HK1104097A - Serial communicating hvac system - Google Patents

Description

Serial communication HVAC system

Technical Field

The present invention relates to heating, ventilation and air conditioning (HVAC) systems in which a plurality of interconnected devices communicate control signals to each other over a communication bus.

Background

HVCA systems are becoming increasingly complex. As the complexity of these systems increases and the control becomes more complex, the number of wires that are hardwired between the system components and the controller also increases. As one example, a traditional residential HVAC system has a thermostat on a wall of the house that allows a user to set a desired operating mode and temperature. There are typically also indoor equipment (gas stoves or heaters/fans) and outdoor equipment (air conditioners or heat pumps). Even this simple system illustrates the above mentioned problems.

The HVAC system operates according to a simple control protocol. Based on the settings on the thermostat desired by the user, and the actual room temperature, command signals are sent to the indoor and/or outdoor equipment to perform heating, cooling or fan functions. In most current systems, each of these functions requires a dedicated line to run between the thermostat and the corresponding equipment. The thermostat turns on the 24 volt ac signal on the wire to command the device to turn on the desired function and removes the 24 volt ac signal to turn off the function.

Some systems have extended this protocol to include additional wires for carrying fault information from one device back to the thermostat and displaying the fault information to the user of the HVAC system. As residential systems become more complex, multiple heating and cooling stages become common. Furthermore, conventional protocols have been extended to include additional wires for each device level. New functions, such as controlling humidity, are also being integrated into the thermostat. Furthermore, each function typically requires its own wiring.

As an example, one thermostat currently manufactured by the assignee of the present application includes the ability to connect up to 11 wires. Two of the wires provide a 24 volt power supply and two of the wires extend to an outdoor air temperature sensor. The remaining seven lines control different functions in the indoor and outdoor HVAC equipment. As one example, separate lines are required to turn on the indoor unit and move it between different speeds or stages. These 11 lines do not include any of the "feedback" or status information mentioned above. More lines would be required to provide this feedback. As can be appreciated, this results in a very complex installation, since each of the 11 wires must be attached at the correct location on the thermostat. Each of the seven control lines provides a single control function. As the number of wires increases, the mounting complexity and the possibility of incorrect wiring also increase. In connection with this problem, each combination of equipment (fan or furnace, AC or heat pump, one or more stages, humidifiers or not, etc.) has a different wiring arrangement. All of this can be challenging for less experienced indoor HVAC installers. This may result in poor installation, resulting in degraded performance, failure, or service calls.

In many existing dwellings, the above challenges are compounded because only 4 wires are run through the wall to the thermostat at installation. It may be difficult or impossible to use additional wires to upgrade functionality.

Some systems have included somewhat more complex controls. As an example, the assignee of the present application has developed a thermostat controller that transmits a plurality of control signals to a main control panel via two control lines. However, the main control panel is still hardwired to the indoor and/or outdoor equipment. Likewise, the above-described problems still exist with respect to an improper number of wires.

Therefore, a simplified system that addresses the above-described problems and allows for simple system upgrades would be desirable.

Disclosure of Invention

In a disclosed embodiment of the invention, at least one of the thermostat and the indoor unit has an electronic controller. The controllers from these devices communicate over four conductors, with control signals being sent on two of the conductors and power being provided on the other two conductors. An unlimited number of different control signals may be sent over two control wires. In addition, peripheral controllers such as zone humidifiers, remote access modules, and the like may also have controllers that communicate over a four-wire bus as described above. The disclosed system uses a microprocessor for the controller.

The transmission of the disclosed control signals is serial in nature and allows for a virtually unlimited flow of information through the system. As disclosed, the thermostat provides central control and initiates all communication and sends all system commands to the respective equipment controllers.

The indoor unit may be provided with a controller capable of providing information to existing outdoor units and peripheral devices such as humidifiers that operate according to conventional hardwired protocols, and does not have built-in communication capabilities (i.e., a dedicated microprocessor). Peripherals with dedicated controllers may also have the ability to interface with other hardwired peripherals. Also, in its broadest scope, the present invention comprises a central controller in a thermostat, wherein the thermostat is capable of receiving a user desired setting and transmitting a plurality of different control signals to an indoor unit over two wires. The control signal is transmitted directly to the microprocessor controlling the indoor unit through the communication bus.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

Drawings

Fig. 1 schematically shows a system according to the invention.

