JPH0943262A - Detector for number-of-revolutions - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately count the number of pulses in a low speed rotating range wrong counting due to noise by providing means for detecting the number of revolutions based on the compared results of first and second comparing means in the first and second comparing means. SOLUTION: The output of a sensor is input in parallel to first and second comparators 21, 22. The comparator 21 compares the input with a reference signal VR1, and outputs (falls) 'L' if it is high. The polarity of the signal VR1 is inverted by this output, the 'L' is continued until it becomes -VR1, and when it becomes lower, 'H' is output (raised). Similarly, the 'H' is continued until the input exceeds VR1, and 'L' is output (falls) if the input exceeds it. The comparator 22 similarly compares the input with a reference signal VR2, and pulse converts it. As a result, the output due to the noise component in the output of the comparator 21 is removed, and since the drop of the voltage VR2 due to the abrupt fall of the number of revolutions does not occur, it is judged to be valid if the corresponding output is not produced from the comparator 22, and the number of revolutions is calculated, and hence the reliability of the apparatus is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation number detecting device for detecting the number of revolutions by counting the number of pulses output corresponding to the number of revolutions.
The present invention relates to a rotation speed detection device that prevents miscounting due to noise.

[0002]

2. Description of the Related Art FIG. 5 is a system configuration diagram of a conventional rotation speed detecting device. FIG. 6 is a waveform diagram of a pulse counter of a conventional rotation speed detection device, where (a) is an input signal and (b) is a comparator output signal. Hereinafter, description will be given with reference to the drawings. Reference numeral 1 denotes a sensor connected to a rotating shaft or the like, which outputs a sine wave having a period and a wave height corresponding to the rotation speed as shown in FIG. Reference numeral 2 is a comparator for comparing the sine wave output from the sensor with a reference voltage VR2, and outputs a portion where the wave height of the sine wave is greater than a certain threshold value VR2 as a square wave pulse. Reference numeral 4 is a counter for counting the number of pulses shaped into a square wave.

Next, the operation will be described. The output from the sensor 1 (sine wave in FIG. 6A) is input to the comparator 2. The comparator 2 compares the input signal with the reference signal VR2 and outputs L if it is higher. Since the polarity of the reference signal VR2 is inverted (-VR2) by the output of the comparator 2, L continues until the input signal becomes below -VR2,
When it is below -VR2, H is output. Similarly, H continues until the input signal exceeds VR2, and L is output when VR2 exceeds VR2. The output from the sensor 1 has a high wave height when the rotation speed is high and the sine wave has a high frequency (short cycle), and has a low wave height when the rotation speed is low and the sine wave has a low frequency (long cycle).
Therefore, in order to reduce erroneous shaping due to noise during waveform shaping, the threshold value V when the output voltage in the low rotation range is low
The threshold of the comparator 2 is changed so that R is set low and the threshold VR2 when the output voltage in the high rotation range is high is set high. Then, the number of pulses is counted by converting into a square wave as shown in FIG. 6B, and the number of revolutions (or the number of pulses per unit time is counted to calculate the rotational speed).

[0004]

In the conventional method, in order to remove the noise superimposed on the sine wave, the reference voltage to be compared by the comparator 2, that is, the threshold value, is at high speed rotation (the wave height of the output signal is high). It is set to change according to the wave height of the output signal such that it becomes high (threshold VR2) and becomes low (lowest threshold VR) at low speed rotation (the wave height of the output signal is low). However, when the rotation speed rapidly decreases from the high speed rotation, the threshold value VR2 cannot follow the decrease in the rotation speed (it must decrease to the threshold value VR). Therefore, the threshold value remains high even in the low rotation speed range, and no pulse is output from the comparator 2 in the low rotation speed range (see FIG. 6).
Due to the arrow (b), there is a problem that accurate waveform shaping cannot be performed and an error occurs in the detection of the rotation speed. That is, it is difficult to eliminate both the influence of noise and the reliable pulse conversion in the low rotation range.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problem, to eliminate a false count due to noise, and to provide a rotation speed detecting device which can surely perform pulse shaping in a low speed rotation range.

