Patent Application
20180022579
This application is a continuation of PCT International Application No. PCT/FI2015/050286 which has an International filing date of Apr. 27, 2015, the entire contents of which are incorporated herein by reference.
The object of the present invention is an arrangement as defined in the preamble of claim 1 for adjusting the tautness of a traction member of an elevator.
In some elevator arrangements the suspension members, such as the suspension ropes, of an elevator car and the traction members of the elevator car are separate from each other. Often, in this case, for practical reasons the hoisting machine is disposed on the base of the elevator hoistway, or close to the bottom part of the elevator hoistway, and e.g. toothed belts, or other belts suited to the purpose, can function as traction members, which are fitted below the elevator car and one or more compensating weights or counterweights. In this type of elevator the stresses exerted on the suspension members and on the traction members change as, among other things, the load in the elevator car changes. From the viewpoint of the proper functioning of the elevator, it is desirable for the distribution of the stresses of the suspension members and traction members to remain suitable and for the traction members to remain suitably taut. Over time elongations easily occur in traction members, especially if the travel height of the elevator is large, in which case the correct tautness is very important. Also changes in temperature affect the length of traction members. Changes in the length of traction members must be compensated in some way in order for the traction members to remain at a suitable tautness. Traction members may not be too loose nor may they be too taut because otherwise they, or other parts of the elevator, can become damaged. An apparatus or arrangement suited to the purpose is therefore needed for adjusting the tautness of the traction members of an elevator.
According to what is known in the art, the tautness of the traction members of elevators is adjusted by means of, inter alia, an arrangement functioning with an electric motor. The adjustment of the tautness can be made e.g. at certain intervals of time or on the basis of the measuring data of a separate sensor. A problem with making an adjustment at certain intervals of time is that the traction members can be at the wrong tautness for a long time between adjustments. An arrangement based on a tension sensor solves this problem, but is for its part a more complex and more expensive solution. A drawback in performing the tensioning of the traction members with an electric motor is also that this requires its own electricity supply, along with the cables and protections associated with it. The apparatus comprised in such an arrangement can also be rather large in size and heavy in weight, and if it is disposed on the elevator car it will increase the mass of the car.
U.S. Pat. No. 5,437,347 presents a solution by means of which the tautness of the traction members of an elevator is adjusted in an elevator wherein the traction members and suspension members are separate from each other. In this solution a rocker means is fixed to the counterweight or to the elevator car, to which rocker means both the suspension members and the traction members are fixed at one of their ends. The rocker means is hinged to the counterweight or to the elevator car, and the suspension members and traction members are fixed to the rocker means at different distances from its fulcrum. In this solution the counterweight of the elevator is used for maintaining the tension of the traction members and for compensating changes in their length. The solution has the problem, however, that its operating range is not very large, owing to which it is not necessarily able the keep the traction members sufficiently taut if the fluctuation range of the length of the traction members is, e.g. as a result of elongation, large. The adjustment margin for compensating elongation is thus too small in the solution described in the US patent. This can be a problem particularly in elevators with large travel heights, in which the elongations are long.
The aim of the present invention is to eliminate the aforementioned drawbacks and achieve an inexpensive and easy-to-implement arrangement in an elevator, in which the suspension members and the traction members are separate from each other, and in which arrangement the compensation of the elongation of the traction members and suspension members can be arranged to be automatic in such a way that the elevator car is all the time in balance regardless of the load or of different elongation of the suspension members and traction members, and the traction members are at a suitable tautness. The arrangement according to the invention is characterized by what is disclosed in the characterization part of claim 1. Other embodiments of the invention are characterized by what is disclosed in the other claims.
Some inventive embodiments are also discussed in the descriptive section of the present application. The inventive content of the application can also be defined differently than in the claims presented below. 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 attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts. Likewise the different details presented in connection with each embodiment can also be applied in other embodiments. In addition it can be stated that at least some of the subordinate claims can, in at least some situations, be deemed to be inventive in their own right.
One advantage of the solution according to the invention is that by means of it the traction members of an elevator can be kept at a suitable tautness automatically in an elevator in which the traction members are separated from the suspension members. Another advantage of the solution is its large operating range, owing to which even large fluctuations in the length of the traction members can be compensated. A further advantage of the solution is that it is simple and inexpensive to implement.
In the following, the invention will be described in more detail by the aid of some examples of its embodiment with reference to the simplified and diagrammatic drawings attached, wherein
The elevator arrangement made possible by the arrangement according to the invention comprises at least an elevator car 1 adapted to move reciprocally in an elevator hoistway and at least one or more compensating weights 2, which are for their part connected to support the elevator car 1 by means of suspension members 4, such as belts or ropes, and also by means of diverting pulleys 6 and 7 e.g. mounted on bearings in the top part of the elevator hoistway. Whenever hereinafter only one compensating weight is mentioned, the simultaneous meaning intended is one or more compensating weights, or alternatively one or more counterweights. In addition, the arrangement according to the invention comprises a hoisting machine 3 that is provided with at least one traction sheave 3a, or with a corresponding means, and is in a machine station disposed in the bottom part of the elevator hoistway, and at least one or more traction members 5, such as a belt or rope, which is adapted to transmit the rotational movement of the traction sheave 3a into linear movement of the elevator car 1 and of the compensating weight 2. Whenever hereinafter only one traction member 5 is mentioned, the simultaneous meaning intended is one or more parallel traction members, such as one or more toothed belts, V-belts, flat transmission belts or traction ropes.
The traction member 5 in the arrangement according to the invention is separated from the suspension members 4, and the traction member 5 together with the suspension members 4 and elevator car 1 and compensating weight 2 form an essentially closed loop in which the tautness of at least the traction member 5 is monitored and the tautness is kept at the desired level independently of different loads and elongations. Characteristic to the invention, and common to all the different embodiments of the invention, is that the compensating weight 2 is connected e.g. by means of a traction member 5 provided with essentially spring tensioning or constant-force tensioning to the elevator car 1 via the hoisting machine 3.
The traction member 5 is fixed at its first end to a tensioning means 9 that is on the bottom part of the elevator car 1 and provides a constant tensioning force, from where the traction member 5 is led downwards to the hoisting machine 3. The traction member 5 is arranged to pass around the bottom of the traction sheave 3a of the hoisting machine 3, after which over the first diverting pulley 10 and onwards under the second diverting pulley 11, from where upwards to the tension control means 8, to which the traction member 5 is fixed at its second end. The traction member 5 is e.g. a toothed belt, in which case on the traction sheave 3a is toothing that matches the toothing of the traction member 5. The compensating weight 2 is fixed at its lifting point to the tension control means 8 by the aid of its own fixing means 2a.
The tension control means 8 is a means that functions as a lever, having e.g. a bar-shaped or rod-shaped frame part 8a, the traction member 5 of the elevator being fixed at its second end to the fixing point 13 at the first end of said frame part via a fixing means 5a, and the compensating weight 2 being fixed at its lifting point to the fixing point 14 at the second end of said frame part via a fixing means 2a. The suspension member 4 is fixed at its second end via a fixing means 4a to a suitable fixing point 15 between the fixing points 13 and 14, to between the first and second end of the frame part 8a of the tension control means 8. The fixing means 2a, 4a and 5a are fixed to the fixing points 13, 14 and 15 on the frame part 8a, e.g. via hinges or shaft extensions suited to the purpose.
The fixing point 15 of the fixing means 4a of the suspension member 4 between the fixing points 13 and 14 is selected in such a way that between the suspension member 4 and the traction member 5 the correct lever ratio A/B is obtained, in which lever ratio the length of the lever arm A is the distance of the fixing point 13 of the traction member 5 of the elevator from the fixing point 14 of the compensating weight 2, and the length of the lever arm B is the distance of the fixing point 15 of the suspension member 4 of the elevator from the fixing point 14 of the compensating weight 2. This lever ratio A/B acts directly on the magnitude of the forces exerted on the suspension member 4 and on the traction member 5.
The detachment points 13a and 14a of the traction member 5 presented in
In the arrangement according to the invention the traction member 5 is fixed at one of its ends, e.g. at the end on the elevator car 1 side, with a fixing means 9 providing a spring force or a constant-tensioning force in such a way that the traction member 5 always remains sufficiently taut on the rim of the traction sheave 3a and that when the suspension members 4 of the elevator car 1 stretch and loosen, the fixing means 9 removes the elongation produced via the traction member 5 and the suspension of the suspension members 4 compensates the elongation by the aid of the tension control means 8 by keeping the elevator car 1 always on an even bearing.
The tensioning means 9 can also be disposed elsewhere than on the bottom part of the elevator car 1, depending on the suspension ratio. For example, when the traction ratio of the elevator car 1 is 2:1, below the elevator car 1 is e.g. a diverting pulley, and the traction member 5 is led from the traction sheave 3a over the top of said diverting pulley back downwards either to the floor of the elevator hoistway or to the elevator machine station, to which the first end of the traction member 5 is fixed via a tensioning means 9 providing a constant tensioning force.
It should also be noted that the different solutions presented above can be inventive features together with one or more other features of the invention.
Characteristic to the solution according to the invention is, inter alia, that tensioning of the traction member 5 is arranged on both sides of the traction sheave 3a, i.e. at the first end of the traction member 5 on the elevator car 1 side as well as at the second end of the traction member 5 on the compensating weight 2 side. At the first end of the traction member 5 in connection with the elevator car 1 is a tensioning means 9 providing a constant tensioning force, and at the second end of the traction member 5 in connection with the compensating weight 2 is a tension control means 8 enabling an adjustable lever ratio A/B.
The size of the tension control means 8, e.g. the length and position of the frame part 8a or the diameters of the diverting pulleys 16, 17, is selected in such a way that, in addition to achieving the desired lever ratio based on the masses of the compensating weight 2, elevator car 1 and load, also the traction member 5 can be disposed in a suitable location beside the compensating weight 2 on a line on which the traction member 5 is guided to travel to the diverting pulley 11 past the compensating weight 2. In this case the point 13, 13a connected to the tension control means 8 of the traction member 5 is, as viewed from above, disposed outside the area of travel formed by the cross-section of the compensating weight 2. This solution allows easier variation of the layout of the elevator.
In the solution according to the invention the tensioning forces exerted on the suspension members 4 and on the traction member 5 are smaller than with tensioning systems according to prior art and, in addition, elongations are smaller and the lever ratio automatically compensates elongations in the suspension members 4 and traction member 5. This is based on the fact that in the structure according to the invention, a force that is larger than that which comes from the combination of the lever ratio and gravity is not produced in the suspension members 4 and traction member 5. Tensioning systems that are known in the art always have more force in order to function sufficiently well.
It is obvious to the person skilled in the art that the invention is not limited solely to the examples described above, but that it may be varied within the scope of the claims presented below. Thus, for example, the suspension solutions and the structural solutions for the tension control means can also be different to what is presented above.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/FI2015/050286 | Apr 2015 | US |
| Child | 15720269 | US |
