Variable sealing pressure plunger rod assembly.

摘要

A variable sealing pressure plunger rod assembly for use with a syringe barrel comprises a plunger rod (27) and a flexible stopper (26). The plunger rod (27) includes a rigid elongate shaft portion (32) having a circular tapered tip portion (35) at the distal end thereof. The flexible cup-shaped stopper (26) includes an annular side wall (45) and a front wall (47) connected to the side wall (45).

An exterior surface of the side wall (45) is larger in diameter than the syringe barrel inside diameter.

The stopper interior includes an inside surface (54) of the front wall (47) and a tapered annular inside wall (55) connected to the side wall (45) and to the inside surface (54). This tapered annular inside wall (55) and the inside surface (54) define a cavity which has the tapered tip portion (35) received therein. The tapered annular inside wall (55) and the tapered tip portion (35) are inclined at approximately the same angle and adjacent to each other. Cooperating structure for maintaining the positional relationship of the stopper (26) and the plunger rod (27) is also provided.

A method of using a syringe assembly including the variable sealing pressure plunger rod assembly, substantially as described above, is also within the purview of the present invention.