JPH0767067B2 - Flow pulse oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention transmits a certain amount of angular displacement as one approximate triangular wave voltage signal, compares the approximate triangular wave voltage signal with a plurality of reference voltages, and compares them. The present invention relates to a pulse oscillator that transmits a displacement amount with high resolution by obtaining a signal.

[Prior Art] The present applicant has proposed a flow rate transmitter in Japanese Utility Model Application No. 61-74286. This flow rate transmitter standardizes a sine wave signal transmitted at a frequency proportional to the rotation speed of the rotor of a positive displacement flow meter into a sine wave signal of constant amplitude, and further converts the sine wave signal into an approximate triangular wave signal. The approximate triangular wave voltage is compared with a plurality of reference level voltages, and when they match each other, a pulse signal is generated to generate a number of flow rate pulses proportional to the number of reference level voltages.

The sine wave in the flow transmitter is, for example, embedded in a rotor of a volumetric flowmeter in a radial direction with a pair of magnets exposed to have mutually opposite polarities, and on the end face plate of the measuring chamber facing the rotor. A magnetoresistive element is arranged so as to face the pair of magnets, and a magnetic flux change due to the magnet rotating with the rotor is detected by the magnetoresistive element to obtain a sine wave signal.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technique, the approximate triangular wave voltage is compared with the voltages of a plurality of reference levels, and when they match, a pulse signal is transmitted. There were the following problems.

That is, when the flowmeter rotor always rotates in one direction, a flow rate pulse having a certain amount of weight proportional to the rotation angle is transmitted, but when the flow rate is pulsating, the rotation of the rotor is Not only in the direction, but it may rotate while being accompanied by reverse rotation, or may generate rotational vibration of a minute angle under the influence of external vibration. The conventional flow rate transmitter has a problem in that due to such rotational fluctuation of the rotor, a noise pulse as if the fluid had moved is transmitted although the fluid does not substantially move.

The present invention has been made to solve the above problems, and in the case where rotational vibration occurs within the angular displacement at which one pulse signal is transmitted and then adjacent pulse signals of the pulse signal are transmitted. Another object of the present invention is to provide a pulse oscillator that does not emit noise pulses and prevents erroneous transmission of flow rate pulses due to rotational fluctuation of the rotor.

[Means for solving problems]

In order to solve the above problems, the present invention provides a flow pulse oscillator including the following means.

A first invention of the present application is a rotor that rotates at a rotational speed according to a flow rate of a fluid, a sine wave generation circuit that outputs a sine wave signal proportional to a rotation angle of the rotor, and the sine wave that is an approximate triangular wave signal. Approximate triangular wave conversion circuit for converting, peak detecting means for detecting the peak of the approximate triangular wave signal and outputting a peak detection pulse, a reference point preset to a plurality of signal levels, and the peak as an observation point, A coincidence signal output means for outputting a coincidence signal pulse when the level of the approximate triangular wave signal coincides with the signal level at the observation point, and these observation points are selected every other signal level in order of signal level,
Generate the coincidence signal pulse for the selected observation point as a state transition trigger from low level to high level,
On the other hand, there are two stable states, high trigger and low trigger, which generate the coincidence signal pulse for the unselected observation point as a state transition trigger from the high level to the low level, and the output of the trigger generating means as a trigger. State storage means and pulse oscillating means for oscillating a pulse consisting of changes in the high level and the low level of the state storage means as a flow rate pulse representing the flow rate of the fluid.

Further, a second invention of the present application is that when the peak detection means in the first invention is compared with a full-wave rectifier circuit, an output voltage of the full-wave rectifier circuit and a capacitor terminal voltage charged by the output voltage are compared and coincident with each other. A comparator circuit that outputs a peak detection pulse, and the full-wave rectification of the capacitor via a resistor until the approximate triangular wave signal reaches a peak beyond the reference point near the peak and reaches the reference point again. It is characterized in that it is constituted by a switch circuit which is connected to the circuit and is switched and connected so as to discharge the electric charge of the capacitor at other points.

