Safety syringe abstract
A safety syringe has a hollow barrel, a plunger, a connector, a
plug and a needle hub. The plunger has a protrusion extended from
the plunger and along a longitudinal axis of the plunger. The connector
is mounted around the protrusion of the plunger. Multiple limit
stubs and multiple curved limit channels communicating with a corresponding
notch with an inclined side-wall are respectively formed on the
connector and a connecting chamber in a connecting tube of the needle
hub. When the plunger is being pushed towards the needle hub, the
multiple limit stubs respectively pass through the corresponding
curved limit channel and are contained in the corresponding notch.
The inclined side-wall of the notch will stably connect the limit
stub so the plunger can stably retract the needle hub in the hollow
barrel.
Safety syringe claims
What is claimed is:
1. A safety syringe comprising: a hollow barrel having a proximal
open end; and a distal open end; a plunger slidably mounted inside
the hollow barrel and having a distal end; a proximal end; a neck
formed integrally and extending from the proximal end of the plunger,
and having a distal end, a proximal end and a longitudinal axis;
a first positive limit attached to the proximal end of the neck;
a protrusion extended from the first positive limit and along the
longitudinal axis of the neck, and having a distal end and a proximal
end; and a second positive limit attached to the proximal end of
the protrusion; a plug mounted around the neck on the plunger; a
cylindrical connector rotatively mounted around the protrusion of
the plunger, and having a side-wall; a longitudinal axis; a through
hole formed along the longitudinal axis of the connector; and a
groove formed in the side-wall and parallel to the longitudinal
axis of the connector, and communicating with the through hole of
the connector; a needle hub mounted in the proximal open end of
the hollow barrel and having a connecting tube having a distal end;
a proximal end; and a connecting chamber formed in the distal end
of the connecting tube and having a proximal open end, a distal
end and an inner surface, wherein the connecting chamber has a radius
larger than that of the connector; and a needle attached to the
proximal end of the connecting tube and having a central passage;
and an engaging device formed between the connector and the connecting
chamber of the needle hub and connected the connector and the connecting
chamber of the needle hub together when the connector is inserted
in to the connecting chamber, and comprising multiple limit stubs;
multiple curved limit channels each corresponding to one of the
limit stubs and having a first inclined side wall; and multiple
notches each communicating with one of the curved limit channels
and having a second inclined side wall formed opposite to the first
inclined side wall on a corresponding one of the curved limit channels,
and the first inclined side wall formed near the corresponding notch,
wherein each notch is larger than the corresponding limit stub and
each limit stub wedges against the second inclined side wall of
the corresponding notch when the connector is inserted into the
connecting chamber.
2. The safety syringe as claimed in claim 1 wherein the push rod
further comprises a V-shape groove defined radially in the push
rod.
3. The safety syringe as claimed in claim 1 wherein the multiple
limit stubs protrudes from the side-wall of the connector; the multiple
curved limit channels are defined in the inner surface and opened
from the proximal open end of the connecting chamber; and the multiple
notches are formed in the inner surface of the connecting chamber.
4. The safety syringe as claimed in claim 3 wherein the push rod
further comprises a V-shape groove defined radially in the push
rod.
5. The safety syringe as claimed in claim 1 wherein the multiple
curved limit channels are defined in the side-wall of the connector
and open toward the needle hub; the multiple notches are formed
in the side-wall of the connector; and the multiple limit stubs
are protruded from the inner surface of the connecting chamber.
6. The safety syringe as claimed in claim 5 wherein the push rod
further comprises a V-shape groove defined radially in the push
rod.
Safety syringe description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a syringe, and more particularly
to a safety syringe that can stably retract the used needle.
2. Description of Related Art
A conventional syringe has a hollow barrel, a plunger and a needle
hub. Due to possible exposure to contagious diseases, the needle
of the syringe and even the hollow barrel and the plunger, should
not be used again and should be discarded immediately after use.
Also, to keep nurses, doctors or health workers who deal with discarded
syringes from getting injured or infected by used needles, a safety
syringe is needed. In particular, manufacturers have focused on
syringes with retractable needles so that once the syringe has been
used, the contaminated needle is entirely housed within the barrel
whereby the chance of infection through accidental pricking is eliminated.
A conventional safety syringe disclosed in Taiwan Pat. No. 356013
and comprises a hollow barrel, a plunger and a needle hub. The plunger
has a connector formed on one end of the plunger to connect with
the needle hub. The connector has a protrusion. The needle hub comprises
a chamber and an annular rib. The chamber has a distal closed end
and a proximal open end. The annular rib extends radially inward
from the proximal open end of the chamber. The protrusion of the
connector can be clipped by the annular rib of the needle hub to
connect the plunger and the needle hub together. When the plunger
is pushed to the needle hub, the connector of the plunger is pressed
by the annular rib of the needle hub and then contained in the needle
hub, whereafter pulling the plunger will retract the needle hub
into the hollow barrel.
