Self diagnosing HVAC zone configuration

In a drive circuit in which a plurality of drive motors are connected to a power source through a protective device which trips when the flow of current is excessive, provision is made to detect which circuit or circuits were active at the time of the failure. A microprocessor is provided to both control the activation of each of the various circuits and to also sense which circuits were active at the time of the failure. Appropriate signals are sent from the microprocessor to a user interface so that proper diagnostic and repair action can be taken.

BACKGROUND OF THE INVENTION

This invention relates generally to air conditioning systems and, more particularly, to a method and apparatus for diagnosing faults in such a system having multiple drive motors.

As improved design and operational procedures for heating, ventilation and air conditioning (HVAC) systems are continually being provided for the benefit of users, such systems are typically becoming more complex and difficult to install and maintain. Among some of the difficulties that occur are improper wiring of the various components and the related problems which are difficult to diagnose in complex HVAC systems. For example, in a multi-zone system, wherein it is desirable to introduce varying degrees of cooling or heating to various zones in a building, a plurality of drive motors are connected to position their respective dampers in a desired position so as to regulate the degree of cooling/heating in their particular zones. In the event that one of the damper drive motors is connected improperly, a fault will occur in the system, but it is difficult to determine exactly where that fault has occurred. Accordingly, the diagnosis and repair of the problem can be unduly complicated.

One such system is a variable volume multizone system as shown and described in U.S. Pat. No. 4,630,670 assigned to the assignee of the present invention. That patent is incorporated herein by reference. As will be seen, both the fan speed and the respective damper positions are selectively varied to obtain the desired temperatures in the various zones. Other similar systems maintain a constant fan speed while varying the damper positions by individual motor control.

SUMMARY OF THE INVENTION

Briefly, in accordance with one aspect of the invention, a protective circuit, which is adapted to trip when the current therethrough exceeds a predetermined level, is connected in parallel with the plurality of devices that are individually powered on a selective basis by an interconnected control system. When the protective device trips because of excessive power, the control system determines which device was receiving power at the time that the device tripped. This information is then provided to the user for diagnosing and repairing the problem.

In accordance with another aspect of the invention, the current protection device is of the self-healing type wherein the device resets itself after a predetermined time period, with current then being restored to the operating system. In particular, a poly thermal crystal (PTC) device is provided for this purpose.

In the drawings as hereinafter described, a preferred embodiment is depicted; however, various other modifications and alternate constructions can be made thereto without departing from the true spirit and scope of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now toFIG. 1there is shown a simplified schematic illustration of a comfort system incorporating the present invention. A duct11carries conditioned air that is caused to flow by the motor12and associated fan13, with the duct11extending over the four zones, Zone 1, Zone 2, Zone 3 and Zone 4. The zones have respective dampers14,16,17and18, driven by respective motors19,21,22and23. The amount of air flowing to respective zones is therefore dependent on the degree of openness of the respective dampers, and those positions are adjusted by operation of the respective motors which receive their power from a power source24by way of a protective device26, one form of which may be a polythermal crystal (PTG). A control apparatus27receives power from a power source24by way of line28and communicates with the protective device26by way of line29. The control27is also connected to the individual damper motors19,21,22, and23by way of line31.

In operation, power is selectively connected, as determined by the control27, to one or more of the damper motors19,21,22, or23by way of the protective device26, for the purpose of meeting the individual demands of the respective zones. Thermostats32,33,34and36are provided in the respective zones to sense the existing temperature and compare it with a desired temperature in the respective zones.

If, at any time, the current flowing through the protective device26exceeds a predetermined level, the device26will trip and disconnect the power to the motor(s) that happens to be operating at that time. The control27will then determine which motor(s) was operating at the time that the device26was tripped and will provide an indication thereof to the user interface37. The user can then use this information to diagnose and repair the fault which caused the device26to trip out as will be described hereinafter.

Referring now toFIG. 2, the circuitry is shown to include a 24 volt AC power input24providing power to the control apparatus27which is in one form a microprocessor27a, by way of line38and a power conditioning module39. Power is also provided by way of the protective device26to the various damper drive motors19,21,22, and23.

The microprocessor27a, in response to other control signals received along line41, such as, for example, the signals from the respective thermostats, operates to send open or close command signals to the respective drive circuitry for the purpose of moving the dampers to a more open or closed position by way of a respective drive motors. Feedback data then passes along line42to inform the microprocessor27aof the condition of the respective circuits.

Assuming now that excess current flow has caused the PTC to temporarily open the circuit. The microprocessor27awill then be able to determine, from feedback received along line42, which of the four circuits (those involving drive motors19,21,22, and/or23), were operating at the time of the failure. This information can then be provided to the user interface37so that corrective action can be taken. After a specified period of time, the PTC will reset itself and, thus, after corrective action has been taken on the basis of information provided to the user interface37, power will be resumed to the circuits as shown inFIG. 2. If the same conditions still exist, the protective device will again break and the process will be repeated, with diagnostic information again being sent to the user interface37. A memory is preferably provided in the microprocessor27aand/or the user interface37such that the performance history will be retained in the memory such that this data can be used in diagnosing problems in the future.

Referring now toFIG. 3, the diagnostics portion of the present system is shown. The system is capable of using a communication protocol to show the serviceman what, if any, faults are in the system. As shown inFIG. 3, the User Interface37, is a graphical interface, which will indicate to the user/serviceman in both code number and short description as to where the fault is located. Should a fault occur in said system such as is in the Zone Controller38as described hereinabove, in a Furnace Board39of a heating system, or in any other Equipment41that may be appropriate, the present system would report this fault to the User Interface37and then the user would have access to the data through a visual report by means of the aforementioned text description and fault code. Instructions to call service professional may also appear on the users screen to direct the user to seek assistance with the provided number on the screen.

If a serviceman runs a diagnostics on the system through the communication bus42, he will be able to evaluate system performance and determine the condition of the operation which have generated the faults. This repair/servicing is made more efficient through the means of detailed fault indicators that can be read through the graphical interface of the communicating Service Tool43which connects to the bus42and runs diagnostics on the system.

While the present invention has been particularly shown and described with reference to a preferred embodiment as illustrated in the drawings, it will be understood that one skilled in the art that various changes in detail may be affected therein without departing from the spirit and scope of the invention as defined by the claims.