JPH0614087B2 - Sensor signal processor - Google Patents

Description

The present invention relates to a sensor signal such as a rotation speed including a stopped state of an object to be detected by processing a pickup signal from an electromagnetic pickup which constitutes a rotation detection sensor or the like. At the same time, it relates to a sensor signal processing device capable of detecting and processing the occurrence of a failure in the sensor unit.

[Prior Art] For example, as a means for detecting the rotational speed of a rotating body such as an engine, a rotating disk made of a magnetic material having a large number of cutouts in the outer peripheral portion, and an outer peripheral portion of the rotating disk. There is known a rotation detecting sensor constituted by a permanent magnet fixedly set at a position close to and an electromagnetic pickup constituted by a coil wound around the magnet.
That is, the rotating disk is rotated in synchronization with the engine that is the object to be detected, and an electromotive force is generated in the pickup coil each time the notch on the outer periphery of the disk passes near the pickup, and the output voltage is leveled. By discriminating, it becomes possible to obtain a pulsed pickup signal having a period corresponding to the rotation speed. Therefore, the rotation speed of the detected object can be measured by counting this pickup signal.

In the sensor configured as described above, the detection output is at a low level in a state where no output signal is generated from this sensor. This occurs not only when the pickup coil is not rotating but also when the pickup coil is disconnected or short-circuited, and cannot be identified by the level discriminating means. If the pickup coil is broken or short-circuited, an output signal is not obtained from the sensor even if the rotating body starts rotating from a stopped state, and it cannot be discriminated whether or not the rotating body is rotating.

As a means for detecting disconnection of such a pickup sensor, for example, an apparatus as disclosed in Japanese Patent Laid-Open No. 62-112070 is considered.

FIG. 6 shows the configuration of this disconnection detecting device, in which the rotation sensor 31 is a rotating disk 311 which rotates in synchronization with the measured rotating body.
Equipped with. The rotating disk 311 is made of a magnetic material having a plurality of cutouts formed on the outer peripheral surface thereof, and a core 3 made of a permanent magnet is provided at a position close to the outer peripheral surface of the rotating disk 311.
12 is fixedly set. A pickup coil 313 is wound around the core 312 to form an electrode pickup. The pickup coil 31 of the electrode pickup is
An electromotive force is generated in the rotating disk 311 every time the rotating disk 311 rotates and the notch passes near the core 312. That is, a pulsed voltage signal is generated in response to the rotation of the rotary disc 311.

The output signal from the rotation sensor 31 is divided by the resistors R31 and R32 in the comparison circuit 32 to perform level determination with the reference voltage set, and the output signal from the sensor 31 is waveform-shaped. Here, in the pickup coil 313,
The bias voltage is set via the resistor R33.

The output signal from the comparison circuit 32 is amplified by the transistor 33 and then supplied to the comparison circuit 34 via the resistor R34. The signal from the transistor 33 is pulled up by the resistor R35 and compared with the reference voltage divided by the resistors R36 and R37 in the comparison circuit 34. Then, when the output voltage from the transistor 33 is higher than the reference voltage, the output of the comparison circuit 34 is set to the high level.

The output from the comparison circuit 34 is the diode D1 and the resistor R38.
The voltage is supplied to the comparison circuit 35 having the reference voltage set by the resistors R41 and R42 via the charging / discharging circuit composed of R40 and the capacitor C1, and the level is discriminated.

In this sensor signal processing circuit, assuming that the pickup coil 313 of the sensor 31 is broken, the capacitor C1 will continue to be charged, and the terminal voltage of this capacitor C1 will be the reference value set by the resistors R41 and R42. The voltage is exceeded and the output of the comparison circuit 35 is set to the high level. Therefore, the disconnection of the pickup coil 313 can be detected by monitoring the output signal from the comparison circuit 35.