In each of the above inventions, the pulse oscillating means outputs a pulse consisting of repeating two stable states of high and low output from the state storing means as a pulse representing the flow rate of the fluid. A pulse having a pulse repetition frequency that is an integral multiple may be formed and output as a pulse representing the flow rate of the fluid. As a means for this, a frequency multiplication circuit can be connected.

Further, in each of the above inventions, the state storage means can have various modes, but in a preferred mode, it is configured by a flip-flop circuit. In this case, the flip-flop circuit used is generally an RS flip-flop circuit.

[Operation] With the above-described configuration, the present invention provides:
At each reference point, when a level match between each reference level voltage and the approximate triangular wave voltage signal that changes like a ramp is detected, that reference point remains in that detection state until a match is detected at the next reference point. By self-holding, the above-mentioned problem is solved by giving hysteresis to the angular displacement. Therefore, the operation of this solving means will be described.

The present invention relates to a flow rate transmitter that outputs a number of flow rate pulses proportional to the number of reference level voltages by comparing an approximate triangular wave voltage with a plurality of reference level voltages and transmitting a pulse signal when they match. Approximately inputting the transition of the stable state from the low level to the high level or from the high level to the low level in the state storage means by using the coincidence signal pulse sequentially generated in the process of rising or falling of the approximate triangular wave voltage as a trigger. The pulse output is obtained by repeating the ramp voltage change of the triangular wave voltage signal.

Here, the coincidence signal pulses that sequentially occur during the process of increasing or decreasing the voltage of the approximate triangular wave alternate between the two stable states every time this pulse is output. Every other voltage is selected in order of voltage, including the peak of the voltage, and is used as a trigger for either a transition from high to low or a transition from low to high. Therefore, the state storage means shifts to one of the two stable states, for example, a high level state by inputting a coincidence signal pulse from a certain reference point, and when the state is stable in this state, adjacent reference points (peak This state is maintained until a coincidence signal pulse is output from (including).

Due to this self-holding action, the state storage means does not shift the current state to another stable state depending on how many coincidence signal pulses are output from the same reference point. As a result, as described above, the flow rate of the fluid pulsates, the rotation of the rotor is not limited to one direction, and the rotor rotates with reverse rotation, or rotational vibration of a small angle is generated under the influence of external vibration. This causes fluctuations in rotation, and the ramp-shaped voltage change of the approximate triangular wave voltage repeats up and down around the same reference point, and even if a match signal pulse is output each time, those pulses are invalid. Therefore, it does not contribute to the flow rate pulse at all.

Therefore, according to the present invention, it is possible to solve the conventional problem that a noise pulse is emitted as if the fluid had moved despite the substantial movement of the fluid.

[Examples] Examples of the present invention will be described with reference to the drawings.

<Structure of Embodiment> FIG. 1A shows a circuit structure of a main part of an embodiment of the pulse oscillator of the present invention, and FIG. 1B shows an outline of an overall structure of an embodiment of the pulse oscillator of the present invention. The figure shows an example of an approximate triangular wave conversion circuit that converts a sine wave into an approximate triangular wave.

As shown in FIG. 1B, the pulse oscillator of the present embodiment is configured to include a sine wave generation circuit 10, an approximate triangular wave conversion circuit 20, and a flow rate pulse forming circuit 30. In the present invention, the flow pulse forming circuit 30 is the main part, but in this embodiment, first, the sine wave generation circuit 10 and the approximate triangular wave conversion circuit 20 will be described.

The sine wave generating circuit 10 is composed of, for example, a magnetoresistive element, and outputs a sine wave proportional to the rotation angle as described above. A DC voltage is applied from the power source E through a terminal T ₁ , A sine wave is output between terminals T ₂ and T ₃ .

The approximate triangular wave conversion circuit 20 includes a low-pass filter 22 for removing high frequency noise and a negative feedback amplifier circuit 23 having a feedback resistor R _2.
A non-inverting amplifier circuit 24 and a correction element 25 for correcting the output voltage of the non-inverting amplifier circuit 24 so as to change exponentially.

