Classifications

• • 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
  • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
  • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
  • G01P3/488—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by variable reluctance detectors
• • 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
• • 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
  • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
  • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
  • G01P3/489—Digital circuits therefor

Definitions

• the invention relates to a method for detecting a speed in a vehicle, a control device for carrying out the method, a speed sensor with the control device and a vehicle with the speed ⁇ keitssensor.
• an inductive speed sensor ⁇ sensor in the form of a wheel speed sensor in which rotates as a sensor formed as a sensor element formed before ferromagnetic encoder in front of a trained as a sensor coil with wholly or partially permanent magnetic core as a yoke.
• the arrangement acts as a generator.
• a Gene ⁇ ratorschreib is induced whose frequency and amplitude are per ⁇ proportional to the speed.
• an active speed sensor in the form of a wheel speed sensor in which rotates in front of a magnetoresistive element as a sensor ferro- or permanent magnetic encoder as a donor element.
• the sensor is connected as a bridge in a bridge circuit, wherein the falling on the sensor bridges ⁇ voltage is modulated by the rotary encoder and evaluated by an evaluation circuit.
• magnetoresistive elements may be Hall elements, AMR elements, XMR elements or GMR elements.
• a method for detecting a speed between a sensor designed as an inductance and a inductance varies. the donor element in a vehicle, the steps:
• the invention is based on the consideration that the
• magnetoresistive sensors in common is that the amplitude of the signal from the sensor does not depend on the speed. Therefore, the magneto-resistive speed sensors can detect a speed from standstill up to a maximum speed which is determined by the signal processing due to Ent ⁇ throw decisions. These design decisions may include, for example, a necessary low-pass filtering of the bridge voltage for noise suppression.
• the generator voltage and its frequency are proportional to the detected speed.
• the generator voltage in inductive speed sensors which is proportional to the speed to be detected also has the disadvantage that at high speeds the correspondingly high generator voltage interferes.
• the semiconductor circuits, which are used for signal processing in inductive speed sensors are designed for ever lower voltages to be processed, so that the inputs of these semiconductor circuits must be protected with additional components against the excessive generator voltages.
• the inductive speed sensors also have advantages. On the one hand, the manufacturing costs are lower compared to magnetoresistive speed sensors made of semiconductors. On the other hand, they are particularly robust. This applies to mechanical stress, to external electromagnetic fields and to the permissible temperature range.
• Magnetoresistive sensor without amplifier over a line of several meters in length past many electromagnetic interference, reliably transfer to outsourced signal processing circuit.
• magnetoresistive speed sensor is considered in terms of their changing electrical impedance, so that the inventive method combines the advantages of the inductive Ge ⁇ speed sensors and the magnetoresistive speed sensors together.
• the inductance can be different than a
• Magnetoresistive sensor over a cable length of several meters are controlled and read, because the internal resistance of an inductor unlike a
• Magnetoresistive sensor not in the range of some kQ but much lower.
• the change in the inductance can be brought about as in the conventional speed sensors via an encoder, which may be formed, for example, ferromagnetic.
• the specified method comprises the steps:
• a variable measurement voltage can be detected as a measurement signal, from which the speed to be measured emerges.
• a measurement signal is selected as the source voltage while an AC voltage ⁇ .
• the voltage drop across the inductance is amplitude modulated by the movement of the encoder, the modulation being independent of the modulation frequency of the source voltage.
• the speed of the encoder does not affect the amplitude of the encoder
• the alternating voltage has a frequency between 30 kHz and 500 kHz.
• any frequency range can be used for the AC voltage, at lower frequencies, the usable frequency of the falling in the inductance measurement voltage is however limited because the measured Ge ⁇ speed, for example in the form of a wheel speed is not should fall below the modulation frequency.
• Higher frequencies when properly designed, have no disadvantages in the function of the speed sensor implementing the specified method, but are unnecessary and, especially when the sensor is driven by a long cable, can lead to unwanted electromagnetic emissions.
• the stability of the AC voltage does not require high demands, because as a result of the demodulation in the signal processing, the modulation frequency of the AC voltage has no direct influence on the speed to be measured. It should only be ensured that a specified frequency interval for which the specified method ⁇ leading speed sensor is designed, is not left.
