Abstract:
A collapsible staircase is provided with a set of flat parts, with each of the parts intended to function as steps. Each flat part can be moved between a first position and a second position. All of the flat parts are substantially coplanar when the parts are in the first position, and the parts are disposed above each other and at a distance from each other when the parts are in the second position. A retractable holding handle is also provided and driven together with the flat parts.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The present invention relates to a collapsible staircase, notably for a vehicle such as an aircraft. 
     II. Description of Related Art 
     In vehicles, and in particular aircraft, it is advisable to save space. This is a constant concern of the person skilled in the art. The saved space makes it possible to increase the comfort of the passengers and/or to decrease the overall dimensions, so that the size and thus also the weight of the vehicle structure can be reduced. If more space is offered to the passengers, the company operating this vehicle achieves a commercial advantage. If the structure is smaller and/or lighter, the advantage is then manifested in operating costs. 
     A staircase is a convenient means making it possible to move from one level to another. It has the disadvantage of being cumbersome. Documents FR 2873349 or US 2006/113427 show, for example, a use of a staircase in an aircraft. To limit the space requirement, a traditional solution is to replace a staircase by a ladder, as suggested in the aforesaid documents. This can be moved around more easily. There also exist collapsible staircases that can be stored in a ceiling, for example by pivoting. To limit the space requirement, it is also known to make staircases steeper, or in other words with a greater inclination than a traditional staircase. 
     The present invention then has the objective of providing a staircase intended more particularly for a vehicle, that will not encroach either on an aisle or the like intended for the passage of passengers into the vehicle or on the storage volume usually available in the said vehicle. 
     BRIEF SUMMARY OF THE INVENTION 
     To this end it proposes a collapsible staircase notably for a vehicle, provided with a set of flat parts each intended to function as steps. 
     According to the present invention, each flat part can be moved between a first position and a second position; all the flat parts are substantially coplanar when they are in their first position, and the flat parts are disposed one above the other and at a distance from one another when they are all in their second position. 
     The staircase created in this way is a combination of a staircase and a ladder. To its users it offers the comfort of a staircase having steps that can be broad to provide good support, and the reduced space requirement of a ladder, especially because of the fact that it is very steep, since it has an inclination of 90°. 
     According to a preferred embodiment, a staircase according to the invention is provided with two vertical beams, between which there are mounted the flat parts intended to function as steps. These beams then serve as guides for the steps during their movement, and the fact that the steps are held at both ends permits them to be firm and to support the weight of a person easily. 
     The flat parts of the staircase can be simply pivotable in order to change from their first position to their second position. However, a preferred embodiment provides that the movement of each flat part between its first position and its second position is a combination of a translation and a rotation. In this case, each flat part is guided, for example, on the one hand by a pin or similar element sliding in a straight corresponding slot disposed substantially in the plane of the flat parts when they are in their first position and on the other hand by a pin or similar element sliding in a curved corresponding slot having a shape resembling an arc of a circle. 
     To facilitate the use of the staircase, all the flat parts are connected to one another by a connecting rod. In this way, the movement of one step or flat part of the staircase pulls the other steps along in its movement. 
     For greater comfort of the users and greater ease of use, a staircase according to the invention is advantageously provided in addition with at least one holding handle to assist a user in climbing the staircase, and this handle can be moved between a retracted position inside a wall and a service position in which it is accessible to the user. Of course, it is preferable to have two holding handles, one for each side of the staircase. The said holding handle is preferably connected to a mechanism that acts on the flat parts to make them move from their first position into their second position and vice versa in such a way that, when the flat parts move from their first position into their second position, then the said handle moves from its retracted position to its service position, and vice versa. 
     In the case in which the staircase is provided both with a connecting rod between the flat parts and with a handle, then the said handle pivots advantageously so as to move from its service position to its retracted position and vice versa, and the connecting rod connecting the flat parts advantageously drives a toothed wheel in rotation during the movement of the flat parts, this toothed wheel then driving the holding handle. In the same movement, all the flat parts intended to function as steps and the holding handle(s) then move from their service position to their idle position. 
     The present invention also relates to a rest compartment for at least one member of the aircraft crew and/or to an aircraft, characterized in that they are provided with an access staircase such as described hereinabove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Details and advantages of the present invention will become more apparent from the description hereinafter, given with reference to the attached schematic drawings, wherein: 
         FIG. 1  illustrates the entrance of a rest compartment for the pilot of an aircraft equipped with a staircase according to the invention, 
         FIG. 2  illustrates the staircase of  FIG. 1  in its collapsed position, 
         FIG. 3  illustrates the staircase of the preceding figures in an intermediate position, 
         FIG. 4  illustrates the staircase of the preceding figures in the service position illustrated in  FIG. 1 , 
         FIGS. 5 to 7  are larger-scale side views of the staircase of  FIGS. 1 to 4  in three different positions, and 
         FIG. 8  shows in more detail the fixation of a step in the embodiment of the staircase illustrated in the preceding figures. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The attached drawings illustrate a preferred embodiment of a staircase according to the invention. In this illustrated embodiment, the staircase makes it possible to move from a first level  2  to a landing  4 . In the description hereinafter, it is assumed that landing  4  is horizontal and that first level  2  corresponds to an aisle that, for example, also has a horizontal floor. 
