Abstract:
In a mechanism for locking curtains and the like, a sleeve rotates about a relative axis and is fastened to a roll, in coaxial relation therewith. A curtain is rolled up on the roll. A barrel features at least one radial housing opening outside of the barrel and enters freely the sleeve. The mechanism includes also one spring introduced freely in each radial housing and pushing a cylinder or a sphere against an inner surface of the sleeve.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the production of darkening and protection devices for windows or doors, e.g. curtains or mosquito nets, these curtains or nets rolling and unrolling on a cylinder structure. 
     In particular, the present invention relates to a mechanism for locking the curtains or mosquito nets in a desired position, usually open or closed, but mainly in any intermediate position. 
     DESCRIPTION OF THE PRIOR ART 
     Devices have heretofore been provided, as including a roll, on which the curtain or mosquito net rolls up, supported by suitable, substantially horizontal means. 
     This roll is usually introduced in a suitable case situated over, or in any case, near the upper edge of the window or door. 
     The free end of the curtain goes out of said case through a relative slot. 
     The curtain can be operated by a suitable drive member, basically including a pulley, which is integral with the roll and is connected to a relative, generally endless pull rope going out of the case at the sides of the pulley. 
     The roll is driven into rotation in the rolling direction by pulling down one of the rope ends, whereas it is driven into rotation in the unrolling direction by pulling down the other of the rope ends. 
     Suitable locking means, usually connected to the roll, allow the curtain to be firmly positioned, approximately in the desired point. 
     The main disadvantage of these locking mechanisms derives from the fact that they are not sufficiently resistant, when the curtain moves, either in rolling or unrolling direction. 
     These locking mechanisms must offer a sufficient resistance when the curtain is motionless, so as to maintain it in the predetermined position, overcoming possible action of elastic means connected to the roll, which would tend to roll it. 
     This locking mechanism can be formed by brakes, which elastically interfere with a support fastened to the roll on which the curtain is positioned. 
     The dimension of the brakes, wound around a suitable blocking part, prevents roll free rotation, if the curtain is not stressed from outside. 
     Other devices have been proposed, as shown in FIG. 1, in which the curtain control means C feature a hollow roll B, coaxial therewith, which has, made therealong, a slit B 1  cooperating with the ends D 1 , D 2  of a plurality of elastic means D, freely wound around an inner roller A, stationary and coaxial with the hollow roll B. 
     When suitable transmission means drive the control means C to rotate, the edges of the slit B 1  go in abutment against the ends D 1 , D 2  of the elastic means D, thus twisting them. 
     When one of the edges of the slit B 1  strikes the related end D 1  or D 2  respectively, the friction of the elastic means D, wound around the inner roller A and sliding therealong, is reduced, thus facilitating the curtain rolling and unrolling. 
     If the control means C are not operated by the user, the action of the elastic means D on the inner cylinder A determines a friction against mutual sliding, and the friction action is bigger than the weight action of the portion of the curtain not wound around the hollow roll B. 
     The above mentioned technical solutions are worldwide marketed, yet they have a very big drawback resulting from a considerable unreliability of the curtain positioning. 
     This unreliability is a direct consequence of the difference between the circumference arc corresponding to the transversal dimension of the slit B 1  and the distance between the ends D 1 , D 2  of the elastic means D; this is a problem particularly in case of mosquito nets. 
     Moreover, the more stressed components, in particular the edges of the slit B 1  of the hollow roll B and the ends D 1 , D 2  of the elastic means D, lack structural resistance. 
     If the locking mechanism maintenance, which is very expensive, is not proper, a structural deficiency of the hollow roll B in the slit B 1  area can seriously jeopardize the locking mechanism functionality, thus damaging its reliability. 
     Moreover, it is to be pointed out that the described technical solutions are obtained by using very expensive components and specialized manpower. 
     In fact, the cost of this mechanism depends on its dimension, which is related to the curtain dimensions. 
     Further, it is necessary to prepare a wide range of sizes for satisfying the market different needs. 
     SUMMARY OF THE INVENTION 
     This invention was evolved with the general object of avoiding the above mentioned drawbacks by proposing a mechanism for locking curtains and the like which guarantees a rapid, precise and stable locking in any position and in any angular position of the curtain supporting roll. 
     Another object of the present invention is to propose a locking mechanism, which is particularly strong and reliable in different working conditions. 
     A further object of the present invention is to propose a considerably versatile locking mechanism, which has almost the same size for curtains and nets of different dimensions. 
