WO2008101829A1 - An injection device comprising a worm gear connection - Google Patents

An injection device comprising a worm gear connection Download PDF

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Publication number
WO2008101829A1
WO2008101829A1 PCT/EP2008/051624 EP2008051624W WO2008101829A1 WO 2008101829 A1 WO2008101829 A1 WO 2008101829A1 EP 2008051624 W EP2008051624 W EP 2008051624W WO 2008101829 A1 WO2008101829 A1 WO 2008101829A1
Authority
WO
WIPO (PCT)
Prior art keywords
lead screw
injection
injection device
dose setting
dose
Prior art date
Application number
PCT/EP2008/051624
Other languages
French (fr)
Inventor
Thomas Pedersen
Original Assignee
Novo Nordisk A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Novo Nordisk A/S filed Critical Novo Nordisk A/S
Publication of WO2008101829A1 publication Critical patent/WO2008101829A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31533—Dosing mechanisms, i.e. setting a dose
    • A61M5/31545—Setting modes for dosing
    • A61M5/31548—Mechanically operated dose setting member
    • A61M5/3155—Mechanically operated dose setting member by rotational movement of dose setting member, e.g. during setting or filling of a syringe
    • A61M5/31553—Mechanically operated dose setting member by rotational movement of dose setting member, e.g. during setting or filling of a syringe without axial movement of dose setting member
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31533—Dosing mechanisms, i.e. setting a dose
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31565—Administration mechanisms, i.e. constructional features, modes of administering a dose
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31511—Piston or piston-rod constructions, e.g. connection of piston with piston-rod
    • A61M2005/3152—Piston or piston-rod constructions, e.g. connection of piston with piston-rod including gearings to multiply or attenuate the piston displacing force
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31533—Dosing mechanisms, i.e. setting a dose
    • A61M5/31535—Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose
    • A61M5/31541—Means preventing setting of a dose beyond the amount remaining in the cartridge
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31533—Dosing mechanisms, i.e. setting a dose
    • A61M5/31535—Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose
    • A61M5/31543—Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose piston rod reset means, i.e. means for causing or facilitating retraction of piston rod to its starting position during cartridge change
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31533—Dosing mechanisms, i.e. setting a dose
    • A61M5/31545—Setting modes for dosing
    • A61M5/31548—Mechanically operated dose setting member
    • A61M5/3155—Mechanically operated dose setting member by rotational movement of dose setting member, e.g. during setting or filling of a syringe
    • A61M5/31551—Mechanically operated dose setting member by rotational movement of dose setting member, e.g. during setting or filling of a syringe including axial movement of dose setting member
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31533—Dosing mechanisms, i.e. setting a dose
    • A61M5/31545—Setting modes for dosing
    • A61M5/31548—Mechanically operated dose setting member
    • A61M5/31556—Accuracy improving means
    • A61M5/31558—Accuracy improving means using scaling up or down transmissions, e.g. gearbox
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31565—Administration mechanisms, i.e. constructional features, modes of administering a dose
    • A61M5/31566—Means improving security or handling thereof
    • A61M5/31573—Accuracy improving means
    • A61M5/31575—Accuracy improving means using scaling up or down transmissions, e.g. gearbox
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
    • A61M5/178—Syringes
    • A61M5/31—Details
    • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
    • A61M5/31565—Administration mechanisms, i.e. constructional features, modes of administering a dose
    • A61M5/31576—Constructional features or modes of drive mechanisms for piston rods
    • A61M5/31578—Constructional features or modes of drive mechanisms for piston rods based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod
    • A61M5/3158—Constructional features or modes of drive mechanisms for piston rods based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod performed by axially moving actuator operated by user, e.g. an injection button

