Spray Device and Spray Nozzle Unit

Abstract

A spray device has a spray nozzle unit (1), wherein said spray nozzle unit (1) comprises a cavity (5) with an inlet (2) for receiving a pressurized liquid at an operating pressure and an outlet (3) for releasing a liquid spray during operation. A spray nozzle body (10) is fitted sealingly within said cavity (5), having a perforated nozzle layer (14) with at least one spray orifice (16) that extends between an upstream surface and a down stream surface thereof releasing at least one jet of said liquid spray at said downstream surface of said nozzle layer. The spray nozzle unit (1) is provided with a pressure safety device (30) upstream of said spray nozzle body (10). Said pressure safety device (30) comprises a closed burst layer (34) that closes a fluid pathway between said inlet (2) and said spray nozzle body (10) but ruptures once a threshold pressure is exceeded. Said operating pressure exceeds said threshold pressure.

Claims

1. Spray device having a spray nozzle unit, wherein said spray nozzle unit comprises nozzle holder with a cavity having an inlet for receiving a pressurized liquid at an operating pressure and an outlet for releasing a liquid spray during operation, wherein a spray nozzle body is fitted sealingly within said cavity of said nozzle holder, said spray nozzle body having a perforated nozzle layer with at least one spray orifice that extends between an upstream surface and a down stream surface thereof, said downstream surface receiving said pressurized liquid during operation and said at least one spray orifice releasing at least one jet of said liquid spray at said downstream surface of said nozzle layer, wherein a pressure safety device is provided upstream of said spray nozzle body, in that said pressure safety device comprises a closed burst layer that closes a fluid pathway to said spray nozzle body but ruptures once a threshold pressure is exceeded, and wherein said operating pressure exceeds said threshold pressure.

2. Spray device according to claim 1, wherein said pressure safety device comprises a pressure safety body that is fitted sealingly within said cavity of said nozzle holder, residing between said inlet of said nozzle holder and said spray nozzle body.

3. Spray device according to claim 2, wherein said pressure safety body is fitted sealingly in an adapter ring, said adapter ring surrounding the pressure safety body and being sealed to an inner wall of said cavity, particularly by fusion or gluing.

4. Spray device according to claim 3, wherein both said nozzle holder and said adapter ring comprise a plastic, particularly a thermoplastic polymer, more particularly a same plastic.

5. Spray device according to claim 2, wherein said pressure safety device is mounted directly downstream of said inlet, particularly at or near said inlet.

6. Spray device according to claim 2, wherein said spray nozzle body comprises a first plate body having at least one first cavity extending throughout a thickness thereof, wherein said nozzle layer extends over said at least one first cavity, in that said pressure safety body comprises a second plate body having at least one second cavity extending throughout a thickness thereof, wherein said burst layer extends over said second cavity, and wherein said first plate body and said second plate body are fitted sealingly within said cavity of said nozzle holder.

7. Spray device according to claim 6, wherein said first plate body and said second plate body each comprise a silicon body, and wherein said nozzle layer and said burst layer each comprise at least one of a silicon nitride and a silicon oxide layer covering the respective silicon body.

8. Spray device as claimed in claim 6, wherein said second cavity has a polygonal lateral cross section that is spanned by said burst layer.

9. Spray device according to claim 1, wherein said burst layer is provided with at least one burst zone of reduced stress resistance.

10. Spray device according to claim 9, wherein said at least one burst zone comprises at least one burst line along which said burst layer has a reduced thickness.

11. Spray device according to claim 1, wherein a sieve device is fitted within said cavity of said nozzle holder between said pressure safety device and said spray nozzle device, said sieve device having a plurality of sieve passages and being capable of intercepting debris of said burst layer.

12. Spray device according to claim 11, wherein said spray nozzle body comprises a first plate body having at least one first cavity extending throughout a thickness thereof, wherein said nozzle layer extends over said at least one first cavity, in that said sieve device comprises a further plate body having at least one cavity extending throughout a thickness thereof and a sieve layer extending over said cavity, said sieve layer having a plurality of sieve passages extending throughout a thickness thereof, similar or smaller in size but of greater number than said at least one spray orifice, and wherein said first plate body and said further plate body are fitted sealingly within said cavity of said nozzle holder.

13. Spray device according to claim 12, characterized in wherein said first plate body and said further plate body each comprise a silicon body, and wherein said nozzle layer and said sieve layer each comprise at least one of a silicon nitride and a silicon oxide layer covering the respective silicon body.

