U.S. patent application number 11/568875 was filed with the patent office on 2007-09-27 for rope and belt for speed governor for elevators and associated sheaves.
Invention is credited to Inaki Aranburu Aguirre, Miguel Angel Madoz Michaus, Juan Manuel Pagalday Erana.
Application Number | 20070221452 11/568875 |
Document ID | / |
Family ID | 35320256 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070221452 |
Kind Code |
A1 |
Aguirre; Inaki Aranburu ; et
al. |
September 27, 2007 |
Rope and Belt for Speed Governor for Elevators and Associated
Sheaves
Abstract
The present invention relates to a rope and belt for a speed
governor for elevators and associated sheaves that is applicable to
speed governors for elevators. The rope comprises high-strength
steel wires clustered in strands among which a core is in turn
formed which is completely coated by a polymeric material which is
introduced in the gaps defined between the strands, obtaining an
outer polymeric surface with a diameter that is slightly greater
than the diameter of the core. The belts cluster at least two
metallic ropes comprising high-strength steel wires completely
coated with a polymeric material. The sheaves designed for the
ropes are semicircular or notched semicircular sheaves having a low
aggression and reduced diameter and high level of adherence,
determining a high coefficient of friction between the coated rope
and the sheave, and a high strength of the rope against fatigue due
to bending and wear is also obtained.
Inventors: |
Aguirre; Inaki Aranburu;
(Hernani, ES) ; Madoz Michaus; Miguel Angel;
(Hernani, ES) ; Pagalday Erana; Juan Manuel;
(Arrasate-Mondragon, ES) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
US
|
Family ID: |
35320256 |
Appl. No.: |
11/568875 |
Filed: |
July 12, 2004 |
PCT Filed: |
July 12, 2004 |
PCT NO: |
PCT/ES04/00331 |
371 Date: |
November 9, 2006 |
Current U.S.
Class: |
187/373 |
Current CPC
Class: |
D07B 2205/205 20130101;
B66B 7/06 20130101; D07B 2201/2055 20130101; D07B 1/16 20130101;
D07B 2801/24 20130101; D07B 2801/24 20130101; D07B 2201/2055
20130101; D07B 1/22 20130101; D07B 2201/2061 20130101; D07B
2201/2061 20130101; D07B 2801/14 20130101; D07B 2205/205 20130101;
D07B 2501/2007 20130101; B66B 5/04 20130101; D07B 2201/1008
20130101 |
Class at
Publication: |
187/373 |
International
Class: |
D07B 1/16 20060101
D07B001/16 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2004 |
ES |
P200401118 |
Claims
1. A rope for a speed governor for elevators, comprises
high-strength steel wires having a strength greater than 2000
N/mm.sup.2 clustered in strands among which a core is in turn
formed having a diameter less than or equal to 5 mm which is
completely coated by a polymeric material which is introduced in
the gaps defined between strands, obtaining an outer polymeric
surface with a diameter slightly greater than the diameter of the
core.
2. A rope for a speed governor according to claim 1, wherein the
diameter of the core is comprised between 2 and 4 mm.
3. A rope for a speed governor according to claim 1, wherein the
core incorporates a central strand of textile material.
4. A rope for a speed governor according to claim 1, wherein the
core incorporates a central strand of a composite material.
5. A belt for a speed governor, wherein at least two metallic ropes
comprising high-strength steel wires having a strength greater than
2000 N/mm.sup.2 clustered in strands forming corresponding metallic
cores having a diameter comprised between 0.01 mm and 2 mm and
which are completely coated by a polymeric material.
6. A belt for a speed governor according to claim 5, wherein the
outer polymeric material surface of the belt consists of a planar
surface.
7. A belt for a speed governor according to claim 5, wherein the
outer polymeric material surface of the belt consists of an
undulated surface.
8. A sheave for a speed governor for elevators used with the rope
according to claim 1, wherein a groove with a semicircular design
with a high level of adherence with BETA groove angle=0.degree. and
an ALPHA contact arc of the rope on the sheave comprised between 25
and 50.degree., as well as having a pitch diameter that is less
than or equal to 150 mm.