Fig. 2 schematically shows a system according to this invention.

Detailed Description

FIG. 1 is a simplified illustration of a basic HVAC system 20 that includes the serial communication of the present invention and incorporates a thermostat 22 having user input settings 24 as is known. The microprocessor 26 is incorporated into the thermostat 22. The microprocessor 26 is both a bus master and a system master, since the temperature controller microprocessor 26 enables all communication between the different devices as will be described below. In addition, the microprocessor 26 issues all commands to the respective devices, again as will be explained below. The microprocessor 26 makes these command decisions based on user settings and other information it receives back from the corresponding device. Generally, the control decisions made by the microprocessor 26 are as known in the art. The present invention relates to how these signals are communicated between the microprocessor 26 and the associated devices.

Four wires 28A-28D provide a data bus 29 to communicate the microprocessor 26 with a microprocessor 32 located at an indoor unit such as a burner controller or a fan/heater controller. As shown, other peripheral devices may be in communication through the microprocessor 32 at the indoor unit 30 and back to the microprocessor 26 at the thermostat 22. One example of a peripheral device would be a humidifier 44, which may not have its own microprocessor controller.

A peripheral device 40, such as a humidifier control module having a microprocessor 42, is shown in communication with the data bus 29 and then to the microprocessor 26 via four conductors 43A-D. The wires 43A-D are connected to the wires 28A-D, as is known, for example at a routing or junction box 31.

The humidifier 44 is shown as an existing type of peripheral device that would be hard wired to communicate with the microprocessor 32 and then to the microprocessor 26 via the data bus 29 (conductors 28A-28D). Microprocessor 26 will in turn send a control signal back to humidifier 44. The microprocessor 32 is provided with control functions that allow it to control the hard-wired humidifier based on signals received from the microprocessor 26. Alternatively, and generally with further improvements in HVAC systems, humidifiers controlled over the same four wire data bus 29 may be improved and incorporated into the system. In addition, the microprocessor 26 will then be fully functional to control the new microprocessor at the humidifier 44.

The data buses (29, 31) are wired so that two of the wires, such as C and D, carry a 24 volt ac power source from the in-room device 30 to power all other controllers in the system. The other two wires a and B are used for system-wide communication and control.

Likewise, as is known, the thermostat is provided with a room temperature sensor, and optionally possibly a humidity sensor, and a digital display. Likewise, among the information transmitted may be identification codes, so that the microprocessor 26 can identify reporting devices, status and fault information, and standard feedback typically provided by such devices to the system controller. As can be appreciated, signals transmitted within the system are provided with codes or identifiers so that the signals can be properly routed and identified. Protocols for achieving this are known.

Since these devices are all connected according to the same simple wiring scheme, wires a-D, it is relatively easy for an installer to properly install the various devices. Moreover, since only four wires are required, the above-mentioned problems associated with incorporating a more complex HVAC system into an existing structure having only four wires leading to a thermostat are eliminated.

Another set of wires 34A-34D communicates microprocessor 32 with outdoor unit 36 and its microprocessor 38. As mentioned above, the microprocessor 32 at the indoor unit 30 is also capable of controlling a hard-wired outdoor unit.

When the user inputs the desired environmental conditions into the controller 24 at the thermostat 22, the microprocessor 26 sends appropriate control signals to the indoor unit 30 and "peripherals" (e.g., the humidifier controller 40) via the data bus 29. The signal may be sent serially from the indoor unit 30 to the outdoor unit 36 and the "peripheral" 44.

Fig. 1 shows a basic arrangement that may be within the scope of the invention. While figure 2 illustrates the ability of the present invention to provide various options.

As shown in fig. 2, the thermostat 24 communicates with the indoor unit 30 through a data bus 29. If the indoor unit 30 is a fan coil or controller, the electric heater 50 may be hardwired to the indoor unit 30. The fan coil controller is operable to control the electric heater. See, for an example, co-pending U.S. patent application serial No.10/707,524 entitled "Identification of Electric Heater Capacity" filed on 12/19/2003. The entire disclosure of this application is incorporated herein by reference. As is known, the fan coil and heater may also provide cooling.

