Ultrasonic sensor device, parking assistance system, and vehicle

Abstract

The invention relates to an ultrasonic sensor device comprising at least one electromechanical transducer (240) and a diaphragm cup (100), wherein the base (110) of the diaphragm cup (100) comprises a diaphragm (120) and the diaphragm (120) has a longitudinal axis (180), and wherein the diaphragm (120) is delimited, at at least one end (181, 182) of the longitudinal axis (180) and on the inner face (202) of the diaphragm cup (100), by at least one groove (130) and / or at least one hole (330).

Description

[0001] R.415797

[0002] - 1 -

[0003] Description

[0004] Ultrasonic sensor device, parking assistance system and vehicle

[0005] The present invention relates to an ultrasonic sensor device with an electromechanical transducer and a membrane pot, wherein the bottom of the membrane pot has a membrane, the membrane having a longitudinal axis and a transverse axis shorter relative to the longitudinal side, wherein the membrane is bounded at at least one end of the longitudinal axis of the membrane and on the inside of the membrane pot by at least one groove and / or a recess. The invention also relates to a parking assistance system and a vehicle, each comprising an ultrasonic sensor device according to the invention.

[0006] State of the art

[0007] The measuring principle of ultrasonic sensors is based on acoustic ultrasound waves, which are emitted in the range inaudible to humans and reflected by an obstacle. The reflected ultrasound signal is received by the ultrasonic sensor, and the electronics evaluate the signal using a time-of-flight measurement. For different applications, the so-called radiation pattern, or field of view, is specifically adjusted. When using the ultrasonic sensor in a vehicle, for example, a wider radiation pattern in the vertical direction detects more ground reflections, allowing curbs to be detected.A narrower vertical beam pattern or field of view can advantageously reduce or eliminate false detections and increase the range of the ultrasonic measurement. For example, US patent 8031556 B2 discloses the adjustment of a directional characteristic of an ultrasonic sensor. R.415797.

[0008] - 2 -

[0009] Document DE 10 2015 209 878 B3 discloses a method for detecting objects in the vicinity of a vehicle using at least one ultrasonic sensor.

[0010] The document EP 1 855 093 B1 discloses a method for adjusting the resonance frequency of a vibration section of a housing of an ultrasonic sensor.

[0011] Document DE 10 2012 207 160 A1 discloses a sensor arrangement comprising a planar vehicle component and an ultrasonic sensor.

[0012] Document EP 2 133 156 A2 discloses an ultrasonic transducer with a membrane.

[0013] Document DE 101 39 341 A1 discloses an ultrasonic sensor.

[0014] Enlarging the membrane in one direction reduces the stiffness of the membrane housing in that direction. This causes, for example, the bottom of the housing or a side wall to vibrate more strongly when excited or emitted by an electromechanical actuator, resulting in a longer settling time for the entire ultrasonic sensor. This also increases the so-called blind zone, or the minimum detectable distance in front of the ultrasonic sensor, as it becomes impossible to distinguish whether the sensor is still oscillating or has already detected a reflection from an object in the sensor's vicinity.

[0015] Documents JP 2006345271 A, JP 5548560 B2, and JP 5950742 B2 each disclose an ultrasonic sensor in which the diaphragm pot has openings on the outer surface or in the side walls. This makes the fixed clamping of the diaphragm more flexible or more like a fixed bearing compared to a diaphragm pot without openings in the side walls, thereby increasing the bending of the diaphragm for the same force from the electromechanical transducer or electromechanical actuator and increasing the vibrating area of ​​the diaphragm during operation.

[0016] Magnetostriction is an effect in which the mechanical properties of a material are influenced by a magnetic field. Electrostriction is a R.415797

[0017] - 3 - another effect in which the elasticity of a dielectric material is based on an applied electric field.

[0018] The object of the present invention is to improve the directional characteristics of an emitted ultrasound wave or of a field of view of an ultrasound sensor in the vertical direction.