However, when the pickup coil 313 is short-circuited, the rotation sensor 31 outputs the same output signal as the normal rotation speed "0", and the short-circuiting of the pickup coil 313 cannot be determined.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and when the rotation of a rotating body such as an engine is detected by an electromagnetic pickup, the pickup coil of this sensor is disconnected or short-circuited. When this occurs, it can be distinguished from the stop of the rotating body so that the occurrence of disconnection and short circuit faults can be discriminated and detected, so that the reliability of this type of detection mechanism is improved and the usability is improved. The present invention intends to provide a sensor signal processing device.

[Means for Solving the Problems] In the sensor signal processing apparatus according to the present invention, a pickup sensor that obtains a pulse-shaped sensor signal corresponding to the operation of the object to be detected is used. The output signal is amplified and then supplied to the oscillating means. This oscillating means oscillates a signal having a period sufficiently longer than the period of the pulsed signal generated by the pickup sensor in a normal state, and the amplified signal is supplied. In this state, the oscillation of the signal having the period corresponding to the period of the pulsed pickup signal is controlled.
Further, when the rotating body is in a stopped state and when the pickup sensor is disconnected or short-circuited, the output signals from the oscillating means are made constant at different levels corresponding to the levels of the signals applied to the oscillating means. To do so.

[Operation] That is, in the sensor signal processing device as described above, when the object to be detected is operating, the pickup sensor can obtain a pulsed pickup signal having a cycle corresponding to the operating state. A signal having a cycle corresponding to this signal cycle is obtained from the oscillating means. Then, by counting this oscillation signal, the operating speed of the detected object can be measured. Further, when the object to be detected is stopped, the oscillating means is in a self-operating state and oscillates at a frequency corresponding to the condition set by the oscillating means, whereby the normality of the pickup sensor can be determined. Then, in the state where the coil of the pickup sensor has a failure such as a disconnection or a short circuit, the oscillation means responds to the disconnection or the short circuit of the coil,
The maximum voltage or the minimum voltage is applied, and the oscillating means does not oscillate and outputs a signal of a specified level. Therefore, based on the output signal from the oscillating means, it is possible to easily and surely determine whether or not the pickup sensor is in a normal state, particularly whether the pickup coil is broken or short-circuited.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows the circuit configuration of the rotary plate, which is made of a ferromagnetic material with a plurality of notches formed in the outer peripheral portion.
111, a rotation detection sensor 11 including a core 112 made of a permanent magnet fixedly set close to the outer peripheral portion of the rotating plate 111, and a pickup coil 113 wound around the core 112. The rotary plate 111 of the rotation detecting sensor 11 is driven to rotate in synchronization with an object to be detected, which is not shown in this figure, for example, an engine, and with the rotation of the rotary plate 111, a cutout portion of the outer peripheral portion thereof. Each time it passes close to the core 112,
A pulsed voltage signal is generated in the pickup coil 113. The pulse-shaped output voltage signal from the pickup coil 113 has a frequency proportional to the rotation speed of the rotating plate 111, and the output signal frequency represents the rotation speed of the engine, which is the object to be detected. Become.

The output from the rotation detection sensor 11 is supplied to the operational amplifier circuit 12, and the pickup coil 113 of the rotation detection sensor 11 is connected to the power source Vcc via the resistor R01. Output from V
a is supplied to the operational amplifier 121 via the resistor R02. This operational amplifier 121 has an amplification degree of resistors R03 and R04.
The amplification degree α is set as follows, and the output signal Vb is obtained.

α = (R03 + R04) / R03 That is, the rotation detection sensor 11 is normal and the rotation plate 11
When the rotation speed of 1 is “0”, the pickup coil 113
The voltage division obtained by the DC resistance component and the resistor R01 is input to the operational amplifier 121, and the output Vb multiplied by α by this amplifier 121 is obtained as the output of the operational amplifier circuit 12.
Then, this output signal Vb is supplied to the oscillation circuit 13.

The output signal from the operational amplifier circuit 12 is supplied to the comparator 131 via the resistor R05. The output side of the comparator 131 is connected to the input side of the comparator 131 via the resistor R06 so that the oscillation output Vout can be obtained from the output side of the comparator 131.

