JPH0829232A - Gas type volume meter - Google Patents

Abstract

PURPOSE:To measure the volume of an object in container located closer to a heat source or the volume of a container at a narrow location by connecting a reference container, a measurement head for differentially giving an alternate volume change to an auxiliary container, and a measurement container and then obtaining the ratio of the pressure changes of both containers. CONSTITUTION:A reference container 1 and an auxiliary container 2 are in contact via a partition 4 and the partition 4 is provided with a speaker 6 for giving an alternate volume change. When an alternate drive signal such as a sinusoidal wave is given from a signal generator 16 via a conductor 10, a diaphragm 7 of the speaker 6 vibrates and volume changes whose absolute values are differentially equal and signs are opposite are given to the containers 1 and 2. The alternate pressure change of the containers 1 and 2 which are generated by the volume change are detected by microphones 11 and 12 being provided at the containers 1 and 2 and are inputted to a signal processing device 15. The volume of an object 8 loaded into a measuring instrument 3 or that of the measuring instrument 3 is obtained according to the ratio of the changes in two pressures by a signal processing device 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume meter for measuring the volume of a container having a complicated shape or the volume of an object having a complicated shape, and more particularly to a volume meter of the type utilizing the pressure change of gas in the container.

[0002]

2. Description of the Related Art As one method for measuring the volume of a container having a complicated shape, a sound source such as a speaker gives an alternating volume change to a space inside the container to adiabatically expand the gas therein. There is a method in which the volume of the container is obtained from the change in pressure at any time regardless of its shape.

As one of the measuring methods of this type, the applicants of Japanese Patent Publication No. 2-33084 and Japanese Patent Laid-Open No. 5223616 (hereinafter, these two are referred to as inventions of the prior application) describe a reference container and a measuring container. An alternating volume change is differentially applied to both sides, and the magnitude of the alternating volume change is calculated from the ratio of the magnitudes of the pressure changes of the gas in these containers that occur at that time, that is, the ratio of the sound pressure. Irrelevantly and without being influenced by the static pressure of gas, a gas volume meter for measuring the volume of a measuring container or the volume of an object put therein is shown.

[0004]

In order to measure changes in various properties of plastics due to temperature, the sample is placed in a measuring container and heated while being heated from the surroundings by infrared rays or the like. When the volume meter of the invention of the previous application is used for measuring the volume change, the heating temperature cannot be raised so much because the distance between the measurement container and the speaker of the sound source is short.

In the automobile industry and the like, there are many demands for measuring the internal volume of a cylinder without disassembling the engine. The measuring container in this case is a space formed by a cylinder and a piston, and the measured amount is the volume of the space. To apply the invention of the previous application to this, let's connect a volume meter to the ignition plug hole of the engine. In this case, however, the valve mechanism around the spark plug hole becomes an obstacle and the volume meter cannot be connected.

[0006]

According to one embodiment of the volume meter of the present invention, there is provided a measuring container including a reference container, an auxiliary container, a speaker for differentially applying an alternating volume change to these two containers, and a measuring container. Are connected by a connecting pipe, and the pressure change due to the alternating volume change is transmitted to the inside of the measuring container through the connecting pipe. Then, the volume of the measurement container or the volume of the object placed in the measurement container is obtained from the ratio of the magnitude of the pressure change inside the reference container and the auxiliary container.

[0007]

In this way, the speaker of the measuring head, the microphone for detecting the internal pressure change, and the like are separated from the measuring container by the connecting pipe, so that the temperature hardly rises even when the measuring container is heated. Therefore, it is possible to measure the volume change of a sample such as plastic placed in a measuring container over a wide temperature range.
Also in the above-mentioned cylinder internal volume measurement, the volume can be measured by sending a pressure change into the cylinder through a connecting pipe connected to the spark plug hole. However, in the volume meter of the present invention, the action of the inertia of the gas inside the connecting pipe must be taken into consideration, so it is necessary to use a measurement formula based on a new theory of operation, which is different from the invention of the previous application.