[0019] Disclosure of the invention

[0020] The above problem is solved according to the invention in accordance with independent claims 1, 10 and 11.

[0021] The present invention relates to an ultrasonic sensor device, in particular an ultrasonic sensor for a vehicle. The ultrasonic sensor device comprises at least one electromechanical transducer or an electromechanical actuator, in particular a piezoelectric element or a MEMS (MEMS: micro-electromechanical system). The ultrasonic sensor device also comprises a membrane housing, the bottom of which has a membrane, the membrane having a longitudinal axis and a transverse axis, the transverse axis being shorter relative to the longitudinal axis. The membrane housing comprises, in particular, aluminum and / or a plastic. The membrane or the membrane region advantageously has a thinner wall than the side walls of the membrane housing. The membrane or the membrane region is preferably symmetrical with respect to the longitudinal and transverse axes.According to the invention, the membrane is bounded at at least one end of its longitudinal axis and on the inside of the membrane pot by at least one groove and / or at least one recess. Preferably, the at least one groove and / or the at least one recess are at least partially arcuate. Thus, the base at the at least one groove advantageously has a thinner wall than the membrane itself. In the case of the recess, the base advantageously has an opening at the location of the recess, wherein the opening is preferably closed or filled by a sealing material. The sealing material preferably has a higher elasticity than the material of the base of the membrane pot, so that a fixed bearing-like support of the membrane at the recess results. R.415797.

[0022] - 4 -

[0023] Preferably, the membrane is limited at both ends of the longitudinal axis of the membrane and on the inside of the membrane pot by the groove and / or the recess. The membrane is advantageously mechanically coupled to the electromagnetic transducer, so that the ultrasonic sensor device is configured to emit an ultrasonic wave or an ultrasonic pulse into the environment of the ultrasonic sensor device and to detect a subsequent reflection of the ultrasonic wave or ultrasonic pulse.The arc-shaped groove and / or the arc-shaped recess provides the advantage of a solid-state hinge at at least one end of the longitudinal axis of the diaphragm, thus increasing the deflection of the diaphragm during mechanical movement of the electromechanical transducer and improving, in particular narrowing, the directional characteristic of an emitted ultrasonic wave or of the field of view of an ultrasonic sensor on a vehicle in the vertical direction. In other words, the groove allows for a more rigid bearing-like mounting of the diaphragm, or the recess allows for a rigid bearing-like mounting instead of a rigid clamping of the diaphragm in the base of the diaphragm pot, so that bending of the diaphragm at the groove and / or the recess is increased when the electromechanical transducer is deflected, which in turn increases the effectively vibrating area, thereby improving the radiation characteristic in accordance with the invention.This narrows the directional characteristic of an emitted ultrasonic wave or the field of view of an ultrasonic sensor in the vertical direction. Furthermore, this has the advantage of increasing the maximum range for measuring distance.

[0024] The ultrasonic sensor device is enhanced. Furthermore, the groove and / or recess does not reduce the wall thickness of the side walls of the membrane pot or the membrane, thus advantageously avoiding unwanted wall vibrations and an increased settling time.

[0025] Preferably, the at least one groove and / or the at least one recess encompasses the membrane completely or partially. This design offers the advantage that the directional characteristics of an emitted ultrasonic wave or pulse, or of the field of view of an ultrasonic sensor, can be better adapted in the horizontal and / or vertical direction.

[0026] In a preferred embodiment, the at least one groove and / or the at least one recess is at least partially arcuate. This results in the advantage described in R.415797.

[0027] - 5 - that mechanical stresses at the edges or the boundary of the membrane are reduced and the robustness is increased or the fault-free service life of the ultrasonic sensor is extended.

[0028] In a further development, at least one recess comprises a sealing material which, in particular, closes or seals the recess and the inner volume of the membrane pot against the environment. In other words, in this further development, the recess is filled with the sealing material. This further development increases the bending of the membrane with the same force of the electromagnetic transducer compared to a design with or without a groove on at least part of the membrane boundary by the recess, and simultaneously protects the interior of the ultrasonic sensor from harmful environmental influences.

