Injection pen
An injection pen comprises a starting mechanism ( 1 ) and a driving mechanism ( 2 ). A needle pin ( 40 ) of the starting mechanism ( 1 ) fitted to a connecting rod ( 30 ) and a front spring ( 60 ) is disposed in a front housing ( 10 ) and an inner casing ( 20 ) therein. A front cover ( 50 ) is disposed at the front end of the front housing ( 10 ) and covers the needle pin ( 40 ). A rear housing ( 70 ) of the driving mechanism ( 2 ) and a driving casing ( 80 ) therein are connected to the front housing ( 10 ). A trigger tube ( 90 ) and a key panel (A 0 ) are mounted in the driving casing ( 80 ). A push rod (A 1 ) fitted to a rear spring (A 2 ) is mounted in the trigger tube ( 90 ). An elastic baffle ( 83 ) of the driving casing ( 80 ) fastens the driving casing ( 80 ) and the push Rod (A 1 ) and locks the rear spring (A 2 ). An injection needle group ( 3 ) can be mounted between the starting mechanism ( 1 ) and the driving mechanism ( 2 ). When the front cover ( 50 ) is removed, the needle pin ( 40 ) can be pressed and inwards retreated into the front housing ( 10 ) to make a needle ( 3 A) to be exposed, and the inwards retreated needle pin ( 40 ) drives the connecting rod ( 30 ) to push away the elastic baffle ( 83 ) of the driving casing ( 80 ) to perform unlocking. The released rear spring (A 2 ) pushes the push rod (A 1 ) to make an injection needle group ( 3 ) to transfer a drug. After the injection, the needle pin ( 40 ) is reset under the push of the front spring ( 60 ), and the needle pin ( 40 ) is fastened in the inner casing ( 20 ) when a key panel (A 0 ) is pulled out by means of the connecting rod ( 30 ), so that the needle pin ( 40 ) cannot be pressed to inwards retreat, and accordingly, a used syringe needle ( 3 A) is protected, so as to prevent users from being hurt by the needle by accident.
1. An injection pen comprising an actuating mechanism and a driving mechanism connected with the actuating mechanism, wherein
the actuating mechanism comprises
a front casing having an assembling space defined axially through the front casing;
an inner casing mounted in the assembling space in the front casing and having a front segment, a rear segment, and a baffle disposed between the front segment and the rear segment and having an inner hole, two first through holes, and two second through holes, wherein the two first through holes and the two second through holes are located around the inner hole;
a connection rod mounted moveably in the inner casing and comprising
a rod body having an axial hole defined axially through the rod body;
two hooks formed on a rear end of the rod body at positions corresponding respectively to the first through holes of the inner casing; and
two actuating portions formed on the rear end of the rod body and extending respectively through the second through holes of the inner casing;
a needle hub mounted moveably in the front casing, connected with the connection rod, and having a tubular body and an outer sleeve formed around a front end of the tubular body, being located in front of a front end of the front casing, and being retractable into the front casing;
a front cap mounted detachably around the outer sleeve of the needle hub and abutting the front end of the front casing; and
a front spring mounted in the front segment of the inner casing, held between the actuating portions of the connection rod, and having two ends abutting the connection rod and the inner casing, respectively; and
the driving mechanism comprises
a rear casing being hollow, mounted on a rear end of the front casing;
a driving casing mounted securely in the rear casing, extending into the front casing, and having a receiving space formed axially through the driving casing and two resilient engaging tabs;
a driving tube mounted in the driving casing and having
a tube hole formed in a rear end of the driving tube;
an end board formed on a front end of the driving tube and having a through bore defined through the end board and communicating with the tube hole; and
two side holes defined radially in an outer surface of the driving tube, communicating with the tube hole, and selectively engaged with the resilient engaging tabs of the driving casing, wherein the actuating portions of the connection rod selectively extend into the driving tube to disengage the resilient engaging tabs from the side holes;
two engaging members mounted in the driving casing and mounted around the front end of the driving tube, and each engaging member having
two engaging hooks formed on a front end of the engaging member, selectively extending respectively through the first through holes in the inner casing and selectively engaged with the hooks on the connection rod; and
two resilient locking portions formed on a rear end of the engaging member and engaged with the driving casing, wherein the engaging members are selectively pushed by the connection rod to move and to engage with the first through holes in the inner casing;
a pushing rod mounted in the driving tube and having a first rod segment mounted through the through bore in the end board of the driving tube, a second rod segment, and a middle board formed between the first rod segment and the second rod segment and abutting the two resilient engaging tabs that are engaged with the side holes in the driving tube; and
a rear spring mounted in the driving tube, mounted around the second rod segment of the pushing rod, and having two ends abutting the middle board and the rear casing, respectively.
2. The injection pen as claimed in claim 1 , wherein
the driving casing further has
two engaging recesses defined in an inner surface of the driving casing and being diametrically opposite each other; and
two guiding recesses defined in the inner surface of the driving casing and being diametrically opposite each other;
the engaging recesses and the guiding recesses in the driving casing are arranged in an alternate manner;
the resilient engaging tabs of the driving casing correspond respectively to the guiding recesses in position;
the actuating portions of the connection rod are mounted respectively through the guiding recesses and selectively push the actuating portions, respectively, to swing outward; and
the resilient locking portions of each engaging member are engaged detachably with the engaging recesses in the driving casing.
3. The injection pen as claimed in claim 2 , wherein
the two first through holes and the two second through holes in the inner casing are arranged in an alternate manner;
the first through holes are diametrically opposite each other;
the second through holes are diametrically opposite each other;
the baffle of the inner casing has an inner tube formed on a front side of the baffle and extending into the front segment of the inner casing;
the inner hole in the baffle extends into the inner tube; and
the front spring is mounted around the inner tube.
