JP2000310551A - Method and apparatus for analyzing pulsation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To analyze a pulsation of a fluid by accurately measuring the pulsa tion, and accurately representing a pulsation waveform as its output by an analog or digital value. SOLUTION: A micro-flow sensor 3 has a heater element 34 for heating a fluid flowing through a channel 17, and temperature measuring elements 32, 33 disposed at upstream and downstream sides of the fluid through the element 34 to detect a temperature of the fluid to output an electric signal responsive to the temperature of the fluid. A data converting means 19A samples a different value of the signals output from the elements 32, 33 at each predetermined time, and digitally converts the signals. A pulsation presence or absence deciding means 19B decides the presence or absence of the pulsation of the fluid, based on the digital data converted by the means 19A. A pulsation analyzing means 19C reproduces the waveform by the pulsation contained in the digital data and analyzes the pulsation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures a pulsation generated in a fluid flowing through a flow path, and reproduces a pulsation by accurately reproducing a pulsation waveform by using an analog value of the output and a digital value obtained by high-speed A / D conversion. The present invention relates to a pulsation analysis method and an apparatus for analyzing the pulsation.

[0002]

2. Description of the Related Art In the field of devices such as gas leak detectors and gas meters for measuring the flow rate of gas, pulsation may occur in the gas in gas piping due to load fluctuations and gas heat pumps (GHP). In such a case, the pulsation causes a flow rate variation unrelated to consumption in the gas in the gas pipe, and the flow rate variation is reflected in the gas flow rate measurement, causing an error in the measured value.

[0003] The error of the flow measurement value due to the pulsation has not been a serious problem in the membrane type flow measurement device which has been widely widely used since the measurement accuracy was originally low.

A mass flow meter that measures a flow rate using a hot-wire sensor includes a sub flow path 102 and a heater 103 wound around the sub flow path 102, as shown in FIG. Fluid Q is laminar flow element bypass 1
It is configured to be diverted to the fluid Q _S to the fluid Q _B and the sub passage 102 to 01. The mass flow meter is one in which the heater 103 is heated heater resistance is changed is cooled by the fluid Q _S flowing through the sub-channel 102, for measuring the flow rate of a fluid based on the amount of change in the heater resistor.

As shown in FIG. 13, a mass flow controller for controlling a flow rate to a set flow rate value using a mass flow meter includes a laminar flow element bypass 101, a flow rate sensor 105 which is a hot wire sensor, and a flow rate sensor 105. 1
05, an amplifying circuit 107 connected to the bridge circuit 106, an amplifying circuit 1
07, the correction circuit 108,
The comparison control circuit 109 connected to the
The flow control valve 112 includes a valve drive circuit 110, a flow control valve 112, a piezo actuator 111 provided in the flow control valve 112, and a metal diaphragm 113 provided as a base for the flow control valve 112.

[0006] According to the mass flow controller configured as described above, the fluid entering from the inflow port receives the fluid from the flow sensor 1.
05 and the laminar flow element bypass 101, and the flow sensor 105 detects a temperature change proportional to the mass flow rate and converts the temperature change into an electric signal by the bridge circuit 106. This electrical signal
The signal is output as a flow rate output signal via the amplification circuit 107 and the correction circuit 108, and is also sent to the comparison control circuit 109.

The comparison control circuit 109 outputs a difference signal between the flow rate setting signal from the outside and the flow rate signal from the flow rate sensor 105 to the valve driving circuit 110, and outputs the signal to the flow control valve 11.
2 operates in a direction in which the difference signal from the valve drive circuit 110 becomes zero, so that the flow rate can always be controlled to the set flow rate.

[0008]

However, in the conventional mass flow meter, since a hot wire sensor is used, the response of the sensor is poor, and the response of the sensor is as short as about 1 second even at the shortest. Was. For this reason, only a pulsation of about 1 Hz could be measured. So, for example,
Even if a pulsation of about 5 Hz to 50 Hz (200 ms to 20 ms) occurs, this pulsation could not be accurately measured and analyzed.

