CN113474576B

CN113474576B - Power transmission belt with aramid tension rope

Info

Publication number: CN113474576B
Application number: CN202080016267.3A
Authority: CN
Inventors: 马赛尔·沙佩尔; 威利·奥伦博格; 迈克尔·吉斯曼
Original assignee: Arntz Beteiligungs GmbH and Co KG
Current assignee: Arntz Beteiligungs GmbH and Co KG
Priority date: 2019-01-11
Filing date: 2020-01-13
Publication date: 2023-08-15
Anticipated expiration: 2040-01-13
Also published as: DE102019100654A1; CN113474576A; WO2020144376A1

Abstract

The invention relates to a power transmission belt comprising at least one tensile cord made of two-stage twisted base yarn and embedded in a body made of an elastic material. Wherein the untwisted base yarn is a multifilament yarn comprising a plurality of aramid filaments. In a first twisting stage, the untwisted base yarns are twisted to form primary twisted yarns, and in a second twisting stage, twisted in a twisting direction opposite to the first twisting stage to form final twisted yarns, which are used to form the tensile cord. The fineness of the base yarn is less than 1000dtex. Twisting two or three base yarns to form primary twisted yarns in a first twisting stage, and twisting three to six primary twisted yarns to form final twisted yarns in a second twisting stage; the twist coefficient (F ₁ ) Twist coefficient with final twisted yarn (F ₂ ) The ratio of the twist of the primary twist yarn (D1 m- ¹ ]) Twist with final twist (D2 m ^‑1 ]) The ratio is 1 to 1.7.

Description

Power transmission belt with aramid tension rope

Technical Field

The invention relates to a power transmission belt, which comprises a tension rope made of two-stage twisting base yarns and embedded in a main body made of elastic materials, wherein the base yarns are aramid base yarns, the aramid base yarns are twisted to form primary twisted yarns in a first twisting stage, and the primary twisted yarns are twisted to form final twisted yarns in a second twisting stage in a direction opposite to the direction of the first twisting stage; the final twist is used to form the tensile cord.

The invention particularly relates to a high-performance transmission belt which can bear high tensile force and high alternating bending stress and is wear-resistant. Among them, V-belts, V-ribbed belts and synchronous belts are mainly represented.

Such a transmission belt is usually equipped with a tensile cord made of so-called high modulus cords (Korde), characterized by a high elastic modulus and low ductility. The rope (Korde) is a strand-like tension rope made of twisted synthetic fibers or synthetic base yarns. Polyester, aramid and carbon fibers, and blends of the above fiber types are used primarily for synthetic base yarns. The aramid based yarn exhibits good compressive and impact strength by virtue of its high tensile strength or high tear strength. The cords (Korde) are typically composed of twisted aramid multifilament yarns (aramid multifilament yarns), wherein the monofilament base yarns are prior art base yarns as described in document DE 69108264 T2.

Since the tensioning cords of a drive belt have a significant impact on the performance of the drive belt, numerous attempts have been made by those skilled in the art to improve the performance of the tensioning cords, particularly in terms of properties such as tear resistance, fatigue resistance, behavior under alternating loads, and service life. These properties are reflected in the properties of the belt reinforced in this way, which are regularly improved.

Background

EP 2601333 B2 relates to the use of a fibrous multifilament yarn with increased denier per filament to improve the fatigue behaviour of a tension member or tension cord. It has been found that an increased denier per filament compared to a smaller denier per filament with a corresponding denier per base yarn is advantageous at least in the case of cellulosic fibers. The tensile cord tested consisted of two multifilament yarns with a total denier of 1840 dtex. Both multifilament yarns had 375 turns per meter (spinning twist or Z twist of yarn twist) and the cords were then twisted with 375 turns per meter (S twist). The structure of the tested tension rope is as follows: 1840 dtex x x 1x 2Z/S375 (symmetrical).

In addition to the yarn titer and the long fiber titer, the twisting of the tensile cord has a decisive influence on the properties of the tensile cord and thus on the belt properties of the drive belt reinforced in this way.

