Patent Description:
As it is well known, a trapdoor is installed at openings in walls in such a way as to provide access to a compartment behind the wall, thus allowing for the inspection of electrical, plumbing or similar systems installed in the compartment.

Each frame consists of four sections arranged at right angle and connected by means of corner pieces comprising two <NUM>° wings, each one being connected to two adjacent sections.

The connection of a wing of the corner piece to the respective section can be made by means of threaded fastening means (screws or bolts), by means of welding or, in the case where at least one section has a C-section defining a longitudinal seat that is open at the ends, by inserting the wing of the corner piece into the end of the longitudinal seat.

Trapdoors are also provided with elements or inserts connected to the sections of the frames such as:.

Said secondary elements can be connected to the sections by means of threaded connection means (screws and bolts) or by means of welding. Both connection methods, however, are rather inconvenient since the threaded connection is a complicated and time-consuming operation and also involves drilling the elements, affecting both the elements and the sections and severely impairing the aesthetics of the trapdoor, whereas the connection by means of welding involves making an irreversible junction that, once the element is welded, prevents the element from being replaced or removed in case one wants to change the structural setting of the trapdoor.

In cases where one of the two frames comprises at least one C-shaped section, another solution can be used to connect the secondary element to the section of the frame. Such a solution provided for equipping the secondary element with a slider that corresponds to the longitudinal seat of the section so that it can be inserted into the longitudinal seat, passing through the ends of the longitudinal seat, before the trapdoor is assembled. It is obvious, however, that this solution cannot be used in the case where the trapdoor is already assembled because the access to the ends of the longitudinal seat would be obstructed by the wings of the corner pieces.

<CIT> describes an access door suitable for being installed in a wall. The access door comprises a fixed outer frame comprising sections and corner pieces, a movable inner frame comprising sections and corner pieces, and a panel supported by the movable inner frame. Said document discloses thereby an assembly according to the preamble of claim <NUM>.

It is precisely from the careful observation of the problems faced by trapdoors of the prior art that the present invention was devised, the purpose of which is to provide a new solution that allows an insert to be connected to a section with a C-shaped section of the fixed or movable frame of the trapdoor in a simple and fast manner even when the trapdoor is already assembled.

More specifically, it is the purpose of the present invention to devise a trapdoor-insert assembly in which the insert can be easily and quickly attached to a section of the fixed or movable frame of the trapdoor even when the trapdoor is already assembled, avoiding the use of welding and/or threaded connection means.

A further purpose of the present invention is to devise a trapdoor-insert assembly that is inexpensive, simple and quick to make.

These purposes are achieved in accordance with the invention with the features listed in the attached independent claim <NUM>.

The trapdoor-insert assembly according to the invention is defined by claim <NUM>.

For the sake of explanatory clarity, the description of the trapdoor-insert assembly according to the invention continues with reference to the attached drawings, which have only illustrative and non-limiting value, wherein:.

With reference to the attached figures, a trapdoor-insert assembly is described according to the invention.

Referring to <FIG>, <FIG>, <FIG>, the trapdoor-insert assembly comprises a trapdoor (<NUM>) comprising:.

The fixed frame (<NUM>) and the movable frame (<NUM>) each comprise four sections (3a, 3b) and four corner pieces (5a, 5b).

Each corner piece (5a, 5b) connects two adjacent sections (3a, 3b) in perpendicular position.

Referring to <FIG>, each section (3a, 3b) has a C-shaped cross-section and comprises a longitudinal seat (<NUM>) that is defined by a bottom wall (<NUM>) and two sidewalls (<NUM>). The sidewalls (<NUM>) comprise two projecting wings (<NUM>) in opposite parallel position that extend along the entire length of the section and define a narrowed inlet (30a) giving access to the longitudinal seat (<NUM>).

Preferably each section (3a, 3b) has ends cut at <NUM>°. Each corner piece (5a, 5b) comprises a central portion (<NUM>) suitable for abutting said ends (<NUM>) of two adjacent sections (3a, 3b) and two side inserts (<NUM>) that protrude from the central portion (<NUM>) so as to fit from the ends (<NUM>) of the sections (3a, 3b) inside the longitudinal seat (<NUM>) to mate with the sections (3a, 3b).

With particular reference to <FIG>, the connection means (C) comprise suspension fittings (<NUM>, <NUM>) arranged between the movable frame (<NUM>) and the fixed frame (<NUM>) in corner areas adjacent to each other and arranged at the back side (LP) of the trapdoor (<NUM>). The suspension fittings (<NUM>, <NUM>) are conformed in such a way to tilt the movable frame (<NUM>) relative to the fixed frame (<NUM>) without uncoupling the movable frame (<NUM>) from the fixed frame (<NUM>).

The suspension fittings (<NUM>, <NUM>) specifically comprise:.

The first section of the first piece (<NUM>) is attached to the corner piece (5a) of the fixed frame (<NUM>), and the second section of the first piece (<NUM>) interferes with the corner piece (5b) of the movable frame (<NUM>).

