DISTRIBUTED AIR FLOW METHOD AND SYSTEM

Description

FIELD OF THE INVENTION

The present invention relates to the field and art of building ventilation systems and operation thereof.

BACKGROUND OF THE INVENTION

The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.

Wherever there is contagion, ventilation can be a critical concern. The ideal hospital room for treating someone with an illness that spreads through the air (of which COVID-19 is one highly relevant example but not the only one) might preferably be well-ventilated with good air flow—but also, none of that air flowing into the rest of the hospital to infect everybody else! This type of concern alone gives a building such as a hospital more complex and multifaceted HVAC needs than most standard prior art HVAC systems are designed for, and the stopgap solution for isolating part of a hospital's atmosphere (such as to create a quarantine zone) as practiced currently is often hospital workers manually, with a screwdriver or other tool, adjusting vents in different rooms to suit the current function of that room. As one might imagine, this method can be error-prone (a manually-adjusted vent is easy to forget or overlook), and makes it difficult to coordinate multiple rooms and their vents into a cohesive area, such as a ward or wing housing all patients with the same affliction. Differentials in air pressure between areas can also become a problem. This whole situation can also be a tedious inconvenience for all involved.

High-tech infectious disease laboratories tend to have better high-tech ventilation, but such systems are often out of a hospital's price range.

For at least the above rationales, there is a widely noted imperative, and a long felt need, to improve specialized HVAC infrastructure affordably and efficiently, particularly for, but not limited to, better supporting the nuanced ventilation environment of a hospital building setting.

SUMMARY OF THE INVENTION

Towards these and other objects of the method of the present invention (hereinafter, “the invented method”) that are made obvious to one of ordinary skill in the art in light of the present disclosure, the present invention is applied to maintain a near constant pre-set volume of airflow into and/or out of an air vent. The invented method further provides, with certain additional alternate preferred embodiments of the present invention, a capability to maintain a near constant volume of airflow into and/or out of a room. The airflow level may be calibrated or preset prior to initiating the performance of one or more aspects of the present invention.

Certain various alternate preferred embodiments of the invented method comprise one or more of the following aspects or elements: (a.) positioning a first thermistor and a second thermistor within a same air duct, whereby the first thermistor and the second thermistor are exposed to a same volumetric air flow; (b.) establishing the volumetric airflow through the air duct at a specified flow value; (c.) selecting a desired temperature delta to be maintained between the first thermistor and the second thermistor, the desired temperature delta correlated to a resistance delta to be exhibited between the first thermistor resistance and the second thermistor resistance; (d.) imposing a first reference current through the first thermistor, whereby the measured first thermistor resistance value is substantially determined by a contemporaneous aggregate air temperature of the air flow; (e.) imposing a variable second reference current through the second thermistor, whereby a variably imposed resistance level of the second thermistor is variably and substantially determined by a magnitude of heat received by the second thermistor from the second reference current; (f.) positioning a servo-motor controlled air flow damper within the air duct; and/or (g.) directing the servo-motor to adjust the air flow damper to drive the second thermistor to a resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.

Certain still other various alternate preferred embodiments of the invented method comprises positioning a device relative to an air duct, the air duct channeling a volumetric airflow, the devise comprising, one or more of the following aspects or elements, additionally or alternatively: (1.) a controller logic communicatively coupled with a first thermistor and a second thermistor positioned within the air duct, whereby the first thermistor and the second thermistor are exposed to a same volumetric air flow and the controller logic monitors a first thermistor resistance value of the first thermistor and a contemporaneous second resistance value resistance value of the second thermistor; (2.) a memory element communicatively coupled with the controller logic, the memory element storing a resistance delta value; (3.) a means to impose a first reference voltage across the first thermistor, whereby the first thermistor resistance value is substantially determined by a contemporaneous aggregate air temperature of the air flow; (4.) a means to impose a variable second reference voltage across the second thermistor, whereby a variably imposed resistance level of the second thermistor is variably and substantially determined by a combination of a magnitude of heat received by the second thermistor from the current through the second thermistor given the second reference voltage and heat transferred from the second thermistor to the air flow; (5.) a servo-motor controlled air flow damper comprising and air flow damper controlled by the server motor, and the servo-motor managed by power adjustably controlled by the controller, and the air flow damper positioned within the air duct; and/or (6.) the controller adapted to receive instantaneous resistance measurements from both the first thermistor and the second thermistor, and thereupon to direct the servo-motor to adjust the air flow damper to modify volumetric airflow of the air duct and thereby cause the second thermistor to achieve the resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a line drawing presenting a perspective view of a preferred exemplary embodiment of the invention “System One” installed in an air duct;

FIG. 2 is a block diagram of the control system of the System One of FIG. 1;

FIG. 3 is a flowchart of a tuning process for the System One of FIG. 1;

FIG. 4 is a block diagram illustrating concepts pertaining to air flow, as practiced in the System One of FIG. 1;

FIG. 5 is a line drawing presenting a first alternative vent for use in the System One of FIG. 1, which is controlled by a rack and pinion;

FIG. 6 is a line drawing presenting a second alternative vent for use in the System One of FIG. 1, which is controlled by a linear motor;