The non-inverting amplifier circuit 24 as a feedback circuit, and a resistor R _3,
It has a circuit in which the capacitor C ₁ is connected in parallel. The capacitor C ₁ is for providing a wide band filter characteristic. This feedback circuit is connected to the inverting input terminal of the non-inverting amplifier circuit 24. The correction element 25 is connected to the inverting input terminal.

This correction element 25 is composed of diodes D ₁ and D ₂ which have a diode characteristic by short-circuiting the base and collector of the transistor.
Are connected in antiparallel. This correction element 25 is a diode voltage
It is used in the region where the current characteristics change exponentially. Since the diodes D ₁ and D ₂ are used in this operating range, the voltage applied to them is set to about ± 0.6 V at the maximum. That is, the output voltage of the negative feedback amplifier circuit 23 is also ± 0.6V.
It is set to a degree.

A resistor R ₈ for output adjustment is connected in parallel with the correction element 25. It is preferable that the resistance R ₈ is set so that the resistance value can be appropriately selected and is connected so as to be adjustable.

Next, the flow rate pulse forming circuit 30, which is the main part of this embodiment,
From the peak to the peak of the input approximate triangular wave voltage signal,
When the input signal voltage change is observed at each reference point by dividing into four equal parts by the three reference points b and c, and when the input signal voltage change matches the reference level of each reference point, a match signal pulse is generated. It is provided with means for forming the coincidence signal pulse to be output, means for detecting the peak of the approximate triangular wave, and state storage means.

The means for forming this coincidence signal pulse is the reference voltage circuit 31.
And a comparator 32a, 32b that outputs a high level when the input voltage exceeds the reference voltage and a low level when the input voltage falls below the reference voltage.
32c, rising and falling of the output voltage of the comparators 32a, 32b and 32c, that is, edge detection circuits 33a, 33b and 33c that detect an edge and output a pulse, and the edge detection circuits 33a, 33b and 33c. Is used as a trigger to output a pulse having a preset pulse width and monostable multivibrators 34a, 34b and 34c.

The means for detecting the peak of the approximate triangular wave is a peak detection circuit 40 for detecting the peak of the approximate triangular wave and outputting a pulse.
And a monostable multivibrator 39 that outputs a peak detection pulse having a preset pulse width by using the pulse from the detection circuit 40 as a trigger.

The peak detection circuit 40, as shown in FIG. 3, is a full-wave rectification circuit 42, a comparison voltage capacitor C ₂ , and a comparator for comparing the output voltage of the rectification circuit 42 and the terminal voltage of the capacitor C ₂ .
43 and a switch circuit 44 that switches between charging and discharging of the capacitor C ₂ . Switch circuit 44
Is configured to include a NAND gate circuit 45, an inverter 46, and switch contacts SW ₁ and SW ₂ .

The state storage means includes an OR gate circuit 35 that ORs the coincidence signals at the reference points a and c, and a reference point b in the middle.
An OR gate circuit 36 that takes the logical sum of the coincidence signal at the peak detection circuit 40 and the peak detection pulse from the peak detection circuit 40, and the OR gate circuit 36.
The flip-flop circuit 37 uses the output pulse of 36 as a set signal and the output pulse of the OR gate circuit 35 as a reset signal. Further, a frequency multiplication circuit 38 is connected to the subsequent stage of the flip-flop circuit 37.

The frequency multiplication circuit 38 includes a circuit that detects the edge of the pulse output from the flip-flop circuit 37, and a monostable multivibrator that outputs a pulse of a certain width by using the edge detection signal as a trigger.
A pulse having a pulse repetition frequency twice that of the output pulse is formed and output as a flow rate pulse.

<Operation of Embodiment> Next, the operation of the present embodiment will be described with reference to the above-mentioned drawings and FIG.

From the sine wave generation circuit 10, a sine wave signal voltage proportional to the rotation angle of the rotating body is output from the terminals T ₂ and T ₃ . in this case,
Since the sine wave is not a perfect sine wave but an approximate sine wave due to uneven rotation of the rotating body, rattling, etc., high-frequency noise superimposed on the signal is removed by passing the low-pass filter 22. .

