JP2019168382A - Signal processing device and sensor device - Google Patents

Abstract

An object of the present invention is to provide a signal processing device capable of distinguishing between a failure of a sensor and a stop of a detection target such as a turbocharger. A signal processing device according to one embodiment of the present invention is a signal processing device connected to a detection coil for detecting a signal, and includes an oscillation unit and a detection unit. The oscillating unit has an oscillating circuit and a waveform shaping circuit. The oscillation circuit outputs a sine wave signal. The waveform shaping circuit is configured such that when a portion higher than the reference potential in the sine wave signal is set to the first amplitude and a portion lower than the reference potential is set to the second amplitude, the first amplitude and the second amplitude are set when the detection coil is disconnected. Waveform of one of the amplitudes is deformed. The detection unit has a first detection circuit, a second detection circuit, and a differential amplifier circuit. The first detection circuit detects the first amplitude. The second detection circuit detects the second amplitude. The differential amplifier circuit amplifies a difference between an output signal of the first detection circuit and an output signal of the second detection circuit. [Selection diagram] Fig. 1

Description

  The present invention relates to a signal processing device used in, for example, a rotation detection device using a change in an electrical signal due to eddy current loss, and a sensor device including the signal processing device.

  For example, Patent Document 1 discloses a rotation detection device that detects the rotation speed of a turbocharger mounted on a vehicle. The rotation detecting device includes an eddy current sensor having a sensor top (a coil around a ferrite core) and a resonance circuit connected to the eddy current sensor, and a turbocharger (blade) close to the sensor top. An eddy current is generated in the turbocharger, and a rotational speed of the turbocharger is detected from a change in an electrical signal due to the eddy current loss.

Japanese Patent No. 5645207

  However, in the rotation detection device having the above configuration, the electric signal from the eddy current sensor has the same waveform when the sensor is broken due to disconnection or the like and when the turbocharger is not rotating. Stopping cannot be distinguished from electrical signals. Therefore, if it is mistakenly determined that the turbocharger is not rotating due to a sensor failure, for example, when an engine equipped with the turbocharger is controlled, the turbocharger or the engine may malfunction or cause a failure. .

  In view of the circumstances as described above, an object of the present invention is to provide a signal processing device capable of distinguishing between a sensor failure and a stop of a detection target such as a turbocharger, and a sensor device including the signal processing device. .

In order to achieve the above object, a signal processing device according to an aspect of the present invention is a signal processing device connected to a detection coil for signal detection, and includes an oscillation unit and a detection unit.
The oscillation unit includes an oscillation circuit and a waveform deformation circuit. The oscillation circuit outputs a sine wave signal. The waveform modification circuit uses a portion of the sine wave signal that is higher than a reference potential as a first amplitude, a portion that is lower than the reference potential as a second amplitude, and the first amplitude when the detection coil is disconnected. And the waveform of any one of the second amplitude is deformed.
The detection unit includes a first detection circuit, a second detection circuit, and a differential amplifier circuit. The first detection circuit detects the first amplitude. The second detection circuit detects the second amplitude. The differential amplifier circuit amplifies a difference between the output signal of the first detection circuit and the output signal of the second detection circuit.

  The waveform deformation circuit may be a clip circuit.

  The detection unit may further include a binarization circuit that binarizes the output of the differential amplifier circuit.

  According to the present invention, it is possible to distinguish between a sensor failure and a stop of a detection target such as a turbocharger.

It is a block diagram showing roughly the composition of the sensor device provided with the signal detection device concerning one embodiment of the present invention. It is a circuit diagram which shows the structural example of the oscillation part in the said signal detection apparatus. It is an example of the signal waveform output from an oscillation part, Comprising: A shows a signal waveform at the time of normal time, B shows the signal waveform at the time of failure of a sensor top. It is a circuit diagram which shows the structural example of the detection part in the said signal detection apparatus. It is a schematic diagram showing a signal waveform (A) of an oscillation circuit, a signal waveform (B) of a differential amplifier circuit, and a signal waveform (C) of a binarization circuit that are output when a sensor top fails.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram schematically showing a configuration of a sensor device 100 according to an embodiment of the present invention. The sensor device 100 includes a sensor top 10 and a signal detection device 20. In the present embodiment, the sensor device 100 is a rotation detection device that detects the rotation speed or the rotation speed of the rotating blade T in the turbocharger.