9. A sheave for a speed governor for elevators according to claim
8, wherein the groove has a notch in its semicircular design.
10. A sheave for a speed governor for elevators according to claim
8, wherein its pitch diameter is less than 100 mm.
11. A sheave for a speed governor for elevators used with the belt
according to claim 5, wherein its pitch diameter is less than or
equal to 100 mm.
12. An assembly formed by a rope and sheave for a speed governor,
wherein the sheave has a synthetic material coating layer in its
groove and has a pitch diameter less than or equal to 150 mm, and
in that the rope comprises high-strength steel wires with a
strength greater than 2000 N/mm.sup.2 clustered in strands among
which a core is in turn formed having a diameter less than or equal
to 5 mm.
13. A sheave for a speed governor for elevators used with the rope
according to claim 2, wherein a groove with a semicircular design
with a high level of adherence with BETA groove angle=0.degree. and
an ALPHA contact arc of the rope on the sheave comprised between 25
and 50.degree., as well as having a pitch diameter that is less
than or equal to 150 mm.
14. A sheave for a speed governor for elevators used with the rope
according to claim 3, wherein a groove with a semicircular design
with a high level of adherence with BETA groove angle=0.degree. and
an ALPHA contact arc of the rope on the sheave comprised between 25
and 50.degree., as well as having a pitch diameter that is less
than or equal to 150 mm.
15. A sheave for a speed governor for elevators used with the rope
according to claim 4, wherein a groove with a semicircular design
with a high level of adherence with BETA groove angle=0.degree. and
an ALPHA contact arc of the rope on the sheave comprised between 25
and 50.degree., as well as having a pitch diameter that is less
than or equal to 150 mm.
16. A sheave for a speed governor for elevators used with the belt
according to claim 6, wherein its pitch diameter is less than or
equal to 100 mm.
17. A sheave for a speed governor for elevators used with the belt
according to claim 7, wherein its pitch diameter is less than or
equal to 100 mm.
Description
OBJECT OF THE INVENTION
[0001] The present invention relates to a rope, a belt and their
associated sheaves which are applicable in a speed governor system
for lifting installations the function of which consists of
transmitting stress from the speed governor system to the
mechanical means in charge of stopping the elevator with its
passengers due to any type of uncontrolled movement.
[0002] It is an object of the invention that the rope or belt has a
high tensile strength so as to reduce the diameter of said rope
without compromising the operating reliability of the governor and
therefore of the installation, achieving that lighter, less
expensive and more manageable tension transmitting elements (ropes
or belts), and generally smaller, lighter and less expensive
governor systems, are used.
[0003] It is also object of the invention that the rope or belt has
a high fatigue strength under bending cycles such as those
occurring when it passes through the sheave or sheaves included in
the governor system so as to reduce the diameter of said sheaves
and thus reduce the space occupied by the governor, gaining space
occupied by the installation in the shaft and hence in the
building, reducing the weight of all the components as well as
achieving that the reliability of the systems is greater when the
sheave rotates at a higher speed.
[0004] Another object of the invention is that the rope or belt has
a coefficient of friction with the sheave of the governor which is
clearly greater than that of conventional systems so as to use
sheaves with less aggressive grooves maintaining the necessary
traction capacity in the sheave, thereby achieving that the rope or
belt is affected less by said sheave, increasing its useful life,
possibly becoming a maintenance-free system.
BACKGROUND OF THE INVENTION
[0005] Speed governor elements normally consist of a sheave joined
to a fixed shaft through which a rope passes, the ends of which are
joined to the element the safety of which is to be protected, and
further having a second sheave joined to a second point fixed in
the other end of the shaft, which is used to tense the connecting
rope. Therefore, the first of the described sheaves rotates at a
speed w given by: w=v/R
[0006] where v is the linear speed of the car or counterweight to
be controlled and R is the radius of the sheave of the overspeed
governor. The safety device is triggered when w exceeds a
pre-established value.
[0007] Reducing the radius R of the sheave makes the rotating speed
of the safety element higher, which makes the calibration thereof
easier given that the calibration of these elements with the usual
speeds and diameters, especially at low speeds, is complex,
specific speed governor elements for rated speeds of less than
v=0.5 m/s being common on the market.
[0008] Speed governors are currently assembled in two types of
design:
[0009] In a first type of design, which has traditionally been the
most used design, a speed governor system is located at a fixed
point of the installation. The governor system has a main sheave on
which the rope in charge of transmitting the actuation stress
circulates, and it may also have deflection sheaves. They also have
tension sheaves ensuring tension in the rope of the system. After
the rope passes through the entire sheave assembly, it is finally
fixed to the moving element the overspeed of which is to be
protected. This tension will at least be the minimum required so
that in the moment that the system is activated, the rope (usually
by friction in the groove of the governor system) is able to
transmit the necessary stress to the component in charge of
stopping the moving unit (usually a safety gear the activation of
which stops the moving unit and keeps it in the elevator guide
rails). The rope therefore forms a closed loop which starts and
ends in the moving unit such that the linear movement of the moving
unit causes the rotation of the sheaves of the governor system and
the deflection sheaves.
[0010] In other designs, such as those described in patents EP
1175367 B1 of Thyssenkrupp Elevator Manufacturing (France), WO
03070615 A1 of JUNG, Insook (Korea) and WO 03091142 A1 of
Mitsubishi Denki Kabushikikaisha (Japan), the governor is
integrally joined to the element to be controlled (moving unit) and
the rope is arranged in a single length with a weight at the lower
end which is the weight that will provide tension thereto. In this
case, the translation of the moving element also makes the speed
governor system rotate. This same governor system is able to
activate itself the safety gear element, i.e. by means of a
rotation and translation which would occur in the governor element
in the event of overspeed, translation and/or rotation movements
would occur in the governor system which would directly activate
the safety gear element.
[0011] This design allows obtaining a contact angle of the rope on
the sheave of values between 180 and 300.degree. increasing the
system traction capacity (T1/T2).
[0012] There are other devices using fixed elements such as, for
example, the guides of the installation described in U.S. Pat. No.
645,756 of James M. Draper et al.
[0013] To date, the traditional ropes used in speed governor
systems must have a minimum diameter d=6 mm which is determined by
regulatory considerations, and the ratio D/d must be greater than
or equal to 30, where D is the diameter of the sheave, which will
determine the minimum value D=180 mm, and accordingly the general
size of the device.
[0014] There are different applications in lifting for ropes such
as those described in the present invention which are described for
traction ropes in European patent EP 1273695, and even traction
elements with non-circular sections such as those described in WO
9942589, WO 9943885, WO 0037738 and WO 0114630.
[0015] The activation of the emergency braking elements (safety
gear) requires the governor to exert a minimum force on said
elements, which is 300 N or twice the force necessary to activate
the braking elements. This makes it necessary to use aggressive
grooves ensuring adherence in conventional systems, which is
achieved by cutting the grooves of the sheave of the governor
system with shapes, usually semi-cut with BETA groove angles
between 100.degree. and 105.degree., and V-shaped notched grooves
or V-shaped grooves without notches with GAMMA groove angles
between 35 and 40.degree., the latter requiring a surface hardening
process to reach hardnesses of about 50 HRC or higher. This process
is expensive since it requires specific materials due to its very
nature and due to the quality control required after it is applied.
The use of this type of grooves involves an inevitable wear of the
grooves of the sheaves in the governor systems and of the rope,
forcing the periodic replacement of those components, which is
expensive and if it is not carried out with precaution may cause
dangerous situations in the installation. Speed governor systems
are subject to CE Certification and Marking, which complicates
administrative work in the competent notified agencies in the event
that they are replaced.
[0016] On the other hand, the use of large sheaves makes governors
rotate at relatively low speeds, which translates into a slow
movement of the elements which are to be activated and low kinetic
energies, which makes calibrating them difficult especially in
centrifugal-type governors.
