Kiernan, Patrick (Stephenstown, Castletown Navan, Co. Meath, IE)
Mullaney, Conor Joseph (58 Selskar Road, Skerries, Co. Dublin, IE)
Cowling, William Paul (Drummeenagh House, Castlebellingham, County Louth, IE)
Kiernan, Patrick (Stephenstown, Castletown Navan, Co. Meath, IE)
Mullaney, Conor Joseph (58 Selskar Road, Skerries, Co. Dublin, IE)
| 1. | A control system for at least one door activated air curtain unit, the air curtain unit comprising: at least one air heating means having a zero heat setting, a maximum heat setting and at least one intermediate heat setting between said zero heat setting and said maximum heat setting; and at least one air moving fan having a zero fan speed setting, a maximum fan speed setting and at least one intermediate fan speed setting between said zero fan speed and said maximum fan speed setting, the control system comprising a timer, means for detecting the opening and closing of the door and means for controlling the operation of the air heating means and air moving fan, wherein: (I) the control system operatively controls the deactivation of the air curtain unit in response to detecting the closing of the door such that: (a) for a predetermined first time period, the air heating means operates at a first heat setting and the air moving fan operates at a first fan speed whereby the first heat setting and first fan speed are identical to those immediately prior to the closing of the door; (b) for a predetermined second time period, the air heating means operates at a second heat setting and the air moving fan operates at a second fan speed, wherein if in the first time period: the first heat setting was said maximum heat setting, then the second heat setting is selected to be said maximum heat setting or a said intermediate heat setting, or the first heat setting was a said intermediate heat setting, then the second heat setting is selected to be a said intermediate setting not higher than the first heat setting, or the first heat setting was said zero heat setting, then the second heat setting is selected to be the zero heat setting and wherein if in the first time period: the first fan speed was said maximum fan speed then the second fan speed is selected to be said maximum fan speed or a said intermediate fan speed, or the first fan speed was a said intermediate fan speed the second fan speed is selected to be a said intermediate fan speed; (c) for a predetermined third time period the air heating means is deactivated and the air moving fan operates at a third fan speed such that, if the air heating means produced heat during the first and second time periods, residual heat is dissipated from the air curtain unit; (d) in a succeeding fourth time period of indefinite length the air moving fan deactivates so that both the air heating means and the air moving fan are dormant, and (II) the control system operatively controls the reactivation of the air curtain unit in response to detecting the opening of the door at any time during the first, second, third or fourth time period such that the air heating means operates at a reactivated heat setting and the air moving fan operates at a reactivated fan speed. |
| 2. | A control system for controlling the cycle of operating at least one door activated air curtain unit, the air curtain unit comprising: at least one air heating means having high, low and zero heat settings; and at least one air moving fan having high and low fan speed settings; the control system comprising: a timer; means for detecting the opening and closing of the door; and means for controlling the operation of the air heating means and air moving fan, characterised in that the control system is operative: (i) on detecting the closing of the door, to continue to operate the air heating means and air moving fan at the same settings as those immediately prior to the closing of the door; (ii) after a preset first time interval, if the door remains closed, to operate the air heating means at a high or low heat if the initial heat setting is a high heat setting, to continue to operate the air heating means at a low heat if the initial heat setting is a low heat setting or to continue to operate the air heating means at the zero heat setting if the initial heat setting is the zero setting and to operate the air moving fan at a high or low fan speed if the initial fan speed setting is a high fan speed or to continue to operate the air moving fan at a low fan speed if the initial fan speed setting is a low fan speed; (iii) after a preset second time interval, if the door remains closed, to switch off the air heating means and to operate the air moving fan at at least a low fan speed; (iv) after a preset third time interval, if the door remains closed, to switch off the air moving fan; and (v) on detecting the opening of the door at any time during steps (i), (ii), (iii) or (iv), to switch the air heating means and air moving fan to respective reactivated settings. |
| 3. | A control system according to claim 1 or 2 wherein the air heating means comprises at least one electrical resistivetype heating element. |
| 4. | A control system according to claim 1,2 or 3 further comprising detection means to detect the heat setting of the air heating means. |
| 5. | A control system according to any of claims 1 to 4, further comprising detection means to detect the fan speed setting of the air moving fan. |
| 6. | A control system according to any preceding claim, wherein when the air curtain unit is reactivated, the reactivated heat setting of the air heating means is the same as the first heat setting and the reactivated fan speed of the air moving fan is the same as the first fan speed. |
| 7. | A control system according to any preceding claim, wherein the length of the respective first, second and third time periods is independently selected to be in the range of from about 0.5 minutes to about 2 minutes. |
| 8. | A control system according to claim 7 wherein each of the first, second and third time periods are about 1 minute in length. |
