Belt conveyer system

A belt conveyer system where along various sections great differences in height must be overcome. A conveyer belt that is initially spread flat is guided in steeply inclined stretches to form a closed hose. To satisfactorily transport, without loss, even difficult-to-handle, fine-particled material, the transition from a steep section into a horizontal section, or even to a discharge station, the steadily opening cross-sectional area is a critical process. To avoid the danger of disruption, a cover belt is provided that extends over the transition zone. The lower run of this cover belt extends into the opening hose cross-section of the conveyer belt, rests directly upon the transported material, and is supported on both sides on the edges of the conveyer belt.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a belt conveyer system in which material 
is transported by an endless conveyor belt that can be closed off to form 
a hose, and that can be made of rubber or rubber-like synthetic material. 
2. Description of the Prior Art 
By embodying the conveyer belt as a so-called hose belt that can be closed 
off to form a complete circular cross-section by overlapping the 
longitudinal edges of the belt, it is possible, at high conveying 
capacities, to overcome steeper inclines than was possible with the 
previously customary flat or trough conveyer belts. However, in the 
heretofore known conveyer systems equpped with such a hose belt, problems 
were encountered in those sections where the belt opened from its 
circular, closed, cross-sectional shape into the flat, spread-out shape. 
These problems were due to the fact that in these sections the material 
that was being transported was unprotected and could thus be subjected to 
wind and rain. Such open sections of the conveyer system occur on the one 
hand where the belt changes over from a steeply ascending stretch into a 
flat or descending stretch, and on the other hand occur at the end of a 
transporting stretch where the belt is guided in a flat state about an end 
guide roller and the material that is being transported is discharged. 
It is therefore an object of the present invention also in these two 
regions to provide a possibility for obtaining and utilizing the 
advantages of the closed, hose belt conveying, i.e. the complete enclosure 
of the material that is being transported, to the greatest extent possible 
.

SUMMARY OF THE INVENTION 
The belt conveyer system of the present invention is characterized 
primarily in that, in the transition region of the conveyer belt from the 
hose shape to the spread-open shape, the lower run of an endless cover 
belt, that runs over at least three guide rollers, extends into the 
opening cross-sectional area of the conveyer belt, with a central portion 
of the lower run of this cover belt resting directly upon the material 
that is being transported, and with the edge portions of the cover belt 
resting on the longitudinal edges of the conveyer belt. 
Expediently disposed on both sides of the conveyer belt, to support those 
edge regions of the lower run of the cover belt that project laterally 
beyond the conveyer belt, are sets of support rollers that are oriented at 
an angle of incline relative to the horizontal. It is furthermore 
advantageous in the central portion of the lower run of the cover belt, to 
provide one or more freely rotatable pressure rollers that are radially 
adjustable in the direction toward the covered material that is being 
transported. 
According to the inventive association of the cover belt with the conveyer 
belt, an enclosed transport of material is assured even where the hose 
belt gradually opens and where it is completely open in a flattened or 
trough-like state. The endpoints of the cover belt guidance are determined 
by respective guide rollers. Disposed between these endpoints are one or 
more other guide rollers that keep the upper run at a sufficient distance 
from the lower run. This results in the characteristic arrangement pattern 
of an angle that is open toward the covered conveyer belt, with the lower 
run of the cover belt additionally being supported against that guide 
roller that guides the conveyer belt, in its flattened end state, into the 
horizontal stretch. The close association of the cover belt with the 
conveyer belt results in the cover belt, in a convexly curved manner, 
being pulled into the hose belt cross-section already in the starting 
phase of the opening process, and results in the cover belt resting 
tightly upon the loose material that is being transported. This effect is 
particularly enhanced if, pursuant to a preferred embodiment of the 
invention, the cover belt contains load-carrying cords that are embedded 
exclusively in the edge regions and that extend in the longitudinal 
direction. Pressure rollers that rotate on the lower run of the cover belt 
assure direct contact with the transported material independent of all 
shifting thereof caused by the progressive cross-sectional changes of the 
conveyer belt. The cover belt is supported on both sides on the bent-up 
belt edges that gradually diverge from one another. Thus, the transported 
material is reliably covered by the cover belt in every phase of the belt 
movement until, after passing the end guide roller, it is discharged or, 
where merely a change in incline of the conveying stretch is involved, the 
material is again conveyed into a hose-like closed stretch. 
For the design of the discharge location, the present invention offers and 
provides the advantage of a precise and protected guidance of the mass 
flow if the cover belt, in contact with the flat-planar conveyer belt, is 
guided through a limited curve angle about the end guide roller of the 
conveyer belt, and below this, is guided about a lower guide roller that 
is placed ahead in the direction of discharge. In this way, the dropping 
material can be held tightly together in a dense stream, the direction of 
which can be determined. Since the lower run of the cover belt moves at 
practically the same downward speed as do the impacting particles of 
transported material, the cover belt is subjected to very little wear. To 
be able to finally adjust the conditions to the characteristics of 
different transported material having respectively different discharge 
parabolas, a preferred embodiment of the present invention proposes that 
the lower guide roller of the cover belt be mounted in such a way that it 
is adjustable in the radial direction in a plane that is parallel, or at 
least essentially parallel, to the discharge direction. 
