Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2002-03-21
2004-12-07
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S156000
Reexamination Certificate
active
06827708
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Techinical Field
The invention relates to a device for administering an injectable product in doses.
2. Description of the Related Art
A device such as the invention relates to is known for example from WO 97/36626. The device comprises a casing having a reservoir for the product. A piston is accommodated in the reservoir, said piston forcing product out of the reservoir when moved in a feed direction towards an outlet of the reservoir. A gear rack which presses against the piston moves the piston in the feed direction. The gear rack is provided with rows of teeth. A drive member is further accommodated in the casing, shiftable in and counter to the feed direction relative to the casing, said drive member slaving the gear rack when moved in the feed direction. To this end, the drive member meshes with the rows of teeth of the gear rack via slaving means. To set the amount of product administered in one stroke, the drive member in a front position is manually retracted counter to the feed direction by a set dosage path length. In this way, the slaving means of the drive member slide over the teeth of the rows of teeth and give elastically. The gear rack is prevented from moving back by blocking means accommodated unshiftably relative to the casing. The blocking means co-operate with one of the rows of teeth of the gear rack, such that the blocking means prevent the gear rack from moving counter to the feed direction and allow the gear rack to move in the feed direction by elastically giving.
Correctly and precisely dosing the injectable product is of great importance. Above all in medical technology, the success of a treatment is heavily dependent on correctly dosing the medicine. Precise dosing requires a fine pitch of the previously described gear rack, with small teeth. Moreover, the rows of teeth of a gear rack must satisfy the heavy demands of production
SUMMARY OF THE INVENTION
It is the object of the invention to realize a device for administering an injectable product in doses, having simpler components for at least the same functionality.
A device for administering an injectable product in doses comprises a casing having a reservoir for the product, a piston which forces product out of the reservoir when moved in a feed direction towards an outlet of the reservoir, a driven rod which moves the piston in the feed direction, a drive member which may be moved in and counter to the feed direction relative to the casing, said drive member slaving the driven rod when moved in the feed direction, and at least one blocking means which co-operates with the driven rod, such that the blocking means prevents the driven rod from moving counter to the feed direction relative to the casing and allows the driven rod to move in the feed direction.
In accordance with the invention, the driven rod is prevented from moving counter to the feed direction by self-locking. There is a friction lock between the blocking means and the driven rod or a friction lock between the blocking means and the casing. When the driven rod is moved in the feed direction, only the friction lock is overcome. Moving the driven rod counter to the feed direction generates the self-locking of the device via the friction lock, and leads to a friction force which increases with movement of the driven rod counter to the feed direction. A moving force of the driven rod counter to the feed direction thus causes, due to the self-locking of the blocking means, a friction force opposing this moving force which is at least as great. The driven rod can be an easily produced rod made of full material. The use of an internally hollow rod is also possible. A round rod is preferably used. A cornered rod can, however, also be used. The demands of production precision are not heavy. The production costs for such a rod are comparatively low. The term “rod” in the sense of the invention, however, includes in principle any structure extending in the feed direction which is suitable for transmitting the drive force and absorbing the friction force.
If the driven rod is moved in the feed direction, the friction force existing between the blocking means and the driven rod is overcome. Given a preferably unvarying distance between the driven rod and the casing, the blocking means is not tensed further. The force for moving the driven rod in the feed direction remains constantly low. The blocking means does not block the driven rod against relative movement in the feed direction. The driven rod is able to slide past it.
A spring force is preferably used to generate the friction lock between the blocking means and the driven rod or the blocking means and the casing. The spring force can be transmitted via moving parts of the blocking means onto the point of the friction lock, for example by means of a wedge effect via a plane at an angle to the feed direction. One or more annular spiral springs may for example be used, which press one or more tilting elements distributed evenly around the driven rod against the driven rod or the casing. Springs running radially towards the driven rod or the casing at an angle, which generate the friction lock via pressure parts, would also be conceivable.
Particularly preferably, the blocking means comprises at least one spiral spring or leaf spring. When installed, this spring is deflected from its untensed neutral position and is under bending stress. The friction lock is permanently maintained. The spring can consist of metal, plastic or another suitable material or combination of materials. The spring preferably acts directly on the driven rod or the casing. Particularly preferably, the spiral spring or leaf spring form the blocking means alone.
A spring of the blocking means, or the blocking means as such if it is formed by a spring alone, is arranged in the device such that, due to the friction lock, the blocking means is immediately tensed so heavily between the casing and the driven rod when the driven rod is retracted, that in practice it is not possible to noticeably retract the driven rod in the first place. This is preferably achieved by a form and arrangement of the blocking means which are such that a force acting on the blocking means at the point of the friction lock and counter to the feed direction strives to strain the blocking means perpendicularly to the feed direction. If a force is applied to the driven rod counter to the feed direction, a tendency to move together with the driven rod counter to the feed direction into its untensed neutral position is transmitted onto the blocking means via the friction lock. However, it is not possible for the blocking means to simply return to its neutral position, since in its untensed state the blocking means would protrude out from its fixing point across the distance between the casing and the driven rod. A parallel movement of the side of the blocking means abutting the driven rod or the casing could be achieved by shortening the blocking means in its longitudinal direction. However, this is not possible, since a sufficient rigidity of the blocking means against buckling and straining is ensured. In this state, the blocking means clamps between the driven rod and the casing and thus blocks the driven rod against moving counter to the feed direction. In this way, the clamping force forming the friction lock between the blocking means and the driven rod increases superproportionally with a force acting on the driven rod counter to the feed direction. Movement of the driven rod counter to the feed direction is prevented by self-locking.
In a first preferred embodiment, the blocking means is fixed in the casing or at least connected to it unshiftably in the axial direction. To this end, the blocking means is fixed on one side such that movement relative to the fixing, in or counter to the feed direction, is prevented. The blocking means can be stuck on or shrunk on, however it preferably sits in a groove or other recess. It protrudes via another side in a radial direction towards the driven rod. When installed, the
Disetronic Services AG
Dorsey & Whitney LLP
Mendez Manuel
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