Note: Descriptions are shown in the official language in which they were submitted.
~1
This invention relates to a syringe, and to a
needleless injector for use with the syringe.
The present inventor has been involved in the field
of needleless injectors for many years, his name appearing in
many patents, including Canadian Patents Nos. 1,178,503,
issued on iVovember 27, 1984; 1,256,343, issued June 27, 1989
and 1,258,019, issued August 1, 1989, and U.S. Patents Nos.
4,342,310, issued August 3, 1982 and 4,518,385, issued May 21,
1985.
In general, needleless injectors of the type
described in the above patents, and the vials or syringes used
in the injectors must be carefully manufactured to close
tolerances. Moreover, the injectors usually are produced from
stainless steel, which prevents the expansion of the plastic
syringes containing the medicine. Consequently, the cost of
material and production is substantial, and a need exists for
a less expensive alternative.
An object of the present invention is to meet the
above defined need by providing a relatively simple syringe,
which can be produced form plastic, and which need not be as
accurately dimensioned as existing devices of the same type.
Another object of the invention is to provide a
needleless injector, which can be produced mainly of plastic
for use with the syringe of the present invention.
Accordingly, the present invention relates to a
syringe for a needleless injector comprising tubular body
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means defining a medicine chamber, said body means having one
closed end and an open end; orifice means in said closed end
for discharging medicine from said chamber; plug means
slidable in said chamber between said open and closed ends for
pushing medicine through said orifice means; prong means
extending inwardly from said plug means into said medicine
chamber; 0-ring means on said prong means for creating a
fluid-tight seal between said plug means and said body means;
and sealing ring means on said prong means for preventing
ZO entry of said 0-ring means between said plug means and said
body means during movement of said plug means towards said
orifice means.
The invention will be described in greater detail
with reference to the accompanying drawings, which illustrate
preferred embodiments of a syringe and needleless injector in
accordance with the present invention, and wherein:
Figure 1 is a side elevational view of a disposable
syringe in accordance with the present invention;
Figure 2 is a longitudinal sectional view of the
syringe of Fig. 1.
Figure 3 is a longitudinal sectional view of the
righthand end of the syringe of Figs. 1 and 2 on a larger
scale;
Figure 4 is an end elevational view of a split ring
or washer used in the syringe of Figs. 1 to 3 as seen from the
left of Fig. 3;
2
Figure 5 is a partly sectioned side elevational view
of the washer of Fig. 4;
Figure 6 is a longitudinal sectional view similar to
Fig. 3, of an alternative embodiment of a split ring or washer
for use in the syringe of Figs. 1 and 2;
Figure 7 is a side elevational view of a second
embodiment of syringe in accordance with the present
invention;
Figure 8 is a longitudinal sectional view of the
syringe of Fig. 7;
Figure 9 is a side elevational view of an needleless
injector utilizing the syringe of Figs. 1 and 2;
Figure 10 is a longitudinal sectional view of the
syringe of Fig. 9; and
Figure 11 is a long itudinal sectional view of a gun-
type needleless injector utilizing the syringe of Figs. 7 and
8.
Referring to Figs. 1 to 3, a disposable syringe 1
in accordance with the present invention includes an
elongated, tubular cylindrical body or body 2 with a tapering
open end 3 and a closed domed end defining a nozzle 4. The
nozzle ~ includes a convex outer end 5 containing a central
stainless steel insert defining an injection orifice 6 through
which medicine can be discharged from a chamber 7 in the body
2. The cylindrical nozzle 4 is threaded for receiving a
cylindrical cap or cover 9. The cover 9 includes a concavo-
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It
convex transversely extending partition 10, which closes the
orifice 6 when the cover is screwed tightly onto the nozzle 4.
An annular flange 12 extends outwardly from the body 2
rearwardly of the nozzle ~ for limiting movement of the
syringe 1 into an ne2dleless injector, as described
hereinafter in greater detail. Radially extending sawtooth
projections 13 are provided on the surface of the flange I2
opposite the nozzle 4 for preventing rotation of the body 2 in
a needleless injector.
