JPH06201434A - Volume detector - Google Patents

Abstract

PURPOSE:To enhance accuracy in measurement with no effect of the volume of an object to be measured contained in a tank. CONSTITUTION:A speaker 3 causes variation of the volume in main and correction tanks 1, 2. A first microphone 4 detects pressure variation in the main tank 1 and delivers a signal to a first bandpass filter 8. A second microphone 5 detects pressure variation in the correction tank 2 and delivers a signal to a second bandpass filter 9. The first and second bandpass filters 8, 9 discriminate signal components having predetermined frequencies from the input signal. An operating circuit 15 detects the amplitude of signal component and measures the volume of an object to be measured contained in the main tank 1 based on the amplitude thus detected. A feedback correction circuit 17 drives the speaker 3 such that the signal component having a predetermined frequency, contained in the signal delivered from the second microphone 5, has a constant amplitude.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume detecting device for detecting the volume of an object to be measured stored in a tank by utilizing the volume change.

[0002]

2. Description of the Related Art Conventionally, a mechanical type fuel gauge has been provided as a vehicle fuel gauge, for example. This one is
On the sender side, it is composed of a float, an arm and a sliding resistance part. As the float moves up and down along with the liquid level of the fuel, the resistance value of the sliding resistance part changes and the change is output to the receiver side. It has become.

However, the mechanical type as described above has a drawback that the fuel detection error is large depending on the inclination angle of the vehicle or the remaining amount of the fuel.

Therefore, in recent years, instead of the mechanical type, a type that electrically detects the remaining amount of the fuel has been considered. As a remaining amount detecting device of this type, JP-A-3-2000
There is one shown in Japanese Patent No. That is, as shown in FIG. 3, a correction tank 2 having a small volume is integrated in a connected state with a main tank 1 for storing an object to be measured. A speaker 3 as a volume changing means is provided between the main tank 1 and the correction tank 2, and a first microphone 4 as a first pressure detecting means is provided on the main tank 1 side. The second side is a second pressure detecting means
Microphone 5 is provided. The speaker driving circuit 6 uses the oscillation signal from the oscillation circuit 7 to drive the speaker 3
Are driven at a predetermined angular frequency ω 0.

The first bandpass filter 8 extracts a signal component of angular frequency ω 0 from the signal from the first microphone 4. The second bandpass filter 9 extracts a signal component obtained by multiplying the angular frequency ω0 by V1 from the signal from the second microphone 5. The first amplitude detector 10 is based on the output from the first bandpass filter 8 .gamma.P0 V0 /
V2 (P0: pressure of gas in main tank, V0: volume change by speaker, V2: volume of gas in main tank, γ: specific heat ratio of gas) is detected and output. The second amplitude detector 11 detects and outputs γP0 V0 based on the output from the second bandpass filter 9. Divider 1
2 divides the output γP0 V0 of the second amplitude detector 11 by the output γP0 V0 / V2 of the first amplitude detector 10. The subtractor 13 calculates the total volume VT of the main tank by the volume V2 of the hollow portion of the main tank 1 calculated by the divider 12.
Subtract from.

Next, a method for obtaining the volume of the object to be measured stored in the main tank 1 with the above configuration will be described.
The main tank 1 and the correction tank 2 are rigid bodies and do not distort when the main tank 1 and the correction tank 2 are pressurized or depressurized with the atmospheric pressure.
0 (t) is equal to the volume change amount V (t) that actually occurs.

Now, the speaker outputs V (t) = V0 sin ω0
When driven at t, the pressure in the main tank 1 is detected by the first microphone 4. The output from the first microphone 4 is input to the first bandpass filter 8 to detect the signal component of the angular frequency ω0. This first
The signal component of the angular frequency .omega.0 extracted by the band pass filter 8 is output by the first amplitude detector 10 as the amplitude value .gamma.P0 V0 / V2 corresponding to the signal component. Further, the pressure fluctuation of the correction tank 2 is detected by the second microphone 5. The output from the second microphone 5 is input to the second bandpass filter 9 and a signal obtained by multiplying the angular frequency ω0 by V1 is extracted. Then, the signal component obtained by multiplying the angular frequency .omega.0 by V1 by the second bandpass filter 9 is output by the second amplitude detector 11 as the amplitude value .gamma.P0 V0 corresponding to the signal component.

The divider 12 divides the output γP0 V0 from the second amplitude detector 11 by the output γP0 V0 / V2 from the first amplitude detector 10 to calculate the volume V2 of the cavity of the main tank 1. calculate. The subtractor 13 then calculates the total volume VT of the main tank from the V2 obtained by the divider 12.
Then, the volume VL of the object to be measured is obtained.

