SENSOR FOR DETERMINING THE OSCILLATING FREQUENCY IN A FLUIDIC OSCILLATING NOZZLE AND A METHOD USING THE SENSOR

Abstract

A sensor for determining the oscillating frequency in a fluidic oscillating nozzle and provides an oscillating nozzle, comprising a fluidic oscillator with inlet and outlet and a main channel and at least one control passage surrounding the main channel, and a splitter comprising at least two splitter channels which is attached to the outlet of the fluidic oscillator, wherein the sleeve of at least one of the at least two splitter channels comprises partially a flexible foil. The invention also relates to a method for monitoring a dispensed fluid jet, comprising the steps of providing an oscillating nozzle as described above; and injecting a fluid jet and in parallel determining the oscillation frequency by determining the deformation changes of the flexible foil.

Claims

1. An oscillating nozzle, comprising a fluidic oscillator with inlet and outlet and a main channel and at least one control passage surrounding the main channel; and a splitter comprising at least two splitter channels which are attached to the outlet of the fluidic oscillator, wherein a sleeve of at least one of the at least two splitter channels comprises partially a flexible foil.

2. The nozzle of claim 1, wherein the outlet of the fluidic oscillator before the splitter is a gorge portion.

3. The nozzle of claim 1, wherein the outer surface of the flexible foil is coated with a conductive material.

4. The nozzle of claim 3, wherein two counter electrodes are arranged with a predefined distance next to the conductively coated outer surface of the flexible foil.

5. The nozzle of claim 4, wherein the two counter electrodes are part of a circuit board.

6. The nozzle of claim 3, wherein a single counter electrode is configured to be in a distance next to the conductively coated outer surface of the flexible foil so that the conductive coating of the outer surface of the flexible foil and a surface of the single counter electrode are configured to measure a capacity change.

7. The nozzle of claim 3, wherein an inductive sensor is arranged with a predefined distance next to the conductively coated outer surface of the flexible foil.

8. The nozzle of claim 1, wherein the flexible foil is on the outer surface of the sleeve surrounded by a sealed housing and a pressure sensor is arranged within the said sealed housing.

9. The nozzle of claim 1, wherein each of the at least two splitter channels is partly covered with a flexible foil and each of the flexible foils is surrounded by a sealed housing, wherein the housings are connected by a channel which comprises a differential pressure sensor.

10. The nozzle of claim 1, wherein a piezo element or a piezo foil is attached to the outer surface of the flexible foil.

11. The nozzle of claim 1, wherein a strain gauge is attached to the outer surface of the flexible foil.

12. The nozzle of claim 1, wherein an acceleration sensor is attached to the outer surface of the flexible foil.

13. The nozzle of claim 1, wherein the outer surface of the flexible foil is coated with a reflecting material.

14. The nozzle of claim 13, wherein a light source illuminates the reflective outer surface of the flexible foil and a light sensor detects the amount and/or direction of reflected light.

15. The nozzle of claim 1, wherein the flexible foil is made of a translucent material and a light source which is arranged outside the splitter channel illuminates through the flexible foil the inner volume of the splitter channel and a light sensor is arranged inside the splitter channel opposite the translucent flexible foil for detecting the amount and/or direction of light passing through the foil.

16. A method for monitoring a dispensed fluid jet, comprising the steps of: providing an oscillating nozzle comprising: a fluidic oscillator with inlet and outlet and a main channel and at least one control passage surrounding the main channel, and; a splitter comprising at least two splitter channels which are attached to the outlet of the fluidic oscillator, wherein a sleeve of at least one of the at least two splitter channels comprises partially a flexible foil; and injecting a fluid jet and in parallel determining the oscillation frequency by determining the deformation changes of the flexible foil.

17. The method of claim 16, wherein the oscillation frequency of the fluid is determined by measuring capacity changes, electromagnetic induction, pressure changes, differential pressure changes, piezoelectricity, changes of the shape of the flexible form and acceleration on the surface of the flexible foil or refractive changes of a translucent flexible foil.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0042] The invention will be described based on figures. It will be understood that the embodiments and aspects of the invention described in the figures are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with a feature of a different aspect or aspects of other embodiments of the invention, in which:

[0043] FIG. 1 shows an embodiment with a flexible foil.

[0044] FIGS. 2A and 2B show a concave or convex shape of a foil.

[0045] FIG. 3 shows an embodiment measuring capacity changes.

[0046] FIG. 4 shows an embodiment with a single counter electrode.

[0047] FIG. 5 shows an embodiment for an inductive measurement.

[0048] FIG. 6 shows an embodiment for determining pressure changes.

[0049] FIG. 7 shows an embodiment for differential pressure determination.

[0050] FIG. 8 shows an embodiment using a piezo element.