  The sensor top 10 is, for example, a protruding eddy current sensor, and has a detection coil L1 for signal detection that is disposed in the vicinity of the metallic rotating blade T. The detection coil L1 is formed of a resin-coated copper wire such as an enameled wire wound around a magnetic core made of a soft magnetic material such as ferrite. The detection coil L <b> 1 is connected to the oscillation unit 21 of the signal detection device 20 and generates a magnetic field that generates an eddy current in the rotating blade T.

  The signal detection device 20 includes an oscillation unit 21 and a detection unit 22. The oscillation unit 21 includes an oscillation circuit 211 and a waveform deformation circuit 212. The detection unit 22 includes a detection circuit 221, a differential amplifier circuit 222, a binarization circuit 223, and a frequency divider circuit 224.

  FIG. 2 is a circuit diagram illustrating a configuration example of the oscillation unit 21.

  The oscillation circuit 211 includes a resonance capacitor C, and a detection coil L1 and an internal coil L2 connected in parallel with the resonance capacitor C. Further, illustration of the amplifying elements necessary for the oscillation circuit is omitted here. The detection coil L1 and the internal coil L2 are connected in series to the resonance capacitor C, and the coils are connected in parallel to each other. The oscillation circuit 211 oscillates at an oscillation frequency f0 determined by the capacitance of the resonance capacitor C and the combined inductance of the detection coil L1 and the internal coil L2 when a voltage is input from a power supply (not shown). The oscillation frequency f0 is not particularly limited and is, for example, 3.5 MHz.

  The oscillation circuit 211 outputs a sine wave signal having an oscillation frequency f0 as a detection signal. The rotating blade T facing the detection coil L1 passes through a position affected by the magnetic field generated by the current flowing through the detection coil L1. When the rotating blade T is at a position facing the detection coil L1, eddy current loss occurs due to the eddy current induced in the rotating blade T. Due to this influence, the voltage V of the detection signal output from the oscillation circuit 211 changes. By detecting the voltage change of the detection signal due to this eddy current loss by the detection unit 22, the rotational speed of the rotary blade T is detected as will be described later.

The waveform deformation circuit 212 is for deforming the waveform of the output signal of the oscillation circuit 211 when the sensor top 10 (detection coil L1) is disconnected.
That is, in this type of conventional rotation detection device, when the sensor top is disconnected, the signal waveform output from the oscillation circuit 211 to the detection circuit 211 has the same shape as when the rotation of the turbocharger is stopped. And turbocharger stoppage could not be distinguished. Therefore, in the present embodiment, as conceptually shown in FIG. 1, the waveform deformation circuit 212 is caused to function when the detection coil L1 is disconnected, and the signal waveform of the oscillation circuit 211 is intentionally deformed when the detection coil L1 is disconnected.

  In the present embodiment, if a portion of the sine wave signal output from the resonance circuit 211 is higher than a reference potential (in this example, the ground potential) is a first amplitude, and a portion lower than the reference potential is a second amplitude, the waveform in this embodiment. The deformation circuit 212 is formed of a clip circuit that can deform the waveform of the second amplitude when the detection coil L1 is disconnected. This clipping circuit restricts (clips) the input negative potential signal waveform to a predetermined voltage or less and deforms it so as to be asymmetric with the positive potential signal waveform.

Here, when the detection coil L1 is disconnected, the combined inductance of the oscillation circuit 211 increases, so that the oscillation frequency f0 decreases, and the impedance of the oscillation circuit 211 increases, so that the signal voltage (V) increases. For example, the oscillation circuit 211 is set such that when the detection coil L1 is disconnected, the oscillation frequency is decreased from 3.5 MHz (normal time) to 800 kHz, and the signal voltage is increased from 6 V (normal time) to 8 V.
Here, for example, regarding the detection of the disconnection of the detection coil L1, the above-described change in oscillation frequency or change in signal voltage may be used. Alternatively, a method of adding another circuit for passing a direct current to the detection coil L1 and detecting a change in the current value is also conceivable.

  The waveform deformation circuit 212 clips a part of the negative sine wave in the signal voltage that rises when the detection coil L1 is disconnected. As an example, FIG. 3A shows a signal waveform of the oscillation circuit 211 at the normal time, and FIG. 3B shows a signal waveform of the oscillation circuit 211 when the detection coil L1 is disconnected. The predetermined voltage may be set such that when the detection coil L1 is disconnected, the vicinity of the peak voltage of the negative sine wave is clipped, and the peak voltage is, for example, ½ times before clipping.

Thus, the waveform deformation circuit 212 of the present embodiment does not function during normal times when the detection coil L1 is not disconnected, and functions only when the detection coil L1 is disconnected. For this reason, as conceptually shown in FIG. 1, the waveform deformation circuit 212 includes a switch SW that starts waveform shaping only when a disconnection (open) of the detection coil L1 is detected.
Although the block for controlling the switch SW is not shown, the disconnection is detected by the above-described disconnection detection method and the switch SW is turned on.