[0009]

However, in the case of the above-mentioned conventional structure, since the volume change by the speaker 3 is constant regardless of the volume of the object to be measured stored in the main tank 1, the object in the main tank 1 is fixed. The amplitude value of the signal component of the predetermined frequency included in the signal discriminated by the second bandpass filter 11 varies depending on the volume of the measurement object, and the amplitude value γP0 V0 which is a constant value varies under the same measurement condition. Therefore, there is a drawback that the measurement accuracy deteriorates.

Further, when the volume of the object to be measured stored in the main tank 1 becomes small, the volume change rate by the speaker 3 becomes small, so the amplitude of the signal from the first microphone 4 becomes small and S The / N ratio deteriorates, and in this case also, the measurement accuracy deteriorates.

The present invention has been made in view of the above circumstances, and an object thereof is to detect the volume of an object to be measured stored in a tank by utilizing pressure fluctuation, and the object to be measured stored in the tank. An object of the present invention is to provide a volume detection device capable of improving the measurement accuracy without being affected by the volume of.

[0012]

According to the present invention, there is provided a volume changing means for changing the volumes of a main tank and a correction tank, and a first pressure for outputting a signal indicating a pressure fluctuation of the main tank by the volume changing means. Detecting means is provided, and second pressure detecting means for outputting a signal indicating a pressure fluctuation of the correction tank by the volume changing means is provided, and a signal component of a predetermined frequency included in the signal from the first pressure detecting means is detected. A first frequency discriminating means for discriminating is provided, and a second frequency discriminating means for discriminating a signal component of a predetermined frequency included in the signal from the second pressure detecting means is provided, and the first and second frequency discriminating means are provided. Means for detecting the amplitudes of the signal components discriminated by the means and calculating the volume of the object to be measured stored in the main tank based on the respective amplitude values are provided, and the second pressure detection device is provided. Detecting the amplitude of a signal component of a predetermined frequency output from the unit, in which the amplitude value is provided a correction means for controlling the volume changing means so that the constant value.

A correction for detecting the amplitude of a signal component of a predetermined frequency output from the first pressure detecting means, and controlling the volume changing means such that the smaller the amplitude value, the larger the volume change. Means may be provided.

[0014]

According to the volume detecting apparatus of the first aspect, when the volume changing means changes the volumes in the main tank and the correction tank, a signal indicating the pressure in the main tank is output from the first pressure detecting means. In addition to being output, a signal indicating the pressure in the correction tank is output from the second pressure detecting means.

The signal from the first pressure detecting means is given to the first frequency discriminating means, and the signal component of a predetermined frequency is discriminated by the first pressure detecting means. Further, the signal from the second pressure detecting means is given to the second frequency discriminating means, and the signal component of the predetermined frequency is discriminated by the second pressure detecting means.

The calculating means detects the amplitude values of the signal components given from the first and second frequency discriminating means and, based on the respective amplitude values, the volume of the object to be measured stored in the main tank. Is calculated.

When the volume of the object to be measured stored in the main tank fluctuates, the amplitude of the signal component of the predetermined frequency contained in the signal from the second pressure detecting means, which is originally a constant value, fluctuates accordingly. I may end up doing it. At this time, since the correction means controls the correction means so that the amplitude value of the signal of the predetermined frequency from the second pressure detection means becomes constant, it is possible to prevent the calculation accuracy of the calculation means from being lowered.

According to the volume detecting device of the second aspect, when the volume of the object to be measured stored in the main tank becomes small, the amplitude of the signal of the predetermined frequency contained in the signal from the first pressure detecting means becomes small. Become. Then, the correction means controls the volume change means so that the volume change becomes large, so that it is possible to prevent the calculation accuracy of the calculation means from being lowered.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. 1. The same parts as those in FIG. 3 showing a conventional example are designated by the same reference numerals and the description thereof will be omitted. Only different parts will be described. explain. That is, the signal from the first microphone 4, which is the first pressure detecting means, is given to the first bandpass filter 8. Second microphone 5 as second pressure detecting means
Signal is applied to the second bandpass filter 9. The first and second bandpass filters 8 and 9 discriminate the signal components of a predetermined frequency contained in the input signal. The signal component discriminated by the first band-pass filter 8 is amplified by the amplifier 14 having an amplification factor of V1 and then given to the arithmetic circuit 15 as an arithmetic means. The signal component discriminated by the second bandpass filter 9 has an amplification factor of 1
It is amplified in 6 and then given to the arithmetic circuit 15.