     Yet another object is to propose a locking mechanism obtained by a simple technical solution, which guarantees correct rolling and unrolling and which is extremely functional, reliable and cheap. 
     The above mentioned objects are obtained, in accordance with the contents of claims, in a mechanism for locking curtains and the like including a sleeve rotating about a longitudinal axis and fastened to a roll, in coaxial relation therewith, with a curtain or a similar article rolled up on said roll, said mechanism being fastened to a stationary support structure, by providing said mechanism with: 
     a barrel which enters freely said sleeve and couples firmly with said structure by relative coupling means, with said barrel featuring, made therein, at least one radial housing opening outside of said barrel; 
     at least one elastic element introduced freely in this radial housing and co-operating with friction means, said friction means being kept in contact with an inner surface of said sleeve due to the action of these friction means on the elastic element. 
     According to a different embodiment of the invention, the mechanism includes: 
     a barrel which enters freely said sleeve and couples firmly with said structure by relative coupling means; 
     a plurality of series of radial housings made in said barrel, with housings of each series all aligned and opening outside of said barrel, with corresponding axes of said housings being laid in a relative longitudinal plan passing through a longitudinal axis of this barrel; 
     at least one elastic element introduced freely in each radial housing and co-operating with relative friction means, said friction means being kept in contact with an inner surface of said sleeve due to the action of these friction means on the elastic element. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The characteristic features of the present invention will become more fully apparent from the following detailed description of a preferred, but not sole, embodiment taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a schematic prospective view of the device described in prior art; 
     FIGS. 2 a ,  2   b  are schematic lateral corresponding views in axial section of the proposed locking mechanism in two different use conditions; 
     FIG. 3 is a section view taken along III—III of FIG. 2 a;    
     FIG. 4 is the same view of FIG. 3 of the proposed device according to another embodiment; 
     FIG. 5 is a schematic front sectional view of the device according to a further embodiment, taken along a plan perpendicular to the device axis; 
     FIG. 6 is a schematic lateral view in axial section of still another embodiment of the proposed device; 
     FIG. 7 is a lateral, partially section view of a different conformation of the proposed device; 
     FIG. 8 is a schematic, perspective exploded view of two different parts of the device shown in FIG.  7 . 
    
    
     With reference to the above mentioned drawings, the reference numeral  1  generally designates a mechanism for locking curtains and the like. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Mechanism  1  is substantially formed by a sleeve  3  featuring a ring-like seat  3   a  made thereinside, near the inlet  3   b.    
     The seat  3   a  goes in abutment with a flange  6   b  of a barrel  6  introduced into the sleeve  3  coaxial therewith. 
     On its outer side, near the inlet  3   b , the sleeve  3  forms a drive member  4 , e.g. integral with this sleeve, which transmits a rotating motion to the sleeve  3  by a relative transmission element  4   a , e.g. a driving rope connected to this member  4 . 
     A hollow roll  5 , around which a curtain is wounded, is fastened outside the sleeve  3  coaxial therewith (FIG. 2 a ). 
     Near its flange  6   b , the barrel  6  is equipped with coupling means which comprise a seating  6   a , coaxial therewith, which couples with a tang  10   a  formed by a stationary support structure, e.g. vertical (FIG. 2 a ). 
     The barrel  6  is provided with a plurality of radial housings  8 , aligned and arranged along a longitudinal plane which include the axis of the barrel  6 . 
     The housings  8  open in a longitudinal recess  9  made in the outer surface of the barrel  6 . 
     Friction means  7 , e.g. a cylinder, freely introduced into this longitudinal recess  9 , are kept always in contact with the inner surface  3   d  of the sleeve  3  due to the elastic reaction exerted by elastic means  8   a  on these friction means. 
     The elastic means  8   a  are freely introduced into the radial housings  8 . 
     According to the embodiment shown in FIG. 4, this cylinder  7  features a flattening  7   a , on which the elastic means  8   a  act. 
     It is possible to operate the drive member  4  by the rope  4   a  starting from any static condition of the curtain wound around the hollow roll  5 , in both rolling and unrolling directions. 
     Rotation, thus imposed to the sleeve  3 , creates a low friction relative sliding and/or rolling motion between the cylinder  7  and the inner surface  3   d  of the sleeve  3 . 
     This effect is obtained because the barrel  6  is locked to the stationary support structure  10 . 
     In this way, rolling and/or unrolling of the curtain, or other similar element, placed on the hollow roll  5  integral with the sleeve  3 , is facilitated. 
