WO2010085861A2

WO2010085861A2 - Blower unit device for generating an air wall for separating the air in two spaces

Info

Publication number: WO2010085861A2
Application number: PCT/BE2010/000006
Authority: WO
Inventors: Peter Julien Joseph Deweerdt; Ernest Jozef Elias Berben
Original assignee: Handelsmaatschappij Willy Deweerdt Bvba
Priority date: 2009-02-02
Filing date: 2010-02-02
Publication date: 2010-08-05
Also published as: EP2396602A2; NL2004182C2; WO2010085861A3; EP2396602B1

Abstract

The invention relates to a blower unit for generating an air wall for thermal separation of the air in a first relatively cold space from the air in a second relatively warm space, for instance the surrounding area, which spaces are mutually connected by a passage opening, the blower unit comprising: an elongate blower unit positioned on one side of the passage opening and comprising fan means and a blower slit for generating a flat air stream directed toward the opposite side of the passage opening. The unit has the special feature that the speed of the air in the air blower slit amounts to at least 15 m/s; the width of the blower slit lies in the range of 5-40 mm; the length of the blower slit in the direction of the air stream lies in the range of 5-100 cm; the cavity has a prismatic form; connecting to which cavity on one side is at least one air feed, extending substantially over the whole longitudinal dimension of the cavity, and on the other side the blower slit; in the upstream zone of which cavity an airflow resistance is present; and the zone of which cavity downstream of the airflow resistance has a form narrowing in the flow direction.

Description

BLOWER UNIT DEVICE FOR GENERATING AN AIR WALL FOR SEPARATING THE AIR IN TWO SPACES

The invention relates to a blower device for generating an air wall for thermal separation of the air in a first relatively- cold space from the air in a second relatively warm space, for instance the surrounding area, which spaces are mutually- connected by a passage opening, the blower unit comprising: an elongate blower unit positioned on one side of the passage opening and having a longitudinal direction and comprising: fan means and a blower slit which connects thereto on the blower side, is disposed substantially parallel to the main plane of the passage opening and extends over substantially the whole relevant dimension of the passage opening for the purpose of generating an at least more or less flat air stream directed at least roughly toward the opposite side of the passage opening.

This known blower unit comprises a single pressure system, wherein the direction of the exiting air stream with a high dynamic pressure lies more or less perpendicularly of the axis of the housing of the blower unit and wherein a single air feed is arranged, usually parallel to the above axis and embodied in round, square or polygonal cross-sectional form.

Such a blower unit is often embodied such that people and small vehicles and auxiliary vehicles such as fork-lift trucks are able to pass through. For this purpose the blower slit can for instance be positioned on one side of a usually rectangular passage opening. Also known is the use of a blower slit which connects to the upper edge of the opening. People and vehicles can then also pass through. A blower device of the type stated in the preamble is the known example in practice, in which an air stream more or less at right angles to the axis of the cavity with air outflow slit can only be obtained by arranging transverse connecting plates with mounting in said slit. This has the consequence that in the longitudinal direction at each connecting plate (at least one per 8 to 10 cm) the parabolic velocity profile, characteristic of a laminar airflow, also provides for an irregular air stream inside the air wall, thereby enhancing divergence of the air stream in this air wall. A double formed parabolic velocity profile is thus created.

Attachment points with rounded head are also arranged in the known example for attaching said connecting plates, this likewise resulting in divergence of the air stream in the air wall. The surfaces forming the air outflow slit are usually also made too short , whereby not only does the asymmetrical embodiment of the air distributing box provide a slightly bending air wall relative to the axis inside the air outflow slit, but the turbulent character of this air stream is also insufficiently converted to laminar airflow, thereby creating a significant cause of divergence. Obtained here in the air distributing box is the influence, on the one hand of the dynamic pressure, at the beginning strong and subsequently decreasing, and on the other hand the uniform static pressure over the whole length of the air distributing box. The air stream coming from this air distributing box therefore has variations from the desired profile .

A blower device of the type stated in the preamble is for instance known from DE-A-102 07 103. In addition to the stated drawbacks, this blower device also has an additional drawback, i.e. the presence of a control valve at the end of the air outflow slit, which will enhance the turbulence in the air wall if it does not lie in the line of the surfaces forming the air outflow slit. Another blower device of the type stated in the preamble is known from US-A-6431 978, wherein diverse connecting plates in the short slit surfaces, just as the short slit surfaces themselves, will cause divergence and unevenness of the air stream in the air wall . All the above stated blower devices belong to the type with the single-stage pressure systems, wherein the air outflow slit, optionally provided with transverse connecting plates, forms the only built-in air resistance of the blower unit. The invention provides a blower device of the stated type, wherein the speed of the air in the air blower slit amounts to at least 15 m/s; the width of the blower slit lies in the range of 5-40 mm; the length of the blower slit in the direction of the air stream lies in the range of 5-100 cm, preferably 5-40 cm, more preferably 10-30 cm; the cavity has an at least more or less prismatic form, i.e. has the same cross-sectional form at any longitudinal position; connecting to which cavity on one side is at least one air feed, extending substantially over the whole longitudinal dimension of the cavity, and on the other side the blower slit; which blower slit is bounded by two smooth, mutually parallel surfaces ; in the upstream zone of which cavity an airflow resistance is present; the zone of which cavity downstream of the airflow resistance has a form narrowing in the flow direction,- and which air feed slit and which air blower slit together define an airflow pattern with a main airflow direction in the cavity, this pattern being substantially the same at any longitudinal position of the downstream part of the cavity, and the airflow speed in this downstream part is everywhere directed toward the inlet of the blower slit. As a result of these measures the turbulence of the air stream flowing out of the outflow slit is greatly reduced, so that the air stream is affected considerably less by factors reducing the smoothness of the main flow and forms a better separation between the two spaces . Inexpensive and reliable is an embodiment in which the blower unit has the special feature that the airflow resistance comprises an at least more or less plate-like element with a regular pattern of openings, for instance a gauze, a perforated plate or the like, the throughflow area of which amounts to about 0.1 - 0.6 times, preferably about 0.3 times, the relevant area of the plate-like element, and the linear dimensions of the openings lie in the range of about 1-15 mm. The openings can have any suitable random form. According to another aspect of the invention, the blower device has the special feature that the blower fan means connect via a feed space to the at least one air feed.

According to yet another aspect of the invention, the blower device has the special feature that the airflow resistance lies at a distance from the at least one air feed of about 0.2 - 0.4 times, preferably about 0.30 - 0.35 times, the overall distance between the least one air feed and the inlet of the blower slit.

An adjustable device is obtained with an embodiment in which the passage of the at least one air feed is adjustable. In order to prevent vortices and turbulences, which can cause pressure drop and energy losses and can moreover cause hissing or whistling sounds, the blower device can advantageously have the special feature that the transitions of the inner surfaces of the cavity to the inner surfaces of the blower slit have smooth, rounded forms.

In the case where it must be possible to choose the direction of the air wall, for instance in order to optimize the operation of the air wall, the blower device can advantageously have the special feature that at least the blower slit is pivotable around a pivot zone roughly parallel to the longitudinal direction of the blower unit .

