[go: up one dir, main page]

WO2009095165A2 - Détecteur de collision à déformation et procédé de contrôle de son fonctionnement - Google Patents

Détecteur de collision à déformation et procédé de contrôle de son fonctionnement Download PDF

Info

Publication number
WO2009095165A2
WO2009095165A2 PCT/EP2009/000284 EP2009000284W WO2009095165A2 WO 2009095165 A2 WO2009095165 A2 WO 2009095165A2 EP 2009000284 W EP2009000284 W EP 2009000284W WO 2009095165 A2 WO2009095165 A2 WO 2009095165A2
Authority
WO
WIPO (PCT)
Prior art keywords
cavity
collision sensor
collision
sound
sensor according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2009/000284
Other languages
German (de)
English (en)
Other versions
WO2009095165A3 (fr
Inventor
Manfred Sondergeld
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG
Original Assignee
Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG filed Critical Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG
Priority to EP09706095A priority Critical patent/EP2247471A2/fr
Publication of WO2009095165A2 publication Critical patent/WO2009095165A2/fr
Publication of WO2009095165A3 publication Critical patent/WO2009095165A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R21/013—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over
    • B60R21/0136—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over responsive to actual contact with an obstacle, e.g. to vehicle deformation, bumper displacement or bumper velocity relative to the vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R2021/01006—Mounting of electrical components in vehicles

