CN117509353A - Suspension device for traction sheave elevator - Google Patents

Abstract

Suspension device for a traction sheave elevator, having a width B and a thickness D and in the form of a flat belt with a plurality of traction sheave strands embedded in the friction-increasing belt body material whereby the traction sheave and optionally at least one further guide wheel are contacted during normal operation, characterized in that in the belt central area (at B/2) immediately adjacent traction sheave strands are spaced apart from each other by a smaller distance than in the flat belt area near the side walls.

Description

Suspension device for traction sheave elevator

Technical Field

The present invention relates to a suspension device for traction sheave elevators according to the generic term of claim 1 and the use of such a suspension device according to the generic term of claim 6 and a suspension device elevator with such a suspension device according to the generic term of claim 7.

Background

The lifting of the elevator car along the elevator shaft is usually achieved by means of driven suspension devices such as ropes or belts, especially when large drops have to be overcome. In order to reduce the drive torque required to operate the elevator with the corresponding suspension, the suspension is usually steered several times by means of guide wheels according to the pulley block principle. This allows the use of small high-speed drive motors that are more easily integrated into the elevator shaft.

In order to further reduce the installation space required in the elevator shaft, flat belts are increasingly also used as suspension devices instead of wire ropes. This is because the use of flat belts generally allows the diameters of the traction sheave and the guide wheel to be further reduced due to the geometry of the flat belts and their materials.

The flat belt generally has a rectangular cross section. During operation of the elevator, one of the two long sides of the rectangular cross section runs along the guide sheave and/or the traction sheave, so that the guide sheave rolls along this side of the suspension. The two short sides of the cross section perpendicular to the long sides are typically much shorter than the diameter of the wire cable used as a suspension instead of a flat belt. In addition, the flat belt is usually not made of steel, or at least not made mainly of steel, but is the case when the cable is the suspension device. Instead, flat belts are usually made at least predominantly of polyurethane plastic. Both of these means that the flat belt has a significantly greater flexibility than the wire rope in the direction of rotation of the guide wheel or traction sheave. When the suspension is turned 180 deg. (as is typically the case along the outer circumference of the traction sheave), the radius achievable with flat belts is significantly smaller than in the case of steel ropes. As a result, significantly smaller guide wheels and traction sheaves can be used. In terms of the available installation space, they can in turn be integrated more easily into the elevator shaft.

There are indeed usually several steel cords in the flat belt, otherwise the flat belt made of plastic will not be able to withstand the tensile forces occurring during operation of the elevator. But the diameter of these wires is many times smaller than the wires used as suspension means instead of flat belts. The wire ropes installed in the flat belts can thus achieve a radius many times smaller than the wire ropes used in place of the car belts for the same steering angle.

Prior Art

To ensure that the flat belt cannot slip off the traction sheave or guide sheave or collide with any lateral stop during the belt payout process and cause excessive wear, the flat belt must be centered on the traction sheave and guide sheave. Traction sheaves and guide wheels having convexly curved surfaces of revolution are commonly used for this purpose. Fig. 1 and 2 show such a guide wheel 4 (or traction sheave 4) and a flat belt 1 running thereon as known in the prior art. The belt running surface 5 can be seen here to be convexly curved. The flat belt 1 is located on the belt running surface 5 in such a way that if it is completely rigid it will form a tangent to the apex of the belt running surface 5. But due to its elasticity the flat belt 1 adapts at least to some extent to the course of the belt running surface 5. Since the flat belt 1 is tensioned between the guide wheels 4 (and the at least one traction sheave 4) during operation, a tensile force acts on the flat belt at the guide wheels 4. These tensile forces then ensure that the flat belt 1 does not move in the direction of one of the side walls 6 defining the belt running surface 5, but remains centered in the region of the apex of the convex belt running surface 5.

However, such a pair also has some drawbacks, as shown by finite element analysis. The flat belt 1 exhibits a certain stiffness due to the traction means strands 2 arranged in the belt body material 3, which are here designed as steel cords and are therefore relatively inelastic in comparison to the belt body material. This has the effect that the flat belt 1 does not bear against the convex belt running surface 5 over its entire width extending in a direction perpendicular to the side walls 6 of the guide wheel 4. This in turn thus causes that the pulling force exerted by the guide wheel 4 on the flat belt 1 cannot produce a constant stretch curve along the width of the flat belt 1. In contrast, there is a maximum tensile stress in the center of the flat belt 1, centered above the apex of the convex belt running surface, the maximum tensile stress decreasing toward the edges of the flat belt 1. This is shown by the arrow in fig. 2.

