Joint for Device for Metering Liquids

Abstract

The present invention relates to a device for metering liquids, for example a pipette or a metering button. The device comprises a joint forming a seal between a hollow cylinder and a piston housed inside the cylinder, the piston being moved vertically so as to suck in or expel the liquid. During the metering operation, the joint remains fixed with respect to the movement of the piston and comprises parts formed by portions having dedicated geometric and mechanical characteristics which make it possible to locally optimize the functions the sliding, sealing, and fastening in the cylinder.

1 - 18 . (canceled) 
     
     
         19 . A device for manually metering liquids comprising
 a cylinder, and   a piston housed inside the cylinder, with the device being arranged so that during a metering operation, the piston moves along an axis of the piston to suck in or to expel a volume of liquid,   
       the device further comprising:
 a joint housed in the cylinder and arranged so as to provide a sealing between the cylinder and the piston, wherein during a liquid metering operation, the joint remains fixed with respect to a movement of the piston, wherein the joint comprises
 a first, external part which cooperates with the internal wall surface of the cylinder and which functions to provide sealing of the joint against an internal wall surface of the cylinder, and, 
 a second, internal part, which is in contact with the piston and which functions to provide a sealing of the joint against the piston and to exert a friction force on the piston upon the movement of the piston relative to said joint, 
 wherein said first and second parts are made in one piece of a same elastomer material, wherein said elastomer material is in sealing contact with said piston. 
 
 
     
     
         20 . The device of  claim 19 , wherein the joint is a one piece joint. 
     
     
         21 . The device of  claim 19 , wherein the friction force imparted by the joint pressing against the piston surface upon the movement of the piston with respect to the joint is smaller than or equal to 2 N. 
     
     
         22 . The device according to  claim 19 , wherein said elastomer material has a Shore A hardness of less than 75. 
     
     
         23 . The device of  claim 19 , wherein said first part of the joint is more rigid than said second part. 
     
     
         24 . The device according to  claim 19 , wherein said first part of the joint is more voluminous than said second part of the joint. 
     
     
         25 . The device of  claim 19 , wherein said first part is not in contact with the piston. 
     
     
         26 . The device of  claim 19 , wherein said first part further functions to fasten the joint in the cylinder. 
     
     
         27 . The device of  claim 19 , wherein said first part comprises fins protruding from a body of the joint, said fins preventing a vertical upwards movement of the joint. 
     
     
         28 . The device according to  claim 19 , wherein the joint comprises a single, annular contact surface with the piston. 
     
     
         29 . The device of  claim 19 , wherein said second part comprises a lip, the distal end of which is in sealing contact with the piston. 
     
     
         30 . The device of  claim 29 , wherein a body of the lip is oriented at an angle compared to the axis of the piston. 
     
     
         31 . The device of  claim 19 , wherein said second part comprises a sinusoidal shaped tube curved towards the axis of the piston. 
     
     
         32 . The device of  claim 31 , wherein said sinusoidal shaped tube defines an air pocket filling part of the annular volume between said cylinder and said joint on the side of the joint that is opposed to the piston. 
     
     
         33 . The device according to  claim 19 , wherein the joint has, in radial cross-section with respect to the piston axis, at least one part having a curved shape, said curved shape being oriented towards the piston axis, wherein a proximal zone of said curved shape is in contact with the piston. 
     
     
         34 . The device according to  claim 19 , wherein the thickness (c, c′) of the second part of the joint, measured at a point of contact of said second part with the piston in a direction perpendicular to the piston axis from said point of contact is smaller than 1 mm. 
     
     
         35 . The device of  claim 34 , comprising a contact surface where said second part is in contact with the piston, wherein said point of contact is in said contact surface, wherein said thickness (c, c′) of said second part of the joint, measured at a point of contact with the piston in a direction perpendicular to the piston from the point of contact, is smaller than  1  mm on whole of said contact surface. 
     
     
         36 . The device according to  claim 19 , wherein the joint includes at least one empty recess that mechanically uncouples said first part from said second part. 
     
     
         37 . The device of  claim 36 , wherein said recess defines a transition zone and/or a connection zone between the first part and the second part. 
     
     
         38 . The device of  claim 36 , wherein said recess does not harbor an O-ring. 
     
     
         39 . The device of  claim 19 , wherein said joint is free of any O-ring and/or said joint is functional without any O-ring. 
     
     
         40 . The device of  claim 19 , wherein said joint comprises a third part made in one piece with said first and second parts, said third part providing the anchoring of the joint in the cylinder. 
     
     
         41 . The device of  claim 40 , wherein said third part comprises one or more selected from protruding fins, an external rim, an upper bulge, and a stabilizing element made from a different material than said elastomer material. 
     
     
         42 . The device according to  claim 19 , wherein the joint is retained in a space between the internal wall of the cylinder and the piston using at least one retaining ring, openings and/or grooves. 
     
     
         43 . The device of  claim 19 , said device having a nominal or maximum volume of 1000 μl or less, wherein the friction force imparted by the joint pressing against the piston surface upon the movement of the piston with respect to the joint is smaller than or equal to 0.6 N. 
     
     
         44 . A device for manually metering liquids, said device having a nominal or maximum volume of 20 to 100 ml, said device comprising:
 a cylinder, and   a piston housed inside the cylinder, with the device being arranged so that during a metering operation, the piston moves along an axis of the piston to suck in or to expel a volume of liquid,   
       the device further comprising:
 a joint housed in the cylinder and arranged so as to provide a sealing between the cylinder and the piston, wherein during the metering operation, the joint remains fixed with respect to a movement of the piston, wherein the joint comprises
 a first, external part, which cooperates with the internal wall surface of the cylinder and which functions to provide a sealing of the joint against an internal wall surface of the cylinder, and, 
 a second, internal part, which is in contact with the piston and which functions to provide a sealing of the joint against the piston and to exert a friction force on the piston upon the movement of the piston relative to said joint, 
 wherein said first and second parts of said joint are made in one piece of a same elastomer material, wherein said elastomer material is in sealing contact with the piston, wherein said first part is more rigid than said second part, and, wherein the friction force imparted by the joint pressing against the piston surface upon the movement of the piston with respect to the joint is from 2 to 5 N.