Abstract:
A device for preventing overfilling of containers, such as those intended to contain liquefied gases, includes a valve body in which a gas duct is defined and a closure. The closure is axially movable in the valve body away from and towards a valve seat in order to respectively open and shut off the gas duct. An actuator, capable of exerting a thrust, urges the closure away from the seat. The actuator includes a float, a cam mechanism and a lever mechanism. The cam mechanism exerts the thrust in an ascending phase of the float until a preimposed limit position corresponding to a maximum filling level is reached. The lever mechanism exerts the thrust in at least a first part of a descending phase of the float starting from the limit position.

Description:
BACKGROUND 
     1. Technical Environment 
     The object of the present disclosure is a device for preventing overfilling of containers, in particular containers intended to contain liquefied gases. 
     2. Prior Art 
     Such containers, better known as “cylinders,” are widely utilized where a connection to the distribution network for fuel gases has not been provided. 
     For financial and safety reasons it is best that the cylinders should be filled with a predefined maximum quantity of gas, avoiding overfilling and thus excessive internal pressure. For this reason the cylinders are equipped with devices for preventing overfilling, sized to cut off the flow of entering gas when a desired fill level has been reached. 
     Devices of the type described above are known, for example, to the production of the Applicant and include membrane valves. Such valves are of the type that is normally closed and include a perforated membrane in the center, which, becoming deformed under the action of the entering gas, permits its passage. The gas flow is intercepted when a prearranged level of filling is reached and a piston, placed below the membrane and actuated by a cam connected to a float inside the container, thrusts against a seat, closing one section for passage of the gas. The variation of the sections for passage causes a counter-pressure that acts on the membrane in a direction opposite to that of the gas entering the container, closing the entrance orifice. 
     The disadvantages of such solutions are those typical of the applications of valves to membranes, i.e., the greater predisposition to wear and tear and the consequent lesser reliability compared to solutions that use valves in which the closure means is a rigid component. 
     Another inconvenience encountered in the specific application of the device for preventing overfilling of cylinders is represented by the fact that the membrane valve thus conceived makes it difficult to produce a vacuum inside the container. 
     A further drawback encountered is the reduction of the capacity of exiting gas during normal use. 
     Devices for preventing overfilling of cylinders that employ valves without membranes are known, for example, from the American patent U.S. Pat. No. 4,541,464. In this solution the valve is spherical, normally open. The obstructing sphere is kept in the open position by means of a pin constructed on a spherical member connected to a float by means of a cam driver. During the filling operation the float comes out of the container so that it causes the spherical member to rotate by means of the driving action of the cam. The system is sized in such a way that when the filling position is reached, the rotation of the spherical member causes a loss of contact between the pin and the sphere, which is thrust into the closed position of the valve by the force of gravity, besides a possible return spring. 
     A principal drawback of such solutions is represented by the fact of its being sensitive to the inclination and the oscillations of the cylinder, also from the moment that the spherical member rotates as an effect of any kind of deviation of the cylinder&#39;s axis from the vertical position. 
     A second problem is represented by the sluggish speed of the system once the maximum fill level of the cylinder has been reached. 
     A further problem with this solution is determined by the number of elements that compose it and the use of spherical members that complicate the operations of construction and assembly, making the device particularly sensitive to size tolerances and coupling. For the same reasons, the reliability of this solution in use is limited. 
     DESCRIPTION OF THE INVENTION 
     The main purpose of the invention is to make available a device for preventing overfilling of containers, in particular devices intended to contain liquefied compressed gas, structurally and functionally conceived so as to avoid all the drawbacks complained of with reference to the prior art cited. 
     This and other purposes that will appear in what follows are confronted and achieved by the invention by means of a device for preventing overfilling of containers accomplished in accordance with the claims that follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The characteristics and advantages of the disclosure will be better shown by the following detailed description of a preferred example of the device, illustrated by way of example but not limitative, with reference to the units drawn in which: 
         FIG. 1  is a lateral view of a device for preventing overfilling according to the present invention; 
         FIG. 2  is a frontal-section view of the device of  FIG. 1 ; 
         FIG. 3  is a lateral-section view of the device of  FIG. 1 ; 
         FIG. 4  is a sectional view corresponding to the one in  FIG. 3 , in a different operating state of the device of the present invention; 
         FIGS. 5 and 6  are two lateral sections of two details of the device shown in  FIG. 1 , in two respective operating states. 
     
    
    
