JPH07103802A - Volume measuring equipment - Google Patents

Abstract

PURPOSE:To conduct accurate measurement of the volume of an object placed in a main tank even under a noisy environment through a simple and inexpensive constitution. CONSTITUTION:The volume measuring equipment comprises first and second microphones 34a, 34b for detecting the pressure variation of an auxiliary tank and a main tank 30, a first amplitude detection circuit 4 for rectifying and smoothing a detection signal from the first microphone 34a and detecting the amplitude thereof, and a second amplitude detection circuit 9 for detecting the amplitude based on the correlation value between a detection signal from the second microphone 34b and a driving signal for a volume variation detecting means. A division circuit divides an output from the second amplitude detection circuit 9 by an output from the first amplitude detection circuit 4 and the volume of an object is measured based on the division results.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume measuring device for measuring the volume (volume) of an object to be measured such as a liquid contained in a tank.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional volume measuring device disclosed in, for example, Japanese Patent Laid-Open No. 206723/1990. In FIG. Is a main tank with a different shape to store
A correction tank 31 having a smaller volume than the main tank 30 is connected to the main tank 30 via a connecting pipe 47.

A vent hole 35 having a small diameter is formed in the upper portion of the main tank 30 having the different shape. The vent hole 35 does not necessarily have to be provided. A volume changing means (mechanism) 33 having, for example, a piston shape or a speaker shape is provided above the correction tank 31, and the volume inside the correction tank 31 can be changed by the operation of the volume changing means 33. Has become.

The volume changing means 33 is constructed such that the main tank 30 and the correction tank 31 are partitioned from each other, and a condenser microphone 34b as a second microphone is provided on the main tank 30 side. There is.

On the other hand, on the correction tank 31 side, a dynamic microphone 34a as a first microphone having a lower sensitivity than the second microphone is provided.
The volume changing means 33 as a speaker is driven at a predetermined angular frequency ω ₀ .

Further, 37a and 37b are center angular frequencies ω ₀
, 39a and 39b are amplitude detectors for extracting the signal amplitudes from the signal components of these bandpass filters 37a and 37b, and 40 is these amplitude detectors 39.
This is a divider that divides the outputs of a and 39b to obtain the volume of the hollow portion of the main tank 30.

Further, 41 is a subtractor, which functions to determine the substantial volume of the liquid by subtracting the volume of the hollow portion from the total volume of the main tank 30.

Therefore, in such a volume measuring apparatus, the main tank 30 and the correction tank 3 are controlled by the speaker 33.
When the respective volumes of 1 are regularly changed at the angular frequency ω ₀ , the respective pressure fluctuations in the main tank 30 and the correction tank 31 are changed by the dynamic microphone 34a attached to the respective tanks 30, 30 and the condenser microphone. Detected by 34b.

Therefore, as for the frequency of the condenser microphone 34b which has detected the pressure fluctuation in the main tank 30, the signal component having the angular frequency ω ₀ is extracted by the bandpass filter 37b having the gain 1 and the central angular frequency ω ₀ , and thereafter. , And is supplied to the second amplitude detector 39b, and the amplitude is detected and output.

On the other hand, the output of the dynamic microphone 34a which has detected the pressure fluctuation of the correction tank 31 is the gain V
₁ , the bandpass filter 37a having the central angular frequency ω ₀ extracts only the signal component having the angular frequency ω ₀ by multiplying it by V ₁ , and then supplied to the first amplitude detector 39a to detect and output the amplitude. It

Thereafter, the amplitude output from the first amplitude detector 39a is divided by the amplitude output from the second amplitude detector 39b by the divider 40 to calculate the volume V ₂ of the hollow portion of the main tank 30. To be done.

Then, the calculation result is supplied to the subtractor 41 and subtracted from the set total volume of the main tank 30, and as a result, the volume of the liquid stored in the main tank 30 is calculated. .

