Reusable torsion spring driven injection device
Inventors
Jakobsen, Nikolaj Eusebius • Kiilerich, Ebbe • Higson, Lee
Assignees
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Publication Number
US-12485229-B2
Publication Date
2025-12-02
Expiration Date
Abstract
The invention relates to an injection device wherein the drive element transferring rotation to the piston rod is divided into two elements which are able to move axially in relation to each other such that the drive mechanism can be released to allow the user to reset the piston rod and change the cartridge.
Core Innovation
The disclosed invention relates to a reusable torsion spring driven injection device for expelling doses of a liquid drug from a loaded cartridge. It includes a piston rod with an outer surface having an outer thread extending helically in a longitudinal direction, and a longitudinal extending engagement surface such that the outer surface has a non-circular cross section. A housing structure comprises a base part with a torsion spring driven expelling mechanism for driving the piston rod axially, and a removable cartridge holder part holding the cartridge and being releasable connectable to the base part.
The torsion spring driven expelling mechanism comprises a rotatable piston rod driver engaging the engagement surface of the piston rod so that rotation of the driver is transmitted to similar rotation of the piston rod. An internal thread in the housing structure engages the outer thread so the piston rod moves helically when rotated. During dose expelling, a strained torsion spring holds torque for rotating the rotatable piston rod driver.
The rotatable piston rod driver comprises an outer element and an inner element releasable coupled together. The outer element is maintained stationary during dose setting and rotated by the torsion spring torque during dose expelling, while the inner element is axially movable relative to the outer element between a first uncoupled position in which the inner element is rotatable independently and a second coupled position in which the inner element follows rotation of the outer element. A movable element operable connected to the inner element is axially movable to transfer the inner element from the uncoupled position to the coupled position.
Claims Coverage
The independent claim set comprises 1 independent claim. The claim defines the core device architecture and a torsion spring expelling mechanism with an uncoupled-to-coupled rotatable piston rod driver, and requires a movable element axially movable to couple an inner element to an outer element.
Non-circular piston rod with helical outer thread and longitudinal engagement surface
A piston rod having an outer surface with an outer thread extending helically in a longitudinal direction and provided with a longitudinal extending engagement surface such that the outer surface of the piston rod has a non-circular cross section.
Rotatable piston rod driver transmitting rotation via engagement surface
A rotatable piston rod driver engaging the engagement surface of the piston rod such that rotation of the rotatable piston rod driver is transmitted to a similar rotation of the piston rod.
Helical piston rod advance using internal thread engaging outer thread
An internal thread associated with the housing structure and engaging the outer thread on the piston rod such that the piston rod is moved helically when rotated.
Torsion spring torque rotating the rotatable piston rod driver during dose expelling
A strained torsion spring holding a torque for rotating the rotatable piston rod driver during dose expelling.
Outer and inner elements releasably coupled in the rotatable piston rod driver
The rotatable piston rod driver comprises an outer element and an inner element releasable coupled together, where the outer element is maintained stationary during dose setting and rotated by the torque of the torsion spring during dose expelling.
Axially movable uncoupled and coupled positions for inner element
The inner element is axially movable relative to the outer element between a first uncoupled position and a second coupled position, wherein the first uncoupled position is rotatable independently of the outer element and the second coupled position couples the inner element to follow rotation of the outer element.
Axially movable movable element to move inner element into coupled position
A movable element operable connected to the inner element is axially movable to move the inner element axially from the first uncoupled position to the second coupled position.
The claim coverage centers on a reusable torsion spring driven injection device in which a rotatable piston rod driver transmits torsion spring torque into a piston rod moved helically via an internal thread, while an inner driver element is axially movable to change from an uncoupled independently rotatable state to a coupled state that follows the stationary-during-setting outer element.
Stated Advantages
Documented Applications
Expelling doses of a liquid drug from a loaded cartridge using a reusable torsion spring driven injection device.
Changing cartridges by releasable connectable cartridge holder part and performing an uncoupled-to-coupled driver coupling for resetting during cartridge change, as described in example release mechanisms.
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