HK1241773A1 - Can and actuator assembly - Google Patents

Description

Canister and actuator assembly

Technical Field

The present invention relates to an apparatus and a method for assembling a metered-dose inhaler. In particular, the invention relates to the assembly of an aerosol canister (already filled with medicament) into an inhaler device.

Background

Patients typically use Metered Dose Inhalers (MDIs) to administer drugs to the lungs via the patient's breath. A typical situation with metered dose inhalers is the treatment of asthma.

Metered-dose inhalers typically comprise two components: an actuating device and an aerosol can.

The actuator is in the form of a hand-held device having a nozzle that is insertable into the mouth of a patient to receive the medicament. The medicament is delivered from an aerosol canister that houses a propellant and a specific medicament or medicament formulation. The pusher is for pushing the medicament out of the aerosol canister upon actuation of the device.

Actuation of the device is typically achieved by compressing a rod on one end of the canister, which opens a valve and releases a metered dose of the drug into an actuator and causes the drug to continue to exit through a nozzle for inhalation by the patient.

The manufacturing tolerances involved in MDI devices are in a narrow range. For example, to ensure reliable operation of the actuation valve, careful control of the movement and alignment of the canister is necessary to prevent damage to the valve and/or inadvertent actuation of the drug from the pressurized canister. Typically, actuation of the device will be caused by pressing any dosing valve stem 3mm or more.

Also, the channel in the actuator into which the stem of the canister is inserted and located is located tightly around the stem to prevent the drug from escaping back towards the canister body and out of the actuator. Such valve stem/actuator channel fittings require a "push" force to insert the stem into the actuator. If the pushing force is too great during the assembly step, the stem will depress and actuate a metered dose of medicament from the pressurized canister.

The above and other technical requirements are achieved by narrow tolerances with respect to the geometry of the actuator subassembly and the canister assembly.

To be able to transport MDI delivery devices at low cost and under high speed manufacturing conditions requires filling and packaging, where each step must be carefully controlled to avoid accidental release of the drug and/or damage to the pressurized canister valve stem or actuator.

Furthermore, the inventors have determined that even a small amount of pre-delivered release of medicament into the actuator channel and nozzle can cause clogging of the MDI. This is because the schedule between manufacture and use can be months or years, with the medicament tending to harden in the actuator nozzle over time when exposed to the environment. This makes the product unusable after delivery to the patient unless the actuator nozzle is cleaned.

The main step in the manufacturing process is to insert the filled and pressurized canister into the actuator ready for packaging and delivery to the patient.

Accurate alignment and positioning of the canister into the actuator has traditionally been achieved using a spring clutch mechanism to prevent the problems of accidental actuation during assembly as described above. However, the present inventors have determined an apparatus and method that allows the required accuracy to be achieved while avoiding the risk of releasing the drug into the manufacturing environment, while allowing extremely high manufacturing productivity.

Disclosure of Invention

According to a first aspect of the invention disclosed herein, there is provided an apparatus for inserting a canister into an inhaler actuation device, the apparatus comprising an inhaler actuation device support member at a first end of the apparatus and an insertion device at a second end, the insertion device being adapted to cause the canister to move relative to the inhaler actuation device and to enter an open end of the inhaler actuation device, wherein the apparatus further comprises a force sensor adapted to measure a reaction force between the canister and the inhaler actuation device as the canister moves relative to the inhaler actuation device.

The canister is secured in the inhaler actuation device by positioning the canister's stem into a corresponding stem-receiving channel formed in a component called the "stem block" of the inhaler device. A light press fit secures the outer wall of the canister rod to the inner wall of the rod-receiving channel to position and retain the canister within the inhaler actuation device.

At the same time, the pushing force to insert the canister into the actuator stem block provides several advantages by measurement.

For example, a reaction force or resistance is generated as the canister stem is pushed into the stem receiving channel, and the present inventors have determined that measuring the reaction force advantageously allows identification of canisters having experienced an excessive insertion force and allows them to be automatically expelled (rejection).