The first section of the second piece (<NUM>) is attached to the corner piece (5b) of the movable frame (<NUM>), and the second section of the second piece (<NUM>) interferes with the corner piece (5a) of the fixed frame (<NUM>).

With reference to <FIG>, <FIG>, and <FIG> the corner areas of the front side (LA) of the trapdoor (<NUM>) can be provided with locking means (B) conformed in such a way as to lock the movable frame (<NUM>) relative to the fixed frame (<NUM>) in the closing position.

Said locking means (B) comprise a hook (B1) provided on the movable frame (<NUM>) that interacts with a corresponding elastic fastening device (B2) of click clack type provided on the fixed frame (<NUM>). The fastening device (B2) is conformed in such a way to retain the hook (B1) while still allowing the hook (B1) itself to be released and thus the movable frame (<NUM>) to be opened when a user pulls on the movable frame (<NUM>) with a force that overcomes the resistance of elastic means of the fastening device (B2). Said locking means (B) are known to a technician of the field and therefore will not be described in detail in the present invention.

Referring to <FIG>, <FIG>, <FIG>, the trapdoor-insert assembly (<NUM>) according to the invention also comprises an insert (<NUM>) which is connected to the section (<NUM>).

The insert (<NUM>) comprises an operating portion (4p) and a coupling body (<NUM>) comprising two retaining teeth (<NUM>) that extend along parallel and opposite directions to each other and are engaged below the two projecting wings (<NUM>), respectively. Otherwise said, each retaining tooth (<NUM>) is interposed between a projecting wing (<NUM>) and the bottom wall (<NUM>) of the section (<NUM>).

The coupling body (<NUM>) is suitably shaped to allow the retaining teeth (<NUM>) to move closer together until they reach an arrangement in which the volume in width of the two retaining teeth (<NUM>) is less than the width of the narrowed inlet (30a) so that said retaining teeth (<NUM>) can first cross the narrowed inlet (30a) along a direction that is orthogonal or incident to the bottom wall (<NUM>) and then, once they have crossed the narrowed inlet (30a), they can move away from each other in order to be engaged below the projecting wings (<NUM>).

In the preferred embodiment said coupling body (<NUM>) is of elastic type and is conformed in such a way as to allow a user to bring the two retaining teeth (<NUM>) closer together by overcoming the elastic resistance offered by the elastic coupling body (<NUM>) and then, after crossing the narrowed inlet (30a), release the coupling body (<NUM>) so that the retaining teeth (<NUM>) move away and elastically engaged in place below the projecting wings (<NUM>).

The coupling body (<NUM>) comprises two opposing, elastically flexible legs (42b), each one ending with said retaining teeth (<NUM>). Each retaining tooth (<NUM>) forms a dihedral angle (γ) comprised between <NUM>° and <NUM>° with an end section of the corresponding leg (42b).

More precisely, the coupling body (<NUM>) comprises an elastic clip comprising an omega-shaped plate (<NUM>) with a central axis (Y) and comprising said two legs (42b) terminating with said retaining teeth (<NUM>) and a top portion (42a) connecting the two legs (42b).

In an alternative embodiment of the invention, shown in <FIG>, instead of comprising said omega-shaped plate (<NUM>), the coupling body (<NUM>) may comprise two rigid legs (<NUM>) movably connected to each other, which terminate with said retaining teeth (<NUM>) and between which an elastic means (M) (such as a spring) is provided to constantly exert a repulsive action such that the two legs (<NUM>) are maintained in their maximum diverged position. The two legs (<NUM>) are connected to each other by means of a pin (P). The spring (M) is loaded by bringing the two legs (<NUM>) closer together (see <FIG>) in such a way that, as soon as the legs (<NUM>) are released, the spring (M) exerts a repulsive action such to restore the position of the legs (<NUM>) shown in <FIG>.

Optionally, in order to prevent the coupling body (<NUM>) from sliding along the longitudinal seat (<NUM>) of the section (<NUM>), the projecting wings (<NUM>) can be deformed to define a protrusion that protrudes inside the longitudinal seat (<NUM>) and is coupled by interference with the retaining tooth (<NUM>) of the coupling body (<NUM>) arranged below the projecting wing (<NUM>).

With reference to <FIG>, <FIG>, <FIG>, said insert (<NUM>) consists of an end-strop element conformed in such a way as to stop the opening travel of the movable frame (<NUM>) in order to prevent an injury in the event of accidental disengagement of the movable frame (<NUM>) from the fixed frame (<NUM>).

In such a case, the coupling body (<NUM>) of the insert (<NUM>) is attached to a section (3b) of the movable frame (<NUM>) arranged at the front side (LA) of the trapdoor (<NUM>), and the operating portion (4p) of the insert (<NUM>) comprises an arm (<NUM>) which protrudes from the coupling body (<NUM>) and is shaped to intercept the fixed frame (<NUM>) when the movable frame (<NUM>) moves from the closing position to the opening position so as to stop the opening travel of the movable frame (<NUM>).