[0029] In an advantageous embodiment, the membrane pot comprises aluminum or a plastic or polymer, and the sealing material comprises a plastic or polymer, in particular an elastomer. This design increases the diaphragm's deflection at the same electromagnetic actuator force, reduces harmful parasitic vibrations of the membrane pot, and improves the seal against harmful environmental influences.

[0030] Furthermore, the sealing material can be a dielectric medium, and the ultrasonic sensor device can have at least one capacitor arrangement on or in the base and / or on or in the membrane, or near the at least one groove and / or the at least one recess. This allows the stiffness of the support or clamping of the membrane on the base of the membrane housing, or the bending of the membrane, to be adjusted, changed, or switched as needed or as required by generating an electrical voltage or an electric field. By adjusting the electrical voltage of the capacitor arrangement or the strength of the electric field, the field of view of the ultrasonic sensor device can advantageously be variably adjusted.This increases the measurement capability for low objects, such as curbs, reduces measurement errors and increases the range of the ultrasonic sensor device.

[0031] Alternatively or additionally, the sealing material can comprise a ferromagnetic material and the ultrasonic sensor device can include at least one electromagnet, wherein R.415797

[0032] - 6 - The electromagnet is specifically designed to generate a magnetic field in the area of ​​the sealing material. This allows the stiffness of the support, the clamping of the membrane to the base of the membrane housing, or the bending of the membrane to be adjusted, changed, or switched as needed or as required by electrically controlling the electromagnet and the resulting magnetic field. By adjusting the strength of the magnetic field, the field of view of the ultrasonic sensor device can advantageously be variably adjusted. This increases the measurement capability for low objects, such as curbs, reduces measurement errors, and increases the range of the ultrasonic sensor device.

[0033] In another embodiment, the ultrasonic sensor device is configured to at least partially extend or retract the sealing material into the recess using an actuator. This allows the rigidity of the support, the clamping of the membrane to the base of the membrane housing, and the bending of the membrane to be adjusted, changed, or switched by adjusting the positioning or fill level of the sealing material within the recess. This improves the measurement capability for low objects, such as curbs, reduces measurement errors, and increases the range of the ultrasonic sensor device.

[0034] The invention also relates to a parking assistance system comprising at least one ultrasonic sensor device according to the invention.

[0035] The invention also relates to a vehicle comprising at least one ultrasonic sensor device according to the invention and / or a parking assistance system according to the invention.

[0036] Further advantages will become apparent from the following description of exemplary embodiments with reference to the figures.

[0037] Figure 1: Top view into the interior of a membrane pot with grooves on the membrane

[0038] Figure 2: Side view of the membrane pot with grooves on the membrane

[0039] Figure 3: Three-dimensional view of the membrane pot with grooves on the membrane

[0040] Figure 4: Side view of the membrane pot with recesses in the membrane R.415797

[0041] - 7 -

[0042] Figure 5a: Displacements of the membrane when electromechanical force is generated

[0043] Figure 5b: Deflections of an enlarged membrane without a groove

[0044] Figure 6: Directional characteristics of different membranes with and without grooves

