AU2013205495B2 - Dispersing unit - Google Patents

Abstract

Abstract A dispersing unit for a powder inhaler comprising a mouthpiece in which a ring passage is provided for the supply of a particle flow and 5 has an axial inlet and an axial outlet, with the axial outlet being adjoined by a ring-shaped deflection chamber in which the axially entering particle flow is deflected into a predominantly radial flow direction and with a rotation chamber having a circular peripheral wall and an axial outlet adjoining the deflection chamber in the axial 10 direction, wherein the axial outlet of the rotation chamber is arranged centrally and wherein a discharge passage which expands concavely, adjoins the axial outlet of the rotation chamber. If I0

Description

1 Dispersing unit The present invention relates to a dispersing unit for a powder inhaler. Dispersing units of this type are generally known and serve to generate 5 a dispersal of an aerosol, wherein the aerosol comprises a mixture of active agent and a carrier substance, e.g. lactose. The carrier substance mainly serves to control the physical properties of the formulation such as its flowability. In this process, the fine active agent primarily adheres to the surface of the coarse carrier substance. The adhesive forces 10 present between carrier particles and active agent particles or between active agent particle agglomerates must be overcome during inhalation to generate a high proportion of respirable active agent particles. The energy required for this can be introduced in a dispersing unit. 15 In known dispersing units, impaction forces or turbulences or a combination of the two are used for the dispersion. It is also known to generate dispersion with the help of impact walls and additional supply air passages. 20 It would be advantageous if embodiments of the present invention provide a dispersing unit which is extremely compact in construction, is simple in construction and with which a fine particle fraction can be generated which is as high as possible without suction force loss. 25 The present invention provides in a first aspect a dispersing unit for a powder inhaler comprising a mouthpiece in which a ring passage is provided for the supply of a particle flow. In this connection, the ring passage has an axial inlet and an axial outlet to supply the particle flow that may comprise a mixture of active agent and carrier substance. 30 2 A ring-shaped deflection chamber adjoins the axial outlet of the ring channel and the axially entering particle flow is deflected in a predominantly radial flow direction in it. At the same time, an acceleration of the particle flow can be achieved in this deflection 5 chamber so that the particle flow circulates in circular form in a rotation chamber which adjoins the deflection chamber in the axial direction and has a circular peripheral wall and an axial outlet. The axial outlet of the rotation chamber is arranged centrally and a discharge passage which expands concavely, adjoins the axial outlet of 10 the rotation chamber. The particle flow supplied through the ring passage may therefore be brought into a ring-shape circulation track after exiting the deflection chamber solely by suction at the mouthpiece, with light particles, for 15 example purely active agent particles having a particle size of less than 5 pm, being able to exit the axial outlet of the rotation chamber at an early stage due to their lower centrifugal force. On the other hand, coarser particles, for example carrier particles charged with active agent, may be held longer in the rotation chamber due to their mass of 20 inertia in which they circulate a multiple of times and impact the peripheral wall of the rotation chamber in the process, whereby the fine active agent particles additionally separate from the coarser carrier particles. All fine particles may follow the airflow through the axial outlet of the rotation chamber at a slowed-down speed and are available 25 for inhalation as a non-ballistic aerosol. In accordance with an embodiment of the invention, the deflection chamber and the rotation chamber are not used for the separation of coarse particles, but a distribution between coarse and fine particles 30 differing in the average dwell time is utilized. Coarser particles may thus also exist the rotation chamber up to the end of the inhalation 3 procedure so that no real powder residues remain which could degrade the functionality of the inhaler or the uniformity of the dose discharge on the application of further doses. 5 The ring passage in accordance with an embodiment of the invention has an axially oriented inlet and outlet. Generally, however, the particle flow introduced into the ring passage may nevertheless also have tangential flow components. 10 In accordance with an advantageous embodiment, guide vanes oriented obliquely to the axial direction may be arranged in the deflection chamber. The particle flow entering axially via an annular space may be deflected into a tangential flow in a simple manner using such guide vanes, with simultaneously an acceleration of the particle flow in the 15 deflection chamber being able to be effected by the design of the deflection vanes. It may be advantageous for the guide vanes to be curved to achieve the desired deflection and acceleration effects. It may be advantageous in 20 this process for the curvature of the guide vanes to reduce in the axial direction. The guide vane may hereby be designed in the manner of a turbine vane in order to achieve the best possible deflection and acceleration. It may also be advantageous in this connection for the guide vanes to have the profile of a wing with a curved skeleton line in 25 section. It may also be advantageous in this connection for the guide vanes to have a rounded front edge in the region of the inlet of the deflection chamber and a rear edge with less pronounced rounding in the region of the outlet of the deflection chamber. Tests which have been made show that very good results may be achieved by such a 30 section design.

