EP1709259A1

EP1709259A1 - Foldable step device such as a staircase or ladder

Info

Publication number: EP1709259A1
Application number: EP04805468A
Authority: EP
Inventors: François ROS
Original assignee: Ros Francois
Current assignee: ROS, FRANCOIS
Priority date: 2003-11-25
Filing date: 2004-11-17
Publication date: 2006-10-11
Anticipated expiration: 2024-11-17
Also published as: FR2862679B1; WO2005054595A8; FR2862679A1; WO2005054595B1; EP1709259B1; WO2005054595A1

Abstract

The step device, such as a ladder (1) or staircase, comprises at least two parts (2, 3, 4), both of which are provided with two longitudinal struts(6) and several steps (7) and which can be folded on top of each other due to hinge-type means (5). The width (L) of a step (7) with a supposed zero thickness is greater than e/sin alpha and, at the most, substantially equal to n.e/sin alpha, e being the width of a longitudinal strut (6), alpha being the angle of inclination between the longitudinal direction of the strut (6) and the plane of said step (7) and n being the number of parts. In the extreme top part (4), the steps (7) partially exceed a first same side of the struts (6) and in the extreme bottom part (2), they (7) partially exceed a same second (C2) or even first (C1) side of the struts (6). The steps of the superposed parts (2, 3, 4), when folded are inserted between each other. As a folding staircase, the device can be coupled to a pivoting trap door or a frame inside which a pivoting trap door is mounted.