The steel cords 2 arranged in the flat belt 1 for receiving tensile forces are thus subjected to different loads. The wire ropes 2 in the central area are subjected to the greatest tensile stress, while the outer wire ropes 2 are subjected to much less stress. This is problematic because the wire ropes 2 exposed to the maximum tensile stress (at the same gauge size) have a service life significantly shorter than the outer wire ropes 2. Once one of the steel cords 2 exceeds its service life, the entire flat belt 1 has to be replaced. Thus, the problem results in a relatively short service life of the flat belt. It is in principle conceivable to make the flat belt thicker in the central region of the belt body material 3 than in the edge regions of the steel cord 2 or to make it of a different material. But this would result in a significant increase in the manufacturing cost of the flat belt.

Task of the invention

In view of this, the object of the invention is to provide a flat ribbon suspension with an extended service life.

Solution of the invention

The solution to the above-mentioned problem is provided by a suspension elevator with a suspension according to the invention, from which the car is suspended and lifted. The suspension elevator comprises a guide wheel designed as a traction sheave and preferably at least one other guide wheel. The elevator is characterized in that at least one guide wheel contacts the suspension with its convex jacket. The jacket of the guide wheel has a curvature designed such that traction means strands enclosed in the flat belt near the side walls tend to withstand less heavy loads than traction means strands enclosed in the center or near the center.

Due to the convex jacket surface of the guide wheel or the convex belt running surface, the hoisting device is centered on the belt running surface during operation, as described above. Since the distance of the traction means strands in the flat belt, which are spaced apart from each other in the belt central region (at B/2), is smaller than in the flat belt region near the side walls, the tensile stresses occurring in the flat belt are better distributed over the individual traction means strands. This extends the life of the suspension and reduces the maintenance effort required to operate the elevator.

The fact that the car is "suspended" from the suspension means may mean that the suspension means is rigidly connected to the car at one end, i.e. the car is actually suspended from the suspension means. However, this fact also includes: at least one guide wheel is attached to the elevator car, which guide wheel rolls along the loop formed by the suspension. In any case, the car is attached to the suspension device in such a way that the suspension device is driven by the traction sheave to raise and lower the car.

In this case, "a" suspension means not a single suspension means, but preferably four suspension means in the form of flat strips which are parallel to one another and are next to one another on their sides or at least close to one another. Thus, the word "a" is not used as a numerical word, but is used in a generic sense only.

Best mode for carrying out the invention

The present invention can be designed in a number of ways to further improve its effectiveness or usefulness.

For example, it is particularly preferred that the distance between two central traction device strands is smaller than the distance between all other paired traction device strands.

At the belt central area, i.e. at B/2, the greatest tensile stress is generated due to the form in which the traction members are centered by means of the convex belt running surface already described. Since the distance between the traction means strands is at a minimum here, a maximum traction means strand density is obtained in this region. Thus, the tensile forces occurring in the hoisting device strands are reduced.

Due to the centering of the suspension means, it is advantageous that the hoisting means strands are always arranged in pairs. This results in a symmetrical distribution of the tensile force on the traction means strands arranged along the flat belt width B.

In another preferred embodiment, three central traction device strands form two traction device strand pairs. The distance between the two pairs of traction device strands is less than the distance between all other pairs of traction device strands.

Ideally, one of the traction device strands is disposed precisely at the center of the flat belt, and the other two traction device strands are disposed symmetrically on the left and right sides of the first traction device strand.

This ensures that the highest possible traction means strand density is obtained in the centre of the flat belt, i.e. in the region of maximum tensile stress.

Also in the area adjacent to the center of the flat belt, which is also subjected to high tensile stresses, a good distribution of tensile stresses over the strands of the traction means is obtained by means of two pairs of strands of traction means, which are spaced apart by a short distance compared to the other paired strands of traction means.

In another preferred embodiment, two traction means strands adjacent to the central traction means strand on both left and right sides in the direction along the longitudinal axis L of the flat belt form a traction means strand pair with one of the traction means strands. Each of the traction device strands forming such a traction device strand pair is spaced farther from each other than the center traction device strand. Further, the distance between the traction means strands forming such a traction means strand pair is smaller than the distance between the traction means strands laterally adjoining them on the left and right sides.

Thus, the density of the traction device strands increases gradually from the flat belt edge region toward the flat belt longitudinal axis L. Most of the center traction device strands are disposed in the region of maximum tensile stress. The tension differences occurring in the hoisting device strands are then reduced.

It is conceivable that the central traction means strand is three traction means strands, one of which is arranged exactly at B/2 and the other two of which are symmetrically arranged on the left and right sides thereof. It is equally conceivable that the "central" traction means strand is only two traction means strands arranged on the left and right sides of the longitudinal axis of the flat belt.

The longitudinal axis of the flat belt is the axis of the flat belt that extends through B/2 and D/2 and is parallel to the longitudinal axis of each traction device strand.

In another preferred embodiment the hoisting means strands are at least partly ropes, preferably wire ropes. More preferably, the hoisting means strands are mainly ropes, preferably wire ropes. Ideally, the traction means strands are even entirely ropes, preferably wire ropes.

In the case of using wire ropes as hoisting means strands, the ropes are preferably wire ropes, each wire rope being formed from a plurality of individual wire strands.

For this purpose, the individual steel wire strands are individually braided together to form a steel wire rope. It is also conceivable to use different types of wires in one rope, thereby fusing the advantages of different materials. In this way the desired tensile strength of the hoisting device strands can be ensured while at the same time a sufficient flexibility is obtained.

The at least one guide wheel and the suspension means assigned thereto are preferably matched to one another in such a way that a stress difference occurring between the one or more central traction means strands and each of the two traction means strands closest to the side wall as the suspension means circulates through the at least one guide wheel is less than 35%. More preferably, the stress differential is less than 25%.

The design of the suspension or traction means strands must be based on the traction means strands that are subjected to the highest loads. If the loading of the traction means strands in the central region (B/2) of the flat belt is no longer many times greater than the traction means strands in the edge regions, the traction means strands which are not too heavily loaded do not have to be designed to be oversized. This has a positive effect on the manufacturing costs of the suspension.

Desirably, the at least one guide wheel has a belt running surface on its jacket that is wider than the width of the suspension device.

This allows a sufficient safety distance to be maintained from the edge area of the guide wheel. This reduces the risk of the suspension slipping off the guide wheel or colliding with the part of the guide wheel that limits the belt running surface of the guide wheel.

List of drawings

Fig. 1-2 show a known prior art suspension device and a guide wheel in an operatively mounted state.

Fig. 3 shows a suspension device according to the invention in a cross-sectional view.

Fig. 4 shows the suspension device according to the invention and the guide wheel in a operatively mounted state.

Fig. 5 shows the structure of the traction device strands.

Preferred design

The operation of the present invention is illustrated with reference to fig. 3-5.

Fig. 3 shows a cross section of the flat belt 1, which clearly illustrates its structure. The flat belt 1 is composed of a belt body material 3 and six traction means strands 2 arranged in the belt body material 3. The hoisting means strands 2 are steel ropes with a circular cross-section. The tape body material 3 is polyurethane having a rectangular cross section. The hoisting device strands 2 serve to absorb tensile stresses occurring during operation of the flat belt 1, while the belt body material 3 serves to ensure sufficient static friction between the guide wheel 4 and the flat belt 1 or between the drive wheel and the flat belt 1. The diameter of each traction means strand 2 is approximately 60% of the thickness D of the belt body material 3, which corresponds to the short side of the rectangular cross section of the belt body material 3.

The traction device strands 2 are not uniformly arranged over the width B of the flat belt 1, which corresponds to the long side of the belt body material 3. The hoisting device strands 2 are indeed arranged mirror-symmetrically with respect to a virtual plane extending through half the width B of the belt body material 3. However, the distance between the individual traction device strands 2 increases from the traction device strands 2 arranged in the center of the belt body material 3 toward the traction device strands 2 arranged at the edges of the belt body material 3. The distance between the two central traction device strands 2 is smaller than their respective radii. A distance has been provided from each traction means strand 2 adjacent to the two central traction means strands 2, which distance corresponds approximately to the diameter of the respective traction means strand 2. Instead, there is a distance between the traction device strand 2 adjacent to the central traction device strand 2 and the corresponding (proximal wall) traction device strand 2 adjacent thereto, which corresponds to approximately twice the diameter of each traction device strand 2. The distance between the aforementioned proximal-side strands 2 of traction means and the side edges of the belt body material 3 is about half the diameter of the individual strands 2 of traction means, respectively.

The longitudinal axis of each traction device strand 2 lies on an imaginary line extending through half the thickness D of the belt body material 3 and orthogonal to the short sides of the belt body material 3.

Due to the described arrangement of the hoisting device strands 2, a relatively even stress distribution is obtained on each hoisting device strand 2. This is shown in fig. 4. Where the flat belt 1 and the guide wheel 4 can be seen. The flat belt 1 is in contact with the belt running surface 5 of the guide wheel 4 in such a way that a movement of the flat belt 1 in the circumferential direction of the guide wheel 4 results in a rotational movement of the guide wheel 4. In order to ensure that the flat belt 1 is not displaced in the direction of the side walls 6 of the guide wheel 4 during operation, the flat belt 1 is centered on the guide wheel 4. For this purpose, the belt running surface 5 is convexly curved. The flat belt 1 can then be mounted on the guide wheel 4 in such a way that the apex of the curvature of the belt running surface 5 is located just below the center of the flat belt 1. The symmetrical structure of the flat belt 1 thus ensures the desired centring in combination with the tension acting on the flat belt 1 during operation. Due to the large distance between the hoisting device strands 2 in the edge region of the flat belt 1, it is ensured on the one hand that the flat belt 1 is less stiff and better against the convexly curved belt running surface 5. In addition, the small distance between the traction means strands 2 in the central region of the flat belt 1 ensures that the greatest tensile stresses occurring in this region are distributed over as many traction means strands 2 as possible. Since there are fewer traction means strands 2 in the edge region of the flat belt 1, but the tensile stress is also lower, the traction means strands 2 of the flat belt 1 as a whole are subjected to a more uniform load. The tensile stress acting on the individual traction means strands 2 is schematically indicated by arrows in fig. 4.

The structure of the individual hoisting device strands 2 can be understood from fig. 5. This means that the hoisting device strands 2 are not made of solid material, but are formed of a large number of fine wires 7 interwoven with each other.

List of reference numerals

1. Suspension device/flat belt

2. Traction device strand or wire rope

3. Tape body material

4. Traction or guiding wheels

5. Tape contact zone/tape moving surface

6. Side walls of guide wheels or traction wheels

7. Single strand wire

B width of hanging means or strips

Thickness of D suspension or belt

Claims (9)

1. Suspension device (1) for a traction sheave elevator, having a width B and a thickness D and in the form of a flat belt (1) with a plurality of traction sheave strands (2) embedded in a friction-increasing belt body material (3) whereby the traction sheave (4) and optionally at least one further guide sheave (4) are contacted during normal operation, characterized in that in the belt central region (at B/2) immediately adjacent traction sheave strands (2) are spaced apart from each other a smaller distance than in the region of the flat belt (1) close to the side walls.

2. Suspension device (1) for traction sheave elevators according to claim 1, characterized in that two central traction means strands (2) are spaced apart from each other by a distance smaller than all other paired traction means strands (2).

3. Suspension device (1) for traction sheave elevators according to claim 1, wherein three central traction means strands (2) form two pairs of traction means strands (2), each pair of traction means strands being at a smaller distance from each other than all other pairs of traction means strands (2).

4. Suspension device (1) for a traction sheave elevator according to claim 2 or 3, characterized in that two traction means strands (2) adjacent to the plurality of central traction means strands (2) on the left and right in the direction of the longitudinal axis L of the flat belt each form a pair of traction means strands with one traction means strand (2) of the plurality of central traction means strands (2), wherein the traction means strands (2) of the pair of traction means strands are spaced apart from each other by a distance greater than the distance from the central traction means strand (2), and the traction means strands (2) of the pair of traction means strands are spaced apart from each other by a distance smaller than the distance from the traction means strands (2) adjacent on the left and right sides.

5. Suspension device (1) according to one of the preceding claims, characterized in that the hoisting device strand (2) is a rope, preferably a wire rope.

6. Use of a suspension device (1) according to one of the preceding claims in such a way that the suspension device is turned in the other direction by at least one guide wheel (4) with a convexly curved belt contact area (5), preferably at least 170 °.

7. Suspension elevator with a suspension (1) according to one of the preceding claims and a guide wheel (4) designed as a traction sheave (4) and preferably at least one other guide wheel (4), characterized in that the at least one guide wheel (4) contacts the suspension (1) with its convex jacket having a curvature such that the traction sheave (2) enclosed in the flat belt (1) near the side wall tends to withstand a less heavy load than the traction sheave (2) enclosed in the middle or near the center.

8. Suspension elevator according to the preceding claim, characterized in that the at least one guide wheel (4) and the suspension (1) associated therewith are matched to each other such that the tension difference occurring between the central traction sheave or sheaves (2) and each of the two traction sheave strands (2) closest to the side wall during the suspension (1) wrapping around the at least one guide wheel (4) is less than 35%, preferably less than 25%.

9. Suspension elevator according to the two preceding claims, characterized in that the at least one guide wheel (4) has a belt running surface (5) on its jacket that is wider than the suspension width (B).