U.S. patent application number 13/749831 was filed with the patent office on 2013-08-01 for hvac system fault root cause self-determination.
This patent application is currently assigned to Carrier Corporation. The applicant listed for this patent is Carrier Corporation. Invention is credited to Adeyemi A. Adepetu, Rajendra K. Shah.
Application Number | 20130197698 13/749831 |
Document ID | / |
Family ID | 48870946 |
Filed Date | 2013-08-01 |
United States Patent
Application |
20130197698 |
Kind Code |
A1 |
Shah; Rajendra K. ; et
al. |
August 1, 2013 |
HVAC System Fault Root Cause Self-Determination
Abstract
A method for self-determining a root cause of a system fault in
a heating, ventilation, and cooling (HVAC) system includes
receiving a fault message indicative of a fault condition in an
operating characteristic of the HVAC system; determining a causal
relationship between the fault condition and a predetermined list
of root causes associated with the fault condition; receiving
information indicative of operating conditions of the HVAC system;
and eliminating at least one root cause that is unrelated to the
fault condition in response to the receiving of the
information.
Inventors: |
Shah; Rajendra K.;
(Indianapolis, IN) ; Adepetu; Adeyemi A.; (Jamaica
Plain, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carrier Corporation; |
Farmington |
CT |
US |
|
|
Assignee: |
Carrier Corporation
Farmington
CT
|
Family ID: |
48870946 |
Appl. No.: |
13/749831 |
Filed: |
January 25, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61590934 |
Jan 26, 2012 |
|
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|
Current U.S.
Class: |
700/276 |
Current CPC
Class: |
F24F 11/32 20180101;
F24F 11/30 20180101; F24F 11/52 20180101 |
Class at
Publication: |
700/276 |
International
Class: |
F24F 11/00 20060101
F24F011/00 |
Claims
1. A method for self-determining a root cause of a system fault in
a heating, ventilation, and cooling (HVAC) system, comprising:
receiving a fault message indicative of a fault condition in an
operating characteristic of the HVAC system; determining a causal
relationship between the fault condition and a predetermined list
of root causes associated with the fault condition; receiving
information indicative of operating conditions of the HVAC system;
and eliminating at least one root cause that is unrelated to the
fault condition in response to the receiving of the
information.
2. The method of claim 1, wherein the receiving of the information
further comprises receiving sensor information substantially
contemporaneous with a time of the fault condition.
3. The method of claim 1, wherein the receiving of the information
further comprises receiving sensor information regarding historical
information of the HVAC system preceding the fault condition.
4. The method of claim 1, wherein the receiving of the information
further comprises receiving predetermined system parametric
information for one of a temperature control, humidity control, and
airflow control system.
5. The method of claim 1, further comprising operating the HVAC
system in a diagnostic mode to generate additional operating
information for the HVAC system, the operating information being
related to the fault condition.
6. The method of claim 1, further comprising presetting the HVAC
system to predefined parameters to eliminate additional root causes
from the predetermined list.
7. The method of claim 6, wherein the predefined parameters are
associated with the operating characteristic that generated the
fault condition,
8. The method of claim 1, further comprising receiving historical
information about the HVAC system and eliminating additional root
causes from the predetermined list responsive to the receiving of
the historical information.
9. The method of claim 1, wherein the controller comprises one of a
system controller associated with at least one environmental
control zone or one or more unit controllers associated with
respective temperature control, humidity control, and airflow
control systems.
10. The method of claim 1, further comprising providing to a user a
related root cause in response to the eliminating of the at least
one root cause that is unrelated .
11. The method of claim 10, wherein the providing of the at least
one root cause further comprises displaying the at least one root
cause on a touch screen display.
12. The method of claim 1, further comprising displaying a
prioritized list of the root causes based on at least one of a
predetermined historical information regarding the HVAC system,
cost information regarding at least one component of the HVAC
system, or a likelihood of the one or more of root causes based on
a combination of the historical information and the cost
information.
13. The method of claim 1, further comprising traversing a fault
tree model to identify the predetermined list of root causes.
14. The method of claim 1, further comprising transmitting to a
remote server information regarding a plurality of root causes
associated with the fault condition via a communication
network,
15. The method of claim 14, further comprising eliminating
additional root causes from the plurality of root causes responsive
to the transmitting of the information regarding the plurality of
root causes.
