| US 7,553,299 B2 | ||
| Drive mechanisms suitable for use in drug delivery devices | ||
| Robert Frederick Veasey, Leamington Spa (United Kingdom); Christopher Nigel Langley, Leamington Spa (United Kingdom); and Steven Wimpenny, Leamington Spa (United Kingdom) | ||
| Assigned to DCA Design International Ltd., Warwick (United Kingdom) | ||
| Filed on Mar. 02, 2004, as Appl. No. 10/790,024. | ||
| Claims priority of application No. 0304823.8 (GB), filed on Mar. 03, 2003. | ||
| Prior Publication US 2004/0267207 A1, Dec. 30, 2004 | ||
| Int. Cl. A61M 5/00 (2006.01) | ||
| U.S. Cl. 604—208 [604/207] | 18 Claims |
| 1. A drive mechanism for use in a drug delivery device comprising:
a housing having an internal and an external thread;
a piston rod having a non-circular cross section, and which is threadedly engaged with the internal thread of the housing;
a unidirectional coupling located between the housing and the piston rod;
a dose dial sleeve, which is threadedly engaged with the external thread of the housing and being rotatable with respect to
the housing;
a drive sleeve, located between the housing and the piston rod, which is axially displaceable but not rotatable with respect
to the piston rod; and
a clutch means located between the drive sleeve and the dose dial sleeve, which
a) when the dose dial sleeve and the drive sleeve are de-coupled by the clutch means, rotation of said dose dial sleeve with
respect to the drive sleeve is allowed; and
b) when the dose dial sleeve and the drive sleeve are coupled by the clutch means, rotation of the dose dial sleeve with respect
to the said drive sleeve is prevented.
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