Note: Descriptions are shown in the official language in which they were submitted.
CA 02596699 2007-08-09
1
Lift installation with a lift support means, lift support means for such a
lift
installation and production method for such lift support means
The present invention relates to a lift installation with a lift support
means, a lift support
means for such a lift installation and a production method for such a lift
support means.
A lift installation comprises a lift cage and usually a counterweight, which
are movable in a
lift shaft or along free-standing guide devices. For producing the movement,
the lift
installation comprises at least one drive unit with at least one drive wheel,
which supports
the lift cage and the counterweight by way of one or more lift support means
in the form of
belts and/or transmits the required drive forces to the cage and
counterweight.
A lift installation according to category is known from EP 1 555 234 B1, in
which the belt
has on a traction side facing the drive wheel a rib arrangement with several
wedge-shaped
ribs, which extend in longitudinal direction of the belt and which engage in
corresponding
grooves on the drive wheel. Due to the fact that the contact between the ben
and the drive
wheel takes place by way of the inclined flanks of the wedge-shaped ribs and
grooves
respectively, the pressing pressure against the drive wheel and thus the
traction capability
or drive capability increases for the same radial force and therefore the same
bearing
loading and belt tension. At the same time the wedge ribs advantageously guide
the belt
in transverse direction on the drive wheel. Since the belts contain tensile
carriers with
relatively small diameters, it is possible to use drive wheels with smaller
diameters. In
particular, the drive output shaft of the drive unit can itself also be
constructed as drive
wheel.
A single, freely movable wedge rib advantageously centres itself in a
corresponding
groove of a drive wheel or a deflecting wheel by way of the inclined flanks,
wherein
compensation for production tolerances and wear of the belt, which has the
wedge rib,
and/or of the drive wheel itself is provided by radial engagement of the wedge
rib in the
groove to different depths. Thus, for example, a wedge belt, which due to wear
of its
wedge flanks has a width smaller relative to the nominal dimension, rests
deeper in radial
direction in a complementary groove which, due to production tolerances, has a
width
greater relative to its nominal dimension. Nevertheless, by virtue of the
wedge flanks the
belt lies centred in the groove of the drive wheel under friction couple.
Overall, a freely
movable wedge rib can provide compensation for deviations in shape resulting
from
CA 02596699 2007-08-09
2
production tolerances of the rib and/or the associated groove in the drive
wheel and also
from wear of rib and/or groove. At the same time, several relatively movable
wedge ribs
can provide compensation for positional deviations, particularly different
spacings of the
ribs and grooves from one another, in belt transverse direction and also in
radial direction
of the drive wheel.
If the rib arrangement comprises, as in EP 1 555 234 B1, several wedge ribs
formed on
the same belt body, this self-centring and compensation for deviations in
shape and/or
position of the individual ribs and associated grooves are no longer possible.
In addition,
deviations in the spacings of the individual ribs and/or grooves relative to
one another
disadvantageously have the consequence that not all wedge ribs are disposed in
homogeneous engagement with the associated grooves.
The belt body is usually made of an elastomer which, due to its elasticity
does indeed
allow a certain relative movement of the individual ribs and thus enables the
above-
described self-centring and compensation for positional and shape deviations
of the ribs
and grooves to a limited extent. It is disadvantageous that this compensation
is possible
only within close limits and under significant elastic deformation of the belt
body, wherein
this deformation leads to premature ageing of the belt due to the alternating
tensile,
compressive and shear stresses connected therewith. This obliges a higher
level of
maintenance effort for the lift installation, since the belt has to be more
frequently checked
and exchanged. In addition, the elastic deformation of the belt body increases
the risk that
individual ribs do not completely bear in the grooves, but in part work out of
this.