It is an object of the present invention to provide a pulsation analysis method and apparatus capable of accurately measuring pulsation of a fluid, accurately reproducing a pulsation waveform based on an analog value and a digital value, and analyzing the pulsation. To provide.

[0010]

In order to achieve the above object, the present invention has the following constitution. In the pulsation analysis method according to the first aspect of the present invention, the fluid flowing through the flow path is heated by a heater element of a micro flow sensor installed on the flow path, and the fluid is moved upstream and downstream of the fluid with the heater element interposed therebetween. An output step of detecting the temperature of the fluid with each of the arranged temperature measuring elements and outputting an electric signal corresponding to the temperature of the fluid, and keeping a difference value between the electric signals output from the respective temperature measuring elements constant A data conversion step of sampling and digitally converting every time, a pulsation presence / absence determination step of determining the presence / absence of pulsation in the fluid based on the converted digital data, and when it is determined that the fluid has pulsation, the digital A pulsation analysis step of analyzing the pulsation by reproducing a pulsation waveform due to the pulsation included in the data. .

A pulsation analyzer according to a second aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, is provided on a flow path 17 for heating a fluid flowing through the flow path 17 and a heater element 34 for heating the fluid. A temperature measuring element 3 which is arranged on the upstream side and the downstream side of the fluid with respect to the fluid 34 and detects the temperature of the fluid and outputs an electric signal corresponding to the temperature of the fluid.
A micro-flow sensor 3 having a micro-flow sensor 2 and a data conversion means 19A for sampling a difference value of the electric signal outputted from each of the temperature measuring elements 32 and 33 at regular time intervals and converting the difference into digital data; Means 19
A pulsation presence / absence determination unit 19B for determining the presence / absence of pulsation in the fluid based on the digital data converted in A. When the pulsation presence / absence determination unit 19B determines that the fluid has pulsation, the pulsation is included in the digital data. And a pulsation analyzing means for reproducing the pulsation waveform due to the pulsation and analyzing the pulsation.

A pulsation analysis method according to the first aspect of the present invention, and a second aspect.
According to the pulsation analyzer of the invention, the fluid flowing through the flow path 17 is heated by the heater element 34 of the micro flow sensor 3 installed on the flow path 17, and the heater element 3
4, the temperature of the fluid is detected by the temperature measuring elements 32 and 33 disposed on the upstream and downstream sides of the fluid, and an electric signal corresponding to the temperature of the fluid is output. The difference value of the electric signal output from each is sampled at fixed time intervals and converted to digital, and the presence or absence of pulsation in the fluid is determined based on the converted digital data. Since the pulsation is analyzed by reproducing the pulsation waveform due to the pulsation included in the data, the pulsation of the fluid can be accurately measured, and the pulsation can be analyzed by accurately reproducing the pulsation waveform of the output with a digital value.

The pulsation presence / absence determining means 1 according to the third aspect of the present invention.
9B is characterized in that the presence or absence of pulsation in the fluid is determined based on whether or not the change in the digital data is periodic.

According to the third aspect of the present invention, the pulsation presence / absence determining means 19B determines the presence / absence of pulsation in the fluid based on whether or not the digital data change has periodicity. If so, it can be easily determined that there is pulsation.

[0015] The data conversion means 19 of the invention of claim 4
A is characterized in that a difference value of the electric signal is digitally converted by a clock signal having a cycle shorter than a minimum cycle of the pulsation that can occur in the fluid flowing through the flow path.

According to the fourth aspect of the present invention, the data conversion means 19A digitally converts the difference value of the electric signal by a clock signal having a cycle shorter than the minimum cycle of the pulsation which can occur in the fluid flowing through the flow path. A pulsation waveform of a minimum pulsation cycle can be accurately measured.

The pulsation analysis means 19C according to the fifth aspect of the present invention.
Is characterized in that the amplitude and the period of the pulsation are analyzed by the pulsation waveform.