DE 1808118 A1 discloses a rope made of rayon having improved strength and fatigue resistance properties for rubber articles to be reinforced, in particular in the field of tires. Artificial silk cords consist of artificial threads which are first formed into a primary twist in a first twisting direction and then twisted in a second twisting direction opposite to the primary twisting direction. It has been found that rope constructions made of rayon filaments with negative asymmetric twist structures have higher strength and fatigue resistance properties.

By definition, "asymmetric twist" refers to the twist of an initial twist (also referred to as rotation or twist) being different from the twist of a final twist in the case of "asymmetric twist". The twist is hereinafter always referred to as twist D, in revolutions per meter (number of turns). On the other hand, "symmetrical twist" is understood to mean that the primary and final twist are rotated or twisted with the same twist, typically in opposite directions. The positive asymmetric twisting structure is that the twist of each meter of primary twisting yarn is larger than the final twisting

Twist and its associated properties are often characterized using a so-called twist multiplier (F), also known as a rotation factor (a or K) or a Twist Factor (TF), also known as an english Twist Multiplier (TM) in english systems (non-metric) due to the involvement of inches and denier. Hereinafter, reference is always made to the metric "twist factor F", wherein:

wherein d=twist (twist rotations per meter),

t=fineness in tex (yarn count)

The twist multiplier is considered as an indicator of the strength and stiffness of the twisted yarn.

The multi-stage twisted base yarn is typically characterized using a ratio of related twist factors, i.e., by a ratio of F1 (first stage twist factor) to F2 (second stage twist factor F2) for two stages of twisting including primary and final twisting. This nomenclature generally involves single stage twisting of the yarn by assigning a first "twist multiplier" to the twisted base yarn; this relates to a twisted structure of the "titer x 1x n" type (n=the number of base yarns in the second stage twist).

EP 1861632 B1 discloses an endless belt with an elastic belt body and carrying cords embedded in the elastic belt body. The base yarn of the cord may also consist at least partially of aramid fibers. The cord comprises a plurality of base yarns twisted in a first rotational direction by a first twist multiplier or twist multiplier, wherein the cord made from a plurality of the base yarns is twisted in an opposite twist direction by a second twist multiplier. The cord exhibits a strong positive asymmetry due to the fact that the ratio of the first twist multiplier to the second twist multiplier is defined to be greater than 1.5. In an embodiment, F1: f2 =2.5 and D1: d2 =5. With great asymmetry, the tensile cord and thus the endless belt reinforced by the tensile cord should have a higher fatigue resistance under varying loads (bending loads, fatigue loads).

Due to recent developments in engines and auxiliary devices, high tensile, alternate bending stress resistance, and wear resistance of the drive belt have been demanded.

Disclosure of Invention

The object of the present invention is to provide a high-performance drive belt, which exhibits high bending fatigue resistance and good vibration performance under high tensile loads, and which has a longer service life, in particular at low rotational speeds with a high torque reduction.

The object of the invention is achieved by the power transmission belt according to the invention, which is embedded in a body made of an elastic material, having at least one tensile cord made of a two-stage twisted base yarn, wherein the base yarn is an aramid base yarn which is twisted in a first twisting stage to form primary twisted threads and in a second twisting stage in a direction of rotation opposite to the first twisting stage to form final twisted threads, which are used to form tensile cords. The power transmission belt of the invention is characterized in that: i) A titer of the base yarn is less than 1000dtex, ii) two or three base yarns are twisted into primary twist yarns in a first twisting stage, and iii) three to six primary twist yarns are twisted into final twist yarns in a second twisting stage, a ratio of a twist factor (F1) of the primary twist yarns to a twist factor (F2) of the final twist yarns being 0.8 to less than 1, a ratio of a twist (D1) of the primary twist yarns to a twist (D2) of the final twist yarns being 1 to 1.7, wherein:

f=twist factor, d=twist (twist rotations per meter),

t=yarn fineness, measured in tex,

n=1 or 2 is used for the first and second twisting stages.

Advantageous further developments of the invention are indicated in the dependent claims.

