Failure mode for HVAC system

• US 20050159846A1
• Filed: 04/14/2004
• Published: 07/21/2005
• Est. Priority Date: 01/20/2004
• Status: Active Grant

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Shah, Rajendra K., Van Ostrand, William F.
• Granted Patent: US 7,216,016 B2
• Time in Patent Office: Days
• US Class Current: 700/276
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/32 Responding to malfunctions or emergencies
• CPC Class Codes: F24F 11/49 ensuring correct operation, e.g. by trial operation or configuration checks
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/65 for selecting an operating mode
• CPC Class Codes: G05B 23/0291 Switching into safety or degraded mode, e.g. protection and supervision after failure

Abstract

A HVAC system provides a central control which detects failed stage(s); removes the failed stage(s) from the staging sequence used by the controller; and later checks the failed stage periodically to see if the failed stage has become functional so that the no properly operational stage is returned to a staging sequence. The central control detects the failed stages and/or components by direct communication with the failed stages and/or components and/or by monitoring a temperature of a controlled area to determine if any particular stage is operating properly.

Claims

1. A method of controlling an HVAC system comprising the steps of:

(1) detecting whether a stage of an HVAC component is a failed stage; and

(2) removing the failed stage detected in said step (1) from a staging sequence.

2. A method as recited in claim 1, wherein said step (1) further comprises the step of:

communicating a health status of the HVAC component to a controller.

3. A method as recited in claim 1, wherein said step (1) further comprises the step of:

determining whether a communication link exists between the HVAC component and a controller.

4. A method as recited in claim 1, wherein said step (1) further comprises the step of:

communicating a temperature of a controlled area to a controller.

5. A method as recited in claim 1, wherein said step (1) further comprises the step of:

(a) monitoring a temperature of a controlled area;

(b) inferring whether the stage has failed from a relationship between the temperature of the controlled area and a time period.

6. A method as recited in claim 5, wherein said step (b) further comprises the step of:

(a) monitoring a slope of the relationship between the temperature of the controlled area and the time period.

7. A method as recited in claim 5, wherein said step (b) further comprises the step of:

(a) monitoring a rate of change of a relationship between the temperature of the controlled area and the time period.

8. A method as recited in claim 1, further comprising the steps of:

(a) periodically attempting communication with the failed stage;

(b) identifying whether the failed stage has become functional; and

(c) returning the failed stage to the staging sequence in response to said step (b).

9. A method as recited in claim 8, wherein said step (b) further comprising the step of:

(i) identifying a positive communication with the failed stage.

10. A method of controlling an HVAC system comprising the steps of:

(1) monitoring a rate of change of a relationship between a temperature of a controlled area and a time period for a first stage of an HVAC component;

(2) determining whether the first stage is a failed stage in response to said step (1); and

(3) removing the failed stage determined in said step (2) from a staging sequence.

11. A method as recited in claim 10, wherein said step (1) further comprises the step of:

determining whether the rate of change is greater than a prior rate of change of a prior stage of the HVAC component.

12. A method as recited in claim 10, wherein said step (1) further comprises the step of:

comparing the rate of change to a stored rate of change for the first stage.

13. A method as recited in claim 12, further comprises the step of:

inputting the stored rate of change into a controller which communicates with the HVAC component.

14. A method as recited in claim 12, further comprises the step of:

learning the stored rate of change over a multiple of cycles of the first stage.

15. A method as recited in claim 14, further comprises the step of:

determining a configuration of the HVAC component in response to learning the stored rate of change of a multiple of stages comprising the first stage.

16. A method as recited in claim 14, further comprises the step of:

incorporating a gain into a control algorithm for the first stage in response to the stored rate of change to obtain a desired rate of change.

17. A method as recited in claim 14, further comprises the step of:

relating a recovery time period to the stored rate of change to achieve a designated temperature at a desired time.

18. A method of controlling an HVAC system comprising the steps of:

(1) monitoring a first rate of change of a first relationship between a temperature of a controlled area and a first time period for a first stage of an HVAC component;

(2) monitoring a second rate of change of a second relationship between the temperature of the controlled area and a second time period for a second stage of the HVAC component;

(3) determining whether the second stage is a failed stage in response to said steps (1) and (2); and

(4) removing the failed stage determined in said step (3) from a staging sequence.

19. A method as recited in claim 18, further comprises the step of:

determining a configuration of the HVAC component in response to said steps (1) and (2).

20. A method as recited in claim 18, wherein said step (3) further comprises the step of:

determining if the second rate of change is less than the first rate of change; and

determining that the second stage is a failed stage.