Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a needleless injector, and
in particular to a multi-dose needleless injector.
The conventional treatment of diabetes includes a
plurality of daily injections of insulin rather than a single
large dose each day. The usual disposable syringe and needle
method of injecting insulin is not particularly satisfactory.
Besides making a somewhat large hole in the skin, needles
create scar tissue making subsequent injections increasingly
more difficult,
The inventor named herein and others have proposed
the use of needleless injectors. Examples of such needleless
injectors are described in Canadian Patents Nos. 1,178,503,
issued to 2. Lindmayer et al on November 27, 1984 and
1,258,019, issued to I. Lindmayer on August 1, 1989, and in
U.S. Patents Nos. 4,722,728, issued to A.J. Dickson on
February 2, 1988 and 4,874,367, issued to B. Edwards on
October 17, 1989.
In general, existing needleless injectors are either
somewhat complicated or are intended for single injections
only, i.e. require a fresh syringe for each injection. Thus,
a need exists for a device which can be used for multi
injections.
The object of the present invention is to meet the
above defined need by providing a relatively simple needleless
injector, which can be used with a disposable syringe for
1
02/19/01 18:30 FAg 232 5831 SEABY-AS50CIATES ~ 003/005
administering multiple injections of a drug without replacing
the syringe.
Accordingly, the present invention relates to a
multi-dose injector for use with a axringe of the type
~.z~cluding a tubular body with an open end, a closed end
contaix~ing an injection orifice and a plug sJ.idable in the
body for movement tot~ards the closed end to force medicine
through the injection orifice, said injector comprising
cyliridrical casing means having a closed front end and an
open rear end; sleeve means slidably mounted on the closed
front end of said casing means; barrel means extending through
the outer free end of said sleeve means into Said front end of
said casing means for receiving a syringe body; Cap means for
releasably retaining the syringe in said barrel means] tubular
bushing means slidab~,G in said paging means for move~nt
between a cocked and a discharge ppsition; latch means for
releasably retaining said bushing means in tha cocked
position; plunger means Q~stending,through said bushing means
for project~~ng into the syringe body to beax against the plugs
2o first spring me$ns for driving said bushing means and said
plunger matins from a cocked position to a di3oharge position;
trigger means for actuating said latch means to release the
bushing means whereby ,said first spring mx~ans drives the
bushing xneaas and plunger means fQx~yaardly to move the plug in
the syringe body towards the discharge orifice; and clutch
means in said bushing meax7,B for releasably connecting said
a
CA 02021566 2001-02-19
plunger means to said bushing means, whereby said plunger
means moves with said bushing means during medicine discharge,
and said plunger means can be released from said bushing means
for rearward movement when cocking the injector or inserting a
fresh syringe.
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 side elevational view of a needleless
injector in accordance with the present invention;
Figure 2 is a longitudinal sectional view of the
needleless injector of Fig. 1; and
Figure 3 is a longitudinal sectional view of the
portion of the needleless injector between the lines A-A and
B-B of Fig. 2 on a larger scale.
With reference to the drawings, the needleless
injector of the present invention includes an elongated,
tubular casing generally indicated at 1 with a sleeve 2
slidably mounted on one closed end 4 thereof. An externally
threaded barrel 5 extends rearwardly from the front end 6 of
the sleeve 2 through a threaded opening 8 in the closed and 4
of the casing 1. Movement of the barrel 5 out of the casing 1
is limited by a split ring 9 on the inner end 10 of the barrel
5. A tubular, externally threaded neck 12 extends outwardly
from the end 6 of the sleeve 2 for receiving a disposable
syringe 13 of the type described in applicant's copending
3
Canadian patent application filed on the same day as this
application.
