Volume-metering pump device

Abstract

The volume-metering pump device comprises 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 axis of the manifold chamber, the ports providing connections with the admission duct and with the discharge duct being disposed facing each other and being coaxial about the longitudinal axis of the manifold chamber on either side of the port providing a connection with the pump member, and being adjacent to seats facing towards the inside of the manifold chamber with which valve-member forming portions made at the ends of the manifold control element co-operate to enable one or the other of the ports to be closed.

1 . 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, wherein the seats face 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.  
   
   
       2 . A pump device according to  claim 1 , wherein the control member is a magnetic member adapted to control displacement of the manifold control element through a wall, without piercing the wall.  
   
   
       3 . A pump device according to  claim 1 , wherein 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 wherein, 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.  
   
   
       4 . A pump device according to  claim 3 , wherein, between the pump chamber and the feed vessel, the pump member includes an auxiliary chamber of transverse dimension greater than a transverse dimension of the pump chamber.  
   
   
       5 . A pump device according to  claim 4 , wherein the auxiliary chamber is on the same axis as the pump chamber and opens out into the feed vessel.  
   
   
       6 . A pump device according to  claim 5 , wherein the actuator member presents a stroke that is long enough to be able to bring the piston into a position in which the piston is withdrawn into the auxiliary chamber sufficiently to allow fluid to flow around the piston into the pump chamber.  
   
   
       7 . A pump device according to  claim 6 , wherein the admission duct opens out into the auxiliary chamber.