Injection device

• US 6,663,602 B2
• Filed: 06/14/2001
• Issued: 12/16/2003
• Est. Priority Date: 06/16/2000
• Status: Expired due to Term

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Møller, Claus Schmidt
• Primary Examiner(s): Casler, Brian L.
• Assistant Examiner(s): RODRIGUEZ, CRIS LOIREN
• Application Number:
  US09/882,536
• Publication Number:
  US 20020052578A1
• Time in Patent Office: 915 Days
• Field of Search: 604/207-211, 604/232, 604/218, 604/234, 604/131-136, 604/139, 604/187, 604/181, 222/46-48, 222/16, 222/18, 222/282, 222/283, 222/309, 222/310, 222/325, 222/326, 222/336, 222/386, 222/390
• US Class Current: 604/211
• CPC Class Codes: A61M 2005/3152 including gearings to multiply or attenuate the piston displacing force
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 5/24 Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or carpules, e.g. automatic ampoules or carpules A61J1/06
• CPC Class Codes: A61M 5/28 Syringe ampoules or carpules, i.e. ampoules or carpules provided with a needle
• CPC Class Codes: A61M 5/315 Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
• CPC Class Codes: A61M 5/31541 Means preventing setting of a dose beyond the amount remaining in the cartridge
• 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 5/31551 including axial movement of dose setting member
• CPC Class Codes: A61M 5/31558 using scaling up or down transmissions, e.g. gearbox
• CPC Class Codes: A61M 5/31575 using scaling up or down transmissions, e.g. gearbox
• CPC Class Codes: A61M 5/3158 performed by axially moving actuator operated by user, e.g. an injection button

Abstract

An injection device for injection of set does of medicine from a cartridge has a nut that is screwed up along a threaded piston rod during a dose setting operation. The nut is screwed along the piston rod by rotating a dose setting drum. An injection button is coupled to the piston rod with a gear wheel transmission. Axial movement of the injection button causes a corresponding axial movement of the piston rod until the nut engages an abutment in the housing.

Claims

1. An injection device comprising:

a. a housing having a proximal end and a distal end;

b. a threaded piston rod having a first pitch, the piston rod being linearly displaceable in the housing but being rotatably fixed with respect to the housing;

c. a displaceable nut that moves relative to the housing, the nut engaging the thread of the piston rod so that the nut can screw along the thread of the piston rod, thereby being capable of moving along the piston rod in proximal direction from a first position on the piston rod to a second position on the piston rod, the displacement of the nut along the piston rod in a proximal direction defining a quantity of medication to be injected by the injection device,

d. a dose setting drum having an injection button disposed on an end thereof, the drum having a threaded surface with a second pitch, the dose setting drum engaging the housing and rotatable within the housing so that it may be screwed outward from the proximal end of the housing;

e. a gear box assembly coupling axial movement of the injection button with axial movement of the nut, the gear box providing a gearing having a ratio corresponding to the ratio of the second pitch to the first pitch.

2. The injection device of claim 1, wherein the gear box assembly that couples axial movement of the injection button with the nut comprises:

a. at least one gear wheel carried by a connector that projects from the gear box assembly, the connector being longitudinally displaceable but non-rotatable with respect to the gearbox and being integral with the nut;

b. a first rack that is integral with a first element of the gearbox, the first element being rotatable but not longitudinally displaceable relative to the housing;

c. a second gear box element carrying a second rack projecting from the gearbox, the second rack being longitudinally displaceable but non-rotatable with respect to the first element and being coupled to the injection button to follow longitudinal movement of the button; and

d. wherein the at least one gear wheel engages the first and second racksand is dimensioned to provide a gearing by which longitudinal movement of the second rack is transformed into longitudinal movement of the connector with a gearing ratio for the longitudinal movements of the second rack and connector relative to the housing being in the ratio of the second pitch to the first pitch.

3. The injection device of claim 2, wherein the gearing ratio is 2:

1.

4. The injection device of claim 2, wherein the piston rod has a stop.

5. An injection device comprising:

a. a housing having a proximal end and a distal end;

b. a linearly displaceable dose setting member protruding from the proximal end of the housing, the dose setting member having a proximal end adapted for receiving an axial force from a finger of a person administering an injection with the device, the dose setting member also having a threaded surface with a pitch P1, the dose setting member being linearly displaceable as a result of rotation of the member relative to the housing;

c. a non-rotating threaded piston rod, the piston rod residing, at least partially, within the housing and a portion of the piston rod extending distally from the distal end of the housing, the piston rod being threaded and having a pitch P2;

d. a threaded nut that screws along the piston rod, the nut being linearly displaceable in a proximal direction from a first position where it abuts a stop in the distal end of the housing, the nut being rotationally coupled to the dose setting member so that rotation of the dose setting member causes the nut to screw along the piston rod;

e. a gearbox coupling axial movement of the dose setting member in a proximal direction with axial movement of the nut in a proximal direction, the gearbox having a gearing such that the ratio of movement of the dose setting element to movement of the nut is the same as the ratio of P2 to P1; and

f. a means for preventing rotation of the nut relative to the piston rod when a force is exerted on the proximal end of the dose setting member.

6. The device of claim 5, wherein the ratio of P2 to P1 is approximately 2:

1.

7. The device of claim 5, wherein the gearing ratio is at least 2:

1.

8. The device of claim 7, wherein the piston rod has a stop.

9. The device of claim 7, wherein gear box assembly comprises:

a housing, a first rack coupled to the injection button and a second rack that is integral with the gearbox housing, a gear wheel that can roll along the racks, a gear wheel carrying element that is coupled to the gear wheel at one end and the nut at another end, and wherein the first and second racks are coupled by the gear wheel.

10. The injection device of claim 9, wherein the gearbox assembly is axially fixed with respect to the housing.

11. An injection device comprising:

a. a housing for a dose setting and injecting mechanism, the housing having a proximal end and a distal end;

b. a rotatable linearly displaceable dose setting member having a proximal end on which an injection button is mounted;

c. a threaded piston rod, the piston rod being rotationally fixed but axially displaceable;

d. a nut that screws along the piston rod in a proximal direction from a first position, the nut being rotatably coupled to the dose setting member so that rotation of the nut corresponds to axial displacement of the dose setting member;

e. a linear force coupling means for coupling linear force exerted on the injection button, wherein the force exerted on the nut is greater than the force exerted on the injection button; and

f. a means for preventing rotation of the nut when linear force is exerted on the injection button.

12. The device of claim 11, wherein the linear force coupling means comprises a gearing that couples axial movement of the injection button to the nut without causing rotation of the nut.

13. The device of claim 11, wherein the coupling means comprises a first rack that is coupled to the injection button and a second rack and a gear assembly coupling the first rack to the second rack.

14. The injection of claim 11, wherein the gearbox is free to rotate within the housing.

15. An injection device comprising:

a. a housing having a proximal end;

b. a non-rotatable threaded piston rod;

c. a nut that screws along the piston rod in a proximal direction from a defined position;

d. a dose setting member protruding from the proximal end of the housing and having injection button located on a proximal end thereof, the injection button adapted to receive a linear force;

e. a gear box assembly disposed within the housing, the gear box assembly coupling axial motion of the injection button with axial motion of the nut without causing rotation of the nut, thereby driving the piston rod in a distal direction when the injection button is moved distally; and

f. wherein the gear box assembly causes the force exerted on the piston rod nut to be greater than the force exerted on the injection button.

16. The injection device of claim 15, wherein the force exerted on the piston rod is approximately at least twice that of the force exerted on the injection button.