DRIVE BELT, USE OF A DRIVE BELT OF THIS TYPE AS A V-RIBBED BELT, AND PRODUCTION METHOD

Abstract

The invention relates to a drive belt (1) having a main body into which one or more tension strands (3) composed of para-aramid in cord construction are embedded, wherein each tension strand (3) has twisted plies each formed from at least one twisted yarn, and wherein the turning direction of the respective ply (first twist) is the opposite of the turning direction of the cord (final twist).

It is a feature of the invention that the tension strands (3) each have at least four plies, wherein the twist factor TM.sub.1 of the plies (first twist) is between 4.5 and 5.4, and the twist factor TM.sub.2 of the cord (final twist) is between 2.7 and 3.8, and the ratio of the twist factor of the plies to the twist factor of the cord (TM.sub.1/TM.sub.2) is between 1.3 and 1.5.

Claims

1.-15. (canceled)

16. A drive belt (1) comprising a main body into which one or more tension strands (3) composed of para-aramid in cord construction are embedded, wherein each tension strand (3) has twisted plies each formed from at least one twisted yarn, and wherein the turning direction of the respective ply (first twist) is the opposite of the turning direction of the cord (final twist); wherein the tension strands (3) each have at least four plies, wherein a twist factor (TM.sub.1) of the plies (first twist) is between 4.5 and 5.4, and a twist factor (TM.sub.2) of the cord (final twist) is between 2.7 and 3.8; and, wherein a ratio (TM.sub.1/TM.sub.2) of the twist factor of the plies to the twist factor of the cord is between 1.3 and 1.5.

17. The drive belt as claimed in claim 16, wherein the ratio (TM.sub.1/TM.sub.2) of the twist factor of the plies to the twist factor of the cords is between 1.35 and 1.45.

18. The drive belt as claimed in claim 16, wherein the plies have a twist (first twist) between 410 m.sup.−1 and 490 m.sup.−1.

19. The drive belt as claimed in claim 16, wherein the cords each have a twist (final twist) between 125 m.sup.−1 and 175 m.sup.−1.

20. The drive belt as claimed in claim 19, wherein the cords each have the twist (final twist) between 150 m.sup.−1 and 170 m.sup.−1.

21. The drive belt as claimed in claim 16, wherein the plies each have a linear density between 800 dtex and 1200 dtex.

22. The drive belt as claimed in claim 21, wherein the plies each have the linear density of 1100 dtex.

23. The drive belt as claimed in claim 16, wherein the top layer of the main body is a fiber-containing top layer and a fiber-containing substructure mixture (4), each formed from a polymeric material having elastic properties.

24. The drive belt as claimed in claim 16, wherein the polymeric material is peroxidically crosslinked ethylene-propylene rubber or peroxidically crosslinked ethylene-propylene-diene rubber.

25. The drive belt as claimed in claim 16, wherein the one or more tension strands are embedded into the main body in a tension strand layer between the top layer and a substructure mixture (4).

26. The drive belt as claimed in claim 16, wherein the one or more tension strands have been provided with a stripping preparation.

27. The drive belt as claimed in claim 16, wherein the one or more tension strands have been coated with an adhesive.

28. The drive belt as claimed in claim 16, wherein the one or more tension strands have been provided with a stripping preparation and coated with an adhesive.

29. The drive belt as claimed in claim 16, wherein the drive belt has tension strand density of between 80 and 130 tension strands per 100 mm of belt width.

30. The drive belt as claimed in claim 29, wherein the tension strand density is between 100 and 110 tension strands per 100 mm of belt width.

31. The drive belt as claimed in claim 16, wherein the drive belt is a V-ribbed belt.

32. The drive belt as claimed in claim 16, wherein the plies have a twist of 450 m.sup.−1 and the cords each have a twist of 160 m.sup.−1.

33. The drive belt as claimed in claim 16, wherein the drive belt is a V-ribbed belt disposed in a motor vehicle engine as a belt-starter generator.

34. The drive belt as claimed in claim 16, wherein four yarns or yarn bundles are each twisted with a twist (first twist) between 410 m.sup.−1 and 490 m.sup.−1 to form one individual ply in each case, the four plies are then combined and are twisted with an opposite twist (final twist) between 125 m.sup.−1 and 175 m.sup.−1 to form a cord, wherein a twist factor TM.sub.1 between 4.5 and 5.4 is established for each of the plies and a twist factor TM.sub.2 between 2.7 and 3.8 for each of the cords and the ratio (TM.sub.1/TM.sub.2) of the twist factor of the plies to the twist factor of the cord between 1.3 and 1.5.

35. The drive belt as claimed in claim 34, having a twist of 450 m.sup.−1 for each of the four plies and a twist of 160 m.sup.−1 for the cords.

Description

[0030] The invention is elucidated in detail hereinafter by a working example with reference to the appended schematic drawings. The figures show:

[0031] FIG. 1 a partial cross section through a drive belt of the invention in a preferred working example;

[0032] FIG. 2 a roll arrangement of a mild hybrid test for the drive belt according to FIG. 1; and

[0033] FIG. 3 a roll arrangement of a constant high-load test for the drive belt according to FIG. 1.

[0034] FIG. 1 shows a drive belt in partial section, having a main body formed from an outer layer 2 and a substructure mixture 4. Extending between the top layer 2 and the substructure mixture 4 is a tension strand layer composed of multiple tension strands 3. The tension strands 3 are preferably arranged parallel to one another. It is also conceivable that the tension strands 3 are in an offset arrangement relative to one another.