The term power transmission belt includes all common types of suitable belts known to those skilled in the art, such as V-belts, V-ribbed belts, synchronous belts or toothed belts, as well as special belts for special driving purposes. Preferably, the V-belt, V-ribbed belt and timing belt are used for mission specification purposes, and the V-belt may be a toothed V-belt.

All these belts have a belt body made of an elastic material in which at least one tension cord, also called string, is embedded. In the production of endless belts commonly used in the prior art, the belt body is typically built up in layers on drums, with the tensile cord being wound in a spiral between two layers of elastic material.

The elastic material of the belt body is formed of at least one elastomer commonly used in belt production. Different belt layers may employ the same or different elastomers. Such as a belt back or cover plate, a harness-embedded plane, a core, teeth or a substructure or compression zone, a power transmitting side cover layer, etc. Additional materials (fibers, adhesive layers, etc.) may also be added to the tape body.

Common elastomers used in belt production include R, M, and S elastomers, which may be used in various areas of the belt body. The elastomer is preferably an elastomer of group EPM, EPDM, ACSM, HNBR, CR, SBR, BR and blends of these elastomers, but PU and PU-containing elastomers may also be selected, but are not preferred.

The tension rope provided by the invention consists of two-stage twisting base yarns, wherein the base yarns are aramid base yarns. The tensile cord may be impregnated, treated, such as plasma treated or coated. The thickness of which can be adjusted by the person skilled in the art according to the specific circumstances. The denier and twist of the individual yarns depend on the intended use of the invention,

aramid fibers or aramid-based yarns and cords are used to reinforce various industrial rubber products and are commercially available in various forms. The aramid fiber or aramid filament is composed of aromatic or mainly aromatic polyamide, for example, obtained from aromatic diamine and aromatic dicarboxylic acid. In addition to the amide groups, it may also contain other functional groups, in particular imide groups. The aramid-based yarn also includes hybrid yarns made mainly of aramid fibers or aramid filaments and other fibers or filaments, such as polyester or carbon, wherein the main inclusion means that the weight fraction is more than 50%.

The base yarn of the tension rope or cord of the invention is composed of aromatic base yarn yarns. As described herein, the term aromatic-based yarns includes aromatic polyamide hybrid yarns. The term "base yarn" is understood to mean an initial yarn formed from single or multiple, single or two-stage yams.

The following applies:

"base yarn" is a structure made of a textile fiber material, such as staple, long, or ribbon fibers. The base yarn may comprise a single or several long fibers or a plurality of long fibers (including very fine synthetic fibers); it is also known as multifilament yarn (multifilmentgam). The long fibers of the base yarn may not twist in a substantially parallel manner to each other; the long fibers may be made into an adhesive to secure the yarns together. The base yarn may also be twisted and then it has a spinning twist or a protective twist, which refers to holding the yarns together by a small number of rotations per meter of yarn. The base yarn twist has no twist, but the base yarn twist can be marked by a twist multiplier with a rotation multiplier.

"twist" is a textile structure made by rotating (twisting) at least two base yarns together.

As described above, a "primary twist" is an untwisted twist (i.e., base yarn). The stage of twisting the base yarn into a primary twist which is then further twisted is referred to as a first twisting stage.

An "end-twisted yarn" is a final product formed by the twisting of twisted yarns, such as a rope or tensile cord herein, twisted in a single or multiple stage twist. Thus, the final twisted thread is referred to herein as a rope thread. In the present invention, the final twist has two twist stages.

The relative rotational direction of twisting is very important for the characteristics of the twisted wire subjected to two-stage twisting. The primary twist and the final twist can be co-directional or counter-directional. In the present invention, the twisting directions of the primary twisted yarn and the final twisted yarn are opposite, i.e., reverse twisting.

The "fineness" (base yarn fineness) is a measure of the fineness of the base yarn in tex or dtex in metric systems.

The invention is characterized in that a relatively large number of threads with a relatively low titer compared to the examples in the prior artTwo-stage twisting is performed, wherein the ratio of the twist factor (F1: F2) of the primary to final twisted thread is less than 1, more precisely very small, i.e. less than 10-20%, and the ratio of the twist of the primary to final twisted thread is 1 to 1.7, which means that the two-stage rope threads are twisted symmetrically or slightly positively asymmetrically.