DESCRIPTION OF THE INVENTION
[0017] The present invention relates to a high-strength steel wire
rope or belt coated with a polymeric material, for example
polyurethane, applicable for speed governors detecting the
overspeed in lifting installations and transmitting the necessary
stress to activate the emergency braking means associated to said
lifting installations.
[0018] The use of high-strength ropes in speed governors allows
reducing the diameter of the rope maintaining a high safety level.
A conventional system incorporates a rope with diameter d=6 mm or
greater, while the metallic rope object of the present invention
has a lower outer diameter of 5 mm and is formed by wires with a
strength greater than 2000 N/mm.sup.2.
[0019] The wires can be in turn clustered into strands which are
clustered around a central strand consisting of wires or of a
high-strength textile or synthetic material such as Kevlar.
[0020] There can be multiple designs of the rope, some of which
show greater flexibility than others, and some making better use of
the cross section than others, but in any case the present
invention can be carried out with any of them.
[0021] In the case of belts, the present invention contemplates
them having at least two metallic ropes comprising high-strength
steel wires with strength greater than 2000 N/mm.sup.2 clustered
into strands forming a metallic core having a diameter comprised
between 0.01 and 2 mm and which are completely coated by a
polymeric material. It has been provided that the outer surface of
polymeric material of the belt can have a planar surface or an
undulated surface.
[0022] By means of the use of a rope or belt such as those
described above, the sheave of the safety system can have a reduced
diameter. The reduction of the diameter of the sheave of the safety
system makes the entire system smaller, occupying less space in the
shaft and also in the building. The size reduction further makes
all the elements be lighter and less expensive. A traditional
system with a metallic rope having a rated diameter of d=6 mm has a
pitch diameter of the sheave D=180 mm or greater. The present
invention operates correctly with acceptable safety levels or
safety levels exceeding said traditional systems with sheave pitch
diameters that are less than or equal to 150 mm in the case of rope
with a circular section and pitch diameters of less than 100 mm in
the case of belts of any type.
[0023] On the other hand, high-strength steel ropes allow a smaller
D/d ratio than usual, also maintaining an acceptable safety level,
further contributing to the reduction of the sheave pitch diameter
D. In the current state of the art, it can be seen that the sheave
diameter is subject to a minimum D/d=30 ratio. The present
invention makes an assembly formed by rope (or belt) and sheave
work with the rope (or belt) provided with polymeric material
coating. As a result of the polymeric coating, the coefficient of
friction between the materials of the rope (or belt) and sheave is
much greater than in traditional systems, being able to use planar
surfaces for the belts and sheaves with semicircular grooves for a
circular rope, obtaining internal pressures in the rope which are
clearly less than those of a traditional system. This allows
reducing the D/d parameter to values less than 30, obtaining safety
levels which are equal to or greater than conventional systems with
ratios between 20 and 30.
[0024] Furthermore, using this type of ropes or belts the
lubrication remains inside and is not dispersed by the installation
with time and in the course of the cycles of the rope on the
sheave, contributing to better lubricating the inner wires and
strands, increasing fatigue strength of the rope+governor system.
The polymeric coating prevents the outer metallic strands from
rubbing against the groove of the sheave, preventing any abrasion
and wear of the outer wires as a result of the intermediate layer
of elastic material, increasing the life of the rope and sheave to
levels which imply a maintenance-free system in practice.
[0025] In the present invention, the use of circular rope implies
the use of a sheave with a planar, convex or concave surface. The
mentioned circular rope can be used with different groove
geometries, but the fact that it is a rope coated with a polymeric
material provides it with a high coefficient of friction with the
groove of the sheave of the speed governor element to which it is
associated, which means that grooves which are rather
non-aggressive with the rope can be used, such as semicircular or
perforated semicircular grooves. The use of this type of grooves
prolongs the life of the rope given that the pressure between rope
and sheave is more uniformly distributed than with other
geometries, and pressure concentration areas which can damage the
cable after a low number of cycles are not produced. This greatly
increases the expected life of the rope and allows reducing or even
eliminating the cost of maintenance activities.
