Injection device with reduced amount of parts

An injection device for dispensing a liquid drug from a syringe through an injection needle, the injection device comprising a pre-assembled drive unit assembled with a pre-assembled syringe unit, wherein the pre-assembled syringe unit comprises:

• a housing defining a longitudinal axis;
• and
• a needle cover movable along the longitudinal axis relative to the housing between a needle covering position and a retracted position in which the needle protrudes from the needle cover, and
• wherein the pre-assembled drive unit comprises:
• a plunger rod;
• a spring member adapted bias the plunger rod in a dispensing direction;
• a supporting member adapted to support or guide the spring member or the plunger rod;
• and
• a first and a second retaining element, wherein each retaining element is configured to be arranged in a holding position in which the first or second retaining element holds the plunger rod biased in place relative to the supporting member and in a release position in which the first or second retaining element does not hold the biased plunger rod in place,
• wherein prior to assembly of the injection device the pre-assembled drive unit and the pre-assembled syringe unit are separated from each other, and the first retaining element is in the holding position and the biased plunger rod is held in place by the first retaining element,
• wherein during connection of the syringe unit to the drive unit a movement of the housing and of the needle cover relative to the supporting member causes the first retaining element to move out of the holding position,
• wherein, when the injection device is completely assembled, the drive unit is connected to the syringe unit and the needle cover is operatively coupled to the second retaining element, the first retaining element is in the release position, and the second retaining element is in the holding position such that the biased plunger rod is exclusively held in place by the second retaining element when the needle cover is in the covering position.

An injection device for dispensing a liquid drug from a syringe through an injection needle, the injection device comprising a pre-assembled drive unit assembled with a pre-assembled syringe unit, wherein the pre-assembled syringe unit comprises:

• a housing defining a longitudinal axis;
• and
• a needle cover movable along the longitudinal axis relative to the housing,
• wherein the pre-assembled drive unit comprises:
• a plunger rod;
• a spring member adapted to bias the plunger rod in a dispensing direction;
• a supporting member;
• and
• a first and a second retaining element, wherein each retaining element is configured to be arranged in a holding position in which the first or second retaining element holds the plunger rod biased in place relative to the supporting member and in a release position in which the first or second retaining element does not hold the biased plunger rod in place,
• wherein prior to assembly of the injection device, the pre-assembled drive unit and the pre-assembled syringe unit are separated from each other, and the first retaining element is in the holding position and the biased plunger rod is exclusively held in place by the first retaining element,
• wherein, when the injection device is completely assembled, the drive unit is connected to the syringe unit and the needle cover is operatively coupled to the second retaining element, the first retaining element is in the release position, and the second retaining element is in the holding position such that the biased plunger rod is exclusively held in place by the second retaining element when the needle cover is in a covering position.