Conveyor belt rip detection system with microwire sensor

1. A conveyor belt comprising (1) an elastomeric body having a load carrying surface and a parallel pulley engaging surface; (2) a reinforcement ply disposed within the elastomeric body; and (3) a rip detection sensor in the form of a microcoil sensor wire which is configured in an endless loop, wherein the microcoil sensor wire is comprised of an elastomeric core having an electrically conductive wire spirally wrapped around the elastomeric core, wherein the microcoil wires can stretch with the elastomeric core and wherein the elastomeric core has a higher elongation than the elastomeric body of the conveyor belt, and wherein the electrically conductive wire of the microcoil sensor wire is not mechanically bound to the elastomeric body of the conveyor belt.

2. The conveyor belt as specified in claim 1 wherein the elastomeric core of the microcoil sensor wire is comprised of an insulating elastic polymer selected from the group consisting of natural rubber, polyurethane-polyurea copolymer rubbers, synthetic polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, and ethylene-propylene-diene monomer rubber.

3. The conveyor belt as specified in claim 1 wherein the electrically conductive wire is comprised of a highly conductive copper alloy having a composition selected from the group consisting of (A) 0.2 to 0.6 weight percent cadmium and 0.2 to 0.6 weight percent chromium with the balance of the alloy being copper and (B) 1 to 4 weight percent nickel and 0.25 to 0.5 weight percent beryllium with the balance of the alloy being copper.

4. The conveyor belt as specified in claim 1 wherein the electrically conductive wire is coated with a metal selected from the group consisting of nickel, tin, and silver.

5. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire is not shielded.

6. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire is shielded with a polymeric electrical insulator.

7. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire has an elongation to break of at least about 150%.

8. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire has an elongation to break of at least 200%.

9. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire has an elongation to break which is within the range of 200% to 500%.

10. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire has a pitch of between 1 to 4 conductor diameters and has a coil diameter of which is within the range of 0.025 to 0.175 inches.

11. The conveyor belt as specified in claim 10 wherein the endless loop is arranged using the microcoil wire in a signal inverting configuration wherein the microcoil sensor wire crosses itself in at least one crossing place by crossing through itself such that the microcoil sensor wire resides substantially in a single plane throughout the sensor including the crossing places.

12. The conveyor belt as specified in claim 11 which is further comprised of a means for preventing short-circuiting or mechanical interaction of the conductor at the crossing places.

13. The conveyor belt as specified in claim 1 wherein the endless loop is arranged in a signal non-inverting configuration wherein the microcoil sensor wire does not cross itself and resides substantially in a single plane throughout the sensor.

14. The conveyor belt as specified in claim 1 wherein the microcoil sensor wire has a pitch of between 1 to 4 conductor diameters and has a coil diameter of between 0.05 to 0.1 inches.

15. The conveyor belt as specified in claim 1 wherein the conveyor belt includes a top load bearing surface, a middle carcass layer, and a pulley cover, characterized in that the sensor is embedded within the bearing surface, the carcass layer or the pulley cover.

16. The conveyor belt as specified in claim 1 characterized in that the rip detection sensor includes loops configured for use in connection with a belt rip detection system which includes external transmitter/exciters, and receiver/detectors.

17. A conveyor system with a rip detection system which is comprised of the conveyor belt as specified in claim 1 ; a drive motor; a drive pulley which is driven by the drive motor; a following pulley; a transmitter which is coupled with the sensor loops; and an external receiver which is coupled with the sensor loops.

18. In a conveyor belt including (1) an elastomeric body having a load carrying surface and a parallel pulley engaging surface; (2) a reinforcement ply disposed within the elastomeric body; and (3) a rip detection sensor in the form of a microcoil sensor wire which is configured in an endless loop, the improvement which comprises the microcoil sensor wire having an elastomeric core with an electrically conductive wire spirally wrapped around said elastomeric core, wherein the microcoil wires can stretch with the elastomeric core and wherein the elastomeric core has a higher elongation than the elastomeric body of the conveyor belt.

19. The conveyor belt as specified in claim 18 wherein the microcoil sensor wire has a pitch of between 1 to 4 conductor diameters and has a coil diameter of between 0.025 to 0.175 inches; wherein the conveyor belt includes a top load bearing surface, a middle carcass layer, and a pulley cover, characterized in that the sensor is embedded within the load bearing surface, the carcass layer or the pulley cover; and wherein the rip detection sensor loops are configured in non-inverted or inverted constructions for use in connection with a belt rip detection system which includes external transmitter/exciters and receiver/detectors.

20. The conveyor belt as specified in claim 1 wherein the electrically conductive wire is comprised of a highly conductive copper alloy consisting of 0.2 to 0.6 weight percent cadmium and 0.2 to 0.6 weight percent chromium with the balance of the alloy being copper.