EP0552696B1 - Ultrasound generating apparatus - Google Patents

Description

The invention relates to a device for generating Ultrasound and to transmit this ultrasound to a liquid medium using an electroacoustic transducer a layered structure made of sound-conducting solids.

Depending on the type of use of an electroacoustic Converter will also be its structure and design selected. From Ultrasonics Symposium, Volume 2, November 14, 1984, Dallas, Texas, USA, pages 809-814 is an example electroacoustic transducer for the medical field known. Here are a corresponding piezoceramic two layers of adaptation to a patient's skin put on, while on the other hand the piezoceramic of one Damping layer is occupied.

In the present case, however, the invention relates to Transfer of sound energy into a liquid medium. The specific sound effects are in the ultrasound range, due to the occurrence of cavitation, the largest and are made by inexpensive converter manufacture at Ultrasonic cleaning most used. Have essentially prevailed with Piezoceramics equipped and sandwiched Transducers, mostly in longitudinal vibration modes work.

Common to many devices is the absolutely necessary positive connection of the individual transducers with the Area that is in contact with the liquid medium. To the transducers or their coupling pieces with for example bottom and side walls of stainless steel tubs, -Vibration plates and sheets glued by submersible transducers, because they are advantageous from aluminum alloys for physical reasons consist.

Such arrangements are for example in DE-OS 21st 20,654 and U.S. Patent 3,318,578. This Arrangements are inexpensive to manufacture and therefore relatively widespread. Crucial disadvantages are however, a limited shelf life and durability of the Adhesions that are never higher temperatures and may be exposed to increased mechanical loads. Their lifespan is limited.

Other mechanical connection techniques, such as friction welding or a connection by means of welded Bolts have not been used for cost reasons enforced.

Accepting a reduced sound amplitude the sound radiating side, i.e. a reduced one Ultrasonic intensity, also become transducer coupling pieces and the sheet of the radiating side made of stainless steel, i.e., chosen from the same basic material. The coupling pieces can then be welded into pre-cut material or with this through e.g. Solder can be connected directly. Disadvantages arise from an increased energy and Preparation effort, lower efficiency Converter as well as changes in tension and joining of the Base material of the radiating side.

All known devices assume the existence of individual, often already assembled electro-acoustic Transducers ahead, which are used for sound transmission with a sheet, a tub or the like. The attachment and / or coupling separate transducers to the vibration Transferring sheet metal often leads to undesirable Bending vibrations and material fatigue. Increased The result is cavitation and corrosion. In DE-OS 26 05 898 and DE-OS 39 33 519 are therefore various costly devices and measures proposed to minimize these disadvantages.

The present invention is based on the object To design the converter structure so that a direct and quasi lossless introduction of sound energy into a medium it is possible, however, that expensive joining techniques omitted. The electroacoustic efficiency should be and unwanted energy losses are minimized.

To solve this problem, that a front layer as a sound-emitting layer and a subsequent one Layer are interconnected by a metal layer and together a coupling piece for connecting to others Form elements of one or more transducers.

It is essential that a large number of layers are determined by transducer elements. With these elements of transducers can be one or more piezoceramics act with corresponding fasteners are connected to the layers.

As a result, a method according to the invention is easily created Device proposed an almost lossless Coupling or transmission of ultrasonic waves allows liquid or other media in containers in which are intended to have ultrasound-specific effects. These include in particular ultrasonic cleaning baths and Tubs, immersion transducers, vibrating plates and the like, whose sheet is preferably made of rustproof and chemical resistant materials.

The device according to the invention thus consists in this Embodiment from an at least two-layer Vibrating plate or panel, being made up of parts of this Vibrating plate itself or a container or the like. can be molded out. This is first thin layer both part of the actual converter as well at the same time sound-emitting surface. To the thin one Layer joins a thicker layer on which sandwich-like additional elements of the acoustic transducer are constructed, such as corresponding Piezoceramics and pressure pieces.

By using a two or more layers Composite or clad metal material for construction of converters is the prerequisite for high Connection strength between different materials Sound impedance and thickness given. Advantageous is the use of suitable material combinations in the Form that the thick layer is much lower Has acoustic characteristic impedance than the thin layer. This is e.g. the ratio of aluminum for the thick layer too Given stainless steel for the thin layer.

One or both of the layers can be made of a non-metallic Material, for example from a fiber-reinforced plastic, a ceramic or the like. consist. All materials are of the inventive idea which is used as a sound-emitting layer can find.

The thicknesses of the layers also determine the frequency.