The data bus 34 may communicate the microprocessor 32 at the indoor unit 30 with a controller 38 on the outdoor unit 36. In addition, a hard-wired "silent" humidifier controlled by the microprocessor 32 at the indoor unit 30 may be connected to the microprocessor 32. As disclosed above, the outdoor unit 36 may also be controlled by the microprocessor 32.

As also shown in fig. 2, the remote sensor 52 may be in direct communication with the thermostat 24. The data bus 53 connecting this remote sensor 52 to the thermostat 24 may be connected to the data bus 29, for example at a junction box or the like. Such remote sensors may be used as thermostats in the same room when it is desired to have a temperature sensor in the room, but hide the thermostat, such as in a storage room or the like. As further shown, the outdoor unit 60 may be directly connected to a data bus 59 branching off from the data bus 29 through a data bus 61. Appropriate nodes or connections 31 connect bus 59 to data bus 29 and bus 61 to bus 59. Such a connection may be used when the outdoor unit has its own microprocessor controller, but for many reasons it is desirable to wire the outdoor unit directly into the bus 59, rather than through the indoor unit 30 (e.g., if the indoor and outdoor units are remote from each other within a building).

As shown, the humidifier control module 40 has a microprocessor 42 and may provide control functions for a "dumb" ventilator 62. In addition, the microprocessor 42 at the humidifier control module 40 is provided with control instructions for controlling the "dumb" ventilator. As shown, there is preferably a hard-wired connection between the ventilator and the microprocessor 42 within the humidifier control module 40. As is known, the humidifier control module receives control signals and turns the humidifier on or off to control the flow of air into the various rooms within the building.

Of course, other damper control modules, such as 64, may simply be connected directly to the data bus 59 via the data bus 65.

The smart sensor 66 may include a microprocessor 67 and is connected to the data bus 59 via a data bus 65. Further, with each of the data buses 65, some node 31 may be used to communicate between the two data buses.

The access module 68 may also be connected to the data bus 59 via its own data bus 69. As is known, the access module allows remote access to the HVAC system. Of course, as will be understood by those of ordinary skill in the art, any of the data buses 61, 65, 69 may also be connected to the data bus 29 directly, rather than through the branch data bus 59.

Another feature provides additional freedom of design. The interface module 54 may basically include a microprocessor control 53 to communicate with "dumb" outdoor equipment, ventilators, etc. Basically, the interface module 54 microprocessor 53 is provided with control of one or more "dumb" devices (56, 58). The interface module 54 communicates with a data bus 59 via a data bus 55.

The microprocessor associated with each device is provided with built-in software to communicate back to the thermostat microprocessor 26 and to interpret and act upon instructions from the microprocessor 26. Further, all such controls may be as is known in the art. How the control signals are transmitted is novel. Also, although a microprocessor is disclosed, other types of controllers capable of performing the disclosed functions may be used.

While four conductors A-D are shown, it is to be understood that the present invention may be provided by other arrangements. As one example, the control functions may be provided by a coaxial line having inner and outer conductors for providing control communications. For the purposes of this application, such a coaxial line would provide two of the four conductors. Also, while a central controller is disclosed in the thermostat, the central controller may be a separate controller or at other components, such as on an indoor unit.

Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims (22)

1. An HVAC system comprising:

a thermostat comprising a central controller and an operator input switch;

transmitting control signals from the central controller to a data bus of an indoor HVAC plant operable to provide a heating function to air within an environment, the indoor HVAC plant being provided with a controller that directly controls the indoor HVAC plant and that receives control signals from the central controller over the data bus.

2. The HVAC system as set forth in claim 1, wherein an outdoor HVAC unit is provided with its own controller and said outdoor HVAC unit controller communicates with said central controller over said data bus.

3. The HVAC system as set forth in claim 1, wherein at least one peripheral HVAC unit includes its own controller and communicates through said indoor HVAC unit controller to provide control signals to and from said central controller.

