Note: Descriptions are shown in the official language in which they were submitted.
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Support system for the suspension of a roller broom
on a sweeping vehicle
The present invention relates to a support system for the
suspension of a roller broom on a sweeping vehicle,
comprising a rotary support mounted to turn on the sweeping
vehicle around a vertical slewing axis, a support part
suspended on the rotary support via a lifting mechanism
comprising a lifting drive, and a broom frame mounted on the
support part to rock around a horizontal axis extending
perpendicular to the axis of rotation of the roller broom.
Such support systems are known from practice. Sweeping
vehicles in which the roller brooms are suspended by means
of appropriate support systems are used, for example, for
so-called black-clearing at airports, where snow must be
removed as completely as possible from traffic surfaces. The
pendulum suspension of the roller broom then compensates on
the one hand for local fluctuations of the side inclination
of the surface to be cleaned, and on the other hand any
lateral roll of the sweeping vehicle when cornering, for
example. In known support systems of the class in question,
the rocking position of the broom frame is urged into a home
position by means of suitable spring elements (such as
rubber springs or gas-filled springs), in order actively to
level the broom unit (meaning the broom frame together with
the roller broom suspended thereon), which is raised during
transport travel of the sweeping vehicle. Such leveling is
important, because the snow burden that otherwise frequently
occurs in practice on one side (especially due to snow dust
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deposited on the broom cover) causes the roller broom to
scrape on one side during transport travel. In such sweeping
vehicles, in which the roller broom is locked in
longitudinal direction of the sweeping vehicle during
transport travel, the roller broom would also scrape on one
side during acceleration and braking of the sweeping vehicle
if such leveling of the broom unit did not take place.
US 2004/0040103 Al discloses a support system for the
suspension of a roller broom on a sweeping vehicle, with the
difference from the prior art of the class in question
explained hereinabove that no lifting mechanism comprising a
lifting drive is provided therein. For lack of an ability to
lift the support part, the problem addressed in the
foregoing is not solved therein.
From US 4643261 A there can be inferred a support system for
the suspension of a roller broom on a sweeping vehicle, with
the difference from the prior art of the class in question
explained hereinabove that the broom frame therein is not
mounted on the support part to rock around a horizontal axis
extending perpendicular to the axis of rotation of the
roller broom. For lack of such rocking ability, the problem
addressed in the foregoing is also not solved therein.
In known sweeping vehicles with support systems configured
according to the class in question for the roller broom, the
result of cleaning is unsatisfactory under various service
conditions (such as cornering at a speed above a specified
value). The object of the present invention is to remedy
this shortcoming.
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This object is achieved according to the present invention
in that, in a support system of the class in question, there
is provided in the region of the pendulum bearing of the
broom frame a locking member, which can occupy a first
position that enables the rocking movement of the broom
frame and a second position that disables the rocking
movement of the broom frame in its leveled condition, and on
which there acts the lifting drive of the lifting mechanism
in such a way that the locking member occupies its second
position when the lifting drive is activated. A
characteristic viewpoint of the present invention is
therefore that the lifting drive of the lifting mechanism
acts on the locking member and, when the lifting drive is
activated in order to raise the broom unit, the locking
member is necessarily actuated, and specifically is brought
from its first position enabling rocking movements of the
broom frame into its second position disabling the rocking
movement of the broom frame in leveled condition. On the way
from its first to its second position, this locking member
brings the broom frame into its leveled condition. If the
lifting drive is nevertheless deactivated during use of the
broom (for example by a hydraulic lifting cylinder switched
to floating position), so that the roller broom can follow
the surface to be cleaned by vertical compensating
movements, rocking movements of the roller broom that
compensate for different side inclinations of the surface to
be cleaned and/or different lateral rolls of the sweeping
vehicle are also directly possible. A particular advantage
is then that the broom unit can rock freely and without any
bias force in the floating position defined by the first
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position of the locking member. In this way, it is ensured
that the roller broom bears over its entire length with the
same bearing force on the surface to be cleaned even in the
case of substantial lateral roll of the sweeping vehicle,
especially while cornering at high speed. This is a decisive
difference compared with prior art sweeping machines, in
which lateral roll of the sweeping vehicle leads to a
different bearing force of the roller broom over its length
due to the bias force of the broom frame toward a home
position relative to the chassis of the vehicle. Without
complex technical devices, therefore, the roller broom is
automatically leveled and fixed in this position according
to the invention while the broom unit is raised, and is
enabled in its lower position, or in other words is
decoupled from the chassis of the sweeping vehicle as much
as possible.