The canister is designed to have a specific actuation force, i.e. the force required to be applied to the lever to cause the lever to depress, thereby causing the valve to operate and release a dose of medicament. If the reaction force is higher than the predetermined force, this may indicate that there is a problem with the assembly step. One reason is that the end of the valve stem snaps over the outer edge of the stem block bore and this results in immediate depression of the valve stem and accidental actuation. Additionally or alternatively, if damage is caused to the valve stem, the valve stem will jam in the stem receiving channel and relative movement of the canister and actuator will cause the stem to depress and again be accompanied by accidental actuation.

The invention thus also allows to identify a damaged or defective canister (valve damaged or stem damaged) as part of the existing steps of assembling the actuator and canister, i.e. to achieve an integrated product quality control step without the need to perform additional inspections. This facilitates high-speed and high-volume manufacturing.

Other advantages are the ability to avoid accidental release of the drug. As described above, each canister has an actuation force; a force at or above the actuation force causes the rod to depress and accidentally release the drug. During assembly, if the rod is pushed into place too quickly and/or with too much force, the canister may be accidentally actuated, releasing the drug. There are several problems with this accidental drug release, including:

the drug may harden and clog the nozzle during storage

Contamination of assembly plants and workshops with drugs

Exposure of the operator to the released drug

By measuring the reaction force and comparing it with the actuation force for a given canister, it is possible to determine whether any drug has been released. Furthermore, it is possible to control the tank movement so as to actively prevent accidental release/actuation. Additional defective cans can be accurately and quickly identified.

The determination may be accomplished using a suitable controller and force measurement device. Such means may for example be adapted to receive input from a force sensor, such as a load cell, and to compare the measured reaction force with a predetermined reaction force limit for the canister/inhaler actuation device combination.

The controller or computer may for example be adapted to output a signal indicating that a predetermined reaction force has been reached or exceeded and/or to record or output data. If this force is exceeded, the canister will be automatically removed from the queue. This therefore allows to warn the operator and to store a record as to whether the can is defective or has been accidentally activated at the assembly stage.

Each tank valve design has its own standard actuation force and thus the controller may be provided with a number of predetermined reaction force limits corresponding to different tank/actuator combinations. The controller may also be provided with a menu selector which allows the user to conveniently select from a plurality of predetermined reaction force limits. In another arrangement, the controller may be arranged to identify the type of canister and automatically select the appropriate force parameter.

For example, a first reaction force limit of the plurality of predetermined reaction force limits may be about 20 newtons, and a second reaction force limit of the plurality of predetermined reaction forces may be about 30 newtons.

The controller may also be adapted to actively control movement of the canister relative to the actuator using feedback control equipment. Thus, the controller may be arranged to output a signal to prevent the insertion device from moving if said predetermined reaction force is reached or exceeded.

The apparatus may be configured such that the canister is only allowed to move from the reference position by a predetermined maximum displacement. Thus, the distal end of the canister rod can be positioned in the rod receiving channel of the actuation device.

The force sensor may be any suitable sensor capable of measuring or determining the force applied to the canister stem by virtue of the canister stem contacting the stem block. This may be, for example, a load cell manufactured by Kistler instruments AG.

Advantageously, the force sensor may be located between the insertion device and a portion of the apparatus arranged to apply a movement force to the canister. Thus, the force applied by the assembly device can be accurately determined by placing the sensor "online" with the mobile device.

The controller may advantageously be arranged to continuously process the measured reaction force relative to a predetermined reaction force limit and to control the movement of the insertion device to keep the measured reaction force below the predetermined reaction force limit.

The insertion means for moving the canister into the actuator may be any suitable means, but may advantageously be a pneumatically driven cylinder. The controller may be arranged to cooperate with the own control equipment of the cylinder (as described above) to control the displacement of the cylinder and hence the position and velocity of the canister relative to the actuator. Thus, feedback control can be achieved and the force applied to the canister rod can be controlled.