FIGS. 7a through 7d are line drawings presenting an alternate preferred exemplary embodiment of the invention employing a butterfly-style damper controlled by a rotating servo motor for use in the System One of FIG. 1;

FIG. 8 illustrates one preferred exemplary embodiment of the control logic of System One comprising a microprocessor-based system of FIG. 1;

FIG. 9 is a flowchart of the firmware executed by the control logic of FIG. 8;

FIG. 10 illustrates another preferred embodiment of the invention comprising several instances of System One of FIG. 1 combined with a central server;

FIG. 11 illustrates an additional alternate preferred exemplary embodiment of the invention, or System Two, installed in an air duct;

FIG. 12 is a block diagram of the control system of System Two of FIG. 11; and

FIG. 13 is a flowchart of the tuning process for System Two of FIG. 11;

FIG. 14 illustrates a preferred alternate exemplary embodiment of the control logic of System Two of FIG. 11 comprising a microprocessor-based system; and

FIG. 15 is a flowchart of the firmware executed by the control logic of FIG. 14.

FIG. 16 illustrates yet another alternate preferred exemplary embodiment of the invention comprising several instances of System Two of FIG. 11 combined with a central server.

DETAILED DESCRIPTION OF DRAWINGS

In the following detailed description of the invention, numerous details, examples, and embodiments of the invention are described. However, it will be clear and apparent to one skilled in the art that the invention is not limited to the embodiments set forth and that the invention can be adapted for any of several applications.

It is to be understood that this invention is not limited to particular aspects of the present invention described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as the recited order of events.

Where a range of values is provided herein, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the range's limits, an excluding of either or both of those included limits is also included in the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the methods and materials are now described.

It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

When elements are referred to as being “connected” or “coupled,” the elements can be directly connected or coupled together or one or more intervening elements may also be present. In contrast, when elements are referred to as being “directly connected” or “directly coupled,” there are no intervening elements present.

In the specification and claims, references to “a processor” include multiple processors. In some cases, a process that may be performed by “a processor” may be actually performed by multiple processors on the same device or on different devices. For the purposes of this specification and claims, any reference to “a processor” shall include multiple processors, which may be on the same device or different devices, unless expressly specified otherwise.

The subject matter may be embodied as devices, systems, methods, and/or computer program products. Accordingly, some or all of the subject matter may be embodied in hardware and/or in software (including firmware, resident software, micro-code, state machines, gate arrays, etc.) Furthermore, the subject matter may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. In the context of this document, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

The computer-usable or computer-readable medium may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media.

Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by an instruction execution system. Note that the computer-usable or computer-readable medium could be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, of otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.

When the subject matter is embodied in the general context of computer-executable instructions, the embodiment may comprise program modules, executed by one or more systems, computers, or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.

Additionally, it should be understood that any transaction or interaction described as occurring between multiple computers is not limited to multiple distinct hardware platforms, and could all be happening on the same computer. It is understood in the art that a single hardware platform may host multiple distinct and separate server functions.

Throughout this specification, like reference numbers signify the same elements throughout the description of the figures.

Referring now generally to the Figures and particularly to FIG. 1, FIG. 1 illustrates a physical installation in an air duct 100 of an invented system (“the System One 102”). It is noted that certain alternative and preferred embodiments of the invention may apply to regulating the flow of any gas through any kind of duct. In the System One 102, a first thermistor 104 and a second thermistor 106 (“the thermistors 104 & 106”) are positioned within the same air duct 100. The thermistors 104 & 106 are positioned so as to receive a same volumetric flow of air 108 (“the air flow 108”). It is noted that FIG. 4 further subdivides the air flow 108 into supply air flow 400, return air flow 402, exhaust air flow 404, and the air flow 108 as presented in FIG. 1 might be an instance of any of those, or a flow of any other kind of air or gas through a duct. It is noted that certain preferred embodiments of the invention might employ any variety of sensors capable of measuring thermal conductivity at two different delta temperatures for the same volume of the air flow 108.

A first reference current 110 is applied to the first thermistor 104. This is a relatively low current, so that the first thermistor 104 temperature primarily depends on an ambient temperature 112. Thus a first voltage 114 measured across the first thermistor 104 is largely a measurement of the ambient temperature 112.

A second reference current 116 applied to the second thermistor 106 is a higher current that significantly heats the thermistor. The temperature of the second thermistor 106 is mitigated by convection cooling from the air flow 108. Thus a second voltage 118 measured across the second thermistor 106 is partly a measurement of the thermal convection cooling afforded by the air flow 108.

Given the first reference current 110 and the second reference current 116, the first voltage measurement 114 and the second voltage measurement 118 are used by a control logic 120 to form an output control signal 122. In various embodiments of this invention, this control logic 120 can consist of an analog circuit, a digital circuit employing simple digital logic or programmable digital logic, or a microprocessor or microcontroller based system.

The product of the control logic 120 is the control signal 122 representing a commanded absolute position of an airflow damper 124. An airflow damper actuator 126 receives the control signal 122 and moves the airflow damper 124 to the desired position, ranging from fully open, providing the largest volume of airflow and the least resistance to the movement of air or gas in the vent, to fully closed, providing the smallest volume of airflow and the greatest resistance to the movement of air or gas in the vent.