According to the invention, part of the converter, namely the or the bodies, from the thick layer like this worked out that the much thinner layer remains unchanged. Should be multiple bodies are provided, so these are through the thinner layer connected, the thinner layer being the sound radiating Forms side. From a sound physics point of view, in In this case, both layers together form the coupling piece of the respective converter. With piezoceramics and pressure pieces from e.g. Completed steel can be any number can be configured by transducers on a thin layer depending on the size you want, Power and frequency. However, this is not allowed are overlooked that the scope of the invention also lies that on a thin layer a single body to build up for example, further piezoceramics and pressure pieces followed.

This asymmetrical operation of with unequal masses composite transducers also causes amplification the intensity towards the radiating side. Over the thin Layer that is part of the one hand Transducer is, on the other hand, in direct contact with the medium stands, to which sound or ultrasonic energy is emitted the sound energy becomes direct and lossless transfer.

In a further embodiment of the invention thicker layer additionally processed so that Free space or web frame undesirable bending resonances be avoided. This is why the bodies are for example arranged at a distance from one another or but there is a web frame between the bodies.

A major advantage of the invention is that the thin layer itself as a container, tub or a plate can be formed. There is also the Possibility of putting the thin layer in a container, a tub or to integrate a plate so that it can be directly connected to the Medium is connected.

Figur 1 eine Seitenansicht einer Schwingplatte;

Figur 2 eine Draufsicht auf einen Teil der Schwingplatte gemäß Figur 1;

Figur 3 eine Seitenansicht eines weiteren Ausführungsbeispiels einer Schwingplatte;

Figur 4 eine Draufsicht auf einen Teil der Schwingplatte gemäß Figur 3;

Figur 5 eine Seitenansicht einer geringfügig mechanisch bearbeiteten Schwingplatte;

Figur 6 eine Draufsicht auf einen Teil der Schwingplatte gemäß Figur 5;

Figur 7 eine schematische Seitenansicht eines mit einer Zentralschraube montierten Schallwandlers.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in

Figure 1 is a side view of a vibrating plate;

FIG. 2 shows a plan view of part of the oscillating plate according to FIG. 1;

Figure 3 is a side view of another embodiment of a vibrating plate;

FIG. 4 shows a plan view of part of the oscillating plate according to FIG. 3;

FIG. 5 shows a side view of a slightly mechanically machined oscillating plate;

FIG. 6 shows a plan view of part of the oscillating plate according to FIG. 5;

Figure 7 is a schematic side view of a transducer mounted with a central screw.

In Figure 1, a two-layer vibrating plate P is made metal composite material shown. Here form two Layers 1 and 2 coupling pieces for building electroacoustic transducers and have a different Sound characteristic impedance for a logitudinal vibration mode on. The thin layer 1 preferably consists of Stainless steel and has additional holes 3 for connecting or Screwing into a stainless steel tub or the like. The thicker Layer 2 contains worked out bodies 4, which are made of an aluminum alloy. In this body 4 are Threaded holes 5 for screwing with in Figure 7 Piezoceramics and pressure pieces shown molded.

For example by milling or sawing are out of the layer 2 the bodies 4 worked out with a square plan, that a distance a stands between them Bending shaft prevented.

The shape of the body is cost dependent and can vary his; truncated pyramids are suitable for good load adjustment, for example, a body is also parabolic Conceivable shape.

The remaining parts of a close to this body 4 Sound transducer, as shown, for example, in FIG. 7 is shown.

In Figures 3 and 4 is a similar vibrating plate P1 as in Figures 1 and 2 shown. It serves, for example Construction of submersible transducers and also consists of one Layer 1 and 2. In contrast to Figure 1, however between layer 2 and layer 1 a circumferential Edge strips 6 of width b left, which to Welding a hood 7 is used.

The bodies 4a molded out of the second layer 2 in contrast to Figure 1 have a circular Floor plan on. In addition, layer 2 is a Bridge frame 8 low height worked out to bending waves to prevent in layer 1. The shape and height of the Web frame 8 can vary. For the body 4a for example, the truncated cone also has an effective shape. On the respective body 4a can then the remaining parts Connect a sound transducer according to Figure 7.

Figures 5 and 6 show an extremely simple and inexpensive structure for the realization of multiple arrangements for adequate applications. Unlike the Embodiments of Figures 1 to 4 is layer 2 to not on the threaded holes 5 and an edge strip 6 or only slightly edited. Layers 1 and 2 thus form a common coupling piece of a defined one and frequency determining thickness c for a variety of Converters. Possible bending phenomena of the vibrating plate P2 towards the radiating side of layer 1 take effect avoided. Small flat depressions 9 can of Be advantage, which is dashed in Figures 5 and 6 are shown. The remaining parts of a transducer 7 can P2 on this vibrating plate being constructed.

