HK1085988B - Elevator without a counterweight having an elevator car - Google Patents

Description

Elevator without counterweight and with elevator car

Technical Field

The invention relates to an elevator, a method of constructing an elevator without counterweight, and the use of the invention.

Background

One of the projects in elevator development work is to achieve efficient and economical utilization of building space. In recent years, this development work has produced, among other things, a number of elevator solutions without machine room. Good examples of elevators without machine room are disclosed in technical specifications EP0631967(a1) and EP 0631968. The elevators described in these specifications are fairly effective in respect of space utilization as they have made it possible to eliminate the space required in the building by the elevator machine room without enlarging the elevator shaft, and in the elevators disclosed in these specifications the machine is compact at least in one direction but may have considerably larger dimensions than a conventional elevator machine in other directions.

In these substantially good elevator solutions, the space required by the hoisting machine limits the freedom of choice in elevator lay-out solutions. The various arrangements required for the passage of the hoisting ropes are space-demanding. It is difficult to reduce the space required by the elevator car itself on its track and likewise the space required by the counterweight, at least at a reasonable cost and without impairing elevator performance and operational quality. In a traction sheave elevator without machine room it is often difficult to mount the hoisting machine in the elevator shaft, especially in solutions with machine above, because the hoisting machine is a large object of considerable weight. Especially in the case of larger loads, speeds and/or hoisting heights, the size and weight of the machine are a problem regarding installation, which is so great that the required machine size and weight have in practice limited the sphere of application of the concept of elevator without machine room or at least retarded the introduction of said concept in larger elevators. When modernizing elevators, the space available in the elevator shaft often limits the scope of application of the concept of elevator without machine room. In many cases, especially when modernizing or replacing hydraulic elevators, it is not practical to apply the concept of roped elevator without machine room due to insufficient space in the shaft, especially in cases where the hydraulic elevator solution to be modernized/replaced has no counterweight. One disadvantage of elevators provided with a counterweight is the cost of the counterweight and the space it requires in the shaft. Drum elevators, which are nowadays rarely used, have the drawback that they require heavy and complex hoisting machines with high energy consumption. Various prior-art elevator solutions without counterweight are exotic and no suitable solution is known. Previously, it has not been technically and economically reasonable to make elevators without counterweight. A solution of this type is disclosed in the technical specification WO 9806655. A recent solution without counterweight provides a viable solution. In prior-art solutions without counterweight, a weight or spring is used to implement the tensioning of the hoisting rope, which is not an attractive way of implementing the tensioning of the hoisting rope. Another problem of elevator solutions without counterweight, when e.g. a large hoisting height or a large rope length is required due to a large suspension ratio, is the compensation of the rope elongation and the fact that the friction between the traction sheave and the hoisting ropes is insufficient to run the elevator due to rope elongation.

Disclosure of Invention

The object of the invention is to achieve at least one of the following objectives. On the one hand it is an object of the invention to develop the elevator without machine room further so that it is possible to utilize the space in the building and elevator shaft more efficiently than before. This means that the elevator should allow to be installed in a fairly narrow elevator shaft if necessary. One objective is to achieve an elevator in which the hoisting ropes have a good grip/contact on the traction sheave. Another object of the invention is to achieve an elevator solution without counterweight that does not necessarily impair the characteristics of the elevator. Another object is to eliminate rope elongations.

The object of the invention should be achieved without losing the possibility of changing the basic layout of the elevator.

To achieve the above object, according to one aspect of the invention, an elevator without counterweight is provided with an elevator car, which is suspended by means of hoisting ropes consisting of a single rope or several parallel ropes, said elevator having a traction sheave which moves the elevator car by means of the hoisting ropes, characterized in that the hoisting ropes have rope portions going upwards and downwards from the elevator car, and the rope portions going upwards from the elevator car are under a first rope tension which is greater than a second rope tension being the rope tension of the rope portions going downwards from the elevator car, and that the elevator comprises a compensating system for keeping the ratio between the first rope tension and the second rope tension substantially constant, said elevator car being connected to the hoisting ropes by means of at least one diverting pulley over which the hoisting ropes go upwards from both sides of its rim and at least one diverting pulley over which the hoisting ropes go downwards from both sides of its rim, and the suspension ratio of the upper rope portion and the lower rope portion is at least 2:1, winding the rope.

Preferably, the compensating system is a lever, a set of tensioning sheaves or a set of compensating sheaves.

Preferably the compensating system comprises one and/or more diverting pulleys.

Preferably the continuous contact angle between the traction sheave and the hoisting ropes is at least 180.

Preferably the roping used between the traction sheave and the rope pulleys used as diverting pulleys is ESW roping or DW roping or XW roping. Preferably, the hoisting ropes used are of a strength of more than 2000N/mm²Hoisting ropes of rope wires.

Preferably the hoisting ropes have a diameter smaller than 8 mm.

Preferably the diameter of the hoisting ropes is between 3 and 5 mm.

Preferably, the hoisting machine has a weight much smaller than the load.

Preferably the traction sheave is coated with polyurethane or rubber.

The traction sheave is preferably made of metal at least in the area of the rope grooves, while the rope grooves are preferably undercut. Preferably, the metal is cast iron.

Preferably the D/D ratio of the diverting pulleys below the elevator car is below 40.

According to another aspect of the invention a method is provided for constructing an elevator without counterweight, characterized in that the elevator car is connected to elevator ropes for hoisting the elevator car, said ropes consisting of a single rope or a plurality of parallel ropes and comprising rope portions going upwards and downwards from the elevator car, and that the elevator ropes are provided with a compensating system for maintaining a substantially constant ratio between the rope forces acting in the upwards and downwards direction.

According to a further aspect of the invention there is provided the use of a compensating system for maintaining a constant ratio between the rope forces acting on the elevator car in upward and downward directions in an elevator without counterweight.

Some embodiments of the invention are also discussed in the descriptive section of the present application. The inventive content of the application may also consist of several separate inventions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims may be superfluous from the point of view of separate inventive concepts.

With the present invention, one or more of the following advantages are obtained, among others:

a very light elevator and/or elevator machine is obtained by using a small traction sheave;

good traction sheave grip is obtained especially by using double wrap roping and the lightweight components make the weight of the elevator car considerably reduced;

the compact machine size and thin substantially circular ropes allow the elevator machine to be relatively freely placed in the shaft. The elevator solution of the invention can thus be implemented in a fairly wide variety of ways in the case of both elevators with machine above and elevator with machine below;

the elevator machine can advantageously be placed between the elevator car and a wall;

all or at least part of the weight of the elevator car can be taken up by the elevator guide rails;

the application of the invention makes it possible to utilize the cross-sectional area of the elevator shaft effectively;

the light and thin rope is easy to carry, load and unload, so that the installation is simple and quick;

in elevators with a nominal load below 1000kg, for example, the thin and strong steel wire ropes preferably used in the invention have a diameter of the order of magnitude of only 3-5mm, although even thin and thick ropes may be used;

in the case of ropes of about 6mm or 8mm in diameter, a fairly large and fast elevator according to the invention can be achieved;

either coated or uncoated ropes may be used;

the use of a smaller traction sheave makes it possible to use a smaller elevator drive motor, which means a reduction in the drive motor acquisition/manufacturing costs;

the invention can be used in gearless and geared elevator motor solutions;

although the invention is primarily intended for use in elevators without machine room, it can also be used in elevators with machine room;

in the invention, a better grip and better contact between the hoisting ropes and the traction sheave are achieved by increasing the contact angle between them;

as the gripping force is improved, the size and weight of the elevator car can be reduced;

the space saving potential of the elevator of the invention increases as the space required by the counterweight can be at least partly reduced;

energy and thus cost savings are achieved because the elevator system is lighter and smaller.

The machine can be chosen relatively freely when placed in the shaft, since the space required for the counterweight and the counterweight guide rails can be used for other various purposes;

by installing at least the elevator hoisting machine, the traction sheave and a rope sheave functioning as a diverting pulley in a complete unit fitted as part of the elevator of the invention, there will be great savings in installation time and costs;

in the elevator solution of the invention, it is possible to arrange all the ropes in the shaft on the side of the elevator car; for example, in the case of some rucksack solutions, the ropes can be arranged to run behind the elevator car in the space between the elevator car and the rear wall of the elevator shaft;

the invention also makes it easy to implement a platform elevator solution;

since the elevator solution of the invention does not necessarily comprise a counterweight, it is possible to implement elevator solutions in which FC has elevator doors on several, in the extreme case even on all, walls of the elevator car. In this case the guide rails of the elevator car are disposed at the corners of the elevator car.

The elevator solution of the invention can be implemented with several different machine solutions;

the suspension of the elevator car can be implemented with almost any suitable suspension ratio;

compensating rope elongations by means of a compensating system according to the invention is an inexpensive and simple to implement device;

compensating rope elongations by means of a lever is an inexpensive and lightweight device;

with the rope elongation compensating solutions of the invention it is possible to obtain a force T acting on the traction sheave₁/T₂Constant ratio therebetween;

force T acting on traction sheave₁/T₂The ratio therebetween is independent of the load;

by using the rope elongation compensation solutions of the invention, unnecessary stress on the machine and the rope can be avoided;

by using the rope elongation compensation solutions of the invention, the force T₁/T₂The relationship between them can be optimized to obtain a desired value;

the various solutions of the invention for rope elongation compensation are safe solutions making it possible to ensure the friction/contact required between the traction sheave and the hoisting ropes in all situations;

furthermore, the rope elongation compensating solutions of the invention make it unnecessary to rely on more than necessary loads for tensioning the hoisting ropes in order to ensure friction between the traction sheave and the hoisting ropes, and consequently the service life of the hoisting ropes is increased and their vulnerability to damage is reduced.

When rope elongations are compensated using the arrangement according to the invention for compensating rope elongations with compensating sheaves of different diameters, it will be possible to compensate even large rope elongations using this solution depending on the diameters of the sheaves used;

by using a rope elongation compensating solution according to the invention, in which the compensating device used is a differential gear, even large rope elongations can be compensated, especially in the case of large hoisting heights.

The main area of application of the invention is elevators designed for transporting people and/or freight. A typical range of application of the invention is in elevators with a speed in the lower range of about 1.0m/s or below, but it may also be higher. For example, it is easy to implement an elevator according to the invention with a travel speed of 0.6 m/s.

In both passenger and freight elevators, many of the advantages achieved by the present finding are clearly shown even in elevators for only 2-4 persons and already clearly for 6-8 persons (500-.

In the elevator of the invention, the usual elevator hoisting ropes, such as the commonly used steel wire ropes, are available, in which elevator ropes made of artificial material and ropes in which the load-bearing part is made of artificial fibres, such as e.g. so-called "ropes", have recently been proposed for use in elevators. Some solutions available also include steel-reinforced flat ropes, especially because they allow for a small bending radius. Particularly well applicable in the elevator of the invention are elevator hoisting ropes twisted e.g. from round and strong wires. With round wires the rope can be twisted using wires of different or equal thickness. In ropes well suited to be used in the invention, the wire thickness is on average below 0.4 mm. Well applicable ropes made of strong wires are those in which the average wire thickness is below 0.3mm or even below 0.2 mm. For example, thin-wire and strong 4mm ropes can be twisted relatively economically from the steel wires so that the average wire thickness in the finished rope is in the range of 0.15-0.25 mm, while the thinnest wire may have a thickness as small as only about 0.1 mm. In the present invention, a strength of more than 2000N/mm can be used²The rope wires of (1). The proper range of the strength of the steel wire of the rope is 2300-². In principle, it is possible to use a material having a strength of up to about 3000N/mm²Or even higher rope wires.

The elevator of the invention, in which the elevator car is suspended by means of hoisting ropes consisting of a single rope or several parallel ropes and which elevator has a traction sheave which can move the elevator car by means of the hoisting ropes, has hoisting ropes going upwards and downwards from the elevator carSegment, while rope segments going upwards from the elevator car are at a first rope tension (T)₁) Is greater than the second rope tension (T)₂) Which is the rope tension of the rope portions going downwards from the elevator car. In addition, the elevator comprises a compensating system for maintaining the ratio (T) between the first rope tension and the second rope tension₁/T₂) Is substantially unchanged.

In the method according to the invention for manufacturing an elevator, the elevator car is connected to elevator ropes hoisting the elevator car, said ropes consisting of a single rope or a number of parallel ropes and comprising rope portions going upwards or downwards from the elevator car, and the elevator ropes are provided with a compensating system for maintaining the ratio (T) between the rope tensions acting in the upwards and downwards direction₁/T₂) Is substantially unchanged.

