Background of the invention

The present invention relates to a ventilation duct in accordance with the preamble of claim 1 which duct can considerably facilitate the building of ducts in work site conditions.

The invention also relates to a method in accordance with the pream- ble of claim 7 for connecting such ventilation ducts to each other.

The invention further relates to an arrangement of claim 11 to pro- duce an installation aid marking for installation in the ventilation duct.

When building a ventilation system by means of ventilation ducts con- nectable to each other, there often arise problems when forming sections that orientate in several different directions. Such installations implemented in many directions require that installers continuously check the installation work and the pipe system in order to ensure correct locations. This makes the work slow and thus also expensive.

Brief description of the invention

It is therefore an object of the invention to achieve a ventilation duct and a method for installing such ventilation ducts so that the aforementioned problems can be mainly solved.

This object is achieved in such a manner that the ventilation duct, the method for its installation and an arrangement for producing an aid marking for installation in the ventilation duct are, in accordance with the present invention, provided with the characteristic features defined in the claims. More specifically, this ventilation duct according to the invention is mainly characterised by what is stated in the characterising part of claim 1. The method according to the inven- tion is, in turn for the most part characterized by what is stated in the characteriz- ing part of claim 7, and the arrangement according to the invention for producing an aid marking for installation in the ventilation duct is for the most part charac- terized by what is stated in the characterizing part of claim 11.

Preferred embodiments of the invention are disclosed in the depend- ent claims. The invention is based on adding a simple feature onto the outer sur- face of the ventilation duct and thus facilitating the accurate alignment of succes- sive ventilation ducts to each other. Hence, it is possible to avoid extra verifying measurements and still be able to provide an installation based on drawings or other plans.

Other advantages provided by the invention are disclosed in the fol- lowing in connection with a more detailed description of specific embodiments of the invention.

Brief description of the figures

In the following, some preferred embodiments of the invention will be explained in more detail and with reference to the accompanying drawing, in which

Fig. 1 shows a principled view of a ventilation system,

Fig. 2 schematically shows location of aid markings for installation as aid lines on the outer surface of a ventilation duct,

Fig. 3 shows an angle of 90 degrees implemented by ventilation ducts guided by installation aid lines,

Fig. 4 shows successive 90-degree angles implemented by ventilation ducts guided by installation aid lines, wherein the upper angle of the figure is also rotated for 90 degrees compared with the previous one,

Fig. 5 shows location of aid markings for installation according to a second embodiment of the invention as aid lines and point-like markings on the outer surface of a ventilation duct, and

Fig. 6 shows a cross cut of the ventilation duct in point A-A of Fig. 5 describing a location of point-like markings.

Detailed description of preferred embodiments

The present figures do not show the ventilation duct, the method for the installation of such ventilation ducts or the arrangement for producing an aid marking for installation in scale but the figures are schematic, illustrating the general structure and operation of the preferred embodiments. The structural parts shown by reference numbers in the attached figures then correspond to the structural parts marked by reference numbers in this specification.

Fig. Ishows a principled view of a ventilation system 1 in a detached house, in which system, ventilation ducts 2 connected to each other form parts conveying air to various terminal devices and from terminal devices. In the pre- sent invention, the ventilation ducts are substantially round of their cross section and have a substantially straight or curved longitudinal axis 3. According to Fig. 2, such a tubular ventilation duct comprises an interior forming a flow space 4 and surrounding it an air-impermeable sheath 5 which includes an inner surface 6 and an outer surface 7. Most conventionally, the present ventilation ducts are formed of a metal spiral-weld pipe or polymer pipe.

As it can be concluded from Fig. 1, the ventilation system 1 formed by the ventilation ducts 2 is, even in its simplest form, quite complex comprising sec- tions oriented into several different directions. These very installations imple- mented in many directions have been very problematic and they have required that installers continuously check the installation work in order to ensure correct locations.

To decrease these known installation problems, the present invention provides at least one aid marking for installation 8 on the outer surface 7 of the sheath 5 of the ventilation duct 2 which markings facilitate the positioning of two successively installable ventilation ducts in relation to each other at the same time considering a possible common rotation between the ventilation ducts in re- lation to their longitudinal axes.

Said installation aid marking 8 can comprise one or more point-like markings provided on the outer surface 7 of the sheath 5 of the ventilation duct 2 being curved in accordance with Fig. 5. The installation aid marking can also comprise one or more aid lines, which can be solid or dashed, parallel with the longitudinal axis 3 of the ventilation duct in accordance with Figs. 3, 4 and 5.

