WO2013107542A1

WO2013107542A1 - Ultrasound sensor

Info

Publication number: WO2013107542A1
Application number: PCT/EP2012/073216
Authority: WO
Inventors: David Bartylla; Bayar Bayarsaikhan
Original assignee: Robert Bosch Gmbh
Priority date: 2012-01-17
Filing date: 2012-11-21
Publication date: 2013-07-25
Also published as: EP2805321B1; CN104040619B; DE102012200639A1; CN104040619A; EP2805321A1

Abstract

The invention relates to an ultrasound sensor for sending and/or receiving ultrasound signals, comprising a diaphragm cup (3) having a transducer (11) and a housing (7), wherein the diaphragm cup (3) is releasably connected to the housing (7), a decoupling ring (13) is accommodated between the membrane cup (3) and the housing (7), and the membrane cup (3) is filled with a filling material (15). The decoupling ring (13) comprises a lip (27) that is designed in such a way that a gap (31) is formed between the lip (27) and the housing inner wall and the filling material (15) is accommodated in a space at the decoupling ring (13), which space is enclosed by the membrane cup (3) and the lip (27). The invention further relates to a use of the ultrasound sensor.

Description

Ultrasonic sensor description

The invention is based on an ultrasonic sensor according to the preamble of claim 1. Furthermore, the invention also relates to a use of an ultrasonic sensor.

State of the art

A field of application for ultrasonic sensors are, for example, driver assistance systems in motor vehicles. These are the distance to the ultrasonic sensors

Motor vehicle surrounding objects determined. For this purpose, a sound pulse is transmitted by the ultrasonic sensor, which is reflected by an object in the vicinity of the motor vehicle. The reflected echo is received and from the duration of the sound, the distance to the object is determined.

Ultrasonic sensors, as used for example for measuring distances to objects in motor vehicles, usually have a membrane, for example in the form of a diaphragm pot, which can be set in vibration with a sound transducer. As a transducer usually a piezo element is used. The diaphragm pot is connected to a housing with which the ultrasound sensor thus mounted is mounted, for example, in a bumper of a motor vehicle. In order to be able to transmit a defined sound pulse, there is usually a decoupling ring between the diaphragm designed as a diaphragm pot and the housing, by which vibrations are damped. As a result, the transmission of vibrations to the housing and thus the motor vehicle part in which the ultrasonic sensor is mounted, reduced or avoided. Such ultrasonic sensors can be used as transmitters, as receivers or as combined transmitters and receivers. If the ultrasonic sensor is used as transmitter and receiver, then a short sound pulse is sent, waiting for the decay of the membrane and then receive the signal. Upon receiving, the membrane is vibrated again by the impinging sound waves, creating a voltage in the transducer that can be detected. Currently common design for ultrasonic sensors having a diaphragm pot with sound transducer, a decoupling ring and a housing are described for example in DE 10 2006 028 213 A1 or DE 10 2006 050 037 A1.

In order to obtain a fast decay of the membrane, in particular in an ultrasonic sensor used as transmitter and receiver, the diaphragm pot is usually filled with a dampening filling material. The filling material is usually a foam which foams only after introduction into the membrane pot. This may be due to differences in manufacturing accuracy and dosing differences in the

Foaming causes the filling material to escape above the height of the diaphragm pot and also to contact the housing. This gives the possibility that

Structure-borne noise is transmitted from the membrane to the housing through the filling material. However, this vibration transmission through the filler material to the housing is not desirable.

Disclosure of the invention

In order to avoid the disadvantages known from the prior art, an ultrasonic sensor for transmitting and / or receiving ultrasound signals is used according to the invention

proposed, comprising a diaphragm pot with a transducer and a housing, wherein the diaphragm pot is releasably connected to the housing and between the diaphragm pot and housing a decoupling ring is received and the diaphragm pot is filled with a filling material. According to the invention, the decoupling ring has a lip which is designed such that a gap is formed between the lip and the housing inner wall and the filling material is accommodated in a space enclosed by the diaphragm pot and lip on the decoupling ring.

Advantages of the invention

Due to the design of the decoupling ring with the lip, which is designed so that between the housing inner wall and lip a gap is formed, it is avoided that even with different geometric dimensions due to manufacturing tolerances filler material with which the diaphragm pot is filled with the housing in contact comes. The filling material remains in the space surrounded by diaphragm cup and lip. This has the advantage that due to avoiding an unwanted

Vibration transmission from the diaphragm to the housing increases the sound pressure of the sensors and the reverberation time can be reduced. The increased sound pressure allows a measurement of longer distances and the reduced ringing time in turn, the measurement of shorter distances, since the distance between the end of the transmission of a signal to the reception of a signal can be chosen smaller. In addition, a more even decay time can be realized, whereby defined waiting times between transmission mode and reception mode of the sensor can be set. Another advantage of the solution according to the invention is that only the geometry of the decoupling ring is changed and thereby current manufacturing processes for the

Ultrasonic sensor can be maintained.