[0008]

[First Embodiment] In FIG. 1, reference numeral 1 is a reference container having a volume of V ₁ , 2 is an auxiliary container having a volume of V ₂ , both of which are in contact with each other through a partition wall 4, and 4 is an alternate container for these containers. A speaker 6 is provided as a means for giving a volume change, and when an alternating drive signal such as a sine wave is applied from a signal generator 16 through a lead wire 10 and a terminal 17, a speaker diaphragm 7 is provided.
Vibrates, and a volume change is differentially applied to the containers 1 and 2. That is, the containers 1 and 2 are given a volume change having the same absolute value and opposite signs. Due to this volume change, an alternating pressure change, that is, a sound pressure is generated inside the containers 1 and 2, but a microphone 11 is attached to the container 1 as a means for detecting the pressure change, and the sound pressure inside 1 is The signal is detected by 11, converted into an electric signal e ₁ and input to the signal processing device 15. Similarly, the sound pressure inside the container 2 is detected by the microphone 12 and converted into an electric signal e ₂ to be another input to the signal processing device 15.

A capillary tube 5 also penetrates through the partition wall 4,
Through this, the static pressures inside the containers 1 and 2 are in equilibrium.
However, due to the viscous resistance of the gas, the volume of gas passing through 5 in response to the above-mentioned alternating volume change is so small that it can be ignored. In order to promote the homogenization of the gas in the container, the capillary tube 5 can be replaced with a tube having a larger inner diameter, but even in this case, the volume of gas flowing into the tube and the volume of gas flowing out of the tube are Since they are equal, there is no change in the assumption that containers 1 and 2 are given a volume change of equal absolute value and opposite sign. Furthermore, in an actual volume measuring device, the static pressure inside the containers 1 and 2 is usually equal to the external atmospheric pressure through the gap of the assembled device, and therefore the capillary tube 5 is normally set. There is no need to provide anything special.

Reference numeral 9 is a connecting pipe, one end of which is connected to the auxiliary container 2,
The other end is connected to the measuring container 3 having a volume of V _{3 and} connects the internal spaces of these two containers. An object 8 to be measured having a volume V is placed inside the container 3. Therefore container 3
The volume of the internal clearance, that is, the extra product V _X is V ₃ −V. In addition, even if it seems that one end of the connecting pipe 9 is directly connected to the speaker 6 without the auxiliary container 2 in appearance,
Since the space in front of the diaphragm 7 of the speaker serves as an auxiliary container, V ₂ never becomes zero.

FIG. 2 is an equivalent circuit of the acoustic system of the apparatus of FIG.
C ₁ = V ₁ / γP ₀ , C ₂ = V ₂ / γP ₀ , C _X = V _X
/ ΓP ₀ , L = ρh / S. Here, γ is the specific heat ratio of the gas in the container, P ₀ is the static pressure in the container and is usually equal to atmospheric pressure. ρ is the density of the gas in the container, h and S are the length and internal cross-sectional area of the connecting pipe 9, respectively. The speaker 6 is represented by an AC signal power supply SPK. Also microphone 11
And 12 output signals respectively corresponding to the terminal voltage e ₂ of the terminal voltage e ₁ and capacitor C ₂ of the capacitor C ₁ of the.

Here, the impedance when looking leftward from the power source SPK is represented by Z ₁ , and the impedance when looking rightward is represented by Z ₂ . The amplitude E ₁ is taken as the quantity representing the magnitude of e ₁ and its amplitude E _{2 is} taken as the quantity representing the magnitude of e ₂ , and the ratio E ₁ / E ₂ is represented by R as follows. become.

[Equation 1]

Here, ω is the angular frequency of the AC signal power source SPK, that is, the angular frequency of the alternating volume change given by the speaker 6. Solving the above equation for C _X gives:

[Equation 2]

However, R ₀ is R when C _X = 0, that is, R when V _X = 0, and is equal to C ₂ / C ₁ . Also,

(Equation 3)

This is nothing but the angular frequency of resonance of the system constituted by the container 2 and the connecting pipe 9.

Rewriting (Equation 2) into an expression representing the co-product V _X is as follows. The graph is as shown in FIG.

