Atomizer device

Abstract

The atomizer device for atomizing pressurized liquid comprises an atomizer body (14) having one or more atomization openings through which mist formed from the liquid escapes during operation. The device comprises a valve device (20, 30) upstream of the atomizer body. The valve device (20, 30) comprises a valve cavity (31) having a valve body (32) and a spring chamber (21) in which a spring means (22) is compressible against spring tension. The valve body (24) receives the liquid in the valve cavity (31) over a first operating cross section (D1), which is smaller than a second operating cross section (D2) of the spring chamber (21) in which the spring means (22) is compressible.

Description

Technical Field

[0001] The present invention is an atomizer device for atomizing pressurized liquid, comprising an atomizer body having one or more atomizing openings through which mist formed from the liquid flows during operation, and a valve device provided upstream of the atomizer body, the valve device opening from a predetermined threshold of the hydraulic pressure exerted thereon by the liquid.

Background Art

[0002] Atomizer devices of the type described above are used to atomize suitable liquids. These liquids are pharmaceuticals, cosmetics, therapeutic liquids, which are inhaled or otherwise brought into contact with the body after being atomized as a fine mist. However, there are many applications with more technical nature where it is desired to apply or deposit the liquid as a finely dispersed mist. The liquid is pressurized by pump means provided for this purpose and conveyed to the atomizer body in a pressurized state. The atomizer body comprises one or more atomizing openings through which the liquid is extruded under increased pressure in the form of a series of continuous droplets to form a finely dispersed mist.

[0003] The physical mechanism underlying such atomization varies depending on the nature of the atomizer body and the dimensions of the atomizing openings. An important mechanism is the so-called Rayleigh breakup. The atomizer device according to the present invention is particularly suitable for generating a so-called microjet spray of very fine droplets having a controlled predetermined size based on this mechanism. Such a microjet spray is usually formed by a number of individual jets, each coming from an individual atomizing opening. The cross-sectional area of these openings is from a few micrometers to less than 1 micrometer. Each jet of the spray initially consists of a monodisperse primary droplet train formed from the liquid by Rayleigh breakup. As a result, the successive droplets are initially substantially the same size and leave the spray orifice in the same direction.

[0004] The diameter of the primary droplets is usually 1.85 to 2.0 times the diameter of the atomizing orifice and often falls within the micrometer range. By providing the atomizing orifice of the atomizer device body with high precision and the same size, it is possible to form a mist such that the variation in droplet size at the atomizing orifice is particularly small. Also, even if the average droplet diameter increases due to the coalescence of droplets, the final droplet diameter distribution is maintained within a relatively narrow range. Thus, such a mist is particularly suitable for severe applications where the individual droplet size affects the spray effect.

[0005] In order to obtain a correct spray pattern, it has actually been found that, in addition to the dimensions and properties of the atomizer body, the pressure applied to the liquid is also an important factor. Below a determined pressure, the liquid cannot be decomposed into droplets, and instead, so-called "dripping" occurs where the liquid drips from the surface of the atomizer body. In particular, the finer the mist to be formed by making the spray orifice smaller, the higher this threshold value becomes, and it can reach about 8 to 10 atmospheres. To prevent this, the atomizer device is provided with a valve body on the upstream side, and the liquid supply to the atomizer body is closed below this pressure and only opens after reaching this threshold value.

Summary of the Invention

Problems to be Solved by the Invention

[0006] With the miniaturization of atomizer devices progressing, it is considered a problem to provide such a valve device that operates at high pressure. As its dimensions become smaller, existing valve devices already give up below such a hydraulic level, thereby resulting in an undesirable spray pattern or no mist at all. The present invention aims to provide an atomizer device of the type described above that provides a spray pattern only when a sufficiently high threshold pressure is reached, particularly in the case of further miniaturization.

Means for Solving the Problems

[0007] To achieve the above object, according to the present invention, in an atomizer device of the type described above, the valve device includes a valve cavity in which a valve body is movable and lies sealed over the entire circumference with respect to its wall, and a spring chamber on the side surface of the valve body away from the valve cavity, where spring means is compressible against spring tension. The valve body receives the counter pressure of the spring means and closes the liquid flow path between the valve cavity and the atomizer body in the first closed state. The valve body can be brought into a second state under the influence of the pressure exerted by the liquid. At this time, the liquid flow path is released, and the liquid acts on the valve body over a first operating cross-section within the valve cavity, and the first operating cross-section is smaller than a second operating cross-section where the valve body acts on the spring means within the spring chamber.