Since a vibration transmission from the diaphragm pot to the housing to be suppressed by the decoupling ring, the decoupling ring is made of a damping material. As a material for the preparation of the decoupling ring, for example, a rubber-elastic material is suitable. Suitable rubber-elastic materials are, for example, natural or synthetic rubber or a thermoplastic elastomer. Preferred is the rubber-elastic material from which the decoupling ring is made, selected from natural rubber, styrene-butadiene copolymers (SBR), polybutadiene, polyisoprene, polychloroprene, nitrile rubber, silicone rubber, polyisobutylene,

Butyl rubber, ethylene-vinyl acetate rubber, ethylene-propylene copolymers

(EPM / EPDM), silicones, silicone gels and silicone foams, for example Fermasil®. Particularly preferred as material for the decoupling ring are ethylene-propylene copolymers, for example EPM or EPDM.

The decoupling ring usually has the same shape as the circumference of the

Diaphragm cup. In general, the decoupling ring is therefore rotationally symmetric, that is designed circular. In addition to a circular design but any other design, for example, as a polygon, for example, with three, four or six corners or the design in the form of an ellipse is conceivable. Any other form for the decoupling ring is possible. Preferably, however, the decoupling ring is rotationally symmetrical circular. Since the decoupling ring completely surrounds the diaphragm pot, the lip extends in the axial direction to the symmetry axis of the decoupling ring. Depending on the design of the diaphragm pot and the Housing, it is also possible that the lip, for example, has an angle to the axis of symmetry. Hereby, the space laterally delimited by the lip can, for example, be rejuvenated or widened. It is only essential that the lip does not touch the housing. It is preferred if the lip is aligned in the same direction as the side walls of the diaphragm pot.

In a particularly preferred embodiment, the decoupling ring has a

Contact area, in which the decoupling ring rests with one side on the diaphragm pot and with an opposite side to the housing, wherein the decoupling ring has at least one rib in the contact region. The rib is preferably designed circumferentially.

By preferably circumferentially shaped rib in the contact area, it is possible to reduce the rigidity of the decoupling ring in this area. Due to the lower rigidity, less structure-borne noise is transmitted from the diaphragm pot to the housing. By increasing the number of fins, the amount of air voids is increased and the rigidity of the decoupling ring is further reduced, resulting in further reduced transmission of structure-borne noise from the diaphragm pot to the housing.

The height of the lip is preferably chosen so that the filling material, with which the diaphragm cup is filled, does not penetrate via the lip into the gap between the decoupling ring and the housing inner wall. The height of the lip is to be chosen so that even with different dimensions of the space formed by the diaphragm pot and the lip due to manufacturing tolerances and due to manufacturing tolerances

each amount of filler material is ensured that no filler material penetrates through the lip in the gap between the decoupling ring and housing inner wall. The height of the lip is therefore preferably chosen so that with minimal height of the space formed by diaphragm pot and lip and maximum capacity nor the entire filler after foaming remains in the space formed by diaphragm cup and lip and not on the lip in the gap between the lip and Housing inner wall penetrates.

The sound transducer, which is used to generate a sound signal or, in the receiving mode of the ultrasonic sensor, a sound signal impinging on the sensor is preferably a piezo transducer. In addition to a piezo transducer but any other known to the expert sound transducer is used. However, the use of a piezoelectric transducer is preferred since it allows the transmission of defined pulses.

The filling material used for damping in the ultrasonic sensor is preferably a closed-cell polymer foam. Any suitable polymer foam known to the person skilled in the art is suitable here. It is particularly preferred if the polymer foam is a silicone-based foam. Such a closed-cell polymer foam

Silicone base is available, for example, under the trade name Fermasil® from Sonderhoff Chemicals GmbH. In addition to closed-cell foams based on silicone, however, closed-cell polyurethane-based foams are also suitable, for example.

The inventively designed ultrasonic sensor is suitable for example as

Distance sensor in a driver assistance system, in which case the ultrasonic sensor is mounted on the vehicle and is used to measure the distance to objects around the vehicle. In addition to the use in driver assistance systems, the

Ultrasonic sensor according to the invention also be used for example in driverless transport systems.

The ultrasonic sensor according to the invention is particularly preferably used as a distance sensor for driver assistance systems in motor vehicles or in driverless transport systems.

Brief description of the drawings

Embodiments of the invention are illustrated in the figure and are explained in more detail in the following description.

