Patent Application
20130123712
1. Field of the Invention
The invention relates, in general, to a plunger rod for use with a syringe and, more particularly, to a plunger rod that includes a plurality of anchors around the circumference thereof to prevent the plunger rod from being pulled out of the syringe barrel during aspiration of the syringe.
2. Description of Related Art
Current syringe designs can typically be categorized as two-piece syringes or three-piece syringes. A typical three-piece syringe includes a tubular barrel having an access opening formed at one end, and a smaller discharge opening formed at the opposing end. The lead end of an elongated plunger rod is received within the access opening of the barrel so as to be slidable within the barrel. Attached to the lead end of the plunger rod is a flexible sealing member or stopper that snugly seals against the interior surface of the barrel. A needle, a threaded member, or a non-threaded member is usually attached to the discharge opening on the barrel. The needle can be used to penetrate a surface while the threaded member can be used to attach the syringe to another medical device, such as a catheter. The flexible stopper is usually manufactured from an elastomeric material, such as rubber or a cross-linked or thermoplastic elastomer.
A two-piece syringe, on the other hand, includes a “stopper” that is in the form of a rigid sealing disc, also known as a plunger rod head. It is typically made of the same rigid plastic as the rest of the plunger rod. The sealing force in a two-piece syringe comes from a thin elastic barrel that deforms around the rigid plunger rod head.
During use, the discharge end of the syringe is initially placed in contact with a fluid. For example, the needle on the syringe can be inserted into a liquid medication. As the plunger is retracted within the barrel, a process known as aspiration, a negative pressure is formed within the end of the barrel so as to cause the fluid to be drawn into the barrel. The syringe can then be moved to a second location where advancing the plunger within the barrel causes the fluid to be pushed or expressed out of the discharge end of the barrel.
With reference to
The current retaining ring provided on conventional plunger rods suffers from various deficiencies. For instance, a large amount of material is required to mold such plunger rods that include retaining rings. In addition, due to the complex geometry of such plunger rods, the molding of these items requires a large number of knockout pins to eject the molded plunger rod from the mold and a high molding cycle time.
Accordingly, a need exists for a plunger rod design that includes a feature having a simple geometry formed from a reduced amount of material for preventing the plunger rod from being removed from the syringe barrel.
An object of the present invention is to provide a plunger rod having a feature for preventing the plunger rod from being removed from the syringe barrel. More specifically, a need exists for a plunger rod that includes a plurality of retaining anchors to replace the conventional retaining ring. The use of such retaining anchors reduces overall material use by 3%-5%, thereby yielding a “greener” syringe. In addition, using these retaining anchors instead of the conventional retaining ring leads to improved plunger rod moldability due to the less complex geometry and a reduction in the number of knockout pins required to eject the plunger rod from the mold which makes the mold more cost effective and robust.
Accordingly, provided is a plunger rod that includes: an elongated body formed by a plurality of orthogonally spaced elongated ribs extending along a longitudinal axis; a first ledge adjacent a first end of the elongated body; a second ledge adjacent a second end of the elongated body; and an attachment portion extending from the second ledge. The second end of the elongated body opposes the first end of the elongated body. At least one elongated rib includes a retaining anchor positioned adjacent the second end adjacent the second ledge.
According to one aspect of the present invention, each of the elongated ribs may include a retaining anchor positioned adjacent the second end adjacent the second ledge. The retaining anchors may be configured to prevent the elongated body from being removed from a syringe barrel by interacting with a retaining structure provided at an end of the syringe barrel.
According to another aspect of the invention, the retaining anchor may include a first angled portion extending from the second ledge toward the second end of the elongated body, a second portion extending parallel to one of the orthogonally spaced elongated ribs toward the second end of the elongated body, and a third portion extending perpendicularly to one of the orthogonally spaced elongated ribs. The first angled portion may extend from the second ledge at an angle of about 3° to about 60°. The third portion of the retaining anchor may interact with a retaining structure of a syringe barrel to prevent the plunger rod from being removed from the syringe barrel. Alternatively, the at least one retaining anchor may have a cross-sectional shape selected from the group consisting of: rectangular, rounded, or angled shape.
The plunger rod may be manufactured from a polymeric material selected from the group consisting of: polyolefines (such as polyethylene and polypropylene), polyamides, polyesters, polystyrene, polyurethane, polycarbonate, acrylonitrile-butadiene-styrene, fluoropolymers, ionomers, polyacrylates, or any combination thereof.
The attachment portion may be configured to secure a stopper thereto. The stopper and the plunger rod may be manufactured integrally or separately and from the same or different material.
In addition, provided is a syringe that includes: a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end. The open end includes a retaining structure. The syringe also includes a stopper configured to be received within the open end of the syringe barrel; and a plunger rod configured to engage a portion of the stopper. The plunger rod includes: an elongated body formed by a plurality of orthogonally spaced elongated ribs extending along a longitudinal axis; a first ledge adjacent a first end of the elongated body; a second ledge adjacent a second end of the elongated body; and an attachment portion extending from the second ledge. The second end of the elongated body opposes the first end of the elongated body. The attachment portion is configured to engage a portion of the stopper. At least one elongated rib includes a retaining anchor adjacent the second end adjacent the second ledge for engaging the retaining structure of the syringe barrel.
Further provided is a plunger rod and stopper assembly adapted for use with a syringe barrel. The assembly includes: a stopper; and a plunger rod configured to engage a portion of the stopper. The plunger rod includes: an elongated body formed by a plurality of orthogonally spaced elongated ribs extending along a longitudinal axis; a first ledge adjacent a first end of the elongated body; a second ledge adjacent a second end of the elongated body; and an attachment portion extending from the second ledge. The second end of the elongated body opposes the first end of the elongated body. The attachment portion is configured to engage a portion of the stopper. At least one elongated rib includes a retaining anchor adjacent the second end adjacent the second ledge.
These and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof, shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.
With reference to
The attachment portion 112 is configured to receive an open bottom end of a stopper 118 (see
The plunger rod 100 also includes at least one retaining anchor 120 positioned adjacent to a bottom surface of the second ledge 116 on each of the orthogonally spaced ribs 104. Desirably, each of the ribs 104 includes one retaining anchor 120. According to one aspect of the present invention and with specific reference to
With reference to
In operation, as a user pulls the plunger rod 100 out of the open rearward end 208 of the syringe barrel 202, the third portion 126 of the retaining anchor 120 interacts with the retaining structure 210 of the syringe barrel 202 to prevent the plunger rod 100 from being removed from the syringe barrel 202. In addition, this interaction between the retaining anchors 120 and the retaining structure 210 of the syringe barrel 202 prevents the plunger rod 100 from being easily removed from the syringe barrel 202 when the syringe 200 is inadvertently filled up beyond its nominal volume.
The plunger rod 100 may be manufactured from a polymeric material such as, but not limited to, polyolefines (e.g., PE, PP, and their copolymers), polyamides (e.g., nylons), polyesters (e.g., PET), polystyrene, polyurethane, polycarbonate, acrylonitrile-butadiene-styrene, fluoropolymers, ionomers, polyacrylates, or any other similar material. The stopper 118 and the plunger rod 100 may be manufactured integrally or separately and from the same or different material.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
| Number | Date | Country | |
|---|---|---|---|
| 61558581 | Nov 2011 | US |
