Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a needleless injection
apparatus, and in particular to a portable, needleless multi-
dose injection apparatus.
The injection of drugs or other injectable fluids
into large animals such as horses and cattle is usually
performed with disposable needles.
~ he injection of drugs and other chemicals into farm
animals is a common occurrence. Not only must the animals be
treated for disease prevention and curing, but hormones are
commonly used to increase meat and milk production.
Traditionally, injections are performed using the conventional
needle and syringe. Quite often, a so-called disposable
needle and syringe is used and re-used until the needle
becomes too dull to penetrate the hide of an animal. Not only
is there a certain amount of pain and trauma to the animal,
but there is a danger of injection with a contaminated needle.
Moreover, the accumulation of used needles and syringes
represent a serious environmental problem.
It is well established that needleless injectors
represent a solution to the pain and trauma problems. A
needleless injector of the type described in applicant's
Canadian Patent No. 1,178,503, issued November 27, 1984 makes
a substantially smaller hole and inflicts much less pain than
even the smallest needle. However, needleless injectors are
high pressure devices, requiring systems for generating
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pressures sufficiently high to propel a drug through a small
injection orifice at a high velocity.
Known multiple injection devices tend to be somewhat
complicated or ill-suited for use in the field, e.g. by
veterinarians wishing to inject drugs into a large herd of
cattle, horses, sheep or goats. Multiple injection units are - ~
disclosed, for example by United States Patents Nos.
2,928,390, which issued to A. Venditty et al on March 15, 1960
and 3,515,130, which issued to J. Tsujino on June 2, 1970.
While the Tsujino device is much simpler and presumably
lighter than the Venditty et al device, Tsujino is concerned
solely with reducing the weight of the hand held injector,
i.e. the Tsujino device is not actually portable, it is only
the injector itself which is portable. The hydraulic system
used with the Tsujino device would be stationary or carried by
a large vehicle.
It is readily apparent that a need still exists for
a truly portable injection apparatus for making multiple
injections.
The object of the present invention is to meet the
above defined need by providing a relatively simple,
inexpensive, lightweight portable, needleless injector, which
can be used to make many quick injections.
Accordingly, the present invention relates to a
portable, needleless injection apparatus comprising fluid
actuated, needleless injector means for discharging a drug
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under pressure; portable generator means for supplying fluid
under pressure to said injector means, said generator means
including casing means; reservoir means in said casing means
for storing fluid; pressure accumulator means in said casing
means; first valve means in said casing means for controlling
the flow of fluid between said accumulator means and said
injector means, and from said injector means to said reservoir
means; and pump means in said casing means for pumping fluid
from said reservoir means to said accumulator means when the
pressure in said accumulator means drops below a predetermined
level.
The use of a needleless injector with a truly
portable, preferably battery operated, power source makes it
possible to perform as many as one thousand subcutaneous
injections per hour. With the apparatus of the present
invention, the user can walk to each animal, carrying the
power generator, rather than being tethered to a stationary
bulky source of power. While the apparatus is primarily
intended for veterinarians, it will be appreciated that farms
with large herds of animals would benefit by owning such an
apparatus.
The invention will be described in greater detail
with reference to the accompanying drawings, which illustrate
a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, perspective view of an
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apparatus in accordance with the invention in the use
position;
Figure 2 is a mainly sectioned, side view of an -
injector for use with the apparatus of Fig. l;
Figure 3 is a mainly, sectional view of a
disposable syringe used in the injector of Fig. 2;
Figure 4 is a mainly sectioned side view of a power
generator used in the apparatus of Fig. l;
Figure 5 is a partly sectioned side view of a pump
used in the power generator of Fig. 4;
Figure 6 is a front view of a wobble plate used in
the pump of Fig. 5; and
Figure 7 is a partly sectioned side view of a
plunger and valve plate used in the pump of Fig. 5.
With reference to Fig. 1, the apparatus of the
present invention which is generally indicated at 1 is
designed to be portable. For such purpose the apparatus 1 is
mounted in a backpack 2 with lugs 3 extending outwardly from
the corners thereof for receiving straps 4. The straps 4
extend around a user's shoulders 5 and chest. The apparatus 1
is designed to inject a drug from a container 6 on the side of
the backpack 2. The drug and hydraulic fluid are fed from the
backpack 2 via lines 8 and 9 to a hand held pistol-style
injector generally indicated at 10.
The injector 10 includes an elongated body 12 with a
barrel 13 connected to one end thereof and a handle 14
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extending downwardly from the other end thereof. The metal
barrel 13 is releasably connected to the body 12 by a stepped,
tubular coupler 15, with an annular shoulder 17 at one end for
engaging an inwardly extending, annular flange 18 on one end
of the body 12. The inner end 20 of the barrel 13 has
interior threads for removably mounting the barrel on the
coupler 15, and the outer end has an annular, inwardly
extending flange 21 for engaging the stepped outer end 22 of a
disposable syringe 24. The outer end of the barrel includes
an annular row of teeth 25 to facilitate locating of the
injector 10 on the skin.
