DE202012010508U1 - Device for applying liquid media with ultrasound through a membrane and ultrasound system - Google Patents

Abstract

Device (1) for applying liquid media with ultrasound through a membrane, the device comprising - an ultrasound generator (5) for generating ultrasound and - a sound guide element (2) for guiding the ultrasound generated by the ultrasound generator, and the sound guide element (2) Has contact surface (15) for decoupling the ultrasound to a flexible medium, the sound guide element (2) having a channel (18) with a first opening (20) for applying negative pressure to the channel (18) and a second opening (17) for Applying the negative pressure to the flexible material includes.

Description

The invention relates to a device for applying ultrasound to liquid media through a membrane, the device comprising an ultrasound generator for generating ultrasound and a sound conducting element for guiding the ultrasound generated by the ultrasound generator, and the sound conducting element has a contact surface for coupling the ultrasound to a flexible medium, in particular a membrane.

In previously available devices, it is problematic to produce an efficient sound transmission between the device and a flexible material, such as a membrane. About such a flexible material can also be a coupling into a liquid. In order to improve the transition of ultrasound from the device to a flexible material, it is known to press the device against the flexible material. Here, the flexible material is mechanically stressed, which can lead to damage of the flexible material.

The object of the invention is to propose a device which enables the most efficient possible ultrasonic coupling to a flexible material, wherein a mechanical stress of the flexible material is kept as low as possible.

This object is achieved by a device according to claim 1 and an ultrasound system according to claim 15. Further possible embodiments are explained in the dependent claims.

By virtue of the fact that the sound conducting element comprises a channel with a first opening for connecting a pump to the channel and a second opening for applying a negative pressure to the flexible material, for example within the contact surface, a flexible material can be coupled into the ultrasound be sucked by means of negative pressure to the contact surface. This allows a very even distribution of a contact pressure over the contact surface. A mechanical stress of the flexible material is thus reduced. In addition, a negative pressure can be adjusted particularly well reproducible and precise.

The ultrasound generator may, for example, comprise at least one piezoelectric element. A particularly precise control of the intensity of the irradiated ultrasound is possible if the ultrasound generator comprises a plurality of piezoelectric elements, wherein at least a first piezoelectric element of the generation of ultrasound and at least one second piezoelectric element is used for the detection of ultrasound, and is suitably connected thereto. For example, the at least one first piezoelectric element may be connected to a voltage supply for the vibration excitation of the first piezoelectric element. The second piezoelectric element may, for example, be connected to a measuring device for measuring the ultrasound passing through the second piezoelectric element. By way of example, the measuring device can determine the amplitude and / or power of the ultrasound passing through the second piezoelectric element via the voltage generated by the at least one second piezoelectric element. The second piezoelectric element may, for example, be arranged between the first piezoelectric element and the contact surface, in particular between the first piezoelectric element and the sound conducting element. Instead, however, the first piezoelectric element may also be arranged between the second piezoelectric element and the sound conducting element.

In order to ensure a time constant introduction of the negative pressure can be arranged in the region of the contact surface, the contact surface circumferential sealing element. When the contact surface is now brought into contact with a flexible material, the sealing element, the contact surface and the flexible material form a pressure space in which the flexible material is sucked against the contact surface with a uniform pressure. Alternatively or in addition to a sealing element, the contact surface may be concave. However, it is also a planar shape (especially when a sealing element is used) of the contact surface possible. The outer region of the contact surface then forms a sealing edge, which has the same effect as a sealing element. By using a seal and / or concave contact surface, the escape of the negative pressure is largely avoided. As a result, a negative pressure maintained by a pump with low flow rate, which allows the use of pulsation-free pumps.

