Patent Publication Number: US-2007116587-A1

Title: Volume-metering pump device

Description:
The present invention relates to a volume-metering pump device.  
     BACKGROUND OF THE INVENTION  
      Volume-metering pump devices are known that comprise a pump member associated with a manifold member comprising a body containing a manifold chamber having ports providing connections with the pump member, with an admission duct connected to a feed vessel, and with a discharge duct, and in which a manifold control element is mounted to move along a longitudinal direction of the manifold chamber and is actuated by a control member so as to put the pump member into communication in alternation with the admission duct or with the discharge duct.  
      In existing-devices, and in particular the device described in British patent document GB-A-968 452, the manifold control element is mounted to slide with reciprocating motion in the manifold chamber and has toroidal rubber valve members mounted on the manifold member outside the manifold chamber. When the pump device is in operation, the pump chamber is in communication with the admission duct or with the discharge duct as a function of the position of the manifold control element. During the displacements of the manifold control element, some of the fluid being pumped accumulates between the toroidal valve members and the manifold control element. This fluid is difficult to extract during washing so that in practice it is not possible to perform pumping under sterile conditions when using existing devices.  
     OBJECT OF THE INVENTION  
      An object of the present invention is to propose a volume-metering pump device that can operate easily under sterile conditions.  
     SUMMARY OF THE INVENTION  
      In order to achieve this object, the invention provides a volume-metering pump device comprising a pump member associated with a manifold member comprising a body containing a manifold chamber having ports providing connections with the pump member, with an admission duct connected to a feed vessel, and with a discharge duct, a manifold control element being mounted to move along a longitudinal axis of the manifold chamber and being actuated by a control member, the port providing a connection with the admission duct and the port providing a connection with the discharge duct being disposed facing each other and coaxially about the longitudinal axis of the manifold chamber on opposite sides of the port providing a connection with the pump member and being adjacent to respective seats facing towards the inside of the manifold chamber, and the manifold control element has ends shaped to form valve members adapted to come to bear in leaktight manner against one or the other of the seats under drive from the control member of the manifold control element.  
      Thus, even though it ensures that one or other of the ports is closed in leaktight manner during operation of the pump device, the manifold control element can easily be cleaned by moving the valve member away from its seat and causing the cleaning fluid to flow around the valve member.  
      In an advantageous version of the invention, the pump member has a cylindrical pump chamber in which there is mounted a piston without gaskets that is connected to an actuator member for moving the piston along an axial direction of the pump chamber, and at an end remote from the port providing a connection between the manifold chamber and the pump chamber, the pump chamber is connected to a feed vessel, the piston being mounted in the pump chamber with clearance that is small enough to ensure that a fluid contained in the feed vessel does not flow around the piston.  
      Thus, while pumping a fluid, a thin film of fluid forms between the piston and the pump chamber, such that sealing is provided between the piston and the pump chamber, with this film of fluid being easily eliminated during cleaning.  
      According to other aspects of the invention that are advantageous, the pump member includes an auxiliary chamber lying on the same axis as the pump chamber and opening out into the feed vessel, and the stroke of the piston actuator member is preferably sufficiently long to enable the piston to be brought fully into the auxiliary chamber, the auxiliary chamber having a diameter that is large enough to allow fluid to flow around the piston. The auxiliary chamber then performs three functions, i.e. for a position of the piston inside the pump chamber, it serves to seal the piston, and when the piston is brought into the auxiliary chamber during washing, the piston is thoroughly subjected to the effects of the cleaning fluid so that the auxiliary chamber acts as a piston-washing chamber. In addition, with the piston in this position, the pump chamber is disengaged and it is therefore itself cleaned thoroughly by the washing fluid. Finally, during initial filling of the installation with the fluid product for packaging, the piston is brought into the auxiliary chamber so that the fluid product flows around the piston in order to fill the pump chamber and the manifold chamber, and bubbles of air can rise into the feed vessel so that the auxiliary chamber also acts as a gravity feed chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other characteristics and advantages of the invention appear on reading the following description of a preferred and non-limiting embodiment of the invention described with reference to the accompanying figures, in which:  
       FIG. 1  is an axial section view on a vertical plane through a device of the invention and the feed vessel associated therewith, for an admission position of the manifold control element; and  
       FIG. 2  is a section view analogous to that of  FIG. 1 , for a washing position of the pump device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      With reference to  FIG. 1 , the pump device comprises a pump member  1  connected to a feed vessel  2  and associated with a manifold member  3 . The pump member comprises a pump body  4  having a pump chamber  5  in which a piston  6  without gaskets or piston rings is mounted to slide with very little clearance, for example clearance of a few tenths of a millimeter. The piston  6  is actuated by a rod  7  connected to an actuator member  8 .  
      Between the pump chamber  5  and the feed vessel  2 , the pump member  1  has an auxiliary chamber  9  on the same axis as the pump chamber  5 , and of transverse dimension D considerably greater than a transverse dimension d of the pump chamber  5 , and opening out into the feed vessel  2 .  
      The manifold member  3  comprises a body  10  containing an elongate cylindrical manifold chamber  11  having a longitudinal axis  36 . The manifold chamber  11  includes a port  12  leading to the pump member  1 . The port  12  opens out into the side of the manifold chamber  11 . At each of its ends, the manifold chamber  11  has respective ports  13  and  14  coaxial about the longitudinal axis  36  and facing each other on either side of the port  12 . Adjacent to the ports  13  and  14 , the manifold chamber includes zones configured to provide respective seats  33  and  34  that are coaxial about the longitudinal axis  36  and that face towards the inside of the manifold chamber. The seats  33  and  34  are disposed so that each of them receives a respective end  15  or  16  shaped to form a valve member and belonging to a cylindrical manifold control element  17  mounted to slide in a longitudinal direction in the manifold chamber. The valve members  15  and  16  are thus located between the seats  33 ,  34 .  
      The manifold control element has a control rod  18  extending in a bore  27  and connected to a control member  19 . The control member  19  comprises an actuator member  35  and a member  20  for coupling through a wall without piercing it. For example, the coupling member comprises in conventional manner a magnet  21  carried by a rod  22  associated with the actuator member  35  and mounted to move in a glove finger  23  of non-magnetic material, together with a magnetic ring  24  surrounding the glove finger  23  and connected to the control rod  18  by a U-shaped bracket  25 . The manifold control element  17  is held coaxially in the manifold chamber  11  by guide fins  26  that slide in the bore  27  on the same axis as the manifold chamber  11 , and guide fins  28  sliding in a bore  29  that likewise lies on the same axis as the manifold chamber  11 . The port  14  is connected to an admission duct  30  via the bore  27  and an admission chamber  31  surrounding the coupling member  20 . At its top end, the admission duct  30  opens out into the bottom end of the auxiliary chamber  9 .  
      The port  13  is connected to a discharge duct  32  by the bore  29 . The discharge duct  32  is connected to a metering spout that is not shown.  
      The actuator member  8  presents a stroke that is sufficient not only to drive the piston  6  back and forth in the pump chamber  5 , but also to pull the piston  6  out of the pump chamber  5  into the auxiliary chamber  9 , as shown in  FIG. 2 .  
      The valve member  15  of the manifold control element  17  is shaped to close the port  13  in leaktight manner when the valve member  15  is pressed against the seat  33  adjacent to the port  13 . Similarly, the valve member  16  is shaped to close the port  14  in leaktight manner when the valve member  16  is pressed against the seat  34  adjacent to said port. The distance between the valve members  15  and  16  is shorter than the distance between the seats  33  and  34  so that when one of the ports is closed, the other is wide open. Furthermore, the transverse size of the manifold control element  17  is considerably smaller than the transverse size of the manifold chamber  11  so that the product for dispensing flows easily around the manifold control element  17  when either one of the ports  13  or  14  is open.  
      When the installation including the pump device of the invention is initially started up, the valve member  16  is caused to press against its seat  34  so that the port  13  is wide open. The piston  6  is raised into the auxiliary chamber  9  as shown in  FIG. 2 . In this position, the product for packaging flows under gravity into the auxiliary chamber  9  and flows around the piston  6 , thereby firstly filling the admission duct  30  and secondly filling the pump chamber  5  and filling the manifold chamber  11  and the discharge duct  32 . The auxiliary chamber  9  thus acts as a gravity feed chamber.  
      The piston  6  is then lowered to the end of its stroke in the pump chamber  5  and is then driven with reciprocating motion over a stroke that keeps the piston  6  in the pump chamber  5 . On each upward stroke of the piston, the valve member  15  is brought to bear against the seat  33  adjacent to the connection opening  13  so as to close it. The connection opening  14  is then wide open and the product for packaging is sucked into the pump chamber  5 , passing via the auxiliary chamber  9  and the admission duct  30 , the admission chamber  31 , and the manifold chamber  11 . On each downward stroke of the piston  6 , the manifold control element  17  is moved to close the port  14  and to open the port  13  so that a volume of product corresponding to the stroke of the piston  6  is propelled by the piston  6  into the discharge duct  32 . The auxiliary chamber  9  then acts as a sealing chamber relative to the piston.  
      When the feed vessel  2  is empty, a washing liquid is introduced into the feed vessel  2  and the pump device is put into the position shown in  FIG. 2 , i.e. the piston  6  is raised so as to extend within the sealing chamber  9 , and the manifold control element  17  is put into an intermediate position in which both ports  13  and  14  are open. The washing liquid flows in the discharge duct  32 , passing simultaneously through the admission duct  30  and the pump chamber  5 . The auxiliary chamber  9  then performs a washing function. In addition, this system enables all of the air to be purged while washing the spout, by allowing the air to rise into the vessel.  
      Naturally, the invention is not limited to the embodiment described above and variants thereof will appear to the person skilled in the art without going beyond the ambit of the invention as defined by the claims.  
      In particular, although the device described combines a manifold member without any gasket and a pump member without any gasket, the manifold member without gaskets could be used together with a pump member of traditional structure, the admission duct then being connected directly to the feed vessel.  
      Although in the embodiment shown an auxiliary chamber is interposed between the pump chamber and the feed vessel, the invention can be implemented with a pump chamber that opens out directly into the feed vessel, which then acts as an auxiliary chamber both for gravity feed purposes and for pumping and washing.  
      Conversely, the auxiliary chamber could be separate from the feed vessel and be connected thereto by a duct.