     The staircase illustrated in the drawings is provided with five steps  6 , which make it easier to move from first level  2  to landing  4 . 
     As is clearly apparent from the attached drawings, steps  6  are each movable steps. They can be moved between a first position ( FIGS. 2 and 5 ) and a second position ( FIGS. 1 ,  4  and  7 ). In the first position, the staircase cannot be used. Steps  6  are all oriented vertically and thus form a vertical wall. In turn, the second position of steps  6  permits use of the staircase. 
     Each step  6  has an overall rectangular shape. It is made, for example, from sheet metal, such as aluminum sheet, or from a composite material. Each step  6  has an upper face  8 , a lower face  10 , two side edges  12 , a front edge  14  and a rear edge  16 . 
     The upper face of step  6  corresponds to the face intended to receive the foot of a user when the staircase is in its use position of  FIGS. 4 and 7 . Lower face  10  of each step corresponds to the face opposite upper face  8 . Side edges  12  correspond to the short sides of rectangular step  6 . Front edge  14  corresponds to what is usually known as the “step tread” in a staircase. It is the step edge facing the user as he is climbing the staircase. Rear edge  16  is the edge opposite front edge  14 . 
     In the collapsed position of the staircase, or in other words when the staircase is not in service, steps  6  are disposed in a vertical plane, one above the other. For two neighboring steps  6 , therefore, rear edge  16  of one is in contact (or almost so) with front edge  14  of neighboring step  6 . In this way the five steps  6  form a vertical flat panel. It is noted that lower face  10  of each step is visible here. It is then possible to provide a design on this lower face  10 . When the staircase is in use, the esthetic appearance of lower face  10  is not affected by the numerous movements of users, since nothing is acting on this lower face  10 . 
     In the service position of the staircase, each step  10  is disposed horizontally. The steps are disposed one above the other and of course are spaced apart, but without horizontal offset from one to the other. Thus all the front edges are in the same vertical plane. 
     As can be seen in the drawings, steps  6  are mounted between two vertical beams  18 . These vertical beams  18  can correspond to an already existing structure having a shape adapted for accommodating the staircase described here. As an example, these beams can be made of an aluminum-base metal alloy. Each beam in turn also has a substantially rectangular shape. It is made, for example, from sheet metal having a width slightly greater than the depth of steps  6 , and its length is slightly greater than the distance separating first level  2  from landing  4 . By depth of steps  6  there is understood here the length of side edges  12 . In turn, the width of steps  6  corresponds to the length of the front and rear edges of the steps. 
     Vertical beams  18  are disposed in a vertical plane perpendicular to steps  6 , both when the latter are in their collapsed position of  FIGS. 2 and 5  and when they are in their active position of  FIGS. 4 and 7 . 
     It is noted that slots  20  are present in the vertical beams. These slots have a shape of an arc of a circle. 
     By analogy with the orientation chosen for steps  6 , the term front edge  22  of vertical beams  18  will be applied hereinafter to the edge of each of these beams that faces a user climbing the staircase. Front edge  22  of a vertical beam  18  therefore corresponds to a long side of the rectangular shape of the vertical beam. As is evident from the drawings, the two vertical beams  18  are parallel and separated from one another by a distance corresponding substantially to the width of steps  6 . Hereinafter the term inside face  24  of a vertical beam  18  will be applied to the face of this beam that is oriented toward the other vertical beam. The other face of the vertical beam  18  under consideration is referred to as the outside face. 
     In the same way that a slot  20  of a vertical beam  18  corresponds to each step  6 , a slideway  28  mounted on inside face  24  of vertical beam  18  at the level of front edge  22  of this beam is associated with each step  6 . This slideway  28  has a straight slot that is closed at least at its lower end (meaning that oriented toward first level  2 ). 
