The present invention relates to an air curtain device for realizing an air curtain. The invention more particularly relates to an air curtain with a substantially horizontal airflow. Such an air curtain device is usually provided in or close to an opening, in particular a door opening.

Known air curtain devices are usually horizontally placed devices which in use realize an air curtain flowing in vertical direction. These known devices require an installation space at the top and/or bottom of the opening where an air curtain has to be realized. Since sufficient space for installation is not always available, air curtains are also known which are provided on a side of the opening. During use these air curtain devices disposed in vertical direction realize an air curtain flowing in horizontal direction. These air curtains are found to be inefficient in practice, resulting in a relatively high energy consumption. In addition, use has to be made of relatively strong airflows in order to realize an air curtain, whereby the comfort for persons passing through the air curtain is not optimal either.

The present invention has for its object to provide an air curtain device for realizing a horizontal air curtain which realizes such an air curtain in a more efficient manner and wholly or partially obviates the above stated drawbacks.

The present invention provides for this purpose an air curtain device for realizing a horizontal air curtain, the air curtain device comprising:

- a housing with air displacing means ;

- at least one air inlet for supplying air to the housing; - a first outflow opening for realizing the horizontal air curtain in a first direction; and

- a second outflow opening for realizing an additional airflow in a second direction during use, wherein the air curtain and the additional airflow are provided at an angle to each other .

The air curtain device according to the invention comprises a housing with air displacing means therein, 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 in use, although the air inlet can also be provided at other positions at which the air is transported to the desired position. If desired, a plurality of air inlets can also be provided.

The device realizes the air curtain flowing substantially in a horizontal direction using a first outflow opening or first series of outflow openings. This outflow opening or series of outflow openings extends substantially in a vertical direction, usually over substantially the same height as the opening in which an air curtain is provided. An air curtain is provided in or close to an opening in a wall, wherein the opening is usually a door opening, for instance the entrance to a shop or storage space. The air curtain device according to the invention is further provided with a second outflow opening or a second series of outflow openings for realizing an additional airflow during use. This additional airflow is provided at an angle to the actual air curtain realized in the opening during use. Providing the two airflows at an angle also means in respect of the air curtain device according to the invention that the two airflows also extend over a substantially corresponding height. The effective height of the two airflows is therefore preferably substantially the same in the vertical direction.

Vertically placed air curtain devices are in practice usually placed in front of the wall at some distance therefrom, adjacently of the opening, so as not to make the opening or passageway smaller. In use the air curtain extends substantially in or parallel to the opening in the wall. This results in practice in leakage loss between the air curtain device and the wall, since the air curtain device is not provided in the opening itself. By providing the additional airflow, which is oriented during use at least partially toward the wall, a screening is brought about between the device and the wall. The two airflows are preferably provided over the height of the whole opening. This achieves that the entry of outside air and/or leakage of usually conditioned inside air is reduced. An additional advantage of providing an additional airflow is that disruptions of the air curtain are prevented.

The angle between the wall and/or the air curtain on the one hand and the additional airflow on the other during use preferably lies in the range of 60D-120D, more preferably

75D-105D, and this angle most preferably amounts to about 900. The additional airflow is preferably oriented here toward the wall. It has been found that an additional airflow with a component substantially perpendicularly of the direction of the wall realizes a good screening and reduces leakage losses. This means that particularly an angle of 75D-105D has been found extremely suitable. The perpendicular component of the additional airflow is preferably so large that the angle between the additional airflow and the wall amounts to about 90D. The least disruption of the air curtain occurs here, and the occurrence of leakage losses is simultaneously reduced.

In an advantageous preferred embodiment according to the present invention the air curtain device comprises heating means for heating at least a part of the air.

A part or even all of the blown-out air for the purpose of the air curtain, and optionally also the additional airflow, can be heated by providing heating means in the air curtain device. This increases the comfort for persons passing through the air curtain. In addition, the comfort of the interior space is increased by reducing losses. The heating means preferably heat the air over at least part of the height of the opening in which the air curtain is provided during use. The energy required for the heating can remain limited by heating only a part of the air curtain, and thereby only a part of the total amount of air for the air curtain. The first part of the height preferably amounts to about 2 to 2.5 metres . By providing warm air over a first part of the height the greatest possible comfort is realized for persons passing through the air curtain. The first part of the height is preferably located up to a height of 2-2.5 metres from the ground. It is however also possible not to heat a part of the air close to the ground, since this makes only a limited contribution toward the sense of comfort. It is thus possible for instance to heat only a height corresponding to the height of the torso and head of persons passing through the air curtain.

