Syringe plunger having an improved sealing ability
First Claim
1. A plunger for use with a syringe having a barrel filled with a liquid that exerts a fluid pressure on the plunger when the plunger is in motion, the barrel having a cylindrical wall with an interior surface and a longitudinal axis extending between a proximal end and a distal end, a discharge outlet at the distal end through which the liquid passes when dispensed, and an access opening at the proximal end for applying a dispensing force to move the plunger in a proximal-to-distal direction toward the discharge outlet, said plunger comprising:
- a piston operably mounted within the syringe barrel for dispensing the liquid from the discharge outlet, said piston including a chamber susceptive of trapping a portion of the liquid when the piston is in motion, said piston having a circumferential first sealing flange exerting a fluid-tight contact pressure with the interior surface of the syringe barrel distally of the chamber and a circumferential second sealing flange exerting a lesser contact pressure with the interior surface of the syringe barrel proximally of the chamber to allow the portion of the liquid trapped in the chamber to be exhausted between the second sealing flange and the interior surface in a proximal direction when the dispensing force is applied to said piston in a proximal-to-distal direction for dispensing liquid from the barrel through the distal discharge outlet, so that the fluid-tight seal between said first sealing flange and the interior surface is undisturbed.
6 Assignments
0 Petitions
Accused Products
Abstract
A plunger is provided for a syringe that includes a pressure relief mechanism that exhausts any fluid trapped in the chamber between sealing flanges carried by the plunger when the plunger is advanced to dispense fluid from the syringe. The contact pressure between the barrel-contacting surface of the rearmost sealing flange nearest the access opening of the syringe barrel is weakened relative to the contact pressure provided by the barrel-contacting surface of the sealing flange that isolates the fluid within the barrel. The contact pressure of the rearmost sealing flange may be lessened by either reducing its radial diameter relative to the radial diameter of the other sealing flange, removing an underlying portion of the plunger, or configuring the rearmost sealing flange as deflectable sealing lip.
111 Citations
63 Claims
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1. A plunger for use with a syringe having a barrel filled with a liquid that exerts a fluid pressure on the plunger when the plunger is in motion, the barrel having a cylindrical wall with an interior surface and a longitudinal axis extending between a proximal end and a distal end, a discharge outlet at the distal end through which the liquid passes when dispensed, and an access opening at the proximal end for applying a dispensing force to move the plunger in a proximal-to-distal direction toward the discharge outlet, said plunger comprising:
a piston operably mounted within the syringe barrel for dispensing the liquid from the discharge outlet, said piston including a chamber susceptive of trapping a portion of the liquid when the piston is in motion, said piston having a circumferential first sealing flange exerting a fluid-tight contact pressure with the interior surface of the syringe barrel distally of the chamber and a circumferential second sealing flange exerting a lesser contact pressure with the interior surface of the syringe barrel proximally of the chamber to allow the portion of the liquid trapped in the chamber to be exhausted between the second sealing flange and the interior surface in a proximal direction when the dispensing force is applied to said piston in a proximal-to-distal direction for dispensing liquid from the barrel through the distal discharge outlet, so that the fluid-tight seal between said first sealing flange and the interior surface is undisturbed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A sheath for attachment to the exterior of an inner member to provide a syringe plunger, the sheath for providing a sealing engagement an the interior surface of a syringe barrel that has a longitudinal axis with a distal end and a proximal end, a distal discharge opening for dispensing a liquid held by the barrel, and a longitudinal axis, the sheath comprising:
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a cylindrical sidewall having an exterior surface, a proximal end and a distal end;
a head that is integral with the distal end of the sidewall, wherein said sidewall and said head are configured for receiving the exterior of the inner member in a snug fit;
a first circumferential sealing flange projecting radially outwardly from said exterior surface of said sidewall, said first sealing flange being substantially circumferentially continuous and exerting a sufficient first contact pressure on the interior surface of the syringe barrel to maintain a fluid-tight seal therewith; and
a second circumferential sealing flange projecting radially outwardly from the exterior surface of the sidewall, said second sealing flange in a spaced position proximally of the first sealing flange so as to define therebetween a chamber susceptive of trapping a portion of the liquid when the piston is in motion, wherein said second sealing flange exerts a second contact pressure lesser than the first contact pressure of the first sealing flange that permits any liquid trapped in the chamber to be exhausted between the second sealing flange and the interior surface in a proximal direction when a dispensing force is applied to the syringe plunger to move the plunger for dispensing liquid from the barrel through the distal discharge outlet, so that the fluid-tight seal between said first sealing flange and the interior surface is undisturbed. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A syringe for dispensing a liquid when acted upon by a dispensing force, said syringe comprising:
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a tubular barrel having a cylindrical wall with a proximal end, a distal end, a longitudinal axis, an interior surface, a proximal access opening, and a distal discharge outlet, wherein the barrel is adapted for holding a liquid; and
a plunger operably mounted within the barrel for dispensing the liquid from the discharge opening, said plunger including a chamber susceptive of trapping a portion of the liquid when the plunger is in motion, said plunger having a circumferential first sealing flange exerting a fluid-tight contact pressure with the interior surface of the tubular barrel distally of the chamber and a circumferential second sealing flange exerting a lesser contact pressure with the interior surface of the syringe barrel proximally of the chamber to allow the portion of the liquid trapped in the chamber to be exhausted between the second sealing flange and the interior surface in a proximal direction when the dispensing force is applied to said piston in a proximal-to-distal direction for dispensing liquid from the barrel through the distal discharge outlet, so that the fluid-tight seal between said first sealing flange and the interior surface is undisturbed. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. A method for dispensing a liquid imaging medium with a dispensing force, the method comprising:
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providing a syringe barrel having a forward end with a discharge outlet, an interior surface and an open rearward end;
providing a plunger within said syringe barrel, said plunger including a chamber susceptive of trapping a portion of a liquid present in the syringe barrel when the plunger is in motion and said plunger located forward of the chamber and having a first circumferential sealing flange configured to normally provide a first contact pressure with said interior surface of the syringe barrel, and a second sealing flange located rearward of the chamber and configured to provide a lesser second contact pressure of a fluid-tight magnitude with said interior surface of the syringe barrel, wherein said second sealing flange preferentially exhausts trapped liquid imaging medium from the chamber in a rearward direction when a dispensing force is applied to said piston for dispensing liquid from the barrel through the discharge outlet;
filling the syringe barrel forward of the plunger with a quantity of a liquid imaging medium;
connecting the syringe to a patient via a catheter and a tube interconnecting catheter and the discharge outlet of the syringe barrel; and
applying a dispensing force to the plunger for dispensing liquid imaging medium from the syringe into the patient, wherein liquid imaging medium trapped in the chamber is preferentially exhausted between the second sealing flange and said interior surface in a rearward direction due to the lesser contact pressure exerted by the second sealing flange against the interior surface of the syringe barrel. - View Dependent Claims (62, 63)
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Specification