Definitions

  • the invention relates to a collision sensor with a deformable cavity, with at least one acoustic sensor element connected to the cavity, with an evaluation unit connected to the sensor element, and with an acoustic actuator connected to the cavity for coupling preferably standing sound waves in the cavity, wherein the evaluation unit is designed to evaluate signals generated by the sound waves in the sensor element.
  • the invention further relates to a plurality of methods for verifying the function of a collision sensor having a deformable cavity.
  • a collision sensor of the type mentioned above is known from DE 10 2004 034 877 A1 and WO 2006/008298 A1. From DE 10 2004 003 199 Al collision systems and methods of the type mentioned above are known.
  • collision sensors which detect when the motor vehicle collides with an obstacle.
  • the obstacle may be another moving vehicle, a moving object, a space-locked obstacle or a pedestrian.
  • different devices are known, in particular for a frontal collision, a side impact, a rear impact, a rollover and a personal impact.
  • Collision sensors are also used in industrial safety technology, where high protection and safety requirements may even have to be met in compliance with standards in order to safely and reliably protect man and machine in dangerous situations of industrial use.
  • These are machine and personnel protection devices of all kinds, especially for machine safety in assembly, handling and robotics, as well as for personal safety and accident prevention in access control, access control, and attendance monitoring. Particularly in work areas with potential danger, there are high demands on safety devices for personal safety.
  • the permanent monitoring functions required for this purpose are realized by sensors which are sensitive to the environment and deliver a control signal directly and immediately after the occurrence of a dangerous situation to a downstream safety device.
  • contacting sensory security elements are used in particular in the presence of pinch edges, such as, for example, tactile switches, contact strips, contact buffers and contact mats.
  • pinch edges such as, for example, tactile switches, contact strips, contact buffers and contact mats.
  • to be monitored crushing edges can be found, for example, on doors, gates, protective gates, road and area boundaries of traffic areas, etc.
  • the monitoring is eg. For sliding gates, rolling gates, lifts, theater stages, machine doors, automatic doors, for example.
  • Forklift trucks, driverless transport systems, high bay warehouses, hangar doors, and passenger boarding bridges these lists being merely exemplary and not exhaustive.
  • the known sensory switching elements utilize different physical effects and are defined by their limit values for the action of force, the duration of action, the switching path and the overtravel path for the eradication of the impact energy.
  • the contact strips and contact buffers used in this case are often formed as hollow chamber profiles of a rubber-like or otherwise elastic material.
  • a sensor tube is integrated in the contact buffers, which has longitudinally opposite, electrically conductive and mutually insulated contact surfaces, which are electrically shorted at a locally impressed from the collision force by partially squeezing the sensor tube and generate a signal in this way.
  • a gas-filled cavity is arranged in the vehicle or at the pinch edge and is deformed in the event of a collision event.
  • it is known to increase the pressure in the cavity (DE 1 944 289 A, DE 43 22 488 A1, DE 195 04 353 A1), the air flow emanating from the deformed cavity (DE 102 44 730 A1, DE 102 44 732 A1) or the temperature rise (DE 100 57 258 C1, DE 101 03 047 C1) and trigger a signal when certain limit values are exceeded.
  • the signal in turn activates a safety system, in a vehicle such as an airbag, a belt tensioner, a roll bar, a pedestrian protection device and the like. More.
  • a sound event occurring during the collision is detected and evaluated.
  • a device for triggering a safety device is known.
  • structure-borne sound sensors such as microphones, mounted on a motor vehicle.
  • the structure-borne sound sensors generate an electrical structure-borne sound signal in the event of a collision of the motor vehicle.
  • This signal is fed to a spectrum analyzer which generates an acoustic power spectrum from the structure-borne sound signal.
  • the output of the spectrum analyzer controls a tripping unit for an occupant safety device.
  • US 4 346 914 A discloses a collision sensor device in which an acoustic waveguide is looped along the vehicle support structure and welded thereto at certain points. At the free ends of the waveguide are piezoelectric sensors, which also operate in the range between 100 kHz and 1 MHz. In the event of a collision of the vehicle, an acoustic wave in the waveguide is excited via the welding points and accordingly a corresponding signal is generated in the sensors. A deformation of the waveguide is not provided in this device.
  • EP 0 445 907 A2 describes a collision sensor device for motor vehicles.
  • an acoustic waveguide is also arranged in the vehicle, but acoustically isolated from its support structure.
  • the waveguide is deformed.
  • the deformation excites an acoustic wave in the waveguide and this wave is in turn detected by sensors.
  • the sensor signals are supplied to a processor, which generates a trigger signal for an occupant safety device from the sensor signals if certain limit values have been exceeded.
  • the acoustic decoupling of the waveguide from the vehicle structure ensures that only collision events are detected in which a deformation of the waveguide occurs.
  • DE 100 34 524 A1 discloses a method for detecting an accidental deformation of a component of a motor vehicle.
  • a component of the motor vehicle is repeatedly excited with a defined frequency pulse and analyzes the structure-borne noise spectrum resulting from the excitation.
  • an impact sensor in which a deformation of a fastening screw of a bumper is detected by means of ultrasound.
  • the screw is provided with an ultrasonic transmitter and an ultrasonic receiver.
  • the ultrasonic signal propagates from the transmitter in the longitudinal direction of the screw, is reflected at the end and runs back to the receiver.
  • the transit time of the ultrasound signal changes, which can thus be evaluated as a criterion for the occurrence of a collision.
  • a piezoelectric crystal sound transmitter couples ultrasonic signals with a frequency of more than 10 kHz into a deformable cylindrical cavity of 1.50 m in length such that in the cavity creates a standing wave.
  • the sound transmitter is mounted on one end face and a sound receiver on the opposite end side. In a collision of the vehicle, the cavity is deformed and thus changes from the sound receiver received signal. To verify whether a collision has actually taken place, the sound transmitter can again emit a test pulse and the signal received by the sound receiver is then evaluated.
  • This known collision sensor has the disadvantage that a standing wave in the cavity is difficult to maintain, if at a length of the cavity of 1.50 m, the wavelength at 10 kHz is only 3.3 cm, ie 45 periods of the sound signal in the waveguide stand. Then, for the coupling of the sound signal of the sound transmitter as well as for the decoupling of the sound signal at the sound receiver important position of the nodes or Schwingungsbäuche changes even with the least change in the resonant frequency of the cavity, especially due to temperature change, so strong that in terms of quality For example, between 100 and 1000, a signal drop occurs in the cavity that could be misinterpreted as a collision.
  • the above-described collision sensors are all limited to detecting a collision event. They thus require a collision sensor, which is in perfect condition immediately before the collision.
  • a permanent narrowing of the cavity cross-section caused by external force or a complete local clamping of a cavity area can cause the air displacement to be detected beyond the bottleneck not to be forwarded to the sensor element which detects the pressure increase or the air flow. This is the case when the deformation caused by the collision takes place beyond the bottleneck in a volume portion of the cavity facing away from the sensor element.
  • the device has a waveguide into which a microwave signal of 2.4-2.5 or 5.72-5.875 GHz is coupled by means of a transmitter.
  • the device measures the transit time of the microwave signal between the transmitter and a receiver located at the opposite or the same end of the waveguide. If the waveguide is not deformed, results in a predetermined duration. If the waveguide is deformed by an impact, the transit time changes, and this transit time change is detected as an impact.
  • the known device also allows a functional test by comparing the measured transit time before or during operation of the device with stored data.
  • the known device thus has the disadvantage that a complex microwave apparatus is needed. Further, the transit time measurement is a relatively inaccurate measurement method because the travel time of a wave in an elongated waveguide is significantly more affected by changes in length than in the cross-sectional shape.
  • the collision sensors described so far also have the inherent disadvantage that the sound characteristic is firmly impressed by the mechanical Inrien entered and must be adapted to the particular application by re-design of the hollow chamber profile always new. That leads to an undesirable because costly variant variety.
  • Canted installations of the collision sensors are also only possible to a limited extent and in the case of very large radii of curvature, so that a frictional adaptation of the collision sensors to the objects to be monitored often succeeds only by embossing a plurality of collision sensors and consequently leads to increased assembly costs.
  • the invention is therefore the object of developing a collision sensor of the type mentioned in such a way that the above-mentioned disadvantages are avoided.
  • the sensor according to the invention should be inexpensive to manufacture and easy to assemble, preferably an immediate detection of the described incidents, in particular a deformation (clamping or constriction) or a leak (hole or crack) of the cavity should be possible.
  • this detection is to be performed independently of which physical principle (air pressure, air flow, temperature, sound, etc.) the collision-induced deformation of the cavity is detected.
  • thermoacoustic actuator generates the sound waves using the thermoacoustic effect and preferably emits sound waves in the frequency range between 5 and 500 Hz.
  • the present invention thus utilizes the so-called thermoacoustic or thermo-pneumatic effect for generating sound in a sensory cavity resonator.
  • the sound is, for example, coupled via a driven with a pulsed or alternating electric current heating element directly into the cavity and the heating element immediately surrounding air due to the inhomogeneous and transient temperature distribution in the vicinity of the heating element by means of induced pressure fluctuations in the air to form sound waves excited ,
  • thermoacoustic effect as such has been known for a long time, the first investigations on a heating flame date back to the year 1777; See review article by M. Altenbokum: "The phenomenon of thermoacoustics” in KI Refrigeration Air Conditioning Technology, May 2007, pages 24 to 26.
  • thermoacoustic effect succeeded in 1880 by means of a thin heating wire, to which a large-area membrane was coupled; See M. Preece, "On Some Thermal Effects of Electric Currents," Proceedings of the Royal Society of London, May 27, 1880.
  • a sounding membrane is not required.
  • the switching point can be set electronically in the downstream evaluation unit and thus u.U. be easily and individually adapted to different operating conditions by means of preselection functions.
  • the collision sensor can be integrated into existing contact buffers - even with shared use of the existing cavity - with little effort, so that therefore the compulsion to variant variety is significantly reduced and often completely eliminated.
  • the new collision sensor is thus inexpensive to manufacture and easy to assemble.
  • the new sensor also supplies a so-called life-zero signal and can be used to record the temporal impact curve, as it not only provides a pure switching function. It thus makes it possible to detect and discriminate against harmless or undesired events, so that false tripping is avoided.
  • the cavity is bent or cranked when used in a contact strip, this leaves the impressed sound signal largely unimpaired.
  • the complete collision sensor system consisting of sensor element, actuator, cavity and evaluation unit can be completely monitored for functionality by self-test, which significantly increases operational reliability and reliability.
  • the object underlying the invention is therefore achieved in that a preferably standing sound wave is coupled into the cavity via a thermoacoustically acting actuator, and that the propagating in the cavity sound event is detected and compared with a predetermined setpoint , wherein preferably the sound wave with a frequency in the range between 5 and 500 Hz coupled into the cavity and / or the sound wave is coupled at predetermined operating conditions of an object to be monitored, in particular a motor vehicle for a predetermined period of time in the cavity.
  • the invention also makes it possible to have a collision sensor in or on an object to be monitored, in particular in a motor vehicle, with respect to its object
  • a collision sensor in or on an object to be monitored, in particular in a motor vehicle, with respect to its object
  • To monitor operability in particular to automatically monitor the entire measuring chain, consisting of cavity and sensor element, so that a fault of the type described above is displayed immediately and can be rectified immediately.
  • the verification of the functionality is on the one hand only for a short time, and preferably only made when a collision detection is not required.
  • the use of a very low frequency has the advantage that the coupling and decoupling of the sound wave into and out of the cavity is not critical with respect to fluctuations of the ambient temperature.
  • the sensor element is further designed to receive a collision signal which has been generated by a collision event acting on the collision sensor in the cavity.
  • This measure has the advantage that when a sound signal is evaluated for detecting the collision event, the sensor element and the evaluation unit are used not only in the manner described for monitoring the function of the collision sensor. Rather, the sensor element then also serves for the actual function, namely the detection of a collision event. This double function of the sensor element and the evaluation unit reduces the required installation space, for example, in the motor vehicle as well as the production costs.
  • the cavity is filled with a fluid, in particular with air, and the sensor element and / or the further sensor element detects a physical parameter from the group: fluid pressure, fluid flow, fluid temperature.
  • thermal flow sensor element particularly preferred is the use of a thermal flow sensor element, because this has an optimal sensitivity for the present application.
  • the acoustic actuator couples a periodic sound wave of fixed frequency into the cavity.
  • This measure has the advantage that the continuous wave excitation generates a stable sound wave in the cavity, which results in an equally stable signal of the sensor element. This is especially true when the frequency corresponds to the resonant frequency of the cavity.
  • the acoustic actuator can also couple a sound wave in the form of a single pressure jump into the cavity.
  • the acoustic actuator can successively couple sound waves of different frequencies into the cavity.
  • This measure has the advantage that a better differentiation of the type of interference is possible with a coupling of sound waves of different frequencies.
  • the acoustic actuator includes a heating element and the heating element is fed from a current source with an adjustable current.
  • This measure has the advantage that an effective acoustic actuator with simple and commercially available elements can be made available, which has a sufficient bandwidth and is able to generate a sound wave without moving elements.
  • the current is a periodically sampled direct current.
  • This measure has the advantage that the sound wave in the cavity can be excited particularly effectively.
  • the direct current is thereby sampled with a duty cycle of 50% and more preferably with a sampling frequency between about 10 and 300 Hz.
  • the direct current may also be sampled once in a stepped manner.
  • the power may also be an alternating current.
  • the heating element is flat, in particular as a carrier membrane with heating conductor tracks structured thereon.
  • This measure has the advantage that the thermal time constant is very small, for example, less than 1 ms, and thereby a correspondingly large temperature modulation is achieved with which effectively a sound wave can be excited in the cavity.
  • a particularly good effect is achieved when the heating element is arranged in a chamber, and the chamber is closed except for an outlet opening.
  • This measure has the advantage that within the chamber, a pulsating pressure is generated, which can be coupled via the outlet particularly well to the cavity.
  • the chamber is elongated, in particular cylindrical, and the heating element is arranged along a longitudinal axis of the chamber.
  • This measure has the advantage that there is a design in which a very high sound pressure is generated in the cavity in a particularly effective manner and thus an intense sound wave can be excited.
  • the heating element has a radial distance from an inner wall of the chamber, wherein the distance is approximately equal to, but not smaller than the thickness of the temperature boundary layer around the heating element around.
  • the outlet opening is arranged in the region of a vibration node of a standing sound wave excited by the acoustic actuator in the cavity.
  • the senor element and the acoustic actuator are arranged in a common housing.
  • This measure has the advantage that a small size is created and that a prefabrication of this module is possible, which facilitates later assembly, for example. In the motor vehicle.
  • the evaluation unit determines the root mean square value of the output signal of the sensor element and compares the root mean square value with a predetermined desired value.
  • the evaluation unit determines the quotient of the peak value and effective value of the output signal of the sensor element and compares the quotient with a predetermined desired value.
  • a sound wave of a first frequency and then a double frequency sound wave are successively coupled into the cavity.
  • the present invention also relates to collision sensors and methods of the type mentioned, in which the new forms of signal evaluation are used.
  • the invention thus relates to a collision sensor in or on an object to be monitored, in particular a motor vehicle, having a deformable cavity, with at least one acoustic sensor element connected to the cavity, with an evaluation unit connected to the sensor element, and with an acoustic actuator connected to the cavity for generating preferably standing sound waves in the cavity, wherein the evaluation unit is designed for evaluating signals which are generated by the sound waves in the sensor element, wherein the collision sensor at predetermined operating states of the object to be monitored with regard to its function monitored, in particular the acoustic Actuator is operable for a predetermined period of time, wherein the acoustic actuator couples a standing sound wave in the cavity (12) and recorded in the cavity propagating sound event and with a predetermined setpoint (RMSo; CRo) verg is determined, and wherein the root mean square (RMS) of the output signal of a sound event sensor element detected and the root mean square (RMS) with the setpoint (RMSo) is compared and / or the quot
  • Another method for checking the function of a collision sensor having a deformable cavity is characterized in that a preferably standing sound wave is coupled into the cavity (12), and that the sound event propagating in the cavity is detected and recorded at a predetermined setpoint value (FIG. RMSo; CRo) and that the root mean square (RMS) of the output signal of a sensor element detecting the sound event determines and the root mean square (RMS) with the setpoint (RMSo) and / or the quotient of peak and rms value (CR) of the output - Determined signal of a sound event detecting sensor element and the quotient (CR) with the setpoint (CR 0 ) is compared.
  • a predetermined setpoint value FOG. RMSo; CRo
  • the predetermined operating state is the actuation of a starter of the motor vehicle.
  • This measure has the advantage that the checking of the functionality of the collision sensor takes place before the start of the journey, that is to say at a time when a collision can not be expected.
  • the predetermined operating state can also be a standstill of the motor vehicle.
  • This measure has the advantage that the review takes place at shorter intervals.
  • the acoustic actuator couple a periodic acoustic wave into the cavity and that the predetermined period of time be shorter than about 20 periods of the acoustic wave.
  • This measure has the advantage that the check is completed in a minimum amount of time. For example, if the acoustic actuator emits sound waves in the frequency range between 5 and 500 Hz, then the duration is only a few milliseconds or seconds.
  • thermoacoustic actuator in the collision sensor according to the invention can be used either only for the self-test or for collision monitoring.