After that, the sine wave signal is amplified by the negative feedback amplifier circuit 23. The output voltage waveform is further amplified by the non-inverting amplifier circuit 24. In the non-inverting amplifier circuit 24, not the linear amplification but the amplification according to the exponential waveform is performed by the correction element 25. As a result, the sine wave waveform becomes a curve that approximates a substantially straight line, and an approximate triangular wave is obtained.

This approximate triangular wave voltage signal is output from the terminal T ₆ to the comparators 32a, 32b and 32c of the flow rate pulse forming circuit 30 and the peak detection circuit 4
Entered as 0 and. Reference voltages of different voltages are input from the reference voltage circuit 31 to the comparators 32a, 32b, and 32c. This reference voltage circuit 31 is a resistor
The DC voltage E is divided by R ₄ , R ₅ , R ₆ and R ₇ to form a reference voltage. In this embodiment, as shown in FIG. 2, the approximate triangular wave voltage L is set to 4 by the three points a, b and c.
It is divided.

When the input approximate triangular wave voltage exceeds the reference voltage at the reference point a, the output of the comparator 32a becomes high level. Next, when the reference voltage at the reference point b is exceeded, the output of the comparator 32b becomes high level, and when the reference voltage at the reference point c is exceeded, the output of the comparator 32c becomes high level. In this state, the outputs of all the comparators 32a, 32b and 32c are at high level.

On the other hand, the approximate triangular wave voltage input to the peak detection circuit 40 is
Full-wave rectification is performed by the full-wave rectification circuit 42, and the portion on the negative voltage side is folded back to the positive voltage side as shown by the broken line in FIG. That is, the peak P _B on the negative voltage side becomes the peak P _B ′ on the positive voltage side, and the peaks P _T on the original positive voltage side are alternately arranged. This rectified output is input to one input terminal of the comparator 43.

Here, the switch circuit 44 is controlled by the outputs X of the comparator 32a and the output Z of the comparator 32c for the reference points a and c shown in FIG. 4 to open and close the switch contacts SW ₁ and SW ₂ .
Since the output Z is inverted and input to the NAND gate circuit 45, the switch contact SW ₁ has the output X at the high level,
It is turned off when the output Z is low level, and is turned on in other cases, that is, when both the output X and the output Z are high level or low level. Since the switch contact SW ₂ passes through the inverter 46, it has an on / off pattern opposite to that of the switch contact SW ₁ .

The outputs X and Z are the same as those shown in FIG.

When the switch contact SW ₁ is turned on, the full-wave rectifier circuit 42 is connected to the capacitor C ₂ via the resistor R ₁₁ , and the capacitor C ₂
Charge ₂ This state occurs when the approximate triangular wave voltage approaches the peak value. The terminal voltage of the capacitor C ₂ is
According to the time constant of the resistor R ₁₁ , it rises as it approaches the peak of the approximate triangular wave voltage, reaches the maximum value at the peak, and coincides with the output voltage of the full-wave rectification circuit 42. At this time, the output of the comparator 43 becomes high level. The rising of the high level triggers the monostable multivibrator 39 to output the peak detection pulse P _S. FIG. 4 shows the output waveform of the comparator 43 as the output of the terminal T ₉ , and also shows the waveform of the peak detection pulse P _S which is the output of the monostable multivibrator 39.

After that, when the approximate triangular wave voltage starts to move away from the peak,
The output level of the NAND gate circuit 45 is inverted, the switch contact SW ₂ is turned on via the inverter 46, and the electric charge of the capacitor C ₂ is discharged via the resistor R ₁₂ . as a result,
The comparator 43 again becomes inconsistent and its output becomes low level.

After that, when the voltage of the approximate triangular wave voltage decreases in order of higher voltage than the reference voltages of the reference points c, b and a, the outputs of the corresponding comparators 32c, 32b and 32a sequentially change from high level to low level. FIG. 2 shows output waveforms of the comparators 32a, 32b and 32c.

