HK1181371B - Traction sheave elevator - Google Patents

Description

Traction sheave elevator

Technical Field

The object of the invention is a traction sheave elevator.

Background

Modernization of elevators in prior art has generally focused on elevators that no longer meet the requirements of the times technically and/or otherwise. Modernization may focus on some subfunctions or subsystems or, to its fullest extent, may mean a complete or substantially complete modernization of the elevator. Possible modernization points include, among others: a control system of the elevator; the elevator passes the hoisting function of the machinery and roping; an elevator door; and an elevator car. On the other hand, the maintenance procedures of the elevator maintain the existing systems and functionality of the elevator. Thus, it is normal that when the hoisting ropes have become worn, they are replaced with new hoisting ropes and, usually in this case, with similar hoisting ropes. At the same time, the traction sheave can be renewed or overhauled. Thus, for example, a replacement rope will last substantially the same time as an old rope has lasted. Accordingly, when updating the traction sheave, the new traction sheave corresponds in characteristics to the previous traction sheave. Neither maintenance activities nor, in general, modernization lead to substantial changes to the rope winding arrangement.

When considering the service life of hoisting ropes, it is appreciated that in traction sheave elevators the rope tension of the elevator ropes passing around the traction sheave generally has different magnitudes on different sides of the traction sheave, which in particular tries to cause the hoisting ropes to slip in the rope grooves of the traction sheave. The tension difference is caused by the counterweight on one side of the traction sheave not having the same weight as the elevator car with the load on the opposite side of the traction sheave. Sometimes the elevator car is empty, sometimes full and sometimes in between empty and full. On the other hand, the mass of the counterweight is usually unchanged. The aim is to select the mass of the counterweight to ensure that it is as optimal as possible under different loads of the elevator car, but this is not sufficient in all situations. These types of situations may be, for example, acceleration, braking, and emergency stops. Up to a certain limit the slipping of the ropes on the traction sheave caused by the tension difference is easy to control, but often the friction of the metal rope grooves is not sufficient to manage a sudden large tension difference, in which case the elevator ropes start to slip too much in the rope grooves of the traction sheave.

According to the prior art, the aim has been to increase the friction required in the rope grooves of the traction sheave, in particular by forming an undercut in the rope grooves that is wider than usual. This solution does increase the friction but at the same time the stress of the elevator ropes increases, because the bearing surface of the elevator ropes in the rope grooves is reduced. In fact, for this reason, this solution is not advantageous, since the service life of the rope decreases as the stress of the rope increases.

One way of increasing the friction is provided in the solution according to japanese patent publication No. JP54124136 (a). Wherein a friction-increasing material, such as rock wool, is arranged in the undercut of the rope groove, which material is pressed against the elevator rope from below, pushed by a separate flexible material in the same undercut at the lower part. When the asbestos wears, the flexible material pushes the asbestos ring towards the elevator rope. The problem with this solution is, in particular, that the material of the two components in the undercut groove is difficult to control. The elevator rope tries to push the asbestos ring in front of it under the influence of friction, in which case a force acts on the interface between the asbestos and the flexible material, which force breaks the structure. In addition, this type of structure is very difficult to size correctly.

Correspondingly, US patent publication US1944426 provides a rope sheave solution in fig. 1, in which the bottom of the metal rope groove of the metal rope sheave comprises a groove filled with rubber, which is glued to the groove. However, the purpose of the rubber here is to prevent the steel cord from wearing due to the expansion of the steel cord in the direction of the rubber. No improvement in friction traction is mentioned in this document, nor is it clear from this document how the rope grooves, the height of the rubber and the diameter of the steel cord are mutually dimensioned.

According to the prior art, friction traction is also improved by enlarging the contact angle between the elevator ropes and the traction sheave. In this case, for example, a so-called Double Wrap (DW) and Extended Single Wrap (ESW) construction is used, wherein a contact angle of about 270-. The result is good frictional traction, but one problem in these solutions is that the bending of the rope stresses the rope, which bending causes the rope to wear, thus shortening the service life of the rope.

Disclosure of Invention

The object of the invention is to eliminate the aforementioned drawbacks and to achieve a manufacturing solution and/or modernization solution of an elevator, in which the traction sheave in the existing elevator is replaced together with the replacement of the ropes, the rope grooves of which traction sheave comprise at least two different materials, which are mounted to each other so that the frictional traction of the rope grooves is large, whereby it has been possible to shape the rope grooves so that the wear of the elevator ropes is reduced and the service life of the elevator ropes is increased. The object of the invention is also to achieve a solution in which the slipping of the elevator ropes is easily controlled. Another object is to achieve a method for manufacturing or modernizing a traction sheave elevator in which it has been possible to simplify and lighten the structure of the elevator compared to earlier elevators due to good controllability of the traction and slipping by friction and thereby due to improved rope traction sheave contact. In this case, for example in connection with modernization, the so-called Double Wrap (DW) and Extended Single Wrap (ESW) structures of the worn rope are removed and replaced by a simpler so-called Single Wrap (SW) structure that causes less rope wear, which SW structure comprises much less rope bending that applies pressure to the rope than in the aforementioned DW and ESW structures. Another object of the invention is to achieve a traction sheave elevator comprising a traction sheave whose rope grooves comprise at least two different materials, which are mounted to each other so that the frictional traction of the rope grooves is large, whereby it has been possible to shape the rope grooves so that the wear of the elevator ropes is reduced and the service life of the elevator ropes is increased, and in connection with which traction sheave the slipping of the ropes is easily controlled.

