Backdraft Damper with Electromagnet for Terminal Unit

This application is a non-provisional of and claims the benefit of U.S. Provisional Patent Application No. 63/645,687, filed on May 10, 2024, the entire contents of which are incorporated herein by reference.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

A heating, ventilation, and/or air conditioning (HVAC) system is often utilized to regulate environmental conditions, such as temperature and/or humidity, within a building or other conditioned space. For example, an HVAC system may include equipment, such as one or more heat exchangers deployed in an HVAC unit, which operates to produce a flow of supply air. To direct the supply air to a conditioned space, the HVAC system may include ductwork configured to direct the supply air from the HVAC unit to the conditioned space. In some applications, the HVAC system may include a terminal unit connected to an end of the ductwork. The terminal unit may discharge the supply air toward the conditioned space. Additionally, the terminal unit may be configured to receive a flow of plenum air, such as air within a plenum or space above a ceiling of the conditioned space. The terminal unit may also be desired to direct the plenum air flow to the conditioned space in order to recirculate air within the conditioned space. Unfortunately, existing terminal units are susceptible to various inefficiencies and operational inconveniences. For example, existing terminal units are susceptible to generation of undesired noise in various operating conditions.

A summary of certain examples disclosed herein is set forth below. It should be noted that these aspects are presented merely to provide the reader with a brief summary of these certain examples and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

In an example, a terminal unit for a heating, ventilation, and/or air conditioning (HVAC) system includes a housing with a first chamber configured to receive a first air flow and a second chamber configured to receive a second air flow. The terminal unit also comprises an internal wall disposed within the housing and extending between the first chamber and the second chamber, where the internal wall comprises an opening. Further, the terminal unit includes a damper collar coupled to the internal wall and disposed about the opening, a damper door rotatably coupled to the damper collar, where the damper door is configured to abut the damper collar and occlude the opening in a closed position. Finally, the terminal unit includes an electromagnet coupled to the damper collar, where the electromagnet is configured to generate a magnetic field to draw the damper door toward the closed position.

In some aspects, the techniques described herein relate to a terminal unit for a heating, ventilation, and/or air conditioning (HVAC) system, including: a housing including a first chamber configured to receive a first air flow and a second chamber configured to receive a second air flow; an internal wall disposed within the housing and extending between the first chamber and the second chamber, wherein the internal wall includes an opening formed therein; a damper door rotatable relative to the opening, wherein the damper door is configured to occlude the opening in a closed position; and an electromagnet that is configured to be selectively activated to generate a magnetic field to retain the damper door in the closed position and thereby prevent the first air flow from flowing through the opening; wherein when the electromagnet is deactivated, the magnetic field is not generated such that the second air flow may be forced from the second chamber to the first chamber through the opening.

In some aspects, the techniques described herein relate to a terminal unit for a heating, ventilation, and/or air conditioning (HVAC) system, including: a housing including a first chamber configured to receive a first air flow and a second chamber configured to receive a second air flow; an internal wall disposed within the housing and extending between the first chamber and the second chamber, wherein the internal wall includes an opening formed therein; a damper door rotatably coupled to the internal wall, wherein the damper door is configured to occlude the opening in a closed position; and an electromagnet coupled to the internal wall, wherein the electromagnet is configured to generate a magnetic field to retain the damper door toward the closed position.

In some aspects, the techniques described herein relate to a terminal unit for a heating, ventilation, and/or air conditioning (HVAC) system, including: a housing including a first chamber configured to receive a first air flow and a second chamber configured to receive a second air flow; an internal wall disposed within the housing and extending between the first chamber and the second chamber, wherein the internal wall includes an opening formed therein; a damper collar coupled to the internal wall and disposed about the opening; a damper door rotatably coupled to the damper collar, wherein the damper door is configured to abut the damper collar and occlude the opening in a closed position; and an electromagnet coupled to the damper collar, wherein the electromagnet is configured to generate a magnetic field to draw the damper door toward the closed position.

One or more specific examples of the present disclosure will be described below. These described examples are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these examples, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but may nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various examples of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one example” or “an example” of the present disclosure are not intended to be interpreted as excluding the existence of additional examples that also incorporate the recited features.

As used herein, the terms “approximately,” “generally,” and “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to mean that the property value may be within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to mean that the given feature is within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Further, it should be understood that mathematical terms, such as “planar,” “slope,” “perpendicular,” “parallel,” and so forth are intended to encompass features of surfaces or elements as understood to one of ordinary skill in the relevant art, and should not be rigidly interpreted as might be understood in the mathematical arts. For example, a “planar” surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within related tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having a “slope” is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., incline) with respect to a point of reference using techniques and tools available to one of ordinary skill in the art.

