Note: Descriptions are shown in the official language in which they were submitted.
o{~
This invention relates to a syringe, and in particular
to a syringe for use with a needleless hypodermic injector.
As discussed in -the Lindmayer et al U.S. Pa-tent No.
4,342,310, issued on ~ugust 3, 1982, and in Canadian patent
application Serial No. ~03,840, filed May 7, 19~2, the needle-
less injection of medicines into the body is decidedly preferable
to injection by means of skin piercing needles. A needleless
injector makes a substantially smaller hole than a needle, and
consequently is less painful and results in less damage than
the needle. However, needleless injectors have only recently
begun to achieve public acceptance. A basic reason for the
limited use of such injectors is the difficulties and incon-
venience involved in injecting different medicines using the
same injector. Until now, it was necessary to sterilize an
injector used -to inject one medicine before using the same
injector for injecting another medicine. Steriliza-tion was
necessary to purge the contaminating first medicine. Accord-
ingly, for the most part, the use of needleless injectors has
been limited to mass inoculations or other situations, e.g.
the adminis-tration of steroids local anaesthetics or insulin
in which the type of medicine is not changed frequently.
Thus, it is readily apparent that a need exists for a
device which permits the extension of needleless injection to
situations in which a varie-ty of medicines are injected into
successive patien-ts.
A search of the relevant patent literature reveals that
others are aware of the problem, and that attempts have been made
to solve such problem. In this connection, reference is made to
Canadian Patent No. 569,887, issued to R.P. Scherer on February
3, 1969, and Uni-ted States Patents Nos. 2,635,601 issued to
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E.A. May on April 21, 1953; 2,764,977, issued to G,l~. Ferguson
on October 2, 1956; 3,688,765, issued to ~.S. Gasaway on
September 5, 1972; 4,089,334, issued to P.R. Schwebel et al on May
16, 1978; and 4,1~4,024, issued to P.R. Schwebel et al on
~ovember 7, 1978. Each of these patents describes an injector
which u-tilizes a disposable ampoule or cartridge containing a
single dosage of medicine. Such devices are unsatisfactory,
because it must be possible to adjust the dosage of most medicines.
The dosage required for any individual is determined, inter alia,
by the age and weight of the individual, and the stage of the
illness. Thus, the person administering the medicine must be
able to vary the dosage. The production and storage of a large
number of ampoules or cartridges containing a variety of dosages
of many medicines would be prohibitively expensive and impractical.
The O.H. Banker U.S. Patents Nos. 3,292,621 and 3~29',622,
issued on December 20, 1966 teach the use of an adjustable stroke
injection device and an adjustable unit, respectively. I~ith the
first of the Banker devices, some medicine may remain in the
ampoules which can be quite expensive. Moreover, there is
no provision for filling of the device with different medicines.
The other Banker unit must be sterilized if the medicine being
administered is changed~
Accordingly, in spite of the extent of earlier work in
this field, the need still exists for a simple disposable syringe
which can be used for needleless inoculations. An object of the
present invention is to attempt to meet such need by providing
a disposable device, which eliminates the need for sterilization
between uses of the injector.
At least one embodiment of the invention prevents the
accidental re-use o~ a contaminated disposable syringe. Such
re-use is possible with conventional disposable syringes.
Moreover, the syringe of the present invention can be filled
accurately to the required dosage, and, in one form, can be
re-used for multiple injections, e.g. when injecting insulin
for the treatment of a diabetic.