16. A method for self-determining a root cause of a system fault in
a heating, ventilation, and cooling (HVAC) system, comprising:
receiving a first list associated with a plurality of fault
conditions in the HVAC system; identifying a second list of root
causes associated with a particular fault condition of the
plurality of fault conditions; receiving information indicative of
operating conditions of the HVAC system; and eliminating at least
one root cause from the second list of root causes that is
unrelated to the particular fault condition in response to the
receiving of the information.
17. The method of claim 16, wherein the identifying of the second
list further comprises determining a causal relationship between
the second list of root causes associated with the particular fault
condition.
18-30. (canceled)
31. A programmable control unit for self-determining a root cause
in an HVAC system, comprising: a controller configured for
receiving a fault message indicative of a fault condition in an
operating characteristic of the HVAC system and for determining a
causal relationship between the fault condition and a predetermined
list of root causes associated with the fault condition; wherein
the controller receives information indicative of operating
conditions of the HVAC system; and wherein the controller
eliminates at least one root cause in response to the receiving of
the sensed information.
32-42. (canceled)
43. An environmental control system for an HVAC system, comprising:
a programmable control unit configured for establishing user
desired environmental control parameters for one or more control
zones; and at least one unit controller configured for storing
information indicative of at least one system parameter for a
control system, the at least one unit controller operatively
coupled to the programmable control unit; wherein the programmable
control unit or the unit controller is configured for receiving a
fault message indicative of a fault condition in an operating
characteristic of the HVAC system, for determining a causal
relationship between the fault condition and a predetermined list
of root causes associated with the fault condition, for receiving
information indicative of operating conditions of the HVAC system,
and for eliminating at least one root cause in response to the
receiving of the sensed information.
44-55. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent application Ser. No. 61/590,934 filed Jan. 26, 2012, the
contents of which are incorporated by referenced herein in their
entirety.
FIELD OF INVENTION
[0002] This invention relates generally to heating, ventilation,
and cooling (HVAC) systems for residential or light commercial air
conditioning applications and, more particularly, to a method and
system for a root cause self-determination of fault conditions in
an HVAC system.
DESCRIPTION OF RELATED ART
[0003] HVAC systems often do not function as well as expected due
to faults developed during routine operation. While these faults
are indicative of a failure mode, many faults do not result in
immediate system shut down or costly damages. However, most faults,
if unnoticed for a long period of time, could adversely affect
system performance, life, and lifecycle cost.
[0004] Fault diagnostics refer to detection of faults and
identification of solutions to the fault. A fault mode in one
system component may cause issues in another component. Approaches
to diagnostics may deal with direct measurement of monitored
quantities as well as dedicated sensors for measurement of crucial
system parameters in order to isolate the problem and provide a
solution. Misdiagnosis of a root cause for the fault may result in
good operating components to be replaced, resulting in repeated
callbacks for a service technician and increased warranty costs.
Additionally, dedicated sensors for diagnosis are typically costly
to implement. Therefore, it is desirable to provide a method and
system for self-determining a root cause in an HVAC system
utilizing algorithms and sensors that provide a prompt and
economical resolution of faults in an HVAC system.
BRIEF SUMMARY
[0005] According to one aspect of the invention, a method for
self-determining a root cause of a system fault in a heating,
ventilation, and cooling (HVAC) system includes receiving a fault
message indicative of a fault condition in an operating
characteristic of the HVAC system; determining a causal
relationship between the fault condition and a predetermined list
of root causes associated with the fault condition; receiving
information indicative of operating conditions of the HVAC system;
and eliminating at least one root cause that is unrelated to the
fault condition in response to the receiving of the
information.
[0006] According to another aspect of the invention, a method for
self-determining a root cause of a system fault in a heating,
ventilation, and cooling (HVAC) system includes receiving a first
list associated with a plurality of fault conditions in the HVAC
system; identifying a second list of root causes associated with a
particular fault condition of the plurality of fault conditions;
receiving information indicative of operating conditions of the
HVAC system; and eliminating at least one root cause from the
second list of root causes that is unrelated to the particular
fault condition in response to the receiving of the
information.