It has been found that such a twisted structure or such a twisted structure has a very positive effect on the belt characteristics of a conveyor belt, which conveyor belt enhances its performance by embedding aramid cords with a twisted structure or twisted structure, the service life of which conveyor belt under high loads is significantly increased, in particular under bending loads, which conveyor belt can be determined by a reduction of high torque at low speeds.

The titer of the aramid base yarn of the tensile cord is preferably 200 to 1000dtex, more preferably 250 to 800dtex, particularly preferably 450 to 650dtex.

The base yarn is preferably a multifilament yarn comprising a plurality of aramid filaments.

The base yarns of the cords and tensile cords are preferably untwisted or provided with a protective twist. The protective twist may be up to about 50 turns per meter.

Further, the ratio of the twist factor F1 to F2 in the present invention is 0.8 to 0.9.

In a currently particularly preferred embodiment, the two-stage twist of the tensile cord is a positive asymmetric twist (D1 > D2).

Preferably, the twist D1 of the primary twist is 150 to 400 turns per meter (TPM, 1/m-1). The twist of the final twist is calculated from the ratio of the initial twist to the final twist of 1 to 1.7 times or preferably (> 1) to 1.7 times.

According to one aspect of the invention, the drive belt is a V-belt, which may be a toothed belt, a V-ribbed belt or a synchronous belt. The performance test described below was performed on a v-ribbed belt as an example belt. However, since these results are based on the characteristics of the tensile cord involved, they can also be applied to other types of belts.

Drawings

The invention is explained in more detail below in connection with specific embodiments and with reference to the drawings and figures. The examples should be understood to illustrate the invention and not to limit the scope of the invention. As mentioned above, they are only intended to facilitate an understanding of the present invention.

The following figures illustrate:

fig. 1 shows a schematic perspective cross-sectional view of the v-ribbed belt of a first embodiment of the invention;

fig. 2 shows a schematic perspective cross-section of a toothed V-belt according to a second embodiment of the invention;

FIG. 3 shows a general schematic of a two-stage twisted tensile cord;

fig. 4-7 illustrate: compared with the comparative belts ((2), (3)) from the prior art, the belt (1) according to the invention has a performance test pattern, i.e.

FIG. 4 is a graph showing performance failure test results applied to an example tape;

FIG. 5 is a bar graph showing the results of a rotational non-uniformity test;

FIG. 6 is a bar graph of the first RSG (English: BSG) test results with a load torque of 50 Nm;

fig. 7 is a bar graph of the second RSG (english: BSG) test result with a load torque of 70 Nm.

Detailed Description

Fig. 1 shows a first exemplary embodiment of a power transmission belt according to the invention, namely a v-ribbed belt, designated as a whole by reference numeral 10, having a cover plate 11 and a belt body 12, wherein a tension rope 14 is embedded in the belt body 12 in a usual manner, further wherein the tension rope 14 is made of an aramid rope yarn according to the invention with a reference coefficient of 550dtex 2 x3 (340/230). The strands form a layer of flat tension members parallel to the back of the belt or beneath the cover plate 11. The tension member layer may be located within a cord inlay not separately shown here. Fig. 1 shows a cross-sectional detail of an annular v-ribbed belt with four ribs 16, although a different number of ribs, for example six ribs, may be chosen. For this type of belt, generally 2 to 20 ribs, more preferably 2 to 16 ribs, and especially 2 to 6 ribs are preferred.

Fig. 2 shows a second exemplary embodiment of the power transmission belt according to the invention, i.e. a schematic cross-sectional view of a V-belt 20 with a cover fabric 21 and a belt body 22, on which belt body 22 a tooth structure 23 is formed. The belt body 22 has embedded therein tension ropes 24 made of the aramid rope yarn of the present invention, for example, having a reference coefficient of 550dtex x 2 x3 (340/230).

