Injection device with torsion spring and rotatable display

• US 8,357,120 B2
• Filed: 10/20/2005
• Issued: 01/22/2013
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Moller, Claus Schmidt, Markussen, Tom Hede, Enggaard, Christian Peter
• Primary Examiner(s): Lucchesi, Nicholas D
• Assistant Examiner(s): Bouchelle, Laura A
• Application Number:
  US11/665,571
• Publication Number:
  US 20090054839A1
• Time in Patent Office: 2,651 Days
• Field of Search: 604/135, 604/131, 604/134, 604/181, 604207-211, 604/224, 604/218
• US Class Current: 604/135
• CPC Class Codes: A61M 2005/202 cocking means, e.g. to bias the main drive spring of an injector
• CPC Class Codes: A61M 2005/3125 specific display means, e.g. to indicate dose setting
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• CPC Class Codes: A61M 5/20 Automatic syringes, e.g. with automatically actuated piston rod, with automatic needle injection, filling automatically A61M5/142 , A61M5/46 take precedence; hypodermic projectiles F42B12/54
• CPC Class Codes: A61M 5/31535 Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose
• CPC Class Codes: A61M 5/3155 by rotational movement of dose setting member, e.g. during setting or filling of a syringe
• CPC Class Codes: A61M 5/31553 without axial movement of dose setting member
• CPC Class Codes: A61M 5/31556 Accuracy improving means
• CPC Class Codes: A61M 5/31583 based on rotational translation, i.e. movement of piston rod is caused by relative rotation between the user activated actuator and the piston rod
• CPC Class Codes: A61M 5/31593 Multi-dose, i.e. individually set dose repeatedly administered from the same medicament reservoir

Abstract

The present invention relates to an injection device comprising a torsion spring operatively connected to a dose setting member being adapted to set a dose to be ejected from the injection device. A rotatably mounted display member adapted to display the dose to be ejected in accordance with a setting of the dose setting member is also provided. The rotatably mounted display member is adapted to be rotated over an angle corresponding to at least one revolution of the display member. The display member may be implemented as a dose indicator barrel having numerals arranged along a helical path on an outer surface thereof, or alternatively, as a counting device having two or more display wheels having numerals arranged on an outer surface thereof.

Claims

1. An injection device comprising

a helical torsion spring (12) operatively connected to a dose setting member (1), the dose setting member (1) being adapted to set a dose to be ejected from the injection device, and

a rotatably mounted display member adapted to display the dose to be ejected from the injection device in accordance with a setting of the dose setting member (1), the rotatably mounted display member being rotatable over an angle corresponding to at least one revolution of the display member, and wherein the device further comprises a drive member for driving a non-rotating threaded piston rod, the drive member having a threaded surface for engaging the thread on the piston rod, the drive member being rotatable within the device but axially fixed and wherein a ratchet couples the dose setting member to the drive member so that the dose setting member is moveable in a first direction to set a dose, the first direction being against the bias of the torsion spring, and being moveable in a second direction with the bias of the spring in order to reset or reduce a set dose without rotating the drive member, and wherein the ratchet retains the dose setting member from rotating under influence of the spring and wherein upon release of a latch the spring drives the drive member to rotate, thereby axially advancing the piston rod, and wherein rotation of the drive member is accompanied by rotation of the dose display member which returns to a zero position upon completion of the ejection of the dose.

2. An injection device according to claim 1, wherein the display member is adapted to be moved between two end positions, said two end positions defining an operation range of the display member, said operation range being associated with a substantially linear working range of the torsion spring.

3. An injection device according to claim 1, wherein the display member comprises a dose indicator barrel (9) having numerals arranged along a helical path on an outer surface thereof and wherein the dose indicator barrel threadly engages a housing surface on the interior of the device so that rotational motion of the dose indicator barrel results in its axial translation.

4. An injection device according to claim 1, wherein the display member comprises a counting device having two or more display wheels having numerals arranged on an outer surface thereof.