The layer 1 in these shown in Figures 1 to 6 However, vibrating plates can advantageously not exclusively as a container, tub, plate or the like. be trained.

FIG. 7 shows a variant of a single sound transducer S shown as a half-wave composite transducer in Longitudinal mode works. It consists of one at least two-layer composite or clad metal with layers 1 and 2, the axially polarized Piezoceramics 10 and 11, the pressure piece 12 made of steel, Connections 13a and 13b and the pressure screw 14. By means of this pressure screw 14, the piezoceramics, Thrust pieces and connections each in the threaded holes 5 the body 4 can be set.

Different materials are used for layers 1 and 2 in question. In particular, this can also be metallic non-metallic materials, for example plastics his. Fiber composites or ceramic materials can also preferred application.

In the case of a multilayer structure, one is preferred Given use of this converter when the Material combination of the composite material stainless steel Is aluminum. The thin layer 1, i.e. the layer made of Stainless steel, can then be easily matched Containers, tubs, plates or the like. same material or other material. A connection both layers of the same material can e.g. by Ring hump welding, friction welding, soldering, electron beam welding or the like.

The described embodiments are in their geometry variable and thanks to modern mechanical processing techniques easy to implement. The invention Construction also allows the transmission of other vibration modes, e.g. from transverse, torsional or Radial oscillations. This is particularly the case in the exemplary embodiment Sound transducer configuration shown in Figure 7 to change accordingly. That is also conceivable Structure of transducers whose axial direction of expansion is not is only λ / 2 but also a multiple of λ / 2 and the may have multiple working frequencies.

Claims (18)

1. Assembly to produce and transfer ultrasound into liquid media via electro-acoustical transducers (S). The transducer consists of multiple layers of sound conducting solid material with the front layer (1) being a sound emitting layer connected to the next layer (2) through a film of metal and these first two layers comprise a coupling unit that can be connected to additional elements (10, 11, 12) of one or several other transducers.
2. Assembly according to claim 1, in which the layers (1 and 2) have different acoustic impedances, hence these layers are frequency-determining parts of one or several transducers (S).
3. Assembly accoording to claim 1 and 2, in which layers (1, 2) differ in thickness.
4. Assembly according to claim 3, in which the thinner front layer (1) comprises the sound emitting layer whereas the next thicker layer (2) contains parts (4) used for configuration with additional elements to make one or several transducers.
5. Assembly according to at least one of claims 1 through 4, in which either one of layer (1) or (2) consists of non-metallic material.
6. Assembly according to at least one of claims 1 through 4, in which the front layer (1 ) is made of stainless steel and in which the following layer (2) consists of an aluminium alloy.
7. Assembly according to at least one of the claims 4 through 6, in which the part (4) is made either plane or curved.
8. Assembly according to at least one of the claims 4 through 7, in which the part (4) contains a taphole (5) to connect the other layers (10, 11, 12) of the transducer (S).
9. Assembly according to at least one of the claims 1 through 8, in which at least one piezoceramic layer (10, 11) as well as a pressure plate (12) are situated to layer (1, 2).
10. Assembly according to claim 8 or 9, in which the additional elements (10, 11, 12) are connected to the following layer (2) by means of a pressure bolt (14).
11. Assembly according to at least one of the claims 1 through 10, in which the front sound emitting layer (1) forms a container, tub or plate or is part of a container, tub or plate.
12. Assembly according to at least one of the claims 1 through 11, in which several shapes (4) have been formed of the following layer (2).
13. Assembly according to claim 12, in which the parts (4) are set apart from each other with a distance (a).
14. Assembly according to one of the claims 12 through 13, in which the following layer (2) contains a number of tapholes (5) for a number of additional elements (10, 11, 12) for a number of transducers (S).
15. Assembly according to at least one of the claims 1 through 11, in which the following layer (2) contains a number of tapholes (5) for a number of additional elements (10, 11, 12) for a number of transducers (S).
16. Assembly according to at least one of the claims 1 through 11, in which the sound emitting front layer (1) of one or several transducers is connected to a container, a tub or a plate.
17. Assembly according to claim 16, in which the connection between the sound emitting front layer (1) and the container, the tub or the plate has been made by ring projection welding, by friction welding, by brazing or by electron beam welding.
18. Assembly according to claim 16 or 17, in which the container, the tub or the plate are made of the same material as the sound emitting front layer (1), preferably using stainless steel.

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