In FIG. 1, the air flow damper 124 and damper actuator 126 as illustrated consist of a plurality of vanes or vents coupled with a rack and pinion motivator. However, the damper 124 could be any physical assembly that constricts airflow, and the actuator 126 could be any electromechanical actuator that could position such a damper 124. Specifically, the actuator 126 could consist of a linear servo motor. Specifically, the damper 124 could be controllable by a rotating servo motor, and the actuator 126 could in this instance be a rotating servo motor.

The control logic 120 persists a desired temperature delta “Set Point” 128. This persistent Set Point 128 can range from a potentiometer setting in an analog embodiment of the control logic to a storage location in a digital memory 130 as illustrated in FIG. 1. The control logic 120 also contains a measured resistance delta “Delta” 132. The control logic can carry this Delta 132 as an analog signal on a wire in an analog embodiment of the control logic or as the illustrated storage location in the digital memory 130. Certain alternate preferred embodiments of the invention may contain pre-specified resistance value tolerance ranges 134 for the first thermistor 104, the second thermistor 106, or both. These ranges can be specified by pairs of potentiometers in the case of analog control logic to, as illustrated, storage in the digital memory 130.

The second reference current 116 supplied to the second thermistor 106 may be a pulse-width-modulated signal 136 as illustrated in FIG. 1. This is a constant voltage signal where the duty cycle of the square wave 136 determines the RMS voltage and therefore the current flowing through the second thermistor 106. In other preferred embodiments, this reference current may be applied employing a linear voltage signal and amplifier.

Referring now generally to the Figures and particularly to FIG. 2, FIG. 2 is a block diagram of the System One 102 as shown in FIG. 1. A first current 200 applied to a first thermistor 202 in FIG. 2 represents the first current 110 applied to the first thermistor 104 in FIG. 1. A second current 204 applied to a second thermistor 206 in FIG. 2 represents the second current 116 applied to the second thermistor 106 in FIG. 1. The applied currents could be provided by a linear amplifier or via a pulse width modulated (PWM) signal 136 of constant peak-to-peak voltage but varying duty cycle to provide a specified current.

A first voltage 208 measured across the first thermistor 202 in FIG. 2 corresponds to the first voltage 114 measured across the first thermistor 104 in FIG. 1. Given a reference current 200, this voltage 208 is a measurement of resistance across the first thermistor 202. This resistance measurement 208, given the thermistor's properties are known, is also a measurement of the thermistor's temperature. In some embodiments of the invention where the control logic is digital, this first voltage 208, properly scaled, is fed into a first analog-to-digital converter (ADC) 210 for conversion into a digital representation of the first measured resistance 212 for use by the control logic 214. In embodiments of the invention where the control logic is analog, the voltage signal 208 itself can be used to represent the first measured resistance 212.

A second voltage 216 measured across a second thermistor 206 in FIG. 2 corresponds to the second voltage 118 measured across the second thermistor 106 in FIG. 1. Given a reference current 204, this voltage 216 is a measurement of resistance across the second thermistor 206. This resistance measurement 216, given the thermistor's properties are known, is also a measurement of the thermistor's temperature. In some embodiments of the invention where the control logic is digital, this second voltage 216, properly scaled, is fed into a second analog-to-digital converter (ADC) 218 for conversion into a digital representation of the second measured resistance 220 for use by the control logic 214.

The first measured resistance 212, properly scaled, is subtracted from the second measured resistance 220, also properly scaled, to form a measured resistance delta 222, which appears as 132 in FIG. 1. This measured resistance delta 222 is then compared to a previously established set point 224 (represented by 128 in FIG. 1) to form the control signal 226 sent to the position controller 228. This control signal 226 corresponds to the control signal 122 in FIG. 1 that is sent to the airflow damper actuator 126 to command the position of the airflow damper 124. The position controller 228 in FIG. 2 corresponds to the airflow damper actuator 126 in FIG. 1.

Note that in the case of digital control logic 214, any measured, calculated, or produced value or measurement may be stored in digital memory 130, specifically, but not limited to, the calculated resistance or temperature delta, or Delta, 222 and the resistance or temperature delta set point, or Set Point, 224. The measured resistance or temperature delta 222 could be either continuously updated or updated at regular intervals. The resistance or temperature delta set point 224 could be updated either manually, semi-automatically, or automatically to allow the air duct to settle on a different volume of air flow.

If the control logic 214 consists of a microprocessor or microcontroller based system capable of supporting a network stack, it may interface with a network or wireless transceiver 230. Such a transceiver 230 would allow the control logic to be remotely configured or reconfigured, including but not limited to setting the first and second reference currents 200 and 204, setting scaling factors and limits for incoming resistance measurements 212 and 220, setting a scaling factor and limits for the resistance delta 222, setting a set point 224, and setting a scaling factor and limits for the control signal 226.

Multiple instances of embodiments of this invention could be combined together to control the air flow in a duct system of arbitrary complexity. These systems could be each manually settable or networked together and controlled centrally. Identical or different embodiments and versions of this invention could be combined in these ways to control a larger system of air flow.