If two or more installation aid markings 8 have been produced in the ventilation duct 2, central angles 9 between radiuses R directed towards the lon- gitudinal axis 3 are preferably formed of the same size or as multiples of said cen- tral angle. In general, the installation work is already facilitated considerably by two aid markings for installation which are arranged symmetrically on the oppo- site sides of the outer surface or by three installation markings, whereby the third one is located at an equal distance from the above-mentioned markings between them, in a way described by Fig. 2. Therefore, adjacent central angles are provid- ed between these three installation markings, both of which angles are 90 de- grees. Indeed, the number of aid markings for installation is implementable as re- quired based on the complexity of the installation site, whereby more complex sites can have e.g. eight aid lines for installation evenly distributed on the perime- ter of the outer sheath with 45-degree intervals.

Installation work can also be considerably facilitated by an embodi- ment according to Figs. 5 and 6, wherein straight-shaped ventilation ducts are provided with one or two opposite aid lines and curved ventilation ducts with their curved longitudinal axes are preferably provided with four point-like mark- ings evenly distanced from each other according to Fig. 6.

The aid markings for installation according to the arrangement are uti- lised in building the ventilation system 1 as follows.

In the installation method, the ventilation duct 2 substantially round of its cross section has a substantially straight or curved longitudinal axis 3 as de- scribed above. Before starting the installation work, one or more installation aid markings 8 are provided on the outer surface 7 of the sheath 5 surrounding the flow space 4. When connecting ventilation ducts which, on one hand, have straight and, on the other hand, curved longitudinal axis to each other, the instal- lation aid markings to be connected to each other are selected to provide a prede- termined common rotation in relation to the longitudinal axis. Hence, the possible common rotation of two successively installable ventilation ducts is easy to im- plement and the ventilation ducts can be accurately positioned in relation to each other, as described in Figs. 3, 4 and 5.

The installation aid marking 8 provided on the outer surface 7 of the sheath 5 of the ventilation duct 2 is implemented either as a point-like marking or as an aid line parallel with the longitudinal axis 3 of the ventilation duct. These can be provided at the installation site but it is more preferable to provide them already in connection with the manufacture of the ventilation duct. When provid- ing more than two more installation aid markings on the outer surface of the ven- tilation duct, they are preferably provided such that central angles between radi- uses directed from them towards the longitudinal axis are formed of the same size or as multiples of said central angle.

Fig. 3 thus shows a 90-degree duct unit formed by two straight and one curved ventilation ducts 2, in which example, the installation aid markings 8 of the two straight and curved ventilation ducts always meet.

Fig. 4 in turn shows successive 90-degree angles implemented by three straight and two curved ventilation ducts 2 at the same time as the upper angle of the figure is also rotated for 90 degrees compared with the previous one. It is possible to see from the figure that, in the lower angle, the installation aid marking of the straight ventilation duct is arranged at the point of the installation aid marking being in the inner fold of the curved ventilation duct. In the upper angle, the installation aid marking of the straight ventilation duct is arranged at the point of the installation aid marking being in the outer fold of the curved ven- tilation duct.

The present installation aid marking 8 can be produced in the ventila- tion duct 2 either by hand at the installation site or, more reliably, when manufac- turing the ventilation duct. In order such a marking not to cause aesthetic nui- sance or to requisite separate priming before the possible coating, the marking is preferably done without deforming the outer surface 7 of the ventilation duct. The arrangement utilised in the manufacture for producing the aid marking for installation in the ventilation duct thus comprises means arrangeable in connec- tion with the duct manufacturing line, which means produce either a brief or con- tinuous drawn marking or particle spray directed on the outer surface of the ven- tilation duct. This particle spray producing the marking of the outer surface of the ventilation duct comprises e.g. a fiber laser or an ink-jet printer.

It is of course possible to provide the aid markings for installation on the surface of the ventilation duct by deforming it, unless particular demands have been set for its visual appearance. Then, an aid line is formable on the outer surface of a ventilation duct having a straight longitudinal axis e.g. by engraving mechanically or by a laser. For parts of a ventilation duct manufactured by press- ing, the installation aid marking 8 can be provided e.g. separately by die-cutting or peening or in connection with the manufacture with a punch in the press tool.

Those skilled in the art will find it obvious that, as technology advanc- es, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not restricted to the examples de- scribed above but may vary within the scope of the claims.