JP2745089B2 - Setting method of threshold voltage for G signal detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of setting a threshold voltage for detecting a G signal, and more particularly, to a method of setting a toothless type N.
The present invention relates to a method for setting a G signal detection threshold voltage by converting a NE signal output from an E sensor from a frequency to a voltage to obtain a G signal detection threshold voltage.

[0002]

2. Description of the Related Art A toothless NE sensor detects the number of rotations and the rotation angle of a crankshaft of an engine, and has a shape as shown in FIG. 5, for example. FIG. 5 shows a chipped tooth N
The E sensor 50 is shown, and the missing tooth type NE sensor 50 includes a uniform tooth part 50a and a missing tooth part 50b. For example, 34 teeth 51 are uniformly attached to the uniform tooth portion 50a at intervals of 10 °, and no teeth 51 are attached to the missing tooth portion 50b. The interval between the missing tooth portions 50b is equivalent to 30 ° in terms of the central angle, and is equivalent to two teeth forming the uniform tooth portion 50a in terms of the number of teeth. Missing tooth type N
The E sensor 50 makes one rotation at a rotation angle of 360 ° of the crankshaft, and can detect the top dead center of the crankshaft at the missing tooth portion 50b.

[0003] Chipped NE sensor 50 having the above configuration
The NE signal output from the above has an output waveform as shown in FIG. In FIG. 6A, P1 and P3 indicate pulse waveforms output from the uniform tooth portion 50a, and P2 indicates a waveform output from the toothless portion 50b. Since pulses are generated every 10 ° from the uniform tooth portion 50a,
By measuring the pulse, the rotation angle of the crankshaft can be accurately detected. In addition, FIG.
FIG. 7 shows the result of frequency-voltage conversion of the NE signal shown in FIG. The description will be given later.

However, since the four-cylinder engine has one cycle with two rotations of the crankshaft (720 °), the toothless portion 5
Even if the top dead center of the crankshaft can be detected at 0b, the compression top dead center and the top dead center at the time of exhaustion are missing and cannot be distinguished by the tooth type NE sensor 50. Therefore, in order to determine the cylinder at the compression top dead center, a G sensor (reference position sensor) that generates a signal once with two rotations of the crankshaft is missing tooth type N
Used together with E sensor.

[0005]

The signal level (reference position discrimination) output from the G sensor varies depending on the engine speed. That is, when the engine speed is high, the signal level output from the G sensor is high, and when the engine speed is low, the signal level output from the G sensor is low. Therefore, it is necessary to set the threshold voltage for G signal detection to be high when the engine is running at a high speed and to be low when the engine is running at a low speed.

In order to set the G signal detection threshold voltage as described above, an all-tooth NE sensor (NE having an equal tooth every 30 °) which is generally used as a sensor for detecting the rotation angle of the crankshaft is used. Sensor), the NE signal output from the all-tooth NE sensor is frequency-to-voltage converted, and the threshold voltage for G signal detection is set / changed based on the voltage value obtained thereby. By doing so, it is possible to set and change the threshold voltage for G signal detection in accordance with the engine speed (FIG. 7). In FIG. 7, the vertical axis represents the threshold voltage (mV) for G signal detection, and the horizontal axis represents the engine speed (r
pm). When the threshold voltage for G signal detection is set or changed as shown in FIG. 7, especially when the engine is running at a high speed, the output level of the G signal is sufficiently high, so that the threshold voltage for G signal detection is also set to a high value, thereby causing erroneous detection due to noise. Can be prevented.

However, if the above-described method of setting and changing the threshold voltage for G detection is directly applied to the toothless NE sensor, the voltage drops at the toothless part P2 as shown in FIG. 6B. FIG. 6B shows the detection of a falling edge (a downward arrow shown in FIG. 6A) of the NE (pulse) signal output from the toothless NE sensor.
7 is a waveform showing a result of frequency-voltage conversion of the NE signal.