The arithmetic circuit 17 is mainly composed of a CPU, an A / D converter, and a memory. The amplitude of the alternately input signal components is converted into a digital value by the A / D converter and stored in the memory. , Performs a predetermined calculation based on the digital value stored in the memory.

Feedback correction circuit 17 as correction means
Is an attenuator 18 based on the signal from the amplifier 16.
Adjust. The attenuator 18 adjusts the amplification factor of the signal from the oscillator 19 and outputs it to the power amplifier 20 for driving the speaker 3.

Next, the operation of the above configuration will be described. When the speaker 3 vibrates at the angular frequency ω 0, the main tank 1
The volume inside and in the correction tank 2 changes. Then, the pressure in the cavity in the main tank 1 and the pressure in the correction tank 2 change, and the signals indicating the changes are output from the first and second microphones 4 and 5.

The first and second bandpass filters 8 and 9 discriminate the signal component of the angular frequency ω 0 contained in the input signal. As a result, the amplitude of the signal discriminated by the first bandpass filter 8 becomes γP0 V0 / V2, and the amplitude of the signal discriminated by the second bandpass filter 9 becomes γP0 V0 / V2.
It becomes P0 V0.

Then, the arithmetic circuit 15 uses the A / D converter to convert the amplitude of the input signal into digital values γP0 V0 and γP0 V.
Converted to 0 / V2 and sequentially stored in memory. Subsequently, the arithmetic circuit 15 sets the amplitude value γP0 V0 stored in the memory to γ
The volume V2 of the hollow portion of the main tank 1 is obtained by dividing by P0 V0 / V2, and the volume V2 of the object to be measured stored in the main tank 1 is subtracted from the total volume VT of the main tank 1. Calculate VL.

Now, the volume in the correction tank 2 slightly changes according to the increase or decrease in the volume of the object to be measured stored in the main tank 1, and the angle included in the signal from the second microphone 5 accordingly. The amplitude of the signal component of frequency ω 0 fluctuates. Therefore, the amplitude of the signal component discriminated by the second bandpass filter 9 fluctuates, and the amplitude value γP0 V0 which is a constant value fluctuates under the same measurement conditions.

At this time, the feedback correction circuit 17
Controls the attenuator 18 to increase or decrease the volume change by the speaker 3 so that the amplitude value of the signal of the angular frequency ω0 output from the second microphone 5 becomes γP0 V0. This prevents the amplitude γP0 V0 of the signal component discriminated by the second bandpass filter 9 from fluctuating under the same measurement condition regardless of the volume of the object to be measured stored in the main tank 1. be able to.

According to the above configuration, when the amplitude of the signal component of the angular frequency ω0 output from the second microphone 5 changes, the feedback correction circuit 17 causes the speaker 3 to have a constant amplitude value. Since the volume change due to the measurement is adjusted, unlike the conventional example in which the volume change by the speaker is always constant regardless of the volume of the measured object stored in the main tank, the measured object stored in the main tank 1 It is possible to improve the measurement accuracy by preventing the influence of the volume change of the object.

FIG. 2 shows a second embodiment of the present invention,
The same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only different parts will be described. The difference between the second embodiment and the first embodiment is that the feedback correction circuit 21, which is the correction means, decreases as the amplitude value of the signal from the amplifier 14 for amplifying the signal from the first microphone 4 decreases. That is, the attenuator 18 is adjusted so that the volume change by the speaker 3 becomes large.

Further, a limiter 22 for receiving the signal from the amplifier 16 for amplifying the signal from the second microphone 5 is provided, and the limiter 22 provides a signal of the angular frequency ω 0 included in the signal from the second microphone 5. When the amplitude value of the component exceeds the set value, the feedback correction amount (amplification factor of the attenuator 18) is set not to exceed the amount of the set value.

Next, the operation of the above configuration will be described. When the volume of the object to be measured stored in the main tank 1 becomes small, the volume of the hollow portion in the main tank 1 becomes large. Therefore, the signal component of the angular frequency ω 0 included in the signal from the first microphone 4 is generated. The amplitude value of becomes smaller. At this time, the feedback correction circuit 21 adjusts the attenuator 18 and controls so that the volume change by the speaker 3 becomes large, so that the amplitude value of the signal component of the angular frequency ω 0 included in the signal from the first microphone 4 is large. Become.

According to the above structure, the main tank 1
When the volume of the DUT stored inside is low,
Since the volume change by the speaker 3 is increased accordingly, the S / N ratio is different from the conventional example in which the volume change by the speaker is always constant regardless of the volume of the object to be measured stored in the main tank. Can be improved to improve the measurement accuracy.