Referring now generally to the Figures and particularly to FIG. 3, FIG. 3 is a flowchart for tuning the control system of an embodiment of the invention where reference currents are used to measure varying voltages. To begin the process, step 1, a specified flow value of volumetric airflow is established 300. This volumetric airflow is the same flow represented in FIG. 1 as volumetric airflow 108 through air duct 100. In step two, 302, of the process of FIG. 3, reference currents are set for the first and second thermistors. In FIG. 1, these are represented by 110 and 116. In FIG. 2, these are represented by 200 and 204. In step 3, 304, a resulting candidate set point is measured. In step 4, 306, provided appropriate currents, limits, and scaling factors have been successfully applied to yield an effective control signal, the process can proceed to step 5, 308. If an effective control signal has not been produced, the process proceeds back to step 1, 300, where all currents, factors, and limits may be reexamined and adjusted. Finally, in step 6, 308, a set point for the control logic is established and applied. Note that the whole or any portion of the process described by FIG. 3 can be implemented manually, semi-automatically with computer assistance, or in a fully automatic fashion.

Referring now generally to the Figures and particularly to FIG. 4, FIG. 4 illustrates differing possible types of the air flow 108. An air duct system 406 is presented here for example, which might represent any network of ducts such as one including the air duct 100 of FIG. 1. The supply air flow 400 is new air or gas substantially supplied from an external source to the substantially closed environment of the air duct system 406. The exhaust air flow 404 is air or gas substantially expelled to an external environment from the substantially closed environment of the air duct system 406. Return air flow 402 is air or gas substantially moving within the substantially closed environment of the air duct system 406. For example, in the case of an air conditioning system, the supply air flow 400 could be pumped in from outside, the exhaust air flow 404 could be pumped to the outside, and the return air flow 402 might be the air flow 108 circulating within the building. Note that even in a substantially leaky air flow system where the air flow 108 could be described as part supply 400, part exhaust 404, and part return 402, if the air flow 108 travels through an instance of the air duct system 406, the invention may be applied to it. These types of the air flow 108 are merely a convenient possible subcategorization of the air flow 108.

Referring now generally to the Figures and particularly to FIG. 5, FIG. 5 is a more detailed illustration of a rack and pinion operated vent 124 as used in the System One 102, in FIG. 1 as the damper 124, and the System Two 1102 in FIG. 11 as the air flow damper 1124. The rack and pinion operated vent 500 may comprise at least a series of vanes 502 (“the vanes 502”) attached to each side of the rack and pinion operated vent 500 which may be adjusted to any position from fully open to fully closed. A rack 504 is attached to the edges of the vanes 502. Moving the rack 504 vertically rotates the positioning of the vanes 502 in the range between fully open, being the least restricting of the air flow 108, to fully closed, being the most restricting of the air flow 108. A pinion 506 is in high-friction contact with the rack 504. Generally, the pinion 506 is a gear and the flat rack 504 has corresponding grooves that capture the teeth of the gear of the pinion 506. As the pinion 506 rotates, the rack 504 is driven vertically, thus positioning the vanes 502. The pinion 506 may be manually rotated, may be driven by a servo motor, or may be repositioned by any positioning device able to apply torque.

Referring now generally to the Figures and particularly to FIG. 6, FIG. 6 is an illustration of a series of vanes 600 driven by a linear motor 602. Here a series of vanes 600 attached to each side of a vent 604 may be adjusted to any position from fully open to fully closed. A platen 606 is attached to the edges of these vanes. Moving the platen vertically effects the positioning of the vanes in the range from fully open, being the least restricting of air flow, to fully closed, being the most restricting of air flow. A forcer or stator 602 is held in contact with the platen 606 generally with magnetic force possibly re-enforced by a guide bar or linear bearings. Generally, the stator 602 is a series of electromagnets and the platen 606 has corresponding permanent magnets that allow the stator 602 to force the platen 606 vertically by controlling the relative electric currents in its windings. As the stator 602 varies the magnetic fields created by its windings, the platen 606 is driven vertically, thus positioning the vanes 600. The linear motor may be a linear servomotor or a linear stepper motor.

Referring now generally to the Figures and particularly to FIG. 7a through 7d, FIG. 7a is an isometric view of an alternate preferred embodiment of the invention employing a butterfly-style damper 700 shown in the closed position. FIG. 7b is a top view of the same alternate preferred embodiment of the invention with the butterfly-style damper 700 closed as in FIG. 7a. FIG. 7c is an isometric view of the same alternate preferred embodiment of FIG. 7a, but with the butterfly-style damper 700 shown in the open position. FIG. 7d is a top view of the same alternate preferred embodiment of the invention with the butterfly-style damper 700 open as in FIG. 7c. The butterfly-style damper is opened and closed by a gear 702 that turns the inner ring 704. The inner ring 704 turns inside of an outer ring 706, which is fixed in the air duct. A servo motor 708 turns the gear 702. The servo motor 708 is controlled by the circuit board 710. A non-heated thermistor 712 and a heated thermistor 714 provide the circuit board 710 with the information required to characterize air flow rate.

FIG. 8 illustrates a microprocessor-based embodiment of the control logic of the invention. Here, a microprocessor 800 generally executes a firmware program 802 stored in a persistent flash memory 804. In some instances, such as during a firmware update, the processor may also execute instructions temporarily stored in a RAM 806. The flash memory 804 and the RAM 806 are always attached to the microprocessor 800 via a memory bus 808 or busses.