[0006]

In order to achieve the above object, the present invention provides a sensor for outputting sine wave signals having different magnitudes and frequencies corresponding to the number of revolutions of an object to be detected, and a sine wave from the sensor. A rotation speed detecting device for detecting a rotation speed of the detection object by counting the number of pulses of the pulse signal converted by the pulse conversion means, wherein the sine wave is provided. Second comparing means for comparing the signal with a second reference signal that varies in accordance with the magnitude of the sine wave signal, and the sine wave signal is at least absolute than a minimum value of the second reference signal. Based on the comparison results of the first comparison means for comparing the first reference signal level which is relatively low and the first and second comparison means,
And a processing unit for detecting the number of rotations of the detected object.

The first and second comparing means have positive and negative binary values with respect to the first and second reference signals, respectively, and the sine wave signal is the first and second positive signals. When the state changes from a state lower than the reference signal having a value of to a state higher than the reference signal, the first and second comparing means output the rising or falling of the pulse, and the sine wave signal outputs the first and second negative signals. The first and second comparing means outputs the trailing edge or the leading edge of the pulse when the value changes from a value higher than the reference signal to a value lower than the reference signal, and the processing means includes the first comparing means. When the rising or falling output from the first comparing means is detected and the rising or falling output from the second comparing means corresponding to the output is not detected, the past rising or rising of the first comparing means is detected. Based on the state of the output of the downlink, the first comparison hand The output from is characterized in that in order to detect the rotational speed of invalid or the object to be detected and determined to be valid.

In the rising or falling output from the first comparing means, when the output interval B from the present time to the previous time becomes smaller than the output interval A from the previous time to the last time before, the processing means may: This is characterized in that the rising or falling output this time is judged to be invalid. Further, the processing means, when the output interval C from the present time to the previous time is larger than the output interval D from the last time to the last two times, of the rising or falling outputs from the first comparing means, the present rising time. Alternatively, the output of the trailing edge is determined to be valid.

The processing means includes the first and second processing means.
Interrupting processing is performed according to the pulse output respectively output from the comparing means, and first and second inhibiting means for inhibiting the interrupt processing when the rotation speed is detected by corresponding the data of each pulse output. The first inhibiting means inhibits the interrupt processing after the interrupt processing corresponding to the pulse output from the first comparing means, and the second inhibiting means includes the pulse from the second comparing means. After interrupt processing corresponding to output, disable the interrupt processing,
It is characterized in that the inhibition of each interrupt process is divided.

[0010]

A first comparing means for comparing a sine wave signal with a low reference signal level, and a second comparing means for comparing a sine wave signal with a second reference signal which becomes higher following the magnitude of the sine wave signal. By providing both of the above, even if the rotation speed sharply decreases, a pulse is always output from the first comparing means, and the second comparing means
From the comparison means, a pulse from which noise in the high rotation speed range has been removed is output. Since the processing means comprehensively judges the relationship between the two pulse outputs, noise is not counted as a pulse, and the pulse in the low rotation speed region is not counted wrongly. As a result, an accurate rotation speed detection device can be obtained.

The first and second comparing means output the rising or falling of the pulse when the sine wave signal changes from a state lower than the first and second positive reference signals to a state higher. Then, when the sine wave signal changes from a higher state to a lower state than the first and second negative reference signals, the trailing edge or the leading edge of the pulse is output. That is, the output of the comparison means switches to a high level or a low level where the state changes. The processing means outputs a falling or rising output from the first comparing means and a corresponding falling or rising output from the second comparing means, and the past falling or rising of the first comparing means. Based on the rising output state, the falling or rising output of the first comparing means is determined to be invalid or valid, and the rotation speed is calculated based on the result, so that an accurate rotation speed detection device can be obtained. .