[0026] This is the opposite of conventional governor systems which
have in their sheave semi-notched or V-shaped grooves similar to
those used in the grooves of traction sheaves, and therefore they
will experience wear, inspection and maintenance tasks being
required to ensure the traction capacity of the governor system,
and hence its replacement due to excessive wear levels. As a result
of the design and materials used, the present governor system
prevents any possible wear of the groove of the sheave of the
governor system, ensuring a much greater useful life than
conventional systems and reducing maintenance tasks to a minimum,
even possibly being maintenance free.
[0027] The sheaves of the governor element used for a rope may be
of a metallic or non-metallic material with a semicircular or
notched semicircular design with a BETA groove angle=0.degree. and
a contact arc of the rope on the sheave ALPHA=25-50.degree.. In the
case of the belt, the sheaves can have a planar, concave or convex
surface.
[0028] Therefore, the diameter of the metallic core of the rope is
acceptable at values of less than or equal to 5 mm, preferably
between d=2 and 4 mm and the pitch diameter of the sheave of the
governor element is acceptable at values less than or equal to 150
mm, preferably between D=75 and D=100 mm.
[0029] For the case of planar belts, they have at least two inner
metallic ropes with a diameter comprised between d=0.01 and 2 mm,
and a pitch diameter of the sheave less than or equal to 100
mm.
[0030] In a possible alternative embodiment, it is contemplated
that the sheave can be made of a metallic material and can have in
its groove a synthetic material coating, and that the metallic rope
has no coating.
DESCRIPTION OF THE DRAWINGS
[0031] To complement the description being made and for the purpose
of aiding to better understand the features of the invention
according to a preferred practical embodiment thereof, a set of
drawings is attached as an integral part of said description in
which the following is shown with an illustrative and non-limiting
character:
[0032] FIG. 1 shows a section of one type of rope.
[0033] FIG. 2 shows another possible rope section in which the
central strand has been replaced with a central strand of a textile
material or of a high-strength material, such as Kevlar or the
like.
[0034] FIG. 3 shows the rope shown in FIG. 1 as it passes through
two sheaves with different types of grooves, in this case
semicircular or notched semicircular grooves.
[0035] FIGS. 4a to 4c show different possible rope designs.
[0036] FIGS. 4d to 4e show different possible belt designs.
[0037] FIG. 5 shows possible speed governor system designs in which
the rope loop starts and ends in the safety gear element located in
the body of the moving unit, although other designs are possible
without the main features of the system being affected. The speed
governor element is in a fixed point of the installation.
[0038] FIG. 6 shows possible overspeed governor system designs in
which the rope loop starts and ends in the safety gear element
located in the body of the moving unit, although other designs are
possible without the main features of the system being affected. In
this case the governor element moves integrally with the moving
unit.
[0039] FIG. 7 shows possible rope tensing element designs, although
other designs are possible without the main features of the system
being affected.
[0040] FIG. 8 shows a speed governor system in which the speed
governor element moves integrally with the moving unit, but unlike
the previously mentioned systems, the stress is transmitted to the
safety gear element directly by the governor element. The rope in
this case has the function of rotating the sheave of the governor
element so as to thus detect the linear speed at which the elevator
is moving, to generate the signal due to an overspeed event and to
provide the necessary force to the governor element to activate the
safety gear element.
[0041] FIG. 9 shows the scheme of forces acting in the moment the
governor system is actuated.
[0042] FIG. 10 shows another possibility of the second type of
governor system.
PREFERRED EMBODIMENT OF THE INVENTION
[0043] FIG. 1 shows a metallic wire rope coated with a polymeric
material layer. The rope comprises an assembly of metallic wires
(1), usually made of steel, clustered according to geometric
designs having certain sections which are subsequently rotated to
form a helix, forming a strand (3). The wires (1) forming a strand
(3) can be identical, as shown in FIG. 1, or different. It is
common for the wires to be concentrically clustered, forming
layers.
[0044] The different strands (3) are in turn clustered following a
clustering scheme parallel to the one described in the previous
paragraph, i.e. being arranged in a certain fashion in a section
and subsequently rotating to form a helix of strands in the same
fashion that a strand is formed by means of a helix of wires.
