METHOD THERE FOR

The present invention relates to an air curtain device for providing an air curtain. More specifically, the invention relates to an air curtain preferably with a substantially vertical air flow. Such an air curtain device is usually provided in or close to an opening, in particular a door opening.

Known air curtain devices provide an air curtain in or close to an opening in a wall to minimize leakage, energy losses and discomfort for people. These air curtains are often provided in door openings with different climate conditions on both sides of the opening. These climate conditions may include temperature and humidity. Several external factors influence the quality of the air curtain that is produced by the air curtain device. Such factors may include wind, wind direction, and sun. However, these factors influence the quality of the air curtain such that the air curtain is in most cases overdimensioned and uses too much energy, or does not perform optimally such that leakages and energy losses are not fully prevented. This results in a not fully effective air curtain.

DE 44 20 167 CI discloses the use of an infra-red sensor for measuring a temperature of a reference point.

The present invention has for its object to provide an air curtain device for realizing an air curtain that is more effective in a broad range of conditions and disturbances, and wholly or partially obviates the above- stated drawbacks, such that a desired air curtain quality is achieved .

Therefore, the present invention provides for this purpose an air curtain device for providing an air curtain in or close to an opening in a wall according to the

invention, the device comprising:

- a housing with air displacing means;

- at least one air inlet for supplying air to the

housing;

- at least one outflow opening for achieving the air curtain ;

- a sensor configured for measuring a temperature

profile extending over a length extending through the air curtain in a substantial horizontal direction and substantially perpendicular to the air curtain; and

- a controller with connecting means configured for connecting with the sensor, the controller configured for adjusting the air curtain based on differences between the measured temperature profile and a

reference profile.

The housing of the air curtain device according to the invention comprises air displacing means, comprising for instance one or more fans. Air is supplied via an air inlet. In most cases this air inlet is situated in the immediate vicinity of the position where the air curtain is realized and used, although the air inlet channels can be provided at other positions such that air is transported to the desired position. If desired, a plurality of air inlet channels can be provided.

The air curtain device according to the invention provides the air curtain, preferably flowing substantially in a vertical direction, using an outflow opening or series of outflow openings that extend substantially in a

horizontal direction, usually over substantially the same width of the opening in the wall. Preferably, the air curtain is provided over a somewhat larger distance as compared to the opening in which the air curtain is

provided .

The air curtain is provided in or close to an opening in a wall, with the opening usually being a door opening, for instance an entrance to a shop or storage space. In use, the air curtain is provided substantially in or parallel to the opening in the wall to prevent or reduce leakage and energy losses.

According to the invention the air curtain device comprises a sensor for measuring a temperature profile. The temperature profile that is measured, in use, extends over a length through the air curtain in a substantially horizontal direction. In a presently preferred embodiment the measured temperature profile extends over the floor or ground

surface, or at least along a line close thereto. Preferably, in use, the sensor measures the temperature profile over a length that extends perpendicular to the air curtain. The sensor may measure average temperatures in ( sub) -intervals of the measurement length/interval or measure a more

continuous temperature profile.

The sensor enables measuring the quality and/or effects of the air curtain in a direction substantially perpendicular to the main air flow direction of the air curtain. This enables measuring the (disturbing) effects of outside conditions and/or disturbances on the air curtain, such as wind, wind direction, and sun. For example, when the wind is blowing towards the air curtain from one side thereof the center or boundary line of the air curtain will be moved towards the other side. This center or boundary line of the air curtain divides the air of the air curtain towards either side of the air curtain when reaching the floor. Amongst other things, the measured temperature profile indicates the location of this center or boundary line .

Measuring a profile, such as a temperature

profile, over a certain length, provides information over the effect of the air curtain including effects thereon by varying outside weather conditions, for example. Measuring the effect of an air curtain in a single location is

insufficient. For example, due to a wind gust or wind storm the air curtain can be moved inwardly from the opening while the single location may provide insufficient information on the actual condition and the relevancy of adapting the settings of the air curtain device, for example.

A further advantageous effect of measuring a temperature profile as compared to measuring a temperature at a specific location/spot only is that erroneous control adjustments can be prevented. For example, adjusting the outflow angle of the air curtain device may improve the air curtain while increasing fan speed would only result in additional energy loss.

By comparing the measured temperature profile with a reference temperature profile and providing the

differences to a controller that may act on differences between these two profiles, the air curtain can be adjusted. In a presently preferred embodiment the controller adjusts the air curtain with adjusting means. These adjusting means may involve one or more of fan speed, size of inlet opening and/or outlet opening, temperature conditions of the air for the air curtain, guide vanes, other air flow directors or manipulators for adjusting the air flow direction etc.