The grip between the traction sheave and the hoisting ropes can be strengthened by increasing the contact angle with the rope sheave functioning as a diverting pulley. In this way the elevator car can be made lighter and its size can be reduced, thus increasing the space saving potential of the elevator. A contact angle of more than 180 between the traction sheave and the hoisting ropes can be achieved by using one or more diverting pulleys. Due to the friction requirements a need arises to compensate rope elongations to ensure that there is a sufficient grip between the hoisting ropes and the traction sheave for the operation and safety of the elevator. On the other hand it is of crucial importance in respect of elevator operation and safety that in an elevator solution without counterweight the rope portion below the elevator car should be kept sufficiently tight. This cannot necessarily be achieved by a spring or a simple lever.

Drawings

In the following, the invention will be described in detail with the aid of examples of embodiments thereof with reference to the accompanying drawings.

Fig. 1 presents a diagrammatic view of a traction sheave elevator without counterweight according to the invention;

fig. 2 presents a diagrammatic view of another traction sheave elevator without counterweight according to the invention;

fig. 3 presents a diagrammatic view of a third traction sheave elevator without counterweight according to the invention;

fig. 4 presents a diagrammatic view of a fourth traction sheave elevator without counterweight according to the invention;

fig. 5 presents a diagrammatic view of another traction sheave elevator without counterweight according to the invention;

fig. 6 presents a diagrammatic view of another traction sheave elevator without counterweight according to the invention;

fig. 7 presents a diagrammatic view of another traction sheave elevator without counterweight according to the invention;

fig. 8 presents a diagrammatic view of another traction sheave elevator without counterweight according to the invention;

fig. 9 presents a diagrammatic view of another traction sheave elevator without counterweight according to the invention.

Detailed Description

Fig. 1 presents a diagrammatic illustration of the structure of an elevator according to the invention. The elevator is preferably an elevator without machine room with a drive machine 4 placed in the elevator shaft. The elevator presented in the figure is a traction sheave elevator without counterweight and with machine above. The passage of the elevator hoisting ropes 3 is as follows: one end of the rope is immovably fixed to a fixing point 16 on a lever 15 fastened to the elevator car 1, said fixing point being located at a distance from a pivot 17 connecting the lever to the elevator car 1. In fig. 1 the lever 15 is thus hinged to the elevator car 1 at a fixing point 17. From the fixing point 16 the hoisting ropes 3 go upwards to a diverting pulley 14 placed in the upper part of the elevator shaft above the elevator car 1, from which diverting pulley the ropes go further downwards to a diverting pulley 13 on the elevator car, and from which diverting pulley 13 the ropes go further upwards to a diverting pulley 12 fitted in the upper part of the elevator shaft above the elevator car. From diverting pulley 12 the ropes go further downwards to a diverting pulley 11 mounted on the elevator car. Having passed around this pulley the ropes go further upwards to a diverting pulley 10 fitted in the upper part of the elevator shaft, and having passed around this pulley the ropes go further downwards to a diverting pulley 9 fitted on the elevator car. After passing around this diverting pulley 9 the hoisting ropes 3 go further upwards to the traction sheave 5 of the drive machine 4 placed in the upper part of the elevator shaft, and before passing over a diverting pulley 7 that is only in "tangential" contact with the ropes. This means that the ropes 3 going from the traction sheave 5 to the elevator car 1 pass via the rope grooves of diverting pulley 7, and the deflection of the ropes 3 caused by the diverting pulley 7 is small. It can be said that the ropes 3 coming from the traction sheave 5 touch the diverting pulley 7 only tangentially. This tangential contact serves as a solution to damp the vibrations of the outgoing ropes and it can be used in other roping solutions. The ropes are passed around the traction sheave 5 of the hoisting machine 4 along the rope grooves of the traction sheave 5. From the traction sheave 5 the ropes 3 go further downwards to diverting pulley 7, passing around it along the rope grooves of diverting pulley 7 and returning upwards to the traction sheave 5, the ropes passing around the traction sheave 5 along the rope grooves of the traction sheave 5. From the traction sheave 5 the hoisting ropes 3 go further downwards in tangential contact with diverting pulley 7 over the elevator car 1 moving along the guide rails 2 to a diverting pulley 8 placed in the lower part of the elevator shaft passing around it along the rope grooves above it. From diverting pulley 8 in the lower part of the elevator shaft the ropes 3 go upwards to diverting pulley 18 on the elevator car and thence to diverting pulley 19 in the lower part of the elevator shaft and back up to diverting pulley 20 on the elevator car, from which the ropes 3 go further downwards to diverting pulley 21 in the lower part of the elevator shaft and thence to diverting pulley 22 on the elevator car, from which the ropes 3 go further to diverting pulley 23 in the lower part of the elevator shaft. From diverting pulley 23 the ropes 3 go further to a lever 15 pivotally fixed to the elevator car 1 at point 17, to which lever 15 one end of the ropes 3 is immovably fastened at a point 24 at a distance b from the pivot 17. In the case presented in fig. 1, the hoisting machine and the diverting pulleys are preferably all placed on the same side of the elevator car. This solution is particularly advantageous in the case of a rucksack elevator, in which case the aforementioned components are arranged behind the elevator car in the space between the rear wall of the elevator car and the rear wall of the elevator shaft. The hoisting machine and the diverting pulleys can also be disposed in the elevator shaft in some other suitable manner. The roping arrangement between the traction sheave 5 and the diverting pulley 7 is called double wrap roping, in which the hoisting ropes are passed around the traction sheave two and/or more times. In this way, the contact angle can be increased by two and/or more stages. For instance in the embodiment presented in fig. 1, a contact angle of 180 +180, i.e. 360, between the traction sheave 5 and the hoisting ropes 3 is achieved. The double wrap roping presented in the figure can also be arranged in another way, e.g. by placing the diverting pulley 7 at the side of the traction sheave 5, in which case a contact angle of 180 + 90-270 is obtained as the hoisting ropes pass twice around the traction sheave; or by placing the traction sheave in some other suitable position. A preferred solution is to arrange the traction sheave 5 and the diverting pulley in such a way that the diverting pulley 7 will also function as a guide for the hoisting ropes 3 as well as a damping pulley. Another advantageous solution is to build an integrated unit comprising both the elevator drive machine with the traction sheave and one or more diverting pulleys with bearings at the correct operating angle in relation to the traction sheave. The working angle is determined by the roping used between the traction sheave and the diverting pulley/diverting pulleys, which defines the arrangement in the unit of the mutual positions and angles between the traction sheave and the diverting pulley/diverting pulleys in relation to each other. The unit may be mounted in place as a single unit in the same manner as a drive machine. In a preferred case the drive machine 4 can e.g. be fixed to an elevator car guide rail, and the diverting pulleys 7, 10, 12, 14 in the upper part of the elevator shaft are mounted on beams in the upper part of the elevator shaft, which are fastened to the elevator car guide rails 2. The diverting pulleys 9, 11, 13, 18, 20, 22 on the elevator car are preferably mounted on beams placed in the upper and lower part of the elevator car, but they may also be secured to the elevator car in some other way, e.g. by mounting all diverting pulleys on the same beam. The diverting pulleys 8, 19, 21, 23 in the lower part of the elevator shaft are preferably mounted on the shaft floor. In fig. 1 the traction sheave engages the rope portion between diverting pulleys 8 and 9, which is a preferred solution according to the invention. In a preferred solution according to the invention the elevator car 1 is connected to the hoisting ropes 3 by means of at least one diverting pulley from whose rim the hoisting ropes go upwards on both sides of the diverting pulley and at least one diverting pulley from whose rim the hoisting ropes go downwards on both sides of the diverting pulley, and in which elevator the traction sheave 5 engages the rope portion of the hoisting ropes 3 between these diverting pulleys. The roping between the traction sheave 5 and diverting pulley 7 can also be implemented in other ways than double wrap roping, such as e.g. single wrap roping, in which case diverting pulley 7, ESW roping (extended single wrap), XW roping (X wrap) or some other suitable roping scheme will not necessarily be needed at all to be implemented.

