The present invention relates to foldable stairs, in particular a ladder-like stairs embedded in a substantially horizontal frame mounted in a ceiling, and in particular in a deep frame apt to a thick ceiling such as ceiling provided with thermal insulation. Stairs of this kind are used mainly as attic entrances.

BACKGROUND OF THE INVENTION

Patent specification GB 2 319 051 discloses a folding attic stairway comprising three stairway portions connected by hinges, where the upper stairway portion is mounted on the inner stairway carrying frame which is pivotally mounted by a hinge on the outer frame for mounting in a ceiling open. The uppermost step of these stairs is the uppermost step of the upper stairway portion mounted to the inner stairway carrying frame. Also the Polish patent specification PL 199927 B1 discloses foldable stairs having the uppermost step fixed to the uppermost stairs segment. If there is a need to use a deep stairway carrying frame, e.g. to be mounted in a ceiling provided with thick thermal insulation, the height between the uppermost step of the stairs and the top edge of the frame is known, prior art solutions substantially extend the step pitch of the stairs.

SUMMARY OF THE INVENTION

The invention provides foldable stairs, in particular foldable stairs embedded in a frame, in particular in a deep frame having increased wall height, comprising stairs segments movable with relation to each other, wherein the uppermost stairs segment is rotationally connected with the frame, which are provided with a movable step pivotally connected to the internal surface of the wall of the frame. The uppermost stairs segment is preferably attached to the cover that adheres to said frame in the stairs closed state and is connected by means of a hinge mechanism with the frame and the movable step is supported by at least one supporting element connected to the cover. The movable step is positioned in such a manner that the distance between the tread of the movable step and the tread of the uppermost step of the uppermost stairs segment substantially corresponds to the step pitch of the stairs. In the stairs closed state, remaining stairs segments are positioned within the frame, above the uppermost stairs segment and in the stairs unfolded, opened state remaining stairs segments are positioned below the uppermost stairs segment in an aligned relation forming a sloped line of stairs. The stairs are also provided with a mechanism, preferably a spring mechanism, that supports lifting up of folded stairs to the stairs closed state and at least partially counterbalances the weight of the stairs during opening thereof. Preferably the stairs are also provided with tie rod arrangement that restricts the opening limits of the stairs.

In one embodiment of the invention, said supporting element of the movable step is the uppermost stairs segment and the movable step is preferably supported by hinged connectors coupling the uppermost stairs segment, preferably stringers of this segment, with the movable step. In the opened state of the stairs (unfolded for use) the hinged connectors are preferably substantially aligned with the stringers of the uppermost stairs segment. Geometrical axis of the stringers of the uppermost segment of the stairs crosses the top surface of the tread of the movable step in the proximity of the centre of its width so that the pressure on this step is transferred mainly on the uppermost stairs segment and only to a limited extent through the joint of this, step on the frame mounted in a ceiling.

In another embodiment of the invention, said supporting element of the movable step is the uppermost stairs segment and the movable step is provided with supporting legs and in the opened state of the stairs the supporting legs are substantially aligned with the stringers of the uppermost segment of the stairs and abut the frontal top surfaces of the stringers. In the opened state of the stairs unfolded for use the geometrical axis of the stringers of the uppermost segment of the stairs crosses the top surface of the tread of the movable step in the proximity of the centre of the width of the tread which has the same advantageous effect of transferring pressure as in the embodiment above. In the closed (folded) state of the stairs the tread of the movable step adheres to the frame wall from inside and the supporting legs have no contact with the uppermost segment of the stairs. In yet another embodiment of the invention, said supporting element of the movable step is at least one bracket attached to the cover connected by means of a hinge mechanism with the frame. The movable step is supported by hinged connectors PL_FK02PCT - 3 - coupling the movable step with this bracket or brackets. Preferably the hinged connectors are substantially aligned with the stringers of the uppermost stairs segment in the opened state of the stairs. The width of the tread of the movable step as well as the distance between the tread and the inside surface of the frame are selected in such a manner that the geometrical axis of the stringers of the uppermost segment of unfolded stairs crosses the top surface of this tread in the proximity of the centre of the width thereof which has the same advantageous effect of transferring pressure as in the embodiments above.

The foldable stairs with an additional movable step according to the present invention are much more convenient than known stairs since the movable step facilitates walking up onto the surface above the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated below with reference to the preferred embodiments thereof that should not be considered in any way as limitative and with reference to the attached drawings on which:

Fig. 1 shows an axonometric schematic view of the first embodiment of the foldable stairs according to the invention having a movable step and hinged connectors, in opened state but with stairs segments folded on the cover,

Fig. 2 shows a side view of the stairs from Fig. 1 in opened state but with stairs segments in intermediate state of opening or closing,

Fig. 3 shows a side view of the stairs from Fig. 1 almost in closed state with stairs segments folded on the cover,

Fig. 4 shows a side view of the stairs from Fig. 1 in closed state with stairs segments folded on the cover,

Fig. 5 shows a side view of another embodiment of the foldable stairs according to the invention having a movable step with supporting legs fixed to a movable step tread in opened state but with stairs segments folded on the cover, and

Fig. 6 shows a side view of the stairs from Fig. 5 in closed state with stairs segments folded on the cover. PL_FK02PCT - 4 -

Another embodiment of the foldable stairs according to the invention has not been depicted on the drawings but is thoroughly described with reference to the common and different features of the embodiments illustrated on drawings.