Description

FOLDABLE STEP DEVICE, STAIRCASE OR LADDER TYPE

The present invention relates to the field of walking devices, that is to say stairs and ladders, said to be foldable because they comprise several longitudinal portions which, in the storage position, are superposed on each other then that in normal position said longitudinal portions are aligned. It relates more particularly to a device of this type having a reduced size in the storage position. It relates in particular to a foldable retractable staircase, the small size of which allows its integration into a ceiling. A retractable staircase is generally used to allow access to the attic, the staircase was not provided for in the original construction. An opening is made in the ceiling, which is closed by an access hatch, generally pivoting relative to one side of the opening. Above this hatch and in the opening frame, a foldable staircase is installed in the storage position. The user just needs to open the hatch and deploy the staircase to be able to climb into the attic. . There are several types of retractable stairs. The most common type has the conventional structure of a ladder, with two longitudinal uprights between which are fixed steps which are wider than the simple bars of a ladder. Intermediate joints delimit several foldable parts one on the other. The number of parts and therefore the number of articulations depends on the height under ceiling of the part being under the hatch and also on the dimension of this one. Most generally, such a retractable staircase has three parts connected to each other by two sets of two joints. When deploying the staircase, the upper end of the latter must remain integral with the fixed frame fixed in the opening made in the ceiling while the lower end rests on the floor of the room in which the staircase has been deployed. In an alternative embodiment, the upper end part of the staircase is fixed to the upper face of the pivoting hatch, that is to say that which is turned towards the roofs. However, it is necessary for this attachment to provide sufficient spacing between the upper face of the hatch and this upper upper part of the staircase so that the user, when taking the stairs, is not hampered by the presence of this hatch, which can easily be grabbed from the side uprights with the hands and not likely to come up against the hatch with the feet. In another alternative embodiment, the upper end of the staircase is pivotally attached to the fixed frame constituting the frame of the opening, the retractable staircase then being independent of the hatch. Whatever the variant, the retractable staircase, in the folded state, when it is positioned above the closed hatch occupies a large space, which generally requires the installation of a box and which , consequently, obliges to sacrifice surface in the arranged roof spaces. Of course it would be possible to limit the size of the steps, like the bars of a ladder, but this would be to the detriment of the comfort of the user. It is therefore important that the steps of the device have a normal dimension for a staircase , at least of the order of 80 mm in width. The object of the present invention is to provide a device with steps, which, under the aforementioned conditions, has a reduced bulk. This object is perfectly achieved by the device of the present invention which, in known manner, comprises at least two parts, each comprising two longitudinal uprights and several steps fixed between said uprights and which are foldable one on the other thanks to means of articulation. Characteristically, according to the invention, the width (L) of a step, this being assumed to be zero thickness, is on the one hand greater than e / sin and on the other hand, at most, substantially equal à ne / sin α, e being the width of a longitudinal upright, α being the angle of inclination between the longitudinal direction of said longitudinal upright and the plane of said step and n being the number of parts. In the upper extreme part, in the deployed position, the steps partly protrude on the same first side (Ci) of the uprights, and in the lower extreme part, the steps partly protrude by the same second side (C ₂ ) or on the same first side (Ci) of the uprights, the steps of the superimposed parts, in the folded position, being intercalated with one another. When the device is in the folded state, the steps of the upper end part extend between the longitudinal uprights of the other part or parts, but without exceeding or slightly exceeding the longitudinal uprights of the lower end part. They may possibly slightly exceed the longitudinal uprights on which they are fixed, in particular in the case of the retractable staircase fixed on a pivoting hatch, as will be indicated below. The upper end part designates the part of the device which is at the top of the latter when it is used in the deployed position and vice versa the lower end part designates the one which is in contact with the ground in this position. By intermediate part is meant the part or parts which are situated between the lower end part and the upper end part. According to the particular arrangement of the present invention, the total size of the device is substantially equivalent to what one could obtain from a conventional ladder with bars in which the width of a bar is at most equal to that of a amount, while, in this case, the steps have a width such that they exceed the amounts. For a number n of parts, the total size of the device is substantially of the order of n times the width of an upright, it being understood that said steps are inclined relative to the longitudinal direction of the upright to take account of the normal inclination of the device in the position of use. The angle α of inclination of the longitudinal upright with the walking plane is generally 70 °, which corresponds to an angle β of inclination of the longitudinal upright with the vertical of 20 °, α and β being complementary. Being a longitudinal upright having a width e, taken perpendicular to the longitudinal axis of its outer face, each step has a width L corresponding at most, substantially to the formula: L = ne / sin α Knowing that in this formula, the step is assumed to be zero thickness, in practice it is necessary to take into account the thickness and the walking configuration. For example, the width L of the step is 80 mm for a longitudinal upright of width e 25 mm in a three-part device, for a value of α of the order of 70 °, knowing that α can vary, depending on the constructions, between 60 ° and 75 °. In a specific embodiment, the device comprising three parts, the steps of the intermediate part protrude on either side of the longitudinal uprights, preferably in the same proportion. It should be noted that, for reasons of mechanical strength, even if the number of parts n is greater than 3, in particular is equal to 4, it is preferable to limit the width L of each step to the value 3e / sin α. The different parts of the device can have lengths of longitudinal uprights which are identical or different. In the latter case, it is possible to have parts which will be offset with respect to each other, in the position of the superimposed uprights, on one side as on the other. The positioning of the first step and the last step, and the interval between two successive steps are not entirely imperative, the standards in force providing for a range of values. In this way, it is possible to choose the values of these different parameters, and the length and the offset of the longitudinal uprights of each part to obtain, for a number n of parts, the superposition of the uprights with the steps inserted in accordance with the invention. In the case where n is greater than 2, the steps of the upper extreme part generally project beyond the first side (Ci) corresponding to the direction facing the user, while the steps of the intermediate part or parts extend beyond the second side (C ₂ ) either on either side of the longitudinal uprights, or possibly on the first side (Ci). It is another object of the present invention to provide an installation comprising a retractable staircase, in accordance with the above-mentioned characteristics, the upper upper part of which is fixed to the upper face of a pivoting hatch by connecting means, pivotally articulated between two positions, a first position - deployed staircase - in which the hatch and the longitudinal uprights have a first spacing between them and a second position - folded staircase - in which the hatch and the longitudinal uprights have a second distance between them, less than the first distance. Thus during the folding of the retractable staircase, it is possible to reduce the total size not only of the staircase itself but also of the staircase and the hatch, thanks to the passage of the connecting means from the first to the second position. Preferably, the installation comprises two connection means articulated by longitudinal upright. Each connecting means comprises two studs connected by at least one link, preferably two links, the first stud being fixed on the hatch and the second under the longitudinal upright. The first pivot axis of the rod is connected either to the outside of the second stud or to the outside of the longitudinal post. The second pivot axis is connected to the outside of the first stud. The link is perpendicular to the hatch and to the longitudinal upright in the first position, staircase extended. In addition, the installation comprises means for blocking the link, at least in the first position. In a preferred embodiment, the first stud has its oblique upper face and the locking means consist of the second stud fixed under the longitudinal upright and which has an oblique upper face, parallel to that of the first stud, so that in the first position, the upper faces of the two studs are engaged one against the other. Thus, in this particular configuration, the two studs when they bear against one another constitute a transverse spacer between the hatch and the corresponding longitudinal upright. In the folded position, due to the pivoting of the link, the two studs separate. In the case where the two studs are of the same dimension, in the folded position, the longitudinal upright rests on the first stud while the second stud is applied to the upper face of the hatch. In this case, the steps fixed on the upper extreme part, like those of the other parts, in the folded device position, can extend towards the hatch by a distance at most equal to d / sin α or by a distance lower, this last dimension is to be considered taking into account that the tread is of zero thickness, which makes it possible to have a tread width L somewhat greater than the value given above, by the formula L = ne / sin α, due to the spacing d between the hatch and the longitudinal uprights. It is of course necessary that this overflow of the steps towards the hatch is compatible with the superposition of the longitudinal uprights and does not cause unacceptable shocks, in particular on the angle frame. It is another object of the present invention to provide an installation comprising a retractable staircase, in accordance with the above-mentioned characteristics, the upper end part of which is pivotally mounted on a frame delimiting an opening formed in a ceiling. The pivot axis can be below or at the level of the last step or between the last and the penultimate step. In the present text, the first step of the staircase is considered to be the one closest to the ground on which the staircase rests. In this latter embodiment, preferably, at least one return spring is used. This spring can for example connect the frame and the upper end of at least one longitudinal upright of said upper end part to facilitate the replacement of the staircase, in the folded position, after use, and to facilitate the descent of the 'stair before deployment of it. The present invention will be better understood on reading the description which will be given of several exemplary embodiments of a step device, of the ladder or retractable staircase type, with reduced bulk illustrated by the appended drawing in which: FIGS. 1 and 16 are very schematic representations of a first example of a folding ladder type in three parts, perspective view and in the unfolded state against a wall (FIG. 1) in side view and in the folded state on the ground (FIG. 16). Figure 2 is a side view of a second example of a retractable staircase type attached to a pivoting hatch. Figures 3 and 4 are front views of the pivoting attachment means between the hatch and the retractable staircase of the second example, respectively in the position of use (Figure 3), in the folded position (Figure 4). Figure 5 is a right view of the fixing means of Figure 3. Figure 6 is a front view of a third example of retractable staircase type pivotally attached to a frame surrounding the opening in a ceiling, the folded state, the last step being above the pivot axis and the hatch being independent of the staircase. Figure 7 is a partial right view of the staircase of Figure 6, in the deployed state, at a first type of articulation between the upper end part and the intermediate part. Figure 8 is a partial right view of the staircase of Figure 9 in the deployed state at a second type of articulation between two parts. FIG. 9 is a front view of a fourth example of the retractable staircase pivotally attached to a frame surrounding the opening made in the ceiling, in the folded state, the last step being below the axis of pivoting and the hatch being independent of the staircase. Figures 10, 11 and 17 are partial sectional and side and front views of the staircase of Figure 9 at the pivoting attachment means on the frame surrounding the opening. Figures 12, 13 and 14 are views, respectively from above (Figure 12), in section along the axis XIII-XIII of Figure 12 and in section along the axis XIV-XIV of Figure 12, of a walking example. Figure 15 is a plan view of the frame and, partially, of the retractable staircase according to the fourth example of Figure 9. In the first embodiment which is illustrated in Figure 1, the device consists of a ladder 1 which has the distinction of having not traditional bars but steps, like a staircase, so as to provide maximum comfort to the user. This folding ladder 1 has three parts 2, 3, 4 between which are hinged means 5, adapted to allow the folding of the ladder 1 on itself. Each part 2, 3, 4 is composed of two longitudinal uprights 6 and, in the example illustrated, only of three steps. In FIG. 1 is illustrated the ladder 1 in its deployed arrangement, the lower end part 2 resting on a horizontal wall 8 while the upper end part 4 rests on a vertical wall 9, for example a wall. In this position, the longitudinal uprights 6 of the three parts 2, 3, 4 are in alignment with one another thanks to the locking in position of the articulation means 5. It should be noted that FIGS. 1 and 16 are not manufacturing plans, the proportions of certain elements, in particular the width L of the steps, having been deliberately exaggerated to facilitate understanding of the invention. The nine steps 7, referenced Ml to M9 in Figures 1 and 16, have a certain inclination, of angle α, relative to the longitudinal direction of the uprights 6. This angle α is generally of the order of 70 °, being complementary to the angle β generally adopted for the installation of a ladder against a vertical wall 9 to ensure a good balance for the user. The value of the angle α may nevertheless vary depending on the devices and possibly the standards in force. In general, the distance between two consecutive steps is substantially the same, to respect a certain stride of the user. In the case of a retractable staircase, the attic floor is considered to be a step for determining this stride. According to the characteristic of the invention, the scale 1 in its folded position, as illustrated in FIG. 16, occupies a reduced overall size, which in this case is the minimum overall size, which strictly corresponds to the superposition of the uprights side 6 of the three parts 2, 3, 4 folded back on themselves. Thus in this first example, the size E of the scale 1 is equal to 3 times the width e of a longitudinal upright 6 and to L. sin α, L being the width of the step. To facilitate understanding, there are shown in solid lines in FIG. 16 the portions of the steps which are fixed to the longitudinal uprights and in dotted lines the portions which protrude from said uprights. More generally, in the case of a scale, E = ne, n being the number of parts of which the foldable scale is composed. In its simplest version, the scale could therefore consist of only two parts. This reduced size is obtained due to the particular arrangement which is given to the steps in each part of the ladder. More precisely, in this first example, as it appears clearly on examining FIG. 1, the steps of the two end parts 2, 4 are fixed on the corresponding longitudinal uprights 6 in cantilever, in a direction of the door -to false which is opposite between the two said end parts, while in the intermediate part 3 the steps protrude on either side of the longitudinal uprights 6. In the example illustrated, the three steps Ml, M2, M3 of the lower end portion 2 are fixed in cantilever on the longitudinal uprights 6, projecting from said uprights; on the second side C ₂ , in the direction facing the vertical wall 9 of the ladder support 1. The last three steps M7, M8, M9 of the upper extreme part 4 protrude from the uprights, on the first side Ci, in the direction facing the user. As for the three intermediate steps M4, M5, M6, they project in a balanced manner on either side of the longitudinal uprights 6. The transition from the deployed position to the folded closed position as illustrated in FIG. 16 is done by pivoting of the articulation means 5, in the direction of the arrows respectively FI between the lower end part 2 and the intermediate part 3 and F2 between the intermediate part 3 and the upper end part 4. In this example, the total size E = do of the ladder folded over the

