MXPA99011271A

MXPA99011271A - A displacement device for controlled dispensing of a dose of a liquid contained in a cartridge

Info

Publication number: MXPA99011271A
Application number: MXPA/A/1999/011271A
Authority: MX
Inventors: Ljunggreen Henrik
Original assignee: Novo Nordisk A/S
Priority date: 1997-06-09
Filing date: 1999-12-06
Publication date: 2000-06-01

Abstract

The present invention relates to an improved displacement device (1) for controlled dispensing of a dose of a liquid contained in a cartridge (40), said displacement device (1) comprising a housing (5) incorporating:a means (6) for accommodating said cartridge (40), a manually activatable displaceable elongated dose dispensing means (20), said elongated dose dispensing means (20) having a first end part (22) extending to the exterior of the housing (5), an elongated piston rod (30) connected with a displaceable piston (32), said piston (32) being adapted to press out the liquid contained in said cartridge (40), and said elongated piston rod (30) having a plurality of transversely extending teeth (25) arranged along its length, a toothed displacing means (14), a user-operated dose setting means (8, 10, 12), said user-operated dose setting means (8, 10, 12) and said toothed displacing means (14) being operatively connected to cause movement of said toothed displacing means (14) in response to the operation of the dose setting means (8, 10, 12), pinion means (35) having a shaft (37), said pinion means (35) being rotatably secured to said elongated dose dispensing means (20), said pinion means (35) being arranged to engage the teeth of said toothed displacing means (14) and the teeth (25) of the piston rod (30).

Description

DISPLACEMENT DEVICE FOR THE CONTROLLED SUPPLY ^ OF A DOSE OF A LIQUID CONTAINED IN A CARTRIDGE DESCRIPTION OF THE INVENTION The present invention relates to displacement devices for controlled delivery of a dose of a liquid contained in a cartridge, in particular for use for the infusion of medicine, such as insulin for patients with diabetes, and comprising a housing that incorporates a medium to accommodate the cartridge, an elongated, displaceable and manually activatable dose delivery means having a first end portion extending into the housing, an elongated piston rod that is connected with a displaceable piston, the piston is adapted for eject by pressure the liquid contained in the cartridge. Such devices are well known in the art, see, for example, FR 2 572 288. Some of the known devices are cumbersome when used, and do not provide a means to allow the user to easily verify that the preset dose is in fact that It is supplied. Other known devices do not allow the readjustment of the dose when it has been established, which makes the devices impractical for their use. REF .: 32132 The invention seeks to provide an improvement of such devices where the required dose can be adjusted before delivery, and where the supply occurs using a simple and reliable means. The device according to the invention finds particular use in cartridges containing a dose corresponding to a plurality of consecutive cycles of dose adjustment and delivery. Using a simple means, the device also provides a clear indication of the current dose setting wherein the dose corresponds to the displacement of an elongated dose delivery means which is subsequently moved or manually pressed by the user to perform the delivery. Another additional advantage is that the dose can be adjusted to another value or can even be readjusted with a corresponding displacement of the dose delivery means, without the corresponding displacement leading to a liquid supply. The invention also provides a simple conversion mechanism which can convert the displacement of a dose delivery means into a displacement of the piston. The above advantages are obtained by means of a device as indicated in the opening paragraph, wherein the elongate piston rod is formed with a plurality of transversely extending teeth placed along its length, and incorporating: a means of toothed displacement, a means of adjusting the dose operated by the user, - - the dose adjusting means operated by the user and the toothed displacement means are operatively connected to cause the movement of the toothed displacement means in response to the operation of the dose adjusting means, a pinion means having a shaft the pinion means is rotatably attached to the elongated dose delivery means, the pinion means is positioned to engage the teeth of the toothed displacement means and the teeth of the piston rod. By adapting the dose adjustment means operated by the user and the toothed displacement means so that the latter moves by operation of the dose adjustment means, the toothed displacement means provides two functions, specifically to displace the adjustment means of dose through its movement during dose adjustment, and serve as a fixed cogged rack during delivery. According to a preferred embodiment, the toothed displacement means is formed as a screw means having a helical cord, the screw means being caused to rotate about its longitudinal axis in response to the operation of the dose adjustment means. The screw means provides the advantage that it is a self-locking member which has the function of a fixed toothed rack when the rotation is stopped. According to a further embodiment of the invention, the toothed traveling means can be formed as an endless, movable toothed rack, and a means is provided to allow the toothed rack to remain stationary during the delivery of a liquid dose. By forming the piston rod as a flexible member, considerable space saving can be obtained, leading to a more compact device. The device can advantageously be provided with at least one guide surface adapted to control the displacement of the dose delivery means. Preferably, a guide surface for coupling the shaft of the pinion means is adapted, and may have first and second end surfaces that limit the displacement of the dose delivery means. According to a preferred embodiment, the pinion means can be provided with a first and second sets of teeth, the first set of teeth engages with the teeth of the toothed displacement means, and the second set of teeth engages with the teeth of the piston rod. In this way, the displacement of the dose delivery means can be adapted to advance towards any desired displacement of the piston. The dose adjustment means operated by the user may further comprise an engine and a motor control means having a dose selection means, and the first end portion of the elongated and displaceable dose delivery means may be provided with marks that can be inspected by the user_indicating the established dose and can allow verification of the adjustment. The invention will now be described in greater detail with reference to the drawings which show a cross-sectional view of a currently preferred embodiment. In Figure 1, a device according to the invention for the infusion of a dose of medicine, such as insulin, is generally designated by the reference number 1 and comprises a housing 5. In the embodiment shown, the housing 5 it is formed with a generally rectangular cross-section and comprises an upper wall 2, a lower wall 2 ', side walls 3, 31 and end walls defining a chamber with housings for the various components of the device. The housing 5 is preferably shaped so as to allow the device 1 to be held by the user's hand during the delivery of liquid medicine from a cartridge 40 that fits within the housing near the lower wall 2 '. The cartridge 40 contains a predetermined amount of medicine corresponding to several subsequent infusions, and incorporates a piston 32 at its first end or upper end. The frictional engagement of the piston 32 with the cartridge 40 requires that some minimum pressure be applied in order to displace the piston 32 and supply a quantity of liquid. A wall portion (not shown) can be removed to provide access to the interior of the housing 5 when a new cartridge 40 is to be inserted to replace an empty one. The cartridge held at its lower end by a cartridge fixing member 6 positioned on the lower wall 2 ', which allows a needle 42 to be connected to the cartridge 40 for the purpose of medicine infusion. The device further comprises an elongated piston rod 30 which can be formed as a rigid member or as a flexible member, as described in WO 95/09021. The piston rod 30 is formed with a plurality of transversely extending teeth 25 or similar elements placed along its length, the teeth 25 being engageable by a pinion 35, as explained in more detail in the following. As shown, and when the cartridge 40 is placed inside the housing 5, the piston rod 30 is positioned so that it rests against the piston 32 of the cartridge 40.