Accordingly, the present invention relates to a
disposable syringe for use in a needleless injector of the type
including a casing, a piston slidably mounted in the casing for
movement between a retracted position and an extended position,
and drive means for driving the piston from the retracted to the
extended position, the syringe comprising tubular plastic barrel
means, said barrel means having an open rear end for insertion into
said casing and a closed front end for extending out of said
casing; orifice means in said front end of said barrel means for
admitting medicine into said barrel means, plastic plunger means
slidably mounted in said barrel means, a rear end of said plunger
means extending out of said open rear end of said barrel means
for gripping whereby the plunger means can be moved away from
said closed front end of said barrel means to a loaded position
in which medicine fills the space in said barrel means between
said closed front end and the front end of said plunger means,
said rear end of the plunger means being engageable by said
piston, whereby the plunger means can be moved Erom the loaded
position to a discharge position against said closed front end
of the barrel means to discharge substantially all of the medicine
from said barrel means.
In this description and in the appended claims, the term
"front" is used to identify the medicine receiving and injection
end of the barrel or plunger, and the term "rear" is used to
identify the other end of the barrel or plunger.
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The invention will now be described in greater detail
with reference to the accompanying drawings, which illustrate
preferred embodimen-ts of the invention, and wherein.
Figure 1 is a schematic side elevation view of one
embodiment of the disposable syringe of the present invention;
Figure 2 is a longitudinal sectional view oE the syringe
of Fig. l;
Figure 3 is a front end view of the syringe of Figs.
1 and 2;
Figure 4 is a rear end view of the syringe of Figs. 1 to 3;
Figure 5 is a longitudinal sectional view of the second
embodiment of the syringe of the present invention;
Figure 6 is a partly sectioned, side elevation view
of the syringe of Figs. 1 to ~ in a needleless injector;
Figure 7 is a partly sectioned, side elevation view of a
second type of needleless injector containing a third embodiment
of the syringe of the present nvention; and
Figure 8 is a longitudinal sectional view of the outer
end of the injector and syringe of Fig. 7.
With reference to Figs. 1 to 4, one embodimen-t of the
syringe of the present invention includes a tubular barrel
generally indicated at 1 and a plunger generally indicated at 2.
The barrel 1 is defined by a hollow cylindrical body. The body
may -taper slightly from a closed front end 3 to an open rear end
. The dimensions of a tapered body need not be as exact as
those of a cylindrical body. The barrel 1 is formed of a trans-
parent, plastic material, e.g. polypropylene of the type used in
the barrel of conventional, commercially available disposable
syringes. The plunger 2 is formed of a hard plastic.
External threads 5 are provided on the front end 3 of the
4~
barrel 1 for mounting the latter in an injector, as described in
greater detail hereinaf-ter. It will be appreciated that the
threads can be replaced by a bayonet or other type coupling. A
pair of diametrically opposed wings 6 extend radially outwardly
the front end 3 of the barrel 1 for facilitating manual ro-tation
of the barrel 1 during insertion or removal of the barrel from
an injector. A conical nose 8 at the centre of the front end 3
of the barrel contains a longitudinally extending injection
orifice 9. A separable needle 10 extends forwardly from the nose
8 Eor loading or filling of the syringe. For such purpose, an
annular groove 11 is provided at the junction between the rear
end of the needle 10 to render the needle 10 frangible. A cyl~
indrical cap 14 normally protects the needle 10 and the front
injection end of the syringe. The open end of the cap 14 includes
an annular bead 15, which is retained in an annular recess 16
at the base of the nose 8. ~awtooth projections 18 are provided
on the front end of the barrel 1 for preventing slipping of the
syringe on the skin of a patient. A longitudinally extending,
smooth bottomed slot 19 is provided on each side of the barrel 1.
The slot 19 extends from between the projections 18 -to the rear
end of the threads 5, so that the interior of the front end 3
of the barrel can easily be seen from the outside.
The plunger 2 includes a cylindrical body 20 with a
conical front end 21 for abuttirlg the conical interior end 22
of the barrel 1. The use of mating conical surfaces 21 and 22
ensures that virtually all of the medicine contained in the chamber
24 is discharged when the plunger is moved from the rear or
loaded position (Figs. 1 and 2) to the front or discharge position
(Fig. 5). An O-ring 25 provides a fluid-tight seal between the
front end of the plunger 2 and the barrel 1. A pair of concave
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depressions 27 are provided near the rear end 28 of the body 20
to facilitate gripping of the plunger 2 during filling. The rear
end 28 of the body 20 is pro-tected by a cylindrical cap 30 until
the syringe is about to be used.