The microprocessor may have a separate I/O bus 810, or all components may be memory-mapped. Attached to this I/O bus 810 are peripherals to the core microprocessor system consisting of microprocessor 800, flash memory 804, and RAM 806. The processor 800 may read the voltage across the first thermistor, properly scaled, using ADC one, 812. The processor 800 may read the voltage across the second thermistor, properly scaled, using ADC two, 814. Finally, the processor 800 may output the position command by manipulating the position output 816.

Referring to the figures and most specifically to FIG. 9, FIG. 9 is a flowchart of the firmware program 802 executed by the microprocessor-based embodiment of the control logic of the invention illustrated by FIG. 8. After reset, the program reads its persistent settings and initializes its peripherals 900. It then enters the main event loop, starting with step two, 902. In step two 902, the program latches both analog-to-digital converters (ADCs) 210 & 218 in FIGS. 2 or 812 & 814 in FIG. 8. These values are then read into RAM 806. In step three 904, a new position is calculated. First, the inputs from the ADCs 210 & 218 in FIG. 2 or 812 & 814 in FIG. 8 are subtracted to form the Delta. Then, the Delta is subtracted from the Set Point and properly scaled to form the new position. In step four 906, this new position command is output. Then the process begins again beginning with step two, 902. In exceptional cases, for example, an emergency stop button is pressed, step five 908 is executed, whereby the program terminates after the system is placed in a safe state.

Referring to the figures and most specifically to FIG. 10, also a preferred embodiment of the invention are several instances of a preferred embodiment such as System One 102 shown in FIG. 1. Several instances 1000, with four such instances shown in the illustration, are connected via a network connection 1002 with a central server 1004. The central server 1004 executes a software program that coordinates the activity among these instances to create air flow systems of arbitrary complexity.

Referring to the figures and primarily to FIG. 11, FIG. 11 illustrates a physical installation of System Two 1102 in an air duct 1100. Note that the invention can apply to regulating the flow of any gas through any kind of duct. In the embodiment illustrated by FIG. 11, a first thermistor 1104 and a second thermistor 1106 are positioned within the same air duct 1100. The thermistors 1104 and 1106 are positioned so as to receive a same volumetric flow of air 1108. Note that this air flow 1108 could be as illustrated in FIG. 4 any of the set of supply air flow 400, return air flow 402, exhaust air flow 404, or any other kind of air or gas flow through a duct. Note that the invention could employ any sensors capable of measuring thermal conductivity at two different delta temperatures for the same gas flow 1108.

A first reference voltage 1110 is applied across the first thermistor 1104. This is a relatively low voltage, so that the first thermistor 1104 temperature primarily depends on an ambient temperature 1112 being measured. Thus a first current 1114 measured through the first thermistor 1104 is largely a measurement of the ambient temperature 1112.

A second reference voltage 1116 applied to the second thermistor 1106 is a higher voltage that significantly heats the thermistor, or the thermistor has a lower base resistance than the first thermistor. Based on the volume of airflow or gas flow 1108 present, the temperature of the second thermistor 1106 is mitigated by convection cooling from the surrounding air or gas flow 1108. Thus a second current 1118 measured through the second thermistor 1106 is partly a measurement of the thermal convection cooling afforded by the airflow or gas flow 1108.

Given the first reference voltage 1110 and the second reference voltage 1116, the first current measurement 1114 and the second current measurement 1118 are used by a control logic 1120 to form an output control signal 1122. In various embodiments of this invention, this control logic 1120 can consist of an analog circuit, a digital circuit employing simple digital logic or programmable digital logic, or a microprocessor or microcontroller based system.

The product of the control logic 1120 is the control signal 1122 representing a commanded absolute position of an airflow damper 1124. An airflow damper actuator 1126 receives the control signal 1122 and moves the airflow damper 1124 to the desired position, ranging from fully open, providing the largest volume of airflow and the least resistance to the movement of air or gas in the vent, to fully closed, providing the smallest volume of airflow and the greatest resistance to the movement of air or gas in the vent.

In FIG. 11, the air flow damper 1124 and damper actuator 1126 as illustrated consist of a plurality of vanes or vents coupled with a rack and pinion motivator. However, the damper 1124 could be any physical assembly that constricts airflow, and the actuator 1126 could be any electromechanical actuator that could position such a damper 1124. Specifically, the actuator 1126 could consist of a linear servo motor. Specifically, the damper 1124 could be controllable by a rotating servo motor, and the actuator 1126 could in this instance be a rotating servo motor.

The control logic 1120 persists a desired temperature delta “Set Point” 1128. This persistent Set Point can range from a potentiometer setting in an analog embodiment of the control logic to a storage location in a digital memory 1130 as illustrated in FIG. 11. The control logic 1120 also contains a measured resistance delta “Delta” 1132. The control logic can carry this Delta 1132 as an analog signal on a wire in an analog embodiment of the control logic or as a storage location in the digital memory 1130. Certain alternate preferred embodiments of the invention may contain pre-specified resistance value tolerance ranges 1134 for the first thermistor 1104, the second thermistor 1106, or both. These ranges can be specified by pairs of potentiometers in the case of analog control logic to storage in the digital memory 1130.