As will be discussed in further detail below, a heating, ventilation, and/or air conditioning (HVAC) system may include a terminal unit for delivering air to a conditioned space of a structure. In general, the terminal unit may be located near or within the conditioned space, and the terminal unit may be configured to receive one or more air flows for supply to the conditioned space. For example, the terminal unit may receive a first air flow (e.g., a primary air flow, a conditioned air flow) from an HVAC unit (e.g., air handler) via ductwork extending from the HVAC unit to the terminal unit. To this end, the terminal unit may include a first air inlet configured to receive the first air flow from the ductwork. The terminal unit may also be configured to receive a second air flow (e.g., a plenum air flow, a return air flow) via a plenum air inlet of the terminal unit. For example, the second air flow may be received from a plenum space, such as a space above a ceiling of the conditioned space, in which the terminal unit is disposed.

In some examples, the terminal unit may include a first chamber configured to receive the first air flow and to discharge the first air flow from the terminal unit. The terminal unit may also include a second chamber configured to receive the second air flow. In some examples, the terminal unit may be configured to direct the second air flow from the second chamber and into the first chamber to enable discharge of the second air flow toward the conditioned space from the first chamber. In some examples, the terminal unit may be configured to receive the first air flow, receive the second air flow, and direct the second air flow from the second chamber and into the first air flow within the first chamber to generate a mixed air flow that is discharged to the conditioned space.

The first chamber and the second chamber of the terminal unit may be generally divided by an internal wall disposed within a housing of the terminal unit. To enable flow of the second air flow from the second chamber into the first chamber, the terminal unit may include a damper (e.g., backdraft damper) coupled to the internal wall. That is, the internal wall may include an opening to fluidly couple the first chamber and the second chamber, and the damper may overlap with the opening to enable control of the second air flow from the second chamber into the first chamber. In some examples, the damper may also enable control of the first air flow from the first chamber into the second chamber. In particular, the damper may be configured to block flow of the first air flow from the first chamber into the second chamber.

In some examples, the terminal unit may include a blower configured to drive flow of air through the terminal unit. For example, the blower may be disposed within the second chamber and may be configured to force the second air flow from the second chamber and into the first chamber via the opening of the internal wall. As the blower forces the second air flow toward and through the opening, the second air flow may impinge against the damper and force the damper to transition toward an open position. In some circumstances, the blower may not be operated to force the second air flow through the terminal unit. In such instances, the damper may transition toward a closed position to at least partially block the opening in the internal wall. In this way, the damper may at least partially block flow of the first air flow from the first chamber and into the second chamber via the opening.

Unfortunately, existing dampers (e.g., backdraft dampers) in terminal units may rely upon a force of the first air flow directed through the first chamber to maintain the damper in a closed position to block flow of the first air flow into the second chamber. For example, existing backdraft dampers may include one or more protrusions (e.g., flanges) that extend outwardly from of a panel (e.g., body, door) of the damper and into a flow path of the first air flow. In some existing designs, a terminal unit may include a baffle configured to direct a portion of the first air flow toward the damper to bias the damper toward a closed position against the internal wall. In this way, the protrusions and/or baffle may harness the force of the first air flow to bias the backdraft damper toward the internal wall and in a closed position. However, traditional backdraft dampers including such features may generate acoustic energy (e.g., noise) as the first air flow contacts the protrusions, and the acoustic energy may manifest as undesirable noise and/or vibrations that are emitted from the terminal unit. Further, the protrusions of traditional backdraft dampers may create undesirable air flow resistance (e.g., a pressure drop) in the first air flow, thereby adversely affecting the discharge of air from the terminal unit and into the conditioned space. In some traditional backdraft dampers for terminal units, the backdraft damper may simply rely on the force of gravity to rest in a vertical position, whereby the backdraft damper may generally occlude the opening in the internal wall. However, as a speed of the first air flow through the first chamber increases, a pressure within the first chamber may decrease (e.g., relative to a pressure within the second chamber), thereby creating a pressure differential between the first chamber and the second chamber. In such instances, the pressure differential may urge traditional backdraft dampers toward an open position that enables undesirable flow (e.g., leakage) of the first air flow into the second chamber.

It is now recognized that improved backdraft dampers and related features may enable improved flow of air flows through a terminal unit. Accordingly, present examples are directed to backdraft damper assemblies and control systems thereof that are configured to reduce undesired and/or unintended flow of air within and/or through the terminal unit. For example, the disclosed techniques enable a reduction in flow of air from the first chamber (e.g., primary air chamber) into the second chamber (e.g., plenum air chamber), such as during instances in which a blower of the terminal unit is not operating to force the second air flow (e.g., plenum air flow) into the first chamber. Indeed, present examples enable improper operation of backdraft dampers to control flow of air through a terminal unit without use of protrusions, baffles, and/or other features that may otherwise impede flow of the first air flow through the terminal unit and/or generate undesirable acoustic energy, noise, vibrations, and so forth. In some examples of the present disclosure, the backdraft damper assembly may be incorporated with an electromagnet system (e.g., control system) configured to enable securement of the backdraft damper in a closed position during non-operation of a blower of the terminal unit. As described in further detail below, the backdraft damper assembly may include a damper collar (e.g., damper frame) and a damper door. The damper collar may be coupled to an internal wall of the terminal unit and may generally extend about (e.g., surround) an opening formed in the internal wall. The damper door may be mechanically attached to an upper portion (e.g., side, edge, frame) of the damper collar, such as via a hinge, and the damper door may be configured to rotate or pivot (e.g., via the hinge) relative to the damper collar to enable and/or block air flow through the opening of the internal wall. The damper collar may also include an electromagnet coupled thereto. In accordance with present techniques, the electromagnet may be selectively energized to selectively retain the damper door against the damper collar and thereby more reliably and securely maintain the damper door in a closed position when desired. In this way, the disclosed examples may reduce undesired flow of air within the terminal unit (e.g., from the first chamber to the second chamber), while also avoiding generation of acoustic energy and undesirable air flow restrictions within the terminal unit.