The uniformity of the exiting air stream over the length of the outflow opening is improved when the feed duct has a prismatic form, i.e. has the same cross-sectional form at any longitudinal position. The device becomes more compact, so that within the given structural preconditions the passage opening can be given a larger form when the blower slit extends at least partially- inside the feed duct. The blower device can further be provided with a feed duct with a cross-section formed from a regular or irregular triangle, a square, a rectangle or irregular forms hereof, an oval, a circle, intermediate forms including asymmetrical forms, and wherein the space between the above stated control valve and the feed duct is sufficient, even in the case of asymmetrical air feed, to obtain a good air feed over both sides of said control valve; a direction control of the air wall, provisions necessary for a horizontal or vertical arrangement.

Although diverse configurations are possible for connection between the feed duct and the blower slit, it is recommended that the blower slit is closed on its side remote from the blower opening by a panel extending transversely of the outflow direction and extending at a distance from the widest part of the blower slit. This configuration makes it possible to carry the air symmetrically into the blower slit. A system is hereby also obtained in simple manner which has a multiple resistance. In order to enable proper control of the quantity of air exiting the blower slit, it is recommended that the panel is movable substantially parallel to itself in the outflow direction.

It is also attractive that a perforated connecting plate extends substantially transversely of the outflow direction between the walls of the blower slit and that the connecting plate is connected to at least one of the two walls. The openings can be arranged in this connecting plate by for instance drilling, punching or working with a piercing element. A gauze can consist of a plastic such as nylon, a metal such as stainless steel, or the like. Stainless sheet steel is considered highly suitable. This plate can comprise a regular pattern of openings, such as a gauze or a perforated plate, the throughflow area of which amounts to about 0.1 - 0.6 times, preferably 0.3 times the area of the plate-like element, and the linear dimensions of the openings lie between 1 and 15 mm.

The airflow resistance preferably lies at a distance from the at least one air feed of about 0.2 - 0.4 times, preferably about 0.30 - 0.35 times the overall distance between the at least one air feed and the inlet of the blower slit.

The above described device is of the type with multi-stage pressure systems. That is, the overall air resistance of the blower unit is made up of multiple air resistances such as those of the outflow slit, with as variables: the distance between the plates and the length of the slit, the position of a perforated plate received in the blower slit and a control valve in the form of a flat U-profile. The advantages of said multiple pressure system are: a compact construction; a smooth air wall; an adjustable air wall; a uniform forming of the air wall over the blower length; an air wall in which the axis of the air stream, without variation, is at right angles to the axis in the length of the core of the blower unit, and a single parabolic velocity profile in the length of the outflow slit.

In order to make the throughflow area of the blower device adjustable, in addition to the option already mentioned above of the adjustment by means of the panel extending transversely of the outflow direction, there is also the possibility that at least one of the walls of the blower slit is movable in the direction transversely of the blow-in direction.

In order to obtain a smooth flow without the danger of disruption, which could cause vortices or turbulence, the transitions between the inner surfaces of the cavity and the inner surfaces of the blower slit preferably have smooth, rounded forms .

In order to simplify the construction the movable wall of the blower slit is preferably suspended from at least three arms extending substantially parallel to the wall, and the movable wall is coupled to an adjusting mechanism provided with levers. For the adjustment of the flat plates a distinction is made between the fixed surface, which serves as basis of said frame and the adjustable part, embodied in light sheet metal and provided at the top and bottom with a seal of rubber, PVC or the like. The adjustable plate is as it were made weightless using four suspension rods so as to remain easily slidable on the contact surfaces .

In the light of for instance the locally dominant wind conditions, the blower device can have the feature that the blower slit is placed for tilting in its length direction in the feed duct. This blower device is also suitable to longer withstand the air pressure with little airflow caused by gusts of wind at frontal door openings adjacent to the outside weather conditions and which temporarily increase the lateral air pressure on the air wall. It is not always possible to have an air wall operate at^' a maximum airflow rate between the gusts of wind because of the nuisance caused by noise and draught.

When an approaching gust of wind is detected, it is now possible to immediately widen the surfaces of the air stream. If at the same moment a bypass valve over the fan is closed, this fan already operating at maximum rotation speed, it is now possible to immediately press more air through the widened surfaces of the air stream slit, whereby the air wall can provide more resistance to the lateral air pressure. The pressure from the gust of wind will press the air wall inward to some extent. An undesired airflow will hereby flush through the space protected with an air wall, resulting in a reduced sense of comfort. By now also orienting the air wall from 5° to 30° outward immediately the approaching gust of wind is detected, the consequences of this overpressure can be limited.

It is also important that the space in which this door opening is arranged does not have on its other side any openings which are also connected in one way or another to the surrounding area.

Envisaged here are air installations, optionally combined with heating and other air-conditioning, which are generally equipped with ventilation. In such a case this blower unit must also be provided with closing valves and associated control. Since closure in the case of gusts of wind is temporary, this has no further effect on the proper operation of air installations with the associated above stated blower units.

Between the gusts of wind the bypass valve must be opened over the fan at maximum operation. In contrast to closing of the bypass valve, which must take place in a fraction of a second, re-opening of the valve may take somewhat longer. The same also applies for once again narrowing the surfaces of the air stream, and for resetting the air wall in the original direction. Not all weather conditions with gusts of wind are the same. Nor is the angle of incidence on the door opening with air wall always the same. Measurement of all these weather conditions is possible. These measurement data can control the above stated elements via an automatic system subject to necessity and intensity.

The above stated blower unit can also be embodied with an automatic control for diverse weather conditions and more constant wind conditions which can nevertheless differ from each other. In such a case the blower unit of the ventilation must be adapted thereto, for instance by placing the air feed and discharge thereof in the same plane as the applied air wall. In the case of a blower unit with control as mentioned above, it may be necessary to equip the door opening with two or more air walls, which are then adjusted subject to necessity and the overpressure. The two air walls can lie on the same axis or on two mutually adjacent axes. The two air walls can also lie opposite one another and form an angle to each other directed toward the outside of the building.

A space-saving solution provides the measure that the feed duct has a substantially triangular form.

The blower device is also suitable for installation above a false ceiling. The air wall is then formed by an air stream flowing from top to bottom. The visible space in the false ceiling is only several millimetres wider than the outflow slit.

Forms other than a triangle are possible, provided a small part of the outflow slit is arranged outside the housing, whereby it debouches just on the underside of the false ceiling. It is precisely because a core of the blower unit is built into this housing that it is possible to arrange one or more air feeds on all sides of the housing. It is thus also possible to construct the fan against the housing, thereby creating a compact construction.

Because this blower device has a prismatically formed part above the air outflow slit, this prismatically formed space can be used to accommodate heating resistors or heat exchangers with CH water in order to heat the air stream of the air wall. In these blower devices the air can move downward, but also upward with a blower unit on the underside of the passage.

Heat exchangers with ice water can also be applied, preferably with an upward directed air stream with a view to discharge of condensed water. In order to increase the symmetry it is recommended that the device comprises two fans connected on either side of the feed duct.

