US5616995A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Systems and methods for controlling a draft inducer for a furnace
Assignee: Regal Beloit Electric Motors Inc
•
Filing: 1995-03-09
•
Granted: 1997-04-01
•
Expires: 2015-03-09
Abstract
Abstract Systems and methods for controlling a draft inducer for use with a furnace. The draft inducer includes a fan for moving combustion chamber gases for inducing a draft in the furnace combustion chamber that causes a pressure drop across a heat exchanger. The density of the gases flowing across the heat exchanger and the fan differs from a first operating state of the furnace to a second operating state of the furnace. A motor drives the fan in response to a motor control signal so that different motor speeds result as a function of the density of the gases flowing across the fan. A control circuit generates the motor control signal as a function of a first set of speed/torque curves until a speed signal indicates that the motor has reached a predetermined speed. After the speed signal indicates that the motor has reached the predetermined speed, the control circuit generates the motor control signal as a function of a second set of speed/torque curves. Thus, the motor will operate in accordance with the first speed/torque curves when the furnace is in the first operating state and in accordance with the second speed/torque curves when the furnace is in the second operating state.
Inventors
- 👤 Robert K. Hollenbeck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:44
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/03; F; F23; F23N; F23N1/00; F23N1/06; F23N1/062; F23N3/00; F23N3/08; F23N3/082; G; G05; G05D; G05D13/00; G05D13/08; G05D13/30; H02P; H02P25/00; H02P25/02; H02P25/04; H02P6/00; H02P6/08; H02P6/085; H02P6/26; F23N2225/00; F23N2225/04; F23N2225/06; F23N2233/00; F23N2233/02; F23N2233/04; F23N5/00; F23N5/18; H02K2201/00; H02K2201/06; Y; Y10; Y10S; Y10S236/00; Y10S236/09
Claims Analysis
Total Claims: 61
Claim 1
Independent Claim
310 words
A draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said apparatus comprising: a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 2
Dependent Claim
310 words
A draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said apparatus comprising: a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 3
Dependent Claim
88 words
The apparatus of claim 1 wherein the first operating state is defined as operation of the furnace when combustion is not occurring in the combustion chamber and the second operating state is defined as operation of the furnace when combustion is occurring in the combustion chamber whereby the density of the combustion chamber gases is greater in the first operating state than in the second operating state so that the fan increases in speed when the furnace changes from the first operating state to the second operating state.
Claim 4
Dependent Claim
209 words
The apparatus of claim 1 wherein the first and second operating states each has a low stage and a high stage and wherein the furnace includes a furnace controller providing a furnace operating signal for causing the furnace to operate in either the low stage or the high stage of the first and second operating states and wherein the first and second sets of speed/torque curves defined by the defining circuit each include a speed/torque curve corresponding to the low stage and a speed/torque curve corresponding to the high stage and wherein the control circuit is responsive to the furnace operating signal for generating the motor control signal as a function of the low stage speed/torque curve of the first speed/torque curves in the low stage of the first operating state and as a function of the high stage speed/torque curve of the first speed/torque curves in the high stage of the first operating state and for generating the motor control signal as a function of the low stage speed/torque curve of the second speed/torque curves in the low stage of the second operating state and as a function of the high stage speed/torque curve of the second speed/torque curves in the high stage of the second operating state.
Claim 5
Dependent Claim
51 words
The apparatus of claim 3 wherein the control circuit is responsive to the furnace operating signal for generating the motor control signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the low stage to the high stage thereby to rapidly increase the motor speed.
Claim 6
Dependent Claim
51 words
The apparatus of claim 3 wherein the control circuit is responsive to the furnace operating signal for generating the motor control signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the high stage to the low stage thereby to rapidly decrease the motor speed.
Claim 7
Dependent Claim
79 words
The apparatus of claim 1 further comprising a memory for storing the motor speed as represented by the speed signal and a circuit for comparing the stored speed to the motor speed as subsequently represented by the speed signal, and wherein the control circuit detects a change from the first operating state to the second operating state when the difference between the compared speeds exceeds a predetermined amount indicating a change in the density of the combustion chamber gases.
Claim 8
Dependent Claim
24 words
The apparatus of claim 6 wherein the memory stores the motor speed a predetermined period of time after the motor begins driving the fan.
