Injection device with holding means to prevent unintentional movements of piston rod

摘要

The invention relates to a injection device, comprising a housing being adapted to receive in its proximal housing portion a container with an injection fluid and to receive in its distal housing portion a dose setting and injection mechanism, wherein the mechanism includes a piston rod being axially displaceable with respect to the housing for dispensing injection fluid from the container, wherein the piston rod has an outer thread and is arranged torque proof with respect to the housing, dose setting means comprising a threaded element, which threaded element has an inner thread being in engagement with the outer thread of the piston rod, is designed so that its axial position relative to the housing is changeable and is rotatable relative to the piston rod and relative to the housing during setting of an injection dose, wherein the dose setting means are designed such that the threaded element is held in torque proof manner relative to the piston rod and to the housing during the injection of the beforehand set injection dose in such a manner that the threaded element and the piston rod are axially displaceable together with respect to the housing, wherein the mechanism further comprises holding means being in contact with the piston rod and being designed such that the axial displacement of the piston rod can be substantially immobilized during use of the device except for the dispensing of the injection dose. It is proposed according to the invention that the holding means are axially fixed with respect to the housing.

主权项

1. An Injection device comprising:
a housing having a proximal portion and a distal portion configured to receive in the proximal housing portion a container containing an injection fluid and to receive in the distal housing portion a dose setting and injection mechanism, wherein the dose setting and injection mechanism includes, a piston rod being axially displaceable in a proximal direction with respect to the housing for dispensing a dose of the injection fluid from the container, wherein the piston rod has an outer thread and is rotationally fixed relative to the housing during dispensing of a dose and where the piston rod is rotatable with respect to the housing during axial return of the piston rod in a distal direction during resetting of the piston rod from a proximal end position to a distal start position; a threaded element having an inner thread in threaded engagement with the outer thread of the piston rod, where the threaded element is configured such that its axial position on the piston rod is changeable during setting of a dose, wherein the threaded element is rotatable relative to the piston rod and relative to the housing during setting of a dose, wherein the threaded element is rotatably fixed relative to the piston rod and to the housing during injection of a dose, wherein the threaded element and the piston rod are axially fixed to each other and displaceable together with respect to the housing during injection of a set dose; and a guiding element that engages the piston rod to prevent rotation of piston rod during both dose setting and dose injection, where the guiding element is axially and rotationally fixed relative to the housing during both dose setting and dose injection.