The drive machine 4 placed in the elevator shaft is preferably of a flat construction, in other words the machine has a small thickness dimension compared to the width and/or height of the machine, or at least the machine is slim enough to be accommodated between the elevator car and a wall of the elevator shaft. The machine can also be placed in different ways, e.g. by arranging the slim machine partly or wholly between an imaginary extension of the elevator car and a shaft wall. In the elevator of the invention it is possible to use almost any type and design of drive machine 4 fitted into the space suited to it. For example, a geared or gearless machine may be used. The machine may be of compact and/or flat size. In the suspension solutions according to the invention the rope speed is often higher compared to the elevator speed, so that even uncomplicated machine types can be employed as basic machine solutions. The elevator shaft is preferably provided with equipment needed for the supply of power to the motor driving the traction sheave 5 and equipment needed for elevator control, both of which can be placed in a common instrument panel 6Or mounted separately from each other or partly or wholly integral with the drive machine 4. A preferred solution is a gearless machine comprising a permanent magnet motor. The drive machine may be fixed to a wall of the elevator shaft, to the ceiling, to a guide rail or to some other structure, such as a beam or frame. In elevators with machine below, another possibility is to mount the machine on the bottom of the elevator shaft. Fig. 1 presents a preferred suspension solution, in which the suspension ratio of the diverting pulleys above the elevator car and the diverting pulleys below the elevator car is in both cases the same 7: 1. To visualize this ratio in practice it refers to the ratio of the distance travelled by the hoisting rope to the distance travelled by the elevator car. The suspension arrangement above the elevator car 1 is implemented by means of diverting pulleys 14, 13, 12, 11, 10, 9 and the suspension arrangement below the elevator car 1 is implemented by means of diverting pulleys 23, 22, 21, 20, 19, 18, 8. Other suspension schemes may also be used to implement the present invention. The elevator of the invention can also be implemented as a solution comprising a machine room or the machine can be mounted movable together with the elevator. In the invention the diverting pulleys connected to the elevator car can preferably be mounted on the same beam. This beam can be fitted on top of the elevator car, on the side of the elevator car or under the elevator car, on the elevator car frame or in some other suitable place in the elevator car structure. The diverting pulleys may also be fitted separately in place on the elevator car and in the elevator shaft. The diverting pulleys disposed above the elevator car in the elevator shaft, preferably in the upper part of the elevator shaft, and/or the diverting pulleys disposed below the elevator car in the elevator shaft, preferably in the lower part of the elevator shaft, may also be fitted e.g. on a common anchorage, such as e.g. a beam. The function of the lever 15 pivoted on the elevator car at point 17 in fig. 1 is to eliminate rope elongations occurring in the hoisting ropes 3. On the other hand, it is essential for elevator operation and safety to maintain a sufficient tension in the lower rope portion, the lower partRope portion refers to the part of the hoisting rope below the elevator car. By means of the lever arrangement 15 according to the invention, the tensioning of the hoisting rope and the compensation of rope elongation can be achieved without the use of springs or weights as in the prior art. By means of the lever arrangement 15 of the invention, rope tensioning can also be achieved in such a way that rope forces T acting in different directions on the traction sheave 5₁And T₂Ratio of T between₁/T₂May be maintained at a desired constant value, which may be, for example, 2. With regard to rope force, we can also say rope tension. This constant ratio can be varied by varying the distances a and b, since T₁/T₂B/a. When using odd suspension ratios in the suspension of the elevator car, the lever 15 is pivotally mounted on the elevator car, and when using even suspension ratios, the lever 15 is pivotally mounted on the elevator shaft.

Fig. 2 presents a diagrammatic illustration of the structure of an elevator according to the invention. The elevator is preferably an elevator without machine room with a drive machine 204 placed in the elevator shaft. The elevator shown in the figure is a traction sheave elevator with machine above and without counterweight, the elevator car 201 moving along guide rails 2. The passage of the hoisting ropes 203 in fig. 2 is similar to that in fig. 1, but in fig. 2 it differs in that the lever 215 is non-movably pivotally mounted on one wall of the elevator shaft at point 217. Since the lever 215 is pivotally mounted on the elevator shaft, preferably on a wall of the elevator shaft, instead of on the elevator car, it is the case that the suspension ratio in the rope portion above the elevator car 1 and in the rope portion below it is even. The suspension above the elevator car comprises a hoisting machine 204 and diverting pulleys 209, 210, 211, 212, 213, 214. The suspension below the elevator car comprises diverting pulleys 208, 218, 219, 229, 221, 222, 223. One end of the hoisting rope is fastened to the lever 215 at point 216, the point 216 being a distance a from the pivot point 217; and its other end is secured to lever 215 at point 224, point 224 being a distance b from pivot point 217. In the rope portion above the elevator car and the rope portion below it, the suspension ratio of the elevator car is 6: 1.