The output of each of the comparators 32a, 32b and 32c, in the edge detection circuit 33a, 33b and 33c, rising and falling are detected, the respective detection signal as a trigger, the corresponding monostable multivibrator 34a, 34b and. A pulse is output from 34c. Of these pulses, the pulses from the vibrators 34a and 34c are input to the OR gate circuit 35 and become the reset signal R of the flip-flop circuit 37. On the other hand, the pulse from the vibrator 34b, along with the peak detection pulse P _S, is inputted to the OR gate circuit 36, a set signal S of the flip-flop circuit 37.

When these reference points a to c are set at appropriate intervals, all of these signals are lined up at this interval. That is, FF _{I in} Fig. 2
As shown by, the set signal S and the reset signal R are alternately arranged at equal intervals.

As a result, the flip-flop circuit 37 outputs pulses with a constant pulse width and a constant interval. This state is shown as FF ₀ in FIG. This makes the rotor 1
A plurality of flow rate pulses can be obtained at equal intervals for rotation, and a high resolution flow rate transmitter can be realized.

This pulse can be used as a flow rate pulse as it is, but the pulse repetition frequency can be further increased,
Thereby, the resolution of the flow meter can be improved.

Therefore, in this embodiment, the frequency multiplication circuit 38 obtains a pulse having a double repetition frequency by utilizing the rising and falling edges of the pulse.

<Other Embodiments> In the above embodiment, the three points a, b and c are selected as a reference, but it goes without saying that two or four or more reference points can be selected.

In this case, if an even number of reference points are selected, in the set / reset combination of the flip-flop circuit by the coincidence signal pulse from each reference point, the positive voltage side peak and the negative voltage side peak are divided into set and reset. Becomes FIG. 5 shows an example thereof.

In the example of FIG. 5, four reference points a to d are selected,
Symbols S (set) and R (reset) indicating set / reset of the flip-flop circuit are attached to the intersections of the approximate triangular wave voltage signal L and the reference voltage level.

As is clear from the arrangement of these symbols, the positive voltage side peak P _T and the negative voltage side peak P _B become the set S,
The latter is reset R. Therefore, whether the peak of the approximate triangular wave voltage is positive or negative is detected, and whether the peak detection pulse is input to the OR gate 36 or 35 is sorted by positive or negative. A means for this can be realized by an AND gate circuit, for example.

Further, the present invention can be configured by including a peak detection circuit having a circuit format different from that of the above-described embodiment. For example,
It may be a circuit that detects by comparing the input voltage with the peak voltage as the reference voltage.

[Effect of the Invention] As described above, according to the present invention, when one pulse signal is transmitted, rotational vibration occurs within an angular displacement at which adjacent pulse signals of the pulse signals are transmitted. In addition, the noise pulse is not transmitted, and there is an effect of preventing an erroneous transmission of the flow rate pulse due to the rotational fluctuation of the rotor.

[Brief description of drawings]

FIG. 1A is a block diagram showing a main part of an embodiment of the pulse oscillator of the present invention, FIG. 1B is a block diagram showing an outline of the overall configuration of the pulse oscillator of the present invention, and FIG. 1C is a pulse oscillator of the present invention. A block diagram showing an example of an approximate triangular wave conversion circuit used,
2 is a waveform diagram showing the operation of an embodiment of the pulse oscillator of the present invention, FIG. 3 is a block diagram showing an example of the peak detection circuit used in this embodiment, and FIG. 4 is an operation of the peak detection circuit. FIG. 5 is a waveform diagram showing the operation of another embodiment of the present invention. 10 …… Sine wave generation circuit, 20 …… Approximate triangular wave conversion circuit, 22
…… Low-pass filter, 23 …… Negative feedback amplifier circuit, 24 ……
Non-inverting amplifier circuit, 25 ... Correction element, 30 ... Flow rate pulse forming circuit, 31 ... Reference voltage circuit, 32a, 32b, 32c ... Comparator, 33a, 33b, 33c ... Edge detection circuit, 34a, 34b , 34c
...... Mono-stable multi-vibrator, 35, 36 …… Or gate circuit, 37 …… Flip-flop circuit, 38 …… Frequency multiplier circuit, 39 …… Mono-stable multi-vibrator, 40 …… Peak detection circuit, 42 …… Full wave rectification Circuit, 43 …… Comparator, 44 ……
Switch circuit 45 ...... NAND gate circuit, 46 ...... _{inverter, R 1 ~R 8, R 11} , R 12 ...... resistance, D _1, D ₂ ...... diodes, C _1, C ₂ ...... capacitors, SW _1, SW ₂ ...... Switch contact