[0045] FIG. 1 shows the strands of wires distributed around a
central strand of wires, whereas in FIG. 2 the central metallic
strand has been replaced with a central strand (4) of a textile
material or of a high-strength synthetic material such as Kevlar or
the like.
[0046] The metallic core of the rope formed by the cluster of
strands (3) is surrounded by a polymeric material coating (2), for
example polyurethane, having a circular outer section with a
diameter close to but somewhat greater than the larger diameter of
the metallic core, and therefore completely coating it without
significantly increasing the diameter of the core.
[0047] FIG. 3 represents the rope shown in FIG. 1 as it passes
through the grooves (5, 5') of different metallic sheaves (2, 2')
belonging to an speed governor of the type used in lifting
apparatuses. These sheaves can have different groove (5, 5')
geometries, although given the features of the rope object of the
invention, the use of grooves that are not aggressive, such as
semicircular grooves (5) or notched semicircular grooves (5'), is
preferred.
[0048] In FIG. 4c, a design can be seen in which the diameter of
the central strand of the metallic part of the rope has a diameter
greater than the outer strands. This ensures that the polymeric
material enters the spaces generated between the outer strands,
increasing system integrity and the physical union between the
metallic part and the polymeric material of the coating.
[0049] A comparison of the typical parameters relating to
rope-sheave assemblies used in conventional speed governors with
those corresponding to rope-sheave assemblies object of the present
invention shall be carried out below.
[0050] The grooves normally used in the conventional speed governor
element are notched semicircular grooves with BETA groove angles
between 100.degree. and 105.degree., V-shaped grooves with or
without surface hardening treatment with a GAMMA groove angle
between 35 and 40.degree..
[0051] In a conventional system with a sheave having a semi-notched
groove with BETA groove angle=105.degree. and a pitch diameter of
200 mm, a specific pressure in the cable is provided having a value
between 3.5 and 7 N/mm.sup.2, depending on the tension coming from
the tension sheave. Coefficient of friction "f" values between 0.4
and 0.5 are achieved with this design (considering a coefficient of
friction between the rope and cast groove of .mu.=0.2), achieving a
traction capacity of T1/T2 of values between 3.5 and 4.
[0052] In a conventional system with a sheave having a non-hardened
V-shaped groove of 40.degree. and BETA notch angle=105.degree. and
pitch diameter of 200 mm, a specific pressure is provoked in the
rope having a value between 4 and 8.5 N/mm.sup.2 depending on the
tension coming from the tension sheave and the wear of the groove
of the sheave. Coefficient of friction "f" values between 0.5 and
0.6 are achieved with this design (considering a coefficient of
friction between the rope and the cast groove of .mu.=0.2),
achieving a traction capacity of T1/T2 having values between 6 and
6.5.
[0053] In a conventional system with a hardened V-shaped groove
with a GAMMA angle=40.degree. and a pitch diameter of 200 mm, a
specific pressure is provoked in the rope having a value between
3.5 and 6.5 N/mm.sup.2 depending on the tension coming from the
tension sheave. Coefficient of friction "f" values between 0.5 and
0.6 are achieved with this design (considering a coefficient of
friction between the rope and the cast groove of .mu.=0.2)
achieving a traction capacity of T1/T2 with values between 6 and
6.5.
[0054] By using planar belts with metallic ropes inside them, the
present invention has specific pressures on said inner ropes having
a value between 3 to 5 times less under the same use conditions as
the previously described practical cases so as to obtain a traction
capacity similar to that obtained in said examples. The belt shall
preferably have at least two internal metallic ropes having a
diameter with values between d=0.01 and 2 mm, and the sheave of the
governor element would have a smooth, concave or convex surface
having a pitch diameter with values less than or equal to 100
mm
[0055] By using metallic ropes with wires having a strength greater
than 2000 N/mm.sup.2, and coated with a polymeric material, such as
polyurethane for example, the present invention has a coefficient
of friction greater than the traditional systems reaching values
greater than .mu.=0.4. Experimental tests have given results
greater than .mu.=0.5. This provides the system with a traction
capacity T1/T2 having a value greater than 8, being possible to
reduce the tension on the cable and therefore reduce the specific
pressure on the rope, increasing the useful life of the rope.
