Auto-injector with a torsion spring

Patent metadata

Field	Value
Publication number	US-9636467-B2
Application number	US-201113579455-A
Country	US
Kind code	B2
Filing date	Feb 16, 2011
Priority date	Feb 18, 2010
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

An auto-injector for administering a dose of a liquid medicament includes an elongate housing that contains a syringe with a hollow needle and a bung for sealing the syringe and displacing the medicament. The housing has distal and proximal ends with an orifice to be applied to an injection site. A spring mechanism, upon activation, pushes the needle from a covered position inside the housing into an advanced position through the orifice. The spring mechanism also operates the syringe to supply the dose of medicament. An activating mechanism is arranged to lock the spring mechanism in a pressurized state prior and to release the spring mechanism upon manual operation. The spring mechanism includes a torsion spring ground at one end in the housing and in a gear member on the other end. The gear member is rotatable to move another gear member to push the bung towards the proximal end.

First claim

The invention claimed is:

1. An auto-injector for administering a dose of a liquid medicament (M), comprising:
an elongate housing arranged to contain a syringe with a hollow needle and a bung for sealing the syringe and displacing the medicament (M), the elongate housing having a distal end (D) and a proximal end (P) with an orifice intended to be applied against an injection site, wherein the syringe is slidably arranged with respect to the housing,
a spring mechanism capable of, upon activation, pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end (P) as well as operating the syringe to supply the dose of medicament (M),
an activating mechanism arranged to lock the spring mechanism in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring mechanism for injection,
wherein the spring mechanism is a torsion spring grounded at one end in the housing and at the other end in a first gear member rotatable about a longitudinal axis but axially fixed, wherein the first gear member, upon rotation, is arranged for translatively moving a second gear member, the second gear member being prevented from rotating relative to the housing and coupled to the bung in order to push it towards the proximal end (P), wherein the first gear member is engaged with the activating mechanism prior to manual operation in a manner to prevent rotation and disengaged from the activating mechanism upon manual operation, wherein an essentially tube-shaped needle shroud is arranged around the syringe in the housing, the needle shroud slidable between at least a retracted position with the needle shroud almost hidden inside the housing and an advanced position with the needle shroud protruding from the proximal end (P) and covering the hollow needle in an advanced position of the hollow needle, wherein the needle shroud is biased by a second spring mechanism towards the advanced position, wherein the needle shroud is locked in the retracted position by a locking mechanism which is releasable by rotary movement transmitted from the first gear member through a clutch mechanism which is engaged by the second gear member shortly before the second gear member is fully advanced during an injection stroke.

2. The auto-injector according to claim 1 , further comprising an interlock mechanism arranged for locking the activating mechanism and preventing it from being manually operated, wherein the interlock mechanism is coupled to the needle shroud, wherein the interlock mechanism is releasable by pushing the needle shroud a small distance into the housing from the needle shroud's retracted position.

3. The auto-injector according to claim 2 , wherein the interlock mechanism comprises respective catches provided at the needle shroud and the trigger button.

4. The auto-injector according to claim 1 , wherein the activating mechanism is a trigger button, laterally arranged at the housing and operable by being pressed transversally with respect to the longitudinal axis.

5. The auto-injector according to claim 4 , wherein the trigger button has a locking pin engageable with at least one dog tooth provided at the first gear member for preventing rotation thereof in order to lock the spring mechanism in a pressurized state of the spring mechanism.

6. The auto-injector according to claim 1 , wherein the locking mechanism has the shape of a bayonet fit between the needle shroud and an outer rear tube arranged around the torsion spring, wherein the needle shroud is guided in the housing in a manner to prevent relative rotation and wherein the outer rear tube is coupled to the clutch mechanism, wherein the bayonet fit comprises a bayonet pin arranged at one of the outer rear tube or the needle shroud and a pin track arranged in the other one of the outer rear tube or the needle shroud.

7. The auto-injector according to claim 1 , wherein the second gear member is a piston rod having an external lead screw thread, the piston rod having an axial bore for slidably arranging the piston rod on a shaft attached to the housing, the axial bore and the shaft having corresponding non-circular profiles, wherein the first gear member is a lead nut engaged with the external lead screw thread.

8. The auto-injector according to claim 7 , wherein the external lead screw thread has a variable pitch.

9. The auto-injector according to claim 7 , wherein the lead nut is provided with at least one pin or with a ball bearing for engaging the external lead screw thread.

10. The auto-injector according to claim 1 , wherein the syringe is arranged in a syringe carrier and supported by the syringe carrier at a proximal end, wherein the syringe carrier is slidably arranged in the needle shroud and wherein an abutment is provided in the needle shroud defining a maximum forward position of the syringe earner.

11. The auto-injector according to claim 1 , wherein the clutch mechanism comprises a circumferential shoulder arranged at the second gear member and at least one resilient clutch finger with a respective inclined inner surface arranged at a distal end of the first gear member, the shoulder arranged for increasingly pressing against the inclined surface thereby flexing the clutch fingers outward near the end of an injection stroke, wherein the clutch mechanism further comprises an inner rear tube arranged around the clutch fingers inside the torsion spring and attached to the outer rear tube at their distal ends, the inner rear tube having a number of internal longitudinal splines for engaging the flexed-out clutch fingers.

12. The auto-injector according to claim 11 , wherein the internal longitudinal splines are arranged in a manner to form a ratchet when engaged with the clutch fingers.

13. The auto-injector according to claim 1 , wherein a locking mechanism is provided for locking the needle shroud in an advanced position of the needle shroud.

14. The auto-injector according to claim 1 , wherein at least one viewing window for inspecting the syringe is provided in the housing.

15. An auto-injector for administering a dose of a liquid medicament (M), comprising:
an elongate housing arranged to contain a syringe with a hollow needle and a bung for sealing the syringe and displacing the medicament (M), the elongate housing having a distal end (D) and a proximal end (P) with an orifice intended to be applied against an injection site, wherein the syringe is slidably arranged with respect to the housing,
a spring mechanism capable of, upon activation, pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end (P) as well as operating the syringe to supply the dose of medicament (M),
an activating mechanism arranged to lock the spring mechanism in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring mechanism for injection,
wherein the spring mechanism is a torsion spring grounded at one end in the housing and at the other end in a first gear member rotatable about a longitudinal axis but axially fixed, wherein the first gear member, upon rotation, is arranged for translatively moving a second gear member, the second gear member being prevented from rotating relative to the housing and coupled to the bung in order to push it towards the proximal end (P), wherein the first gear member is engaged with the activating mechanism prior to manual operation in a manner to prevent rotation and disengaged from the activating mechanism upon manual operation, wherein a

Assignees

• Ekman Matthew
• Barrow-Williams Timothy Donald
• Hourmand Yannick
• Sanofi Aventis Deutschland

Inventors

• Ekman Matthew
• Barrow-Williams Timothy Donald
• Hourmand Yannick

Classifications

• A61M2205/581

  by audible feedback · CPC title

• A61M5/2033 Primary

  Spring-loaded one-shot injectors with or without automatic needle insertion (multishot dosing syringes A61M5/31525, needle insertion only A61M5/3287) · CPC title

• A61M2005/206

  With automatic needle insertion · CPC title

• A61M5/3257 Primary

  Semi-automatic sleeve extension, i.e. in which triggering of the sleeve extension requires a deliberate action by the user, e.g. manual release of spring-biased extension means · CPC title

• A61M5/31583

  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 title