Turning now to the drawings,illustrates an example of a heating, ventilation, and/or air conditioning (HVAC) system for environmental management that may employ one or more HVAC units. As used herein, an HVAC system includes any number of components configured to enable regulation of parameters related to climate characteristics, such as temperature, humidity, air flow, pressure, air quality, and so forth. For example, an “HVAC system” as used herein is defined as conventionally understood and as further described herein. Components or parts of an “HVAC system” may include, but are not limited to, all, some of, or individual parts such as a heat exchanger, a heater, an air flow control device, such as a fan, a sensor configured to detect a climate characteristic or operating parameter, a filter, a control device configured to regulate operation of an HVAC system component, a component configured to enable regulation of climate characteristics, or a combination thereof. An “HVAC system” is a system configured to provide such functions as heating, cooling, ventilation, dehumidification, pressurization, refrigeration, filtration, or any combination thereof. The examples described herein may be utilized in a variety of applications to control climate characteristics, such as residential, commercial, industrial, transportation, or other applications where climate control is desired.

In the illustrated example, a buildingis air conditioned by a system that includes an HVAC unit. The buildingmay be a commercial structure or a residential structure. As shown, the HVAC unitis disposed on the roof of the building. However, the HVAC unitmay be located in other equipment rooms or areas adjacent the building. The HVAC unitmay be a single packaged unit containing other equipment, such as a blower, heat exchangers, integrated air handler, and/or auxiliary heating unit. In other examples, the HVAC unitmay be part of a split HVAC system, which may include an outdoor HVAC unit and an indoor HVAC unit.

The HVAC unitmay be an air-cooled device that implements a refrigeration cycle to provide conditioned air to the building. Specifically, the HVAC unitmay include one or more heat exchangers across which an air flow is passed to condition the air flow before the air flow (e.g., primary air flow) is supplied to the building. In the illustrated example, the HVAC unitis a rooftop unit (RTU) that conditions a supply air stream, such as environmental air and/or a return air flow drawn from the building. After the HVAC unitconditions the air flow, the air flow, also referred to herein as a primary air flow, is supplied to the buildingvia ductworkextending throughout the buildingfrom the HVAC unit. For example, the ductworkmay extend to various individual floors or other sections of the building. In certain examples, the HVAC unitmay be a heat pump that provides both heating and cooling to the building with one refrigeration circuit configured to operate in different modes. In other examples, the HVAC unitmay include one or more refrigeration circuits for cooling an air flow and a furnace for heating the air flow. The primary air flow supplied to the buildingby the HVAC unitmay include environmental air, such as air from outside the building, and/or recirculated air from within the building, which may or may not be actively and/or passively heated or cooled by the HVAC unit. For example, the HVAC unitmay operate in a recirculating or economizer mode, such that the supply air flow, and thus the primary air flow, is not actively heated or cooled in some operating modes.

A control device, one type of which may be a thermostat, may be used to designate a desired temperature of a conditioned spacewithin the building. The control devicealso may be used to control the flow of air, such as volume, through the ductworkto different areas within the conditioned space. For example, the control devicemay be used to regulate operation of one or more components of the HVAC unitor other components, such as dampers, fans, and/or terminal unitswithin the buildingthat may control the flow of air through and/or from the ductwork. In some examples, other devices may be included in the system, such as pressure and/or temperature transducers or switches that sense the temperatures and pressures of the conditioned air, return air, and so forth. Moreover, the control devicemay include computer systems that are integrated with or separate from other building control or monitoring systems, including systems that are remote from the building.

As mentioned above, an HVAC system may include one or more terminal unitsfluidly coupled to the ductworkof the HVAC system. The terminal unitsmay each be configured to receive a first air flow, such as the primary air flow discharged by the HVAC unit, and may direct the first air flow into the conditioned space. In some examples, the terminal unitsmay also be configured to receive a second air flow, such as a plenum air flow or return air flow. To this end, the terminal unitsmay be disposed within and/or adjacent a plenum spacewithin the building. In some examples, the plenum spacemay facilitate transfer of return air back to the HVAC unit. For example, the plenum spacemay be above a dropped ceilingthat separates the plenum spacefrom the conditioned space. Moreover, in some examples, the terminal unitmay be implemented in the buildingwithout the dropped ceiling, and the terminal unitsmay be configured to receive a plenum air flow or other air flow from a portion of air near a ceiling or another area of the conditioned space.