| 9. | A control system according to any preceding claim, wherein the control system further comprises manual control means to enable a user to over ride and/or specifically programme the control system. |
| 10. | A control system according to claim 9 wherein said manual control means operatively enables a user to set the length of said first, second and third time periods. |
| 11. | A control system according to any preceding claim, wherein the control system is linked to a remote host computer system. |
| 12. | A control system according to any preceding claim, wherein the air heating means operates at a second heat setting and the air moving fan operates at a second fan speed during the second time period such that, if the air curtain unit is reactivated during this time period, the time taken for air heating means producing heat to reach a reactivated heat setting is reduced and the time taken for the air moving fan to reach a reactivated fan speed is reduced. |
| 13. | A method of controlling at least one door activated air curtain unit having at least one air heating means with a zero heat setting, a maximum heat setting and at least one intermediate heat setting between said zero heat setting and said maximum heat setting; and at least one air moving fan with a zero fan speed setting, a maximum fan speed setting and at least one intermediate fan speed setting between said zero fan speed and said maximum fan speed setting, comprising the steps of : (I) controlling the deactivation of the air curtain unit on detecting the closing of the door by: (a) operating the air heating means at a first heat setting and the air moving fan at a first fan speed for a first time period whereby the first heat setting and first fan speed are identical to those immediately prior to the closing of the door; then (b) operating the air heating means at a second heat setting and the air moving fan at a second fan speed for a second time period, wherein if in the first time period: the first heat setting was said maximum heat setting, then the second heat setting is selected to be said maximum heat setting or a said intermediate heat setting, or the first heat setting was a said intermediate heat setting, then the second heat setting is selected to be a said intermediate setting not higher that the first heat setting, or the first heat setting was said zero heat setting, then the second heat setting is selected to be the zero heat setting; and wherein if in the first time period: the first fan speed was said maximum fan speed then the second fan speed is selected to be said maximum fan speed or a said intermediate fan speed, or the first fan speed was a said intermediate fan speed the second fan speed is selected to be a said intermediate fan speed; then (c) deactivating the air heating means and operating the air moving fan at a third fan speed for a third time period such that, if the air heating means produced heat during the first and second time periods, residual heat is dissipated from the air curtain unit; and then (d) deactivating the air moving fan and maintaining both the air heating means and air moving fan as dormant for a fourth indefinite time period, (II) controlling the reactivation of the air curtain unit on detecting the opening of the door at any time during the first, second, third or fourth time period by: (e) overriding steps (a) to (d); and (f) operating the air heating means at a reactivated heat setting and the air moving fan at a reactivated fan speed. |
| 14. | A method according to claims 13, further including the step of detecting the heat setting of the air heating means. |
| 15. | A method according to claim 13 or 14, further including the step of detecting the fan speed setting of the air moving fan. |
| 16. | A method according to any of claims 13 to 15, further including the step of operating the air heating means at the first heat setting and the air moving fan at the first fan speed when the air curtain unit is reactivated. |
| 17. | A method according to any of claims 13 to 16 wherein each of the first, second and third time periods range from about 0.5 to about 2 minutes in length. |
| 18. | A method according to claim 17 wherein each of the first, second and third time periods are about 1 minute in length. |
| 19. | A method according to any of claims 13 to 18 wherein the air heating means operates at a second heat setting and the air moving fan operates at a second fan speed during the second time period such that, if the air curtain is reactivated during this time period, the time taken for air heating means producing heat to reach a reactivated heat setting is reduced and the time taken for the air moving fan to reach a reactivated fan speed is reduced. |
| 20. | An air curtain system comprising: (i) at least one door activated air curtain unit, having at least one air heating means and at least one air moving fan, to provide an air barrier across a doorway and (ii) at least one control system, as claimed in any of claims 1 to 12, each control system being operative to control at least one air curtain unit. |
| 21. | A Building Energy Management System comprising at least one air curtain system as defined in claim 20. |
| 22. | A control system substantially as hereinbefore described with reference to any of the drawings. |
| 23. | A method of controlling an air curtain unit substantially as hereinbefore described with reference to any of the drawings. |
| 24. | An air curtain system substantially as hereinbefore described with reference to any of the drawings. |
| 25. | A Building Energy Management System as defined in claim 21 and substantially as hereinbefore described. |
Field of Invention This invention relates to a control system and method for controlling at least one door-activated air curtain unit, each unit having at least one air heating means and at least one air moving fan. The invention particularly relates to a control system and method that, on detecting the closure of the door, phases the deactivation of the at least one air curtain unit and on detecting the opening of the door, reactivates the at least one air curtain unit.