[0045] Examples of implementation

[0046] Figure 1 schematically depicts a membrane housing 100 of an ultrasonic sensor device with arcuate grooves 130 in both boundary or edge regions 182, 184 of a membrane at both respective ends 181, 183 of the longitudinal axis 180 of the membrane 120, in a top view of the interior 201 or internal volume of the membrane housing 100. The membrane 120 is arranged at the base 110 of the membrane housing 100. In other words, the base 110 encompasses the membrane 120 or a membrane region. The membrane 120 is mechanically coupled to an electromechanical transducer 240, in particular a piezoelectric actuator or a MEMS, and is configured to be deflected or excited to at least one oscillation by a deflection of the electromechanical transducer, thereby emitting an ultrasonic wave or an ultrasonic pulse. The symmetrical membrane 120 has a transverse axis 190, which is perpendicular to the longitudinal axis 180.In this example, the membrane 120 is mirror-symmetrical with respect to the longitudinal axis 180 and the transverse axis 190. The longitudinal axis 180 is longer than the transverse axis 190, so that the membrane 120 advantageously has an elliptical shape. The arc-shaped grooves 130 encompass and delimit the membrane 120, particularly only in the boundary or edge regions 182, 184 at both respective ends 181, 183 of the longitudinal axis 180. In other words, in this embodiment, there are no grooves and / or recesses in the lateral edge regions 191 and 192 at the two respective ends of the transverse axis 190. At the grooves 130, the thickness or wall thickness of the base 110 is reduced compared to the membrane 120, with the remaining base 110 outside the membrane 120 having a greater wall thickness and higher stiffness than the membrane 120.The arc-shaped grooves 130 for limiting the membrane 120 result in a lower stiffness of the support of the membrane 120 in the base 110, or a more fixed-bearing-like support instead of a fixed clamping of the membrane 120 in the base 110. This reduces bending and R.415797.

[0047] - 8 - the deflection of the diaphragm 120 in the edge regions 182, 184 of the diaphragm 120 is increased by mechanical excitation using the electromechanical actuator 240. In other words, the effectively vibrating diaphragm area along the longitudinal axis is increased by the grooves 130.

[0048] Figure 2 schematically shows a section of the membrane pot 100 along the longitudinal axis 180 and a side view of the membrane pot 100 with grooves 130 on the membrane 120. The membrane 120 is mechanically coupled to an electromechanical transducer 240 on the inside 202 and within 201 of the membrane pot 100; for example, the membrane 120 directly contacts the electromechanical transducer 240. The wall thickness 230 and the thickness of the base 110 at the grooves 130 are reduced compared to the wall thickness 220 and the thickness of the membrane 120. The side walls 210 of the membrane pot 100 typically have a wall thickness 211 and a thickness 211 that is greater than that of the membrane 120. The interior 201 of the membrane pot 100 is typically sealed from the environment 10.

[0049] Figure 3 shows a schematic three-dimensional view of the section of the membrane pot 100 along the longitudinal axis 180 from Figure 2, or the side view of the membrane pot 100 with grooves 130 on the membrane 120 from Figure 2, wherein the groove 130 in the edge region 182 at the end 181 of the longitudinal axis 180 of the membrane 120 is shown enlarged in an additional view of the cutout 400.

[0050] Figure 4 schematically shows a side view of the membrane pot 100 along the longitudinal axis 180, as in Figure 2. However, in Figure 4, recesses 330 are shown instead of grooves, with the recesses 330 delimiting the membrane 120 in the direction of the longitudinal axis 180. The recesses 330 are filled with a sealing material. In other words, the recesses 330 encompass the sealing material, in particular an elastomer. The membrane 120 is also connected to the base 110 of the membrane pot 100 at its ends in the direction of the transverse axis, or rather, firmly clamped in the base 110, or formed integrally with the membrane pot 100 (not shown in Figure 4). The sealing material 330 can, for example, be made in one piece and be connected to the floor 110 in the interior 201 by material and / or form-fitting means, for example by snapping, injection and / or bonding.In a further development, it is planned that the elasticity R.415797.

[0051] - 9 - the sealing material can be variably adjusted by an electromagnet or by a capacitor arrangement (not shown in Figure 4). For this extension, the sealing material comprises at least partially a dielectric medium or dielectric and / or a ferromagnetic material. A dielectric can be, for example, a weakly or non-conductive solid or a weakly or non-conductive gel.