Such a blower unit can also be provided with a symmetrically arranged air separation from above the beginning of the air outflow slit and further in a straight line (vertically) to the casing thereabove. Two fans can thus be connected, the one fan of which draws in the air to the left of the blower unit and the other of which draws in the air to the right of the blower unit . The air to the left may have a temperature and absolute humidity differing from the air on the right. The air stream is not mixed in the outflow slit and the air wall, whereby an air stream in the air wall is created with two mutually differing temperatures and humidities. Close to the floor the air on the left will move again to the left, and the same on the right. These measures will contribute toward even fewer heat and moisture losses than with the use of an air wall with only one fan.

A blower device which serves to produce a secondary air stream over the primary air wall can be provided with a housing or casing with the core of a blower device, both embodied in accordance with the above stated description, into which a second blower device in a low-pressure embodiment is fixedly arranged. The whole casing can here be adjustable in order to simultaneously control the direction of the air streams. It is however also possible to apply an individually directable core of a blower device which is assembled together with a second fixedly built-in blower device in one casing. All these variants can likewise be applied in the case of an embodiment with one primary air stream having a low-pressure secondary air stream on both sides. The walls are optionally insulated in accordance with the difference in temperature over the surfaces of the air-guiding parts.

A blower device can be embodied in two ways: firstly with the core of the blower unit attached fixedly in the housing, wherein a flexible connection is present between the casing and the air feed ducts to enable adjustment of the direction of the air wall; and another option is to uncouple both during the adjustment and to re-couple them following adjustment. This involves an auxiliary blower slit which is placed adjacently of the blower slit and connected to an auxiliary fan. A second method consists of arranging above and below the air stream outlet a shaft or spindle which is connected to said frame, whereby the core of the blower unit is independently rotatable through an angle of about 40° . This assumes that sealing means such as strips or rubber/PVC profiles are arranged on the moving contact surfaces at the axis of the spindles in order to prevent air losses in the housing at any position or angle of the core of the blower unit .

In the air outflow slit of the prior art single-stage pressure devices not only are connecting plates placed in order to blow the air stream straight out to some extent, these also serve for the form-retaining embodiment of the plate construction of the whole housing. In order to also obtain a form-retaining blower unit in the device according to the invention, the components of the core of the blower unit are assembled on an external form-retaining frame embodied and assembled from profile or in plate with folds in the metal for strengthening purposes .

The adjusting screw is situated on the surface of the above stated perforated plate. This adjusting screw can for instance be reached with a long screwdriver. The adjusting screw can be reached between the two surfaces of the outflow slit. Because the core of the blower unit can change direction, it is found that the above mentioned point can always be reached without internal disruption. A supplementary passage is therefore not necessary in the housing, thereby preventing air leakages.

The movement of the adjusting screw is transmitted to the flat adjusting plate via a threaded rod mounted in the frame and a mechanical transmission. When the adjustment must be controlled at distance, a drive, for instance with a servomotor, must be added thereto which, for instance by means of an eccentric and a spring release, can provide for an immediate adjustment. This preferred embodiment provides a blower device of the above described type, wherein the movable walls are connected to an electric motor by means of a belt drivable by the electric motor and at least one lever.

The control of the valve formed from a flat U-profile of the core of the blower unit likewise takes place via an adjusting screw. This adjusting screw is situated on the surface of the above mentioned perforated plate and is connected to a threaded rod, held in the frame and with mechanical transmission in order to obtain a parallel adjustment of the valve opening on two sides along the whole length. The same screwdriver as mentioned above can be used for adjustment purposes. The adjustment of the blower device takes place with a threaded rod which connects the core of the blower device to an opening in the housing. The position of at least the electric motor, the bearing of the drivable belt or the lever is preferably adjustable by means of a threaded rod which can be operated with a screwdriver.

In the case the adjustment must be controlled at distance a servomotor must be used which, with an eccentric and a spring release, can provide for the immediate adjustment. The housing with the blower device must develop an air wall which begins at the floor and ends against the false ceiling of the blower unit of the air wall, or vice versa. This also entails the blower slit also having to begin at the floor and end at the false ceiling. In order to make this possible the support of the housing must remain as close as possible to the floor. Not all floors are completely flat; the support must therefore be embodied such that a vertical adjustment in all directions is possible and that the usable height under the air blower slit remains < 1.5 cm. Used for this purpose is a metal plate on which the casing can be mounted. Around this metal plate with upright folds on both sides is placed a frame with options for fixing to the floor in addition to adjusting screws for small height adjustment and fixing.

An aspect of the invention relates to the ventilation means. These ventilation means must supply sufficient static pressure to overcome the losses in feed conduits and bends and in the blower unit. The dynamic pressure must also be sufficient to still have thrust after passing through said air circuit to close the width of the door opening with an air wall. Another aspect of the invention relates to the reuse of the air stream produced in the air wall. This air stream is preferably reused because it has a temperature and humidity which, on the temperature and humidity scale, lies roughly halfway between the two temperatures and humidities measured over the air wall as separation. This enhances the proper operation of the air wall as separation.

This also reduces the formation of fine ice crystals, at least over the width of the door opening. However, the formation of ice crystals cannot be wholly prevented. There are still at least two situations in which icing can occur.

In a first situation the air layers do indeed arrive substantially separated at the suction unit and, at the position of the rectangular suction unit, they all collide externally against the same wall of the suction unit. At this position the previously separated airflows and layers of different temperature and humidity are nevertheless mixed, wherein fine ice crystals can then occur. These ice crystals are then drawn in by the suction unit and deposit internally on the metal outer walls of the whole installation. This is caused in that the temperature of the indrawn air in the case of an air wall in the door opening of a cold storage space is higher in said system than the external temperature of the metal outer walls, whereby the ice crystals are deposited on the inner side of these metal walls, with the result that they there form a layer which after a time will obstruct the further disturbance-free operation of the device. It is sufficient to insulate the outer walls of the air wall device in accordance with the anticipated difference in temperature so that icing is prevented. A second situation is the formation of fine ice crystals on the suction grid and all other grids and filters which may be present in the device. This icing is a result of turbulence, wherein unmixed small air volumes or parts move successively in front of and through the grid. The first air part can be cold and dry, wherein the grid decreases in temperature, and a second part at the same location on the grid can be warmer and more humid. The second air part can form and deposit ice crystals here, with the result that the grid can become clogged and eventually impede proper operation. Whether and how this ice deposition takes place depends on the temperature the grid can maintain during operation and the frequency of the temperature and humidity changes.

According to the invention the separated air layers are kept separated as far as possible to a point beyond the suction grid. It will be apparent that rectangular suction units with frontal surfaces cannot be used for this purpose. Suction units taking a triangular form, and equipped with a suction grid beginning roughly at the point of the triangle and ending roughly at the halfway point of this surface or before, can separate the secondary air streams to the left and right of the optionally combined primary air stream. These secondary air streams will certainly become turbulent if they collide with a wall, although this does not affect the quality of the air at said suction grid. Situated between the two said secondary air streams is the optionally combined primary air stream which is discharged via said suction grid for reuse in the air wall installation.