Transversely extending lines 32 are pr~vided on the
body 20 for indicating the dosage in the chamber 24. The lines
32 are visible through a rectangular slot 33 ln -the side of the
reduced diameter rear end 4 of the barrel 1. A line 35 on one
side of the slot 33 provides an accurate reading of the volume
of medicine (dosage) in the chamber 24. A pair of opposed rec-
tangular grooves 36 extend along substantially the entire length
of the body 20. The bottom 37 of each groove 36 has a sawtooth
configuration. Small ridges 38 on opposed projections 39 in the
rear end 4 of the barrel 1, engage the teeth in the grooves 36.
Thus, as the plunger 2 is moved rearwardly in the barrel 1 and
medicine is drawin into the barrel, and the ridges 38 make a
clicking sound as they move over the teeth in the grooves 36.
The teeth correspond to the lines 32, so that blind patients such
as diabetics can measure the dosage by counting the clicks.
Moreover, this arrangement prevents rotation of the plunger
relative to the barrel.
The syringe of Figs. 1 to 4 is loaded by inserting the
needle 10 into a medicine bottle 40 (Fig. 5~ and withdrawing the
plunger 2. The syringe of Fig. 5 is the same as that of Figs. 1
to 4, except that the Eront end includes a frusto-conical pro-
jection 42, which has the same taper as the funnel 43 of a
conventional disposable needle 44. The projection 42 contains
an inser-t 45, with the injection orifice 46 therein. A recess
47 around the projection 42 includes a thread 48 for securing
the flanged end 49 of the needle funnel 43. The end 49 of
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the funnel 43 is inserted into the recess 47 and rotated to lock
the needle in place. The needle 44 is then inserted lnto the
medicine bottle 40, and the plunger 2 is partially withdrawn to
fill the barrel 1.
The syringe of Figs. 1 to 4 or 5 can be used in a
variety of injec-tors including the injector indicated generally
at 50 in Fig. 6. The injector 50 is similar to the injector
described in U.S. Patent No. 4,342,310, mentioned hereinbefore,
and includes an elongated tubular casing 51 with a handle 52 and
a trigger 53 substantially perpendicular thereto. A tubular
barrel 54 is connected to the front end of the casing 51. The
rear end of the casing 51 defines a compression chamber 55, which
contains a substance such as chlorotrifluoromethane which changes
to a liquid when subjected to pressure at normal room temperature,
and changes back to a aas when 'he pressure is released. There is
sufficient of the substance in the chamber 55 that some liquid
is always present in such chamber.
The rear end 56 of the barrel 54 is threaded for
connecting the barrel 54 to the casing 51. A gasket 57 provides
a fluid-tight seal bet~een the barrel 54 and the casing 51. A
piston 58 is slidably mounted in the compression chamber 55
for longitudinal reciprocating movement between a rest position
and a charged position tFig. 6) in which the piston 58 compresses
the gas to convert at least a portion of the gas into a liquid.
An O-ring 59 seals the piston 58 with respect to the interior of
the handle end of the casing 51. A gasket 60 on the rear, com-
pressions chamber end of the piston 58 seals the chamber 55
from the remainder of the casing 51.
The piston 58 is slidably mounted in the rear end of the
barrel 54. An O-ring 62 provides a seal between the piston 58
and the barrel 54. A recess 63 i5 provided in the front end oE
the piston 58 for receiving the rear end 28 of the plunger 20.
