Patent Application
20110204097
The present invention relates to dispenser assemblies for dispensing liquid products, such as oral medicines.
Dispenser assemblies are frequently used for dispensing liquids such as medicines. These dispenser assemblies can be used in various settings where the administration of medicine is required, for example, hospitals and homes. Historically, dispenser assemblies for dispensing injectable medicines generally comprise an elongated, hollow barrel and a plunger that moves within the hollow barrel during filling and dispensing of the medicine. The plunger has radially outwardly projecting lugs or ribs which engage and seal against the interior cylindrical surface of the hollow barrel during axial movement of the plunger in the barrel during filling of the dispenser assembly or dispensing of medicine from the dispensing assemble.
Numerous considerations go into the design and manufacture of dispenser assemblies. One consideration is the seal that is created between the barrel and the plunger when the plunger moves in the barrel. The seal is necessary to effectively dispense the medicine and prevent liquid from leaking past the plunger into the barrel when the plunger moves in the barrel.
The problem of leakage is acerbated when a force is exerted on the plunger rod and plunger to move the plunger in dispensing the medicine from the dispenser assembly. The pressure of the liquid medicine is thus increased and which, in turn, increases the possibility of the liquid medicine leaking past the seal between the plunger and the barrel in the direction away from the direction that the medicine is being dispensed from the dispenser assembly.
Leakage must be eliminated for a variety of reasons. Too tight of a seal increases the frictional force between the plunger and the barrel and increases the force it takes to move the plunger within the barrel. A dispenser assembly too tight of a seal results in high frictional forces between the barrel and the plunger and is therefore disadvantageous because the user must exert higher forces to move the plunger in the barrel thereby making it physically harder to actuate the plunger. However, a loose seal between the barrel and plunger increases the chances of the liquid leaking from the dispensing assembly or leaking past the seal between the plunger and the barrel. Leakage is disadvantageous for a variety of reasons.
Consequently, it would be advantageous to have a dispensing assembly that provides a tight, effective seal between the plunger and the hollow barrel to prevent leakage therebetween and yet which contributes minimal frictional force to allow for easy movement of the plunger within the hollow barrel.
The present invention provides an improved dispenser assembly for dispensing liquid products such as medicines. The present invention provides a dispenser assembly that reduces the amount of force required to move the plunger inside the barrel. At the same time, the present invention provides a dispenser assembly with a seal between the plunger and the barrel sufficient to prevent leakage of the medicine.
In one embodiment of the present invention, the dispenser assembly includes an elongated barrel and an elongated plunger. The elongated plunger includes a flared sealing lip disposed at one end. In one embodiment, the flared sealing lip on the plunger may have a beaded portion on the lip that creates the seal between the plunger and the barrel when the plunger is located in the barrel. The beaded portion of the sealing lip reduces the amount of material on the sealing lip in contact with the barrel relative to a sealing lip that does not have a beaded portion. By reducing the amount of material on the plunger that is in contact with the barrel, the amount of frictional force required to move the plunger in the barrel is reduced. The reduction of frictional force in turn reduces the amount of force necessary to move the plunger within the barrel. Consequently, the beaded portion of the sealing lip makes it easier to slide the plunger within the barrel thus making it easier to dispense the liquid from the dispenser assembly. At the same time, the beaded portion of the sealing lip increases the seal pressure of the dispensing assembly, i.e. the pressure between the plunger and the barrel. An adequate seal pressure prevents the liquid from leaking from the barrel while the plunger is actuated in the barrel.
In another embodiment of the invention, the dispenser assembly includes an elongated barrel and an elongated plunger having a sealing lip disposed with a beaded portion that defines an outer diameter of the sealing lip. In this embodiment, when the plunger is actuated in the barrel the outer diameter of the beaded portion engages the inner wall of the barrel as the plunger moves within the barrel.
In yet another embodiment of the invention, the dispenser assembly includes an elongated barrel having an internal cross-sectional diameter and a one piece elongated plunger having a body portion, a flared sealing member disposed at a tip portion of the body portion, and a sealing bead defined on the sealing member disposed circumferentially around the tip portion. Further, an air gap is defined between the sealing bead and the tip portion.
