Disposable syringe

• US 5,275,582 A
• Filed: 10/15/1992
• Issued: 01/04/1994
• Est. Priority Date: 10/22/1991
• Status: Expired due to Fees

• Current Assignee: Erwin Wimmer
• Original Assignee: Erwin Wimmer
• Inventors: Wimmer, Erwin
• Primary Examiner(s): YASKO JR, JOHN D
• Application Number:
  US07/961,443
• Time in Patent Office: 446 Days
• Field of Search: 604/218, 604/187, 604/110, 604/221, 604/222, 604/228, 604/256, 604/229, 604/230
• US Class Current: 604/218
• CPC Class Codes: A61M 2005/31516 reducing dead-space in the syringe barrel after delivery
• CPC Class Codes: A61M 2005/31521 Pistons with a forward extending skirt at their front end
• CPC Class Codes: A61M 2005/342 Off-center needles, i.e. needle connections not being coaxial with the longitudinal symmetry axis of syringe barrel
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding

Abstract

A disposable syringe comprises a syringe cylinder and a syringe piston. The syringe cylinder is open at one end and at its other end has an end wall, which is closed with the exception of a region adjacent to a needle holder. The syringe piston comprises a piston skirt, which protrudes from the syringe cylinder, and a piston head, which is disposed within the syringe cylinder and provided with an annular seal. The annular seal is connected to the piston head by an annular peripheral flange.

In order to provide a syringe which can easily be actuated and is nevertheless absolutely tight, the flange is frustoconical and flares toward the piston skirt. The radial distance from the inside peripheral surface of the hollow frustoconical flange to the piston skirt increases continuously. The flange is adjoined by the annular seal, which consists of a coaxial cylinder and freely protrudes on the side of the piston head.

Claims

1. A disposable syringe comprising

a syringe cylinder having an inside peripheral surface, an open first end and a second end, an end wall at said second end, the end wall being provided with a hollow needle holder and being closed with the exception of the region adjacent to said needle holder,

a syringe piston comprising a piston skirt that protrudes out of said open first end of said cylinder and is provided with a handle outside said cylinder, and a piston head disposed within said cylinder and facing said second end thereof, the piston head having an end face facing said second cylinder end and carrying a peripheral annular flange that is provided with an annular seal in sliding contact with said inside peripheral surface of said cylinder,

said end wall of said cylinder having an inside surface which, except adjacent to said needle holder, conforms to said end face of said piston head,

said flange having a frustoconical inside surface facing said first end of said cylinder and said piston skirt and a frustoconical outside surface facing said inside peripheral surface of said cylinder and said second end of said cylinder,

said flange flaring toward said first end of said cylinder,

said inside surface of said flange and said annular seal defining a peripheral annular space which is generally triangular in radial section,

said end wall of said cylinder comprising a peripheral annular portion which is generally triangular in radial section and conforms to said annular space,

said needle holder being eccentrically disposed with respect to said end wall and extending through said annular portion and opening into said annular space,

the radical distance from said frustoconical inside surface to said piston skirt continuously increasing toward said second end of said cylinder, and

said annular seal being cylindrical and being joined to, and coaxial with, said flange and freely protruding therefrom toward said end wall of said cylinder.

2. The syringe set forth in claim 1, wherein said annular seal has a smaller wall thickness than said cylinder and decreases toward said annular seal.

3. The syringe set forth in claim 1, wherein said flange has a smaller wall thickness than said cylinder.