The sound conducting element, which may be arranged so that the ultrasound is passed through the sound conducting element, may have at least one tapered region. A region is regarded as being tapered if, in this region, the cross-sectional area of the sound-conducting element in a plane orthogonal to the direction of sound propagation is smaller than the cross-sectional area outside this region. In particular, the cross-sectional area in the tapered region can be smaller than the contact surface. By means of such a tapered region, the amplitude of the ultrasound which reaches the contact surface can be influenced. In particular, the ultrasound can concentrate the ultrasound to a relatively small cross-section through the tapered region become. This makes it possible to increase the amplitude of the ultrasound at the contact surface to 3 to 5 times the amplitude present directly at the ultrasound generator. In order to minimize the wear of the second part of the sound-conducting element and of the flexible medium, the maximum amplitude at the contact surface can be, for example, less than 30 micrometers. In particular, the maximum amplitude may be between 10 and 20 microns.

The sound-conducting element can be designed, for example, rotationally symmetrical and, in particular, as a rotationally symmetrical rod. However, it can also be designed differently from a rotationally symmetrical shape. For example, the sound-conducting element can be shaped as a rod with a triangular or quadrangular cross-section.

The sound conducting element may have a first part connected to the ultrasound generator and a second part having the contact surface. The two parts are then connected to each other, wherein the compound may be formed in particular detachable. For example, the connection may be formed as a screw connection. The two-part design of the Schallleitelements allows, with little effort to replace the bearing surface having part. This is advantageous because the contact surface is most affected by wear.

The tapered region can be arranged in particular in the second part having the contact surface. In particular, there may be a plurality of second parts for the device, which differ with regard to the cross section in the tapered region. Accordingly, the intensity of the ultrasound that comes to the contact surface can be changed by replacing an easily replaceable part, which is already occasionally replaced due to wear anyway.

In addition, a taper portion in which the cross section decreases in the direction of the abutment surface may be arranged in the first part. Through this taper section, an ultrasound generator having a large cross-sectional area and a small amplitude can be used, wherein the ultrasound is concentrated by the taper section to a smaller cross-sectional area.

If both a tapered portion and a tapered portion are present, both contribute to the amplification of the amplitude at the contact surface.

In particular, the channel can at least partially pass through both the first and the second part of the sound-conducting element. The second part, for example, can also be completely traversed by the channel. The arranged in the contact surface second opening is then part of the second part, while serving to connect a pump first opening is part of the first part. Characterized in that the serving to connect the pump opening is part of the first part, it is not necessary in case of (for example, wear-related) replacement of the second part to release a connection between the pump and the device.

A diameter of the channel can change over its length. In particular, the diameter of the channel may change within the second part and / or in the region of the connection between the first and the second part. By replacing the second part with a similarly shaped second part but differing in the diameter of the channel in the region of the abutment surface (i.e., the diameter of the second opening), a suction force on the abutment surface can be changed.

In addition, the device may comprise a termination element which is arranged on the side remote from the sound conducting element side of the ultrasound generator.

The first part, the second part and / or the closing element may be formed of the same or of different materials. In particular, a solid material that can withstand high vibration / strain stresses comes into question as materials. The material or materials should be low in attenuation. For example, suitable metals, alloys, plastics or ceramics may be used as the material.

The sound-conducting element can also be formed in one piece. Even with a one-piece design, the above-mentioned materials for the Schalleitelement can be used.

The ultrasound generator can be set up to generate ultrasound at a frequency between 20 kHz and 100 kHz (in particular between 30 kHz and 40 kHz). The length of the device may be in particular half of the ultrasonic wavelength, so that a standing wave can form in the ultrasonic transducer. The device can thus be designed as a λ / 2 converter.

A connection between the first part and the second part of the sound-conducting element can in particular be between one sixteenth and three sixteenths of the wavelength λ from the connection surface. As "wavelength λ" is meant here the wavelength of the ultrasound in the material of the sound conducting element (for example titanium) become. This arrangement of the connection is advantageous, since in this region of the device, the oscillation amplitude is still low, and the tension against the tension in the middle of the device has already dropped significantly. The connection between the first and the second part of the sound conducting is thus not overstressed, ie the mechanical stress of the compound is within the tolerable range.

In principle, it is also possible to design the second part as a thin plate-shaped attachment. The connection is then only slightly removed from the contact surface. However, this results in a significantly greater oscillation amplitude in the region of the connection. As a result, a gap between the first and second part arise, and this is not desirable. In addition, the design freedom would be severely limited in terms of the channel and the contact surface.