Although a different mounting of the locking member
(especially on the support part or on the broom frame) is
entirely conceivable in the scope of the present invention,
the locking member according to a first preferred
improvement of the invention is mounted to swivel around an
axis extending parallel to the axis of rotation of the
roller broom, and in fact particularly preferably on the
broom frame. In the latter cited case, the point of action
of the lifting drive and the articulated linkage of the
locking member can be disposed on the broom frame,
especially on different sides of the broom frame. Such a
configuration is characterized by particularly high
functionality.
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The same is true if the locking member in its first position
comprises part of a stop device to limit the rocking
movement of the broom frame to a predetermined range. With
such a dual function of the locking member, the inventive
5 support system is effective with a minimum of components.
Specifically in this case, it is particularly favorable if
shock-absorbing buffer elements that come into effect at
least near the end of the permissible rocking movement are
disposed on the locking member.
According to another preferred improvement of the invention,
it is provided that the locking member is formed as a
bracket provided with two cheeks, which bracket embraces the
connecting joint between the support part and the broom
frame. In this case it is particularly preferable for the
support part to be provided adjacent to its articulated
connection with the broom frame with respective stops for
each of the two cheeks of the bracket.
Certainly the present invention can obviously be implemented
with differently constructed lifting mechanisms. According
to a particularly preferred improvement of the invention,
however, the lifting mechanism comprises a parallelogram-
type linkage. It is then particularly favorable if the
parallelogram-type linkage comprises two double link arms,
wherein the link-arm pairs of the two double link arms
respectively receive the support part and the rotary support
between them. The lifting drive can also be disposed between
the link-arm pairs of the two double link arms in this case,
whereby it is mounted in particularly well protected manner.
Nevertheless, a corresponding arrangement of the lifting
drive between the rotary support and the support part is
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also advantageous if the parallelogram-type linkage of the
lifting mechanism does not comprise any double link arms.
The present invention will be explained in more detail
hereinafter on the basis of a preferred practical example
illustrated in the drawing, wherein:
Fig. 1 shows a perspective, slightly schematic view, looking
obliquely from the left rear upper region, of a support
system according to the present invention with the
broom unit lowered,
Fig. 2 shows a detail view of the region of the pendulum
suspension of the broom frame of the support system
according to Fig. 1,
Fig. 3 shows a view, looking obliquely from the left rear
upper region, of the support system according to Figs.
1 and 2 with the broom unit raised, and
Fig. 4 shows a view, looking obliquely from the left front
lower region, of the support system according to Figs.
1 to 3, also with the broom unit raised.
Support system 1 shown in the drawing for the suspension of
a roller broom 2 on a sweeping vehicle comprises a rotary
support 3, a lifting mechanism 4, a support part 5 and a
broom frame 6. Rotary support 3 is mounted on the sweeping
vehicle and can turn around a vertical slewing axis 7.
Thereto there is linked support part 5, which can be raised
and lowered via lifting mechanism 4. For this purpose, the
lifting mechanism comprises a parallelogram-type linkage 8
with an upper double link arm 9 and a lower double link arm
10. The link-arm pairs of each of the two double link arms 9
and 10, connected in known articulated manner to rotary
support 3 and support part 5, receive support part 5 and
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rotary support 3 between them. The two link arms 11 of lower
double link arm 10 are rigidly connected to one another by
means of two connecting pieces 12 and 13.
On support part 5 there is suspended broom frame 6, which is
constructed as a rectangular pipe and on which roller broom
2 is mounted to rotate in a manner known in itself around
its long axis L. This suspension is achieved by a pendulum
bearing 14 in the form of a swivel joint 15, which connects
broom frame 6 to support part 5 such that it can rock around
horizontal axis 16 extending perpendicular to axis of
rotation L of roller broom 2.