With the reference numeral 20 there is shown an elongated and displaceable dose delivery means having a first end portion 22 extending into the interior of the housing 5 through the opening 7 which is provided in the upper wall 2 and the which provides support for the first end portion 22 preventing lateral movement. The dose delivery means 20 is positioned so that it is movable in a direction indicated by the arrow P. The end portion 22 provides an upper end surface against which the user of the device can manually press to deliver a dose of medicine pre-established, and is further provided with a graduated scale on a surface 21 for reasons which will be explained later. At its second end or lower end, the dose delivery means 20 is provided with the aforementioned pinion 35 connected thereto, by means of a shaft 37. The displacement of the dose delivery means 20 is controlled by means of a surface 9 of guide which can be formed as a recess or track placed on each of the end walls of the housing 5, and which are provided with an upper and lower surface 9 ', 9"that limit the movement of the medium 20 of dose delivery in any of the directions indicated by the arrow P. Preferably, the dose delivery means 20 engages the guide surface 9 by means of an extension of the pinion shaft 37. The pinion 35 is positioned to rotate with respect to the dose delivery means 20, the teeth of the pinion 35 are engaged with the teeth 25 of the piston rod 30 and also with a means 14 of toothed displacement, which is operatively connected to a means 8,10,12 of dose adjustment operated by the user which operates in the manner described below. Accordingly, the piston rod 30 and the toothed displacement means 14 provide a support for the lower end of the elongated dose delivery means 20, preventing its lateral movement. In the preferred embodiment, the toothed moving means 14 is formed as a screw means having a helical cord and is placed with its longitudinal axis extending perpendicularly to the axis of rotation of the pinion 35. The screw means 14 can be caused to rotate around its longitudinal axis in response to the operation of the medium 8, 10, 12 of dose adjustment. As will be apparent, rotation of the screw means 14 will cause rotation of the pinion 35. Due to the frictional engagement of the piston 32 with the cartridge 40, the piston rod 30 remains stationary, which causes the dose delivery means 20 it moves in a direction P, which depends on the direction of rotation of the screw means 14.