The first opening of the channel, which may be arranged in the first part as already mentioned, may for example be approximately one quarter of the wavelength (in particular between 0.2λ and 0.3λ) away from the connection surface, i. H. the first opening may be arranged in particular in the middle 20% of the length of the ultrasonic transducer. By this it is meant that the opening of the channel from a zero vibration level of the device (i.e., the plane in which the amplitude of the vibration is zero) can be longitudinally less than ± 10% of the length of the device. In this area, there is only a small longitudinal amplitude. Thus, a connection to a pump is only slightly loaded, which significantly reduces the risk of leaks in the connection between the channel and the pump.

In particular, a power of the ultrasound generated by the ultrasound generator may be between 5 W and 20 W. The amplitude of the ultrasound may be, for example, between 10 and 30 μm at the contact surface. An amplitude in this range is sufficient to induce cavitation in the case of liquids to be treated with a low-attenuation membrane, the amplitude still being sufficiently low in order to minimize wear in the region of the contact surface.

In particular, the first opening may be arranged in a side face that is substantially orthogonal to a radiation direction of the ultrasound generator. A side surface is considered substantially orthogonal if its surface normal has an angle between 60 ° and 120 ° to the emission direction. In particular, the angle can be between 80 ° and 100 °.

In addition to a device, the invention also relates to an ultrasound system having a device as described above. The ultrasound system further includes a pump configured to generate a negative pressure and connected to the channel via the first opening. The ultrasound system may further comprise a membrane applied to the contact surface as a flexible material. Such a membrane can be used to surround, for example, liquids to be treated with ultrasound.

In addition, the ultrasound system may include a power supply configured to supply the ultrasound generator - which may include a piezoelectric element as mentioned above - with a voltage for vibrational excitation of the ultrasound generator. Furthermore, the ultrasound system can have a measuring device for determining the amplitude and / or intensity of the ultrasound generated. The measuring device can determine the amplitude and / or intensity in particular via the voltage of the second piezoelectric element.

Embodiments of the invention will be explained in more detail with reference to FIGS. Show it:

1a and 1b Section through and plan view of an embodiment of a device for applying liquid media with ultrasound through a membrane,

1c Detail view of a variant of the device from the 1a and 1b .

2a to 2d Sectional view, top view and two detailed views of a first part of the Schallleitelements of the device 1 .

3a and 3b Sectional view and supervision of a second part of the Schallleitelements the device 1 .

4 a cross section through another part of the device 1 .

5 a fundamental course of the voltage and the oscillation amplitude over the device 1 .

6a and 6b Sectional view and top view of another embodiment of a device for applying liquid media with ultrasound through a membrane and

7a to 7d Sectional views through and on views of alternative embodiments of a suction for the device 1 ,

In the 1a and 1b is a device 1 shown in cross-section and in supervision. The device 1 has a sound conducting element 2 , consisting of a first part 3 and a second part 4 (also called ultrasonic squeegee) on. Furthermore, the device comprises an ultrasound generator 5 and a back end element 6 ,

The ultrasound generator 5 which is arranged to generate ultrasound at a frequency of 30 kHz in this embodiment is between the first part 3 of the sound conducting element 2 and the back end element 6 trapped. This is the final element 6 with a recording 7 equipped for a screw. The first part of the sound conducting element 2 again has a threaded hole 8th on, in which a screw 9 whose head 10 in the final element 6 is arranged, is screwed. The first part 2 further includes one from the ultrasonic generator 5 directed away screw hole 11 in which the second part 4 of the sound conducting element 2 is screwed. For this purpose, the second part 4 of the sound conducting element 2 a thread 12 on. To screw in the second part 4 of the sound conducting element 2 in the first part 3 to facilitate both the first and the second part 4 of the sound conducting element key surfaces 13 and 14 on, where by means of a conventional wrench a force can be introduced. The second part 4 of the sound conducting element 2 also has a contact surface 15 on top, with a surrounding O-ring 16 equipped and is used for coupling the ultrasound in a flexible medium. In the middle of the contact surface 15 is an opening 17 arranged with a channel 18 communicates. The channel 18 crosses the second part 4 the Schallleitelements complete and the first part 3 at least partially. That from the opening 17 wayward end of the canal 18 is within the first part 3 arranged the Schallleitelements. There is the channel 18 with a connector 19 which is an opening 20 has, in conjunction. About this connector 19 a conventional hose can be pushed and fastened, for example, with a hose clamp. About the connector 19 can the channel 18 thus connected to a pump (not shown), via which a negative pressure for sucking the flexible medium to the contact surface 15 can be applied. The diameter of the channel 18 changes within the second part 4 , By the geometry of the channel in the second part 4 Thus, the suction force is influenced at the contact surface. As a pump, in particular a pulsation-free pump can be used.