4. The injection pen as claimed in claim 3 , wherein
the front casing has a window formed radially in an outer surface of a front segment of the front casing and communicating with the assembling space;
the front segment of the inner casing comprises two wings diametrically opposite each other and spaced at a spaced interval;
the interval between the wings is equal to a width of the window in the front casing; and
the connection rod has an elongated hole defined in the rod body of the connection rod and corresponding to the window in the front casing in position.
5. The injection pen as claimed in claim 4 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab;
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing;
the rod body of the connection rod further has two resilient tabs formed on an outer surface of the rod body and diametrically opposite each other; and
the tubular body of the needle hub further has two tab holes defined in the tubular body and engaged respectively with the resilient tabs on the rod body of the connection rod to connect the connection rod with the needle hub.
6. The injection pen as claimed in claim 3 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab; and
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing.
7. The injection pen as claimed in claim 3 , wherein
the front cap comprises
a cap body mounted around the outer sleeve of the needle hub and having a closed front end and an open rear end abutting the front end of the front casing; and
a connection tube formed in the cap body, extending out of the open rear end of the cap body, extending into the tubular body of the needle hub, and having a rear end provided with a hook and at least one slit defined in the rear end of the connection tube.
8. The injection pen as claimed in claim 2 , wherein
the front casing has a window formed radially in an outer surface of a front segment of the front casing and communicating with the assembling space;
the front segment of the inner casing comprises two wings diametrically opposite each other and spaced at a spaced interval;
the interval between the wings is equal to a width of the window in the front casing; and
the connection rod has an elongated hole defined in the rod body of the connection rod and corresponding to the window in the front casing in position.
9. The injection pen as claimed in claim 8 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab;
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing;
the rod body of the connection rod further has two resilient tabs formed on an outer surface of the rod body and diametrically opposite each other; and
the tubular body of the needle hub further has two tab holes defined in the tubular body and engaged respectively with the resilient tabs on the rod body of the connection rod to connect the connection rod with the needle hub.
10. The injection pen as claimed in claim 2 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab; and
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing.
11. The injection pen as claimed in claim 2 , wherein
the front cap comprises
a cap body mounted around the outer sleeve of the needle hub and having a closed front end and an open rear end abutting the front end of the front casing; and
a connection tube formed in the cap body, extending out of the open rear end of the cap body, extending into the tubular body of the needle hub, and having a rear end provided with a hook and at least one slit defined in the rear end of the connection tube.
12. The injection pen as claimed in claim 1 , wherein
the two first through holes and the two second through holes in the inner casing are arranged in an alternate manner;
the first through holes are diametrically opposite each other;
the second through holes are diametrically opposite each other;
the baffle of the inner casing has an inner tube formed on a front side of the baffle and extending into the front segment of the inner casing;
the inner hole in the baffle extends into the inner tube; and
the front spring is mounted around the inner tube.
13. The injection pen as claimed in claim 12 ,
wherein the front casing has a window formed radially in an outer surface of a front segment of the front casing and communicating with the assembling space;
the front segment of the inner casing comprises two wings diametrically opposite each other and spaced at a spaced interval;
the interval between the wings is equal to a width of the window in the front casing; and
the connection rod has an elongated hole defined in the rod body of the connection rod and corresponding to the window in the front casing in position.
14. The injection pen as claimed in claim 13 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab;
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing;
the rod body of the connection rod further has two resilient tabs formed on an outer surface of the rod body and diametrically opposite each other; and
the tubular body of the needle hub further has two tab holes defined in the tubular body and engaged respectively with the resilient tabs on the rod body of the connection rod to connect the connection rod with the needle hub.
15. The injection pen as claimed in claim 12 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab; and
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing.
16. The injection pen as claimed in claim 12 , wherein
the front cap comprises
a cap body mounted around the outer sleeve of the needle hub and having a closed front end and an open rear end abutting the front end of the front casing; and
a connection tube formed in the cap body, extending out of the open rear end of the cap body, extending into the tubular body of the needle hub, and having a rear end provided with a hook and at least one slit defined in the rear end of the connection tube.
17. The injection pen as claimed in claim 1 , wherein
the front casing has a window formed radially in an outer surface of a front segment of the front casing and communicating with the assembling space;
the front segment of the inner casing comprises two wings diametrically opposite each other and spaced at a spaced interval;
the interval between the wings is equal to a width of the window in the front casing; and
the connection rod has an elongated hole defined in the rod body of the connection rod and corresponding to the window in the front casing in position.
18. The injection pen as claimed in claim 17 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab;
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing;
the rod body of the connection rod further has two resilient tabs formed on an outer surface of the rod body and diametrically opposite each other; and
the tubular body of the needle hub further has two tab holes defined in the tubular body and engaged respectively with the resilient tabs on the rod body of the connection rod to connect the connection rod with the needle hub.
19. The injection pen as claimed in claim 1 , wherein
the front casing further has two engaging holes defined in a rear segment of the front casing;
the rear casing has two extension tabs formed on a front end of the rear casing and extending into the rear segment of the front casing;
each extension tab has an engaging protrusion selectively engaged with a respective one of the engaging holes in the front casing and a fixing hole defined in the extension tab; and
the driving casing has two fixing blocks formed on an outer surface of the driving casing and engaged respectively with the fixing hole in the rear casing to securely mount the driving casing in the rear casing.
20. The injection pen as claimed in claim 1 , wherein
the front cap comprises
a cap body mounted around the outer sleeve of the needle hub and having a closed front end and an open rear end abutting the front end of the front casing; and
a connection tube formed in the cap body, extending out of the open rear end of the cap body, extending into the tubular body of the needle hub, and having a rear end provided with a hook and at least one slit defined in the rear end of the connection tube.