[0052] Figures 5a and 5b, as in Figure 1, schematically depict a membrane pot 100 of an ultrasonic sensor device in a top view of the interior 201 of the membrane pot 100. In Figure 5a, the membrane pot 100 has an arc-shaped groove 130 at each of the end regions 182 and 184 of the longitudinal axis 180 of the membrane 120. In Figure 5b, the membrane pot 100 has a larger membrane 120 and no grooves compared to the membrane pot 100 in Figure 5a. In addition, Figure 5a shows the deflections of the membrane 120, each with a groove 130 at both ends of the longitudinal axis 180, when the electromechanical force of the electromechanical transducer is generated, in color and grayscale, respectively. Figure 5b shows the corresponding deflections of an enlarged membrane without a groove under the same electromechanical force of the electromechanical transducer, respectively, in color or in shades of gray.It can be seen that, based on the same electromechanical force, approximately the same diaphragm deflections can be achieved with either an enlarged diaphragm or with the two grooves. In other words, to reduce the vertical extent of the ultrasonic sensor device's field of view, the diaphragm does not need to be enlarged; instead, two arc-shaped grooves can be provided at the two ends of the diaphragm's longitudinal axis. This results in approximately the same vibration behavior, i.e., the same diaphragm deflections, under the same excitation or electromechanical force, or in the same effect. In other words, although the diaphragm 120 with at least one groove 130 in Figure 5a has a smaller diaphragm area, the effectively vibrating area is essentially the same as that of the larger diaphragm 120 in Figure 5b.

[0053] Corresponding to the essentially identical deflections, the smaller membrane 120 shown in Figure 5a with two arcuate grooves and the larger membrane 120 shown in Figure 5b without a groove result in an essentially identical R.415797

[0054] - 10 -

[0055] Directional characteristic 610, 620 for the emitted ultrasound wave or the emitted ultrasound pulse in the vertical direction, see Figure 6.

Claims

R.415797 - 11 - Claims 1. Ultrasonic sensor device comprising at least the following components • an electromechanical converter (240), and • a membrane pot (100) wherein the bottom (110) of the membrane pot (100) comprises a membrane (120) and the membrane (120) has a longitudinal axis (180), characterized in that the membrane (120) is limited at at least one end (181, 182) of the longitudinal axis (180) and on the inside (202) of the membrane pot (100) by at least one groove (130) and / or at least one recess (330).

2. Ultrasonic sensor device according to claim 1, wherein the membrane (120) is limited at both ends (181, 182) of the longitudinal axis (180) by the groove (130) and / or the recess (330).

3. Ultrasonic sensor device according to one of the preceding claims, wherein the at least one groove (130) and / or recess (330) fully or incompletely or partially encompasses the membrane (120).

4. Ultrasonic sensor device according to one of the preceding claims, wherein the at least one groove (130) and / or the at least one recess (330) is at least partially arc-shaped.

5. Ultrasonic sensor device according to one of the preceding claims, wherein the at least one recess (330) comprises a sealing material which in particular closes the recess (330) against the environment (10) or seals the interior 201 or the internal volume of the membrane pot (100) against harmful environmental influences.

6. Ultrasonic sensor device according to claim 5, wherein the membrane pot (100) comprises aluminium and the sealing material comprises a plastic, in particular an elastomer.

7. Ultrasonic sensor device according to one of claims 5 or 6, wherein the sealing material (330) is a dielectric medium and the ultrasonic sensor device comprises at least one capacitor arrangement on or in the base (110) and / or on or R.415797 - 12 - in the membrane (120) or in the vicinity of the at least one groove (130) and / or the at least one recess (330).

8. Ultrasonic sensor device according to one of claims 5 to 7, wherein the sealing material (330) comprises a ferromagnetic material and the ultrasonic sensor device has at least one electromagnet, wherein the electromagnet is in particular configured to generate a magnetic field in the area of ​​the sealing material.

9. Ultrasonic sensor device according to one of the preceding claims, wherein the ultrasonic sensor device is configured to at least partially extend or retract the sealing material into the recess (330) by means of an actuator.

10. Parking assistance system comprising at least one ultrasonic sensor device according to any one of claims 1 to 9.

11. Vehicle comprising at least one ultrasonic sensor device according to any one of claims 1 to 9 and / or a parking assistance system according to claim 10.

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