[0007] According to yet another aspect of the invention, a
programmable control unit for self-determining a root cause in an
HVAC system includes a controller configured for receiving a fault
message indicative of a fault condition in an operating
characteristic of the HVAC system and for determining a causal
relationship between the fault condition and a predetermined list
of root causes associated with the fault condition; where the
controller receives information indicative of operating conditions
of the HVAC system and eliminates at least one root cause in
response to the receiving of the sensed information.
[0008] According to yet another aspect of the invention, an
environmental control system for an HVAC system includes a
programmable control unit configured for establishing user desired
environmental control parameters for one or more control zones; and
at least one unit controller configured for storing information
indicative of at least one system parameter for a control system,
the at least one unit controller operatively coupled to the
programmable control unit; where the programmable control unit or
the unit controller is configured for receiving a fault message
indicative of a fault condition in an operating characteristic of
the HVAC system, for determining a causal relationship between the
fault condition and a predetermined list of root causes associated
with the fault condition, for receiving information indicative of
operating conditions of the HVAC system, and for eliminating at
least one root cause in response to the receiving of the sensed
information.
[0009] Other aspects, features, and techniques of the invention
will become more apparent from the following description taken in
conjunction with the drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0010] Referring now to the drawings wherein like elements are
numbered alike in the FIGURES:
[0011] FIG. 1 is a schematic view of an environmental control
system including a programmable controller for root cause
determination in accordance with an embodiment of the invention;
and
[0012] FIG. 2 is a flow diagram illustrating a method for
determining a root cause of a fault condition in accordance with an
embodiment of the invention.
DETAILED DESCRIPTION
[0013] Embodiments of a system for root cause self-determination of
a fault condition in an HVAC system include a control unit assembly
including software for utilizing fault tree analysis techniques,
predetermined system knowledge, and current sensed information that
is received from one or more sensors during the time of the fault
condition. In an embodiment, the control unit assembly includes an
integrated controller for operating the system in a diagnostic mode
in order to gather additional data needed to narrow the fault
condition down to a single root cause. In other embodiments, where
the root causes may not be narrowed to a single root cause, the
control unit assembly utilizes historical probabilities of the
system as well as cost information regarding the components in the
system to present the root causes in an optimal order to a user,
for example, a technician to fix.
[0014] Referring to FIG. 1, there is shown an example of an
environmental control system 100 including a control unit assembly
105 for self-determining a root-cause of a fault condition or error
associated with one or more environmental control zones in an HVAC
system according to an embodiment of the invention. Particularly,
environmental control system 100 includes a programmable control
unit assembly 105 including a housing 110 and a user input/output
device shown in the form of a touch screen display 115 that allows
a user of the HVAC system to establish and view various
environmental control parameters or conditions for one or more
environmental control zones 120, 125 such as, for example,
environmental parameters related to temperature, humidity and/or
airflow in a first and second environmental control zone 120, 125.
Also, as well as to provide fault conditions detected in any of the
first and second control zones 120, 125 and root-causes of the
fault conditions for a service technician to fix, which is shown
and described below in FIG. 2. In other embodiments, programmable
control unit assembly 105 may be used to control a single
environmental zone, for example environmental control zone 120 or
more than two environmental control zones. Further, programmable
control unit assembly 105 includes an integrated controller 130
that is operatively connected to, in embodiments, a temperature
control system 150 such as, for example, a gas furnace, air
conditioner, and/or heat pump, a humidity control system 155 such
as, for example, an air conditioner or a humidifier, and an airflow
control system 160. The integrated controller 130 establishes user
desired environmental control parameters such as, for example,
temperature, indoor air quality, humidity and/or airflow for first
and second environmental control zones 120 and 125 as well as
self-determination of root causes in systems 150, 155, and 160
associated with a deviation in the desired environmental control
parameters in zones 140, 145, as is shown and described below in
FIG. 2.
[0015] In an embodiment, systems 150, 155, 160 include respective
unit controllers 165, 170, 175, each having a processor and a
memory (not shown) that stores local sensed information as well as
information regarding predetermined system parameters for the
respective temperature control system 150, humidity control system
155, and airflow control system 160 in order to eliminate root
causes for fault detected within systems 150, 155, 160. It is to be
appreciated that integrated controller 130 may be utilized to
establish other user desired environmental control parameters in
addition to indoor air quality control, and the like for first and
second environmental control zones 120 and 125 as well as
self-determination of root causes in these control zones 120,
125.
