Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes linking support cable in drive-means
Reexamination Certificate
1999-02-10
2001-02-27
Olszewski, Robert P. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes linking support cable in drive-means
C187S256000, C187S264000, C187S266000
Reexamination Certificate
active
06193017
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to elevators in general, and in particular to a traction-sheave elevator which has no mechanical counterweight running with it.
2. Description of the Invention
The most diverse types of elevators for the conveyance of passengers and/or loads are known and are used extensively. Elevators can generally be divided into three classes: traction-sheave or rope elevators, hydraulic elevators, and special solutions, such as, for example, rack, chain or spindle-gearing elevators. Furthermore, combined forms are also known, such as, for example, a hydraulic rope elevator, which is actuated via a piston-cylinder arrangement and interposed ropes.
In the case of traction-sheave elevators or rope elevators, a load-conveying means, in particular an elevator car, is suspended on a rope which is run over a so-called traction sheave. The traction sheave is motor-driven in order to move the car up or down. A counterweight, which as a rule is heavier than the load-conveying means, is normally arranged on the other end of the carrying means or rope. In order to set the load-conveying means and the counterweight in motion, there must be sufficient friction between the carrying rope and the traction sheave. The rope friction required for the drive is determined, on the one hand, by the configuration of the traction sheave, the rope and the number of ropes and, on the other hand, by the applied pressure of the rope against the traction sheave, this applied pressure in turn depending on the rope tension and thus on the weight of the load-conveying means and on the counterweight. The counterweight is normally designed in such a way that it corresponds approximately to the weight of the load-conveying means plus half the maximum useful load. Common counterweights are made of steel, reinforced concrete or the like and require a very large space in the elevator shaft on the one hand and robust guide rails for the spatial fixing on the other hand. This spatial guidance in the elevator shaft is costly and requires considerable material. In particular, it is often necessary to provide speed limiters and catching devices for the counterweight, which entail further constructional measures with requisite space, costs and material. Furthermore, the response behavior of the elevator is greatly impaired by the combined high moment of inertia of the load-conveying means and the counterweight.
During the modernization of existing elevator installations or during the integration of new elevators in existing buildings, in particular old buildings, apart from government conditions there is also often only a restricted space available.
A traction-sheave elevator without counterweight is disclosed by German Patent 105 613. In the traction-sheave elevator of the generic type, a manually adjustable tensioning device acts on a section of a carrying means. The tension force introduced into the carrying means is distributed uniformly to the two traction sheaves via deflection pulleys and a further carrying means closed upon itself.
The journal Liftreport, No. 2, 1990, pages 6-8 discloses a traction-sheave elevator which has no counterweight and in which a traction sheave is provided which, in combination with the driving gear, is arranged so as to hang as tension weight at the bottom in the ropes.
The object of the invention is to develop a traction-sheave elevator of the generic type without counterweight and having two traction sheaves in such a way that a high degree of safety in operation, in particular a high traction capacity, is ensured, while the elevator is to have dimensions which are as compact as possible, a reduced number of parts and reduced manufacturing and installation costs.
SUMMARY OF THE INVENTION
In the traction-sheave elevator according to the invention, the tensioning device is self-regulating, i.e. self-acting or self-adjusting in the event of any elongation of the carrying means. Furthermore, the angle of wrap of the carrying means relative to each traction sheave, according to the invention, is greater than 180°, i.e. the angle of wrap less any integral multiple of 360° is greater than 180°. Finally, the traction-sheave elevator according to the invention has at least one braking device for at least one of the traction sheaves in order to further increase the safety of the elevator in operation. Since the tensioning device acts on the carrying means after the latter runs off from the second traction sheave, the force introduced acts directly as applied pressure of the carrying means relative to the traction sheave, so that a lower stress overall on the elevator shaft or the building to be equipped can be achieved.
The traction-sheave elevator without counterweight, which is guided in an elevator shaft, preferably has a load-conveying means, a flexible carrying means, at least two motor-driven traction sheaves, and a tensioning device, which introduces a requisite tension into the carrying means. In particular, the load-conveying means is an elevator car and the flexible carrying means are, in particular, ropes, which are wound one after the other around the two traction sheaves. Due to the provision of two traction sheaves in combination with the carrying-means-tensioning device connected downstream, the static friction produced between the carrying means and the traction sheaves is greater than the force due to the weight of the load-conveying means at maximum loading, as a result of which the use of a voluminous and heavy counterweight may be dispensed with, in which case the admissible loading limits of the carrying means and of the traction sheave, in particular the traction-sheave groove, are not exceeded. By the omission of the counterweight, the risk of an elevator suddenly moving upward is advantageously eliminated, this risk occurring in conventional traction-sheave elevators, in particular due to the fact that the counterweight is normally designed to be heavier than the load-conveying means.
The elevator according to the invention permits a very compact type of construction, in which case, in particular, all the components may be accommodated in the elevator shaft itself.
The requisite rope tension may be provided via a tensioning device provided at one rope end, e.g. a hydraulic or pneumatic tensioning device, which may be installed, for example, at the bottom of the elevator shaft. However, the requisite tension of the carrying means is in particular preferably achieved via a deflection sheave to which force is applied, in which case the deflection sheave to which force is applied may likewise serve to increase the angle of wrap of the carrying means around the traction sheaves.
In a preferred refinement of the traction-sheave elevator according to the invention, in each case an end of the carrying means is connected to the load-conveying means. Therefore each section of the carrying means is moved at the same speed as the load-conveying means. The fastening of the ends of the carrying means is preferably designed in one piece for both ends, i.e. the carrying means in particular preferably forms a closed loop. Alternatively, separate attachment locations may also be provided for the two ends of the carrying means, in which case these attachment locations may in particular be displaced from one another in order to compensate for a displaced center of gravity if need be. In the case of a displaced fastening of the ends of the carrying means on the load-conveying means, care should be taken during the design to ensure that that end of the carrying means which continues upward is attached essentially above the center of gravity of the load-conveying means.
Alternatively, it is preferred that in each case an end of the carrying means be fastened to the bottom of the elevator shaft and to the top end of the elevator shaft, as a result of which a stationary carrying means is formed. This arrangement is especially advantageous, since less material is required for the carrying means. Furthermore, with this arrangement, t
Blain Hydraulics GmbH
Casella Anthony J.
Chin Paul T.
Hespos Gerald E.
Olszewski Robert P.
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