The oscillator circuit 13 includes a capacitor C charged in series with resistors R07 and R08 connected to a power supply Vcc, and a terminal voltage Vc of the capacitor C is coupled to an inverting side terminal of a comparator 131. The connection point between the resistors R07 and R08 is connected to the output side of the comparator 131 via the diode D so that the discharge circuit of the capacitor C is formed.

Here, the output Vb from the operational amplifier 121 is higher than the voltage VF obtained at the side of the diode D when the output of the comparator 131 is at a low level, so that the resistors R03 and R3 are provided.
Determine the value of 04.

A transistor 141 is connected in parallel to the capacitor C that constitutes the oscillator circuit 13. This transistor 141 constitutes the limit circuit 14, and its base has a resistor R09.
And the voltage divided by R10 is supplied.

In the limiter circuit 14, Vb from the operational amplifier 121 is
When a high voltage state close to the power supply voltage Vcc is reached, the terminal voltage Vc of the capacitor C becomes the output voltage Vb of the operational amplifier 121.
The values of the resistors R09 and R10 are set so that the voltage does not exceed the value.

In the oscillating circuit 13, when the output Vout of the comparator 131 becomes low level, the charge Vc of the capacitor C is discharged to the output side of the comparator 131 via the resistor R08 and the diode D, and this discharge is It continues until the electric charge Vc of the capacitor C becomes lower than the voltage Vb 'on the input side of the comparator 131, and when Vc becomes lower than Vb', the comparator 131 operates and its output Vout is inverted to the high level. And
When the output Vout of the comparator 131 becomes high level, the capacitor C is charged via the resistors R07 and R08.

Oscillation is performed by repeating such a series of operations, and the frequency F of the oscillation signal thus obtained is sufficiently higher than the frequency of the panel-shaped rotation signal obtained by the normal rotation detection sensor 11. As the lower frequencies,
The values of capacitor C and resistors R07 and R08 are determined.

The operation of the device configured as described above will be described. First, in the state where the rotation detection sensor 11 is operating normally, the rotating plate 111 is smoothly rotating in response to the rotation of the detected object. Then, as shown in FIG. 2 (A), the notch of the pickup coil 113 corresponding to the rotation of the rotary plate 111 changes periodically every time the notch passes near the core 112. An electromotive force is generated, and a signal Va that changes periodically is generated. This signal Va is the operational amplifier 12
A signal Vb which is amplified α times by 1 and periodically changes is obtained as shown in FIG.

Here, the oscillation frequency obtained under the oscillation condition of the oscillation circuit 12 is set sufficiently smaller than the frequency of the signal Vb generated when the rotary plate 111 is rotated in a normal state. . Therefore, a change in the output Vb of the operational amplifier 121 occurs at a sufficiently fast cycle as compared with a change in the voltage of the capacitor C terminal, and the output Vout of the comparator 131 has a frequency synchronized with the frequency of the output Vb of the operational amplifier 121. Output voltage.

That is, the output Vb of the operational amplifier 121 changes periodically, so that the output Vout of the comparator 131 changes in a rectangular wave shape between the high level and the low level, and the frequency of the rectangular wave is detected as rotation detection. It matches the frequency of the signal Va obtained from the sensor 11, and the rotational speed of the rotary plate 111, that is, the rotational speed of the detected object is measured based on the output Vout of the comparator 121.

Next, when the rotation detection sensor 11 is normal, but the rotation plate 111 is in a stopped state, that is, when the detected body is in a stopped state, consider FIG. 2B. As shown, the output Va from the sensor 11 is kept at a constant value. That is, this voltage Va becomes a voltage division between the DC resistance component of the pickup coil 113 and the resistor R01, and this voltage Va is multiplied by α in the arithmetic width unit 121 to obtain Vb. This voltage Vb is higher than the anode voltage FVF of the diode D obtained when the output of the comparator 131 is at the low level as described above, so that when the output of the comparator 131 is at the high level, the capacitor C becomes It is charged via resistors R07 and R08. When the charging voltage Vc of the capacitor C exceeds the voltage Vb 'on the input side of the comparator 131, the output Vout of the comparator 131 becomes low level.
Here, Vb ′ = {R05 / (R05 + R06)} × (Vout−Vb) When the output of the comparator 131 becomes low level, the capacitor C
Is charged to the output side of the comparator 131 via the resistor R08 and the diode D, and the terminal voltage Vc of the capacitor C becomes the voltage Vc.
When it goes below b ', the output Vout of the comparator 131 becomes high level. Then, the charging of the capacitor C is started again, and by repeating this, the continuous state of oscillation is maintained.

