Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Lifting device, in particular patient lifter, with an unrolling prevention
device
The content of the German application DE 10 2012 202 257.0 is adopted
The invention relates to a lifting device and, in particular, a patient
lifter,
comprising a drive motor with an output shaft and a winding coil rotatably
mounted on the output shaft to wind and unwind a lifting mechanism,
Lifting devices of this type are, for example, used as so-called patient
lifters for transporting a disabled person.
event of a motor failure or a component breakage within the lifting device,
lifting devices of this type have to be equipped with an unrolling
prevention device, which automatically ensures a stopping of the lifting
mechanism in a suitable manner, for example by a blocking of the winding
20 coil.
Similar securing devices are also required for rolling doors, sectional
doors, roller blinds or the like, which people pass through.
inferred from EP 0 940 134 A2. The shaft of the drive motor is connected
to a ratchet disc here, which has projections distributed over its periphery.
These form a hook geometry that cooperates with a locking lever
peripherally arranged on the ratchet disc. The ratchet disc is locked
28 07 2014 H/H P1,0156W0 2014050489 DOC
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depending on the rotational speed, the locking lever being controlled due to
gravity.
The problem with this unrolling prevention device is the fact that a specific
rotational speed ¨ in other words a relatively high falling speed of the
lifted
person ¨ firstly has to be reached until the blocking mechanism sets in
suddenly. This may entail serious injuries in terms of health for injured
people moved with the aid of the patient lifter.
A rolling door securing device is known from DE 20 2004 012 024 Ul, the
engagement of which takes place by means of a mechanical centrifugal
force control. The advantages mentioned of the prior art also apply here.
The invention is based on the object of disclosing a lifting device, which
ensures a gently responding but effective unrolling prevention device in all
the phases of application.
This object is achieved by the features disclosed in the characterising part
of the claim and is characterised by
- a mounting of the winding coil that can be rotated relative to the
output shaft,
- an abutment body non-rotatably connected to the winding coil,
- at least one clamping body, which can be displaced radially with
respect to the output shaft between the inner abutment body and an
outer locking ring, said clamping body being coupled by means of a
coupling arm, which is articulated to the output shaft, to the latter in
such a way that
= in the event of a torque produced by the output shaft both in the
winding and in the unwinding direction, the clamping body can
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be transferred from its locking position resting on the locking
ring into a torque transmission position resting on a wedge face
of the abutment body to rotate the abutment ring with the
winding coil independently of the load-induced counter-torque
acting on the winding coil, and
= in the event of a torque-free output shaft, owing to the load-
induced counter-torque on the winding coil, the at least one
clamping body is loaded by the wedge face of the abutment body
radially outwardly into the locking position resting on the
locking ring with rotary blocking of the abutment body with the
winding coil.
Because of this concept, the lifting device according to the invention is
designed with a complete functional range as a lifting, lowering, stopping
and securing unit. In this case, a separate motor brake for stopping and a
separate securing unit, such as is also used, for example, in the form of an
electromagnetically activated locking element in the known unrolling
prevention device according to EP 0 940 134 A2, is avoided, as is a
disadvantageous, centrifugal force-controlled brake or lock. Because of the
release and locking of the lifting device acting both in the winding and in
the unwinding direction, the latter acts like a switchable freewheel acting in
both directions, which reacts selectively to a torque introduction on the
drive and output side. To this extent its function is, in particular,
independent of the rotational direction of the drive side, on the one hand,
and the output side, on the other hand. As no components operating due to
gravity are present, the function of the lifting device with the unrolling
prevention device is also independent of its installation position.
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A further important advantage is furthermore that because of the
arrangement of the unrolling prevention device between the output shaft
and winding coil, the electric motor itself can also be exchanged under load
on the lifting mechanism. Equally, an emergency lowering can be carried
out by a direct emergency actuation of the output shaft if the drive fails.
The latter is also released by means of the unrolling prevention device
according to the invention of the lifting device.