Background to the Invention Air curtain units produce a high velocity curtain of air that acts as a barrier to separate different environments. Typically, air curtain units are mounted at doorways in order to provide a curtain of air that inhibits the infiltration of air, dust, smoke, insects, pollution and odours into a building or room. Door activated air curtain units are activated as and when the door is opened. Air curtain units help to keep heated and air conditioned air in a building or room and so reduce heat loss in the winter and maintain an air conditioned environment in the summer. Air curtain units with air heating means are particularly useful in helping to control the temperature of a heated internal environment. When these types of air curtain units are activated the air moving fan draws in air, moves the air over the heating elements and expels the now warmed air as a high speed jet across the door opening. The curtain of warm air acts as a barrier to keep out the cold air and keep in the warm air, helps to heat the internal space and provides a welcome warm draft as people
walk through the doorway. Air curtain systems including such air curtain units are commonly used in shops, offices, factories and warehouses etc.
Unfortunately, air curtain units suffer from an initial operational delay when activated. It takes time for the fan to produce a sufficiently high velocity stream of air to act as a barrier and as a consequence air, dust, smoke, insects, pollution and odours are able to ingress until the fan is fully operational.
Furthermore, it also takes time for electrical heating elements to become hot enough to sufficiently warm the air passing through the air curtain unit. As a result, the air curtain unit creates a'chill effect', similar to that of a conventional table-mounted or floor-standing cooling fan, because the initial stream of air is either at the same temperature or only slightly warmer than the ambient air temperature. It has been found that a fan may take 1-1.5 seconds to become fully operational and an electrical air heating element may take even longer to become hot enough to sufficiently warm the air. An automatic door typically takes approximately 4 seconds to open and close, therefore such operational time delays are very significant. Hence, the effectiveness and efficiency of an air curtain unit is seriously reduced if it only operates when a door is open, particularly if the door is only open for a short space of time or repeatedly opened and closed.
It is imperative to disperse the heat energy from the electrical air heating elements and fan when an air curtain unit is deactivated. The heat energy must be dispersed as quickly as possible in order to try and reduce high temperatures within the air curtain unit, reduce the temperature of products fitted locally to the air curtain unit and prevent the stressing of components.
Heat energy is dispersed by either natural convection or by continuing to operate the fan during a'cooling cycle'. The natural convection method is inefficient and often takes a significant amount of time to sufficiently cool the
air curtain unit and locally fitted products. The cooling cycle may be thermostatically controlled or time based. When the fan and heating elements are switched off the overall internal temperature of the air curtain unit initially increases. This is because the heating elements are still hot and continue to radiate heat, but the fan is unable to disperse this heat. A thermostatically controlled cooling cycle includes a thermostat located within or adjacent the air curtain unit. Theoretically, a thermostatically controlled cooling cycle should immediately re-activate the fan in order to disperse the heat once an air curtain unit has been switched off. However, in practice this does not occur.
This is because the thermostat can only be set to reactivate the fan at a particular temperature. Such controlled cooling cycles are not intelligent and are insensitive to different ambient or operating conditions. Thus, the reactivation of the fan may be delayed since it may take some time for the internal temperature of the unit to reach the requisite thermostatic triggering temperature. Alternatively, the fan may never be reactivated because the internal temperature of the air curtain unit may never reach the requisite temperature. In reality, thermostatically controlled cooling cycles are ineffective and inefficient. Furthermore, they are also wholly inappropriate for door activated air curtain units. A time based cooling cycle is simplistic and merely enables a fan to operate for a set period of time. Once the fan has stopped, any remaining heat is dissipated by natural convection.
