Note: Descriptions are shown in the official language in which they were submitted.
21'~~il~
TITLE: AUTOMATIC NEEDLE GUARD TIP PROTECTOR
FIELD OF THE INVENTION
This invention relates to the safe disposal of
hypodermic needles by a guard device which protects the
needle tip from exposure after use. More particularly,
it relates to a locking mechanism for a tip protector
which is storable on the needle and which automatically
locks over the end of the needle when slid into position
by the user.
BACKGROUND TO THE INVENTION
The dangers of infection from accidental
contact with the pointed end of used hypodermic needles
have long been recognized and are well documented. In
most procedures, the greatest avoidable risk of
accidental needle puncture, or "needle-stick", occurs
during handling of the used needle, when it is generally
inserted into a protective sheath for disposal. This
action usually requires moving the hand which holds the
sheath towards the pointed tip of the needle, and any
inaccuracy in this operation raises the possibility of a
puncture. The risk of this is greatly increased if the
operator is working under stress, such as time-pressure
21'~~1~.J
2
or fatigue, or is handicapped by marginal eyesight or
unsteady hands.
United States patents Nos. 5,322,517 and
5,328,482 describe needle guards that are essentially
"free floating" in that they are stored at the base of
the needle and lock to the needle when deployed from the
base to the tip of the needle to occupy a covering
protective position.
The protective guard preferably is stored prior
to use at the base of the needle. In this position it
may further be contained within the usual protective
sheath which covers a needle prior to use, and may
thereby be supplied with the needle in its sealed and
sterilized package.
By reason of the fact that the protective guard
may be stored on the needle prior to the normal use of
the needle, and occupies an insignificant, compact space,
its presence produces a minimum interference with the
normal use of the needle. In one application the
protective guard may be stored adjacent to or even within
the enlarged base of a catheter, in an unobtrusive manner
that allows the catheter to be inserted in the normal
manner.
~1'~~~.1J
3
After withdrawal of the needle following use,
the tip of the needle can be immediately covered with the
protective guard by a simple manual action of gripping
the protective guard with the fingers, sliding it out of
its storage position at the base of the needle, and
continuing the sliding motion along the needle shaft
until the guard just over-reaches the end of the needle.
There it automatically locks in position with the tip of
the needle safely covered inside the protective guard.
The protective guard may be slid to the needle
tip by the direct application of fingers to the guard.
Alternately, handle means may be provided either in the
form of an arm, or the like, attached to the guard body;
or by use of a simple draw string that is initially
stored on the protective guard by being wrapped around
its exterior casing.
The protective guard achieves its locking
effect by being provided with an internal energy storage
element, such as a spring, that is capable of initiating
a clamping force through a clamping mechanism. This
clamping force is applied directly to the exterior
surface of the needle shaft. A latching mechanism serves
to suspend initiation of the clamping force prior to
withdrawal of the needle tip within the protective guard.
4
A trigger system releases the latching
mechanism once the needle tip passes within the
protective guard, thereby initiating the clamping force
which is applied to the needle, and thereby locking the
protective guard in place over the needle tip. These
functions occur automatically and enclose the needle tip
with a protecting means which is non-removably engaged
thereto.
The clamping force need only immobilize the
protective guard against axial or longitudinal
displacement on the needle. Further, its locking
resistance need not be symmetrical. It is essential to
have a high locking resistance against further removal of
the guard from the needle. In the other direction
resistance to the reemergence of the needle tip from the
guard can be substituted or supplemented by arranging for
an occluding element to occupy the path of the needle and
serve as a containment means. Once the tip enters the
guard the presence of such a blocking element ensures
that the needle tip cannot re-emerge from the guard even
where the locking resistance against displacement of the
guard towards the needle base is overcome. When such a
blocking element is present, it is sufficient for the
clamping mechanism to provide only a uni-directional or
one-way resistance to further removal of the guard from
the needle.
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The present invention addresses one of the
classes of mechanisms by which a needle guard of such
type may engage with a needle.
The invention in its general form will first be
5 described, and then its implementation in terms of
specific embodiments will be detailed with reference to
the drawings following hereafter. These embodiments are
intended to demonstrate the principle of the invention,
and the manner of its implementation. The invention in
its broadest and more specific forms will then be further
described, and defined, in each of the individual claims
which conclude this Specification.
SUMMARY OF THE INVENTION
This invention is directed to providing an
engagement means for locking the protective guard to a
needle based on introducing a jamming element into an
angular space, such as may be provided by a tapered
cavity or collet. In function it performs similarly to
"chuck" systems. The jamming element is forced into
locking engagement with the needle by forcing the jamming
element between an angled, jamming surface providing a
narrowing or tapered gap between the jamming surface and
the needle shaft.
In one embodiment of the invention, locking
elements or jaws of hardened material may be provided,
6
radially disposed about the needle shaft, and contained
within a gradually tapered or narrowing cavity within the
body of the guard device which provides an angled surface
with respect to the needle and provides a conic chuck
arrangement.
In the unlocked state, these jaws may be
maintained loosely in the bore but, if small, may be held
in a generally uniform distribution about the needle axis
by compliant fingers engaging each jaw. These fingers
may optionally be constituted by axial extensions of a
spring-biased pressure sleeve described further below,
which advances the jaws into the narrowing cavity.
From an initial locked state, the pressure
sleeve may be released by a trigger mechanism and urged
by an energy storage element, such as a compressed
spring, to move axially, forcing the jaws into the conic
chuck means and thereby produce a high radial gripping
force between the jaws and the needle shaft. This force
arises from the gradual narrowing taper of the cavity
walls and the consequent high mechanical force advantage
that this creates.
This arrangement is closely analogous to the
familiar three-jawed drill chuck, where the axial force
required to produce the required clamping force is
usually developed by some form of screw thread. In this
embodiment of the invention, the taper of the containment
21'~8~19
cavity is much more gradual, chosen consistently with the
various parts to produce a self-locking action which
increases as axial force is applied to the needle shaft
in the same direction as the force of the pressure
sleeve. It follows that motion of the needle shaft in
the opposite direction will produce lessening of the grip
of the locking jaws, but this may be resisted by
selecting a spring for the pressure plate that is of
sufficient strength to resist loosening of the clamping
action.
In yet another embodiment of the invention, the
locking jaws as described above may be replaced by
rolling elements in the form of a plurality of
substantially cylindrical rollers of hardened material,
uniformly disposed about the axis of the needle shaft,
with the axis of each roller in a plane perpendicular to
the needle shaft axis, and with each roller making
tangential, or crossed-cylinder contact with the surface
of the needle shaft. The rollers are again contained in
a gradually tapered cavity within the body of the guard
device, each side of this cavity in this case being a
plane surface forming part of a side surface of a conical
polyhedron coaxial with the needle shaft.
In the unlocked state, these rollers are
retained loosely in the bore by a surrounding containment
21'~~~1~
8
cage, optionally constituted by an axial extension of the
pressure sleeve as described above.
From its locked state, the pressure sleeve may
be released to move axially, bringing the rollers into
contact between the walls of the tapered cavity on the
outside and the needle shaft on the inside. Subsequent
axial motion of the needle shaft in this same direction
of motion causes the rollers to roll axially with the
needle towards the smaller end of the tapered cavity,
increasing the force of contact between the tapered
cavity wall and the needle shaft. This results in high
frictional grip between the rollers and their containment
cavity on the outside, and the needle shaft on the
inside, sufficient to block further motion of the needle
in this direction. Once jammed in this locking position
continuing pressure from the pressure sleeve will tend to
keep the protective guard in this locked condition.
