DESCRIPTION

The present invention relates to the field of elevators. The invention relates in particular to an improvement of a suspension and safety stop system for the cabin of an elevator of the self-supporting type without counterweight.

It is known that an elevator needs to be equipped with a safety brake suitable to stop the cabin in the event of overspeed or in any case of malfunction. Said safety system is commonly known as "parachute" brake. In the event of intervention of said parachute brake the cabin is halted in a virtually instantaneous manner and the kinetic energy of the moving mass is released to the guide structure, causing a remarkable stress and/or strong vibrations. Moreover the onboard passengers are affected by the sharp stop.

The object of the present invention is to solve this problem. The object in particular is to devise a system for avoiding that the intervention of the safety brake causes sharp stresses and/or vibrations on the cabin.

This object is achieved with an elevator without counterweight according to the attached independent claim 1. Some preferred embodiments are described in the dependent claims.

In a preferred embodiment the cabin is suspended by a cable or belt by means of a unit known as carriage. Said carriage essentially comprises a fixed assembly which is firmly attached to the cabin and an assembly which is elastically suspended to the fixed assembly, not being directly linked to the cabin. At least one respective pulley or a respective set of pulleys are associated with said fixed assembly and with said suspended assembly of the carriage. The suspension means is wound around said pulleys or sets of pulleys of the fixed assembly and of the suspended assembly. The suspension means can be represented by one or more cables or belts. In a preferred embodiment said suspension means is represented by a belt.

The suspended assembly of the carriage is elastically connected to the fixed assembly by means of at least one spring or equivalent elastic means. In an embodiment given as an example of the invention, the two assemblies are connected by sliding pins contrasted by respective coaxial springs.

According to the invention at least one shock-absorbing system is provided between said fixed assembly and said suspended assembly of the carriage. The sharp stop of the cabin, following an intervention of the parachute brake, tends to move the fixed assembly and the mobile assembly of the carriage away or towards each other, depending on the brake being operated while the cabin is descending or ascending, respectively. The shock-absorbing system has a dampening function which makes the stopping of the cabin less sharp and prevents vibrations which are unpleasant for the users or which could be dangerous for the integrity of the suspension and guide system, causing permanent damage to vital parts of the elevator.

Further advantages of the invention are: the compactness of the solution, the constructional simplicity and the reduced installation time. At each intervention of the parachute brake the shock-absorbing system absorbs the inertia and therefore the kinetic energy of the moving mass, protecting the constructional parts of the elevator. Thanks to the invention the stop caused by intervention of the parachute brake is less sharp and more tolerable by passengers, if any, on board the cabin.

These and other advantages of the invention will be made clearer herein below, with the aid of the description of some non-limiting preferred embodiments, in which:

Fig. 1 shows schematically an elevator without counterweight, according to a preferred embodiment of the invention;

Fig. 2 shows the detail "B" of the carriage of the elevator of Fig. 1 , in a lateral view;

Fig. 3 shows a front view of the carriage of Fig. 2;

Figs. 4 and 5 show a variant of the invention with double shock absorber.

Referring to the drawings, an elevator of the self-supporting type without counterweight is shown, which comprises a cabin 1 guided by a load-bearing structure represented essentially by lateral guides 2 connected by upper and lower crosspieces 2A, 2B. The cabin 1 is suspended by a belt 3, wound around pulleys 4. More particularly the cabin 1 is suspended by a carriage 5 which supports some of the pulleys around which the belt 3 is wound.

The pulleys 4 are positioned in fixed and mobile sets. Fixed sets of pulleys are integral with the load-bearing structure and mobile sets are associated with the carriage 5, following the movement of the cabin 1. In the example two sets of fixed pulleys are associated respectively with the upper and lower crosspieces 2A, 2B and two sets of mobile pulleys are associated with the carriage 5.

The pulleys of each set are preferably coplanar in a plane parallel to the direction of the movement of the cabin. More preferably each set comprises a plurality of pulleys of different diameter and aligned by decreasing size, from a pulley of greater diameter to a pulley of smaller diameter, as represented in the drawings and in particular in Figs. 3 and 5.

The belt 3 is wound around the pulleys 4, between two fixed end points. A motor (not shown) drives a drive pulley, for example one of the pulleys 4 of a fixed set integral with the crosspiece 2A or 2B.

The carriage 5, according to one of the embodiments of the invention, is shown in greater detail in Figs. 2 and 3. The carriage 5 essentially comprises an assembly 5a associated with the cabin 1 and an assembly 5b which is elastically suspended to the assembly 5a, not being directly anchored to the cabin itself. Referring more specifically to Fig. 2, the fixed assembly 5a comprises a plate 6, attached to the rear wall of the cabin 1 . Said plate 6 carries a first set of three coplanar pulleys 4 of decreasing diameter, as schematised in Fig. 3. The suspended assembly comprises a plate 7 which carries another set of three coplanar pulleys 4 of decreasing diameter. The plates 6 and 7 are connected by two pins 8A each contrasted by a coaxial spring 8, which is preloaded with a predetermined compression. In this way the system maintains an adequate tension of the belt 3 and acts as a compensation system. In particular the spring 8 opposes the plates 6 and 7 from moving away each other. According to the invention a shock-absorbing system connects the two assemblies 5a and 5b each other. In the example of Figs. 2 and 3 a shock- absorbing system 20 connects the fixed plate 6 to the suspended plate 7. The shock-absorbing system 20 reacts with a force proportional to the relative speed which exists between the two plates 6 and 7, with the effect of dampening the vibrations of the springs 8.

In Figs. 2 and 3 said shock-absorbing system 20 is made with a cylinder 21 integral with the assembly 5b, and a piston 22 sliding in the cylinder 21 and having an end integral with the assembly 5a. The travel of the piston 22 in the cylinder 21 is contrasted by an appropriate means (oil, gas or other) which provides the dampening effect.

Embodiments of the invention with more than one shock-absorbing system are possible. In another embodiment of the invention, shown in Figs. 4 and 5, two shock absorbers 20 are provided at the opposite sides of the carriage 5. This configuration with double shock absorber is further advantageous because it provides a more accurate guide of the assembly 5b compared to the fixed assembly 5a and avoids the generation of a bending moment.