Low modulus belt for automotive applications
View Patent ↗A low modulus drive belt for an automotive accessory drive system is disclosed that allows for relatively high elongation during installation and that maintains a relatively high percentage of its install tension throughout the useful life of the belt. In addition, an automotive accessory drive system is taught that utilizes such a belt as is a method for constructing such a belt. According to one aspect an accessory drive system for an automobile is provided that includes: (a) a drive pulley; (b) an accessory pulley operatively coupled to an accessory drive shaft; and (c) an endless drive belt engaged between the drive pulley and the accessory pulley, where the drive belt includes an endless band of rubber composite material having a plurality of circumferentially extending an axially aligned polyamide 6.6 twisted cords formed therewithin.
1. A multiple-pulley accessory drive system for an automobile, comprising:
a drive pulley;
at least one accessory pulley operatively coupled to an accessory drive shaft, the drive pulley and accessory pulley having a nominal drive length therebetween; and
an endless drive belt engaged between the drive pulley and the accessory pulley, the drive belt including an endless band of rubber composite material having a plurality of circumferentially extending and axially aligned, polyamide 6.6 twisted cords formed therewithin and having a tensile modulus per width of about 400 to 1500 N/mm.
2. The multiple-pulley accessory drive system 1 wherein the tensile modulus per width is about 400 to 1200 N/mm.
3. The multiple-pulley accessory drive system 2 wherein the tensile modulus per width is about 600 to 1000 N/mm.
4. The multiple-pulley accessory drive system of claim 3 , wherein the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2% to approximately 3% lower than the nominal drive length of the accessory drive system.
5. The multiple-pulley accessory drive system of claim 4 , wherein the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2% to approximately 2.3% lower than the nominal drive length of the accessory drive system.
6. The multiple-pulley accessory drive system of claim 4 , wherein the axial distance between the cords is approximately 0.8 mm to approximately 1.0 mm.
7. The multiple-pulley accessory drive system of claim 6 , wherein each twisted cord includes one or more cord yarns twisted together.
8. The multiple-pulley accessory drive system of claim 7 , wherein each twisted cord includes a pair of cord strands twisted together.
9. The multiple-pulley accessory drive system of claim 4 , wherein the twisted cords are axially distributed at a distribution of approximately 26 to approximately 30 of the twisted cords per inch.
10. The multiple-pulley accessory drive system of claim 4 , wherein the operational torque of the accessory drive system is less than, or equal to approximately 2.7 N-m (2 ft-lb).
11. The multiple-pulley accessory drive system of claim 10 , wherein the accessory is an automotive water pump and the accessory pulley is operatively coupled to a drive shaft of the water pump.
12. The multiple-pulley accessory drive system of claim 4 , wherein the accessory drive system is a two-pulley accessory drive system.
13. The multiple-pulley accessory drive system of claim 1 , wherein the endless drive belt has a tensile modulus of at least approximately 7,000 N/mm/mm (1575 lbf/in/in).
14. The multiple-pulley accessory drive system of claim 13 , wherein the endless drive belt has a tensile modulus of approximately 7,800 N/mm/mm (1750 lbf/in/in) to approximately 8,500 N/mm/mm (1910 lbf/in/in).
15. A multiple-pulley accessory drive system for an automobile, comprising:
a drive pulley;
at least one accessory pulley operatively coupled to an accessory drive shaft, the drive pulley and accessory pulley having a nominal drive length therebetween; and
an endless drive belt engaged between the drive pulley and the accessory pulley, the drive belt including an endless band of rubber composite material having a plurality of circumferentially extending and axially aligned cords formed therewithin;
wherein the endless drive belt has a tensile modulus of at least approximately 7000 N/mm/mm (1575 lbf/in/in).
16. The multiple-pulley accessory drive system of claim 15 , wherein the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2% to approximately 3% lower than the nominal drive length of the accessory drive system.
17. The multiple-pulley accessory drive system of claim 16 , wherein the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2% to approximately 2.3% lower than the nominal drive length of the accessory drive system.
18. The multiple-pulley accessory drive system of claim 17 , wherein the cords are polyamide twisted cords.
19. The multiple-pulley accessory drive system of claim 15 , wherein the operational torque of the accessory drive system is less than, or equal to approximately 2.7 N-m (2 ft-lb).
20. The multiple-pulley accessory drive system of claim 19 , wherein the accessory is an automotive water pump and the accessory pulley is operatively coupled to a drive shaft of the water pump.
21. The multiple-pulley accessory drive system of claim 20 , wherein the accessory drive system is a two-pulley accessory drive system.
22. The multiple-pulley accessory drive system of claim 15 , wherein the endless drive belt has a tensile modulus of approximately 7,800 N/mm/mm (1750 lbf/in/in) to approximately 8,500 N/mm/mm (1910 lbf/in/in).
23. The multiple-pulley accessory drive system of claim 22 , wherein the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2% to approximately 3% lower than the nominal drive length of the accessory drive system.
24. The multiple-pulley accessory drive system of claim 23 , wherein the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2% to approximately 2.3% lower than the nominal drive length of the accessory drive system.
25. The multiple-pulley accessory drive system of claim 24 , wherein the cords are polyamide twisted cords.
26. The multiple-pulley accessory drive system of claim 15
wherein the endless drive belt has a tensile modulus of approximately 8500 N/mm/mm (1910 lbf/in/in).
27. The multi-pulley drive system, of claim 4 wherein the drive belt is adapted to be manually stretched on the plurality of pulley at an install tension, and the drive belt maintains at least approximately 40% of the install tension throughout a useful life of the drive belt.
28. The multi-pulley drive system of claim 27 , wherein the drive belt maintains at least approximately 40% to approximately 60% of the install tension throughout the useful life of the drive belt.
29. A method for fabricating an accessory drive belt, comprising the steps of:
applying at least a layer of cover material to an outer circumferential surface of a drum;
applying at least a first layer of cushion stock rubber material to the drum over the cover layer;
winding a polyamide 6.6 twisted cord to the drum over the first layer of cushion stock;
applying a layer of relatively strong and wear resistant, fiber loaded, rubber material to the drum over the polyamide 6.6 twisted cord;
curing multiple layers together into a cured sleeve of belt composite material;
cutting the cured sleeve into a plurality of endless belts; and
turning the endless belts inside-out for use as an accessory drive belt;
wherein the polyamide 6.6 twisted cord is wound in the winding step at approximately 13 N (3 lbf.) to approximately 15.5 N (3.5 lbf.).