Automatic injection device with torsional spring
First Claim
Patent Images
1. A fixed dose injection device comprising the following in combination,a. a housing;
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that corresponds to only one predetermined fixed dose of medicament, where the rotatable gear is fixed axially in the housing;
ii. a plunger threadedly engaged with the rotatable gear having a pitch β
that is matched with angle α
so that the plunger moves distally during dose delivery a distance corresponding to the only one predetermined fixed dose;
iii. a torsional spring, and a drive shaft wherein the torsional spring rotates the drive shaft back to a zero position if the drive shaft is rotated by an angle smaller than α
during dose dialing such that dialing doses smaller than the only one predetermined fixed dose is prevented;
iv. a trigger connected to the rotatable gear such that when the trigger is activated the torsional spring unwinds and causes the rotatable gear to rotate through angle α and
to move the plunger distally to deliver the only one predetermined fixed dose; and
v. a rotation stop that limits the rotation of the drive shaft, allowing a rotation beyond one tooth and preventing a rotation beyond more than one tooth of the rotatable gear such that setting a dose exceeding the only one predetermined fixed dose is prevented.
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Accused Products
Abstract
A semi-automatic “fixed” dose injection device is disclosed containing a reservoir of medicament, where a trigger controls the unwinding of a torsional spring to cause a predetermined injection of medicament from the reservoir through a disposable needle.
32 Citations
9 Claims
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1. A fixed dose injection device comprising the following in combination,
a. a housing; - and
b. a dose setting and injecting assembly comprising, i. a rotatable gear having only at least two teeth offset from each other at an angle α
that corresponds to only one predetermined fixed dose of medicament, where the rotatable gear is fixed axially in the housing;ii. a plunger threadedly engaged with the rotatable gear having a pitch β
that is matched with angle α
so that the plunger moves distally during dose delivery a distance corresponding to the only one predetermined fixed dose;iii. a torsional spring, and a drive shaft wherein the torsional spring rotates the drive shaft back to a zero position if the drive shaft is rotated by an angle smaller than α
during dose dialing such that dialing doses smaller than the only one predetermined fixed dose is prevented;iv. a trigger connected to the rotatable gear such that when the trigger is activated the torsional spring unwinds and causes the rotatable gear to rotate through angle α and
to move the plunger distally to deliver the only one predetermined fixed dose; andv. a rotation stop that limits the rotation of the drive shaft, allowing a rotation beyond one tooth and preventing a rotation beyond more than one tooth of the rotatable gear such that setting a dose exceeding the only one predetermined fixed dose is prevented. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fixed dose injection device comprising the following in combination,
a. a housing comprising a removable cartridge holder configured to contain a cartridge of medicament; - and
b. a dose setting and injecting assembly comprising, i. a rotatable gear having only two teeth offset from each other at an angle α
that corresponds to only one predetermined fixed dose of medicament, where the rotatable gear is fixed axially in the housing;ii. a plunger threadedly engaged with the rotatable gear having a pitch β
that is matched with angle α
so that the plunger moves distally during dose delivery a distance corresponding to the predetermined fixed dose;iii. a torsional spring, and a drive shaft wherein the torsional spring rotates the drive shaft back to a zero position if the drive shaft is rotated by an angle smaller than α
;iv. a trigger connected to the rotatable gear such that when the trigger is activated the torsional spring unwinds and causes the rotatable gear to rotate through angle α and
to move the plunger distally to deliver the predetermined fixed dose;and vi. a reset dial configured to prevent rotation of the plunger and to allow the plunger to be retracted proximally into the housing when the cartridge holder is removed.
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9. A fixed dose titration injection device comprising the following in combination,
a. a housing comprising a removable cartridge holder configured to contain a cartridge of medicament; - and
b. a dose setting and injecting assembly comprising, i. a rotatable gear having only a first, a second, and a third tooth offset from each other at an angle α
that corresponds to only one predetermined fixed dose of medicament such that only three injections of medicament can be performed using the cartridge of medicament, where the rotatable gear is fixed axially in the housing;ii. a drive shaft having a ratchet arm that is configured to engage either the first, the second or the third tooth during dose setting; iii. a plunger threadedly engaged with the rotatable gear having a pitch β
that is matched with angle α
so that the plunger moves distally during dose delivery a distance corresponding to one or more multiples of the predetermined fixed dose;iv. a torsional spring wherein the torsional spring rotates the drive shaft back until the ratchet arm engages at the next gear tooth, corresponding to the next lower dose, if a dose is dialed in between two fixed titration doses; and v. a trigger connected to the rotatable gear such that when the trigger is activated the torsional spring unwinds and causes the rotatable gear to rotate through one or more multiples of angle α and
to move the plunger distally to deliver the one or more multiples of the predetermined fixed dose,and vii. a reset dial configured to prevent rotation of the plunger and to allow the plunger to be retracted proximally into the housing when the cartridge holder is removed.
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Specification