Preferred embodiments of the invention are given in the dependent claims,
the features, details and advantages of which are described in more detail in
the following description of an embodiment with the aid of the
accompanying drawings, in which:
Fig. 1 shows a partially broken away, perspective view of the
lifting device,
Fig. 2 shows a vertical rotational axial section of the lifting
device according to Fig. 1 and
Figs. 3 and 4 show sections along the section line A-A according to Fig.
2 in different functional positions of the lifting device.
As emerges from the accompanying drawings, the lifting device designated
1 as a whole is fastened to a solid U-shaped bow 2, which is either
stationarily attached to a ceiling of a room or to a travelling trolley of a
ceiling rail system. In the case first mentioned, the lifting device 1 is
merely used to lift and lower a patient and in the case mentioned second,
the patient can additionally be brought to a different location with the aid
of the rail system.
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The lifting device 1, as the central drive part, has a gear motor 3 with an
electrically operated motor unit 4 and an upstream planetary gear 5. The
gear motor 3 is flanged to the U-shaped bow 2 laterally on the outside. Its
output shaft 6 projects by way of a bore 7 into the interior 8 between the
limbs 9, 10 of the bow 2, where the remaining components of the lifting
device 1 with the unrolling prevention device are accommodated. A
winding coil 11 is thus provided, between the cheeks 12 of which a belt 13
indicated in Fig. 2 layerwise and running out to the bottom can be wound
and unwound. The winding coil 11 is rotatably mounted relative to the
output shaft 6 by means of ball bearings 14 relative thereto. This winding
coil 11 is rigidly connected by one of its cheeks 12 ¨ the right-hand one in
relation to Fig. 2 ¨ to an abutment body 15 by means of fixing screws 16,
said abutment body being substantially disc-shaped. Three bearing
extensions 17, which are rotatably supported at their ends in a pivot bearing
18 in an annular bearing body 19, project in the axially parallel direction
from the abutment body 15 from the side remote from the winding coil 11.
The bearing body 19 is screwed to the inside of the second limb 10 of the
bow 2 opposing the gear motor 3 by means of screws 20. On its side
facing the winding coil 11, the bearing body 19 has a projecting annular
shoulder that forms a locking ring 21 of the unrolling prevention device in
the lifting device 1. The abutment body 15 is arranged radially within this
locking ring 21, said abutment body forming, with corresponding recesses,
three receivers 22 arranged angle-symmetrically with respect to the
rotational axis R of the lifting device, said receivers in each case having,
on
the inside, wedge faces 23 adopting a large obtuse angle W of about 150
with respect to one another. Said wedge faces are symmetrical with respect
to a radial line passing through the apex of the angle.
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Congruently formed clamping bodies 24, the radially outer side 25 of
which is arc of a circle-shaped with an external diameter corresponding to
the internal diameter of the locking ring 21, are inserted in the receivers
22,
in each case. The two clamping bodies 24 radially inwardly have contact
faces 26 in each case, which are at the angle W to one another and
cooperate with the wedge faces 23 of the receivers 22 in the abutment body
in a manner still to be described in more detail.
The clamping bodies 24 are in each case coupled to the output shaft 26 by
10 means of a coupling arm 26 articulated to the end face of the output
shaft 6
by means of pivot bolts 28. The connection between the coupling arm 27
and clamping body 24 takes place here by means of a sliding connection
that is radially affected by play, which is realised by a connecting bolt 29
on the side face of the clamping body 24 in a radially directed slot 30 in the
15 coupling arm 27.
Finally, each coupling arm 27 is spring-loaded by paired tension springs 31
clamped between its inner end and the abutment body 15, which will be
functionally described in more detail below.
The mode of functioning of the lifting device 1 with an unrolling
prevention device is now to be described as follows:
In the locking position of the lifting device shown in Fig. 3, the output
shaft 6 is torque-free and, without further securing measures, in the event
of a load-induced counter-torque G, upon the exceeding of the inner
inhibition of the gear motor 3, would lead to an uncontrolled unwinding of
the belt 13.
