The present invention relates to a hatch construction for trap doors or the like, said hatch construction comprising a metal hatch frame with a flange pressing against the lower surface of the ceiling board and a hatch on the hatch frame that closes the hatch opening- Different trap and access doors secured to the inner surface of a ceiling are used for inspecting and maintaining air conditioning, electric and plumbing systems. Typically, this type of hatch is made by manufacturing a metal frame to which a hatch is secured in such a way that it pivots on its hinges at one edge. The frame is then secured to an opening made in the ceiling by screwing it to ceiling boards or by inserting separate supporting means in the gap on the upper edge of the frame so that the hatch rests on the supporting means and is supported by the upper surface of the ceiling board.

This type of hatch made of metal plate is expensive to manufacture and furthermore, even if separately painted, it is clearly distinguishable from the rest of the ceiling. It also requires a separate tool or key, whereby it can be opened on inspection. Securing the hatch is difficult, and especially where small hatches are concerned, it has to be carried out before the ceiling boards are mounted.

It is the object of the present invention to provide a hatch construction by which the above- mentioned disadvantages can be avoided and which is easy to manufacture and secure. The hatch construction of the invention is characterized in that the hatch frame is formed of a light metal profile with flanges that form between them a mounting slot in order to secure the

frame profiles of the frame to one another by means of corner pieces inserted into the slots, these frame profiles being at an angle to one another; that each frame profile comprises a flange that is essentially parallel to the lower surface of the ceiling both on the outer edge of the frame profile and on the side of the hatch opening; that the hatch is separate from the frame and can be arranged to be supported by the frame, resting on the flange located on the side of the hatch opening.

It is an essential idea of the invention that the hatch frame comprises a profile with two flanges on the outwards visible surface so that one rests against the lower surface of the ceiling board and the other supports the hatch preferably made of the same material as the ceiling. Another essential idea of the invention is that the frame profiles are secured to each other by separate corner pieces, whereby it is not necessary to weld them or otherwise separately secure them mechanically. Yet another essential idea of the invention is that the frame is secured to the ceiling board either by a mounting element, such as a corner piece, a fixing screw extending through a vertically elongated opening in the frame profile, or by a wedge- shaped locking piece inserted through the opening in the frame profile.

An advantage of the invention is that for the hatch, it is necessary to manufacture only one light metal profile by extrusion, out of which all sides needed for the frame can be provided by sawing or by machining in some other similar manner. A further advantage of the invention is that the frame is easy to assemble because all that is required is that the corner pieces made of a suitable corner profile, such as an aluminium profile corner, are pressed into the mounting

slot of the frame profile so as to form a rectangular hatch frame. Another advantage of the invention is that it is easy and simple to mount by forming in the profile frame suitable, vertically elongated openings through which the frame can be mounted on the ceiling board by screws, wedges or the like. Moreover, a further advantage of the invention is that no separate metal hatch is needed but the hatch can be made for instance of the same ceiling board material as the rest of the ceiling using for instance the part removed from the opening of the hatch frame and reducing it so that it will fit properly on the inside of the hatch frame, resting on the flange thereof directed towards the opening and thus covering the opening. The invention will be described in greater detail in the appended drawings, in which

Figure 1 is a schematic representation of a cross section of the hatch construction of the invention and Figure 2 is a schematic representation of a partial cross section of the hatch construction of the invention, seen from below.

Figure 1 shows the hatch construction of the invention cross-cut at one side of the hatch. A hatch frame 2 is mounted in an opening formed in a ceiling board 1, said hatch frame comprising frame profiles 3a -

3c and corner pieces 4a and 4b for connecting said frame profiles. As is apparent from the figure, the frame profiles are provided with flanges in both directions at their lower edge so that an outer flange 5 rests against the lower surface of the ceiling board 1 and an inner flange 6 supports a hatch 7. Further, in the sides of the hatch frame 2 are formed elongated openings 8 through which are fitted fixing screws 9. The fixing screws 9 are used to tighten mounting corners 10

against the outer surface of the hatch frame 2, said mounting corners being used to mount the hatch frame 2 firmly against the lower surface of the ceiling board 1. The cross section of the frame profile is such that apart from the part visible under the ceiling board 1 and the hatch 7, there is a flange 11 extending to the upper end of the frame profile, making a cross-sectional downward bend there. Similarly, upwards from the visible part of the profile there is another, lower vertical flange 12 so that the flange 12 and the downwards pointed part of the flange 11 are on the same line but spaced from each other. This allows a mounting slot to be formed in the frame profile, into which the corner pieces 4a and 4b can be inserted at their one end. At the same time, the mounting elements for the frame composed of the frame profile, such as screws or the like, remain outside the inner dimensions of the opening of the frame inside the frame profile so that they will not obstruct the mounting of the hatch 7. In principle, the flanges of the frame profile could be attached in reverse order, but said embodiment is nevertheless the most preferable. While the hatch frame 2 is assembled, the corner pieces 4a and 4b are mounted at their ends in the angle between the frame profiles 3a and 3b, and 3b and 3c, respectively, and they are then pressed together so that the corner pieces 4a and 4b are inserted into the slot between the flanges 11 and 12 of the frame profiles, the corner pieces wedging into this slot and thus forming a tight and fast joint between the frame profiles 3a - 3c. Similarly, the fourth frame profile not shown in the figure is mounted at the same time onto the profiles 3a and 3c.

The hatch 7 can be made for instance of the same ceiling board material as the rest of the ceiling, whereby it can be formed of the material removed while

making an opening for the hatch frame 2. The hatch 7 can also be made of some other material that can be painted or coated like the rest of the ceiling so that the hatch will be as trim, inconspicuous and indistinguishable from the rest of the ceiling as possible. The hatch 7 can be pushed into place for instance after the hatch frame 2 has been mounted by pushing it diagonally in the vertical direction through the opening of the hatch frame 2 and then by turning it in the appropriate direction and position.

Figure 2 shows a partial view of the hatch construction of the invention seen from below, thus revealing how the frame profiles 3a - 3c are connected to each other, forming a neat area between the ceiling board 1 and the hatch 7. The partially cut area in the figure also shows how the corner piece 4b is disposed in the angle between the frame profiles 3b and 3c so as to form a tight, unbroken joint.

In the description above and the drawing, the invention has been illustrated only by way of an example, and is by no means so restricted. Instead of the fixing screw 9 and the mounting corner 10, for instance different wedges or other suitable mounting elements can be used to secure the hatch frame 2 firmly by means of the force acting against the upper surface of the ceiling board so that the outer flange 5 of the frame presses against the surface of the ceiling board 1. As shown in Figure 1, the inner flange is preferably at a slight angle towards the ceiling board so that the edge of the outer flange 5 comes into as close a contact with the ceiling board 1 as possible and, if desired, can be made to press to some extent into the ceiling board in order to better disguise the boundary.