  • the collision sensor may preferably operate in pulsed mode.
  • the sound wave becomes a sound impulse generated directly by the local deformation of the cavity and detected the associated air displacement at the sensor element.
  • the thermoacoustic actuator is then intended only for the self-test.
  • thermoacoustic actuator continuously generates a standing sound wave.
  • a temporary attenuation of the sound intensity corresponding to the time duration of the external force action is detected on the sensor element.
  • the functional test ie the self-test, is then carried out by the life-zero signal of the (still) undeformed cavity generated continuously by the thermoacoustic actuator on the sensor element, by which the functionality and in particular the continuity of the entire measuring path is signaled.
  • Figure 1 is an extremely schematic plan view of an embodiment of a collision sensor according to the invention
  • Figure 2 is a representation, similar to Figure 1, but for a slightly modified embodiment
  • Figure 3 is another illustration, similar to Figure 1, but for another, slightly modified embodiment
  • Figure 4 is a detail of an acoustic actuator, as in the
  • Collision sensor of Figures 1 to 3 can be used;
  • FIG. 5 shows a signal / time diagram for illustrating a continuous wave
  • Figure 6 is a signal / time diagram similar to Figure 5, but illustrating a pulse method
  • FIG. 7 shows a signal / frequency diagram
  • FIG. 10 shows a decision matrix for different signal evaluation methods according to the invention in the case of different incidents.
  • the present invention takes advantage of the fact that in a gas volume with appropriate excitation sound waves can propagate.
  • air in particular in closed cavities, other gases can be used.
  • the properties of the sound waves are determined by the shape and dimensions of the cavity enclosing the air column.
  • the cavity can be in a conventional manner, a separate component or a structural cavity of an object to be monitored, so for example.
  • a vehicle for example, the interior of a door of the vehicle.
  • the cavity is preferably closed, but it may also be partially open, for example open on one side or it may have specifically provided outflow openings.
  • a sound wave is generated in the cavity and detected by means of a sensor element, if the current propagation pattern of the sound wave corresponds to the propagation pattern of the undisturbed cavity, for which purpose special evaluation methods are provided. If the state of the cavity is disturbed, for example by a deformation (clamping, bottleneck) or by a leak (hole, crack), then this invention is individually recognized and displayed.
  • an acoustic pulse is coupled into the air column located in the cavity by means of an acoustic actuator.
  • the actuator is preferably designed as a thermoacoustic actuator, which can also be referred to as a thermo-pneumatic actuator.
  • a sound wave is generated, for which applies:
  • the effective resonance length L changes accordingly.
  • the resonance frequency v n from [3] then also changes.
  • a shift in the resonant frequency thus signals a faulty state. This shift can be detected by means of a sound-sensitive sensor element and detected in an evaluation circuit.
  • the sensor element can be designed as a pressure sensor or as a flow sensor, with thermal flow sensors being preferred. Furthermore, it is preferred if the sensor element also serves as impact sensor element for the actual function of the collision sensor, namely the detection of a collision event.
  • 10 as a whole denotes an exemplary embodiment of a collision sensor according to the invention.
  • the collision sensor 10 has a cavity 12, which in the illustrated example is elongate-cylindrical.
  • the cavity 12 is a resonant structure which is in the frequency range of 5 to 500, preferably of 10 to 300 Hz is resonant.
  • the cavity 12 has a quality which in practice may be between 100 and 1000.
  • a Y-shaped branch with a first sound-conducting channel 18 and a second sound-conducting channel 20 is connected to a right front end 16 in FIG.
  • the first channel 18 leads to a sensor element 22 and supplies an acoustic signal 23 to it.
  • the sensor element 22 serves primarily to monitor the operability of the collision sensor 10 in the manner described in detail below. In addition, however, it can also detect signals which serve to detect a collision event, unless a separate sensor element is provided for this purpose.
  • the second channel 20 leads to an acoustic actuator 24, which can generate and deliver a sound wave 25.
  • An evaluation unit 26 is connected with a line 27 to the sensor element 22 and a line 28 to the actuator 24.
  • An output 29 of the evaluation unit 26 leads to a trip unit, not shown, for a safety system, which contains, for example, airbags, belt tensioners, a roll bar or the like.
  • the sensor element 22, the actuator 24 and the evaluation unit 26 and possibly also the Y-shaped branching can be arranged in a common housing 30, which is shown in FIG.
  • the housing 30 is arranged there at the front end 16.
  • the housing 30 ' may also be connected to a center position 31 of the cavity 12', as shown in FIG.
  • the actuator 24 is connected to a vibration node of the sound wave in the cavity 12, because then there is an optimal coupling.
  • 32 denotes an optional further sensor element, which is likewise connected to the cavity 12.
  • the further sensor element 32 detects a for a collision event characteristic signal. If this function is already performed by the sensor element 22, as described above, no further sensor element 32 is required.
  • the further sensor element can also be arranged elsewhere and work according to any other suitable physical principles of action.
  • perturbations of concern to the state of the cavity 12 are of interest.
  • the cavity 12 In the undisturbed state, the cavity 12 has a predetermined, for example, cylindrical shape.
  • the cavity can now be deformed, as indicated in FIGS. 1 and 34 and 36.
  • This may be a bulge or a clamping defect 34, in which the cavity 12 is narrowed over a substantial part of its cross section, as indicated in FIG.
  • Another disturbance is formed by a leak, which is indicated in Figure 1 as a hole defect 36, but which may also be a crack or a porous spot.
  • FIG. 4 shows details of the acoustic actuator 24.
  • the actuator 24 has a housing 40 in which a chamber 42 is located.
  • the housing 40 and the chamber 42 are closed except for a common outlet opening 43.
  • the chamber 42 is at least approximately cylindrical in the illustrated embodiment.
  • the heating element 46 is for example a filament in which a thin hot wire, such as a platinum wire of 20 microns in diameter, meandered or stretched in a plane or as Spiral is arranged around a longitudinal axis.
  • a so-called hotplate This consists of a flat membrane chip made of silicon with a corresponding heating structure.
  • Such filament heating elements have a very short response time and are operable in a wide frequency range.
  • heating elements are used as thermal-pneumatic or thermoacoustic See actuators used instead of conventional mechanical acoustic actuators, such as piezoelectric elements, which are usually only at a fixed frequency and in a much higher frequency range, in particular in the ultrasonic range, operable.