The triangular suction unit can be embodied in different ways. A first embodiment is that of the isosceles triangle, although right-angled triangles to the left and right, with all scalene triangles therebetween, are possible. Triangles can also be connected at the base to a rectangle in order to enable fitting into determined insertion, and variants thereof. To this end a further preferred embodiment provides an air extraction unit placed upstream of the fan and comprising a prismatic discharge duct with a cross-section having an acute angle, wherein the acute angle is turned toward the direction from which the air for extraction is supplied, and that a feed opening is arranged in a wall adjacent to the acute edge.

The direction of the primary air stream in the air wall determines the temperature and humidity in this generated air wall. If the primary air stream is directed slightly inward, i.e. to the side of the cold store, the temperature of this air stream will then rise because more air is then drawn from the warmest secondary air stream. More moisture from outside can in this way enter the cold store. If the primary air stream is directed slightly outward away from the side of the cold store, the temperature of this air stream will then fall because more air is then drawn from the colder secondary air stream. It is the intention to direct the primary air stream of the air wall as accurately as possible toward the triangular suction unit, assisted here by a vane at the point of the triangular suction unit which is adjustable. This vane can take an integrally straight or twisted form. This twisted vane then takes into account the difference in pressure which is characteristic of the differences in quality of the bounded air volumes and which occurs at the top and bottom of the door opening of a cold store . This twisted vane can also be embodied in a plurality of straight pieces which can be oriented gradually one below another, more or less corresponding to said twisted vane. A preferred embodiment therefore provides the measure that a panel extending in lengthwise direction and connected tiltably to the discharge duct is placed on the acute edge of the duct.

The primary air stream of the optionally composite air wall must be drawn in uniformly over the height of the suction unit, knowing that internally the air in the suction unit is discharged at the top. In order to enhance uniform suction the suction grid will have to take an adjustable form such that a narrowing is created at the top with a greater pressure difference than at the bottom, where the maximum opening remains in place at lower pressure difference. Such a grid can be manufactured by laying onto each other two identical perforated plates with an air passage of between 15 and 60%, preferably 30%. The perforations can be round, although other shapes are also possible provided the intended purpose is achieved. If the perforations are open to the maximum at all locations in this grid, the maximum chosen air passage is then obtained. Sliding the one perforated plate relative to the other perforated plate creates a uniform narrowing over the whole surface of the plates lying on each other. In this embodiment it is also possible to slide said perforated plates relative to each other more at the top than elsewhere. The embodiment as described above is in this way obtained. In this embodiment the plates must lie in suctioning manner on each other.

This air wall with the described blower unit and suction unit can also be placed successively, in opposite direction in each case, and further air walls can be added thereto to the extent the difference in temperature and humidity makes this necessary. An additional consequence of the use of a plurality of air walls in a door opening is that the difference in temperature and humidity will decrease when compared to the use of only one air wall. The transverse pressure on the air wall at the top and bottom will hereby also decrease, thereby at least partially eliminating a source of heat and moisture losses.

The above stated embodiment will ensure that icing is limited to a minimum. Icing cannot however be wholly prevented in extreme conditions of the available air quality. Ice is deposited in the form of crystals adhering to surfaces and objects. Upon contact these ice crystals are released in the form of ice dust. This aspect of the invention consists of releasing these ice crystals from the grid in a direction opposite to the indrawn airflow using a strong airflow or air pulse and blowing them away to the space outside the internal air wall installation. A preferred embodiment therefore relates to a blower unit wherein a compressed air device is present in the discharge duct which is adapted to guide a compressed air flow to the feed opening.

Serving for this purpose is a mini-cavity with blower slit fed by air at compressor pressure which can automatically move upward and downward at set times with cogwheels, drive motor with worm wheel transmission and a guide chain system. So as not to obtain any suction airflow in the vicinity of this counterflow under pressure, which would a draw in the ice crystals, plates are provided and fixed above and below the blower slit of the mini-cavity at a height of 5 to 30 cm, which are also disposed behind the above-mentioned grid. In this suction airflow-free zone which is then created the secondary air stream will ensure these ice crystals are entrained to the rear, where in a large accumulation they remain visible and accessible for discharge in simple manner. According to another preferred embodiment, the discharge duct is located in the side of the passage opening opposite the other parts of the blower unit.

The invention will now be elucidated with reference to the accompanying drawings of a number of different exemplary embodiments and partial aspects according to the invention, to which the invention is not limited. In the drawings: figure 1 shows a schematic section of the core of the blower device; figure 2 shows a schematic section of the blower device with an asymmetrical casing; figure 3 shows a schematic section of the blower device with a form-retaining frame in profile and an adjustment of the air direction in the air wall; figure 4 shows a schematic section of the side view of the blower device of figure 3, with a view of the form-retaining frame ; figure 5A shows a schematic section of the blower device embodied with a triangular casing as plate frame, with a fan at one of the outer ends of the casing; figure 5B shows a view corresponding to figure 5A, with a part of the blower device embodied with a triangular casing as plate frame with a fan on one of the outer ends of the casing; figure 5C shows a view corresponding to figures 5A and 5B of an upright blower unit; figure 6 is a side view of the blower device of figure 5; figure 7 shows a schematic section of the core of the blower device provided with heat exchangers; figure 8 shows a schematic section of a blower device equipped with a vertical air separation; figure 9 shows a schematic section of the core of a blower device for the primary air stream, assembled with a blower device at low pressure for the secondary air stream; figure 10 shows an outline of the parallel suspension of the adjustable flat plate of the core of the blower device; figure 11 shows an outline of the fine adjustment of the adjustable flat plate of the core of the blower device; figures 12A, B and C show outlines of the fine adjustment of the control valve for the double air feed of the core of the blower device ; figures 13A, B and C show sections of the blower device connected to the casing; figure 14 shows a combination of figures 10 and 11; figures 15A, B and C show outlines of a spring-loaded control for gusts of wind, and an electrical schematic diagram therefor; figure 16 shows a schematic section of an air extraction unit with the primary and secondary air streams; figure 17 shows a schematic section wherein the primary air stream is directed such that humid air can enter the cold store,- figure 18 shows a schematic section wherein the primary air wall is directed such that it can become colder and drier relative to the outside temperature and humidity; figure 19 shows a schematic section wherein all air streams are pressed outward at the bottom; figure 20 shows a schematic section wherein all air streams are pressed inward at the top; figure 21 is a top view of a compressed air blower unit for blowing fine ice crystals out of a grid; figure 22 shows a schematic section of an air suction unit; figure 23 is a side view of an air suction unit; figure 24A shows the known air streams occurring after opening of a door between two spaces at respectively +5⁰C and -20⁰C; figure 24B shows the same situation as in figure 24A, although an attempt is made here to limit the air losses by means of air wall 19; figure 24C shows a double air wall; figure 25 shows a cold store with an air wall device; figure 26 shows a blower device.

Figure 1 shows a schematic section of the core of blower device 1 assembled from two flat plates 2,2' with length 4 and adjustable in width as according to 12, with means 10 which provide for a parallel position of flat plates 2,2' at all widths 12, and fixed opening 17. Reference numeral 18 relates to the arcuate profile arranged for maximum prevention of turbulence, with length 5, which connects to the prismatically formed surfaces 20 with a height between 5 and perforated plate 7 equal to 6. Perforated plate 7 is attached fixedly to the one formed prismatic plate 20 and fixed in corner fold 8. It is not attached in corner fold 9 in order to enable sliding or widening with means 10 to position 12.