The width of the cover belt is expediently of the order of magnitude of the 
width of the conveyer belt in its flat-planar state. For very great 
transport capacities, it is advantageous to provide the cover belt, on 
that surface which faces the conveyer belt, with continuous, resilient 
wall or side elements that are placed on the edges of the cover belt. So 
that it is possible to take along larger quantities of material, these 
wall elements enclose along with the conveyer belt, which in the end phase 
of the opening process is bordered on both sides by these elements, a 
space that is considerably greater than that created when the cover belt 
rests in a flat state on the material transported by the conveyer belt. It 
is furthermore recommended in this situation that the load-carrying cords 
that extend in the longitudinal direction be embedded exclusively in these 
wall elements. 
Further features of the present invention will be discussed in detail 
subsequently. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to the drawings in detail, the portion of the conveyer system 
illustrated in FIG. 1 contains a conveyer belt 7 of synthetic rubber; 
load-carrying cords that extend in the longitudinal direction are 
preferably embedded only in the edge regions of the conveyer belt 7. In 
steeply inclined stretches, the conveyer belt 7, by means of sets 8 of 
idler or support rollers that are grouped together in a garland fashion, 
is movably supported and formed into a hose belt having an approximately 
circular cross-sectional shape with edges that overlap one another. On the 
other hand, to discharge or dump the material that is being conveyed, the 
conveyer belt 7 is opened by the end guide roller 9 in a continuous 
process by an appropriate grouping of the support rollers. Finally, the 
conveyer belt 7 is spread to its full linear width as it runs up on the 
guide roller 9. The returning empty run can be guided on customary single 
cylindrical support rollers 10. 
Disposed above the conveyer belt 7 is a cover belt 11 that extends over the 
transition region of the conveyer belt from its completely closed state to 
its completely opened state. In the illustrated embodiment, the cover belt 
11 is endlessly guided over three guide rollers 12, 13, 14, and is 
associated with the conveyer belt 7 in the shape of an angle that is open 
toward the latter. The rearward guide roller 12, as viewed in the 
direction of conveyance, preferably serves as the drive roller and is 
stationarily freely rotatably mounted directly or only slightly ahead of 
the transition region of the conveyer belt 7, which region is defined by 
the start of the first opening movement. In contrast, the forward guide 
roller 14 is disposed at a great distance ahead of, and at an angle below, 
the end guide roller 9 of the conveyer belt 7. The upper or central guide 
roller 13, about which the upper run of the cover belt 11 is looped, is 
mounted in such a way as to be slightly radially adjustable in order to be 
able to regulate or alter the tension of the cover belt when necessary. 
Thus, for example, shifting of the guide roller 13 into the position 
indicated by dashed lines in FIG. 1 leads to a slackening along with a 
change of the discharge tangent as shown by the dashed line in the dumping 
position. The guide roller 14 can be adjusted in a wide range as indicated 
by the double arrow I. The necessity or advantage of such alterations in 
the geometry of the cover belt guidance results, for example, from a 
change of the material that is being conveyed, which routinely also 
involves changes in the falling and impact conditions. 
FIG. 2 illustrates the conveyer belt 7 in the first third of the transition 
zone in a partially opened state. Under the effect of gravity, and as a 
result of the exclusive placement in the edge regions of the load-carrying 
cords that absorb tension forces, the lower run of the cover belt 11 is 
drawn convexly, in an appropriately V-shape, into the increasingly opening 
gap of the originally circular cross-section. In so doing, the lower run 
of the cover belt 11 rests with slight pressure upon the material 16 that 
is being transported. This lower run is linearly supported on the still 
bent-up side edges of the conveyer belt 7. However, those side regions of 
the lower run that extend beyond these bent-up side edges of the conveyer 
belt 7 are additionally guided on inclined cylindrical support rollers 15. 
The cross-sectional view of FIG. 3 shows an opening state or condition 
that has already progressed further, with a freely rotating pressure 
roller 18, to which is applied a variable force P, pressing the central 
portion of the lower run of the cover belt 11 down onto the material 16 
that is being transported in a more intense manner. In the end state 
(prior to the material 16 being dumped) or final condition as illustrated 
in FIG. 4, the conveyer belt 7 runs in a fully spread state or condition 
onto the guide roller 9 and, as this guide roller rotates further, 
discharges the compactly held material 16 in a constantly uniform 
direction at a precisely defined adjustment of the roller. Since the mass 
flow in free fall no longer describes a parabola of changing chord length, 
but rather a movable guidance is provided for that leg of the cover belt 
11 that continues downwardly at an angle, the impact zone can be precisely 
localized in a narrowly defined manner. 
In FIG. 5, the transition of the conveyer belt 7 from a steeply inclined 
stretch into a continuing horizontal stretch is illustrated using a cover 
belt 11 in the inventive arrangement. In this case, the guide or 
deflection roller 19 does not mark the end of the conveying stretch, but 
rather marks only a change in direction that is connected with a change in 
shape of the conveyer belt 7, which is initially closed to form a hose 
cross-section. The operation is essentially the same as that described in 
conjunction with FIGS. 1 to 4. 
In the embodiment illustrated in FIG. 6, the cover belt 11 is provided with 
flexible wall or side elements 17 that are placed on the side edges, so 
that when the conveyer belt is spread to its full width, the cover belt 11 
can trap a greater volume of material than is possible when the cover belt 
rests upon the material in a flat state or condition. In other respects, 
the operation of this embodiment is essentially the same as that 
previously described. 
The present invention is, of course, in no way restricted to the specific 
disclosure of the specification and drawings, but also encompasses any 
modifications within the scope of the appended claims.