(Figure 16) is equal to three times the width e of a longitudinal upright 6 and also corresponds to the dimension L sin α. Given the inclination of angle α of each step, of thickness supposed to be zero, the dimension L in width of a step 7 is then substantially equal to 3.e / sin.α. This formula, which is based on a step of zero thickness, must be adapted according to the thickness of the step and its configuration. This first example illustrates the case where the smallest possible footprint is sought for the ladder or the staircase folded back on itself as such, without taking account of its immediate environment, and for a width L of maximum walking. This example of a three-part ladder or staircase is immediately transferable to a two-part ladder or staircase; in this case, the intermediate part 3 of FIG. 1 no longer exists, only the upper extreme part remains, the steps of which extend from a first side, towards the user, and the lower extreme part, the steps of which extend beyond a second side, towards the support wall (in the direction opposite to the user). When the number n of parts is greater than 3, an adequate arrangement of the steps in each part should be adopted. The steps of the upper extremity project in principle always along the first side, which corresponds to the direction facing the user, in the deployed device position. If the number n is a multiple of three, notably equal to six, the arrangement of the steps in the three upper parts can be that of the first example of FIG. 1, and that in the three lower parts can be reversed compared to those of the three upper parts. There is thus, in the folded position, the simple superposition of two three-part devices conforming to that of the example. In practice, even if the number n is greater than three, it is preferable that the length L of the steps is substantially equal to 3e / sin α, mainly for reasons of mechanical strength. In addition, when the number n is greater than 3, in particular equal to 4.5 or