A belt for a belt drive is known from US 3 996 813, which comprises individual
wedge ribs,
which are connected only by a carrier band of an elastomer, with tensile
carriers arranged
therein. By contrast to a lift installation in which the relative position
between drive and
deflecting wheels, around which the belt runs, constantly changes, in the belt
drive of US 3
996 813 the driving and driven drive pulleys are inertially fixed so that a
high level of
stiffness in belt transverse direction is not necessary here. In addition,
variable run
lengths, such as occur in a lift installation and hamper the use of belts
which are soft in
transverse direction, do not occur in such a belt drive, because with large
free run lengths
and drive or deflecting wheels moving relative to one another soft belts have
a tendency to
twist about the longitudinal axis thereof and to bend in transverse direction.
Moreover, in
the belt drive discussed in US 3 996 813 the belt is deflected only over its
traction side so
CA 02596699 2007-08-09
3
that its belt rear side remote therefrom is free of contact, whereas in lift
installations with
fixed and free deflecting wheels the lift support means frequently also loops
around
deflecting wheels by its belt rear side.
Accordingly, the specification also proposes an elastomer carrier band, which
is reinforced
with tire cord threads and which does indeed satisfactorily connect with the
elastomer
wedge ribs, but has only a low transverse stability and wear resistance on the
belt rear
side. The belt known from US 3 996 813 is therefore unsuitable for use in a
lift installation
in which the run regions, which in part are long, between drive and deflecting
wheels, the
variable run lengths and the deflection also over the belt rear side impose
higher demands
on the transverse stability and wear resistance of the belt.
The object of the present invention is to construct a lift installation, which
is known from EP
1 555 234 B1, to be lower in maintenance.
For this purpose a lift installation according to the introductory part of
claim 1 is developed
by the characterising features thereof. In claim 9 a lift support means for
such a lift
installation is made available and in claim 9 a method for production thereof
is indicated.
A lift installation according to the invention comprises a drive unit which by
way of a drive
wheel drives at least one lift support means supporting a lift cage, wherein
the lift support
means has on a traction side facing the drive wheel a rib arrangement with at
least two
ribs, which extend in longitudinal direction of the lift support means and
which engage in
corresponding grooves on the drive wheel. For transmission of the tensile
force in the lift
support means the belt arrangement comprises a tensile carrier arrangement
with at least
one tensile carrier arranged in a rib.
In a preferred embodiment at least one tensile carrier, with particular
preference more than
one tensile carrier, is or are arranged in each rib. In an alternative
embodiment a tensile
carrier is not associated with each of the ribs. The ribs which do not have
tensile carriers
can transmit only a small part of the tension force of the lift support means,
but serve for
guidance and centring of the belt in transverse direction.
According to the invention it is now proposed that a groove is formed between
two
adjacent ribs of the rib arrangement and reaches substantially up to a carrier
band which is
CA 02596699 2007-08-09
4
arranged on the belt rear side of the lift support means remote from the
traction side and to
which the ribs of the rib arrangement are fastened.
The two ribs separated by the groove can thereby move relative to one another
in
transverse and/or height direction of the lift support means. This makes it
possible for the
at least two adjacent ribs to provide compensation for deviations in shape,
particularly the
width of the respective rib relative to the associated groove of the drive
wheel and/or
deviations in position of the ribs and/or grooves relative to one another,
through this
relative movement and to centre in the grooves without deforming the rib
bodies. This
reduces the stresses arising in the ribs and thereby increases the service
life thereof. As a
consequence, the maintenance outlay in the lift installation reduces due to
the longer
inspection intervals and the less frequent exchange of the belt.
In a preferred embodiment all ribs of the rib arrangement are separated from
one another
by respective grooves. This enables the above-explained compensation for
position and
shape tolerances between all ribs.
In an aftemative embodiment of the present invention not all ribs of the rib
arrangement
are separated by a respective groove. Even in this form of embodiment a
compensation
for positional deviations of the rib blocks separated by the groove or grooves
is still
possible, whereby there is avoidance, in particular, of formation of high
material stresses
over the entire width of the belt due to the deviations in position and/or
shape. Instead
thereof, due to the smaller positional deviations in each instance only
smaller deformations
arise within a rib block. On the other hand, less grooves reduce the
transverse stiffness of
the belt correspondingly less. For example, a groove is formed only between
the two
middle ribs of the lift support means.
Preferably the grooves reach up to the said carrier band, so that the adjacent
ribs
separated from one another by a groove are completely separated from one
another. This
allows a maximum movability of the ribs relative to one another, wherein
elastic
deformations of the rib body are reduced. For increase in transverse
stiffness, but also for
improved fastening of the ribs to the carrier band, the grooves can, however,
also end
shortly in front of the carrier band so that a thin web of rib material
connecting the ribs
remains on the carrier band. A greater connecting area between ribs and
carrier band is
thereby available. Advantageously such a web has approximately the thickness
of the
CA 02596699 2007-08-09
carrier band.
The ribs of the rib arrangement preferably have a contact section with a
substantially
trapezium-shaped or wedge-shaped cross-section for engagement in the
corresponding
grooves of the drive wheel. With such wedge ribs the pressing force of the
belt against the
drive wheel increases, and thus the drive or traction capability, for the same
radial force,
i.e. for the same bearing loading and belt tension. In that case cross-
sections with a flank
angle between 60 and 120 , preferably 750 and 105 and particularly
preferably 900, have
proved particularly advantageous.
The wedge flanks of these wedge ribs can reach almost up to the carrier band,
which
maximises the contact area with the flanks of the drive wheel grooves. This on
the one
hand reduces, due to the greater contact area, the wear of the ribs and
grooves co-
operating by friction couple. On the other hand, for the same rib spacing and
the same
wedge angle the height of the ribs reduces and thus their capability of being
able to
compensate for deviations in position and shape.
In an altemative embodiment the ribs of the rib arrangement have a base
section, which
lies between the contact section and the carrier band and the flanks of which
have an
angle relative to the carrier band different from that of the wedge flanks of
the contact
section. In particular, the base section can have a substantially rectangular
cross-section
or a trapezium-shaped cross-section with a smaller flank angle, i.e. with
steeper flanks.
This enables formation of higher ribs with less stiffness in bending, the ribs
being
particularly suitable for providing compensation for positional and shape
deviations, which
may be present, between the ribs of the belt and the grooves of the drive or
deflecting
wheels. Closely adjacent side surfaces of relatively high base sections also
increase the
transverse stiffness of the belt, since the opposite flanks of narrow grooves
already make
contact in the case of relatively small tipping of adjacent ribs. Excessive
twisting of the
belt about the longitudinal axis thereof is thus avoided particularly in the
long, free run
sections resulting in the case of a lift installation with a cage in the
uppermost or lowermost
storey. Advantageously the groove width, i.e. the narrowest spacing between
opposite
flanks of adjacent ribs, is approximately 10%, preferably 5% and particularly
preferably
2.5%, of the (maximum) rib width.
The tensile carriers are arranged in the ribs and contact the carrier band. In
this manner
CA 02596699 2007-08-09
6
the tensile carriers support the carrier band, which can be constructed to be
corresponding
thin and flexible. At the same time, the tensile carriers arranged at the
carrier band and
thus at the base of the individual ribs connected therewith increase the
stiffness of the
base region of the ribs. The deformations, particularly archings of the
contact surface of
the ribs relative to the carrier band, thereby reduce, which reduces the
loading of the
connection and thus counteracts detaching of the ribs from the carrier band.
By contrast
thereto, the upper region of the ribs free of tensile carriers is
correspondingly more resilient
and can absorb the compression or tension deformations resulting from the belt
bending
as well as better provide compensation for the afore-mentioned deviations in
shape and
position. The tensile carriers are preferably arranged in the neutral axis of
the belt or in
the vicinity thereof.
In production of the belt the tensile carriers can be advantageously pressed
under bias
onto the carrier band before the ribs are mounted on the carrier band in such
a manner
that they completely enclose the tensile carriers. By virtue of the bias the
tensile carriers
are fixed in correct position on the carrier band during production process.