That is, when the rotation detection sensor 11 is in a normal state, the rotation plate 111 is rotated while the rotation plate 111 is rotating.
When the rotating plate 111 is stopped, the oscillation circuit 13 oscillates under the condition set by itself, and the rectangular wave output having the frequency corresponding to the oscillation frequency is obtained. Output is obtained.

Considering the case where the pickup coil 113 of the rotation detection sensor 11 is broken, as shown in FIG. 2C, the terminal voltage Va of the pickup coil 113 is almost equal to the power supply voltage by the power supply given through the resistor R01. It is set to Vcc. Therefore, the operational amplifier 121 tries to output Vb that is α times this Va, but this Vb is Vcc.
It can never be higher.

If “Vb≈Vcc” is set here, “Vb ′ = Vb” is established and the capacitor C is charged when the output of the comparator 131 is at a high level. However, the terminal voltage Vc of the capacitor C does not exceed the voltage determined by the limit circuit 14, and the terminal voltage Vc cannot exceed the voltage Vb 'on the input side of the comparator 131. Therefore, the output Vout of the comparator 131 maintains a high level state.

Next, considering a case where the pickup coil 113 of the rotation detection sensor 11 is short-circuited, the impedance of the pickup coil 113 is “0” as shown in FIG.
Therefore, the terminal voltage Va of the pickup coil 113 becomes “0V”, and the output V of the operational amplifier 121 becomes V.
b also becomes "0V". Therefore, in this state, the comparator 13
When the output of 1 is low level, the capacitor C has a resistance R0.
8 and diode D. However, the terminal voltage Vc of the capacitor C does not drop below the voltage drop of the diode D.

That is, since Vb is "0V" and the output Vout of the comparison circuit 131 is low level (0V), the input voltage Vb 'of the comparison circuit 131 is also "0V", and the terminal voltage V of the capacitor C
c does not fall below the input Vb 'of the comparator 131, and its output Vout maintains a low level state.

Therefore, the pickup coil 11 of the rotation detection sensor 11
In the state where 3 is disconnected, the output Vout is maintained at the high level, and when short-circuited, Vout is maintained at the low level. Then, the rotation detection sensor 11
In the normal operating state, when there is no rotation, the output Vout corresponding to the internal oscillation signal of the oscillation circuit 13 is obtained,
When there is rotation, an oscillation signal having a cycle corresponding to the rotation speed is obtained as the output Vout.

The output Vout from the oscillator circuit 13 is appropriately supplied to a control circuit 14 formed of a microcomputer or the like, and in this control circuit, the same voltage is supplied for a time longer than one cycle of the internal oscillation signal frequency obtained by the oscillator circuit 13. If the means for determining whether or not the state is set, the output Vou of the oscillation circuit 13 is set.
The abnormality of the rotation detection sensor 11 is detected by determining that t has been maintained in the same state for the specified time or longer. Then, in this abnormality detection state, the output Vout
By determining the level of the pickup coil
It becomes possible to determine 113 disconnection or short circuit.

Further, when it is determined that the output Vout is not kept in the same state in the specified time range, the rotation detection sensor 11
Is operating normally. In this normal operating state, it is determined whether the oscillation cycle of the output Vout from the oscillation circuit 13 is higher than the internal oscillation frequency of the oscillation circuit 13. With this, it is possible to determine the rotational operating state or the stopped state of the detected object, and when it is determined to be the operating state, the rotation speed of the rotated object is measured by counting the cycle of Vout. Become.

In the control circuit 15, along with the determination operation as described above,
If a predetermined abnormality control mode is set in a state where the abnormality of the sensor 11 is discriminated, a dangerous control state can be effectively avoided when the sensor is abnormal.