Referring to the figures and specifically FIG. 12, this is a block diagram of System Two 1102 as shown in FIG. 11. A first voltage 1200 applied across a first thermistor 1202 in FIG. 12 represents the first voltage 1110 applied to the first thermistor 1104 in FIG. 11. A second voltage 1204 applied to a second thermistor 1206 in FIG. 12 represents the second voltage 1116 applied to the second thermistor 1106 in FIG. 11.

A first current 1208 measured in the first thermistor 1202 in FIG. 12 corresponds to the first current 1114 measured in the first thermistor 1104 in FIG. 11. Given the reference voltage 1200, this current 1208 is a measurement of resistance across the first thermistor 1202. This resistance measurement 1208, given the thermistor's properties are known, is also a measurement of the thermistor's temperature. In some embodiments of the invention where the control logic is digital, this first resistance measurement 1208, properly scaled, is fed into a first analog-to-digital converter (ADC) 1210 for conversion into a digital representation of a first measured resistance 1212 for use by a control logic 1214. In embodiments of the invention where the control logic 1214 is analog, the current 1208 itself can be used to represent the first measured resistance 1212.

A second current 1216 measured in a second thermistor 1206 in FIG. 12 corresponds to the second current 1118 measured in the second thermistor 1106 in FIG. 11. Given a reference voltage 1204, this current 1216 is a measurement of resistance across the second thermistor 1206. This resistance measurement 1216, given the thermistor's properties are known, is also a measurement of the thermistor's temperature. In some embodiments of the invention where the control logic is digital, this second resistance measurement 1216, properly scaled, is fed into a second analog-to-digital converter (ADC) 1218 for conversion into a digital representation of a second measured resistance 1220 for use by the control logic 1214.

The first measured resistance 1212, properly scaled, is subtracted from the second measured resistance 1220, also properly scaled, to form a measured resistance delta 1222, which appears as 1132 in FIG. 11. This measured resistance delta 1222 is then compared to a previously established set point 1224 (represented by 1128 in FIG. 11) to form a control signal 1226 sent to a position controller 1228. This control signal 1226 corresponds to the control signal 1114 in FIG. 11 that is sent to the airflow damper actuator 1110 to command the position of the airflow damper 1108. The position controller 1228 in FIG. 12 corresponds to the airflow damper actuator 1126 in FIG. 11.

Note that in the case of digital control logic 1214, any measured, calculated, or produced value or measurement may be stored in digital memory 1130, specifically, but not limited to, the calculated resistance or temperature delta, or Delta, 1222 and the resistance or temperature delta set point, or Set Point, 1224. The measured resistance or temperature delta 1222 could be either continuously updated or updated at regular intervals. The resistance or temperature delta set point 1224 could be updated either manually, semi-automatically, or automatically to allow the air duct to settle on a different volume of air flow.

If the control logic 1214 consists of a microprocessor or microcontroller based system capable of supporting a network stack, it may interface with a network or wireless transceiver 1230. Such a transceiver 1230 would allow the control logic to be remotely configured or reconfigured, including but not limited to setting the first and second reference voltages 1200 and 1204, setting scaling factors and limits for incoming resistance measurements 1212 and 1220, setting a scaling factor and limits for the resistance delta 1222, setting a set point 1224, and setting a scaling factor and limits for the control signal 1226.

Referring to the figures and specifically to FIG. 13, FIG. 13 describes a flowchart for tuning the control system of an embodiment of the invention where reference currents are used to measure varying voltages. To begin the process, step 1, a specified flow value of volumetric airflow is established 1300. This volumetric airflow is the same flow represented in FIG. 11 as volumetric airflow 1108 through air duct 1100. In step two, 1302 of the process of FIG. 13, reference voltages are set for the first and second thermistors. In FIG. 11, these are represented by 1110 and 1116. In FIG. 12, these are represented by 1200 and 1204. In step 3, 1304, a resulting candidate set point is measured. In step 4, 1306, provided appropriate voltages, limits, and scaling factors have been successfully applied to yield an effective control signal, the process can proceed to step 5, 1308. If an effective control signal has not been produced, the process proceeds back to step 1, 1300, where all voltages, factors, and limits may be reexamined and adjusted. Finally, in step 6, 1308, a set point for the control logic is established and applied. Note that the whole or any portion of the process described by FIG. 13 can be implemented manually, semi-automatically with computer assistance, or in a fully automatic fashion.

FIG. 14 illustrates a microprocessor-based embodiment of the control logic of the invention. Here, a microprocessor 1400 generally executes a firmware program 1402 stored in a persistent flash memory 1404. In some instances, such as during a firmware update, the processor may also execute instructions temporarily stored in a RAM 1406. The flash memory 1404 and the RAM 1406 are always attached to the microprocessor 1400 via a memory bus 1408 or busses.

