Patent ID: 9662453
Date: 2017-05-30
CPC Classifications: A61M,F04B

Claim:
1. A dosing unit for an infusion pump device, the dosing unit comprising a piston pump with a pump cylinder, a plunger arranged within the pump cylinder, and a plunger driving part provided for transmitting rotational torque to the plunger without itself being linearly displaced, the cylinder, the plunger and the plunger driving part being coaxially arranged along a longitudinal axis and rotatable around said axis in regard to static parts of the dosing unit; wherein the plunger has a plunger shaft with a plunger thread and the cylinder has a threaded sleeve part with a cylinder thread; wherein one of plunger thread or cylinder thread is an outer thread and the other one is an inner thread, the inner thread and outer thread engaging with each other in such a way that a rotational movement of the plunger around the longitudinal axis results in an additional linear displacement of the plunger along said longitudinal axis; wherein the plunger driving part has a driving rod that is arranged in a longitudinal bore of the plunger shaft, the driving rod being linearly displaceable within the longitudinal bore along the longitudinal axis, and being rotationally engaged with the plunger shaft; the dosing unit further comprising one or more first coupling parts mounted to or being integral with the cylinder, and one or more second coupling parts mounted to or being integral with the plunger driving part and/or the plunger; wherein the first and second coupling parts interact in such a way that a. the first and second coupling parts are bidirectionally switchable between a first state and a second state, by reversing the rotation direction of the plunger driving part; b. the first and second coupling parts are unidirectionally switchable from the first state to the second state, by mechanically blocking cylinder rotation or actuating the first coupling part; and c. the cylinder is rotationally coupled to the plunger driving part in the first state of the first and second coupling parts; and not rotationally coupled in the second state; the first and second coupling parts interacting in such a way that the cylinder is rotationally coupled to the plunger on at least one linear position of the plunger in regard to the cylinder and is not rotationally coupled to the plunger on the other positions; and wherein the one or more first coupling part is mounted to or is integral with the cylinder, and the one or more second coupling part is mounted to or is integral with the plunger driving part; wherein the first and/or the second coupling part comprise one or more bistable elements that are configured to be in a first configuration where the one or more bistable elements rotationally couple the first and second coupling parts by static friction or positive locking when the plunger driving part rotates clockwise, and do not rotationally couple the first and second coupling parts when the plunger driving part rotates counter-clockwise; and in a second configuration where the bistable elements rotationally couple the first and second coupling parts by static friction or positive locking when the plunger driving part rotates counter-clockwise, and do not rotationally couple the first and second coupling parts when the plunger driving part rotates clockwise.