6, it is desirable for the intermediate parts to have improved mechanical strength, for example being produced in tubes of rectangular section of thickness 3mm, while the tubes of the two end parts have a thickness of 2 mm. This is desirable whether said parts are made of steel or aluminum. Furthermore, the length of the longitudinal uprights can vary from one part to another. In the first example illustrated in FIG. 16, the lower end part 2 is slightly longer than the two other parts 3, 4 which are of the same length. This difference in length between the different parts of the ladder or staircase can be taken advantage of, in particular when the number n of parts is greater than 3, to adapt the placement of the steps, with a view to superimposing the uprights and to get the steps to fit well together when folding the ladder or the stairs. In the folded position, this difference in length results in an offset of the different amounts superimposed relative to each other, on one side, as in the case of FIG. 16, or on both sides. In the second example which relates to a retractable staircase, the reduced size which is sought takes account of the fact that this retractable staircase is fixed on a pivoting hatch, as illustrated in FIG. 2. More specifically, the staircase 10 has its end part upper 11 which is fixed to the upper face 12a of a hatch 12 of thickness T, which is intended to close the opening 13 formed in a ceiling 14, said opening 13 being delimited by a frame 15 fixed in said ceiling 14. It can be a wooden hatch, possibly insulated, or treated to have good thermal resistance, but it can also be an aluminum hatch, the thickness of which will be less than that of a wooden hatch. . The frame 15 is in particular of angle iron - equal or uneven - of steel, preferably reinforced by welded gussets 68, to be fixed either on a concrete slab or on the wooden joists of the ceiling. The staircase 10 is fixed to the hatch 12 by means of fixing means 16 which form spacers between the hatch 12 and the upper end part 11 of the ladder 10 so as to provide a space between these two elements 17 which is sufficient to allow the user to take the staircase 10 without being hindered by the presence of the hatch 12, both at the level of the passage of the hands of the user who grab the side uprights 18 of the scale 10 as feet landing on the steps 19. This space 17 has a dimension D which is generally of the order of 50 to 100 mm, bearing in mind that standard DIN 4570 requires that the distance X between the median axis transverse 19a on the upper face 19b of the step 19 to the hatch 12 must be at least 130 mm (Figure 3). The hatch 12 is pivotally mounted relative to the frame 15 thanks to at least one pivot axis 20 which, in the example illustrated, is mounted transversely between the angles forming the frame 15, near the edge 13a of the opening 13. As illustrated in FIG. 2, the upper face 15b of the angles forming the frame 15 is applied to the external face 14a of the ceiling 14. Preferably, the positioning of the pivot axis 20 or portions of the pivot axis (as in the example of FIG. 15) on the frame 15 is determined so that, in the closed hatch position, the lower face 12b of the hatch 12 is flush with the plane of the lower face 15a of the frame 15. The bearings of the pivot axis 20 or portions of the pivot axis are mounted on gussets 84. Similarly, fixing means 67 can be provided in two parts 67a, 67b, as described more precisely in the example of FIGS. 9, 10 , 11, 17. Flat irons 83 (fi gure 6) welded to the frame 32 facilitate the fixing of said frame on a concrete slab. In Figure 2, the hatch 12 is shown in the open position. For its closing, it suffices to rotate it in the direction of arrow F3 around the axis 20 until it reaches a substantially horizontal position for the engagement of closing and locking means not shown. In this closed position, the hatch 12 is slightly recessed inside the frame 15 and the total size of the assembly constituted by the hatch 12 and the retractable ladder 10 corresponds firstly to the thickness (T ) from the hatch 12, for a second part to the space 17 (D) and for a third part to the space (E) of the staircase 10. Optimally, it is sought that the presence of the retractable staircase 10 does not reduce the floor space usable in the upper room, generally attic space, when the hatch 12 is closed. Therefore, the size of the aforementioned assembly - hatch and staircase - which one seeks to reduce to the maximum must be significantly less than the total thickness of the ceiling 14, possibly taking into account the thickness a second hatch or other means for closing the opening 13, at the level of the upper part, hatch or means for closing which would then be in alignment with the floor of said part To obtain if necessary a reduction of the size of the assembly formed by the hatch 12, the space 17 and the staircase 10, according to a preferred embodiment illustrated in Figures 3, 4 and 5, the fixing means 16 are pivotally articulated. More precisely, these fixing means 16 comprise two studs 21, 22 and at least one link, but preferably two links 23. The first stud 21 is fixed on the upper face 12a of the hatch 12 while the second stud 22 is fixed under a longitudinal upright 18 of the upper end 11 of the ladder 10. It is of course understood that there are four fixing means 16 of this type, forming a front pair and a rear pair, each pair being fixed to the same level of the two upper end portions of the longitudinal uprights. The rods 23 are fixed to the stud 21 and to the longitudinal upright 18, on the outer sides of the latter, and the inner sides as appropriate, and this along pivot axes 25, 26. This particular structure of the connecting means 16 allows, when the ladder 10 is in the folded position on the hatch 12, reduce the space 17 by causing the rods 23 to pivot according to the arrow F4, as illustrated in FIG. 3. This angular pivoting makes it possible to move the ladder 10 towards the hatch 12, to an extreme position according to which either the first stud 21 comes into contact against the longitudinal post 18 or else the second stud 22 comes into contact against the upper face 12a of the hatch 12. It can also act of a simultaneous contact when the two studs 21, 22 are strictly the same height. If one seeks to avoid contact of the studs 21, 22 with the uprights 18 and the hatch 12, it is possible to have, in particular on a first stud 21, a stop stop 21d, capable of blocking at least the link 23 in the second position (Figure 4). The link could also be connected not directly to the longitudinal upright 18 but to the second stud 22. It is necessary to prevent the link 23 from pivoting in the opposite direction to the arrow F4, in particular when the scale 10 is placed in the deployed position. . To do this, in the embodiment as illustrated, the upper faces

