System and method for controlling indoor air flow for heating, ventilating and air conditioning equipment

• US 20070095082A1
• Filed: 11/02/2005
• Published: 05/03/2007
• Est. Priority Date: 11/02/2005
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: American Standard Companies Incorporated (Ideal Standard International Topco SCA)
• Inventors: Hugghins, Gordon, Helt, Robert, Garrett, Carl, Storm, Timothy
• Granted Patent: US 7,640,761 B2
• Time in Patent Office: Days
• US Class Current: 62/180
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

An HVAC system includes a variable speed electric motor driven fan for circulating air to an enclosed space through an indoor unit for providing heating or cooling effect to air circulated through the indoor unit. A controller with user or system installer actuatable switches includes a programmable microcontroller providing a pulse width modulated (PWM) signal to a motor control unit to select a predetermined air flowrate less than full air flowrate during system startup and shutdown. User input parameters include selected percentages of full air flowrate to satisfy requirements for reduced noise level, lower humidity and for improved sensible heating of air being circulated, the latter being effective particularly for heat pump applications. Selection of pre-run, short run and shutdown cycles may be provided.

Claims

1. A heating, ventilating and air conditioning system comprising:

an indoor unit including a motor driven fan for circulating air to and from an enclosed space, said fan being driven by a variable speed electric motor, at least one heat exchanger disposed in a flow path of air circulating through said indoor unit; and

a controller operably connected to said indoor unit including a programmable microcontroller operable to provide pulse width modulated signals to a motor control unit for said motor, said controller including one of installer and user selectable values of motor speed for controlling airflow through said heat exchanger to provide at least one comfort parameter sensed by said user.

2. The system set forth in claim 1 wherein:

said controller includes a temperature sensor for sensing the temperature in said enclosed space and said microcontroller is responsive to a call for one of heating or cooling air to be circulated through said space for providing a selected air flowrate less than full air flowrate at startup of said fan.

3. The system set forth in claim 2 wherein:

said microcontroller is operable to control the speed of said motor when the call for heating or cooling is satisfied to provide a selected air flowrate through said indoor unit less than full air flowrate capability of said fan.

4. The system set forth in claim 3 wherein:

said controller comprises a visual display operably connected to said microcontroller and user or installer actuatable switch actuators for selecting at least one of a percent air flowrate of full air flowrate and a time of reduced air flowrate during at least one of a pre-run period after a call for heating or cooling, a short run period following said pre-run period and a shutdown period after said call for heating or cooling is satisfied.

5. The system set forth in claim 1 wherein:

said microcontroller is operable to provide a pulse width modulated signal to said motor control unit for selecting the air flowrate and the time of said air flowrate during an operating cycle of said indoor unit.

6. The system set forth in claim 1 wherein:

at least one of said heat exchangers comprises one of an evaporator coil and a condenser coil of a vapor compression refrigerant condensing and expansion circuit for providing cooling and heating to said air circulating through said indoor unit.

7. The system set forth in claim 1 wherein:

at least one of said heat exchangers comprises one of a dual fuel furnace and an electric furnace.

8. In a heating, ventilating and air conditioning system including an indoor unit comprising a variable speed electric motor driven fan for circulating air to and from an enclosed space, said indoor unit including at least one heat exchanger for providing one of a heating and cooling effect to said air circulating to said indoor space and a controller including user actuatable switch actuators and a microcontroller operable to provide a signal to a motor control unit for said electric motor to control motor speed and air circulation rate to said indoor space, the method characterized by:

providing a selected pulse width modulated electrical signal to said motor control unit to provide a predetermined motor speed corresponding to said pulse width modulated signal to modify the air flowrate to a predetermined percentage of full air flowrate available from said fan.

9. The method set forth in claim 8 including the step of:

providing said selected signal for selecting a predetermined air flowrate during a pre-run period after a call for one of heating and cooling effect from said system.

10. The method set forth in claim 9 including the step of:

providing said selected signal for selecting a predetermined air flowrate during a short run period following said pre-run period.

11. The method set forth in claim 8 including the step of:

providing said selected signal for selecting a predetermined air flowrate during a system shutdown phase commencing with satisfaction of a call for one of heating and cooling effect by said system.

12. The method set forth in claim 8 including the step of:

providing said selected signal for controlling a continuous air flowrate available from said fan.

