JPH0614926U - Volume measuring device - Google Patents

Abstract

(57) [Summary] A microphone air chamber is formed between a vibration plate to which a piezoelectric element is attached and a printed circuit board, and a microphone provided with a communication hole for communicating the microphone air chamber with the outside is provided.
A microphone capable of improving durability and reliability by communicating an air chamber of the microphone with the inside of the main tank or the correction tank through the communication hole so that an abnormal pressing force on the diaphragm of the microphone is not applied. It is to provide a volume measuring device equipped with.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention changes the volume (volume) of the liquid contained in the tank by changing the volumes of the first and second microphones respectively provided in the main tank and the correction tank, and the main tank and the correction tank. The present invention relates to a volume measuring device for measuring using a volume changing means.

[0002]

[Prior art]

 A volume measuring device of this type has been applied, for example, in Japanese Patent Application No. 1-27808 (Japanese Patent Application Laid-Open No. 2-20723). In order to facilitate understanding of the present invention, the basic structure of the volume measuring device of the above application will be described with reference to FIG.

Reference numeral 1 is a speaker (volume changing means), and an oscillator 3 is connected to the volume changing means via an amplifier 2. The volume changing means partitions the main tank 4 and the correction tank 5. Further, a condenser microphone (first microphone) 6 is provided on the main tank 4 side, and a dynamic microphone (second microphone) 7 having lower sensitivity than the first microphone is provided on the correction tank 5 side. Has been. (Note that the second microphone may be configured to have a sensitivity equivalent to that of a dynamic microphone by attaching, for example, a tape having fine holes to the entire receiving surface of the condenser microphone.) The speaker 1 is driven at a predetermined angular frequency ω ₀ .

Here, the volume of the correction tank 5 is V ₂ , the volume of the gas in the main tank 4 is V ₁ , the volume of the liquid in the main tank 4 is V _L , and the volume of the gas in the main tank 4 is V ₁ . the sum of the volume V _L of the liquid in the main Ntanku 4 and V _T (total volume of the main tank 4).

The pressure change ΔP ₂ (t) in the correction tank 5 is

[0006]

[Equation 1]

[0007]

Further, the pressure change ΔP ₁ (t) in the main tank is

[0009]

[Equation 2]

[0010]

Assuming that the amplitude value of the pressure change in the correction tank 5 is A ₂ and the amplitude value of the pressure change in the main tank 4 is A ₁ , the ratio of these amplitude values is given by the equations (3a) and (3b).

[0012]

[Equation 3]

[0013]

From this

[0015]

[Equation 4]

Therefore, the volume V _L of the liquid stored in the main tank 4 is

[0017]

[Equation 5]

It becomes

It should be noted that ΔV is obtained in advance by experiments.

Next, a specific embodiment according to the present invention will be described based on the above principle.

A speaker (volume change means) 1 is placed between the correction tank 5 and the main tank 4. Further, in order to equalize the static pressures of the main tank 4 and the correction tank 5, both tanks 5, 4 are arranged. The main tank 4 and the correction tank 5 are connected to each other by a thin pipe 14 having an orifice 13 so that the main tank 4 and the correction tank 5 are substantially completely closed so as not to be affected by atmospheric pressure. Since the frequency ω ₀ is very large compared to the slow change of the atmospheric pressure and the fluid resistance in the ventilation hole 15 is very large, it seems that the ventilation hole 15 is blocked while the speaker 1 is driven. Since it operates, the atmospheric pressure inside the tanks 4 and 5 is not affected by the atmospheric pressure difference inside and outside the tanks 4 and 5. Here, the time constant of the pressure transmission of the pipe 14 is sufficiently larger than the time constant of the pressure change of the correction tank 5 by the speaker 1, and the time constant of the atmospheric pressure outside the tanks 4 and 5, that is, the pressure change time of the absolute pressure. If the speaker 1 is driven at an angular frequency ω ₀ , the pressure change ΔP ₂ (t) in the correction tank 5 is

[0022]

[Equation 6]

It becomes When the main tank (4) is rigid, the pressure change ΔP ₁ (t) is as follows.

