Surgery – Means for introducing or removing material from body for... – Material introduced into and removed from body through...
Reexamination Certificate
2000-02-08
2001-05-15
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Material introduced into and removed from body through...
C604S246000
Reexamination Certificate
active
06231539
ABSTRACT:
This application is based on patent application Ser. Nos. 11-33137, 11-208787, and 11-329439 filed in Japan, the contents of which are hereby incorporated by references.
BACKGROUND OF THE INVENTION
This invention pertains generally to a liquid medicine injection device used in medical applications and, more particularly, relates to a backflow prevention structure and a backflow prevention unit for a liquid medicine injection device which allows easy liquid medicine filling operation.
FIGS. 14A and 14B
illustrate an example of a conventional liquid medicine injection device
100
, which comprises a liquid medicine retaining vessel
110
containing a liquid medicine to be injected, a backflow prevention structure
120
provided at an opening of the liquid medicine retaining vessel
110
at its one end (right end as shown in FIGS.
14
A and
14
B), and a tip cover
130
which closes off the opening of the liquid medicine retaining vessel
110
.
The liquid medicine retaining vessel
110
accommodates in its internal space a piston
111
which can move back and forth in sliding contact, and has a connecting sleeve
112
whose diameter is smaller than that of the liquid medicine retaining vessel
110
itself at its right end. The aforementioned backflow prevention structure
120
is fitted in the connecting sleeve
112
. The tip cover
130
Is constructed of a socket portion
131
which is fitted over the connecting sleeve
112
such that the socket portion
131
will not come off the connecting sleeve
112
, and an inlet tube
132
which extends outward from a right end of the socket portion
131
and has a smaller diameter than the socket portion
131
. The inlet tube
132
is provided for inserting an injection tube
210
of an injector
200
which has a cylinder
230
for holding the liquid medicine to be refilled into the liquid medicine retaining vessel
110
and a piston
220
for forcing the liquid medicine out of the cylinder
230
.
The liquid medicine retaining vessel
110
also has an outlet tube
113
extending from a right end surface of the liquid medicine retaining vessel
110
for discharging the liquid medicine therein. With a delivery pipe
114
connected to the outlet tube
113
, the liquid medicine within the liquid medicine retaining vessel
110
is forced out through the outlet tube
113
and introduced into a human body through the delivery pipe
114
, a flow rate regulator and a catheter as the piston
111
is moved rightward by an unillustrated drive mechanism.
The aforementioned backflow prevention structure
120
includes a support cylinder
121
which is fitted into the connecting sleeve
112
such that a curved outer surface of the support cylinder
121
can slide along a curved inner surface of the connecting sleeve
112
, and a check valve
125
made of an rubber-like elastic material which is fitted concentrically in the support cylinder
121
. The support cylinder
121
is provided with a support bar
122
situated on a central axis of the support cylinder
121
, and the check valve
125
is fitted over the support bar
122
. A plurality of rodlike stoppers
123
radially project from a curved outer surface of the support bar
122
. Outer ends of these stoppers
123
are fixed to a curved inner surface of the support cylinder
121
so that the support bar
122
is located on the central axis of the support cylinder
121
.
Also, an annular projection
115
jutting inward is formed at a root end of the curved inner surface of the connecting sleeve
112
. This annular projection
115
prevents the support cylinder
121
from entering the interior of the liquid medicine retaining vessel
110
.
The aforementioned check valve
125
is constructed of a cylindrical portion
126
whose diameter is slightly smaller than the inner diameter of the support cylinder
121
and a conical valve portion
127
having a solid truncated circular cone shape formed at a far end (right end as illustrated in
FIGS. 14A and 14B
) of the cylindrical portion
126
. A plurality of ribs
128
running parallel to an axial direction are formed on the cylindrical portion
126
at regular intervals around its curved outer surface, and liquid medicine passages
300
are formed between these ribs
128
.
The conical valve portion
127
is shaped such that it comes in contact with a conical slope
133
formed where a curved inner surface of the socket portion
131
and a curved inner surface of the inlet tube
132
meet when the tip cover
130
is fitted on the connecting sleeve
112
. This makes it possible to securely prevent the liquid medicine in the liquid medicine retaining vessel
110
from leaking through the backflow prevention structure
120
. Furthermore, there is formed a slotted groove
127
a
, through which the liquid medicine flows, in a projecting end (right end as illustrated in
FIGS. 14A and 14B
) of the conical valve portion
127
across the diameter of the projecting end.
According to the liquid medicine injection device
100
thus constructed, the liquid medicine is injected into the liquid medicine retaining vessel
110
as follows. First, the injection tube
210
of the injector
200
charged with the liquid medicine is inserted into the inlet tube
132
until a tip end of the injection tube
210
pushes the projecting end of the conical valve portion
127
inward as shown in FIG.
14
A. Since the check valve
125
made of the rubber-like elastic material is deformed consequently, the projecting end of the conical valve portion
127
is forced into an internal space of the socket portion
131
of the tip cover
130
as shown in FIG.
14
B. As a result, the liquid medicine passages
300
are formed in the backflow prevention structure
120
as shown by thick arrows in FIG.
14
B. When the piston
220
of the injector
200
is pushed into the cylinder
230
in this condition, the liquid medicine within the cylinder
230
is injected into the liquid medicine retaining vessel
110
through the injection tube
210
, the slotted groove
127
a
in the conical valve portion
127
and the liquid medicine passages
300
formed in a gap between the curved outer surface of the cylindrical portion
126
and the curved inner surface of the support cylinder
121
. As the liquid medicine is injected in this fashion, the piston
111
in the liquid medicine retaining vessel
110
is caused to retract (leftward as illustrated).
When injection of the liquid medicine into the liquid medicine retaining vessel
110
is completed, the injection tube
210
of the injector
200
is pulled out of the inlet tube
132
. Then, the check valve
125
which has been elastically deformed extends, or returns to its original shape, so that the conical valve portion
127
of the check valve
125
comes back into contact with the conical slope
133
of the tip cover
130
and thereby closes an opening in the tip cover
130
as shown in FIG.
14
B. Therefore, the liquid medicine once introduced into the liquid medicine retaining vessel
110
will never leak to its exterior through the inlet tube
132
.
In the above-described conventional liquid medicine injection device
100
, the injection tube
210
of the injector
200
is pulled out of the inlet tube
132
when interrupting the injection of the liquid medicine into the liquid medicine retaining vessel
110
halfway or when the injection of the liquid medicine has been completed. If the injection tube
210
is pulled out quickly in such cases, the liquid medicine left in the liquid medicine passages
300
may flow out backward to the exterior through a gap between the conical slope
133
of the tip cover
130
and the conical valve portion
127
of the check valve
125
before the check valve
125
which has been reduced in length due to elastic deformation returns to its original length.
To avoid such a leakage problem, it would be necessary to pull the cylinder
230
(leftward as illustrated in
FIGS. 14A and 14B
) while exerting a pushing force on the piston
220
and, then, slowly extract the injection tube
210
out of the inlet tube
132
. S
Inoue Mitsuyoshi
Komatsu Yasuo
Yamamoto Atsushi
Daiken Iki Kabushiki Kaisha
Mendez Manuel
Smith Patent Office
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