Definitions

  • the present invention relates to injection devices, preferably medical devices, such as devices suitable for self-medication, e.g. injector pens, e.g. for delivering insulin. More particularly, the present invention relates to an injection device in which coupling in and out between a dose setting system and an injection system can be avoided, while maintaining the possibility of accurate dose setting and injection.
  • medical devices such as devices suitable for self-medication, e.g. injector pens, e.g. for delivering insulin. More particularly, the present invention relates to an injection device in which coupling in and out between a dose setting system and an injection system can be avoided, while maintaining the possibility of accurate dose setting and injection.
  • An injection device for injecting a medical drug into the body of a user typically has the ability for the user to set a specific dose, i.e. amount of drug to be injected, and subsequently to inject the set dose of drug into the body.
  • various technical solutions have previously been used, e.g. electrical, mechanical, etc.
  • the solutions for accommodating the two main functions described above are typically separated into more or less independent technical solutions. Thereby a number of drawbacks and problems are introduced.
  • When activating the dose setting unit of an injection device it is important that the dose injection unit is kept in place in order not to jeopardize the dose accuracy when the injection function is subsequently activated.
  • US 5,279,586 discloses an injection device for injecting fluids such as insulin within body tissue.
  • the device includes a housing, a piston rod, and a dose setting mechanism for controlling the movement of the piston rod with respect to a fluid containing cartridge.
  • the piston rod includes a plunger and a lead screw slidably positioned within the plunger.
  • the lead screw includes an enlarged front end and a tapered rear end which are connected by an elongate threaded body. A pair of longitudinal grooves are formed within the threaded body. The grooves receive radially inwardly extending projections formed on the plunger.
  • the lead screw is accordingly rotatable with the plunger and capable of sliding axially with respect to the plunger.
  • the adjusting knob is first set to zero by releasing the plunger, thereby moving it axially in a backwards direction. Then the adjusting knob is rotated away from the zero setting, the plunger rotates, and thereby the lead screw turns and screws forward in a nut. When the dose is injected the plunger is moved a fixed distance, and the injected dose thereby depends on the travel of the lead screw during dose setting.
  • US 2005/0090781 discloses an administration instrument for medical use that can perform injection of a drug solution.
  • the instrument may comprise a rotatable adjustment knob for setting a dose.
  • a plunger is also rotated.
  • the plunger comprises a threaded portion which engages an inner thread arranged on a movable piece.
  • a toothed rack arranged on the exterior of the movable piece thereby engages a gear arrangement which moves an injection button in a direction out of the instrument.
  • the injection button is pushed, thereby moving the movable piece and the plunger in an axial direction, and the plunger causes injection of the set dose.
  • an injection device having a geared mechanism including a gear-box which during dose setting rotates relative to both a plunger and to the housing.
  • the gear-box performs a helical movement along a threaded tubular member in a proximal direction of the device.
  • the gear-box remains rotationally locked relative to the housing during injection.
  • a syringe which includes a worm drive mechanism and providing an axle extending from the housing which is adapted for being connected to a motorized drive.
  • an object of the invention to provide an injection device in which coupling in and out of a dose setting mechanism and of an injection mechanism can be avoided.
  • an injection device comprising:
  • a dose setting mechanism comprising a dose setting means adapted to be rotated to set a desired dose
  • a lead screw adapted to cooperate with a piston of a cartridge containing a drug to be injected by means of the injection device, so as to cause a dose of drug to be injected, said lead screw being connected to the dose setting means in such a manner that the lead screw is adapted to perform a rotational movement relative to the housing portion when the dose setting means is rotated, and in such a manner that the lead screw and the dose setting means are slidably movable relatively to each other, and
  • injection means being operatively connected to the lead screw via a worm gear connection in such a manner that a linear movement of the injection means relative to the housing portion causes the lead screw to perform a linear movement, thereby causing a set dose to be injected, the dose setting means and the injection means thereby being connected via the lead screw and the worm gear connection.
  • the term 'injection device' should be interpreted to mean a device which can be used for injecting a desired dose of drug, preferably liquid drug.
  • the injection device is preferably of a kind being suitable for performing self injection of liquid drug, e.g. insulin or growth hormone.
  • the injection device may advantageously be a pen-shaped injection device, but it could alternatively have any other suitable shape.
  • the dose setting mechanism is a part of the injection device which is used when a desired dose of drug is being set by a user.
  • the dose setting means is a part of the dose setting mechanism which a user operates, preferably manually, in order to set the dose.
  • the user rotates the dose setting means, and this causes the dose setting mechanism to set the injection device in such a manner that when an injection means is subsequently operated, a desired set dose is injected by the injection device.
  • the lead screw is adapted to cooperate with a piston of a cartridge containing a drug to be injected.
  • the cartridge may form part of the injection device, or it may be a replaceable cartridge, in which case the injection device is preferably of a reusable kind. This will be described further below.
  • the piston of the cartridge is normally arranged in the interior of the cartridge in such a manner that moving the piston causes drug to be pushed out of the cartridge, the distance travelled by the piston determining the dose being pushed out.
  • the lead screw is preferably positioned relatively to the piston in such a manner that the piston is moved when the lead screw is moved, and thereby moving the lead screw causes drug to be pushed out of the cartridge, and this drug is thereby injected by the injection device.
  • the lead screw is connected to the dose setting means in such a manner that the lead screw is adapted to perform a rotational movement when the dose setting means is rotated, and in such a manner that the lead screw and the dose setting means are slidably movable relatively to each other.