Statements of Invention The present invention seeks to counteract the problems incurred due to the initial operational delay of an air curtain unit. In particular, the present invention helps to counteract the ingress of air due to the operational delay of
the air moving fan and the unwanted'chill effect'due to the operational delay of the air heating means.
The present invention seeks to counteract the operational delay of the air moving fan and air heating means if the air curtain unit reactivates during the deactivation cycle.
The present invention seeks to overcome the problems associated with the air curtain unit when it repeatedly deactivates and reactivates as the door closes and opens in quick succession.
The present invention seeks to effectively and efficiently cool the air curtain unit by dispersing heat energy.
A first aspect of the invention relates to control system for at least one door activated air curtain unit, the air curtain unit comprises at least one air heating means having a zero heat setting, a maximum heat setting and at least one intermediate heat setting between said zero heat setting and said maximum heat setting and at least one air moving fan having a zero fan speed setting, a maximum fan speed setting and at least one intermediate fan speed setting between said zero fan speed and said maximum fan speed setting, the control system comprises a timer, means for detecting the opening and closing of the door and means for controlling the operation of the air heating means and air moving fan, wherein: (I) the control system operatively controls the deactivation of the air curtain unit in response to detecting the closing of the door such that (a) for a predetermined first time period, the air heating means operates at a first heat setting and the air moving fan operates at a first fan speed whereby the first heat setting and first fan speed are identical to those immediately prior to the
closing of the door; (b) for a predetermined second time period, the air heating means operates at a second heat setting and the air moving fan operates at a second fan speed, wherein if in the first time period: the first heat setting was said maximum heat setting, then the second heat setting is selected to be said maximum heat setting or a said intermediate heat setting, or the first heat setting was a said intermediate heat setting, then the second heat setting is selected to be a said intermediate setting not higher than the first heat setting, or the first heat setting was said zero heat setting, then the second heat setting is selected to be the zero heat setting, and wherein if in the first time period: the first fan speed was said maximum fan speed then the second fan speed is selected to be said maximum fan speed or a said intermediate fan speed, or the first fan speed was a said intermediate fan speed the second fan speed is selected to be a said intermediate fan speed; (c) for a predetermined third time period the air heating means is deactivated and the air moving fan operates at a third fan speed such that, if the air heating means produced heat during the first and second time periods, residual heat is dissipated from the air curtain unit; (d) in a succeeding fourth time period of indefinite length the air moving fan deactivates so that both the air heating means and the air moving fan are dormant, and (II) the control system operatively controls the reactivation of the air curtain unit in response to detecting the opening of the door at any time during the first, second, third or fourth time period such that the air heating means operates at a reactivated heat setting and the air moving fan operates at a reactivated fan speed.
In a second aspect, the invention includes a control system for controlling the cycle of operating at least one door activated air curtain unit, the air curtain unit comprising at least one air heating means having high, low and zero heat settings and at least one air moving fan having high and low fan speed
settings; the control system comprising a timer, means for detecting the opening and closing of the door and means for controlling the operation of the air heating means and air moving fan, characterised in that the control system is operative: (i) on detecting the closing of the door, to continue to operate the air heating means and air moving fan at the same settings as those immediately prior to the closing of the door; (ii) after a pre-set first time interval, if the door remains closed, to operate the air heating means at a high or low heat if the initial heat setting is a high heat setting, to continue to operate the air heating means at a low heat if the initial heat setting is a low heat setting or to continue to operate the air heating means at the zero heat setting if the initial heat setting is the zero setting and to operate the air moving fan at a high or low fan speed if the initial fan speed setting is a high fan speed or to continue to operate the air moving fan at a low fan speed if the initial fan speed setting is a low fan speed; (iii) after a pre-set second time interval, if the door remains closed, to switch off the air heating means and to operate the air moving fan at at least a low fan speed; (iv) after a pre-set third time interval, if the door remains closed, to switch off the air moving fan; and (v) on detecting the opening of the door at any time during steps (i), (ii), (iii) or (iv), to switch the air heating means and air moving fan to respective reactivated settings.
Typically, the air heating means comprises at least one electrical resistive-type heating element.
Preferably, the control system further comprises detection means to detect the heat setting of the air heating means. The control system may also comprise detection means to detect the fan speed setting of the air moving fan.
Preferably, when the air curtain unit is reactivated, the reactivated heat setting of the air heating means is the same as the first heat setting and the requisite fan speed of the air moving fan is the same as the first fan speed.