By correcting and/or compensating the air curtain based on the difference between a measured temperature profile and a reference temperature profile the air curtain may fulfill its duties over a broad range of conditions and disturbances. This provides an air curtain with good

quality .

For example, if one side of the air curtain shows a desired temperature profile and the other side shows a temperature profile that is too high as compared to the reference profile there appears to be too much air in the air curtain such that the amount of air in the air curtain can be reduced without adversely affecting the desired quality of the air curtain. On the other hand, in an example wherein the inside temperature of the temperature profile is too low, there may be energy losses towards the other, colder, side of the air curtain. This may be a reason to increase the amount of air in the air curtain by increasing the fan speed and/or increasing the air temperature in the air curtain.

The adjustments of the air curtain in the air curtain device according to the invention assure that the air curtain quality can be maintained over a broad range of conditions and disturbances. This reduces leakage and energy losses over a broad range of conditions and disturbances.

In a presently preferred embodiment the sensor comprises an infra-red sensor. This infra-red sensor is capable of measuring the temperature profile accurately in a robust manner such that can be relied on the measured temperature profile for adjusting the temperature and optimizing the air curtain quality.

In one of the preferred embodiments according to the invention comparing the measured profile with a

reference profile involves determining the maximum

temperature gradient along the length of the measured temperature profile. This gradient is sensitive to

disturbances. This renders the gradient useful for adjusting the air curtain. The gradient can be determined by the controller that preferably comprises calculating means configured for determining the maximum temperature gradient along the length of the measured temperature profile.

Adjusting the air curtain may involve changing parameters of the air curtain device, such as fan speed, outflow

direction, and air temperature. Adjustments can be made by the controller in view of differences between measured and reference temperature profile. The differences may relate to the actual value for the gradient and/or the location along the temperature profile length with the maximum gradient, for example.

Typically, the length of the temperature profile is in the range of 1-20 m, more preferably in the range of 2-10 m. It is shown that this range for the length of the measured temperature profile will suffice in most relevant cases. Providing information about this temperature profile to the controller enables adjusting the air curtain and maintaining the air curtain quality at a desired level.

In an advantageous preferred embodiment according to the present invention the temperature profile has a width in a direction substantially parallel to the plane of the opening in the wall. Preferably, the width of the

temperature profile corresponds to the width of the opening in the wall .

By providing information not only for a temperature profile having a length, but also having a significant width, air curtain information is collected over a plane preferably extending in a substantially horizontal direction and substantially perpendicular to the air

curtain. Measuring in a width direction can be achieved by providing measurements along different more or less parallel lines and/or performing a measurement more continuously over the desired surface. Providing measurement information about a

temperature profile extending over a plane with a length and a width may provide additional information to the

controller. For example, in a presently preferred embodiment this additional information relates to the edges or

boundaries of the air curtain and/or close to the sides of the opening. This enables taking into account so-called side effects of the air curtain. For example, wind gusts may influence the air curtain especially at the sides/edges thereof. Using the measured two dimensional temperature profile information enables the controller to adjust the air curtain accordingly, thereby further improving and/or maintaining the air curtain quality.

In a further advantageous preferred embodiment according to the present invention the air curtain device further comprises a detector for detecting people

approaching the air curtain.

Providing a detector for detecting people approaching the air curtain enables adapting the air curtain when people are about to pass through. This may not only maintain the quality of the air curtain, but may also improve the comfort for the people passing through the air curtain. In a presently preferred embodiment the detector is combined with the sensor for measuring a temperature

profile, more preferably with the infra-red sensor.

In a further advantageous preferred embodiment according to the present invention the device further comprises a door position detector for enabling the

controller to compensate the air curtain for the door position.

When an opening is partly closed the air curtain requirements are significantly influenced. A(n) (unknown) door position can be deduced from the measured temperature profile and/or with a separate door position detector. The use of this measured information by the sensor and/or detector enables the controller to adjust the air curtain taking into account the actual door position. In a presently preferred embodiment the door position detector is

integrated in the sensor, more preferably the infra-red sensor .

The sensor of the air curtain device according to the invention can be provided integrally or separately from the air curtain device thereby improving installation flexibility. The sensor may communicate with the air curtain device wired or wireless using a transmitter and/or a receiver .