21a and 22a of the two studs 21, 22 have an oblique inclination such that, when the scale 10 passes from the storage position to the use position, the two upper faces 21a, 22a of the two studs 21, 22 remain constantly parallel and engage one against the other, the two studs 21, 22 then being strictly aligned, as illustrated in FIG. 3. Optimal operation of such a fixing means 16 is obtained with an oblique inclination d 'angle γ making about 17 °. In addition, the opposite edges 21b, 21c and 22b, 22c of the upper faces 21a and 22a of the studs 21, 22 are slightly bevelled 21b, 22b and rounded 21c, 22c to avoid jamming during pivoting and premature wear. It is of course important to take account of this movement of the staircase 10 between its position of use and its storage position to determine its precise positioning on the hatch 12 relative to the dimensions of the frame 15, in particular the length. The choice of material for the construction of the studs must allow their contact without risk of degradation, in particular electrolytic. As it is an aluminum hatch, the stud fixed on the hatch will also be made of aluminum and the other stud or at least the oblique face of the other stud will for example be made of stainless steel if the longitudinal uprights are made of steel. In this case the aluminum stud will have a sheet thickness greater than that of the steel stud. Furthermore, as much as necessary, bronze, steel or aluminum rings are also used, at the pivot axes. The passage of the hatch 12 from the open position as illustrated in Figure 2 to the closed position by pivoting about the axis 20 according to the arrow

F3 is made by usual means, either simply using a pole or by a system using pulleys, a traction cable and possibly springs. As regards the steps themselves, they may be steps of any shape, for example rectangular, or forming part of a trapezoid, for example wooden steps having a thickness of 18 mm, a length of 390 mm. In this case they are screwed or bolted to angles of aluminum or steel, which themselves are welded or bolted to the longitudinal posts, preferably of rectangular or square section, which are themselves of aluminum or steel. The square section is preferred for aluminum uprights. The rectangular section is preferred for steel uprights. Preferably, the width e of the uprights is kept constant whatever the rectangular or square section. In the case of an aluminum upright, it may be necessary to increase the thickness of the tube forming the upright, compared to a steel upright. It can also be, as illustrated in FIGS. 12 to 14, non-slip steps 50 made of aluminum or pressed steel having a thickness of the order of 1.5 mm for steel and 4.5 mm for aluminum welded directly or preferably using a flat iron or an intermediate aluminum plate 51 on the longitudinal uprights. The step 50 has a C-shaped cross section (Figure 13), with aligned oblong hollows 53 (Figure 12). The width L of the step as actually observed with the caliper and taking into account the thickness of the step is a function of the width e of the longitudinal uprights. It can in particular be from 80 to 124 mm (FIG. 12). In a third exemplary embodiment, illustrated in FIG. 6, the retractable staircase 30 has its upper end portion 31 which is fixed, along a pivot axis 33, to the frame 32 delimiting the opening 34 formed in the ceiling 35. A pivoting hatch 36, independent of the staircase 30, makes it possible to close said opening 34 after the staircase 30 has been put in place in its folded storage position. The hatch 36 may have a thickness t smaller than that T of the hatch 12 of the second example, not having to support the load of the stairs. In addition, in this embodiment, there is no need to have a space provided between the hatch and the upper end portion 31 of the staircase 30 insofar as said hatch 36 is folded vertically after its opening and n is therefore not likely to annoy the user when he takes the staircase 30. This embodiment therefore makes it possible to minimize the total size of the assembly constituted by the hatch 36, the staircase 30 and possibly an upper hatch or upper closing means at the level of the attic floor or any other room. The hatch 36, of thickness t, and the staircase 30 when it is placed directly on the hatch constitutes a set of overall dimension equal to (3e + t). Depending on the space available in the ceiling, it is possible to provide for the steps to protrude, the staircase being in the folded position and housed in the opening 34, beyond the superimposed longitudinal uprights, opposite the hatch 36 (towards the attic floor or the upper room). It would even be possible to envisage steps of greater width L which would be cut on demand, according to this space available in the ceiling. Of course, the width of the steps L is determined so as not to hinder the closing of the upper hatch or the folding of the stairs. Whatever the embodiment, it is desirable, but not completely mandatory, to have the same step width for all steps. To absorb the descent of the staircase 30 when it is put in the use position, and also to facilitate its ascent, at least one return spring is provided. In the example illustrated in FIG. 6, it is a spring 37 which connects the upper end 38 of the upper extreme part 31 of the staircase 30 to the adjacent edge 32a of the frame 32. It may be two torsion springs at the pivot pin portions 33. It can also be two tension springs between the joists and a point located on the uprights of the upper extreme part, in particular on the external faces of those here, for example substantially in the middle. It can be a combination of these different possibilities. It should be noted that, in this embodiment, illustrated in FIG. 6, the last step 39 of the scale 30 is located between the upper end 38 and the pivot axis 33. This embodiment is not not exhaustive. In the fourth example in Figure 9, the last step N12 is located below the pivot axis 61. It would also be possible to arrange the last step at the level of the pivot axis. In Figure 7, there is shown a locking part 40, in particular for the staircase 30 allowing the longitudinal uprights to remain aligned in the deployed position. This part has a U shape, at least the lateral uprights 41, 42 of which are hollow tubes of circular or rectangular section. On the external faces of the longitudinal uprights of the ladder 30 are provided - in particular fixed by welding - lugs 43, 44 adapted to be able to penetrate into the interior recess of one or the other tube 41, 42 and arranged on one side and on the other of the articulation means 45. For example, each lug has a tapped blind hole and a threaded rod, passing through the longitudinal upright, enters the tapped hole of the lug; the threaded rod is welded on the inside of the upright and the lug is welded on the outside of the upright. The spacing h between the pins 43, 44 when the ladder is deployed, is equal to the spacing between the axes of the two lateral uprights 41, 42 of the locking piece 40 so that the locking piece 40 can be fix by interlocking on the two pins 43, 44. In the example illustrated in FIG. 7, through holes are provided in at least one pin 44 and a lateral upright 42, for the passage of a pin 46 making it possible to prevent the part 40 to detach from the ladder 30 without positive action from the user, In another embodiment illustrated in FIG. 8, the locking in position is achieved by a ratchet system 54 and with spring 55; moreover, in this case, the lateral uprights 41, 42 internally have springs 56, facilitating the positioning of the locking piece 57 on the pins 43, 44, as well as its unlocking. The implementation of such a locking piece is generally not necessary between the lower end part and the intermediate part due to the different placement of the hinge hinge which acts as a stop. In this example, a spacer 58 connects the two longitudinal uprights at the lug 44, preferably fixed by welding. The same room or another room of different size can be used, according to the same principle, for locking the ladder (figure 16) or the staircase (figures 2, 6, 9) in the folded position . The distance must then be h between the longitudinal axes of the two lateral uprights of said locking piece is equal to either the width e of a longitudinal upright of the scale, or else to e (n - 1) depending on whether the locking piece is engaged respectively on two immediately adjacent longitudinal uprights or on the two extreme longitudinal uprights. In the fourth example illustrated in FIG. 9, the retractable staircase 60 has its last step N12 which is located below the pivot axis 61, mounted on the frame 62. The steps NI to N12 are referenced in said figure and shown with the hatched part of the step attached to the corresponding part of the longitudinal uprights. There may be provided, as reinforcement, at least one and preferably four spacers 90 to 93 mounted transversely on the two longitudinal uprights, in steel or aluminum as the case may be, crossing these. One 91 is close to the pivot axis 61 and prevents the portions 64 of the pivot axis from coming out of their bearings 65. Two other spacers 90, 92 reinforce the region of the articulation means 5 and possibly of the pins . In Figure 9, the spacer 92 is screwed at the joint 5. The fourth spacer 93 located near the first step NI provides better results during buckling tests. By way of example, for steel uprights, the spacers can be tubes of circular section 15/21 made of steel (15mm inside diameter and 21mm outside diameter). Figures 10, 11, 15 and 17 illustrate the pivoting mounting of the staircase 60 on the frame 62. The frame 62 is formed of an angle 63 equal or unequal in L, which could also be in particular a T-profile or U-shaped, reinforced by welded gussets 68, which surrounds the entire opening 66. A portion of pivot axis 64 is mounted in a bearing 65 fixed by welding to the inner face 63a of the angle 63. It is possible to add to the bearing 65 a complementary ring in bronze. The frame 62 proper is fixed in the thickness of the opening, between the lower face 14a of the ceiling 14 and the floor 95, by means of fixing means 67 which, in the example illustrated, comprise a first part 67a intended to be fixed permanently to the side uprights, in particular wooden joists, defining the opening 66 and a second part 67b which is fixed to the frame 62. The first 67a and the second 67b parts are adjustable in position relative to each other. For example, the second part 67b comprises a fixed threaded rod welded to a gusset 70 (itself welded to the frame 62) by overlapping it and placed in the axis of the bearing 65. The first part 67 a is movable in height and can be a threaded ring on which a plate is welded. The support threaded rod 67b can also be welded directly to the bearing