The length of the respective first, second and third time periods may be independently selected to be in the range of from about 0.5 minutes to about 2 minutes. It is preferable for each of the first, second and third time periods are about 1 minute in length.
The control system may further comprise manual control means to enable a user to over-ride and/or specifically programme the control system.
Preferably, the manual control means operatively enable a user to set the length of said first, second and third time periods.
The control system may be linked to a remote host computer system.
Preferably, the air heating means operate at a second heat setting and the air moving fan operate at a second fan speed during the second time period such that, if the air curtain unit is reactivated during this time period, the time taken for air heating means producing heat to reach a reactivated heat setting is reduced and the time taken for the air moving fan to reach a reactivated fan speed is reduced.
A third aspect of the invention relates to a method of controlling at least one door activated air curtain unit having at least one air heating means with a zero
heat setting, a maximum heat setting and at least one intermediate heat setting between said zero heat setting and said maximum heat setting and at least one air moving fan with a zero fan speed setting, a maximum fan speed setting and at least one intermediate fan speed setting between said zero fan speed and said maximum fan speed setting, comprising the steps of : (I) controlling the deactivation of the air curtain unit on detecting the closing of the door by (a) operating the air heating means at a first heat setting and the air moving fan at a first fan speed for a first time period whereby the first heat setting and first fan speed are identical to those immediately prior to the closing of the door; then (b) operating the air heating means at a second heat setting and the air moving fan at a second fan speed for a second time period, wherein if in the first time period: the first heat setting was said maximum heat setting, then the second heat setting is selected to be said maximum heat setting or a said intermediate heat setting, or the first heat setting was a said intermediate heat setting, then the second heat setting is selected to be a said intermediate setting not higher that the first heat setting, or the first heat setting was said zero heat setting, then the second heat setting is selected to be the zero heat setting; and wherein if in the first time period: the first fan speed was said maximum fan speed then the second fan speed is selected to be said maximum fan speed or a said intermediate fan speed, or the first fan speed was a said intermediate fan speed the second fan speed is selected to be a said intermediate fan speed; then (c) deactivating the air heating means and operating the air moving fan at a third fan speed for a third time period such that, if the air heating means produced heat during the first and second time periods, residual heat is dissipated from the air curtain unit; and then (d) deactivating the air moving fan and maintaining both the air heating means and air moving fan as dormant for a fourth indefinite time period, and (II) controlling the reactivation of the air curtain unit on detecting the opening of the door at any time during the first, second, third or fourth time period by:
(e) over-riding steps (a) to (d); and (f) operating the air heating means at a reactivated heat setting and the air moving fan at a reactivated fan speed.
In a fourth aspect, the invention relates to an air curtain system comprising (i) at least one door activated air curtain unit, having at least one air heating means and at least one air moving fan with high and low fan speed settings, to provide an air barrier across a doorway and (ii) at least one control system, according to either the first or second aspect of the invention, each control system being operative to control at least one air curtain unit.
A fifth aspect of the invention relates to a Building Energy Management System comprising at least one air curtain system according to the fourth aspect of the invention.
Brief Description of the Drawings For a better understanding of the present invention and how it may be carried into effect, reference shall now be made by way of example to the accompanying drawings in which: Figure 1 depicts a door activated air curtain unit.
Figure 2 depicts a flow chart indicating the operation of the air curtain unit of Figure 1 when the door opens and closes.
Detailed Description of Drawings Figure 1 depicts a door activated air curtain unit 1 mounted on the wall above a doorway 2. The air curtain unit includes an intake 3 through which air is drawn into the unit and a nozzle 4 through which air is expelled.
An air curtain system may include a single air curtain unit or a plurality of air curtain units.
Air curtain units are usually mounted horizontally on the wall above a doorway. However, air curtains may be mounted on the ceiling above a doorway or installed within the wall or ceiling. Alternatively, air curtain units may be mounted vertically along one or both sides of a doorway. Furthermore, air curtain units may be integrated vertically or horizontally within a door unit.
Air curtain units may be Im or 1. 5m in length. A single air curtain may be mounted to provide an air barrier across the width of a conventional doorway.
Alternatively, a series of air curtains may be mounted to provide an air barrier across a much wider doorway.
