MEMBRANE UNIT FOR GENERATING AN AEROSOL IN AN AEROSOL THERAPY DEVICE, AEROSOL THERAPY DEVICE AND METHOD OF MANUFACTURING A MEMBRANE UNIT OF AN AEROSOL GENERATOR

Abstract

The present invention relates to a membrane unit for generating an aerosol in an aerosol therapy device, the membrane unit comprising a membrane (1) having an area (6) comprising a plurality of through-holes for nebulizing a fluid and a flange (7) circumferentially surrounding the area (6), and a substrate (2) having an opening (8) wherein the flange (7) of the membrane (1) is welded to the substrate (2) so that the area (6) is located in the opening (8) wherein the weld (5) comprises at least three discontinuous welds (5c) arranged at a distance from each other a long a circumference of the opening (8) and a first annular weld (5b) circumferentially surrounding the opening (8).

Claims

1. A membrane unit for generating an aerosol in an aerosol therapy device, comprising: a membrane having an area comprising a plurality of through holes for nebulizing a fluid and a flange circumferentially surrounding the area; and a substrate having an opening, wherein the flange of the membrane is welded to the substrate so that the area is located in the opening, wherein the weld comprises at least three discontinuous welds arranged in a distance to each other along a circumference of the opening and a first annular weld circumferentially surrounding the opening.

2. The membrane unit according to claim 1, wherein the discontinuous welds are arranged on a common circle concentric with the first annular weld.

3. The membrane unit according to claim 1, wherein the first annular weld is arranged radially inward of the discontinuous welds with respect to the opening.

4. The membrane unit according to claim 1, further comprising a second annular weld substantially concentric with the first annular weld.

5. The membrane unit according to claim 4, wherein the second annular weld is arranged radially outward of the discontinuous welds.

6. A membrane unit for generating an aerosol in an aerosol therapy device, comprising: a membrane having an area comprising a plurality of through holes for nebulizing a fluid and a flange circumferentially surrounding the area; and a substrate having an opening, wherein the flange of the membrane is welded to the substrate so that the area is located in the opening, wherein the weld comprises a first annular weld circumferentially surrounding the opening and a second annular weld substantially concentric with the first annular weld.

7. The membrane unit according to claim 6, wherein the second annular weld overlaps a radial outer edge of the flange in a plan view and/or the first annular weld overlaps a radial inner edge of the substrate at the opening in a plan view.

8. The membrane unit according to claim 6, wherein the welds are laser welds.

9. An aerosol therapy device for generating an aerosol, comprising the membrane unit according to claim 6.

10. Method of manufacturing a membrane unit of an aerosol generator, the method comprising the steps of: bringing a substrate having an opening, and a membrane having an area comprising a plurality of through holes for nebulizing a fluid and a flange circumferentially surrounding the area in surface contact so that the area is located in the opening, laser welding the flange to the substrate at a first annular weld circumferentially surrounding the opening, wherein preferably a feed rate of the laser along the annular path of the first annular weld is between 200 and 800 mm/s and a laser output is between 300 W and 900 W.

11. Method according to claim 10, further comprising the step of laser welding the flange to the substrate at at least three discontinuous welds arranged around the opening in a circumferential direction before laser welding the first annular weld.

12. Method according to claim 10 or 11, further comprising the step of laser welding the flange to the substrate at a second annular weld circumferentially surrounding the opening.

13. Method according to claim 10, wherein the laser used for laser welding is a multimode laser having a scanner optic.

14. Method according to claim 10, wherein at least one of the surfaces of the substrate and the flange of the membrane to be brought in contact is roughened by laser structuring.