In yet another embodiment of the invention, the
rollers described above are replaced by a plurality of
hardened spherical balls, uniformly disposed about the
needle shaft axis, with the centers of the balls in a
common plane perpendicular to the needle shaft axis, and
with each ball making contact with the surface of the
needle shaft. These balls may be contained within a
gradually tapered conical bore or cavity within the body
of the guard device, loosely confined within a containing
2~~~1~~
9
cage which may be an axial extension of the pressure
sleeve as described above.
In a further embodiment of the invention a
sensing ball mechanism is employed in order to effect
engagement of the protective guard to the needle. A
locking assembly of the "chuck" type is provided within
a main body that envelopes the needle by a transverse
passage and is slidable thereon. This body is provided
with a tapered or narrowing interior cavity which lies
adjacent to the needle bore, and substantially may
surround the needle shaft. A locking element
conveniently, for the benefit purposes of symmetry, in
the form of a pair of conically shaped locking jaws
(although a single jaw element could be adopted) is
present within the cavity, these locking jaws being
displaceable between the broader and narrower regions
within the interior cavity. A spring means is provided
within the main body which biases the locking jaws
towards the narrowing regions of the cavity whereby the
locking jaws may be forced into jamming engagement
between the needle bore and cavity wall, locking the
protective guard to the needle.
A latch or latching means releaseably retains
the locking element from advancement into the tapered
cavity. A trigger means, based on a sensing element,
operates to release the latching means when the tip of
2178118
the needle is withdrawn into the protective guard,
allowing the spring means to force the locking jaws into
locking engagement with the needle.
In this embodiment this latching or retention
5 means is of the ball-in-socket type wherein a latching
ball lies partially within a groove or socket generally,
or against a stopping surface, formed within the side of
the locking jaws. This latching ball also partially
rests against a stop surface formed on the interior of
10 the main body of the guard. It is therefore
inter-engaged with both elements. The pair of conical
jaws are loosely inter-fitted with portions of each
overlapping or interleaved with the other. This permits
a single latching ball to be used to retain both of the
jaws in their latched position.
The latching ball is held within the groove in
the jaws by a further ball retention element, which may
be in the form of a cylindrical sleeve or plunger which
is able to slide from a position where it contains the
latching ball within the groove on the jaws, to a
position where it no longer contains the ball whereupon
the ball may withdraw from the groove and release the
locking jaws. This cylindrical sleeve retention element,
therefore, serves as a release means for the jaws, thus
forming part of the latching means.
11
A trigger means serves to hold the ball
retention element in its ball-retaining position while
the needle shaft passes entirely through the needle
guard. Upon activation, this trigger means allows the
retention element to be displaced to a ball-releasing
position, once the needle tip is withdrawn within the
protective guard.
This trigger means is of the sensing ball type
wherein a steel ball serves as the sensing means for
reacting to the presence or absence of the needle shaft
within the guard. This sensing ball partially rests
between a stop surface on the ball retention element and
a further stop surface on the interior of the guard body.
By reason of its contact with the stop surface on the
ball retention element, this second ball prevents the
ball retention element from moving and thereby releasing
the first ball and latching system.
This sensing ball is, however, also retained in
place by the needle shaft against which it rests, and
towards which it is biased to move by pressure from the
ball retention means. This pressure arises from a spring
means which, conveniently may be the same spring means
that applies pressure against the locking element. This
second sensing ball is directed by the inclination of the
further stop surface on the guard body to be displaced
into the path of the needle. It is blocked from so
2~'~~~~~
12
moving by the needle, so long as the needle passes fully
through the guard.
Once the tip of the needle is withdrawn into
the guard past the sensing ball, leaving this second or
sensing ball no longer in contact with the needle the
sensing ball will move into the path previously occupied
by the needle. This displacement of the sensing ball
then allows the ball retention element to move
sufficiently to release the latching ball, and thereby
release the jaws in order to effect locking of the guard
to the needle.
Thus, in this embodiment the latching means is
distinctly removed from the trigger means, and two
independent parts, the latching ball and the sensing ball
must both be displaced from their positions in order for
locking to occur.
The locking force of the jaws within the chuck
is enhanced by any attempt to further remove the guard
from the needle. Conversely, it is reduced by an attempt
to cause the needle tip to re-emerge from the guard.
Conveniently, the presence of the sensing ball in the
needle path can serve to prevent such a re-emergence.
Thus, we summarize these embodiments as
providing a tip protective guard for covering the tip of
a needle of comprising:
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13
(1) a main guard body provided with a passage
therethrough capable of enveloping a needle
inserted therein, said body contains a
narrowing interior cavity that provides an
angled jamming surface;
(2) a locking element or jamming means slidable
within said cavity capable of locking relative
movement between said needle and said body in
at least one axial direction of said needle;
(3) spring means capable of biasing said jamming
means to advance into the narrowing interior
of said tapered cavity and lockingly engage
said needle in at least one axial direction of
said needle;
(4) latching means positioned to releaseably
restrain said jamming means from being
advanced into said cavity;
(5) trigger means, positioned to release said
latching means when the tip of said needle is
withdrawn into said guard body; and
(6) containment means for preventing re-emergence
of said needle tip from said body once the
needle tip has been withdrawn into said body.
In yet another embodiment of the invention, the
angled surface described above is carried by a canting
funnel held in place in its orientation by a lever arm.
14
This funnel and lever arm may be formed of a flat,
hardened strip, bent in the shape of a broad U to provide
a tapered funnel lying in the plane of the needle shaft,
nearly coaxially with the needle and with the lever arm
extending from the funnel in the direction of the
funnel's opening.
The lever arm, which serves as an alignment
means for the canting funnel, is contained within the
body of the guard device. An end of the funnel remote
from the lever arm is held in contact with the body of
the guard device by the force of a helical compression
spring. The funnel's point of contact with the internal
face of the body serves as a pivot point and clearance is
provided for the funnel and lever arm to pivot about this
pivot point. The spring is seated within a cylindrical
cavity in the body on the opposite side of the needle
shaft from the pivot point, the axis of the funnel being
close to and, initially, nearly or substantially parallel
with the needle axis. The free end of the spring extends
from its seat to press against the outer, central end of
the funnel on the side remote from the lever arm and
pivot point. This biases both the funnel and the leg of
the lever arm to rotate with respect to the needle shaft,
the lever arm being urged towards the needle. With the
needle extending through the body of the guard device,
the lever arm is constrained by the contact of its outer
21'~~~.~.
end with the side of the needle shaft. So long as this
contact occurs, the lever arm maintains the orientation
of the funnel unit with respect to the needle axis.
When the guard is slid along the needle so that
5 the tip end of the needle has entered the guard body and
moved past the point of contact with the end of the lever
arm, the lever arm is freed to turn about the pivot point
under spring pressure applied to the funnel. This causes
the funnel to cant with respect to the needle. The
10 spring then forces a jamming element, preferably in the
form of a hardened ball, into the newly-formed, tapered
gap existing between the inner surface of the funnel and
the needle. This action causes substantial frictional
contact and locking engagement between the guard body
15 through the hardened ball and the needle shaft.