[0024]

[Equation 7]

It becomes

[0026] That is, the speaker 1, the volume of each of the main tank 4 and the correction tank 5 v ₀ sinω ₀ t is regularly varied only the angular frequency omega _0, the correction tank 5 main tank 4 The respective pressure fluctuations of are detected by the condenser microphone 6 and the dynamic microphone 7 attached to the respective tanks 4 and 5, and the output of the condenser microphone 6 which has detected the pressure fluctuations of the main tank 4 is gain 1, center angular frequency. signal component of omega angular frequency omega ₀ by a band-pass filter 8 of ₀ is extracted, then fed to a second amplitude detector 9,

[0027]

[Equation 8]

Is detected and output. The output of the dynamic microphone 7 which has detected the pressure fluctuation in the correction tank 5 is extracted by multiplying the signal component of the angular frequency ω ₀ by V ₁ by the bandpass filter 10 having the gain V ₁ and the central angular frequency ω _0. Then, it is supplied to the first amplitude detector 11, and γP ₀ v ₀ is detected and output. After that, the output γP ₀ v ₀ from the first amplitude detector 11 is the output from the second amplitude detector 9.

[0029]

[Equation 9]

The gas volume V of the main tank 4 is divided by the divider 12 by₁ Is calculated, and the calculation result is supplied to the subtractor 24, and the total volume V of the set main tank 4 is calculated. _T Volume V of the liquid or the like stored in the main tank 4 as a result_L Is calculated.

[0031]

[Problems to be solved by the device]

 However, as shown in FIG. 2, the structure of the first microphone 6 and the second microphone 7 used in the volume measuring device having the above-described configuration is as shown in FIG. The peripheral portion of the vibration plate 18 in which the piezoelectric element 17 is appropriately fixed by an adhesive is fixedly held by the support member 19, and the circuit element 20 is wired inside the other side opening of the case 16. The peripheral edge of the printed circuit board 21 is fixed. A microphone air chamber 22 is formed between the diaphragm 18 and the printed circuit board 21, and the microphone air chamber 22 has a structure in which an orifice 23 provided in the printed circuit board 21 communicates with the outside of the microphone, that is, the atmosphere. Therefore, for example, when an object to be measured such as fuel contained in the main tank 4 becomes high in temperature due to an increase in temperature and the pressure in the main tank is increased, the diaphragm of the microphone is oscillated. Since 18 is subjected to a pressing action from the direction of the arrow in FIG. 2, there is a problem that the sensitivity of the diaphragm 18 is reduced due to the pressing action, and the reliability and durability of the measurement deteriorate. .

[0032]

[Means for Solving the Problems]

 The present invention has been made in view of such a conventional problem, and a microphone air chamber is formed between a vibration plate on which a piezoelectric element is attached and a printed circuit board, and a communication for connecting the microphone air chamber to the outside is provided. A microphone provided with a hole is provided, and the air chamber of the microphone is connected to the inside of the main tank or the correction tank through the communication hole so that an abnormal pressing force on the diaphragm of the microphone is not applied. , To provide a volume measuring device equipped with a microphone capable of enhancing durability and reliability.

[0033]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. As the microphone that can be used in this volume measuring device, any one of a condenser microphone, a dynamic microphone, and a ceramic microphone can be selectively used, but in this embodiment, the ceramic microphone is used as an example. explain.

In FIG. 3, reference numeral 30 denotes a microphone used in the above-mentioned volume measuring device, 31 denotes a cylindrical microphone case with both ends open, and the inside of the opening on one side of the cylindrical microphone case 31. The peripheral portion of the vibration plate 33 to which the piezoelectric element 32 is fixed by an adhesive is airtightly fixed and held by the support member 34. Inside the opening on the other side of the case 31, a peripheral portion of a printed circuit board 36 in which the same circuit element 35 as that described in the conventional example is arranged is airtightly fixed. Therefore, the diaphragm 33 and the printed circuit board 3 are fixed. The microphone air chamber 37 is formed between the microphone air chamber 37 and the microphone 6. Further, the microphone case 31 and the support member 34 are provided with a communication hole 38 for communicating the microphone air chamber 37 with the outside.

