Use of a transmission belt in oil and related transmission system
A fabric for transmission belts is described that is made entirely with polyaramid fibers. Furthermore, a transmission belt is provided that comprises a body made of a first elastomeric material, in which a plurality of resistant longitudinal filiform inserts is embedded, and a working surface covered in a covering fabric comprising polyaramid fibers in weft and warp yarns; advantageously, the transmission belt is a toothed belt. According to the present invention, in use, the belt is in continuous contact with oil or partially immersed in oil.
1. A belt for continuous contact with oil or immersion in an oil bath, said belt comprising;
a body made of a first elastomeric material,
a toothing,
a plurality of resistant longitudinal inserts embedded in the body of the belt, and
a back,
wherein said belt has a working surface and said working surface is covered with a covering fabric comprising weft and warp yarns, characterised in that said weft yarns comprise polyaramid, and said warp yarns consist of poly-meta-aramid.
2. The belt according to claim 1 , characterised in that said weft yarns are formed by an elastic yarn and by a first and second yarn.
3. The belt according to claim 2 , characterised in that said weft yarns are formed by poly-para-aramid.
4. The belt according to claim 3 , characterised in that said first yarn is a poly-para-aramid fibre yarn wound around said elastic yarn in a first direction and said second yarn is a poly-para-aramid fibre yarn wound in an opposite direction around said first yarn.
5. The belt according to claim 1 , characterised in that said transmission belt is a toothed belt.
6. The belt according to claim 1 , characterised in that said back is covered with said covering fabric.
7. The belt according to claim 1 , characterised in that said first elastomeric material is obtained from a diene monomer and a nitrile-group containing monomer.
8. The belt according to claim 7 , characterised in that said nitrile groups are in a percentage in the range between 33 and 51 percent by weight.
9. The belt according to claim 7 , characterised in that said first elastomeric material is selected from the group consisting of NBR, HNBR, XHNBR or mixtures thereof.
10. The belt according to claim 9 , characterised in that said first elastomeric material comprises a polymer containing an unsaturated carboxylic acid and/or a salt of an unsaturated carboxylic acid.
11. The belt according to claim 1 , characterised in that said fabric is subjected to a first treatment and to a second treatment.
12. The belt according to claim 11 , characterised in that said first treatment comprises polyisocyanates.
13. The belt according to claim 12 , characterised by comprising a third treatment.
14. The belt according to claim 13 , characterised in that said third treatment comprises an elastomer selected from the group consisting of NBR, HNBR, XHNBR or mixtures thereof.
15. The belt according to claim 13 , characterised by comprising a fourth treatment.
16. The belt according to claim 11 , characterised in that said second treatment comprises an adhesive.
17. A timing control system for a motor vehicle comprising at least one drive pulley, a driven pulley and means adapted to continuously maintain a belt according to claim 1 in contact with oil or immersed in oil.