According to the invention of claim 5, the pulsation analysis means 1
9C analyzes the amplitude and cycle of the pulsation by the pulsation waveform, so that the degree of the pulsation can be easily grasped,
By correcting the pulsation in this way, an accurate flow rate value can be obtained.

According to the sixth aspect of the present invention, the flow rate pulsation can be accurately measured by converting the digital data into digital data corrected to respective flow rate values.

According to a seventh aspect of the present invention, there is provided a flow rate measuring means for measuring a flow rate of the fluid based on the digital data, a set value input means for setting a desired flow rate value, and a flow rate value measured by the flow rate measuring means. And a flow rate value set by the set value input means, and a flow rate control means for controlling the flow rate to the set flow rate value based on a comparison result of the comparison control means. .

According to the invention of claim 6, when the flow rate measuring means measures the flow rate of the fluid based on the digital data and the set value input means sets a desired flow rate value, the comparison control means
The flow rate value measured by the flow rate measuring means is compared with the flow rate value set by the set value input means, and the flow rate control means controls the flow rate value to be set based on the comparison result of the comparison control means. It is possible to always control the flow value of the fluid flowing to the set flow value.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pulsation analysis method and apparatus according to the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 2 is a block diagram showing a schematic configuration of a pulsation analyzer according to a first embodiment of the present invention. This pulsation analyzer is provided in a mass flow meter and analyzes the degree of pulsation in a fluid, and is used particularly for a pulsation test. This pulsation analyzer includes a micro flow sensor 3, a power supply 5, an amplifier 9, and an oscilloscope 15.

The micro flow sensor 3 is provided on the inner wall of the gas flow path 17 as shown in the sectional view of FIG.
As shown in the side view of FIG. 4, a thin diaphragm portion 31a formed between the semiconductor bases 31, 31 is provided.
Also, as shown in the plan view of FIG.
A thermopile 32, 33 (corresponding to a temperature measuring element) for temperature measurement and a heater element 34 for heating are formed on a.

Further, as shown in FIG. 3, the micro flow sensor 3 has a flow direction X of the gas flowing through the gas flow path 17.
From the upstream side of the thermopile 32, heater element 3
4, the thermopiles 33 are arranged at regular intervals along the flow direction X.

The thermopiles 32 and 33 are temperature measuring elements that generate an electromotive force according to the temperature difference between the temperature sensing part and the temperature of the sensor substrate. As shown in the drive circuit diagram of FIG. An electromotive force and a difference from the side thermopile 33 are amplified by the amplifier 9 and output from the output terminal 39 of the micro flow sensor 3 as a signal corresponding to the flow velocity of the gas flowing in the gas flow path 17. .

The power supply 5 includes a battery 51 and a constant voltage circuit 5.
The digital circuit IC voltage circuit 53 outputs the power voltage from the battery 51 as a predetermined constant voltage. The constant voltage circuit 53 sets the voltage of the electric power from the battery 51 to a predetermined constant voltage, and supplies the constant voltage to the heater element 34.

The amplifier 9 amplifies the temperature measurement output signal output from the output terminal 39 of the micro flow sensor 3, and the amplified signal is output to the oscilloscope 15, as shown in FIG.

The oscilloscope 15 converts the amplified signal output from the amplifier 9 that has amplified the temperature measurement output signal from the micro flow sensor 3 into a signal having a period sufficiently shorter than the minimum period of the pulsation that may occur in the gas flowing through the gas flow path 17. Sampling is performed, and an analog waveform of the amplified signal is displayed based on the sampling result. Note that a pen recorder may be used instead of the oscilloscope 15.