     PREFERRED MODE OF ACTUATING THE INVENTION 
     In the figures,  1  is a comprehensive indication of a device for preventing overfilling of containers according to the present invention. Device  1  is intended to be applied to a container (cylinder B) for liquefied gas under pressure. Device  1  includes an upper channel  2  which has a longitudinal axis Y, connected to the pipe union for supplying and filling of cylinder B. 
     Below channel  2 , device  1  comprises a valve  3   a , below which is installed a lower channel  4  with axis X orthogonal to axis Y, connected with an internal volume V of the cylinder, of known cylindrical form with rounded bottoms, intended to collect the liquefied gas stored in cylinder B. 
     Valve  3   a  comprises a valve body  3 , interposed between channels  2  and  4 , in which is defined a gas duct  5  entering the cylinder, extended mainly along the direction of axis Y. The gas duct  5  is delimited, in the directions transversal to axis Y, by an internal surface  6  of valve body  3 . 
     Valve  3   a  comprises a rigid closure means  7  having the shape of a truncated cone, on axis Y with the tapered part turned toward channel  4 , axially movable in valve body  3  from and toward a valve seat  8  in order to respectively open and intercept gas duct  5 . 
     Closure means  7  comprises a bottom surface turned toward channel  2 , from which rises an appendix  9 , having a circular base and longitudinally extended along axis Y. 
     Valve  3   a  furthermore comprises a guide element  10 , in which is defined a cylindrical cavity  11 , along axis Y, in which appendix  9  is smoothly contained. 
     Guide element  10 , on the side axially opposite to the cavity  11 , comprises a central arch  12 , capable of being entered by the flow of gas entering the cylinder. Guide element  10  is integral with valve body  3 , being equipped with a perimetric annular protuberance  13 , partially nested in an annular seat  14 , located on the inner surface  6  of valve body  3 . 
     Annular protuberance  13  is transverse to axis Y and is provided with a plurality of passages  15 , to allow for the flow of entering gas to valve seat  8 . 
     Valve  3   a  comprises a control rod  17 , associated with closure means  7 , being constructed as a piece with it. Rod  17  is longitudinally extended along axis Y, in a position axially opposite with respect to the appendix  9 . 
     According to other variations of the present invention (not shown), in place of valve  3   a  other types of valves may be used, for example valves with a membranous closure means controlled by means of a control rod extended longitudinally, analogous to rod  17 . 
     Control rod  17  crosses channel  4 , above which it is bound in a cylindrical axial guide  18 , integral to valve body  3  and working together with guide element  10  to axially guide closure means  7 . Control rod  17  furthermore comprises an end  19 , axially opposite closure means  7 . 
     Device  1  comprises an actuator  16  that can exert a thrusting force F on end  19  of rod  17  in order to urge closure means  7  away from valve seat  8 . 
     Actuator  16  comprises a float  20 , extended inside the interior volume V of cylinder B, and a cam mechanism  21  to exert the thrust F, in a rising phase of float  20 . Thrust F is exerted until it reaches an extreme position preset by float  20 , corresponding to a maximum fill level of cylinder B. 
     Mechanism  21  comprises a member  22 , linked to valve body  3  by a hinge  23 , on which a cam profile  24  is defined. The cam profile  24  is compatible with closure means  7  in order to exert thrust F until it meets end  19  of control rod  17 . During the upward-traveling phase of float  20 , end  19  of rod  17  slides on cam profile  24  until it reaches an end point  25  ( FIG. 4 ). 
     Cam profile  24  is an arc of a circle with its center on hinge  23  so as to hold closure means  7  at a constant distance from valve seat  8 . Cam profile  24  is sized in such a way that when float  20  has reached the extreme position of maximum filling, end  19  is placed in correspondence with point  25 . In this state, thrust F cannot be exerted, and closure means  7  thus becomes subject only to its own force weight P, which causes closure means  7  to fall toward valve seat  8  so as to intercept gas duct  5 . 
     According to a constructible variant (not shown) of the present invention, the fall of closure means  7  is caused, in addition to weight P, by a return spring. 
     Actuator  16  furthermore comprises a lever mechanism  26  for exerting thrust F on rod  17  in a first stage of descent of float  20  starting from its extreme point of maximum filling. 
     Lever device  26  comprises a fulcrum  27 , hinged to member  22  at distance D from hinge  23 , and a first arm  28  extended from fulcrum  27  toward cam profile  24 . First arm  28  [is] compatible with closure means  7  by exerting thrust F, until it meets end  19  of control rod  17  and a second arm  29 . Fulcrum  27  is interposed between first arm  28  and a second arm  29 , integral to float  20 . First arm  28  and cam profile  24  are positioned from the same part with respect to straight line Z, which joins hinge  23  and fulcrum  27 . 
     During the upward-moving phase of float  20 , arms  28  and  29  place themselves in a position aligned with member  22 , in such a way that first arm  28  can rest against member  22 . 
     During the descent phase of float  20 , end  19  of rod  17  slides on first arm  28  until it reaches an end  30  of first arm  28  in correspondence with an intermediate position of float  20  ( FIG. 6 ). 
     In correspondence with the intermediate position of float  20 , the point of end  25  of cam profile  24  and end  30  of first arm  28  are adjacent to each other. Besides the intermediate position, in a second part of the upward-moving phase of float  20 , end  19  of rod  17  moves on cam profile  24 . 
     The functioning of lever mechanism  26  described above thus permits the rearming of cam mechanism  21 , in such a way that end  19  of rod  17  can move on cam profile  24  when the level of cylinder B is lower than the intermediate one, in particular when cylinder B is empty. 
     The present invention allows us to obtain a device for preventing overfilling of containers capable of responding quickly when the maximum fill level is reset. 
     This device does not experience variations of pressure during the filling of the cylinder. 
     The reduced number, compared to other known solutions, of valve components permits the achievement of greater simplicity in the functional geometries and, consequently, fewer rejects in production and greater dependability in usage. 
     In this way the invention fulfills the proposed purpose, at the same time achieving numerous advantages, among which are: 
     a) the use of a valve of the type that is always open allows better performance with respect to implementing the vacuum in cylinders. 
     b) the phenomenon of interrupting filling before it is completed is reduced; 
     c) performance does not depend on the pressure or density of the fluid being handled; 
     d) repetitiveness of the filling operations is improved, because of reduction of variability in the maximum level actually achieved inside of the cylinder in several successive filling operations.