It is a further possibility to provide a plurality of heated parts in vertical direction of the air curtain so that for instance cold and heated air curtain parts are alternately provided. Relatively cold air is preferably provided at the top of the air curtain in order to thereby limit the loss of warm air . This is preferably a height above 2 to 2.5 metres since this does not detract, or only minimally, from the comfort.

In an advantageous preferred embodiment according to the present invention the air curtain device comprises a speed control for adjusting a flow speed over the height of the air curtain and/or of the first and second outflow opening.

Providing a speed control achieves that the speed of an airflow in the air curtain, and if desired also in the additional airflow, can be adjusted, for instance subject to the dimensions of the opening and/or the distance between the device, particularly the outflow openings, and the wall. In addition to adjusting a single air speed over the whole height of the air curtain, it is also possible according to the invention to apply a variation in speed over the height of an air curtain. The comfort can hereby be further enhanced. In addition, the efficiency of the device is hereby increased. Using the speed control a lower speed of the air can for instance be set at a height corresponding to the head height of persons passing through the air curtain. The comfort of these persons is hereby enhanced. By varying the speed of the airflow over the height of the air curtain it is further possible to influence the play of forces such that energy losses are further limited. In addition or alternatively, the amount of air can be distributed over the substantially horizontal air curtain and the additional airflow using the speed control. This distribution preferably depends on specific conditions, such as for instance the prevailing wind direction.

In a further advantageous preferred embodiment according to the present invention an outflow opening is provided on either side of the air curtain.

Providing an outflow opening or series of outflow openings on both sides of the air curtain, in practice therefore on both sides of the opening at which the air curtain is provided during use, achieves that a good air curtain is realized over the whole width of the opening.

In a further advantageous preferred embodiment according to the present invention the air curtain device comprises adjusting means for blowing out air differently from the outflow openings on either side of the air curtain during use.

The length of the airflow from the two outflow openings or series of outflow openings can be adjusted by providing the adjusting means. This achieves that the location where these two airflows come into mutual contact can be realized at a desired position. This means for instance that the airflows do not come into contact with each other in the centre, but more to a side of the opening. This further increases comfort. In addition, the prevailing wind direction can hereby be taken into account such that the disruptive influence thereof is minimized.

In a further advantageous preferred embodiment according to the present invention the air curtain device comprises control means for controlling adjusting means and/or speed control on the basis of ambient conditions.

Controlling the adjusting means and/or speed control on the basis of ambient conditions achieves that the air curtain can be adapted to the prevailing conditions in the immediate vicinity thereof. In the case an air curtain is provided at an opening to the outside, the ambient conditions are for instance temperature differences, wind speeds and/or wind directions. This avoids inter alia the air curtain having to be

over-dimensioned. The use of energy is hereby brought into line with the actual need. The comfort is also increased here. A more efficient air curtain is hereby obtained.

The invention further also relates to a method for realizing an air curtain with an air curtain device as described above.

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

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:

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

- figure 2 shows an alternative embodiment of the air curtain device according to the invention;

- figure 3 shows a further alternative embodiment of the air curtain device according to the invention,-

- figure 4 shows a top view of an air curtain device as according to figure 2; and

- figure 5 shows a view of a velocity profile obtained in an opening without an air curtain.

An air curtain device 2 (figure 1) is provided in the vicinity of an opening 4 in a wall 6. Device 2 comprises a first upright 8 provided with a lower part 10 and an upper part 12. A second upright 14 is placed on the other side of opening 4 close to opening 4, wherein upright 14 consists of a lower part 16 and an upper part 18. Lower parts 10, 16 and upper parts 12, 18 are provided at a small angle to each other, for instance in order to prevent torsion of air curtain 22. Uprights 8, 14 are provided with a series of outflow openings 20 with which air is blown out in order to realize an air curtain 22 in opening 4. In a direction toward wall 6 uprights 8, 14 are provided with second outflow openings 23 to enable a secondary airflow 24 to be realized for the purpose of preventing leakage losses.