The already mentioned ultrasonic generator 5 includes several piezo elements 21 to 24 , Two of the piezo elements 21 and 22 are connected to a voltage source, not shown, and configured to generate the ultrasound. The two piezo elements 23 and 24 on the other hand, no power supply but a signal tap, which is in communication with a measuring device, also not shown. This measuring device can be based on one of the piezo elements 23 and 24 Depending on the present ultrasonic amplitude generated voltage determine the amplitude and / or intensity of the ultrasound. As in the supervision 1b can be seen, the device has 1 also a flange 25 on which it can be attached.

The device 1 has a length, ie a total extent in the sound propagation direction x, which corresponds to half the wavelength of the generated ultrasound. The device can thus be referred to as a λ / 2 converter. In the present embodiment, the device 1 set up to generate ultrasound at a frequency of 30 kHz. The sound conducting element 2 is made of titanium and the final element 6 made of aluminum. The length of the device is thus a little over 17 cm. The sound conducting element 2 can be formed as shown in two parts or one piece. The first part 3 , the second part 4 , the entire sound conducting element 2 and / or the conclusion element 6 may also be formed of another metal of an alloy, a plastic or a ceramic instead of titanium. That sound-conducting element 2 can have a rotationally symmetrical cross section. A cross section of the sound conducting element 2 However, it can also deviate from a rotationally symmetrical shape. For example, a triangular or quadrangular cross section of the sound conducting element 2 possible.

In 1c is the suction surface 15 ' as a detail of an alternative variant of a device 1 shown. In the illustrated detail is the contact surface 15 ' formed curved. Due to the curved, concave shaped design of the contact surface 15 ' No seal is required as the outside edge 26 the contact surface 15 ' serves as a sealing edge. Alternatively, the contact surface may also be convex, ie curved in the opposite direction. The abutment surface may then be pressed against a flexible material (in particular a membrane) to make a reliable contact and over the opening 17 be connected by means of negative pressure with the flexible material, so that the flexible material follows the movement of the contact surface.

In the 2a to 2d is the first part 3 of the sound conducting element 2 from the device 1 from the 1a and 1b shown in section and in supervision. In the sectional view 2a are the two threaded holes 8th and 11 to connect with the screws 10 or the second part 4 particularly easy to recognize.

It can also be seen that the first part is a rejuvenation area 32 in which the cross-section (ie, the sectional area orthogonal to the direction x 1 ) from the ultrasonic generator 5 decreases towards the contact surface, and a coupling area 33 in which the threaded hole 11 is arranged and thus the coupling to the second part 4 serves. The rejuvenation area 32 serves to amplify the amplitude of the ultrasound, the gain being achieved by concentrating the ultrasound in the reduced cross-sectional area.

The ultrasonic generator 5 facing threaded hole 8th is in the detail view 2 B shown in more detail while the second part 4 of the sound conducting element 2 facing threaded hole 11 in the detail view 2c is more accurate. In the supervision off 2 B is in particular the flange 25 which is used to attach the device 1 can be used to recognize.