[0016] The touch screen display 115 causes fault conditions from,
in one embodiment, desired environmental parameters, for example,
temperature, humidity and/or airflow for the environmental control
zones 120, 125 or fault conditions in temperature control system
150, humidity control system 155 and/or airflow control system 160,
to be displayed to a technician including a reporting of one or
more root causes the displayed fault condition. Additionally, the
touch screen display 115 may provide information on one or more
possible components to be replaced for components associated with
the fault conditions in the environmental control zones 120, 125
and systems 150, 155, and 160. Also, controller 130 includes a
processor and a memory 135 that stores various programs for
execution including algorithms utilizing, in one embodiment, a
fault tree analysis technique that is executed by the processor for
self-identifying a list of root causes of the fault conditions
(i.e., predetermining a list of root causes) detected in the
environmental control system 100. The processor of controller 130
can be any type of processor (CPU), including a general purpose
processor, a digital signal processor, a microcontroller, an
application specific integrated circuit, a field programmable gate
array, or the like. Additionally, controller 130 receives
information regarding parameters of system 100 as well as
predetermined historical information regarding system 100 that are
stored in memory 135, and utilizes these for narrowing down the
list of root causes. In one embodiment, memory 135 stores
information about the current sensed conditions at the time of the
fault condition, which is received from the one or more devices
150, 155, 160 and one or more sensors 140, 145. In other
embodiments, the memory 135 may store sensed information preceding
the fault condition or sensed information generated during a root
causes determination one or more programs stored in memory 135. It
is to be appreciated that while controller 130 is shown integrated
within programmable control unit assembly 105, controller 130 may,
in an embodiment, be remotely located from housing 110.
[0017] In an embodiment, a process of narrowing the list of root
causes of a particular fault condition can occur in several places
in a coordinated manner. For example, one or more of the unit
controllers 165, 170, 175, can begin the process of diagnosing a
fault in its respective unit by starting from a predetermined list
of possible root causes for the fault and, based on information
available to, for example, unit controller 165, eliminate one or
more of the root causes. In one non-limiting example, the unit
controller 165 passes the narrower list of root causes to the
integrated controller, 130, which then further narrows the list
based on information available to it as well as information
received from other units in the system. Furthermore, the
integrated controller, 130, may transmit its narrowed list of root
causes over a communication channel, such as a WiFi network or the
internet, to a remote device such as, for example, a personal
computer or a server. These remote devices may have additional
databases with historical and other information related to the
fault, which may be used to narrow the root cause list even
further. The final narrowed list may be displayed to the technician
or user on the touch screen display 115, as well as on any remote
display such as on the personal computer or a smart phone. It is to
be appreciated that any of the other unit controllers 170, 175 may
also perform the process of narrowing the possible list of root
causes as described above with respect to unit controller 165.
[0018] Referring now to FIG. 2, there is shown a flow diagram
illustrating a root cause self-determination process 200 according
to an embodiment of the invention. The process 200 includes
self-determining a root cause of one or more system fault
conditions in the environmental control system 100 or root cause in
any of the systems 150, 155, or 160 (shown in FIG. 1) including
self-determining the root cause to a system fault event in one
system component that may cause issues in another component. In an
exemplary embodiment, the root cause process 200 may identify a
fault condition such as, for example, a low pressure on an outdoor
unit (not shown) of a temperature control system 150 (FIG. 1), for
example, an air conditioner or a heat pump unit, and accurately
narrows the root cause to low indoor airflow from several other
root causes such as, in some non-limiting examples, low refrigerant
charge, faulty outdoor pressure switches, faulty outdoor expansion
valve, faulty outdoor reversing valve, or faulty outdoor
compressor. While a single fault condition is described below, it
is to be appreciated that a root cause of additional fault
conditions may be determined by the environmental control system
100 utilizing a similar process 200 described herein. It is to be
appreciated that a root cause elimination may occur within the
controller 130 or any of the unit controllers 165, 170, 175 through
a similar process as shown and described below.