The biasing of
the tensile carriers makes it possible to, for example, impose on the belt a
concave
intrinsic curvature towards the traction side, which can be useful in lift
installations in which
the drive and deflecting wheels are so arranged that the belt is always bent
in the same
sense of bending.
The tensile carriers of the tensile carrier arrangement can be constructed as
a single wire
or consist of singly or multiply stranded strands or cables, wherein the
strands or cables
can be made of steel wires or synthetic material fibres. It is also possible
to construct
different tensile carriers in different manner. By virtue of this and/or due
to the
arrangement of different tensile carrier numbers in the individual ribs it is
possible to
predetermine a distribution of stiffness for the belt. Thus, for example one
rib can have
two or more doubly or multiply stranded individual wires, whilst in another
rib several
tensile carriers are arranged which in turn have less individual wires. It is
thus possible to
achieve, for example, a decrease in the longitudinal stiffness of the belt
from the belt
centre towards the belt edge, whereby in the case of a slight skewed setting
of the axes of
the drive and deflecting wheels or even in the case of slight axial offset the
outwardly
disposed ribs of the belt can, by virtue of their lesser stiffness, provide
compensation for
these deviations.
CA 02596699 2007-08-09
7
In a preferred embodiment the ribs are made of a first material which
comprises an
elastomer, particularly polyurethane, polychloroprene and/or ethylene-
propylene-diene
rubber. Ribs of elastomeric material can, by virtue of their elasticity,
provide compensation
to a certain extent for deviations in shape and position and thus reduce the
relative
movement of the ribs necessary for this purpose. At the same time they are
particularly
suitable for the friction-coupling contact with a drive wheel and for the
transmission of the
tensile forces from this to the tensile carriers. In addition, they
advantageously damp
vibrations and shocks and thus increase the comfort of the lift installation.
In that case ribs
with a hardness of 70 to 100 Shore (A), preferably 75 to 95 Shore (A) and
particularly
preferably a hardness of 80 to 85 Shore (A), have proved particularly
favourable. Due to
the separation in accordance with the invention of the ribs by grooves the
ribs do not have
to deform or have to deform only slightly when there are shape and/or
positional deviations
of ribs and grooves, so that the aforesaid relatively stiff or hard elastomers
can be used.
Advantageously the carrier band is made of a second material comprising a
thermoplastic
plastics material, particularly polyamide (PA), polypropylene (PP),
polyethylene (PE),
polycarbonate (PC) or polyvinylchloride (PVC) or polybiend and/or of a fabric
of such a
thermoplastic plastics material. Equally, use can also be made of a mixture of
different
thermoplastic plastics materials, i.e. a so-termed polyblend. The second
material can
preferably also comprise a fabric of such a thermoplastic plastics material.
The mentioned thermoplastic plastics material have, by contrast to elastomers,
a sufficient
strength in order to withstand the stresses, which occur between the
individual ribs, in belt
transverse direction (due to shape and/or positional deviations), but also
shear stresses
due to different groove diameters or rib heights or a transverse running of
the belt. Insofar
as, for example, a groove diameter and/or a rib height is smaller than the
diameter or
height of an adjacent groove or rib then the circulation speed of this rib
correspondingly
reduces relative to the adjacent rib, which leads to a shear stress in the
carrier band
connecting these.
By contrast to an elastomeric carrier band as is known from US 3 996 813, a
thermoplastic
carrier band according to the present invention does not necessarily have to
be reinforced
with cords in belt transverse direction. Such a reinforcement is obviously
possible and
allows a corresponding thinner carrier band.