  • the lead screw and the dose setting means can move slidably relatively to each other.
  • the injection means is a part of the injection device which ensures that, upon operation, a dose set by means of the dose setting mechanism is actually injected by the injection device.
  • the injection means preferably comprises a part which is operable by a user, preferably manually, in order to inject the set dose.
  • a part may, e.g., be in the form of an injection button which must be pressed by the user.
  • the injection means is connected to the lead screw via a worm gear connection.
  • a worm gear connection normally comprises a worm and one or more gear wheels which directly or indirectly engage the worm.
  • the gear wheel(s) When the worm is rotated the gear wheel(s) also rotate(s), thereby possibly causing a translational movement of a part connected to the gear wheel(s).
  • the gear wheel(s) when the gear wheel(s) is/are rotated, the engagement with the worm will cause the part having the worm arranged thereon to move translationally, because the thread of the worm will typically have a very low pitch, and therefore it requires a large force to rotate the worm in a reverse direction. Accordingly, the worm will instead be moved translationally.
  • the dose setting means and the injection means are connected via the lead screw and the worm gear connection.
  • the dose setting means and the injection means are integrated, and coupling in and out between a dose setting function and an injection function is thereby avoided.
  • the lead screw it is still possible for the lead screw to be in contact with the piston of the cartridge during dose setting, thereby ensuring a very accurate dose setting as well as a very accurate dose injection. This is very advantageous.
  • the lead screw may be rotatably locked to the dose setting means. In this case the lead screw is rotated along when the dose setting means is rotated, e.g. during dose setting.
  • This connection between the lead screw and the dose setting means may, e.g., be obtained by positioning one inside the other with the lead screw and the dose setting means having non- circular cross sections.
  • the lead screw and the dose setting means may be connected via a key and groove connection, or in any other suitable manner.
  • the dose setting means and the lead screw may be adapted to rotate about separate rotational axes.
  • the dose setting means and the lead screw may advantageously be connected via one or more gear wheels.
  • the fact that the dose setting means and the lead screw rotate about separate rotational axes allows the injection device to be manufactured with a relatively flat design. For some applications, e.g. when it is desired to position additional electronics and/or a display in the injection device, this may be advantageous.
  • the lead screw may be adapted to abut a piston of a cartridge during dose setting as well as during injection of a set dose. As mentioned above, this ensures accurate dose setting as well as accurate injection of a set dose.
  • the worm gear connection may comprise:
  • the injection device is preferably operated in the following manner.
  • the dose setting means is rotationally operated to set the desired dose. Since the lead screw is adapted to perform a rotational movement when the dose setting means is rotated, this will cause the lead screw to rotate. Thereby the worm formed on the lead screw will also rotate, and since the first gear wheel engages the worm, the rotation of the worm will cause the first gear wheel to rotate. This, in turn, will cause the second gear wheel to rotate, and since the second gear wheel engages the gear rack, the gear rack will thereby move translationally, thereby causing the injection means to move translationally.
  • the travel of the injection means preferably indicates the amount of the set dose.
  • the user presses the injection means in a direction which is opposite to the direction in which the injection means was moved during dose setting as described above. This causes a corresponding translational movement of the gear rack, thereby causing the second gear wheel and the first gear wheel to rotate. Since the first gear wheel engages the worm formed on the lead screw, rotation of the first gear wheel will cause the lead screw to move translationally, thereby causing the set dose to be injected.
  • the worm may be in the form of a thread having a very low pitch.
  • it may be in the form of a helical spring fixed to the lead screw, and also having a low pitch.
  • the first gear wheel and the second gear wheel may define a non-unity gearing ratio, such as a 2 to 1 gearing ratio, or any other desired gearing ratio.
  • the injection device may further comprise means for preventing setting of a dose larger than a remaining amount of drug in a cartridge. This may, e.g., be achieved by using means which prevent further rotation of the lead screw when a dose corresponding to the remaining amount of drug in the cartridge has been set.
  • the injection device may comprise means for preventing setting of a dose larger than a predetermined dose, even if more drug remains in the cartridge.
  • the injection device may advantageously be a reusable device, i.e. a device in which the cartridge may be replaced by a new cartridge when it is empty.
  • the injection device may be a disposable device, i.e. it may be of a kind in which the cartridge is an integral part, and which is disposed of when the cartridge is empty.
  • the injection device may further comprise a release mechanism adapted to release the lead screw in order to allow the lead screw to return to an initial position during or prior to change of cartridge.
  • the release mechanism may, e.g., be in the form of a nut travelling along with the lead screw during injection, and means for releasing the lead screw and the nut when it is desired to change the cartridge, thereby allowing the lead screw to move without the nut.
  • Fig. 1 is a cross sectional view of an injection device according to a first embodiment of the invention
  • Fig. 2 is a cross sectional view of an injection device according to a second embodiment of the invention.
  • Fig. 3 is a cross sectional view of an injection device according to a third embodiment of the invention.
  • Fig. 1 is a cross sectional view of an injection device 1 according to a first embodiment of the invention, the injection device 1 comprising a housing 2.
  • the injection device 1 comprises a dose setting mechanism 3 comprising a rotatable dose knob 4.
  • the injection device 1 further comprises a lead screw 5 having a worm 6 formed thereon.
  • the lead screw 5 comprises a head 7 having a non-circular, e.g. a polygonal, cross section.
  • the dose setting mechanism 3 is provided with a hollow part 8 in which the head 7 of the lead screw 5 is accommodated.
  • the hollow part 8 has a cross section which matches the cross section of the head 7 of the lead screw 5 in such a manner that it prevents the lead screw 5 and the dose setting mechanism 3 from rotating relatively to each other. On the other hand, the lead screw 5 is allowed to move slidably within the hollow part 8.