• the specified method comprises the step of demodulating the voltage dropped at the inductance.
• the demodulation can be done arbitrarily. It is only necessary, the signal carrier, so the source voltage of the actually interesting information, so the speed of the encoder and the associated induct ⁇ telless selectedung of trained as inductance
• the demodulation for this purpose comprises an Amp ⁇ litudendemodulation, since the sensor changing its inductance acquires information which is amplitude modulated by the AC voltage source designed as a voltage.
• any known methods for AM demodulation can be used, both analog and digital. Circuits that would not be able to demodulate arbitrary signals with small distortions are also possible, since the information interesting for the given method as a result of the demodulation basically comprises the time of change between only two discrete states of the latter Inductance changing sensor.
• the at the Inductance dropping voltage filtered with a low pass for demodulation is particularly useful in the context of the specified method, because an upper limit frequency low-pass filtering can set in the specified method to a value that allows the support of all applications in the car, without any adaptation to vehicle types or the measuring point is necessary. This is also possible because of the designed as an inductance
• a control device is set up to carry out one of the specified methods.
• the specified control device can be used as an adapter for an already existing in a vehicle
• the specified control device messag Congress furnishede and control unit side terminals have to convert the information about the speed to be detected in the speed to be detected ⁇ um, so that they can be understood by the control unit in the conventional manner.
• the specified device has a memory and a processor.
• the specified method is stored in the form of a Compu ⁇ terprogramms in the memory and the processor is provided for performing the method when the computer program from the memory is loaded into the processor.
• a computer program comprises program code means for performing all the steps of one of the specified methods when the computer program is run on a computer or one of the specified devices is performed.
• a computer program product comprises a program code which is stored on a data carrier and the compu ⁇ terlesbaren, when executed on a data processing device, carries out one of the methods specified.
• a speed sensor for detecting a speed in a vehicle
• a sensor designed as an inductance whose inductance is variable by a donor element
• one of the specified control devices for detecting the speed between the sensor and the encoder element.
• the inductance comprises a coil and a yoke guided through the coil, which is set up to form a magnetic circuit via the transmitter element. In this way, the magnetic fields occurring during the measurement of the speed can be concentrated, whereby the measurement of the speed can be carried out more sensitively.
• the yoke is formed soft magnetic.
• the present embodiment is based on the consideration that the operation of a conventional inductive speed sensor in the manner of a generator requires a strong field, so that even at low speeds a sufficient signal amplitude can be achieved and thus the above-mentioned minimum detectable speed is not too high.
• a strong magnet would be required, which is designed as a permanent magnet, however, is relatively expensive.
• only one yoke is needed in the specified speed sensor, which can be made of almost all soft magnetic materials, including ferrite or even steel, the most likely cost-effective way.
• the maximal Working temperature can be at 250 ° C and even higher, because the specified speed sensor can not only be completely built without semiconductors, it can not be affected by demagnetization, since no permanent magnet is present. Degaussing is known to be a problem that can damage permanent magnets both at high temperatures and in strong external magnetic fields.
• the speed sensor can optionally be made one to two changes to adapt to the new function, which relate to the replacement of the aforementioned permanent magnet by a soft magnetic component and in addition to the winding.
• the second optional change relates to the winding and contributes to further cost reduction.
• the impedance measurement in the sensor according to the invention can be achieved, in particular due to the free selection of the modulation frequency described above, with a significantly smaller winding with fewer turns than in the conventional inductive speed sensor.
• the specified speed sensor is set up to detect a speed as a speed.
• speeds may include, for example, speeds of the wheels of vehicles, speeds of crankshafts of internal combustion engines, or speeds in powertrain components of vehicles, such as driven.
• a vehicle includes one of the specified speed sensors, an actuator, and a controller for driving the actuator based on the speed detected by the speed sensor.
• the Wiring of the specified vehicle as well as the construction of a control unit and the sensor designed as an inductance sensor in the vehicle need not be changed compared to the prior art.
• control device of the wheel speed sensor is designed, for example, as an adapter which is connected on the one hand to the conventional control unit of the vehicle and on the other hand to the sensor designed as an inductance.