With particular reference to <FIG> the arm (<NUM>) comprises:.

In order to increase the rigidity of the arm (<NUM>), said arm (<NUM>) is provided with a central median partition <NUM>) with gradually increasing height going from the first section (<NUM>) to the second section (<NUM>) of the arm (<NUM>).

With reference to <FIG>, other examples of inserts (<NUM>) are shown, which differ from the insert (<NUM>) shown in <FIG>, <FIG>, <FIG> in that the operating portion (4p) is connected to the coupling body (<NUM>). In such a case, the two inserts (<NUM>) act as auxiliary locking means that can be used as an alternative to the locking means (B) or even together with the locking means (B) to ensure a more stable and effective locking of the movable frame (<NUM>) in the closing position.

In such a case the two inserts (<NUM>) comprise:.

It should be noted that although inserts acting as end-stop means or locking means have been shown as inserts (<NUM>) in this patent application, the inserts may also consist of inserts with different functions, changing the configuration of said operating portion (4p). By way of example, as shown in <FIG>, the operating portion (4p) may consist of parallelepiped blocks (4t) projecting from the coupling body (<NUM>) and overhanging the adjacent section in order to act as anti-warping means of the trapdoor (<NUM>).

To assemble the trapdoor-insert assembly according to the invention, firstly the trapdoor (<NUM>) is assembled and then, once the trapdoor (<NUM>) is assembled, the insert (<NUM>) is provided.

With reference to <FIG>, the following operations are performed in order to attach the insert (<NUM>) to one of the sections (3a, 3b) of the fixed frame (<NUM>) or of the movable frame (<NUM>):.

In the specific case where the coupling body (<NUM>) is of elastic type, the retaining teeth (<NUM>) are brought closer by exerting an approaching thrust on the retaining teeth (<NUM>), overcoming the elastic resistance offered by the elastic coupling body (<NUM>), whereas the retaining teeth (<NUM>) are automatically moved apart by interrupting the approaching thrust on the retaining teeth (<NUM>). As a matter of fact, by interrupting the approaching thrust, the coupling body (<NUM>) returns to its idle state and the retaining teeth (<NUM>) are diverged and automatically and elastically engaged below the projecting wings (<NUM>) of the sidewalls (<NUM>) of the section (3a, 3b).

Although in <FIG> that the retaining teeth (<NUM>) simultaneously pass through the narrowed inlet by approaching the insert along a direction orthogonal to the bottom wall, it is also possible to tilt the insert (<NUM>) so that one retaining tooth (<NUM>) is engaged below one of the two projecting wings (<NUM>) and then bring the two retaining teeth (<NUM>) closer together so that also the other retaining tooth (<NUM>) can also pass through the narrowed inlet (30a) and engage below the other projecting wing (<NUM>).

Finally, it should be noted that, although the appended figures show that the coupling body (<NUM>) is of elastic type, in an alternative version of the invention said coupling body (<NUM>) may comprise adjusting and locking means that allow the retaining teeth (<NUM>) to be moved apart from each other and closer together. It is meant that, by way of example, said retaining teeth (<NUM>) may be mounted on two legs that are hinged to each other and can be lockable in more or less divergent position by means of special locking means arranged between the two branches.

As a result of the above description, it becomes evident how the present invention succeeds in achieving its intended purposes.

Claim 1:
Trapdoor-insert assembly comprising a trapdoor (<NUM>) comprising:
- a front side (LA) and a back side (LP):
- a fixed frame (<NUM>) suitable for being fixed to a wall in a wall opening,
- a movable frame (<NUM>) disposed in the fixed frame (<NUM>),
- a panel (E) mounted on said movable frame (<NUM>), and
- connection means (C), which are arranged at the back side (LP) of the trapdoor (<NUM>) and connect the movable frame (<NUM>) to the fixed frame (<NUM>) so that the movable frame (<NUM>) can be moved between an opening position and a closing position;
wherein at least one of said frames (<NUM>, <NUM>) comprises at least one section (3a, 3b) having a longitudinal seat (<NUM>) defined by a bottom wall (<NUM>) and by two sidewalls (<NUM>); wherein the assembly comprises an insert (<NUM>) which is connected to the section (<NUM>) and comprises an operation portion (4p) and a coupling body (<NUM>);
characterized in that said two sidewalls (<NUM>) comprise two projecting wings (<NUM>) in opposite parallel position that extend for the entire length of the section and define a narrowed inlet (30a) giving access to the longitudinal seat (<NUM>);
whereby said coupling body (<NUM>) comprises two retaining teeth (<NUM>) that extend along opposite directions and are engaged under the two projecting wings (<NUM>); wherein said coupling body (<NUM>) is configured in such a way that:
- the retaining teeth (<NUM>) can be moved closer to each other until they reach a position wherein said retaining teeth (<NUM>) can pass through the narrowed inlet (30a) along a coupling direction that is incident to the bottom (<NUM>) of the section (<NUM>); and
- the retaining teeth (<NUM>) can be moved apart in order to be engaged under the projecting wings (<NUM>).