Injection Device Having a Capability of Controlling Injection Dose

An injection device comprising:

• a dose controlling assembly comprising:
• an outer tube having
• an axial hole defined axially through the outer tube;
• and
• a spiral rib formed on an inner surface of the axial hole of the outer tube;
• a dose controlling tube mounted rotatably in the axial hole in the outer tube and comprising
• an axial hole defined axially through the dose controlling tube;
• a front segment having a spiral groove engaged with the spiral rib of the outer tube;
• a rear segment formed at a rear end of the dose controlling tube;
• and
• multiple engaging grooves defined longitudinally in an inner surface at a rear end of the axial hole of the dose controlling tube;
• a driving tube mounted in the axial hole in the dose controlling tube and having
• a front segment;
• a rear segment formed at a rear end of the driving tube;
• a first inner space defined in the front segment of the driving tube and having an opening at a front end of the driving tube;
• a second inner space defined in the rear segment of the driving tube and having an opening at the rear end of the driving tube;
• at least one notch defined radially in the rear segment of the driving tube and communicating with the second inner space, and each one of the at least one notch having an engaging tab formed in the notch and selectively engaged with the engaging grooves in the dose controlling tube;
• and
• a limiting portion formed on the front end of the driving tube;
• a connection tube mounted in the dose controlling tube and having
• a rear end connected with the front end of the driving tube;
• an axial hole defined axially through the connection tube;
• a connection segment provided with a thread and having a front end and a rear end;
• and
• an annular flange formed around the front end of the connection segment;
• a dose controlling collar mounted in the dose controlling tube, located in front of the driving tube, and having
• a threaded hole threaded with the thread on the connection segment of the connection tube;
• and
• a rear end provided with a spiral limiting portion selectively engaged with the limiting portion of the driving tube;
• an operation assembly mounted on a rear end of the dose controlling assembly and comprising
• an operation element mounted in the second inner space of the driving tube to push the engaging tab on the driving tube to engage with the engaging grooves in the dose controlling tube and having
• an insertion sheet extending outside the rear end of the driving tube, selectively extending into the rear end of the dose controlling tube, and having a front end and a rear end;
• and
• an insertion head formed on the rear end of the insertion sheet;
• a compression spring mounted around the insertion sheet of the operation element and having two ends respectively abutting the rear end of the driving tube and the insertion head;
• and
• a pushing element mounted around the insertion head of the operation element;
• an injection pushing assembly mounted on a front end of the dose controlling assembly and comprising
• an axial tube having
• an axial hole defined axially through the axial tube;
• a tube body mounted in the connection tube, being axially moveable relative to the connection tube, and having a front end;
• and
• a front segment formed on the front end of the tube body and located in front of the connection tube and the dose controlling tube;
• a pushing rod mounted in the axial hole in the axial tube, being axially moveable relative to and driven to rotate with the axial tube, and having a front end and a pushing thread formed around the pushing rod;
• and
• a pushing block mounted on the front end of the pushing rod;
• and
• a clutch assembly mounted in a front segment of the outer tube, connected with the injection pushing assembly, and comprising
• a front casing mounted securely in a front end of the outer tube and having
• a rear board having a threaded hole defined through the rear board and threaded with the pushing thread on the pushing rod;
• and
• a first ratchet portion formed on a rear side of the rear board and around the threaded hole of the rear board and having multiple unidirectional ratchet teeth arranged annularly;
• a rear casing mounted securely in the front end of the outer tube and connected with a rear end of the front casing;
• a clutch element mounted moveably in the rear casing, being driven to rotate with the axial tube, and having
• a central hole formed axially through the clutch element and disposed moveably around the front segment of the axial tube;
• and
• a second ratchet portion formed on a front side of the clutch element and having multiple unidirectional ratchet teeth arranged annularly and selectively engaged with the multiple unidirectional ratchet teeth of the first ratchet portion on the front casing;
• and
• a pushing spring mounted in the rear casing, mounted around the front segment of the axial tube, and having two ends respectively abutting the clutch element and the axial tube.