  • the lead screw 5 abuts a piston 9 arranged inside a cartridge 10 containing a drug to be injected, the cartridge 10 being arranged inside the injection device 1, i.e. within the housing 2.
  • the abutment takes place via an abutment foot 11 attached to the lead screw 5 in such a manner that the lead screw 5 and the abutment foot 11 can rotate relatively to each other, but are locked axially relatively to each other.
  • the piston 9 is arranged slidably inside the cartridge 10, and thereby moving the piston 9 in a distal direction, i.e. in a direction away from the dose setting mechanism 3, liquid drug is expelled from the cartridge 10, and can thereby be injected.
  • the injection device 1 further comprises an injection button 12 which is axially movable, and which is connected to a gear rack 13.
  • the gear rack 13 forms part of a gear arrangement, also comprising a first gear wheel 14 and a second gear wheel 15.
  • the first gear wheel 14 engages the worm 6 and the second gear wheel 15 engages the gear rack 13.
  • the first gear wheel 14 and the second gear wheel 15 are connected to the same rotational axis 16, and thereby rotation of the first gear wheel 14 will result in rotation of the second gear wheel 15, and vice versa. This allows for introduction of a gearing between the rotational movement of the lead screw 5 and the translational movement of the injection button 12.
  • the rotational axis 16 is fixed axially relatively to the housing 2.
  • the injection device 1 of Fig. 1 is preferably operated in the following manner.
  • the user rotates the dose knob 4.
  • the lead screw 5 rotates along with the dose knob 4.
  • This causes the first gear wheel 14, as well as the second gear wheel 15, to rotate about the rotational axis 16, due to the engagement between the worm 6 formed on the lead screw 5 and the first gear wheel 14.
  • the rotation of the second gear wheel 15 causes the gear rack 13, and thereby the injection button 12, to move in a proximal direction, i.e. in a direction away from the cartridge 10.
  • the travel of the injection button 12 represents the dose being set.
  • the user then positions a needle (not shown) at an appropriate injection site, and the set dose can be injected in the following manner.
  • the user pushes the injection button 12 in a distal direction.
  • the gear rack 13 is also moved in a distal direction, thereby causing the second gear wheel 15, as well as the first gear wheel 14, to rotate about the rotational axis 16.
  • the engagement between the first gear wheel 14 and the worm 6 will then cause the lead screw 5 to move in a distal direction.
  • the lead screw 5 pushes the piston 9 in a distal direction inside the cartridge 10, and via the abutment foot 11. This causes the set dose to be injected by the injection device 1.
  • Fig. 2 is a cross sectional view of an injection device 1 according to a second embodiment of the invention.
  • the injection device 1 of Fig. 2 is operated essentially as the injection device 1 of Fig. 1, and the parts which have already been described above, as well as their function, will therefore not be described in detail here.
  • a smaller part of the injection device 1 is shown in Fig. 2 than in Fig. 1, and a middle part of the lead screw 5 has been cut away for the sake of clarity.
  • the injection device 1 is provided with a nut 17 being connected to the worm 6 formed on the lead screw 5 via the outer thread defined by the worm 6 and an inner thread of the nut 17.
  • the nut 17 is in the form of a helical spring.
  • the nut 17 is rotationally locked to the housing 2 by means of protrusions 18 formed on the nut 17 and being arranged in a groove 19 in the housing 2.
  • the groove 19 could be formed in another part which is locked relatively to the housing 2.
  • the protrusions 18 are formed by the ends of the helical spring making up the nut 17. The ends have been bent in such a manner that they protrude from the nut 17 in a direction perpendicular to the axial direction of the injection device 1.
  • the nut 17 and groove 19 arrangement illustrated in Fig. 2 defines the largest settable dose of the injection device 1.
  • the injection device 1 is further provided with a release element 21 having a recess 22 formed therein.
  • the recess 22 is arranged at a position corresponding to the position of the groove 19 formed in the housing 2. Thus, when the nut 17 is in the position shown in Fig. 2 one of the protrusions 18 is arranged in the recess 22.
  • the nut 17 and the protrusions 18 being arranged in the groove 19 prevent the lead screw 5 from being moved a long distance in a proximal direction.
  • the injection device 1 is a reusable device, it must be possible to replace an empty cartridge by a new one. When doing so, it is necessary to return the lead screw 5 to an initial position, i.e. to move it axially in a proximal direction. In the embodiment shown in Fig. 2 this is achieved in the following manner.
  • the release element 21 When it is desired to replace a cartridge, the release element 21 is rotated in a direction indicated by arrow 23, while the protrusion 18 is arranged in the recess 22. Since the other protrusion 18 is arranged in the grove 19, this will cause the helical spring forming the nut 17 to expand, i.e. the diameter of the nut 17 is increased. As a consequence, the threaded engagement between the lead screw 5 and the nut 17 is released, and it is thereby possible to move the lead screw 5 in a proximal direction without moving the nut 17. Accordingly, the lead screw 5 can be returned to the initial position, and a new cartridge can be inserted.
  • Fig. 3 is a cross sectional view of an injection device 1 according to a third embodiment of the invention.
  • the dose knob 4 and the lead screw 5 are adapted to rotate about separate rotational axes.
  • Most of the remaining parts of the injection device 1 are very similar to and are operated very similar to the corresponding parts of the injection device of Fig. 1. These parts will therefore not be described in detail here.
  • the dose setting mechanism 3 comprises an extruded gear wheel 24 which is rotatably locked to the dose knob 4.
  • the lead screw 5 is provided with a gear wheel 25, and the extruded gear wheel 24 and the gear wheel 25 are arranged in meshing engagement.
  • the dose knob 4 When it is desired to set a dose, the dose knob 4 is rotated, and the extruded gear wheel 24 rotates along. Due to the meshing engagement between the extruded gear wheel 24 and the gear wheel 25, this causes the gear wheel 25, and thereby the lead screw 5, to rotate. As described above with reference to Fig. 1 this will cause the injection button 12 to move in a proximal direction, due to the worm 6, the gear wheels 14, 15 and the gear rack 13.
  • the injection button 12 When the dose has been set, the injection button 12 is pressed in a distal direction, thereby causing the lead screw 5 to move translationally in a distal direction, as described above. Due to the extruded gear wheel 24, this translational movement of the lead screw 5 can be performed without moving the dose setting mechanism 3, in particular the dose knob 4, translationally.