[0035] The drive belt 1 shown in FIG. 1 takes the form of a V-ribbed belt. For this purpose, the substructure 4 has multiple ribs 5 arranged parallel to one another, delimited from one another by grooves 6. The opposite side of the substructure mixture 3 from the tension strands 3 or from the top layer 2 forms a force transmission surface 7 that extends via the ribs 5 and through the grooves 6.

[0036] The force transmission surface 7 may have a coating 8. The coating 8 may be a flock coating, especially with a cotton flock or aramid flock. It is also possible to use an applied textile layer as coating 8. The textile layer may take the form of a weave, loop-formed knit or loop-drawn knit. The coating 8 preferably results in wear protection and sound insulation.

[0037] An essential factor for the improvement in properties of the drive belt 1 over the prior art is the formation of the individual tension strands 3. Each tension strand 3 preferably has at least four, especially exactly four, plies. The twist factor TM1 of the plies here is between 4.5 and 5.4, and the twist factor TM2 of the cords is between 2.7 and 3.8. More particularly, for the tension strands 3 in the drive belt 1 of the invention, the ratio of the twist factor of the plies to the twist factor of the cords (TM1/TM2) is between 1.3 and 1.5, preferably between 1.35 and 1.45.

[0038] On the way to the present invention, multiple V-ribbed belts were constructed with a fiber-containing top layer and a fiber-containing substructure mixture with various aramid tension strands. The top layer and/or the substructure mixture consist of peroxidically crosslinked ethylene-propylene-diene rubber (EPDM). The filament yarn used was the aramid type T1008 (1100 dtex) from Teijin Limited. The tension strand length was generated by parallel winding of 2 cords with different directions of rotation (sZ and zS) with the 1100×1×4 construction. The cords were each provided with a stripping preparation and coated with an adhesive.

[0039] In all the drive belts tested, the tension strand density in the drive belt was 105 tension strands per 100 mm of belt width. Drive belts of different width were cut off the original tube, and the cut edges were assessed visually. The length of the drive belts was about 1200 mm in each case. The drive belts were also tested for dynamic lifetime in a mild hybrid test and a constant high-load test, and the resistance to unwinding of the tension strands was assessed.

[0040] Specifically, the drive belts were each subjected to a CT Mild Hybrid Test (6PK1196) and a Constant High Load Test (4PK1196).

[0041] In the mild hybrid test, the drive belt runs alternately with its top layer and its substructure mixture over six rolls having different diameters. The arrangement of the rolls in the mild hybrid test is shown in FIG. 2. A drive roll BSG applies a torque to the drive belt according to a fixed test cycle. Each test cycle comprises a start section, a boost section, a recuperation section and a baseload section. The total duration of the test cycle is 20 seconds. In the start and boost sections of the test cycle, the drive pulley has an accelerating effect on the belt, while it decelerates the belt in the recuperation section and in the baseload section.

[0042] The starting section is comparatively short, although a high torque of the generator pulley, especially about 60 Nm, acts on the drive belt. In the longer-lasting boost section, a lower torque acts on the belt. It is only about half of the starting torque, i.e. about 30 Nm. The recuperation section is of similar duration to the boost section, with a torque of about −30 Nm. The longest section is the baseload section, in which there is a constant torque of about −5 Nm. The ambient temperature during the mild hybrid test was set to 130° C.

[0043] In the constant high-load test, the drive belt runs alternately with its top layer and its substructure mixture over four rolls, with a drive roll at a speed of rotation of 5000 revolutions per minute applying a constant torque of 20 Nm. The arrangement of the rolls in the mild hybrid test is shown in FIG. 3. The ambient temperature during the constant high-load test was set to 100° C.

[0044] All drive belts were subjected to the same tests, with repetition of the test cycle until the drive belt tore or the tension strands were unwound from the drive belt or the substructure of the belt had at least 3 partial breaks or a loss of material. The test results are apparent from the table below, with the drive belt having test cord No. 6 being constructed in accordance with the invention. These drive belts achieved the best results overall. This is clear from the ultimate service lives in the different tests. The comparative drive belts could not achieve such long test service lives.

TABLE-US-00001 Twist Twist CT Mild Constant High First Final factor factor Hybrid Test, Load Test, twist twist of first of final 6PK1196, 4Pk1196, Visual Experimental TM1 TM2 twist twist Quotient service life service life assessment cord [m.sup.−1] [m.sup.−1] TM1 TM2 TM1/TM2 [h] [h] of cut edge Target >150 h >70 h service life 1 270 270 2.96 5.91 0.50 74 . . . 84 h 38 . . . 48 h + 2 300 105 3.28 2.30 1.43 74 . . . 94 h 124 . . . 163 h − 3 360 126 3.94 2.76 1.43 50 . . . 291 h 161 . . . 182 h ∘ 4 360 200 3.94 4.38 0.90 — 58 . . . 64 h + 5 450 100 4.93 2.19 2.25 164 . . . 400 h 8 . . . 63 h − 6 450 160 4.93 3.50 1.41 224 . . . 421 h 74 . . . 184 h + 7 450 190 4.93 4.16 1.18 44 . . . 96 h 1 . . . 20 h +

[0045] Especially experimental cord No. 5, which had a twist factor ratio according to WO 2006/102641 A1, shows a distinct variance in the ultimate service lives in the two tests, especially in the constant high-load test, and a belt edge with a high level of fluff. The drive belt of the invention (experimental cord No. 6) achieves longer ultimate service lives both in the mild hybrid test and in the constant high-load test. Moreover, the drive belt thus configured shows a cut edge with a very low level of fluff.

LIST OF REFERENCE SIGNS

(Part of the Description)

[0046] 1 Drive belt [0047] 2 Top layer [0048] 3 Tension strand [0049] 4 Substructure mixture [0050] 5 Rib [0051] 6 Groove [0052] 7 Force transmission surface [0053] 8 Coating