[0056] A governor mechanism according to this invention having a
sheave of a cast material with a semicircular groove with an ALPHA
winding angle of the ropes on the sheave=30.degree. and a pitch
diameter of the sheave of 200 mm provokes a specific pressure in
the metallic part of a rope with diameter d=2 mm of a value between
1.2 and 1.5 N/mm.sup.2 depending on the tension coming from the
tension sheave, which in this case would be less than that normally
used in conventional systems, this value being clearly less than
those reached in conventional systems, and this together with the
benefits of being a coated rope would ensure a virtually
maintenance-free useful life of the governor system.
[0057] A governor mechanism according to this invention having a
sheave of a cast material with a semicircular groove with ALPHA
angle=30.degree. and a pitch diameter of 80 mm provokes a specific
pressure in the metallic part of a rope with d=2 mm, of a value
between 3 and 4 N/mm.sup.2 depending on the tension coming from the
tension sheave, which in this case would be less than that normally
used in conventional systems. This value is similar to or less than
those obtained in traditional systems, and this together with the
benefits of being a coated rope would ensure a useful life of the
system which is similar to or greater than a conventional governor
system.
[0058] A governor system with a design such as the one shown in
FIG. 6, in which the governor system moves with the moving assembly
but the rope is stationary with a fixed fixing point in its upper
part and a weight in its lower part with a semicircular groove with
ALPHA angle=30.degree. of a cast material and a pitch diameter of
80 mm, provokes a specific pressure in the metallic part of a rope
with d=2 mm, having a value between 1 and 3 N/mm.sup.2 depending on
the tension coming from the tension sheave, which in this case
would be less than that normally used in conventional systems and
even less than the previously described designs. This value less
than those obtained in traditional systems together with the
benefits of being a coated rope would ensure a useful life of the
system exceeding a conventional governor system.
[0059] FIGS. 5 and 6 show a metallic rope of a governor system
formed by wires with a strength greater than 2000 N/mm.sup.2 and
the outer diameter of which is less than or equal to 5 mm and is
not coated with any material. This rope passes through the groove
of the sheave of the governor element which is metallic with a
coating of a synthetic material, such as polyurethane or resins for
example, with a design increasing the coefficient of friction
between rope and sheave.
[0060] As can be seen in FIG. 9, the present invention requires a
tension in the rope that is less than conventional systems normally
requiring a tension between G=50 kg and 100 kg for designs such as
those represented in FIG. 5 and between G=25 kg and 50 kg for
designs such as those represented in FIG. 6.
[0061] In FIG. 9, the following is obtained for the loop design
type: F1+GR+G/2-T2=0
[0062] When considering experimental data indicating T1/T2=8, a
tension in the rope with values between 10 and 12 kg is required,
depending on the path of the installation. The weight of a rope or
belt object of the present invention is less than that of
conventional ropes and has values between 0.04 and 0.1 kg/m. This
reduces the effects of inertia for moving the mass of the rope in
the acceleration and deceleration of the elevator.
[0063] In FIG. 9, the following is obtained for the design type in
which there is only one rope length: F1+GR+G-T2=0
[0064] When considering experimental data indicating T1/T2=10
(greater than the previous case due to the fact that it is possible
to increase the contact angle of the rope on the sheave of the
governor element), a tension in the rope with values between 5 and
8 kg is required depending on the path of the installation. This
tension is clearly less than conventional systems contributing to
the fact that the effects of inertia are minimized and decreasing
the specific pressure on the cable when it passes through the
sheaves. Therefore, the present invention implies a virtually
maintenance-free system in practice.
[0065] The use of high-strength steel in the ropes also contributes
to prolonging the life thereof, given that their mechanical fatigue
performance and wear improve, contributing to the previously
described effect.
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