[Equation 4]

In the above equation, R ₀ , V ₂ , and (ω / ω ₂ ) ²
Coefficients are included. As described above, R ₀ is V _X
Since R is the case of = 0, the amplitude ratio R is obtained when the measuring container 3 is taken in the apparatus of FIG.
= E ₁ / E ₂ is determined. The other 2
The value of each coefficient is R for two different values of V _X by a method such as connecting a container of known volume instead of the measuring container 3.
Is determined by measuring the value of

When the relationship between the amplitude ratio R and the extra product V _X is determined by the above-described calibration, the value of the volume V ₃ of the measuring container 3 without the object 8 can be obtained. Although completed in this measurement when the measured amount is of its volume V ₃ of the measurement container 3, when the amount to be measured is the volume V of the object 8 are surplus product put 8 into the measurement vessel 3 V _X is measured, and the value of V is obtained by setting V = V ₃ −V _X.

FIG. 4 shows a signal processor 15 and a signal generator 16.
2 is an example of the internal structure of the electronic circuit device 14 made of. The output signals e ₁ and e ₂ of the microphones 11 and 12 are amplified by amplifiers 21 and 22, respectively, and then A
It is converted into a digital quantity by the D converters 23 and 24 and taken into the digital computer 25. A frequency multiplier 26 frequency-multiplies the synchronizing pulse supplied from the signal generator 16 through the lead wire 27 into a sampling pulse, which is sent to the AD converters 23 and 24, and AD conversion is performed in synchronization with this sampling pulse. To do. But,
In this portion, a clock pulse generator may be provided inside the signal processing device 15, and AD conversion may be performed by this clock pulse independently of the signal generator 16. In the digital computer 25, the taken-in data is Fourier-transformed to output the microphone output signal e ₁ ,
Precisely measure the amplitudes E ₁ and E ₂ of e ₂ . Further, the measurement formula shown in (Equation 4) or its approximation formula is created and stored in the computer, and the extra product V _X or the volume V of the object is calculated and displayed from the measured E ₁ and E ₂ .

[0020]

[Second Embodiment] Although the above-described calculation can be performed by an analog circuit using an operational amplifier or the like, the problem at that time is to obtain the amplitude ratio R = E ₁ / E ₂ . It is division. In general, it is difficult to configure a precision divider with an analog circuit, which reduces the accuracy of the volume meter as a whole. However, if the size of either E ₁ or E ₂ is controlled to be constant, the volume can be obtained without using the divider.

Now, assuming that the amplitude E ₁ is always kept constant, (Equation 4) is rewritten as a function of E ₂ as follows.

(Equation 5)

Here, E ₂₀ is the value of E ₂ when V _X = 0, and is a constant value if E ₁ is constant.

FIG. 5 shows an example of the electronic circuit device 14 in the case of the volume measurement formula (Equation 5). The configuration of the other parts of the volume meter is the same as in FIG. From the output signals e ₁ and e ₂ of the microphones 11 and 12, only the frequency components near the angular frequency ω of the alternating volume change are extracted by the filters 31 and 32, respectively, and their amplitudes E ₁ and Converted to a signal representing E ₂ . The output of the rectifying / smoothing circuit 33 is given to the signal generator 16 ′ through the lead wire 29. Reference numeral 16 'is a signal generator 16 shown in FIG. 1 added with an output variable function, and the amplitude of its output is changed by the signal given from the rectifying / smoothing circuit 33, and therefore the alternating volume given to the container by the speaker 6 is provided. The magnitude of change changes. Then, the feedback loop from the microphone 11 to the speaker 6 via the signal generator 16 ′ controls the amplitude E _{1 to} be constant. On the other hand, the rectifying / smoothing circuit 3 representing E ₂
The output of No. 4 is sent to the meter 30 and its size is displayed. Since the scale plate has the V _X or V value preset by (Equation 5) and calibration, The measurement value of is read directly. However, this graduation is an unequal interval graduation that includes the nonlinearity of 1 / E ₂ .

Similar to the above, the volume meter is constructed even if the amplitude E ₂ is kept constant. The measurement formula in this case is as follows.