5. An injection device according to claim 2, further comprising

a housing (5),

a piston rod (2) having a threaded outer surface with a drive track (7) arranged in a longitudinal direction of said outer surface,

wherein the dose setting member (1) is rotatably mounted and defines a passage for the piston rod (2), the dose setting member (1) further having a guiding track (11) arranged on an inner surface thereof,

a rotatable drive member (6) being adapted to at least partly engage with at least part of the drive track (7) of the piston rod (2) so as to drive the piston rod,

wherein the dose indicator barrel (9) has a part engaging at least part of the guiding track (11) of the dose setting member (1), the dose setting member (1) and the dose indicator barrel (9) being movable in relation to each other, the dose indicator barrel (9) further having a threaded outer surface (8) cooperating with a threaded inner portion (10) of the housing (5) whereby the dose indicator barrel (9) undergoes a combined translational and rotational movement in relation to the housing (5) upon rotation of the dose setting member (1), and

wherein the injection device has a threaded portion (3) cooperating with the threaded outer surface of the piston rod (2) so that rotation of the piston rod (2) relative to the housing (5) results in a longitudinal movement of the piston rod (2).

6. An injection device according to claim 2, further comprising

a housing (5),

a piston rod (2) having a threaded outer surface with a track (7) arranged in a longitudinal direction of said outer surface,

wherein the dose setting member (1) is rotatably mounted and defines a passage for the piston rod (2), the dose setting member (1) further having a guiding track (11) arranged on an inner surface thereof,

a rotatable drive member (6) having a threaded portion cooperating with at least part of the threaded outer surface of the piston rod (2),

wherein the dose indicator barrel (9) has a part engaging at least part of the guiding track (11) of the dose setting member (1), the dose setting member (1) and the dose indicator barrel (9) being movable in relation to each other, the dose indicator barrel (9) further having a threaded outer surface (8) cooperating with a threaded inner portion (10) of the housing (5) whereby the dose indicator barrel (9) undergoes a combined translational and rotational movement in relation to the housing (5) upon rotation of the dose setting member (1), and

wherein the injection device has a portion at least partly engaging the track (7) of piston rod (2) so that rotation of the drive member (6) relative to the housing (5) results in a longitudinal movement of the piston rod (2).

7. An injection device according to claim 5, wherein the drive member (6) is adapted to be connected to the dose setting member (1) via a ratchet (13).

8. An injection device according to claim 5, wherein the torsion spring (12) is arranged between the housing (5) and the dose setting member (1) in such a way that when the dose setting member (1) is rotated around the piston rod (2), the torsion spring (12) is strained.

9. An injection device according to claim 5, further comprising a stopping member for defining an outer position of the dose indicator barrel (9), the outer position of the dose indicator barrel (9) corresponding to a maximum obtainable dose.

10. The injection device of claim 9, wherein axial movement of the display member does not cause the spring to work outside a substantially linear working range.

11. An injection device according to claim 1, further comprising a release button adapted to release the locking member (4) from its locking position and wherein the display undergoes a rotational and translation movement during operation of the device.

12. An injection device according to claim 11, wherein the release button is positioned in the distal half of the length of the injection device.

13. The apparatus of claim 1, wherein the piston rod is keyed to a component that is irrotatable with respect to the housing.

14. The injection device of claim 1, wherein axial movement of the display member does not cause the spring to operate outside a substantially linear working range.

15. The injection device of claim 1, wherein axial movement of the display member does not cause the spring to work outside a substantially linear working range.

16. A dose setting and injecting apparatus for assisting in the setting and ejection of a dose of medication from an injection device;

the apparatus comprising

a. a housing component;

b. a dose setting member capable of being rotated over an angle larger than 360 degrees;

c. a dose indicator barrel having a helical display of numerals arranged thereon and that rotates back to an initial position during ejection of a dose of medication and that moves axially during rotation;

d. a piston rod (2) having a threaded surface, the piston rod being non-rotatable relative to the housing;

e. a drive member (6) having an internal thread that engages a portion of the threaded surface on the piston rod, the drive member being rotatable relative to the housing so that when it rotates it causes axial translation of the piston rod;

f. a releasable locking member (4) that rotatably locks in a releasable manner the driver member so that it does not rotate relative to the housing component;

g. a helical torsional spring which extends coaxially with the piston rod and which interconnects with the dose setting member in such a way that rotation of the dose setting member in a direction that sets a dose strains the spring;

h. a ratchet coupling the dose setting member to the drive member, the ratchet allowing a dose to be set by a procedure that consists of dialing up a dose against the strain of the spring to set a dose size and, when necessary, dialing the dose setting member in an opposite direction to reduce the size of the dose, wherein the ratchet allows the dose setting member to be dialed in an up and a down direction without rotation of the drive member but where the ratchet prevents the torsional spring from rotating the dose setting member in a downward, dose reducing direction;

wherein when the releasable locking member is released, the drive member is free to rotate under the influence of the spring and thereby drives the piston rod in an axial direction to expel a drug from the device.

