IP Library › Granted Patent US 11,268,720

Granted Patent B2

US 11,268,720 · App. 16/806,258 · Granted Mar 8, 2022

HVAC system fault prognostics and diagnostics

Inventors: Amita Brahme (Dallas, TX); Umesh Gokhale (Irving, TX)

Assignee: Lennox Industries Inc.

F24F11/38 F24F2140/12

View Patent ↗

Loading inventors, assignments & file history…

Monitor This Case

Get email alerts when status or documents change.

Order Certified Copies

Most orders are placed with the USPTO same day — all within 24 business hours.

Order via The Patent Place →

Pre-filled with this patent's details

Quick Facts

Patent No.: US 11,268,720
App. No.: 16/806,258
Granted: Mar 8, 2022
Kind: B2

External Links

USPTO Patent Center↗ Full Patent PDF↗

Abstract

A controller of an HVAC system monitors a suction-side property and a liquid-side property over a period of time. The controller determines whether the suction-side property has an increasing or decreasing trend over the period of time. The controller determines whether the liquid-side property has an increasing or decreasing trend. In response to determining that both the suction-side property and the liquid-side property have an increasing trend over the period of time, a fan fault is detected. In response to determining that the suction-side property has a decreasing trend and the liquid-side property has an increasing trend over the period of time, a blockage of a refrigerant conduit subsystem is detected. In response to determining that both the suction-side property and the liquid-side property have a decreasing trend over the period of time, a blower fault is detected.

Claims (171)

1. A heating, ventilation and air conditioning (HVAC) system comprising:

a refrigerant conduit subsystem configured to allow a flow of refrigerant through the HVAC system;

a compressor configured to receive refrigerant and direct the refrigerant to flow through a refrigerant conduit subsystem;

a condenser configured to receive the refrigerant and allow heat transfer between the received refrigerant and a first flow of air across the condenser;

a fan configured to provide the first flow air across the condenser;

an evaporator configured to receive the refrigerant and allow heat transfer between the refrigerant and a second flow air across the evaporator;

a blower configured to provide the second flow of air across the evaporator;

a suction-side sensor positioned and configured to measure a suction-side property associated with refrigerant provided to an inlet of the compressor, wherein the suction-side property comprises at least one of a suction-side temperature or a suction-side pressure;

a liquid-side sensor positioned and configured to measure a liquid-side property associated with the refrigerant provided from an outlet of the compressor, wherein the liquid-side property comprises at least one of a liquid-side temperature or a liquid-side pressure; and

a controller communicatively coupled to the suction-side sensor and the liquid-side sensor, the controller configured to:

monitor the suction-side property over a period of time;

monitor the liquid-side property over the period of time;

determine whether the suction-side property has an increasing or decreasing trend over the period of time;

determine whether the liquid-side property has an increasing or decreasing trend;

in response to determining that both the suction-side property and the liquid-side property have an increasing trend over the period of time, determine that a fan fault is detected;

in response to determining that the suction-side property has a decreasing trend and the liquid-side property has an increasing trend over the period of time, determine that a blockage of the refrigerant conduit subsystem is detected; and

in response to determining that both the suction-side property and the liquid-side property have a decreasing trend over the period of time, determine that a blower fault is detected.

2. The system of claim 1 , wherein the suction-side property is a suction-side pressure of the refrigerant measured at a position proximate the inlet of the compressor and the liquid-side property is a liquid-side pressure of the refrigerant measured at a position proximate the outlet of the compressor.

3. The system of claim 1 , the controller further configured to:

determine whether the liquid-side pressure has an increasing or decreasing trend by:

determining a first rate of change of the liquid-side property over the period of time;

in response to determining that the first rate of change is positive and is greater than a first threshold value, determining that the liquid-side property has an increasing trend; and

in response to determining that the positive first rate of change is positive and is not greater than the first threshold value, determining that the liquid-side property does not have an increasing trend;

in response to determining the first rate of change is negative and is less than a second threshold value, determining that the liquid-side property has a decreasing trend; and

in response to determining that the first rate of change is negative and is not less than the second threshold value, determining that the liquid-side property does not have a decreasing trend; and

determine whether the suction-side pressure has an increasing or decreasing trend by:

determining a second rate of change of the suction-side property over the period of time;

in response to determining that the second rate of change is positive and is greater than a third threshold value, determining that the suction-side property has an increasing trend;

in response to determining that the second rate of change is positive and is not greater than the third threshold value, determining that the suction-side property does not have an increasing trend; and

in response to determining the second rate of change is negative and is less than a fourth threshold value, determining that the suction-side property has a decreasing trend; and

in response to determining that the second rate of change is negative and is not less than the fourth threshold value, determining that the suction-side property does not have a decreasing trend.