  Next, the detection unit 22 will be described. FIG. 4 is a circuit diagram illustrating a configuration example of the detection circuit 221 and the differential amplifier circuit 222.

  The detection circuit 221 includes a first detection circuit 221A and a second detection circuit 221B.

  The first detection circuit 221A includes capacitors C1, C2, and C3, a diode D1, and a resistor R1. The diode D1, the capacitor C2, and the resistor R1 are connected in parallel between the first signal line S1 connected to the oscillation circuit 211 and the reference potential. The capacitor C2 and the resistor R1 constitute an integration circuit F1 that detects the first amplitude higher than the reference potential (positive potential) in the sine wave signal (detection signal) output from the oscillation circuit 211.

  The second detection circuit 221B includes capacitors C4, C5, C6, a diode D2, and a resistor R2. The diode D2, the capacitor C4, and the resistor R2 are connected in parallel between the second signal line S2 connected to the oscillation circuit 211 and the reference potential. The capacitor C5 and the resistor R2 constitute an integration circuit F2 that detects a second amplitude lower than the reference potential (negative potential) in the sine wave signal output from the oscillation circuit 211.

  The differential amplifier circuit 222 amplifies the difference between the output signal of the first detection circuit 221A and the output signal of the second detection circuit 221B. The differential amplifier circuit 222 includes an operational amplifier OP, resistors R3, R4, R5, and R6, and a bias power source E. The resistor R3 is connected between the first signal line S1 of the detection circuit 221 and the input terminal (non-inverting input terminal) of the operational amplifier OP, and the resistor R4 is connected to the second signal line S2 of the detection circuit 221 and the operational amplifier OP. Is connected to the inverting input terminal of. The resistor R5 is a negative feedback resistor of the operational amplifier OP, and the resistor R6 is connected between the bias power supply E and the input terminal of the operational amplifier OP.

  The binarization circuit 223 includes a comparator that compares the output of the differential amplifier circuit 222 with a predetermined potential. The predetermined potential is set to an appropriate value capable of detecting a change in signal voltage that changes as the rotating blade T approaches the sensor top 10. The binarization circuit 223 outputs the voltage fluctuation accompanying the approach and separation from the sensor top 10 due to the rotation of the rotating blade T as a pulse signal having a frequency corresponding to the number of rotations.

  Also, the binarization circuit 223 is deformed by the waveform deformation circuit 212 when the sensor top 10 fails, and is amplified by the differential amplifier circuit 222. The output waveform (sinusoidal wave) of the oscillation circuit 211 is positive (first potential). ) And a negative potential side (second amplitude), a pulse signal is output as a result when an amplitude difference of a predetermined value or more is detected.

  The frequency dividing circuit 224 divides the output of the binarizing circuit 223 by a predetermined frequency dividing ratio. Thereby, the detection signal corresponding to the rotation speed of the rotating turbine T is obtained. The obtained detection signal is output to an ECU (Electronic Control Unit) 30 to detect the rotational speed of the rotating turbine T. Note that the frequency dividing circuit 224 may be provided in the ECU 30.

  In the detection unit 22 configured as described above, the first detection circuit 221A detects the detection signal output from the oscillation circuit 211 and converts it into a pulse signal having a positive potential, and the second detection circuit 221B The detection signal output from the oscillation circuit 211 is detected and converted to a negative potential pulse signal. The detection signal output from the oscillation circuit 211 is a high-frequency signal that decreases in amplitude when the rotating turbine T approaches the sensor top 10 and increases in amplitude when the rotating turbine T moves away from the sensor top 10. Therefore, when the turbocharger is rotating, the amplitude of the detection signal periodically changes in accordance with the rotational speed of the rotating turbine T. Therefore, the rotating turbine T is supplied via the binarization circuit 223 and the frequency dividing circuit 224. Is output to the ECU 30.

  On the other hand, when the rotation of the rotating turbine T is stopped, the amplitude of the detection signal output from the oscillation circuit 211 does not change. For this reason, since the detection voltage of the detection circuit 221 (the first detection circuit 221A and the second detection circuit 221B) and the output of the differential amplifier circuit 222 are both constant, the output of the binarization circuit 223 (pulse signal) ) Will not be output.