In the region of pendulum bearing 14 there is provided a
locking member 17 in the form of a bracket 18, which
comprises two cheeks 19 and 20, two connecting pieces 21 and
22 connecting these to one another and two stiffening plates
23 and 24. This bracket 18 embraces swivel joint 15, by the
fact that the two cheeks 19 and 20 are disposed on different
sides of the swivel joint. On front connecting piece 21
there acts, via a ball head, a lifting cylinder 25, which
forms lifting drive 26 associated with lifting mechanism 4
and whose other, upper end is stopped against rotary support
3, again via a ball head.
By means of the two bearing straps 27 welded on broom frame
6, bracket 18 is mounted on broom frame 6 such that it can
slew around axis 28 extending parallel to axis of rotation L
of roller broom 2. Thereby it can occupy a lowered, first
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position releasing the rocking movement of broom frame 6 and
a raised, second position leveling the broom frame and
disabling the rocking movement of the leveled broom frame.
In the second position of bracket 18, raised by activated
lifting cylinder 25, cams 29 of cheeks 19 and 20 bear
against the underside of a stop plate 30, which forms a
component of support part 5. Hereby the rocking movement of
broom frame 6 is locked in its leveled condition; at the
beginning of raising of the broom unit as a result of
activation of lifting cylinder 25, bracket 18 is brought
from its first position into its second position, thus
leveling the broom unit. In contrast, bracket 18 can occupy
its lowered first position when the hydraulic cylinder is
switched into its floating position, in which the broom unit
can follow ground irregularities and/or different elastic
deflections of the sweeping vehicle without hindrance by
corresponding up and down movements of the support part. In
this first position of bracket 18, the broom unit can
execute rocking movements around swiveling axis 16 without
hindrance and without any bias force, within a predetermined
angular range.
In order to cushion rocking movements at the end of the
permissible range, buffer elements 31 and 32, which are
formed as rubber buffers attached at the top and bottom of a
corresponding beam 33, are provided on each of cheeks 19 and
20 of bracket 18. When bracket 18 occupies its first
position, the two lower buffer elements 32 bear on the top
of broom frame 6, and so a small gap permitting elastic
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deflection of the lower buffer elements 32 is present
between cheeks 19, 20 and the top side of broom frame 6; a
gap - in the leveled condition of the broom unit - is also
present on both sides between cams 29 of cheeks 19 and 20
and stop plate 30. If the broom unit is deflected from its
leveled condition, that one of the two upper buffer elements
31 which is located on the upwardly moving side of the broom
unit comes into contact, at a predetermined rocking angle,
with the underside of stop plate 30, thus damping further
rocking movement before or possibly when, during further
compression of upper buffer element 31, cam 29 associated
with this side strikes against the stop plate. The two lower
buffer elements 32 are also compressed in this case, to the
point, in fact, that the lower edges of cheeks 19 and 20
bear on the top of broom frame 6. To this extent bracket 18
in its first position also represents part of a stop device
limiting the rocking movement of broom frame 6.
Merely for clarification it is pointed out that a gap
between upper buffer elements 31 and stop plate 30 is by no
means absolutely necessary in the first position of bracket
18. To the contrary, it is entirely possible for the two
upper buffer elements 31 to bear against stop plate 30 and
for the two lower rubber buffers 32 to bear against broom
frame 6 in the first position of bracket 18 with leveled
broom unit. Even in this case, the corresponding support
system still exhibits a decisive advantage compared with the
prior art, because the buffer elements, in contrast to the
spring units used in known support systems, can be made to
be relatively compliant, depending on how positional
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stability of the raised broom unit in its leveled condition
is achieved by the explained separate locking member.
Obviously the broom unit suspended on the illustrated
5 support system is capable of more than executing rocking
movements around swiveling axis 16 without hindrance.
Compared with the prior art, up and down movements of the
broom unit to follow ground irregularities are also
facilitated within a predetermined fluctuation range. This
10 is so because not every deflection movement of the broom
unit in vertical direction leads to a change in length of
lifting cylinder 25 and thus to displacement of hydraulic
fluid to prevent rapid deflection; to the contrary, the
broom frame together with support part 5 can execute
movements within a predetermined fluctuation range in
vertical direction without causing a change in length of
lifting cylinder 25, because of the gap of cheeks 19 and 20
of bracket 18 between stop plate 30 on the one hand and
broom frame 6 on the other hand. This is particularly
favorable for an excellent cleaning result on surfaces with
relatively short and shallow ground irregularities.