Next, the operation of the pulsation analyzer of the first embodiment will be described. First, in the micro flow sensor 3, the power from the power source 5, in which the voltage of the power from the battery 15 is set to a predetermined constant voltage by the constant voltage circuit 53, is supplied to the heater element 34. When no pulsation occurs in the gas flowing in the gas flow path 17, the temperature measurement output from the output terminal 39 of the micro flow sensor 3 is performed as long as the flow rate of the gas flowing in the gas flow path 17 is constant. As shown in the graph of FIG. 7, the waveform of the output signal has a rectangular waveform in which a zero flow potential and a potential corresponding to the gas flow rate are repeated at predetermined intervals. Then, the waveform of the amplified signal obtained by amplifying the temperature measurement output signal by the amplifier 9 and displayed on the oscilloscope 15 has the same waveform as the waveform of the temperature measurement output signal shown in FIG.

On the other hand, in a state where the gas flowing in the gas flow path 17 is pulsating, assuming that the flow rate of the gas flowing in the gas flow path 17 is constant, the output terminal 39 of the micro flow sensor 3 will be described. The waveform of the temperature measurement output signal output from the oscilloscope has an electric potential corresponding to the gas flow rate in the waveform shown in FIG. Signal components superimposed,
The waveform is as shown in the graph of FIG.

When the gas flowing through the gas flow path 17 is pulsating, the waveform of the amplified signal obtained by amplifying the temperature measurement output signal by the amplifier 9 and displayed on the oscilloscope 15 is of course also changed. The waveform is the same as the waveform of the temperature measurement output signal shown in FIG.

As described above, according to the pulsation analyzer of the first embodiment, since the micro flow sensor 3 is used and the DC drive is used, the sensor responsiveness is improved, and 10 Hz to 21 Hz is obtained.
Since the pulsation flow rate change of 10 Hz can be accurately captured, the pulsation of 10 Hz to 21 Hz can be easily measured.

For example, in pulse driving, the time required for the heater to be sufficiently heated and cooled is at least about 20 ms (millisecond). By adopting the drive, the response time to the flow rate fluctuation is only about 2 ms, so that a high responsiveness in the pulsation measurement can be sufficiently secured.

The waveform of the amplified signal obtained by amplifying the temperature measurement output signal output from the output terminal 39 of the micro flow sensor 3 by the amplifier 9 is displayed on the oscilloscope 15. Therefore, the oscilloscope 15
The waveform pattern of the AC signal component of the waveform displayed in
That is, the amplitude and the period of the pulsation generated in the gas flowing in the gas flow path 17 can be measured based on the amplitude and the period of the AC signal component. In addition, the pulsation can be reproduced to analyze the amplitude, cycle, maximum value, minimum value, and the like of the pulsation.

Also, based on the measurement result, the gas flow path 17
It is also possible to correct the flow rate of the gas flowing in the gas passage 17 so as to eliminate the error of the integrated flow rate caused by the flow velocity fluctuation due to the pulsation of the gas flowing in the gas flow path 17.

<Second Embodiment> Next, a pulsation analyzer according to a second embodiment of the present invention will be described below. FIG. 9 is a block diagram illustrating a schematic configuration of a pulsation analysis device according to the second embodiment of the present invention. The pulsation analyzer according to the second embodiment includes an A / D converter 11 connected to the output terminal of the amplifier 9 instead of the oscilloscope 15 and an output of the A / D converter 11 connected via a signal line 12. Microcomputer 1
9. Personal computer 20 capable of data communication with microcomputer 19 via signal line 12, display 21, printer 23, microcomputer 19
And a mass flow controller 25 connected to the

The A / D converter 11 converts an analog amplified signal obtained by amplifying the temperature measurement output signal from the micro flow sensor 3 corresponding to the flow velocity of the gas flowing through the gas flow path 17 by the amplifier 9 into a predetermined sampling period. Each time the amplified signal is converted into a digital signal, the amplified signal is sampled by a clock signal having a frequency higher than the maximum frequency of the pulsation. A /
The D converter 11 is connected to the output terminal 3 of the micro flow sensor 3.
9 has a high-speed sampling function capable of correctly and fully tracing the cycle and amplitude of the AC signal component corresponding to the frequency of the gas flow velocity fluctuation appearing in the temperature measurement output signal output from the thermometer 9. The signal line 12 is, for example, an RS-232C cable.