  Next, a detection method for detecting disconnection (failure of the sensor top 10) of the detection coil L1 due to disconnection of the detection coil L1 will be described. 5A to 5C are diagrams schematically illustrating output waveforms of the oscillation circuit 211, the differential amplifier circuit 222, and the binarization circuit 223, respectively.

  When the detection coil L1 is disconnected, the oscillation frequency f0 of the oscillation circuit 211 is lowered and the signal voltage V is increased as described above. For this reason, the oscillation circuit 211 outputs a detection signal in which the peak region of the second amplitude on the negative potential side of the sine wave is clipped by the waveform transformation circuit 212 (see FIG. 5A). The detection circuit 221 detects the first amplitude on the positive potential side of the sine wave and the second amplitude.

  The differential amplifier circuit 222 amplifies the difference between the output signal of the first detection circuit 221A and the output signal of the second detection circuit 221B, and outputs the amplified difference to the binarization circuit 223 (see FIG. 5B). The binarization circuit 223 outputs a pulse waveform signal obtained by extracting a signal component of a predetermined potential (Vref) or higher from the output signal of the differential amplifier circuit 222 (see FIGS. 5B and 5C). The output of the binarization circuit 223 is output to the ECU 30 via the frequency dividing circuit 224. As described above, the oscillation frequency f0 of the oscillation circuit 211 decreases due to the disconnection, and thus the pulse frequency also decreases. Thereby, the ECU 30 can know the failure of the sensor top 10.

  As described above, according to the present embodiment, since the oscillation unit 21 includes the waveform deformation circuit 212, it is possible to distinguish between failure of the sensor top 10 and stop of the turbocharger. Accordingly, an erroneous determination that the turbocharger is not rotating due to a failure of the sensor top 10 is avoided, so that a malfunction or failure of the turbocharger or the engine can be prevented.

  Furthermore, according to the present embodiment, since the failure of the sensor top 10 can be detected from the detection signal of the oscillation circuit 211, it is necessary to separately provide a terminal for outputting the abnormality detection signal of the sensor top 10 in the oscillation unit 21. The normal detection signal and the abnormal detection signal can be output from one output terminal.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, a various change can be added.

  For example, in the above embodiment, the waveform deformation circuit 212 is configured to deform the waveform of the second amplitude lower than the reference potential among the sine wave signals output from the oscillation circuit 211, but is not limited thereto. The first amplitude waveform higher than the reference potential may be deformed. This also makes it possible to form an asymmetric signal waveform with respect to the reference potential for the first signal component and the second signal component, so that the same effect as described above can be obtained.

  Further, the clip circuit constituting the waveform deformation circuit 212 is not limited to the peak clipper, and may be a base clipper. Furthermore, other waveform deformation circuits other than the clip circuit may be employed.

  In the above embodiment, the rotating blade in the turbocharger has been described as an example of the rotational speed detection target. However, the detection target is not limited to this, for example, a rotary blade such as an air cooling fan or a blower fan. May be.

  Further, in the above embodiment, the eddy current sensor has been described as an example of the sensor top 10. However, the sensor top 10 is not limited to this, and may be various sensors having a coil, an antenna, and the like. May be applied.

DESCRIPTION OF SYMBOLS 10 ... Sensor top 20 ... Signal detection apparatus 21 ... Oscillation part 22 ... Detection part 30 ... ECU
DESCRIPTION OF SYMBOLS 100 ... Sensor apparatus 211 ... Oscillation circuit 212 ... Waveform deformation circuit 221 ... Detection circuit 221A ... 1st detection circuit 221B ... 2nd detection circuit 222 ... Differential amplification circuit 223 ... Binarization circuit 224 ... Frequency division circuit L1 ... Detection coil

Claims (4)

A signal processing device connected to a detection coil for signal detection,
An oscillation circuit that outputs a sine wave signal;
A portion of the sine wave signal that is higher than a reference potential is a first amplitude, a portion that is lower than the reference potential is a second amplitude, and the first amplitude and the second amplitude when the detection coil is disconnected. An oscillating unit having a waveform deforming circuit for deforming any one of the waveforms,
A first detection circuit for detecting the first amplitude, a second detection circuit for detecting the second amplitude, an output signal of the first detection circuit, and an output signal of the second detection circuit; A signal processing device comprising: a differential amplification circuit that amplifies the difference between the detection unit and the detection unit. The signal processing device according to claim 1,
The signal processing apparatus, wherein the waveform deformation circuit is a clip circuit. The signal processing device according to claim 1 or 2,
The signal processing apparatus, wherein the detection unit further includes a binarization circuit that binarizes an output of the differential amplifier circuit.   A sensor device comprising the signal processing device according to claim 1.

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