The subject of the invention is a modular staircase unit, the configuration of which staircase unit allows the easy and quick assembling of staircase units to form staircase flights with adjustable length and stair rise with adjustable height according to the requirements.

Many different staircase structures are being used in practice. Most of them are installed permanently, and are made of concrete, wood or steel. The construction of these staircases needs qualified personnel, while requiring large amounts of building material and time. In addition to that, an individual solution is necessary for each installation site.

It is often a requirement in the case of bridging small heights, however, that the staircase structure should be deployed quickly and easily. Such requirements occur for example in case of terraces, access shafts, theater stages or in case of temporary stairs used at construction sites.

According to the state of art the Australian patent AU 2015200568 makes known a staircase unit. The stair units can be assembled in a modular fashion, so that the lateral supporting parts of the stair units are fastened to one another in a staggered configuration.

The Chinese patent CN 108590057 makes known a staircase structure which can be assembled and has a low mass. The staircase structure is assembled from staircase units, so that the profiled ends of the lateral supporting parts of the staircase units are fitted and fastened together, and the treads are fixed between them. The German patent DE 3214744 makes known a staircase structure established from IJ- shaped consoles. The U-shaped consoles are shifted relative to one another before fastening them together, so that the height difference between the U-shaped consoles determine the rise of the stair.

The drawback of the solutions described above is that the shape of the staircase unit is complicated, and their configuration and their mode of assembling do not allow the adjustment of the rise of the assembled flight of stairs to the given conditions of the site.

When developing the solution according to the invention we had the aim to create a flight of stairs made of units, which allow the quick and easy assembling of a flight of stairs without the use of additional supporting elements, and which allows the harmonization with the conditions of the site due to its adjustable length.

While creating the staircase units according to the invention we recognized that if a modular staircase unit is formed, which can be assembled together easily and quickly with the help of elongated holes prepared in the connecting extensions of the staircase units and with the help of holes in their fastening parts, so that the rise of stair and the length of flight of stairs can be adjusted with the help of the elongated holes within a certain range, then the set out goal can be achieved. The invention is modular staircase unit, which is established form fitting plates and stair tread. It is characterised by that the staircase unit is formed with stair tread fixed between identical fitting plates having an edge, the axis tl of the connecting extensions of whose fitting parts has an angle a relative to the edge, and two holes having diameter D are formed in each connecting extensions in a way, that the centers of holes aligned in parallel with axis tl are located at a distance K2 relative to each other, while the centers of holes are aligned perpendicularly to the axis tl and are located at a distance K1 relative to each other, furthermore, the lower elongated holes are formed with a length LI and a width S in the fastening parts of the fitting plates, where the distance between the axes of elongated holes is Kl, and the axes are aligned at an angle a relative to the edges of the fitting plates, furthermore, the upper elongated holes having a width S and a length L2 are formed beneath the edges of the fitting plates, and the stair tread is fastened in parallel with the edges of the fitting plates beneath the upper elongated holes.

In preferred embodiment of the solution according to the invention the stair tread is made as a grating.

In another preferred embodiment of the solution according to the invention a leading safety edge with antiskid elements is fastened to the outside edge of the stair tread.

In further another preferred embodiment of the solution according to the invention the length LI of the lower elongated holes is larger than or equal to the cumulative length of distance K2 and diameter D of the holes.

In further another preferred embodiment of the solution according to the invention the diameter D of the holes is identical to the width S of the lower elongated holes.

In further another preferred embodiment of the solution according to the invention the inclination angle a is 40°-50°, preferably 45°. The staircase unit according to the invention is described below with reference to the following drawings:

Fig. 1 shows a possible embodiment of the staircase unit according to the invention with perspective view.

Fig. 2 shows the lateral view of the staircase unit introduced in Fig. 1.

Fig. 3 shows the top view of the staircase unit introduced in Fig. 1.

Fig. 4 shows the front view of the staircase unit 1 introduced in Fig. 1.