CA 02596699 2007-08-09
8
A further advantage of a thermoplastic carrier band resides in its good
sliding properties,
particularly its wear resistance and/or its low coefficient of friction. If,
for example, as is
frequently the case in lift installations the lift support means is deflected
singly or multiply
over fixed or floating deflecting wheels for reduction in tension forces in
block-and-tackle-
like manner, wherein it partly loops around the defiecting wheels by its belt
rear side
remote from the traction side, a thermoplastic carrier band advantageously
reduces the
friction occurring between the deflecting wheels and the belt. Advantageously
there are
thereby reduced, in particular, the friction force which has to be overcome
for lateral
guidance of the belt on a deflecting wheel, thus the lateral loading of the
belt, for example
by guide flanges of deflecting wheels, and as a consequence also the required
drive power
of the lift installation. At the same time the service life of the belt as
also that of the
deflecting wheels are extended. The wear resistance of the belt rear side is
improved at
the same time so that in turn the service life of the lift support means
increases.
Advantageously, the belt rear side of the thermoplastic carrier band can for
this purpose
have a coefficient of friction of at most 0.4, preferably at most 0.3 and
particularly
preferably at most 0.25.
In order to keep the loading of the carrier band as small as possible, the
ribs can be
arranged thereon at a spacing from one another which advantageously is
slightly greater
than the spacing of the associated ribs of the friction wheel. Insofar as no
positional or
shape deviations are present, the carrier band relieved of stress between the
ribs and can
correspondingly fold or arch due to its elasticity. In this state the tensile
force is
appropriately uniformly distributed to the individual belts which transmit
this by means of
their tensile carriers. Insofar as ribs move towards one another due to a
positional and/or
shape deviation of ribs and/or grooves, the carrier band arches or folds
correspondingly
more strongly without impairing operation of the lift installation. For this
purpose the
carrier band can advantageously have a bias in belt transverse direction,
which leads to a
concave arching of the carrier band away from the drive wheel. To the extent
that the ribs
move away from one another due to a positional and/or shape deviation of ribs
and/or
grooves initially the loose carrier band is drawn taut between the ribs so
that the carrier
band itself is still not elastically deformed. This advantageously reduces the
elastic
deformation of the carrier band and thus increases the service life thereof.
At the same
time, the carrier band allows, by virtue of its elasticity in transverse
direction, also
movement apart of the ribs beyond the setting in which the carrier band is
completely taut
and thus creates, with simultaneous minimisation of the deformation of the
carrier band
CA 02596699 2007-08-09
9
occurring in operation, a further area of compensation.
In order to guarantee the afore-described effects of the carrier band, this
has a thickness
of at most 0.5 millimetres or at most a tenth of the entire belt thickness.
A lift support means according to the invention is preferably produced in that
initially the
tensile carriers are arranged on the carrier band and subsequently the ribs
are mounted on
the carrier band, for example by means of an extrusion process, wherein a
groove
reaching substantially as far as the carrier band is formed between at least
two adjacent
ribs. In that case the tensile carriers are simultaneously incorporated in the
ribs. In an
advantageous embodiment the tensile carriers are for this purpose pressed
under bias
onto the carrier band so as to fix them correct in position during the
production process of
the belt.
Preferably the first material in that case contains an adhesive which
thermally glues the
ribs to the carrier band when being extruded on. In an alternative embodiment
initially the
individual ribs are extruded, wherein the tensile carriers are fed to them.
The ribs are
subsequently connected with the carrier band by thermal adhesion.
Further objects, features and advantages are evident from the subclaims and
the
examples of embodiment described in the following. With respect thereto:
Fig. 1 shows a section, which is parallel to a lift cage front, through a lift
installation according to an embodiment of the present invention; and
Fig. 2 shows a cross-section through a belt according to an embodiment of the
present invention.