Claim 9
Dependent Claim
88 words
The apparatus of claim 6 wherein the furnace includes a fuel control providing a fuel signal representative of fuel being supplied to the combustion chamber and wherein the memory is responsive to the fuel signal for storing the motor speed when the fuel signal indicates that fuel is not being supplied to the combustion chamber and the comparing circuit is responsive to the fuel signal for comparing the stored speed to the motor speed when the fuel signal indicates that fuel is being supplied to the combustion chamber.
Claim 10
Dependent Claim
31 words
The apparatus of claim 1 further comprising a pressure switch providing a pressure signal for disabling the furnace when the pressure across the heat exchanger is less than a minimum pressure.
Claim 11
Dependent Claim
39 words
The apparatus of claim 1 wherein the circuit for defining the first and second sets of speed/torque curves includes a memory for storing a table of predefined speed/torque values corresponding to desired operation of the furnace under varying conditions.
Claim 12
Dependent Claim
114 words
The apparatus of claim 1 wherein the furnace discharges heated conditioned air to a space in response to a thermostatic control, said thermostatic control providing a thermostat signal as a function of the temperature of the air in the space, said thermostat signal having a DEMAND state for beginning operation of the furnace in the first operating state and a NO DEMAND state for ending operation of the furnace in the second operating state, and wherein the control circuit is responsive to the NO DEMAND state for generating the motor control signal whereby the motor drives the fan for a predetermined period of time after the furnace ends operation in the second operating state.
Claim 13
Dependent Claim
31 words
The apparatus of claim 11 further comprising a reset circuit responsive to the NO DEMAND state for resetting the control circuit after the furnace ends operation in the second operating state.
Claim 14
Dependent Claim
292 words
A furnace system operable in at least two operating states comprising: a combustion chamber producing combustion gases; an exhaust outlet for venting exhaust combustion gases from the combustion chamber; at least one heat exchanger for extracting heat from exhaust combustion chamber gases and for transferring heat to conditioned air; a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state; a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace system is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace system is in the second operating state.
Claim 15
Dependent Claim
292 words
A furnace system operable in at least two operating states comprising: a combustion chamber producing combustion gases; an exhaust outlet for venting exhaust combustion gases from the combustion chamber; at least one heat exchanger for extracting heat from exhaust combustion chamber gases and for transferring heat to conditioned air; a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state; a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace system is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace system is in the second operating state.
Claim 16
Dependent Claim
91 words
The system of claim 13 wherein the first operating state is defined as operation of the furnace system when combustion is not occurring in the combustion chamber and the second operating state is defined as operation of the furnace system when combustion is occurring in the combustion chamber whereby the density of the combustion chamber gases is greater in the first operating state than in the second operating state so that the fan increases in speed when the furnace system changes from the first operating state to the second operating state.
Claim 17
Dependent Claim
55 words
The system of claim 13 wherein the first and second operating states each has a low stage and a high stage and further comprising a furnace controller providing a furnace operating signal for causing the furnace system to operate in either the low stage or the high stage of the first and second operating states.
Claim 18
Dependent Claim
48 words
The system of claim 15 wherein the low and high stages as represented by the furnace operating signal correspond, respectively, to a first desired flow of fuel to the combustion chamber and a second desired flow of fuel to the combustion chamber greater than the first desired flow.
Claim 19
Dependent Claim
157 words
The system of claim 15 wherein the first and second sets of speed/torque curves defined by the defining circuit each include a speed/torque curve corresponding to the low stage and a speed/torque curve corresponding to the high stage and wherein the control circuit is responsive to the furnace operating signal for generating the motor control signal as a function of the low stage speed/torque curve of the first speed/torque curves in the low stage of the first operating state and as a function of the high stage speed/torque curve of the first speed/torque curves in the high stage of the first operating state and for generating the motor control signal as a function of the low stage speed/torque curve of the second speed/torque curves in the low stage of the second operating state and as a function of the high stage speed/torque curve of the second speed/torque curves in the high stage of the second operating state.
Claim 20
Dependent Claim
51 words
The system of claim 15 wherein the control circuit is responsive to the furnace operating signal for generating the motor control signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the low stage to the high stage thereby to rapidly increase the motor speed.
Claim 21
Dependent Claim
51 words
The system of claim 15 wherein the control circuit is responsive to the furnace operating signal for generating the motor control signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the high stage to the low stage thereby to rapidly decrease the motor speed.