Placed above said construction is a control valve 11 consisting of a flat U-profile with adjustment option 16 whereby airflows 13 and 13' can be controlled. This control valve 11 is adjusted along its whole length. It is thereby possible to control airflows 13 and 13 ' along the whole length, whereby the pressure in the space bounded by control valve 11 and perforated plate 7 is homogenized. In this way a uniform air stream 15 will also be pressed through perforated plate 7 with an air passage of about 10-60%. The air stream, which is still turbulent at 14, will become laminar after the passage through the two flat plates 2. The air stream leaves blower device 1 at 3 and then forms air wall 19.

Figure 2 shows a schematic section of the whole blower device 26 embodied with an asymmetrical casing 28. In this case air feed 24 can be seen on the right-hand side of casing 28. It is however also possible to select this air feed in accordance with numbers 21, 22, 23, as well as at the front or rear of blower device 26. Following the supplied airflow 24, it can then divide in the directions 29 and 30 in lengthwise direction between the core of blower device 1 and casing 28. Airflow 31 then passes over the core of blower device 1. The space 27 for this airflow 31 must be sufficiently large that the airflows can pass easily and uniformly through air passages 13 and 13 ' into the space between control valve 11 and perforated plate 7. Airflow 32 continues into the space between 1 and 28 on the left-hand side so that the airflow can everywhere be well distributed. Figure 3 shows a schematic section of a blower device 26, wherein the direction of the core of blower device 1 can be adjusted, with axes 40 and 40' as extreme divergence, or an angle of 10 to 40°. Flat plate 2 is the base plate on which form-retaining frame 41 is mounted. This frame is strengthened by the upright profiles 47 and 47' . In order to enable the rotation from 40 to 40' a spindle or shaft 42 is provided above and below the frame as rotation point.

Flat plate 2' is the adjustable plate which is mounted by control means 10 on the other side of form-retaining frame 41. The direction adjustment is performed with a rotating rod

43 which can be rotated with a screw 45 by means of a runner nut

44 and a double locking nut 46 of rotating rod 43 for the purpose of imparting the driving force. The adjusting means for valve 11 are found under 16, with mounting on frame 41. Figure 4 shows a schematic section of the side view of blower device 26 of figure 3, with a view of the form-retaining frame formed from the various parts 41 and 47. The air stream enters at position 24 and leaves blower device 26 as air wall at 3. The spindles, or the rotation axes of the core of blower device 42 are shown at the top and bottom. Shown here is a front view of the direction adjustment under numbers 43, 44 and 45. Figures 5A, 5B and 5C show schematic sections of a blower device 52 embodied with a triangular casing 50 which also serves as frame in sheet metal or other materials, to which a fan 51 is connected at one of the ends of casing 50.

Figures 5A and 5B show a fan 51, drawn behind casing 50. Casing 50 with fan 51 is suspended from ceiling 58 by means of fastening rods 56 with fastening points 57. Blower device 52 according to figure 5A can thus be arranged in false ceiling 54 such that only the edges, of a size of several millimetres, of the core of blower device 1 remain visible.

In the case of figures 5A and 5B the airflow 59 is drawn in along a grid 60 arranged in false ceiling 54. Airflow 59 is then fed through blower device 52, more precisely along respectively the left-hand side 53 and the right-hand side 55 of the core of blower device 1. This creates the respective feed airflows 13 and 13 ' which, after passing through the core of blower device 1, result in the blow-in air stream 3, and subsequently form air wall 19. Control valve 11 can be embodied here with a flat U-profile with adjusting means 16.

Figure 5B shows a blower device 52, wherein a part hereof protrudes below the false ceiling. It is hereby possible to partially build in this blower device 52, even in the case of a small distance between ceiling and false ceiling. It is possible in both figure 5A and figure 5B to place fan 51 at a distance from blower device 52 and to subsequently feed the air stream via one or more ducts to blower device 52. In a serially produced blower device 52 it is possible, on the basis of preliminary testing, to replace control valve 11 with adjusting means 16 by casing plate 61, which is then placed at the correct distance from the prismatically formed plates 20. Airflows 13 and 13' can hereby be correctly defined. Figure 5C is an upright embodiment with the same cross-section as that according to figures 5A and 5B. The secondary airflows (not shown in the figures) also pass herealong. The air feed is designated here with an arrow 22. Here too the control valve 11 with adjusting means 16 can coincide with casing plate 61. The airflows can then be supplied uniformly via an opening in the two sides 50, or at the top.

Figure 6 shows the side view of blower device 52 of figure 5. Also shown here is how airflow 59 passes through suction grid 62 to fan 51. The same airflow passes through blower device 52 and eventually forms air wall 19. This air circuit above the false ceiling will of course only be possible when the false ceiling and the ceiling are substantially airtight. A connecting duct 62 is provided between fan 51 and blower device 52. A vertical air distributor is provided in the middle of this connecting duct 62 so that the airflow from fan 51 is distributed uniformly over airflows 53 and 55 with the least possible air resistance.

Figure 7 shows a schematic section of the core of blower device 1 provided with a heat exchanger 85 above or below perforated plate 7. The heat exchanger is designated in this case with 86. It is possible to envisage both heat exchangers 85 and 86 being necessary to discharge or supply heat. If heat has to be supplied, this is possible by means of heat exchangers provided with fins and with tubes filled with hot water or with electrical resistors. In the case electrical resistors are used as heating, this can also be embodied with smooth tubes in which the resistors are placed. If heat has to be discharged, this is possible using ice water or using cooling means.

Airflows 13 and 13' flow over said heat exchangers. The airflow with changed air quality flows further through the core of blower unit 1 and thus arrives in air outlet 3.

Figure 8 shows a schematic section of a blower device 70 equipped with a vertical air separation 72 which is arranged symmetrically. Created in this way are two spaces 87 and 87' respectively to which the respective airflows coming from fans 71 and 71' are fed. From these spaces 87 and 87' two airflows 13 , 13 ' enter the core of blower unit 1. Without mixing in the core of blower unit 1 an air wall is formed with two air qualities, i.e. 19 and 19' . Secondary air layers 73 and 73' will also develop here, which in the area of the floor will result in two horizontal airflows 74 and 74' of differing air quality. This forced separation of air of differing qualities will contribute toward reduction of heat losses in the area of the air wall.

Figure 9 shows a schematic section of the core of blower device 1 for the primary air stream 19, assembled with a blower device 82 at low pressure for the secondary air stream 81. These parts are assembled in a casing 80. The walls of blower device 82 must be insulated if the heat loss over these walls is too great. In the shown embodiment one airflow 24 suitable for forming the primary air stream 19 for the air wall is fed to casing 80 via connection 25 and one airflow 83 suitable for the secondary air stream 81 at low pressure via connection 84.

A second blower device can also be provided on the other side of blower device 1 if this is desirable.