Further, as described above, the feedback correction circuit 21 controls the speaker 3 to increase the volume change, and as a result, the amplitude of the signal component of the angular frequency ω 0 included in the signal from the second microphone 5 becomes excessive. If it becomes larger than the usable range of the second microphone 5 (the range in which the relationship between the input and the output is linear), the limiter 22 stops the operation of the feedback correction circuit 21. Since this is done, the second microphone 5 is used in a range having excellent input / output characteristics, so that the measurement can be reliably performed.

In each of the above embodiments, the speaker 3 is used as the volume changing means, but instead of this, a piston, a bellows, or a diaphragm may be used. Further, instead of the first and second microphones 4 and 5, a pressure sensor may be used.

[0034]

As is apparent from the above description, the volume detecting device of the present invention has the following effects.

According to the volume measuring apparatus of the first aspect, the volume of the object to be measured stored in the main tank is changed with the volume of the main tank and the correction tank being changed by the volume changing means. For discriminating by a frequency discriminating means a signal component of a predetermined frequency output from the first and second pressure detecting means provided in, and measuring by an arithmetic means based on the amplitude value of the signal component, Correcting means for detecting the amplitude value of the signal component of the predetermined frequency output from the second pressure detecting means and controlling the volume changing means so that the amplitude value becomes the predetermined value is provided, and the correction value is stored in the main tank. Since the calculation error is reduced regardless of the volume change of the measured object, in the one that detects the volume of the measured object stored in the main tank using the pressure fluctuation, It is possible to improve the measurement accuracy regardless of the volume of the housing has been measured object to link.

According to the volume detecting device of the second aspect, the amplitude of the signal component of the predetermined frequency output from the first pressure detecting means is detected, and the smaller the amplitude value, the larger the volume change. The correction means for controlling the volume changing means is provided so as to improve the S / N ratio when the volume of the object to be measured stored in the main tank becomes small. Similar to the detection device, in detecting the volume of the measured object stored in the main tank by utilizing the pressure fluctuation, the measurement accuracy is improved without being affected by the volume of the measured object stored in the tank. be able to.

[Brief description of drawings]

FIG. 1 is an overall schematic view showing a first embodiment of the present invention.

FIG. 2 is an overall schematic diagram showing a second embodiment of the present invention.

FIG. 3 is an overall schematic diagram showing a conventional example.

[Explanation of symbols]

1 is a main tank, 2 is a correction tank, 3 is a speaker (volume changing means), 4 is a first microphone (first pressure detecting means), 5 is a second microphone (second pressure detecting means), 8 Is a first bandpass filter (first frequency discriminating means), 9 is a second bandpass filter (second frequency discriminating means), 15 is an arithmetic circuit (arithmetic means), and 17 is a feedback correction circuit (correction means). ) And 21 are feedback correction circuits (correction means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Nakano No. 1 Noda, Toyoda, Oguchi-cho, Niwa-gun, Aichi Prefecture Tokai Rika Electric Co., Ltd.

Claims (2)

[Claims] 1. A volume changing means for changing volumes of a main tank and a correction tank, a first pressure detecting means for outputting a signal indicating a pressure fluctuation of the main tank by the volume changing means, and a volume changing means. Second pressure detecting means for outputting a signal indicating the pressure fluctuation of the correction tank; first frequency discriminating means for discriminating a signal component of a predetermined frequency contained in the signal from the first pressure detecting means; Second frequency discriminating means for discriminating a signal component of a predetermined frequency contained in the signal from the second pressure detecting means, and detecting the amplitudes of the signal components discriminated by the first and second frequency discriminating means, A calculation means for calculating the volume of the object to be measured stored in the main tank based on the respective amplitude values, and the amplitude of the signal component of a predetermined frequency output from the second pressure detection means. And a correcting means for controlling the volume changing means so that the amplitude value becomes a constant value. 2. A volume changing means for changing the volumes of the main tank and the correction tank, a first pressure detecting means for outputting a signal indicating a pressure fluctuation of the main tank by the volume changing means, and the volume changing means. Second pressure detecting means for outputting a signal indicating the pressure fluctuation of the correction tank; first frequency discriminating means for discriminating a signal component of a predetermined frequency contained in the signal from the first pressure detecting means; Second frequency discriminating means for discriminating a signal component of a predetermined frequency contained in the signal from the second pressure detecting means, and detecting the amplitudes of the signal components discriminated by the first and second frequency discriminating means, An arithmetic means for calculating the volume of the object to be measured stored in the main tank based on the respective amplitude values; and an amplitude of a signal component of a predetermined frequency output from the first pressure detecting means. And a correcting means for controlling the volume changing means so that the volume change increases as the amplitude value decreases.