Fig. 5 shows a possible embodiment of the flight of stairs assembled from staircase units 1 according to the invention.

Fig. 1 shows a possible embodiment of the staircase unit 1 according to the invention with perspective view. The figure shows the staircase unit 1 formed with fitting plates 2, 3 at its two sides, and stair tread 4 is fastened in a known manner between the fitting plates 2, 3. In this case the stair tread 4 has a grated arrangement. A leading safety edge 5 with antiskid elements 11 is located at the outside edge 33 of the stair tread 4.

The figure furthermore shows the two holes 10 in each of the connecting extensions 12, 13 of the fitting plates 2, 3, and there are elongated holes 8, 9 in their fastening parts 22, 23, and upper elongated holes 6, 7 are formed in parallel with the plane of the stair tread 4. If required, railing elements can be fastened in the upper elongated holes 6, 7 with the help of bolts 24.

Fig. 2 shows the lateral view of the staircase unit 1 introduced in Fig. 1. The figure shows the staircase unit 1 together with the fitting plate 3 and the stair tread 4. The leading safety edge 5 established with antiskid elements 11 can be seen at the outside edge 33 of the stair tread 4.

The figure further shows the that there are two holes 10 having diameter D formed in the connecting extension 13 of the fitting plate 3 with axis tl , the centers of which holes 10 are located at a distance K1 in a direction perpendicular to the axis tl, and are located at a distance K2 in a direction parallel with the axis tl . The distance K2 of the holes 10 is determined in a way that K2+D< LI. The figure shows the lower elongated holes 8, 9, which have a length LI and a width S with axes t2, t3 formed in the fastening part 23 where the axes t2 and t3 have a distance K1 from each other.

The figure shows the upper elongated holes 6, 7, which are aligned in parallel with the stair tread 4 and have a length L2 and a width S.

The figure shows that the lower elongated holes 8, 9 and the axis tl of the connecting extension 13 are aligned with an inclination angle a relative to the horizontal plane of the stair tread 4 and the edge 14, which inclination angle a determines the angle of the flight of stairs.

Fig. 3 shows the top view of the staircase unit 1 introduced in Fig. 1. The figure shows the staircase unit 1 and the fitting plates 2, 3 together with the connecting extensions 12, 13, as well as the leading safety edge 5 formed with antiskid elements 11 on the stair tread 4.

Fig. 4 shows the front view of the staircase unit 1 introduced in Fig. 1. The figure shows the staircase unit 1 together with the fitting plates 2, 3, as well as the leading safety edge 5 with antiskid elements 11.

Fig. 5 shows a possible embodiment of the flight of stairs assembled from staircase units 1 according to the invention. The figure shows a flight of stairs which consists of five staircase units fastened together with the help of bolts 24. The figure shows that the lower initial staircase unit 1 is attached to the lower fastening elements 25 by means of bolts 24, and the lower fastening elements 25 are attached to the horizontal support 31 in a known manner, e.g. by means of bolting with the help of holes 29 formed in it. The upper staircase unit 1 is attached to the fastening parts 27 of the upper fastening elements 26 by means of bolts 24, while the upper fastening elements 26 are attached to the recipient vertical surface 32 in a known manner, e.g. by means of bolts passed through holes 30 formed in them.

The figure shows that staircase units 1 are attached to one another, so that the connecting extensions 12, 13 formed in the fitting plates 2, 3 of the lower staircase unit 1 having holes 10 are oriented towards the lower elongated holes 8, 9 formed in the fastening parts 23 of the staircase unit 1 located above, and are fixed together with the help of bolts 24.

The figure furthermore shows the bolts 24 are screwed into the upper elongated holes 6, 7 formed in the fitting plate 3.

In a possible embodiment of the staircase unit according to the invention the identically configured fitting plates 2, 3 are established first. The fitting plate 3 is formed with edge 14, connecting extension 13 and fastening part 23, so that two holes 10 having diameter D are prepared in each connecting extension 13, and two parallel lower elongated holes 8, 9 having a length LI and a width S are created in the fastening part 23.