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Abstract

An injection device (1) comprising a dose setting mechanism (3) and injection means. The injection device comprises a lead screw (5) which is adapted to perform a rotational movement when a dose setting means is rotated during dose setting, and which is adapted to cooperate with a piston (9) of a cartridge (10) in order to cause a set dose of drug to be injected from the cartridge. The lead screw is connected to the injection means via a worm gear (6) connection in such a manner that linear movement of the injection means causes linear movement of the lead screw. Thus, the dose setting means and the injection means are connected via the lead screw and the worm gear connection. Thereby the dose setting mechanism and the injection mechanism are integrated into each other by, at least partly, using the same components. The need for coupling a dose setting mechanism and an injection mechanism in and out during operation is thereby avoided, and a greater accuracy is obtained during dose setting and during injection.

Description

AN INJECTION DEVICE COMPRISING A WORM GEAR CONNECTION
FIELD OF THE INVENTION
The present invention relates to injection devices, preferably medical devices, such as devices suitable for self-medication, e.g. injector pens, e.g. for delivering insulin. More particularly, the present invention relates to an injection device in which coupling in and out between a dose setting system and an injection system can be avoided, while maintaining the possibility of accurate dose setting and injection.
BACKGROUND OF THE INVENTION
An injection device for injecting a medical drug into the body of a user typically has the ability for the user to set a specific dose, i.e. amount of drug to be injected, and subsequently to inject the set dose of drug into the body. In order to accommodate these features, various technical solutions have previously been used, e.g. electrical, mechanical, etc. In prior art mechanical injection devices the solutions for accommodating the two main functions described above are typically separated into more or less independent technical solutions. Thereby a number of drawbacks and problems are introduced. When activating the dose setting unit of an injection device it is important that the dose injection unit is kept in place in order not to jeopardize the dose accuracy when the injection function is subsequently activated. This may be very difficult, and typically requires additional components in the case that the dose setting mechanism and the injection mechanism are separated, thereby increasing the complexity of the device. Furthermore, when separating the dose setting mechanism and the injection mechanism, it is necessary to couple the two systems in and out in order to perform dose setting as well as injection at appropriate and selected times. This is also a challenge, because the coupling in and out has to be precise in order to prevent the device from jamming, and in order to ensure an accurate transfer of information from the dose setting system to the injection system, i.e. in order to ensure that the set dose is also the dose which is actually injected by the device.
US 5,279,586 discloses an injection device for injecting fluids such as insulin within body tissue. The device includes a housing, a piston rod, and a dose setting mechanism for controlling the movement of the piston rod with respect to a fluid containing cartridge. The piston rod includes a plunger and a lead screw slidably positioned within the plunger. The lead screw includes an enlarged front end and a tapered rear end which are connected by an elongate threaded body. A pair of longitudinal grooves are formed within the threaded body. The grooves receive radially inwardly extending projections formed on the plunger. The lead screw is accordingly rotatable with the plunger and capable of sliding axially with respect to the plunger. During dose setting the adjusting knob is first set to zero by releasing the plunger, thereby moving it axially in a backwards direction. Then the adjusting knob is rotated away from the zero setting, the plunger rotates, and thereby the lead screw turns and screws forward in a nut. When the dose is injected the plunger is moved a fixed distance, and the injected dose thereby depends on the travel of the lead screw during dose setting.
Thus, in the device disclosed in US 5,279,586 the dose setting mechanism and the injection mechanism need to be coupled in and out when a dose is to be set or injected. Furthermore, it is a disadvantage that the lead screw is pulled away from the piston of the cartridge during dose setting, since this has an adverse effect on the accuracy of the dose setting as described above.
US 2005/0090781 discloses an administration instrument for medical use that can perform injection of a drug solution. The instrument may comprise a rotatable adjustment knob for setting a dose. When rotating the adjustment knob during dose setting a plunger is also rotated. The plunger comprises a threaded portion which engages an inner thread arranged on a movable piece. Thus, when the plunger rotates the movable piece moves axially, and a toothed rack arranged on the exterior of the movable piece thereby engages a gear arrangement which moves an injection button in a direction out of the instrument. During injection the injection button is pushed, thereby moving the movable piece and the plunger in an axial direction, and the plunger causes injection of the set dose. In the instrument disclosed in US 2005/0090781 it is also necessary to couple the dose setting mechanism and the injection mechanism in and out when a dose is to be set of injected. Furthermore, the plunger is, also in this case, pulled away from the cartridge during dose setting. Accordingly, the disadvantages described above are also present in this instrument.
In WO patent application No. 2006/114395 an injection device is disclosed having a geared mechanism including a gear-box which during dose setting rotates relative to both a plunger and to the housing. During dose setting the gear-box performs a helical movement along a threaded tubular member in a proximal direction of the device. The gear-box remains rotationally locked relative to the housing during injection.
Further, in DE patent application No. 1076332, a syringe is disclosed which includes a worm drive mechanism and providing an axle extending from the housing which is adapted for being connected to a motorized drive. SUMMARY OF THE INVENTION
It is, thus, an object of the invention to provide an injection device in which coupling in and out of a dose setting mechanism and of an injection mechanism can be avoided.
It is a further object of the invention to provide an injection device in which a high degree of accuracy can be obtained in dose setting as well as in injection.
It is an even further object of the invention to provide an injection device in which problems relating to jamming of the device are minimised.
It is an even further object of the invention to provide an alternative gearing mechanism in an injection device enabling a geared movement between injection means operable by the user and the movement of the lead screw and wherein the mechanism enables various different gearing ratios to be obtained.
According to the invention the above and other objects are fulfilled by providing an injection device comprising :
- a housing portion,
- a dose setting mechanism comprising a dose setting means adapted to be rotated to set a desired dose,
- a lead screw adapted to cooperate with a piston of a cartridge containing a drug to be injected by means of the injection device, so as to cause a dose of drug to be injected, said lead screw being connected to the dose setting means in such a manner that the lead screw is adapted to perform a rotational movement relative to the housing portion when the dose setting means is rotated, and in such a manner that the lead screw and the dose setting means are slidably movable relatively to each other, and
- injection means being operatively connected to the lead screw via a worm gear connection in such a manner that a linear movement of the injection means relative to the housing portion causes the lead screw to perform a linear movement, thereby causing a set dose to be injected, the dose setting means and the injection means thereby being connected via the lead screw and the worm gear connection.
In the present context the term 'injection device' should be interpreted to mean a device which can be used for injecting a desired dose of drug, preferably liquid drug. The injection device is preferably of a kind being suitable for performing self injection of liquid drug, e.g. insulin or growth hormone. The injection device may advantageously be a pen-shaped injection device, but it could alternatively have any other suitable shape.
The dose setting mechanism is a part of the injection device which is used when a desired dose of drug is being set by a user. The dose setting means is a part of the dose setting mechanism which a user operates, preferably manually, in order to set the dose. Thus, when a dose is to be set the user rotates the dose setting means, and this causes the dose setting mechanism to set the injection device in such a manner that when an injection means is subsequently operated, a desired set dose is injected by the injection device.