Embodiment 1 Foldable stairs shown in Fig. 1 comprise a frame 1 embedded horizontally in a ceiling of a building, wherein the walls of the frame are relatively deep due to a thick ceiling or necessity of providing that the walls extend over the top surface of the ceiling. From the bottom, the frame 1 can be closed by a cover 2 which is connected to the frame by means of a hinge mechanism and tie rod arrangement that restricts the opening limits of the cover 2. The arrangement connecting the frame 1 with the cover 2 also comprises springs that support lifting up the cover with folded stairs segments to the closed state and also counterbalance the weight of the cover 2 and the stairs during opening thereof. In this embodiment the stairs comprise three segments, wherein the uppermost stairs segment 3 is fixed to the cover 2. The number of segments and a method of connection between the segments and the cover are irrelevant to the subject of the present invention.

Within the interior of the frame 1 a movable step 4 is positioned. The movable step 4 is pivotally connected to the internal surface of the wall of the frame 1 and supported on the uppermost stairs segment 3 by means of two hinged connectors 5 that connect stringers (side beams) of this segment with lugs of the movable step 4 located below a tread 41 of the movable step 4. In opened state of the stairs, the hinged connectors 5 are substantially aligned with the stringers of the uppermost stairs segment 3 (cf. Fig. 1 and Fig. 2) wherein the tread 41 of the movable step 4 is oriented substantially horizontally as the treads of the remaining steps of unfolded stairs segments.

The width of the tread 41 as well as the distance between the tread 41 and the inside surface of the frame 1 are selected in such a manner that the geometrical axis of the stringers of the uppermost segment 3 of the stairs crosses the top surface of the tread 41 in the proximity of the centre of its width. The distance between the tread 41 of the movable step and a tread 31 of the uppermost step of the uppermost stairs segment 3 is selected to correspond to the step pitch of the stairs. PL_FK02PCT - 5 -

When the folded stairs are lifted in order to place them within the frame 1 , the hinged connectors 5 lift up the movable step 4 (cf. Fig. 3), and in closed state where the cover 2 is closed and stairs segments are positioned in the frame 1 , the connectors are oriented substantially vertically. Also the stair tread 41 is then oriented substantially vertically inside the frame 1 in a close proximity of the frame wall (cf. Fig. 4).

The foldable stairs are additionally provided with a telescopic handrail (not shown in the drawings) which is jointedly connected with two segments of the stairs. A spring positioned inside the handrail supports lifting up and folding all the stairs segments but the uppermost one, as well as counterbalances the weight of these segments while unfolding the stairs.

Embodiment 2

Similarly as in the Embodiment 1 foldable stairs presented in Fig. 5 comprise a deep walled frame 1 embedded horizontally in a ceiling of a building and closable from the bottom by a cover 2 connected to the frame by a hinge mechanism and tie rod arrangement that restricts the opening limits of the cover 2. The uppermost stairs segment 3 is fixed to the cover 2 and in this embodiment the stairs also comprise three segments but obviously the number of segments and their mutual connections are irrelevant to the subject of the present invention. A movable step 6 is connected pivotally inside the frame 1 at the internal surface of the wall thereof and supported by the uppermost stairs segment 3 by means of two supporting legs 61 fixedly connected to the movable step 6. When the stairs are in the opened state the supporting legs 61 are substantially aligned with the stringers of the uppermost stairs segment 3 (cf. Fig. 5) wherein a tread 62 of the movable step 6 is oriented substantially horizontally as the treads of the remaining steps of unfolded stairs segments.

The width of the tread 62 as well as distance between the tread 62 and the inside surface of the frame 1 are selected in such a manner that the geometrical axis of the stringers of the uppermost segment 3 of the stairs crosses the top surface of the tread 62 in the proximity of the centre of its width. The distance between the tread 62 of the movable step and a tread of the uppermost step of the uppermost stairs segment 3 is selected to correspond to the step pitch of the stairs (i.e. the rise height of the stars). Additionally the supporting legs 61 can be provided with a mechanism for adjusting their length, e.g. by means of adjusting screws driven from the side of the stringers of the uppermost segment 3. The foldable stairs are additionally provided with a telescopic handrail (not shown in the drawings) as in the Embodiment 1.

Folding the stairs in order to hide them within the frame 1 should be preceded by turning the movable step 6 to a position in which its tread 62 is oriented substantially vertically inside the frame 1 close to the frame wall (cf. Fig. 6). In this position the supporting legs 61 of the movable step 6 will be positioned above the space provided for the stair segments in closed state of the stairs.

Embodiment 3

Similarly as in the Embodiment 1 foldable stairs comprise deep walled frame embedded horizontally in a ceiling of a building and closable from the bottom by a cover connected to the frame by a hinge mechanism and tie rod arrangement that restricts the opening limits of the cover. The uppermost stairs segment is fixed to the cover.

Furthermore brackets are fixed to the cover alongside stringers (side beams) of the uppermost stairs segment. Within the interior of the frame a movable step is positioned. The movable step is pivotally connected to the internal surface of the wall of the frame and supported on the brackets by means of two hinged connectors that connect the brackets with lugs of the movable step located below a tread of the movable step 4.

The width of the tread of the movable step as well as the distance between this tread and the inside surface of the frame are selected in such a manner that geometrical axis of the stringers of the uppermost segment of the unfolded stairs crosses the top surface of the tread in the proximity of the centre of its width. Functionality of the movable step in all its positions is identical as in the Embodiment 1. Similarly as in the Embodiment 1 the foldable stairs are additionally provided with a telescopic handrail.