Figure 10 shows the an outline of the weightless suspension of the adjustable flat plate 2¹ (figure 1) of the core of blower device 1. In order to enable the fine adjustment of flat plate 2 ' it must slide substantially without friction between lower surface 93 and upper surface 93 ' . Flat plate 2 ' is therefore suspended from four rods 91 of 50 to 60 cm in length. Flat plate 2 ' can hereby move several millimetres to the left or to the right, with a total of 15 to 20 mm. Rods 91 are suspended from fixed points 92, for instance on form-retaining frame 41 (figure 3) . In the enlargement 94 is shown how, by means of a trailing sealing profile in rubber or PVC 95, the bottom and the top sides are made airtight at this sliding surface.

Figure 11 shows an outline of the fine adjustment 113 of adjustable flat plate 2' of the core of blower device 1. The adjustable flat plate has four slots 100, i.e. two on the front side and two on the rear side of flat plate 2 ' . Into this slot fits a shaft mounted on rod 114. Rod 114 is mounted pivotally as according to 101 on form-retaining frame 41. The movement 116 of rod 103 is now transmitted via a lever 104, a fixed point 101 and a pivot point 117 to respectively rod 102 and rod 114. Flat plate 2 ^■ will hereby be displaced in direction 105, or vice versa. Driving takes place with a screwdriver 111 which is long enough to find adjusting screw 110 between plates 2 and 2¹. This adjusting screw 110 is connected to threaded rod 108, which is blocked in 109 with two sets of two nuts screwed fixedly against each other. In this way the position of runner nut 106 is changed when adjusting screw 110 is rotated. The adjustment is finally- transmitted to flat plate 2¹ via lever 118 and fixed point 107. For the purpose of clarity of elucidation of the control system, the frame 41 is shown in section at the top of the drawing, and at the bottom the same frame 41 is shown in front view.

Figures 12A and 12B showed the fine adjustment of control valve 11 for the double air feeds 13 and 13 ' of the core of blower device 1. For the sake of clarity figure 12A shows the adjustment with adjusting screw 123 and figure 12B shows the transmission to control valve 11. As seen from top to bottom, in the case of a vertical embodiment of blower device 26 (figure 3) the adjustment according to figure 12B takes place first, then followed by the adjustment according to figure 12A so as to end, at sufficient distance, with the adjustment according to figure 12B.

Figure 12C shows the side view whereby the position of said adjusting means is clarified. This arrangement ensures that control valve 11 uniformly adjusts airflows 13 and 13' over the whole height of the core of blower device 1. For the sake of clarity in figure 12A the threaded rod 120 is not connected to valve 11. The fine adjustment is mounted on form-retaining frame 41.

In the adjustment according to figure 12A screwdriver 111 is used to rotate adjusting screw 123. Adjusting screw 123 is fixed firmly to threaded rod 120. Threaded rod 120 is blocked at 121 with two sets of two nuts screwed fixedly against each other. A runner nut 124 will now be able to move on threaded rod 120 when rotated forward or rearward. This adjusting movement can be transmitted via lever 128 onto a shaft 125, indicated here by an angle profile. The transmission from shaft 125 to control valve 11 can be seen in figure 12B. When shaft 125 rotates, it can then move the free-running threaded rod 126 via lever 128, provided this lever can be held at 122 between two sets of two nuts screwed fixedly against each other. Said shaft is connected at 129 to control valve 11. Provided it takes a dual form, valve 11 will control airflows 13 and 13' in uniform manner.

Figures 13A, 13B and 13C show a section of the end at air outlet 3 of the core of blower device 1. The one side of the blower slit is designated with 2. Wooden plates of "Betonplex^®" can be used for this purpose, although other materials are also possible provided they remain straight after fitting. The numerals 2¹ and 2" refer to aluminium plates, each of 2 mm thickness. Other materials can also be used for this purpose, provided the further described assembly remains possible. Squeezed between these two plates is a rubber or PVC sealing profile 138. A similar profile

131 can be found on the side 82 at the secondary air stream 81.

So as to seal in any position as according to 137, within a range of an adjustable angle of 30°, a foam rubber 133, a flat profile 132 as cover plate is provided with adjusting screws 134 for sealing purposes. This unit is supported by an L-profile, for instance of aluminium, with dimensions 40 mm x 20 mm x 3 mm.

Figure 13A shows the position to the extreme left, with slit width 130 of for instance 10 mm. In this position the slit can also be brought to a maximum width of for instance 22 mm.

Figure 13B shows the position to the extreme right, with slit width 130' of for instance 22 mm. In this position the slit can also be narrowed to for instance a minimum of 10 mm. The rotation point is indicated with 42. This rotation point lies on the same axis on the top side. The whole core of blower slit 1 rotates around rotation points 42. This is only one example of a construction.

Figure 13C shows a flexible seal with for instance a strip of sailcloth 136 clamped into two profiles 135. In this embodiment the slit remains closed at any position. This embodiment is also suitable for changing direction during operation.

Figure 14 shows an assembly of a flexible mounting of flat plate 2¹ as according to figure 10 and the adjustment thereof according to figure 11. Figure 14 has the purpose of making the operation clear. The indicated numerals and the elucidation can be found with reference to the relevant figures.

Rods 91 for supporting and suspending flat plate 2¹ have respective pivot points 150 and 151. Numeral 150 is the pivot point with a fixed connection to 92 and 41. Both points are parts on the frame. Numeral 151 is the pivot point mounted on the slidable flat plate 2'.

Figures 15A and 15B show an outline of a spring-loaded adjustment for immediate orienting of air wall 19 for the purpose of providing more resistance to a gust of wind.

Frame 148 carries a drive motor 14 for control which drives cogwheels 141 with chain 142. Ratchets 143 are arranged at regular distances on chain 142.

Figure 15A shows the position during normal operation. Motor 140 must now carry chain 142 somewhat further so that lever 145 is released by ratchet 143. Spring 152 will now carry the whole frame 41 to a maximal position so that air wall 19 can better withstand an incident gust of wind.

Components 26, 41, 42, 43, 44, 45 and 46 can be seen in figure 3.

Figure 15B shows the maximal position. A ratchet 143 with chain 142 driven by motor 140 is now about to reach the position of figure 15A again so as to be ready to withstand the following gust of wind. The setting of the main direction of air wall 19 at a determined angle can still take place by adjusting or rotating threaded rod 43 ' by means of adjusting screw 45. Through rotation of threaded rod 43 ' held in shaft bearings 147 the runner nut 146 coupled to frame 148 will be displaced on threaded rod 43'. Frame 41 will follow in proportional relation because it is coupled to rod 43 and attachment point 44, whereby the direction of the core of blower unit 1 and air wall 19 will be moved.

This embodiment with the spring-loaded adjustment can also be applied to adjust the distance between flat plates 2 and 2' of the core of blower device 1, as well as to adjust the bypass valve of the fan (not shown) .

