EP1530520A2 - Device for determining the acceleration of the wheel of a vehicle - Google Patents

Device for determining the acceleration of the wheel of a vehicle

Info

Publication number
EP1530520A2
EP1530520A2 EP03729969A EP03729969A EP1530520A2 EP 1530520 A2 EP1530520 A2 EP 1530520A2 EP 03729969 A EP03729969 A EP 03729969A EP 03729969 A EP03729969 A EP 03729969A EP 1530520 A2 EP1530520 A2 EP 1530520A2
Authority
EP
European Patent Office
Prior art keywords
component
saw
acceleration
wheel
surface wave
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.)
Withdrawn
Application number
EP03729969A
Other languages
German (de)
French (fr)
Inventor
Christian Mayer
Andreas Schwarzhaupt
Gernot Spiegelberg
Armin Sulzmann
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.)
Mercedes Benz Group AG
Original Assignee
DaimlerChrysler AG
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 DaimlerChrysler AG filed Critical DaimlerChrysler AG
Publication of EP1530520A2 publication Critical patent/EP1530520A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/171—Detecting parameters used in the regulation; Measuring values used in the regulation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
    • B60C23/02—Signalling devices actuated by tyre pressure
    • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
    • B60C23/02—Signalling devices actuated by tyre pressure
    • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
    • B60C23/0422—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver characterised by the type of signal transmission means
    • B60C23/0433—Radio signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/0888—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values for indicating angular acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/097—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements
    • G01P15/0975—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements by acoustic surface wave resonators or delay lines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed

Definitions

  • the invention relates to a device for determining the acceleration of a vehicle wheel with an acceleration information arranged in the vehicle wheel as a radio signal that transmits a radio sensor to a receiver.
  • the speed measurement is usually carried out by considering and evaluating the frequency of rotation of one or more vehicle wheels.
  • the average length of the vehicle wheels is used to determine the distance covered per unit of time.
  • a device for detecting speeds of a rotor with a speed sensor which transmits its speed information wirelessly to an electrical control device.
  • inductive speed signals are generated, the time intervals of which are proportional to the wheel speed.
  • the speed sensor has a passive radio sensor, the radio signals of which inductively generated radio signals are sent at time intervals proportional to the wheel speed to a receiver of the control device, the radio signals having codes assigned to the respective wheels.
  • the radio sensor has a delay line designed as a surface wave (SAW) component.
  • SAW surface wave
  • SAW component fed pulses are converted by an interdigital transducer into mechanical waves propagating on the surface of a piezoelectric crystal of the component.
  • partially reflecting electrode structures are introduced as reflectors in a characteristic sequence in accordance with the coding to be transmitted. These partially reflecting structures form several pulses from the single excitation pulse, which are reflected back to the interdigital transducer. There they are converted into electromagnetic waves and emitted as a radio signal.
  • the invention is based on the object of providing a device for determining the acceleration of a vehicle wheel, wherein a complex sensor system for determining the wheel speed and the acceleration of the vehicle wheel to be calculated therefrom should be dispensed with.
  • the object is achieved by a device for determining the acceleration of a vehicle wheel with an acceleration information arranged in the vehicle wheel as a radio signal, which transmits a radio signal to a receiver, which has a surface wave (SAW) component with at least one mass m attached to it in such a way that vehicle acceleration a change in length of the Surface wave (SAW) component causes, which can be detected as a change in transit time of mechanical waves, the change in transit time is passed on to the receiver as acceleration information.
  • SAW surface wave
  • the force F acting on the mass m during vehicle acceleration causes a change in the length of the surface wave (SAW) component in the direction or opposite direction of the attached mass m. Depending on the direction of the change in length, this involves an expansion or compression (compression) of the surface wave (SAW) component.
  • SAW surface wave
  • the radio sensor designed as a surface wave sensor functions in such a way that an expansion or compression of the surface wave (SAW) component also stretches or compresses a signal that is sent and reflected by the component in proportion to the change in length of the component.
  • Elongation and compression of the signal is understood here to mean the change in transit time of a mechanical shaft due to the change in the path length which the mechanical shaft has to travel.
  • the measured changes in the running time of the mechanical waves in the surface waves (SAW) component which are proportional to the change in length of the component, can therefore be used to calculate the force F acting on the mass m during vehicle acceleration and thus the acceleration of the vehicle wheel.
  • SAW surface waves
  • the acceleration signal of the individual vehicle wheel can be used by the ABS system to easily determine the vehicle wheel acceleration, the vehicle wheel speed and the vehicle wheel position.
  • the elaborate ABS sensor system which determines the wheel speed and uses it to calculate an acceleration value, can be omitted.