14. Spray device according to claim 1, wherein a flexible, particularly plastic retention layer is formed over the burst layer, and wherein a depression is formed along a peninsula portion of the plastic layer and burst layer at the area of the cavity, said depression extending through said plastic layer and part of a thickness of said burst layer.

15. Spray nozzle unit of the kind as applied in the spray device according to claim 1.

Description

[0020] The invention also relates to a spray nozzle unit of the kind as applied in the spray device according to the invention and will now be described in further detail with reference to one or more embodiments and an accompanying drawing. In the drawing:

[0021] FIG. 1A is a cross section of a first typical example of a spray nozzle unit for use in or on a spray device according to the invention;

[0022] FIG. 1B is a cross section of a second typical example of a spray nozzle unit for use in or on a spray device according to the invention;

[0023] FIG. 2 is a cross section of a nozzle device as applied in the spray nozzle unit of FIGS. 1A and 1B;

[0024] FIG. 3 is a cross section of a sieve device as applied in the spray nozzle unit of FIGS. 1A and 1B;

[0025] FIGS. 4A, 4B are cross sections of a pressure safety device as applied in the spray nozzle unit of FIGS. 1A and 1B in a closed and open condition, respectively;

[0026] FIG. 4C is a top, planar view of the pressure safety device of FIG. 4A;

[0027] FIG. 6A is a top, planar view of a first alternative embodiment of a pressure safety device for use a spray nozzle unit of a spray device according to the invention;

[0028] FIG. 6B is a cross section of the pressure safety device of FIG. 6A;

[0029] FIG. 7 is a top, planar view of a second alternative embodiment of a pressure safety device for use a spray nozzle unit of a spray device according to the invention;

[0030] FIG. 8 is a top, planar view of a third alternative embodiment of a pressure safety device for use a spray nozzle unit of a spray device according to the invention;

[0031] FIG. 9 is a top, planar view of a fourth alternative embodiment of a pressure safety device for use a spray nozzle unit of a spray device according to the invention;

[0032] FIG. 10A is a top, planar view of a fifth alternative embodiment of a pressure safety device for use a spray nozzle unit of a spray device according to the invention;

[0033] FIGS. 10B, 10C are cross sections of the pressure safety device of figure in a closed and open condition, respectively.

[0034] It should be noticed that the drawings are drafted purely schematically and not to scale. In particular, certain dimensions may have been exaggerated to a lesser or greater extent for sake of clarity and understanding. Corresponding parts have been identified with same reference numerals throughout the drawing.

[0035] FIG. 1A shows an example of a spray nozzle unit as used in a spray device according to the invention. The nozzle unit comprises a solid or assembled nozzle holder 1 of plastic with an internal cavity 5. In the example shown both the cavity 5 and the body itself have a circular cross-section around a centre line 7, but in practice may each have any convenient design and dimension. The nozzle unit body 1 may conveniently be formed form a thermoplastic polymer, like polyethylene or poly-propylene, such that it may be manufactured using a conventional thermo-form process, like for instance blow moulding.

[0036] In the present example, the spray nozzle unit presents a so-called Luer fitting that may be fitted directly on a syringe or the like that contains or supplies a fluid to be sprayed from a container and that is assumed to be known to skilled person. This fluid is received under an operating pressure of several Bar to over 10 Bar at an inlet 2 of the cavity 5, forced by suitably selected pressurizing means, to be delivered to a spray nozzle body 10 that is mounted at an outlet side 3 of the spray nozzle unit.

[0037] The spray nozzle body 10 is depicted in greater detail in FIG. 3 and comprises a silicon plate body 10 (chip) of several hundreds micron thickness that is covered by a silicon oxide layer 12 and a silicon nitride layer 14. The silicon nitride layer 14 has a thickness of one or more micron and spans one or more cavities 15 formed inside the silicon body 10 to create a perforated nozzle layer (membrane) that is provided with at least one spray orifice 16 at the location of each such cavity 15. The cavities 15 have typically a circular cross section of the order of 50 to 100 micron diameter.

[0038] The spray orifices 16 extend throughout the thickness of said nitride layer 14 from an upstream surface to a downstream surface thereof and each have a precisely defined and etched size of a few micron to 10 or more micron. During operation, pressurized fluid that is received by the cavity 5 of said nozzle unit will enter the cavities 15 of said nozzle chip 10 and will pass through these nozzle orifices 16. At the downstream outlet side 3 the liquid will then emanate in the form of a fluid ray that breaks up (so called Rayleigh breakup) into a droplet train of fluid droplets of a well controlled droplet size. This will create a spray (mist) of droplets within an very well defined droplet size distribution.