[0008] The present invention is based on the insight that by narrowing the operating cross-section of the valve cavity, thereby narrowing the area where the liquid acts on the valve body, the play in the force exerted on the spring means from the valve body can be reduced. As a result, the valve body can withstand a greater liquid pressure, enabling further miniaturization of the entire atomizer device. In particular, the first operating cross-section is here at least substantially equal to the cross-section of the valve cavity, and the second operating cross-section is at least substantially equal to the cross-section of the spring chamber, whereby the diameter ratio between the spring chamber and the valve cavity is at least substantially equal to the transmission ratio between these forces.

[0009] In a preferred embodiment, in the atomizer device according to the present invention, the valve cavity has an inlet on the upstream side, is adjacent to the spring chamber at the distal side surface on the opposite side, and a valve opening that opens into the liquid flow path is provided in the wall of the valve cavity. The valve body closes the valve cavity upstream of the valve opening in the first closed state and is located at the distal side surface beyond the valve opening in the second state. The valve body functions as a closing piston within the valve cavity that separates the inlet from the valve opening in the first state and enables an open communication between the inlet and the valve opening in the second state.

[0010] In a further preferred embodiment, the atomizer device is characterized in that the valve body comprises a flexible cup-shaped skirt which is sealingly disposed against the wall of the valve cavity on the side facing the inlet of the valve cavity. Due to the flexibility and (hollow) shape of the skirt, when the liquid pressure increases, the skirt is pressed more strongly against the wall of the valve cavity. It has been found that in this way a particularly effective seal against the wall of the valve cavity can be obtained.

[0011] In a further preferred embodiment, the atomizer device according to the invention comprises an atomizer holder part which forms an atomizer cavity bounded by an outlet side surface by the atomizer body, a spring holder part which forms a spring chamber with spring means and whose distal outer end is disposed within the atomizer cavity, and a valve holder part which forms a valve cavity with a valve body and whose distal outer end projects into the spring chamber, and the spring holder part is sealingly disposed against the wall of the atomizer cavity. It comprises a valve holder part which forms a valve cavity containing the valve body and whose distal outer end projects into the spring chamber, and the spring holder part is sealingly disposed against the wall of the atomizer cavity and the valve holder part is sealingly disposed against the wall of the spring chamber. In this way, the atomizer device is composed of an assembly of a number of individual holder parts which can be arranged relative to each other in a simple manner as part of the assembly of the atomizer device. The desired liquid tightness between the holder parts can be achieved by interposing a suitable seal. A further preferred embodiment of the atomizer device according to the invention is characterized in this respect in that the spring holder part is clamped tightly against the wall of the atomizer cavity and the valve holder part is clamped tightly against the wall of the spring chamber. For such press-fitting, the assembled article can be obtained simply by pushing the parts into each other.

[0012] From the perspective of transmitting the pressure of the liquid to the spring means, a further specific embodiment of the atomizer device according to the present invention is characterized in that the valve body consists of a relatively rigid disk, on which the spring means is supported in the spring chamber, and the disk body hits the edge of the valve cavity in the first closed state. For the connection between the disk and the valve body, it is also possible to use an interlocking clamp according to the further assembly of the device.

[0013] In a more preferred embodiment, the atomizer device according to the present invention is characterized in that the spring chamber of the spring holder part has airtightness, and at least in the second state, an air portion is confined therein. This air portion thereby resists further compression, and here it gives a counter-pressure (reverse pressure, opposing pressure) to the valve body, which is converted into a threshold value imposed by the liquid pressure.

[0014] A further specific embodiment of the device according to the present invention is characterized in that the atomizer body is built into the atomizer holder of the atomizer unit. The relatively small atomizer body is first assembled here together with the atomizer holder into a more easily handled atomizer unit. This can be arranged in the atomizer holder part of the atomizer device. As the spring means, a coil spring, especially a metal one, is advantageously used. Its continuous miniaturization will undoubtedly result in a lower spring constant, but due to the narrowing of the valve cavity associated therewith, thanks to the present invention, it can withstand a sufficiently high liquid pressure.

[0015] Hereinafter, the present invention will be further described based on exemplary embodiments and the accompanying drawings.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 2A

Figure 3A

Figure 3B

Figure 4

Embodiments for Carrying Out the Invention

[0017] Also, it should be noted that the figures are purely schematic and are not necessarily drawn to the same scale. In particular, some dimensions may be exaggerated more or less for clarity. In the figures, corresponding parts are given the same reference numerals.