4. The HVAC system as set forth in claim 1, wherein four wires communicate said indoor HVAC unit controller to said central controller, wherein two of said wires carry power and two of said wires carry said control signal, wherein a plurality of different signals are sent on said two wires carrying control signals.

5. The HVAC system as set forth in claim 1, wherein at least one peripheral device is hardwired to said indoor HVAC device controller, and said indoor HVAC device controller is designed to include control information for said at least one peripheral device.

6. The HVAC system as set forth in claim 1, wherein an interface module is provided with a controller to communicate with said data bus from an associated HVAC device that does not have a controller capable of receiving control signals over said data bus, said interface module being hardwired to said associated HVAC device, and said interface module being provided with control information for controlling said associated HVAC device.

7. The HVAC system as set forth in claim 1, wherein remote sensor communicates with said central controller generally over said data bus.

8. The HVAC system as set forth in claim 1, wherein said central controller and said indoor HVAC unit controller are both microprocessors.

9. The HVAC system of claim 1, wherein the control signal comprises an identifier for the databus routing information.

10. An HVAC system comprising:

a data bus comprising four conductors for conveying signals from a central controller to a controller of an indoor HVAC unit, the data bus comprising two control conductors conveying a plurality of different control signals and two power conductors conveying power, the indoor HVAC unit providing power for supplying power through the two power conductors, the central controller being a system controller for generating control signals and sending control signals to the indoor HVAC unit controller, the indoor HVAC unit being operable to provide heating and fan functions to move air within an environment; and

a four wire outdoor HVAC unit, wherein two power wires carry a power signal and two control wires carry a plurality of different control signals from the outdoor HVAC unit to the central controller, the central controller providing control signals to the outdoor HVAC unit controller to operate the outdoor HVAC unit.

11. The HVAC system as set forth in claim 10, wherein at least one peripheral device is hardwired to said indoor HVAC device controller, said indoor HVAC device controller being designed to include control information for said at least one peripheral device.

12. The HVAC system as set forth in claim 11, wherein at least one peripheral device is a humidifier.

13. The HVAC system as set forth in claim 10, wherein at least one peripheral device comprises a controller controlling its function, said at least one peripheral device controller communicating with said central controller over four conductors, two of said four conductors being power conductors and two control conductors carrying control signals from said central controller to said at least one peripheral device controller.

14. The HVAC system as set forth in claim 13, wherein said at least one peripheral device is a humidifier control module.

15. The HVAC system as set forth in claim 13, wherein said at least one peripheral device is a sensor for detecting conditions within a room, said sensor providing signals to said central controller over said two control wires.

16. The HVAC system as set forth in claim 10, wherein said outdoor HVAC unit control communicates serially with said central control through said indoor HVAC unit control.

17. The HVAC system as set forth in claim 10, wherein said outdoor HVAC unit controller and said indoor HVAC unit controller are separately connected into said data bus for communication with said central controller.

18. The HVAC system as set forth in claim 10, wherein an interface module is provided with a controller to communicate with said data bus from an associated HVAC device that does not have a controller capable of receiving control signals over said data bus, said interface module being hardwired to said associated HVAC device, and said interface module being provided with control information for controlling said associated HVAC device.

19. The HVAC system as set forth in claim 10, wherein said central controller, said indoor HVAC unit controller and said outdoor HVAC unit controller are each a microprocessor.

20. The HVAC system of claim 10, wherein the control signal includes an identifier for the databus routing information.

21. The HVAC system as set forth in claim 10, wherein said four conductors are provided by four distinct and separate conductors.

22. An HVAC system comprising:

a central controller;

a thermostat having an operator input switch;

indoor HVAC equipment operable to provide a heating function to air within an environment, the indoor HVAC equipment being provided with a controller that directly controls the HVAC equipment; and

a data bus communicating control signals from the central controller to the thermostat and to at least the indoor HVAC equipment and communicating control signals from the thermostat, the indoor HVAC equipment receiving control signals from the central controller over the data bus and communicating signals from the operator input switches to the central controller to effect control of the indoor HVAC equipment over the data bus.