13. The method set forth in claim 8 including the step of:

providing selected ranges of a pre-run delay time and a short run delay time of air flowrate less than full air flowrate from a selected number of preset flow rates and periods of such air flowrates for said pre-run delay time and short run delay time.

14. The method set forth in claim 13 wherein:

respective sets of pre-run delay times and short run delay times are provided for fan turn-on delay profiles and fan turnoff delay profiles, said profiles commencing with a call for one of heating and cooling and satisfaction of said call for one of heating and cooling, respectively.

15. The method set forth in claim 8 including the step of:

causing said microcontroller to provide a signal to said control unit for a predetermined air flowrate dependent on single stage operation or multistage operation of said system.

16. The method set forth in claim 15 wherein:

the percentage of full air flowrate is adjusted based on a selected air flowrate multiplied by an installer selected air flowrate for a single or low stage system operation.

17. The method set forth in claim 8 including the step of:

providing said signal to said motor control unit to modify said air flowrate to a predetermined value dependent on whether said heating effect is provided by a heat pump heat exchanger, a dual fuel furnace and an electric heat source.

18. The method set forth in claim 8 including the step of:

providing said signal to said motor control unit to provide a predetermined air flowrate if one of heating or cooling effect is terminated during one of a pre-run delay period or a short run delay period, said pre-run delay period commencing with a call for one of heating or cooling effect and said short run delay period commencing with termination of said pre-run delay period.

19. The method set forth in claim 18 wherein:

said signal to said motor control unit provides for an air flowrate which is a predetermined percentage of a preprogrammed air flowrate during said pre-run delay period or said short run delay period dependent on which period said one of said heating or cooling effect is terminated.

20. In a heating, ventilating and air conditioning system including an indoor unit comprising a variable speed electric motor driven fan for circulating air to and from an enclosed space, said indoor unit including at least one heat exchanger for providing one of a heating and cooling effect to said air circulating to said indoor space and a controller including switch actuators and a microcontroller operable to provide a signal to a motor control unit for said electric motor to control motor speed and air circulation rate to said indoor space, the method characterized by:

providing a selected electrical signal to said motor control unit to provide a predetermined motor speed corresponding to said selected signal to modify the air flowrate to a predetermined percentage of full air flowrate available from said fan during one of a pre-run period after a call for one of heating and cooling effect from said system, a short run period following said pre-run period, and a system shutdown phase commencing with satisfaction of a call for one of heating and cooling effect by said system.

21. The method set forth in claim 20 including the step of:

providing said signal to said motor control unit to modify said air flowrate to a predetermined value dependent on whether said heating effect is provided by a heat pump heat exchanger, a dual fuel furnace and an electric heat source.

22. The method set forth in claim 20 including the step of:

providing said signal to said motor control unit to provide a predetermined air flowrate if one of heating or cooling effect is terminated during one of said pre-run delay period, and said short run delay period, said pre-run delay period commencing with a call for one of heating or cooling effect and said short run delay period commencing with termination of said pre-run delay period.

23. The method set forth in claim 22 wherein:

said signal to said motor control unit provides for an air flowrate which is a predetermined percentage of a preprogrammed air flowrate during said pre-run delay period or said short run delay period dependent on which period said one of said heating or cooling effect is terminated.

24. The method set forth in claim 20 including the step of:

providing selected ranges of a pre-run delay time and a short run delay time of air flowrate less than full air flowrate from a selected number of preset flow rates and periods of such air flowrates for said pre-run delay time and short run delay time.

25. The method set forth in claim 24 wherein:

respective sets of pre-run delay times and short run delay times are provided for fan turn-on delay profiles and fan turnoff delay profiles, said profiles commencing with a call for one of heating and cooling and satisfaction of said call for one of heating and cooling, respectively.

26. The method set forth in claim 20 including the step of:

causing said microcontroller to provide a signal to said control unit for providing a predetermined air flowrate dependent on single stage operation or multistage operation of said system.

27. The method set forth in claim 26 wherein:

said system comprises a multistage compressor for circulating a heat exchange fluid and said method includes the step of causing said microcontroller to provide a signal to said control unit to provide a reduced air flowrate when said system is operating at a first or low stage of compression.

28. The method set forth in claim 27 including the step of:

causing said controller to provide a signal to said control unit to provide maximum air flowrate through said system when said system is operating at a highest stage of compression unless said system is operating in conjunction with a humidity sensor or said system is a heat pump operating in the heat pump heating mode or said system is operating in the cooling mode at an efficiency setting during mild outdoor temperature conditions.