The toothless type NE sensor can detect the rotation angle of the crankshaft every 10 ° as compared with a generally used full tooth type NE sensor.
0b has the advantage that the top dead center of the crankshaft can be detected. However, if the NE signal output from the toothless NE sensor is directly subjected to frequency-voltage conversion in order to obtain a G signal detection threshold voltage as shown in FIG. There is a problem that voltage disturbance occurs at the tooth portion P2.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a method of setting a threshold voltage for detecting a G signal in which voltage disturbance does not occur even in a missing tooth portion.

[0010]

In order to achieve the above object, a method of setting a threshold voltage for detecting a G signal according to the present invention is to output an NE signal using a toothless type NE sensor including a toothless part. , And subject the NE signal to waveform processing to obtain G
A method for setting a threshold voltage for detecting a G signal for outputting a threshold voltage for detecting a signal, the method comprising:
The signal is divided based on the gap between the missing teeth , and
The apparatus is characterized in that the threshold voltage is output based on the divided NE signal so as not to be affected by the teeth .

[0011]

In the method of setting the threshold voltage for detecting a G signal according to the present invention, the frequency of the NE signal output from the toothless type NE sensor including the toothless part is divided based on the interval between the toothless parts, and the chipping is performed. The threshold voltage is output based on the frequency-divided NE signal so as not to be affected by the teeth . Hereinafter, the principle of the determination of the missing tooth portion and the (1/3) frequency division will be described with reference to FIGS.

In FIG. 4, (a) shows the NE signal output from the missing tooth NE sensor (FIG. 5), (b) shows the missing tooth detection signal, and (c) divides the frequency of the NE signal by one third. FIG. 7D shows the NE12 signal generated by the above-described operation, and FIG. 7D shows a voltage waveform obtained as a result of frequency-voltage conversion of the NE12 signal.

First, a method of generating the missing tooth detection signal of (b) from the NE signal of (a) will be described. In FIG. 7A, a portion where the periodic pulse waveform is broken indicates a missing tooth portion (arrow A), and the missing tooth portion A is detected by the ratio of the previous signal period to the current signal period. Further, the signal periods Ta, T
“b” shows the measured time from the fall of the NE signal (downward arrow shown in the figure) to the fall. As described in the description of FIG. 5, the toothless type N
The uniform tooth portion 50a of the E sensor 50 is a portion where the teeth 51 are evenly attached at intervals of 10 °, and the missing tooth portion 50b has one tooth.
This is a portion where two teeth 51 attached at 0 ° intervals are missing. In other words, in FIG.
The rotation angle of the sensor 50 indicates 10 °, and Tb is 3
0 ° is shown. Therefore, the value K of Tb / Ta is theoretically 3. However, in reality, the signal periods Ta and Tb also fluctuate due to fluctuations in the number of revolutions of the engine.
Is in the range of 2 to 2.8, it is determined to be a missing tooth portion. If it is determined by the above method that the tooth is missing, a missing tooth detection signal shown in FIG.

After the missing tooth detection signal is output, when the falling edge of the first pulse output from the missing tooth NE sensor is detected, the frequency dividing counter is reset. At the same time when the counter is reset, NE
12 pulses B are output. Thereafter, if 1/3 frequency dividing the pulse output from the even teeth 50a based on NE12 pulse B, equal pulse signal with 30゜Go shown in (c) FIG., Namely toothless portion 50b Under the influence of
A missing pulse signal NE12 is produced. NE1
When the two signals are subjected to frequency-voltage conversion, voltage disturbance does not occur even if the missing tooth portion A exists as shown in FIG.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a method for setting a threshold voltage for detecting a G signal according to the present invention. FIG. 1 is a block diagram schematically showing a circuit for setting a threshold voltage for G signal detection according to the embodiment. Note that components having the same functions as those of the conventional example are denoted by the same reference numerals.

In FIG. 1, reference numeral 10 denotes a cam position.
The cam position sensor 10 includes a toothless NE sensor 50 and an NE pickup coil 13, and a G sensor 12 and a G pickup coil 14. One end of the NE pickup coil 13 is connected to the inverter 15 in the control unit 20 via the NE terminal, and one end of the G pickup coil 14 is connected to the inside of the control unit 20 via the G terminal. It is connected to the threshold variable waveform processing circuit 18. NE Pickup Coil 13 and G
The other ends of the pickup coil 14 are respectively
It is connected to the NE- terminal and the G- terminal, and is grounded in the control unit 20.

In the control unit 20, the inverter 15 is connected to a waveform processing circuit 16, and the waveform processing circuit 16 is connected to a frequency-voltage conversion circuit 17 and a control circuit (not shown). The frequency-voltage conversion circuit 17 is connected to a threshold variable waveform processing circuit 18, and the threshold variable waveform processing circuit 18 is connected to a control circuit (not shown).

In the above configuration, the threshold voltage for G signal detection is set as follows. Missing tooth type N
The E sensor 50 makes one rotation at a rotation angle of the crankshaft of 360 °, and outputs the NE signal shown in FIG. On the other hand, the G sensor 12 makes one rotation at a crankshaft rotation angle of 720 ° to generate a signal once.

As the toothless NE sensor 50 rotates, the amount of magnetic flux passing through the NE pickup coil 13 changes, and a voltage corresponding to the change is generated at both ends of the NE pickup coil 13. . The generated voltage is input to the waveform processing circuit 16 as an NE 36 signal (FIG. 4A) via the inverter 15. When the G sensor 12 rotates, a voltage is generated across the G pickup coil 14 as described above, and the generated voltage is input to the threshold variable waveform processing circuit 18 as a G signal.

The NE36 signal is output from the waveform processing circuit 16 as 1
N divided by / 3 and not affected by the missing tooth portion 50b
It is output as an E12 signal. The NE12 signal output from the waveform processing circuit 16 is input to a frequency-voltage conversion circuit 17 and also to a control circuit (not shown). The NE12 signal is frequency-to-voltage converted by the frequency-voltage conversion circuit 17, and the converted result is output to the threshold variable waveform processing circuit 18. The threshold variable waveform processing circuit 18 sets and changes the threshold voltage for G signal detection according to the input level of the G signal.

FIG. 2 shows NE performed by the waveform processing circuit 16.
This shows a method for determining a missing tooth portion of 36 signals. The determination of the missing tooth portion is made up of two counters and 2 not shown.
This is performed using different types of clocks (first and second clocks). Note that the cycle of the second clock is a predetermined multiple (determination value) of the cycle of the first clock. FIG. 2A shows N
An E36 signal is shown, T1 represents the period immediately before the missing tooth portion, and T2 represents the period of the missing tooth portion. (B) shows the output waveform of the U / D counter (1), and (c) shows the output waveform of the U / D counter (2).

In FIG. 2B, when the edge of the NE36 pulse is input, the counter starts falling when the counter is in the rising process, and is reset ("0" level) and then rises in the falling process. start. By the way, as can be seen from the diagram (b), the rising and falling slopes of the counter are kept at a constant value, so the difference between the rising and falling slopes is k, and if this k is used, the following equation is obtained. The missing tooth portion can be determined.

KT1−T2 <0 This equation means that if T2 is greater than k times T1, the output of the counter is always maintained at “0” level for a certain period of T2. Partial tooth type N of the embodiment
In the E sensor 50, T1 indicates a rotation angle of 10 °, and T2
Indicates a rotation angle of 30 °, and the value of k is theoretically set to 3. However, in practice, the values of T1 and T2 also change due to fluctuations in the rotation of the engine and the like, so the determination value k is usually set to about 2 to 2.8. Thus, if there is a period during which the output of the counter is maintained at the “0” level, the period including that period is longer than k (judgment value) times the immediately preceding period. Can be determined.

The U / D counter 1 and the U / D counter 2 play a complementary role, and one of the counters can always determine the missing tooth portion.

