JPH06201433A - Volume detector - Google Patents

Abstract

PURPOSE:To enhance accuracy in measurement with no ill effect of the variation of characteristics of components. CONSTITUTION:A speaker 3 causes variation of the volume of main and correction tanks 1, 2. A first microphone 4 detects pressure variation in the main tank 1 and delivers a signal to a multiplexer 15. A second microphone 5 detects pressure variation in the correction tank 2 and delivers a signal to the multiplexer 15. The multiplexer 15 switches the input signal and delivers an output to a bandpass filter 8. The bandpass filter 8 discriminates a signal component having a predetermined frequency from the input signal. An operating circuit 17 switches the multiplexer 15 and detects the amplitude of a signal component received from the bandpass filter 8 and then measures the volume of an object contained in the main tank 1 based on the amplitude thus detected.

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 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. 2, 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 1, the first microphone 4 detects the pressure fluctuation in the main tank 1. The output from the first microphone 4 is the first bandpass filter 8
Is input to and the signal component of the angular frequency ω 0 is detected. The signal component of the angular frequency ω0 extracted by the first bandpass filter 8 is output by the first amplitude detector 10 as an amplitude value γP0 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 ω0 by V1 by the second bandpass filter 9 is output by the second amplitude detector 11 as the amplitude value γP0 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.

By the way, in the above-mentioned configuration, the second bandpass filter 9 having an amplifying function is used, but the present inventor provides an amplifier on the input side of the second bandpass filter 9. As the band pass filter 9, a prototype having only the frequency discriminating function was manufactured. Therefore, the first
As the band pass filter 9 of, the one having the same characteristics as the second band pass filter 8 is used.

[0010]

However, in the case of the above-mentioned conventional configuration, the characteristics of the first and second bandpass filters 8 and 9 are required to be completely the same, but the characteristics of both are different. The reality is that The factors that cause such fluctuations in the characteristics are the error in the resonance frequency of the bandpass filters 8 and 9 and the difference in the characteristics of the bandpass filters 8 and 9 due to temperature fluctuations There are differences in the temperature characteristics of.

Therefore, although it is important to manufacture the bandpass filters 8 and 9 having the same characteristics and to make the characteristics of both match, the characteristics of the bandpass filters 8 and 9 vary from one part to another and the measurement accuracy deteriorates. There is a drawback that it will end up.

The present invention has been made in view of the above circumstances. An object of the present invention is to detect the volume of an object to be measured stored in a tank by utilizing the pressure fluctuation, and it is affected by the characteristic fluctuation of parts. It is to provide a volume detection device that can improve the measurement accuracy without the need.

[0013]

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.
The signal selection means for selecting one of the signals from the second pressure detection means is provided, and the frequency discrimination means for discriminating the signal component of the predetermined frequency contained in the signal selected by the signal selection means is provided, and the signal selection is performed. While switching the means,
An arithmetic means is provided for detecting the amplitude of the signal component discriminated by the frequency discriminating means and calculating the volume of the object to be measured stored in the main tank based on the respective amplitude values.

[0014]

When the volume changing means changes the volume in the main tank and the correction tank, the first pressure detecting means outputs a signal indicating the pressure in the main tank, and
A signal indicating the pressure in the correction tank is output from the second pressure detection means.

Now, the arithmetic means applies the signal from the first pressure detecting means to the frequency discriminating means by switching the signal selecting means. Thereby, the frequency discriminating means discriminates the signal component of the predetermined frequency contained in the signal from the first pressure detecting means. Subsequently, the arithmetic means applies the signal from the second pressure detecting means to the frequency discriminating means by switching the signal selecting means. Thereby, the frequency discriminating means discriminates the signal component of the predetermined frequency contained in the signal from the second pressure detecting means.

Then, the calculating means detects the amplitude of the signal component given from the frequency discriminating means and calculates the volume of the object to be measured stored in the main tank based on each amplitude value.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1. The same parts as those in FIG. 2 showing a conventional example are designated by the same reference numerals and the description thereof will be omitted, and only different parts will be described. To do. That is, the signal from the first microphone 4 which is the first pressure detecting means is given to the multiplexer 15 which is the signal selecting means through the amplifier 14 whose amplification factor is set to V1. Second microphone 5 as second pressure detecting means
The signal from is supplied to the multiplexer 15 through the amplifier 16 having an amplification factor of 1. This multiplexer 1
5 selects signals from the first and second microphones 4 and 5. The bandpass filter 8 discriminates a signal component of a predetermined frequency contained in an input signal and is an arithmetic circuit 1 serving as arithmetic means
Output to 7.