[0051] FIG. 9 shows an embodiment with expansion elements.

[0052] FIG. 10 shows an embodiment employing an acceleration sensor.

[0053] FIGS. 11A and 11B show an optical detection using a foil which has a reflective coating.

[0054] FIG. 12 shows an embodiment where a change of the focal length is use for determining the deformation of the foil.

[0055] FIG. 13 shows alternatives to the splitter channel shape.

[0056] FIGS. 14A and 14B show an embodiment with flexible foils that are arranged within the splitter channel in two layers.

DETAILED DESCRIPTION OF THE INVENTION AND THE FIGURES

[0057] The technical problem is solved by the independent claims. The dependent claims cover further specific embodiments of the invention.

[0058] The invention relates to a device and method for determining oscillation frequencies in a fluidic oscillating nozzle.

[0059] The term “outer” refers to the outside of a channels sleeve, so that an outer surface is directed towards the surrounding environment and the inner surface is directed towards the inner part of a channel.

[0060] The term “conductive material” refers to any material that is suitable for conducting electricity or an electrical potential.

[0061] The term “predefined distance” refers to a distance between electrically conductive surfaces so that they are separated by an air gap for instance. Such a predefined distance may allow or prohibit a contact of the separated conductive surfaces.

[0062] A basic idea of the present invention is the at least partly replacement of the cover in the area of the two splitter channels of an oscillating nozzle with a flexible foil. The foil or film replaces at least partly the sleeve of at least one of the splitter channels and can basically be applied in different areas of the splitter or oscillator. Several foils and thus several measuring points are also conceivable.

[0063] FIG. 1 shows an oscillating nozzle 1 which comprises a fluidic oscillator 2 with an inlet 3 and an outlet 4. A splitter 5 is attached to the outlet 4 of the fluidic oscillator 2. The splitter 5 has two splitter channel 7 merging an outlet 8 of the splitter. The sleeve of one of the splitter channels 7a, 7b is partly replaces by a flexible foil or film 9. The flexible foil 9 may be arranged at any place of the oscillating nozzle but preferably in the splitter sleeve as outlet 4 of the fluidic oscillator may be formed as a narrowing. When a fluid, e.g., a liquid, flows through the first splitter channel 7a, an overpressure is created, which deforms the foil convex. When the liquid flows through the second splitter channel 7b, a negative pressure is created in the first splitter channel 7a, which causes the film to deform concave. Thereby the film pulsates with the oscillation frequency.

[0064] The flexible foil 9 is at least partly replacing the sleeve 11 of the splitter channel and will with respect to the changing pressure in the splitter channels alternately be convex (FIG. 2A) if the pressure in the splitter channel is high or concave (FIG. 2B) if the pressure in the splitter channel is low. This deformation or the change in the direction of the deformation of the foil can be measured, and the result may be used as a measure for the actual oscillation frequency. The measurement of the deformation can be done by different measuring principles, which will be described in detail below.

[0065] By separating the fluidic oscillator and the measuring chamber (i.e., the splitter arrangement with flexible foil) of an oscillating nozzle, the dimensioning of the actual oscillating nozzle remains flexible and is not restricted by other requirements resulting from the measurement. The pressure differences and thus the deformation of the foil can be increased by a narrowing behind the splitter.

[0066] The deformation of the foil may be measured by determining capacity changes (FIG. 3). In this process, the flexible foil 9 is coated/vaporized to be electrically conductive by applying a conductive layer 13. Together with two counter-electrodes which are e.g., part of a printed circuit board, a capacitor 15 is formed with an air layer in between as dielectric. The capacity of this capacitor 15 depends directly on the distance between the electrodes. The deformation of the film therefore changes the distance and thus the capacitance, which can be measured by a suitable electronic circuit which is part of a circuit board 17, e.g., an electric resonant circuit. This method has the advantage that the conductive layer 13 on the flexible foil 9 does not have to be contacted directly electrically.

[0067] It is also envisaged that a capacitance measurement with only one counter electrode 14 is used (FIG. 4). This method works on the same principle, but with only one counter-electrode 14, which is why the second electrode is formed by the conductive layer 13 on the flexible foil 9 and must therefore be directly electrically contacted.

[0068] FIG. 5 shows an embodiment for an inductive measurement which is achieved using an inductive sensor 19 which is arranged above the flexible foil 9 that is covered with a conductive layer 13.

[0069] FIG. 6 shows an embodiment for determining pressure changes caused by the deformation of the flexible foil 9. In this process the area above the film is hermetically sealed by a housing 20 and the pressure change in the resulting chamber 20a caused by the deformation of the flexible foil 9 is measured by pressure sensor 21.