Viewed from another aspect there is provided an aerosol inhaler assembly apparatus comprising a first portion arranged to support an inhaler actuation device and a second portion arranged to support an aerosol canister, the apparatus being arranged to move the aerosol canister into an assembled position within the inhaler actuation device, and wherein as the aerosol canister moves, a reaction force between the inhaler actuation device and the canister is measured.

Viewed from a further aspect, there is provided a method of inserting a canister into a canister activation device, the method comprising the steps of: causing the canister to move into the open end of the canister actuation device; while measuring the reaction force between the canister and the canister actuator.

Drawings

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

figure 1 shows two sub-components of a simple metered-dose inhaler;

FIG. 2 shows a cross-section of an actuator;

FIG. 3 shows an end view of the actuator;

FIG. 4 shows the valve stem and valve stop in detail;

FIG. 5 shows an illustrative "damaged" valve stem;

FIG. 6 is a schematic view of an assembly machine; and

fig. 7 is a displacement force diagram.

While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.

Detailed Description

Figure 1 shows two sub-components of a metered-dose inhaler in partial cross-section.

The metered-dose inhaler 1 is made up of two base sub-components, an actuation means 2 and an aerosol canister 3.

The actuating device 2 has at one end a cylindrical opening 4 for receiving the canister stem of the cylindrical canister 3 and at the other end an outlet nozzle 5, which outlet nozzle 5 is ready to be placed into the mouth of a user for inhaling the medicament. The actuator is configured to actuate the canister through a passage 6 formed in the stem block 7. The channel 6 is aligned so that the opening 8 can receive a can stem (described in more detail below).

The channel 6 is also in fluid communication with a medicament dispensing diffuser 9 which receives medicament from the channel and diffuses the medicament into the nozzle 5.

The canister 3 comprises a cylinder body which houses a propeller, medicament and a dosing valve having a projecting valve stem 10. Aerosol containers or canisters of this type are well known in the art and will not be described in detail, it being said that axial movement or depression of the valve stem 10 causes the metered dose of medicament carried in the propellant to be expelled from the end of the valve stem 10.

Fig. 2 shows a cross-sectional view of another actuator 2, wherein like reference numerals refer to like features. As shown in fig. 2 (and in more detail in fig. 4), the stem block 7 is provided with a projection 11 on the inner surface of the channel 6, the stem engaging with said projection 11. The projection 11 provides an abutment preventing the valve stem from moving downwardly and causing relative movement of the canister body and valve stem so that actuation occurs.

Figure 3 is an end view of the actuator as seen from the generally cylindrical end for receiving the canister. The stem block 7 and the projection 11 can be seen in the end view of fig. 3. Fig. 3 also shows optional support ribs 12a, 12b …, which support the tank circumferentially once in place 12a, 12 b.

The inhaler assembly is obtained by inserting the entire canister into the actuator body so that the valve stem is located within the channel 6 prior to delivery to the patient. The valve stem may extend into the channel all the way into abutment with the projection 11 so that it is ready for operation, i.e. the user pressing on the end of the canister (the upper part as seen in fig. 1) causes the valve stem to press against the projection and release the medicament.

The canister valve stem is secured within the actuator stem block by a light press fit between the inner surface of the passageway 6 and the outer surface of the valve stem 10. During assembly, the ribs provide radial support to the canister and assist in coaxial alignment of the canister relative to the actuator. Importantly, the valve stem must be aligned with the stem block passageway when the canister is inserted into the actuator, as will be discussed below,

Turning to fig. 4, an expanded view of the stem block 7 and valve stem 10 is shown. As shown, the channel 6 has a projection 11, said projection 11 being arranged to abut a distal end 13 of the valve stem 10 when the stem is inserted into the stem block.

As noted above, one of the problems that the present inventors have identified (and solved) is that the assembly of a canister into an actuator can result in accidental actuation of the canister valve. This can be caused by a number of reasons.

One reason for accidental actuation of the canister is damage to the valve stem. FIG. 5 illustrates an example of a flared (expanded) end of the valve stem 10 where the outer diameter d1 is greater than the nominal diameter d 2. Because the valve stem passageway 6 is adapted to closely match the diameter of a given valve stem (in order to provide the necessary interference fit to secure the canister in the actuator), any damage such as that shown in fig. 5 will cause the distal end 13 of the valve stem to abut the upper surface 14 of the stem block. This creates a reaction force that quickly exceeds the actuation force for the canister, causing the stem to depress and accidentally release the drug during the assembly process.

It will be appreciated that corresponding damage to the stem block in the actuator may likewise cause accidental actuation of the canister.

Referring to fig. 4, the canister is assembled by causing the canister to first move a distance a so that the distal end 13 of the valve stem 10 is aligned with the stem block. Next, the canister is moved a distance B to slide the valve stem into the stem block. In this case, other accidental actuations can occur.

As the valve stem moves into the stem block, the outer surface 15 of the valve stem engages the inner surface 16 of the stem block. Due to friction (dynamic and static) a reaction force is generated against the force applied to cause the tank to move.

As one example, if this reaction force is allowed to exceed the actuation force of a given canister, accidental actuation may occur. As an example, a metered dose valve for a canister manufactured by 3M company has an actuation force of 30 newton.

In the event of accidental actuation, a quantity of medicament 17 is discharged into the channel. In the absence of user breathing, it will remain in the channel, causing the channel to clog.

In any of these cases, the actuator or canister in question must be automatically discarded at once by the control system.

Thus, measuring the reaction force generated when assembling the canister and actuator can not only be used to identify a defective canister or a defective actuator, but can also determine whether an accidental actuation has occurred that could jam the actuator as described above.

The assembly apparatus and method will now be described with reference to figure 6, which figure 6 schematically shows the general arrangement and subcomponents of an assembly machine.

The assembly machine comprises an actuator support part 18 and an opposite canister support part 19. The actuator support portion is arranged to support the actuator 20 such that the rod block 21 is aligned with the longitudinal axis 22 of the machine. It will be appreciated that the actuator may be supported in a variety of different ways. An important feature of the actuator support is that the stem block is aligned with the axis 22.

The canister support portion 19 is adapted to support and hold a canister and is further coupled to a linear actuator 23. The canister support portion 19 is also arranged so that the valve stem 10 of the canister is aligned with the axis 22 so that movement of the canister relative to the actuator maintains the stem block 21 and valve stem 10 in alignment.

The tank support portion 19 is connected on the opposite side to a pneumatically driven linear actuator 23, which linear actuator 23, in operation, causes the tank support portion 19 to move in a direction 24 along the axis of the machine 22. Thus, the canister can be inserted into the actuator.

A force sensor in the form of a Kistler load cell 25 is located between the pneumatic linear actuator 23 and the canister support portion 19. Any reaction force generated along the axis of the machine (e.g. by causing a damaged valve stem to abut the stem block 21) causes a load to be applied to the sensor 25. The load cell is provided with a control equipment 26, said control equipment 26 receiving output signals from the cell along a control line 27.

The control equipment 26 is provided with a plurality of predetermined reaction force limits which match the actuation force of the respective canister and actuator combination. The operator can interact with the controller via the interface 28 to select the correct reaction force limit for the current canister and actuator combination.

The controller may optionally be provided with a feedback control line 29 which communicates with a control equipment 30 for the pneumatic linear actuator 23. The control equipment 30 is arranged to cause the canister support to reciprocate between a loading position in which a new canister and actuator can be placed on the machine, and an assembly position in which the canister is moved into the actuator and the valve stem enters at least partially into the passage in the stem block 21.

The control circuit 29 allows the controller 26 to optionally control the movement of the linear actuator to ensure that the reaction force remains below a predetermined limit, e.g. the actuation force for a given canister is less than a threshold value.