(Equation 6)

Here, E ₁₀ is the value of E ₁ when V _X = 0, and is a constant value if E ₂ is constant. In the electronic circuit device 14 in this case, the output signals e ₁ and e ₂ of the microphones are interchanged as shown in parentheses in FIG. 5, and the operation is exactly the same as that described in the measurement formula of (Equation 5). Is.

[0026]

[Third Embodiment] In industrially mass-produced containers, there is a demand for measuring the deviation of the volume of a large number of homogeneous containers from a certain reference value. In addition, when measuring the volume change due to heating of the plastic sample described above, the volume V of the sample at room temperature is measured in advance by a method such as the underwater weight method and used as the volume reference value and heated with a gas volume meter. Only the volume change ΔV due to is measured. Of course, while heating the sample with the apparatus of FIG. 1, the volume V + Δ
Although V can be measured, in such a case, the microphones 11 and 12 are required to have sufficient precision and stability of sensitivity to detect a slight volume change rate ΔV / V. However, as described below, by introducing a new communication pipe, it is possible to measure the above-mentioned volume change, that is, the deviation of the volume from the reference value, using a microphone with relatively low accuracy.

In FIG. 6, reference numeral 18 denotes a communication pipe, which communicates the inner space of the reference container 1 and the auxiliary container 2. A microphone 13 is provided in the middle of the length direction of 18 as a means for detecting a pressure change therein, and its output signal e
₃ is input to the signal processing device 15. A communicating pipe tip portion 20 is screwed to the tip of the communicating pipe 18, and the total length of the communicating pipe 18 can be changed by turning this tip portion. The configuration of parts other than the above is the same as in FIG.

When a constant magnitude alternating drive signal is applied to the speaker 6 from the signal generator 16, the diaphragm 7 vibrates, and the reference container 1 and the auxiliary container 2 have the same absolute value as described above. Volume changes of opposite sign are given. Therefore, the signs of the resulting pressure changes in 1 and 2 are opposite to each other. That is, the pressure changes in 1 and 2 have a phase difference of 180 ° from each other. Communication pipe 1 here
Considering the distribution of the pressure change inside 8, the pressure change at the upper end of 18 is equal to the pressure change inside the container 1, and the pressure change at the lower end of 18 is equal to the pressure change inside the container 2. , 18, the amplitude of the pressure change continuously changes from the upper end to the lower end. Therefore, 18
There is an acoustic equilibrium point at which the pressure change is zero in the middle of the length direction of the microphone, and the microphone 13 is attached near this equilibrium point.

The position of the above-mentioned equilibrium point is determined by the communicating pipe tip 20.
It can be adjusted by turning to change the total length of the communication tube, but the output signal e ₃ of the microphone 13 in a state where the sample object 8 is put in the measuring container 3 at room temperature.
Is adjusted so that the value becomes approximately 0. When the volume of the object 8 increases by ΔV due to heating or the like, the container 3
The co-product V _X of V is decreased by ΔV, and the position of the acoustic equilibrium point inside the communication pipe 18 changes accordingly. Therefore, the amplitude E ₃ of the signal e ₃ changes, but this change in amplitude changes in volume. It is almost proportional to ΔV. That is, the relationship between ΔV and E ₃ is expressed as follows.

(Equation 7)

Here, K is a coefficient determined by the sensitivity of the microphone 13 and the like. The amplitude E ₃ has a negative value when the signal e ₃ has the same phase as the pressure change inside the reference container 1, and has a positive value when the signal e ₃ has the opposite phase. B is a residual bias that could not completely reduce E ₃ to zero by adjusting the end portion 20 of the communicating tube, but this can be electrically removed as described below.

FIG. 7 shows an example of the internal structure of the electronic circuit device 14 of FIG. The output signal e ₃ of the microphone 13 is amplified by the amplifier 35 and then synchronously rectified by the synchronous rectifier 36 to become a signal representing the amplitude E ₃ , and the adder 37 subtracts a portion corresponding to the bias B and displays it by the meter 38. It At that time, a synchronization signal serving as a phase reference of the synchronous rectification is supplied to the signal generators 16 to 36 through the conductor 39. Since the scale plate of the meter 38 is calibrated in advance using an object of known volume or the like, the value of ΔV is directly read.