The arithmetic circuit 17 is mainly composed of a CPU, an A / D converter and a memory, and the multiplexer 1
5 is provided so as to be switched at an appropriate timing, and the signal input according to the switching timing is converted into a digital value by the A / D converter and stored in the memory, and a predetermined value is set based on the digital value stored in the memory. Perform an operation.

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.

Now, the arithmetic circuit 17 includes the multiplexer 1
The signal from the first microphone 4 is input to the bandpass filter 8 by switching the switch 5. As a result, the bandpass filter 8 has the angular frequency ω included in the input signal.
Discriminate 0 signal components. At this time, since the amplification factor of the amplifier 14 is set to V1, the bandpass filter 8
The amplitude of the signal discriminated by is γP0 V0 / V2. The arithmetic circuit 17 then A / Ds the amplitude γP0 V0 / V2 of the signal component input through the multiplexer 15.
The data is converted into digital data by the converter and stored in the memory.

Further, the arithmetic circuit 17 includes the multiplexer 1
The signal from the second microphone 5 is input to the bandpass filter 8 by switching the switch 5. As a result, the bandpass filter 8 has the angular frequency ω included in the input signal.
Discriminate 0 signal components. At this time, since the amplification factor of the amplifier 14 is 1, the amplitude of the signal discriminated by the bandpass filter 8 becomes .gamma.P0 V0. Then, the arithmetic circuit 17 digitally converts the amplitude γP0 V0 of the signal component input through the multiplexer 15 by the A / D converter and stores it in the memory.

Subsequently, the arithmetic circuit 18 obtains the volume V2 of the hollow portion of the main tank 1 by dividing the amplitude value γP0 V0 stored in the memory by γP0 V0 / V2, and also calculates the volume from the total volume VT of the main tank 1. The volume VL of the object to be measured stored in the main tank 1 is obtained by subtracting V2.

According to the above configuration, the bandpass filter 8 for discriminating the signal component of the angular frequency ω 0 contained in the signals from the first and second microphones 3 and 4 is commonly used. Even if the characteristics of the bandpass filter 8 fluctuate due to the temperature characteristics, the fluctuation can be invalidated by the division by the arithmetic circuit 17. Therefore, as compared with the conventional example that uses two bandpass filters requiring the same characteristics, the measured object stored in the main tank 1 is not affected by the characteristic fluctuation of the bandpass filter 8. The volume can be detected accurately.

Although the speaker 3 is used as the volume changing means in the above embodiment, a piston, a bellows, or a diaphragm may be used instead. Further, instead of the first and second microphones 4 and 5, a pressure sensor may be used.

[0025]

As is apparent from the above description, according to the volume detecting apparatus of the present invention, the volume of the object to be measured stored in the main tank is changed by the volume changing means between the main tank and the correction tank. In this state, the frequency discriminating means discriminates the signal component of the predetermined frequency output from the first and second pressure detecting means provided in the main tank and the correction tank, and calculates based on the amplitude value of the signal component. Since the influence of the characteristic variation of the frequency discriminating means is canceled by using the frequency discriminating means in common, the volume of the object to be measured stored in the tank can be measured by the pressure variation. In the case of using and detecting, there is an excellent effect that the measurement accuracy can be improved without being affected by the characteristic variation of the parts.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram showing an embodiment of the present invention.

FIG. 2 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 bandpass filter (frequency discrimination means), 1
Reference numeral 5 is a multiplexer (signal selecting means), and 17 is an arithmetic circuit (arithmetic 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 (1)

[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 detection means for outputting a signal indicating the pressure fluctuation of the correction tank, signal selection means for selecting one of the signals from the first and second pressure detection means, and selection by this signal selection means A frequency discriminating means for discriminating a signal component of a predetermined frequency contained in the signal, and an amplitude of the signal component discriminated by the frequency discriminating means, which is provided to switch the signal selecting means,
A volume detecting device, comprising: an arithmetic means for calculating the volume of the object to be measured stored in the main tank based on the respective amplitude values.