     Each side edge  12  of a step  6  is provided with a first pin  30  intended to cooperate with a corresponding slideway  28  and with a second pin  32  intended to cooperate with a corresponding slot  20 . First pin  30  is disposed on the corresponding side edge  12  in immediate proximity to front edge  14  of the corresponding step  6 . Second pin  32  in turn is disposed at a distance from the first pin but is not necessarily located at the level of rear edge  16  of step  6 . In the illustrated embodiment, this pin extends toward the outside of step  6  while being fixed on upper face  8  of this step  6  (see  FIG. 8 ), and it is located closer to rear edge  18  than to front edge  16 . The shape of slot  20  is defined in such a way that when first pin  30  slides in its slideway  28 , second pin  32  corresponding to the same side edge  12  of step  6  slides freely in corresponding slot  20 . The shape obtained is an arc of a circle, which should be positioned correctly as a function of the starting position and of the ending position of step  6 . The length of slot  20 —and of slideway  28 —depends on the travel of step  6 . When step  6  is in its service position, or in other words is horizontal, first pin  30  is stopped against the bottom of slide  28 . Pins  30  and  32  and especially also slideway  28  must then be dimensioned to support the weight of a person with complete safety. 
     To permit all steps to be moved at the same time and in phase, a rod  34  is provided on each side of the staircase. Each rod  34  connects steps  6  at the level of their second pins  32 . As can be noted, the figures show that each rod  34  is extended upward. The upper end of each rod  34  is equipped with a third pin  36 . This slides in a slot  20  parallel to the other slots  20  of corresponding vertical beam  18 . The cooperation of third pin  36  with corresponding slot  20  ensures guidance of the corresponding end of rod  34 . It is also noted that the end of rod  34 , equipped with third pin  36 , is linked to an arm  37 . The latter connects the end of the rod to a toothed wheel  38 . This wheel is mounted around a spindle  40  that is fixed relative to the corresponding vertical beam  18 . This toothed wheel  38  engages with a rack  42 . 
     A holding handle  44  is integral with rack  42 . The assembly formed by holding handle  44  and rack  42  is mounted pivoting around a second horizontal spindle  46  that in this case is disposed in the extension of the corresponding vertical beam  18 . Rack  42  then has a shape of an arc of a circle whose center corresponds to second spindle  46 . 
     With such a structure, the movement of steps  6  drives the movement of holding handles  44  and vice versa. Holding handles  44  are defined in such a way that they are retracted when the staircase is not in service and that they appear and can be grasped when the staircase is in service. 
     In the preferred embodiment illustrated in the drawings, the lower end of rod  34  is connected to a gas spring  48 . It is possible to provide only a single gas spring  48  for a single rod  34 , but preferably each rod  34  is equipped with its own gas spring  48 . The gas spring(s)  48  used make(s) it possible to ensure assistance to the user at the time of moving of steps  6  from one position to another. 
     Conceivably the movement of steps  6  can be controlled manually or electrically. In the case of manual opening, it can be provided, for example, that holding handles  44  function as control handles for moving the staircase into service and out of service. The shape of these holding handles  44  is then designed such that they can function just as well from landing  4  as when the user is on first level  2 . Electrical opening is achieved by providing, for example, a small electric motor that acts on toothed wheel  38 . 
     The staircase described in the foregoing is illustrated in  FIG. 1  in an application in which it permits access to a rest compartment for an aircraft pilot. It is noted that it is then integrated into a monument of the aircraft used in particular for storage of carts  50 , usually known as “trolleys”, and used to provide food and beverage services to the passengers during a flight. In this particular case, the staircase makes it possible to gain access from an aisle to a landing disposed above the carts without reducing the cart capacity of the monument. Here there are disposed four carts  50 , as is usually the case for aircraft monuments. The staircase therefore does not limit the capacity of the monument and in addition it does not encroach on the neighboring aisle. Only holding handles  44  project into the aisle, but they can be retracted into the interior of the monument so that they no longer present an obstacle. 
     By virtue of its very small space requirement, this staircase can find other applications in an aircraft or else in other vehicles (train, bus, ship, etc.). 
     The staircase described with reference to the drawings also has the esthetic advantage of being able to be “invisible” when it is not in service. As indicated in the description, when the staircase is in its idle position, steps  6  form a flat panel that can easily be integrated into a wall. Vertical beams  18  can also be treated esthetically so that they are discreet or quasi-invisible in their environment. 
     A staircase such as described hereinabove is better adapted for permitting movement from a lower level to an upper level when the difference between the height of the two levels is not very great. Nevertheless, by providing adequate holding handles, staircases with a larger number of steps  6  can be designed in accordance with the present invention. 
     For ergonomic reasons, the depth of steps  6  is preferably on the order of 180 mm. This dimension makes it possible not only to have sufficient support for the foot of a person ascending or descending the staircase but also to have steps that are correctly spaced from one another in service position of the staircase. 
     The present invention is not limited to the preferred embodiment illustrated in the drawings and described in the foregoing. It also relates to all the alternative embodiments mentioned and those within the capacity of the person skilled in the art within the scope of the claims hereinafter.