[0019] The process 200 is initiated at 202, and, in 204, a fault
condition such as, for example, low-pressure lockout in the cooling
mode may be stored in the memory 135 (FIG. 1) for determining a
root cause. The controller 130 may receive local sensed data or any
other information from, in one embodiment, systems 150, 155, 160
and one or more sensors 140, 145, in order to determine fault
conditions that cause the system 100 to deviate from user or system
defined environmental parameters, e.g., temperature, humidity
and/or airflow for the environmental control zones 120, 125 (FIG.
1). Further, controller 130 determines whether the received
information indicates a deviation from the desired environmental
parameters and presents these as a fault condition on display 115
(FIG. 1). This fault condition is stored in memory 135 (FIG. 1), in
embodiments, as either error codes, for example fault code 83
and/or as a text message, for example "Fault 83: Low Pressure
Lockout for 4 Hours".
[0020] In 206, controller 130 (FIG. 1) determines a causal
relationship between the fault condition and one or more root
causes of the fault condition. In one embodiment, the controller
130 (FIG. 1) utilizes algorithms stored in memory 135 (FIG. 1) to
implement a fault tree model such as, for example, a
cause-and-effect diagram in order to identify a predetermined list
of root causes associated with the particular fault condition. In
an embodiment, the predetermined list of root causes associated
with the fault condition are causally linked by the fault tree
model within the controller 130 and may be accessed for each fault
condition that is particularly detected by controller 130. In 208,
the controller 130 analyzes the information on the current sensed
conditions received from controllers 165, 170, 175 in the
respective systems 150, 155, 160 using locally sensed information
from systems 150, 155, 160 as well as predetermined information
that are received about systems 150, 155, 160 substantially
contemporaneous at the time of the fault condition or preceding the
fault condition in order to eliminate unrelated root causes from
the predetermined list of root causes and limit it to a single root
cause for the fault condition. Particularly, the controller 130
(FIG. 1) analyzes the current sensed conditions obtained from, in
embodiments, sensors 140, 145, temperature control system 150,
humidity control system 155 and/or airflow control system 160 (FIG.
1) at the time of the fault condition or preceding the fault
condition in order to eliminate one or more root causes not related
to the fault condition
[0021] In 210, if the sensed information indicates that there is a
single root cause, then in 212, the single root cause is provided
to the technician on touch screen display 115 including the
solutions for fixing the particular fault condition. However, if
the controller 130 determines that there may be several root causes
associated with the fault condition, then, in 214, the controller
130 will run the system 100 in a particular diagnostic mode in
order to generated additional specific data and further limit the
possible root causes and eliminate unrelated root causes. In the
diagnostic mode, the controller 130 is programmed for presetting
the system 100 to predefined parameters associated with an
operating characteristic of the HVAC system that generated the
fault condition such as, for example controlling the speed of the
compressor or the speed of the indoor fan, in order to obtain
additional data needed for eliminating one or more root causes of a
particular fault condition. This additional information obtained is
stored in memory 135 for additional fault diagnosis by the
controller 130. In 216, if a single root cause remains after the
diagnostic mode is implemented, then the root cause is provided to
the technician on touch screen display 115 in 212. However, in 216,
if more than one root cause remains then, in 218, the controller
103 utilizes the predetermined historical information regarding the
probability or likelihood of a defect in one of the various
components in system 100 that is associated with the fault
condition to display a list of possible root causes in the order of
priority for the technician to fix or address. In one embodiment,
the root causes may be prioritized base on historical probabilities
of the system 100 as well as the cost associated with replacing one
or more components associated with the root cause. The process end
at 220.
[0022] The technical effects and benefits of embodiments relate to
an HVAC a system programmed for determining a root cause of a fault
condition including software utilizing a fault tree analysis
methodology, historical information of the HVAC system, and current
sensed information for eliminating one or more erroneous root
causes of the fault condition.
[0023] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. While the description of the present invention has
been presented for purposes of illustration and description, it is
not intended to be exhaustive or limited to the invention in the
form disclosed. Many modifications, variations, alterations,
substitutions, or equivalent arrangement not hereto described will
be apparent to those of ordinary skill in the art without departing
from the scope and spirit of the invention. Additionally, while
various embodiment of the invention have been described, it is to
be understood that aspects of the invention may include only some
of the described embodiments. Accordingly, the invention is not to
be seen as limited by the foregoing description, but is only
limited by the scope of the appended claims.
* * * * *