This invention relates to an air conditioning tube having air outlet apertures for discharging incoming air into the room to be air-conditioned, the tube being designed into an air disperser blowing in the incoming air,by punching a plurality of small air outlet apertures into the tube wall.

It is previously known to design an air con litioning tube into an air dispenser blowing in incoming air by punching appropriately sized and spaced apertures in the tube wall.

In examining the outflow of air from the said apertures, it can be seen (cf figure 2) that the velocity and direction of the air flow inside the tube cause a certain axial component also in the air jets discharged outside the tube, whereupon the mass of air surrounding the tube begins to flow parallel to the tube hitting e.g. the opposite wall through which the tube is led. The radial flow component v, , shown in figure 2, is dependent on the static pressure inside the tube in such a way that as the static pressure increases, component v. increases. The axial flow component v ₂ , which is discharged outside the tube via aperture 3, is dependent on both the flow velocity v _Q inside the tube and the diameter of aperture 3 in relation to the material thickness of wall 2. As an interaction of these factors, a flow v is produced outside the tube, the said flow v having a lower or higher axial component v_.

The object of the invention is to develop further this type of an air conditioning tube, in order to be able to partially or fully compensate flow component v .

This object is achieved on the basis of the characteristics

of the invention described in the enclosed claims.

In the following the invention is described with reference to the enclosed drawings wherein

Figure 1 shows as a partial axial section, a spiral-seam air conditioning tube relating to one of the embodiments of the invention.

Figure 2 shows an enlarged detail of the air conditioning tube aperture and the flow components relating to it.

Figures 3-8 show alternative embodiments of the invention.

The spiral-seam air conditioning tube shown in figure 1 is manufactured by punching apertures 3 into the strip led from the storage roll with an appropriate punching device, before inserting the strip into the spiral seaming machine, in which the spiral-seam air conditioning tube 1 is manufactured in the known manner. The spiral seam is marked with the reference numeral 10.

With reference to figure 2 it is stated that the air flowing inside the tube with a given velocity v_ brings about in the air flowing out of the tube through aperture 3 also an axial flow component v_, the relative value of which depends on both the velocity v- as well as the diameter of aperture 3 in relation to the thickness of wall 2. Practical tests have, however, shown that the flow component outside the tube and parallel to it often becomes disturbingly high.

In order to eliminate flow component v~ partially or fully, the starting point of the invention has been to choose as the air conditioning tube a type of tube known as such, and to which tube 1 has been formed by distending

the tube 1 wall material 2 inwards or outwards a groove 4, which encircles the tube in the same spiral manner as seam 10. The function of the groove is to reinforce the tube. Between the seams there may be one or more grooves. In the embodiments of figures 1 - 4, apertures 5 piercing the wall material 2 on one side of groove 4 have been punched in the groove in addition to those punched on the side of the tube. The direction of flow v- of the air flowing out of apertures 5 on only one side of groove 4, contains an axial component which is opposite to the flow component v . Thus flow v- stops either partially or fully the flow parallel to the tube, whereupon the exhaust air is distributed evely in the room and not e.g. on one wall of the room.

Figure 3 shows a case in which there are several outwards distending grooves between the seams. Figure 4, on the other hand, shows a case in which the groove is distended inwards.

Apertures 5 can be punched in connection with apertures 3, whereat the positions of the apertures on the. web to be fed into the seaming machine are determined so that they fit appropriately in relation to the groove 4 formed in the seaming machine. Apertures 5 may obviously also be punched separately and sized differently from apertures 3.

In the case of figure 5, inclined apertures have been punched into the side of the tube, that is, the apertures have been formed into flow openings deviating from the radial direction into the axial direction, the said openings having the shape of a deflector nozzle. This form is produced by using an appropriate tool for the punching.

In figure 6, the inclination of the nozzles 6 has been

brought about by providing grooves 7 and 8 in the tube wall material on both sides of the row of nozzles, of which grooves one is deeper than the other and between which remains a space essentially wider than the basal diameter of the nozzle tube.

In the case of figure 7 the groove provided with air outlet apertures is connected to the interior of the tube by means of a narrow flow pass, whereat the groove forms a decompression chamber 12 around the tube, which chamber in addition eliminates the effect of the speed component of tube interior flow on the outflow direction. In this the pressure loss between the tube and outside air take place in two steps, P, - P_ and P_ - P _Q , during which the pressure loss between the tube and outside air can be increased while the uniformity of the flow and acoustic properties improve. Flow openings 13 can be made into both walls of the decompression chamber 12 or at the top of it, as in figure 8.

In the case of figure 8, the decompression chamber has been constructed by fixing in the wall opening of tube 1 a separate plastic strip 9 which comprises a cavity acting as a decompression chamber, the said cavity being connected to the interior of the tube by means of a throttle or openings 11 and opens to the outside of the tube via a nozzle opening 14 provided with deflector walls. The nozzle openings 14 can be provided with piercable diaphragms whereat the opening of a desirable and variable number of nozzle openings 14 is made possible.