In the above embodiment, the sensor 11 provided in the oscillation circuit 13
The lower limit setting diode D that operates when the short circuit is detected, and the upper limit voltage setting limit circuit 14 that operates when the sensor 11 is disconnected are used.

FIG. 3 shows an embodiment constructed without using such limit means. The control circuit 21 composed of a digital processing circuit such as a microcomputer causes the coil 113 of the rotation detection sensor 11 to be disconnected or short-circuited. I am trying to detect.

That is, in this device, the detection signal obtained by the rotation detection sensor 11 is amplified by the operational amplifier 121 as in the previous embodiment, and the operational amplification output is supplied to the comparison circuit 22. The comparison circuit 22 determines the level of the output from the operational amplifier 121 based on the voltage Vg divided by the resistors R21 and R22, and supplies the determination result to the input terminal 211 of the control circuit 21. In the control circuit 21, the signal input from the terminal 211 determines whether or not the frequency is equal to or higher than a predetermined frequency, and determines the rotation stop state of the rotation detection sensor 11. When the rotation stop state is determined, , Output terminal 212
After that, the output signal is set to the low level for a predetermined time T1 to control the transistor 23 in the ON state. This transistor
A resistor R23 is connected in series to 23, and this transistor 23
The resistor R23 is connected in parallel with the resistor R21 in the ON state of.

After the signal having the low level for the time T1 is output in this manner, the output terminal 213 of the control circuit 21 is subsequently set to the high level for the predetermined time T2, and the transistor 24 is turned on. This transistor 24 has a resistor R
24 are connected in series, and the resistor R24 is connected in parallel to the resistor R22 when the transistor 24 is on.

That is, the control circuit 21 has a built-in oscillating circuit that oscillates a signal having a cycle set at the times T1 and T2. The output from the comparison circuit 22 remains unchanged for a predetermined time or longer, and the transistors 23 and 24 is reciprocally controlled on / off.

In this device, when the rotation detection sensor 11 is in the normal state and is rotating, the output of the operational amplifier 121 changes without regard to the cycles T1 and T2, and the comparison is made correspondingly. The output of circuit 22 changes. Then, when the sensor 11 is normal and is in a stopped state, and further, when the rotation detection sensor 11 has a disconnection or a short circuit abnormality, the output from the comparison circuit 22 is as shown in FIG. The operation state is as follows.

First, when the rotation detection sensor 11 is in a normal state and is rotating, as shown in FIG.
A signal having a period corresponding to the rotation speed is generated from 1, a rectangular signal is generated from the comparison circuit 22 in a state of being synchronized with the signal which changes the period, and this signal is supplied to the control circuit 21. Therefore, in the control circuit 21, the transistors 23 and 24
Is not on-controlled, and the comparison reference voltage set in the comparison circuit 22 is kept constant.

When the rotation is stopped in such a normal state, the comparison circuit 22
The output of the control circuit 21 does not change, the output terminal of the control circuit 21 outputs a signal that is at the low level for the time T1, the transistor 23 is turned on, and the resistor R23 is turned on.
Are connected in parallel. Therefore, the reference voltage V of the comparison circuit 22
Since g becomes high, the level of this voltage and the voltage from the operational amplifier 121 are discriminated. Then, after the lapse of the time T1, the output terminal 213 is set to the high level for the time T2, the transistor 24 is turned on, and the resistor R22 is connected in parallel with the resistor R22. Then, the reference voltage Vg is set low.

Here, the values of the resistors R21 and R22 are set such that they are at the center of the peak value of the output obtained when the sensor 11 is normal, and the resistor R23 is connected in parallel with the resistor R21. The resistance value is set so as to obtain a reference voltage Vg that is larger than the maximum value of the peak value of the output obtained when the sensor 11 is normal and lower than the output voltage obtained when the sensor 11 is disconnected. In addition, the resistance R22
When 24 is connected in parallel, the resistance of the sensor 11 is set so that a reference voltage Vg lower than the peak value of the output obtained when the sensor 11 is normal and higher than the output voltage obtained when the sensor 11 is short-circuited is obtained. The value is set.