An alternative air curtain device 26 (figure 2) consists of a first upright 28 and a second upright 30 placed on either side of an opening 4 in a wall 6. Air curtain 32 is realized by allowing air to flow out of outflow openings 20 at uprights 28, 30. Secondary airflows 34 directed toward wall 6 are realized from uprights 28, 30 with second airflow openings 33.

A further alternative air curtain device 36 (figure 3) consists of a upright 28 provided on a side of opening 4. Upright 28 is provided with a series of outflow openings 20 for realizing an air curtain. Upright 28 is further connected to a beam 38 in which are provided second outflow openings 40 from which air can be blown in order to realize secondary airflow 42. In this embodiment secondary airflow 42 is directed substantially vertically and therefore also makes a large angle with the air curtain close to opening 4. A screening can be realized without loss of installation space by positioning the beam 38 outside the immediate opening 4.

An air curtain 32 {figure 4) , as can for instance be realized in use with the alternative embodiment of air curtain device 26, is provided with two uprights 28, 30 on either side of an opening 4. The larger part of the air is used to realize air curtain 32. A smaller part of the air is used to realize the additional or secondary airflow 34. In the shown embodiment airflow 34 is provided at an angle of 90° relative to air curtain 32, and is directed toward wall 6.

The air can optionally be heated wholly or partially by providing air curtain device 2, 26, 36 with a heating spiral (not shown) . This particularly relates to the air of air curtain 22, 32.

A velocity profile 44 occurring in practice (figure 5) in an opening without an air curtain runs from ground surface 46 to upper edge 48 of an opening 4. Air from outside (on the left in figure 5) is thus carried inside (on the right in figure 5) for instance over a first height A, whereby the indoor climate is disrupted. Conversely, air will move from inside to outside in opposite direction over a height B of speed profile 44, whereby wholly or partially conditioned air of an indoor climate is carried outside, wherein energy is lost. The transition point of the flow direction depends for instance on the conditions prevailing inside and outside. Through the use of a speed control in an air curtain device it is therefore possible to keep the flow around the transition point to a minimum, since losses will here be minimal. In addition, it is efficient in the case of the shown opening to blow relatively cold air at the top of the air curtain without this detracting from the comfort. In addition, profile 44 shows that some torsion of air curtain 22, 32 may occur. This can be prevented by providing an air curtain device 2 as shown in figure 1, wherein uprights 8, 14 comprise in the height a plurality of parts which blow out air at an angle to each other.

In order to obtain air curtain 22, 32 an air curtain device 2, 26, 36 is provided, wherein during use air is blown out of first outflow openings 20 by activating the air displacing means, usually in the form of a number of fans. This results in an air curtain 22, 32. Air is likewise blown out of second outflow openings 40 during use in order to realize an additional airflow 24, 34, 42. Leakage losses are hereby reduced.

In the shown embodiments uprights 8, 14, 28, 30 are provided on either side of opening 4. It is also possible to suffice with a single upright 8, 28, depending for instance on the dimensions of opening 4. It is also possible to provide a number of uprights on the other side of opening 4. It is thus possible to provide four uprights on either side of the opening, and on both sides thereof, i.e. inside and outside. A part of the air displaced with air displacing means or fans can be used to realize an additional airflow 24, 34, 42. Alternatively, it is possible to provide separate air displacing means, for instance in the form of one or more fans, in order to obtain the additional airflow 24, 34, 42.

If desired, the air speeds can be controlled using a speed control. A velocity profile can hereby be obtained along the height of air curtain 22, 32. It is optionally possible also to control the air speed of the additional airflow 24, 32, 42. The speed control here for instance controls the rotation speed of a fan. It is also possible for instance to vary the air distribution over the outflow openings, or the outflow openings themselves. By measuring ambient conditions, preferably the wind direction and the wind speed, the amount of air required for air curtain 22, 32 can be adjusted thereto using control means. These control means for instance set the speed control and/or control adjusting means. In an embodiment in which a plurality of uprights 8, 14, 28, 30 are for instance provided, air can be distributed over the different uprights. The position where the airflows from either side of the opening come into contact with each other can hereby be adjusted for instance such that the wind direction has no or a minimal influence on air curtain 22, 32, 42.

The present invention is by no means limited to the above described preferred embodiments thereof . The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged. Air curtain device 2, 26, 36 can thus be applied at many locations. Examples hereof are for instance entrances to shops, loading and/or unloading positions at warehouses or logistical centres, and climate-controlled spaces .