Figure 15C shows an arrangement of an air wall 19 in a building 212. A gust or blast of wind 211 is indicated outside the building. Inside the building is an air-conditioning (not further defined) 209, wherein a quantity of fresh air is supplied via opening 203 and wherein the same quantity of used indoor air is discharged via an opening 210. An air pressure gauge 202 can detect a higher pressure resulting from a gust of wind 211 and convert this to an electric current, for instance through closing of a switch. This switch can be found in the schematic diagram of figure 15D for adjustment of the different elements, such as:

206 the adjustment of the direction of air wall 19;

207 the adjustment of the width of the core of blower slit 1; and

280 the adjustment of the bypass valve over the fan. The diagram of figure 15D shows the adjustment circuit at rest, this including the situation of figure 15A. A gust of wind 211 strikes the device. Switch 202 closes. A timer 201 hereby comes into operation and immediately closes three contacts 206, 207 and 208. The three motors 140 of the above stated elements are hereby started. The contacts of timer 201 remain closed until the final switch 203 under 206, 207 and 208 has taken over the further operation of the three motors. When the controls have reached the respective end positions, the respective contacts 203 switch off and the control is once again at rest. The speed at which the respective motors have to operate is controlled by the respective controls 205. This control will determine the speed of a ratchet 143. Figure 16 shows a schematic section of an air extraction unit 167 with a primary air stream 19 and secondary air streams 161 and 163, these latter flowing along said air extraction unit 167. Only the optionally composite primary air stream 19 is drawn in mainly via grid 164 with the intention of reusing this air to form air wall 19' . Secondary air streams 161 and 163 are pressed against an end plate, wall 162 or other obstacle and there held back, and will there form turbulent air volumes at respectively 165 and 166 which do not affect the primary air stream 19 flowing through grid 164. It is also possible to envisage there being no obstacle 162 for secondary air stream 161. In that case this secondary air stream 161 will flow further into the space and there disappear. This situation is shown in figures 17 and 18. It is noted that only a negligible mixing will occur between primary air stream 19 and secondary air stream 161, whereby only a very small moisture transfer will take place.

Figure 17 shows a schematic section wherein primary air stream 19 is directed such that moisture from outside can be introduced into the cold store. The temperature of primary air stream 19 will hereby rise because more air is now drawn in from the secondary air stream on the warmer side 163 via grid 164.

Figure 18 shows a schematic section wherein primary air stream 19 is directed such that it becomes colder and drier relative to the outside temperature and humidity. This is because a part 161' of the colder secondary air flow 161 is drawn in via grid 164. The thus obtained air mixture of a part of primary air stream 19 and a part 161 ' of the colder air stream 161 then becomes colder. A balanced control of the direction of primary air stream 19 is shown in figure 16.

Figure 19 shows a schematic section wherein at the bottom of the door opening all air streams 161, 19 and 163 are pressed outward in direction 191 as a result of thermal pressure due to the local difference in temperature and humidity. The air streams are improved by setting the vane 190 such that they are similar to the situation shown in figure 16. Figure 20 shows a schematic section wherein at the top of the door opening all air streams 161, 19 and 163 are pressed inward in direction 192. See the further elucidation of figure 19.

Figure 21 shows a top view of the compressed air blower device 170 for blowing fine ice crystals out of grid 164. The compressed air blower device 170 consists of a mini-cavity 174 in which a slit 173 of 1 to 2 mm is arranged. An air compressor group 176 provides compressed air via a flexible compressed air line 175. Exiting from slit 173 is an air stream 171 under pressure which blows the ice crystals away through the openings of grid 164. Reference numeral 19 indicates the direction of the primary air stream, which is opposite to that of the air stream under pressure 171. The width of grid 164 and mini-cavity 174 is indicated with reference numeral 180 and has a width of 15-50 cm, preferably 30-35 cm.

Figure 22 shows a schematic section of air suction unit 167 at the position of compressed air blower device 170, having therein a flexible compressed air line 175. The air stream under pressure 171, which is blown through grid 164 and entrains the ice crystals, enters primary air stream 19 and secondary air stream 163 and eventually becomes turbulent at closure 162 at the position 166 where the ice crystals will adhere visibly and accessibly somewhere or drop down onto the floor.

Figure 23 shows a side view of air suction unit 167 with a grid 164 therein. Behind grid 164 can be seen the compressed air blower device 170, components of which have been described with reference to figures 21 and 22. In addition, wind guiding plates 171 are arranged upward and downward which ensure that no air suctioned from air streams 19 and 163 enters the location at height 172. The compressed air flow 171 can hereby develop, with transport of the fine ice crystals out of grid 164 which are then further discharged externally to the location 166. The whole compressed air blower device 170 is displaced downward and upward by means of drive chains 181 with cogwheels 182 and motor with worm wheel 183 during the operation of air wall 19, while the compressed air flow 171 is maintained during the displacement. At location 184 is a space where the compressed air blower device 170 with wind guiding plates 177 is held out of air stream 19 during the rest periods. The time control 185 of motor 183 is also indicated. The air compressor group 176 is likewise controlled with a compression control and magnetic valve for compressed air and accommodated in 185. When the compressed air blower device 170 arrives at the bottom the lower wind guiding plate 177 will move into flat position, whereby the compressed air blower device 170 can also serve the lowest point of grid 164. When the blower device moves upward again, a spring (not shown) will then ensure that the lower wind guiding plate moves back into the vertical position. The same system is provided on the top side in order to keep the height for location 184 as small as possible.

Figure 24A shows the air streams which occur after opening a door between two spaces at respectively +5°C and -20⁰C. The Dt (difference in temperature) along 220 is 25°C. The Dx (difference in AH, absolute humidity) is: 0.5 g/kg at -20⁰C and 6 g/kg at +5⁰C. If this outside space is cooled, the AH can then become ± 5 g/kg. The Dx then becomes about 4.5 g/kg. If the door remains open, the temperature and the AH decrease, whereby the shown air streams will also decrease in volume.

Figure 24B shows the same situation as in figure 24A, although an attempt is now made to limit the air losses by means of air wall 19. At the top the air wall 19 will diverge in the direction indicated by arrow 225 toward the cold store. At the bottom the direction, indicated by arrow 227, will diverge toward the higher temperature. In the centre at 226 there is no divergence. The divergence will decrease as the pressures in the air wall increase. The Dt and Dx are the same as in figure 24A.

Figure 24C shows a double air wall 19, 19' in a tunnel passage

229. The difference in temperature between air walls 19 and 19' can for instance be -8⁰C. Shown below is a table indicating the respective values for t and x. It will be apparent that both Dt and Dx decrease over each air wall. The divergence will hereby decrease sharply and, depending on modification of the pressure in the air wall, perhaps disappear completely. If a third air wall were placed in tunnel 229, the effect would of course be even more favourable. 221 222

-8°C +5°C → DT=13°C -20°C -8°C → DT=12°C

AH → 2g/kg 5g/kg → Dx=3g/kg 0.5g/kg 2g/kg → Dx=I.5 g/kg

Figure 25 shows a cold store 301 with an internal temperature in the order of -20⁰C. The outside temperature, i.e. the temperature of the ambient air, amounts in this example to about 5⁰C. There is thus a difference in temperature of 25°C between the air in the cold store and the outside air. A blower device 303 for generating an air wall 304 is added to a passage opening 302. This air wall, which will be described in more detail hereinbelow, comprises an at least more or less flat air stream which extends in a vertical plane and which moves in the drawing from the left-hand side of blower device 303 to the right-hand side of blower device 303. The relatively warm outside air is effectively separated from the cold inside air by this air stream, which has a substantial speed, i.e. a speed of at least 15 m/s, or more than 54 km/h. This separation relates to all relevant properties of the inside air and the outside air, in particular temperature and humidity.