Further, there is no falling or rising output from the first comparing means and there is no corresponding falling or rising output from the second comparing means because the threshold value of the first comparing means is equal to the input voltage. There are both noise caused by the noise being too low than the value to be tracked, and noise caused by the threshold of the second comparing means being too high to track the input voltage. When the output interval B from the present output to the previous output output becomes smaller than the output interval A from the previous output to the output before the last output, among the outputs of the falling or the rising from the first comparing device,
It is determined that the current output of the rising edge or the falling edge is invalid. That is, when noise is introduced, the rising or falling output interval becomes abnormally shorter than the previous rising or falling output interval. Since the rotation speed is calculated based on the result, an accurate rotation speed detection device can be obtained.

Further, there is no falling or rising output from the first comparing means and there is no corresponding falling or rising output from the second comparing means because the threshold value of the first comparing means is equal to the input voltage. There are both noise caused by the noise being too low than the value to be tracked, and noise caused by the threshold of the second comparing means being too high to track the input voltage. When the output interval C from the current time to the previous time is greater than the output interval D from the previous time to the last time, among the outputs of the falling or the rising from the first comparing means, the processing means:
It is determined that the current rising or falling output is valid. That is, the decrease of the input voltage is related to the increase of the cycle of the input signal, and it is determined that the output interval of the rising or falling is longer than the output interval of the previous rising or falling. Since the rotation speed is calculated based on the result, an accurate rotation speed detection device can be obtained.

The output timing of the first comparing means and the second comparing means is always lower than the reference voltage of the first comparing means, so that the output of the first comparing means is always output first. Therefore, by disabling interrupts first from the first prohibiting means, when counting the outputs of the first comparing means and the second comparing means, the outputs obtained by converting the same waveform are counted at different timings. The probability of

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system configuration diagram of a rotation speed detecting device according to a first embodiment of the present invention. 2A and 2B are waveform diagrams of the counter of the rotation speed detection device according to the first embodiment of the present invention. FIG. 2A is an input signal, FIG. 2B is a first comparator output signal, and FIG. 2C is a second comparator output signal. , (D) are signals taken in by the microcomputer. Hereinafter, description will be given with reference to the drawings. In this embodiment, the output states of the first comparator and the second comparator are taken into consideration to determine whether the output from the first comparator is valid or invalid.

Reference numeral 1 denotes a sensor connected to a rotating shaft or the like, which is shown in FIG.
As shown in (a), a sine wave having a period and a wave height corresponding to the rotation speed is output. Reference numeral 21 is a first comparator for comparing the sine wave output from the sensor 1 with the reference voltage VR1, and the reference voltage VR1
Is set to a low constant voltage regardless of the input signal. 22 is a reference voltage V of the sine wave output from the sensor 1.
In the second comparator for comparing with R2, the reference voltage VR2 is low when the output voltage of the input signal is low in the low speed rotation range (long cycle) and is high when the output voltage of the high speed rotation range (short cycle) is high. It changes according to the input signal. Reference numeral 3 denotes a CPU unit that processes the outputs from the first comparator 21 and the second comparator 22, and includes interfaces 31, 34,
A register 32 for temporarily storing input data, a computation control unit 33 for determining whether the pulse is valid or invalid, writing or reading data, counting the number of outputs to calculate the number of revolutions, and a memory 35 for temporarily storing data for computation. , 36, 37.