As mentioned above, the body 2 defines a medicine
chamber 7. The chamber 7 is closed by a plug 15 which
includes a cylindrical body 16 and a prong 17 extending into
the medicine chamber 7. An 0-ring 19 and an annular seal or
washer 20 are provided on the prong 17. The washer 20, which
is in fact a split ring with a slot 21 (Figs. 4 and 5), is
designed to expand with the body 2 to prevent movement of the
0-ring 19 between the body 16 of the plug 15 and the interior
surface 22 of the body 2 when the plug 15 is pushed towards
the orifice 6 under pressure. The slot 21 is inclined with
respect to the front and rear surfaces of the washer so that
the 0-ring 1.9 cannot be squeezed into the slot. As the plug
15 moves towards the orifice 6, the prong 17 enters a reduced
diameter portion 23 of the chamber 7 ensuring that virtually
all of the medicine is expelled from the body 2. The orifice
or front surface of the washer 20 is inclined inwardly, so
that the pressure of the medicine in the syringe presses the
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0-ring 19 against the washer 20 to force the latter outwardly
against the interior surface 22 of the body 2. Alternatively,
as best shown in Fig. 6, both surfaces 24 of the washer 20 can
be bevelled inwardly, so that forces acting on either side
force the washer outwardly against the interior 22 of the body
2.
With reference to Figs. 7 and 8, a second embodiment
of the syringe 25 of the present invention includes an
elongated tubular body or body 26 with an open end 27 and a
closed end 28. A nozzle 29 with an injection orifice 30
therein extends outwardly from the closed end 28 of the body
26. The orifice 30 is normally closed by a valve generally
indicated at 31. The valve 31 is defined by a short tube 33
extending inwardly away from the nozzle 29. Longitudinally
extending slots 34 are provided in the top and bottom of the
tube 33. A resilient rubber plug 36 extends into the tube 33.
The plug 36 includes a tubular body 37 and an annular, domed
head 38 extending around the open inner end of the tube 33.
When liquid in the medicine chamber 39 is subjected to
pressure by virtue of movement of a plug or plunger 40 towards
the orifice 30, the medicine passes through the slots 34
pressing against the tubular body 37 of the valve 36 to open
the valve permitting discharge of medicine through the orifice
30.
The plunger 40 is slidably mounted in the body 26.
A central passage 42 is provided in the plunger 40 for
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admitting medicine into the medicine chamber 39. As in the
case of the first embodiment of the invention, a prong 43 is
provided on the inner end of the plug or plunger 40. An 0-ring
45 and an annular split ring or washer 46 are mounted on the
prong 43. The O-ring 45 and the seal 46 perform the same
function as the 0-ring 19 and the washer 20, respectively of
the first embodiment of the invention. The front or inner end
of the passage 42 is closed by a second valve generally
indicated at 48. The valve 48 includes a cylindrical cover 49
mounted on the prong 43. The cover 49 is retained on the
prong 43 by generally L-shaped fingers 51 extending through
openings 52 in the inner end of the cover 49. When the
plunger 40 is withdrawn from the orifice end of the body 26, a
partial vacuum is created in the medicine chamber 39, whereby
the cover 49 is caused to slide on the prong 43 to an open
position (not shown) against the outer ends of the fingers 51.
Medicine is drawn through the passage 42 from a bag (not
shown) and is admitted to the chamber 39 via the openings 52
in the cover 49. When the plug 40 moves towards the orifice
30, the cover 49 is pressed against the inner end of the
passage 42 to close the latter.
An annular groove 53 is provided in the end of the
plug 4p extending out of the body 26. The groove 53 is
followed by a ring 54 and a tapering end 55 for connecting the
syringe 25 to a source (not shown) of medicine.