With the selection of the known appropriate
geometry of the funnel's inner jamming surface and needle
shaft, critically related to the coefficient of friction
between them, the frictional grip between the jamming
element and the needle shaft may be arranged to always be
greater than the applied axial force on the needle. Thus
further axial motion of the needle in at least one
direction is prevented until material failure occurs.
By way of further security, the needle-
contacting end of the lever arm is provided with a
blocking plate which becomes displaced into the needle
217~~:~.9
16
path once the needle is no longer in contact with the
plate-carrying end of this leg. This serves to block the
reverse displacement of the needle, ensuring the complete
containment of the needle tip within the protective
guard.
A loosely-fitting cylindrical sleeve
surrounding the body of the guard is preferably added in
all cases to provide rotational isolation from the means
used to move the guard axially on the needle shaft,
thereby preventing the forcible removal of the protective
guard by accidental or deliberate twisting of the guard
relative to the needle. Such a sleeve may optionally be
applied to all embodiments of the protective guard.
A catheter with an insertion needle or wire is
particularly suited to carry a needle tip protector of
the type described.
The foregoing constitutes a description of a
series of exemplary modes by which the protective guard
may be clamped or locked in place so as to conceal a
needle tip. These mechanisms all rely upon introducing
a jamming element into a tapering space existing between
a needle and a jamming surface. Details of these
mechanisms are further described in the following
sections in conjunction with the description of the
preferred embodiments.
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17
The foregoing summarizes the principal features
of the invention and some of its optional aspects. The
invention may be further understood by the description of
the preferred embodiments, in conjunction with the
drawings, which now follow.
BRIEF SUN~IARY OF THE DRAWINGS
Figure 1 shows a hypodermic needle fitted with
the subject guard device, mounted on a syringe, and with
the needle removed from its protective sheath preparatory
to use;
Figure 2 shows the needle following use, with
the subject guard device being slid towards the end of
the needle by hand as the first step in the disposal
sequence;
Figure 3 shows the guard device locked
automatically over the end of the needle, and the needle
removed from the syringe for disposal
Figure 4 shows an embodiment of the guard
device in its protective sheath prior to use, this
embodiment including a detachable handle on the guard
device;
Figure 5 shows the device of Figure 4 removed
from its protective sheath and mounted on a syringe,
ready for use;
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18
Figure 6 shows the device of Figure 5 following
use of the needle, with the protective device being moved
along the needle with the detachable handle;
Figure 7 shows the device of Figure 5 with the
protective device locked on the end of the needle and the
detachable handle pulled free for disposal;
Figure 8 is a partial cross-section of the
device in an embodiment incorporating jaws within a
chuck, shown in its unlocked state;
Figure 9 is a cross-section of Figure 8 showing
an end view of the locking jaws, viewed from within;
Figure 10 is a partial cross-section showing
the device of Figure 8 in its locked state;
Figure 11 is a perspective view of the device
of Figure 8 showing the locking jaws and their means of
retention:
Figure 12 is a partial cross section of the
device in the embodiment incorporating locking rollers
within a tapered cavity, shown in its locked state;
Figure 13 is a cross sectional end view of
Figure 12;
Figure 14 is a partial perspective view of the
locking sleeve portion of Figure 12, showing the
placement of the locking rollers within their containment
means;
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19
Figure 15 is a partial cross-section of the
device in the embodiment incorporating locking balls
within a conical bore, shown in its locked state;
Figure 16 is a cross-sectional end view of
Figure 15;
Figure 17 is a partial perspective view of the
locking sleeve portion of Figure 15, showing the
placement of the locking balls within their containment
means;
Figure 18 is a partial cross-section of the
device in the alternate embodiment employing locking
leaves and a needle sensing and trigger mechanism, shown
in its unlocked state.
Figure 19 is a partial cross-section of Figure
18 showing the latch shaft in its unlocked position.
Figure 20 is a cross-section of the device of
Figure 18 in its unlocked state, rotated ninety degrees
from Figure 18.
Figure 21 is a cross-section of Figure 20
showing the locking leaves in their unlocked position,
viewed from within.
Figure 22 is a cross-section of the device of
Figure 18 in its locked state.
Figure 23 is a cross-section of Figure 22
showing the latch in its locked position.
2~7$~.1J
Figure 24 is an exploded perspective view of
the device of Figure 22.
Figure 25 shows the guard device of Figure 37
fitted to an intravenous catheter assembly, prior to
5 insertion into a patient;
Figure 26 shows the catheter inserted into a
patient with the guard in place on the catheter and the
needle being withdrawn;
Figure 27 shows the needle fully withdrawn
10 from the catheter with the guard locked over the point of
the needle;
Figure 28 shows a catheter hub with needle
protector in cross-section, based on a double trigger
mechanism utilizing on a ball-latch and sensing ball
15 system, in cocked condition;
Figure 29 shows the device of Figure 28 in
transition to grasping the needle
Figure 30 shows the device of Figure 28/ with
the needle grasped by the guard element and deployed as
20 a protector over the needle tip;
Figure 31 is a side view of the jaw element of
Figure 28;
Figure 32 is an end view of the jaw element of
Figure 28:
Figure 33 is a further side view of the jaw
element of Figure 28;
21
Figure 34 is an end view cross-section through
Figure 33;
Figure 35 is a side view cross-section through
Figure 32; and
Figure 36 is an end view cross-section of the
jaw element of Figure 30 as it embraces a needle.
Figure 37 is a longitudinal section of the
"canting-funnel" needle guard device in its unlocked
state, prior to use of the needle.
Figure 38 is a cross-sectional view of Figure
37.
Figure 39 is a longitudinal section of the
device of Figure 37 in its locked state, after use of the
needle and deployment of the needle guard.
Figure 40 is a cross-sectional view of the
locking mechanism of Figure 37 in the locked state,
fitted to a large-diameter needle.
Figure 41 is a cross-sectional view of the
locking mechanism of Figure 37 in the locked state,
fitted to a small-diameter needle.
Figure 42 is a partial longitudinal section of
the unlocked device of Figure 37, with two needle sizes
and two locking balls superimposed.
Figure 43 is a side view of the locking arm of
Figure 37.
Figure 44 is a top view of Figure 43.
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22
Figure 45 is a bottom view of Figure 43.
Figure 46 is a right-end view of Figure 43.
Figure 47 is a left-end view of Figure 43.
Figure 48 is a cross-sectional view of the
funnel portion of Figure 43.
Figure 49 is a side view of the inner body of
the device of Figure 37.
Figure 50 is a left-end view of Figure 49,
showing the needle being inserted during assembly.
Figure 51 is a top view of Figure 49.
Figure 52 is a partial oblique longitudinal
section of Figure 49, with locking ball, spring, and
locking arm shown in the unlocked state.
Figure 53 is an oblique cross-section of Figure
49 showing the needle cavity and spring cavity.
Figure 54 is the partial oblique section of
Figure 52, showing the first stage of the installation of
the locking ball and its spring.
Figure 55 is the partial oblique section of
Figure 52, showing the second stage of the installation
of the locking ball and its spring.
Figure 56 is the partial oblique section of
Figure 52 , showing the third stage of the installation of
the locking ball and its spring.