Claim 22
Dependent Claim
79 words
The system of claim 13 further comprising a memory for storing the motor speed as represented by the speed signal and a circuit for comparing the stored speed to the motor speed as subsequently represented by the speed signal, and wherein the control circuit detects a change from the first operating state to the second operating state when the difference between the compared speeds exceeds a predetermined amount indicating a change in the density of the combustion chamber gases.
Claim 23
Dependent Claim
24 words
The system of claim 20 wherein the memory stores the motor speed a predetermined period of time after the motor begins driving the fan.
Claim 24
Dependent Claim
86 words
The system of claim 20 further comprising a fuel control providing a fuel signal representative of fuel being supplied to the combustion chamber and wherein the memory is responsive to the fuel signal for storing the motor speed when the fuel signal indicates that fuel is not being supplied to the combustion chamber and the comparing circuit is responsive to the fuel signal for comparing the stored speed to the motor speed when the fuel signal indicates that fuel is being supplied to the combustion chamber.
Claim 25
Dependent Claim
32 words
The system of claim 13 further comprising a pressure switch providing a pressure signal for disabling the furnace system when the pressure across the heat exchanger is less than a minimum pressure.
Claim 26
Dependent Claim
40 words
The system of claim 13 wherein the circuit for defining the first and second sets of speed/torque curves includes a memory for storing a table of predefined speed/torque values corresponding to desired operation of the furnace system under varying conditions.
Claim 27
Dependent Claim
118 words
The system of claim 13 wherein the furnace system discharges heated conditioned air to a space in response to a thermostatic control, said thermostatic control providing a thermostat signal as a function of the temperature of the air in the space, said thermostat signal having a DEMAND state for beginning operation of the furnace system in the first operating state and a NO DEMAND state for ending operation of the furnace system in the second operating state, and wherein the control circuit is responsive to the NO DEMAND state for generating the motor control signal whereby the motor drives the fan for a predetermined period of time after the furnace system ends operation in the second operating state.
Claim 28
Dependent Claim
32 words
The system of claim 25 further comprising a reset circuit responsive to the NO DEMAND state for resetting the control circuit after the furnace system ends operation in the second operating state.
Claim 29
Dependent Claim
42 words
The system of claim 15 wherein the furnace controller is responsive to the speed signal for disabling the furnace system when the speed signal indicates that the motor speed is less than a minimum speed or is greater than a maximum speed.
Claim 30
Independent Claim
309 words
A method of operating a draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said method comprising the steps of: driving the fan with a motor in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; providing a speed signal representative of the motor speed; defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; generating the motor control signal in response to the speed signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed; and generating the motor control signal in response to the speed signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 31
Independent Claim
309 words
A method of operating a draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said method comprising the steps of: driving the fan with a motor in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; providing a speed signal representative of the motor speed; defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; generating the motor control signal in response to the speed signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed; and generating the motor control signal in response to the speed signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 32
Dependent Claim
90 words
The method of claim 28 further comprising the steps of defining the first operating state as operation of the furnace when combustion is not occurring in the combustion chamber and defining the second operating state as operation of the furnace when combustion is occurring in the combustion chamber whereby the density of the combustion chamber gases is greater in the first operating state than in the second operating state so that the fan increases in speed when the furnace changes from the first operating state to the second operating state.
Claim 33
Dependent Claim
210 words
The method of claim 28 wherein the first and second operating states each has a low stage and a high stage and wherein the furnace includes a furnace controller providing a furnace operating signal for causing the furnace to operate in either the low stage or the high stage of the first and second operating states and wherein the first and second sets of speed/torque curves each include a speed/torque curve corresponding to the low stage and a speed/torque curve corresponding to the high stage and further comprising the steps of generating the motor control signal in response to the furnace operating signal as a function of the low stage speed/torque curve of the first speed/torque curves in the low stage of the first operating state and as a function of the high stage speed/torque curve of the first speed/torque curves in the high stage of the first operating state and generating the motor control signal in response to the furnace operating signal as a function of the low stage speed/torque curve of the second speed/torque curves in the low stage of the second operating state and as a function of the high stage speed/torque curve of the second speed/torque curves in the high stage of the second operating state.
Claim 34
Dependent Claim
51 words
The method of claim 30 further comprising the step of generating the motor control signal in response to the furnace operating signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the low stage to the high stage thereby to rapidly increase the motor speed.
