Resistance-based monitoring system and method

• US 9,423,369 B2
• Filed: 09/01/2010
• Issued: 08/23/2016
• Est. Priority Date: 09/01/2010
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Fargo, Richard N., Keyo, Peter
• Primary Examiner(s): Nguyen, Tung X
• Assistant Examiner(s): Pothen, Feba
• Application Number:
  US13/820,387
• Publication Number:
  US 20130162266A1
• Time in Patent Office: 2,183 Days
• US Class Current: 1/1
• CPC Class Codes: B66B 7/1223 by analysing electric variables
• CPC Class Codes: D07B 1/145 comprising elements for indicating or detecting the rope or cable status
• CPC Class Codes: G01N 27/20 Investigating the presence of flaws

Abstract

A monitoring system for a support structure is provided. The monitoring system may include a resistance circuit coupled to the support structure, and an interface circuit coupled to the resistance circuit. The resistance circuit may include a first set of resistors and a second set of resistors, wherein the second set of resistors is configured to provide a reference voltage. The interface circuit may include one or more comparators, wherein each comparator is configured to compare a voltage across at least one of the resistors with the reference voltage and generate an output signal corresponding to the comparison. The interface circuit may be configured to continuously monitor an effective resistance of the support structure based on the output signals.

Claims

1. A monitoring system for a tensile support structure, comprising:

a voltage input node to supply a voltage, the voltage applied to the tensile support structure;

a resistance circuit connected to an effective resistance of the tensile support structure, the resistance circuit having a first set of resistors and a second set of resistors, the second set of resistors being coupled to the voltage input and configured to provide a reference voltage;

the first set of resistors including at least two resistors in series and coupled to the voltage input, the at least two resistors in series being in parallel with the effective resistance of the tensile support structure; and

an interface circuit directly coupled to the resistance circuit and having two or more comparators, each comparator being configured to directly compare a voltage across at least one of the at least two resistors with the reference voltage and generate an output signal corresponding to the comparison, the interface circuit being configured to monitor the effective resistance of the tensile support structure based on the output signals.

2. The monitoring system of claim 1, wherein the interface circuit is configured to continuously or intermittently monitor the effective resistance of the tensile support structure based on the output signals.

3. The monitoring system of claim 1, wherein at least one of the second set of resistors is adjustable so as to as approximate the effective resistance of the tensile support structure during calibration.

4. The monitoring system of claim 1, wherein a plurality of the second set of resistors is adjustable and configured in series such that the maximum resistance of each resistor is successively decreased.

5. The monitoring system of claim 1, wherein the resistance of each of the second set of resistors is different and enabled via a dual in-line package (DIP) switch.

6. The monitoring system of claim 5, wherein the DIP switches may be sealed upon calibration.

7. The monitoring system of claim 1, wherein the interface circuit is configured to control a relay based on the output signals.

8. The monitoring system of claim 1, wherein the resistance circuit further includes at least one temperature-dependent resistor having a variable resistance that is dependent on temperature.

9. The monitoring system of claim 1, wherein the interface circuit includes one or more light emitting diodes (LEDs) configured to receive the output signals and indicate one or more operational states of the tensile support structure based on the output signals.

10. The monitoring system of claim 9, wherein each operational state is indicative of the tensile support structure being in at least one of a shorted state, a normal state, a low-wear state, a high-wear state, an end-of-life state, and an open-circuit state.

11. A method for calibrating a resistance-based monitoring system for a tensile support structure, the method comprising:

providing a resistance circuit connected to an effective resistance of the tensile support structure, the resistance circuit having a first set of resistors and a second set of resistors disposed at least partially in parallel to the tensile support structure, the first set of resistors including at least two resistors in series and coupled to a voltage input, the at least two resistors in series being in parallel with the effective resistance of the tensile support structure;

generating a reference voltage across the second set of resistors;

comparing a voltage across at least one of the first set of resistors directly with the reference voltage; and

adjusting the reference voltage until an effective resistance of the tensile support structure is substantially matched by the resistance circuit;

wherein the comparing includes providing two or more comparators coupled to the resistance circuit, each comparator being configured to directly compare a voltage across at least one of the first set of resistors with the reference voltage and generate an output signal corresponding to the comparison; and

adjusting the resistance of the second set of resistors until the output signals indicate that the effective resistance of the tensile support structure is substantially matched by the resistance circuit.

12. The method of claim 11 further comprising:

providing one or more light emitting diodes (LEDs) coupled to the comparators, each LED being configured to receive the output signals and illuminate based on the comparisons; and

adjusting the resistance of the second set of resistors until an illumination of the LEDs indicates that the effective resistance of the tensile support structure is substantially matched by the resistance circuit.

13. The method of claim 11, wherein each of the second set of resistors is connected in series and configured with a different maximum resistance being enabled via a dual in-line package (DIP) switch, each DIP switch being successively enabled or disabled until the effective resistance of the tensile support structure is substantially matched.

14. The method of claim 13 further comprising sealing the second set of resistors once the effective resistance of the tensile support structure is substantially matched.

15. A method for monitoring a tensile support structure, comprising:

providing a resistance circuit connected to an effective resistance of the tensile support structure, the resistance circuit having a first set of resistors and a second set of resistors disposed at least partially in parallel to the tensile support structure, -the first set of resistors including at least two resistors in series and coupled to a voltage input, the at least two resistors in series being in parallel with the effective resistance of the tensile support structure;

generating a reference voltage across the second set of resistors, the reference voltage corresponding to an initial effective resistance of the tensile support structure;

directly comparing a voltage across at least one of the first set of resistors with the reference voltage; and

determining at least one operational state of the tensile support structure based on the comparisons;

providing two or more comparators coupled to the resistance circuit, each comparator being configured to directly compare a voltage across at least one of the first set of resistors with the reference voltage and generate an output signal corresponding to the comparison;

providing one or more light emitting diodes (LEDs) coupled to the comparators, each LED being configured to receive the output signals and illuminate based on the comparisons; and

determining at least one operational state of the tensile support structure based on an illumination of the LEDs.

16. The method of claim 15, wherein the resistance of each of the second set of resistors is adjustable and enabled via a dual in-line package (DIP) switch.

17. The method of claim 15, wherein each operational state is indicative of the tensile support structure being in at least one of a shorted state, a normal state, a low-wear state, a high-wear state, an end-of-life state, and an open-circuit state.