17. The apparatus of claim 16, wherein the spring is coupled directly between the housing and the dose setting member.

18. The apparatus of claim 16, wherein the spring is operably coupled to the dose setting member at one portion and operably fixed with respect to the housing another portion, so that rotation of the dose setting member relative to the housing strains the spring.

19. The apparatus of claim 18, wherein the latch member moves axially to release the drive member.

20. The apparatus of claim 18, wherein the piston rod is keyed to prevent rotation.

21. The apparatus of claim 16, wherein the dose indicator barrel moves axially in a first direction during setting of a dose and axially in an opposite direction during injection of the dose.

22. The apparatus of claim 16, 17, 18, or 21, wherein the dose indicator rotates back to an initial position as an ejection is being completed.

23. The apparatus of claim 22, wherein the dose indicator barrel is integral with the dose setting member.

24. The apparatus of claim 16, wherein the dose indicator barrel or the dose setting member is threadedly engaged with an element fixed to the housing portion.

25. The apparatus of claim 16, wherein the latch member moves axially to release the drive member.

26. The apparatus of claim 16, or 20, wherein the dose setting member may be separated from the drive member by relative axial movement between the two.

27. The injection device of claim 26, wherein axial movement of the display member does not cause the spring to work outside as substantially linear working range.

28. A dose setting and injecting mechanism for an injection device, the mechanism comprising:

a rotatable dose setting member being rotatable over more than one revolution;

a dose indicator barrel that has a helical scale of numerals disposed thereon, the dose indicator barrel translating axially when rotated;

a threaded non-rotating piston rod, the piston rod being driveable in a distal direction to expel a dose of medication;

a rotatable but axially fixed drive member containing a thread that engages the thread on the piston rod;

a torsional spring for storing energy needed to expel a dose of medication, the torsional spring being helical, the torsional spring being operable connected to the dose setting member so that when a dose is dialed up energy for ejecting medication is stored in the spring;

a ratchet mechanism coupling the dose setting member with the drive member and allowing the dose setting member to be rotated over more than one revolution in a dose setting direction and to be rotated in a dose reducing direction without rotating the drive member, wherein the ratchet mechanism provides sufficient force to prevent the dose setting member from counter rotating under the influence of a force from the torsional spring;

a releasable lock that prevents rotation of the drive member until it is released, thereby allowing the torsional spring to remain strained until it is released when performing an ejection; and

wherein upon release of the lock, energy from the spring drives the drive member to rotate which drives the piston rod in a distal direction and simultaneously the dose indicator barrel is rotated to an initial position so that upon completion of the expulsion of the dose another dose can immediately be set and ejected.

29. An injection device comprising:

a rotatable dose setting member being rotatable over more than one revolution;

a dose indicator barrel that has a helical scale of numerals disposed thereon, the dose indicator barrel translating axially when rotated;

a threaded non-rotating piston rod, the piston rod being driveable in a distal direction to expel a dose of medication;

a rotatable but axially fixed drive member containing a thread that engages the thread on the piston rod;

a torsional spring for storing energy needed to expel a dose of medication, the torsional spring being helical, the torsional spring being operable connected to the dose setting member so that when a dose is dialed up energy for ejecting medication is stored in the spring;

a coupling mechanism connecting the dose setting member with the drive member and allowing the dose setting member to be rotated over more than one revolution in a dose setting direction and to be rotated in a dose reducing direction without rotation of the drive member, wherein the coupling mechanism provides sufficient force to prevent the dose setting member from counter rotating under the influence of a force from the torsional spring;

a releasable lock that prevents rotation of the drive member until it is released; and

wherein upon release of the lock, energy from the spring drives the drive member to rotate which drives the piston rod in a distal direction and simultaneously the dose indicator barrel is rotated toward an initial position so that upon completion of the expulsion of the dose another dose can immediately be set and injected; and

wherein the torsional spring operates over a substantially linear working range.

30. The injection device of claim 29, wherein the torsional spring is operably coupled at one end to a housing and is operably coupled to the dose setting member at another end and wherein the coupling mechanism allows the spring to be wound during dose setting and retains the spring in a strained position, and wherein the coupling mechanism allows the spring to be unwound during ejection of a dose by allowing it to rotate the drive member and wherein prior to ejection the coupling mechanism allows the resetting or reduction of a dose by allowing the dose setting member to be dialed down.