The microcomputer 19 calculates a digital value of the amplified signal fetched from the A / D converter 11,
It measures and analyzes the amplitude and cycle of the pulsation generated in the gas flowing in the gas flow path 17, calculates the instantaneous flow rate, the passing flow rate, the integrated value, and the like.

The microcomputer 19 has a CPU 19
a, a RAM 19b, a ROM 19c, and an EEPROM 19d that can be rewritten and read and can be stored even when the power is off.
An A / D converter 11 is connected in addition to the A / D converter 19c and the EEPROM 19d. The EEPROM 19d stores a flow state, an instantaneous flow rate, an integrated value, and a pulsation value of a pulsation waveform.

The RAM 19b has a data area for storing various data and a work area used for various processing operations. The ROM 19c stores a control program for causing the CPU 19a to perform various processing operations.
The display 21 displays the pulsation waveform,
Prints a pulsating waveform.

The mass flow controller 25 includes a set value input unit 27 for setting a desired flow value, and a comparison control circuit 28 for obtaining a difference between a flow signal from the microcomputer 19 and the flow value input by the set value input unit 27. And a flow control valve 29 that operates in a direction in which the difference signal from the comparison control circuit 28 becomes zero and controls the flow rate to a set flow value.

In FIG. 9, the same parts and portions as those of the pulsation analyzer of the first embodiment shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. Description is omitted.

Next, pulsation analysis processing performed by the CPU 19a in accordance with the control program stored in the ROM 19c will be described with reference to the flowchart of FIG.

When the microcomputer 19 is started by being connected to a power source (not shown) and the program is started,
First, as shown in FIG. 10, the CPU 19a performs a pulsation determination condition input accepting process from a keyboard or a mouse (not shown) (step S1).

In the pulsation determination condition input accepting process of step S1, parameters of the pulsation determination condition are determined from the keyboard or the mouse for a predetermined time from the start of the microcomputer 19 in accordance with the contents of an input request screen displayed on a display (not shown). Waits for an input to be set, and if it is input during the predetermined time, the input value is stored in the RAM 1
9b is stored as condition data.
The default value stored in the OM 19c is stored in the RAM 19
The processing of storing as condition data in b is executed.

The parameter of the pulsation determination condition is, for example, the instantaneous flow rate of the gas in the gas flow path 17 analyzed based on the amplified signal input from the A / D converter 11. When a change occurs, the number of cycles in which the change continues is determined as the occurrence of pulsation.

After the pulsation determination condition input acceptance processing in step S1 has been completed, it is next determined whether or not the sampling cycle for A / D conversion of the amplified signal from the amplifier 9 by the A / D converter 11 has arrived. If it has not arrived (N in step S3), step S3 is repeated until it arrives.

On the other hand, when the sampling period has arrived (Y in step S3), an amplified signal converted into digital data is fetched from the A / D converter 11 (step S3).
5) After the fetched digital data is stored in the past buffer area of the RAM 19b in the order of fetch from the A / D converter 11 (step S7), the change of the value of the digital data stored in this past buffer area is changed. Then, it is determined whether or not a change in the value of the digital data due to the pulsation-specific frequency of 10 to 21 Hz is found (step S9). The processing in step S9 constitutes a pulsation presence / absence determination unit.

If such a change is not found (N in step S9), the process proceeds to step S21 described later, and if such a change is found (Y in step S9), it is determined that a change is seen. It is checked whether or not the number of times has been repeated by the number of determinations stored as condition data in the RAM 19b. If not (N in step S11), the process returns to step S3. If they are continuous (Y in step S11), it is determined that the pulsation has occurred, and the pulsation waveform based on the digital data is displayed on the display 21 or the printer 23.
The amplitude and period of the pulsation, the maximum value and the minimum value of the amplitude, and the like are analyzed from the pulsation waveform (step S13). The processing in step S13 constitutes a pulsation analysis unit.