In the 3a and 3b is the second part 4 the Schallleitelements shown in detail. In the area of the contact surface 15 the second part of the sound conducting element has a contact surface 15 circumferential groove 27 on, for fixing the O-ring 16 (see. 1a ) serves. At a small distance to the contact surface 15 rejects the part 4 the Schallleitelements a tapered area 28 on, over which the amplitude of the ultrasound, to the contact surface 15 arrives, continues. Together with the rejuvenation area 32 of the first part 3 thus results in an amplification of the amplitude at the contact surface 15 versus the amplitude at the ultrasonic generator 5 by a factor of 3 to 5. The second part 4 of the sound conducting element 2 It is very easy to exchange for a breakdown, if maintenance due to wear of the contact surface 15 it is necessary to keep as short as possible. The second part 4 can also be exchanged to an intensity of the contact surface 15 changing ultrasound. For this purpose, a built-in second part 4 of the sound conducting element 2 against an alternative of the second part 4 be replaced, which in terms of the cross section in the region of the tapered region 28 different.

In 4 is the final element 6 shown in section. As can be seen, the end element points 6 the recording 7 for the screw head and a through hole for the shaft of the screw 9 on.

In 5 is the principal course 29 the tension and the principal course 30 the oscillation amplitude over the length of the transducer 1 applied. The position of the contact surface 15 is marked on the X axis. As based on the course 30 can be seen, the amplitude of the ultrasonic vibration in the region of the ends of the device 1 maximum. For example, it can be between 20 and 30 microns. The tension is the lowest at the ends. In the field of vibration level of the device 1 however, the tensile stress is much greater, but the amplitude is very low. Because of the threaded holes 8th and 11 close, but not directly in the vibrational level of the device 1 are arranged, the amplitude of the vibration in the region of the threaded bore is still low, the tensile stress against a tensile stress in the center of the device 1 already dropped significantly. The connection 19 is arranged in the longitudinal direction (ie x-direction) of the transducer in the vibrational zero plane, since there the amplitude is minimal.

It should be noted that the progressions shown 29 and 30 only schematic representations are. The exact gradients caused by the shape of the device 1 and especially through the rejuvenation 28 and the rejuvenation area 32 can be influenced significantly different from the illustrated courses 29 . 30 be.

A slightly modified variant of a device 1 is in the 6a and 6b shown in a sectional view and a plan view. The embodiment differs only in that instead of a closure element 6 and an ultrasonic generator 5 a coherent drive unit 31 is provided, which contains an ultrasonic generator and into the threaded hole 8th of the first part 3 of the sound conducting element 2 can be screwed.

In the 7a to 7c are three different further embodiments of a contact surface 15 shown in section and in a plan. In the 7a illustrated contact surface has four distributed over the circumference, at 90 ° angles to each other arranged suction 34 on, each with the channel 18 are connected. For this purpose, the channel is not up to the contact surface 15 performed as a central channel but divides into four associated with each one of the openings sub-channels 35 on. The channel 18 can in the second part 4 from the first part 3 pointing side of the second part by drilling initially partially introduced. The introduced hole penetrates the second part 4 not complete and is thus designed as a blind hole. The subchannels 35 can then proceed from the contact surface 15 be introduced, such that they end in the lower end of the blind hole.

The variant off 7a can also be modified to the effect that the channel 18 (especially with reduced cross-section) to the contact surface 15 is carried out. The with the subchannels 35 connected suction openings 34 then act as additional suction points (in addition to a central opening 17 like out 1 known) and improve uniformity of the pressure force of the membrane on the contact surface over the variant 1 ,

The variant off 7b has a continuous central channel 18 on, the same as in 1 is trained. Star-shaped from the opening 17 starting, are in the contact surface 15 but superficial channels 36 incorporated. A height of the channels increases with increasing distance from the contact surface 15 from.

The variant off 7c also has a continuous channel 18 like out 1 known on. In the contact surface are an annular channel 37 as well as connection channels 38 incorporated. Of course, also several annular channels 37 be provided and the number of connection channels 38 can be varied.

The variant off 7d also has a continuous channel 18 on. From this outgoing go several main channels 39 off, which in turn turn into hub channels 40 aufzweigen. These in turn can branch out according to the principle of a self-similar structure, but this is not shown in the figure. The main channels 39 have, as the sectional view can be seen, a greater height than the secondary channels 40 on.