The lead screw is adapted to cooperate with a piston of a cartridge containing a drug to be injected. The cartridge may form part of the injection device, or it may be a replaceable cartridge, in which case the injection device is preferably of a reusable kind. This will be described further below. The piston of the cartridge is normally arranged in the interior of the cartridge in such a manner that moving the piston causes drug to be pushed out of the cartridge, the distance travelled by the piston determining the dose being pushed out. The lead screw is preferably positioned relatively to the piston in such a manner that the piston is moved when the lead screw is moved, and thereby moving the lead screw causes drug to be pushed out of the cartridge, and this drug is thereby injected by the injection device.
The lead screw is connected to the dose setting means in such a manner that the lead screw is adapted to perform a rotational movement when the dose setting means is rotated, and in such a manner that the lead screw and the dose setting means are slidably movable relatively to each other. Thus, when the dose setting means is rotated, such as during dose setting, the lead screw also performs a rotational movement. Furthermore, the lead screw and the dose setting means can move slidably relatively to each other. Thus, it is possible for the lead screw to move axially, e.g. during injection in order to move the piston of the cartridge as described above, without moving the dose setting means axially.
The injection means is a part of the injection device which ensures that, upon operation, a dose set by means of the dose setting mechanism is actually injected by the injection device. The injection means preferably comprises a part which is operable by a user, preferably manually, in order to inject the set dose. Such a part may, e.g., be in the form of an injection button which must be pressed by the user.
The injection means is connected to the lead screw via a worm gear connection. A worm gear connection normally comprises a worm and one or more gear wheels which directly or indirectly engage the worm. When the worm is rotated the gear wheel(s) also rotate(s), thereby possibly causing a translational movement of a part connected to the gear wheel(s). On the other hand, when the gear wheel(s) is/are rotated, the engagement with the worm will cause the part having the worm arranged thereon to move translationally, because the thread of the worm will typically have a very low pitch, and therefore it requires a large force to rotate the worm in a reverse direction. Accordingly, the worm will instead be moved translationally.
Accordingly, the dose setting means and the injection means are connected via the lead screw and the worm gear connection. Thus, the dose setting means and the injection means are integrated, and coupling in and out between a dose setting function and an injection function is thereby avoided. Furthermore, it is still possible for the lead screw to be in contact with the piston of the cartridge during dose setting, thereby ensuring a very accurate dose setting as well as a very accurate dose injection. This is very advantageous.
The lead screw may be rotatably locked to the dose setting means. In this case the lead screw is rotated along when the dose setting means is rotated, e.g. during dose setting. This connection between the lead screw and the dose setting means may, e.g., be obtained by positioning one inside the other with the lead screw and the dose setting means having non- circular cross sections. Alternatively, the lead screw and the dose setting means may be connected via a key and groove connection, or in any other suitable manner.
As an alternative, the dose setting means and the lead screw may be adapted to rotate about separate rotational axes. In this case the dose setting means and the lead screw may advantageously be connected via one or more gear wheels. The fact that the dose setting means and the lead screw rotate about separate rotational axes allows the injection device to be manufactured with a relatively flat design. For some applications, e.g. when it is desired to position additional electronics and/or a display in the injection device, this may be advantageous. Furthermore, it will be possible to introduce a gearing between the rotation of the dose setting means and the rotation of the lead screw.
According to one embodiment the lead screw may be adapted to abut a piston of a cartridge during dose setting as well as during injection of a set dose. As mentioned above, this ensures accurate dose setting as well as accurate injection of a set dose. The worm gear connection may comprise:
a worm formed on the lead screw,
- a first gear wheel engaging the worm,
a gear rack connected to the injection means, and
- a second gear wheel adapted to engage the gear rack and being connected to the first gear wheel in such a manner that rotation of the first gear wheel causes the second gear wheel to rotate.
The injection device according to this embodiment is preferably operated in the following manner. When it is desired to inject a dose, the dose setting means is rotationally operated to set the desired dose. Since the lead screw is adapted to perform a rotational movement when the dose setting means is rotated, this will cause the lead screw to rotate. Thereby the worm formed on the lead screw will also rotate, and since the first gear wheel engages the worm, the rotation of the worm will cause the first gear wheel to rotate. This, in turn, will cause the second gear wheel to rotate, and since the second gear wheel engages the gear rack, the gear rack will thereby move translationally, thereby causing the injection means to move translationally. The travel of the injection means preferably indicates the amount of the set dose.
When the dose has been set the user presses the injection means in a direction which is opposite to the direction in which the injection means was moved during dose setting as described above. This causes a corresponding translational movement of the gear rack, thereby causing the second gear wheel and the first gear wheel to rotate. Since the first gear wheel engages the worm formed on the lead screw, rotation of the first gear wheel will cause the lead screw to move translationally, thereby causing the set dose to be injected.
The worm may be in the form of a thread having a very low pitch. Alternatively, it may be in the form of a helical spring fixed to the lead screw, and also having a low pitch.
The first gear wheel and the second gear wheel may define a non-unity gearing ratio, such as a 2 to 1 gearing ratio, or any other desired gearing ratio. In this case the travel of the injection means in response to a specific rotation of the dose setting means, and vice versa, can be designed by selecting an appropriate gearing ratio. The injection device may further comprise means for preventing setting of a dose larger than a remaining amount of drug in a cartridge. This may, e.g., be achieved by using means which prevent further rotation of the lead screw when a dose corresponding to the remaining amount of drug in the cartridge has been set. Alternatively or additionally, the injection device may comprise means for preventing setting of a dose larger than a predetermined dose, even if more drug remains in the cartridge.
The injection device may advantageously be a reusable device, i.e. a device in which the cartridge may be replaced by a new cartridge when it is empty. Alternatively, the injection device may be a disposable device, i.e. it may be of a kind in which the cartridge is an integral part, and which is disposed of when the cartridge is empty.
Thus, the injection device may further comprise a release mechanism adapted to release the lead screw in order to allow the lead screw to return to an initial position during or prior to change of cartridge. The release mechanism may, e.g., be in the form of a nut travelling along with the lead screw during injection, and means for releasing the lead screw and the nut when it is desired to change the cartridge, thereby allowing the lead screw to move without the nut.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in further detail with reference to the accompanying drawings in which
Fig. 1 is a cross sectional view of an injection device according to a first embodiment of the invention,
Fig. 2 is a cross sectional view of an injection device according to a second embodiment of the invention, and
Fig. 3 is a cross sectional view of an injection device according to a third embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross sectional view of an injection device 1 according to a first embodiment of the invention, the injection device 1 comprising a housing 2. For the sake of clarity only a small part of the housing 2 is shown in Fig. 1, but it should be understood that, in reality, the housing 2 at least substantially surrounds the remaining parts of the injection device 1. The injection device 1 comprises a dose setting mechanism 3 comprising a rotatable dose knob 4. The injection device 1 further comprises a lead screw 5 having a worm 6 formed thereon. The lead screw 5 comprises a head 7 having a non-circular, e.g. a polygonal, cross section. The dose setting mechanism 3 is provided with a hollow part 8 in which the head 7 of the lead screw 5 is accommodated. The hollow part 8 has a cross section which matches the cross section of the head 7 of the lead screw 5 in such a manner that it prevents the lead screw 5 and the dose setting mechanism 3 from rotating relatively to each other. On the other hand, the lead screw 5 is allowed to move slidably within the hollow part 8.