The front end 64 of the barrel 54 is internally threaded, so that
the barrel 1 of the disposable syringe can be securely mounted
in such barrel 54. In order to use a thin walled barrel 1 which
is capable of resisting the high pressures required in the barrel
5~ to create a high velocity jet, the ~ront section 65 of the
barrel 54 is tapered in-ternally to match the taper of the syringe
barrel 1.
The handle 52 of the injector contains a charging chamber
66 for a liquid such as an oil. The chamber 66 can be connected
to a pressure chamber 67 between the rear end 68 of the barrel
54 and the rear end 69 of the piston 58. ~hen the piston 58
moves into the chamber 55, the pressure chamber 67 enlarges to
receive liquid from the charging chamber 66. I,iquid from the
chamber 66 passes through a valve defined by a ball 71 and a
helical spring 72, which biases the ball against a seat 74. A
rod 76 is slidably mounted in the chamber 66 for moving the ball
71 upwardly to open the valve. The bottom end of the rod 76 is
connected to a piston (not shown), which is operated by the
trigger 53. Because the piston actuating mechanism does not form
part of the present invention, no details of such mechanism are
provided herein. It is sufficient to know that the rod 76 is
moved by operation of the trigger 53, which is pivotally connected
to the casing 51. The trigger 53 is biased away from the handle
52 by a spring 78. The trigger 53 is connected to a bar 80,
which is slidably mounted in a slot in the front side of the
handle 52. The bottom end of the bar 80 (not shown) operates
the piston to move the rod 76 against the ball 71. In order to
move the piston 58 rearwardly to the cocked position~ it is
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necessary to pump the trigger 53 which pumps liquid from the
charging chamber 66 into the pressure chamber 67. Thus, the
gas in the compression chamber 55 is compressed and changes
in-to liquid form. In order to administer medicine, the front
end 3 of the barrel 1 is placed against the skin, and a safety
catch 82 on the bottom end of the handle 52 is rotated 90 to
connect the trigger 53 to the rod 76, releasing the ball 71
when the trigger is pressed. In the manner, the piston 58 is
released, and moves forward in the barrel 54, the plunger 20
moves forward in the barrel 1 to discharge the medicine, and the
charging liquid re-turns to the handle 52.
The disposable syringe of the present invention can
also be used with a needleless injector of the type disclosed by
Canadian patent application 403,840, also mentioned hereinbefore.
Referring to Figs. 7 and 8, the injector includes a casing
generally indicated at 84. The casing 84 is defined by cylin~
drical, telescoping front and rear sections 85 and 86, respectively.
The rear section 86 of the casing 84 is mounted in the front
section 85 for movement between the extended or rest position
~Fig. 7) and the retracted position (Fig. 8). The front section
85 of -the casing 84 includes a forwardly extending neck 87 and
an internal cylinder 88for receiving a syringe in accordance
with the present invention. For such purpose, the front end 89
of the cylinder 88 is internally threaded for retaining the
externally threaded front end 90 of the barrel 91 of the syringe.
During injection, the front end 90 of the barrel 91 is
covered by an injection head 92. The head 92 includes a
cylindrical outer sleeve 93, which surrounds the neck 87 of the
casing 84 and an externally threaded inner sleeve 94 for
30 connecting the head 92 to the front end 89 of the cylinder B8.
g
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Projections 95 are provided on the disc-shaped front end 96 of
the head 92 for preven-ting slipping of the injector on the skin
during use. An insert 97 with an injection orifice 98 is pro-
vided in the front end 96 of the head 92.