The axis tl of the connecting extension 13 is aligned with an angle a relative to the edge 14 and the upper elongated holes 6, 7. The centers of each two holes 10 are located at a distance K1 from each other, and the distance between the axes of lower elongated holes 8, 9 is also Kl . The holes 10 and the lower elongated holes 8, 9 are formed in a way that the diameter D of holes 10 is identical to the width S of the lower elongated holes 8, 9, i.e. D = S.

The two upper elongated holes 6, 7 having length L2 are formed in parallel with the edge 14 of the fitting plate 3, where the width S of the upper elongated holes 6, 7 is preferably identical to the width S of the lower elongated holes 8, 9.

The fitting plate 2 is formed similarly to the fitting plate 3. Following this the stair tread 4 is formed preferably with a grating. The leading safety edge 5 is created with antiskid elements 11 and is fastened to the outside edge 33 of the stair tread 4.

Then the stair tread 4 having a leading safety edge 5 is fixed with known method, preferably by means of welding between the fitting plates 2, 3. The stair tread 4 is fixed at the area below the upper elongated holes 6, 7 in parallel with the edges 14 of the fitting plates 2, 3.

In a possible embodiment of the staircase unit according to the invention the flight of stairs is established from the staircase units 1 in a way, that the lower initial staircase unit 1 is attached first in a known manner to the lower fastening elements 25 by means of bolts 24 passed through the lower elongated holes 8, 9 formed in the fastening parts 22, 23. The lower fastening element 25 is attached in a known manner to the horizontal support 31.

The subsequent staircase unit 1 is attached to the lower staircase unit 1 so that the connecting extensions 12, 13 formed in the fitting plates 2, 3 of the staircase unit 1 with holes 10 are oriented towards the lower elongated holes 8, 9 formed in the fastening parts 22, 23 of the staircase unit 1 situated above, and are fixed by means of bolts 24.

Each of the subsequent staircase unit 1 is fastened according to the above method.

The topmost staircase unit 1 is attached by means of bolts 24 to the upper fastening elements 26 with the help of its holes 10, while the upper fastening elements 26 are fixed to the vertical surface.

The height of the stair together with the height of the flight of stairs can be determined during the assembling of the staircase units 1, so that the holes 10 of the lower staircase unit 1 can be shifted to the desired distance up to a length L1-(K2+D) along the lower elongated holes 8, 9 having a length LI of the staircase unit 1 situated above when the staircase units 1 are fastened to each other.

Elements of the railing can be attached as required with the help of bolts 24 screwed into the upper elongated holes 6, 7 formed in the fitting plates 2, 3.

The material of the staircase unit 1 according to the invention is steel, preferable structural steel.

The dimensions of the staircase unit 1 according to the invention can be selected according to the requirements, the preferred dimensions being 800x270 and 600x270 mm. The a inclination angle can be 40°-50°, preferably 45°, Kl= 45 mm, K2 =50 mm, Ll= 86,5 mm, L2= 77 mm, S= 16 mm.

Advantages of the staircase unit 1 according to the invention:

- can be assembled quickly and easily,

- assembling does not require professionally qualified personnel,

- moderate weight,

- adjustable length and stair rise with adjustable height,

- can be used at outdoor location, as it does not hold snow,

- corrosion resistant and durable because of its material

- does not require cladding. List of reference items

1 - staircase unit

2 - fitting plate

3 - fitting plate

4 - stair tread

5 - leading safety edge

6 - upper elongated hole

7 - upper elongated hole

8 - lower elongated hole

9 - lower elongated hole 10 - hole

11 - antiskid element

12 - connecting extension

13 - connecting extension

14 - edge

22 - fastening part

23 - fastening part

24 - bolt

25 - lower fastening element

26 - upper fastening element

27 - fastening part

28 - connecting extension

29 - hole

30 - hole

31 - horizontal support

32 - vertical surface

33 - outside edge