Next, the operation will be described. The output from the sensor 1 (sine wave in FIG. 2A) is the first comparator 21.
And to the second comparator 22 in parallel. The comparator 21 compares the input signal with the reference signal VR1 and outputs L if it is higher (falling). Since the polarity of the reference signal VR1 is inverted (-VR1) by the output of the comparator 21, L continues until the input signal becomes below -VR1.
When -VR1 or less, H is output (rise). Similarly, H continues until the input signal exceeds VR1, and L is output (falling) when VR1 exceeds VR1. Similarly, the second comparator 22 is also compared with the reference signal VR2 and converted into a pulse. As a result, one square wave pulse having a rising edge and a falling edge is output for one cycle of the sine wave. For the input sine wave (sensor output) of FIG. 2A, the first comparator 21 outputs the square wave of FIG. 2B and the second comparator 22 outputs the square wave of FIG. 2C. It That is, the output from the first and second comparators is not in the H or L state, but in the portion corresponding to the rising or falling of the pulse.

In the output signal of the first comparator 21 of FIG. 2B, among the rising or falling outputs from the first comparator 21, the output interval from this time to the previous time is a predetermined value from the output interval from the previous time to the last two times. When it becomes smaller than α, it is judged that the output of the current rising or falling is invalid. In addition, when the output interval from this time to the previous time among the rising or falling outputs from the first comparator becomes greater than the output interval from the previous time to the last two times by a predetermined value β or more, the output of the rising or falling time is effective. It is determined that
For example, at the rising edge A11 of the first comparator output, there is the corresponding rising edge A21 of the second comparator output, so that it is effective without making a determination based on the output interval.

At the trailing edge A12 of the first comparator output, there is no corresponding trailing edge of the second comparator output, and the output interval B2 from this time to the last time is smaller than the output interval B1 from the last time to the last time by a predetermined value α or more. So it is invalid. At the rising edge A13 of the first comparator output, there is no corresponding rising edge of the second comparator output, and the output interval B3 from this time to the previous time is smaller than the output interval B2 from the previous time to the last two times by a predetermined value α or more, which is invalid.

Since there is a corresponding trailing edge A24 of the second comparator output at the trailing edge A14 of the first comparator output, it is effective without making a determination based on the output interval. At the rising edge A15 of the first comparator output, there is no corresponding falling edge of the second comparator output, and the output interval B5 from this time to the previous time is greater than the output interval B4 from the previous time to the last two times by a predetermined value β or more, which is effective. .

At the falling edge A16 of the first comparator output, there is no corresponding falling edge of the second comparator output, and the output interval B6 from this time to the previous time is larger than the output interval B5 from the previous time to the last time by a predetermined value β or more. So effective. At the rising edge A17 of the first comparator output, there is no corresponding falling edge of the second comparator output, and the output interval B7 from this time to the previous time is larger than the output interval B6 from the previous time to the last two times by a predetermined value β or more, which is effective. .

As described above, in the present embodiment, in the case of a normal input signal, the rising or falling is output from the second comparator in a predetermined time after the rising or falling from the first comparator. It should be done. However, if there is a change such as noise or low rotation, it will not be able to cope with it. Therefore, it is intended to detect a specific state from the past output interval as described above.

As a result of judging whether each rising or falling output of the first comparator is valid or invalid, the signal of FIG. 2 (d) is taken into the microcomputer. Based on this signal, the rotation speed or rotation speed is calculated by the equation (1) as required. Rotational speed (peripheral speed cm / sec) = d / x (1) where x: output interval sec (corresponding to B1, B2, B3, etc.) d: one tooth of the tooth portion of the sensor Length As described above, in the present embodiment, of the outputs of the first comparator, the output generated by the noise component is invalidated and removed,
Since the reference voltage VR2 of the second comparator does not drop following the rapid decrease in the number of revolutions, it is determined to be valid when there is no corresponding output from the second comparator, and the number of revolutions is calculated based on this result. Therefore, the reliability of the rotation speed detection device is improved.

FIG. 3 is a waveform diagram of a pulse counting section of the rotation speed detecting device according to the second embodiment of the present invention, in which (a) is an input signal,
(B) is a 1st comparator output signal, (c) is a 2nd comparator output signal. FIG. 4 is an execution flowchart of interrupt processing according to the second embodiment of the present invention. Hereinafter, description will be given with reference to the drawings. Since the system configuration is the same as that of the first embodiment, the description will be omitted. The present embodiment relates to interrupt processing at the time of calculating the rotation speed.

