| 摘要 |
When a trigger of an injection device is released, a main spring ( 4 ) expands, driving a member ( 7 ) forwards. This compresses a weak spring ( 11 ), but a spring ( 5 ) is stiff enough to remain expanded. A syringe ( 2 ) is thus thrust forwards via a collar ( 9 ), so that a needle ( 3 ) projects from a barrel ( 1 ). The spring ( 4 ) continues to expand after the syringe has reached its forward position, with the spring ( 11 ) fully compressed, so that the stem ( 8 ) of the member ( 7 ) acts on a piston ( 14 ) within the syringe ( 2 ), to expel the dose while the spring ( 5 ) is caused to be compressed. The spring ( 5 ) ensures that the syringe is retained in its forward position during this phase.
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