In a still further embodiment, the dispenser assembly includes an elongated barrel having an internal cross-sectional diameter and a one piece elongated plunger having a body portion, a flared sealing member disposed at a tip portion of the body portion, and a sealing bead defined on the sealing member disposed circumferentially around the tip portion with the sealing bead being oval in cross section.
In yet a still further embodiment, the dispenser assembly includes an elongated barrel having an internal cross-sectional diameter and a one piece elongated plunger having a body portion, a flared sealing member disposed at a tip portion of the body portion where the tip portion is radially arced and its thickness tapers inwardly toward the distal end of the tip portion.
Referring now to the drawings, there is shown in
As such, plunger 10 has an elongated body 15 preferably made of a high-density polyethylene, although numerous other suitable plastic and other materials could be used. The plunger 10 has a tip portion 18 at one end and a base portion 20 at the other end. The base portion 20 of the plunger 10 can include an outwardly flared portion 19 and a circumferentially extending wall 24 to aid the user in actuating the plunger 10 when positioned within the barrel 14. Typically, a user will exert a force on the extending wall 24 with the thumb to move the plunger 10. However, numerous ways to actuate the plunger 10 are contemplated.
The tip portion 18 of the plunger 10 includes a flexible sealing lip 28 for aiding in the formation of a seal that is made between the plunger 10 and the barrel 14 when the plunger 10 is positioned within the barrel 14. The sealing lip 28 has a diameter DSL. The sealing lip 28 extends slightly outwardly so as to project axially from the plunger 10 at the juncture 48 of the cylindrical elongated body 15. The distal tip 29 of the sealing lip 28 is spaced outwardly from a nose portion 44 so that when the plunger 10 is fully seated in the barrel 14, the sealing lip 28 exerts a bias against the inner surface of the barrel 14 to assist in forming a seal as will later become clear.
In one embodiment, the sealing lip 28 projects outwardly at an angle A of about ten degrees (10°) to the longitudinal axis of the plunger 10. However, it is contemplated that the sealing lip 28 could extend from the longitudinal axis of the plunger 10 at other suitable angles.
Further, in one embodiment of the invention, the sealing lip 28 includes an annular beaded portion 30 formed thereon. The beaded portion 30 will be described more fully below. In one embodiment of the present invention, as described below, the beaded portion 30 is a rounded protrusion at the distal tip 29 of the sealing lip 28 furthest from juncture 48.
The plunger 10, as illustrated, has an extended portion or bulbous nose portion 44 at its tip portion 18. The nose portion 44 is inwardly offset from the side wall of the elongated body 15 as shown. In one embodiment, the cross sectional thickness of the nose portion 44 is slightly greater than the cross sectional thickness of cylindrical elongated body 15 of the plunger 10. The nose portion 44 will be described more fully below.
In the embodiment shown in
Referring specifically to
The barrel 14 also includes an extended ramped wall portion 70. This extended ramped wall portion 70 seats the plunger 10 when the plunger 10 is fully extended into the barrel 14, as will be discussed more fully below. Preferably, as will be described more fully below, the barrel 14 also has color strip markings (not shown) thereon that indicate the volume and/or color of liquid in the barrel. Such markings help the user of the multiple dispenser assemblies to distinguish one from another.
In an exemplary embodiment, the barrel 14 is preferably made of polypropylene and the plunger 10 is preferably made of a high-density polyethylene. It has been found that this combination of materials and the specific configuration facilitate easy sliding of the parts relative to one another. Further the plunger 10 is easy and economical to manufacture by reason of the simple mold design which does not require side action components. The tooling therefore is relatively simple and does not require the complex tooling which prior art dispenser assemblies require. The tooling can accommodate more cavities for a given tonnage and is therefore very economical and cost saving.
In accordance with one aspect of the present invention, the sealing member 405 includes a beaded portion 415. In one embodiment of the present invention, as shown, the beaded portion 415 is a rounded protrusion on the sealing member 405. In one embodiment, the beaded portion 415 of the sealing member 405 serves as the outermost or distal portion of the sealing member 405.
As such, when the plunger tip 400 moves within a barrel, the beaded portion 415 of sealing member 405 is the only contact between the plunger tip 400 and the barrel. As will be described more fully below, by providing the beaded portion 415 as the sole contact between the barrel and the plunger tip 400, the plunger tip 400 slides more easily in the barrel. As the plunger tip 400 travels within the barrel (not shown) during movement caused by the user, the flexible sealing member 405 is pressed inwards towards nose portion 440 and the beaded portion 415 provides the seal between the barrel (not shown) and the plunger tip 400.