[0039] Preceding the spray nozzle, i.e. upstream, is a sieve device 20 having a plurality of sieve passages 26 of equal or smaller size than the spray nozzle orifices 16, as shown in greater detail in FIG. 3. These sieve passages protect the nozzle body against clogging as particles or other bodies that might otherwise block a nozzle orifice are effectively blocked and intercepted by the sieve device. Like the nozzle device 10, the sieve device 20 comprises a silicon body (chip) of the order on a few hundred micron thickness in which a cavity 25 is created running throughout its thickness. On top of this silicon body 20 are a silicon oxide layer 22 and a silicon nitride layer 24. The latter extends over said cavity 25 to form a sieve plate having a great number of sieve passages 26 that are precisely etched throughout its thickness. This thickness may exceed that of the nozzle layer 14 to gain additional strength. The number of passages 26 greatly outnumbers the number of nozzle orifices 16 in order to guarantee an uninterrupted delivery of fluid to the nozzle body 10.

[0040] Both the nozzle body 10 and the sieve device 20 allow a free flow of both fluid from within the device to the environment as well as of ambient air to within the cavity 5 of the nozzle unit. The latter may be contaminated with micro-organisms, like bacteria, fungi and viruses. In order to prevent evaporation of liquid from the pre filled syringe via the open nozzle chip and to prevent microbial ingrowth into the container, a pressure safety device 30 is placed upstream of the sieve device 20 within the cavity 5. This pressure safety device is shown in greater detail in FIGS. 4A and 4B. The pressure safety device contains a closed burst layer 34 extending over an opening 35 that is in direct communication with the inlet 2 of the nozzle unit. The closed burst layer 34 initial seals the flow path to the syringe completely, to prevent premature evaporation of liquid and to protect the content of the syringe or other container to which the nozzle unit is mounted against microbial intrusion, see FIG. 4A.

[0041] Once a threshold pressure of the burst layer is exceeded, however, it will burst or rupture thus opening said flow path, see FIG. 4B. The burst layer 34 is configured to have a threshold pressure below a normal operating pressure of the spray device in which the nozzle unit is applied, for instance between 2 and 3 Bar, such that this opening of the flow path will occur automatically once the pressure means of the device are actuated by a user and a pressurized liquid is forced under said operating pressure against said burst layer. This will open the flow path to the nozzle device 10 causing the spray device to generate an undisturbed spray. This way the spray nozzle unit has an internal lidding foil, or a ‘lidding chip’, which is opened at first use. This is a one-time event. At the first use of the spray nozzle unit, it is ‘deflowered’ but during shelf life there is no open path between the container content and the outside world.

[0042] In this example also the pressure safety device has been formed using a similar semiconductor or micro machining manufacturing technology that has also been used for the formation of the nozzle chip 10 and sieve chip 20. As such the safety device 30 comprises a silicon semiconductor body with a central cavity 35 that is spanned by a silicon nitride burst layer 34 of appropriate thickness to allow rupture of this layer below a the operating pressure of the spray device. The nitride layer 34 is given a thickness of 1 micron or less to assure breakage below the operating pressure. In between the nitride layer 34 and the silicon body is a thin silicon oxide layer 32. In this example the thickness of the burst layer is chosen below the respective thicknesses of the sieve layer 24 and nozzle layer 14 that are both dimensioned to withstand said operating pressure.

[0043] Because of the constructional similarity between the pressure safety device 30 and the nozzle device 10, not only a similar manufacturing technique but also similar pick-and-place methods and equipment may be used during assembly of the nozzle device for properly positioning and fastening the pressure safety device within the cavity 5 of the nozzle unit. Any potential debris from the rupture of the burst layer 34 will be intercepted by the sieve device 20 and, hence, will not influence the spray behaviour, nor will it be inhaled, ingested or otherwise be administered to the user of the spray device. This order of placement also enables an in line testing with air or another gas of the nozzle device 10 and sieve device 20 after assembly. The safety device 30 may in that case be mounted in place afterwards, followed by a porous pre-filter 4 of an appropriate woven or non-woven polymer fabric, like fluffy polypropylene.

[0044] An alternative embodiment of a spray nozzle unit with such an integrated pressure safety device is shown in FIG. 1B. Also in this case the pressure safety device contains a silicon semiconductor body with a nitride burst layer, similar to that as in the device of FIG. 1A. In this example, however, the silicon body is not mounted directly in the cavity 5 of the nozzle holder 1, but fitted in a surrounding adapter ring 33. This adapter ring may be formed of a thermoplastic polymer, particularly the same or a similar plastic as the nozzle unit itself, and crosses the space between the smaller silicon body and the internal wall of the cavity 5. This saves chip area, hence, cost, but moreover allows proven fusion techniques, like melting and gluing, for mounting and sealing the safety device 30 within the cavity after the nozzle unit has been tested with the nozzle body 10 and sieve body 20 in place. In this case the pressure safety device is, moreover, placed upstream of the porous pre-filter 4, but might also be positioned downstream of the pre-filter 4.

