile (118) of each longitudinal tooth (114, 114') comprises two concave portions (118 d) located on either side of a base portion (118 b) of the longitudinal tooth, and tooth tops (118 c) that are convex (118 c).

7. The belt (100) of claim 6, wherein each concave portion (118 d) of the second profile (118) has a radius of curvature (R2') between 0.8mm and 1.6mm, and the top portion (118 c) of the second profile has a radius of curvature (R3) between 0.8mm and 1.6 mm.

8. The belt (100) of any one of claims 1 to 7, wherein the second profile (118) of each longitudinal tooth (114, 114') is a trapezoidal profile with rounded corners.

9. The belt (100) according to any one of claims 1 to 8, comprising a coating (120) arranged at the level of the outer surfaces of the plurality of transverse teeth (112, 112 ') and the plurality of longitudinal teeth (114, 114').

10. The belt (100) according to claim 9, wherein the elastomer-based body (102) of belt (100) is made of a material selected from ethylene-a-olefins or polyurethanes, and the coating (120) is a textile material or an elastomeric thermoplastic film.

11. The belt (100) according to any one of claims 1 to 10, wherein each cord (110) of the assembly of tensile cords is made of aramid, polyester, glass or carbon fibers or a combination thereof.

12. An assembly (300) comprising at least one pulley (200) and a synchronous drive belt (100) according to any one of claims 1 to 11, each pulley comprising:

-two rows of circumferential teeth (210, 210 ') parallel to each other and configured to receive tooth recesses (122) of the plurality of transverse teeth (112, 112') of the belt (100), and

-A circumferential groove (220) separating the two rows of circumferential teeth, the circumferential groove being configured to receive the plurality of longitudinal teeth (114, 114') of the belt (100).

13. The assembly (300) of claim 12, wherein each row of circumferential teeth (210, 210 ') includes a tooth recess (212) having a depth P1 that is greater than a height H1 of the transverse teeth (112, 112') of the belt (100).

14. The assembly (300) according to any one of claims 12 or 13, wherein a depth P2 of the longitudinal groove (220) is greater than a height H2 of the longitudinal teeth (114, 114') of the belt (100).

15. A method of manufacturing a belt (100) according to any one of claims 1 to 14, the method comprising the steps of:

-forming a strip blank (10) from the strip material around a cylindrical mandrel;

-removing the blank from the mandrel;

-inserting the blank (10) into a cylindrical mould (12) comprising on an inner cylindrical wall a female pattern of transverse and longitudinal teeth to be formed on the belt;

-pressing the blank (10) against the mould (12) by means of an expandable rubber capsule (14) and heating the mould in order to vulcanize the strip;

demolding the vulcanized blank, and

-Cutting the vulcanized blank so as to form the strip.