Fig. 3 shows the basic structure of the twisted tensile cord 30 according to the invention, which is shown substantially in a partially untwisted manner, i.e. at the twisted end of the tensile cord shown, in order to more clearly identify the individual cords, base yarns and filaments. The base yarn 31 consists of a number of aramid long fibers 32, which aramid long fibers 32 are shown adjacent to each other in this embodiment simply in an untwisted manner. In the cord of the embodiment, two base yarns 31 having a fineness of 550dtex are twisted together to form a primary twisted yarn 33, specifically in the present embodiment, the primary twisted yarn 33 is twisted together to form a final twisted yarn 34, specifically in the present embodiment, the primary twisted yarn 33 is twisted in the opposite direction to the twisting direction of the primary twisted yarn 33 itself. The drawings show only the structure in principle, not the actual dimensions. In the rope according to the present embodiment, the final twist 34 is less than the initial twist 33.

Belt testing:

the performance test, the results of which are shown in fig. 4 to 7, described below, was performed by comparing the example belt of the present invention, labeled (1), with two comparative belts, labeled (2) and (3), respectively. All of these belts were multi-wedge belts made of EPDM elastomer, used for core and backing materials, without embedment, with PK parameter values, further from the description, figures 4, 5 show the run time results for belts with parameters 6PK,2050 mm; fig. 6 and 7 show the run time results for a belt with a parameter value of 6pk,1130 mm. The test strips all have exactly the same structure, the only difference being the helically wound aramid cord for the respective test strip.

The aramid rope yarn in the embodiment belt (1) provided by the invention has a configuration of 550dtex x x 2 x3 (Z/S) (340/230), namely, the fineness of the aramid base yarn is 550dtex, two base yarns are used for forming primary twist yarns, the twisting direction of three primary twist yarns is opposite to the twisting direction of the final twist yarns, wherein the primary twist yarns have a twist number of 340m < -1 >, and the final twist yarns have a twist number of 230m < -1 >. The twist ratio D1:D2 was accordingly 1.48, and the ratio of the twist factor F1:F2 was 0.85.

The aramid rope in the comparative tape (2) has a configuration of 1100 x 1x 3, which is an opposite-direction asymmetric twisting structure, and the aramid rope in the comparative tape (3) has a configuration of 1100 x 1x 3, which is an opposite-direction symmetric twisting structure.

1: performance failure test

In a performance failure test, the test belt may undergo repeated alternating bending, resulting in reduced performance.

The test is a performance failure test performed at ambient temperatures greater than 100 ℃. A test belt of approximately 2000mm length was repeatedly bent and reverse bent around smooth and profiled pulleys. The high belt speed and reduced braking force are used to create additional load. All loads remain constant.

The results shown in the bar graph of fig. 4 demonstrate that the example belt (1) reliably passed the three test runs shown herein for a sufficient test duration of about 250 to 300 hours. The comparison strip (2) clearly shows more fluctuations, i.e. the test results show less reliable performance, while the comparison strip (3) already gives worse results in the two test runs shown.

2: irregular rotation test

In an irregular rotation test, the test belt is alternately accelerated and decelerated. So that the test strip is subjected to uneven or pulsating loads.

The results of the irregular rotation test described above are shown in fig. 5. Under the above test conditions, the comparative tape (3) with symmetrical twist failed. The test results of the inventive example belt (1) and the test results of the comparative belt (2) are similar, i.e. show a better performance in each case.

The test is a performance failure test performed at ambient temperatures greater than 100 ℃. A test belt of approximately 2000mm length was repeatedly bent and reverse bent around smooth and profiled pulleys. In this test, further loading can also be provided by the deflected cardan shaft exerting an irregular rotation on the belt drive. This is to simulate irregular rotation of a real internal combustion engine, which is caused by retarded ignition of the individual cylinders. As a further increased load, high braking performance was also applied at the same time in this test. All loads remain constant.

RSG (English: BSG) analog State test

In the case of a belt-driven starter generator (RSG), also denoted BSG in english, the belt is switched between start and stop for the purpose of belt suitability. At start-up, the drive belt must transmit a large torque at low speed. In this type of operation, the traction side and the load side are varied in a constant sequence. In addition, in the transmission mode, the traction side and the load side are changed in a constant order. This drive causes a significant increase in the load in the drive belt drive, so that the performance of the drive belt can be demonstrated by this test.