Claim 35
Dependent Claim
51 words
The method of claim 30 further comprising the step of generating the motor control signal in response to the furnace operating signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the high stage to the low stage thereby to rapidly decrease the motor speed.
Claim 36
Dependent Claim
73 words
The method of claim 28 further comprising the steps of storing the motor speed as represented by the speed signal and comparing the stored speed to the motor speed as subsequently represented by the speed signal whereby a change from the first operating state to the second operating state is detected when the difference between the compared speeds exceeds a predetermined amount indicating a change in the density of the combustion chamber gases.
Claim 37
Dependent Claim
30 words
The method of claim 33 wherein the step of storing the motor speed includes storing the motor speed a predetermined period of time after the motor begins driving the fan.
Claim 38
Dependent Claim
90 words
The method of claim 33 wherein the furnace includes a fuel control providing a fuel signal representative of fuel being supplied to the combustion chamber and wherein the step of storing the motor speed includes storing the motor speed when the fuel signal indicates that fuel is not being supplied to the combustion chamber and wherein the step of comparing the stored speed to the motor speed includes comparing the stored speed to the motor speed when the fuel signal indicates that fuel is being supplied to the combustion chamber.
Claim 39
Dependent Claim
31 words
The method of claim 28 further comprising the step of providing a pressure signal for disabling the furnace when the pressure across the heat exchanger is less than a minimum pressure.
Claim 40
Dependent Claim
39 words
The method of claim 28 wherein the step of defining the first and second sets of speed/torque curves includes storing in a memory a table of predefined speed/torque values corresponding to desired operation of the furnace under varying conditions.
Claim 41
Dependent Claim
114 words
The method of claim 28 wherein the furnace discharges heated conditioned air to a space in response to a thermostatic control, said thermostatic control providing a thermostat signal as a function of the temperature of the air in the space, said thermostat signal having a DEMAND state for beginning operation of the furnace in the first operating state and a NO DEMAND state for ending operation of the furnace in the second operating state, and further comprising the step of generating the motor control signal in response to the NO DEMAND state whereby the motor drives the fan for a predetermined period of time after the furnace ends operation in the second operating state.
Claim 42
Independent Claim
300 words
A method of operating a furnace system in at least two operating states, said furnace system including a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace system and also including at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air and a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said method comprising the steps of: driving the fan with a motor in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; providing a speed signal representative of the motor speed; defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; generating the motor control signal in response to the speed signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed; and generating the motor control signal in response to the speed signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace system is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace system is in the second operating state.
Claim 43
Independent Claim
300 words
A method of operating a furnace system in at least two operating states, said furnace system including a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace system and also including at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air and a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said method comprising the steps of: driving the fan with a motor in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; providing a speed signal representative of the motor speed; defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; generating the motor control signal in response to the speed signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed; and generating the motor control signal in response to the speed signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace system is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace system is in the second operating state.
Claim 44
Dependent Claim
93 words
The method of claim 39 further comprising the steps of defining the first operating state as operation of the furnace system when combustion is not occurring in the combustion chamber and defining the second operating state as operation of the furnace system when combustion is occurring in the combustion chamber whereby the density of the combustion chamber gases is greater in the first operating state than in the second operating state so that the fan increases in speed when the furnace system changes from the first operating state to the second operating state.
Claim 45
Dependent Claim
55 words
The method of claim 39 wherein the first and second operating states each has a low stage and a high stage and further comprising the step of providing a furnace operating signal for causing the furnace system to operate in either the low stage or the high stage of the first and second operating states.
Claim 46
Dependent Claim
158 words
The method of claim 41 wherein the first and second sets of speed/torque curves each include a speed/torque curve corresponding to the low stage and a speed/torque curve corresponding to the high stage and further comprising the steps of generating the motor control signal in response to the furnace operating signal as a function of the low stage speed/torque curve of the first speed/torque curves in the low stage of the first operating state and as a function of the high stage speed/torque curve of the first speed/torque curves in the high stage of the first operating state and generating the motor control signal in response to the furnace operating signal as a function of the low stage speed/torque curve of the second speed/torque curves in the low stage of the second operating state and as a function of the high stage speed/torque curve of the second speed/torque curves in the high stage of the second operating state.