The operation of the machine will now be described with reference to fig. 6 and 7, fig. 7 being a displacement diagram.

First, the canister and actuator pair are inserted into their respective support sections in the machine. Actuating the control equipment and the pneumatic linear actuator causes the canister to move along the axis 22 and through the distance d₁、d₂And d₃As shown in fig. 6 and 7.

FIG. 7 is a graph showing force (N) versus distance d along a machine₁、d₂And d₃A graph of (a).

d₁Corresponding to the distance between the loading positions of the linear actuator

d₂Corresponding to the distance the canister moves into the actuator; and

d₃corresponding to the distance moved into the stem block.

During the tank movement, the control equipment continuously receives signals from the load cell 25, which are converted into reaction force data, which are continuously compared with the force set point that has been selected by the user via the interface 28.

Figure 7 shows how the force measured by the load cell changes as the canister is moved to the assembled position in the actuator.

As the tank moves through a first distance d₁The reaction force decreases after a small initial rise due to overcoming the static friction, since there is no resistance against the tank movement.

At a distance d₂The shoulder 31 of the can engages with the rib shown in figure 3 and the small rise in force is due to the slight resistance to movement as the outer wall of the can slides along the rib.

The following three examples represent three scenarios represented by lines N1, N2, and N3 in fig. 7.

Line N1 is a flawless can, i.e., a can having a valve stem without damage

As the valve stem enters the stem block, the inner surface of the outer surface block is in tight engagement with the stem block so as to cause an interference fit. The force initially increases, then decreases slightly as the canister support portion stops moving and finally drops to zero. In this example, the canister has been accurately inserted into the actuator. The canister support portion is retracted and the assembled canister and actuator are removed for packaging. The reaction force limit is not exceeded.

Line N2 represents the same graph for a damaged valve stem

As the valve stem approaches the stem block, the damaged end surface (reference numeral 13 in fig. 4) abuts the end face 14 of the stem block. This causes the reaction force as represented by line N2 at distance d2 to immediately increase substantially. At this time, the reaction force exceeds the limit of the reaction force shown in fig. 7, which is detected by the force sensor 25 and the control equipment 26. Here, alerting the operator that the force has been exceeded indicates that the canister may have been actuated accidentally. This may be any suitable signal, such as an audible alarm or a visual alarm. The controller may additionally be arranged to cause retraction of the canister support portion in combination with an alarm of a defective canister.

Line N3 represents an alternative feedback control arrangement

N3 represents the case where the valve stem has minimal imperfections in the geometry of the valve stem. Here, at a distance d3, the damaged outer portion of the valve stem engages and partially abuts the end of the stem block. In this feedback arrangement, the force sensor detects an increase in the reaction force, which approaches the actuation force limit. The controller is arranged to slow the movement of the pneumatic actuator to reduce the generated reaction force (represented by line N3 over distance d 3). The valve stem slides slowly into the stem body due to the slower movement deflection defect through the canister support portion.

Thus, continuously monitoring the reaction force allows the controller to actively control the reaction force being generated, thereby preventing accidental actuation of the valve, but also preventing the canister being identified from being inserted into a defective canister in the assembly that may actually pass the quality test if the canister is more carefully (i.e., at a lower speed and resulting in less force).

The position of the sensor head (such as that manufactured by Kistler) is generally arranged so that it bears the direct load transmitted to the canister during the insertion step, typically being mounted in-line on the drive arm. Kistler load cells can be advantageously used because they are approved robust measurement devices, however, any load cell from an equivalent instrument vendor can be interchanged in design.

Claims (25)

1. An apparatus for inserting a canister into an inhaler actuation device, the apparatus comprising an inhaler actuation device support member at a first end of the apparatus and an insertion device at a second end for causing a canister to move relative to the inhaler actuation device and for entering an open end of the inhaler actuation device, wherein the apparatus further comprises a force sensor for measuring a reaction force between the canister and the inhaler actuation device as the canister moves relative to the inhaler actuation device.