     The absence of the outer pull action on the drive member  4  creates a friction which prevents relative rotation of the sleeve  3 . 
     This is caused by elastic reaction of the elastic means  8   a , of suitable number and of proper characteristics, which pushes the cylinder  7  against the inner surface  3   d  of the sleeve  3 . 
     In this way, a particularly static angular condition of the sleeve  3  with respect to the barrel  6  is obtained. 
     This condition can be altered by acting on the drive member  4  by the rope  4   a , in a predetermined way. 
     According to another embodiment, the locking mechanism includes a plurality of series of aligned radial housings  8 , arranged along relative longitudinal plans all including the barrel  6  axis and angularly equispaced. 
     The radial housings  8  of each series open in a related longitudinal recess  9  made in the outer surface of the sleeve  3  (FIG.  5 ). 
     This way, it is possible to stabilize in better way the angular configuration of the sleeve  3  and/or a sleeve  3  supporting a hollow roll  5  with a curtain of big dimensions and/or weight. 
     According to a further embodiment of the present invention, it is possible to obtain a regular positioning precision for the curtain by providing radial housings  8 , which do not open into a longitudinal recess  9 , but extend up to the outer surface of the barrel  6  (FIG.  6 ). 
     In this case, the most proper friction means  7  are spheres kept permanently in contact with the inner surface  3   d  of the sleeve  3  by the elastic reaction of the elastic means  8   a.    
     Likewise, series of aligned radial housings  8  can be provided, arranged along relative longitudinal plans all including the barrel  6  axis and angularly equispaced. 
     According to a possible construction, the barrel  6  includes two bodies, an anchorage body  61  and an operative body  62 , which can be removably fastened to each other (FIGS. 7,  8 ). 
     In this case, the anchorage body  61  has coupling means which mesh with the support structure  10 , in a known way, by a splined coupling  11   a  having grooved profiles provided with the support structure for entering a seating having a complimentary section made in the anchorage body portion of the barrel. 
     The anchorage body  61  features also a transversal slot  12 , made along an axial symmetry plane. 
     The operative body  62  includes a unit  13 , situated in the region of the coupling head  62   a  and having a profile complementary to the transversal slot  12  into which it is introduced. 
     Likewise, the sleeve  3  is formed by two bodies, a reference body  31  and a support body  32 , which can be removably locked to each other. 
     The reference body  31  winds freely and tightly around the anchorage body  61  and is integral with the drive member  4 . 
     This reference body  31  has also a pair of longitudinal grooves  14   a , e.g. facing opposite directions, which couple with a corresponding pair of wings  14 , formed by the support body  32 . 
     The assembly constituted by the operative body  62  and the part of the support body  32 , without considering the wings  14 , is manufactured according to any one of the described embodiments, shown in FIGS. from  1  to  6 . 
     Basically, while the reference body  31  rotates with respect to the anchorage body  61 , the support body  32 , driven by the reference body  31 , rotates with respect to the corresponding operative body  62 . 
     Once the anchorage body  61  has been fastened to the support structure  10 , this solution allows a rapid and best mounting of the operative body  62  and the complementary support body  32  introduced into the relative head of the hollow roll  5 . 
     This way, when the barrel and the sleeve are coupled with the hollow roll  5 , they are not subjected to dangerous bending stresses, particularly in case of very big, and consequently heavy, curtains and the like. 
     The described locking mechanism in its proposed embodiments guarantees a rapid and precise positioning of curtains and like articles independently from the angular position of the curtain supporting roller. 
     This precision is guaranteed by the stabilizing action of the friction means, cylinders or spheres, which cooperate with the relative elastic means. 
     The compact and reduced structure of the barrel, equipped with a plurality of radial seats, allows to obtain a particularly strong locking mechanism, which is very reliable with a wide range of curtains and the like, thus permitting a substantial reduction of the number of sizes to be stored in magazine. 
     The possibility to easily stabilize the angular position of the sleeve by interaction of the elastic means with the relative friction means, makes the proposed mechanism very versatile, since it allows to work with almost constant dimensions, for different sizes of curtains and similar articles. 
     Moreover, it is to be pointed out that the number of the elements of the above described locking mechanism is limited and that they are very simple to manufacture, which is advantageous to the production costs. 
     It is understood that what above has been described as a mere, non limitative example, therefore possible constructive variants remain within the protective scope of the present technical solution, as described above and claimed in the following.