[0045] The pressure safety device of FIG. 4A is shown in top view in FIG. 5A with the burst layer 34 extending over the central cavity 35. In order to promote rupture of the burst layer one or more weakening zones or lines 38 of reduced stress resistance may be formed in the burst layer 34 as shown in FIGS. 6A, 7 and 8 in top view and in FIG. 6B in cross section. As shown in FIG. 6B these lines or zones are created by a local thickness reduction 38 along these lines or zones. This will result in a local weakening of the burst layer and a more controlled rupture along these lines or zones. Alternatively or additionally also the central cavity 35 may be given a polygonal lateral cross section as shown along the embodiment of FIG. 9 that will lead to a stress concentration in the vicinity of the corners.

[0046] FIG. 10A-10C show in planar top view and cross section, respectively, a fifth embodiment of a pressure safety device for use in a spray device according to the invention. The configuration of this embodiment is similar to that of FIG. 6A and 6B in that it comprises a semiconductor silicon body 30 on top of which an silicon oxide layer 32 is grown and a silicon nitride burst layer 34 is deposited with a thickness of the order on a few micron. In this embodiment, however, the structure is coated or otherwise covered by a flexible thermoplastic polymer layer 42 that sticks to the nitride layer 34. In this case parylene is used for the polymer layer 42 with a thickness of only a few micron or even less than a micron.

[0047] A breaker line or zone 44 has been formed in the nitride burst layer 34 in the form of a depression or ditch 44 that extends almost along the entire periphery of the cavity 35 except for a relatively small hinge portion 46. Said ditch extends entirely across the plastic layer 42 to create a peninsula like central portion 45 of the plastic layer and said nitride layer 34. The ditch 44 delivers a weakness in the nitride burst layer 34 causing the nitride layer 34 to burst at a pressure of the order of a few bar, which is below the normal operating pressure of the spray device.

[0048] The plastic layer 42 on top, however, has sufficient flexibility and tensile strength to withstand this pressure and will hinge along the hinge portion as shown in FIG. 10C, while keeping the central portion 45 of the nitride layer 34 to it. This will avoid the loss of any noticeable debris of the nitride burst layer 34 once it bursts, while creating a considerable opening 35 in the support body 30. Due to this enhanced retention of material of the burst layer 34 this embodiment might also be applied down stream of the nozzle body without the risk that debris of the burst layer will interfere with, or enter into the spray that is to be generated by the spray device.

[0049] In all cases the closed burst layer effectively closes the pathway between any liquid to be sprayed and the environment before initial use of the device. The strength of the burst layer is, however, chosen such that it will burst once it is exposed to the normal operating pressure of the spray device to which the spray nozzle unit is mounted. This will automatically open said pathway without any necessary additional interference by the user and renders the device ready for use.

[0050] Although the invention has been describes hereinbefore with reference to merely a few specific embodiments, it will be clear that the invention is by no means limited to these examples. Instead many alternatives and variations are feasible for a skilled person without departing from the scope and spirit of the present invention. As such the pressure safety device need not be placed in the nozzle holder or spray nozzle unit but may also reside upstream thereof, for instance between a container, containing the fluid to be sprayed, or pumping means of the spray device and the spray nozzle unit or holder.

[0051] Other designs, materials and dimensions may be used for the safety device 30 and, particularly, the burst layer 34. This also concerns mutatis mutandis the sieve device and the nozzle device as well as the nozzle unit. Particularly the beaker layer might as well comprise a polymer foil or metal foil that is attached to a support body, extending over a central opening. Also other thermoplastic materials can be used than parylene, to cover the burst layer and to form one or more flexible hinges. The plastic materials can be anchored in the micro machined silicon structure by forming anchoring holes or the like. Preferably use is made of a bio-compatible plastic in case of medical appliances.

[0052] Also more that one cavity may be formed in the support body of the safety device, spanned by the same or individual burst layers, to implement several parallel pathways through the device, again to assure breakage of at least one of them below the operating pressure.

[0053] In the example a so called Luer type nozzle unit has been shown for placement on a syringe. Alternative the nozzle unit may be give any appropriate design to match a particular spray device, which might, for instance, be a spray cannister, bottle, ampul or any other container holding a certain amount of fluid to be pressurized by means of appropriate pressurizing means of the spray device.