DE102009052814B3 - Ultrasonic transducer-arrangement for use in flow measuring device for gaseous or liquid medium, has coating extending from front and rear sides of transducer element into cavities, and connection elements engaged into cavities - Google Patents

Abstract

The arrangement (1) has a piezoelectric transducer element (2) i.e. piezoelectric disk, with a mantle surface (3), a front side turned towards a medium and a rear side turned away from the medium. The front side and the rear side are provided with an electrically conductive coating. Electrical connection elements (7) are provided for electrical connection of the front and rear sides of the piezoelectric transducer element. The coating extends from the front and rear sides of the transducer element into cavities (8). The connection elements are engaged into the cavities.

Description

The invention relates to an ultrasonic transducer assembly for use in a flow meter for gaseous or liquid medium with the further features of the preamble of claim 1. Furthermore, the invention relates to a flow meter for gaseous or liquid medium with at least one ultrasonic transducer assembly according to the invention.

Previously known ultrasonic transducer arrangements, which are designed in particular for use in a flow meter for liquid or gaseous medium, have at least one piezoelectric transducer element, in particular a piezoelectric disk whose front facing the medium and the back facing away from the medium each with a conductive Coating such. As a silver or gold layer are provided. In addition, a membrane is arranged on the electrically conductive coating on the front side. On the back of an electrode on the conductive coating is provided. Electrode and membrane extend over the entire surface or almost the entire surface over the front and back or the end faces of the transducer element, wherein they are glued to the front side with the piezoceramic or the electrically conductive coatings. This end-face arrangement of electrode and membrane must simultaneously fulfill different functions. It serves to fix the piezoceramic, to produce an electrical connection and to ensure a large-area acoustic coupling.

A corresponding ultrasonic transducer assembly goes out of the DE 101 58 015 A1 in which a piezoelectric disc is arranged in a cup-shaped converter housing with the front side open. At the front side facing the medium, the first electrode is contacted with a first connection electrode for supplying current, wherein the first connection electrode closes the converter housing. On the back of a second electrode is contacted with a second connection electrode for supplying power.

Out DE 10 2007 037 088 A1 For example, an ultrasonic transducer is known which has a piezoelectric transducer element and a matching body with a matching layer for promoting vibration coupling between the piezoelectric transducer element and a surrounding fluid medium. In one embodiment variant, the piezoelectric transducer element is fixed with laterally attachable clamps, wherein in each case at least one clamp contacts the upper electrode of the piezoelectric transducer element and at least one further clamp contacts the lower electrode. The brackets themselves have a connection contact for contacting electrode leads.

At the DE 196 26 293 A1 known ultrasonic transducer, the electrical contact is created by means of at least one resiliently seated on the piezoelectric crystal or the vibrating element contact spring. In this case, contact springs are held by a connecting body, which is pressed into the interior of a pot-shaped oscillating element. As a result, the necessary support for the molded with the connecting body spring contacts is created so that they can rest with a corresponding bearing force on the piezoelectric disk.

Out JP 08205287 A there is disclosed an electro-acoustic transducer device in which a piezoelectric diaphragm is held between top and bottom housing parts. Edge-side U-shaped clamps are in spring contact with a piezoceramic disk and a metallic substrate of the piezoelectric diaphragm.

Out US 4,429,247 A a node contact for piezoelectric audio transducer is known, in which within a housing a disc-shaped transducer is provided with a peripheral groove. On the inside of the housing extends an inwardly projecting rib which engages in the groove of the transducer. The groove on the converter thus serves only to position the housing.

The object of the present invention is to provide a novel ultrasonic transducer assembly for use in a flow meter, which can be produced with a low production cost.

The invention is solved by the entire teaching of claim 1. Advantageous developments of the invention will become apparent from the dependent claims 2-12. An inventive flow meter is taught in claim 13.

The ultrasonic transducer arrangement according to the invention for use in a flowmeter for gaseous or liquid medium has a piezoelectric transducer element, in particular a piezoelectric disc, also called piezoceramic, which has a lateral surface, wherein the front side facing the medium and the rear side facing away from the medium Transducer element are each at least partially provided with an electrically conductive coating, and electrical connection elements for electrically connecting the front and rear of the piezoelectric transducer element are provided with the electronics. The lateral surface has two Einformungen, wherein the conductive coating from the front of the piezoelectric transducer element in the one indentation and the conductive coating from the back of the piezoelectric transducer element extends into the other indentation and engages in each case an electrical connection element in a respective indentation. Thus, a lateral fixation and electrical contacting of the piezoceramic by the same elements. Preferably, a cylindrical piezoelectric transducer element is used, which in each case has a indentation at two different locations of the lateral surface, into which a re-contacting (electrically conductive coating) is applied from in each case one of the two end faces. The electrically conductive coating may in particular be a silver or gold layer which extends into the respective indentation. The electrical connection elements engage in the recesses, wherein they fix the piezoelectric transducer element and simultaneously contact electrically. A gluing process is not necessary. Fixation and contacting of the piezoelectric transducer element can preferably be done by a simple clamping. The assembly effort is therefore low.

The piezoelectric transducer element can be arranged on a wall to be penetrated or a housing to be audible, which is in contact with the medium. The wall to be penetrated or the housing to be penetrated can be a plastic part. The wall to be penetrated can consist of one or more layers and replace the previously thin metal membrane. The piezoelectric transducer element is securely fixed in this way to the wall or housing to be penetrated.

The electrical connection elements can also be fastened at least in regions to the wall to be penetrated or the housing to be penetrated. For example, the electrical connection elements can already be introduced as inserts in a plastic injection molding process. On the back side, the electrical connection elements are fastened, for example, to the electronics provided there or to a circuit board.

In this way no gluing process is needed. Before applying the piezoceramic disk on the wall to be penetrated by a coupling gel or a coupling paste can be applied to the wall before. Subsequently, the piezoceramic disc only has to be plugged on.

The indentations described above may be formed as grooves which extend at least partially from front or back to the rear or front side of the piezoelectric disk. The grooves may be configured differently in shape and z. B. semicircular or square be formed. The grooves can be easily incorporated into the piezoelectric transducer element or the piezoelectric disc. They are in each case with only one end face, ie the front or rear side of the transducer element in electrical connection to the other end face they are insulated or non-conductive.

The indentations may expediently be provided at opposite positions of the electrical transducer element. The engaging therein electrical connection elements securely fix the electrical transducer element in this way.

The electrical connection elements can contact the front and / or rear side for increased fixation of the transducer element. The electrical connection elements can then be designed according to a clip.

The electrical connection elements can therefore be designed as clip-like springs or as pins, in particular precisely fitting pins. The pins are precisely in the recesses and are securely fixed therein.

The fixation and / or electrical contacting of the electrical connection elements can be supported by (conductive) adhesive or soldering. The electrical connection elements are glued to the electrically conductive coating and / or soldered.

As already described above, an acoustic coupling agent, in particular a coupling gel or a coupling paste, can be provided between the front side of the piezoelectric transducer element and the wall to be penetrated. The acoustic coupling is thereby realized or substantially improved. Thus, a very robust acoustic coupling of the piezoelectric traveling element or the piezoceramic to the wall to be penetrated and the medium is possible.

The rear side facing away from the medium of the transducer element may at least partially communicate with air and thereby swing freely in the air. As a result, damping, the generation of structure-borne noise and (possibly temperature-dependent) feedback are avoided.

• – Das piezoelektrische Wandlerelement kann zunächst beim durchströmten Rohr (Grundzähler) mit montiert werden. In diesem Fall stehen je Ultraschallwandler zwei Stifte bzw. Anschlussenden der elektrischen Verbindungselemente für den elektrischen Kontakt hervor, die am Ende an passender Stelle in die Elektronik bzw. die Platine gesteckt und eventuell verlötet werden.
• – Es besteht auch die Möglichkeit, das piezoelektrische Wandlerelement zunächst auf der Elektronikseite zu montieren. Bei der Endmontage wird die akustische Verbindung an der zu durchschallenden Wand mit Hilfe eines akustischen Koppelmittels, z. B. einem Kontaktgel oder einer Kontaktpaste, hergestellt.

The ultrasonic transducer assembly according to the invention is in its function and spatially between the flow-through pipe and the electronics. Towards the end of production, these two parts are brought together. This assembly can optionally be done as follows:

• - The piezoelectric transducer element can first be mounted on the flow-through pipe (basic meter). In this case, each ultrasonic transducer two pins or terminal ends of the electrical connection elements for the electrical contact out, which are inserted at the end of an appropriate location in the electronics or the board and possibly soldered.
• - It is also possible to first mount the piezoelectric transducer element on the electronics side. During final assembly, the acoustic connection to the wall to be penetrated by means of an acoustic coupling agent, for. As a contact gel or a contact paste produced.

The invention is explained in more detail with reference to an advantageous embodiment in the drawing figures. These show:

1A : perspective view (partially in section) of the piezoelectric transducer element inserted on a wall to be penetrated through with protruding contacts of the electrical connecting elements;

1B : Page presentation of the arrangement according to 1A ;

2A : Perspective illustration of a piezoelectric transducer element with two grooves as well

2 B : Side view of the transducer element according to 2A ;

In the 1 illustrated ultrasonic transducer assembly is denoted by reference numeral 1 and intended for use in a gaseous or liquid medium flowmeter. It comprises a piezoelectric transducer element 2 which is formed as a piezoelectric disc. The lateral surface of the piezoelectric transducer element 2 is with reference number 3 Mistake. The medium facing front 4 as well as the rear facing away from the medium 5 the piezoelectric transducer element 2 are each up to the edge area with an electrically conductive coating 6 Mistake. Electrical connection elements 7 are used for electrical connection of front 4 or back 5 the piezoelectric transducer element 2 provided with an electronics (not shown in the drawing figures). The electrical connection elements 7 serve at the same time the mechanical fixation.

The lateral surface 3 has two indentations 8th . 9 on that in 2A can be clearly seen. As well as from the 2A and 2 B shows, extends the electrically conductive coating 6 from the front 4 the piezoelectric transducer element 2 in the indentation 8th , At the same time extends the electrically conductive coating 6 from the back 5 the piezoelectric transducer element 2 in the other impression 9 , This is indeed in the drawing figure 2A not recognizable, however corresponds the back 5 the front 4 , wherein the re-contacting of the electrically conductive coating 6 is placed by the two end faces in each case only in a molding. The lateral fixing and contacting of the piezoceramic or the piezoelectric transducer element 2 takes place with appropriate Umkontaktierung by the electrical connection elements 7 in the form of spring-like clamp elements. The electrical connecting elements 7 are shaped to be the piezoelectric transducer element 2 pinch. This is connected to only a small amount of assembly work.

The piezoelectric transducer element 2 is also on a wall to be penetrated 10 made of plastic, which communicates directly with the medium. The wall to be penetrated 10 serves the acoustic coupling to the medium.

The indentations 8th . 9 are formed as semicircular grooves extending from the front 4 to the back 5 extend. These grooves can be introduced manufacturing technology without much effort.

The wall to be penetrated 10 serves at the same time - as from the 1A and 1B visible - the fixation of the electrical connection elements 7 , The electrical connection elements 7 are as inserts in a plastic injection molding process already in the wall to be penetrated 10 made of plastic.

The indentations 8th . 9 are at opposite positions of the piezoelectric transducer element 2 provided and thereby serve the optimal fixation of the transducer element 2 , In addition, in this way, the electrical connections are sufficiently spaced apart.

The electrical connection elements 7 also slightly contact the back 5 the piezoelectric transducer element 2 , whereby the clamping effect is brought about.

For the electrical connection elements 2 is in the illustrated embodiment, clip-like springs. It can also be accurately fitted pins are provided in the recesses 8th . 9 einliegen.

In addition, the electrical connection elements 7 to the electrically conductive coating 6 glued and / or soldered, whereby the fixation and electrical contact is supported.

Between front 4 the transducer element 2 and the wall to be penetrated 10 is a pasty acoustic coupling means for realizing a very robust acoustic coupling provided.

The backside 5 of the transducer element 2 is at least partially in contact with air, so that even this side facing away from the medium can swing freely. The back is area wise 5 the transducer element 2 on a support or a housing section.

LIST OF REFERENCE NUMBERS

1

Ultrasound transducer assembly

2

piezoelectric transducer element

3

lateral surface

4

front

5

back

6

electrically conductive coating

7

electrical connection elements

8th

indentation

9

indentation

10

to durchschallende wall

Claims (13)

Ultrasonic transducer arrangement for use in a flow meter for gaseous or liquid medium, with an outer surface ( 3 ) having piezoelectric transducer element ( 2 ), whose front facing the medium ( 4 ) and its rear side facing away from the medium ( 5 ) each at least partially with an electrically conductive coating ( 6 ), as well as electrical connecting elements ( 7 ) for the electrical connection of front ( 4 ) or back ( 5 ) of the piezoelectric transducer element ( 2 ), characterized in that - the lateral surface ( 3 ) two impressions ( 8th . 9 ), - the electrically conductive coating ( 6 ) from the front ( 4 ) of the piezoelectric transducer element ( 2 ) in a molding ( 8th ), - the electrically conductive coating ( 6 ) from the back ( 5 ) of the piezoelectric transducer element ( 2 ) into the other impression ( 9 ) and - in each case an electrical connection element ( 7 ) in each case a molding ( 8th . 9 ) intervenes. Ultrasonic transducer assembly according to claim 1, characterized in that the piezoelectric transducer element ( 2 ) on a wall to be penetrated ( 10 ) which is in communication with the medium. Ultrasonic transducer arrangement according to claim 2, characterized in that the electrical connection elements ( 7 ) at least partially on the wall to be audible ( 10 are attached. Ultrasonic transducer arrangement according to one of claims 2 and 3, characterized in that the wall to be penetrated through ( 10 ) is a plastic component. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the indentations ( 8th . 9 ) are formed as grooves extending from front ( 4 ) or back ( 5 ) to the return ( 5 ) or front side ( 4 ) at least partially extend. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the indentations ( 8th . 9 ) at opposite positions of the piezoelectric transducer element ( 2 ) are provided. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the electrical connection elements ( 7 ) also the front ( 4 ) and / or back ( 5 ) of the piezoelectric transducer element ( 2 ) to contact. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the electrical connection elements ( 7 ) are staple-like springs or pins. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the electrical connection elements ( 7 ) to the electrically conductive coating ( 6 ) are glued and / or soldered. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the piezoelectric transducer element ( 2 ) between the electrical connection elements ( 7 ) and the wall to be penetrated ( 10 ) is fixed. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that between front side ( 4 ) of the transducer element ( 2 ) and through-wall ( 10 ) An acoustic coupling means is provided. Ultrasonic transducer arrangement according to one of the preceding claims, characterized in that the rear side ( 5 ) of the transducer element ( 2 ) communicates with air. Flow meter for gaseous or liquid medium with at least one Ultrasonic transducer arrangement ( 1 ) according to any one of claims 1 to 12.

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