Claims (6)

[Claims] 1. A rotor that rotates at a rotational speed according to the flow rate of a fluid, a sine wave generation circuit that outputs a sine wave signal proportional to the rotation angle of the rotor, and a sine wave that converts the sine wave to an approximate triangular wave signal. An approximate triangular wave conversion circuit, a peak detecting means for detecting a peak of the approximate triangular wave signal and outputting a peak detection pulse, a reference point preset to a plurality of signal levels, and the peak as an observation point, A coincidence signal output means for outputting a coincidence signal pulse when the level of the above-mentioned approximate triangular wave signal coincides with the signal level at the observation points, and these observation points are selected every other signal level in order,
Generate the coincidence signal pulse for the selected observation point as a state transition trigger from low level to high level,
On the other hand, there are two stable states, high trigger and low trigger, which generate the coincidence signal pulse for the unselected observation point as a state transition trigger from the high level to the low level, and the output of the trigger generating means as a trigger. A flow rate pulse oscillator comprising: a state storage means; and a pulse oscillating means for oscillating a pulse composed of a change in the high level and a low level of the state storage means as a flow rate pulse representing the flow rate of the fluid. 2. The pulse oscillating means includes a frequency multiplication circuit for converting the pulse output from the state storing means into a pulse having a pulse repetition frequency of at least twice, and the pulse of the pulse repetition frequency of at least twice is flown. The flow rate pulse oscillator according to claim 1, wherein the flow rate pulse oscillator oscillates as a pulse. 3. A flow pulse oscillator according to claim 1 or 2, wherein the state storage means is constituted by a flip-flop circuit. 4. A rotor that rotates at a rotational speed according to the flow rate of a fluid, a sine wave generation circuit that outputs a sine wave signal proportional to the rotation angle of the rotor, and a sine wave that converts the sine wave to an approximate triangular wave signal. An approximate triangular wave conversion circuit, a peak detecting means for detecting a peak of the approximate triangular wave signal and outputting a peak detection pulse, a reference point preset to a plurality of signal levels, and the peak as an observation point, A coincidence signal output means for outputting a coincidence signal pulse when the level of the above-mentioned approximate triangular wave signal coincides with the signal level at the observation points, and these observation points are selected every other signal level in order,
Generate the coincidence signal pulse for the selected observation point as a state transition trigger from low level to high level,
On the other hand, there are two stable states, high trigger and low trigger, which generate the coincidence signal pulse for the unselected observation point as a state transition trigger from the high level to the low level, and the output of the trigger generating means as a trigger. And a pulse oscillating means for oscillating a pulse composed of a change of the high level and the low level of the state storing means as a flow rate pulse representing the flow rate of the fluid, wherein the peak detecting means is a full-wave rectifying circuit, A comparison circuit that outputs a peak detection pulse when the output voltage of the full-wave rectifier circuit and the capacitor terminal voltage charged by the output voltage are compared and coincides with each other, and the approximate triangular wave signal peaks beyond a reference point near the peak. Until it reaches the reference point again and the capacitor is connected to the full-wave rectification circuit through a resistor. Connect, in other times, the flow rate pulse generator, characterized in that it is constituted by a switch circuit which connects the switching so as to discharge electric charge of the capacitor. 5. The pulse oscillating means includes a frequency multiplying circuit for converting the pulse output from the state storing means into a pulse having a pulse repetition frequency of at least twice, and the pulse of the pulse repetition frequency of at least twice is flown. The flow pulse oscillator according to claim 4, wherein the flow pulse oscillator oscillates as a pulse. 6. A flow pulse oscillator according to claim 4 or 5, wherein the state storage means is constituted by a flip-flop circuit.