However, the connector of the plunger and the needle hub often
separate from each other after the plunger is pulled back to retract
the needle hub. When the protrusion of the connector is pulled toward
the hollow barrel, since the needle hub is elastically connected
to the annular rib of the needle hub, the elastic connection often
slips to let the protrusion of the connector separate from the needle
hub. If the annular rib of the needle hub is produced small in order
to prevent from the protrusion of the connector separating from
the needle hub, the protrusion of the connector will be difficult
to mount in the chamber of the needle hub when trying to engage
the plunger with the needle hub.
SUMMARY OF THE INVENTION
The main objective of the present invention is to provide a safety
syringe that can have reliable engagement and separation between
a plunger and a needle hub. To achieve the objective, a safety syringe
in accordance with the present invention comprises a hollow barrel,
a plunger, a connector, a plug and a needle hub. The plunger is
slidably mounted in the hollow barrel, and has a neck to mount the
plug and a protrusion extended from the plunger and along a longitudinal
axis of the neck. The connector is mounted around the protrusion
of the plunger. The needle hub is mounted in one end of the hollow
barrel and comprises a connecting tube and a needle. Multiple limit
stubs and multiple curved limit channels communicated with a corresponding
notch with a second inclined side wall are respectively formed on
the connector and in the connecting chamber of the needle hub. When
the plunger is being pushed toward the needle hub, the multiple
limit stubs respectively pass through the corresponding curved limit
channel and are contained in the corresponding notch. The second
inclined side wall of the notch will stably connect the limit stub
so the plunger can stably retract the needle hub in the hollow barrel.
Further benefits and advantages of the present invention will become
apparent after a careful reading of the detailed description with
appropriate reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a safety syringe in accordance
with the present invention;
FIG. 2 is an exploded perspective view of the safety syringe in
FIG. 1;
FIG. 3 is a perspective view of the partial safety syringe in FIG.
1;
FIG. 4 is a perspective view of the partial safety syringe in FIG.
1 showing multiple limit stubs on a connector respectively mounted
into a corresponding recess inside a connecting tube;
FIG. 5 is a perspective view of the safety syringe in FIG. 1 showing
the needle hub retracted back into a hollow barrel; and
FIG. 6 is an exploded perspective view of a second embodiment of
a safety syringe in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIGS. 1 2 and 6 a safety syringe in accordance
with the present invention comprises a hollow barrel (10), a plunger
(20), a plug (30), a connector (4040'), an engaging device (not
numbered) and a needle hub (5050').
The hollow barrel (10) is cylindrical and has a proximal open end
(not numbered), a distal open end (not numbered), a lip (not numbered)
and an annular flange (not numbered). The lip extends radially inward
from the proximal open end of the hollow barrel (10) so the proximal
open end is smaller than the distal open end. The annular flange
extends radially out from the distal open end of the hollow barrel
(10).
The plunger (20) has a distal end (not numbered), a proximal end
(not numbered), a V-shaped groove (210), a neck (21), a first positive
limit (22), a protrusion (23) and a second positive limit (24),
and is slidably mounted inside the hollow barrel (10). The neck
(21) is formed integrally and extends from the proximal end of the
plunger (20), and has a distal end (not numbered), a proximal end
(not numbered) and a longitudinal axis (not numbered). The first
positive limit (22) is circular and attached to the proximal end
of the neck (21). The protrusion (23) is extended from the first
positive limit (22) and along the longitudinal axis of the neck
(21), and has a distal end (not numbered) and a proximal end (not
numbered). The second positive limit (24) is circular and attached
to the proximal end of the protrusion (23). The V-shaped groove
(210) is defined radially in the plunger (20).
The plug (30) is mounted around the neck (21) on the plunger (20).
The connector (4040') is cylindrical and rotatively mounted around
the protrusion (23) of the plunger (20), and has a side-wall (not
numbered), a longitudinal axis (not numbered), a through hole (4242')
and a groove (4343'). The through hole (4242') is formed along
the longitudinal axis of the connector (40). The groove (4343')
is formed in the side-wall and extends parallel to the longitudinal
axis of the connector (4040'), and communicates with the through
hole (4242') of the connector (4040').
With further reference to FIG. 3 the needle hub (5050') is mounted
in the proximal open end of the hollow barrel (10) and has a connecting
tube (5151') and a needle (52). The connecting tube (5151') has
a distal end (not numbered), a proximal end (not numbered) and a
connecting chamber (512512'). The connecting chamber (512512')
is formed in the distal end of the connecting tube (5151') and
has a proximal open end (not numbered), a distal end (not numbered)
and an inner surface (not numbered). The connecting chamber (512512')
has a radius larger than that of the connector (4040'). The needle
(52) is attached to the proximal end of the connecting tube (5151')
and has a central passage (not shown).