As for the output timings of the first comparator 21 and the second comparator 22, the reference voltage of the first comparator 21 is lower as shown in FIG. 4, so the output of the first comparator 21 is the output of the second comparator 22. More a
1, 1, a2, a3, and a4 are output earlier. When a change such as a fall of the pulse signal occurs as shown in (b) and (c) during the main routine processing of the CPU, the interrupt processing is started at this time, and the time (t) at this time is automatically stored in the interrupt RAM 1. And the count value added for each interrupt is automatically set in the interrupt RAM 2. After returning to the main routine processing, when the arithmetic processing is started, (t) is read from the RAM 1, and at the same time, the RAM is disabled while interrupts are prohibited to prevent data corruption due to the next interrupt.
The count value is read from 2, and the rotation speed calculation from the first comparator 21 is performed. In this case, since there are two comparators, the second comparator also reads (t) and the count at the same interrupt prohibition timing as the first comparator 21, and performs the calculation. In this way, the first and second
Data calculation is performed by interrupting each comparator output.

Although the above description is about the basic processing, if the interrupts are simultaneously prohibited in the first comparator 21 and the second comparator 22 in this way, the following problems occur. That is, when the interruption inhibition of the CPU happens to be between a1 after the output (H → L) of the first comparator as shown by A in FIG. 3B (that is, the inhibition is entered before A21), the first comparator The A11 output of the second comparator is counted at this timing, but the A21 output of the second comparator is counted at the next timing because the interrupt is disabled at this time. Although the pulse outputs of the first comparator 21 and the second comparator 22 originally have slight deviations, such deviations are allowed, and the pulse information of the first comparator 21 and the pulse information of the second comparator 22 are made to correspond to each other. However, the first comparator 21 and the second comparator 22 are deviated from each other and an error occurs.

Therefore, in this embodiment, the interruption of the interrupts from the first and second comparators is processed at the previous timing. Specifically, as shown in the block diagram of FIG. 5, the output of the sensor 1 is input to the first comparator 21 and the second comparator 22, and the output compared with the reference signal is temporarily stored in the register 32 via the interface 31. It Up to this point, both outputs are processed in parallel.

At step S1, initial processing is performed. In step S2, for example, as shown by A in FIG. 3B, the interruption of the first comparator 21 is prohibited. This is because the arithmetic processing is performed while the input data is once held in the register 32. In step S3, the data of the first comparator 21 is read out from the interrupt RAMs 1 and 2 and processed, and the processed data of the first comparator 21 is written in the main routine RAM 35. In step S4, since the data processing is completed, the interruption prohibition of the first comparator is released.

In step S5, for example, as shown by B in FIG. 3 (b), the interruption of the second comparator 22 is prohibited. In step S6, the second comparator 2
The data of No. 2 is read from the interrupt RAMs 1 and 2 and processed, and the processed data of the second comparator 22 is written to the RAM 35 for main routine. In step S7,
The interruption prohibition of the second comparator 22 is released.

At step S8, RA for main routine is used.
The data of the first comparator 21 and the data of the second comparator 22 are read from M35, and the arithmetic processing unit 33 performs pulse correction (determination processing of validity and invalidity) to calculate the rotation speed or the wheel speed. In step S9, ABS control is performed. That is, the brake pressure is controlled based on the wheel speed or the like output via the interface 34. Step S10
Then perform fail-safe processing.

As described above, in the present embodiment, for example, even if there is an interrupt from the second comparator 22 during the processing of steps S2 to S4, this interrupt is accepted and processed. The interrupts can be taken in synchronously, the counting error due to the shift of the output timing of both comparators at the time of pulse counting is reduced, and the reliability of the rotation speed detecting device is improved.

