JPS63277929A - Vortex flowmeter - Google Patents

Abstract

PURPOSE:To detect a correct vortex frequency by fixing the passing band of a variable frequency filter to a specific passing band in synchronism with abrupt speed reduction of an engine. CONSTITUTION:An ultrasonic wave which crosses a flow of a Karman vortex street is received by an ultrasonic wave receiver 5, whose output is inputted to a phase comparator 9 through a waveform shaping circuit 8. The output of the phase comparator 9 is outputted through a low-pass filter 11, the variable frequency filter 12, and a waveform shaping and amplifying circuit 13. Its output is supplied to a gate circuit 5 and an f-V converting circuit 14, whose output is used to control the frequency band of the filter 12. A reset signal is generated in synchronism with the abrupt speed reduction of the engine to operate the gate circuit 15, and the passing band of the filter 12 is fixed to the low frequency in-fixation passing band.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vortex flowmeter used for one engine, and in particular, it is capable of detecting the correct vortex frequency without causing erroneous measurements due to excessive noise that occurs when one engine decelerates. This is how it was done.

[Conventional technology]

Conventionally, regarding vortex flowmeters used in engines, for example, Japanese Patent Publications No. 58-15045 and Japanese Patent Publication No. 59. -24363
Japanese Patent Publication No. 58-56415 are known. FIG. 1 is a block diagram showing a vortex flow meter according to the present invention, which will be described later. FIG. 1 will be referred to when explaining the [prior art].

This FIG. 1 also includes a portion of the prior art.

First, referring to FIG. 1, the portion shown in the above-mentioned Japanese Patent Publication No. 58-56415 will be briefly described. In FIG. 1, an ultrasonic transmitter 4 is connected to a flowmeter 1 having a vortex generator 2.
and an ultrasonic receiver 5 are arranged facing each other, and an ultrasonic oscillation circuit 6 generates an ultrasonic wave so that the ultrasonic wave propagates across the flow of the Karman vortex street 3 generated on the downstream side of the vortex generator 2. The sound wave transmitter 4 is excited.

The ultrasonic wave that crosses the flow of the Karman vortex street is phase-modulated by the Karman vortex street 3 and is received by the ultrasound receiver 5. This received signal is waveform-shaped by a waveform shaping circuit 8 and output to a phase comparator 9.

On the other hand, the output of the ultrasonic oscillation circuit 6 that excites the ultrasonic transmitter 4 is applied to the voltage controlled phase shift circuit 7.

This voltage controlled phase shift circuit 7 maintains high frequency stability of the ultrasonic oscillation frequency signal.

It controls only the phase shift angle. This voltage controlled phase shift circuit 7 shifts the phase of the output of the ultrasonic oscillation circuit 6 and applies it to the phase comparator 9.

Phase comparator9. Ultrasonic oscillation circuit 6, voltage controlled phase shift circuit 7j? and loop filter IOK) constitute a phase-locked loop. Note that 11 is a low-pass filter.

A phase comparator 9 compares the phases of the output of the waveform shaping circuit 8 and the output of the voltage controlled phase shift circuit 7.

The comparison result is added to the loop filter IO, and the loop filter 10 removes the non-fluorescent frequency component of this comparison band.

Depending on the output voltage of this loop filter 10.

The voltage controlled phase shift circuit 7 controls the phase shift angle of the output signal of the ultrasonic oscillation circuit 6 and outputs it to the single phase comparator 9.

In addition, the output of the voltage-controlled phase shift circuit 7 is synchronized with the ultrasonic reception signal, and as a result, the output of the loop filter 1O becomes the phase demodulated signal as it is.

However, in the case of this publication, IC! , the vortex frequency is disturbed by low-frequency undulations caused by noise other than <g, which is received by the ultrasonic receiver 5, and the flow of the fluid.

In order to solve this problem, a vortex flow rate fitJ has been proposed by the non-inventing applicant and the same applicant.
The AtIL meter will be further described with reference to FIG.

In addition to the configurations shown by reference numerals 1 to 11, the invention of this prior application has newly added parts described below.