is a schematic diagram of an example of a portionof the building, illustrating an example of the terminal unitimplemented within the building. As discussed above, the terminal unitmay receive a first air flow(e.g., a primary air flow), such as via the ductworkextending from the HVAC unit. Accordingly, the first air flowmay be a conditioned air flow (e.g., a heated air flow, a cooled air flow, a dehumidified air flow) that is produced by the HVAC unitor other HVAC system. The terminal unitmay also be configured to receive a second air flow, such as a plenum air flow from the plenum spacewithin the building. In the illustrated example, the terminal unitincludes a housingdefining a first air inletconfigured to receive the first air flowand a second air inletconfigured to receive the second air flow. The terminal unitmay be configured to mix the first air flowand the second air flowwithin the housingto generate a mixed air flow(e.g., discharge air flow, supply air flow) that is then supplied to the conditioned spacevia an air outletof the terminal unit(e.g., the housing). In some implementations, the plenum spacemay receive a return air flow, for example, drawn into the plenum spacevia a vent, which may be formed in the dropped ceiling. In some examples, a portion of the return air flowmay be directed back to the HVAC unit(e.g., via the ductwork) for conditioning. Additionally or alternatively, a portion of the return air flowmay be drawn into the housingof the terminal unit, via the second air inlet, as the second air flow. The mixed air flowmay include a portion of the first air flowand/or a portion of the second air flowreceived by the terminal unit. That is, during some operations of the terminal unit, the mixed air flowmay include both the first air flowand the second air flow, and in other operations the mixed air flowmay include one of the first air flowor the second air flowwithout the other of the first air flowor the second air flow. To this end, the terminal unitmay include one or more valves, dampers, and/or other flow control device configured to regulate flow of air (e.g., first air flow, the second air flow) into and/or through the housing. For example, if the first air inletof the terminal unitor the second air inletof the terminal unitis closed (e.g., via a damper or valve), the mixed air flowmay include air from a single source. In other words, if the first air inletis closed, the terminal unitmay receive and supply the second air flowalone to the conditioned space, and if the second air inletis closed, the terminal unitmay receive and supply the first air flowalone to the conditioned space.

As mentioned above, present examples are directed to systems and methods configured to enable improved control of air flow through the terminal unit. In particular, examples of the terminal unitincorporating the present techniques may include a damper assembly(e.g., backdraft damper assembly) configured to block undesired flow of air through the terminal unit. For example, the damper assemblymay be configured to block a flow (e.g., a backdraft) of the first air flowthrough the terminal unit, such as toward the second air inlet. In some examples, the terminal unitmay also include a control systemconfigured to adjust, control, and/other enable desired operation of the damper assembly, such as to reduce noise and/or vibrations generated during operation of the terminal unit. The present techniques may also enable more efficient operation of the terminal unit. Details of the damper assemblyand the control systemare described further below.

is a perspective view of a portion of an example of the terminal unitincluding the damper assemblyand the control system. As mentioned above, the terminal unitincludes the housinghaving the first air inletconfigured to receive the first air flow, the second air inletconfigured to receive the second air flow, and the air outletconfigured to discharge the first air flowand/or the second air flowreceived by the terminal unit. The housinggenerally defines a first chamber(e.g., first section, first volume) configured to receive the first air flowvia the first air inletand a second chamber(e.g., second section, second volume) configured to receive the second air flowvia the second air inlet. In the illustrated example, the first chambergenerally extends from the first air inletto the air outletdefined by the housing. In some examples, the terminal unitmay include an inlet valveconfigured to enable flow of the first air flowfrom the HVAC unitto the terminal unit. The second air inletmay be an opening formed in the housingand may be exposed to the plenum spacewithin the buildingto enable flow of the second air flowfrom the plenum spaceinto the terminal unit(e.g., the second chamber).

The first chamberand the second chamberwithin the housingare generally divided (e.g., separated) by an internal walldisposed within the housing. As described in further detail below with reference to, the internal wallincludes an opening configured to enable fluid coupling of the first chamberand the second chamber. In accordance with present techniques, the terminal unitincludes the damper assembly(e.g., backdraft damper assembly) configured to enable improved control of air flow through the opening and between the first chamberand the second chamber. The damper assemblyis configured to couple to the internal wall, such that the damper assemblygenerally overlaps with the opening formed in the internal wall. In the illustrated example, the damper assemblyis coupled to the internal walland is disposed within the first chamber.

As described in further detail below, the damper assemblymay include a damper collar(e.g., damper frame, damper mount) that is attached (e.g., fixed) to the internal walland generally surrounds the opening formed in the internal wall. The damper collarmay include a mounting flangeconfigured to mount the damper collarto the internal wallof the terminal unit. The mounting flangemay include mounting holes configured to receive fasteners, screws, or any other suitable attachment device to secure the damper collarto the internal wall. Further, in other examples, the damper collarmay be affixed to the internal wallof the terminal unitvia welding, adhesives, or any other suitable attachment mechanism. The damper assemblymay also include a damper door(e.g., panel, cover) adjustably coupled to the damper collar. For example, the damper doormay be coupled to damper collarvia a hinge, a pivot joint, or other suitable connection configured to enable relative movement between the damper collarand the damper door. In the illustrated example, the damper dooris shown in a closed position, whereby the damper dooroverlaps with the opening formed in the internal wallto block air flow between the first chamberand the second chamber.

