Injection unit for administering or delivering a fluid product

An injection device for administering or conveying fluid product, comprising:

• a housing comprising a receptacle for the product, the housing extending along an axis of the injection device;
• a delivery apparatus comprising a piston rod and a guide element, wherein the piston rod is axially movable relative to the housing in a delivery direction for discharging a set product dose in a delivery stroke that corresponds to the set product dose, wherein the guide element guides an axial movement of the piston rod;
• a drive element engaged with the piston rod;
• a dosing device for setting and correcting a product dose to be administered, the dosing device comprising a dosing sleeve and a rotary knob;
• a discharge button arranged coaxially on the dosing sleeve;
• and
• a coupling mechanism, wherein the dosing device is coupled to the delivery apparatus by the coupling mechanism, the coupling mechanism comprising at least two coupling surfaces each comprising a tooth arrangement comprising teeth, wherein the at least two coupling surfaces are movable relative to each other during a dosing operation or during a dose correction such that an acoustic and/or tactile signal is produced corresponding to the set product dose or to a corrected dose of the product, and wherein a relative movement between the at least two coupling surfaces is prevented by triggering the discharge button,
• wherein the coupling mechanism comprises a coupling member arranged non-rotatably and axially displaceably at the drive element, and wherein one of the at least two coupling surfaces is fixedly arranged on the coupling member, and another of the at least two coupling surfaces is fixedly arranged at the dosing sleeve such that the coupling surface of the coupling member and the coupling surface of the dosing sleeve can be indirectly brought into a coupling engagement by a click disk,
• wherein a radially directed reverse lock is provided between the housing and the drive element such that the drive element is rotatable only in a direction which results in a motion of the piston rod that causes a discharge of the fluid product, the reverse lock comprising a flexible arm extending radially outward,
• wherein the click disk comprises a first coupling surface and a second coupling surface and is arranged between the coupling surfaces of the coupling member and the dosing sleeve, wherein the first coupling surface of the click disk comprises a tooth arrangement complementary to the tooth arrangement of the coupling surface of the coupling member, and the second coupling surface of the click disk comprises a tooth arrangement complementary to the tooth arrangement of the coupling surface on the dosing sleeve.

An injection device for administering or conveying fluid product, comprising:

• a housing comprising a receptacle for the product, the housing extending along an axis of the injection device;
• a delivery apparatus comprising a piston rod and a guide element, wherein the piston rod is axially movable relative to the housing in a delivery direction for discharging a set product dose in a delivery stroke that corresponds to the set product dose, wherein the guide element guides an axial movement of the piston rod;
• a drive element engaged with the piston rod, wherein the drive element is rotatable and axially fixed relative to the housing;
• a reverse lock configured to form a radial engagement with the drive element that permits a rotation of drive element relative to the housing only in a direction which results in a motion of the piston rod that causes a discharge of the fluid product;
• a dosing device for setting and correcting a product dose to be administered, the dosing device comprising a dosing sleeve rotatable in a first direction in a dosing operation to an adjusted dose and in an opposite direction during a dose correction for correcting an inadvertently adjusted excessive dose to a corrected dose;
• and
• a coupling mechanism, wherein the dosing device is coupled to the delivery apparatus by the coupling mechanism, the coupling mechanism comprising at least two coupling surfaces each comprising a tooth arrangement comprising teeth, wherein the at least two coupling surfaces are movable relative to each other during the dosing operation or during the dose correction such that an acoustic and/or tactile signal is produced corresponding to the set product dose or to a corrected dose of the product, and wherein a relative movement between the at least two coupling surfaces is prevented during a discharge stroke of the piston rod,
• wherein the coupling mechanism comprises a coupling member arranged non-rotatably and axially displaceably at the drive element, and wherein one of the at least two coupling surfaces is fixedly arranged on the coupling member, and another of the at least two coupling surfaces is fixedly arranged at the dosing sleeve such that the coupling surface of the coupling member and the coupling surface of the dosing sleeve can be directly or indirectly brought into a coupling engagement.