When measuring a large number of mass-produced containers, first, the container having the reference volume value is used as the measuring container 3 and is connected to the tip of the connecting pipe 9 so that the output signal e ₃ of the microphone 13 becomes substantially zero. After that, the container to be measured is connected to the tip of 9 as the measuring container 3 one after another, and the deviation of the volume from the reference volume value is measured.
When measuring the increase in volume of the object 8 due to heating, if the container 3 itself expands due to heating, first measure the change in the volume V ₃ of the container 3 due to the heating temperature without the object. Next, when the object 8 is put in and the measurement is performed, the influence of the container expansion is removed.

[0033]

[Fourth Embodiment] The apparatus of FIG. 8 corresponds to the measuring container 3 of the apparatus of FIG.
In addition to the above, a volume changing mechanism including a screw hole 50 and an adjusting screw 51 is added, and the volume V _{3 of the} container 3 can be changed by turning the screw 51. The other parts of the volume meter are the same as the device of FIG. The same applies to the case where the output signal e _{3 of the} microphone 13 is adjusted to be almost zero.

[0034] The coproduct V _X If only increased [Delta] V by the volume V of the object 8 placed in a container 3 such as heating decreased by [Delta] V, but the amplitude E ₃ of the signals e ₃ changes, the pointer of the meter 38 When the screw 51 is turned while adjusting to adjust E ₃ to the same value as before, the co-product V _{X at} this time has the same value as before. That is, the increment of the volume V ₃ due to the screw 51 is equal to ΔV. Therefore, the value of ΔV can be known from the relationship between the rotation angle of the screw 51 and the increase in volume.

The value of ΔV can also be obtained by attaching the above-mentioned variable volume mechanism to the reference container 1 or the auxiliary container 2 and performing the same operation. However, in this case, the volume increase due to the adjusting screw does not always become equal to the volume increase ΔV of the object 8, and the relationship between the two needs to be determined in advance by calibration using an object having a known volume or the like.

[0036]

Fifth Embodiment FIG. 9 shows an example in which the volume meter of the present invention is applied to the cylinder volume measurement of a gasoline engine. Reference numeral 40 is an engine crank chamber, 48 is a crank, 41 is a cylinder, and 42 is a piston.
Reference numeral 3 is the measurement container in this case, and the volume V _{X of} the space is the measured amount. 44 and 44 'are engine head covers,
A valve opening / closing mechanism and the like are housed inside. Reference numeral 49 denotes a spark plug hole, which is normally attached to the spark plug hole. However, in the case of volume measurement, the spark plug is removed and the tip of the connecting pipe 9 of the volume meter is connected to the hole. The other parts of the volume meter are the same as the device of FIG. However, the auxiliary container 2 is provided with a capillary tube 5 ′ communicating with the outside atmosphere. This is for allowing gas to flow in or out when the piston is moved up and down by turning the crankshaft with the volume meter attached. A crank angle sensor is attached to the crankshaft,
The output is sent to the crank angle display 45 by a conductor 46 to display the crank angle θ at the time of volume measurement.

When the volume is measured by rotating the crank little by little, as shown by the solid line in FIG. 10, the value of V _X is a function V _X (θ) of the crank angle θ, and θ ₁ across the top dead center is set. To θ ₂ for the crank angle range. In the range of θ other than this, the valve of the engine is open, so that the volume cannot be measured. However, by applying a sine waveform to the solid line portion of FIG. 10, V _X (θ) can be extrapolated as shown by the dotted line, whereby the top dead center volume V _T , the bottom dead center volume V _B , and the exhaust gas The quantity V _D = V _B −V _T etc. can be determined. For a diesel engine, the same measurement can be performed by removing the fuel injection valve and connecting the tip of the connecting pipe 9 to the hole.

[Brief description of drawings]

FIG. 1 is an apparatus according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit of an acoustic system of the device of FIG.

FIG. 3 is a graph showing a relationship between a co-product V _X and an amplitude ratio R.

