Medical device
First Claim
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1. A medical device comprising:
- a dose delivery mechanism comprising a piston rod, the piston rod having a screw thread being located a first distance near a piston and a further screw thread located at a second distance from the piston, where the second distance is greater than the first distance and the piston rod rotates during dose delivery;
a lock nut and a piston rod nut of the mechanism, where one of the lock nut or the piston rod nut is threadedly engaged with the piston rod;
a coupling device configured to cause the lock nut and the piston rod nut to engage each other to prevent relative rotation between them;
a spring arranged in contact with at least one of the lock nut and the piston rod nut and tending to engage or disengage the lock nut and the piston rod nut; and
the spring being a wave spring or wave washer.
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Abstract
The medical device comprises a wave spring or wave washer in a mechanism to engage or disengage a first element and a second element. The invention also discloses the use of a multiple wave spring or wave washer comprising at least two waved spring layers in a medical device.
9 Citations
12 Claims
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1. A medical device comprising:
- a dose delivery mechanism comprising a piston rod, the piston rod having a screw thread being located a first distance near a piston and a further screw thread located at a second distance from the piston, where the second distance is greater than the first distance and the piston rod rotates during dose delivery;
a lock nut and a piston rod nut of the mechanism, where one of the lock nut or the piston rod nut is threadedly engaged with the piston rod;
a coupling device configured to cause the lock nut and the piston rod nut to engage each other to prevent relative rotation between them;
a spring arranged in contact with at least one of the lock nut and the piston rod nut and tending to engage or disengage the lock nut and the piston rod nut; and
the spring being a wave spring or wave washer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- a dose delivery mechanism comprising a piston rod, the piston rod having a screw thread being located a first distance near a piston and a further screw thread located at a second distance from the piston, where the second distance is greater than the first distance and the piston rod rotates during dose delivery;
Specification