15. Method according to claim 10, wherein the substrate is thicker than the flange of the membrane in a direction perpendicular to the surfaces of the substrate and the flange of the membrane to be brought in surface contact and the step of laser welding is performed from a side of the flange of the membrane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG. 1 shows a cross-section of a membrane unit;

[0044] FIG. 2a shows a plan view of a membrane unit according to the invention;

[0045] FIG. 2b shows a plan view of an alternative membrane unit according to the invention;

[0046] FIG. 2c shows a plan view of a further alternative membrane unit according to the invention;

[0047] FIG. 3a shows an enlarged cross-section of a membrane unit according to the invention; and

[0048] FIG. 3b shows an enlarged cross-section of an alternative membrane unit according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0049] FIG. 1 shows a membrane unit of the present invention. The membrane unit is basically an oscillatable system, which is rotationally symmetrical relative to the central axis M shown in FIG. 1. The membrane unit comprises a membrane 1 and a substrate or carrier or support 2 having a centrally arranged circular opening 8. The membrane 1 is preferably curved or dome-shaped. The membrane 1 is circular and arranged concentric to the central axis M. The membrane 1 comprises a circular, centrally arranged effective area 6 which comprises a plurality of (invisible) through-holes. Preferably, the through-holes are in the range of less than 10 μm, preferably less than 5 μm and more preferably between 1.5 μm and 5 μm in diameter.

[0050] A flange or annular collar 7 is arranged concentric to the effective area 6. The flange 7 circumferentially surrounds the area 6. The flange 7 protrudes over the opening 8 (so as to form an overlapping with the substrate 2) and serves to fix the membrane 1 to the substrate 2. The flange of the membrane 1 is welded to the substrate 2 so that the area 6 is located in the opening 8, by means of one or more welds 5.

[0051] FIG. 1 shows the membrane unit according to the invention, including a piezo electric element as actuator. When installed in an aerosol therapy device, the fluid to be nebulized is present on the upper side of the substrate 2, and nebulization or aerosol generation occurs on the opposite side, namely the lower side of the substrate 2, when the membrane is caused to oscillate, and the fluid, in particular a liquid, is nebulized through the plurality of through-holes on the lower side of the substrate 2.

[0052] A piezo element 3 is attached, in particular adhered, to the substrate 2 on the lower side. An AC voltage can be applied via a first electrode 4 and via the substrate 2. The substrate 2 can assume the function of a second electrode for the piezo element 3. Alternatively, a second electrode may be provided on the upper side of the substrate 2. In one embodiment, the first electrode 4 may be formed as a Kapton foil with electronic conductive paths.

[0053] When the AC voltage is applied to the electrodes (see the right part of FIG. 1), this leads to a lengthening and shortening of the piezo element 3 in a direction perpendicular to the axis of symmetry M as shown in FIG. 1. As a result, during the alternating lengthening and shortening of the piezo element 3, the carrier is bent and caused to flexurally oscillate, these oscillations being transferred to the membrane 1. The resonance frequencies of the oscillation system are determined by the membrane 1, the substrate 2 and the piezo element 3 as well as by the type of fixing or connecting between the membrane 1 and the substrate 2. The resonance frequencies of the oscillation system are also influenced by the liquid which is in contact with the membrane 1.

[0054] The weld or welding seal 5 in the region of the flange 7 fixes the membrane 1 to the substrate 2. For this purpose, the flange 7 is in surface contact with the lower side of the substrate 2. Connection is carried out such that the membrane 1 with the collar or flange 7 is brought into surface contact with the substrate 2, more specifically the lower side, i.e. lower surface area, of the substrate, and then a welding process is performed.

[0055] The width of the flange is adjusted accordingly in the radial direction. For example, the area of the flange is in the range between 5 mm.sup.2 and a maximum of 96 mm.sup.2, preferably a maximum of 80 mm.sup.2, and mostly preferred a maximum of 20 mm.sup.2. The area of the flange 7 is measured in the region which protrudes over the opening 8 of the substrate 2.