Claims (17)

Contraption ( 1 for exposing liquid media to ultrasound through a membrane, the apparatus comprising - an ultrasonic generator ( 5 ) for generating ultrasound and - a sound conducting element ( 2 ) for guiding the ultrasound generated by the ultrasound generator, and the sound conducting element ( 2 ) a contact surface ( 15 ) for coupling the ultrasound to a flexible medium, wherein the sound conducting element ( 2 ) a channel ( 18 ) with a first opening ( 20 ) for applying negative pressure to the channel ( 18 ) and a second opening ( 17 ) for applying the negative pressure to the flexible material. Contraption ( 1 ) according to claim 1, characterized in that the ultrasonic generator ( 5 ) at least one piezoelectric element ( 21 . 22 . 23 . 24 ). Contraption ( 1 ) according to claim 2, characterized in that the ultrasonic generator ( 5 ) a plurality of piezoelectric elements ( 21 . 22 . 23 . 24 ), wherein - at least one first piezoelectric element ( 21 . 22 ) is connected to a voltage supply for the vibration excitation of the first piezoelectric element and - at least one second piezoelectric element ( 23 . 24 ) with a measuring device for measuring the second piezoelectric element ( 23 . 24 ) continuous ultrasound is connected. Contraption ( 1 ) according to one of the preceding claims, characterized in that the second opening ( 17 ) within the contact surface ( 15 ) is arranged. Contraption ( 1 ) according to one of the preceding claims, characterized in that in the region of the contact surface ( 15 ) the contact surface ( 15 ) circumferential sealing element ( 16 ) is arranged and / or that the contact surface ( 15 ' ) is concaved to form a circumferential sealing edge. Contraption ( 1 ) according to one of the preceding claims, characterized in that the sound conducting element ( 2 ) at least one tapered region ( 28 ) having. Contraption ( 1 ) according to one of the preceding claims, characterized in that the sound conducting element ( 2 ) at least one with the ultrasonic generator ( 5 first part ( 3 ) and one the contact surface ( 15 second part ( 4 ), the two parts ( 3 . 4 ) are connected to each other, for example screwed, are. Contraption ( 1 ) according to claim 7, insofar as it relates to claim 6, characterized in that the tapered region ( 28 ) in which the contact surface ( 15 second part ( 4 ) is arranged. Contraption ( 1 ) according to claim 7 or 8, characterized in that the channel ( 18 ) the first and second parts ( 3 . 4 ) of the sound conducting element ( 2 ) at least partially passes through, wherein the first opening ( 20 ) of the channel in the first part ( 3 ) and the second opening ( 17 ) of the channel in the second part ( 4 ) is arranged. Contraption ( 1 ) according to one of the preceding claims, comprising a closure element ( 6 ), that of the contact surface ( 15 ) forms opposite end of the device. Device according to one of the preceding claims, characterized in that the first part ( 3 ) of a different material than the second part ( 4 ) and / or the conclusion element ( 6 ) is trained. Device according to one of claims 1 to 6, characterized in that the Schallleitelement is integrally formed. Contraption ( 1 ) according to one of the preceding claims, characterized in that the ultrasonic generator ( 5 ) is set up to generate ultrasound at a frequency between 20 kHz and 100 kHz, for example a frequency between 30 kHz and 40 kHz. Contraption ( 1 ) according to one of the preceding claims, characterized in that the first opening ( 20 ) of the channel ( 18 ) is arranged in a substantially orthogonal to a radiation direction of the ultrasound generator side surface of the Schallleitelements. Comprising an ultrasound system - a device ( 1 ) according to one of the preceding claims, - a vacuum source, for example a pump, which is designed to generate a negative pressure and connected to the channel ( 18 ) connected is. Ultrasound system according to claim 15, comprising a contact surface ( 15 ) fitting flexible material, in particular a voltage applied to the contact surface membrane. An ultrasound system as claimed in any of claims 15 or 16, when dependent on claim 8, comprising a plurality of interchangeable second parts ( 4 ) of the sound conducting element ( 2 ), wherein the interchangeable second parts ( 4 ) in terms of a cross-sectional area in the area of the rejuvenation ( 28 ) and / or in terms of the contact surface ( 15 ).

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