Drive belt

Abstract

A drive belt having a main body formed of an elastomeric material, preferably a v-belt or v-ribbed belt, the drive belt including a top layer as belt backing, a power transmission zone having two or more tensile strands as strength members, and also a substructure optionally provided with some profiling preferably having a v-shape or a v-rib profile. The strength members are formed of cords made of mutually twisted plies (final twist), the plies being in turn twisted out of individual yarns (first twist). The cords consist essentially of polyethylene terephthalate (PET) and of two plies, the number of turns introduced into the plies twisted into a cord (final twist) and the number of turns introduced into the yarns twisted into a ply (first twist) differing by not more than 10 turns per meter (t/m).

Claims

1. A drive belt comprising: a main body formed of an elastomeric material; a top layer configured as belt backing; the drive belt including a power transmission zone having two or more tensile strands as strength members; a substructure; said strength members being formed of cords having mutually twisted plies (final twist), said plies being in turn twisted out of individual yarns (first twist); and, said cords consisting essentially of polyethylene terephthalate (PET) and of two plies, a number of turns introduced into the plies twisted into a cord (final twist) and the number of turns introduced into the yarns twisted into a ply (first twist) differing by not more than 10 turns per meter (t/m).

2. The drive belt of claim 1, wherein said number of turns is between 60 and 175 t/m.

3. The drive belt of claim 1, wherein said number of turns is between 90 and 140 t/m.

4. The drive belt of claim 1, wherein said cords have a linear density (total linear density) from 3650 to 9000 dtex.

5. The drive belt of claim 1, wherein said cords have a linear density (total linear density) from 6200 to 7000 dtex.

6. The drive belt of claim 1, wherein the cords have been drawn/preoriented such that the shrinkage of the cords at 150 C. is greater than 2% and the shrink force is between 0.0018 and 0.0051 N/dtex.

7. The drive belt of claim 1, wherein said cords have been drawn/preoriented such that the shrinkage of the cords at 150 C. is greater than 2% and the shrink force is between 0.0022 and 0.0038 N/dtex.

8. The drive belt of claim 1, wherein a cord s has been subjected to a stiffening treatment with at least one of isocyanates and blocked isocyanates.

9. The drive belt of claim 1, wherein said elastomeric material consists of peroxidically crosslinked EPDM or EPM.

10. The drive belt of claim 1, wherein: said cords define a cord plane; and, said cords comprise not less than 80% of said cylindrical cord plane.

11. The drive belt of claim 1, wherein the drive belt is a v-belt or a v-ribbed belt.

12. The drive belt of claim 1, wherein said substructure is provided with profiling.

13. The drive belt of claim 12, wherein said substructure has a v-shape or a v-rib profile.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(1) In an advantageous embodiment, the number of turns is between 60 and 175 t/m, preferably between 90 and 140 t/m. The advantage of this embodiment consists in imparting as many turns as are needed for the intended use. However, the choice of final twist should not be too low, or the cuttability of the cords degrades.

(2) In a further advantageous embodiment, the cords have a linear density (total linear density) of from 3650 to 9000 dtex, especially from 6200 to 7000 dtex. A linear density at this level gives the best results for the abovementioned uses in the automotive sector and is obtainable at acceptable cost.

(3) In a further advantageous embodiment, the cords have been drawn/preoriented such that the shrinkage of the cords at 150 C. is greater than 2% and the shrink force is between 0.0018 and 0.0051 N/dtex, preferably between 0.0022 and 0.0038 N/dtex. The effect of such an embodiment is that the cords scarcely lengthen in service.

(4) The hot-shrink force and the hot shrinkage are determined in oil.

(5) To determine the hot-shrink force, a cord is tensioned, along a length of 800 mm at a pre-load of 0.2 cN/tex of the total linear density, between two stationary clamps and then immersed for 3 min in a hot bath at 150 C. and then the developing shrink force is determined. In the case of an 110023 dtex cord, the pre-load amounts to 132 cN, that is, 1.3 N.

(6) To determine the hot shrink or shrinkage, a cord is firmly clamped at one end and put under a constant pre-load of 0.2 cN/tex of the total linear density at the other end. An 800 mm sector of the cord tensioned with the pre-load is immersed for 3 min in a hot bath of 150 C. and the shrinkage of the cord at the pre-tension mentioned is determined.

(7) In a further advantageous embodiment to improve the cuttability of the cords, the cord has been subjected to a stiffening treatment with isocyanates or blocked isocyanates.

(8) In a further advantageous embodiment, the drive belt consists of peroxidically crosslinked EPDM or EPM. These materials are notable for high thermal stability and therefore will embrittle less and thereby attain a very high level of abrasion resistance.

(9) In a further advantageous embodiment, the cord comprises not less than 80% of the cylindrical cord plane, that is, the proportion of the gaps between the cords/cord coils amounts to less than 20% of the cylinder area defined by the cord plane. Such an embodiment prevents the cords developing any uncoiling tendency in the event of a high or excessive load.

(10) The example described hereinafter shows a v-ribbed belt configured according to the present invention. To this end, a direct-cabling machine, which makes it possible to twist the plies and the cord in one operation, was used to produce a directly cabled PET cord having the construction 3300 dtex2 (125/125 t/m) having a shrinkage force of 21 N (0.0032 N/dtex), and the cord was vulcanized into a V-ribbed belt whose mixture consisted of peroxidically crosslinked EPDM. Using a direct-cabling machine, which makes it possible to twist the plies and the cord in one operation, improves the economics of cord production.

(11) This v-ribbed belt thus constructed was tested to a standard catalog of specifications. Absolutely no disadvantages were found versus v-ribbed belts having tensile strands of cords having a larger number of plies. The drive belt constructed according to the invention behaved no different from the drive belt having standard cords 1100 dtex23 (150/125 t/m) with a hot-shrink force of 20 N, which is twisted together conventionally.

(12) It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.