Abstract:
There is described a valve assembly having a casing defining a cavity for passage of a fluid; and a valve housed in the cavity; the valve has first sealing means cooperating with the casing to divide the cavity into a first and a second environment; at least one opening permitting flow of the fluid between the first and second environment; and second sealing means varying in configuration to permit/prevent communication between the first and second environment through the opening; and the second sealing means also cooperate with the casing, on the side facing the second environment, to prevent the first and second environment from communicating fluidically through the opening.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to European Patent Application No. 05425550.0 filed Jul. 27, 2005.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to an improved valve assembly, in particular for use in household coffee machine water circulation conduits.  
       BACKGROUND OF THE INVENTION  
       [0003]     Valve assemblies are known, as described for example in Patent WOO2088580, which comprise a casing defining a fluid flow cavity; and a valve housed inside the casing to separate a first and a second environment of the flow cavity hermetically when the pressure in the first environment exceeds the pressure in the second environment by an amount above a predetermined threshold value.  
         [0004]     More specifically, the valve substantially comprises a disk-shaped base member having an opening to permit fluid flow between the first and the second environment separated by the base member; and an elastically deformable ring cooperating with the base member to fix the base member hermetically inside the cavity. The valve also comprises a flexible shutter having, on the side facing the first environment, a membrane portion which, by virtue of fluid pressure, cooperates elastically with the opening to separate the first and second environment hermetically.  
         [0005]     As stated, valve assemblies of the above type permit fluid flow between the first and second environment when the difference in pressure between the first and second environments is less than or equal to the predetermined threshold value.  
         [0006]     To this end, the base member also comprises, on the side facing the first environment, a recess communicating with the opening and selectively engageable by the membrane portion to permit fluid flow through the base member for pressure difference threshold values depending on the geometry of the recess.  
         [0007]     Though efficient and reliable, valves of the above type still leave room for improvement. In particular, a need is felt to reduce the number of component parts, so as to reduce the number of moving parts and simplify component machining and assembly.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an object of the present invention to provide a valve assembly designed to satisfy the aforementioned need in a straightforward, low-cost manner.  
         [0009]     According to the present invention, there is provided a valve assembly as claimed in the attached Claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:  
         [0011]      FIG. 1  shows an axial section of a valve assembly in accordance with the present invention and in the closed position;  
         [0012]      FIG. 2  shows a section along line II-II in  FIG. 1 ;  
         [0013]      FIG. 3  shows an axial section of a further embodiment of the  FIG. 1  valve assembly in the closed position;  
         [0014]      FIG. 4  shows a section along IV-IV in  FIG. 3 ;  
         [0015]      FIG. 5  shows a top plan view of a detail in  FIG. 1 ;  
         [0016]      FIG. 6  shows a side view of the  FIG. 5  detail. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     With reference to  FIGS. 1 and 2 , number  1  indicates as a whole a valve assembly in accordance with the present invention, and particularly suitable for use in household coffee machine water circulation conduits.  
         [0018]     Valve assembly  1  comprises a casing  2  defining a fluid flow cavity  3 ; and a valve  4  housed hermetically inside cavity  3  to control flow between two separate environments  5 ,  6  of cavity  3  separated by valve  4 .  
         [0019]     More specifically, casing  2  has an axis A, and comprises a body  7  and a body  8 , which extend axially on opposite sides towards environments  5  and  6  respectively.  
         [0020]     Body  7  comprises an axial fluid conduit  9 ; and an axial end portion  10  larger radially than conduit  9  and connected to conduit  9  by a radial wall  11 .  
         [0021]     Similarly, body  8  comprises an axial fluid conduit  12  extending on the opposite side to conduit  9 ; and an axial end portion  13 , which is larger radially than conduit  12 , is fixed to portion  10  of body  7  in a manner not shown, and is connected to conduit  12  by a radial wall  14 .  
         [0022]     Valve  4 , shown in more detail in  FIGS. 5 and 6 , is housed coaxially inside casing  2 , and comprises a portion  15  which cooperates hermetically with portion  10  of body  7  and permits fluid flow between environments  5  and  6 .  
         [0023]     More specifically, at its radially outer end, portion  15  comprises a toroidal portion  18  cooperating radially and hermetically with portion  10 ; and an annular portion  16  no larger axially than portion  18 , and connected at its radial ends to portion  18 .  
         [0024]     At the join between portion  16  and portion  18 , portion  15  also comprises a number of—in the example shown, four—axially through openings  23  permitting passage between environments  5  and  6 .  
         [0025]     More specifically, openings  23  are equally spaced angularly about axis A, and each comprise a contour defined by two radially opposite circumferential portions  31  connected by two angularly opposite radial portions  32 .  
         [0026]     Portion  15  is bounded axially towards environments  5  and  6  by respective end surfaces  20  and  21 . More specifically, end surface  21  cooperates with a number of—in the example shown, three—appendixes  22  equally spaced angularly and projecting axially from wall  14  towards valve  4  to hold valve  4  in position axially.  
         [0027]     Valve  4  also comprises a portion  19  varying in configuration to permit/prevent communication between environments  5  and  6 .  