4 By arranging the axial outlet of the rotation chamber centrally, light particles may hereby exit the rotation chamber through the outlet at an early stage, whereas heavy particles circulate along the peripheral wall of the rotation chamber. 5 In accordance with an embodiment of the invention, the discharge passage, which expands, adjoins the axial outlet of the rotation chamber. The expansion may be concave, whereby it is achieved that the aerosol particles exiting the outlet of the rotation chamber with 10 relatively high speed in a direction transversal of the direction of inhalation are slowed down in the region of the discharge passage, with the movement of the aerosol being predominantly oriented in the longitudinal direction in the outlet passage. At the same time, a slow aerosol discharge may be achieved by the cross-section increase of the 15 discharge passage so that the patient inhales a non-ballistic aerosol. The aerosol deposition in oropharyngeal region of the patient may be reduced using such a mouthpiece geometry by influencing the exit direction and the exit speed. Although the aerosol exits the rotation chamber into the outlet at relatively high radial speeds, the aerosol exit 20 speed at the end of the discharge passage is relatively low. It may furthermore be advantageous for the discharge passage to have a circular cylindrical region in an end section at the exit side since an axial bundling of the discharge particle flow can thereby be effected. A 25 convex design may also conceivable instead of a concave design. The deposition of light particles from the rotation chamber may additionally be improved in that the discharge passage is sharp-edged and in particular adjoins the rotation chamber with an edge having an 30 acute angle in cross-section.

5 It may also be advantageous to form the transition from the circular peripheral wall to the axial outlet in the rotation chamber with a part curvature since this effects improved aerodynamics, on the one hand, and a reduced deposition of particles, on the other hand. 5 In the dispersing unit in accordance with an embodiment of the invention, no air inlet openings are provided for the supply of external air between the axial outlet of the ring passage and the outlet of the rotation chamber. It is hereby precluded that an additional suction 10 power has to be applied to maintain the functionality of the dispersing unit, which does not benefit either the mobilization of the powder from the dispersing device nor the actual dispersing power. The deflection of the particle flow and the directed outlet into the pharynx are realized solely via geometrical implementations in accordance with an 15 embodiment of the invention. Embodiments of the present invention will be described in the following purely by way of example with reference to an advantageous embodiment and to the enclosed drawing. 20 There are shown: Fig. 1 a partly sectioned side view of a dispersing unit. 25 Fig. 1 shows a dispersing unit for a powder inhaler (not shown) having a mouthpiece 10 at whose lower side a ring passage 12 is provided for the supply of a particle flow. The particle flow is generally produced by suction at the mouthpiece, for example in that a predetermined dose of active agent and carrier substance is made available in the inhaler and 30 is then sucked into the ring passage 12 by suction at the mouthpiece.

6 The ring passage 12 is circumferential in the peripheral direction and has an axial inlet 14 and an axial outlet 16, with both the inlet 14 and the outlet 16 extending over the total periphery of the ring passage 12. 5 Adjoining the axial outlet 16 of the ring passage 12, a likewise ring shaped deflection chamber 18 is provided which has approximately the same radial extent as the ring passage 12 and in which the axially entering particle flow is deflected into a predominantly radial direction of flow. The substantially radially directed particle flow at the outlet of 10 the deflection chamber 18 is in this process guided into a rotation chamber 20 which has a circular peripheral wall 22 and an axial outlet 24. As Fig. 1 shows, the outer diameters of the ring passage 12, of the 15 deflection chamber 18 and of the rotation chamber 20 are of substantially the same size. The inner diameter of the ring passage 12 and the inner diameter of the deflection chamber 18 also correspond to one another. The inner diameter of the axial outlet 24 of the rotation chamber 20 is lower than the inner diameter of the deflection chamber 20 18. To deflect the axially entering particle flow in the deflection chamber 18 into a predominantly radial flow direction and to accelerate it at the same time, a plurality of guide vanes 26 are provided in the deflection 25 chamber 18, distributed over its periphery, and are oriented obliquely to the axial direction. Each of the guide vanes 26 extends over the total cross-section of the deflection chamber 18, with each guide vane being curved and the curvature reducing in the axial direction, i.e. being more pronounced at the inlet of the deflection chamber 18 than at the outlet. 30 In section (longitudinal section), the guide vanes 26 have the section of a wing having a curved skeleton line. In accordance with an 7 advantageous embodiment, the guide vanes have a rounded front edge in the region of the inlet of the deflection chamber 18 and a rear edge of less pronounced rounding in the region of the outlet of the deflection chamber 18 so that the section of the guide vanes 26 is similar to an 5 airplane wing. As Fig. 1 further shows, the peripheral wall 22 of the rotation chamber 20 is of circular cylindrical form and directly adjoins the outlet of the deflection chamber 18, with the axial extent of the deflection chamber 10 18 and of the rotation chamber 20 being approximately of equal size. At its outlet side end, the rotation chamber 20 has an end wall 28 which forms a transition between the peripheral wall 22 and the centrally arranged axial outlet 24. In this process, the transition from the circular peripheral wall 22 to the end wall 28 is curved in the region of 15 the corner. A discharge passage 30 whose peripheral wall 32 expands concavely adjoins the axial outlet 24 of the rotation chamber 20. The transition between the end wall 28 of the rotation chamber 20 and the peripheral 20 wall 32 of the discharge passage 30 is, however, sharp-edged and is made with an acute angle in the embodiment shown. Furthermore, the discharge passage 30 has a circular cylindrical region 33 in its outlet side end section which extends up to the end of the discharge passage 30 and which effects an axial bundling of the discharged particle flow. 25 As Fig. 1 further shows, no air inlet openings for the supply of external air are provided between the inlet 14 of the ring passage 12 and the discharge passage 30. 30 In the use of the described dispersing unit, the patient sucks at the mouthpiece 10, whereby a particle flow is guided through the 8 mouthpiece in the direction of the arrows shown (axial direction), said particle flow having been previously made available in a desired dose by a powder inhaler (not shown). The sucked-in particle flow is first introduced into the ring passage 12 through the inlet 14 and exits the 5 ring passage 12 into the ring-shaped deflection chamber 18 through the ring-shaped axial outlet 16. In the deflection chamber 18, the particle flow is accelerated by the guide vanes 26, on the one hand, and deflected into a predominantly radial flow direction, on the other hand, so that the particle flow enters into the rotation chamber 20, which 10 adjoins the deflection chamber 18 in the axial direction, approximately tangentially at the outlet of the deflection chamber 18. The particle flow rotates in the rotation chamber 20, with heavy particles circulating longer in the region of the circular peripheral wall 22 and lighter particles following the air flow and moving faster in the direction of the 15 discharge passage 30. The heavier particles circulating in the rotation chamber 20 initially discharge increasingly smaller (active agent) particles during their circulation due to contact with the peripheral wall 22 until these 20 particles circulating in the rotation chamber 20 likewise follow the air flow and are then also discharged. The described dispersing unit is made of plastic in accordance with an advantageous embodiment. It can be advantageous in this connection 25 to make the guide vanes 26 in one piece with an insert 27, for example as an injection molded part, with the insert 27 with the guide vanes 26 molded thereon being able to be inserted into the interior of the mouthpiece 10. 30 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express 9 language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features in various embodiments of the invention. 5 Modifications and variations as would be apparent to a skilled addressee are determined to be within the scope of the present invention. 10 10 Reference numeral list 10 mouthpiece 12 ring passage 5 14 inlet of the ring passage 16 outlet of the ring passage 18 deflection chamber 20 rotation chamber 22 circular peripheral wall 10 24 outlet of the rotation chamber 26 guide vanes 27 insert 28 end wall 30 discharge passage 15 32 peripheral wall 33 circular cylindrical region

