Low modulus belt for automotive applications

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).

A two-pulley accessory drive system for an automobile, comprising:

• a drive pulley;
• an 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 approximately 8500 N/mm/mm (1910 lbf/in/in);
• and
• wherein the the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2.2% to approximately 2.3% lower than the nominal drive length between the drive pulley and the accessory pulley.

A multiple-pulley accessory drive system for an automobile, comprising:

• a drive pulley;
• an 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
• wherein the the circumferential length of the endless drive belt, before installation on the pulleys, is approximately 2.2% to approximately 2.3% lower than the nominal drive length of the accessory drive system.

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.).