Z17~1
23
DETAILED DESCRIPTION OF EMBODIMENTS
Referring to Fig. 1, the hypodermic needle 1 is
attached to the syringe 2 by a needle connector or base
element 3 of conventional design as regards its
attachment to the syringe. The needle is optionally
provided with a guard retainer 4 in the form of a hollow
cylinder coaxial with the needle, with one end attached
to the needle connector element 3 , and with its other end
directed towards the opposite or tip-end of the needle.
This cylinder 4 attaches frictionally to the outer
circumference of the guard device 5, hereinafter referred
to as the "guard" or "protective guard".
The guard may be removed axially from the guard
housing 4 with normal finger effort, and thereafter may
be slid axially with slight or no frictional resistance
along the length of the needle. Alternately, the
retainer 4 may be detached from the base 3 and used as a
gripping means to slide the guard along the needle.
While the retainer 4 provides convenience in coupling and
handling the parts of the needle assembly, it is purely
optional. If omitted, the guard 5 may be provided with
a tight sliding fit on the needle 1 that will allow it to
be stored on the needle 1 near the base 3 without use of
the retainer 4.
Prior to use, the needle 1, guard retainer 4,
and guard 5 may be stored in a protective sheath 6 of
21'~~~.~
24
conventional design. The sheath 6 may be fractionally
retained axially on the retainer 4 by inwardly-directed
detent projections on the inner bore of the sheath entry
opening, following well-established practice. Such
established practice allows the needle to be retained
within and gripped by the protective sheath while fitting
the needle to the syringe or other device. The
frictional coupling between the sheath 6 and retainer 4
is selected to release more easily than the coupling
between the retainer 4 and needle base 3. This allows
for removal of the sheath 6 without disturbing the
retainer 4 or guard 5. The sheath 6 may optionally be
provided with an inner shoulder 7 which will axially bias
the guard 5 towards its stored position inside the
retainer 4.
Referring to Fig.2, all motions of the guard 5
during the disposal process are axial and directed away
from the point of the needle 1, with the hands held away
safely to the rear of the latter. Provided the guard 5
is not slid beyond the point of the needle 1, it may be
slid in either direction along the needle, and may be
returned to its stored position in the retainer 4 if
desired. While fractionally stored in and when released
from its retainer 4 the guard 5 is in its unlocked state.
As shown in Fig. 3, when the guard 5 reaches
the end of the needle 1, and when the point of the needle
21'~~?~~
is entirely enclosed within the guard, an armed locking
mechanism within guard 5 is released to firmly grip the
guard to the needle 1. Preferably, as shown in the
exemplary trigger mechanisms described next, the opening
5 in the outer end of the guard is closed-off to completely
cover the point of the needle against accidental
protrusion, even in the event of failure of the locking
mechanism to hold the guard in place against impact, such
as may be caused by dropping the needle and attached
10 syringe. The guard 5 is now in what is referred to
herein as its locked state.
In instances where it is desirable to increase
the separation between the operator's fingers and a
possibly contaminated needle, a further embodiment
15 provides a detachable handle to allow the operator to
slide the guard device along the needle from a safe
distance. Fig. 4 shows this embodiment, where detachable
handle 38 is frictionally attached to guard 5, and the
assembly of needle 1, guard 5, and handle 38 are encased
20 in protective sheath 39, ready for use. The entry of
protective sheath 39 is provided with a with a key-hole
shaped cross-section to accommodate handle 38, and the
other retaining features described above would also be
included in the entry of this sheath.
25 In Fig. 5, syringe 2 has been fitted to the
needle connector or base 3, the circular clip 40 of
21'~°11~
26
handle 38 has been snapped over the body of syringe 2 for
retention, and the needle and guard assembly has been
removed from the protective sheath ready for use. Handle
38 is frictionally attached to guard 5 by circular clip
41.
Fig. 6 shows guard device 5 being slid along
needle shaft 1 following use, using handle 38. When
guard 5 locks on the end of needle 1, handle 38 may be
detached for disposal by pulling or twisting, as shown in
Fig. 7.
Figures 8 and 10 show a first example of
locking system before and after engagement. The general
locking means comprises three locking jaws 55 contained
in a gently tapered conical cavity in the form of a bore
56 in the chuck body 43. In this example, these jaws are
formed from sheet material into an approximately C-shaped
cross-section and then hardened although alternate forms
may be used. These are arranged uniformly about the
needle shaft as shown in Fig. 9, and are retained loosely
in this position by fingers 57 extending axially from the
end of pressure sleeve 47, and fitting inside the jaws
55. This is shown in Fig. 11, one jaw being omitted for
clarity.
Fingers 57 extend from a reduced portion or
spigot 58 of pressure sleeve 47, to allow entry of the
latter into bore 56 during locking. This spigot is
27
provided with axial slots 59 as shown in Fig. 11 to allow
its outer end to collapse slightly in diameter as it is
forced into the tapered bore 56. Further elasticity is
imparted to this spigot bore 60, shown in Fig. 8, by a
reduction in its wall thickness in the vicinity of its
junction with the main body of the pressure sleeve 47.
A greater wall thickness is retained at its outer end
where it presses against the locking jaws 55.
In the locked state, pressure sleeve 47 is
released by latch 42 described further below and its
spigot drives j aws 55 into the narrowing annular space 56
between the needle shaft 1 and the tapered bore 56,
forcing the jaws 55 against the needle shaft 1. Contact
between the two is made along the narrow rectangular
edges of the C-shaped jaws 55. By finely serrating these
edges in the blanking stage of forming the jaws, the
coefficient of friction between jaw and needle shaft may
be substantially increased.
By providing a suitable length of tapered bore
56, this clamping means can accommodate a range of needle
diameters.
A further embodiment is shown in Fig. 12,
wherein the general locking means comprises a plurality
of locking rollers 61 of hardened material, two being
shown in this example. These are loosely contained in an
axially tapering cavity 62 of substantially rectangular
21'~8~1.~
28
cross-section in the body 43 of the guard device. Each
locking roller 61 is loosely retained within a
substantially rectangular cavity 63 in a rectangular
extension 64 of pressure sleeve 47, with the axis of each
locking roller 61 in a common plane perpendicular to the
axis of the needle shaft 1, and with each roller 61
uniformly disposed about the axis of needle shaft 1, as
shown in Fig. 13.
In the unlocked state, the pressure sleeve 47
is held by the latch 42 against the pressure of the
spring 49 as described above, such that the locking
rollers 61 are held loosely by extension 64 in the larger
portion of the tapered cavity 62, making no significant
contact with the walls 65 of the cavity 62 or with the
needle shaft 1. In this state, the needle shaft 1 is
free to move both axially and rotationally within its
bore 92 in the guard device.
In the locked state, as shown in Fig. 12, the
latch 42 releases the pressure sleeve 47 by the same
action as described further below to move under pressure
of spring 49 towards the narrowing end of cavity 62 as
described above, so that extension 64 carries the locking
rollers 61 into contact with the wall 65 of the tapering
cavity 62 on the outside and the needle shaft 1 on the
inside. Motion of the needle shaft 1 relative to the
body 43 in the same direction as the spring directed
2~7~1~.J
29
motion of pressure sleeve 47 will cause the locking
rollers 61 to roll further into the gradually narrowing
end of cavity 62 , exerting a high radial pressure against
the wall 65 and the surface of the needle shaft 1. This
prevents further motion of the needle by frictional grip
between the rollers 61, the cavity walls 65, and the
needle shaft 1.
By providing a suitable length of tapered
cavity 62 , this clamping means can accommodate a range of
needle diameters from any arbitrary maximum value down to
near zero.