Further, FIG. 4 shows, for example, Japanese Patent Laid-Open No. 3-48124.
It is a block diagram which shows the other conventional volume measuring apparatus shown by the publication, the same code | symbol is attached | subjected to the same component as what is shown in FIG. 3, and the overlapping description is abbreviate | omitted. Reference numeral 50 is an oscillator that outputs a signal, and is a speaker 3 that is volume changing means.
Drive 3

Reference numeral 51 denotes a phase difference detection circuit, which is an oscillator 5
The phase difference between the output signal from 0 and the detection signal output from the first microphone 34a is detected. Reference numeral 52 denotes a phase matching circuit, which matches the phase of the output signal of the oscillator 50 with the phase difference of the detection output from the phase difference detecting circuit 51.

Further, 53 is a first multiplier, which multiplies the detection output of the first microphone 34a and the output of the phase matching circuit 52. Reference numeral 54 denotes a first zero-cross detection circuit, which outputs an integration start signal at a zero-cross at a certain point of the detection signal of the first microphone 34a, and then outputs n.
An integration end signal is output at the zero cross after the predetermined time t of the first time.

Reference numeral 55 denotes a first output from the first multiplier 53.
This is a first integrator which outputs an amplitude value by integrating based on the integration start signal and the integration end signal from the zero-cross detection circuit 54. The first integrator 55 outputs the integrated output until the integration end signal comes. Not.

Numeral 56 is an inverting circuit for inverting the output from the phase matching circuit 52, and numeral 57 is a second multiplier.
It has the same function as the multiplier 53. A second zero-cross detection circuit 58 has the same function as the first zero-cross detection circuit 54.

Further, reference numeral 59 is a second integrator, which has the same function as the first integrator 55 and has the second zero-cross detection circuit 5.
When the integration end signal is supplied from 4, the integration is stopped and the amplitude value is output. Reference numeral 40 is the divider for dividing the outputs of the integrators 55 and 59 to obtain the volume of the hollow portion of the main tank 30.

In such a volume measuring device, the oscillator 50
Supplies the output signal to the speaker 33 to drive the speaker 33. Further, with the output of the oscillator 50 as a reference, the phase difference between the detected output from the first microphone 34a is detected by the phase difference detection circuit 51, and the output from the oscillator 50 is detected based on the detected phase difference. , Correct the phase and output.

The corrected signal is multiplied by the detection signal from the first microphone 34a in the first multiplier 53 and supplied to the first integrator 55 to start the integration from the first zero-cross detection circuit 54. The integration is started based on the signal, and after the predetermined time t, the integration is ended based on the integration end signal from the first zero-cross detection circuit 54, and the integrated value in the meantime is obtained.

On the other hand, the output of the phase matching circuit 52 is inverted by the inverting circuit 56, and the output thereof is output by the second microphone 34.
The detection signal from b is multiplied by the second multiplier 57,
It is supplied to the second integrator 59 to start the integration based on the integration start signal from the second zero-cross detection circuit 58, and then ends the integration based on the integration end signal after a predetermined time t to obtain the integrated value. . Then, each of these integrated values is divided by the divider 40.

[0022]

However, in the volume measuring device described in Japanese Patent Laid-Open No. 2-206723, the amplitude detection of the output signals of the dynamic microphone 34a and the condenser microphone 34b through the bandpass filters 37a, 37b. When the main tank 30 is used as a fuel tank of an automobile, for example, the tank generated during traveling is input to the containers 39a and 39b and the obtained amplitude value is divided to measure the volume. Due to the pressure noise (which includes frequency components other than the drive signal), the measured value becomes inaccurate, and the circuit becomes complicated and costly.

Further, in the volume measuring device described in Japanese Patent Laid-Open No. 3-48124, the microphones 34a, 34a,
Since the amplitude value of 34b is obtained and the volume is measured by this, it is particularly suitable for an automobile with a lot of tank pressure noise, but there is a problem that the circuit becomes complicated.

The present invention has been made by paying attention to the above-mentioned conventional problems. Even when it is applied to a fuel tank of an automobile in a noisy environment, it has a simple and low-cost structure and has a main structure. It is an object of the present invention to obtain a volume measuring device capable of accurately measuring the volume of a measured object in a tank.