The single FIGURE shows a sectional view of an inventively designed ultrasonic sensor.

EXEMPLARY EMBODIMENTS OF THE INVENTION The single FIGURE shows an ultrasound sensor designed according to the invention. An ultrasonic sensor 1 comprises a diaphragm pot 3, which is fastened to a housing 7 with a union nut 5. At the bottom 9 of the diaphragm pot 3, a sound transducer 1 1 is mounted on the inner side. With the sound transducer 1 1 ultrasonic pulses are generated, which set the bottom 9 of the diaphragm pot 3 in vibration. The vibrations are output to the outside, whereby a sound pulse is sent from the ultrasonic sensor 1. The transmitted sound pulse is reflected in the presence of an object of this object and the echo is received from the bottom 9 of the diaphragm pot 3. As a result, the bottom 9 of the diaphragm pot 3 is vibrated, which are transmitted to the transducer 1 1. The vibrations are detected by the transducer 1 1 and converted into a signal. In this way, the distance to the object can be determined by the sound transit time from the transmission of the signal to the reception of the reflected echo. As a transducer 1 1 is usually a piezoelectric element is used.

In order to be able to measure even short distances to objects, in particular when using the ultrasonic sensor 1 as transmitter and receiver, it is necessary to let the vibrations decay quickly after the transmission of the sound pulse. For this purpose, the diaphragm pot 3 is preferably filled with a dampening filling material 15. The filling material 15 is preferably a closed-cell polymer foam, preferably a

Closed-cell polymer foam based on silicone.

In order to reduce a sound transmission from the diaphragm pot 3 to the housing 7 or exclude as possible is between the diaphragm pot 3 and the housing 7 a

Decoupling ring 13 was added. In order to exclude a sound transmission from the diaphragm pot 3 via the union nut 5 on the housing 7, the union nut 5 is also on the decoupling ring 13 and not directly on the diaphragm pot 3. For mounting, the diaphragm pot has a collar 17, which is enclosed by the decoupling ring 13. Here, the decoupling ring 13 is applied to the collar 17. With the

Union nut 5, the decoupling ring 13 is pressed against the collar 17 and so the diaphragm pot 3 is connected to the housing 7. So that the decoupling ring can act as such and the transmission of vibrations from the diaphragm pot 3 to the housing 7 are minimized, the decoupling ring 13 is made of a damping material. Suitable damping materials are in particular, as already described above, elastomers. In order to further minimize the transmission of structure-borne noise from the diaphragm pot 3 to the housing 7, the decoupling ring is preferably formed with a low rigidity. For this purpose, the decoupling ring 13 has a contact region 19. In the contact region 19 of the decoupling ring 13 is located with a first side 21 on the diaphragm pot 3. With one of the first side 21 opposite side 23 of the decoupling ring 13 is located on the housing 7.

A reduction of the rigidity is achieved by the contact region 19 having at least one rib 25. By the ribs, it is possible to reduce the wall thickness of the decoupling ring 13 and thereby reduce the rigidity. The ribs are the areas that rest on the diaphragm pot 3 or on the housing 7. For this purpose, the ribs 25 are preferably designed circumferentially in the contact region of the decoupling ring 13. In addition to a straight course, the ribs, for example, alternatively

zigzagged or undulating. The number of ribs results from the desired reduction of the wall thickness of the decoupling ring and the width of the collar 17 on the diaphragm pot 3. The reduced wall thickness of the decoupling ring 13 with the ribs 25 which rest against the diaphragm pot 3 and the housing 7 leads to the formation of several air cavities 28 between diaphragm pot 3 and decoupling ring 13th

or between decoupling ring 13 and housing 7th

By reducing the transmission of structure-borne noise due to the reduction of the rigidity of the decoupling ring, it is possible to minimize or eliminate unwanted spurious signals resulting from transmission to the housing.

According to the invention, the decoupling ring 13 furthermore has a lip 27. The lip 27 is preferably formed circumferentially on the decoupling ring 13. In a

Embodiment, as shown in Figure 1, the lip is aligned in the axial direction parallel to a symmetry axis 29. The lip is designed so that a gap 31 between the lip 27 and the housing 7 is formed. In addition to the paraxial

Alignment of the lip 27, as shown in the figure, it is also possible that the lip 27 has an inclination to the axis of symmetry 29, wherein the lip can be both inclined so that a diaphragm cup 3 and the lip 27 enclosed space 33 widened in the region of the lip 27 or, alternatively, tapers in the area of the lip 27 as well. In an extension, the lip points with increasing distance from the diaphragm pot 3 outwardly away from the axis of symmetry 29 and at a taper of the diameter of the space, the lip 27 with increasing distance from the diaphragm pot 3 in the direction of the axis of symmetry 29th