4 is an example of an internal structure of an electronic circuit device of the device of FIG.

FIG. 5 is an example of the internal structure of the electronic circuit device of the device of the second embodiment of the present invention.

FIG. 6 is an apparatus according to a third embodiment of the present invention.

7 is an example of the internal structure of the electronic circuit device of the device of FIG.

FIG. 8 is an apparatus according to a fourth embodiment of the present invention.

FIG. 9 is an example in which the present invention is applied to cylinder volume measurement of an engine.

FIG. 10 is a graph showing a relationship between a cylinder internal space volume V _X and a crank angle θ.

[Explanation of symbols]

1 reference container of volume V _{1 2} auxiliary container of volume V _{2 3} measurement container of volume V ₃ partition wall 5, 5'capillary tube 6 speaker 7 speaker diaphragm 8 volume V object 9 connecting tube 10 conducting wire 11, 12, 13 Microphone 14 Electronic circuit device 15 Signal processing device 16, 16 'Signal generator 17 Terminal 18 Communication pipe 19 Terminal 20 Communication pipe tip 21, 22 Amplifier 23, 24 AD converter 25 Digital computer 26 Frequency multiplier 27, 29 Conductor wire 30 Meters 31, 32 Filters 33, 34 Rectification smoothing circuit 35 Amplifier 36 Synchronous rectifier 37 Adder 38 Meter 39 Conductor wire 40 Crank chamber 41 Cylinder 42 Piston 43 Cylinder internal space 44, 44 'Engine head cover 45 Crank angle indicator 46 Conductor wire 47 Crank angle Sensor 48 Crank 49 Spark plug hole 50 Di hole 51 adjustment screw

Claims (5)

[Claims] 1. A reference container, an auxiliary container, a measuring container,
A connecting pipe that connects the measurement container and the auxiliary container, a means for differentially applying an alternating volume change to the reference container and the auxiliary container, a means for detecting a pressure change inside each of the reference container and the auxiliary container, A gas volume meter comprising means for determining the volume of an object placed in a measuring container or the volume of the measuring container based on the ratio of the two detected pressure changes. 2. A reference container, an auxiliary container, a measuring container,
A connecting pipe that connects the measurement container and the auxiliary container, a means for differentially applying an alternating volume change to the reference container and the auxiliary container, a means for detecting a pressure change inside each of the reference container and the auxiliary container, A means for controlling the magnitude of the alternating volume change so that one of the detected pressure changes is constant, and an object placed in the measurement container according to the other magnitude of the detected pressure change. A gas volume meter comprising means for determining the volume of the measurement container or the volume of the measuring container. 3. A reference container, an auxiliary container, a measuring container,
A connecting pipe that connects the measurement container and the auxiliary container, a means that differentially gives an alternating volume change to the reference container and the auxiliary container, a communication pipe that connects the reference container and the auxiliary container, and a pressure change inside the communication pipe. Means for detecting the pressure change at a position where is substantially zero, and a deviation from the reference value of the volume of the object put in the measurement container or the reference value of the volume of the measurement container depending on the amplitude of the detected pressure change. A gas volume meter consisting of a means for obtaining the deviation. 4. A reference container, an auxiliary container, a measuring container,
A variable volume mechanism attached to at least one of the above-mentioned three containers, a connecting pipe for communicating the measurement container and the auxiliary container, means for differentially giving an alternating volume change to the reference container and the auxiliary container, and a reference A communication pipe that connects the container and the auxiliary container,
A means for detecting the pressure change at a position where the pressure change inside the communication pipe becomes substantially zero, and the volume changeable so that the amplitude of the detected pressure change remains unchanged regardless of the change in the extra volume of the measuring container. A gas volume meter comprising means for determining a deviation of a volume of an object put in a measuring container from a reference value or a deviation of a volume of the measuring container from a reference value by adjusting a mechanism. 5. An internal space of one cylinder of an engine is used as a measuring container, and a connecting pipe is connected to a spark plug hole or a fuel injection valve hole of the cylinder to measure the volume of the internal space of the cylinder. Claim 1 and Claim 2
The gas volume meter described in 1.