Dosing system for an injection device

A dosing and dispensing mechanism for an injection device for dispensing a dose of a product by advancing a piston rod, the dosing and dispensing mechanism comprising:

• a housing having a longitudinal axis;
• a dosing sleeve at least partially arranged in the housing for dose setting and dose correcting;
• a housing insert axially and rotationally fixed relative to the housing and at least partially arranged within an interior of the dosing sleeve;
• and
• a coupling sleeve at least partially arranged within the housing for driving the piston rod,
• wherein for the dose setting and dose correcting, the dosing sleeve is rotatable relative to the coupling sleeve in a first direction and in an opposite, second direction, and for dispensing the dose, the dosing sleeve is coupleable to the coupling sleeve and rotatably fixed relative thereto, and
• wherein the coupling sleeve comprises an external surface with a locking element extending therefrom, the locking element defining an elastic radial arm configured to engage with a plurality of axial grooves on an external surface of the housing insert facing the external surface of the coupling sleeve such that the coupling sleeve and the elastic radial arm are rotatable relative to the housing insert in the first direction of rotation and are prevented from rotation the second direction of rotation by an engagement of the elastic radial arm within one of the plurality of axial grooves of the housing insert.

A dosing and dispensing mechanism for an injection device for dispensing a dose of a product by advancing a piston rod, the dosing and dispensing mechanism comprising:

• a housing having a longitudinal axis;
• a dosing sleeve at least partially arranged in the housing for dose setting and dose correcting;
• a housing insert axially and rotationally fixed relative to the housing and at least partially arranged within an interior of the dosing sleeve;
• and
• a coupling sleeve at least partially arranged within the housing for driving the piston rod,
• wherein for the dose setting and dose correcting, the dosing sleeve is rotatable relative to the coupling sleeve in a first direction and in an opposite, second direction, and for dose dispensing, the dosing sleeve is coupleable to the coupling sleeve and rotatably fixed relative thereto,
• wherein the coupling sleeve comprises an external surface with a locking element extending therefrom, the locking element defining an elastic radial arm configured to engage with a plurality of axial grooves on an external surface of the housing insert facing the external surface of the coupling sleeve such that the coupling sleeve and the elastic radial arm are rotatable relative to the housing insert in the first direction of rotation and are prevented from rotation in the second direction of rotation by an engagement of the elastic radial arm within one of the plurality of axial grooves of the housing insert, and
• wherein the coupling sleeve is rotationally fixed relative to and displaceably mounted on the piston rod such that rotation of the coupling sleeve during the dose dispensing causes the piston rod to rotate to thereby advance and dispense the dose.