In operation, air is drawn into the air curtain unit through the intake 3, across the air heating means (not shown) and a high-pressure stream of air is forced out through the nozzle 4. The air is expelled such that a uniform curtain of air is provided across the entire width of the doorway and from the top of the doorway to the floor.
Air is moved along the air-moving path within the air curtain unit by at least one air moving fan. The air moving fan may have a zero fan speed, maximum fan speed and at least one intermediate fan speed between the zero and maximum fan speeds. In this particular embodiment the air curtain includes a
motor driven centrifugal fan (not shown). The motor driven fan may operate at 90W, 120W, 190W or 250W and may be powered by 380-415V 3 phase AC (220-240V phase to neutral). The motor driven fan has two connections MI and M2 and only one may be powered at a time. M 1 equates to a low fan speed and M2 equates to a high fan speed. The embodiment depicted in the Figures has a low fan speed of approximately 900 rev/min and a high fan speed of approximately 1400 rev/min. Effectively, MI is approximately half the fan speed of M2. With such fan speeds, air may be drawn into the air curtain at approximately 2m/s and the velocity of the curtain of air may range from approximately 8m/s to 15m/s.
The intake 3 may include a grill with fixed vanes. The nozzle 4 may include a grill with adjustable vanes, thus allowing the direction of the air curtain to be adjusted.
At least one air heating means is arranged within an air curtain unit to heat the air prior to its expulsion through the nozzle 4. The air heating means may have a zero heat setting, maximum heat setting and at least one intermediate heat setting between the zero and maximum heat settings. The heating elements are electrically powered resistor type units. In this particular embodiment, the air curtain includes two identical electrical heating elements HI and H2 (not shown). These heating elements may reach an operating temperature of approximately 300°C. The heating elements are arranged such that neither element, one or both elements may be energised when the air curtain unit is operational. Obviously, when neither element is powered no heat is provided.
When one unit is energised (H1 or H2) only a low level of heat is provided to warm the air as it passes through the air curtain unit. When both units are powered (H1 and H2) a high level of heat is provided. In the embodiment depicted, air moving through the air curtain is heated to a temperature of
approximately 34°C when both heating elements are powered. Since the heating elements are identical one energised heating element provides half the heat of two energised heating elements. Such an arrangement enables the air curtain system to be usable throughout the whole year. For example, on a particularly cold winter day the ambient temperature will be low and both heating elements H1 and H2 will be required to sufficiently warm the air.
Whereas, the ambient air temperature will be much higher in the summer and so the heating elements are unnecessary. In such a situation, the air curtain is set to advantageously create a'chill effect'.
The air curtain unit is adaptable to cope with all on site conditions and can provide a barrier that is sufficient for all weather conditions.
A control system (not shown) electronically controls at least one door activated air curtain unit. A single control system may control a host of air curtain units arranged throughout a building, alternatively a control system may control a single or plurality of air curtain units mounted at a specific doorway. The control system preferably includes a processor or other suitable programmable or non-programmable circuitry including suitable software.
The control system includes a microcontroller that controls the air heating means and air moving fan. The microcontroller is pre-programmed to phase the deactivation of the air curtain unit when the door closes and reactivate the unit when the door opens.
The control system may also include manual control means to enable a user to over-ride and/or specifically programme the system. The manual control means may allow the user to retrieve information from the control system, set various parameters and/or program or reprogram the control system. The
manual control means may include a user interface. The user interface may be wall mounted. The interface preferably includes a touch screen or keyboard or may include switches. A switch box type interface may include a general on/off switch for the at least one air curtain unit, a switch to set the fan speed to low or high, a switch to set the heat setting to zero, low or high and a switch to override the door activation/deactivation cycle in order to run the air curtain unit continuously. The manual control means may include a remote-control device that communicates with an appropriately configured control system.
The remote control device may communicate with the control system using infrared, radio or other suitable signals.
Suitable devices, circuitry and software for implementing a control system will be readily apparent to those of ordinary skill in the art.
An air curtain system includes at least one air curtain unit to provide an air barrier across a doorway and at least one control system, each control system being operative to control at least one air curtain unit.
A plurality of control systems may be linked to a remote host computer to control a network of air curtain units/systems throughout a building or series of buildings.