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With reference to Figs. 9 and 10, a needleless
injector 55 for use with the syringe of Figs. 1 and 2 includes
a cylindrical casing 56, one end 57 of which is closed, and
the other end of which is closed by a trigger or actuator
button 58. A sleeve 59 is mounted on the closed end 57 of the
casing 56. The sleeve 59 has an open end 60 and a closed end
62. An externally threaded cylinder or barrel 63 extends
inwardly through the closed end 62 of the sleeve 59. The
barrel 63 extends through a threaded opening 64 in the end 57
of the casing 56. Outward movement of the barrel 63, and
consequently of the sleeve 59 is limited by a split ring 66 on
the inner end of the barrel 63, i.e. the end of the barrel 63
in the casing 56. Rotation of the sleeve 59, and consequently
of the barrel 63 causes movement of the barrel 63 into the
casing 56. A window 68 is provided in the side of the sleeve
59 for observing indicia (not shown) on the casing 56
indicative of the dosage being administered using the
injector.
A threaded neck 69, defining the front or outer end
of the barrel 63, extends outwardly from the front end 62 of
the sleeve 59 for receiving an internally threaded syringe
cover 70. A prefilled syringe 1 is inserted into the neck 69,
the front end 72 of which has raised extending sawtooth
projections for mating with the projections 13 on the syringe.
The cover 70 is placed on the neck 69, so that radially,
inwardly extending flange 73 on the front end thereof bears
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against the flange 12 of the syringe 1 to retain the latter in
the barrel 63. The opening 74 in the outer end of the cover
70 is sufficiently large to permit removal and replacement of
the cover 9 from the nozzle 4 of the syringe 1. Movement of
the plug 15 in the body 2 of the syringe 1 is effected by a
plunger 76, which is slidably mounted in the casing 56. The
plunger 76 includes an elongated rod 77 for insertion into the
open trailing end 3 of the syringe body 2, and a cup-shaped
bushing 79 integral with the rod 77 for sliding in the casing
56. The bushing 79 is maintained in a loaded position (Fig.
10) by a latch, which includes a ball 80 in an opening 81 in
the side of the bushing 79. The ball 80 rests in a groove 83
in the interior of the casing 56. A cup-shaped collar 84 in
the open rear end of the bushing 79 retains the ball in the
groove 83. The collar 84 is biased to the loaded or latched
position by a small helical spring 86. The collar 84 is
retained in the bushing 79 by a ring 87,
An elongated plunger 89 is used to move the collar
84 into the bushing 79 so that the ball 80 can enter an
annular recess 90 in the collar 84 permitting sliding of the
bushing 79 in the casing 56. The plunger 89 includes a
reduced diameter trailing end 92 and a shoulder 93. The
plunger 89 is biased towards the button 58 by a small helical
spring 94 bearing against a guide ring 96, which is retained
in position by a split ring 97. The plunger 76 is moved
towards the orifice end of the sleeve 59 by a helical spring
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99. When the button 58 is pressed, the plunger 89 moves
forwardly to move the collar 84 to the ball release position.
When the ball 80 enters the annular groove 90, the bushing 79
is free to move forwardly, so that the rod 77 moves rapidly
forwardly against the plug 15. With the cover 9 removed,
sufficient pressure is generated that the drop of medicine
discharged through the orifice 6 breaks the skin, so that the
medicine can be injected. For such purpose, there is a gap
between the trailing end of the plug 15 in the syringe 1 and
the leading or front end of the plunger 76. Forward movement
of the plunger 76 ceases when the bushing 79 hits the inner
end of the barrel 63, at which point the plug 15 has reached
the orifice end of the syringe.
The cover 70 is removed and the disposable syringe 1
is removed from the barrel 63. In order to reload the
injector 55, the barrel 63 is wound into the end 57 of the
casing 56 to push the bushing 79 rearwardly against the bias
of the spring 99 until the ball 80 drops into the groove 83.
The sleeve 59 is then rotated in the opposite direction until
the desired setting is observed through the window 68, at
which time a new disposable, prefilled syringe 1 is inserted
into the barrel 63, and the injector can be again fired. The
setting will determine the gap between the plug 15 and the
plunger 76, and thus the depth of penetratian of the medicine.
The setting may require altering depending upon whether a
human or an animal (e. g, pig, cow or horse) is being injected.
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A pair of wings 100 are provided on the actuator button end of
the casing 56 for facilitating handling of the injector.