The engaging device is formed between the connector (4040') and
the connecting chamber (512512') of the needle hub (5050'). The
engaging device connects the connector (4040') and the connecting
chamber (512512') of the needle hub (5050') together when the
connector (4040') is inserted into the connecting chamber (512512').
In a first embodiment, the engaging device comprises multiple limit
stubs (41), multiple curved limit channels (510) and multiple notches
(511). The multiple limit stubs (41) protrude from the side-wall
of the connector (40). The multiple curved limit channels (510)
are defined in the inner surface and respectively correspond to
a limit stub (41), and each opens from the proximal open end of
the connecting chamber (512). The multiple curved limit channels
(510) are trumpet shaped and each curved limit channel has a first
inclined side wall (514). The multiple notches (511) are formed
in the inner surface and respectively communicate with a corresponding
curved limit channel (510), and have a second inclined side wall
(not numbered). The first inclined side wall (514) and the second
inclined side wall are formed oppositely and the first inclined
side wall (514) is formed near the notch (511). The multiple notches
(511) of the connecting tube (51) can respectively contain a corresponding
limit stub (41) and each notch (511) is larger than the corresponded
limit stub (41).
With reference to FIG. 6 a second embodiment of the engaging device
comprises multiple curved limit channels (44), multiple notches
(45) and multiple limit stubs (513). The multiple curved limit channels
(44) are defined in the side-wall of the connector (40') and open
toward the needle hub (50). The curved limit channels (44) of the
connector (40') are trumpet shaped and has a first inclined side
wall (46). The multiple notches (45) are formed in the side-wall
of the connector (40) and respectively communicate with a corresponding
curved limit channel (44), and each notch (45) has a second inclined
side wall (not numbered). The first inclined side wall (46) and
the second inclined side wall are formed oppositely and the first
inclined side wall (46) is formed near the notch (45). The multiple
limit stubs (513) protrude from the inner surface of the connecting
chamber (512') and correspond to the respective curved limit channel
(44) of the connector (40'). The multiple limit stubs (513) of the
connecting tube (51') can be respectively contained in the corresponding
notch (45) of the connector (40'). Each limit stub (513) is smaller
than the corresponding curved limit channel (44) of the connector
(40').
With further reference to FIGS. 3 and 4 the safety syringe is
used and the plunger (20) is pushed toward the proximal open end
of the hollow barrel (10) to engage with and retract the needle
hub (50). The connector (40) will rotate to a suitable location
and let the multiple limit stubs (41) of the connector (40) respectively
move along the corresponding curved limit channel (510) and the
first inclined side wall such that each limit stub (41) is mounted
into the corresponding notch (511). Thus, the plunger (20) and the
needle hub (50) are connected together. Pulling back the plunger
(20) into the hollow barrel (10) will let each limit stub (41) wedge
with the second inclined side wall of the notch (511) and stably
connect the plunger (20) and the needle hub (50). Continuously pulling
the plunger (20) will retract the needle hub (50) into the hollow
barrel (10).
With further reference to FIG. 5 pulling the plunger (20) toward
the distal open end of the hollow barrel (10) will pull the needle
hub (50) back into the hollow barrel (10). Since the radius of the
connecting chamber (512) in the needle hub (50) is larger than that
of the connector (40), the needle (52) will incline by gravity and
use the limit stub (41) as a fulcrum. The needle hub (50) cannot
be pushed out from proximal open end of the hollow barrel (10).
After the V-shaped groove (210) of the plunger (20) exits the hollow
barrel (10), the V-shaped groove (210) of the plunger (20) permits
the protruding portion of the plunger (20) to be snapped off whereby
the needle hub (50) is retained inside the hollow barrel (10).
In the second embodiment of the safety syringe, with reference
to FIG. 6 the connector (40') will rotate to a suitable location
and let the multiple limit stubs (41) of the connecting chamber
(512') in the needle hub (50') respectively move along the corresponding
curved limit channel (44) and be mounted into the corresponding
notch (45). The multiple limit stubs (41) will respectively wedge
to the corresponding second inclined side wall of the notch (45).
Thus, the plunger (20) and the needle hub (50') are connected together
stably.
The safety syringe in accordance with the present invention can
let the plunger (20) connect with the needle hub (5050') stably.
After the safety syringe has been used to treat a patient, the plunger
(20) can connect with the needle hub (5050') to let the needle
hub (5050') retract back in the hollow barrel (10).
Although the invention has been explained in relation to its preferred
embodiment, many other possible modifications and variations can
be made without departing from the spirit and scope of the invention
as hereinafter claimed is to be understood. |