FIG. 3 shows a method of outputting a missing tooth detection signal based on the determination of the missing tooth portion and dividing the NE36 signal by １ ／. In FIG. 3, (a) shows NE3
6, (b) shows a missing tooth detection signal, (c) shows a set state of a ３ frequency divider counter, and (d) shows an NE12 signal.

The control for dividing the NE36 signal to generate the NE12 signal is performed as follows.

First, a missing tooth portion is determined by the method shown in FIG. 2, and if it is determined that the missing tooth portion, a missing tooth detection signal (g) is output. When the missing tooth detection signal (g) is output, the 1/3 frequency dividing counter is set to "2". When the NE36 pulse is input while the 1/3 frequency dividing counter is set to "2", the counter is cleared to "0" and at the same time, the NE12 pulse (h)
Is output. When the NE36 pulse is input when the counter is “0” or “1”, the counter is incremented by +1.
However, the NE12 pulse is not output. As a result, the NE36 pulse is frequency-divided by ３, and an equivalent signal NE12 as shown in FIG. 3D is created.

As described above, in the embodiment, the NE36 signal is frequency-divided by 1/3 in the waveform processing circuit 16 to generate an equal signal NE12, and the NE12 signal is converted by the frequency-voltage conversion circuit 17 into the frequency-voltage conversion circuit 17. Then, the threshold voltage for G signal detection is set. As a result, a threshold voltage for G signal detection can be obtained in which the voltage is not disturbed in the missing tooth portion 50b even if the missing tooth type NE sensor 50 is used.

[0029]

As described above in detail, the method of setting the threshold voltage for detecting a G signal according to the present invention includes a missing tooth portion.
The NE signal is output using a chipped tooth type NE sensor,
In a method of setting a threshold voltage for G signal detection in which a waveform process is performed on the NE signal to output a threshold voltage for G signal detection, the NE signal may be used to generate a threshold voltage for G signal detection .
Divided based on the interval, not affected by the missing tooth
And so, since it is characterized in that for outputting the threshold voltage and the frequency-divided NE signal on the basis of the disturbance voltage does not occur in the toothless portion be used NE sensor missing tooth formula G The signal detection threshold voltage can be set.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a circuit for setting a G signal detection threshold voltage according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing a method of detecting a missing tooth portion in an NE36 signal, wherein FIG. 2A shows an NE36 signal, and FIG.
The output waveform of the counter (1) and (c) show the output waveform of the U / D counter (2).

3A and 3B are diagrams showing a method of dividing the NE36 signal by 1/3, wherein FIG. 3A shows the NE36 signal, FIG. 3B shows the missing tooth detection signal, and FIG. 3C shows the set state of the 1/3 dividing counter. , (D)
Indicates the NE12 signal.

FIGS. 4A and 4B are diagrams used to explain the principle of detection of a missing tooth portion and 1/3 frequency division of the NE36 signal, where FIG. 4A shows the NE signal output from the missing tooth NE sensor, and FIG. FIG. 4 is a schematic waveform diagram showing a result of frequency-to-voltage conversion of the NE12 signal, FIG.

FIG. 5 is a schematic view showing a toothless NE sensor.

FIG. 6 (a) shows N output from a toothless NE sensor;
FIG. 9B is a schematic waveform diagram showing a result of frequency-voltage conversion of the NE signal, and FIG.

FIG. 7 is a graph schematically showing a relationship between a G signal detection threshold voltage and an engine speed;

[Description of sign]

 12 G sensor 16 Waveform processing circuit 17 Frequency-voltage conversion circuit 18 Threshold variable waveform processing circuit 50 Missing NE sensor

Claims (1)

(57) [Claims] A G signal for outputting a NE signal using a toothless NE sensor including a toothless portion , subjecting the NE signal to waveform processing, and outputting a threshold voltage for G signal detection.
In the method for setting a threshold voltage for signal detection, the frequency of the NE signal is divided based on an interval between the missing teeth , and
A method of setting a threshold voltage for detecting a G signal, wherein the threshold voltage is output based on the frequency-divided NE signal so as not to be affected by a notched tooth portion .