As best shown in Fig. 3, the disposable syringe 24
includes a tubular barrel 26 with a thin skirt 27 defining one
end thereof. The beaded free~end 28 of the skirt mates with an
annular groove 30 in the coupler 15 to connect the syringe
barrel 26 to the coupler when the barrel 13 is screwed onto
the coupler. The other, discharge end 32 of the barrel 26
includes a shoulder 33, which acts as a stop for a separate
cover 34. The end 32 is generally conical with three
longitudinally extending passages 36 spaced equidistant apart
through which liquid can be discharged. The passages 36 are
normally closed by a one-way valve in the form of a tapering
flexible rubber skirt 37, the beaded inner end 38 of which
forms a seal between the barrel 26 and the cover 34. Liquid
passing through the passages 36 is discharged from the syringe
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through a central orifice 39 in the conical end 22 of the
cover 34.
An elongated tubular plunger 40 is slidably mounted
in the barrel 26. An O-ring 42 forms a seal between the
barrel 26 and the plunger 40. The hollow front end of the
plunger 40 receives a cylindrical insert 43 with a plurality
of small longitudinally extending passages 44 therein. The
front or outer ends of the passages 44 are normally closed by
a rubber disc 46. The disc 46 is held on the insert by three
small lugs 47 extending rearwardly from a generally conical,
tubular head 49. Thus, liquid travelling through the plunger
26 enters a small chamber 50 behind the insert 43 and is
discharged through the passages 44 and the head 49 into a
chamber 52 formed between the plunger 40 and the barrel 26
during rearward movement of the plunger 40. The use of many
small holes or passages 44 in the insert 43 prevents
puncturing of the one-way valve disc 46 by liquid under high
pressure. A tubular coupler 53 is provided at the inner end
of the plunger. The coupler 53 includes a rearwardly
extending bifurcated arm 55 with an enlarged frusto-conical
head 56 for connecting the plunger to the small tubular end 57
of a piston 58 (Fig. 2). A tubular arm 59 perpendicular to
the arm 55 includes a series of annular ridges for connecting
the drug carrying line 8 to the interior of plunger 40. A
longitudinally extending slot 60 (Fig. 2) is provided in the
coupler 15 so that the coupler 53 can pass therethrough when
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the syringe 24 and the barrel 13 are being connected to the
body 12 of the injector.
Referring again to Fig. 2, the piston 58 is
generally cup-shaped with the tubular front end 57 for
connecting the piston to the plunger 40. The piston 58 is
biased rearwardly by three helical springs 61, and is sealed
in the body 12 by an O-ring 62. The stroke of the piston 58
and consequently of the plunger 40 is determined by a tubular
stop 64, which is slidably mounted in an extension 65 on the
rear end of the body 12. The extension 65 is sealed in the
body 12 by an O-ring 66, and the stop 64 is sealed in the
extension 65 by an O-ring 67. Longitudinal movement of the
stop 64 is effected by rotation of a screw 69 in the threaded
interior of the stop. The screw 69 extends outwardly through
the closed outer end 70 of the extension 65 to a short
cylindrical handle 72 for manual rotation of the screw.
Rotation of the stop 64 is prevented by a pin 73 extending
outwardly from the stop through a longitudinally extending
slot 74 in the extension 65. A series of dosage lines (not
shown) is provided on the extension 65 beside the slot 74 for
indicating the stroke of the piston 58 and plunger 40, and
consequently the dosage of the drug. An oil duct 76 extends
from the body 12 through the handle 14 and is connected to the
line 9 by a coupler 77. Operation of the injector 10 is
controlled by a trigger defined by a pushbutton 78 in the
handle 14. The button 78 is connected to the solenoid valve
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79 of a portable power generator (Fig. 4) by a wire 80 (Figs.
1 and 3) .
With reference to Fig. 4, the power generator is
defined by a casing containing a hydraulic fluid reservoir
generally indicated at 81 and a pressure accumulator
generally indicated at 82.
The reservoir 81 is defined by a pair of tubular,
coaxial casings 84 and 85, with a tubular diaphragm 86
sandwiched therebetween. An opening 88 in the outer casing 84
permits air to enter and exit the outer casing 84 for
balancing pressure on the diaphragm 86. The hydraulic fluid
is housed in the chamber defined by the inner casing 85, the
diaphragm 86 and one side of the pressure accumulator casing
89. A DC motor 90 is mounted on a flange 92 on one end of a
sleeve 93 using bolts 95 and nuts 96 (one shown). The sleeve
93 is connected to the casings 84 and 85, and to the
accumulator casing 89 by bolts 97 (one shown), so that the
various casings form one large housing or casing for mounting
in a backpack 2. The motor shaft 99 is connected to a wobble
plate pump shaft 100 by a coupler 101. The shaft 100 is
rotatably mounted in bearings 103 in the casing 85, and a
fluid seal 104 is provided at the motor end of the shaft. The
shaft 100 carries an inclined wobble plate 105, i.e. a plate
105 with an inclined face 106 (Figs. 5 and 6), which
reciprocates three plungers 107 (one shown) in a valve body
108 which closes the accumulator end of the casing 85.