That is, the output of the 1-phase comparator 9 is input to a loop filter 10 and is also input to a variable frequency filter 12 via a low-pass filter 11. The output of this variable frequency filter 12 is input to a waveform shaping amplifier circuit 13.

A carmine vortex frequency signal corresponding to the flow rate of the flowmeter 1 is output from the waveform shaping amplifier circuit 13.

The signal is also input to this Karman vortex frequency signal frequency-voltage (hereinafter referred to as f-4) conversion circuit 14. The output of the fV conversion circuit 14 controls the frequency band of the variable frequency filter 120.

With this configuration, as described above.

The vortex signal, that is, the phase demodulated signal, which occurs in the flow rate of the fluid to be measured in the flowmeter IKfi, is processed by the low arm filter 11.
The signal is inputted to the variable frequency filter 12 via.

The variable frequency filter 12 is a band/arm filter, and has frequency band characteristics as shown in Figure E4, and the shaded part between the lower limit fL and the upper limit fU of the frequency variable filter 12 is a pass band. There is.

In this variable frequency filter 12, the lower limit frequency f
Noise components with frequencies below L are removed.

Further, as the upper limit is met, noise components caused by the engine having a frequency higher than the overfrequency fU are removed.

This engine noise is caused by the pulsation of the air flow. When the relatively low-frequency noise air passes through the air valve, tA
These are low output frequency noises caused by so-called wind noise, that is, relatively high frequency noises when the flow rate is low, or high output frequency noises that occur during operations such as charging.

Since these noises vary in their generation area and the visible flow rate also varies depending on the instantaneous behavior of the engine, the bandwidth of the vortex frequency is quite wide.

The variable frequency filter 12 is designed to have passband characteristics as shown in FIG.

The vortex frequency signal that has passed through the variable frequency filter 12 is waveform-shaped and amplified by a waveform shaping amplification circuit 13, and a vortex frequency signal is output.

At the same time, the vortex frequency signal u f -V conversion circuit 14 converts it into a voltage corresponding to the frequency, and this voltage limits the passband of the variable frequency filter 12 .

As a result, the passband of the variable frequency filter 120 changes, the passband in FIG. 4 changes, and the width of the passband shown by diagonal lines in FIG. 4 changes.

[Problem that the invention seeks to solve]

When this vortex flowmeter measures the amount of intake air in an engine equipped with a supercharger, the vortex signal wave is disturbed by ultrasonic noise generated by the supercharger. This turbulence increases as the rotation of the supercharger increases, or normally the amount of intake air increases. As shown in FIG. 5 (bJ), the good signal B passes through the frequency variable filter 12 and distortion is removed.

However, when the throttle valve is suddenly closed, the rotation of the supercharger does not suddenly decrease due to inertia, even though the amount of intake air decreases. As shown in FIG. 6(b), the signal at the output end of the variable frequency filter 12 has a waveform with an extremely poor S/N ratio.

With this waveform, noise is mistakenly judged to be a signal, and an extremely high frequency is output after passing through the variable frequency filter 12.) This causes engine stoppage and rough idling.

This invention was developed to solve this problem, and aims to provide a vortex flowmeter that can detect the correct vortex frequency during engine deceleration (without erroneous measurements due to excessive noise). shall be.

[Means for solving problems]

The vortex FL quantity meter according to the present invention includes a variable frequency filter that receives a vortex signal generated in response to the flow rate of a fluid to be measured, a well-shaped shaping amplifier circuit that shapes and amplifies the output of the frequency variable filter, and A frequency-voltage conversion circuit that converts the vortex frequency output output from the shaping amplifier circuit into voltage and controls the passband of the variable frequency filter, and a frequency-voltage conversion circuit that controls the passband of the variable frequency filter by changing it as the engine decelerates to a predetermined value. There is a type 11' provided with fixing means.

[For production]

In this invention, a vortex signal generated in response to the flow rate of the fluid to be measured is introduced into a variable frequency filter, an unstable noise component is removed, and the waveform is shaped and amplified by a waveform shaping amplifier circuit. It is converted into a voltage according to the output frequency, and the output voltage is used to control the passband of the variable frequency filter to block the passage of noise superimposed on the vortex frequency, and in synchronization with the sudden deceleration of the engine, the passband of the variable frequency filter is controlled. is fixed to a predetermined passband.