The syringe 13 includes a tubular body 14 with a
closed outer end 16 and an open inner end 17. An annular
flange 18 is provided on the body 14 near the outer end 16 for
limiting movement of the body 14 into the barrel 5. Opposed
radially extending, alternating ridges and grooves or
serrations 20 are provided on the inner side of the flange 18
and on the outer end of the neck 12 for preventing rotation
of the syringe 13 relative to the barrel 5 once fully inserted
therein. An internally threaded cap 21 is mounted on the
neck 12 to retain the syringe 13 in the barrel 5. The outer,
domed end 16 of the syringe 13 is threaded for receiving a
tubular, cylindrical cover 23. A concavo-convex, partition 24
in the cover 23 closes a stainless steel discharge orifice 25
in the end 16 of the syringe 13. An plug 27 is slidably
mounted in the body 14 for pushing medicine from the chamber
28 defined by the body 14. The plug 27 is cylindrical with a
smaller diameter prong 29 on one end thereof extending towards
the orifice end of the body 14. The prong 29 carries an 0-
ring 31 and a split ring or washer 32. The washer 32 prevents
movement of then 0-ring between the plug 27 and the body 14
under injection pressure.
The plug 27 is caused to move in the body 14 by a
plunger 34 with an enlarged head 35 slidable in the open end
17 of the body 14. The plunger 34 in turn is moved from the
4
cocked position shown in Figs. 2 and 3 to a discharge position
by a bushing 36 and a large helical drive spring 38. The
bushing 36 includes a tubular body 39 with a narrow diameter
forward end or neck 40 and an open rear end 41. The bushing
36 contains a cup-shaped collar 43, which forms part of a
latch for releasably retaining the bushing in the cocked
position. As best shown in Fig. 3, the collar 43 includes an
open inner end 44 for receiving a helical spring 45, which
biases the collar 43 rearwardly. The spring 45 extends from
ZO the closed end 46 of the collar 43 to a shoulder 47 at the
neck end of the bushing 36. An annular recess 49 in the
collar 43 receives three balls 50 (one shown) which extend
through holes 52 (one shown) spaced equidistant apart in the
bushing 36 into a longitudinally extending, annular groove 53
in the interior of the casing body 55. When the collar 43
moves forwardly, the balls 50 enter the groove 49, whereby the
bushing 36 is released for sliding movement in the casing 1.
When the bushing 36 and the collar 43 are moved toward the
cocked position, the balls 50 are forced outwardly through the
opening 52 into the groove 53 to latch the bushing 36 in the
cocked position.
The collar 43 is pushed into the bushing 36 by
movement of a hollow shaft 57, which is coaxial with the
plunger 34. When the shaft 57 moves forwardly, a shoulder 58
(Fig. 3) thereon bears against the closed end 46 of the collar
43 to press the latter into the bushing 36 again st the bias of
5
~02~~~i
the spring 45. The shaft 57 contains a longitudinally
extending slot 60 (Fig. 2) for receiving a pin 61 extending
outwardly from the rear end 63 of the plunger 34, so that the
plunger 34 can move longitudinally, but not rotate in the
shaft 57. The shaft 57 is moved forwardly by a trigger
defined by a push button 64 mounted on the outer or rear end
of the shaft 57 in the open end 66 of the casing body 55. The
shaft 57 and the button 64 are biased rearwardly by a helical
spring 67 extending into the hollow rear end 63 of the plunger
34 and through the shaft 57 to the closed rear end thereof.
Thus, when the button 64 is pressed, the shaft 57
moves forwardly, so that the shoulder 58 pushes the collar 43
into the bushing 36 to release the balls 50. The balls 50
move into the groove 49, and the bushing 36 and plunger 34 are
moved forwardly by the spring 38 to expel medicine from the
syringe chamber 28. The dosage is determined by the spacing
between the closed front end 40 of the bushing 36 and the rear
or inner end _1.0 of the barrel 5.
In order to re-cock the injector, the sleeve 2 is
rotated so that the barrel 5 moves into the closed end 4 of
the casing 1. The barrel 5 pushes the bushing 36 rearwardly
against the bias of the spring 38 until the balls 50 reach the
groove 53. The balls 50 are forced into the groove 53 to
latch the bushing 36 in the cocked position. When the balls
50 enter the groove 53, a zero (~0) is visible on the casing
body 55 through a window 69 in the sleeve 2. As the sleeve 2
s
~~~~e~~~
is wound out away from the casing 1, numbers (not shown) in
ascending order appear through the window 69. The gap between
the rear end 10 of the barrel 5 and the front end 40 of the
bushing 36 also increases.