Referring to Fig. 11, a pistol-type needleless
injector using the refillable syringe 25 of Figs. 7 and 8
includes an elongated cylindrical casing 102, with a hollow
handle 103 perpendicular thereto. An externally threaded neck
105 extends forwardly from th a front end of the casing 102 for
receiving a tubular syringe 25 holder 106. For such purpose,
one end 107 of the syringe holder 106 is internally threaded
for engaging the neck 105. The other closed end 108 of the
holder 106 engages the closed end 28 of the syringe body 26
for retaining the syringe in the holder 106. The nozzle 29 of
the syringe 25 extends outwardly through an opening 110 in the
otherwise closed end 111 of the holder 106. The inner,
tapered end 55 of the syringe plug 40 is connected to a supply
of medicine such as a plastic bag (not shown) by a tube 113,
which extends through a slot 114 in the bottom center of the
casing 102. The tube 113 extends through the slot 114, an
opening 115 in the front of the handle 103 above a trigger
117 and downwardly through the handle to the bag of medicine.
When the plug 40 is withdrawn from the casing 26 (moved to the
right in Fig. 11) a partial vacuum is created in the chamber
39, whereby the valve 48 (Fig. 8) opens and medicine is drawn
through the tube 113 and the passage 42 into the chamber 39 of
the syringe 25. When the trigger 117 is depressed to close a
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switch 118, hydraulic fluid is introduced into the injector as
described hereinafter in greater detail.
The plug 25 is caused to move by a plunger 120
slidably mounted in the casing 102. The plunger 120 includes
a semi-cylindrical body 121 with the groove in the front end
122 thereof for insertion into the groove 53 in the plunger
40, whereby the plunger 40 can be pulled out of the syringe
body 26 or pushed towards the orifice end thereof. The inner
or trailing end of the plunger 120 is defined by a cup-shaped
piston 124 sealed in the casing 102 by an O-ring 125. A rod
127 extends rearwardly from the piston 124 into a spring
chamber 128, which includes a sleeve 129 surrounding the rod
127. The sleeve 129 includes an annular flange 130 for
bearing against a shoulder 131 in the casing 102. The sleeve
129 is retained in position by the externally threaded end 133
of a cylindrical rear end cap 134 of the casing 102. The area
between the piston 124 and the sleeve 129 defines a pressure
chamber 135, which receives fluid under pressure through an
inlet line 137 extending through the handle 103 when (as
mentioned above) the trigger 117 is depressed. The fluid
comes from a pressure accumulator (not shown) or other source
of fluid under pressure.. The rod 127, and consequently the
piston 124 are biased towards the outer end of the cap 134 by
a helical spring 138 sandwiched between the closed inner end
139 of the sleeve 129 and an annular flange 141 on the spring
chamber end of the rod 127.
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In operation, with the gun in the fired position
shown in Fig. 11, the spring 138 moves the rod 139 and the
piston 124 away from the orifice end of the injector. Such
movement draws the plunger 40 out of the syringe body 26
creating a partial vacuum in front of the second valve 48
(Fig. 8), The vacuum draws medicine into the chamber 39 to
fill the chamber. When the trigger 117 is pressed, fluid
under pressure is introduced into the pressure chamber 135 via
the line 137 to move the plunger 40 rapidly towards the
orifice end of the gun. Such movement closes the valve 48 and
opens the valve 31. The width of the groove 53 in the plunger
40 is such that there is a gap between the end 122 of the
plunger 120 and the orifice end of the groove 53. Thus, as
the plunger 120 moves rapidly forwardly it strikes the front
end of the groove 53 to discharge a skin piercing drop of
medicine throw-gh the orifice 30. Thereafter, the plunger 120
pushes the plug 40 forwardly until the medicine has been
discharged through the orifice 30. Upon completion of an
injection, the chamber 135 is vented, and the spring 138 moves
the plunger 120 rearwardly to repeat the syringe filling or
loading operation. When the bag carrying the medicine has
been emptied, the holder 106 is removed from the neck 105, the
syringe 25, the tubing 113 and the bag are discarded. A tube
113 attached to a fresh bag of medicine is inserted through
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the handle 103 and the slots 114 and 115 into the casing 102,
and attached to the tapered end 55 of the plunger 40 of a
fresh syringe 25.
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