Further, in the preferred embodiment, the dose adjustment means operated by the user comprises a motor 12 and a motor control means 8 having a means 10 of dose selection. The motor 12 has an output shaft connected to the gearing means 14 which causes the latter to rotate as indicated above. When in use, the user selects a desired dose of medicine to be delivered by providing this information to the motor control means 8 via the dose selection means 10. The adjustment to zero, the shaft 37 of the pinion 35 bears against the lower surface 91 'of the guide surface 9. When the supply process is to start, the motor 12 is activated, which causes the rotation of the displacement means 14 corresponding to the selected dose. This "rotation" becomes an upward displacement in the dose delivery means 20, which causes its upper end surface to rise above the upper wall 2 of the housing 5, making the scale visible on the surface 21. The displacement of the dose delivery means 20 will depend on the gear ratio that is chosen and the adjustment of the dose selection means 10 can be verified by inspecting the scale on the surface 21 which is graduated according to the gear ratio chosen.

When the dose delivery means 20 has moved according to the desired dose, the motor 12 automatically stops and the device is ready to deliver the amount of medicine that is desired. If the user wants to change the dose, for example to inspect the scale, the motor control means 8 can be caused to readjust the device by rotating the screw means 14 in a given direction, leading to a corresponding additional displacement of the medium 20 of dose delivery. When supply is finally desired, the displacement means 14 is blocked preventing its movement so as to perform the operation of a fixed toothed rack and a needle 42 is inserted into the body of the user. By using the self-locking screw means having a helical cord, this situation is automatically achieved when the motor 12 is stopped. When the displacement means 14 is provided alternately, for example, by a driven movable rack. by motor, it may be necessary to provide a coupling means to immobilize the rack preventing its movement. When a downward pressure is subsequently applied by the user to the end portion 22 of the dose delivery means 20, the pinion 35 will rotate and move downward along the locked movement means 14 until "the shaft 37 reaches the The bottom surface 9 'of the guide surface 9. This movement becomes a simultaneous downward displacement of the piston rod 30 and the piston 32, so that the desired quantity of liquid is supplied. the "active" part of the piston rod 30, i.e. the teeth 25 engaging the pinion 35 during adjustment and dose delivery, travels from an area close to the piston 32 when the cartridge 40 is full, an area of the piston rod 30 near its free end when the cartridge 40 is empty.When one cartridge is to be replaced by another, the teeth 25 of the piston rod 30 can be decoupled from the pinion means 35, which e allows the piston rod 30 to move to the position shown in the drawing whereby it is possible to remove the empty cartridge. Alternatively, the dose delivery means 20 can be pushed into the housing such that the shaft 37 bears against the lower end surface 9"and prevents further downward movement of the dose delivery means 20, and can be made operate the displacement means 14 in an inverse manner, whereby the piston rod 30 is displaced. Subsequently the piston rod 30 bears against the piston of a new cartridge that is inserted into the housing 5, and the teeth 25 of the piston rod 30 engage with the pinion 35.

It should be noted that the upper end surface 9 'of the guide surface 9 provides a safeguard against inadvertent adjustment of a dose exceeding a maximum allowable dose. When the shaft 37 reaches the limit 9 'of the guide surface 9, an additional rotation of the screw means 14 leads to an immediate supply of liquid before the moment in which the needle 42 is inserted in the body of the user, thus which provides a visible warning. By varying the distance between the end surfaces 9 ', 9", it can be adapted to the device for different maximum allowed doses. In the drawing, a pinion 35 is shown with only one set of teeth. In the lower part of the drawing an alternative sprocket 35 'is shown, and is provided with a second set of teeth' fixed to the shaft 37 'at a distance from the first set of teeth, the first set of teeth engages with the teeth of the means 14 of toothed displacement, the second set of teeth engages with the teeth 25 of the piston rod 30. In this way, a gear can be obtained by which the displacement by the dose supply means 20 leads to the desired displacement of the piston 32 different from that of the ratio of 1: 2 obtained with the arrangement shown in the part top of the drawing, for example, a 2: 1 or 1: 1 gear.