[0056] In the embodiment of FIG. 1, the membrane 1 is connected to the lower side of the substrate 2. Also the piezo electric element 3 is connected to the lower side of the substrate 2. The membrane 1 and the piezo electric element 3 are connected to the identical (same) side of the substrate 2. The membrane 1 with the collar or flange 7 is brought into surface contact with the substrate 2, more specifically to the same side as the piezoelectric element is in contact with the substrate 2 (FIG. 1, FIG. 3b, FIG. 3c).

[0057] In an alternatively embodiment of FIG. 3a, the membrane 1 is connected to the lower side of the substrate 2 and the piezoelectric element 3 may be connected to the upper side of the substrate 2. The membrane 1 is connected to the opposite side of the substrate 2 than the piezoelectric element 3. The membrane 1 with the collar or flange 7 is brought into surface contact with the substrate 2, more specifically to the opposite side as the piezoelectric element is in contact with the substrate 2.

[0058] A laser beam may be applied to the membrane and the substrate as indicated in FIG. 3a, FIG. 3b and FIG. 3c with the triangles marked with 5a and 5b. For example as shown in FIG. 3c, the laser beam may be applied at the triangle 5b such that the laser beam is entirely on the substrate 2. Alternatively, the laser beam could be placed half on the substrate 2 and half on the membrane 1, as indicated by the laser beam at the triangle 5a pointing to the edge of the flange 7. Ideally, one third of the width of the laser beam is on the substrate 2, and two thirds are on the membrane 1.

[0059] FIG. 2a shows a first specific embodiment in line with the invention, in which the weld 5 comprises three discontinuous or discrete welds 5c arranged equidistantly to each other along a circumference of the opening 8 and a first annular weld 5b circumferentially surrounding the opening. As can be taken from FIG. 2a, the discontinuous welds 5c are arranged on a common circle concentric with the first annular weld 5b. The discontinuous welds 5c fix the substrate 2 to the membrane 1 and may reduce the bulge.

[0060] FIG. 2b shows another embodiment of the present invention, in which the weld 5 comprises the first annular weld 5b circumferentially surrounding the opening and a second annular weld 5a substantially concentric with the first annular weld 5b. In particular, also the second annular weld 5a circumferentially surrounds the opening 8.

[0061] FIG. 2c basically shows a combination of the embodiments of FIGS. 2a and 2b, which can, however, also be provided alternatively. More specifically, in FIG. 2c, nine discontinuous welds 5c, a first annular weld 5b, and a second annular weld 5a are provided. The second annular weld 5a is substantially concentric with the first annular weld 5b and is arranged radially outward of the discontinuous welds 5c. The first annular weld 5b is arranged radially inward of the discontinuous welds 5c with respect to the opening 8. The second annular weld 5a overlaps a radial outer edge of the flange 7, and the first annular weld 5b overlaps a radial inner edge of the substrate 2 at the opening 8.

[0062] The membrane units as shown in FIGS. 2a to 2c can be manufactured by laser welding. In particular, in the embodiment shown in FIG. 2a, the step of laser welding the flange 7 to the substrate 2 at the three discrete welds 5c can be performed before laser welding the first annular weld 5b.

[0063] For the embodiments of FIGS. 2b and 2c, a further step of laser welding the flange 7 to the substrate 2 at a second annular weld 5a circumferentially surrounding the opening 8 is performed.

[0064] In each of these embodiments, the substrate and the membrane 1 having the area 6 are brought into contact such that the area 6 is located in the opening 8. Afterwards, laser welding of the flange 7 to the substrate 2 is performed, wherein the feed rate of the laser along the annular path of the first annular weld is between 200 and 800 mm/s and a laser output is between 300 W and 900 W. Preferably, before the substrate and the flange 7 of the membrane 1 are brought into contact, the surfaces of the substrate 2 and the flange 7 may be roughened by laser structuring.

[0065] As shown in FIG. 3a, the membrane 1 may be positioned above the substrate 2, so that the welds 5a, 5b are formed on the upper side of the substrate 2. Hence, the welds are visible in a plan view taken from the above. The piezoelectric element 3 may be provided on the upper side (as indicated in FIG. 3a) or may be provided on the lower side of the substrate 2.

