The present invention relates to a door lifting system, more particularly a lifting system using an improved device for its movement.

The inventive lifting system is particularly used to operate doors for garages, warehouses and the like, where sectional overhead doors are movably supported in suitable guides. It is known that the door can slide on a single generally vertical plane or on non parallel planes, like in the sectional doors. In order to avoid that the door opening and closure operations, when carried out either manually by the user or by motors, require a considerable power, elastic systems are used, applying a suitable load on the door through a cable connection, so as to balance its weight.

Most known lifting mechanisms for doors or windows are provided with a balancing system. For instance, these devices comprise a shaft provided with a pair of drums, each drum being fixed at one shaft end, and two pairs of plates fixed on the shaft in symmetric positions in respect of its central section.

In the space between each pair of plates, a torsional spring is wound on the shaft, the ends of the spring being fixed to the corresponding plates. The balancing device is mounted at the door lintel, through support fixed to the wall, allowing free rotation of the shaft on its axis. Around each drum cables are wound, one end of the cable being connected to the door or to a panel of the door, generally the base or lowest one. Obviously the winding direction of the springs is chosen so as to oppose or balance the door weight, thus making its opening and closure easier.

Several examples of different applications of balancing devices are known from the prior art. Document US 2782456 discloses a spring balancing system for a window sash allowing to balance the window heavy weight during its operation. To keep the window fixed at any desired position, the balancing mechanism provides for a constant traction obtained through a spiral cable, whose traction is kept constant through a complex system balancing the door weight through further springs, gears and other devices opposing the natural trend of the spring to get released when lifting the window.

Other prior art preloaded balancing systems are disclosed in the documents US 4569490 and US 2679659, also related to systems balancing the weight of a window sash during the lifting, lowering and regulating operations. The present invention relates to a lifting mechanism for sectional devices used in doors or windows, such as sectional overhead doors for garages or lockups. More particularly, the device of the invention was particularly designed for lifting sectional doors and not for balancing movement of window or door sashes. Unlike the known balancing devices, which are complex and bulky systems difficult to be installed, the present invention exploits the natural relief trend of the spring during the lifting operation, allowing to lift the sectional door with a simpler device, without requiring the above mentioned further balancing devices. This inventive device is also easier to be manufactured and installed, being less cumbersome and more versatile to be positioned. In other words, the device of the present invention may be mounted either close or remote to the door lifting position, in view of the possibility to adjust the length of the lifting cables to the room configuration, as it will be better explained hereinafter in the detailed description of the device.

It is to be noted that in the field of door lifting mechanisms, several systems of regulating the spring preload, fixing the spring to the plates and the plates to the support and/or shaft were developed, but all these systems have a common drawback, i.e. the considerable bulk of the whole device. This involves a great installation difficulty due not only to the weight of the device that must be mounted at a noticeable height from the floor, but also to the need of adjusting the preload of springs or similar elastic systems.

It has also to be pointed out that, when handling fireproof, reinforced or like doors, the weight of the various components of the lifting system and more particularly of the balancing devices is still bigger, consequently with further installation difficulties.

Moreover the above mentioned usual configuration of the elastic system, more particularly during the preload calibration, exposes the installer to noticeable risks of accident: in case of possible fault, the components under the applied heavy loads may easily hit the installer with obvious serious consequences.

At last, a further drawback of the above mentioned prior art systems consists of the considerable bulk, thus the difficulty to be adapted and installed near the lintel, thus being very close to the ceiling, especially in constructions like garages and the like. Therefore an object of the present invention is to provide a driving device for lifting a sectional door allowing an easy assembling, that can be installed even by one person only.

Another object of the present invention is to provide a driving device for lifting a sectional door allowing a reliable, quick and easy preload adjustment.

A further object of the present invention, is to provide a device having reduced dimensions and assembling easiness still keeping optimal operative characteristics.

Still another object of the present invention is to provide a driving device for lifting sectional doors which can be industrially manufactured at low costs and very reduced size.

