Elastic self carrying bellows

The invention relates to an elastic self-carrying bellows-body, in particular for vehicles, having been formed with ribs separated by spacings and interconnected with connecting means. The essence of the invention lies in that the thickness of the connecting means interconnecting the ribs is less on at least two opposite sides of the bellows-body, than that of the ribs and the ribs and connecting means are formed as monolithic units.

The invention relates to elastic self-carrying bellows in particular for 
vehicles, which are formed with ribs mutually separated by spacings and 
connected with connecting means. 
From technical literature diverse bellows are known for confining the space 
between the bodies of two connected vehicles at least on three sides. 
So e.g. articulated busses used to be provided with bellows, which are sewn 
from a cloth coated with a flexible synthetic material and the outer 
contour of which follows the outline of the body of the articulated bus. 
The ribs having been cut and sewn for the bellows do not assure 
self-keeping, self-carrying of the bellows, so they are provided with an 
extra reinforcement along the stitching. A further disadvatageous feature 
of the solution lies in that the stresses arising in the course of drawing 
apart the bellows cause a permanent deformation in the inserts made of 
metal. 
From the patent HU-PS No. 171 185 elastic bellows made of textile-elastomer 
are known. The essence of this solution lies in that at least at the 
elements assuring self-carrying the bellows are formed of at least two 
textile-layers and the elastomer layer lying inbetween; furtheron the 
profile-width of the vertical ribs is preferably constant, while in 
dependence of the dimensions of the bellows, from the connection of the 
horizontal ribs advancing towards the vertical symmetry-axis of the 
bellows said profile-width continuously decreases; at the same time the 
vertical and horizontal ribs are interconnected with a circular arc with a 
pre-determined radius and in a given case the outer and/or inner edges are 
provided with a reinforcement made of a profiled cord. 
Another solution--being similar to the specified one--is also well known, 
with which one, three or even more layers containing properly oriented 
elementary fibres are used and at least 60% of the elementary fibres are 
of the same orientation. With this solution the elementary fibres are more 
embedded in rubber, and accordingly interlacing points exert less shearing 
forces. 
The common deficiency of both of the solutions mentioned lies in their 
production requiring a considerable live labour, as only manual 
manufacturing is possible, involving a lot of error sources. The 
deficiencies fundamentally influence the usefull life of the bellows and 
the aesthetic appearance thereof. 
A further disadvantageous feature lies in that the bellows are composed of 
single elements cut out of sheet material, accordingly, a considerable 
waste is produced far increasing productional costs. 
From Italian technical literature extruded bellows made without a 
textile-carcasse are also known, the essence of which lies in that the 
ribs are mainly hollow and are interconnected by connecting means. 
The deficiency of this solution appears in the slight--scarcely 
twofold--extensibility; costs of production are high; due to the large 
dimensions the bellows can be used but under special conditions, so they 
are not widely used. 
The aim of our invention is to eliminate said deficiencies i.e. to develop 
elastic self-carrying bellows, which can be produced in an easy manner and 
at low costs, the extensibility meeting even extreme requirements; further 
requirements lie in that the ribs should be small-sized; usual and cheap 
basic materials could be used; design should be simple and simultaneously 
aesthetic; special expenditures and preparatory works are not needed, 
working with a high operational safety and having at least the same useful 
life as the known solutons, if possible, even longer. 
The invention is based on the recognition that by using synthetic 
materials, expediently polyurethane foam material as a basic material and 
by a more simple structural design the aim set can be achieved. 
The aim set is achieved in case of the elastic self-carrying bellows--as 
described above--in such a manner that the thickness of the connecting 
means connecting the ribs is less, than that of the ribs at least on two 
opposite sides of the bellows, furtheron, the ribs and the connecting 
means are formed as monolithic units. 
The majority of the bending stresses arising in the course of opening and 
closing the ribs is taken up in the range, where the adjacent ribs meet, 
in which--in order to decrease the bending stresses caused by the 
considerable bending and as a consequence, to prolongate useful life--a 
preferred embodiment is used, with which at least on one side the 
cross-section of the connecting means is confined by an arc; furtheron the 
theoretical geometric cconfigurations being characteristic for the arched 
parts of the connecting means have coinciding symmetry-points or are 
displaced in relation to each other, at least in the joining range of the 
longitudinal sides the ribs are diminished. 
In order to promote mechanization of production and to facilitate assembly, 
disassembly and exchange, with a preferred embodiment, at least at one 
place transversely to the ribs it is divided and at the ends thereof an 
outermost rib each is formed. 
With a further preferred embodiment in order to assure close connection 
with the vehicle body the bellows-bodies are assembled of at least two 
pieces. 
With another preferred embodiment--facilitating production--in the two 
outermost ribs a Bowden-cable is inserted.