A further alternate embodiment is shown in Fig.
15, wherein the general locking means comprises a
plurality of locking balls 66 of hardened material, three
being shown in this example, as more clearly seen in Fig.
16. The balls 66 are loosely contained in an axially
tapering bore 67 of circular cross-section in the body 43
of the guard device. Each locking ball 66 is loosely
retained within a cage optionally composed of a
substantially cylindrical cavity 68, the axis of each
said cavity being perpendicular to the needle axis in a
cylindrical extension 69 of pressure sleeve 47. The
center of each locking ball 66 lies in a common plane
perpendicular to the axis of the needle shaft 1, and the
balls 66 are disposed uniformly about the needle shaft 1,
as shown in Fig. 16. In all other respects, the action
2~7~~~
of the locking balls 66 in the locked state is similar to
that of the locking rollers 61 as described above.
By providing a suitable length of tapered bore
67, this clamping means can accommodate a range of needle
5 diameters from any arbitrary maximum value down to a
minimum diameter determined by the point at which the
locking balls come into contact with one another. When
three balls are used, this minimum needle diameter is
theoretically approximately 0.155 of the diameter of the
10 locking balls. Considerations relating to the retention
of the locking balls place a practical limit of
approximately 0.3 of the ball diameter. The minimum
diameter of needle which can be gripped becomes
progressively larger as more than three balls of a given
15 size are used.
Thus, three alternate embodiments have been
described which rely on a narrowing cavity to achieve the
locking effect. The latch and trigger mechanism
referenced for each case has been of a type that relies
20 on a transverse rotating cylinder. Alternate latch and
trigger system could be substituted, relying, for
example, on the later described sensing ball or lever arm
types of systems.
For completeness of understanding ,the
25 transverse rotating cylinder latch will now be described
31
with respect to an alternate "push-nut" needle engagement
system.
The generally assembly of the components for
this embodiment may be seen in exploded view Fig. 24
wherein a pair of locking leaf elements 51 are mounted on
a rim 52 within a body 43, coaxially with the needle 1.
Referring to Fig. 18, latch shaft 42 is mounted
transversely in the body 43. a portion of the left side
of latch 42 is relieved to form a flat surface 44 in the
axial plane on either side of an unrelieved center
portion 45, through which the needle shaft passes at
right angles to the latch axis, thus preventing its
rotation in the body 43.
Sliding axially in the bore 46 of body 43 is
pressure sleeve 47, in the form of a hollow cylinder,
largely closed at the right end. A portion of its left
half is cut away to form bifurcated arms 48 which engage
the plane surfaces 44 of latch 42, thus preventing motion
of the pressure sleeve to the right when latch 42 is in
the position shown.
Referring to Fig. 20, pressure sleeve 47 is
pressed to the right by compression spring 49, whose
leftwards reaction is taken by spring plunger 50, sliding
freely within sleeve 47, and which presses against latch
42. The latter 42 holds plunger 47 away from the ends of
locking leaves 51, which are retained in bore 46 by
32
retaining rim 52, integral with leaves 51. The rim 52 is
deflected out of its free form to produce a slight
interference fit in bore 46, thereby allowing it to be
retained at the bottom of the bore.
The locking leaf assembly is shown in Fig. 21,
two leaves being shown in this example. optionally one
leaf or more than two leaves could be employed with
equivalent results. In Fig. 20 spring pressure to the
right on sleeve 47 is transmitted to the plane surfaces
44 of latch 42 by arms 48, the ends of which are radially
separated from the axis of latch 42 by distance 53. This
forms a small turning moment tending to cause rotation of
the latch in a clockwise direction as viewed in Fig. 18,
this rotation being prevented by the needle shaft passing
through the axis of the latch.
In Fig. 22, needle 1 has been withdrawn until
its tip is inside body 43 and free of latch 42, allowing
the latter to rotate until its plane surfaces 44 are
parallel with the axis of pressure sleeve 47. This
allows the latter to slide to the right past the latch
and apply spring pressure to the ends of locking leaves
51, pressing them against the needle shaft 1. This locks
the latter in position, preventing further motion to the
right, relative to the body. The continued engagement of
the arms 48 of sleeve 47 with the cut-away portions of
33
latch 42 prevents the latter from falling out of body 43,
and from rotating significantly about its own axis.
The needle is now prevented from withdrawing
from body 43 to the right, and as latch 42 is now turned
and locked in position with its needle held 54 at right
angles to the needle axis, the needle point cannot re-
emerge from the left end of the body, even though the
one-way locking action of leaves 51 may permit motion in
this direction.
The foregoing description has, therefore, shown
one form of needle sensing latch and trigger mechanism.
A further such alternate mechanism will be
described below in conjunction with an additional needle-
engagement system mounted on a catheter/needle assembly.
The use of the guard on such an assembly will first be
described.
Fig. 25 shows the protective guard device 5
fitted to a needle 1 and attached to a catheter 118 as
part of an intravenous catheter assembly. The outer
shell 113 of the guard extends over and is fractionally
retained on the tubing attachment chuck 119 or base of
the catheter 118. The needle 1 extends through the guard
5 and the catheter 118 to emerge slightly beyond the
distal end 120 of the catheter. The needle may be moved
freely within the catheter 118 in any direction, either
axially or rotationally, impeded only by the slight drag
34
of the latch 109 of guard 5 and the constriction of the
reduced end 120 of the catheter tube 118.
The inner diameter 121 of the extended portion
of shell 113 is such as to provide a frictional axial
retention force between shell 113 and catheter chuck 119
significantly greater than the maximum axial drag of
needle 1 within guard 5, and comparable to the initial
axial retention familiarly encountered between the needle
and catheter in a conventional intravenous catheter
assembly. This retains guard 5 on catheter chuck 119
during needle withdrawal, as shown in Fig. 41. Here the
operator has inserted needle 1 and catheter 118 into a
blood vessel in the patient 122, and is withdrawing
needle 1 from catheter 118 through guard 5, holding
catheter 118 in place with one hand 123 and holding
needle 1 with the other hand 124. The guard 5 remains
frictionally retained on chuck 119 of the catheter.
When the needle point passes into the body of
the guard 5, the guard 5 locks automatically onto needle
shaft 1, the operator exerts a slightly increased
withdrawal force on the needle, sufficient to release
guard 5 from catheter chuck 119, as shown in Fig. 42.
The operator can now dispose of the protected needle
without further action, while attending to the catheter
tube attachment.
35
A further embodiment is shown in Figures 28 to
36. This version relies on a ball-latching mechanism to
maintain the guard in a cocked condition, and a
sensing-ball arrangement to serve as the trigger. This
embodiment is shown in a form adapted to be installed on
a catheter assembly. It could equally be applied to a
straight needle, as used on a syringe.
Prior to use, the needle guard assembly Fig.
28-36, inclusive, is housed largely within the base of
the catheter 209. The guard base 201 provides radial
support for the base 210 of the needle 1 but does not
fictionally retain it axially. The guard shell 202,
which is retained on guard base 201 by snap-fit shoulders
212, has an outer surface tapered to fit the
correspondingly tapered bore 213 of the catheter base
209, with moderate axial frictional retention therein.
During insertion of the catheter, the necessary
axial thrust is transferred from the face 214 of the
needle base 210 to the guard base 201 and thence through
face 215 of the latter to catheter base 209, without
affecting the respective radial fits described the
paragraph directly above.