[0018] The atomizer device shown in FIG. 1 is substantially made of plastic. Thus, as also shown in FIG. 2, the atomizer device is composed of a polyethylene atomizer holder part 10 having a spray opening 13 in which the atomizer unit 12 is arranged. The atomizer unit 12 is composed of a plastic atomizer holder as a casing in which an atomizer body 14 (not further shown) is arranged. This atomizer body communicates with the atomizer cavity 11 in the atomizer holder 12 and the atomizer holder part 10 on the one hand, and communicates with the spray surface in the spray opening 13 on the other hand, and discharges a liquid mist there.

[0019] The atomizer device has a spring holder part 20 and a valve holder part 30, both made of polypropylene, arranged continuously upstream of the atomizer holder part 10. The spring holder part 20 has a spring chamber 21, in which spring means in the form of a coil spring 22 made of steel or other suitable material or metal alloy is accommodated. Except for the opening for receiving the valve holder part, the spring chamber is completely airtight and air is trapped therein. A groove 26 is arranged outwardly on the wall of the spring holder part as part of the liquid flow path between the cavity of the atomizer device and the inlet 40 of the device.

[0020] This inlet 40 is upstream of the valve holder part 30. Like the other holder parts, this part is also manufactured from polypropylene, and individual injection molding parts are used for each of the parts 10, 12, 20, 30. The valve holder part 30 is here in a particularly hard form to prevent its deformation, and has a valve cavity 31 extending between the inlets 40 and a valve body 32 movably and closely received within the valve cavity. The valve body 32 is also entirely formed from a suitable plastic such as polypropylene, in which case a relatively hard distal part 32 and a relatively flexible proximal part connecting thereto to form a hollow skirt 34 are utilized. This skirt 34 provides a desired liquid seal against the inner wall of the valve cavity 31. Further, the valve body has a shaft 36 on the distal side surface, and this shaft projects from the valve holder part 30 into the spring chamber 21. On it, a disk 38 for supporting the spring 22 is provided, which is manufactured from a very hard material such as polyoxymethylene (POM) to prevent deformation under the influence of the spring pressure.

[0021] The wall of the valve cavity 31 forms a valve opening 33 continuous with the valve holder portion 30, which, in the assembled state, coincides with the liquid flow path 24 in the wall of the spring holder portion. Thanks to the exact dimensional setting of the various components shown in Fig. 2, they fit seamlessly with each other and the whole can be assembled purely by press-fitting them into each other (see also Figs. 3A and 3B). Registration marks 25, 35 in the form of shallow recesses for this purpose serve here as guides for the correct relative orientation.

[0022] Fig. 3A shows the atomizer device in a first closed state. The disk 38 supports here the edge 37 of the valve cavity 31, and the spring 22 is clamped between the disk 38 and the distal outer end of the spring chamber 21. As can be seen more clearly in Fig. 2, the liquid flow path 24 opens into the atomizer cavity 11 on the downstream side. On the upstream side, the liquid flow path 24 coincides with the valve opening 33, but this opening is still separated from the inlet 40 by the valve body 32. Thus, there is no open path from the inlet 40 to the liquid flow path 24 to the atomizer cavity 11. The valve body 32 is held in this position by the interposition of the spring 22 and the disk 38.

[0023] When pressurized atomizing liquid enters from the inlet 40, a force acting against the spring force of the spring 22 acts on the valve body. This force is approximately proportional to the operating cross-section D1 of the valve bodies 32, 34 and thus also to the operating cross-section D1 of the valve cavity 31. This cross-section D1 is considerably smaller than the corresponding operating cross-section D2 of the spring chamber 21, so that only a limited force from the liquid is transmitted to the spring in proportion to the ratio D1:D2.

[0024] As a result, only when the liquid pressure is about 20 bar, the spring is sufficiently compressed for the first time, and the valve body 32 with the skirt 34 can move far beyond the valve opening 33. Until this state is reached, referring to FIG. 3B, there is no connection of the liquid that opens between the valve opening 33 and the inlet 40 of the valve cavity 31, and the liquid can reach the atomizer cavity 11 having the atomizer body 14 through the liquid flow path 24. Therefore, this order of minimum liquid pressure sufficient to ensure the good operation of the atomizer device and form fine mist is always applied to the atomizer body.