The self-carrying elastic bellows-body 1 according to the invention is 
formed with an upper arch 2, two side walls 3, and a lower arch 4, which 
are formed with the ribs 5. In the vertical symmetrical axis of the 
elastic self-carrying bellows-body 1 the ribs 5 are divided and are 
interconnected by means of the connecting means 6. The ribs 5 are arranged 
with the spaces d and are elastically interconnected with the connecting 
means 6, i.e. they are formed of one piece. In general, the thickness a of 
the ribs 5 is larger, than the smallest thickness b of the connecting 
means 6. 
The elastic self-carrying bellows-body 1 according to the invention is 
provided on both ends with an outermost rib 8 each, incorporating the 
synthetic pipe 15 and the Bowden-cable 9 therein. The elastic 
self-carrying bellows-body 1 is fixed to the connected body of the bus 
along the outermost ribs 8 in a manner known in itself. 
The thickness of the connecting means 6 is formed in the range between the 
outer curvature and the inner curvature, where it has the less thickness 
b. 
On the place of division the ribs 5 are interconnected by the connecting 
means 6, which is formed of the stiffening bars 11 provided with the 
screws 12--as the clamping plate 13--, the stiffening bar 11 is inserted 
between the two ribs 5 of the elastic self-carrying bellows-body 1. The 
screws 12 are welded onto the stiffening bars 11 and pass through the bore 
having been formed in the connecting means 6 of the two ribs 5; the 
flexible sheet 10 protecting against dust, the clamping sheet 13 and the 
screws 12 are fixed with nuts. 
The connecting means 6 may have a cross-section, wherein on the outer 
and/or inner side it is formed with at least one arc with identical and/or 
different radius, while the part without the arc is formed of a straight 
portion. In case of too large dimensions, as it is the case with the 
embodiment illustrated here, the ribs are thinned in the corner-range 14; 
as a consequence, the stresses arising in the course of the motions in the 
corner-ranges 14 can be considerably decreased, whereby the useful life of 
the bellows according to the invention can be well prolongated. 
The elastic self-carrying bellows-body 1 according to the invention can be 
produced in pieces symmetrically divided and perpendicularly to the ribs 
5. In this case the single pieces are joined into one organic unit in a 
manner known in itself, e.g. by glueing. In such a manner production can 
be considerably facilitated. 
In the case of divided elastic self-carrying bellows-bodies 1 division is 
preferably performed along the plane passing through the vertical symmetry 
axis and lying perpendicularly to the ribs 5 forming the arch 4. The 
divided parts are interconnected by means of the connecting means 6 
already mentioned. 
It seems to be expedient to perform division along the plane running 
perpendicularly to the ribs 5 forming the arch 4 and passing through the 
vertical symmetry axis of the elastic self-carrying bellows-body 1, 
because the slightest motions arise just in said range, accordingly, load 
of the connecting device can be decreased and as a consequence, useful 
life thereof can be prolongated. 
The elastic self-carrying bellows-body 1 was cast from foamed polyurethane, 
having a density of 0.9 g/cm.sup.3, the hardness was about 95 Shore. Any 
other basic material may be suitable; the most essential requirement lies 
in that high limit values of fatigue, proper hardness assuring 
self-carrying, sufficient elasticity and a lightweight structure could be 
achieved. 
The elastic self-carrying bellows-body 1 according to the invention is at 
least tentimes more extensible than the known solutions.