The length of the hoisting ropes used in elevators without counterweight is large due to the high suspension ratio. E.g. in an elevator without counterweight suspended with a suspension ratio of 10:1, in which the same suspension ratio of 10:1 is used both above and below the elevator car, and which elevator has a hoisting height of 25m, the rope length of the hoisting ropes is about 270 m. In this case the length of the rope may vary up to about 50cm due to variations in rope stress and/or temperature. The requirements regarding rope elongation compensation are therefore also high. For the operation and safety of the elevator it is essential that the ropes below the elevator car are kept under a sufficient tension. This cannot always be achieved by using a spring or a simple lever.

Fig. 3 presents a diagrammatic illustration of the structure of an elevator according to the invention. The elevator is preferably an elevator without machine room with a drive machine 304 placed in the elevator shaft. The elevator shown in the figure is a traction sheave elevator with machine above and without counterweight, the elevator car 301 moving along guide rails 302. In fig. 3 the lever solution used in fig. 1 and 2 has been replaced by two sheave-like members, preferably sheaves 313 and 315, connected to each other at point 314, where the tensioning sheaves 313, 315 are fixedly attached to the elevator car 301. Of the sheave-like members, the sheave 315 engaging the hoisting rope portion below the elevator car has a larger diameter than the sheave 313 engaging the hoisting rope portion above the elevator car. The diameter ratio between the diameters of the tensioning sheaves 313 and 315 determines the magnitude of the tensioning force acting on the hoisting ropes and thus the compensating force for the elongation of the hoisting ropes. The advantage resulting from the use of tensioning sheaves in this solution is that the structure can compensate even very large rope elongations. By varying the diameter of the tensioning sheaves, the magnitude of the rope elongation to be compensated and the rope force T acting on the traction sheave can be influenced₁And T₂And this ratio can be made constant by virtue of this arrangement. Rope length for use in an elevator, due to a large suspension ratio or a large hoisting heightIs very large. For the operation and safety of the elevator it is essential that the hoisting rope portion below the elevator car is kept under sufficient tension and that the amount of rope elongation to be compensated is large. This often cannot be achieved with a spring or a simple lever. In the case of odd suspension ratios above and below the elevator car, the tensioning sheaves are fitted immovably in connection with the elevator car, and in the case of even suspension ratios, the tensioning sheaves are fitted immovably in the elevator shaft or in some other corresponding part, the latter not being fitted immovably to the elevator car. This solution can be implemented with tensioning sheaves as shown in fig. 3 and 4, but the number of sheave-like members used can vary; for example, it is possible to use only one rope sheave and the locations for the fixing points of the hoisting ropes differ in diameter. It is also possible to use e.g. more than two tensioning sheaves so that the diameter ratio between the sheaves is changed by only changing the diameter of the tensioning sheaves.

In fig. 3, the hoisting ropes run as follows: one end of the hoisting ropes is secured to the tensioning sheave 313, which sheave is immovably attached to the sheave 315. The set of sheaves 313, 315 is firmly fitted to the elevator car at point 314. From the rope sheave 313 the hoisting ropes 303 go upwards and meet a diverting pulley 312 placed above the elevator car in the elevator shaft, preferably in the upper part of the elevator shaft, passing around it along rope grooves provided on the diverting pulley 312. The rope grooves may be coated or uncoated, for example with a friction-increasing material, such as polyurethane or some other suitable material. From pulley 312 the ropes go further downwards to a diverting pulley 311 on the elevator car and, having passed around this pulley, the ropes go further upwards to a diverting pulley 310 fitted in the upper part of the elevator shaft. Having passed around this diverting pulley 310 the ropes go downwards again to a diverting pulley 309 mounted on the elevator car, and having passed around this pulley the ropes go further upwards to a diverting pulley 307 preferably fitted near the hoisting machine 304. Between diverting pulley 307 and the traction sheave 304 the figure shows X wrap roping in which the rope portion of the hoisting ropes going upwards from diverting pulley 307 to the traction sheave 305 runs crosswise with the rope portion returning from the traction sheave 305 to diverting pulley 307. The pulleys 313, 312, 311, 310, 309 together with the hoisting machine constitute a suspension arrangement above the elevator car, where the suspension ratio is the same as in the suspension arrangement below the elevator car, which suspension ratio is 5: 1 in fig. 3. From diverting pulley 307 the ropes go further to a diverting pulley 308, which is preferably fitted in place in the lower part of the elevator shaft, e.g. on the elevator car guide rails 302 or on the shaft floor or at some other appropriate place. Having passed around diverting pulley 308 the hoisting ropes 303 go further upwards to a diverting pulley 316 fitted in place on the elevator car, pass around this pulley and then go further downwards to a diverting pulley 317 in the lower part of the elevator shaft, pass around it and return to a diverting pulley 318 fitted in place on the elevator car. Having passed around diverting pulley 318 the hoisting ropes 303 go further downwards to a diverting pulley 319 fitted in place in the lower part of the elevator shaft, pass around it and then go further upwards to a tensioning sheave 315 fitted in place on the elevator car and immovably fitted to the tensioning sheave 313.

Fig. 4 presents a diagrammatic illustration of the structure of an elevator according to the invention. Which is preferably an elevator without machine room and with a drive machine 404 placed in the elevator shaft. The elevator shown in the figure is a traction sheave elevator without counterweight and with machine above, the elevator car 401 moving along guide rails 402. The passage of the hoisting ropes 403 in fig. 4 corresponds to that in fig. 3, the difference in fig. 4 being that the tensioning sheaves 413,415 are fitted in place in the elevator shaft, preferably on the bottom of the elevator shaft. Since the tensioning sheaves 413,415 are fitted in place in the elevator shaft without being connected to the elevator car, this is a situation with even suspension ratios both in the rope portion above the elevator car 1 and in the rope portion below it. In fig. 4, the suspension ratio is 4: 1. The end of the hoisting ropes 403 below the elevator car 401 is fastened to the tensioning sheave 415 having the larger diameter, and the end of the hoisting ropes above the elevator car is fastened to the tensioning sheave 413 having the smaller diameter. The tensioning sheaves 413,415 are immovably fitted together and secured to the elevator shaft via a mount 420. The suspension arrangement above the elevator car comprises a hoisting machine and diverting pulleys 412, 411, 410, 409, 407. The suspension arrangement below the elevator car comprises diverting pulleys 408, 416, 417, 418, 419. The tensioning sheaves (415, 413) used as a rope elongation compensating system presented in fig. 4 can also advantageously be mounted to replace or be the diverting pulley 419 at the bottom of the elevator shaft, which is preferably mounted in place on the shaft floor; or a diverting pulley 412 in the upper part of the elevator shaft, which is preferably fixed in place at the top of the shaft. In this embodiment the number of diverting pulleys required is reduced by one compared to the embodiment shown in fig. 4. This also makes the installation of the elevator easier and quicker in appropriate circumstances.

