Drive mechanism and drug delivery device herewith
First Claim
1. A drive mechanism for a drug delivery device, the mechanism comprising a spring driven rotatable drive member, a rotatable driven member, a clutch rotationally coupling the driven member and the drive member into a coupled state and allowing relative clockwise and anti-clockwise rotation between the driven member and the drive member when in a decoupled state, and a spring biasing the clutch into the coupled state and allowing relative axial movement between the drive member and the driven member into the decoupled state of the clutch against the bias of the spring, wherein the clutch comprises a first ring of crown teeth on the drive member and a second ring of corresponding crown teeth on the driven member with each crown tooth having in the clockwise and the anti-clockwise direction different ramped tooth angles such that the teeth are allowed to override each other in the de-coupled state of the clutch with a different resistance in the clockwise and the anti-clockwise direction, wherein the drive member is formed of polybutylene terephthalate (PBT), polyoxymethylene (POM), or polycarbonate (PC) and the rotatable driven member is formed of PBT, POM or PC, and a coefficient of friction (μ
- ) between the teeth on the drive member and the teeth on the driven member is between 0.05 and 0.3, and the teeth on the drive member and the teeth on the driven member have a surface roughness (Ra) of 0.2≤
Ra≤
10 micrometers.
1 Assignment
0 Petitions
Accused Products
Abstract
The present disclosure relates to a drive mechanism which is suitable for an injection device, especially a pen type drug delivery device and to such a drug delivery device. The mechanism comprises a spring driven rotatable drive member, a rotatable driven member, a clutch rotationally coupling the driven member and the drive member in a coupled state and allowing relative clockwise and anti-clockwise rotation between the driven member and the drive member in a decoupled state, and a spring biasing the clutch into its coupled state and allowing relative axial movement between the drive member and the driven member into the decoupled state of the clutch against the bias of the spring. The clutch comprises a first ring of crown teeth on the drive member and a second ring of corresponding crown teeth on the driven member with each crown tooth having in the clockwise and the anti-clockwise direction different ramped tooth angles such that the teeth are allowed to override each other in the de-coupled state of the clutch with a different resistance in the clockwise and the anti-clockwise direction.
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Citations
16 Claims
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1. A drive mechanism for a drug delivery device, the mechanism comprising a spring driven rotatable drive member, a rotatable driven member, a clutch rotationally coupling the driven member and the drive member into a coupled state and allowing relative clockwise and anti-clockwise rotation between the driven member and the drive member when in a decoupled state, and a spring biasing the clutch into the coupled state and allowing relative axial movement between the drive member and the driven member into the decoupled state of the clutch against the bias of the spring, wherein the clutch comprises a first ring of crown teeth on the drive member and a second ring of corresponding crown teeth on the driven member with each crown tooth having in the clockwise and the anti-clockwise direction different ramped tooth angles such that the teeth are allowed to override each other in the de-coupled state of the clutch with a different resistance in the clockwise and the anti-clockwise direction, wherein the drive member is formed of polybutylene terephthalate (PBT), polyoxymethylene (POM), or polycarbonate (PC) and the rotatable driven member is formed of PBT, POM or PC, and a coefficient of friction (μ
- ) between the teeth on the drive member and the teeth on the driven member is between 0.05 and 0.3, and the teeth on the drive member and the teeth on the driven member have a surface roughness (Ra) of 0.2≤
Ra≤
10 micrometers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- ) between the teeth on the drive member and the teeth on the driven member is between 0.05 and 0.3, and the teeth on the drive member and the teeth on the driven member have a surface roughness (Ra) of 0.2≤
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11. A drug delivery device for selecting and dispensing a number of user variable doses of a medicament, the drug delivery device comprising:
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a drive mechanism comprising a spring driven rotatable drive member, a rotatable driven member, a clutch rotationally coupling the driven member and the drive member into a coupled state and allowing relative clockwise and anti-clockwise rotation between the driven member and the drive member when in a decoupled state, and a spring biasing the clutch into the coupled state and allowing relative axial movement between the drive member and the driven member into the decoupled state of the clutch against the bias of the spring, wherein the clutch comprises a first ring of crown teeth on the drive member and a second ring of corresponding crown teeth on the driven member with each crown tooth having in the clockwise and the anti-clockwise direction different ramped tooth angles such that the teeth are allowed to override each other in the de-coupled state of the clutch with a different resistance in the clockwise and the anti-clockwise direction, wherein the drive member is formed of polybutylene terephthalate (PBT), polyoxymethylene (POM), or polycarbonate (PC) and the rotatable driven member is formed of PBT, POM or PC, and a coefficient of friction (μ
) between the teeth on the drive member and the teeth on the driven member is between 0.05 and 0.3, and the teeth on the drive member and the teeth on the driven member have a surface roughness (Ra) of 0.2≤
Ra≤
10 micrometers,a housing, a dose setting member located within the housing, and a piston rod engaging the driven member, wherein the drive member is operatively interposed between the driven member and the dose setting member. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification