WO2016173947A1

WO2016173947A1 - Method and device for producing an ultrasonic sensor for a motor vehicle

Info

Publication number: WO2016173947A1
Application number: PCT/EP2016/059042
Authority: WO
Inventors: Wolfgang Katzenberger; Lukas Berger; Markus Osterrieder; Ceren OEZAYDIN
Original assignee: Valeo Schalter Und Sensoren Gmbh
Priority date: 2015-04-28
Filing date: 2016-04-22
Publication date: 2016-11-03
Also published as: DE102015106484A1

Abstract

The invention relates to a method for producing an ultrasonic sensor (1) for a motor vehicle by providing a membrane (2) for emitting and/or receiving an ultrasonic signal, providing a piezoelectric element (3) for exciting the membrane (2) and/or generating an electrical signal on the basis of the received ultrasonic signal, connecting the piezoelectric element (3) and the membrane (5) by means of an adhesive (6) and providing infrared radiation by means of an infrared radiation source (18) for the curing of the adhesive (6).

Description

Method and device for producing an ultrasonic sensor for a motor vehicle

The present invention relates to a method for producing an ultrasonic sensor for a motor vehicle by providing a membrane for emitting and / or receiving an ultrasonic signal, providing a piezoelectric element for exciting the membrane and / or generating an electrical signal due to the received ultrasonic signal and connecting the piezoelectric element and the membrane by means of an adhesive. The present invention also relates to an apparatus for manufacturing an ultrasonic sensor for a motor vehicle.

Ultrasonic sensors are already state of the art. They are usually used in the so-called parking aid system to help the driver maneuver

To support motor vehicle. The ultrasonic sensors measure the distances between the motor vehicle on the one hand and the obstacles located in its surroundings on the other hand. By means of a membrane, an ultrasound is emitted, which then reflects on the obstacle in the vicinity of the motor vehicle and returns to the ultrasound sensor, in the form of an echo. This ultrasound is received using the membrane. To send out the ultrasound is the

Membrane excited by a piezoelectric element (piezoelectric element). And vice versa, when the membrane is excited by the received ultrasound, the piezo element also stimulated generates an electrical signal which can be evaluated with regard to the distances. The distance measurement takes place as a function of the transit time of the emitted ultrasound.

Thus, the excitation of the membrane can be particularly effective using the piezoelectric element and vice versa, the electrical signal can be generated very precisely by the piezoelectric element, the piezoelectric element is usually using a

Adhesive bonded to the membrane.

For this purpose DE 10 2009 019 667 A1 describes a method for adhering

Piezoceramic components on a carrier body, in which in a first step, a transportable in a production machine tape is produced, which has a printed with adhesive surfaces base film. Next, the tape is provided with a cover sheet. In a further method step, the cover film is removed for joining the piezoceramic component with the adhesive surface and the piezoceramic component is pressed in each case on the adhesive surface. It can thereby be achieved that the final strength of the arrangement can already be achieved by a simple pressing.

Furthermore, DE 10 201 1 120 391 A1 discloses an ultrasonic sensor for a

Motor vehicle having a membrane for emitting and / or receiving ultrasound and a piezoelectric element which is connected to the membrane by means of a liquid adhesive. The adhesive is a cold curing anaerobic adhesive, which preferably hardens under exclusion of air. In this case, it can also be provided that the adhesive is additionally a UV-curing adhesive. So it can be used a total of a dual-curing adhesive, which cures both alone under exclusion of air as well as alone under UV radiation.

In addition, a method for producing an ultrasonic transducer for use in a fluid medium is described in DE 10 2008 055 1 16 A1. In this case, at least one piezoelectric transducer element is connected directly or indirectly with at least one matching body to favor a vibration coupling between the piezoelectric transducer element and the fluid medium. In this case, the piezoelectric transducer element and the matching body can be connected to each other by means of a bond. The adhesive may be, for example, a UV-curing adhesive, which is optionally fully cured under the influence of heat.

In addition, from DE 10 2012 207 871 A1 a method for producing a

Ultrasonic transducer for use in a fluid medium known. Of the

Ultrasonic transducer has an intermediate element between an electromechanical transducer element and a matching body. The intermediate element is adhered to the electromechanical transducer using a photocuring adhesive. The photochemical curing can be additionally supported by a thermal action, for example by infrared radiation. The excitation light penetrates the intermediate element at least partially. The

Intermediate element can be made of glass or crystal.

It is an object of the present invention to provide a solution, such as a

Ultrasonic sensor or the type mentioned can be made faster and cheaper. This object is achieved by a method, by a device and by an ultrasonic sensor having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

An inventive method is used to produce an ultrasonic sensor for a motor vehicle. The method includes providing a membrane for emitting and / or receiving an ultrasonic signal. In addition, the method comprises providing a piezoelement for exciting the membrane and / or generating an electrical signal on the basis of the received ultrasound signal. Furthermore, the method comprises connecting the piezoelectric element and the membrane by means of a

Adhesive. Finally, the method includes providing infrared radiation by means of an infrared radiation source for curing the adhesive.

The membrane of the ultrasonic sensor may be made of aluminum, for example. The membrane may in particular be designed pot-shaped and have a membrane bottom and a membrane wall. The piezoelectric element may in particular comprise a piezoelectric material. For example, the piezoelectric element may comprise a piezoelectric ceramic on which a metallization for electrical

Contacting the piezoelectric ceramic is applied. The piezoelectric element is adhesively bonded to the membrane by means of the adhesive. For emitting the ultrasonic signal, an electrical voltage can be applied to the piezoelectric element. This causes the piezoelectric element and the mechanically mechanically coupled to the piezoelectric element membrane to be excited to mechanical vibrations. To the

Receiving the ultrasonic signal, the voltage generated by the piezoelectric element can be measured as a function of time. When the ultrasonic signal impinges on the membrane, in particular, the piezoelectric element is excited to mechanical vibrations. These mechanical vibrations cause an electrical voltage to be tapped at the piezoelectric element.

In the present case, the adhesive can be applied in liquid form to a rear side of the membrane bottom on an inner side of the membrane. Then that can

Piezo element are arranged on the adhesive. To cure the adhesive, infrared radiation is provided by means of an infrared radiation source. The infrared radiation is provided in particular by means of the infrared light source or by means of an infrared radiator such that it impinges from outside on the membrane bottom or on a front side of the membrane base. By the Infrared radiation generates thermal energy through which the adhesive

can be cured. By means of the infrared light source, the energy can be transferred without contact by the infrared radiation, wherein the energy is converted into heat only with the absorption in the adhesive to be heated. The use of infrared radiation to generate heat has the advantage over shorter manufacturing processes, for example using continuous furnaces

Process times can be achieved. This allows, for example, that the adhesive can be cured within a process time of a few minutes. When using furnaces usually process times of a few hours can be achieved. Thus, the production of the ultrasonic sensor can be done faster and thus cheaper. In addition, it requires no intermediate element, which is formed for example of glass or a crystal to connect the piezoelectric element with the membrane. The use of infrared radiation also has the advantage that only a local heating takes place. Furthermore, the infrared radiation can be provided over short distances and also a precise controllability can be made possible. The infrared radiation is also not harmful to health. In addition, the infrared light source can be provided inexpensively.

In one embodiment, the piezoelectric element and the membrane are connected by means of a dual-curing adhesive. In other words, the adhesive can be cured by means of two different curing mechanisms. The adhesive may include, for example, an acrylate. This is particularly suitable in the production of ultrasonic sensors in which areas of the adhesive are sealed off from irradiation by means of a radiation source.

Preferably, the adhesive is additionally irradiated with ultraviolet radiation by means of a light source. As a light source, for example, a corresponding UV light source can be used here. Thus, with the light source, ultraviolet radiation may be radiated to at least a predetermined area of the adhesive. Thus, in addition to infrared radiation, the adhesive can also be irradiated with ultraviolet radiation and thus cured by means of different curing mechanisms.

In one embodiment, a first region of the adhesive, which is located outside a gap between the piezoelectric element and the membrane, cured by means of the ultraviolet radiation. In the intermediate region between the membrane and the piezoelectric element is the area or proportion of the adhesive which is covered or shaded by the piezoelectric element. One of This area of different first area of the adhesive, which is outside the intermediate area or an edge area, can be cured by means of the ultraviolet radiation. Thus, this border area

or residual ring of the adhesive, for example, first cured. Thus, a prefixing of the piezoelectric element to the membrane can be achieved.

In one embodiment, a second region of the adhesive, which is located in the intermediate space between the piezoelectric element and the membrane, is cured without contact by means of the infrared radiation. The second region or the second portion of the adhesive, which is located in the intermediate region is through the

Piezo element covered or shaded. This second area of the

Adhesive can now be cured by the action of infrared radiation. The curing of the second region of the adhesive by means of the infrared radiation preferably takes place after the curing of the first region of the adhesive by means of the ultraviolet radiation. Thus, the adhesive in the second area can be cured reliably.

In one embodiment, the membrane and the piezoelectric element that are provided are opaque to the ultraviolet radiation. This means that the second area of the adhesive can not be cured by means of the ultraviolet radiation. Thus, as already explained, the infrared radiation with which this second region can be cured is used. Thus, a reliable bond between the membrane and the piezoelectric element can be provided.

The thermal energy provided by the infrared radiation source during curing of the adhesive is preferably controlled. With a corresponding

Radiation sensor, in particular a pyrometer, can with a

Infrared radiation source provided radiation energy or thermal energy are detected. Depending on the detected thermal energy, the radiant power provided by the infrared radiation source can then be adjusted. It can also be provided that the radiation provided with the infrared radiation source is regulated by means of a corresponding control loop. Thus, it can be guaranteed that the curing process of the adhesive takes place reliably.

Furthermore, it is advantageous if, after a predetermined cooling time at least one electrical connection element is soldered to the piezoelectric element. In particular, two electrical connection elements can be soldered to the piezoelectric element. By These electrical connection elements, which are formed for example as a cable, the piezoelectric element can be subjected to an electrical voltage. In addition, the electrical voltage generated by the piezoelectric element can be tapped off via the electrical connection elements. In this case, the predetermined cooling time can be selected so that the piezoelectric element after expiration of the predetermined cooling time has approximately room temperature.

A device according to the invention serves to produce an ultrasonic sensor for a motor vehicle. The device according to the invention is for performing a

designed according to the method. The device may in particular comprise an infrared light source. The device may include multiple manufacturing devices. In a manufacturing device, for example, the adhesive can be applied to the membrane and then the piezoelectric element are applied to the adhesive. In a further production device, the first region of the adhesive can be irradiated by means of the ultraviolet radiation. In another

Manufacturing device, the second region of the adhesive by means of

Hardened infrared light source.

An inventive ultrasonic sensor for a motor vehicle is produced according to a method according to the invention or by means of a device according to the invention.

The preferred embodiments presented with reference to the process according to the invention

Embodiments and their advantages apply correspondingly to the device according to the invention and to the ultrasonic sensor according to the invention.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures, are not only in the respectively indicated combination but also in others

Combinations or alone, without departing from the scope of the invention. Thus, embodiments of the invention are to be regarded as encompassed and disclosed, which are not explicitly shown and explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained. There are also versions and feature combinations as disclosed therefore do not have all the characteristics of an originally formulated independent claim.

The invention will now be described with reference to preferred embodiments and with reference to the accompanying drawings.

Showing:

1 shows a schematic representation of a cross section through a membrane and a piezoelectric element of an ultrasonic sensor according to an embodiment of the invention;

FIG. 2 is a schematic representation of the ultrasonic sensor; FIG. and

Fig. 3 shows a schematic representation of an apparatus for producing the

Ultrasonic sensor.

In the figures, the same or functionally identical elements are the same

Provided with reference numerals.

In Fig. 1, an ultrasonic sensor 1 is shown in a schematic representation, which has a membrane 2 and a piezoelectric element 3, that is, a piezoelectric element. The membrane 2 may, for example, be arranged on a base 4, so that it is supported by the base 4. The membrane 2 is made of aluminum and serves to emit ultrasonic waves. It can also serve to receive reflected ultrasonic waves. To emit the ultrasonic waves, the membrane 2 is excited to a mechanical vibration, namely by means of the piezoelectric element 3. For this purpose, an electrical voltage is applied to the piezoelectric element 3, due to which the piezoelectric element 3 and thus the associated membrane are excited to vibrate. When receiving the ultrasonic waves, in turn, the membrane 2 is excited by these ultrasonic waves, so that the piezoelectric element 3 comes into mechanical vibration and generates an electrical signal. This electrical signal can then be evaluated in terms of distances, such as by means of a

Computing device. The piezoelectric element 3 is arranged on a rear side 5 of the membrane 2 fittingly, namely mediated by an adhesive 6. This means that the piezoelectric element 3 is firmly connected by means of the adhesive 6 with the back 5 of the membrane 2, so that the piezoelectric element 3 together with the membrane 2 can swing.

The adhesive 6 has two different areas. A first region 10 is located outside a gap between the membrane 2 and the piezoelectric element 3. The first region 10 of the adhesive 6, which is not covered by the piezoelectric element 3, can - as explained in more detail below - cured by means of ultraviolet radiation or UV radiation become. A second region 1 1 of the adhesive 6 is located in the intermediate space between the membrane 2 and the piezoelectric element 3. This second region 1 1 of the adhesive 6 is thus covered by the piezoelectric element. The second region 1 1 of the adhesive 6 can - as explained in more detail below - means

Cured infrared radiation.

As is apparent from Fig. 2, the piezoelectric element 3 has the circular shape and is formed in the form of a thin plate. The piezoelectric element 3 is therefore a circular disc which can be inserted into a sensor housing 7, as shown schematically in FIG. 2 by means of arrow representations 8. The sensor housing 7 is formed for example of plastic. It can be provided that the

Sensor housing 7 is formed in one or more parts. It also has one

Terminal area 9, via which the ultrasonic sensor 1 with said

Computing device can be electrically coupled, for example via a communication bus of the motor vehicle.