Fig. 5 presents a diagrammatic illustration of the structure of an elevator according to the invention. The elevator is preferably an elevator without machine room with a drive machine 504 placed in the elevator shaft. The elevator shown in the figure is a traction sheave elevator without counterweight and with machine above, the elevator car 501 moving along guide rails 502. In elevators with a large hoisting height, the elongation of the hoisting ropes involves the need to compensate rope elongation, which must be reliably implemented within certain permitted limit values. With a set of rope force compensating sheaves 524 according to the invention as presented in fig. 5, a very long movement is obtained for compensating rope elongations. This allows even large elongations to be compensated, which often cannot be done with simple lever or spring solutions. The rope force T acting on the traction sheave of the compensating sheave arrangement according to the invention, which is presented in fig. 5, is applied to the traction sheave₁And T₂Form a constant ratio T₁/T₂. In the case shown in FIG. 5, the ratio T₁/T₂Equal to 2/1.

The passage of the hoisting ropes in fig. 5 is as follows. One end of the hoisting ropes 503 is fastened to a diverting pulley 525 that has been fitted to hang on the rope portion coming down from diverting pulley 514. Diverting pulleys 514 and 525 together constitute a rope force compensating system 524, which in the case of fig. 5 is a set of compensating sheaves. From diverting pulley 514 the hoisting ropes further run as described in connection with the previous figures between diverting pulleys 512,510, 507 fitted in place in the upper part of the elevator shaft and diverting pulleys 513,511, 509 fitted in place on the elevator car, forming a suspension arrangement above the elevator car. Between diverting pulley 507 and the traction sheave 505 DW roping is used, which has been described in detail in connection with fig. 1. The roping between the diverting pulley 507 and the traction sheave can also be implemented using other suitable roping solutions such as e.g. SW, XW or ESW suspension. From the traction sheave the hoisting ropes go further via diverting pulley 507 to a diverting pulley 508 placed in the lower part of the elevator shaft. Having passed around diverting pulley 508 the hoisting ropes run in the manner described in connection with the previous figures between diverting pulleys 518,520, 522 fitted in place in the lower part of the shaft and diverting pulleys 519,521, 523 fitted on the elevator car 501. From diverting pulley 523 the hoisting ropes 503 go further to a diverting pulley 525 comprised in the rope force compensating sheave system 524 and fastened to one end of the hoisting ropes. Passing around it along the rope grooves of diverting pulley 525 and then to an anchorage 526 at the other end of the rope in the elevator shaft or in some other appropriate place. The suspension ratio of the elevator car is 6:1 both above and below the elevator car.

In the embodiment presented in fig. 5, the rope force compensating sheave system 524 compensates rope elongations by means of diverting pulley 525. This diverting pulley 525 moves over a distance I compensating the elongation of the hoisting rope 503. The compensating distance I is equal to half the rope elongation of the hoisting rope. Furthermore, this arrangement results in a constant tension across the traction sheave 505, the ratio T between the rope forces₁/T₂Is 2/1. The rope force compensating sheave system 524 can also be implemented in other ways than those described in this example, e.g. by using a more complex suspension arrangement with rope force compensating sheaves, e.g. by using different suspension ratios between the diverting pulleys in the compensating sheave system.

Fig. 6 presents another embodiment of the use of a compensating device for compensating rope elongations. Passage of ropes andthe suspension ratios in the rope portions above and below the elevator car are identical to those in fig. 5 as described above. The hoisting ropes 603 run in the manner presented in fig. 5 between diverting pulleys 609,611, 613 mounted on the elevator car and diverting pulleys 610,612, 614 in the upper part of the elevator shaft and the traction sheave 605, and from the traction sheave 605 the ropes go further to the lower part of the elevator shaft to the traction sheave 608 and, after passing around it, run further between diverting pulleys 618,620, 622 fitted on the elevator car and diverting pulleys 619,621, 623 fitted in the lower part of the elevator shaft as described in connection with fig. 5. The suspension ratio of the elevator car in the parts above and below the elevator car is 6: 1. The elevator presented in fig. 6 differs from the situation presented in fig. 5 in the compensating device 624. Fig. 6 presents a roping arrangement according to the invention that differs in the combination of the compensating sheaves of the compensating device 624. In the combination of compensating sheaves one end 629 of the hoisting ropes 603 is immovably fitted to the elevator shaft, from which point the hoisting ropes go to the traction sheave 625, pass around it and go further to a diverting pulley 614 that can be fitted in place in the upper part of the elevator shaft, from where they go further to the traction sheave 605 in the manner described above. Diverting pulley 625 is fixedly fitted in connection with another diverting pulley 626. The two diverting pulleys 626,625 may e.g. be placed on the same shaft or they may be connected to each other by a straight bar or in some other suitable way. After passing around the traction sheave 623 the part of the hoisting ropes 603 below the elevator car goes to the diverting pulley 626 of the compensating device 624, which is connected to diverting pulley 625 in the manner described above. Having passed around diverting pulley 626, the hoisting ropes 603 go further to a diverting pulley 627 immovably fitted in place in the elevator shaft and forming part of the compensating system 624. After passing around diverting pulley 627 the hoisting ropes 603 go further to an anchorage 628, to which the other ends of the hoisting ropes are immovably secured. This anchorage 628 is on diverting pulley 625 or fixedly connected to it. With this roping arrangement in the compensating device 624, the rope force T is obtained₁And T₂Constant ratio T between₁/T₂3/2. With this roping arrangement it is possible to use the traction sheaveThe upper realisation of SW roping, in other words the diverting pulley 507 presented in fig. 5, is not completely necessary. SW roping can be used on the traction sheave because the roping arrangement in the compensating device 624 shown minimizes the required friction on the traction sheave and allows a smaller rope force T₁And T₂. If desired, however, the diverting pulley 507 presented in fig. 5 can be used e.g. to make tangential contact with the hoisting ropes as described in connection with the previous figures. In the compensating device 624 the roping and the number of diverting pulleys can also be varied in ways other than those described in connection with fig. 6 here. Via the roping suspension ratio, T, in the compensating device 624₁/T₂The ratio can be maintained at a desired constant magnitude. In fig. 6 the compensation of rope elongations is implemented by means of diverting pulley 625 and diverting pulley 626 fitted fixedly to it. The compensation distance of rope elongation in the compensating device is such that the larger the suspension ratio in it, the shorter it is.

Fig. 7 is an embodiment wherein the suspension ratio of the ropes is 1: 1. In the elevator presented in fig. 7, the compensation of rope elongation is implemented using a lever 715 non-movably pivotally mounted on the elevator car 701, acting as a rope force compensating device. The rope forces are compensated and a rope force T is obtained in the manner described in connection with figure 1₁And T₂Constant ratio of between, which yields T₁/T₂Ratio of T₁/T₂B/a, regardless of the size of the load. The example of an embodiment of the elevator of the invention presented in fig. 7 can be implemented using conventional ropes of a diameter of 8mm, such as are commonly used in elevators for a nominal load of 4 persons, i.e. about 700 kg. In this elevator, T₁/T₂The ratio is 1.5/1 and it uses a traction sheave with a diameter of 320mm and usually undercut grooves, while the mass of the elevator car is 700 kg. In this case the force T lifting the elevator car upwards₁1.5 times the force needed to lift the weight of the elevator car and its load, and the force T acting downwards on the elevator car₂Is the force required to lift the weight of the elevator car as well as the load. This example is not ideal because it results in a change with respect to loadUnnecessarily large rope tension. By increasing the suspension ratio, this rope tension can be reduced. The elevator of the invention can be provided with a geared machine and it can be constructed e.g. according to fig. 7 with 1:1 roping.

Fig. 8 is an elevator according to the invention, in which a suspension ratio of 2:1 is used in the roping portions 803 of the hoisting rope above and below the elevator car 801 and DW roping is used between the traction sheave 805 and diverting pulley 807. The compensation of rope elongation and constant rope force are achieved with a rope elongation compensating device as presented in fig. 5, which forms T₁/T₂2/1 and diverting pulley 825 travels a compensating distance equal to half the magnitude of the rope elongation.

Fig. 9 presents an embodiment of the invention for compensating rope elongations and maintaining a constant ratio of rope forces. In fig. 9 the passage of the hoisting ropes is as in fig. 6 described above, where the suspension ratio of the elevator car above and below the elevator car is 6: 1. In fig. 9 the passage of the hoisting ropes differs from the situation in fig. 6 in that the ropes go downwards from diverting pulley 914 to diverting pulley 924 and in the compensating system. Furthermore, one end of the hoisting ropes 903 is immovably fixed to the elevator shaft at a point 923 before the traction sheave 922. In the figure, diverting pulley 908 is fixed to one end of the hoisting ropes 903 at point 926 in order to achieve compensation of the elongation of the hoisting ropes. The elongation of the hoisting ropes is compensated in such a way that the diverting pulley 908 moves upwards or downwards over a distance corresponding to half the rope elongation, thereby compensating the rope elongation. In the system presented in fig. 9, the compensation of rope elongation and the maintenance of constant rope force are implemented according to the same principle as in the situation presented in fig. 5, where the ratio T of the rope forces is₁/T₂2/1 and the compensating distance traveled by diverting pulley 908 amounts to half the magnitude of the rope elongation. The compensating system of fig. 9 can be implemented by fixing one end of the hoisting ropes to the diverting pulley 908, 919, 921 using any diverting pulley 908, 919, 921 in the lower part of the elevator shaft, as described above in connection with diverting pulley 908.

When the elevator car is suspended with a small suspension ratio, such as e.g. 1:1, 1:2, 1:3 or 1:4, diverting pulleys of large diameter and hoisting ropes of large thickness can be used. Below the elevator car, smaller diverting pulleys can be used if necessary, because the tension in the hoisting ropes is lower than in the rope portion above the elevator car, allowing smaller bending radii of the hoisting ropes to be used. In elevators with a smaller space below the elevator car it is preferable to use diverting pulleys of small diameter in the rope portion below the elevator car, because by using the rope force compensating system according to the invention the tension in the rope portion below the elevator car can be kept at a constant level, i.e. at the ratio T₁/T₂To be said lower than the tension in the rope portion above the elevator car. This makes it possible to reduce the diameter of the diverting pulleys in the rope portion below the elevator car without causing any significant loss in respect of the service life of the hoisting ropes. For example, the ratio of the diameter D of the diverting pulley to the diameter D of the rope used may be D/D<40 and preferably the D/D ratio may be only 25-30, when the ratio of the diameter of the diverting pulleys in the rope portion above the elevator car to the diameter of the hoisting ropes is 40. By using diverting pulleys having a smaller diameter, the space required below the elevator car can be reduced to a very small size, which may preferably be only 200 mm.

A preferred embodiment of the elevator of the invention is an elevator without machine room and with machine above, in which the drive machine has a coated traction sheave, and which elevator has thin hoisting ropes of a substantially round cross-section. In which elevator the contact angle between the hoisting ropes and the traction sheave is greater than 180. The elevator comprises a unit with a mounting base on which is fitted a drive machine, a traction sheave and a diverting pulley fitted at a correct angle relative to the traction sheave. This unit is secured to the elevator guide rails. The elevator is implemented without counterweight with a suspension ratio of 9:1, so that the rope suspension ratio above the elevator car and the rope suspension ratio below the elevator car are both 9:1, and the ropes of the elevator runIn the space between one of the walls of the elevator car and a wall of the elevator shaft. Solution for compensating rope elongations of elevator ropes comprising a set of compensating sheaves, which are under force T₁And T₂Form a constant ratio T₁/T₂2: 1. With the compensating sheave system used, the required compensating distance amounts to half the magnitude of the rope elongation.