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In order to prevent this, the lifting device has the unrolling prevention
device formed from the abutment body 15, clamping body 24 and locking
ring 21. The counter-torque G is transmitted by the winding coil 11 to the
abutment body 15, which therefore exhibits the tendency to rotate
clockwise in relation to Fig. 3. Owing to this introduction of force, the
clamping bodies 24 are pressed radially outwardly by means of their
contact faces 26 by means of the wedge faces 23 of the receivers 22 in the
abutment body 15, so they come into braking engagement with the
clamping ring 21 and therefore prevent a further, uncontrolled rotation of
the abutment body 15 with the winding coil 11. The coupling arms 27 are
therefore radially erected and are symmetrical to a radial line running
through the pivot bolts 28. The lifting device 1 is therefore reliably
rotationally blocked.
In the event of an actuation of the gear motor 3, for example to lift a load
counter to the counter-torque G, the drive torque D produced by the gear
motor will ensure a rotation of the output shaft 6 in the anti-clockwise
direction in relation to Fig. 4. This rotary movement is transferred to the
coupling arms 27, which, figuratively speaking, "bend in" and are drawn
radially inwardly by their outer ends. As a result, the connecting bolt 29 in
the slot 30 comes to abut the radially outer end thereof. Upon a further
rotation of the output shaft 6, the clamping bodies 24 are drawn radially
inwardly so they leave the locking position on the locking ring 21. Owing
to the abutment of the contact faces 26 of the clamping bodies 24 pointing
in the direction of the drive torque D on the corresponding wedge faces of
the receivers 22 in the abutment body 15, the latter is entrained in the
direction of the drive torque D and the winding body 10 is correspondingly
made to carry out the rotary movement. A patient suspended on the belt is
thus drawn upwardly.
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When the gear motor 3 is switched off, the counter-torque G is active
again, so the coupling arms 27 are erected again under the influence of the
abutment body 15 on the clamping bodies 24 and the latter are pressed
radially outwardly onto the locking ring 21 into the blocking position.
Thus the position shown in Fig. 3 is adopted again.
To let down the patient ¨ as is not shown in more detail in the drawings ¨
the output shaft 6 is made to rotate parallel to the counter-torque G, so the
coupling arms 27 "bend in" in the opposite direction in relation to Fig. 4
and thus pull the clamping bodies 24 radially inwardly again. As a result,
the rotary blocking of the lifting device 1 is eliminated again and the load
can be safely let down under the control of the gear motor 3
The mentioned tension spring pairs 31 in this case assist the erecting
movement of the coupling arms 27 and the aligning connected therewith of
the output shaft 6 and abutment body 15 in relation to one another into the
blocking position shown in Fig. 3. The interaction between the two
rotational directions of the drive torque D to wind and unwind the belt 13 is
configured overall in the manner of dead centre kinematics, in which the
coupling arms 27 bend in once in the unwinding or winding direction, in
other words in opposite directions, depending on the torque direction.
Instead of the planetary gear 5, a spur gear may also be provided for the
output shaft 6, the motor unit 4 then not being arranged aligned with the
output shaft in the axial direction, but being arranged laterally adjacent
thereto with a parallel offset.
Finally, as indicated in Fig. 2, the bow 2 may have a central through-bore
33 in its limb 10 remote from the gear motor 3, by way of which through-
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bore a tool connection 34 rests on the output shaft 6 in the access region.
The tool connection 34 may, for example, be formed by the extended pivot
bolts 28, on which a rotary handle with its tool head having three
corresponding receiving bores can be placed. Thus, an emergency
lowering can take place if the gear motor 3 fails by manual rotation of the
output shaft 6 with the aid of this rotary handle.
Because of the mode of construction shown of the lifting device 1, a
modular system can advantageously be realised, in that the output shaft 6
can be equipped with the most varied gear motors. Owing to the
symmetric construction of the lifting device 1, many identical parts are
produced here, which involves a small diversity of parts in the
construction.
Overall, a very compact, reliably operating lifting device 1 with an
unrolling prevention device is provided.