[0025]

A volume measuring apparatus according to the present invention is installed between a main tank for accommodating an object to be measured and a correction tank, and changes the volumes of the correction tank and the main tank at a predetermined frequency. Volume changing means,
A first microphone and a second microphone for detecting the pressure fluctuation of each tank, and a first microphone for rectifying and smoothing a detection signal of the first microphone to detect an amplitude value.
And an amplitude detection circuit for detecting an amplitude value based on a correlation value of a detection signal of the second microphone and a signal for driving the volume changing means.
The output of the amplitude detection circuit and the output of the first amplitude detection circuit are divided by a division circuit, and the volume of the object to be measured can be measured based on the result of the division.

[0026]

In the volume measuring apparatus according to the present invention, the amplitude value of the output signal of the dynamic microphone in the correction tank is obtained from the signal obtained by rectifying the output signal by the rectifier circuit and smoothed by the smoothing circuit, and by the capacitor in the main tank. The amplitude value of the output signal of the microphone is detected by the correlation value with the drive signal from the oscillator, and both detected values are divided and subtracted from the tank volume to obtain the main tank such as gasoline to be measured. Makes it possible to measure the volume at.

[0027]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. Now, when considering a tank having a volume of 50 to 70 l for an automobile, when comparing the amplitudes of the microphone signal of the main tank 30 and the microphone signal of the reference tank (for example, 400 cc), for example, 125 times (50 l / 400 cc = 125).
Double).

Now, as the vehicle runs, the main tank 30
When pressure noise is generated in the inside due to the fluctuation of the fuel, the pressure noise is generated at the level of 1/10 to 1/3 of the microphone signal of the main tank 30, depending on the structure and material of the tank. Noise in the correction tank 31
However, the noise may be added to the microphone signal due to the noise as the sound caused by the vibration of the vehicle.

The level of this noise is 1/100 or less of the microphone signal, and the level of the correction tank 31 is low.
It is at a level that can be ignored compared to the internal pressure fluctuations. For this reason, the microphone signal amplitude detection circuit of the correction tank 31 can be realized by a simple circuit, that is, a full-wave rectification circuit and a smoothing circuit of the microphone signal, for example.

This will be specifically described with reference to FIG. In FIG. 1, reference numeral 1 is a double-wave rectifier circuit connected to a dynamic microphone 34a as a first microphone via an amplifier circuit 2.

Further, 3 is a smoothing circuit for smoothing the output rectified by the double-wave rectifying circuit 1, and the double-wave rectifying circuit 1 and the smoothing circuit 3 constitute a first amplitude detecting circuit 4. Reference numeral 5 is a divider for dividing each output of the first amplitude detection circuit 4 and a second amplitude detection circuit described later.

Further, 6 is a bandpass filter connected to a condenser microphone 34b as a second microphone, 7 is an output of the bandpass filter 6 and a signal for driving the volume changing means outputted by the oscillator 10 as a driving source. And a multiplier 8 that multiplies the output of the multiplier 7, and these constitute a second amplitude detection circuit 9.

Reference numeral 10 is an amplification circuit for amplifying the division calculation force in the divider 5 of each of the amplitude detection circuits 4 and 9, and 11 is the volume of the hollow portion of the main tank 30, which is the output of the amplification circuit 10, and the main tank 30. It is a subtractor that subtracts from the total volume of to obtain the volume of the measured object such as a substantial liquid.

Reference numeral 13 is a speaker amplifier for amplifying the output of the oscillator 10, and 14 is a speaker as the volume changing means driven by the output of the speaker amplifier 13.

Next, the operation will be described. First, since the correction tank 31 does not generate noise due to disturbance as described above, there is no need for a filter for noise removal or the like, and the output signal of the dynamic microphone 34a is directly amplified by the amplification circuit 2 and then amplified. , Is amplified by the both-wave rectifying circuit 1, is further smoothed by the smoothing circuit 3, and is input to the divider 5 for volume calculation.