[0066] Alternatively, as shown in the embodiment of FIG. 3b, it is conceivable that the membrane 1 is, with its flange 7, positioned beneath the substrate 2. Hence, depending on the positioning of the membrane 1 and the flange 7 of the substrate 2, the welds are formed either on the upper side of the substrate 2 (see FIG. 3a) or on the lower side of the substrate 2 (see FIG. 3b). The piezoelectric element 3 may be provided on the upper side (as indicated in FIG. 3b) or may be provided on the lower side of the substrate 2.

[0067] In the embodiments shown in the drawings, the substrate 2 is thicker than the flange 7, in the direction perpendicular to the surface of the substrate 2, i.e. in the direction of the symmetry axis M. Therefore, the welding is performed from the side of the flange 7. In an embodiment which is not shown in the drawings, it is conceivable that the step of welding is performed from a side of the substrate 2, when the substrate is thinner than the flange 7 of the membrane 1 in a direction perpendicular to the surfaces of the substrate 2 and the flange 7 of the membrane 1.

[0068] In one embodiment, the membrane 1 is positioned on the opening 8 in the substrate 2. A centring tool or centring aid, for example a stop bar, noses, feed hopper, funnel and so on, and/or alternatively an optical monitoring and positioning system could be used for positioning of the membrane 1 on the substrate 2. After the positioning of membrane 1 and substrate 2, in a further step at least three discontinuous welds 5c arranged in a distance to each other along a circumference of the opening 8, for example, three or more welding points. In the next step, the first annular weld 5b circumferentially surrounding the opening 8 is provided. Optionally, one may create the second annular weld 5a, which is substantially concentric with the first annular weld 5b and is arranged radially outward of it or of the discontinuous welds 5c. In one embodiment, the discontinuous welds 5c may coincide with the second annular weld 5a or the first annular weld 5b. The first annular weld 5b may weld and/or melt the membrane 1 and substrate 2 together. The second annular weld 5a may weld and melt the membrane 1 and substrate 2 together.

[0069] In a preferred embodiment, the laser beam is placed on the edge of the opening 8 and is focused on the substrate 2 and/or the membrane 1. The laser beam can be focused on the membrane or the substrate side.

[0070] In a preferred embodiment, the laser beam is put on the membrane 1 side, especially when the thickness of the membrane 1 is smaller than the thickness of the substrate 2. In this case, the membrane 1 is melted in its entirety, and only a part of the substrate 2, for example less than half of the thickness of the substrate 2 or even less than one third of the thickness of the substrate 2 is melted. In another preferred embodiment, the laser beam is focused completely on the surrounding substrate 2 and melts the substrate 2 and the membrane 1 together. In this case, the laser beam does not reach only one of the substrate and the membrane, but both of them.

[0071] In one embodiment, the laser beam is placed on the flange 7 and is focused on the substrate 2 and/or the membrane 1. The laser beam can be focused on the membrane 1 or the substrate 2 side.

[0072] In one embodiment, the laser beam may partly melt the membrane 1 and the substrate 2 so as to form a closed ending of the membrane 1 on the substrate 2. The laser beam may be placed partly on the membrane 1 and partly on the substrate 2. In a preferred embodiment, the laser beam is focused about two thirds on the membrane 1 and about one third on the substrate 2. A good closed ending of the membrane 1 on the substrate 2 with the optional second annular weld 5a can be achieved and extends the life-time of the membrane unit by avoiding any gaps which may be prone to corrosion.

LIST OF REFERENCE SIGNS

[0073] 1 membrane [0074] 2 substrate (support) (optionally including second electrode) [0075] 3 piezo element [0076] 4 first electrode [0077] 5 weld [0078] 5a annular weld [0079] 5b first annular weld [0080] 5c discontinuous welds [0081] 6 effective area [0082] 7 flange [0083] 8 opening [0084] M symmetry axis