In addition to the damper assembly, the terminal unitalso includes the control systemconfigured to enable improved control of air flow through the opening of the internal walland between the first chamberand the second chamber. The damper assemblymay include an electromagnet, and the control systemmay be configured to selectively activate (e.g., energize) and deactivate (e.g., de-energize) the electromagnet to control operation of the damper assemblyand regulate flow of air between the first chamberand the second chamber. For example, in some instances, the control systemmay be configured to energize the electromagnet and cause the electromagnet to retain the damper dooragainst the damper collar(e.g., via generating of a magnetic field that attracts the damper door) to block flow of air between the first chamberand the second chamber. In other instances, the control systemmay be configured to de-energize the electromagnet and enable the damper doorto move (e.g., rotate, pivot) relative to the damper collarand thereby enable flow of air between the first chamberand the second chambervia the opening in the internal wall.

As will be appreciated, it may be desirable to enable flow of the second air flow(e.g., received via the second air inlet) from the second chamberto the first chamberto enable discharge of the second air flowfrom the terminal unitvia the air outlet. To this end, the terminal unitmay include a blowerdisposed within the second chamber. The blowermay operate to draw the second air flowinto the second chambervia the second air inletand may force the second air flowto flow toward the opening formed in the internal wall. In this way, the second air flowmay be directed into the first chamberand may be discharged via the air outlet. In accordance with present techniques, the control systemmay be configured to control operation of the damper assemblybased on an operating state of the blower. For example, during operation of the blower, the control systemmay cause the electromagnet of the damper assemblyto be de-energized and thereby enable movement of the damper doorrelative to the damper collar. Accordingly, the second air flowdriven by the blowermay impinge against the damper doorand force the damper doorto rotate or pivot at least partially into the first chamber. In this way, the second air flowmay be directed into the first chambervia the opening formed in the internal wall. During instances in which the bloweris not operating (e.g., when the terminal unitreceives and discharges the first air flowand not the second air flow), the control systemmay cause the electromagnet of the damper assemblyto be energized and thereby cause the electromagnet to attract and retain the damper dooragainst the damper collar. In this way, the damper assemblyand/or the control systemmay maintain the damper doorin a closed position against the damper collar. Indeed, with the electromagnet energized, the damper doormay be restricted from movement (e.g., relative to the damper collar) that may otherwise be induced, such as via a pressure differential between the first chamberand the second chamber). As a result, undesired flow of the first air flowfrom the first chamberto the second chamber(e.g., backflow of the first air flow) and/or undesired flow of the second air flowinto the first chambermay be reduced, which may enable more efficient operation of the terminal unit. For example, a fan or blower of an HVAC unit (e.g., HVAC unit) associated with the terminal unitmay be operated with reduced energy usage due to more efficient flow of the first air flowthrough the terminal unit.

In some examples, the control systemmay be configured to control and/or adjust other operations of the terminal unit. For example, the control systemmay be configured to control a speed of the blowerto regulate a flow rate of the second air flowthrough the terminal unit, a position of the inlet valveto regulate a flow rate of the first air flowthrough the terminal unit, and so forth. The control systemmay be configured to control operation of one or more components of the terminal unitbased on data, feedback, and/or control instructions received from a sensor and/or other component of an HVAC system incorporating the terminal unit. For example, the control systemmay control operation of the terminal unitbased on a temperature and/or a setpoint temperature of the conditioned spaceserviced by the terminal unit. In some examples, the terminal unitmay include a heat exchanger (e.g., heater, cooling coil, etc.) disposed within the housing(e.g., within the first chamber) to condition the first air flow, the second air flow, or both prior to discharge via the air outlet.

The control systemmay further include one or more sensors configured to detect one or more operating parameters of the terminal unit, the conditioned space, and/or an HVAC system incorporating the terminal unit, and the control systemmay be configured to adjust operation of the terminal unit(e.g., blower, damper assembly, inlet valve, etc.) based on received data indicative of the one or more operating parameters. In some examples, the control systemmay adjust operation of one or more components of the terminal unitto approach, reach, and/or satisfy a target operating parameter, such as a target operating parameter of the first air flow, the second air flow, the mixed air flow, the conditioned space, and so forth. Such operating parameters may include, for example, volumetric flow rate, relative amounts of the first air flowand the second air flowdischarged by the terminal unit, pressure, temperature, and so forth.

is an exploded perspective view of an example of the damper assemblyand the internal wallof the terminal unit. As mentioned above, the internal wallis configured to extend between the first chamberand the second chamberwithin the housingof the terminal unit, and the internal wallincludes an opening(e.g., flow path, aperture, plenum air flow path) configured to enable flow of air between the first chamberand the second chamber. In accordance with present techniques, the terminal unitincludes the damper assemblyand the control systemto enable improved, selective control of air flow between the first chamberand the second chambervia the opening. More specifically, the damper assemblyand the control systemare configured to enable improved regulation of flow of the second air flowfrom the second chamberinto the first chamberand to more effectively block flow of the first air flowfrom the first chamberinto the second chamber(e.g., backflow or backdraft of the first air flow).

As mentioned above, the damper assemblyincludes the damper collar, which is configured to be mounted to the internal wall(e.g., via the mounting flange), such that the damper collargenerally extends about (e.g., surrounds) the opening. In particular, the damper collarmay be coupled to a first sideof the internal wallfacing the first chamberwithin the housing. The damper assemblyalso includes the damper door, which is configured to adjustably couple to the damper collar. For example, the damper doormay couple to the damper collarvia a hinge joint(e.g., a pin connection, pivot joint). The hinge jointmay be disposed at an upper or top endof the damper assembly. Thus, the damper doormay be configured to pivot, rotate, or swing further into the first chamber, such as in response to a force applied to the damper doorby the second air flow(e.g., via operation of the blower). In other examples, the damper doormay be pivotably coupled to the internal wall(e.g., instead of the damper collar), as will be discussed below relative to. The damper doormay have any suitable mass to enable a force of the second air flowproduced by the blowerto rotate or pivot at least partially away from the damper collarand bias the damper doortoward an open position, thereby enabling flow of the second air flowfrom the second chamberinto the first chambervia the opening.

In a closed position, the damper doormay abut against the damper collarand may generally block or occlude the openingto block air flow between the first chamberand the second chamber. In some examples, the damper doormay be manufactured with certain dimensions that overlap and/or are greater than corresponding dimensions of damper collar. For example, the damper doormay include a main body(e.g., main panel) and side flangesextending from the main body. In a closed position of the damper door, the side flangesmay overlap with and/or extend along lateral sides(e.g., side surfaces, lateral surfaces) of the damper collarto more fully occlude the openingand block air flow through the opening(e.g., via a space or gap between the damper doorand the damper collar. Moreover, when the damper dooris in the closed position against the damper collar, movement of the damper door, such as in a lateral direction (e.g., along an axis) may be restricted via the overlap between the side flangesand the lateral sides.

In some examples, the damper assemblymay include a gasket (e.g., seal) positioned on or against the damper collar, such as along an outlet face or surfaceof the damper collarthat generally faces the damper door. The gasket may be configured to create a seal between the damper doorand the damper collarin a closed position of the damper assembly. In this way, undesired flow of the first air flowfrom the first chamberto the second chamber, as well as undesired flow of the second air flowfrom the second chamberto the first chambermay be blocked. The gasket may have a similar geometry as the outlet faceto enable the gasket to extend along a substantially portion and/or an entirety of the outlet face. The gasket may be made of any suitable material, such as rubber, cork, silicone, a polymer, foam, and so forth.

As mentioned above, the damper assemblyalso includes an electromagnetconfigured to enable selective securement of the damper doorin a closed position (e.g., against the damper collar) to occlude and/or substantially occlude the openingand thereby block flow of air between the first chamberand the second chamber. The electromagnetmay be attached to the damper collar(e.g., one of the lateral sides) in some examples. In the manner described further below, the electromagnetmay be selectively actuated (e.g., energized, via operation of the control system) to cause the electromagnetto generate a magnetic field and draw the damper doortoward the damper collarand to retain the damper door(e.g., damper assembly) in a closed position. Indeed, the electromagnetmay retain the damper doorin a generally fixed position against the damper collarto improve blockage of air flow between the first chamberand the second chamber(e.g., backflow of the first air flowinto the second chamber).

is a perspective view schematic of an example of the damper assemblyand the control systemconfigured to regulate operation of the damper assembly, in accordance with present techniques. As discussed above, the damper assemblyincludes the electromagnet(e.g., electromagnetic coil) configured to be selectively actuated (e.g., energized) to enable retention of the damper doorin a closed position against the damper collarvia a magnetic force. The electromagnetmay be positioned in any suitable location of the damper assembly, such as coupled to the damper collaror to the damper door. For example, the electromagnetmay be coupled to one of the lateral sidesof the damper collar, as shown. In some examples, the electromagnetmay be integrated with the damper collar. Alternatively, the electromagnetmay be mechanically coupled (e.g., removably coupled) to an existing example of the damper collar. For example, the damper assembly, the electromagnet, and/or the control systemmay be incorporated with an existing example of the terminal unitas a retrofit kit. As discussed in greater detail below, the electromagnetmay be coupled to the internal wall. In some examples, the damper assemblymay include multiple electromagnets(e.g., positioned on opposite lateral sides) of the damper collar.

In the illustrated example, the damper dooralso includes a flange(e.g., damper door flange) extending (e.g., along axis) from the main bodyof the damper door. The flangemay be configured to enable improved magnetic attraction of the damper doorto the electromagnet. To this end, the flangemay be formed from any suitable material, such as a ferromagnetic material (e.g., steel, sheet metal) that may be attracted by a magnetic force. The flangemay be attached to the damper doorvia any suitable manner, such as welding, adhesive, a mechanical fastener, and so forth. In this way, the flangemay be incorporated with existing examples of the damper door. Alternatively, the flangemay be integrally formed with the damper door. In a closed position of the damper door(e.g., damper assembly), the flangemay overlap with and/or contact the electromagnet. In this way, the electromagnetand the flangemay enable improved retention of the damper assemblyin the closed position (e.g., during energization of the electromagnet). In some examples, the electromagnetmay be integrated internally within the damper collar, and the damper doormay not include the flangeto enable retention of the damper doorin the closed position via the electromagnet.

As discussed above, the control systemmay be configured to control operation of the electromagnetbased on an operational state and/or operating mode of the terminal unit. More specifically, the control systemmay control operation of the electromagnetbased on an operation of the blowerof the terminal unit. For example, during operation of the blowerto force the second air flowfrom the second chamberinto the first chamber, the control systemmay operate to deactivate (e.g., de-energize) the electromagnet. Thus, the electromagnetmay not generate a magnetic field to attract the damper doorto the closed position against the damper collar, thereby enabling the damper doorto open and enable fluid coupling of the first chamberand the second chambervia the openingof the internal wall. During instances in which the bloweris not operating, the control systemmay operate to activate (e.g., energize) the electromagnetto generate a magnetic field and attract the damper doorto the closed position against the damper collar. Thus, the openingin the internal wallmay be occluded via the damper assembly, and air flow between the first chamberand the second chambermay be blocked. In particular, a back flow of the first air flowfrom the first chamberto the second chambervia the openingmay be blocked, which may enable improved operation of the terminal unitand/or an HVAC system (e.g., HVAC unit) utilized with the terminal unit. Further, the electromagnetmay retain the damper doorin the closed position, which may reduce undesired noise and/or vibration that may otherwise be generated via incidental movement of the damper door(e.g., via a pressure differential across the first chamberand the second chamber.

As will be appreciated, the electromagnetmay include an electromagnetic coil wound around a magnetic core. The electromagnetic coil may be formed from copper or any other suitable conductive material configured to create a magnetic field. Further, the magnetic core may be formed from iron, steel or any other suitable material. The amount, size, and/or thickness of the material forming electromagnetic coil may be any suitable amount, size and/or thickness configured to create a magnetic field configured to draw and retain the damper doorin the closed position to block flow of the first air flowinto the second chamberand/or to block flow of the second air flowinto the first chamber. As an electric current is supplied through the electromagnetic coil, the flow of electric current may create a magnetic field to magnetically attract the damper door(e.g., the flange). The amount of electric current directed through the electromagnetic coil may be any amount suitable to create a magnetic force configured to draw and retain the damper doorin the closed position while also withstanding and/or resisting a force generated by the first air flowdirected through the first chamberand/or a pressure differential between the first chamberand the second chamber.

Flow of electric current to the electromagnetmay be regulated by the control system. One or more of the components of the control systemdescribed herein may be incorporated with the terminal unit, the HVAC unit, another portion of an HVAC system having the terminal unit, or any combination thereof. In the illustrated example, the control systemincludes a controller(e.g., a control system, a control panel, control circuitry). The controllermay be a component of the terminal unit. Alternatively, the controllermay be a component of another system or subsystem of the HVAC unit, the building, or other system. The controllermay be configured to control operation of one or more components of the terminal unit, such as the damper assemblyand/or the electromagnet, in accordance with the techniques discussed herein. The controllerincludes processing circuitry, such as one or more microprocessors, which may execute software for controlling the components of the terminal unit. The processing circuitrymay include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processing circuitrymay include one or more reduced instruction set (RISC) processors.

The controllermay also include a memory device(e.g., a memory) that may store information, such as instructions, control software, look up tables, configuration data, etc. The memory devicemay include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory devicemay store a variety of information and may be used for various purposes. For example, the memory devicemay store processor-executable instructions including firmware or software for the processing circuitryexecute, such as instructions for controlling components of the terminal unit. In some examples, the memory deviceincludes one or more tangible, non-transitory, machine-readable-media that may store machine-readable instructions for the processing circuitryto execute. The memory devicemay include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory devicemay store data, instructions, and any other suitable data.

The control systemalso includes an electromagnet circuit(e.g., interlock circuit) having a switched-mode power supply(e.g., switching-mode power supply, switched power supply, switcher, SMPS) and an electromagnet relay. The controllermay be configured to supply power, such as 24-volt alternating current (24 VAC), to the blower(e.g., a blower relayof the blower) and to the SMPS. The SMPSmay be configured to receive the 24 VAC and convert the 24 VAC to 24-volt direct current (24V DC). The controllermay supply power to the blower relayto cause the blowerto draw the second air flowinto the terminal unitand to force the second air flowfrom the second chamberand into the first chamberof the terminal unit. For example, the controllermay be configured to operate the blowerin response to data and/or a control instruction from another controller and/or from a thermostat, such as a call for heating. Thus, the controllermay operate the blowerto direct the second air flow, which may be warmer than the first air flow, through the terminal unitto provide the second air flowto the conditioned space.

In response to supply of power (e.g., 24 VAC) to the blower relayto power the blower, the blower relaymay provide first feedback (e.g., a first signal) to the SMPSand/or to the electromagnet relay. Based on the first feedback (e.g., first signal) from the blower relay, the electromagnet relaymay be energized. Upon such energization of the electromagnet relay, the electromagnet relaymay de-energize the electromagnet, which may suspend generation of a magnetic field by the electromagnet. As a result, the electromagnetmay not operate to draw and retain the damper dooragainst the damper collar. Thus, the damper doormay transition toward an open position, via force of the second air flowgenerated by the blower, to enable flow of the second air flowfrom the second chamberand into the first chamber.

In other instances, the controllermay determine that the blowershould not operate, and supply of power to the blowerfrom the controller(e.g., via the blower relay) may be suspended. In response to suspended supply of power to the blower relay, the blower relaymay provide second feedback (e.g., a second signal) to the electromagnet circuit. In response to the second feedback from the blower relay, the electromagnet circuitmay remain energized (e.g., via the SMPS), and the electromagnet relaymay operate to activate and/or energize the electromagnet. Thus, the electromagnetmay generate a magnetic field to draw and retain the damper dooragainst the damper collar. In accordance with present techniques, the energized electromagnet(e.g., electromagnetic coil) may cause the damper door(e.g., the flange) to magnetically attach to the damper collar, thereby retaining the damper doorin a substantially closed position against the damper collar.

The electromagnet relaymay be mechanical (e.g., with movable contacts) or with no movable contacts. In some examples, the electromagnet relaymay include a coil, configured to receive electric current and generate a magnetic field utilizing the electric current. The magnetic field may cause contacts of the electromagnet relayto move or change positions. The contacts may be normally closed (NC) or normally open (NO). When the contact state is normally closed, the electromagnet relaycontacts are closed, thereby enabling electric current to flow to an output of the electromagnet relay(e.g., to the electromagnet). When the contact state is normally open, the electromagnet relaycontacts are open, and no electrical current may flow to the output of the electromagnet relay. When a control signal (e.g. an electrical current) is applied to the electromagnet relayhaving normally open contacts, the magnetic field created by the coils may cause the contacts to move or change position to a closed configuration, thereby enabling electrical current to flow to the output of the electromagnet relay. When a control signal is applied to the electromagnet relayhaving normally closed contacts, the magnetic field created by the coils cause the contacts to move or change position to the open configuration, and no electrical current may flow to the output of the electromagnet relay. The electromagnet relayof the electromagnet circuitin the illustrated example may have a normally closed configuration. In this way, when power is supplied to the blower relayto operate the blower, and electrical current flows through the electromagnet circuit, the electromagnet relaycontacts may move or change position to an open configuration, thereby de-energizing the electromagnet. When power is not supplied to the blower relayto suspend operation of the blower, the electromagnet relaymay not be energized by the power supplied to the blower relay, and the normally closed contacts will return to the closed configuration to enable continued supply of electric current to the electromagnet.

illustrate another exemplary damper assembly′. The damper assembly′ ofsimilar to the damper assemblyof. Thus, like structure will be identified with like reference numerals and only the differences will be discussed. As shown, the damper assembly′ may have a configuration in which the damper collaris omitted. In such case, the damper doormay be fixed directly to the internal wallvia a hinge, a pivot joint, or other suitable connection configured to enable relative movement between the internal walland the damper door. In, the damper dooris shown in a closed position, whereby the damper dooroverlaps with the openingformed in the internal wallto block air flow between the first chamberand the second chamber.

The example ofalso importantly illustrates that the damper doormay have any suitable configuration. The damper dooris rotatably or pivotably along a lateral side of the openingin the internal wall, rather than along a top side of the openingin. Moreover, the damper doorincludes a flangethat projects from a surface facing the first chamber. This flangemay assist the first air flowin moving the damper doorto the close position. Moreover, the damper dooris generally planar such that a planar surface thereof engages a planar surface of the internal wall in the closed position. A gasket (not shown in) may surround all or a portion of the openingto help seal the damper doorto the internal wallin the closed position. Similarly, the gasket of the damper assembly′ may have a similar geometry as the perimeter of the opening.

Additionally, in, the electromagnetis coupled to the internal wall. In the illustrated example, the electromagnetis positioned within the second chamber, but in other examples, the electromagnetmay be positioned elsewhere or embedded into the internal wall. In the illustrated example, the electromagnetis positioned adjacent to a perimeter of the openingat a location that is overlapped by the damper door. In other examples there may be multiple electromagnetsadjacent to the perimeter of the openingat locations that are overlapped by the damper door.

The damper doormay be formed from a ferromagnetic material. Alternatively, the damper doormay include a ferromagnetic material member coupled to the planar surface of the damper doorat the location corresponding the electromagnet. In still other examples, the damper doormay include a flangeformed from ferromagnetic material, as discussed above with respect to. If included, the flangemay extend from the perimeter of the damper door and thereby give greater flexibility to the placement of the electromagnet.