[0025] FIG. 4 shows the pressure profile of the present valve device. According to this, the valve device does not open until the pressure of about 22 bar indicated by the arrow P1, and is closed at a pressure of about 12 bar or less indicated by the arrow P2. This hysteresis is probably caused by the frictional effect between the valve bodies 32, 34 and the inner wall of the valve cavity, but it has no further influence on the correct operation of the atomizer device. The closing pressure of 12 bar is still high enough to obtain a perfect spray pattern.

[0026] These thresholds P1 and P2 can be imposed despite the relatively small dimensions of the relevant parts. In this exemplary embodiment, the diameter D2 of the spring chamber is only about 4 mm, and the relatively small spring 22 with sufficient strength can be arranged therein. If the liquid acts directly thereon, this spring would not be able to withstand the pressure of the above order within the approximate dimensions. When the diameter D1 is about 2 mm, the valve cavity becomes quite small, whereby the force applied to the spring 22 is halved, and still the above-sized threshold can be imposed.

[0027] Although the present invention has been further elucidated with reference to only a single exemplary embodiment above, it will be apparent that the present invention is in no way limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the present invention for those skilled in the art. Instead of using polypropylene for all or part of the plastic part of the atomizer device, it is also possible to use one or more other plastics or other materials such as metals. The dimensions described are given only by way of example and can also be selected in different ways for specific applications. The same applies to the ratio of the two cross-sections D2:D1. By appropriately setting and adjusting this ratio, a desired threshold value of the hydraulic pressure can always be set and pressed by a predetermined spring means.

Claims

1. An atomizer device for atomizing pressurized liquid, comprising: an atomizer body having one or more atomizing openings through which mist formed from the liquid flows during operation; and a valve device provided upstream of the atomizer body and opening when a predetermined threshold value of the liquid pressure exerted by the liquid is exceeded. The valve device comprises: a valve cavity in which a valve body is movably provided, the valve cavity being provided on a side surface of the valve body away from the valve cavity; and a spring chamber provided with spring means compressible against the tension of a spring, the valve cavity having a first cross-section and the spring chamber having a second cross-section. The valve body receives the counterpressure of the spring means and, in a first state, closes the liquid flow path between the valve cavity and the atomizer body. The valve body is urged to a second state under the influence of the pressure exerted by the liquid. The liquid flow path is released. The liquid in the valve cavity acts on the valve body across the first cross-section, and the cross-sectional area of the first cross-section is smaller than the cross-sectional area of the second cross-section where the valve body acts on the spring means in the spring chamber. An atomizer device characterized by this.

2. The valve cavity has an inlet on the upstream side and is adjacent to the spring chamber on the distal side surface on the opposite side. The valve opening opening into the liquid flow path is provided in the wall of the valve cavity. The atomizer device according to claim 1, wherein the valve body closes the valve cavity upstream of the valve opening in the first state and is located on the distal side surface beyond the valve opening in the second state.

3. The atomizer device according to claim 2, wherein the valve body is provided with a flexible cup-shaped skirt that adheres to the wall of the valve cavity on the side facing the inlet of the valve cavity.

4. An atomizer holder portion that constitutes an atomizer cavity bounded by an outlet side surface by the atomizer body; a spring holder portion that constitutes the spring chamber provided with the spring means and has a distal outer end disposed in the atomizer cavity; a valve holder portion that constitutes the valve cavity incorporating the valve body and has a distal outer end protruding into the spring chamber. The atomizer device according to any one of claims 1 to 3, characterized in that: The spring holder portion is disposed in a sealed manner on the wall of the atomizer cavity. The valve holder portion is disposed in a sealed manner on the wall of the spring chamber.

5. The spring holder portion is in close contact with the wall of the atomizer cavity, The atomizer device according to claim 4, wherein the valve holder portion is in close contact with the wall of the spring chamber.

6. The valve body is composed of a relatively rigid disk body on which the spring means is supported in the spring chamber, and the disk body hits the edge of the valve cavity in the first state. The atomizer device according to claim 4 or 5.

7. The atomizer device according to claim 4, 5 or 6, wherein the spring chamber of the spring holder portion has high airtightness, and air is confined at least in the second state.

8. The atomizer device according to any one of claims 1 to 7, wherein the atomizer body is built in an atomizer holder of an atomizer unit.

9. The atomizer device according to any one of claims 1 to 8, wherein the spring means is constituted by a coil spring.

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