[0032]

As described above, the present invention solves such a problem, eliminates false counting due to noise, and
It is possible to provide a highly reliable rotation speed detection device without pulse counting error in the low speed rotation range.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a pulse counting unit of a rotation speed detecting device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of a pulse counter of the rotation speed detecting device according to the first embodiment of the present invention, in which (a) is an input signal and (b) is a first signal.
A comparator output signal, (c) is a second comparator output signal, and (d) is a signal taken in by the microcomputer.

FIG. 3 is a waveform diagram of a pulse counter of a rotation speed detecting device according to a second embodiment of the present invention, in which (a) is an input signal and (b) is a first signal.
The comparator output signal, (c) is the second comparator output signal.

FIG. 4 is an execution flowchart of interrupt processing according to a second embodiment of this invention.

FIG. 5 is a system configuration diagram of a pulse counting unit of a conventional rotation speed detection device.

FIG. 6 is a waveform diagram of a pulse counter of a conventional rotation speed detection device, in which (a) is an input signal and (b) is a comparator output signal.

[Explanation of symbols]

1 ... Sensor 32 ...
Register 21 ... First comparator 33 ...
.Operation control unit 22 ... Second comparator 31, 34 ...
-Interface 3 ... CPU section 36, 37 ...
RAM

Claims (5)

[Claims] 1. A sensor for outputting a sine wave signal having a different size and frequency corresponding to the number of revolutions of an object to be detected, and pulse conversion means for converting the sine wave signal from the sensor into a pulse signal, In a rotation speed detecting device for detecting the rotation speed of the detected object by counting the number of pulses of the pulse signal converted by the pulse converting means, the sine wave signal is changed in accordance with the magnitude of the sine wave signal. A second comparing means for comparing the sine wave signal with a constant first reference signal level that is absolutely lower than a minimum value of the second reference signal. A rotation speed detection device comprising: a first comparison means; and a processing means for detecting the rotation speed of the detected object based on the comparison results of the first and second comparison means. 2. The first and second comparing means have positive and negative binary values with respect to the first and second reference signals, respectively, and the sine wave signal is the first and second positive signals. When the state changes from a state lower than the reference signal having a value of
And a rising or falling edge of a pulse is output from the second comparing means, and when the sine wave signal changes from a state higher than the first and second negative reference signals to a state lower than the first and second negative reference signals, A second comparing means for outputting a trailing edge or a leading edge of the pulse, wherein the processing means detects the leading edge or the trailing edge output from the first comparing means, and outputs the leading edge or the trailing edge of the pulse corresponding to the output. Two
If the rising or falling output from the comparing means is not detected, the output from the first comparing means is invalid or invalid based on the state of the past rising or falling output of the first comparing means. 2. The rotation speed detection device according to claim 1, wherein the rotation speed detection device detects the rotation speed of the object to be detected as being valid. 3. The processing means, when the output interval B from the present time to the previous time is smaller than the output interval A from the previous time to the last two times, among the rising or falling outputs from the first comparing means, 3. The rotation speed detecting device according to claim 2, wherein it is judged that the current rising or falling output is invalid. 4. The processing means, when the output interval C from the current time to the previous time is larger than the output interval D from the previous time to the last time, among the rising or falling outputs from the first comparing means, 3. The rotation speed detecting device according to claim 2, wherein the current output of the rising edge or the falling edge is judged to be valid. 5. The processing means performs interrupt processing according to the pulse output respectively output from the first and second comparing means, and detects the rotational speed by associating the data of each pulse output. Further comprising first and second prohibiting means for prohibiting the interrupt processing, the first prohibiting means prohibiting the interrupt processing after the interrupt processing corresponding to the pulse output from the first comparing means, The second prohibiting means is configured to, after interrupt processing corresponding to the pulse output from the second comparing means, prohibit the interrupt processing and divide prohibition of each interrupt processing. The rotation speed detection device according to 1.