Another preferred embodiment of the elevator of the invention is an elevator with a suspension ratio of 10:1 above and below the elevator car without counterweight. This embodiment uses normal hoisting ropes, preferably of a diameter of 8mm, and a traction sheave made of cast iron at least in the area of the rope grooves. The traction sheave has undercut rope grooves and its contact angle to the traction sheave has been adjusted to 180 or more by means of a diverting pulley. When using normal 8mm ropes the traction sheave diameter is preferably 340 mm. The diverting pulleys used are large rope sheaves having a diameter of 320, 330, 340mm or even more in the case of a normal 8mm hoisting rope. The rope forces are kept constant so that the ratio T between them₁/T₂Equal to 3/2.

It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the examples described above, but that they may be varied within the scope of the invention. The number of times the hoisting ropes are passed between, for example, the upper part of the elevator shaft and the elevator car and between the elevator car and the diverting pulleys below it is not a decisive question as regards the basic advantages of the invention, although some additional advantages can be achieved by using multiple rope passes. The application is generally implemented such that the ropes are passed to the elevator car as many times from above as from below so that the suspension ratios of the diverting pulleys going upwards and the diverting pulleys going downwards are the same. It is also obvious that the hoisting ropes do not necessarily need to pass under the elevator car. In accordance with the examples described above the skilled person can vary the embodiments of the invention and the traction sheaves and rope pulleys, instead of being coated metal pulleys, may also be uncoated metal pulleys or uncoated pulleys made of some other material suited to the purpose.

It is further obvious to the person skilled in the art that the metallic traction sheaves and rope pulleys used in the invention, which function as diverting pulleys and are coated with a non-metallic material at least in the area of their grooves, may be implemented using a coating material consisting of e.g. rubber, polyurethane or some other material suited to the purpose.

It is also obvious to the person skilled in the art that the elevator car and the machine unit can be disposed in the cross-sectional area of the elevator shaft in a different layout than described in the examples. Such a different lay-out may be e.g. one in which the machine is located behind the elevator car as seen from the shaft door and the ropes are passed under the elevator car in a diagonal direction with respect to the bottom of the elevator car. Passing the ropes under the elevator car diagonally or otherwise oblique relative to the shape of the bottom also creates some advantage in other types of suspension lay-out when the suspension of the elevator car on the ropes is made symmetrical relative to the centre of mass of the elevator.

It is further obvious to the person skilled in the art that the equipment needed for the supply of power to the motor and the equipment needed for elevator control can be placed elsewhere than in connection with the machine unit, e.g. in a separate instrument panel, or the equipment needed for control can be made as separate units, which can be placed in the elevator shaft and/or in some other part of the building. It is also obvious to the skilled person that an elevator applying the invention can be equipped in a manner differing from the examples described above. It is further obvious to the skilled person that the elevator of the invention can be implemented using almost any type of flexible hoisting means as hoisting ropes, e.g. flexible rope of one or more strands, flat belt, cogged belt, v-belt or some other type of belt suited to the purpose.

It is obvious to the person skilled in the art that instead of using ropes with filler, the invention can be implemented using ropes without filler, lubricated or unlubricated. Furthermore, it is obvious to the person skilled in the art that the rope can be twisted in many ways.

It is also obvious to the person skilled in the art that the elevator of the invention can be implemented to increase the contact angle a using a different roping arrangement between the traction sheave and the diverting pulley/diverting pulleys than the roping arrangement described as an example. For instance, the diverting pulley/diverting pulleys, the traction sheave and the hoisting ropes can be arranged in other ways than in the roping arrangements described in the examples. It is also obvious to the skilled person that in the elevator of the invention the elevator can also be provided with a counterweight, in which elevator the counterweight has e.g. a weight below the weight of the elevator car and is suspended with a separate roping arrangement.

Due to the bearing resistance of the rope pulleys used as diverting pulleys and due to the friction between the ropes and the rope sheaves and possible losses occurring in the compensating system, the ratio between the tensions deviates somewhat from the nominal ratio of the compensating system. Even a deviation of 5% does not cause any significant disadvantage, because in any case the elevator must have some inherent robustness.

Claims (14)

1. Elevator without counterweight having an elevator car, in which the elevator car is suspended by means of hoisting ropes consisting of a single rope or several parallel ropes, said elevator having a traction sheave which moves the elevator car by means of the hoisting ropes, characterized in that the hoisting ropes have rope portions going upwards and downwards from the elevator car, and the rope portions going upwards from the elevator car are at a first rope tension (T)₁) This tension is then greater than a second rope tension (T) being the rope tension of the rope portion going downwards from the elevator car₂) And electricityThe ladder comprises a compensating system for maintaining the ratio (T) between the first rope tension and the second rope tension₁/T₂) Substantially constant, the elevator car is connected to the hoisting ropes by means of at least one diverting pulley from whose rim both sides the hoisting ropes go upwards and at least one diverting pulley from whose rim both sides the hoisting ropes go downwards, and the suspension ratio of the upper rope portion and the lower rope portion is at least 2:1 roping.

2. Elevator according to claim 1, characterized in that the compensating system is a lever, a set of tensioning sheaves or a set of compensating sheaves.

3. Elevator according to claim 1, characterized in that the compensating system comprises one and/or more diverting pulleys.

4. Elevator according to claim 1 or 2, characterized in that the continuous contact angle between the traction sheave and the hoisting ropes is at least 180 °.

5. Elevator according to claim 1 or 2, characterized in that the roping used between the traction sheave and the rope pulley serving as a diverting pulley is ESW roping or DW roping or XW roping.

6. Elevator according to claim 1 or 2, characterized in that the hoisting ropes are of a strength greater than 2000N/mm²Hoisting ropes of rope wires.

7. Elevator according to claim 1 or 2, characterized in that the hoisting ropes have a diameter of less than 8 mm.

8. Elevator according to claim 7, characterized in that the diameter of the hoisting ropes is between 3 and 5 mm.

9. Elevator according to claim 1 or 2, characterized in that the weight of the hoisting machine is substantially less than the load.

10. Elevator according to claim 1 or 2, characterized in that the traction sheave is coated with polyurethane or rubber.

11. Elevator according to claim 1 or 2, characterized in that the traction sheave is made of metal at least in the area of the rope grooves.

12. Elevator according to claim 11, characterized in that the metal is cast iron.

13. Elevator according to claim 11, characterized in that the rope grooves are undercut.

14. Elevator according to claim 1 or 2, characterized in that the D/D ratio of the diverting pulleys below the elevator car is below 40.