During withdrawal of the needle from the
catheter, the needle base 210 readily releases from the
guard base 201, while the latter is axially retained
36
within the catheter base 209 by the greater frictional
grip between the two.
With the needle 211 passing wholly through the
needle guard assembly as in Fig. 28, interval plunger 203
is urged towards the pointed end of the needle 211 by
compression spring 204, but is prevented from moving
axially by the three-point confinement of sensing ball
205, which makes contact with plunger 204 against the
latter's perpendicular end face at point 216, against the
sloping internal end face 227 of guard shell 202 at point
217, and against the needle shaft 211 at point 218. The
sensing ball 205 is free to move orbitally about the
needle axis in the annular space 219 surrounding the
needle.
The reactionary force at the opposite end of
spring 204 acts against the perpendicular end face of the
pair of locking jaws 206 and 207, but motion of these
latter parts is prevented by the confinement of latching
ball 208. This makes contact with jaw 207 on the curved
side of its guard 220 at point 221, with the
perpendicular end face of guard base 201 at point 222,
and with the cylindrical inner surface of plunger 203 at
point 223. Axial motion of locking jaw 206 is prevented
by its being axially locked to jaw 207 as will be
described below. Latching ball 208 is free to move
37
orbitally about the needle axis in the annular space 224
surrounding locking jaws 206 and 207.
With jaws 206 and 207 held axially as shown in
Fig. 29, their tapered outer surfaces are confined within
the correspondingly tapered inner bore 225 of guard base
201 to an extent sufficient to radially support the
needle shaft 211 on the cylindrical inner surfaces 226 of
the locking jaws, yet without developing sufficient
frictional contact to significantly impede the axial
movement of the needle shaft through the jaws.
Similarly, the pressure of plunger 203 against
sensing ball 205 is re- directed by contact point 217 to
produce a reduced force at contact point 218, such that
the frictional force between the polished surfaces of
sensing ball 205 and needle shaft 211 negligibly impedes
the axial movement of the needle shaft 211 within the
needle guard.
As the point of the needle enters the needle
guard during withdrawal, sensing ball 205 passes over the
end of the needle, following the inclined inner end face
227 of body shell 202, under the axially-directed urging
of plunger 203, driven by spring 204. The greatest
extent of this motion before the sensing ball 205 becomes
free of the needle occurs with the bevel 228 of needle
211 rotationally oriented to be tangent with the surface
of ball 205 as shown in Fig. 29, and with the point of
2~.7~~~.~
38
tangency 229 being on the end of a line passing through
the centre of the sensing ball 205 to an opposite point
of contact 230 between the sensing ball 205 and the
corner of ball socket 231 in the end of guard shell 202.
It will be seen that the configuration in Fig.
29 is a critical one, in that reversal of the needle
withdrawal motion will not cause the ball to likewise
reverse its motion towards the configuration of Fig. 28,
because the force exerted on the ball by the tangential
face 228 of the needle acts on a line through the centre
of the ball, and therefore cannot move it in any
direction. It will be seen further that when the
configuration of Fig. 29 is reached, the spring-driven
plunger 203 will force sensing ball 205 free of the
needle 211, and drive it into ball cavity 231, as shown
in Fig. 30.
With the configuration of Fig. 29, the geometry
of the containment of latching ball 208 is the same as in
Fig. 28, so that the locking jaws 206 and 207 cause no
significant resistance to the axial motion of the needle
211, yet continue to provide radial support to it. Thus
the withdrawal motion of the needle 211 can continue
beyond the critical configuration of Fig. 24, ensuring
that sensing ball 205 is released into its cavity 231 to
block the re-emergence of the needle point, before the
locking jaws 206 and 207 are activated.
39
When the plunger 203 moves to the position of
Fig. 30, it releases latching ball 208 from the
confinement of Figs. 28 and 29, allowing locking jaws 206
and 207 to be driven by spring 204 into the confinement
of tapered bore 225 in guard base 201. This causes the
jaws 206 and 207 to grip the needle shaft 211. The angle
of taper of bore 225 is critically selected with respect
to the coefficients of friction between the jaws 206 and
207 and needle shaft 211 and between the jaws and bore
225, such that the axial component of frictional grip
between the jaws and the needle shaft is always greater
than the externally-applied axial force on the needle,
which develops this gripping force. Thus the needle
cannot be withdrawn from the needle guard, as the
gripping force of the jaws on the needle increases with
withdrawal force until material failure occurs.
Re-emergence of the needle is resisted to a much lesser
degree by the locking jaws 206 and 207, but such
re-emergence is blocked by the sensing ball 205 which now
blocks the exit path of the needle 211 from the guard.
The self-locking action of the jaws in the
direction of withdrawal of the needle from the guard is
independent of the axial force on the jaws of spring 204,
and the latter acts only as the initiator of the locking
action, by moving the jaws onto the confinement of
tapered bore 225. Once in this position application of
40
further withdrawal force on the needle 211 enhances the
locking effect of the jaws 206 and 207 as they are drawn
deeper into the narrowing cavity of the tapered bore 225.
The rotational component of the coefficient of
friction between locking jaws 206 and 207 and bore 225 is
significantly less than the rotational component of the
coefficient of friction between the locking jaws and
needle shaft 211. This maintains the rotational grip
between the locking jaws and the needle shaft if the
latter is rotated with respect to the needle guard, with
relative rotation occurring between the locking jaws and
bore 225.
The locking jaws 206 and 207 are shown in
enlarged views Figs. 31 to 36. The two jaws are
identical, each having a substantially rectangular lug
234 extending from its diametral place on one side of its
central axis, which engages a corresponding substantially
rectangular recess 235 in the opposite jaw when the two
are placed together on a common diametral place. The
resulting engagement of each lug and recess prevents
relative axial reaction of the two jaws. This allows the
use of a single latching ball 208, as described above,
holding the two jaws as an axially-coupled pair in the
unlocked position.
41
The tapered outer surface 232, Fig. 31, is
polished to reduce the coefficient of friction between
the jaw and the bore 225 of the guard body 201.
The internal bore 226, Fig. 36, is provided
with a relatively coarse surface finish, and is
furthermore of a slightly smaller diameter than that of
the needle shaft 211. This produces contact with needle
shaft 211 along axial lines of concentrated pressure 233,
as shown in Fig. 36. This causes the exclusion of any
bodily fluids which may be on the surface of the needle,
and provides a high frictional grip both axially and
rotationally.
This last embodiment demonstrates the use of a
narrowing-cavity or chuck-action clamping system, in
combination with a sensing ball trigger mechanism. A
second latching ball is also employed to maintain the
guard in its cocked condition. The major components in
this embodiment may be readily manufactured by inj ection
molding without onerous tolerance requirements, and this
design has the capacity of having one size fit a range of
needle diameters.
A further "ball-in-funnel" variant of
embodiments of the invention is shown in Figure 37, which
is a longitudinal section of the device. Here the
locking means comprises a locking arm 301, right-hand
portion 302 of which is in the form of a conical tube or
2~7~~~~
42
funnel, of generally pear-shaped cross section, more
particularly shown in Figures 43 to 48. This funnel
loosely encloses needle 1, as shown in Figure 38, except
for a slot 303 in one side, which allows the lateral
insertion of needle 1 during assembly. Locking arm 301
is furnished with a substantially rectangular extension
from the large end of the funnel 302, bent in the general
shape of a sickle to form a sensing end 306.