An air curtain system may be one of many different types of environmental control systems used in a building. Thus, a control system (or plurality of control systems) may be connected to a remote host computer/computer network that controls a range of environmental systems to regulate the environment of a building. These are commonly known as Building Energy Management Systems (BEMS). Building Energy Management Systems are
well known and their features will be readily apparent to persons skilled in the art.
The speed at which the fan operates when the air curtain is operational may be pre-programmed into the control system, set by the manual control means and/or set by a host computer. The control system includes control means to automatically set, adapt and regulate the fan speed at different stages of the operation and/or over time. The control system may further include sensors to detect on site conditions (e. g. external wind speed). The control system may further include control means to regulate the speed of the fan according to environmental conditions. The control system also may also include detection means to detect the fan speed of the air moving fan.
The control system includes a door sensor to detect the opening and closing of a door. On detecting the opening of the door, the control system activates the air curtain unit such that a barrier of air is created across the open doorway.
The expelled air may or may not have been warmed by the air heating means.
The air curtain unit continues in'active mode'until the door is closed. On detecting the closure of the door, the control system deactivates the air curtain unit in a phased manner. If the door is reopened during or once deactivation has occurred then the air curtain is reactivated. Such operational steps are explained in more detail below.
As explained above, the control system may also include means to override the door sensor so that the air curtain unit is never deactivated when the door closes.
The amount of heat provided by the air heating means when the air curtain is operational may be pre-programmed into the control system, set by the manual
control means and/or set by a host computer. The control system includes control means to automatically set, adapt and regulate the use of the air heating means at different stages of the operation and/or over time. The control system may include ambient temperature sensors to detect the internal and/or external temperature. The control system may further include thermostatic switches to thermostatically control the air heating means in accordance with the internal and/or external temperatures. The thermostatic switches may particularly control air heating means H2. The control system may also include detection means to detect the heat setting of the air heating means.
The control system includes timing means to control the operation of the air curtain unit. The timing means may also control the times at which the air curtain system may be used. The timing means may be pre-programmed, set by the manual control means and/or set by a host computer.
The control system may further include a faults feedback system to detect, report and shutdown the air curtain system.
The operational steps of the door activated air curtain system shall now be explained with reference to the flow chart of Figure 2. Figure 2 depicts the operational steps of the embodiment of the invention as shown in Figure 1 and described above. Initially the control system detects the general operational mode of an air curtain unit (Block 100). If the mains switch is detected as being'open'then the air curtain unit is in permanent dormant mode. The control system triggers the air moving fan of the unit to operate for a specified time period (Block 140) if the air curtain unit is found to have been turned off in the past 60 seconds (Block 120). This helps to ensure that the heat from the air curtain has fully dissipated. If the mains switch is detected as being
'closed'then the air curtain unit is recognised as being in operational mode.
The control system goes on to determine if the door is open or closed (Block 160).
If the door is open then the air curtain unit is activated to provide an air barrier across the doorway. The air moving fan may operate at a maximum fan speed or an intermediate fan speed. In the embodiment depicted in Figure 2, the air moving fan operates at full or half speed (Block 180). As explained above, the speed at which the fan operates may be pre-programmed, manually specified, remotely controlled by a host computer, environmentally controlled and/or regulated during operation. The air heating means may operate at a maximum heat setting, an intermediate heat setting or zero heat setting. In the embodiment depicted, the air heating means operate at full, half or no heat (Block 200). The level of heat provided may be pre-programmed, manually specified, remotely controlled by a host computer, thermostatically controlled and/or regulated during operation.
If the door is closed, and has been closed for more than approximately 3 minutes, then the control system starts the cycle again (Block 220). If the control system detects the closure of the door then it triggers a phased shut down of the air curtain unit. Initially, the air heating means and air moving fan continue to operate at the same levels immediately prior to the closure of the door (e. g. Full or half fan speed and full, half or no heat) (Block 240). The air curtain unit effectively'runs-on'and maintains the same state for a first time period. During the second phase (Block 260), the air moving fan and air heating means operate at levels sufficient to reduce the operational delay of the air curtain unit if it is reactivated at this stage in the deactivation cycle. The operational delay of the fan is at least minimised because it will still be moving air throughout the second time period and so will take less time to
become fully operational when reactivated. The operational delay of the fan may even be eliminated if the second fan speed matches that of the requisite reactivated fan speed. If in use prior to the closure of the door, the operational delay of the air heating means will at least be minimised because it will still be warm throughout the second time period and so will take less time to become fully operational when reactivated. As with the fan, the operational delay of the air moving means may be eliminated if the second heat setting matches that of the requisite reactivated heat setting. The air moving fan may continue to operate at a full speed, if this was the case during the first time period.