On the other hand, the output signal from the condenser microphone 34b of the main tank 30 passes through a bandpass filter (which is adjusted to the same pass band frequency as the drive signal frequency) 6 having an amplifier built therein, and is driven by the oscillator 10. The signal is multiplied by the multiplier 7 to calculate the correlation value. Then, the correlation value is passed through the integrating circuit 8 to obtain the amplitude value of the signal output from the condenser microphone 34b.

Subsequently, the amplitude value obtained from the smoothing circuit 3 and the amplitude value output from the integrating circuit 8 on the main tank 30 side are divided by the divider 5 (volume ratio is calculated), Further, the divided calculation force is passed through the amplification circuit 10 having a gain corresponding to the correction tank 31, and the space (cavity) volume in the main tank is calculated.

After that, the space volume is reduced to the main tank 30.
Is subtracted from the total volume of
The liquid amount as the measured object in 0 is output as a measurement volume signal.

Example 2. In the first embodiment, the bandpass filter 6 is connected to the output side of the condenser microphone 34b of the main tank 30. The bandpass filter 6 multiplies the drive signal by the output signal of the condenser microphone 34b. Since the circuit that performs (the circuit that calculates the correlation value) functions as an ultra-narrow band filter, it does not have a role as a so-called bandpass filter but suppresses the peak value when large signal noise enters (frequency component). Has a role.

For this reason, for example, instead of the bandpass filter 6, an amplification circuit 20 having an amplification degree lower than that of the bandpass filter 6 is installed as shown in FIG. A simpler output signal processing circuit for the main tank 30 can be provided by installing an amplifier having the remaining amplification degree after the integration circuit 8 or the integration circuit 8.

As a result, it is possible to omit the frequency setting (adjustment) work by combining the resistors, capacitors, coils, etc. in the bandpass filter 6, and further, the amplifier in the latter stage of the multiplier 7 is replaced by the amplifier of the divider 5. If they are also used, the configuration can be further simplified.

[0042]

As described above, according to the present invention, the volume change is installed between the main tank for accommodating the object to be measured and the correction tank to change the volumes of the correction tank and the main tank at a predetermined frequency. Means, a first microphone and a second microphone for detecting pressure fluctuations in the tanks, and a first amplitude detection circuit for rectifying and smoothing a detection signal of the first microphone to detect an amplitude value, A second amplitude detection circuit for detecting an amplitude value based on the correlation value of the detection signal of the second microphone and the signal for driving the volume changing means is provided, and the output of the second amplitude detection circuit and the first amplitude detection circuit are provided. The output of the amplitude detection circuit is divided by a division circuit, and the volume of the measured object is measured based on the result of the division. A simple and addition can be reliably measured by the circuit configuration of the low cost, the effect is obtained that improves the assembling efficiency by reducing the adjustment locations or parts.

Further, by omitting the use of the bandpass filter and substituting it with an amplifier having a low amplification degree, it is possible to further simplify the configuration and reduce the cost by the frequency adjustment work and the number of parts. It is effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing a volume measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a volume measuring device according to another embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional volume measuring device.

FIG. 4 is a block diagram showing another conventional volume measuring device.

[Description of Codes] 4 First Amplitude Detection Circuit 9 Second Amplitude Detection Circuit 30 Main Tank 31 Correction Tank 33 Volume Change Means 34a Dynamic Microphone (First Microphone) 34b Condenser Microphone (Second Microphone)

Claims (1)

[Claims] 1. A volume changing means, which is installed between a main tank that stores an object to be measured and a correction tank that has a smaller volume than the main tank, and that changes the volume of the correction tank and the main tank at a predetermined frequency. A first microphone and a second microphone that detect pressure fluctuations in the correction tank and the main tank; and a first amplitude detection circuit that rectifies and smoothes a detection signal from the first microphone to detect an amplitude value. A second amplitude detection circuit for detecting an amplitude value based on a correlation value between a detection signal of the second microphone and a signal for driving the volume changing means, an output of the second amplitude detection circuit and the first amplitude A volume measuring apparatus comprising: a divider that divides the output of the detection circuit and that can measure the volume of the object to be measured based on the result of the division.