The plunger tip 400, as illustrated, has the extended portion or bulbous nose 440 at its tip or distal end. As will be described more fully below, the bulbous nose 440 fits into an extended portion of the barrel so as to minimize “dead space” and maximize the amount of the fluid that is expended from the dispenser assembly.
As can seen in
Referring now to
The plunger 160 has an elongated body 162 having a generally uniform diameter which has an outwardly flared section or sealing lip 170 at its open end and terminates in a circumferentially extending radially outwardly directed wall (not shown) serving as a finger grip for the user to activate the plunger in the barrel. The flexible sealing lip 170 can be formed integrally with the plunger and in the relaxed state projects at an angle C relative to the axis A-A of the plunger 160.
The tip end 190 of the plunger 160 has a circumferentially extending wall 195 offset radially to provide a circumferentially extending space or pocket 199 between the sealing lip 170 and tip end 190. The pocket 199 provides more space for the sealing member 170 to flex when the plunger 160 is positioned in the barrel 165. The tip end 190 has raised a central indentation 172.
As shown in
In accordance with one embodiment of the present invention, the sealing lip 170 includes a beaded portion 180 thereon. The beaded portion 180 as shown is a rounded protrusion on the sealing lip 170. In one embodiment of the invention, the beaded portion 180 may provide the sole contact between the plunger 160 and the barrel 165.
The beaded portion 180 of the sealing lip 170 reduces the amount of material on the sealing lip 170 in contact with the barrel 165 relative to a sealing lip that does not have a beaded portion (as shown in
In one embodiment as described above, the plunger includes a nose portion 192 on the tip end 190. In this manner, when the plunger 160 is fully inserted into the barrel 165, the nose portion 192 of the plunger 160 extends into and may contact the axially extending wall 195 of the barrel 165. This design reduces dead space and aids in the full expulsion of the liquid from the barrel when dispensing the liquid from the assembly. A reduction in dead space increases the precision in the amount of fluid delivered from the dispenser assembly.
In one embodiment of the present invention, when the plunger is not inserted in the barrel (relaxed position, not shown), the inside diameter D of the barrel 165 is slightly smaller than the external diameter of the beaded portion 180 of the sealing lip 170. As such, when the plunger 160 is inserted into the barrel 165, the flexible sealing lip 170 is flexed toward the nose portion 192 of the plunger 160. In accordance with one embodiment of the invention, the beaded portion 180 thereby creates the sole contact between the barrel 165 and the plunger 160 during actuation.
Similar to the previously described embodiments, the barrel of the dispenser assembly is preferably made of propylene and the plunger is preferably made of a high-density polyethylene. The combination of these materials and the specific configuration of the sealing lip facilitates movement of the parts relative to one another and does not require the close molding tolerances to provide good sliding action.
Consider briefly the use of an oral dosing assembly in accordance with one embodiment of the present invention with the use of
Turning now to
In accordance with this embodiment of the present invention, the sealing member 702 includes a beaded portion 706. In this exemplary embodiment of the present invention, as shown, the beaded portion 706 is oval cross section with the longer surface of the oval facing outwardly so as to contact a barrel. As with the
In addition, with this embodiment the wall thickness t along the intermediate portion 708 tapers inwardly in the direction from the body portion 704 toward the outer or distal end 710 of the sealing member 702.
Turning then to
As such, when the plunger tip 700 moves within the barrel 800, the beaded portion 706 of sealing member 702 is the only contact between the plunger tip 700 and the barrel 800. Since the beaded portion 706 is of an oval cross section, there is more surface area of the beaded portion 706 contacting the barrel 800 to enhance the seal therebetween than that of the
It is noted that even though the dispenser assembly of the present invention has been shown and described in connection with dispensing medicaments for children, the dispensing assembly has many other useful applications for dispensing other types of liquid products. Further, even though the high-density polyethylene and polypropylene are the preferred combination of materials, in some applications, other dissimilar combinations of materials may be used which provide the good sliding action between the flexible wiper lip and the interior wall of the barrel.
Even though particular embodiments of the present invention have been illustrated and described herein, it is not intended to limit the invention and changes and modifications may be made therein within the scope of the following claims.