65. Thus, it is possible to perfectly position the frame 62, without the staircase, at the opening 66, during its installation. In addition, the forces exerted on the frame 62 by the use of the staircase are much better distributed in this particular configuration. Gussets 71 welded obliquely on either side to the bearing 65 and also welded to the internal face 63a of the angle bracket 63 reinforce the solidity of the bearing 65, The angle bracket 63 forming the frame 62 can advantageously, in particular if it is in aluminum, to be reinforced by a flat welded on the upper edge of the angle iron, and which is therefore parallel to the horizontal base 62a of the angle iron and opposite it, towards the inside of the frame. In a nonlimiting example of the invention, the frame has external dimensions 1,250 x 690 mm overall, and internal dimensions 1,190 x 630 mm, its height being 30 mm and the thickness of the angle iron being 3 mm. The use of such an angle iron reinforced over all or part of the periphery of the frame, the dimensions of the angle iron and the reinforcement plate are determined, in particular as a function of the materials chosen, in order to obtain the desired mechanical strength. To dampen the descent and facilitate the ascent of the staircase, provision is preferably made for the implementation of one or more return springs. In the example of FIG. 15, it may be two torsion springs mounted on two portions 64a, 64b of pivot axes which connect the frame 62 to each of the two longitudinal uprights 69 of the upper end portion 94 of the staircase 60. It is also possible to use two tension springs arranged between the joists and the two uprights 69 of the upper end portion 94, preferably in the middle. ^• Preferably, each of the two portions 64a, 64b of the pivot axis comprises locking / unlocking means making it possible to attach / detach them from the frame 62. Thus, in this variant embodiment, it is possible to install the staircase 60 only after having mounted the frame 62 and also to dismount the staircase 60 - that is to say to extract it from the frame 62 - if necessary. In the example of FIG. 17, each portion 64a of pivot axis comprises two sliding parts 80, 81, locked in position by a pin 82: an internal part 80 and an external part 81, acting as a sheath in which the inner part 80 can slide, said outer part 81 being welded to the longitudinal upright 69, passing through it. To dismount the staircase, simply remove the pin 82 and extract the interior part 80 according to arrow G (Figure 17). It is then possible to use the dismantled staircase as a ladder. In all embodiments of retractable stairs and whether the uprights are made of aluminum, steel or another material, it is sought that the staircase can be accommodated in the smallest space, which is - in practice - delimited on a height H between a lower hatch, at the level of the ceiling of the lower room, and an upper hatch, at the level of the attic floor or the upper room. The width of the steps must take into account this height H and also the method of fixing the staircase, either on the lower hatch with a spacing (d according to the example in Figure 2) or on the frame, preferably without spacing between the staircase and the hatch (according to the example in FIGS. 6 and 9. Depending on this height H and the method of attachment, it is therefore possible that the steps may substantially exceed the lower end portions of the longitudinal uprights in the direction of the upper hatch, in the folded staircase position, but it is also possible that steps may protrude appreciably from the upper end parts of the longitudinal uprights in the direction of the lower hatch, folded staircase. In the case where the hatch is independent of the staircase, the position of the pivot axis is determined so that the front edges of the steps, projecting towards the hatch, rest on the latter in the folded staircase position and closed hatch. The size of the staircase should of course not hinder the closing of the two doors. In addition the width of the steps should not hinder the folding of the different parts of the staircase. The present invention is not limited to the embodiments described by way of non-exhaustive examples. In particular, it is up to the person skilled in the art to choose the materials and the configurations of the different parts used, in particular longitudinal uprights (in particular wood, steel, aluminum), steps (in particular wood, steel, aluminum), frame (in particular angle) , profiled in U, in T), to obtain the desirable mechanical characteristics. In addition, reinforcing rings, of steel or bronze, welded or fitted, can advantageously be implemented for example at the pivot axes of the articulation means, and holes formed in the longitudinal uprights. As shown in FIG. 10, the longitudinal uprights are advantageously tubes of rectangular section, the thickness of the tube in the intermediate part being greater than that of the tubes in the extreme parts, in the case of steel, possibly in that aluminum.