         [0028]     Portion  19  advantageously also cooperates hermetically with casing  2 , on the side facing environment  5 , to prevent environments  5  and  6  from communicating fluidically through openings  23 .  
         [0029]     More specifically, at portion  16 , portion  19  extends from portion  15  towards environment  5  to define, with body  7 , a cavity  30  which is cut off fluidically from openings  23  when the pressure in environment  6  exceeds the pressure in environment  5  by an amount above a predetermined threshold value P. Conversely, cavity  30  is connected fluidically to openings  23 , to permit fluid flow through openings  23 , when the pressure in environment  6  exceeds the pressure in environment  5  by an amount below predetermined threshold value P.  
         [0030]     More specifically, portion  19  comprises a radially outer, truncated-cone-shaped profile  24  connected to portion  16  on the opposite side to environment  5 ; a radially inner, concave profile  25 ; and a circular axial end  26  cooperating hermetically with wall  11  of body  7 .  
         [0031]     More specifically, profile  24  diverges towards environment  5 , and, together with profile  25 , defines end  26  on the environment  5  side.  
         [0032]     Profile  25  comprises a curved portion  27  at portion  16 ; and a truncated-cone-shaped portion  28  interposed axially between portion  27  and end  26 , and diverging towards environment  5 .  
         [0033]     More specifically, profiles  24  and  25  are shaped so that portion  19  has an axial section tapering from portion  15  to end  26 .  
         [0034]     Cavity  30  is therefore bounded by profile  25  of portion  19  and by wall  11 , and is open at conduit  9 .  
         [0035]     Portions  19  and  15  are defined integrally by one body and made of flexible material. More specifically, portions  19  and  15  are preferably made of an organic polymer compatible with use in contact with food products, e.g. silicone.  
         [0036]     In actual use, when the pressure in environment  6  exceeds the pressure in environment  5  by an amount above threshold value P, end  26  adheres to wall  11  of body  7 , so that cavity  30  is cut off fluidically from openings  23  to separate environments  5  and  6  in fluidtight manner.  
         [0037]     Conversely, when the difference in pressure between environments  6  and  5  is less than or equal to threshold value P, the fluid in cavity  30  detaches end  26  from wall  11 , so that cavity  30  is connected fluidically to openings  23  to allow fluid flow between environments  6  and  5 ; which characteristic may be used to prevent fluid stagnating in environment  5  when the pressure in environment  5  falls as a result, for example, of a delivery pump connected to cavity  3  being turned off.  
         [0038]     Threshold value P, corresponding to the maximum pressure difference value at which fluid flows both ways through cavity  3 , may obviously be varied by varying the shape of portion  19 .  
         [0039]     With no change in the shape of portion  19 , threshold value P may obviously also be varied by varying the axial position of wall  11  with respect to end  26 .  
         [0040]     More specifically, moving wall  11  axially away from end  26  reduces threshold value P, eventually to zero; in which latter case, valve assembly  1  permits flow from environment  6  to environment  5  for any pressure difference between environments  6  and  5 .  
         [0041]     Conversely, moving wall  11  axially towards end  26  increases threshold value P.  
         [0042]     The  FIG. 3  embodiment shows a valve assembly  1 ′ similar to valve assembly  1 , and the component parts of which are indicated, where possible, using the same reference numbers as for the corresponding parts of valve assembly  1 .  
         [0043]     Valve assembly  1 ′ differs from valve assembly  1  by wall  11  comprising a groove  35 , which imparts an undulated shape to wall  11 . Groove  35  cooperates with end  26  to separate environments  5  and  6  hermetically, when the pressure in environment  6  exceeds the pressure in environment  5  by an amount above threshold value P, and is disengaged by end  26 , to permit fluid flow, when the pressure difference between environments  6  and  5  is below threshold value P.  
         [0044]     More specifically, groove  35  comprises a number of—in the example shown, three—contiguous lobes  36  equally spaced angularly and lying in a plane set back towards environment  5  with respect to wall  11 .  
         [0045]     With particular reference to  FIG. 3 , when the pressure in environment  6  exceeds the pressure in environment  5  by an amount above threshold value P, end  26  of portion  19  adheres to groove  35 , at each lobe  36 , so that cavity  30  is cut off fluidically from openings  23  to separate environments  5  and  6  in fluidtight manner.  
         [0046]     Conversely, when the pressure difference between environments  6  and  5  is less than or equal to threshold value P, end  26  does not adhere to groove  35 , so that cavity  30  is connected fluidically to openings  23  to permit fluid flow between environments  6  and  5 .  
         [0047]     Threshold value P therefore depends, not only on the shape of portion  19  and the axial position of wall  11  with respect to portion  19 , but also on the shape of groove  35 .  
         [0048]     The advantages of valve assembly  1 ,  1 ′ according to the present invention will be clear from the foregoing description.  
         [0049]     In particular, valve assembly  1 ,  1 ′ is formed in two parts, thus reducing the number of moving parts and relative machining and assembly costs.  
         [0050]     Clearly, changes may be made to valve assemblies  1 ,  1 ′ according to the present invention without, however, departing from the protective scope of the accompanying Claims.