The lead screw 5 abuts a piston 9 arranged inside a cartridge 10 containing a drug to be injected, the cartridge 10 being arranged inside the injection device 1, i.e. within the housing 2. The abutment takes place via an abutment foot 11 attached to the lead screw 5 in such a manner that the lead screw 5 and the abutment foot 11 can rotate relatively to each other, but are locked axially relatively to each other. The piston 9 is arranged slidably inside the cartridge 10, and thereby moving the piston 9 in a distal direction, i.e. in a direction away from the dose setting mechanism 3, liquid drug is expelled from the cartridge 10, and can thereby be injected.
The injection device 1 further comprises an injection button 12 which is axially movable, and which is connected to a gear rack 13. The gear rack 13 forms part of a gear arrangement, also comprising a first gear wheel 14 and a second gear wheel 15. The first gear wheel 14 engages the worm 6 and the second gear wheel 15 engages the gear rack 13. The first gear wheel 14 and the second gear wheel 15 are connected to the same rotational axis 16, and thereby rotation of the first gear wheel 14 will result in rotation of the second gear wheel 15, and vice versa. This allows for introduction of a gearing between the rotational movement of the lead screw 5 and the translational movement of the injection button 12. Thus, choosing the first gear wheel 14 and the second gear wheel 15 appropriately will result in a desired travel of the injection button 12 in response to a certain rotation of the dose knob 4. For instance, a relatively long travel of the injection button 12 may be obtained, and thereby the force required in order to return the injection button 12 to the initial position during injection of the set dose will be reduced. The rotational axis 16 is fixed axially relatively to the housing 2.
The injection device 1 of Fig. 1 is preferably operated in the following manner. When it is desired to inject a dose of drug, the user rotates the dose knob 4. Due to the head 7 of the lead screw 5 and the hollow part 8 of the dose setting mechanism 3 the lead screw 5 rotates along with the dose knob 4. This causes the first gear wheel 14, as well as the second gear wheel 15, to rotate about the rotational axis 16, due to the engagement between the worm 6 formed on the lead screw 5 and the first gear wheel 14. The rotation of the second gear wheel 15 causes the gear rack 13, and thereby the injection button 12, to move in a proximal direction, i.e. in a direction away from the cartridge 10. The travel of the injection button 12 represents the dose being set.
The user then positions a needle (not shown) at an appropriate injection site, and the set dose can be injected in the following manner. The user pushes the injection button 12 in a distal direction. Thereby the gear rack 13 is also moved in a distal direction, thereby causing the second gear wheel 15, as well as the first gear wheel 14, to rotate about the rotational axis 16. The engagement between the first gear wheel 14 and the worm 6 will then cause the lead screw 5 to move in a distal direction. Thereby the lead screw 5 pushes the piston 9 in a distal direction inside the cartridge 10, and via the abutment foot 11. This causes the set dose to be injected by the injection device 1.
Fig. 2 is a cross sectional view of an injection device 1 according to a second embodiment of the invention. The injection device 1 of Fig. 2 is operated essentially as the injection device 1 of Fig. 1, and the parts which have already been described above, as well as their function, will therefore not be described in detail here. Furthermore, a smaller part of the injection device 1 is shown in Fig. 2 than in Fig. 1, and a middle part of the lead screw 5 has been cut away for the sake of clarity.
The injection device 1 is provided with a nut 17 being connected to the worm 6 formed on the lead screw 5 via the outer thread defined by the worm 6 and an inner thread of the nut 17. In Fig. 2 the nut 17 is in the form of a helical spring. The nut 17 is rotationally locked to the housing 2 by means of protrusions 18 formed on the nut 17 and being arranged in a groove 19 in the housing 2. Alternatively, the groove 19 could be formed in another part which is locked relatively to the housing 2. In Fig. 2 the protrusions 18 are formed by the ends of the helical spring making up the nut 17. The ends have been bent in such a manner that they protrude from the nut 17 in a direction perpendicular to the axial direction of the injection device 1.
When the lead screw 5 is rotated during dose setting as described above, the nut 17 is prevented from rotating along with the lead screw 5 due to the protrusions 18 being arranged in the groove 19. Accordingly, the threaded engagement between the lead screw 5 and the nut 17 will cause the nut 17 to move axially in a proximal direction, the protrusions 18 thereby travelling in the groove 19 until reaching an end 20 of the groove 19. When the end 20 is reached it is no longer possible for the nut 17 to move axially in a proximal direction, and as a consequence it is no longer possible to rotate the lead screw 5, and thereby a larger dose can not be set. Accordingly, the nut 17 and groove 19 arrangement illustrated in Fig. 2 defines the largest settable dose of the injection device 1.
When a set dose is subsequently injected as described above, the lead screw 5 is moved axially in a distal direction, and the nut 17 will move along with the lead screw 5, thereby returning the nut 17 to the position shown in Fig. 2. When the protrusions 18 reach this position, it is not possible for the nut 17 to move further in a distal direction, and thereby it is also not possible for the lead screw 5 to move further in a distal direction, and the injection is therefore stopped. Furthermore, when the nut 17 is in this position, it is not possible to rotate the lead screw 5 in a 'wrong' direction, which would result in a 'negative' dose being set, i.e. attempts to set a dose smaller than zero will be prevented.
The injection device 1 is further provided with a release element 21 having a recess 22 formed therein. The recess 22 is arranged at a position corresponding to the position of the groove 19 formed in the housing 2. Thus, when the nut 17 is in the position shown in Fig. 2 one of the protrusions 18 is arranged in the recess 22.
The nut 17 and the protrusions 18 being arranged in the groove 19 prevent the lead screw 5 from being moved a long distance in a proximal direction. However, in the case that the injection device 1 is a reusable device, it must be possible to replace an empty cartridge by a new one. When doing so, it is necessary to return the lead screw 5 to an initial position, i.e. to move it axially in a proximal direction. In the embodiment shown in Fig. 2 this is achieved in the following manner.
When it is desired to replace a cartridge, the release element 21 is rotated in a direction indicated by arrow 23, while the protrusion 18 is arranged in the recess 22. Since the other protrusion 18 is arranged in the grove 19, this will cause the helical spring forming the nut 17 to expand, i.e. the diameter of the nut 17 is increased. As a consequence, the threaded engagement between the lead screw 5 and the nut 17 is released, and it is thereby possible to move the lead screw 5 in a proximal direction without moving the nut 17. Accordingly, the lead screw 5 can be returned to the initial position, and a new cartridge can be inserted.
Fig. 3 is a cross sectional view of an injection device 1 according to a third embodiment of the invention. In the injection device 1 of Fig. 3 the dose knob 4 and the lead screw 5 are adapted to rotate about separate rotational axes. Most of the remaining parts of the injection device 1 are very similar to and are operated very similar to the corresponding parts of the injection device of Fig. 1. These parts will therefore not be described in detail here. In the injection device 1 of Fig. 3 the dose setting mechanism 3 comprises an extruded gear wheel 24 which is rotatably locked to the dose knob 4. Furthermore, the lead screw 5 is provided with a gear wheel 25, and the extruded gear wheel 24 and the gear wheel 25 are arranged in meshing engagement. Thus, the injection device 1 of Fig. 3 can be operated in the following manner. When it is desired to set a dose, the dose knob 4 is rotated, and the extruded gear wheel 24 rotates along. Due to the meshing engagement between the extruded gear wheel 24 and the gear wheel 25, this causes the gear wheel 25, and thereby the lead screw 5, to rotate. As described above with reference to Fig. 1 this will cause the injection button 12 to move in a proximal direction, due to the worm 6, the gear wheels 14, 15 and the gear rack 13.
When the dose has been set, the injection button 12 is pressed in a distal direction, thereby causing the lead screw 5 to move translationally in a distal direction, as described above. Due to the extruded gear wheel 24, this translational movement of the lead screw 5 can be performed without moving the dose setting mechanism 3, in particular the dose knob 4, translationally.