Claims

1. A device with steps, of the ladder or staircase type which comprises at least two parts, which each comprise two longitudinal uprights and several steps fixed between said uprights and which are foldable one on the other by means of articulation means, characterized in that the width (L) of a step, this being assumed to be zero thickness, is on the one hand greater than e / sin α and on the other hand, at most, substantially equal to ne / sin α, e being the width of a longitudinal upright, α being the angle of inclination between the longitudinal direction of said longitudinal upright and the plane of said step and n the number of parts, in that in the upper end part (4 ), the steps (7) protrude in part from the same first side (Ci) of the uprights (6), and in the lower extreme part (2), the steps (7) protrude in part from the same second (C ₂ ) or on the same first (Ci) side of the uprights (6), and in that the steps of the super parts placed (2,3,4), in the folded position, are inserted one between the other.

2. Device according to claim 1 characterized in that it comprises three parts and the steps (7) of the intermediate part (3) project on either side of the longitudinal uprights (6), preferably in the same proportion.

3. Device according to one of claims 1 or 2, of the ladder type to be placed on a support wall characterized in that the steps (Ml, M2, M3) of the lower extreme part project beyond the longitudinal uprights in the turned direction towards the support wall and the steps (M7, M8, M9) of the upper end part extend beyond the longitudinal uprights in the direction facing the user.

4. Device according to claim 1 characterized in that it comprises a number n of part greater than or equal to 3 and in that the width L of the steps is substantially equal to 3 e / sin α.

5. Device according to one of claims 1 to 4, in which n is equal to or greater than 3, characterized in that the longitudinal uprights are tubes, in particular of rectangular section, and in that the thickness of the tubes of the intermediate parts is greater than that of the tubes of the upper and lower extremities.

6. Device according to one of claims 1 to 5 characterized in that the length of the longitudinal uprights is different, depending on the parts, whereby the parts are offset relative to each other, in the position of the superimposed uprights , on one side and / or the other, allowing an adequate positioning of the steps, in particular the first and the last steps on the extreme parts, as well as an adequate spacing between two successive steps.

7. Device according to claim 1 characterized in that, the number n of parts being greater than 2, the steps of the upper extreme part extend beyond the longitudinal uprights on the first side (Ci), corresponding to the direction facing the user, and in that in the intermediate part or parts, the steps extend either from the second side (C ₂ ), or from either side of the longitudinal uprights, or from the first side (Ci).

8. Device according to one of claims 1 to 7 characterized by at least one U-shaped locking part (40, 57) allowing the longitudinal uprights to remain aligned in the deployed position, the lateral uprights (41, 42) of said piece ( 40, 57) being able to be fixed, in a removable manner on said longitudinal uprights, in particular by an interlocking on lugs (43, 44), each lug being rigidly fixed on a longitudinal upright, for example by means of a threaded rod, passing through said longitudinal upright, penetrating into the threaded lug, the threaded rod being welded on the inside face of the upright and the lug on the outside face of the upright.

9. Device according to one of claims 1 to 8 characterized by a U-shaped locking piece allowing the blocking of two longitudinal uprights in the folded position, the spacing (h) between the longitudinal axes of the two lateral uprights of said piece being equal to e or e (nl).