During movement of the bushing 36 to the cocked
position, the spring 67 causes the plunger 34 to remain in
contact with the plug 27 in the syringe 13. In order to
enable the plunger 34 to follow the plug 27, i.e. to remain in
contact therewith, a clutch mechanism is provided in the front
LO end 40 of the bushing 36. The clutch mechanism (Fig. 3)
includes a plurality of small balls 70, which are biased
against a frusto-conical, rearwardly and inwardly inclined
interior surface 72 of the front end 40 of the bushing 36 by a
helical spring 73 and a washer 74. When the plunger 34 and
the shaft 57 move rearwardly during cocking of the injector,
the balls 70 are pressed against the inclined surface 72, so
that the plunger 34, the bushing 36 and the shaft 57 move
rearwardly together. When the sleeve 2 is wound outwardly or
forwardly to determine the dosage of medicine to be injected,
the spring 67 causes the plunger 34 to move forwardly
releasing the clutch, i.e. moving the balls 70 away from the
inclined surface to permit the plunger to follow the syringe
plug 27.
In order to load a fresh syringe 13 into the barrel
5, the button 64 is rotated, so that an ~-shaped lug 76
thereon is aligned with a longitudinally extending notch 77 in
7
the rear end 64 of the casing body 55. For such purpose and
for other manual manipulation of the injector, longitudinally
extending, rectangular vanes or handles 79 are provided on the
casing body 55 near such rear end 66. The button 64 is
pressed so that the lug 76 enters the notch 77. Thus, the
narrow diameter front end 80 of the shaft 57 is pressed
against the balls 70 to release the clutch, so that the
plunger 34 can move rearwardly as a fresh syringe 13 is
inserted into the barrel 5. when released, the button 64 is
returned to the outer or rest position by a helical spring 82
coaxial with the rear end 83 of the shaft 57. The spring 82
is sandwiched between the button 64 and a split ring 84 in the
casing body 55. A washer 86 on the front side of the ring 84
supports the rear end of 'the drive spring 38.
During operation, with the injector in the cocked
position shown in Fig. 2 and the cover 23 removed from the
syringe 13, the button 64 is pressed to release the latch,
i.e. to move the shaft 57 forwardly so that the shoulder 58
presses the collar 43 into the bushing 36. The balls 50 enter
the groove 49 in the bushing 36, and the spring 38 moves the
bushing 36, and the plunger 34 rapidly forwardly to expel
medicine from the medicine chamber 28 through the orifice 25.
Once the dosage, dictated by the spacing between the rear end
10 of the barrel 5 and the front end 40 of the bushing 36, has
been discharged, the injector can be recocked by winding the
sleeve 2 toward the rear end 66 of the casing body 55 so that
8
the rear end 10 of the barrel 5 pushes the bushing 36
rearwardly until the balls 50 re-enter the grooves 53. The
sleeve 2 is then wound forwardly, i.e. away .from the rear end
66 of the casing body 55 to set the dosage. As the sleeve 2
is moved away from the rear end 66 of the casing body 1, the
spring 67 releases the clutch, i.e. biases the plunger 34
forwardly to move the balls 70 away from the surface 72, so
that the plunger 34 follows movement of the plug 27. When the
bushing 36 moves forwardly during injection, the balls 70 are
pressed against the surface 72 to engage the clutch, i.e. to
latch the plunger 34 to the bushing 36.
When the syringe 13 has been emptied, the plunger 34
must move rearwardly; otherwise, it would be impossible to
insert a fresh syringe. Accordingly, during syringe
insertion, the button 63 is aligned with the notch 77.
Depression of the button 63 releases the clutch so that the
fresh syringe 13 can be inserted fully into the barrel 5.
It will be appreciated that the term "forwardly" has
been used to mean towards the discharge end of the injector,
and "rearwardly" has been used with respect to the button or
trigger end of the device.
9