Finally an object of the present invention is to provide a driving device for lifting sectional doors, achieving a high level of safety for the installer in case of fault of one or more components of the device.

These and other advantages of the lifting system and device according to the present invention will be apparent from the following description of a preferred embodiment when taken together with the accompanying drawings, where same reference numerals are used for identical or equivalent elements, in which:

Fig. 1 is a front view of a door lifting system provided with the lifting mechanism according to a preferred embodiment of the present invention and the relevant door;

Fig. 1a is a sectional side view along line A-A of Fig. 1 ;

Fig. 2 is a perspective view of the embodiment of Fig. 1;

Fig. 3 is a partially sectional top view of the device of Fig. 1 ;

Fig. 3a is a sectional side view along line B-B of Fig. 3;

Fig. 4 is a sectional front view of the device shown in Fig. 1 ;

Fig. 4a is a sectional front view taken along line D-D of Fig. 4;

Fig. 4b is a sectional top view taken along line C-C of Fig. 4;

Fig. 5 is a bottom view of a detail of the device shown in Fig. 4; and

Fig. 5a is a sectional side view taken along line E-E of Fig. 5.

With reference now to Figs. 1 , 1a and 2, inside a garage or lockup 300, a lifting system 200 is shown, using a mechanism 100 to drive the garage door, according to a preferred embodiment of the present invention. The lifting system 200 has vertical guides 210 fixed at the piers 320 of the garage entry 340, and horizontal guides 230 fixed on the garages ceiling 330 and connected with the vertical guides 210 by angle guides 220. The overhead door 260 is of the sectional type and therefore comprises a set of panels 262 hinged to one another by hinges 264 and slidable in said guides 210-230 by any known means from a first closure position of entry 340 to a second opening position of entry 340. In a central position relative to the lintel, the mechanism 100 is fixed to the ceiling 330. From the mechanism two opposite cables 250 are extending up to fixed points 266 of door 260, preferably on the base panel of the door; at the ends of the lintel 310 two snub pulleys 240 are provided for cable 250. Referring again to Fig. 1 , the mechanism 100 comprises, inside a housing 1 10, a gear including two main bodies 120; on a portion of the external surface of said bodies 120 there are conjugated profiles 130, namely toothed wheels meshing to one another, the remaining portion 140 of their external surface being provided with grooves for winding of said cables 250; one can also see the lower grooved end 152 of the shafts 150 of the bodies 120, whose axes are indicated with the letter X.

Turning now to Fig. 3, the mechanism 100 is shown in a partially sectioned top view, where one can see the toothed profile 130 of the wheel, the winding of a bandlike torsional spring 170, shaft 150, the upper bearing 160 and the upper end 154 of shaft 150. More particularly, in section B-B of Fig. 3a, coupling of two side plates 116 of housing 1 10 is shown. One can see also holes 115 of connection between upper plate 114 and side plates 116. a similar connection between lower plate 1 12 and side plates 116 is also provided. Although the device 100 is always shown as a pair of bodies 120, it has to be pointed out that said bodies or wheels 120 are operating independently, namely each body or wheel 120 acts on one side of the sectional door to be lifted, but they must operate symmetrically and at the same time on the relevant side of the door. Indeed in case of very heavy sectional doors, it is contemplated to use four devices to lift the door.