10. Installation comprising a retractable staircase (10), according to one of claims 1 to 9, characterized in that the upper end part (11) is fixed on the upper face (12a) of a pivoting lower hatch (12) by connecting means (16), pivotally articulated between two positions, a first position - deployed staircase - in which the hatch (12 ) and the longitudinal uprights (11) have between them a first spacing (D) and a second position - folded staircase - in which the hatch (12) and the longitudinal uprights (11) have between them a second spacing (d), lower at the first spacing (D) and in that possibly the steps, assumed to be of zero thickness, project towards the hatch by a distance at most equal to d / sin α.

11. Installation according to claim 10 characterized in that it comprises two articulated connection means by longitudinal upright, in that each articulated connection means comprises two studs (21, 22), connected by at least one link (23), preferably two links (23, 230, the first stud (21) being fixed on the hatch (12) and the second (22) under the longitudinal upright (18), in that the first pivot axis (26) of the rod (23) is connected either to the external side of the second stud (22), or to the external side of the longitudinal upright (18), in that the second pivot axis (25) of the rod (23) is connected to the external side of the first stud (21), in that the connecting rod (23) is perpendicular to the hatch (12) and to the longitudinal upright (18) in the first position, staircase deployed, and in that the installation comprises locking means of the link (23), at least in said first position.

12. Installation according to claim 11 characterized in that the first stud (21) has its upper face (21a) oblique and the locking means consist of a second stud (22) fixed under the longitudinal upright (11) and which has a oblique upper face (22a), so that the upper faces (21a, 22a) remain constantly parallel and that in the first position, they engage one against the other, and in that it possibly includes at least a stop (21d), in particular mounted on a first stud (21), capable of blocking at least one link (23) in the second position.

13. Installation according to one of claims 10 to 12 characterized in that the pivoting hatch (12) is mounted on a frame (15) by a pivot axis (20) or portions of pivot axis, mounted on gussets (84), the positioning of said axis or said axis portions being determined so that, in the closed hatch position, the lower face (12b) of the hatch (12) of thickness T is flush with the plane of the lower face (15a) of the frame (15), and in that the overall size of the installation is substantially equal to T + d + ne.

14. Installation comprising a retractable staircase (30) according to one of claims 1 to 9, characterized in that the upper end part (31) is pivotally mounted on a frame (32) delimiting an opening (34) formed in a ceiling (35), the pivot axis (33) being located below or at the level of the last step (39) or located between the last (39) and the penultimate step.

15. Installation according to claim 14 characterized in that it comprises at least one return spring, in particular either a tension spring (37) connecting the frame (32) and the upper end (38) of the upper end part ( 31) either two torsion springs on the pivot axis portions, or two tension springs between the joists or the frame and a point located on the upper upper part (31) of the staircase, in particular on the external faces of the latter, for example substantially in the middle, or a combination of these different springs.

16. Installation according to one of claims 14 or 15 characterized in that it comprises a pivoting hatch (36) of thickness t independent of the staircase (30) and in that the staircase (30), in position folded over and closed hatch, rests directly on the hatch either by the support of the upper extreme parts of its longitudinal uprights or by the support of the front edges of the steps projecting towards the hatch, the overall size of the installation then being substantially equal to t + ne.

17. Installation according to one of claims 14 to 16 characterized in that the upper end part (94) is pivotally mounted on the frame by two portions (64a, 64b) of the pivot axis, the axis (61) being from preferably located above the last step, connecting the frame (62) to the two longitudinal uprights (69) and in that the two axis portions (64a, 64b) are equipped with locking / unlocking means allowing the separation of the staircase (60) of the frame (62), for example each portion (64a) of pivot axis comprising two sliding parts (80,81), locked in position by a pin (82), namely an external part ( 81) welded to the longitudinal upright (69) passing through it and an interior part (80).

18. Installation according to one of claims 10 to 17 characterized in that a frame (15, 32, 62), preferably reinforced by gussets (68), is fixed in the thickness of the opening by means of fixing means (67) comprising a first part (67a) intended to be fixed permanently in the thickness of the opening, in particular on the lateral joists defining the opening (66) and a second part (67b) fixed to the frame (62), preferably overlapping at least one gusset (68), said first and second parts being adjustable in position relative to each other.

19. Installation according to claim 18 characterized in that the first part (67b) comprises a threaded rod and the second part (67a) comprises at least one threaded ring, on which is preferably welded a flat iron and which is able to cooperate with the threaded rod, in that the pivot pin is mounted in a bearing (65) welded to the frame (62), in that the threaded rod (67b) is either welded directly to the bearing (65) or overlaps a vertical gusset (70), welded to the frame (62), located in the axis of the bearing (65) and perpendicular to the plane of the underside of the frame, on which the gusset it is welded, and in that at least two other gussets (71) are welded at an angle to the bearing (65) on either side of the latter and to the inner face (63a) of the angle iron (63) of the frame (62).

20. Installation according to one of claims 10 to 19 characterized in that the retractable staircase comprises at least one consolidation spacer, fixed transversely on its two longitudinal uprights while crossing these, preferably four spacers for a staircase (60) in three parts, a spacer (91) being located near the pivot axis (61), a spacer (90) being located respectively near a articulation means (5) and possibly lugs (43, 44), a spacer (93) near the first step NI of the staircase (60) and a spacer (92) being located on the articulation means (5) connecting the intermediate part and the lower end part.

21. Installation according to one of claims 10 to 20, the staircase of which is intended to be housed in a ceiling opening between a lower hatch and an upper hatch having a spacing H between them, characterized in that the bulk, in folded position, the staircase - whether the uprights are made of aluminum, steel or other material - is less than the height H and in that the steps substantially protrude from the longitudinal uprights superimposed on the lower end, in the direction of the upper hatch.