However, the fan preferably operates at half speed (Block 280). The air heating means may continue to operate at a full heating setting, if this was the case during the first time period, but it is preferably controlled to operate at half heat during the second phase. However, if the air heating means were not in use when the air curtain unit was in'active mode'then no heat is provided during the second phase of the shut down cycle (Block 300). In the third phase (Block 320) the air heating means are deactivated and the air moving fan is operated at a speed that sufficiently enables heat to dissipate. The fan may operate at full speed but preferably operates at half speed (Block 340). The control system ensures all the heating elements are now deactivated and no heat is provided during the third time period. Finally, in the fourth phase, the air moving fan is deactivated. The air moving fan and air heating means are now dormant.
In the embodiment depicted in the Figures the first, second and third phase of the shut down cycle are times periods of approximately 1 minute (60 seconds).
Alternatively, the first, second and third time periods may each range from approximately 0.5 minutes (30 seconds) to approximately 2 minutes (120 seconds) in length. If this is the case, then the time period at Block 220 must
be suitably adapted. The fourth phase is indefinite and depends on when the door is opened again and the air curtain unit is activated.
The control system reactivates the air curtain when it detects the opening of the door. The door may be opened at any time during the shut-down cycle or when the air curtain is dormant. The air heating means may be triggered to operate at any particular heat setting (e. g. full, half or zero). The heat setting of the reactivated air heating means may be pre-programmed, selected, determined according to environmental conditions or set to match the heat setting prior to the closure of the door (i. e. the first heat setting). Furthermore, the air moving fan may be triggered to operate at any fan speed (e. g. full or half). The fan speed of the activated air moving fan may be pre-programmed, selected, determined according to environmental conditions or set to match the fan speed prior to the closure of the door.
Phasing the deactivation of the air curtain unit in such a manner is most advantageous. Phasing the deactivation of the air curtain unit compensates for the problems incurred due to the initial operation delay of the air moving fan and air heating means. Phasing the deactivation of the air curtain unit overcomes the problems associated with a door activated unit that is repeatedly open and closed. Furthermore, the phased deactivation of the air moving fan and air heating means leads to the quick and efficient cooling of the air curtain unit (i. e. the first fan speed).
The first and second phase of the shut down cycle compensates for the initial operational delay of the air curtain unit when it is activated. As described above, the air moving fan and air heating means take time to become fully operational. As a result air, dust, smoke, insects, pollution and odours are able to ingress until a sufficient air barrier is created across the doorway. By
continuing to operate the fan and heating means for a period of time, after the door is closed, the air curtain system is able counter the temperature imbalance and heat energy losses that occur during the initial operational delay by providing further warm air and recirculating existing warm air that is trapped under the ceiling.
The first phase of the deactivation cycle overcomes the problems associated with a repeatedly open and closed door since the requisite air curtain barrier is maintained throughout this time period. Consequently, the air curtain unit does not suffer from an operational delay leading to an ingress of air or undesirable 'chill effect'if the door is opened at any time during the first phase.
The second phase of the shut-down cycle counteracts the operational delay of the air curtain unit if the door is opened during the second time period. The air moving fan operates at a speed so that, if the unit is activated, the length of time it takes for the fan to become fully functional is minimised or eliminated.
The air heating means may also operate at a heat setting so that, if the unit is activated, the length of time to takes to get the heating means sufficiently warm is minimised or eliminated.
Lowering the fan speed during the second and/or third phase reduces the noise produced by the air curtain unit.
Dropping both the heat setting and fan speed from full to half rate during the second time period the air curtain unit saves up to 25% energy.
During the third phase of the shut down cycle the fan operates at a speed so that air continually moves through the air curtain in order to help dissipate any
residual heat. Thus, this phase ensures that the residual heat is significantly eliminated from the air curtain system before entering the deactivated state.
The preferred features of the invention are applicable to all aspects of the invention and may be used in any possible combination.
Throughout the description and claims of this specification the words "comprise"and"contain"and variations of the words, for example "comprising"and"comprises", means"including but not limited to"and are not intended to and do not exclude other components, integers, moieties, additives or steps.