With reference to Fig. 4, the components of the mechanism 100 are shown in detail, the gear is constituted by coupling two toothed wheels or profiles 130 arranged on a horizontal plane; each profile 130 is arranged above the grooved surface 140, which in turn has a diameter lower that the inner diameter of the teeth, so as to avoid interference between winding of cables 250 on each main body 120; said surface 140 is provided with a spiral groove 142 of a predetermined pitch, on which cable 250 may be wound. Thus the dimensions of this component are dependent upon the size of cable 250 and the desired number of windings. As shown in Fig. 4, the toothed profile 130 and the grooved surface 140 are made on the body 120 which is internally hollow. This cavity 190 allows to lodge inside the band torsional spring 170, whose ends 172 and 174 are connected to shaft 150 and to side wall 192 of said cavity 190. Shaft 150 is mounted with its axis X arranged on a vertical plane, through a pair of upper and lower bearings 160, each bearing abutting against a shoulder 156 of shaft 150 and a lower plate 162 through a bend 115 of the upper plate 114. Each lower plate 162 is suitably shaped so as to abut on projections 194 made on side wall 192 of cavity 190. Fig. 4b shows the detail of coupling between housing plate 114 and holding plate 118 fixed to the garage ceiling 330 by usual screw anchors 119. Finally section C-C in Fig. 4b shows the way in which torsional spring 170 is fixed to shaft 150 at its first end 172 and at its second end 174 to wall 192 of the cavity 190.

Fig. 5 is a bottom view of a detail of mechanism 100 shown in Fig. 4, showing the grooved lower end 152 of shaft 150 and a ratchet 180. More particularly the ratchet 180 consists of a saw-toothed wheel 182 keyed on end 152 and a gullet tooth 184 hinged on a bend 113 of lower plate 112 of housing 110. A spring 186 or other elastic element is arranged in such a way to push the gullet tooth 184 to be permanently engaged with the teeth of wheel 182.

It is to be noted that groove 153 of end 152 of shaft 150 is so designed as to mate with a proper tool (not shown) for adjusting preload of mechanism 100.

From the foregoing detailed description one can easily understand that the installation of mechanism 100 is made very much easier in comparison with similar prior art devices. As soon as all the components of the lifting system, namely the guides and the door are mounted, the mechanism 100 of the present invention is fastened to the ceiling by simple screw anchors. The first ends of the lifting cables are fixed to the grooved surfaces and wound around them, while the other ends are fastened at the predetermined positions on the door or its panel. At this point the installer acts with the above mentioned tool on the grooved end of each gear shaft so as to rotate the relevant wheel, load the torsional spring and stretch the cable to a degree which is predetermined according to the construction specifications of the lifting system. Then the installer proceeds in the same way on the other wheel, so as to obtain a balanced tension of both lifting cables. Therefore it is clear that installation and adjustment of the mechanisms can be achieved by a single installer under full safety conditions. Indeed the mechanism has very reduced size, with particular reference to civilian houses, allowing the installation at the ceiling level without undue efforts. Alignment of the device relative to the horizontal direction is obtained automatically, while this must be achieved in the prior art devices only with a precise fastening of the supports. Moreover, preload can be effected by a simple rotation of the two shafts independently. Finally, the arrangement of all the components inside a closed, preferably sealed housing, protects the installer if one of the springs breaks, and the presence of the ratchet avoids, if one of the cables breaks, that the cable may hit the installer, when flapping under the spring pull. In a second preferred embodiment, the mechanism of the present invention may comprise more main bodies 120 mutually mated, again by means of conjugated profiles or toothed wheels 130. a simple configuration of this kind may provide for the adoption of four main bodies 120 of the same diameter, arranged in series with one another, or each one engaged with the adjacent one. More particularly the grooves 142 for winding the lifting cables, will be made only on the bodies at the ends of said configuration. Use of more toothed wheels may support the correct dimensions of the system when there are considerable loads to be lifted, for instance for hangar doors and the like, where it is necessary to provide for stronger lifting systems and mechanisms. This embodiment also allows to use band springs 170 having different thickness or rigidity of the inner bodies relative to the outer bodies, again for the purpose of manage to the best the load to be lifted. Other configurations with more toothed wheels may be provided to deal with applications not discussed in the present disclosure. The persons skilled in this field may notice possible modifications or variations that could be resorted to the disclosed embodiment of the present invention, such as a different configuration of the conjugated profiles relative to the grooved surfaces, a different arrangement of the components inside the device housing, use of materials for manufacturing said components, all these modifications and variations falling anyway in the scope of the invention as defined in the appended claims.