4. The system of claim 1 , the controller further configured to:

determine whether the liquid-side property has an increasing or decreasing trend by:

determining a first value of the liquid-side property at a first time stamp during the period of time;

determining a second value of the liquid-side property at a second time stamp during the period of time, wherein the second time stamp corresponds to a predefined time after the first time stamp;

determining a liquid-side difference between the second value and the first value;

in response to determining that the liquid-side difference is positive and greater than a first threshold value, determining that the liquid-side property is increasing; and

in response to determining that the liquid-side difference is negative and less than a second threshold value, determining that the liquid-side property is decreasing; and

determine whether the suction-side property has an increasing or decreasing trend by:

determining a third value of the suction-side property at the first time stamp during the period of time;

determining a fourth value of the suction-side property at the second time stamp during the period of time;

determining a suction-side difference between the fourth value and the third value;

in response to determining that the suction-side difference is positive and greater than a third threshold value, determining that the suction-side property is increasing; and

in response to determining that the suction-side difference is negative and less than a fourth threshold value, determining that the suction-side property is decreasing.

5. The system of claim 1 , the controller further configured to:

determine whether the liquid-side property has an increasing or decreasing trend by:

determining, for each of at least three sequential intervals of time during the period of time, a first value of the liquid-side property at a start of the interval of time;

determining, for each of the at least three sequential intervals of time, a second value of the liquid-side property at an end of the interval of time;

determining, for each of the at least three sequential intervals of time, a liquid-side difference between the second value and the first value for the interval of time;

in response to determining that, for each of the at least three sequential intervals of time, the liquid-side difference is positive and greater than a first threshold value, determining that the liquid-side property is increasing; and

in response to determining that, for each of the at least three sequential intervals of time, the liquid-side difference is negative and less than a second threshold value, determining that the liquid-side property is decreasing; and

determine whether the suction-side property has an increasing or decreasing trend by:

determining, for each of the at least three sequential intervals of time, a third value of the suction-side property at the start of the interval of time;

determining, for each of the at least three sequential intervals of time, a fourth value of the suction-side property at the end of the interval of time;

determining, for each of the at least three sequential intervals of time, a suction-side difference between the fourth value and the third value for the interval of time;

in response to determining that, for each of the at least three sequential intervals of time, the suction-side difference is positive and greater than a third threshold value, determining that the suction-side property is increasing; and

in response to determining that, for each of the at least three sequential intervals of time, the suction-side difference is negative and less than a fourth threshold value, determining that the suction-side property is decreasing.

6. The system of claim 1 , the controller further configured to:

in response to determining that the fan fault is detected, cause communication of a fan-malfunction alert;

in response to determining that the blockage of the refrigerant conduit subsystem is detected, cause communication of a conduit-blockage alert;

in response to determining that the blower fault is detected, cause communication of a blower-malfunction alert.

7. The system of claim 1 , the controller further configured to, in response to, in response to determining that the fan fault is detected, stop operation of the HVAC system.

8. A method of operating heating, ventilation and air conditioning (HVAC) system, the method comprising:

monitoring, over a period of time, a suction-side property associated a refrigerant provided to an inlet of a compressor of the HVAC system, wherein the suction-side property comprises at least one of a suction-side temperature or a suction-side pressure;

monitoring, over the period of time, a liquid-side property associated with the refrigerant provided from an outlet of the compressor, wherein the liquid-side property comprises at least one of a liquid-side temperature or a liquid-side pressure;

determining whether the suction-side property has an increasing or decreasing trend over the period of time;

determining whether the liquid-side property has an increasing or decreasing trend;

in response to determining that both the suction-side property and the liquid-side property have an increasing trend over the period of time, determining that a fan fault is detected, wherein the fan fault is associated with a malfunction of a fan of the HVAC system;

in response to determining that the suction-side property has a decreasing trend and the liquid-side property has an increasing trend over the period of time, determining that a blockage of the refrigerant conduit subsystem is detected; and

in response to determining that both the suction-side property and the liquid-side property have a decreasing trend over the period of time, determining that a blower fault is detected, wherein the blower fault is associated with a malfunction of a blower of the HVAC system.

9. The method of claim 8 , wherein the suction-side property is a suction-side pressure of the refrigerant measured at a position proximate the inlet of the compressor and the liquid-side property is a liquid-side pressure of the refrigerant measured at a position proximate the outlet of the compressor.

10. The method of claim 8 , further comprising:

determining whether the liquid-side pressure has an increasing or decreasing trend by: