SE2250907A1 - An exhaust fan and operating method thereof - Google Patents
An exhaust fan and operating method thereofInfo
- Publication number
- SE2250907A1 SE2250907A1 SE2250907A SE2250907A SE2250907A1 SE 2250907 A1 SE2250907 A1 SE 2250907A1 SE 2250907 A SE2250907 A SE 2250907A SE 2250907 A SE2250907 A SE 2250907A SE 2250907 A1 SE2250907 A1 SE 2250907A1
- Authority
- SE
- Sweden
- Prior art keywords
- flaps
- rotation direction
- impeller
- electric motor
- airflow
- Prior art date
Links
- 238000011017 operating method Methods 0.000 title abstract 2
- 238000000034 method Methods 0.000 claims description 11
- 238000010276 construction Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D25/00—Pumping installations or systems
- F04D25/02—Units comprising pumps and their driving means
- F04D25/08—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
- F04D25/12—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation the unit being adapted for mounting in apertures
- F04D25/14—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation the unit being adapted for mounting in apertures and having shutters, e.g. automatically closed when not in use
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
- F24F13/10—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
- F24F13/14—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
- A01K1/00—Housing animals; Equipment therefor
- A01K1/0047—Air-conditioning, e.g. ventilation, of animal housings
- A01K1/0052—Arrangement of fans or blowers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F7/00—Ventilation
- F24F2007/0025—Ventilation using vent ports in a wall
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
- F24F13/10—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
- F24F13/14—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre
- F24F13/1426—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre characterised by actuating means
- F24F2013/146—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre characterised by actuating means with springs
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
- F24F13/10—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
- F24F13/14—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre
- F24F13/1426—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre characterised by actuating means
- F24F2013/148—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre characterised by actuating means with magnets
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
An exhaust fan and operating method thereofAn exhaust fan comprisinga housing (30) defining a passage for an exhaust airflow (A),an impeller (20) rotatably supported within the housing,an electric motor (40) operable to drive the impeller to rotate, anda damper (60) comprising a plurality of flaps (62, 63) hinged about respective rotation axes (xl, x2), the plurality of flaps being rotatable between an open position and a closed position, respectively for opening and closing the passage, wherein the plurality of flaps are driven to open by a dynamic air pressure applied by the exhaust airflow (A) generated by the impeller (20) rotating in a first rotation direction, springs (64) being provided to bias the plurality of flaps towards the closed position,wherein the electric motor (40) is configured to drive temporarily the impeller (20), upon a stop command, in a second rotation direction opposed to the first rotation direction, in such a way to generate a temporary airflow (B) flowing in a reverse direction with respect to the exhaust airflow (A), the temporary airflow being adapted to drive the plurality of flaps into the closed position.
Description
This invention relates generally to the f1eld of axial fans, of the type provided with a damper that intercepts the passage of fluid in the duct of the fan, and used for example in the agricultural or farrning field to ventilate the interior of a building by extracting air from said interior (negative pressure) and discharging it towards the extemal environment.
Exhaust fans are known in which the damper comprises a pair of flaps which can be driven to open by a dynamic air pressure applied by an air flow generated by the fan. In general, springs are provided to take the flaps in a closed position when the fan is stopped. It has been observed that in some conditions, for instance due to air heating systems or air currents, a small overpressure (positive pressure) is generated in the interior of the building which prevents the flaps from closing completely. This is undesired, particularly in the cold season, as it allows Warm air to escape to the extemal environment or cold air to enter the interior of the building. This problem could be overcome by using springs with larger elastic constant, but this is detrimental to the complete opening of the flaps. Moreover, dedicated actuators have been proposed to control motion of the flaps, but this entails an increase in the complexity of the exhaust fan. WO 2010/ 129734 A2 discloses a fan comprising a propeller and a BLDC motor, whose control system is programmed to automatically rotate the propeller briefly in the backward direction when the fan is shut down. When the propeller is rotated in the backward direction, the movement of the propeller moves air out of the inlet of the fan which closes the damper on the outlet of the fan to prevent conditioned air in the building from exiting the building.
An object of this invention is to provide a fan capable of at least partially overcoming the aforesaid drawbacks. A further object is to improve operation of the fan with respect to the solution known from WO 2010/ 129734 A2.
These objects have been achieved by an exhaust fan comprising a housing def1ning a passage for an exhaust airflow, an impeller rotatably supported within said housing, an electric motor operable to drive said impeller to rotate, and a damper comprising a plurality of flaps hinged about respective rotation axes, said plurality of flaps being rotatable between an open position and a closed position, respectively for opening and closing the passage, Wherein said plurality of flaps are driven to open by a dynamic air pressure applied by the exhaust airfloW generated by the impeller rotating in a first rotation direction, return means being provided to bias said plurality of flaps towards the closed position, Wherein said electric motor is conf1gured to drive temporarily said impeller, upon a stop command, in a second rotation direction opposed to the first rotation direction, in such a Way to generate a temporary airfloW floWing in a reverse direction With respect to the exhaust airfloW, said temporary airfloW being adapted to drive said plurality of flaps into the closed position and Wherein the exhaust fan further comprises retaining means conf1gured to releasably retain said plurality of flaps in the closed position.
According to an embodiment, said retum means comprise springs. Springs provide a reliable Way to take the flaps back in the closed position When the exhaust airflow is stopped.
Preferably, said retaining means comprise magnetic or electromagnetic elements. In this Way, the damper is operated With simple closure means.
According to an embodiment, the electric motor comprises an asynchronous motor, and the electric motor is provided With means adapted to sWap the phases of the electric motor for temporarily driving said impeller in the second rotation direction. According to an altemative embodiment, the electric motor comprises an inverter operable to invert the rotation direction of the electric motor. These embodiments provide the electric motor With an automatic inversion capability Without complicating excessively the construction of the motor.
The above mentioned objects have also been achieved by a method for operating an exhaust fan, said exhaust fan comprising a housing def1ning a passage for an exhaust airfloW, an impeller rotatably supported Within said housing, an electric motor operable to drive said impeller to rotate, a damper comprising a plurality of flaps hinged about respective rotation axes, said plurality of flaps being rotatable between an open position and a closed position, respectively for opening and closing the passage, wherein said plurality of flaps are driven to open by a dynamic air pressure applied by the exhaust airflow generated by the impeller rotating in a first rotation direction, return means being provided to bias said plurality of flaps towards the closed position, and retaining means configured to releasably retain said plurality of flaps in the closed position, said method comprising the following steps: driving the impeller in said first rotation direction, receiving a stop command, drive temporarily said impeller in a second rotation direction opposed to the first rotation direction, in such a way to generate a temporary airflow flowing in a reverse direction with respect to the exhaust airflow, said temporary airflow driving said plurality of flaps into the closed position.
According to an embodiment, said retum means comprise springs. Springs provide a reliable way to take the flaps back in the closed position when the exhaust airflow is stopped Preferably, said retaining means comprise magnetic or electromagnetic elements. In this way, the damper is operated with simple closure means.
According to an embodiment, the electric motor comprises an asynchronous motor, and two phases of the electric motor are swapped to drive temporarily said impeller in the second rotation direction opposed to the first rotation direction. According to an altemative embodiment, an inverter is operated to invert the rotation direction of the electric motor to drive temporarily said impeller in the second rotation direction opposed to the first rotation direction. These embodiments provide the electric motor with an automatic inversion capability without complicating excessively the construction of the motor.
The above mentioned object have also been achieved by a control system, comprising: a processor; and a memory coupled to the processor to store instructions, which when executed by the processor, cause the processor to perforrn the method of the invention.
According to the invention, by simply reversing the motor quickly after the fan operation has ceased, a "negative local pressure" is created at the damper which pulls the damper fully closed. This is obtained without the need for a stronger closure spring or for mechanical or electromechanical means to provide actuation of the damper mechanism.
Preferred embodiments of the invention are defined in the dependent claims, which are to be understood as an integral part of this description.
Further features and advantages of the fan according to the invention will become clearer from the following detailed description of an embodiment of the invention, made in reference to the accompanying drawings, provided purely for illustrative and non-limiting purposes, wherein: - Figure l is a perspective view of an exhaust fan according to the invention; - Figure 2 is a vertical sectional view, passing through the rotation axis of the fan in Figure 1; - Figure 3 is a flowchart showing the operation of the exhaust fan The figures illustrate an exhaust fan, conventionally comprising an impeller 20 rotatably supported within a housing or shroud 30, and driven to rotate by an electric motor 40. The rotation axis of the impeller 20 is indicated with z in Fig. 2. The electric motor 40 comprises a control unit 41, such as a PCB board, an electrical terminal or socket, through which the electric motor 40 can be controlled by an extemal control system (not shown). The rotation direction of the impeller 20 extracting air from a building will be hereinafter designated as first rotation direction.
The exhaust fan further can comprise a frusto-conical exhaust duct 50 arranged downstream of the impeller 20, i.e., on the exhaust side thereof. In the illustrated example, the inlet of said passage faces the impeller 20, and the outlet faces the frusto-conical exhaust duct 50.
The arrows A in Fig. 2 represent the overall direction of an exhaust airflow generated by the impeller 20 rotating in the first rotation direction. The housing 30 def1nes a passage for the exhaust airflow A having an inlet and an outlet respectively upstream and downstream of the exhaust fan according to the direction of the airflow A.
The fan further comprises a damper 60, which in the example shown is arranged downstream of the impeller 20, i.e., on the exhaust side thereof. In other embodiments not shown, the damper could be arranged upstream of the impeller, i.e., on the suction side thereof. In the illustrated example, the damper 60 is interposed between the impeller 20 and the frusto- conical exhaust duct 50.
The damper 60 comprises a frame 61 fixed to the housing 30. The damper 60 also comprises a plurality of flaps hinged to the frame 6l about respective rotation axes parallel to each other. In the example shown in the drawings, there is a pair of flaps 62, 63 hinged to the frame 6l about respective rotation axes xl, x2 parallel to each other. The flaps 62, 63 are rotatable between an open position (shown in Fig. 1) and a closed position (shown in Fig. 2), respectively for opening and closing the passage defined in the housing 30.
The transition of the flaps 62, 63 from the closed position to the open position occurs by the direct effect of the thrust exerted by the airflow generated by the impeller 20. Therefore, in order to achieve the transition from the open position to the closed position of the flaps 62, 63 when the impeller 20 is stopped, retum means using gravity and/or elastic forces may be provided. In the illustrated example, respective retum springs (only one of which is visible in Figure 1 and indicated by 64) are provided for retuming the flaps 62, 63 into the closed position, which are connected on one side to the flaps and on the other side to the frame 61.
Furthermore, permanent magnets 65 can be provided on the frame 61 of the damper. These permanent magnets 65 are conf1gured to apply a magnetic force on the flaps 62, 63 when these flaps are proximate to the closed position in order to attract and releasably retain the flaps 62, 63 in the closed position. In other words, the magnets 65 serve to keep the flaps 62, 63 in the closed position when the fan is on rest mode (avoiding the flaps to open also for little positive pressure inside the building). In other embodiments, electromagnetic elements such as coils may be used in place of the permanent magnets.
The electric motor 40 is configured to temporarily invert its rotation direction and therefore drive temporarily the impeller 20 in a second rotation direction opposed to the first rotation direction, when a stop command is received by the control unit 41 of the electric motor 40. In electric motors having programmable control electronics or inverter, this may be obtained by running a software or firmware configured to control a temporary inversion of the motor rotation direction when a stop command is received. In other electric motors, dedicated control circuits may be added to manage the control unit of the electric motor. For instance, when the electric motor is an asynchronous motor, an inversion of the motor rotation direction is obtainable by simply swapping two phases of the motor. Anyway, the invention is not limited to the above mentioned examples. Note that some or all of the components as shown and described above may be implemented in software, hardware, or a combination thereof. For example, such components can be implemented as software installed and stored in a persistent storage device, which can be loaded and executed in a memory by a processor (not shown) to carry out the processes or operations described throughout this application. Altematively, such components can be implemented as executable code programmed or embedded into dedicated hardware such as an integrated circuit (e.g., an application specific IC or ASIC), a digital signal processor (DSP), or a field programmable gate array (FPGA), which can be accessed via a corresponding driver and/or operating system from an application. Furthermore, such components can be implemented as specific hardware logic in a processor or processor core as part of an instruction set accessible by a software component via one or more specific instructions.
With reference to Figure 3, operation of the exhaust fan is described. In normal air extraction operation, the impeller 20 rotates in the first rotation direction (step 101). When a stop command generated by the extemal control system is received by the control unit 41 of the electric motor 40 (step 102), electric power supply to the electric motor 40 is temporarily interrupted, deterrnining thereby a deceleration of the electric motor and consequently, of the impeller 20 (step 103). Then, the control unit 41 triggers the electric motor 40 to rotate in the second rotation direction for a predeterrnined time interval AT in such a way to generate a temporary airflow B flowing in a reverse direction with respect to the exhaust airflow A (step 104). This temporary airflow B is adapted to drive the flaps 62, 63 into the closed position, in Which the flaps 62, 63 are therefore held by the perrnanent magnets 65. The damper is therefore reliably closed by the holding action exerted by the perrnanent magnets 65. The electric power supply to the electric motor 40 is again interrupted, deterrnining thereby the final stop of the electric motor and consequently, of the impeller 20 (step 105).
The delay at Which the electric motor 40 is triggered to rotate after the stop command as Well as the time interval AT are designed based on the specific characteristics of the exhaust fan and associated damper or based on the application/ installation conditions.
Claims (11)
1. An exhaust fan comprising a housing (3 0) defining a passage for an exhaust airfloW (A), an impeller (20) rotatably supported Within said housing, an electric motor (40) operable to drive said impeller to rotate, and a damper (60) comprising a plurality of flaps (62, 63) hinged about respective rotation axes (xl , X2), said plurality of flaps being rotatable between an open position and a closed position, respectively for opening and closing the passage, Wherein said plurality of flaps are driven to open by a dynamic air pressure applied by the exhaust airfloW (A) generated by the impeller (20) rotating in a first rotation direction, return means (64) being provided to bias said plurality of flaps towards the closed position, Wherein said electric motor (40) is configured to drive temporarily said impeller (20), upon a stop command, in a second rotation direction opposed to the first rotation direction, in such a Way to generate a temporary airfloW (B) flowing in a reverse direction With respect to the exhaust airfloW (A), said temporary airfloW being adapted to drive said plurality of flaps into the closed position, characterized by further comprising retaining means (65) configured to releasably retain said plurality of flaps (62, 63) in the closed position.
2. The exhaust fan of claim 1, Wherein said retum means comprise springs (64).
3. The exhaust fan of claim l or 2, Wherein said retaining means comprise magnetic or electromagnetic elements (65).
4. The exhaust fan of any of the preceding claims, Wherein the electric motor (40) comprises an asynchronous motor, and Wherein the electric motor (40) is provided With means adapted to sWap the phases of the electric motor (40) for temporarily driving said impeller in the second rotation direction.
5. The exhaust fan of any of claims 1-3, Wherein the electric motor (40) comprises an inverter operable to invert the rotation direction of the electric motor (40).
6. A method for Operating an exhaust fan, said exhaust fan comprising a housing (3 0) def1ning a passage for an exhaust airflow (A), an impeller (20) rotatably supported within said housing, an electric motor (40) operable to drive said impeller to rotate, a damper (60) comprising a plurality of flaps (62, 63) hinged about respective rotation axes (xl , X2), said plurality of flaps being rotatable between an open position and a closed position, respectively for opening and closing the passage, wherein said plurality of flaps are driven to open by a dynamic air pressure applied by the exhaust airflow (A) generated by the impeller (20) rotating in a first rotation direction, retum means (64) being provided to bias said plurality of flaps towards the closed position, and retaining means conf1gured to releasably retain said plurality of flaps in the closed position, said method comprising the following steps: driving the impeller (20) in said first rotation direction, receiving a stop command, driving temporarily said impeller in a second rotation direction opposed to the first rotation direction, in such a way to generate a temporary airflow (B) flowing in a reverse direction with respect to the exhaust airflow (A), said temporary airflow driving said plurality of flaps (62, 63) into the closed position.
7. The method of claim 6, wherein said retum means comprise springs.
8. The method of claim 6 or 7, wherein said retaining means comprise magnetic or electromagnetic elements.
9. The method of any of claims 6-8, wherein the electric motor (40) comprises an asynchronous motor, and wherein two phases of the electric motor (40) are swapped to drive temporarily said impeller in the second rotation direction opposed to the first rotation direction.
10. The method of any of claims 6-8, wherein an inverter is operated to invert the rotation direction of the electric motor (40) to drive temporarily said impe11er in the second rotation direction opposed to the first rotation direction.
11. A control system, comprising: a processor; and a memory coupled to the processor to store instructions, Which When executed by the processor, cause the processor to perform the method according to any one of c1aims 6-10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE2250907A SE2250907A1 (en) | 2022-07-14 | 2022-07-14 | An exhaust fan and operating method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE2250907A SE2250907A1 (en) | 2022-07-14 | 2022-07-14 | An exhaust fan and operating method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| SE2250907A1 true SE2250907A1 (en) | 2024-01-15 |
Family
ID=89844104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| SE2250907A SE2250907A1 (en) | 2022-07-14 | 2022-07-14 | An exhaust fan and operating method thereof |
Country Status (1)
| Country | Link |
|---|---|
| SE (1) | SE2250907A1 (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5236448U (en) * | 1975-09-08 | 1977-03-15 | ||
| KR100926583B1 (en) * | 2009-04-21 | 2009-11-12 | (주)두영에너텍 | Damper for shutting outside air using magnetic force |
| WO2010129734A2 (en) * | 2009-05-06 | 2010-11-11 | Munters Corporation | Fan for use in agriculture |
| US20130051999A1 (en) * | 2011-08-23 | 2013-02-28 | Ctb, Inc. | Plastic fan shroud and cone assembly and method |
| US20190093663A1 (en) * | 2017-09-22 | 2019-03-28 | The Gsi Group Llc | Adjustable spring tension clip for external damper agricultural fans |
| CN211084350U (en) * | 2019-12-13 | 2020-07-24 | 孙文义 | Ventilation unit for building curtain |
-
2022
- 2022-07-14 SE SE2250907A patent/SE2250907A1/en unknown
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5236448U (en) * | 1975-09-08 | 1977-03-15 | ||
| KR100926583B1 (en) * | 2009-04-21 | 2009-11-12 | (주)두영에너텍 | Damper for shutting outside air using magnetic force |
| WO2010129734A2 (en) * | 2009-05-06 | 2010-11-11 | Munters Corporation | Fan for use in agriculture |
| US20130051999A1 (en) * | 2011-08-23 | 2013-02-28 | Ctb, Inc. | Plastic fan shroud and cone assembly and method |
| US20190093663A1 (en) * | 2017-09-22 | 2019-03-28 | The Gsi Group Llc | Adjustable spring tension clip for external damper agricultural fans |
| CN211084350U (en) * | 2019-12-13 | 2020-07-24 | 孙文义 | Ventilation unit for building curtain |
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