The invention further relates to a method for realizing an air curtain in or close to an opening in a wall, the method comprising the steps of:

- providing an air curtain device as described above ;

- producing the air curtain with a device;

- measuring the temperature profile extending over a length extending through the air curtain in a substantial horizontal direction and substantially perpendicular to the air curtain;

- comparing the measured temperature profile with the reference temperature profile; and

- adjusting the air curtain based on comparing the measured temperature profile with the referenced profile by the controller.

Such a method provides the same effects and advantages as those in respect of the air curtain device.

In a presently preferred embodiment according to the invention the air curtain is adjusted by the controller on basis of temperature gradient, more preferably on basis of differences between the measured and reference temperature gradient. Preferably, the temperature gradient comprises the maximum temperature gradient along the length of the measured temperature profile. Alternatively, or in addition to the value of the temperature gradient, the air curtain is adjusted on basis of location exhibiting maximum temperature gradient. This provides an effective means to adjust the air curtain by manipulating the angle of the outflow of air through the outflow opening, air temperature of the outflow of air through the outflow opening and/or speed of the outflow of air through the outflow opening, in case of disturbances, such as wind gusts of a wind "storm".

Further advantages, features and details of the invention are elucidated on the basis of preferred

embodiments thereof, wherein reference is made to the accompanying drawings, in which:

- Fig. 1 shows a view of an air curtain device according to the invention;

- Fig. 2A-B shows two measured temperature

profiles; and

- Fig. 3 shows a schematic overview of a method for adjusting with the air curtain according to the invention.

Air curtain device 2 (Fig. 1) produces air curtain 4. In the illustrated embodiment air is provided to device 2 via air inlet 6 and leaves device 2 through a series of outflow openings 8. The housing of device 2 comprises one or more fans 10 and, optionally, one or more heater elements 12. Outflow openings 8 can be provided with guide vanes, an airflow directing grille and/or other guides 14. In the illustrated embodiment device 2 is connected via

construction elements 16 to ceiling 18. In the illustrated embodiment air curtain 4 is provided in opening 20 in wall 22 and extends in a substantially vertical direction towards floor or ground surface 24. Air curtain 4 comprises a central or boundary line 26 separating air of air curtain 4 going to either one of the two sides of opening 20.

Air curtain device 2 is provided with infra-red sensor 28 capable of measuring a temperature profile on ground surface 24 with a detection area 30. Sensor 28 measures a temperature profile over a length B in a

direction substantially perpendicular to air curtain 4 and preferably along ground surface 24. Optionally, sensor 28 also measures temperature profiles in a direction C

perpendicular to the direction B and parallel to opening 20 and air curtain 4. This achieves a measuring temperature profile over a surface are preferably corresponding to ground surface 24 or close thereto.

A measured temperature profile 32 (T _m ) (Fig. 2A-B) is compared with a reference temperature profile 34 (T _ref ) over the length B and/or width C of the profile. In the illustrated examples of temperature profiles 32, 34 the vertical axis corresponds to the central or boundary line 26 in a neutral position, i.e. without disturbances acting on air curtain 4.

In the illustrated temperature profiles (Fig. 2A- B) reference maximum temperature gradient 48 at location xi (Fig. 2A) along length B is compared with measured maximum temperature gradient 48a. Alternatively, or in addition therewith, the location X2 (Fig. 2B) of the measured maximum temperature gradient 50a is compared with the location xi of the reference maximum temperature gradient 50. The

comparison ( s ) may lead to adjustments of the air curtain and/or air curtain device.

The method 36 for operating device 2 (Fig. 3) starts with initiating step 38 for starting device 2, followed by activating step 40 to produce air curtain 4. In measuring step 42 a temperature profile 32 is measured to enable controller 44 to perform a comparing step 46 and define control actions to adjust air curtain 4.

For example, in case the measured temperature profile 32 shows a too high temperature as compared to the reference temperature profile 34 on the inside of opening 20, i.e. inside the building, the air curtain produces too much energy such that the amount of air can be reduced and/or the temperature of the air in the air curtain 4 can be reduced, for example. In case the temperature on the outside of opening 20 of the measured profile 32 is below the reference temperature profile 34 the outside conditions appear to affect the quality of air curtain 4 and leakage and energy losses may increase. In this case, for example, controller 44 may adjust air curtain 4 by manipulating the fan speed, heater and/or flow direction of outflow 8 to enhance the quality of air curtain 4.

The present invention is by no means limited to the above described preferred embodiment thereof. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged. Air curtain device 2 can thus be applied to many locations. Examples hereof are for instance entrances to shops, loading and/or unloading positions, warehouses or logistical centers, and climate-controlled spaces.