• the adapter can imitate at its output the electrical interface of the conventional speed sensors with sufficient accuracy.
• the entire controller of the specified speed sensor may be located at the location of the evaluating controller. There, the control device is protected from high temperatures and other raw environmental conditions, as they can prevail at the measuring point. There are also other installation locations possible, but the positioning of the control device on or in the control unit is particularly advantageous.
• one of the above-mentioned source voltage that is, the voltage on which the modulation described above is based
• the signal source and signal processing controller would be separated by a few meters in a typical vehicle, but due to the robustness described above, to interference due to the low impedance of the inductor
• FIG. 2 is a schematic diagram of a wheel speed sensor in the vehicle
• FIG. 3 shows an illustration of an interconnection of the vehicle dynamics control from FIG. 1 with a wheel speed sensor from FIG. 2, FIG.
• Fig. 7 shows a circuit diagram of another possible wheel speed sensor.
• the same technical elements are provided with the same reference numerals and described only once.
• FIG. 1 a plan view of a vehicle 2 is shown.
• the vehicle 2 has a chassis 4, which is supported in a manner known per se on a road not shown in more detail by wheels 6.
• a wheel speed sensor 10 which measures a wheel speed 12 shown in FIG. 2 at the location of the respective wheel 6 and outputs it to a vehicle dynamics control 14, is arranged on each wheel 6.
• the Wheel speed sensor 10 may be formed as a tire pressure sensor, which outputs a tire pressure instead of the wheel speed 12 to a tire pressure monitoring system instead of the vehicle dynamics control 14.
• the vehicle dynamics control 14 receives the wheel speeds 12 from the wheel speed sensors 10, among other known driving dynamics data, as actual values. In a manner known to the person skilled in the art, the vehicle dynamics control 14 can contrast the received driving dynamics with a desired driving dynamics, such as, for example, a desired trajectory. If a difference between the desired driving dynamics and the received driving dynamics, the control device 14 can be intervened by means of actuating 2 ⁇ via actuators such as brakes not further shown to the desired driving dynamics return the vehicle.
• FIG. 2 shows a schematic diagram of a wheel speed sensor 10 in the vehicle 2. So that the wheel speed sensor 10 can detect the wheel speeds of its corresponding wheel 6, a per se known encoder 16 is arranged on the wheel 6 in the present embodiment of a ferromagnetic material.
• the wheel speed sensor 10 comprises a coil 18 with an inductance, wherein a soft magnetic core 20 is guided through a center of the coil 18.
• a voltage source 22 is connected, which applies to the coil 18, a source voltage 24 in the form of a harmonic alternating voltage with a constant amplitude.
• the encoder 16 changes the inductance of the coil 18 in a periodic manner.
• the voltage applied to the coil 18 voltage source 24 is changed in a manner known per se in its amplitude, and thus amplitudenmo ⁇ duliert.
• the amplitude modulated source voltage 24 can then be used as
• Measuring voltage 26 are detected by a measuring device 28, which derives from the amplitude-modulated source voltage 24, an intermediate voltage 30, which is dependent on the wheel speed to be detected 12.
• the measuring device 28 is preferably designed as a demodulation device, which can construct the intermediate voltage 30 in a manner known per se under an optional knowledge of the modulation frequency 32 of the source voltage 24.
• the intermediate voltage 30 can then finally be processed in an evaluation device 34 that the wheel speeds 12 can be connected in a standardized form to the vehicle dynamics control 14. Is the coil 18 as a sensor ready in the vehicle 2 available, for example because that
• the other of the wheel speed sensors 10 shown in FIG. 1 can be connected to the connections 40 not occupied in FIG.
• FIG. 4 shows a circuit whose signal processing with the measuring circuit 28 embodied as an AM demodulator consists of a
• Rectifying diode 42, a smoothing capacitor 44 and a resistor 46 begins.
• a representation of the voltage source 22 has been omitted for the sake of clarity.
• the measuring voltage 26 at the input of the measuring circuit 28 is through the rectifying diode 42 is rectified and smoothed by the smoothing capacitor 44.
• the rectified and smoothed measurement voltage 26 corresponds to the intermediate voltage 30, which receives a comparator 48 one of its inputs, while at the other input an appli ⁇ onscomb adjustable reference voltage 50 is.
• the comparator 48 compares the intermediate voltage 30 with the reference voltage 50 and outputs an output signal 52, which should have a pulse-like course, which directly reproduces the wheel speed 12 of the corresponding wheel in a manner known per se.
• the intermediate voltage 30 has a ripple, false pulses and thus incorrect wheel speeds 12 can be generated, so that the output signal 52 of the comparator 48 can not be used directly as Radcard ⁇ number signal 12.
• the output signal 52 is supplied to a D flip-flop 54 wei ⁇ terleton to which a clock signal is applied 56, which is synchronized with the modulation frequency 32nd.