FIG. 3 shows a schematic illustration of a device 12 for producing the ultrasound sensor 1. The device 12 may have a plurality of manufacturing devices, not shown here, in which the ultrasonic sensor 1 is produced in succession. This is illustrated in the present case by the arrows 14. The preparation can be done for example manually, semi-automatically or fully automated. Here, the ultrasonic sensors 1 individually or more of the ultrasonic sensors 1 in pallets can be processed simultaneously or sequentially.

The upper area of FIG. 3 describes the manufacture of the ultrasonic sensor 1 at a first production facility. In this case, the ultrasonic sensor 1 is located on a first working surface 13. Here, as already explained in connection with FIG. 2, the adhesive 6 is applied to the membrane 2 and then the piezoelectric element 3 is applied to the adhesive 6.

In the central region of Fig. 3 is a further manufacturing step at a

Manufacturing device shown. In this case, the ultrasonic sensor 1 is located on a second working surface 15. In this case, the ultrasonic sensor is irradiated by means of a light source 16 or a UV light source with UV radiation. In particular, the first region 10 of the adhesive 6 is irradiated with the UV radiation and thus cured. Thus, the edge region of the adhesive 6 can be cured. With the light source 16, radiation in a wavelength range can be adapted to the adhesive 6, in particular to its thickness and / or to the amount of inhibitors in the adhesive 6. With the light source 16, a radiation intensity can be provided which corresponds to the desired cycle time, measured in watts per square meter. The

Curing of the adhesive 6 or the first region 10 of the adhesive 6 can be adjusted over the exposure time.

The lower area of FIG. 3 describes a further step in the production of the ultrasonic sensor 1 by means of a production device. Here, the ultrasonic sensor 1 is arranged on a third work surface 16, which may be formed for example by a thin metal plate. Furthermore, an infrared radiation source 18 is provided, by means of which infrared radiation can be provided. These

For example, infrared radiation source 18 may have a power in a range between 1 and 3 kilowatts and a maximum power density in a range between 5 and 30 watts per square centimeter, but may vary depending on the materials used, adhesive 6, and wall thicknesses. Thus, a spectral maximum can be in a range between 500 and 1000 nanometers. The irradiation time during which the adhesive 6 or the second region 11 of the adhesive 6 is irradiated with infrared radiation may be, for example, 1 minute. The infrared radiation provided with the infrared radiation source 18 can be monitored by means of a pyrometer 19. Depending on the measurement signals of the pyrometer 19, the radiant power provided with the infrared radiation source 18 can be controlled.

Following irradiation with the infrared radiation source 18, the

Ultrasonic sensor 1 for a predetermined cooling time, which is, for example, 20 minutes, are cooled, so that the ultrasonic sensor 1 substantially

Room temperature reached. Then then electrical connection devices be soldered to the piezoelectric element 3. The connection elements can be, for example, corresponding cables. For soldering a corresponding solder paste can be used.

Claims

claims

1 . A method of manufacturing an ultrasonic sensor (1) for a motor vehicle

Providing a membrane (2) for emitting and / or receiving an ultrasonic signal,

- Providing a piezoelectric element (3) for exciting the membrane (2) and / or for generating an electrical signal due to the received

Ultrasonic signal and

- Connecting the piezoelectric element (3) and the membrane (5) by means of a

Adhesive (6),

marked by

- Providing infrared radiation by means of an infrared radiation source (18) for curing the adhesive (6).

2. The method according to claim 1,

characterized in that

the piezoelectric element (3) and the membrane (2) are connected by means of a dual-curing adhesive (6).

3. The method according to claim 1 or 2,

characterized in that

the adhesive (6) is additionally irradiated with ultraviolet radiation by means of a light source (16).

4. The method according to claim 3,

characterized in that

a first region (10) of the adhesive (6) which extends outside of

Interspace between the piezoelectric element (3) and the membrane (2) is cured by means of the ultraviolet radiation.

5. Method according to one of the preceding claims,

characterized in that

a second region (1 1) of the adhesive (6) extending in the space between the piezoelectric element (3) and the membrane (2) is cured by means of infrared radiation.

6. The method according to any one of the preceding claims,

characterized in that

the diaphragm (2) and the piezoelectric element (3) which are provided are impermeable to the ultraviolet radiation.

7. The method according to any one of the preceding claims,

characterized in that

controlling the thermal energy provided upon curing of the adhesive (6) by means of the infrared radiation source (18).

8. The method according to any one of the preceding claims,

characterized in that

after expiration of a predetermined cooling time at least one electrical

Connection element to the piezoelectric element (3) are soldered.

9. Device (12) for producing an ultrasonic sensor (1) for a motor vehicle, which is designed for carrying out a method according to one of the preceding claims, wherein the device (12) comprises an infrared light source (18).