FI96675B - Arrangement for balancing cable forces in a lift - Google Patents

Abstract

The invention concerns an arrangement for balancing the cable forces in parallel lift-support cables 6. The balancing arrangement comprises a frame part 1 with, for each support cable 6, a piston 4 which can move relative to the frame part. The frame part is provided with a closed pressure chamber in which a viscoelastic mass 12, subjected beforehand to high pressure, presses on the shoulder 14 of each piston in a direction opposite to the cable force. The pistons move inside boxes inter- connected by intermediate channels 11 which allow the mass 12 to move freely between the boxes. <IMAGE>

Description

96675

DEVICE FOR EQUALIZING ELEVATOR ROPE FORCES

The present invention relates to a device as defined in the preamble of claim 1 for equalizing elevator rope forces.

The service life of the traction sheave ropes depends on the rope tension, the bending diameters of the traction sheave and the sheaves, the shape of the traction sheave and the number of individual folds, which in turn is determined by the number of sheaves and the frequency of use. Once the suspension system, wheel geometry and rope type have been defined, the rope tension remains the dimensioning parameter. The rope tension used thus mainly determines the size and load-bearing capacity of the rope and the entire machinery.

15 In practice, the rope force of a traction sheave elevator is not determined by the load alone and the additional dynamic forces provided by acceleration and braking, but can be significantly increased by the fact that the rope forces are not evenly distributed over 20 different ropes.

The main reason for the uneven distribution of the rope forces is that, due to their large number, the ropes are passed over the same rope pulley: and the diameter differences due to manufacturing defects or different wear in the wheel grooves tend to cause the rope to slip on the wheel. Because the slip due to friction is limited, there is a certain difference in rope force on the ropes before the leveling of the slip «· ·; . ·. through happening. The measured rope force in the above-mentioned practical elevator example has been 30%, even 50% higher than what a uniform distribution would have required.

* - Due to its flexibility, the hoisting rope itself partially compensates for the rope forces. Enhance the equalization is used in addition to a spiral or "... ·· disc springs either side of the body, or both the body side and left-side köysikiinnityksessä 35 curb weight. High lift heights of high-speed lifts can cause large rope force differences despite the expansion springs. It is clear that the resulting rope force differences cause problems and additional rope replacement costs, as a 30% 96675 2 permanent increase in rope force means a halving of the rope lifetime.

In order to solve the above-mentioned problem, i.e. to balance the rope forces, several solutions have been proposed, such as a leveling balance or leveling levers with small amounts of ropes. With large amounts of ropes, the most common way to balance the rope forces is the springs already mentioned above in the rope fastenings.

The publications SU-125 3929 A1, SU-1257048 A1, DE-354 0266 C1 and DE-372 0488 A1 disclose passive equalization of rope forces in which elevator ropes are attached to the piston rods of hydraulic cylinders and the cylinder spaces of which are connected to each other.

15 These known rope force compensators have been very limited in scope. Their rope forces do not have sufficient compensating capacity or their adjustment range is not wide enough, which has led to premature wear of the ropes. In addition to this, they require manual adjustment, in which case the equalization of the rope forces has been practically done by the installer.

An automatic equalization system is disclosed in Finnish patent FI-84803. there, the end of each rope is attached to a separate piston which can move a certain distance in the body of the leveling device on the roof of the car 25. The device includes an electro-hydraulic pump unit with valves that move each: the piston so that the rope forces are automatically kept at the same • »· · · * · *. However, this device becomes complex and cumbersome. Its reliability of many components and potential; . .30 oil spills may also become problematic. In addition, it needs expert service personnel.

It is an object of the present invention to obviate the above-mentioned drawbacks and to provide an inexpensive, reliable and automatic device for actively equalizing the elevator rope forces. The device according to the invention is characterized by what is set forth in the characterizing part of claim 1. Other embodiments of the invention are characterized by what is set forth in the other claims of 96675 3. The advantage of the device according to the invention is e.g. the fact that once installed it requires no adjustment and maintenance and fluid leaks are completely eliminated. The compensating device according to the invention operates reliably and completely automatically, keeping the rope forces of the different ropes equal to each other, whereby the uneven distribution of the rope forces in the parallel ropes is eliminated, as a result of which the effective rope force is lower and the rope life increases. In addition, the device is small in size and simple in construction, and can be mounted in many different places, such as an elevator car gripper frame, a counterweight, or some suitable location in the elevator shaft, depending on the suspension. A further advantage of the device according to the invention is that it has a very high damping capacity due to the viscoelastic medium, so that the vibrations entering the basket along the machine rope can be effectively damped. In addition, the stroke length, spring and damping characteristics of the compensating device can be extensively varied by the design of the pistons and the cylinder-blade space.

In the following, the invention will be described in detail with reference to a preferred embodiment with reference to the accompanying drawings, in which Fig. 1 shows a side view, simplified and cross-sectional structure of an elevator car leveling device, and Fig. 2 shows a leveling device according to Fig. 1 from above. : viewed and simplified.

; .- 30 The leveling device comprises a body part 1 in which cylindrical • · · # bores are made against each piston 4. The first end of the piston rod 5, which is an extension of the piston, has an adapter 13 * 5 ** · for fastening the end of the rope 6. In the case according to Figure 1, the upper surface of the body part 1 has a first sealing cover 7 fitted to each piston rod 5, which guides the piston rod and seals the pressure space under the cover by means of a seal 8 surrounding the piston rod. Attached to one end of the piston rod is a cylindrical piston 4 coaxial with the piston rod, the diameter of which is at least at the above-mentioned attachment point larger than the diameter of the piston rod, whereby the annular shoulder 14 at the first end of the piston which in Fig. 1 has the lower end of the piston 5 passes through the second sealing cover 9 into a depressurized space 3 provided with a protective cover 2 attached to the body 1 of the equalizer. The seal 10 in the sealing cover 9 closes the cylindrical pressure space below. The seals 8 and 10 are plastic rings, the friction of which is only about 1% of the force transmitted through the device, so that the device is able to dampen the vibrations transmitted through the ropes.

The pressure space associated with each piston communicates with the pressure space of the adjacent piston-15 through an intermediate passage 11 so that the viscoelastic mass 12 used as the pressure medium can move to the adjacent piston side and move freely throughout the closed pressure space, the piston pressure spaces forming a congruent vessel with the same pressure . The proportion of the piston-20 arm and the piston in the pressurized space displaces the viscoelastic mass in the pressurized space by its volume. The viscoelastic mass is a high-viscosity fluid, more specifically a silicone elastomer. The viscoelastic mass 12 in the closed pressure space is compressed to a very high pressure when the pressure space is filled, whereby the pistons 25 are pressed into their lowest position in the opposite direction to the direction of the rope forces due to the force on the shoulder 14 at the first end of the piston. In this situation, the ··· · viscoelastic mass is thus in a high-pressure pre-compressed state. The pre-compression pressure is about 600 to 800 bar, while the maximum; .30 the pressure inside the pressure chamber can rise to approx. 3500 bar. When the weight of the car • · · and the load is brought to the lift ropes and further to the pistons. by attaching the elevator ropes 6 to the piston rod adapter 13, ♦ *; ** · the pistons rise close to their upper position due to the compression of the viscoelastic mass. The maximum compressibility is approx.

35 15% of the total volume of the pulp. However, when pre-compressed, 4-8% of the compressibility of the pulp has already been used. The piston 4 has a certain volume and, depending on the pressure ratios, a certain margin of movement, which is dimensioned according to the compensating need required by the elevator. Within these 96675 5 limits, the heights of the pistons, and thus also of the rope ends, can vary in the body part with the forces acting on the pistons and thus also the rope forces acting on the parallel ropes of the elevator being equal. When the rope forces cease to act ha-5, all the pistons swing to their original lowest position.

The movements of the rope ends and thus also the pistons, even in high-speed elevators, take place at a reasonable speed so that the viscoelastic mass has time to move well according to the leveling needs.

10 Pulp flow rates are only a fraction of what is used in similar buffer applications. The desired flexibility and damping properties are achieved with the design of the pressure space and the pistons and their intermediate spaces, as well as with the volume and diameter ratios. The final adaptation to the case of each elevator and its masses 15 can, if desired, be carried out by adjusting the pressure of the medium to a suitable value.

It will be clear to a person skilled in the art that the invention is not limited exclusively to the example given above, but can be varied within the scope of the claims set out below. Thus, the position of the leveling device is not tied exclusively to the elevator car and the counterweight, but may vary depending on the suspension. A preferred embodiment can also be implemented in such a way that the leveling device is arranged at both ends of the elevator ropes. Unlike a liquid, the pressure 25 medium is always a viscoelastic pre-pressurized mass, but its properties and the pressure level s used can be varied within wide limits to optimize the entire system.

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Claims (4)

1. A device for equalizing the link forces in parallel lift carriers (6) which causes a lift basket and its counterweight to move in relation to each other, to which the equalizing device belongs to a body part (1) with a piston (4) movable relative to the body part. each support line (6), characterized in that in the body of the equalizing device there is a closed pressure chamber provided with pressurized elastomeric mass (12) acting on each piston (4). Device according to claim 1, characterized in that the elastomeric mass (12) is a highly viscous, viscoelastic mass. Device according to claim 1 or 2, characterized in that each piston (4) has a shoulder (14) which is so located in the closed pressure chamber of the device that the pressurized viscoelastic mass (12) exerts a compressive force on the shoulder which presses the pistons (4). ) in a direction opposite to that in which the link forces act. Device according to claim 1, 2 or 3, characterized in that each piston (4) moves in the same common pressure chamber, where the pistons are enclosed in boxes which are interconnected with intermediate channels (11) which allow it to ···. pressurized mass (12) to move freely from one box to another, whereby it acts on each piston with equal force, regardless of the position of the piston within its working range. t · I 1 · I »« I