RSG (English: BSG) test:

the test is a performance failure test performed at room temperature. A test belt of approximately 1000mm length was repeatedly bent and reverse bent around smooth and profiled pulleys. In contrast to the above test, the load in this test does not remain constant. Like a real vehicle, it operates in a stepped cycle of different rotational speed and load torque. The load in the test belt drive also changes, so the test belt load side and slack side alternate (increase load/decrease load). The high dynamics of this test represent the strongest and truest loads on the drive belt. It has been shown that a drive belt with a tension element according to the invention has significantly improved properties in this test.

Two tests were performed under different loads, namely at 50Nm and 70 Nm. The correlation results are shown in fig. 6 and 7. Previously failed comparison tape 3 was no longer tested here. The drive belt according to the invention exhibits a strong performance, which is of great advantage when the drive belt according to the invention is used in RSG (english: BSG) units.

The yarn of the present invention having finer base yarns has a tear strength at least 10% higher than a conventional two-stage asymmetric twisted yarn of similar (available for comparison) denier (such as the comparison tape (2)).

In tensile testing, the force-elongation plot of the test strip (550/2 x 1x 3) of the present invention shows an average tear strength of 640N, whereas the tear strength of the comparative strip (1100 x 1x 3) is only 560N.

The belts according to the invention are particularly suitable for RSG (english: BSG) drives, since they have particularly good tear resistance values and long service lives even under high loads.

Claims

1. A power transmission belt (10, 20) having at least one tensile cord (14, 24) made of a two-stage twisted base yarn (31) and embedded in a body (12, 22) made of an elastic material, said base yarn (31) being an aramid base yarn, twisted in a first twisting stage to form a primary twisted yarn (33) and twisted in a second twisting stage in a twisting direction opposite to the first twisting stage to form a final twisted yarn (34), said final twisted yarn (34) being used to form said tensile cord (14, 24), characterized in that: i) The titer of the base yarn (31) is less than 1000dtex; ii) two or three of said base yarns (31) are twisted to form primary twisted yarns (33) in a first twisting stage and iii) three to six of said primary twisted yarns (33) are twisted to form final twisted yarns (34) in a second twisting stage; wherein the ratio of the twist factor (F1) of the primary twist to the twist factor (F2) of the final twist is from 0.8 to less than 1, and the ratio of the twist (D1) of the primary twist to the twist (D2) of the final twist is from 1 to 1.7, wherein:

f=twist coefficient, d=twist,

t=yarn fineness, measured in tex,

n=1 or 2 is used for the first and second twisting stages.

2. The power transmission belt (10, 20) according to claim 1, characterized in that the base yarn (31) of the tension cord (14, 24) has a titer of 200 to 1000dtex.

3. The power transmission belt (10, 20) according to claim 1, characterized in that the base yarn (31) of the tension cord (14, 24) has a titer of 250 to 800dtex.

4. The power transmission belt (10, 20) according to claim 1, characterized in that the base yarn (31) of the tension cord (14, 24) has a titer of 450 to 650dtex.

5. The power transmission belt (10, 20) of claim 1, wherein the base yarn (31) is a multifilament yarn comprising a plurality of aramid filaments (32).

6. The power transmission belt (10, 20) according to claim 1 or claim, characterized in that the base yarn (31) of the tensile cord (14, 24) is provided with a protective twist or is not twisted itself.

7. The power transmission belt (10, 20) according to claim 1, characterized in that the twist factor F1: the ratio of F2 is 0.8 to 0.9.

8. The power transmission belt (10, 20) of claim 1, wherein the two-stage twist of the tensile cord (14, 24) is a positive asymmetric twist, wherein the twist relationship is D1 > D2.

9. The power transmission belt (10, 20) according to claim 1, characterized in that the twist (D1) of the primary twist is 150 to 400 turns/m.

10. The power transmission belt (10, 20) of claim 1, wherein the belt is a V-belt, a toothed V-belt, a V-ribbed belt, or a synchronous belt.

11. A power transmission belt (10, 20) according to any one of the preceding claims, characterized in that the belt is a high performance belt.