• the output signal 52 at the output of the comparator 48 is always evaluated only at certain phases of the measuring voltage 26 and passed through the D flip-flop 54 as Radcardsignal 12. In this way, the ripple is effectively suppressed.
• the measurement voltage 26 for generating the intermediate voltage 30 is tapped off via a pickup resistor 60, wherein a sampling signal 62 used for sampling is synchronized with the modulation frequency 32, so that voltage values between the individual periods of the source voltage 22 ultimately used as carrier voltage remain unconsidered so that the envelope of the measurement voltage 26 is filtered out in a manner known per se.
• the downstream comparator 48 At an input of the downstream comparator 48 is thus the demodulated measuring voltage 26 and thus the intermediate chip ⁇ tion 30, which is free in the present embodiment of the explained in the context of FIG. 4 ripple.
• the intermediate voltage 30 is also applied to the further input of the comparator via a low-pass filter 64 known per se.
• the output voltage of the comparator 48 changes twice per period of the intermediate voltage 30, provided that a frequency of the intermediate voltage 30 at the input, a cut-off frequency of the low-pass filter 64 is not too clear below.
• the wheel speed sensor 10 embodied herein requires a certain amount of time after powering up an operating voltage until the low pass filter 64 has settled to its equilibrium value.
• the low-pass filter 64 can be designed as an RC element with the advantage that the equilibrium value is variable, so that changes to the sensor 18 or the environment, for example due to temperature change, have no influence on the detected wheel speeds 12 provided these changes are slow.
• the circuit in FIG. 6 again uses the AM demodulator from FIG. 3.
• a low-pass filter 64 which in the present embodiment is designed as a second-order active low-pass filter in a Shaner configuration. Due to the active low-pass filter, the residual ripple in the intermediate voltage 30 can be strongly suppressed.
• the active low-pass filter 64 is followed by an amplifier circuit 66, which in the present embodiment is connected in a manner known per se as an inverting amplifier.
• Another low-pass filter 64 in the amplifier circuit 66 has the same function as the low-pass filter 64 in FIG. 5. If a high gain is selected for the amplifier circuit, then the output voltage is predominantly in a positive or negative limit of the amplifier circuit 66 and the output of the amplifier circuit 66 acts as a logic output, at which the wheel speed signal 12 can be tapped.
• the comparator 48 can be switched as in FIGS. 4 and 5.
• a first part 68 of the circuit in Fig. 7 is constructed analogously to the circuit of Fig. 6, wherein in Fig. 7 instead of the amplifier circuit 66 of the interconnected comparator 48 is indicated.
• This first part 68 of the circuit has already been described and referenced in detail in the context of FIG. 6, which is why in the context of FIG. 7 for the sake of brevity, the first part will not be discussed further.
• a Schmitt trigger 70 which has a comparator 72, which is connected in a manner known per se for fixing a hysteresis with two resistors 74, is located at the output of the first part 68 in the present embodiment.
• an application-dependent selectable reference potential 76 can be switched.
• the Schmitt trigger 70 with its hysteresis has the task to prevent possible speed pulses at the output of the circuit, which can be set without the Schmitt trigger 70 when the wheel 6 is at a standstill and therefore the inductance of the coil 18 is not changes. In this case, it would be possible without hysteresis that smallest changes in the measuring voltage 26, for example due to noise, appear in the wheel speed signal 12, where they can no longer be distinguished from a non-zero wheel speed signal 12.
• an amplifier 78 can be connected to the Schmitt trigger 70 as a driver if a load to which the wheel speed signal 12 is output requires it.
• the amplifier 78 is designed as a voltage follower in the present embodiment. Potential vibrations of the amplifier 78 are suppressed by another resistor 74.
• the functions of the last three comparators can be combined prior to the output of the wheel speed signal 12 in a comparator. This total comparator should then be used as a Schmitt trigger through a separate input or through the external circuitry of the comparator 72 of the Schmitt trigger 70. At one input, a low pass would have to be switched and the comparator should have the ability to directly drive the connected load.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)

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Cited By (2)

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Citations (5)

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• 2012
  • 2012-12-20 DE DE102012224098.5A patent/DE102012224098A1/de not_active Withdrawn
• 2013
  • 2013-11-29 CN CN201380067312.8A patent/CN104870275A/zh active Pending
  • 2013-11-29 KR KR1020157017710A patent/KR20150097564A/ko not_active Application Discontinuation
  • 2013-11-29 WO PCT/EP2013/075159 patent/WO2014095311A1/de active Application Filing
  • 2013-11-29 EP EP13798666.7A patent/EP2934965A1/de not_active Ceased

Patent Citations (5)

Non-Patent Citations (1)

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