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As best shown in Figs. 5 to 7, the inclined face 106
of the plate 105 includes a shallow arcuate recess 109 for
receiving hydraulic fluid entering the pump casing 85 through
an opening 110 (Fig. 4). During rotation, the face 106 of the
plate 105 slides relative to three similar circular plates
112. Each plate 112 is maintained in position against the
plate 105 by the hemispherical head 113 of the plunger 107 and
a helical compression spring 114. The head 113 bears against
the sides of a generally conical recess 115 (Fig. 7) in the
outer end of the plate 112. Each of the plates 112 contains a
central opening 116 permitting the passage of hydraulic fluid
from the recess 109 into the plungers 107. A second passage
117 equalizes fluid pressure on each side of the plunger head
113. Each plunger 107 contains a longitudinally extending
passage for feeding fluid through passages (one shown) 118 in
the valve body 108.
The two-part valve body 108 is sealed in the
casing 85 by an annular gasket 119 and in the accumulator
casing 8g by an O-ring 120. During rotation of the plate
105, the plungers 107 reciprocate between open and closed
positions of valves 121 ~one shown) normally closing the
passages 118 containing the plungers 107 from a passage 123
through the valve body 108. ~he valves 121 are biased to the
closed position by helical springs 124. The passage 123 is in
fluid communication with a passage 125 in the pressure
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accumulator casing 89. A pressure sensor 126 is mounted in a
passage 127 perpendicular to the passage 125.
The pressure accumulator includes a semispherical
recess 128 with an internally threaded top end 129 for
receiving an externally threaded, domed cover 130. A
diaphragm 131 divides the interior of the pressure accumulator
into an upper gas chamber 132 and a lower oil chamber 133.
Compressed nitrogen is introduced into the chamber 132
through an opening 134 and a one way valve 135.
A metal insert 136 is provided in the diaphragm 131
for preventing damage to the diaphragm as it presses against
one end of a passage 137 perpendicular to the passage 125.
The passage 137 contains a sleeve 138 carrying the plunger 139
of the solenoid valve 79. The valve is biased to the closed
position by a helical spring 140 between the closed inner end
142 of the sleeve 138 and the inner end of the plunger 139.
The plunger 139 includes two shoulders 143 and 144 for closing
openings 146 and 147, respectively in the sleeve 138. The
opening 146 permits the flow of hydraulic fluid from the
chamber 133 through the passage 137, the sleeve 138 and an
opening 149 to the line 9. The opening 147 permits the return
of hydraulic fluid from the line 9 through the opening 149,
sleeve 138 a passage 150 in the casing 89, and around the
pressure sensor 126 to a passage lSl and the reservoir 81.
The motor 90 is operated by portable, rechargeable
batteries (not shown) mounted in the backpack 2. By turning
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the sleeve 72, the length of the piston stroke and
consequently the dosage to be administered can be adjusted.
With the chamber 52 full of medicine, the trigger (button) 78
is depressed to actuate the solenoid valve 79. Thus, the
plunger 139 is moved upwardly (Fig. 4) to open the flow path
from the accumulator oil chamber 133 to the line 9. Oil flows
into the body 12 of the injector forcing the piston 58
forwardly. Such forward piston movement pushes the plunger 40
forwardly to open the one-way valve (skirt) 37 and forces the
drug from the chamber 52 through the orifice 39 under high
pressure.
Once the drug has been discharged, the spring 140
returns the plunger 139 to the closed position (Fig. 4), and
the springs 61 move the piston 58 to the rest position
against the sleeve 64. Thus, the hydraulic oil returns
through line 9, the sleeve 138, and passages 150 and 151 to
the reservoir 81. At the same time, rearward movement of the
plunger 40 creates a partial vacuum in the chamber 52. Drug
is drawn through the line 8 and the insert 44 into the chamber
52. The injector is now ready for another injection.
When pressure in the accumulator 82 drops below a
predetermined level as detected by the sensor 126, the motor
90 is started to operate the pump forcing hydraulic oil into
the chamber 133 of the accumulator. Such pressurizing of the
system can occur while the operator is walking from one animal
to the next animal. By using the pressure accumulator 82, a
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relatively small, battery operated DC motor can be used to
power the pump.
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