DEVICE FOR REVERSING AN AIR FLOW IN A DRYING CHAMBER

Abstract: Device for reversing an air flow in a drying chamber where the air flow is created by means of at least one blower (20). A drum (23) rotatable about its longitudinal shaft (24) is arranged about the blower or blowers, said drum having apertures (25, 26) on its casing surface to provide an air flow through the drum. The drum (23) extends from the floor of the drying chamber to its roof or is sealed in another way at its ends. By rotating the drum (23) about its longitudinal shaft (24) between two different positions a reversal of the direction of the air flow in the drying chamber is achieved in a very simple way although the blower is stationary and drives the air continuously in the same direction. A heat battery (21) is arranged on the intake side of the blower (20).

Description: Device for reversing an air flow in a drying chamber This invention relates to a device for reversing an air flow in a drying chamber where the air flow is created by at least one blower. In drying chambers for e.g. drying of wood there is a need of reversing the direction of the air flow in the drying chamber during a drying process. A reversal of the direction of the air flow is desired in order to obtain a continuous and rapid drying of the wood. As a rule, the air flow is created by means of one or more blowers and the circulating air is normally heated by means of a heating device of some type, e.g. one or more so-called heating batteries. According to known technology the reversal of the air flow is ef¬ fected for instance by turning the blowers so that these operate in different directions in dependence on the desired air flow direction. The blowers can be mounted on a common support frame which is then ar- ranged rotatablγ. It is also previously known to change the air flow direction by adjusting a number of dampers or doors arranged at one or more stationary blowers. It is the object of this invention to provide a device for reversing the air flow, said device being very reliable and, moreover, having a very simple structure, and this object is achieved by means of the characteristic features defined in the claims. The blower or blowers can be designed for one single direction of rotation or working direction by means of the inventive device, resulting in that the blower can be made more efficient simultaneously as no reversal is necessary with accompanying recurrent re¬ starts of the driving motor of the blower. Moreover, the reversal of the air direction by means of the in- ventive device is very soft which is also advantageous. Furthermore, there is a great freedom of choosing the position of heat batteries about the blowers as the latter are stationary. Also, there are no difficulties in drawing the required connection lines to heat bat¬ teries and blower motors . Illustrative examples of the invention will be de¬ scribed below with reference to the appended drawings, wherein Fig. 1 shows a horizontal section of a drying chamber provided with an inventive device, Fig. 2 shows a vertical section of a part of the drying chamber, Fig. 3 shows a section of the inventive device taken along the line III-III according to Fig. 2, and Figs . 4 and 5 show schematically the inventive device in its two different working positions. Fig. 1 shows a drying chamber with four walls 1-4 and an aperture 5 provided with a door. Within the drying chamber there is a wall 6 extending between the floor 7 and roof 8 of the drying chamber and defining in this way a passage 9 from the part of the drying chamber where the wood to be dried is placed. In Fig. 1 four piles of wood 10 are shown as an example thereof. A number of stationary blowers 20 are arranged in the passage 9 which preferably consist of axial fans operated by electric motors (not shown) . A so-called heat battery 21 fed by hot water (not shown) is ar- ranged close to the blowers 20, the object of which is to heat the air circulating in the drying chamber. The heat battery 21 is arranged on the suction side of the blowers 20. Moreover, shields 22 for air control are arranged at the blowers 20. According to the invention a rotatable cylinder/drum 23, for instance made of a relatively thin sheet, is disposed about the stationary blower-heat battery device. The drum 23 is arranged to be rotatable about its longitudinal shaft 24. The drum 23 is provided with apertures 25, 26 in its casing sur- face which apertures provide an air flow through the drum. Sealing shields 27 are disposed between the heat battery 21 and the drum 23 which are intended to pre¬ vent an undesired air leakage. A roof shield 29 is connected with the heat bat¬ tery 21, the object of which is to seal the upper end of the drum 23. Similarly, it is also possible to ar¬ range a floor shield connected with the heat battery 21 and sealing the lowermost end of the drum 23, but in many cases it is as suitable to use the floor 7 of the drying chamber or a frame arranged on the floor for this purpose. A shield 30 sealing between the heat bat¬ tery 21 and the floor 7 may then be required. In order to achieve the rotational ability of the drum 23 about the rotary shaft 24 the drum 23 is pre¬ ferably provided with a number of wheels 32. A number of guide rolls 33 is arranged on the wall 2 and a number of guide rolls 34 is arranged on the wall 6 as well which wheels and guide rolls are intended to fa¬ cilitate rotation of the drum. In order to obtain this turning or rotation an electric motor (not shown) is for instance arranged which can rotate the drum 23 in a desired direction via a mechanical gear and a chain drive 40 by way of a chain 41 connected with the drum 23. The rotational drive of the drum 23 can of course be arranged in a plurality of different manners and the arrangement just mentioned is only an example thereof . Other possible alternatives can be belt drive, gear drive or friction drive. Moreover, the wheels 32 and the guide rolls 33 and 34 can of course be arranged in another way than that shown here. By rotating the drum 23 so that it enters the turning position shown in Figs. 1, 3 and 4 the blowers 20 will drive the air flow in the drying chamber in the direction shown by the arrows A, the aperture 25 serv¬ ing as intake aperture and the aperture 26 as blow-out aperture. The air flow in the drying chamber can be reversed very simply by rotating the drum 23 so that the aper¬ tures 25 and 26 are moved 1/4 of a revolution to the position shown in Fig. 5. The blowers 20 having the same direction of rotation all the time will then drive the air flow in the direction shown by the arrows B. It will be appreciated from the above that it is very easy to reverse the air flow direction in the dry¬ ing chamber whenever desired by means of the inventive device. The device of the invention can be used irre- spective of the number of blowers and heat batteries used. Of course it is also possible to provide the drum with one or two end sections if this is necessary with respect to the surroundings of the drum. The drum apertures 25 and 26 can of course be di¬ vided into a suitable number of smaller apertures to impart an increased stability to the drum, if required. The blower 20 can of course also comprise a so-called radial fan if this should be found to be suitable. Moreover, the control and bearing of the drum 23 can of course be designed in several different ways in addition to that shown here. In order to make the placement of the drum in the drying chamber easier it may be suitable for practical reasons to design the drum in a number of parts that are assembled when the drum is installed. Of course it should also be realized that the de¬ vice of the invention is not restricted to drying chambers for wood but it can naturally be used in all types of drying chambers where reversal of the direc¬ tion of the air flow is desirable. Thus, the invention is not restricted to what has been shown and described above but amendments and modi- fications thereof are possible within the scope of the appended claims.