Fig. I schematically shows a section through a lift installation, which is
installed in a lift
shaft 1, with the belt 12. The lift system comprises a drive unit 2, which is
fixed in a lift
shaft 1, with a drive wheel 4.1, a lift cage 3, which is guided at cage guide
rails 5, with
deflecting wheels, which are mounted below the cage floor 6, in the form of
cage support
rollers 4.2, a counterweight 8, which is guided at counterweight guide rails
7, with a further
deflecting wheel in the form of a counterweight support roller 4.3, and a lift
support means
in the form of a belt 12 for the cage 3 and the counterweight 8, which
transmits the drive
CA 02596699 2007-08-09
force from the drive wheel 4.1 of the drive unit 2 to the lift cage and the
counterweight.
The belt 12 is fastened at one of its ends below the drive wheel 4.1 at a
first belt fixing
point 10. From this it extends downwardly as far as the counterweight support
roller 4.3,
loops around this and extends from this to the drive wheel 4.1, loops around
this and runs
downwardly along the cage wall at the counterweight side, loops around in each
instance
by 900 respective cage support rollers 4.2 mounted on both sides of the lift
cage below the
lift cage 3 and runs upwardly along the cage wall, which is remote from the
counterweight
8, to a second belt fixing point 11.
The plane of the drive wheels 4.1 can be arranged at right angles to the cage
wall and the
counterweight side and its vertical projection can lie outside the vertical
projection of the lift
cage 3. It is therefore to be preferred that the drive wheel 4.1 has a small
diameter, so
that the spacing between the cage wall at the lefthand side and the wall of
the lift shaft I
opposite thereto can be as small as possible. Moreover, the small drive wheel
diameter
enables use of a gearless drive motor with relatively low drive torque as
drive unit 2.
Fig. 2 shows a cross-section through the belt 12. This comprises a carrier
band 15 of
polyamide, which is produced, for example, in an extrusion method. Tensile
carriers 14 of
multiply stranded steel wires are subsequently pressed under bias onto this
carrier band
and thus fixed in their positional arrangement relative to one another.
Individual ribs 13
of polyurethane are subsequently extruded onto the carrier band and in that
case
connected therewith, wherein the rib material extruded on partly encloses the
tensile
carriers 14 fully bearing against the carrier band 15.
Each rib 13 is separated from its adjacent ribs by a groove 16, which in the
example of
embodiment reaches up to the carrier band 15 so that each rib 13 is separately
fastened to
the carrier band 15. Two respective tensile carriers 14 are symmetrically
received in each
rib.
In the example of embodiment a rib 13 comprises a base section 13.2, which is
connected
with the carrier band 15 by being extruded on, with a substantially
rectangular cross-
section, the side flanks of which define the grooves 16. A contact section
13.1 with
trapezium-shaped cross-section is formed continuously with this base section
13.2 and is
provided for friction-locking engagement in a correspondingly shaped groove of
the drive
CA 02596699 2007-08-09
11
wheel 4.1.
The individual wedge ribs 13 are movable relative to one another under
deformation of the
carrier band 15 and can thus provide compensation for deviations of the ribs
and grooves
in position and shape. In particular, two adjacent wedge ribs can change their
spacing
from one another in both transverse direction and height direction of the belt
12 and thus
engage in grooves, which are formed with different spacings apart, different
depth and/or
different shape, in the drive wheel 4.1.
The drive wheel 4.1 and the counterweight support roller 4.3 are provided at
the periphery
thereof with grooves which are formed to be substantially complementary to the
contact
sections 13.1 of the belt 12. Where the belt 12 loops around one of the belt
wheels 4.1
and 4.3 the contact sections lie in corresponding grooves of the belt wheel,
whereby
excellent of guidance of the belt on these belt wheels is ensured. Moreover,
the traction
capability is improved by the wedge action arising between the grooves of the
drive wheel
4.1 and the ribs of the belt 12.
The cage support rollers 4.2 are so looped around by the belt 12 that the
unprofiled belt
backs, which are formed by the support band 15, are in contact with the cage
support
rollers. In order to ensure lateral guidance of the belt 12 on the cage
support rollers 4.2,
two guide rollers 4.4 provided with grooves are mounted at the cage base 6,
the grooves
of the rollers co-operating with the ribs of the belt 12.