Since during the assembly of the ultrasonic sensor the sound transducer 1 1 is usually used only after the assembly of diaphragm pot 9 and housing 7 and is generally connected by gluing to the diaphragm pot 9, it is necessary that the diameter of the space 33 is kept so large, that mounting the transducer after mounting the other components of the ultrasonic sensor 1 is still possible. After insertion of the transducer 1 1 and the assembly of the space 33 is filled with the filler 15. For this purpose, the filling material 15 is preferably introduced in the form of a liquid in the space 33, wherein the liquid cures after introduction into the space 33 and thereby foams. The filler material is usually a material that after the

Foaming forms a closed-cell foam, preferably based on silicone. The filling material 15 serves for damping, so that a fast decay is achieved after sending a sound pulse. To avoid that by the filler 15

Vibrations are transmitted to the housing 7, the lip 27 is formed on the decoupling ring 13 according to the invention. This prevents the filling material 15 with the

Housing 7 comes into contact. The height of the lip 27 is selected so that the filling material 15 does not flow via the lip 27 into the gap 31 after foaming. Through the lip 27 can manufacturing differences, for example, due to

Manufacturing tolerances result, be balanced. For example, it is possible that the height of the side wall 35 of the diaphragm pot 3 deviates due to the

Manufacturing tolerance occupies. Also, the amount of foaming liquid that forms the filler 15 may vary within manufacturing tolerances. The height of the lip 27 is chosen so that at minimum height of the side wall 35 of the diaphragm pot 13 and maximum amount of filler after foaming no filler 15 via the lip 27 in the Gap 31 arrives. As a result, on the one hand optimal damping of the sound transducer 1 1 is achieved after the termination of a signal and on the other avoided that structure-borne noise are transmitted via the filling material 15 from the transducer 1 1 to the housing 7. In order to increase the stability of the lips 27, it is possible to make them wavy or zigzag, for example, or to provide them with reinforcing ribs.

Claims

claims

1 . Ultrasonic sensor for transmitting and / or receiving ultrasonic signals, comprising a diaphragm pot (3) with a sound transducer (1 1) and a housing (7), wherein the

Membrane pot (3) with the housing (7) is detachably connected and between the diaphragm pot (3) and housing (7) a decoupling ring (13) is received and the diaphragm pot (3) with a filling material (15) is filled, characterized in that the decoupling ring (13) has a lip (27) which is designed so that between lip (27) and

Housing inner wall a gap (31) is formed and the filling material (15) in a diaphragm pot (3) and lip (27) on the decoupling ring (13) enclosed space (33) is accommodated.

2. Ultrasonic sensor according to claim 1, characterized in that the

Decoupling ring (13) is made of a rubber-elastic material.

3. Ultrasonic sensor according to claim 2, characterized in that the

rubber elastic material is a natural or synthetic rubber or a

thermoplastic elastomer is.

4. Ultrasonic sensor according to claim 2 or 3, characterized in that the rubber-elastic material is selected from natural rubber, styrene-butadiene copolymers (SBR), polybutadiene, polyisoprene, polychloroprene, nitrile rubber, silicone rubber, polyisobutylene, butyl rubber, ethylene-vinyl acetate rubber and ethylene Propylene copolymers (EPM / EPDM).

5. Ultrasonic sensor according to one of claims 1 to 4, characterized in that the decoupling ring (13) is rotationally symmetrical and the lip (27) extends in the axial direction.

6. Ultrasonic sensor according to one of claims 1 to 5, characterized in that the height of the lip (27) is chosen so that the filling material (15) not via the lip (27) in the gap (31) between the decoupling ring (13) and housing inner wall penetrates.

7. Ultrasonic sensor according to one of claims 1 to 6, characterized in that the decoupling ring (13) has a contact region (19), in which the decoupling ring (13) with a first side (21) on the diaphragm pot (3) and with one of the first side (21) opposite side (23) on the housing (7), wherein the decoupling ring (13) in the contact region (19) has at least one preferably circumferential rib (25).

8. Ultrasonic sensor according to one of claims 1 to 7, characterized in that the sound transducer (1 1) is a piezoelectric transducer.

9. Ultrasonic sensor according to one of claims 1 to 8, characterized in that the filling material (15) is a closed-cell polymer foam.

10. Ultrasonic sensor according to one of claims 1 to 9, characterized in that the polymer foam is a silicone-based foam.

1 1. Use of an ultrasonic sensor according to one of claims 1 to 10 as a distance sensor in a driver assistance system of a motor vehicle or as

Distance sensor in a driverless vehicle.