Mechanism for a drug delivery device and drug delivery device comprising the mechanism
The mechanism includes a body, a drive member movable in the body, a main spring that is loaded when a dose is set and is released for moving the drive member during a delivery of a dose, and a movable trigger inhibiting a movement of the drive member, a movement of the trigger releasing the main spring and the drive member. The trigger is moved from a start position to an end position relative to the body during a setting of a dose, the end position having a distance from the start position that increases as the dose set increases.
1. A mechanism for a drug delivery device, comprising:
a body;
a drive member movable in the body;
a main spring, wherein the mechanism is configured such that the main spring is loaded when a dose is set and the main spring is released to move the drive member during a delivery of the dose; and
a movable trigger configured to inhibit a movement of the drive member, wherein a movement of the trigger relative to the body releases the main spring and the drive member, and
wherein the trigger is further configured to move from a start position to an end position relative to the body during the setting of the dose, the end position having a distance from the start position that increases as the dose set increases, and the distance of the end position from the start position depending on an amount of the dose set, wherein the trigger is axially moveable with respect to the body, and wherein the trigger is rotationally locked to the body during the setting of the dose and during the delivery of the dose.
2. The mechanism according to claim 1 , wherein the trigger is moved from the end position towards the start position for the delivery of the dose.
3. The mechanism according to claim 1 , wherein the distance covered by the trigger during the setting of the dose is proportional to an amount of the dose delivered.
4. The mechanism according to claim 1 , further comprising:
a locking feature releasably locking the drive member to the trigger during the setting of the dose and releasing the drive member from the trigger during drug delivery.
5. The mechanism according to claim 4 , wherein the locking feature rotationally locks the drive member to the trigger by a rotational lock.
6. The mechanism according to claim 5 , wherein the locking feature comprises:
a spline of the trigger, and
a spline of the drive member, wherein the spline of the trigger and the spline of the drive member rotationally lock the drive member to the trigger in such a way that the rotational lock is released by a movement of the trigger from the end position towards the start position.
7. The mechanism according to claim 4 , further comprising:
a trigger spring acting on the trigger, the trigger spring tending to keep the drive member locked to the trigger.
8. The mechanism according to claim 1 , further comprising:
an indicator member, the drive member being unidirectionally rotationally coupled to the indicator member.
9. The mechanism according to claim 8 , further comprising:
a resilient element acting between the body and the drive member, the resilient element being arranged to keep the drive member coupled to the indicator member.
10. The mechanism according to claim 8 , further comprising:
a spring cap axially movable and rotationally locked to the body, the main spring being fastened to the indicator member and to the spring cap in such a manner that the main spring is loaded by a rotation of the indicator member relative to the spring cap.
11. A drug delivery device comprising a mechanism according to claim 1 .
12. The drug delivery device of claim 11 , wherein the drug delivery device is a pen-type device.
13. The drug delivery device of claim 11 , wherein the drug delivery device is a disposable device.
14. The mechanism according to claim 1 , further comprising:
a dial rotatably mounted to a proximal end of the body, wherein rotation of the dial in a first direction increases a dialed dose, and wherein rotation of the dial in a second direction, opposite the first direction, decreases the dialed dose or cancels the dose completely.
15. The mechanism according to claim 1 , wherein the trigger provides an optical or tactile feedback of the amount of the dose set.
16. The mechanism according to claim 1 , wherein a display window is formed in a portion of the body, the display window adapted to display the dose set.
17. The mechanism according to claim 1 , further comprising a lead screw threadedly engaged with the body, wherein the lead screw comprises a proximal last-dose abutment at a proximal end of the lead screw, and wherein rotation of the drive member along a proximal direction is inhibited by the proximal last-dose abutment.
18. The mechanism according to claim 1 , further comprising a lead screw threadedly engaged with the body, wherein the main spring is disposed around a portion of the lead screw.
19. The mechanism according to claim 1 , wherein a longitudinal axis extending between the start position and the end position is parallel to a longitudinal axis of the body.