Therefore, when the sensor 11 is in the normal state and is in the stopped state, the comparison circuit 22 outputs the fifth signal from the comparison circuit 22 between T1 and T2.
As shown in the figure, it changes to high level and low level. Then, when the sensor 11 is short-circuited, the inputs of the comparison circuit 22 are both low during T1 and T2, and the outputs of the comparison circuit 22 are both at low level. Then, in the state where the sensor 11 is disconnected, the output from the comparison circuit 22 becomes high level during both T1 and T2, and the fourth
The logic shown in the figure comes to hold.

Therefore, by discriminating this logic in the control circuit 21, it becomes possible to discriminate the normal state of the rotation detecting sensor 11 and the abnormal state of disconnection or short circuit.

[Effects of the Invention] As described above, according to the sensor signal processing device of the present invention, the pickup sensor is in a normal state, when the detected object is in an operating state or in a stopped state. Also, a pulsed oscillation signal of a predetermined period or more can be obtained, and the normal state of the sensor can be clearly determined. If the sensor pickup coil is disconnected or short-circuited in an abnormal state, a signal of a level corresponding to the content of the abnormal state can be obtained. The determination can be made easily and surely on the basis of the above, and the reliability and handleability of this type of measuring device are significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration diagram for explaining a sensor signal processing device according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining an operating state in each mode of the device. FIG. 3 is a signal waveform diagram, FIG. 3 is a circuit configuration diagram for explaining another embodiment of the present invention, FIG. 4 is a diagram showing a logical relationship for judging an operating state of this embodiment, and FIG. Signal waveform diagram to explain,
FIG. 6 is a circuit configuration diagram illustrating a conventional sensor signal processing device. 11 ... Rotation detection sensor, 111 ... Rotating plate, 112 ... Core (ferromagnetic material), 113 ... Pickup coil, 12 ... Operational amplifier circuit, 13 ... Oscillation circuit, 131 ... Comparator, 14 ... …
Limit circuit, C ... Capacitor.

Claims (4)

[Claims] 1. A pickup sensor for generating a pulsed pickup signal in response to an operation of an object to be detected, and an amplification means for amplifying a sensor signal corresponding to a potential difference between both ends of a pickup coil constituting the pickup sensor. An oscillating unit that oscillates at a period sufficiently longer than the period of a pickup signal obtained from the pickup sensor in the operating state of the object to be detected, and the output signal from the amplifying unit is supplied to the oscillating unit. The oscillating means is adapted to obtain an oscillating output corresponding to the output signal from the amplifying means corresponding to the pickup signal having a cycle sufficiently shorter than the oscillating signal cycle, and the output signal from the amplifying means is maximum. In the state or the minimum state, the oscillation signal of the oscillation means is stopped. Processing apparatus. 2. The oscillating means includes a capacitor and a charging / discharging circuit for the capacitor, and the capacitor is controlled to be charged and discharged based on a pulsed output signal from the amplifying means. The capacitor is provided with limit means for preventing its terminal voltage from being charged to a voltage higher than the maximum output from the amplifier means and from being discharged to a voltage lower than the minimum output from the amplifier means. The sensor signal processing device according to claim 1. 3. The sensor signal processing apparatus according to claim 2, wherein the output of the amplifying means is set to the maximum voltage state when the pickup coil is disconnected, and is set to the minimum voltage state when the pickup coil is short-circuited. . 4. The output from the amplifying means is supplied to a comparing means to which a specified reference voltage is set, and the output signal from the comparing means is supplied to a digital processing circuit. Along with the oscillation means, a stop determination means for determining that the output signal from the comparison means is equal to or less than a specified frequency is configured, and in the oscillation cycle of the oscillation means in the stop determination state by the stop determination means. Correspondingly, the reference voltage of the comparison means is set to be switched to a state higher than the maximum voltage or lower than the minimum voltage of the output of the amplification means generated by the disconnection or short circuit of the pickup coil.
Sensor signal processor.