  • the heating element 46 is connected directly or inductively to a current source 50, to which a heating voltage UH is supplied via a first input 52 and a control voltage Uc via a second input 54.
  • the power supplied by the power source 50 to the heating element 46 may be an alternating current.
  • a sampled DC i. a rectangular time profile, in which by means of the control voltage Uc of the heating current with a duty cycle of 50% and a sampling frequency in the range between about 5 to 500 Hz, preferably from about 10 and 300 Hz, is adjustable.
  • the current supplied to the heating element 46 then also has a rectangular time profile, which switches between the value 0 and a predetermined current value.
  • the thickness of the so-called temperature boundary layer is designated.
  • the thickness of the temperature boundary layer is to be understood as meaning the distance from the heating element 46 at which the temperature has dropped to 1/100 times the amount in static ambient air.
  • the distance of the Wien to the inner wall of the chamber 42 is preferably about a. For a thermal crosstalk and associated heat losses in the wall of the chamber 42 are avoided. Due to the sampled heat generation, the air expands in the interior 44 of the chamber 42 periodically and also keyed. The air blasts are blown through the outlet opening 43 to the outside in the cavity 12, whereby in the cavity 12 a vibration of the air column therein and at a suitable sampling frequency a standing sound wave is excited.
  • the air surges are coupled into the cavity 12 as a continuous wave signal of constant frequency, preferably at the resonant frequency of the cavity 12.
  • the sound signal S detected by the sensor element 22 has a profile 62 shown in FIG. 5 in a first diagram 60 as a function of the time t.
  • the sound signal detected by the sensor element 22 has the profile 68 shown in a second diagram 66 in FIG. 6, which shows echoes decaying in the sound amplitude.
  • the envelope of the echoes reflects the quality of the cavity 12 and the distance of the echoes the resonance frequency again.
  • the sensor element 22 then generates a signal S with the frequency vi and maximum amplitude. This signal S then indicates that the cavity 12 is unchanged and the function of the collision sensor 10 is not impaired.
  • This form of monitoring can be carried out continuously or at predetermined time monitoring intervals.
  • the fundamental frequency vi of the cavity 12 is changed, for example by a clamping defect 34 and / or a hole defect 36, then the frequency vi of the air pulses no longer corresponds to the fundamental vibration of the changed cavity 12.
  • the signal S of the sensor element 22 changes then. The greater the quality, i. the edge steepness of the transmission curve of the cavity 12, the greater the signal change.
  • the frequency change is the measure of an existing fault.
  • the acoustic actuator 24 is driven at a fixed frequency in the preferred continuous wave mode, then frequency selective signal processing per se is not required. If, on the other hand, the actuator 24 is operated with a jump function, then it is expedient to connect a narrow bandpass filter downstream of the sensor element 22, in which the frequency vi lies in the passband, preferably in its middle.
  • FIG. 7 shows a third diagram 70 with a profile 72 of the signal S at the sensor element 22 as a function of the excitation frequency v of the sound waves 25 for an exemplary embodiment of a cavity 12 with an acoustic length of 150 cm.
  • the curve 72 shows a first maximum 74 at the fundamental frequency vi of approximately 100 Hz and a second maximum 76 at the second harmonic vz of approximately 200 Hz.
  • the signal S is determined as the root mean square RMS over several oscillation periods.
  • FIG. 8 shows a fourth diagram 80 for different axial positions of a clamping defect 34 in a 150 cm long cavity 12.
  • the diagram 80 contains a first profile 82, which represents the RMS value of the signal S as a function of the distance z.
  • the associated limit value RSo is indicated at 84.
  • a second curve 86 represents the so-called crest value CR. This is understood in the specialist world to be the quotient of the peak value and the effective value of the signal S.
  • the associated limit value CRo is indicated at 88.
  • the RMS value 82 can reach the setpoint value 84 and even exceed it, so that a clear diagnosis is not possible here.
  • the RMS value 82 is equal to the desired value 84, because the cavity 12 is closed there anyway. Therefore, with the exception of the initial range, a clamping defect 34 can be detected by the fact that the RMS value 82 of the signal S lies below the limit value RMSo indicated at 84.
  • the second criterion is the CR value 86.
  • the second course 86 shows that a clamping defect 34 over the entire length z of the cavity 12 results in the CR value 86 being above the limit value CRo indicated at 88.
  • FIG. 9 shows in a similar form to FIG. 8 a fifth diagram 90 in the case of a hole defect 36.
  • a first curve 92 again represents the RMS value and 94 its limit value RMSo.
  • a second curve 96 shows the CR value and 98 its limit value CRo.
  • a hole defect 36 is detected when the RMS value 94 is below the threshold 94. Only in the middle of the cavity 12 a clear diagnosis is not possible because there the RMS value 94 exceeds the limit 96 in some cases significantly. A similar problem arises for the CR value 96, which is only outside the center of the cavity 12 well above the limit value 98, but in the middle can assume the magnitude of the limit value.
  • a third criterion must be considered, namely the second harmonic V2 (see FIG.
  • a hole defect 36 at half the length of the cavity 12 corresponds to a unilaterally open resonator.
  • only odd-numbered harmonics (v 3 , vs, V7]. In the sense of equation [2] can form. Therefore, if one excites the cavity 12 with the second harmonic V2 and there is no increased signal S in terms of the maximum 76 of Figure 7, then there is a hole defect 36.
  • FIG. 10 again shows the criteria for the cases “no disturbance”, “clamping defect” and “hole defect” in the form of a decision matrix.
  • the checking of the collision sensor 10 is expediently carried out outside normal operation, because otherwise the sound waves 25 generated by the actuator 24 could interfere with the detection of a collision event. According to the invention, therefore, the check is made when starting the vehicle, possibly alternatively or additionally, when the vehicle is stationary or in the rest periods of the monitored object.
  • the verification process can be very fast.
  • continuous wave operation in the sense used above, it is to be understood that the actuator 24 emits the sound wave 25 only for a very limited number of periods, for example for less than 50, preferably less than 20 periods.
  • thermoacoustic actuator 24 is then used only for the functional test.
  • thermoacoustic actuator 24 is operated continuously, so that in the event of an external force, a change in the signal permanently generated at the sensor element 22 is detected.
  • the signal evaluation for the self-test described above can also be used advantageously when no thermoacoustic but an acoustic actuator is used, which is based on a different physical principle.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