[0070] Another possibility for measuring the changing deformations of the flexible foil 9 is a differential pressure determination (FIG. 7). This method is an extension of the simple pressure measurement method. Here, in both channels of the splitter, a first splitter channel 7a and a second splitter channel 7b, the sleeve of the first splitter channel 11a and the sleeve of the second splitter channel 11b, respectively, are at least partly covered with a flexible foil 9. These two channels are flowed through with a 180° phase shift, which is why the associated foils always deform in opposite directions. If pressure measuring chambers 20a are placed above the flexible foils 9 in each splitter channel and the pressure difference between these chambers is measured by a differential pressure sensor 22, the oscillation frequency can be measured. In contrast to the simple pressure measurement, the amplitude of the measured signal doubles, which leads to a more robust system.

[0071] A piezo element 24 may also be used for determining the deformation of the flexible foil 9 (FIG. 8). A piezo element 24 deforms when an electrical voltage is applied or generates an electrical voltage when it is mechanically deformed. In contrast to the capacitive process, the flexible foil 9 is not conductively coated in this embodiment, but it is directly bonded to a piezo foil 24. Alternatively, the piezo film 24 could also be used directly as a flexible foil 9 for at least partly replacing the sleeve 11 of the splitter channel. The voltage generated by the deformation of the piezo element 24 is then again identical to the oscillation frequency of the nozzle

[0072] Expansion elements 26 may also be used for determining differences in the deformation of the flexible foil 9 (FIG. 9) which at least partly replaces the sleeve 11 of the splitter channel. An expansion element 26 changes its electrical resistance when it is deformed. This method is similar to the piezo electrical method, described above, with the difference that a change in resistance is detected.

[0073] Another possibility for determining the deformation of the foil which at least partly replaces the sleeve 11 of the splitter channel, is the use of an acceleration sensor 28 (FIG. 10). An accelerometer or the acceleration sensor 28 is mounted directly on the flexible foil 9 and can thus directly measure the vibration/pulsation/deformation of the flexible foil 9. However, this method is probably also susceptible to vibration in the direct environment.

[0074] It is also conceivable to determine optically the bending of the deformed foil 9 (FIGS. 11A and 11B). In this process, the flexible foil 9 is coated with a reflective coating 34. By the suitable arrangement of a light source 30 and a light sensor 32 the deformation of the flexible foil 9 can be measured, because sometimes more times less light is reflected into the sensor 32 or the reflected light hits at different places of the sensor 32 or when using several sensors 32 at different positions.

[0075] An alternative to the above-described optical determination is to employ a method where the light source 30 is not reflected but focused by the film and the liquid behind it (FIG. 12). Such a method is thus based on a change of the focal length.

[0076] Alternative approaches may encompass embodiments with a different geometry of the oscillating nozzle, wherein again at least partly the sleeve 11 of a splitter channel is replaced by a flexible foil (comp. FIG. 13).

[0077] FIGS. 14A and 14B show another alternative embodiment of channels of the splitter 5 which are bordered by flexible foils 9 which are only mounted to the rim so that they may move in their middle part. These two foils may also be coated with a conductive material like a metal from the outside (i.e., electrically insulated from each other) and form an electrical capacitor. In the resting state, the foils lie against each other, their distance against each other is close to zero. When the current liquid flows through them, the foils are driven apart and the capacitance changes which can be determined, e.g., it increases because a signal stroke results from the increased distance between the foils.

[0078] The advantages of the invention can be summarized as follows: [0079] Contactless measurement of the oscillation frequency and thus the flow rate [0080] No moving parts in the system [0081] High measuring frequency possible/fast response [0082] Direct measurement on the film, therefore less susceptible to interference [0083] Partially non-contact measurement, i.e., measuring electronics and measuring chamber can be exchanged independently of each other, the measuring chamber could therefore also be used as a low-cost disposable part.

[0084] The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.

REFERENCE NUMERALS

[0085] 1 oscillating nozzle [0086] 2 fluidic oscillator [0087] 3 inlet fluidic oscillator [0088] 4 outlet fluidic oscillator [0089] 5 splitter [0090] 7 splitter channel [0091] 7a first splitter channel [0092] 7b second splitter channel [0093] 8 outlet splitter [0094] 9 flexible foil [0095] 11 sleeve splitter channel [0096] 11a sleeve first splitter channel [0097] 11b sleeve second splitter channel [0098] 13 conductive layer [0099] 14 counter electrode [0100] 15 capacitor [0101] 17 circuit board [0102] 19 inductive sensor [0103] 20 housing [0104] 20a resulting chamber [0105] 21 pressure sensor [0106] 22 differential pressure sensor [0107] 24 piezo element [0108] 26 expansion element [0109] 28 acceleration sensor [0110] 30 light source [0111] 32 light sensor [0112] 34 reflective coating