Arrangement of brake onto lift deflection pulley and improved rope wrappings

The present invention relates to a lift provided with a brake onto the deflection pulley and rope wrapping around the deflection pulley in accordance with the Improved Single Wrap (ISW) diagram and Improved Double Wrap (IDW) diagram.

Among the several expedients that are attempted to be adopted in the development of new solutions for the manufacturing of lifts that can be suitable with the new market requirements, arise those ones directed to maximize the lift cage size, by reducing the overall dimensions of the other devices to be installed in the lift shaft. Among these, even the lift motor, a bulky element per se, and generally having a brake, which adds further bulk, had been studied in order to save the available space, especially in pre-existent plants and the lift shaft of which would be result hardly or expensively modifiable in order to increase the cage space even in favour of a wider accessibility, extended to handicapped users.

The solutions allowing for reducing the number of ropes, with subsequent reduction of the pulley size, and those allowing to lighten hung masses, particularly those of the cage and counterweight, both of them allow for obtaining beneficial effects in that sense.

On the other hand, there could be the disadvantage, in most cases proposed on the market, that a relevant reduction of the hung masses leads to problems concerning the need of providing a suitable traction of the ropes on the traction pulley. This requires in turn adoption of section of the traction pulley races suitable to assure the traction, even in the worst conditions, of braking during descent with overloading on the cage, but it implies a higher stress of the ropes and then a lower life, therefore, in order to respect the safety coefficients imposed by the standards, it needs to increase the number of the ropes, increasing

consequently the pulley sizes and this minimizing the effect of the advantages aimed to be

obtained.

It is also to be envisioned that the braking torque during full load is averagely 50% greater than the drive torque of the lift, this implies that a dimensioned lift, as well as ropes and frictions, for the only drive, makes the ropes skidding on the pulleys during braking at full load. In order to avoid these important disadvantages, and nevertheless maximize the cage spaces, herein there is proposed an innovative solution that provides the adoption of a combination of a brake on the deflecting pulley and a wrapping of the ropes with improved friction, such that greater cage spaces can be obtained (reducing the brake dimensions on the drive machine or even removing it), and also a safety braking, significantly lacking in rope skidding. The wrapping of the ropes with improved friction has a wrapping angle around the deflecting pulley that can easily reach and even be 50% over the maximum wrapping angle normally feasible on the traction pulley. The installation of a braking structure on the deflecting pulley allows by this improved wrapping for assuring the necessary traction of the ropes on the braking pulley without adopting race configurations that produce in the ropes a stress greater than the one necessary to transmit from the traction pulley the drive torque of the lift, that, as above mentioned, is averagely 50% lower than the braking torque at overload.

The advantages deriving from the adoption of the present invention regard the possibility of removing the braking device normally installed on the drive machine of a lift, or reducing the efficiency and thus the dimensions, especially in the case of a lift without machine room, for example dividing the braking between two brakes, one on the traction pulley, the other on the deflecting pulley, thus less loading, in terms of dimensions, on the motor unit, bulky per se, in order to save the spaces.

Moreover, while considering the pair of pulleys for traction and deflecting, the entry and the exit of the ropes in cases of normal rope wrapping are placed the former on one pulley and the latter on the other pulley, and the rope bulk does not allow for embedding the motor

in a niche outside the lift shaft, in order to better use the cage path. Vice versa the ISW and IDW wrappings have both the entry and exit of the ropes on the deflecting pulley, therefore the bulk of the cables allows also for embed the motor and the corresponding pulley outside the lift shaft, with the just seen corresponding advantages. By realizing a deflecting pulley with a wrapping angle of the ropes, that as known is proportional to friction, greater than the one obtainable on the traction pulley of the machine, on this deflecting pulley a braking device can be set up and a suitable braking can be obtained on the deflecting pulley, without skidding, even in the braking conditions with the cage at full load, adopting a configuration of the rope races that allows a longer life of the suspension rope or, alternatively, a reduction of the number of the ropes, with reduction of the bulk of the apparatuses in the lift shaft, with advantage for the dimensions obtainable for the cage.

The details of the expedients previously disclosed can be verified in the invention hereinafter described in an exemplificative form not limiting, in some of the advantageous possible configurations, even with the aid of the following drawings, in which: Fig. 1 shows a wrapping configuration called Improved Single Wrap (ISW) and a brake on the deflecting pulley;

Fig. 2 shows a wrapping configuration called Improved Double Wrap (IDW) and a brake on the deflecting pulley; and

Fig. 3 is a perspective view of the dowelling of the pulley races and the shape of the notch housing them object of an embodiment of the present invention.

Referring to fig. 1, there is now described the rope configuration called Improved

Single Wrap (ISW), consisting in the rope wrapping around the pulley in a range of angle approximatively comprised between 200° and 330°, so as increase the friction (that as known is also proportional to the wrapping angle of the ropes around the pulleys) and with exit and entry of the ropes placed on the deflecting pulley, so as, as just said, to can place the motor

and the corresponding pulley in a niche accessible from outside or inside of the lift shaft, without bulks in it.

The rope section 5b coming from the upper side of the traction pulley 2 enters in the race 6 of the upper side of the deflecting pulley 3, runs over it along an arc of about three- quarters of circle and goes vertically with the vertical section of the rope 5, towards the cage of the lift. In order to avoid the section 5b of the rope and the vertical section 5 that goes from the deflecting pulley towards the cage from touching one another, the rotation axes of the pulleys 2 and 3 are biased one in respect of the other for about 3° - 4 °, or in respect of a projection of the axes on a vertical plane, or in respect of a projection of the axes on a horizontal plane, such that the vertical section of the rope 5 is shifted in respect of the horizontal section 5b of the rope enough to avoid interference.

The section of the rope 7 coming from the lower side of the traction pulley is inserted in the lower portion of the race 8 of the deflecting pulley 2, runs in the same for about a quarter of circle and goes vertically 7a towards the counterweight. This wrapping solution of the ropes allows the rotation direction of the deflecting pulley 2 and traction pulley 3 fof-bβiαg the same. It allows moreover the wrapping direction of the ropes passing on such pulleys for being also the same, preserving the contact side of the rope and thus reducing the rope stress. Such a characteristic supports a longer life of the ropes, because the stress of the traction is applied on only one side, without bending the rope in one direction and the in the opposite one.

It finally allows the wrapping angle of the rope around the deflecting pulley 3 for being greater than the wrapping angle of the rope around the traction pulley 3 and being widely

greater than 180°.

It is to be envisioned the fact that what said about a rope can be applied on a set of

ropes following the same path.

Referring now to fig. 2, there is now disclosed the rope configuration called Improved Double Wrap (IDW), consisting in the wrapping of the ropes around the pulley in a range of angles approximatively comprised between 380° and 510° and with entry and exit of the ropes placed on the deflecting pulley, with the advantages of housing motor just seen in the case of ISW. The presence of the braking device 4 on the deflecting pulley 3, in place of or supporting the one normally installed on the traction machine 1, thanks to greater traction angle on the deflecting pulley 3 allows for obtaining on such pulley the necessary traction to assure the absence of excessive skidding of the ropes during braking at full load, keeping, as disclosed, a configuration of the rope races that generate lower stress on the ropes and therefore can allow a longer life of the same ropes or possible reduction of the number of the ropes, under the same life expectations.

Referring again to fig. 2, the rope 15a coming from the upper side of the traction pulley 2 is inserted in the race 6 of the upper side of the deflecting pulley 3, runs over it along an about 180° arc, then goes towards the traction pulley 2, is inserted in the lower portion of the race 10, performs a substantially semicircular arc and goes again towards the upper side of the deflecting pulley 3, is inserted in the race 11, performs an almost three-quarters of circle and goes in vertical direction 15, towards the lift cage. In order to avoid the horizontal section 15b of the rope that is inserted in the race of the deflecting pulley and the vertical section 15 that from the deflecting pulley goes to the cage from touching each other, the rotation axes of the deflecting and traction pulleys are, similarly to the ISW case, biased of 3° - 4° one in respect of the other, such that the vertical section of the rope is shifted in respect of the horizontal section of the rope enough to avoid interference.

The section 17 of the rope coming from the lower portion of the traction pulley is inserted in the lower portion of the race 8 of the deflecting pulley adjacent to the race 6 in which the rope coming from the upper branch has been just inserted. It runs in the same for

about a quarter of circle and goes in the vertical direction 17a towards the counterweight. This wrapping solution of the ropes allows the rotation direction of the deflecting and traction pulleys for being the same, with the advantages above disclosed.

It also allows the wrapping angle of the rope around the deflecting pulley for being greater of the wrapping angle of the rope on the traction pulley and being widely greater than 360°.

The presence of the braking device 4 on the deflecting pulley 3, in place of or supporting the one normally installed on the traction machine 2, thanks to a greater traction angle on the deflecting pulley, due to the presence of the IDW wrapping, allows for obtaining on such pulley the necessary traction to assure the absence of excessive rope skidding or a possible reduction of the number of the same, under the same life expectations.

Similarly to what said about ISW, it is to be envisioned that what said about a rope can be applied on a set of ropes that follow an similar path.

The reciprocal biasing mode of the rotation planes of the pulleys 2 and 3 and the insertion angle of the ropes into the pulleys are exemplificative and not limiting. Other similar displacements can be adopted in the application field of the proposed solution.

With reference to fig. 3 there is shown a dowelling arc 301 of a pulley 305, of which simply only one race is herein illustrated, sectioned and with the dowelling arc 301 inserted into the circular race 307 with an undercut 306. The dowelling provides moreover a section with side wings 302, object of which is to provide a protection and a side guide to the rope.

The possibility to manufacture the dowelling of the pulleys by dowelling arcs 301 detachable one from another allows an easier replacement by segments, by rotating the pulley on which they are installed around an arc enough to the easy replacement, without removing the ropes in order to replace the whole circular dowel. This is a considerable advantage in terms of comfort and cost, considering the machine stop time for the replacement of the worn races.

Once worn by the friction the bottom filleted of the dowel where the rope preferably lays, the rope touches the metallic surface of the race, but partly it is longer laid on the dowel tang inserted in the undercut 306.

Still with reference to fig. 3, the function of the undercut 306 is either to provide afo system of assembly and locking in position for the dowelling arcs 301, or to, in case of wear of the same, assure a certain friction between the undercut 306 and the metallic cables so as to allow to move the lift for a short time, even though not assuring a cable life comparable to the one resulting in presence of dowelling, due to the wear of the same during the contact with the undercut 306, which provides for enough friction for handling for short time, due to the excessive wear of the ropes in these conditions.