Although a user-operated dose adjustment means constituted of a motor unit 12 has been described and illustrated, it should be noted that this unit can be replaced by any manually driven means which provides movement for the toothed moving means of according to the desired dose. In addition, the cartridge can be provided with a piston integrally connected with a piston rod, in which case a new piston rod is used whenever the cartridge is replaced. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A displacement device for controlled delivery of a dose of a liquid contained in a cartridge, characterized in that the displacement device comprises a housing that incorporates: a means for accommodating the cartridge, an elongated piston rod connected with a displaceable piston, - - the piston is adapted to expel by pressure the liquid contained in the cartridge, and - the elongated piston rod has a plurality of transversely extending teeth positioned along its length, a means of toothed displacement, - a means of dose adjustment, operated by the user, to adjust the dose. - the dose adjustment means, operated by the user, is adapted to move the toothed displacement means in response to the operation of the dose adjusting means, the extent of movement of the toothed displacement means is determined by the dose, pinion means having a shaft, the pinion means is positioned to couple the teeth of the toothed displacement means and the teeth of the piston rod, characterized in that the housing further incorporates: an elongated, displaceable and activatable dose delivery means manually, the elongated dose delivery means has a first end portion extending into the interior of the housing, and the elongated dose delivery means is movable from a first end position to a position in which the liquid is can provide, by displacing the elongated dose delivery means, towards the first end position, a means to define the first end position, a pinion means which is rotatably fixed to the elongated dose delivery means.

2. The displacement device, according to claim 1, characterized in that: the toothed displacement means is formed as a screw means having a helical cord, the screw means is caused to rotate about its longitudinal axis in response to operation of the means of dose adjustment.

3. The displacement device, according to claim 1, characterized in that: The toothed displacement means is formed as a toothed endless toothed rack, a means is provided to allow the toothed rack to be movable during the delivery of the dose of liquid.

4. The displacement device, according to any of the preceding claims, characterized in that: the piston rod is formed as a flexible member.

5. The displacement device, according to claim 1 or 2, characterized in that: the housing comprises guide surfaces to support the dose delivery means.

6. The delivery device, according to the preceding claims, characterized in that one of the guide surfaces is formed by an opening in the housing that engages the first end part of the elongated dose delivery means.

7. The displacement device, according to claim 5 or 6, characterized in that: the housing comprises a guiding surface adapted to control the displacement of the dose delivery means, and coupling the pinion means shaft, - - the surface of The guide is formed by an elongated rack extending in parallel with the elongated dose delivery means, and having first and second end surfaces adapted to limit the displacement of the dose delivery means, the second end surface defines the first end portion.

8. The displacement device, according to any of the preceding claims, characterized in that: the pinion means is provided with a first and second sets of teeth, the first set of teeth engages the teeth of the toothed displacement means, and the second set of teeth engages the teeth of the piston rod.

9. ~ The displacement device, according to any of the preceding claims, characterized in that: the dose adjustment means operated by the user comprises a motor and a motor control means having a means of dose selection.

10. The displacement device, according to any of the preceding claims, characterized in that: - the first end part of the elongated and displaceable dose delivery means is provided with marks that can be inspected by the user, indicating the dose established SUMMARY OF THE INVENTION The present invention relates to a device (1) displacement, improved, for controlled delivery of a dose of a liquid contained in a cartridge (40), the displacement device (1) comprises a housing (5) that incorporates: a means (6) to accommodate the cartridge (40), an elongated, displaceable and manually activatable dose delivery means (20), the elongated dose delivery means (20) has a first end portion (22) extending into the interior of the housing (5), an elongated piston rod (30) connected with a displaceable piston (32), the piston (32) is adapted to eject by pressure the liquid contained in the cartridge (40), and the elongate piston rod (30) has a plurality of teeth (25) that extend transversely placed along their length, a means (14) of toothed displacement, a means (8, 10, 12) of dose adjustment, operated by the user, the means (8, 10, 12) of dose adjustment operated by the user and the means (14) of displacement d In this case, they are operatively connected to cause movement of the toothed movement means (14) in response to the operation of the dose adjustment means (8, 10, 12), a pinion means (35) having a shaft (37), the pinion means (35) is rotatably fixed to the elongated dose delivery means (20), the pinion means (35) is positioned to engage the teeth of the toothed displacement means (14) and the teeth (25) of the rod (30) piston.