초록 ▼

A dose setting device for a delivery system has a piston rod ( 6, 9 ) which successively presses a piston ( 2 ) into a cylinder ampoule ( 1 ). Doses are set by rotating a second part ( 9 ) of the piston rod ( 6, 9 ) in relation to a first part ( 6 ). The two parts are connected by mating threads so

A dose setting device for a delivery system has a piston rod ( 6, 9 ) which successively presses a piston ( 2 ) into a cylinder ampoule ( 1 ). Doses are set by rotating a second part ( 9 ) of the piston rod ( 6, 9 ) in relation to a first part ( 6 ). The two parts are connected by mating threads so that the total length of the piston rod ( 6, 9 ) is increased proportional to the angle of rotation, and a point ( 18 ) on the second part is moved away from a stop position fixed in relation to a housing ( 5 ) The set dose is delivered when the point ( 18 ) is moved back to the stop position. The first part ( 6 ) can be axially displaced but not rotated in the housing ( 5 ), and the second part ( 9 ) can both rotate and be axially displaced. The first part ( 6 ) is maintained in abutment with the piston ( 2 ) and the second part ( 9 ) is coupled to be rotated by a dose setting wheel ( 20 ). An injection push button ( 10 ) is movable between a projecting position and a pressed home position and has elements ( 13 ) acting on the second part ( 9 ) to press this part to its stop position.

대표청구항 ▼

1. A drug delivery system comprising:a housing;an ampoule accommodated in the housing and having an interior with first and second ends, a piston closing the first end, which piston can be pressed into the ampoule, a membrane closing the second end, and a medicine disposed in the ampoule interior be

1. A drug delivery system comprising:a housing;an ampoule accommodated in the housing and having an interior with first and second ends, a piston closing the first end, which piston can be pressed into the ampoule, a membrane closing the second end, and a medicine disposed in the ampoule interior between the piston and the membrane;a piston rod mounted in the housing and comprising first and second parts, wherein the first part is flexible and has a first end which is maintained in contact with the piston and a second end which is deflected 180 degrees relative to the first end and includes a thread, wherein the second part includes a thread which mates with the thread on the first part so that rotation of the second part relative to the first part changes the total length of the piston rod, wherein the housing includes a guide allowing the first part to move axially but not rotationally, wherein the second part is mounted in the housing for both axial and rotational movement, wherein rotation of the second part relative to the first part causes the second part to move in a first direction away from an initial position to set the amount of a dose, and wherein the second part can be moved in said first direction away from said initial position no more than a maximum distance representing a maximum dose; andan injection mechanism comprising a push button which can be moved between a projecting position and a pressed home position, wherein the injection mechanism includes a piston rod moving element that, responsive to moving the push button from its projecting position to its pressed home position, moves in a direction opposite to said first direction from a first end position to a second end position and engages the second part during at least part of such movement to move the second part back to said initial position upon reaching said second end position, and wherein the distance between the first and second end positions is at least as great as said maximum distance, whereby the distance of movement of the push button is independent of the size of the set dose. 2. A drug delivery system according to claim 1, further comprising a dose setting drum having teeth and supported by the housing, wherein the second part of the piston rod includes a gear engaging the teeth on the dose setting drum, and a mechanism for selectively locking the dose setting drum against unintentional rotation relative to the housing. 3. A drug delivery system according to claim 1, wherein the piston rod moving element comprises a lifter, and wherein the second part of the piston rod has an end point which abuts said lifter when the lifter is in its second end position and during at least part of its movement from the first end position to the second end position. 4. A drug delivery system according to claim 3, wherein the lifter and push button are coupled by gearing to move in opposite directions relative to one another. 5. A drug delivery device according to claim 3, wherein the threads on the first and second parts of the piston rod are not self-locking, and further comprising a drawer element for holding the ampoule and which is moveable between open and closed positions, a piston rod withdrawal element coupled between the drawer element and the piston rod such that, when the drawer element is opened, the piston rod withdrawal element moves the first part of the piston rod towards the lifter, and wherein the end point of the second part abuts the lifter and forms a pivot about which the second part can rotate to allow the second end of the first part to move towards the lifter. 6. A drug delivery system according to claim 5, further comprising a dose setting drum having teeth and supported by the housing, wherein the second part of the piston rod includes a gear engaging the teeth on the dose setting drum, and a mechanism for selectively locking the dose setting drum against unintentional rotation relative to the housing. 7. A drug delivery device according to claim 6, wherein the piston rod withdrawal element is coupled to the piston rod such that, when the drawer is opened, the piston rod withdrawal element unlocks the dose setting drum for rotation. 8. A drug delivery device according to claim 1, wherein the thread on the second part of the piston rod is in the form of a threaded spindle, wherein the thread on the first part is a nut member at the second end of the first part, wherein the nut member is moveable between first and second positions for engaging the spindle and disengaging from the spindle, respectively, wherein the threads on the first and second part of the piston rod are self locking when the nut is in its first position, and further comprising a drawer element for holding the ampoule and moveable between open and closed positions, and a piston rod withdrawal element coupled between the drawer element and the piston rod such that, when the drawer element is opened, the nut is moved to its second position and the second end of the first part of the piston rod is pushed towards the lifter without rotating the spindle. 9. A drug delivery device according to claim 8, wherein the nut member has two overlapping bores at an angle to one another, wherein one bore has an inner thread matching the thread of the spindle and the other bore is smooth and fits slidingly over the spindle, wherein the nut member is tiltably mounted relative to the first part of the piston rod so that the threaded bore is concentric with the second part of the piston rod when in its first position, during dose setting and injection, and is tilted to its second position to bring the smooth bore to a position concentric with the second part of the piston when the drawer is opened. 10. A drug delivery system according to claim 9, wherein the nut member is tilted to its smooth bore position when the nut member is acted on by the piston rod withdrawal element.