In order to install the two microphones 30 having such a structure in the volume measuring device, as shown in FIG. 4, the main tank 4 and the correction tank 5 are separately formed on the partition wall 39, which is located in the main tank 4. The first microphone 30-1 and the second microphone 30-2 positioned in the correction tank 5 are fixed back-to-back, and the communication provided in the first microphone 30-1 is established. The hole 38 is located in the main tank 4 and the communication hole 38 provided in the second microphone 30-2 is located in the correction tank 5.

As described above, in the present embodiment, the communication holes 38 provided in the microphones 30-1 and 30-2 provided on the main tank 4 side and the correction tank 5 side of the volume measuring device are Since the microphones 30-1 and 30-2 are opened inside the main tank 4 and the correction tank 5, the internal pressures of the main tank and the correction tank are substantially equal to each other. In addition, even if the atmospheric pressure in the main tank and the correction tank fluctuates, the diaphragm 33 of each microphone is not pressed, and an effective vibration action is generated, resulting in reliability and durability. An excellent volume measuring device can be provided.

[0037]

[Effect of device]

 As described above, the present invention is interposed between the main tank 4 and the correction tank 5 having a volume smaller than that of the main tank, and each volume of the main tank and the correction tank can be varied at a predetermined frequency. Volume changing means 1, first microphone 30-1 for detecting pressure fluctuation in the main tank, second microphone 30-2 for detecting pressure fluctuation in the correction tank, and first microphone Of the second amplitude detection circuit 11, a second amplitude detection circuit 11 for detecting the amplitude value of the detection signal of the second microphone, a second amplitude detection circuit 11 for detecting the amplitude value of the detection signal of the second microphone, And a divider 12 that divides the output by the output of the first amplitude detection circuit, and measures the volume of the DUT stored in the main tank based on the output of the divider. Device smell The two microphones 30-1 and 30-2 described above have a communication hole 38 that connects the air chamber of the microphone and the outside of the microphone, and the communication hole 38 has a volume that is opened in the correction tank or the main tank. Since this is a measuring device, the main tank 4 side and the correction tank 5 side of the volume measuring device are provided with communication holes 38 provided in the microphones 30-1 and 30-2, respectively. 4. Since the opening is made inside the correction tank 5, the internal pressures of the main tank and the correction tank are approximately equal to the internal pressure and the external pressure of the microphones 30-1 and 30-2. Even if the atmospheric pressures in the main tank and the correction tank fluctuate, the diaphragm 33 of each microphone is not pressed, and effective vibration action is generated, so that the reliability and durability are improved. Effect there Ru that excellent volumetric measuring device can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the overall structure of a volume measuring device.

FIG. 2 is an explanatory view of a conventional microphone structure used in a volume measuring device.

FIG. 3 is an explanatory view of the configuration of the microphone according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a main part structure of a volume measuring device to which a microphone according to an embodiment of the present invention is attached.

[Explanation of symbols]

 30 ... Microphone 31 ... Microphone case 32 ... Piezoelectric element 33 ... Vibration plate 34 ... Support member 35 ... Circuit element 36 ... Printed circuit board 37 ... Microphone air chamber 38 ... Communication hole

Claims (1)

[Scope of utility model registration request] 1. A main tank (4) and a correction tank (5) having a volume smaller than that of the main tank are interposed, and the respective volumes of the main tank and the correction tank are varied at a predetermined frequency. Volume changing means (1), a first microphone (30-1) for detecting a pressure fluctuation in the main tank, and a second microphone (30-2) for detecting a pressure fluctuation in the correction tank. A first amplitude detection circuit (9) for detecting the amplitude value of the detection signal of the first microphone, and a second amplitude detection circuit (11) for detecting the amplitude value of the detection signal of the second microphone. A divider (12) that divides the output of the second amplitude detection circuit by the output of the first amplitude detection circuit, and is stored in the main tank based on the output of the divider. A body for measuring the volume of a measured object In the product measuring device, the two microphones (30-1) and (30-2) are communication holes (3) that connect an air chamber of the microphone and the outside of the microphone.
8), and the communication hole (38) is opened in the correction tank or the main tank.