Pen-type injector

Inventors

Roedle, Tilman • Kistler, Tobias • Kühnle, Sarah • Limbeck, Roland

Assignees

Vetter Pharma Fertigung GmbH • Vetter Pharma Fertigung GmbH and Co KG

Abstract

A pen includes a carpule having a longitudinal axis, a first end with a dispensing opening closable by a closure part, a second end via which at least one stopper can be inserted in the direction of the longitudinal axis, and an interior that is tightly closed by the closure part and the at least one stopper. A pen housing has a central axis, receives the carpule, and has a piston rod that interacts with the at least one stopper and a drive for moving the at least one stopper within the interior of the carpule, wherein the second end of the carpule can be inserted into the housing. The drive element moves the carpule into the housing in the direction of the longitudinal axis, which is arranged coaxially to the central axis of the housing, when the drive is activated; and in the process the piston rod is held in a fixed position with respect to the longitudinal direction of the housing such that the piston rod, which is engaged in the second end of the carpule, moves the at least one stopper within the interior of the carpule in the direction of the first end of the carpule.

Core Innovation

The invention relates to a pen-type injector having a carpule with a longitudinal axis, a dispensing opening at a first end closeable by a closure part, and a second end receiving at least one stopper, with the interior tightly closed by the closure part and the at least one stopper. A housing has a central axis coaxial to the carpule longitudinal axis and receives the carpule, where the housing includes a piston rod and a drive. When the drive is activated, the second end of the carpule inserted into the housing is moved into the housing in the direction of the longitudinal axis of the carpule, thereby moving the stopper within the carpule toward the dispensing end.

A defining feature is the longitudinally fixed piston rod position in the direction of the housing central axis, while the drive moves the carpule into the housing. The drive includes a drive element that interacts with the carpule, including coupling arrangements via friction fit and/or positive fit, and the use of a threaded-sleeve drive in which a threaded sleeve is held in a longitudinally fixed position in the housing while the sleeve is rotated. Rotation of the threaded sleeve draws the carpule into the drive element to move the at least one stopper through the carpule interior.

The invention further defines mechanical behavior and control for accurate actuation, including rotation decoupling means so that unwanted stopper rotation is prevented. Sensors are provided to detect the position of the stopper relative to the piston rod and/or drive current to establish a defined initial position for accurate first-dose volume. The document illustrates functional positions with a first functional position and a second functional position as the cartridge shortens with each application, including configurations such as a dual chamber carpule with first stopper and second stopper and possible bypass, overpressure, and reconstitution aspects.

Claims Coverage

The document provides three independent claims. Across the independent claims, the coverage centers on a threaded-sleeve drive that draws the carpule into the housing to drive a stopper, while the piston rod is axially fixed and interacts with the stopper for movement toward the dispensing opening.

Across the independent claims, the inventive core is the combination of a threaded sleeve drive with interior and exterior thread engagement that draws the carpule into the drive element during rotation, a piston rod that is axially fixed in the housing direction while interacting with the stopper to move it toward the dispensing opening, and defined coupling and kinematic constraints including rotation-fast arrangement and synchronous rotation relationships between the drive element and piston rod.

Stated Advantages

Documented Applications