Injection device for delivering a predefined plurality of predetermined dose volumes
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Publication Number
US-12558493-B2
Publication Date
2026-02-24
Expiration Date
Abstract
The invention relates to a spring driven multi-use fixed dose injection device with an End-of-Content (EoC) mechanism. A housing structure contains a volume of a liquid drug which is expelled in a predefined number of substantially equally sized dose volumes. Each dose volume is expelled automatically with the assistance of a spring which is loaded with a force sufficient to expel the full number of the predefined plurality of predetermined and equally sized dose volumes. Each dose volume is prepared and released by moving a drive element a predetermined axial distance in the proximal direction away from an initial position, followed by a rotation of the drive element by the force of the spring back to the initial position during which rotation the drive element rotates the piston rod to move helically. The End-of-Content mechanism determines how many times the drive element can be moved proximally and comprises a longitudinal track structure associated with the piston rod which has a free length defined by a proximal stop associated with the piston rod which stop prevents the drive element from moving an additional predetermined axial distance in the proximal direction required to prepare a subsequent predetermined dose volume after the predefined plurality of predetermined and equally sized dose volumes have been selected.
Core Innovation
The invention relates to a spring driven injection device for ejecting a predefined plurality of predetermined and substantially equally sized dose volumes. A housing structure contains a volume of a liquid drug ejectable by moving a piston rod in a distal direction. The piston rod is provided with an outer thread and a longitudinal track-structure in which the outer thread engages an inner thread associated with the housing structure such that the piston rod is moved helically when rotated relative to the housing structure.
A drive element engages the longitudinal track-structure of the piston rod so that rotation of the drive element is transferred to a rotation of the piston rod. A spring encompassed between the housing structure and the drive element is loaded with a force sufficient to eject the predefined plurality of predetermined and substantially equally sized dose volumes. Each dose volume is released by moving the drive element a predetermined axial distance (dl) in the proximal direction away from an initial position followed by a rotation of the drive element back to the initial position by the force of the spring, during which rotation the drive element rotates the piston rod to move helically.
The longitudinal track-structure provided in the piston rod has a free length (L) defined by a proximal stop associated with the piston rod, which prevents the drive element from moving an additional predetermined axial distance (dl) in the proximal direction required to prepare a subsequent predetermined dose volume once the predefined plurality of predetermined and substantially equally sized dose volumes have been selected. The disclosure further includes a telescopically movable needle shield arrangement and associated mechanical features for controlling movement of the drive element in translation and rotation.
Claims Coverage
The independent claims are clm-00001 and clm-00016. Across these two independent claims, the coverage centers on spring driven ejection of a predefined plurality of substantially equally sized dose volumes, helical piston-rod movement via thread engagement and drive-element rotation, and an End-of-Content stopping function that prevents further proximal translation once a remaining free length (L) becomes smaller than dl.
Spring driven injection device for predefined equal dose volumes
A spring encompassed between a housing structure and a drive element is loaded with a force sufficient to eject a predefined plurality of predetermined and substantially equally sized dose volumes, where each dose volume is released by moving the drive element a predetermined axial distance (dl) in the proximal direction away from an initial position followed by a rotation of the drive element by the force of the spring back to the initial position, and wherein during the rotation the drive element rotates the piston rod to move helically.
Helical piston rod drive via outer thread and longitudinal track-structure
A piston rod is provided with an outer thread and a longitudinal track-structure where the outer thread engages an inner thread associated with the housing structure such that the piston rod is moved helically when rotated relatively to the housing structure, and a drive element engaging the longitudinal track-structure of the piston rod such that rotation of the drive element is transferred to a rotation of the piston rod.
End-of-Content free length stop using proximal stop preventing additional dl
The longitudinal track structure provided in the piston rod has a free length (L) defined by a proximal stop associated with the piston rod which prevents the drive element from moving an additional predetermined axial distance (dl) in the proximal direction required to prepare a subsequent predetermined dose volume after the predefined plurality of predetermined and substantially equally sized dose volumes have been selected.
Method sequencing with needle shield translation, spring release rotation, and free-length stopping
The method comprises pushing a telescopically movable needle shield against a surface for thereby moving the drive element translationally a predetermined axial distance (dl), rotating the drive element a specific angle by releasing the force stored in the spring, transferring rotation from the drive element to a rotation of the piston rod for ejecting the predetermined dose volume, providing a specific free length (L) of the longitudinal track-structure between the engagement of the drive element with the piston rod and a predefined stop associated with the piston rod, and preventing further translational movement of the drive element when the remaining part of the free length (L) is smaller than the predetermined axial distance (dl).
The independent claims cover a spring driven injection/ejection mechanism that converts drive element translation by an axial distance (dl) and spring-driven return rotation into helical piston-rod motion through thread engagement, and that uses a defined free length (L) with a proximal stop or predefined stop to prevent further dl translation once the predefined plurality of substantially equally sized dose volumes has been selected.
Stated Advantages
Documented Applications
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