Claims: What is claimed is: 1. A device for reversing an air flow in a drying chamber where the air flow is created by means of at least one blower (20), a drum (23) rotatable about its longitudinal shaft (24) being arranged about the blower or blowers, said drum having at least two recesses or apertures (25, 26) on its casing surface (25, 26) to provide an air flow through the drum, c h a r a c - t e r i z e d in that the rotary shaft (24) of the drum (23) extends in vertical direction, that the ro¬ tary shaft of the blower (20) extends in horizontal di¬ rection and that the drum (23) extends substantially from the floor (7) of the drying chamber to its roof (8). 2. The device of claim 1, c h a r a c t e r ¬ i z e d in that the blower (20) is stationary and of axial type. 3. The device of claim 1 or 2, c h a r a c - t e r i z e d in that the apertures (25, 26) are ar¬ ranged diametrically. 4. The device of any one of claims 1-3, c h a r ¬ a c t e r i z e d in that the drum (23) is rotatable by means of wheels (32) and/or rolls (33, 34). 5. The device of any one of claims 1-4, c h a r ¬ a c t e r i z e d in that it comprises means (40, 41) for providing rotation of the drum (23) between two different turning positions. 6. The device of any one of claims 1-5, c h a r - a c t e r i z e d in that at least one heat battery (21) is arranged on the intake side of the blower (20) within the drum (23). 7. The device of any one of claims 1-6, c h a r ¬ a c t e r i z e d in that shields (22, 27, 30) for air control are arranged close to the blower (20).

Inventors: FORSSEN GUSTAV, FORSSEN, GUSTAV
Applicants: UTEC S M AB, UTEC S.M. AB
Application year: 1987
Main classification: F26B21
IPC codes: F26B21