  • the mass m and the surface wave (SAW) component are preferably arranged one after the other in the circumferential direction of the vehicle wheel. There are two versions.
  • the mass m can be arranged in the direction of rotation of the vehicle wheel before or after the surface acoustic wave (SAW) component.
  • the mass m and the surface wave (SAW) component can be arranged one after the other in the radial direction to the wheel axis.
  • the mass m can be arranged in the radial direction both before and after the surface acoustic wave (SAW) component.
  • the centrifugal force ensures the change in length of the surface wave (SAW) component during the acceleration phase and can be used to calculate the radial acceleration of the vehicle wheel.
  • FIG. 1 and 2 each show a device for determining the acceleration of a vehicle wheel with a vehicle wheel and a radio sensor arranged in it in a schematic representation and different arrangement.
  • the device illustrated in FIG. 1 for determining the acceleration of a vehicle wheel 2 comprises a radio sensor 6 arranged in the vehicle wheel 2 and containing a surface wave (SAW) component 4.
  • a mass m 8 is on the surface wave (SAW) component 4 of the radio sensor 6 attached that surface waves (SAW) component 4 and mass m 8 are arranged in the tangential direction or circumferential direction to the vehicle wheel 2.
  • SAW surface wave
  • the mass m 8 is arranged in the direction of rotation 10 in front of the surface component (SAW) 4.
  • the order regarding the direction of rotation 10 is not important.
  • a change in length of the surface wave (SAW) component 4 is caused.
  • compression of the surface waves (SAW) component 4 is achieved due to the inertia of the mass m 8.
  • the compression that is the corresponding change in length, is a measure of the force acting on the mass 8 during the acceleration of the vehicle and is passed on as acceleration information to a receiver of a control device, not shown, which is arranged centrally in the vehicle and is not shown.
  • the mechanical waves generated in the surface wave (SAW) component 4 by an interdigital transducer become partially reflecting in the beam path of these mechanical surface waves in a characteristic sequence
  • the electrode structures 12 can be designed, for example, as metal strips. Also a use of the surface wave (SAW) component 4 without electrode structures is possible because the surface waves are also reflected on the end faces of the surface wave (SAW) component 4.
  • a stretching or compression of the surface wave (SAW) component 4 which corresponds to an acceleration of the vehicle in different directions, has the effect that the mechanical signals which are sent and reflected by the surface wave (SAW) component 4 in relation to the length of time of the acceleration process are proportional to the change in length of the surface wave (SAW) component 4 also stretched or compressed.
  • SAW surface wave
  • the force F which acts on the mass m during the vehicle acceleration and thus the acceleration of the vehicle wheel can thus be calculated via the measured changes in the running time of the mechanical waves in the surface wave (SAW) component 4.
  • SAW surface wave
  • the mass m 8 is chosen so large that there is a change in the length of the surface wave (SAW) component 4 in the acceleration range to be expected for the motor vehicle, which enables a simple evaluation of the travel time differences of the mechanical waves.
  • SAW surface wave
  • the device for determining the acceleration of a vehicle wheel 2 according to FIG. 2 has a radio sensor 4 with the technical features corresponding to the statements relating to FIG. 1.
  • the mass m 8 and the surface wave (SAW) component 4 are arranged one after the other in the radial direction to the wheel axis 14. It is possible that the mass m 8 is attached to the surface wave (SAW) component 4 on the side facing the wheel axis 14 and on the side facing away from the wheel axis 14.
  • the centrifugal force ensures the change in length of the surface wave (SAW) component 4 during the acceleration phase and can be used to calculate the radial acceleration of the vehicle wheel 2.
  • the radio sensor 6 can be integrated in the tire or in the rim of the vehicle wheel 2. This applies to all versions of the radio sensor 6.
  • the change in length of the surface wave (SAW) component can be measured in two directions that are orthogonal to one another. Due to the orthogonal material structure of the surface wave (SAW) component 4, surface waves can run perpendicular to one another through the surface wave (SAW) component 4 without influencing one another. This enables at least two measurement variables, such as wheel speed, tire pressure or acceleration, to be measured simultaneously.
  • the wheel acceleration can be determined redundantly.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Measuring Fluid Pressure (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

The invention relates to a device for determining the acceleration of the wheel of a vehicle (2), comprising a radio sensor (6) which is arranged in the wheel of a vehicle, (2) transmitting the acceleration information as a radio signal to a receiver. The radio sensor (6) consists of a surface wave (OFW) component (4) with at least one material m (8) fixed thereto such that acceleration of the vehicle causes the length of the surface wave (OFW) component (4) to be modified, which can be detected as a modification in the propagation time of mechanical waves. The propagation time modification is transmitted to the receiver as acceleration information. Said measures make it possible to dispense with a complex sensor system for the determination of wheel speed.

Description

Vorrichtung zur Ermittlung der Beschleunigung eines Device for determining the acceleration of a
Fahrzeugradesvehicle wheel
Die Erfindung bezieht sich auf eine Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades mit einem im Fahrzeugrad angeordneten seine Beschleunigungsinformation als Funksignal an einen Empfänger weitergebenden Funksensor.The invention relates to a device for determining the acceleration of a vehicle wheel with an acceleration information arranged in the vehicle wheel as a radio signal that transmits a radio sensor to a receiver.
Eine exakte Geschwindigkeitsbestimmung für Fahrzeuge ist von genereller Bedeutung. Die Geschwindigkeitsmessung erfolgt üblicherweise durch Betrachtung und Auswertung der Umdrehungsfrequenz einer oder mehrerer Fahrzeugräder. Über den durchschnittlichen Umfang der Fahrzeugräder wird auf die pro Zeiteinheit zurückgelegte Weglänge geschlossen.An exact speed determination for vehicles is of general importance. The speed measurement is usually carried out by considering and evaluating the frequency of rotation of one or more vehicle wheels. The average length of the vehicle wheels is used to determine the distance covered per unit of time.
Aus der nachveröffentlichten deutschen Patentanmeldung 101 31 205.9 ist eine Vorrichtung zum Erfassen von Drehzahlen eines Rotors mit einem Drehzahlfühler bekannt, der seine DrehzahlInformation drahtlos an eine elektrische Steuereinrichtung abgibt. Während der Drehung werden induktive Drehzahlsignale erzeugt, deren zeitliche Abstände der Raddrehzahl proportional sind. Der Drehzahlfühler weist einen passiven Funksensor auf, dessen induktiv erzeugte Funksignale in der Raddrehzahl proportionalen Zeitabständen an einen Empfänger der Steuereinrichtung gesendet werden, wobei die Funksignale den jeweiligen Rädern zugeordnete Codierungen aufweisen.From the post-published German patent application 101 31 205.9 a device for detecting speeds of a rotor with a speed sensor is known, which transmits its speed information wirelessly to an electrical control device. During rotation, inductive speed signals are generated, the time intervals of which are proportional to the wheel speed. The speed sensor has a passive radio sensor, the radio signals of which inductively generated radio signals are sent at time intervals proportional to the wheel speed to a receiver of the control device, the radio signals having codes assigned to the respective wheels.
In der DE 100 10 846 AI sind drahtlos abfragbare, passive Sensormodule beschrieben, welche ein Oberflächenwellenelement enthalten. Hinsichtlich der technischen Grundlagen zu Oberflächenwellenelementen wird auf diese Schrift verwiesen. Zur Erzeugung der Funksignale werden mehrere Magnetpole und der Funksensor mit einer der Raddrehzahl proportionalen Geschwindigkeit relativ zueinander bewegt. Die Magnetpole sind auf einem Polrad in gleichen Winkelabständen voneinander angeordnet . Beim Vorbeidrehen der Magnetpole am Funksensor werden Anregungspulse mit der Raddrehzahl proportionalen Zeitabständen mittels einer Induktivität in den Funksensor induziert, an welchen ein Signalgeber angeschlossen ist.DE 100 10 846 AI describes wireless, interrogable, passive sensor modules which contain a surface acoustic wave element. With regard to the technical fundamentals of surface acoustic wave elements, reference is made to this document. To generate the radio signals, several magnetic poles and the radio sensor are moved relative to one another at a speed proportional to the wheel speed. The magnetic poles are arranged on a pole wheel at equal angular distances from one another. When the magnetic poles turn past the radio sensor, excitation pulses with time intervals proportional to the wheel speed are induced in the radio sensor by means of an inductor, to which a signal transmitter is connected.
Der Funksensor besitzt als Codiereinrichtung eine als Oberflächenwellen (OFW) -Bauelement ausgebildete Verzögerungsleitung. Die vom Signalgeber in dasAs a coding device, the radio sensor has a delay line designed as a surface wave (SAW) component. The from the signal generator in the
Oberflächenwellen (OFW) -Bauelement eingespeisten Impulse werden von einem Interdigitalwandler in sich an der Oberfläche eines piezoelektrischen Kristalls des Bauelements sich ausbreitende mechanische Wellen gewandelt. Im Strahlengang dieser Oberflächenwellen sind teilreflektierende Elektrodenstrukturen entsprechend der zu übermittelnden Codierung in einer charakteristischen Reihenfolge als Reflektoren eingebracht. Diese teilre lektierenden Strukturen bilden aus dem einzelnen Anregungsimpuls mehrere Impulse, die zum Interdigitalwandler zurückreflektiert werden. Dort werden sie in elektromagnetische Wellen gewandelt und als Funksignal abgestrahlt.Surface wave (SAW) component fed pulses are converted by an interdigital transducer into mechanical waves propagating on the surface of a piezoelectric crystal of the component. In the beam path of these surface waves, partially reflecting electrode structures are introduced as reflectors in a characteristic sequence in accordance with the coding to be transmitted. These partially reflecting structures form several pulses from the single excitation pulse, which are reflected back to the interdigital transducer. There they are converted into electromagnetic waves and emitted as a radio signal.
Der Erfindung liegt nun die Aufgabe zugrunde, eine Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades bereitzustellen, wobei auf eine aufwendige Sensorik zur Ermittlung der Raddrehzahl und hieraus zu berechnender Beschleunigung des Fahrzeugrades verzichtet werden soll .The invention is based on the object of providing a device for determining the acceleration of a vehicle wheel, wherein a complex sensor system for determining the wheel speed and the acceleration of the vehicle wheel to be calculated therefrom should be dispensed with.
Die Aufgabe wird gelöst durch eine Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades mit einem im Fahrzeugrad angeordneten seine Beschleunigungsinformation als Funksignal an einen Empfänger weitergebenden Funksensor, der ein Oberflächenwellen (OFW) -Bauelement mit wenigstens einer derart an ihm befestigten Masse m aufweist, dass eine Fahrzeugbeschleunigung eine Längenänderung des Oberflächenwellen (OFW) -Bauelements verursacht, welche als Laufzeitänderung mechanischer Wellen erfassbar ist, wobei die Laufzeitänderung als Beschleunigungsinformation an den Empfänger weitergegeben wird.The object is achieved by a device for determining the acceleration of a vehicle wheel with an acceleration information arranged in the vehicle wheel as a radio signal, which transmits a radio signal to a receiver, which has a surface wave (SAW) component with at least one mass m attached to it in such a way that vehicle acceleration a change in length of the Surface wave (SAW) component causes, which can be detected as a change in transit time of mechanical waves, the change in transit time is passed on to the receiver as acceleration information.
Durch die auf die Masse m während der Fahrzeugbeschleunigung einwirkende Kraft F wird eine Längenänderung des Oberflächenwellen (OFW) -Bauelements in Richtung oder Gegenrichtung der befestigten Masse m verursacht. Je nach Richtung der Längenänderung handelt es sich hierbei um eine Dehnung oder Stauchung (Zusammendrückung) des Oberflächenwellen (OFW) -Bauelements.The force F acting on the mass m during vehicle acceleration causes a change in the length of the surface wave (SAW) component in the direction or opposite direction of the attached mass m. Depending on the direction of the change in length, this involves an expansion or compression (compression) of the surface wave (SAW) component.
Der als Oberflächenwellensensor ausgebildete Funksensor funktioniert derart, dass eine Dehnung oder Stauchung des Oberflächenwellen (OFW) -Bauelements ein Signal, das durch das Bauelement geschickt und reflektiert wird, proportional zur Längenänderung des Bauelements ebenfalls gedehnt oder gestaucht wird. Unter Dehnung und Stauchung des Signals wird hier die Laufzeitänderung einer mechanischen Welle aufgrund der Änderung der Weglänge verstanden, welche die mechanische Welle zurückzulegen hat .The radio sensor designed as a surface wave sensor functions in such a way that an expansion or compression of the surface wave (SAW) component also stretches or compresses a signal that is sent and reflected by the component in proportion to the change in length of the component. Elongation and compression of the signal is understood here to mean the change in transit time of a mechanical shaft due to the change in the path length which the mechanical shaft has to travel.
Über die gemessenen LaufZeitänderungen der mechanischen Wellen im Oberflächenwellen (OFW) -Bauelement , die proportional zur Längenänderung des Bauelements sind, ist somit die während der Fahrzeugbeschleunigung auf die Masse m wirkende Kraft F und damit die Beschleunigung des Fahrzeugrades berechenbar.The measured changes in the running time of the mechanical waves in the surface waves (SAW) component, which are proportional to the change in length of the component, can therefore be used to calculate the force F acting on the mass m during vehicle acceleration and thus the acceleration of the vehicle wheel.
Das Beschleunigungssignal des einzelnen Fahrzeugrades kann vom ABS-System verwendet werden, um die Fahrzeugradbeschleunigung, die Fahrzeugradgeschwindigkeit und die Fahrzeugradstellung einfach zu bestimmen. Die aufwendige ABS-Sensorik, die die Raddrehzahl ermittelt und daraus einen Beschleunigungswert berechnet, kann entfallen. Vorzugsweise sind die Masse m und das Oberflächenwellen (OFW) - Bauelement in Umfangsrichtung des Fahrzeugrades nacheinander angeordnet. Hierbei gibt es zwei Ausfuhrungsformen. Die Masse m kann in Drehrichtung des Fahrzeugsrads vor oder nach dem Oberflächenwellen (OFW) -Bauelement angeordnet sein. Die Beschleunigung in Umlaufrichtung wird aus der während des Beschleunigungsvorgangs in tangentialer Richtung zum Fahrzeugrad wirkenden Kraft F bestimmt. Aufgrund der Massenträgheit kann über die Formel F=ma die tatsächliche Tangentialbeschleunigung des Fahrzeugrads berechnet wird.The acceleration signal of the individual vehicle wheel can be used by the ABS system to easily determine the vehicle wheel acceleration, the vehicle wheel speed and the vehicle wheel position. The elaborate ABS sensor system, which determines the wheel speed and uses it to calculate an acceleration value, can be omitted. The mass m and the surface wave (SAW) component are preferably arranged one after the other in the circumferential direction of the vehicle wheel. There are two versions. The mass m can be arranged in the direction of rotation of the vehicle wheel before or after the surface acoustic wave (SAW) component. The acceleration in the circumferential direction is determined from the force F acting in the tangential direction to the vehicle wheel during the acceleration process. Due to the inertia, the actual tangential acceleration of the vehicle wheel can be calculated using the formula F = ma.
In einer anderen Ausgestaltung können die Masse m und das Oberflächenwellen (OFW) -Bauelement in radialer Richtung zur Radachse nacheinander angeordnet sein. Auch hierbei gibt es zwei Ausfuhrungsformen. Die Masse m kann in radialer Richtung sowohl vor als auch nach dem Oberflächenwellen (OFW) -Bauelement angeordnet sein. In dieser Ausführungsform sorgt die Zentrifugalkraft für die Längenänderung des Oberflächenwellen (OFW) -Bauelements während der Beschleunigungsphase und kann zur Berechnung der Radialbeschleunigung des Fahrzeugrades herangezogen werden.In another embodiment, the mass m and the surface wave (SAW) component can be arranged one after the other in the radial direction to the wheel axis. There are also two versions of this. The mass m can be arranged in the radial direction both before and after the surface acoustic wave (SAW) component. In this embodiment, the centrifugal force ensures the change in length of the surface wave (SAW) component during the acceleration phase and can be used to calculate the radial acceleration of the vehicle wheel.
Weitere vorteilhafte Ausgestaltungen der Erfindung sind in den Unteransprüchen wiedergegeben.Further advantageous embodiments of the invention are given in the subclaims.
Die Erfindung wird anhand mehrerer Ausführungsbeispiele in den Figuren näher erläutert. Die FIG 1 und 2 zeigen jeweils eine Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades mit einem Fahrzeugrad und einem in ihm angeordneten Funksensor in schematischer Darstellung und unterschiedlicher Anordnung.The invention is explained in more detail with reference to several exemplary embodiments in the figures. 1 and 2 each show a device for determining the acceleration of a vehicle wheel with a vehicle wheel and a radio sensor arranged in it in a schematic representation and different arrangement.
Die in FIG 1 veranschaulichte Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades 2 umfasst einen im Fahrzeugrad 2 angeordneten, ein Oberflächenwellen (OFW) - Bauelement 4 enthaltenden Funksensor 6. Eine Masse m 8 ist am Oberflächenwellen (OFW) -Bauelement 4 des Funksensors 6 so befestigt, dass Oberflächenwellen (OFW) -Bauelement 4 und Masse m 8 in tangentialer Richtung oder Umfangsrichtung zum Fahrzeugrad 2 angeordnet sind. Zu der angegebenen Drehrichtung 10 des Fahrzeugsrads 2 ist die Masse m 8 in Drehrichtung 10 vor dem Oberflächenwe11en (OFW) -Bauelement 4 angeordnet. Die Reihenfolge bzgl . der Drehrichtung 10 ist nicht von Bedeutung.The device illustrated in FIG. 1 for determining the acceleration of a vehicle wheel 2 comprises a radio sensor 6 arranged in the vehicle wheel 2 and containing a surface wave (SAW) component 4. A mass m 8 is on the surface wave (SAW) component 4 of the radio sensor 6 attached that surface waves (SAW) component 4 and mass m 8 are arranged in the tangential direction or circumferential direction to the vehicle wheel 2. For the specified direction of rotation 10 of the vehicle wheel 2, the mass m 8 is arranged in the direction of rotation 10 in front of the surface component (SAW) 4. The order regarding the direction of rotation 10 is not important.
Während der Beschleunigung des Fahrzeugs wird eine Längenänderung des Oberflächenwellen (OFW) -Bauelements 4 verursacht. Bei Drehrichtung 10 wird aufgrund der Trägheit der Masse m 8 eine Stauchung des Oberflächenwellen (OFW) - Bauelements 4 erzielt. Die Stauchung, also die dementsprechende Längenänderung, ist ein Maß für die auf die Masse 8 während der erfolgenden Beschleunigung des Fahrzeugs einwirkende Kraft und wird als Beschleunigungsinformation an einen zentral im Fahrzeug angeordneten, nicht weiter dargestellten Empfänger einer nicht weiter dargestellten Steuereinrichtung weitergegeben .During the acceleration of the vehicle, a change in length of the surface wave (SAW) component 4 is caused. In the direction of rotation 10, compression of the surface waves (SAW) component 4 is achieved due to the inertia of the mass m 8. The compression, that is the corresponding change in length, is a measure of the force acting on the mass 8 during the acceleration of the vehicle and is passed on as acceleration information to a receiver of a control device, not shown, which is arranged centrally in the vehicle and is not shown.
Die im Oberflächenwellen (OFW) -Bauelement 4 von einem nicht weiter dargestellten Interdigitalwandler generierten mechanische Wellen werden von im Strahlengang dieser mechanischen Oberflächenwellen in einer charakteristischen Reihenfolge eingebrachten teilreflektierendeThe mechanical waves generated in the surface wave (SAW) component 4 by an interdigital transducer (not shown further) become partially reflecting in the beam path of these mechanical surface waves in a characteristic sequence
Elektrodenstrukturen 12 reflektiert. Diese teilreflektierenden Elektrodenstrukturen bilden aus dem einzelnen Anregungsimpuls mehrere Impulse, die zum Interdigitalwandler zurückreflektiert werden. Dort werden sie in elektromagnetische Wellen gewandelt und als Funksignal, welches die Beschleunigungsinformation enthält, abgestrahlt. Durch die charakteristische Reihenfolge der Reflektoren, welche gechirpte oder dispersive Strukturen haben können, wird zusätzlich dem Funksignal eine bestimmte dem jeweiligen Fahrzeugrad zugeordnete Codierung aufgeprägt, wie dies in der eingangs genannten Anmeldung beschrieben ist. Die Elektrodenstrukturen 12 können beispielsweise als Metallstreifen ausgeführt sein. Auch eine Verwendung des Oberflächenwellen (OFW) -Bauelements 4 ohne Elektrodenstrukturen ist möglich, da die Oberflächenwellen ebenso an den Stirnflächen des Oberflächenwellen (OFW) -Bauelements 4 reflektiert werden.Electrode structures 12 reflected. These partially reflecting electrode structures form several pulses from the single excitation pulse, which are reflected back to the interdigital transducer. There they are converted into electromagnetic waves and emitted as a radio signal that contains the acceleration information. Due to the characteristic sequence of the reflectors, which can have chirped or dispersive structures, a certain coding assigned to the respective vehicle wheel is additionally impressed on the radio signal, as described in the application mentioned at the beginning. The electrode structures 12 can be designed, for example, as metal strips. Also a use of the surface wave (SAW) component 4 without electrode structures is possible because the surface waves are also reflected on the end faces of the surface wave (SAW) component 4.
Eine Dehnung oder Stauchung des Oberflächenwe11en (OFW) - Bauelements 4, was einer Beschleunigung des Fahrzeugs in verschiedene Richtungen entspricht, bewirkt, dass die mechanischen Signale, welche im Verhältnis zur zeitlichen Länge des Beschleunigungsvorganges durch das Oberflächenwellen (OFW) - Bauelement 4 geschickt und reflektiert werden, proportional zur Längenänderung des Oberflächenwellen (OFW) -Bauelements 4 ebenfalls gedehnt oder gestaucht werden. Mit der Längenänderung des Oberflächenwellen (OFW) -Bauelements 4 verändert sich die freie Weglänge zwischen Interdigitalwandler und teilreflektierender Elektrodenstruktur 12. Die Laufzeitdifferenz enthält somit die benötigte Beschleunigungsinformation.A stretching or compression of the surface wave (SAW) component 4, which corresponds to an acceleration of the vehicle in different directions, has the effect that the mechanical signals which are sent and reflected by the surface wave (SAW) component 4 in relation to the length of time of the acceleration process are proportional to the change in length of the surface wave (SAW) component 4 also stretched or compressed. With the change in length of the surface wave (SAW) component 4, the free path length between the interdigital transducer and the partially reflecting electrode structure 12 changes. The transit time difference thus contains the required acceleration information.
Über die gemessenen LaufZeitänderungen der mechanischen Wellen im Oberflächenwellen (OFW) -Bauelement 4 ist somit die während der Fahrzeugbeschleunigung auf die Masse m wirkende Kraft F und damit die Beschleunigung des Fahrzeugrades berechenbar.The force F which acts on the mass m during the vehicle acceleration and thus the acceleration of the vehicle wheel can thus be calculated via the measured changes in the running time of the mechanical waves in the surface wave (SAW) component 4.
Die Masse m 8 wird dabei so groß gewählt, dass sich bei dem zu erwartenden Beschleunigungsbereich für das Kraftfahrzeug ein Längenänderungsbereich des Oberflächenwellen (OFW) -Bauelements 4 ergibt, der eine einfache Auswertung der LaufZeitdifferenzen der mechanischen Wellen ermöglicht.The mass m 8 is chosen so large that there is a change in the length of the surface wave (SAW) component 4 in the acceleration range to be expected for the motor vehicle, which enables a simple evaluation of the travel time differences of the mechanical waves.
Während des Fahrzeugradumlaufs wird der beschleunigungsbedingten Längenänderung des Oberflächenwellen (OFW) -Bauelements 4 aufgrund der einwirkenden Gravitationskraft ein Sinusverlauf aufgepräg . Hieraus lässt sich in bekannter Weise die Radstellung und/oder die Winkelgeschwindigkeit und/oder die Raddrehzahl ermitteln. Die Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades 2 gemäss FIG 2 weist einen Funksensor 4 mit den technischen Merkmalen entsprechend den Ausführungen zu FIG 1 auf. Die Masse m 8 und das Oberflächenwellen (OFW) -Bauelement 4 sind in radialer Richtung zur Radachse 14 nacheinander angeordnet. Es ist sowohl möglich, dass die Masse m 8 auf der der Radachse 14 zugewandten als auch auf der der Radachse 14 abgewandten Seite am Oberflächenwellen (OFW) -Bauelement 4 angebracht ist. In dieser Ausfuhrungsform sorgt die Zentrifugalkraft für die Längenänderung des Oberflächenwellen (OFW) -Bauelements 4 während der Beschleunigungsphase und kann zur Berechnung der Radialbeschleunigung des Fahrzeugrades 2 herangezogen werden.During the vehicle wheel revolution, the acceleration-related change in length of the surface wave (SAW) component 4 is impressed by a sinusoidal curve due to the gravitational force acting on it. From this, the wheel position and / or the angular velocity and / or the wheel speed can be determined in a known manner. The device for determining the acceleration of a vehicle wheel 2 according to FIG. 2 has a radio sensor 4 with the technical features corresponding to the statements relating to FIG. 1. The mass m 8 and the surface wave (SAW) component 4 are arranged one after the other in the radial direction to the wheel axis 14. It is possible that the mass m 8 is attached to the surface wave (SAW) component 4 on the side facing the wheel axis 14 and on the side facing away from the wheel axis 14. In this embodiment, the centrifugal force ensures the change in length of the surface wave (SAW) component 4 during the acceleration phase and can be used to calculate the radial acceleration of the vehicle wheel 2.
Je nach Ausfuhrungsform kann der Funksensor 6 in den Reifen oder in die Felge des Fahrzeugrades 2 integriert werden. Das gilt für alle Ausfuhrungsformen des Funksensors 6.Depending on the embodiment, the radio sensor 6 can be integrated in the tire or in the rim of the vehicle wheel 2. This applies to all versions of the radio sensor 6.
In einer weiteren nicht dargestellten Ausgestaltung der Vorrichtung ist die Längenänderung des Oberflächenwellen (OFW) - Bauelements in zwei zueinander orthogonal verlaufenden Richtungen messbar. Aufgrund der orthogonalen WerkstoffStruktur des Oberflächenwellen (OFW) -Bauelements 4 können Oberflächenwellen senkrecht zueinander durch das Oberflächenwellen (OFW) -Bauelement 4 laufen, ohne einander zu beeinflussen. Dadurch wird ermöglicht wenigstens zwei Messgrößen, wie Raddrehzahl, Reifendruck oder Beschleunigung zugleich zu messen.In a further embodiment of the device, not shown, the change in length of the surface wave (SAW) component can be measured in two directions that are orthogonal to one another. Due to the orthogonal material structure of the surface wave (SAW) component 4, surface waves can run perpendicular to one another through the surface wave (SAW) component 4 without influencing one another. This enables at least two measurement variables, such as wheel speed, tire pressure or acceleration, to be measured simultaneously.
Ist in jede der beiden zueinander senkrechten Richtungen jeweils eine Masse am Oberflächenwellen (OFW) -Bauelement angeordnet, so kann die Radbeschleunigung redundant ermittelt werden. If a mass is arranged on the surface wave (SAW) component in each of the two mutually perpendicular directions, the wheel acceleration can be determined redundantly.

Claims

Patentansprüche claims
1. Vorrichtung zur Ermittlung der Beschleunigung eines Fahrzeugrades (2) mit einem im Fahrzeugrad (2) angeordneten seine Beschleunigungsinformation als Funksignal an einen Empfänger weitergebenden Funksensor (6) , der ein Oberflächenwellen (OFW) -Bauelement (4) mit wenigstens einer derart an ihm befestigten Masse m (8) aufweist, dass eine Fahrzeugbeschleunigung eine Längenänderung des1. Device for determining the acceleration of a vehicle wheel (2) with its acceleration information arranged in the vehicle wheel (2) as a radio signal, which transmits a radio sensor (6) to a receiver, which has a surface wave (SAW) component (4) with at least one such on it attached mass m (8) has that a vehicle acceleration a change in length of the
Oberflächenwellen (OFW) -Bauelements (4) verursacht, welche als Laufzeitänderung mechanischer Wellen erfassbar ist, wobei die Laufzeitänderung als Beschleunigungsinformation an den Empfänger weitergegeben wird.Surface wave (SAW) component (4) causes, which can be detected as a change in transit time of mechanical waves, the change in transit time being passed on to the receiver as acceleration information.
2. Vorrichtung nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, d a s s die Masse m (8) und das Oberflächenwellen (OFW) -Bauelement (4) in Umfangsrichtung des Fahrzeugrades (2) nacheinander angeordnet sind.2. Device according to claim 1, d a d u r c h g e k e n n z e i c h n e t, that the mass m (8) and the surface waves (SAW) component (4) in the circumferential direction of the vehicle wheel (2) are arranged one after the other.
3. Vorrichtung nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, d a s s die Masse m (8) und das Oberflächenwellen (OFW) -Bauelement (4) in radialer Richtung zur Radachse (14) nacheinander angeordnet sind.3. Device according to claim 1, d a d u r c h g e k e n n z e i c h n e t, that the mass m (8) and the surface waves (SAW) component (4) are arranged one after the other in the radial direction to the wheel axis (14).
4. Vorrichtung nach einem der Ansprüche 1 bis 3, d a d u r c h g e k e n n z e i c h n e t, d a s s die Längenänderung des Oberflächenwellen (OFW) -Bauelements (4) in zwei zueinander orthogonal verlaufenden Richtungen erfassbar ist . 4. Device according to one of claims 1 to 3, characterized in that the change in length of the surface waves (SAW) component (4) can be detected in two mutually orthogonal directions.
5. Vorrichtung nach Anspruch 4, d a d u r c h g e k e n n z e i c h n e t, d a s s für jede Richtung jeweils eine Masse am Oberflächenwellen (OFW) -Bauelement (4) befestigt ist.5. The apparatus of claim 4, d a d u r c h g e k e n n z e i c h n e t, that a mass for each direction is attached to the surface wave (SAW) component (4).
6. Vorrichtung nach einem der Ansprüche 1 bis 5, d a d u r c h g e k e n n z e i c h n e t, d a s s für die mechanischen Wellen teilreflektierende Elektrodenstrukturen (12) im Oberflächenwellen (OFW) - Bauelements (4) vorgesehen sind.6. Device according to one of claims 1 to 5, d a d u r c h g e k e n n z e i c h n e t, that a s s are provided for the mechanical waves partially reflecting electrode structures (12) in the surface waves (SAW) component (4).
7. Vorrichtung nach einem der Ansprüche 1 bis 6, d a d u r c h g e k e n n z e i c h n e t, d a s s über den der Längenänderung aufgrund der während des Fahrzeugradumlaufs einwirkenden Gravitationskraft aufgeprägten Sinusverlauf die Radstellung und/oder die Winkelgeschwindigkeit und/oder die Raddrehzahl bestimmbar ist.7. The device according to claim 1, wherein the wheel position and / or the angular velocity and / or the wheel speed can be determined via the sine curve impressed on the change in length due to the gravitational force acting during vehicle wheel rotation.
8. Vorrichtung nach einem der Ansprüche 1 bis 7, d a d u r c h g e k e n n z e i c h n e t, d a s s der Reifendruck erfassbar sind. 8. Device according to one of claims 1 to 7, d a d u r c h g e k e n n z e i c h n e t, that the tire pressure can be detected.
EP03729969A 2002-06-21 2003-05-02 Device for determining the acceleration of the wheel of a vehicle Withdrawn EP1530520A2 (en)

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DE2002127768 DE10227768A1 (en) 2002-06-21 2002-06-21 Device for determining the acceleration of a vehicle wheel
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PCT/EP2003/004637 WO2004000578A2 (en) 2002-06-21 2003-05-02 Device for determining the acceleration of the wheel of a vehicle

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