Claims (12)

1. A dispersing unit for a powder inhaler comprising a mouthpiece in which a ring passage is provided for the supply of a particle 5 flow, the ring passage having an axial inlet and an axial outlet, with the axial outlet being adjoined by a ring-shaped deflection chamber in which the axially entering particle flow is deflected into a predominantly radial flow direction, the deflection chamber being adjoined in the axial direction by a rotation chamber having 10 a circular peripheral wall and an axial outlet, wherein the axial outlet of the rotation chamber is arranged centrally and is adjoined by a discharge passage which expands concavely. 15

2. A dispersing unit in accordance with claim 1, wherein guide vanes oriented obliquely to the axial direction are arranged in the deflection chamber.

3. A dispersing unit in accordance with claim 2, wherein the guide 20 vanes effect an acceleration of the particle flow.

4. A dispersing unit in accordance with claim 2 or claim 3, wherein the guide vanes are curved, with the curvature reducing in the axial direction. 25

5. A dispersing unit in accordance with claim 2, claim 3 or claim 4, wherein the guide vanes have the profile of a wing with a curved skeleton line in section. 30

6. A dispersing unit in accordance with any one of claims 2 to 5, wherein the guide vanes have a rounded front edge in the region 12 of the inlet of the deflection chamber and a rear edge having a less pronounced rounding in the region of the outlet of the deflection chamber. 5

7. A dispersing unit in accordance with any one of the preceding claims, wherein the discharge passage adjoins the rotational chamber with a sharp edge, for example at an angle acute in cross-section. 10

8. A dispersing unit in accordance with any one of the preceding claims, wherein the discharge passage has a circular cylindrical region in an end section at the outlet side in order to effect an axial bundling of the discharged particle flow. 15

9. A dispersing unit in accordance with any one of the preceding claims, wherein a transition in the rotation chamber from the circular peripheral wall to the axial outlet is partly curved.

10. A dispersing unit in accordance with any one of the preceding 20 claims, wherein the outlet of the ring passage extends over the total periphery.

11. A dispersing unit in accordance with any one of the preceding claims, wherein no air entry openings for the supply of external 25 air are provided between the axial outlet of the ring passage and the outlet of the rotation chamber.

12. A dispersing unit in accordance with any one of the preceding 30 claims, wherein the concave expansion is arranged such that it is achieved that the particles exiting the outlet of the rotation chamber with relatively high speed in a direction transversal of 13 the direction of inhalation are slowed down in the region of the discharge passage, with the movement of the particle flow in the discharge passage being predominantly oriented in the longitudinal direction.