As in the other embodiments of the invention, a plunger
100 is slidably mounted in the barrel 91 for mo~emen-t between a
front, rest or discharge position (Fig~ 7) and a loaded or filled
position (Fig. 8). The plunger 100 includes a tapered front end
101 and is sealed in the barrel 91 by an O-ring 102. The rear end
of the cylinder 88 carrying the syringe is externally threaded
for mounting in an internally threaded ring 103, which is connected
-to an annular, inwardly extending shoulder 104 on the front end
of the rear casing section 86. Rotation of the rear casing section
86 with respect to the section 85 causes movement of the section
86 into the section 85. Such movement of the rear section 86
into the front section 85 of the casing is limited by a latch
mechanism. The latch mechanism includes a hole 105 and a ball
106 in the rear casing section 86. When the ball 106 is aligned
with the hole 105, the ball is forced into the hole 105 by a
20 stepped collar 107. The collar 107 and the ball 106 are mounted
in a cup-shaped bushing 108, which slidable in the rear casing
section 86. A helical spring 110 in the collar 107 biases the
collar and the ball 106 towards the rear of the casing section 86.
Xn the e~tended position of the casing 84 (Fig. 7), the ~all 106
bears against the interior surface 112 of the casing section 86.
When the ball 106 becomes aligned with the hole 105, the ball is
pushed into the hole.
When the casing sections 85 and 86 mo~e together a stack
of disc springs 113 is compressed between the bushing 108 and an
30 end cap 114 on the casing 84. The cap 114 is cup-shaped and
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externally threaded for mounting in the internally threaded end
115 of the casing section 86. Opposed rectangular wings 116
are provided near the end 115 of the casing section B6 to
facilitate rotation of the section 86. The injector is actuated,
i.e. the bushing 108 is pushed forwardly by the springs 113, when
the sec-tions 35 and 86 are released by a push button (not shown)
in the cap 114. ~s described in Canadian patent application
~03,840, the desired injection pressure can be achieved by pro
viding the appropriate disc springs 113 in series.
In order to move the plunger 100 wi-th the bushing 108,
the rear end 117 of the plunger 100 is bifurcated for engaging
the bushing 108. An annular flange or washer 118 on the plunger
100 moves the bushing 108 rearwardly to engage the springs 113
when the syringe is inserted into the casing 84. The rear casing
section 36 is rotated counterclockwise to move the front section
85 and the barrel 91 away from the rear section 86. As the
casing sections 85 and 86 move apart, the plunger 1()0 initially
moves the barrel 91 because of the friction of the O-ring 102
The enlarged heads 119 on the arms at the rear end 117 of the
20 plunger 100 engage the rear surface of the bushing 108 to prevent
movement of the plunger 100 with the barrel 91. Continued
separation of the casing sections 85 and 86 creates a partial
vacuum in a chamber 120 (Fig. 8) in the syringe for receiving
medicine.
~hen filling the syringe, the injection head 92 is
removed, and a bottle holder generally indicated at 122 is
placed in the front end 87 of the casing 84. The bottle holder
122 includes a hollow cylindrical body 123 with an open bottom
end 124 for receiving a standard medicine bottle 125. Longi-
30 tudinally extending slots 126 in a skirt portion 127 of the body
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:~19~;2'1~
123 Eacilitate insertion of the bottle 125 into the holder by
making the body flexible. ~ needle 128 extends downwardly from
the closed top end 129 of the holder for puncturing the top end
of the medicine bottle 125. An externally threaded sleeve 130
extends upwardly from the top end 129 of the holder for connecting
the holder to the front end ~9 of the cylinder 88. In such
position, the sleeve 130 receives a projection 131 on the front end
of the barrel 91 ensuring proper filling of the chamber 20.
This embodiment of the invention is best adapted for
the treatment of diabetics, who generally use one type of
medicine only. Injections can be repeated using the same barrel
91 until such barrel becomes contaminated at which time the
disposable head 92, the barrel 91 and the plunger 100 are replaced
with sterile elements.
All of the elements of each embodiment of the invention
are stored in hermetically sealed, sterile plastic bags of
the type used for conventional disposable syringes. The syringe
of the present invention provides a relatively inexpensive, quick
means for sterile injections, without the inconvenience of steri-
lization. Moreover, the syringe described hereinbefore isrelatively accurate in terms of dosage, and can be filled from
virtually any bottle or vial.
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