The microprocessor may have a separate I/O bus 1410, or all components may be memory-mapped. Attached to this I/O bus 1410 are peripherals to the core microprocessor system consisting of microprocessor 1400, flash memory 1404, and RAM 1406. The processor 1400 may read the current measurement in the first thermistor, properly scaled, using ADC one, 1412. The method of measuring the current may consist of measuring the voltage across a low resistance and thermally stable precision resistor in series with the first thermistor. The processor 1400 may read the current measured through the second thermistor, properly scaled, using ADC two, 1414. The method of measuring the current may consist of measuring the voltage across a low resistance and thermally stable precision resistor in series with the second thermistor. Finally, the processor 1400 may output the position command by manipulating the position output 1416.

Referring to the figures and most specifically to FIG. 15, FIG. 15 is a flowchart of the firmware program 1402 executed by the microprocessor-based embodiment of the control logic of the invention illustrated by FIG. 14. After reset, the program reads its persistent settings and initializes its peripherals 1500. It then enters the main event loop, starting with step two, 1502. In step two 1502, the program latches both analog to digital converters (ADCs) 1412 & 1414. These values are then read into RAM 1406. In step three 1504, a new position is calculated. First, the inputs from the ADCs are subtracted to form the Delta. Then, the Delta is subtracted from the Set Point and properly scaled to form the new position. In step four 1506, this new position command is output. Then the process begins again beginning with step two, 1502. In exceptional cases, for example, an emergency stop button is pressed, step five 1508 is executed, whereby the program terminates after the system is placed in a safe state.

Referring to the figures and most specifically to FIG. 16, also a preferred embodiment of the invention are several instances of a preferred embodiment such as System One shown in FIG. 11. Several instances 1600, with four such instances shown in the illustration, are connected via a network connection 1602 with a central server 1604. The central server 1604 executes a software program that coordinates the activity among these instances to create air flow systems of arbitrary complexity.

In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

While selected embodiments have been chosen to illustrate the invented system, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment, it is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims

1. A method comprising; a. positioning a first thermistor and a second thermistor within a same air duct, whereby the first thermistor and the second thermistor are exposed to a same volumetric air flow;b. establishing the volumetric airflow through the air duct at a specified flow value;c. selecting a desired temperature delta to be maintained between the first thermistor and the second thermistor, the desired temperature delta correlated to a resistance delta to be exhibited between a first thermistor resistance and a second thermistor resistance;d. imposing a first reference current through the first thermistor, whereby the measured first thermistor resistance value is substantially determined by a contemporaneous aggregate air temperature of the air flow;e. imposing a variable second reference current through the second thermistor, whereby a variably imposed resistance level of the second thermistor is variably and substantially determined by a magnitude of heat received by the second thermistor from the second reference current;f. positioning a servo-motor controlled air flow damper within the air duct; andg. directing the servo-motor to adjust the air flow damper to drive the second thermistor to a resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
2. The method of claim 1, wherein a valuable current provided to the second thermistor is pulse width modulated.
3. The method of claim 1, wherein the air duct provides air flow selected from the air flow group consisting of supply air flow, return air flow, and exhaust air flow.
4. The method of claim 1, wherein the servo-motor controlled air flow damper comprises a plurality of vents coupled with a rack and pinion motivator.
5. The method of claim 1, wherein the servo-motor controlled air flow damper comprises a linear servo motor controlled aperture.
6. The method of claim 1, wherein the servo-motor controlled air flow damper comprises a continuous rotation motor controlled aperture.
7. The method of claim 1, further comprising storing the resistance delta in a digital memory.
8. The method of claim 1, further comprising updating the resistance delta to a different value.
9. A device positioned relative to an air duct, the air duct channeling a volumetric airflow, the system comprising; a controller communicatively coupled with a first thermistor and a second thermistor positioned within the air duct, whereby the first thermistor and the second thermistor are exposed to a same volumetric air flow and the controller monitors a first thermistor resistance value of the first thermistor and a contemporaneous second resistance value of the second thermistor;a memory element communicatively coupled with the controller, the memory element storing a resistance delta value;a means to impose a first reference current through the first thermistor, whereby the first thermistor resistance value is substantially determined by a contemporaneous aggregate air temperature of the air flow;a means to impose a variable second reference current through the second thermistor, whereby a variably imposed resistance level of the second thermistor is variably and substantially determined by a combination of a magnitude of heat received by the second thermistor from the second reference current and heat transferred from the second thermistor to the air flow;a servo-meter coupled with a servo-motor controlled air flow damper;the servo-motor controlled air flow damper comprising an air flow damper controlled by the server motor, and the servo-motor managed by power adjustably controlled by the controller, and the air flow damper positioned within the air duct; andthe controller adapted to receive instantaneous resistance measurements from both the first thermistor and the second thermistor, and thereupon to direct the servo-motor to adjust the air flow damper to modify volumetric airflow of the air duct and thereby cause the second thermistor to achieve a resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
10. The device of claim 9, wherein the means to impose the second reference current through the second thermistor is a pulse width modulated current source.
11. The device of claim 9, wherein the controller is coupled with the means to impose the second reference current through the second thermistor, and the control logic directs a second reference current delivered to the second thermistor.
12. The device of claim 9, further comprising a communications channel coupled with the controller, and the controller adapted to receive the resistance delta value and store the resistance delta value in the memory element.
13. The device of claim 9, wherein the memory element is comprised within the controller 1.
14. The device of claim 9, wherein the controller comprises programmable logic.
15. The device of claim 9, wherein the controller contains programmed logic that enables the controller to direct the servo-motor to adjust the air flow damper to drive the second thermistor to a resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
16. The device of claim 9, further comprising a memory module bi-directionally coupled with the controller, and the memory module contains software encoded instructions that operatively directs the controller to perform the following: a. receive contemporaneous resistance measurements from both the first thermistor and the second thermistor, andb. thereupon direct the servo-motor to adjust the air flow damper to modify volumetric airflow of the air duct and thereby cause the second thermistor to achieve the resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
17. The device of claim 16, wherein the means to impose the second reference current through the second thermistor is a pulse width modulated current source.
18. The device of claim 16, further comprising a communications channel coupled with the controller logic, and the controller logic adapted to receive an updated resistance delta value and store updated resistance delta value in the memory element.
19. The device of claim 18, wherein the communications channel comprises a wireless communications receiver, and the updated resistance delta value is received via the wireless communications receiver.
20. A system comprising: at least two devices of claim 9, and the controller logic of each device comprising a bi-directional wireless communications transceiver; anda remote server bi-directionally communicatively coupled with the at least two devices and adapted to exchange information with the at least two devices.
21. A method comprising; a. positioning a first thermistor and a second thermistor within a same air duct, whereby the first thermistor and the second thermistor are exposed to a same volumetric air flow;b. establishing the volumetric airflow through the air duct at a specified flow value;c. selecting a desired temperature delta to be maintained between the first thermistor and the second thermistor, the desired temperature delta correlated to a resistance delta to be exhibited between the first thermistor resistance and the second thermistor resistance;d. imposing a first reference voltage across the first thermistor, whereby the measured first thermistor resistance value is substantially determined by a contemporaneous aggregate air temperature of the air flow;e. imposing a variable second reference voltage across the second thermistor, whereby a variably imposed resistance level of the second thermistor is variably and substantially determined by a magnitude of heat received by the second thermistor from the second reference voltage;f. positioning a servo-motor controlled air flow damper within the air duct; andg. directing the servo-motor to adjust the air flow damper to drive the second thermistor to a resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
22. The method of claim 21, wherein the air duct provides air flow selected from the air flow group consisting of supply air flow, return air flow, and exhaust air flow.
23. The method of claim 21, wherein the servo-motor controlled air flow damper comprises a plurality of vents coupled with a rack and pinion motivator.
24. The method of claim 21, wherein the servo-motor controlled air flow damper comprises a linear servo motor controlled aperture
25. The method of claim 21, wherein the servo-motor controlled air flow damper comprises a continuous rotation motor controlled aperture.
26. The method of claim 21, further comprising storing the resistance delta in a digital memory.
27. The method of claim 21, further comprising updating the resistance delta to a different value.
28. A device positioned relative to an air duct, the air duct channeling a volumetric airflow, the system comprising; a controller logic communicatively coupled with a first thermistor and a second thermistor positioned within the air duct, whereby the first thermistor and the second thermistor are exposed to a same volumetric air flow and the controller logic monitors a first thermistor resistance value of the first thermistor and a contemporaneous second resistance value resistance value of the second thermistor;a memory element communicatively coupled with the controller logic, the memory element storing a resistance delta value;
29. The device of claim 28, wherein control logic is coupled with the means to impose the second reference voltage across the second thermistor, and the control logic directs a second reference voltage level delivered to the second thermistor.
30. The device of claim 28, further comprising a communications channel coupled with the controller logic, and the controller logic adapted to receive the resistance delta value and store the resistance delta value in the memory element.
31. The device of claim 28, wherein the memory element is comprised within the controller logic.
32. The device of claim 28, wherein the controller logic comprises programmable logic.
33. The device of claim 28, wherein the controller logic contains programmed logic that enables the controller logic to direct the servo-motor to adjust the air flow damper to drive the second thermistor to a resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
34. The device of claim 28, further comprising a memory module bi-directionally coupled with the controller logic, and the memory module contains software encoded instructions that operatively directs the controller to perform the following: a. receive contemporaneous resistance measurements from both the first thermistor and the second thermistor, andb. thereupon direct the servo-motor to adjust the air flow damper to modify volumetric airflow of the air duct and thereby cause the second thermistor to achieve the resistance value equal to the sum of the measured first thermistor resistance value and the resistance delta and within a pre-specified resistance value tolerance range, whereby the volumetric airflow of the air duct is maintained at the specified flow value within a pre-specified air flow variance tolerance range.
35. The device of claim 34, further comprising a communications channel coupled with the controller logic, and the controller logic adapted to receive an updated resistance delta value and store updated resistance delta value in the memory element.
36. The device of claim 35, wherein the communications channel comprises a wireless communications receiver, and the updated resistance delta value is received via the wireless communications receiver.
37. A system comprising: at least two devices of claim 28, and the controller logic of each device comprising a bi-directional wireless communications transceiver; anda remote server bi-directionally communicatively coupled with the at least two devices and adapted to exchange information with the at least two devices.

DISTRIBUTED AIR FLOW METHOD AND SYSTEM

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CPC

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Claims