Claims

1. An injection device comprising:
- a housing portion,
a dose setting mechanism comprising a dose setting means adapted to be rotated to set a desired dose,
- a lead screw adapted to cooperate with a piston of a cartridge containing a drug to be injected by means of the injection device, so as to cause a dose of drug to be injected, said lead screw being connected to the dose setting means in such a manner that the lead screw is adapted to perform a rotational movement relative to the housing portion when the dose setting means is rotated, and in such a manner that the lead screw and the dose setting means are slidably movable relatively to each other, and
- injection means being operatively connected to the lead screw via a worm gear connection in such a manner that a linear movement of the injection means relative to the housing portion causes the lead screw to perform a linear movement, thereby causing a set dose to be injected,
the dose setting means and the injection means thereby being connected via the lead screw and the worm gear connection.
2. An injection device according to claim 1, wherein the lead screw is rotatably locked to the dose setting means.
3. An injection device according to claim 1 or 2, wherein the lead screw is coupled to the dose setting means by a geared connection.
4. An injection device according to any of the claims 1 to 3, wherein the lead screw is adapted to remain in abutment with the piston of the cartridge during dose setting as well as during injection of a set dose.
5. An injection device according to any of the preceding claims, wherein the worm gear connection comprises: a worm formed on the lead screw,
a first gear wheel engaging the worm,
- a gear rack connected to the injection means, and
a second gear wheel adapted to engage the gear rack and being connected to the first gear wheel in such a manner that rotation of the first gear wheel causes the second gear wheel to rotate.
6. An injection device according to claim 5, wherein the injection means is adapted to move in a proximal direction relative to the housing portion during dose setting.
7. An injection device according to claim 5 or 6, wherein the first gear wheel and the second gear wheel define a non-unity gearing ratio.
8. An injection device according to any of the preceding claims, further comprising means for preventing setting of a dose larger than a remaining amount of drug in a cartridge.
9. An injection device according to any of the preceding claims, wherein said injection device is a reusable device and wherein the cartridge is replaceably mounted.
10. An injection device according to claim 9, further comprising a release mechanism adapted to release the lead screw in order to allow the lead screw to return to an initial position during or prior to replacement of the cartridge.
PCT/EP2008/051624 2007-02-20 2008-02-11 An injection device comprising a worm gear connection WO2008101829A1 (en)

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EP07003480 2007-02-20

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010115743A1 (en) * 2009-04-01 2010-10-14 Shl Group Ab Medicament delivery device
WO2011003762A1 (en) * 2009-06-30 2011-01-13 Sanofi-Aventis Deutschland Gmbh Drive mechanism and drug delivery device
WO2011039207A1 (en) * 2009-09-30 2011-04-07 Sanofi-Aventis Deutschland Gmbh Drive mechanism for a drug delivery device
WO2011081867A3 (en) * 2009-12-15 2011-09-29 Shl Group Ab Medicament delivery device
WO2011145998A1 (en) * 2010-05-20 2011-11-24 Shl Group Ab A medicament delivery device comprising a manual activation member with improved gripping and activation abilities.
WO2012023135A1 (en) * 2010-08-19 2012-02-23 Omrix Biopharmaceuticals Ltd. Device, system and method for dispensing a fixed dose of fluid
WO2015018811A3 (en) * 2013-08-06 2015-04-02 Sanofi-Aventis Deutschland Gmbh Drug delivery device
WO2017180480A1 (en) 2016-04-15 2017-10-19 Santen Pharmaceuticals Co., Ltd. Accurate, precise microliter dosing syringe
US9795744B2 (en) 2009-12-15 2017-10-24 Shl Group Ab Medicament delivery device
CN107666930A (en) * 2015-05-21 2018-02-06 伊莱利利公司 The driving with both of which gear part of injection device
USD823459S1 (en) 2009-12-15 2018-07-17 Shl Group Ab Medical injector
US10322243B2 (en) 2009-12-15 2019-06-18 Shl Group Ab Medicament delivery device
US10322244B2 (en) 2009-12-15 2019-06-18 Shl Group Ab Medicament delivery device
WO2020065563A1 (en) * 2018-09-26 2020-04-02 Galderma S.A. Injection device
US11052200B2 (en) 2013-08-29 2021-07-06 Sanofi-Aventis Deutschland Gmbh Cap for a drug delivery device
US11324893B2 (en) * 2016-09-12 2022-05-10 Norton Healthcare Limited Dose limiting mechanism
US11446444B2 (en) 2016-09-12 2022-09-20 Norton Healthcare Limited Dose delivery mechanism
US11690960B2 (en) 2019-11-14 2023-07-04 Congruence Medical Solutions, Llc Variable dosing syringe

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1076332B (en) * 1956-10-09 1960-02-25 Dr Maurice Julliard Injection syringe
WO1996032973A1 (en) * 1995-04-19 1996-10-24 Eli Lilly And Company Multi-cartridge medication injection device
WO2002024260A1 (en) * 2000-09-19 2002-03-28 Disetronic Licensing Ag Device for carrying out the dosed administration of an injectable product
US20050090781A1 (en) * 2001-12-13 2005-04-28 Tokumi Baba Administration instrument for medical use
WO2006114395A1 (en) * 2005-04-24 2006-11-02 Novo Nordisk A/S An injection device with a gearbox

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1076332B (en) * 1956-10-09 1960-02-25 Dr Maurice Julliard Injection syringe
WO1996032973A1 (en) * 1995-04-19 1996-10-24 Eli Lilly And Company Multi-cartridge medication injection device
WO2002024260A1 (en) * 2000-09-19 2002-03-28 Disetronic Licensing Ag Device for carrying out the dosed administration of an injectable product
US20050090781A1 (en) * 2001-12-13 2005-04-28 Tokumi Baba Administration instrument for medical use
WO2006114395A1 (en) * 2005-04-24 2006-11-02 Novo Nordisk A/S An injection device with a gearbox

Cited By (42)

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US8640921B2 (en) 2010-08-19 2014-02-04 Omrix Biopharmaceuticals Ltd. Device, system and method for dispensing a fixed dose of fluid
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