L'invention concerne un détecteur de collision à déformation (10) comportant une cavité déformable (12), au moins un élément de détection acoustique (22) connecté à la cavité (12), une unité d'évaluation (26) connectée à l'élément de détection (22), et un actionneur thermoacoustique (24) connecté à la cavité (12), destiné à introduire des ondes sonores de préférence stationnaires (25) dans la cavité (12). L'unité d'évaluation (26) est conçue pour évaluer des signaux (23) produits par les ondes sonores (25) dans l'élément de détection (22). L'actionneur acoustique (24) émet de préférence des ondes sonores (25) dans la gamme de fréquence de 5 à 500 Hz.
PCT/EP2009/000284 2008-01-29 2009-01-17 Détecteur de collision à déformation et procédé de contrôle de son fonctionnement Ceased WO2009095165A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP09706095A EP2247471A2 (fr) 2008-01-29 2009-01-17 Détecteur de collision à déformation et procédé de contrôle de son fonctionnement

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008008082.9 2008-01-29
DE200810008082 DE102008008082B4 (de) 2008-01-29 2008-01-29 Deformations-Kollisionssensor und Verfahren zur Überprüfung von dessen Funktion

Publications (2)

Publication Number Publication Date
WO2009095165A2 true WO2009095165A2 (fr) 2009-08-06
WO2009095165A3 WO2009095165A3 (fr) 2009-10-15

Family

ID=40622149

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2009/000284 Ceased WO2009095165A2 (fr) 2008-01-29 2009-01-17 Détecteur de collision à déformation et procédé de contrôle de son fonctionnement

Country Status (3)

Country Link
EP (1) EP2247471A2 (fr)
DE (1) DE102008008082B4 (fr)
WO (1) WO2009095165A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112092763A (zh) * 2019-06-17 2020-12-18 北汽福田汽车股份有限公司 碰撞检测系统、方法和车辆

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011014251A1 (de) * 2011-03-17 2012-09-20 Continental Automotive Gmbh Verfahren zur Aufpralldetektion mittels eines Drucksensors sowie Aufpralldetektorsystem
DE102012101859A1 (de) * 2012-03-06 2013-09-12 Continental Automotive Gmbh Drucksensor für ein Aufprallsensorsystem
DE102012101856B4 (de) * 2012-03-06 2021-06-24 Continental Automotive Gmbh Verfahren zur Funktionsprüfung eines Aufprallsensorsystems bestehend aus einem Hohlraum und Drucksensoren
DE102013215330A1 (de) * 2013-08-05 2015-02-05 Continental Automotive Gmbh Aufprallsensor für ein Kraftfahrzeug mit einem elastischen Hohlkörper und einem Drucksensor sowie einer Testdruckerzeugungseinrichtung