In the needle guard's unlocked state as shown
in Figure 37, arm 301 is canted toward the top of the
assembly, pivoting about its point of contact 317 between
the small end 305 of the funnel and needle guard body
308. The positioning of needle 1 in funnel 302 is shown
in cross-section Figure 38.
As shown in Figure 37, in the absence of other
forces on arm 301, the left end of the latter is held in
this position by its sensing end 306 pressing against
needle 1 at point 307, preventing its movement downward.
Notch 365, more clearly shown in Figure 47, prevents
lateral movement of end 306 on needle 1.
Significant upward movement of this end of arm
301 is prevented by its near-contact with needle guard
body 308 at surface 309. Similarly, right end 305 of arm
301 is confined between needle 1 and body 308 in the
region of contact point 317.
21'~~~.~~
43
Helical compression spring 310 is contained in
a largely compressed state within cavity 311 in body 308,
cavity 311 being shown somewhat simplified for clarity.
spring 310 exerts force with its right end against a
locking ball 312 so as to direct it to the right,
bringing the top of the ball against needle 1 at point
313, and its right side against edge 314 of the large end
of funnel 302 on locking arm 301.
The angle of the face of funnel edge 314 with
respect to the needle axis is such as to re-direct the
spring force to the right, along a line 338 through the
centre of ball 312, and at a perpendicular distance 315
from pivot point 317. This forms a turning moment,
tending to rotate locking arm 301 in a counter-clockwise
direction about pivot point 317. This motion is blocked
by contact of sensing end 306 with needle 1 at point 307,
as already described. The rightward direction of the
spring force against arm 301 also maintains its small end
305 in contact with inner face 316 of body 308 at point
317.
In this unlocked state of the needle guard,
axial motion of needle 1 through the guard is impeded
only by the small frictional forces occurring from
contact of the needle with locking arm 301 at points 304
and 307, with locking ball 312 at point 313, and with
body 308 at needle passages 318 and 319.
21~~~.1~
44
If needle 1 is drawn to the right through the
needle guard until its point 320 is in the position shown
in Figure 39 contact between sensing end 306 and the
needle is lost, allowing locking arm 301 to rotate
counter-clockwise under the urging of spring-driven ball
312, pressing against edge 314 of funnel 302, as already
described for Figure 37.
When locking arm 301 has rotated to almost the
position shown in Figure 39, ball 312 is able to move
past edge 314 of the funnel and to enter the converging
space 321 between the bottom of needle 1 and the lower
inner surface 322 of funnel 302. Travel of ball 312 is
halted when it becomes wedged between contact point 323
with needle 1 and contact point 324 with lower inner
surface 322 of funnel 302. The upward pressure from ball
312 on needle 1 at point 323 presses the needle into
contact with points 323 and 324, caused by the force of
spring 310, are moderate only, sufficient to ensure
rolling of the ball through friction if the needle is
moved axially.
If an attempt is made to remove needle 1 by
drawing it further to the right relative to the needle
guard, locking ball 312 will roll to the right with the
needle, entering more deeply into converging cavity 321,
and increasing the pressure at contact points 323 and
324. By setting the slope angle 325 of funnel 302 equal
45
to or less than a critical value Acrit, the resulting
leftward frictional forces developed on the needle by
this rolling and wedging action will always equal the
rightward force applied to needle 1 in attempting to
remove it from the needle guard.
If the coefficient of friction between the
needle and funnel surface and between needle and ball is
denoted as F, then it can be shown that the critical
value of angle 325 is:
Acrit - Siri-~t2F/(F2 + 1) ~
and is typically about twelve degrees. Provided that
angle 325 is less than this value, the maximum attainable
axial frictional force to the left on the needle,
generated by the external pull to the right, will always
exceed the pull, so that the needle cannot be removed
from the needle guard, unless material failure or
deformation occurs.
The rightward pull on needle 1 is transferred
through friction to funnel 302, and thence to body 308 by
engagement of the small end 305 of the funnel with inner
face 316 of the body.
If, after locking as in Figure 39, needle 1 is
pushed axially to the left with respect to the needle
guard, ball 312 will tend to roll with the needle out of
the confinement of funnel 302, releasing the wedging
action of the latter on the ball. This will release the
21'~8~~.9
46
grip of the needle guard on the needle, allowing the
latter to slide past ball 312 and move towards re-
emergence of needle point 320 from the guard. However,
sensing end 306 prevents this by solidly obstructing the
path of the needle point, and is maintained in this
position by ball 312 being held in space 321 by the force
of spring 310. Leftward force of needle point 320
against lever sensing end 306 is transmitted to body 308
by contact of end 306 with inside surface 362 of the end
of body 308.
The grip between funnel 302 and needle 1 is by
friction, without significant penetration of the needle
surface by ball 312. Thus, any rotation of the needle
about its axis relative to the funnel while an external
pull is applied to the needle will result in some axial
slippage of this frictional grip. This would allow the
needle to be deliberately removed from the needle guard,
by persistent rotating or twisting back and forth of the
needle in the guard.
To prevent this, a rotatable outer shell 326 is
preferably, though optionally, provided, fitting loosely
about body 308, as shown in Figure 39. Rightward axial
thrust against the outer shell by body 308 is transmitted
by spigot 327 on its right end, which fits into opening
360 on inner end face 328 of outer shell 326. Because of
the small diameter of the contact surface between spigot
2178~~~
47
327 and outer shell 326, the rotation resistance to
turning of body 308 within the shell is small, and less
than that between needle 1 and funnel 302 when locked.
This provides rotational isolation of the needle guard
from external handling.
Body 308 is typically pressed axially into the
open left end of shell 326 during assembly, and retained
within the shell by snap lips 329 formed on the open end
of the outer shell, and which engage left end face 330 of
body 308, as shown in Figure 39. Because needle opening
360 in closed end 361 of outer shell 326 is significantly
larger than the diameter of needle 1, the outer shell may
be safely passed over the end of the needle during
assembly.
Alternatively, outer shell 326 may be made in
two or more longitudinally-divided sections, optionally
hinged at their meeting edges, and designed to close
about the needle in book-fashion, with integral or
separate snap means provided to hold the sections in
their closed state. Alternatively, the sections may be
bonded together after assembly, using such means as
adhesive, ultra-sonic welding, or the like. Using such
an outer shell, all parts of the needle guard may be
assembled to the needle from the side.
Figure 40 is a cross-sectional view of the
needle, ball and funnel in the locked state of Figure 39,
217~11~
48
with other components omitted for clarity. The wedging
action of needle lA and ball 312A in funnel 302 is
transmitted to the funnel as outwardly-directed forces
along axial contact line 331 and at point 324
respectively. Because these forces are typically about
ten times the external pull which may be applied to
needle 1 in an attempt to remove it forcibly from the
locked needle guard, thickness 332 of the funnel must be
sufficient to provide adequate strength against spreading
apart of the funnel under such conditions.
Figure 41 is the same cross-section of funnel
302 as in Figure 40, but with needle lA replaced by
needle 1B of smaller diameter than that of figure 4.