2. The apparatus of claim 1, further comprising a controller for receiving input from the force sensor and for comparing the measured reaction force to a predetermined reaction force limit for the canister/inhaler actuation device combination.

3. The apparatus of claim 2, wherein the controller is for outputting a signal indicating that a predetermined reaction force has been reached or exceeded and/or recording or outputting data.

4. A device according to claim 2 or 3, wherein the controller is provided with a plurality of predetermined reaction force limits and the controller is provided with a selector allowing a user to select from the plurality of predetermined reaction force limits.

5. The apparatus of claim 4, wherein a first reaction force limit of the plurality of predetermined reaction force limits is approximately 20 newtons and a second reaction force limit of the plurality of predetermined reaction force limits is approximately 30 newtons.

6. An apparatus according to any of claims 2-5, wherein the controller is arranged to output a signal to prevent the insertion device from moving if a predetermined reaction force is reached or exceeded.

7. The apparatus of any one of the preceding claims, wherein the insertion device is controlled such that the canister moves into the canister a predetermined distance.

8. The apparatus of claim 7, wherein the predetermined distance is such that a distal end of a valve stem of a metered dose valve of the canister is located within a stem receiving channel in a stem block of the inhaler actuation device.

9. An apparatus according to any preceding claim, wherein the force sensor is located between the insertion device and a portion of the apparatus arranged to apply a movement force to the canister.

10. The apparatus of claim 9, wherein the force sensor is a piezoelectric force sensor.

11. An apparatus according to any of claims 2-10, wherein the controller is arranged to continuously process the measured reaction force with respect to the predetermined reaction force limit and to control the movement of the insertion device to keep the measured reaction force below the predetermined reaction force limit.

12. The apparatus according to any one of the preceding claims, wherein the insertion device is a pneumatically driven cylinder.

13. Apparatus according to any preceding claim, wherein the insertion means is operable to move the canister at different speeds relative to the inhaler actuation means.

14. The apparatus of claim 13, wherein the insertion device operates at a first speed to bring the canister towards the inhaler actuation device, and the insertion device operates at a second speed as the canister rod moves into the inhaler actuation device rod receiving channel.

15. The apparatus of any one of the preceding claims, wherein the canister is a metered dose inhaler canister and the inhaler actuation device is a metered dose inhaler actuation device.

16. An aerosol inhaler assembly apparatus, comprising: a first portion arranged to support an inhaler actuation device and a second portion arranged to support an aerosol canister, the apparatus being arranged such that the aerosol canister moves into an assembled position within the inhaler actuation device, and wherein a reaction force between the inhaler actuation device and the aerosol canister is measured as the aerosol canister moves.

17. A method of inserting a canister into a canister actuator assembly, the method comprising the steps of: causing the canister to move into the open end of the canister actuation device; while measuring the reaction force between the canister and the canister actuator.

18. The method of claim 17, further comprising the steps of: comparing the measured reaction force with a predetermined reaction force for the canister/canister actuator combination.

19. The method of claim 18, further comprising a controller, wherein the controller is for outputting a signal indicating that a predetermined reaction force has been reached or exceeded and/or recording or outputting data.

20. A method according to claim 19, wherein the controller is arranged to output a signal to prevent the canister from moving if a predetermined reaction force is reached or exceeded.

21. A method according to claim 18 or 19, wherein the canister is automatically excluded if the predetermined reaction force is reached or exceeded.

22. A method according to claim 18, 19 or 20, wherein the canister activation device is automatically excluded if the reaction force between the canister and the canister activation device reaches or exceeds the activation force of the canister and/or reaches or exceeds the predetermined reaction force limit for the canister/canister activation device.

23. A method according to claim 18 or 19, wherein the controller is arranged to continuously process the measured reaction force against the predetermined reaction force limit and to control the movement of the canister to keep the measured reaction force below the reaction force limit.

24. An apparatus substantially as herein described with reference to figure 6.

25. A method substantially as herein described.