Family Cites Families (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1944289A1 (de) * 1969-09-01 1971-03-11 Herzer Fa Kurt Unfalldetektor,besonders fuer Kraftfahrzeuge
US4346914A (en) * 1980-12-17 1982-08-31 General Motors Corporation Acoustic emission automotive crash sensor
DE3729019A1 (de) * 1987-08-31 1989-03-16 Messerschmitt Boelkow Blohm Einrichtung zur ausloesung einer sicherheitsvorrichtung
US4842301A (en) * 1988-09-02 1989-06-27 General Motors Corporation Acoustic emission automotive crash sensor
GB9004916D0 (en) * 1990-03-05 1990-05-02 Stresswave Tech A collision detector for a vehicle
DE9215382U1 (de) * 1992-11-11 1994-03-17 Siemens AG, 80333 München In einem Fahrzeug angebrachter Schalldetektor
JPH07242153A (ja) * 1994-03-04 1995-09-19 Tokai Rika Co Ltd クラッシュセンサ
DE10034524B4 (de) * 2000-07-15 2017-08-10 Volkswagen Ag Verfahren und Vorrichtung zur Erkennung einer unfallbedingten Verformung mindestens eines Bauteils eines Kraftfahrzeugs
DE10057258C1 (de) * 2000-11-18 2002-03-07 Bosch Gmbh Robert Vorrichtung und Verfahren zur Seitenaufprallerkennung
DE10103047C1 (de) * 2001-01-24 2002-07-25 Bosch Gmbh Robert Vorrichtung zur Seitenaufprallsensierung in einem Fahrzeug
DE10244730A1 (de) * 2002-09-25 2004-04-01 Bayerische Motoren Werke Ag Vorrichtung und Verfahren zur Seitenaufprallerkennung bei einem Fahrzeug
DE10244732A1 (de) * 2002-09-25 2004-04-01 Bayerische Motoren Werke Ag Vorrichtung und Verfahren zur Personenaufprallerkennung bei einem Fahrzeug
DE10259527A1 (de) * 2002-12-19 2004-07-01 Robert Bosch Gmbh Aufprallsensor
DE102004003199A1 (de) * 2004-01-22 2005-08-11 Robert Bosch Gmbh Vorrichtung zur Aufpralldetektion
DE102004034877A1 (de) * 2004-07-19 2006-02-16 Siemens Ag Anprallsensor
US7331415B2 (en) * 2005-09-28 2008-02-19 Delphi Technologies, Inc. Pedestrian impact sensing apparatus for a vehicle bumper
DE102006051295B4 (de) * 2006-10-13 2009-02-05 Gebr. Schmidt Fabrik für Feinmechanik GmbH & Co. KG Sensorelement für einen Kollisionssensor
JP4513833B2 (ja) * 2007-07-17 2010-07-28 株式会社デンソー 車両用衝突検知装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112092763A (zh) * 2019-06-17 2020-12-18 北汽福田汽车股份有限公司 碰撞检测系统、方法和车辆

Also Published As

Publication number Publication date
DE102008008082B4 (de) 2009-12-10
WO2009095165A3 (fr) 2009-10-15
DE102008008082A1 (de) 2009-08-13
EP2247471A2 (fr) 2010-11-10

Similar Documents

Publication Publication Date Title
DE4209140C2 (de) Aufprallerfassungseinrichtung für Gaskissensysteme
DE10164760B4 (de) Ultraschallhindernisdetektor
DE60038383T2 (de) Magnetischer sensor
DE102011007881B4 (de) Diagnose eines Personenschutzsystems
EP1019271A1 (fr) Dispositif pour la protection des occupants dans un vehicule automobile
EP2247471A2 (fr) Détecteur de collision à déformation et procédé de contrôle de son fonctionnement
WO1999019175A1 (fr) Detecteur d'accident constitue d'une partie deformable d'un vehicule
DE102009040365A1 (de) Kollisionsdetektionsvorrichtung für ein Fahrzeug
DE102010021960A1 (de) Verrfahren zum Erkennen eines blockierten Zustands eines Ultraschallsensors eines Kraftfahrzeugs, Fahrerassistenzeinrichtung und Kraftfahrzeug
DE10034524B4 (de) Verfahren und Vorrichtung zur Erkennung einer unfallbedingten Verformung mindestens eines Bauteils eines Kraftfahrzeugs
DE102012221591A1 (de) Verfahren und Vorrichtung zur Umfelderfassung eines Fahrzeugs
DE112005001509B4 (de) Anprallsensor
DE4226543A1 (de) Verfahren zur Bewertung von Echosignalen in Sicherungssystemen für Innenräume
EP1710598B1 (fr) Appareil de détection de la collision d'un véhicule avec un piéton
EP2294456B1 (fr) Dispositif et procédé de surveillance de zones par ultrasons
DE102008002549A1 (de) Sensorik zur Ermittlung einer Aufprallgeschwindigkeit für ein Fahrzeug und Verfahren zur Ermittlung einer Aufprallgeschwindigkeit für ein Fahrzeug
DE102020114636A1 (de) Integrierter Sensor zur Erfassung eines minimalen Grenzstandes und eines Füllstandes, Anordnung eines solchen Sensors an einem Behälter und Verfahren zum Betreiben eines solchen Sensors
EP1904344B1 (fr) Dispositif de detection d'un choc en cas de collision d'un vehicule avec un pieton
DE102004049380B4 (de) Fahrzeugsensor
WO2019034626A1 (fr) Procédé pour faire fonctionner un capteur ultrasonique monté de manière dissimulée derrière un élément structural d'un véhicule automobile avec interprétation des fréquences d'un signal de réception, dispositif à capteur ultrasonique, arrangement d'habillage ainsi que véhicule automobile
WO1992006455A1 (fr) Procede pour la surveillance des vitres d'un espace interieur
DE4244901C2 (de) Aufprallerfassungseinrichtung für Gaskissensysteme
DE102006054095A1 (de) Ultraschallsensor sowie Verfahren zum Betrieb eines Ultraschallsensors
EP1827913A1 (fr) Procede d'amorçage d'un systeme de securite dans un vehicule
DE102005030135A1 (de) Schallwellendetektor und Verfahren zum Aufnehmen einer Welle

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09706095

Country of ref document: EP

Kind code of ref document: A2

NENP Non-entry into the national phase

Ref country code: DE

WWE Wipo information: entry into national phase

Ref document number: 2009706095

Country of ref document: EP