Claim 47
Dependent Claim
51 words
The method of claim 41 further comprising the step of generating the motor control signal in response to the furnace operating signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the low stage to the high stage thereby to rapidly increase the motor speed.
Claim 48
Dependent Claim
51 words
The method of claim 41 further comprising the step of generating the motor control signal in response to the furnace operating signal independent of the second speed/torque curves when the furnace operating signal indicates a change from the high stage to the low stage thereby to rapidly decrease the motor speed.
Claim 49
Dependent Claim
73 words
The method of claim 39 further comprising the steps of storing the motor speed as represented by the speed signal and comparing the stored speed to the motor speed as subsequently represented by the speed signal whereby a change from the first operating state to the second operating state is detected when the difference between the compared speeds exceeds a predetermined amount indicating a change in the density of the combustion chamber gases.
Claim 50
Dependent Claim
30 words
The method of claim 45 wherein the step of storing the motor speed includes storing the motor speed a predetermined period of time after the motor begins driving the fan.
Claim 51
Dependent Claim
88 words
The method of claim 45 further comprising the step of providing a fuel signal representative of fuel being supplied to the combustion chamber and wherein the step of storing the motor speed includes storing the motor speed when the fuel signal indicates that fuel is not being supplied to the combustion chamber and wherein the step of comparing the stored speed to the motor speed includes comparing the stored speed to the motor speed when the fuel signal indicates that fuel is being supplied to the combustion chamber.
Claim 52
Dependent Claim
32 words
The method of claim 39 further comprising the step of providing a pressure signal for disabling the furnace system when the pressure across the heat exchanger is less than a minimum pressure.
Claim 53
Dependent Claim
40 words
The method of claim 39 wherein the step of defining the first and second sets of speed/torque curves includes storing in a memory a table of predefined speed/torque values corresponding to desired operation of the furnace system under varying conditions.
Claim 54
Dependent Claim
119 words
The method of claim 39 further comprising the step of providing a thermostat signal as a function of the temperature of air in a space wherein the furnace system discharges heated conditioned air to the space in response to the thermostat signal, said thermostat signal having a DEMAND state for beginning operation of the furnace system in the first operating state and a NO DEMAND state for ending operation of the furnace system in the second operating state, and further comprising the step of generating the motor control signal in response to the NO DEMAND state whereby the motor drives the fan for a predetermined period of time after the furnace system ends operation in the second operating state.
Claim 55
Dependent Claim
36 words
The method of claim 39 further comprising the step of disabling the furnace system when the speed signal indicates that the motor speed is less than a minimum speed or is greater than a maximum speed.
Claim 56
Dependent Claim
326 words
A draft inducer system for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger differs from a first operating state to a second operating state, said system comprising: a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger wherein the density of the combustion chamber gases flowing across the fan differs from the first operating state to the second operating state; a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 57
Dependent Claim
326 words
A draft inducer system for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger differs from a first operating state to a second operating state, said system comprising: a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger wherein the density of the combustion chamber gases flowing across the fan differs from the first operating state to the second operating state; a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing across the fan; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 58
Dependent Claim
313 words
A draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the combustion chamber for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing through the combustion chamber and across the heat exchanger differs from a first operating state to a second operating state, said apparatus comprising: a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing through the combustion chamber; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 59
Dependent Claim
313 words
A draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the combustion chamber for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing through the combustion chamber and across the heat exchanger differs from a first operating state to a second operating state, said apparatus comprising: a motor including a shaft for driving the fan in response to a motor control signal so that different motor speeds result as a function of the density of the combustion chamber gases flowing through the combustion chamber; a speed circuit providing a speed signal representative of the motor speed; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the speed signal for generating the motor control signal as a function of the first set of speed/torque curves until the speed signal indicates that the motor speed has reached a predetermined speed and for generating the motor control signal as a function of the second set of speed/torque curves after the speed signal indicates that the motor speed has reached the predetermined speed whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 60
Dependent Claim
310 words
A draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said apparatus comprising: a motor including a shaft for driving the fan in response to a motor control signal so that different motor torques result as a function of the density of the combustion chamber gases flowing across the fan; a torque circuit providing a torque signal representative of the motor torque; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the torque signal for generating the motor control signal as a function of the first set of speed/torque curves until the torque signal indicates that the motor speed has reached a predetermined torque and for generating the motor control signal as a function of the second set of speed/torque curves after the torque signal indicates that the motor torque has reached the predetermined torque whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
Claim 61
Dependent Claim
310 words
A draft inducer apparatus for use with a furnace that includes a combustion chamber producing combustion gases and an exhaust outlet for venting exhaust combustion gases from the furnace and that also includes at least one heat exchanger for extracting heat from exhaust combustion chamber gases and transferring heat to conditioned air, and for use with a fan for moving the combustion chamber gases through the exhaust outlet for inducing a draft in the combustion chamber that causes a pressure drop across the heat exchanger, said furnace being operable in at least two operating states wherein the density of the combustion chamber gases flowing across the heat exchanger and the fan differs from a first operating state to a second operating state, said apparatus comprising: a motor including a shaft for driving the fan in response to a motor control signal so that different motor torques result as a function of the density of the combustion chamber gases flowing across the fan; a torque circuit providing a torque signal representative of the motor torque; a circuit for defining first and second sets of speed/torque curves corresponding to a desired pressure across the heat exchanger; and a control circuit responsive to the torque signal for generating the motor control signal as a function of the first set of speed/torque curves until the torque signal indicates that the motor speed has reached a predetermined torque and for generating the motor control signal as a function of the second set of speed/torque curves after the torque signal indicates that the motor torque has reached the predetermined torque whereby the motor will operate in accordance with one or more of the first speed/torque curves when the furnace is in the first operating state and in accordance with one or more of the second speed/torque curves when the furnace is in the second operating state.
References Cited (Backward Citations)
US2679607A
Cited
US3426273A
Cited
US3517308A
Cited
US3550426A
Cited
US3765234A
Cited
US3678352A
Cited
US3679953A
Cited
US3740629A
Cited
US3849718A
Cited
US3824446A
Cited
US3818310A
Cited
US3859577A
Cited
US3879646A
Cited
US3818298A
Cited
US3859549A
Cited
US4044287A
Cited
US3866099A
Cited
US3940680A
Cited
US4030005A
Cited
US4005347A
Cited
US4390826A
Cited
US4654566A
Cited
US5075608A
Cited
US4169990A
Cited
US3955130A
Cited
US4012677A
Cited
US4097789A
Cited
US4099111A
Cited
US4119892A
Cited
US4009825A
Cited
US4167691A
Cited
US4253053A
Cited
US4274036A
Cited
US4371823A
Cited
US4360770A
Cited
US4392417A
Cited
GB2056044B
Cited
US4384241A
Cited
US4376261A
Cited
US4374347A
Cited
US4449079A
Cited
US4556827A
Cited
US4379984A
Cited
US4401933A
Cited
US4389886A
Cited
US4519540A
Cited
EP0073717B1
Cited
US4563619A
Cited
US4504881A
Cited
US4535275A
Cited
US4467657A
Cited
US4520296A
Cited
US4499407A
Cited
US4578623A
Cited
FR2547075B1
Cited
US4774656A
Cited
US4500821A
Cited
US4710684A
Cited
US4533986A
Cited
US4678974A
Cited
US4734627A
Cited
US4540921A
Cited
US4748388A
Cited
US4544868A
Cited
US4644233A
Cited
US4645450A
Cited
US4558264A
Cited
US4891537A
Cited
US4733146A
Cited
US5268623A
Cited
US4820317A
Cited
US4704567A
Cited
US4638233A
Cited
US4651079A
Cited
US4860231A
Cited
US4707646A
Cited
US4648551A
Cited
US4851751A
Cited
US4755728A
Cited
US4703747A
Cited
US4729207A
Cited
US4667480A
Cited
US4806833A
Cited
US4707650A
Cited
US4737674A
Cited
EP0279771B1
Cited
US4818924A
Cited
US4743815A
Cited
US4757241A
Cited
US4835448A
Cited
US4972134A
Cited
US4940912A
Cited
US4870332A
Cited
US4937467A
Cited
US4858676A
Cited
US5057733A
Cited
US4836096A
Cited
US4935861A
Cited
US4978896A
Cited
US5005115A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-03-31 | 2000-09-30 | 2001-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-03-31 | 2004-09-30 | 2005-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-03-31 | 2008-09-30 | 2009-04-01 | $7700.00 | Window Closed / Lapsed |