Some embodiments of the invention are also discussed in the description part of the present application. It is conceivable as an invention that the inventive concept comprises a traction sheave elevator and a traction sheave with rope grooves comprising at least two different materials. The inventive content 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 features included in the following embodiments may be superfluous from the point of view of separate inventive concepts. Likewise, the different details provided in connection with each embodiment of the invention are also applicable to the other embodiments.

The rope tension of the elevator ropes on the traction sheave of a traction sheave elevator has different magnitudes at different positions of the traction sheave, wherein the traction sheave is usually referred to as a metallic traction sheave, most often a steel or cast iron traction sheave, the rope tension of which is caused by the aforementioned tension difference. Due to this variable tension, the hoisting ropes try to flex (flexing), in which case a small slip of the hoisting ropes occurs in the rope grooves of the traction sheave. Under normal operating conditions, including acceleration and braking, when the hoisting rope reaches the traction sheave, it moves at the rim speed of the traction sheave and slippage caused by the telescoping of the hoisting rope occurs only over a portion of the contact length between the hoisting rope and the traction sheave, which in this case is in the direction in which the hoisting rope leaves the traction sheave. This slipping in fact distributes the expansion and contraction of the hoisting ropes caused by the tension difference over a longer part of the contact length between the hoisting ropes and the traction sheave, possibly even over the entire length of the curve over which the hoisting ropes are in contact with the traction sheave. The gradual slipping of the hoisting ropes and the traction sheave caused by this telescoping takes place towards greater rope tensions. More simply, it can be said that the part of the contact length between the hoisting ropes and the traction sheave, where no slippage of this kind occurs due to the expansion and contraction of the hoisting ropes, is a kind of friction reserve on which the safe traction of the traction sheave elevator is based. Thus, normally a small slip therefore occurs on the side of greater tension, but on the side of lesser tension, slip does not necessarily occur. In this case the hoisting ropes as a whole have not yet slipped in the rope grooves, but instead they have slipped only on the side with greater tension and the more they have slipped, the greater the rope tension. It can be said that slippage occurs only over a part of the contact length between the hoisting ropes and the traction sheave or that slippage is partly present when the traction sheave moves the hoisting ropes under normal operating conditions. In the invention, mainly partial slippage between the traction sheave and the hoisting ropes of the type described above is utilized by arranging a flexible insert material in the rope groove, the frictional traction of which is improved when the hoisting rope slips relative to it. Preferably the coefficient of friction between such material and the rope is even at its minimum greater than the coefficient of friction between the rope and the actual traction sheave material. Even more preferably the coefficient of friction between such material and the rope is even at its minimum greater than the coefficient of friction between the rope and the actual traction sheave material at its minimum. As such, the slip between the rope and the traction sheave under normal load conditions of the elevator is very small, because with normal hoisting rope dimensioning the elongation of the rope is less than 1/1000. When using the solution of the invention, it is normal practice that the hoisting ropes actually slip to some extent against the actual traction sheave material due to elongation, but not against the flexible insert material, but instead receive a supporting force that is tangential with respect to the traction sheave due to deformation of the flexible insert material and/or due to internal shear stresses. Also, in case the rope starts to slip against the insert material, supporting forces tangential to the traction sheave are transferred between the traction sheave and the hoisting rope via the flexible insert material and/or via internal shear stresses. An increased traction between the hoisting ropes and the rope grooves is thus achieved in at least a part of the contact surface, which traction also improves the overall traction.

A very suitable insert material to be arranged into the rope groove is a flexible elastomer, which consists for example of rubber, polyurethane, cellular rubber, foam plastic or, suitably, for example, of micro-cellular polyurethane and in which the compression can be directed in only one direction, i.e. in the direction of the radius of the traction sheave. An insert material made of micro-cellular polyurethane and suitable for this purpose is for example Cellasto, with a density of between about 300-.

Accordingly, it is advantageous to select the dimensions of the insert material for the rope grooves such that the compression of the insert by the elevator rope does not produce too great a force variation. In this case, the compression of the insert is, for example, between 15 and 40%, preferably between 18 and 25% and suitably about 20%. Accordingly, the magnitude of compression in this case is actually about 1-2 mm, depending on the size selection. Thus, the metal support surface of the rope groove bears the largest part of the rope force and the insert, based on its size selection, is compressed by the aforementioned 15-40%, bearing only the force of essentially constant magnitude generated by the compression in the radial direction of the traction sheave.

A construction in which the insert supports the hoisting rope with a substantially constant supporting force is easy to implement, in which case the interaction between the hoisting rope and the insert is independent of the load of the elevator. In this case the groove material, which determines the position of the elevator rope in the radial direction, is harder than the insert and always bears all the variations of the load.

It is also possible to arrange the flexible insert material in the rope grooves of the traction sheave so that it is on the side of the rope groove and correspondingly the non-flexible, supportive metal material is on the bottom of the rope groove.

The solution according to the invention can also provide a new elevator with a traction sheave of the type described above, the rope grooves of which comprise at least two different materials, of which the first material is a substantially hard and inflexible material, e.g. metal or hard plastic, and the second material is a substantially flexible material, which is arranged to increase its frictional traction when the slippage of the elevator ropes increases at certain positions of the rope grooves.

By means of this solution according to the invention, a number of different advantages are achieved, depending on what is desired to be optimized in connection with modernization. A basic advantage is, inter alia, that the friction traction of the traction sheave is improved, whereby the control of the slipping of the elevator ropes on the traction sheave is also improved. Thereby, an advantage is also that a smaller and lighter structure can be used in the elevator, which also results in a reduced manufacturing cost, due to better friction traction. With the lighter solution according to the invention, the energy consumption is also smaller than with conventional solutions, in which case the operating costs are also reduced since less machinery is required. Also, wear of the structures is reduced, as less force acts on the structures. Another advantage is that the frictional traction of the elevator ropes can be improved without increasing the stress of the elevator ropes. Hereby is achieved a significant advantage that the service life of the elevator rope can be extended. In this case, for example the aforementioned DW and ESW rope suspensions can be changed to SW rope suspensions of less worn ropes, in which case the load of the shaft is reduced and the service life of the machinery and roping is increased. In addition, the number of ropes can be reduced by suitable optimization.

Due to the aforementioned advantages with regard to friction traction, further decisive advantages are achieved. The elevator car can be enlarged, for example, if there is space in the elevator hoistway for this purpose. A further advantage is that the speed of the elevator can be increased, because the frictional traction increases. In this case, for example, the maximum speed range of the elevator can be lengthened and/or the acceleration of the elevator can be improved.

Drawings

The invention will be described in more detail hereinafter by means of an example of embodiment thereof, with reference to the accompanying drawings, in which:

fig. 1 shows a schematic simplified side view of a traction sheave elevator by means of a rope tension diagram of a traction sheave elevator;

fig. 2 presents a cross-sectional view of a top part of a traction sheave elevator modernized by a method according to the invention, with bottom-cut rope grooves and with an insert in a part of the rope grooves;

fig. 3 shows a cross-sectional view of the top part of the traction sheave according to fig. 2, with the bottom cut-out rope groove with an insert and the elevator ropes in the rope groove;

fig. 4 shows a schematic, simplified and enlarged view of the bottom of the rope groove of the traction sheave according to fig. 2 with an insert but without ropes;

fig. 5 shows a schematic, simplified and enlarged view of the bottom of the rope groove of the traction sheave according to fig. 2, with an insert pressed by the rope;

fig. 6 shows a side view of different inserts of a groove of a traction sheave to be used in the method according to the invention, said inserts being provided with various relief cuts;

figure 7 shows a schematic and simplified view of the different load situations typical on a traction sheave as seen from the side of the traction sheave;

fig. 8 presents a graph compiled on the basis of measurements of the ratio of the sliding percentage of the elevator rope to the coefficient of friction between the elevator rope and the rope groove;

fig. 9 shows a schematic simplified side view of a Double Wrap (DW) elevator suspension;

fig. 10 shows a schematic simplified side view of an Extended Single Wrap (ESW) elevator suspension;

fig. 11 shows a schematic simplified side view of a Single Wrap (SW) elevator suspension; and

fig. 12 shows a schematic simplified side view of one other Single Wrap (SW) elevator suspension.

Detailed Description

Fig. 1 presents a schematic simplified view of a typical traction sheave elevator comprising an elevator car 1, a counterweight 2 and elevator roping formed by elevator ropes 3 parallel to each other mounted between them. The elevator ropes 3 are guided in rope grooves dimensioned for the elevator ropes 3 around a traction sheave 4 rotated by the hoisting machine of the elevator. When the traction sheave 4 rotates, the traction sheave 4 simultaneously moves the elevator car 1 and the counterweight 2 in the upward direction and in the downward direction due to friction.

Due to the difference between the counterweight 2 and the load in the elevator car 1 and the elevator car at any given time, the rope force T exerted on the elevator ropes 3_CTWAnd T_CARWith different magnitudes on different sides of the traction sheave 4. When the elevator car 1 contains a load of less than one-half the nominal load, the counterweight is usually heavier than the elevator car 1 with a load. In this case the rope force T between the counterweight 2 and the traction sheave 4_CTWGreater than the rope force T between the elevator car 1 and the traction sheave 4_CAR. Accordingly, when the elevator car 1 contains a load of one-half of the small and large rated load, the counterweight 2 is generally lighter than the elevator car 1 with the load. In this case the rope force T between the counterweight 2 and the traction sheave 4_CTWIs less than the rope force T between the elevator car 1 and the traction sheave 4_CAR. In the situation shown in fig. 1, the rope force between the elevator car 1 and the traction sheave 4 is T_CAR>T_CTW. As a result, a rope force T acting on the elevator ropes 3 in the rope grooves of the traction sheave 4_CTWAnd T_CARThe rope tension generated is not constant but, on the contrary, increases when going from the counterweight 2 side to the elevator car 1 side. This increased rope tension is schematically illustrated by the tension diagram 5 depicted in fig. 1. As explained earlier, this tension difference tries to produce a slipping of the elevator ropes 3 in the rope grooves. It is attempted to compensate for the tension difference across the traction sheave 4 by controlled slipping.

Fig. 2-5 show the top of a split traction sheave 4 of a traction sheave elevator modernized according to the method of the invention. The bottom of the rope groove 8 is enlarged in fig. 4 and 5. The material of the traction sheave 4 is, for example, metallic, cast iron or steel, whichever is suitable. The traction sheave 4 comprises parallel rope grooves 8 on the rim of the rope sheave, the bottoms of which have a substantially semicircular cross-sectional shape, in the bottoms of which bottom cut grooves 9 have been formed, the cross-sectional shape of which bottom cut grooves 9 is substantially rectangular and substantially symmetrical with respect to the cross-section of the rope grooves 8.

A filler piece of elastic material, i.e. an insert 11, is arranged in each bottom undercut groove 9 such that the top edge of the insert 11 is substantially higher than the lowest point of the radius of curvature of the semicircular string groove 8. In other words, the insert 11 extends partly into the substantially semi-circular cross-sectional shape of the rope groove 8 and at the same time into the space of the passage of the elevator rope 3. For the sake of clarity, the free top surface of the insert 11 in fig. 3 is drawn with dashed lines as visible within the elevator rope 3. The insert 11 is immovably fixed in the bottom cut-out groove 9 of the rope groove 8. This fixing is preferably achieved, for example, by gluing the insert 11 at its bottom to the bottom of the groove 9. In addition, the insert 11 is shaped so that it is a substantially one-piece ring, which is flexible at least in the direction of the radius of the traction sheave 4. Preferably the insert 11 is more flexible in the radial direction of the traction sheave 4 than in the rim direction of the traction sheave 4, or at least the insert 11 is arranged such that the expansion of the insert 11 under the elevator ropes 3 is greater in the radial direction than in the rim direction. In addition, the insert 11 is preferably narrower than the bottom cut-out groove 9, in which case a gap 9a is maintained between the insert 11 and the side edges of the groove 9, which are symmetrically placed in the groove 9, in the direction of which gap the insert 11 can expand when the elevator rope 3 presses the insert 11 towards the bottom of the groove 9. This expansion is more clearly shown in figure 5. Although the insert 11 is preferably narrower than the undercut groove 9, an insert which completely fills the undercut groove in the cross-section of the rope groove in the transverse direction can also be applied to the invention. A completely filled insert of this type may also be fixed to the side of the undercut groove, for example by gluing.

On both sides of the insert 11, essentially from the insert 11 towards the outer edge of the traction sheave 4, are curved metal support surfaces 10 in the rope grooves 8, against which support surfaces the elevator ropes 3 are fitted to mainly bear. The heights of the rope grooves 8, undercut grooves 9 and inserts 11 are mutually dimensioned in relation to the diameter of the elevator rope 3 such that the elevator rope 3 presses the inserts 11 properly in the direction of the radius of the traction sheave 4, but only so little that the metallic bearing surface 10 of the rope grooves 8 supports the elevator rope over the entire contact distance of the traction angle, i.e. over the entire contact length of the rope, under all loads3 and determines its proper position in the slot. In this case the following equation is suitable for the normal force N exerted on the insert 11 and caused by the elevator rope 3₂：

N₂<T/R, wherein,

t being the smaller rope force acting over the traction sheave, i.e. depending on the load T at that time_CTWOr T_CARThe smaller of the two, and

r-radius of the traction sheave.

In fact, N₂As close as possible to the value T/R, for example between about 80-100% of the value T/R, preferably between about 90-100% of the value T/R.

If the tolerances are dimensioned to be strict and to the greatest extent, in practical applications, for example when the car and the counterweight are made lighter than conventionally determined in connection with modernization, it can happen that the metallic support surface 10 does not have to support the elevator rope 3 in all cases over the entire distance of the contact angle when applying the inventive concept. In this case, for example, the elevator rope 3 can be separated instantaneously by a small contact distance from the support surface 10, in which case the contact angle supported by the metallic support surface 10 is in fact smaller than the overall contact angle. However, the solution according to the invention will in principle be effective even in this case, even if not as good as expected.

In this description the term friction coefficient refers to the friction coefficient between the rope and the rope groove of the traction sheave, which is the result of the different friction between the rope and the material of the rope groove. Here, the coefficient of friction is thus an empirically obtained coefficient of friction between two objects sliding against each other, not a specific coefficient of friction of an individual material. Hereinafter, this is also referred to as the effective friction coefficient.

The material and the structure of the insert 11 are chosen such that the coefficient of friction between the contact surfaces of the insert 11 and the elevator rope 3 is greater than the coefficient of friction between the metal support surfaces 10 of the rope grooves 8 and the elevator rope 3. In addition, the material of the insert 11 is chosen such that the coefficient of friction between the contact surfaces of the insert 11 and the elevator rope 3 substantially increases when the sliding speed, i.e. the slip, between the surfaces increases. The friction mechanism of the insert 11 is in this case different from that of a metallic/metallic surface. The friction is in this case achieved mainly via the deformation and the internal damping of the insert 11. Due to the aforementioned dimensioning of the rope grooves 8 and the choice of material of the inserts 11, the inserts 11 participate even more in the formation of friction traction when the slippage of the elevator rope 3 increases, while at the same time the friction traction of the metal support surfaces 10 of the rope grooves 8 remains unchanged or even decreases. These types of possible situations are e.g. acceleration, braking and emergency stops. The friction of the elevator rope 3 against the insert 11 may be characterized by a combined effect of hysteresis friction (hysteresis friction) and friction adhesion effects.

The elastic insert 11 is an elastomer made of, for example, rubber, polyurethane, cellular rubber, or suitably of, for example, microcellular polyurethane, wherein the size of the gas bubbles is preferably in the range of, for example, 0.05-0.5 mm and the density of the material is about 300-650kg/m³Of less than about 550kg/m, however, suitably³And preferably at about 350-500kg/m³In the meantime. One such insert material made of micro-cellular polyurethane suitable for this purpose is, for example, the commercially available product name Cellasto.

Based on the size selection the height of the insert 11 is selected such that the compression of the insert 11 caused by the elevator ropes 3 is e.g. between 15-40%, preferably between 18-25%, suitably about 20%. In this case, the absolute magnitude of compression is about 1-2 millimeters, depending on the size selection. The metal support surface 10 of the rope groove 8 thus supports the largest part of the rope force, and the insert 11 is, due to its dimensioning, compressed by the aforementioned 15-40%, bearing only the force N of substantially constant magnitude resulting from the compression₂. Because the flexible insert 11 supports a part of the rope force, it simultaneously reduces to some extent the force exerted by the elevator rope 3 on itThe pressure occurring on the metal support surface 10 of the rope groove 8 is however so small that the lifting force generated by the insert 11 is not sufficient to separate the elevator rope 3 from the support surface 10 of the rope groove 8.

Fig. 6 shows a schematic simplified side view of different inserts 11 for the groove 9 of the traction sheave 4 used in the method according to the invention, said inserts being provided with various damping cut-outs 12 which contribute to the expansion and contraction of the insert 11 in the longitudinal direction of the insert and which balance the deformation forces generated in the insert by the rope 3.

By the method according to the invention, two mechanisms of transferring force to the elevator ropes 3 act in parallel in the rope grooves 8 of the traction sheave 4 of modernized traction sheave elevators, of which mechanisms the first is the rope/iron contact in the rope groove 8 and the second is the rope/insert contact in the undercut 9 of the rope groove 8. There are various force effects that provide traction in the cord/insert contact, which are, among others:

1) the compression force exerted on the ropes 3 in the radial direction of the traction sheave 4, caused by the insert 11, can be adjusted to a desired value by adjusting the compression and properties of the insert 11,

2) the friction between the insert 11 and the rope 3, an

3) The deformation forces caused by the transmission of the non-slipping rope 3 in the insert 11,

4) and the deformation forces caused by the sliding rope 3 in the insert.

These phenomena can be examined in different ways. For example, when the rope slips, at least a part of the force can be analyzed by means of the concept of hysteresis friction. Since forces in the direction of the rope grooves, i.e. in the tangential direction of the traction sheave, are generated in the insert material via friction, it can be considered that the insert material contains support forces between the hoisting ropes and the metal structure of the traction sheave, which support forces are transmitted in the insert material as shear forces, which cause the insert material to stretch internally in the direction of greater rope tension.

Maximum frictional traction is obtained with the friction limit close to the entire contact length, wherein there is no slippage of the rope 3 with respect to the insert 11, and wherein the deformation force will be constant. However, since the displacement of the rope 3 relative to the insert 11 increases during the entire period of rope contact, the aforementioned maximum frictional traction is not achieved by the insert 11 being of homogeneous structure, but instead the deformation force increases during contact so much that slippage occurs. However, the deformation force may be influenced by the properties and geometry of the insert 11. The easiest adjustable aspect is the thickness and compression of the insert 11. The second easiest adjustable aspect is the shape of the surface of the insert 11.

Fig. 6 shows some inserts 11 in which various relief cuts 12, such as apertures, holes or side cuts, have been made in the surface or immediately below the surface. The relief cuts have been made, for example, by water jet cutting. The uppermost insert of fig. 6 comprises triangular shaped apertures 12 which are open at the top as seen from the side and which are successive to each other, every other of these apertures being pointed downwards and every other being pointed upwards. An insert 11 below the uppermost insert comprises a top surface without a gap, but immediately below that surface are a plurality of successive triangular apertures 12, every other of which is pointed downwards and every other is pointed upwards. Correspondingly, in the insert 11 next to the lowermost insert, the top surface is also free of gaps, and as the apertures 12 below this surface are a plurality of circular holes divided into two rows one above the other. The lowermost insert 11 comprises as apertures 12 a plurality of successive cuts in the transverse direction of the insert, which cuts form a comb-like structure, which cuts enable better flexibility of the surface of the insert 11 by collapsing easily in the direction of the rope force when the rope force compresses the insert.

Fig. 7 shows, schematically and in simplified form, a modernization mainly by the method according to the inventionDifferent load situations on the traction sheave 4 of a traction sheave elevator. A substantially constant magnitude of force N resulting from compression of the insert 11₂Independent of the load situation and therefore essentially constant over the entire contact distance of the traction angle. In the lightest load situation, i.e. in the case of an empty elevator car 1, the rope force T acting on the traction sheave 4 on the elevator car 1 side₀Less than the rope force on the counterweight 2 side. Thus, in this case, T_CAR<T_CTWAnd the rope force T₀Increases substantially uniformly over the entire distance of the traction surface from the elevator car 1 side to the counterweight 2 side.

In addition, as can be seen from fig. 7, also in this lightest load situation, the rope force T₀The lifting force N generated by the compression of the insert 11 is greater over the entire contact distance of the traction angle₂Greater so that the lifting force N is greater₂The elevator ropes cannot be detached from the metallic support surface 10. In this case the elevator rope 3 has support of a hard, inflexible metal bearing surface 10 throughout the contact angle.

Correspondingly, in the case of the heaviest load, i.e. in the case of a full load of the elevator car 1, the rope force T acting on the traction sheave 4 on the elevator car 1 side₁Is larger than the rope force of the counterweight 2 side. In this case, T_CAR>T_CTWAnd the rope force T₁Increases substantially uniformly from the counterweight 2 side to the elevator car 1 side over the entire contact distance of the traction angle.

Fig. 8 shows a graph compiled on the basis of experimentally-made measurements of the ratio of the percentage of slip (slip%) of the elevator rope 3 to the coefficient of friction (coefficient of friction) between the elevator rope 3 and the rope grooves. The situation shown here is thus an empirically obtained effective coefficient of friction between two objects sliding against each other, not a specific coefficient of friction of an individual material.

It can be seen from the graph that in the case of a rope groove of only metal, for example cast iron, which rope groove is shown by curve 6 in fig. 8, the effective friction coefficient rises linearly and relatively sharply in the initial phase of the slip. When the slip is approximately 0.1%, the increase in the effective coefficient of friction, however, slows down rapidly and does not increase here beyond a limit value of approximately 0.14, even if the slip would increase even more. Thus the curve 6 becomes substantially vertical as the slip further increases. In this case, the situation is that the elevator ropes lose traction in the grooves of the traction sheave. It is typical for the wire rope grooves that when traction is lost, the traction is suddenly lost, there being virtually no room for adjustment regarding the traction.

Correspondingly, in the case of a rope groove of metal, for example cast iron, filled with the elastic insert 11 according to the invention, which is represented by curve 7 in fig. 8, the effective coefficient of friction likewise rises linearly and relatively sharply in the initial phase of the slip. As the slip increases, the effective coefficient of friction now continues its increase, and curve 7 does not change to the vertical position at all. At lower values of slip, the frictional drag produced by the insert 11 is substantially smaller and the metallic contact frictional drag dominates, but as the slip speed increases, the frictional drag of the insert 11 begins to increase and at the same time the metallic contact frictional drag proportionally decreases. For example, based on the test results, it can be estimated that the effective coefficient of friction between the insert 11 and the elevator rope 3 is about 0.4 or more for said dimensions and said material when the slip is 1%. However, the overall effective coefficient of friction is only approximately 0.16 according to curve 7. Thus, the effective coefficient of friction between the insert 11 and the elevator rope 3 is greater than the effective coefficient of friction between the metal support surface 10 of the rope groove 8 and the elevator rope 3 when the slip increases.

In practice, when only metallic rope grooves, for example cast iron, are concerned, values of the effective friction coefficient greater than 0.1 cannot be used in the dimensioning, so that it is possible to retain sufficient traction to be retained on the traction sheave in case of accident. Instead, in the solution according to the invention, there is a sufficient reserve of traction, since curve 7 starts to climb gradually. In this case, values greater than 0.1, for example up to 0.14, can be used for the effective coefficient of friction in the dimensioning. This enables T of the rope force_CAR/T_CTWThe ratio is larger, in which case the movable mass is smaller, with the further result that the acceleration forces are smaller, the energy consumption is lower and the losses are smaller and, in relation to the rope, the rope suspension comprising a number of bends stressing the rope is replaced by a simpler suspension prolonging the service life of the elevator rope. Also, the service life of the rope is extended because a narrower bottom cut out slot can be used. In addition, material can be saved.

Based on the test results it can be said that under certain conditions the total traction increases when the rope force decreases. This is mainly due to the fact that: the friction of the inserts 11 is substantially constant at constant slip speed, because the normal force acting on the inserts 11 is not dependent on the rope force as long as the metal support surfaces 10 of the rope grooves 8 support the elevator ropes 3 and determine their position in the rope grooves 8. In this case, it is said that the smaller the cable force, the larger the relative proportion of the frictional force of the insert 11. This is very important from the point of view of the invention, since the friction traction problem usually occurs especially at small rope forces.

Fig. 9 shows a schematic simplified side view of a Double Wrap (DW) elevator suspension, in which the parallel elevator ropes 3, e.g. from the elevator car, first rise up to the traction sheave 4, pass around the top of the traction sheave 4, descend down to the diverting pulley 4a, pass around its bottom, rise up again to the traction sheave 4 and after passing around the top of the traction sheave 4a second time, the elevator ropes descend to the counterweight. In this solution the contact angle of the elevator ropes 3 on the traction sheave is very large, in the solution according to the figure almost 360 degrees, but it can also be larger. In this case the friction traction is large, but one problem is that many bends of the elevator rope 3 stress the rope and thus shorten the service life of the rope.

Fig. 10 shows a schematic simplified side view of an extended single wrap (DW) elevator suspension, in which the parallel elevator ropes 3, e.g. from the elevator car, first rise up to the traction sheave 4 between diverting pulley 4a and traction sheave 4, pass around the top of the traction sheave 4, fall down downwards to diverting pulley 4a, pass around its top, and fall forwards to the counterweight. In this solution the contact angle of the elevator ropes 3 on the traction sheave 4 is at most about 270 degrees. In this case the friction traction is also large, but the problem is still that the many bends of the elevator ropes 3 stress the ropes and thus shorten the service life of the ropes, albeit not as much as in the DW solution. ESW and DW result in very wide traction sheaves and in oblique pulling on the traction sheave.

Fig. 11 shows a schematic simplified side view of another Single Wrap (SW) elevator suspension, where the parallel elevator ropes 3, e.g. from the elevator car, first rise to the traction sheave 4, pass over the top of the traction sheave 4, and descend via diverting pulley 4a to the counterweight. In this solution the contact angle of the elevator ropes 3 on the traction sheave is less than 180 degrees and there are two bends, in which case the stress exerted on the ropes is smaller, but the frictional traction is also much smaller than in the DW and ESW solutions.

Fig. 12 shows a schematic simplified side view of a Single Wrap (SW) elevator suspension, where parallel elevator ropes 3, e.g. from the elevator car, rise to the traction sheave 4, pass around the top of the traction sheave 4, and descend to the counterweight. In this solution the contact angle of the elevator ropes 3 on the traction sheave is less than 180 degrees and there is only one bend, in which case the stress exerted on the ropes is smaller, but the frictional traction is also much smaller than in the DW and ESW solutions.

In the method according to the invention, the existing traction sheave elevator is modernized so that in connection with the modernization the traction sheave 4 is replaced into the elevator, in which traction sheave the frictional traction of the rope grooves 8 is improved e.g. so that a greater part of the rope force exerted on the rope grooves 8 is produced by the metal bearing surfaces 10 of the rope grooves 8 of the essentially hard and inflexible first material and, correspondingly, a smaller part of the rope force exerted on the rope grooves 8 is produced by the flexible second material of the insert 11. Also, when the slippage of the elevator ropes 3 increases in the rope grooves 8, the frictional traction of the elevator ropes 3 is increased by the flexible second material being the insert 11. This means that at the same time as the slippage of the elevator rope 3 increases in the rope grooves 8, the frictional traction of the elevator rope 3 changes with respect to the increase in slippage from the hard and inflexible first material, i.e. from the metal support surface 10 of the rope grooves 8, to the flexible second material, which is the insert 11.

Preferably, in the method according to the invention, an insert 11 placed in the undercut groove 9 of the rope groove 8 of the rope sheave 4 and extending to its height into the space of the passage of the elevator rope 3 is used as flexible second material, which insert is compressed by the elevator rope 3 in the direction of the radius of the traction sheave 4 by about 15-40%, preferably about 18-25% and suitably about 20% of its height, while by means of the insert 11 a substantially constant value of the force N is applied as a flexible second material₂Is generated which relieves the pressure exerted by the elevator ropes 3 in the rope grooves 8.

With respect to modernization, one or more of the following structures or characteristics are simultaneously changed:

-a Double Winding (DW) machine to a Single Winding (SW) machine,

-the Extended Single Winding (ESW) machine is transformed into a Single Winding (SW) machine,

the undercut groove of the existing rope groove is made smaller,

-the number of elevator ropes is reduced,

the machine and other elevator structures are made lighter,

-the elevator car is enlarged,

the speed of the elevator is increased by extending the maximum speed period,

the speed of the elevator is increased by increasing the acceleration of the elevator.

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 presented below. Thus, for example, the shape and positioning of the insert in the rope groove may also differ from what is described above. Instead of an integral ring, the insert may for example be a tape which is glued to the bottom of the undercut groove.

Claims (21)

1. Traction sheave elevator comprising at least an elevator car (1) and a traction sheave (4) for moving the elevator car (1) by means of elevator ropes (3), the rim of which traction sheave comprises one or more rope grooves (8), wherein in the rope grooves at least a first material and a second material contact the elevator ropes (3), wherein the second material is more flexible and/or more compressible than the first material,

wherein the rope grooves (8) of the traction sheave (4) comprise an undercut groove (9) containing an insert (11) of a second material, and the heights of the rope grooves (8), undercut groove (9) and insert (11) are mutually dimensioned with respect to the diameter of the elevator rope (3), and the heights of the insert (11) and undercut groove (9) are selected such that the compression of the insert (11) caused by the elevator rope (3) is between 15-40%.

2. Traction sheave elevator according to claim 1, characterized in that the compression of the insert (11) caused by the elevator ropes (3) is between 18-25%.

3. Traction sheave elevator according to claim 1, characterized in that the compression of the insert (11) caused by the elevator ropes (3) is 20%.

4. Traction sheave elevator according to claim 1, characterized in that the friction coefficient of the second material with respect to the elevator ropes is larger than the friction coefficient between the base material of the metal traction sheave and the elevator ropes (3).

5. Traction sheave elevator according to one of claims 1-4, characterized in that the first material is a hard and inflexible material and the second material is a flexible material arranged to increase its frictional traction when the slippage of the elevator ropes (3) in the rope grooves (8) increases.

6. Traction sheave elevator according to claim 5, characterized in that the first material is metal or hard plastic.

7. Traction sheave elevator according to one of claims 1-4, characterized in that the elevator ropes (3) compress the insert (11) in the radius direction of the traction sheave (4) so little that the metal support surface (10) of the rope groove (8) supports the elevator ropes (3) and determines their position in the rope groove (8) over the entire contact distance of the traction angle.

8. Traction sheave elevator according to one of claims 1-4, characterized in that the height of the insert (11) and the size of the undercut (9) are chosen such that the compression of the insert (11) caused by the elevator ropes (3) is between 1-2 mm.

9. Traction sheave elevator according to one of claims 1-4, characterized in that on or immediately below the surface of the insert (11) are a number of successive relief cuts (12) in the longitudinal direction of the insert, which relief cuts (12) are adapted to balance the deformation forces generated by the rope (3) in the insert.

10. Traction sheave elevator according to claim 9, characterized in that the buffer cut (12) is an aperture.

11. Traction sheave elevator according to claim 9, characterized in that the buffer cut (12) is a hole.

12. Traction sheave elevator according to claim 9, characterized in that the relief cut (12) is a transverse cut.

13. Traction sheave elevator according to one of claims 1-4, characterized in that the stress of the elevator ropes (3) is reduced by reducing the width of the undercut groove (9).

14. Traction sheave elevator according to one of claims 1-4, characterized in that the stress of the elevator ropes (3) is reduced by reducing the contact angle between the elevator ropes (3) and the traction sheave (4).

15. Traction sheave elevator according to claim 14, characterized in that the contact angle between the elevator ropes (3) and the traction sheave (4) is reduced by converting a Double Wrap (DW) suspension or Extended Single Wrap (ESW) suspension into a Single Wrap (SW) suspension.

16. Traction sheave elevator comprising at least an elevator car (1) and a traction sheave (4) for moving the elevator car (1) by means of elevator ropes (3), the rim of the traction sheave comprising one or more rope grooves (8), which rope grooves (8) comprise at least two different materials in contact with the elevator ropes (3), wherein the first material is a hard and inflexible material and the second material is a flexible material, wherein the radial force of the flexible material mounted in the rope grooves (8) of the traction sheave (4) supports the elevator ropes (3) over the whole contact angle and is smaller than the radial force exerted by the elevator ropes (3) on the rope grooves (8),

wherein the rope grooves (8) of the traction sheave (4) comprise an undercut groove (9) containing an insert (11) of a second material, and the heights of the rope grooves (8), undercut groove (9) and insert (11) are mutually dimensioned with respect to the diameter of the elevator rope (3), and the heights of the insert (11) and undercut groove (9) are selected such that the compression of the insert (11) caused by the elevator rope (3) is between 15-40%.

17. Traction sheave elevator according to claim 16, characterized in that the compression of the insert (11) caused by the elevator ropes (3) is between 18-25%.

18. Traction sheave elevator according to claim 16, characterized in that the compression of the insert (11) caused by the elevator ropes (3) is 20%.

19. Traction sheave elevator according to claim 16, characterized in that the first material is metal or hard plastic.

20. Traction sheave elevator according to one of claims 16-19, characterized in that the flexible second material is arranged to increase its frictional traction when the slippage of the elevator ropes (3) in the rope grooves (8) increases.

21. Traction sheave elevator according to one of claims 16-19, characterized in that the elevator ropes (3) compress the insert (11) in the radius direction of the traction sheave (4) so little that the metal support surface (10) of the rope groove (8) supports the elevator ropes (3) and determines their position in the rope groove (8) over the entire contact distance of the traction angle.