Figure 26 shows blower device 303 in more detail. The blower device comprises a blower device 305 positioned on one side of passage opening 302 and having a blower fan 306, which fulfils an additional function in the manner to be described hereinbelow, and a blower slit 307 which connects thereto on the blower side, is arranged substantially parallel to the main plane of passage opening 302 and extends over at least substantially the whole height of passage opening 302 for the purpose of generating the air stream, which is indicated with arrows 308 and forms air wall 304, this air stream being directed at the other side of passage opening 302. Blower device 305 comprises a cavity 309 which connects via a duct 310 to fan 306, to which cavity 309 the blower slit 307 connects. This has a width 333 of for instance 10-30 mm and a length 334 of 20-40 cm in the direction of air stream 8.

The drawing shows that cavity 309 and blower slit 307 have a prismatic form. Situated on the other side of passage opening 302 is a suction unit 311 with a suction slit 312, which in this embodiment is substantially prismatic. Suction slit 312 also connects to fan 306 via a second duct 313. There is therefore, as indicated with arrows 324 showing the air streams, a more or less closed circuit in portal 315, of which air stream 308 and thereby air wall 304 form part, and which is wholly generated and sustained by fan 306. Added to suction slit 312 are a number of passive constant flow control valves 314 which are uniformly distributed along the height such that the same air stream passes through at each height position. As a result the air in air stream 308 flows substantially horizontally at any height. Arrows 308 indicate this.

Claims

1. Blower device for generating an air wall for thermal separation of the air in a first relatively cold space from the air in a second relatively warm space, for instance the surrounding area, which spaces are mutually connected by a passage opening, the blower device comprising: an elongate blower device positioned on one side of the passage opening and having a longitudinal direction and comprising fan means and a blower slit which connects thereto on the blower side, is disposed substantially parallel to the main plane of the passage opening and extends over substantially the whole relevant dimension of the passage opening for the purpose of generating an at least more or less flat air stream directed at least roughly toward the opposite side of the passage opening; characterized in that the speed of the air in the air blower slit amounts to at least 15 m/s; and the width of the blower slit lies in the range of 5-40 mm; the length of the blower slit in the direction of the air stream lies in the range of 5-100 cm, preferably 5-40 cm, more preferably 10-30 cm; the cavity has an at least more or less prismatic form, i.e. has the same cross-sectional form at any longitudinal position; connecting to which cavity on one side is at least one air feed, extending substantially over the whole longitudinal dimension of the cavity, and on the other side the blower slit; which blower slit is bounded by two smooth, mutually parallel surfaces; in the upstream zone of which cavity an airflow resistance is present; the zone of which cavity downstream of the airflow resistance has a form narrowing in the flow direction; and which air feed slit and which air blower slit together define an airflow pattern with a main airflow direction in the cavity, this pattern being substantially the same at any longitudinal position of the downstream part of the cavity, and the airflow speed in this downstream part is everywhere directed toward the inlet of the blower slit.

2. Blower device as claimed in claim 1, wherein the airflow resistance comprises an at least more or less plate-like element with a regular pattern of openings, for instance a gauze, a perforated plate or the like, the throughflow area of which amounts to about 0.1 - 0.6 times, preferably about 0.3 times, the relevant area of the plate-like element, and the linear dimensions of the openings lie in the range of about 1-15 mm.

3. Blower device as claimed in any of the foregoing claims, wherein the blower fan means connect via a feed space to the at least one air feed.

4. Blower device as claimed in any of the foregoing claims, wherein the airflow resistance lies at a distance from the at least one air feed of about 0.2 - 0.4 times, preferably about 0.30 - 0.35 times, the overall distance between the at least one air feed and the inlet of the blower slit.

5. Blower device as claimed in any of the foregoing claims, wherein the passage of the at least one air feed is adjustable.

6. Blower device as claimed in any of the foregoing claims, wherein the transitions of the inner surfaces of the cavity to the inner surfaces of the blower slit have smooth, rounded forms.

7. Blower device as claimed in any of the foregoing claims, wherein at least the blower slit is pivotable around a pivot zone roughly parallel to the longitudinal direction of the blower unit.

8. Blower device as claimed in any of the foregoing claims, wherein the feed duct has a prismatic form.

9. Blower device as claimed in any of the foregoing claims, wherein the blower slit extends at least partially inside the feed duct.

10. Blower device as claimed in any of the foregoing claims, wherein the blower slit is closed on its side remote from the blower opening by a panel extending transversely of the outflow direction and extending at a distance from the widest part of the blower slit.

11. Blower device as claimed in claim 10, wherein the panel is movable substantially parallel to itself in the outflow direction.

12. Blower device as claimed in any of the foregoing claims, wherein a perforated connecting plate extends substantially transversely of the outflow direction between the walls of the blower slit, and the connecting plate is connected to at least one of the two walls.

13. Blower device as claimed in any of the foregoing claims, wherein at least one of the walls of the blower slit is movable in the direction transversely of the blow-in direction.

14. Blower device as claimed in claim 13, wherein the movable wall of the blower slit is suspended from at least three arms extending substantially parallel to the wall.

15. Blower device as claimed in claim 13 or 14, wherein the movable wall is coupled to an adjusting mechanism comprising levers .

16. Blower device as claimed in any of the foregoing claims, wherein the blower slit is placed for tilting in its length direction in the feed duct.

17. Blower device as claimed in any of the foregoing claims, wherein the feed duct has a substantially triangular cross-sectional form.

18. Blower device as claimed in any of the foregoing claims, wherein at least one heat exchanger is arranged in the blower slit.

19. Blower device as claimed in any of the foregoing claims, wherein the device comprises two fans connected on either side of the feed duct.

20. Blower device as claimed in any of the claims 1-18, wherein an auxiliary blower slit is arranged adjacently of the blower slit and connected to an auxiliary fan.

21. Blower device as claimed in any of the foregoing claims, wherein the movable walls are connected to an electric motor by means of a belt drivable by an electric motor and at least one lever .

22. Blower device as claimed in claim 21, wherein the position of at least one of the electric motor, the bearing of the drivable belt or the at least one lever is for instance adjustable by means of a screw spindle which can be operated with a screwdriver.

23. Blower device as claimed in claim 21 or 22, wherein the electric motor is coupled to a detector for detecting gusts of wind, which is adapted to generate to the electric motor a signal when a gust of wind is detected, and the electric motor adjusts a wall of the blower slit when such a signal is received.

24. Blower device as claimed in any of the foregoing claims, comprising an air extraction unit placed upstream of the fan and comprising a prismatic discharge duct with a cross-section having an acute angle, wherein the acute angle is turned toward the direction from which the air for extraction is supplied, and a feed opening is arranged in a wall adjacent to the acute edge.

25. Blower device as claimed in claim 24, wherein a panel extending in lengthwise direction and connected tiltably to the discharge duct is placed on the acute edge of the duct .

26. Blower device as claimed in claim 24 or 25, wherein a compressed air device is present in the discharge duct which is adapted to guide a compressed air flow to the feed opening.

27. Blower device as claimed in claim 24, 25 or 26, wherein the discharge duct is located in the side of the passage opening opposite the other parts of the blower unit.