Ball 312A has been replaced by ball 312B of
correspondingly larger diameter, so that their total
height 333 is the same as in Figure 40. This allows the
same locking arm 301 to be used for a number of different
needle diameters, simply by using different diameters of
locking ball 312. Furthermore, a given diameter of
locking ball may accommodate more than one needle
diameter, since minor differences in dimension 333 can be
accommodated simply by ball 312 locking at different
axial positions in funnel 302.
Figure 42 is a partial longitudinal section
similar to Figure 1, but with large needle size lA and
its small locking ball 312A superimposed on smaller
2~7~119
49
needle size 1B and its larger locking ball 312B. This
illustrates that in the unlocked state as described above
for Figure 37, essentially the same geometry of needle,
ball, and funnel occurs for two significantly different
needle sizes. This establishes for both configurations
the counter-clockwise turning moment on arm 301 required
to maintain sensing end 306 in contact with needle 1 in
this unlocked state, as already described.
Figure 49 shows body 308 in isolation as a side
view, rather than in section as in Figures 37 and 39.
This gives a more detailed view of needle passages 318
and 319 in the left and right ends, as well as needle
passage 334 and spring recess 311 in the central portion
335 of the body.
As more clearly seen in left end view figure
14, needle passage 318 is largely circular in cross-
section, but is pierced radially on one side by a wedge-
shaped slot 336, and on the other side by a generally
rectangular slot 337, which is an extension of slot 336.
The same general configuration is used in needle passages
319 and 334.
Slot 336, serves as an entry for the lateral
insertion of needle 1, while slot 337, which extends
axially partway into the bulk of body 308 over the axial
length of the latter, provides some hinge-like
flexibility to that portion of the body to allow the
50
needle passageways to open slightly. This permits needle
1 to snap past constriction 339 during assembly of the
needle guard, after which the constriction largely closes
behind the needle to confine it loosely in central
circular portion 318. To aid in this needle-insertion
process, wedge-shaped portion 336 may be expanded
temporarily by a generally wedge-shaped insertion bar
340, forming part of the assembly machine, and which also
provides the lateral insertion force 341 to needle 1
during insertion of the latter, as shown in Figure 50.
This lateral insertion allows the needle to be
installed in body 308 without having to pass the latter
over either end of the needle, thus preventing damage to
the pristinely sharp needle point 320. Similarly, slot
303 in locking arm funnel 302, Figures 43 and 48, allows
the needle to be placed in the funnel entirely from the
side, without jeopardy to the needle point.
Figure 51 is a top view of body 308 in
isolation, with a broken section, showing principally the
placement of spring cavity 311. This cavity is more
clearly seen in partial section Figure 52 , made along the
axis of cavity 311 by oblique section plane 16-16 shown
in Figure 49. Spring 310, ball 312 and lever 301 have
been added to Figure 52 to show their relationship to one
another as a top view in the unlocked state.
217~~~.J
51
Figure 53 is a section made transversely to the
axis of cavity 311 by oblique section plane 17-17 in
Figure 49. The spring 310 and ball 312 have been omitted
for clarity. As can be seen here, central portion 342 of
spring cavity 311 may be cored from the near side during
molding.
Referring to Figure 49, the remainder of cavity
311 comprises lower left portion 343 and upper right
portion 344, both cored from the far side of the body
during molding, as shown by broken lines in Figure 51.
Portions 342 and 343 are more clearly seen in Figure 53.
The closed ends of all three cavity portions consist of
semi-circular surfaces commonly centred on the axis of
spring cavity 311, and overlapping one another
alternately to form a continuous passage for spring 310.
This overlapping is also shown by the broken lines in
Figure 51.
As shown in Figure 52, cavity 343 forms a
closed left end surface 345 for the spring passage,
providing a seat for the fixed end of spring 310. The
closed semi-circular near-side end surfaces 363 and 358
of cavities 343 and 344 restrain spring 310 from moving
in direction 346. Similarly the semi-circular far-side
end surface 364 of cavity 342 restrains the spring from
moving in direction 347. Because the spring is smaller
21~~11~
52
in diameter than the spring passage enclosing it, this
restraint is radially loose.
Figures 54, 55. amd 56 are sections similar to
Figure 52, and depict an example of how the configuration
of spring cavity 311 is utilized during that part of the
assembly stage involving installation of spring 310 and
ball 312. This stage begins with needle 1 and locking
arm 301 already in place in body 308, and arm 301 placed
in the upwardly-canted, unlocked position shown in Figure
37: In Figures 54, 55, and 56 the needle is not shown,
and only the lower portion of funnel 302 of arm 301 is
visible, in section.
In Figure 54, insertion tube 348, which forms
part of the needle guard assembly machine, has been
obliquely inserted into the open near-side of cavity 342.
Locking ball 312 and spring 310 are shown being delivered
in sequence through tube 348 by plunger 349, moving in
direction 350.
In Figure 55, ball 312 has entered and passed
through cavity 342. Angled tip 351 of insertion tube 348
blocks any motion to the left by the ball, which has been
diverted to the right under the urging of spring 310,
pushed in turn by insertion plunger 349 in direction 350.
This diversion of the ball is aided by the insertion of
guide core 352 partway into cavity 344, forming a
temporary wall face 353 as a continuation of ball support
21'~~1~.;
53
face 354 on body 308. Ball 312 has crossed cavity 344,
to rest against edge 314 of funnel 302. The motion of
plunger 349 continues, compressing spring 310 against
ball 312.
In Figure 56 insertion tube 348 has been
partially withdrawn from cavity 342 independently of
plunger 349, and rotated about its axis by a half-turn,
so that its angle tip 351 now lies parallel to the needle
axis. Plunger 349 has advanced in direction 350 until
its angled tip 355 is level with end surface 358 of
cavity 344. This allows compressed spring 310 to expand
axially, with its left end sliding free in direction 357
as shown, until it seats itself against surface 345, as
shown in Figure 52. Insertion tube 348 and plunger 349,
together with guide core 352, are then retracted from
body 308, completing this stage of assembly.
With locking ball 312 in position in the
unlocked state as shown in Figure 52, it is restrained
from moving in direction 346 by cavity end surface 358,
and in direction 347 by support surface 354. During the
locking sequence, as edge 314 of funnel 302 begins to
drop from the position shown in Figure 37, ball 312
emerges from cavity 344 and away from the support of
surfaces 358 and 354. During this transition, curved
sides 359 of funnel 302, shown in Figure 52, provide
support in directions 346 and 347 by partially embracing
54
ball 312 until it fully enters the funnel and is seated
in its curved lower surface 322, as shown in Figures 39,
40, and 41.
All of the principal parts of the device may be
made of any suitable material, such as of injection
moulded plastic, eg. Nylon, or of corrosion-resistant
metal such as stainless steel, according to such
considerations as convenience of manufacture, cost and
other factors relevant to medical devices.
Throughout the foregoing disclosure a hollow
hypodermic needle has been depicted. The needle need
not, however, be hollow. The protective guard
contemplated by this invention is equally applicable to
solid needles, such as might be used for smallpox
inoculations or as solid cores for wire catheters.
CONCLUSION
The foregoing has constituted a description of
specific embodiments showing how the invention may be
applied and put into use. These embodiments are only
exemplary. The invention in its broadest, and more
specific aspects, is further described and defined in the
claims which now follow.
These claims, and the language used therein,
are to be understood in terms of the variants of the
invention which have been described. They are not to be
2~7~~~
restricted to such variants, but are to be read as
covering the full scope of the invention as is implicit
within the invention and the disclosure that has been
provided herein.