〔Example〕

Embodiments of the vortex flowmeter of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment.

In FIG. 1, the description of the parts described in the "Prior Art" column will be omitted to avoid duplication.

In this invention, a new Kr-) circuit 15 is added in addition to the parts indicated by numerals 1 to 14 in FIG. -) The output of the circuit 15 is applied to the fV conversion circuit 14. The passband of the variable frequency filter 12 is controlled by the output voltage of the fV conversion circuit 14.

Further, the r-) circuit 15 is configured to be activated by a reset signal R generated in response to deceleration of one engine.

Next, the operation of the present invention will be explained, but since the operation up to controlling the pass band width of the variable frequency filter 12 has already been described, here, only the features of the present invention will be explained. Let's talk about K.

Since the conventional problem occurrence area is only the sudden deceleration area of the engine, a reset signal R is generated in synchronization with the sudden deceleration of the engine, and the gate circuit 15 is activated by this reset signal R.

As a result, the output of the waveform shaping amplifier circuit 13, that is,
The input of the fV conversion circuit 14 is bypassed, and the passband of the variable frequency filter 12 is fixed to the fixed passband shown in FIG.

This forcibly removes the high frequency component i1, as shown in Figure 3 (
Even if a signal wave with superimposed noise as shown in a) is applied to the variable frequency filter 12, the variable frequency filter 12
A signal from which noise has been removed as shown in FIG. 3(b) is output at the output end of the .

In the embodiment shown in FIG. 1, the gate circuit 15 is provided on the input side of the f-VK conversion circuit 14, but the present invention is not limited to this, and the gate circuit 15 may be provided as shown in FIG. % is provided between the output side of the f-V conversion circuit 14 and the variable frequency filter 12, and the gate circuit 15 is operated by the reset signal R to bypass the output of the f-V conversion circuit 14. However, the same effect as in the above embodiment,
Effects can be obtained.

〔Effect of the invention〕

As explained above, this invention fixes the pass band of the frequency variable filter to a predetermined pass band in synchronization with the sudden deceleration of the engine, and 6. The correct vortex frequency can be detected without any measurements occurring.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an embodiment of the vortex flowmeter invented by Jin.
FIG. 2 is a block diagram showing only the peripheral portion of another embodiment of the vortex flow meter of this invention that is different from that in FIG. Waveform diagram of the input side and output side of the variable frequency filter during rotation,
45th! J is a diagram showing the relationship between the output frequency and the passing frequency of the variable frequency filter for explaining the present invention and the conventional vortex flowmeter, and FIG. Waveform diagrams on the input side and output side, Figure Wc6 is a waveform diagram on the input side and output side of the variable frequency filter of a conventional vortex flowmeter during low rotation after rapid deceleration of the engine. l... Flowmeter, 2... Vortex generator, 3... Karman vortex street, 4... Ultrasonic transmitter, 5... Ultrasonic receiver,
6... Ultrasonic oscillation circuit, 7... Voltage controlled phase shift circuit, 8... Waveform shaping circuit, 9... Phase shift comparator, 10
. . . Loop filter, 11 . . . Low frequency filter, 12 . . . Variable frequency filter, 13 . . . Waveform shaping circuit, 15 . Show parts.

Claims (2)

[Claims] (1) A detection means for detecting a vortex signal generated in response to the amount of air taken into the engine, a frequency variable filter that band-passes the output of this detection means, and a waveform shaping and amplification of the output signal of this frequency variable filter to A waveform shaping amplifier circuit that outputs a vortex frequency corresponding to the amount of intake air, and a frequency-voltage converter that receives the vortex frequency output and converts it into a voltage corresponding to that frequency, and uses this voltage to control the passband of the variable frequency filter. A vortex flowmeter comprising: a circuit; and means for fixing the passband of the variable frequency filter to a predetermined passband in response to deceleration of the engine. (2) The vortex flowmeter according to claim 1, wherein the fixing means is a gate circuit that bypasses the input or output to the input or output side of the frequency-voltage conversion circuit.