Then, based on the digital data taken in from the A / D converter 11 in step S5, the instantaneous flow rate of the gas in the gas flow path 17 is obtained, and this is displayed on the display 2.
1 (step S15).

Next, an average value is obtained for each sampling based on a plurality of digital data taken from the A / D converter 11 and stored in the past buffer area of the RAM 19b (step S17). Then, an integrated value from the point in time when the periodicity occurs in the digital data is calculated (step S19), and the process proceeds to step S27.

On the other hand, the value of the digital data stored in the past buffer area in step S9 is
If no change due to the pulsation-specific frequency of 1 Hz is found (N), it is determined that the flow rate is a steady flow rate (step S2).
1) Based on the digital data taken in from the A / D converter 11, an instantaneous flow rate of the gas in the gas flow path 17 is obtained and displayed on the display 21 (step S2).
3).

Further, the flow rate of the gas is determined based on the determined instantaneous flow rate, and the integrated value of the flow rate for each sampling is calculated based on the determined flow rate of the gas (step S2).
5). Then, data such as a flow state, an instantaneous flow rate, an integrated value, a pulsation amplitude, a cycle, a pulsation value such as a maximum value, and a minimum value are stored in the EEPROM 19d (step S27).

As described above, the output terminal 39 of the micro flow sensor 3 in which the heater element 34 is constantly driven to heat is output.
Is amplified by an amplifier 9 to obtain an amplified signal, and the A / D converter 11 capable of high-speed sampling of about 1 ms converts the amplified signal into digital data at high speed. Based on the fluctuation, it is determined whether or not a pulsation has occurred in the gas flowing in the gas flow path 17, and when the digital data has fluctuated, the amplitude and cycle of the pulsation are accurately measured to reproduce the pulsation. Can be analyzed.

In this case, since the micro flow sensor 3 is used and the digital data is sampled at a sampling cycle having a cycle shorter than the minimum cycle of the pulsation, a pulsating flow rate change of 10 Hz to 21 Hz can be faithfully captured. A pulsation of 10 Hz to 21 Hz can be easily measured.

The pulsation data stored in the EEPROM 19d can be transmitted to the personal computer 20, and the personal computer 20 can analyze the data based on the pulsation data.

Next, the flow rate control by the mass flow controller 25 will be described with reference to the flowchart of FIG. First, when the set value input unit 27 inputs a set value as a desired flow value (step S31), the sensor output from the micro flow sensor 3 is digitally converted by the A / D converter 11 (step S33), and the digital data Is output from the microcomputer 19 to the comparison control circuit 28.

Then, the comparison control circuit 28 outputs the digital data from the microcomputer 19 to the set value input section 2.
It is determined whether or not the value is larger than the set value input in step 7 (step S35). If the digital data is larger than the set value, the flow control valve 29 is closed (step S3).
7). If the digital data is smaller than the set value, the flow control valve 29 is opened (step S39).

As described above, the flow rate can always be controlled to be constant using the digital data from the microcomputer 19 and the set value.

Next, the operation of the pulsation analyzer of the second embodiment will be described. First, in the micro flow sensor 3, the power from the power supply 5 is supplied to the heater element 34 with the voltage of the power from the battery 51 set to a predetermined constant voltage by the constant voltage circuit 53.

Here, in the state where the gas flowing in the gas flow path 17 is pulsating, assuming that the flow rate of the gas flowing in the gas flow path 17 is constant, the output terminal 39 of the micro flow sensor 3 The waveform of the temperature measurement output signal to be output is the same as the gas flow rate shown in FIG. 8 except that an AC signal component corresponding to the frequency of the flow velocity variation of the gas generated in the gas passage 17 due to the pulsation of the gas is superimposed. A waveform in which the corresponding potential portion is continuous will be presented, and the waveform of the amplified signal obtained by amplifying the temperature measurement output signal by the amplifier 9 will be the same.

In the microcomputer 19, the amplified signal obtained by amplifying the temperature measurement output signal output from the output terminal 39 of the micro flow sensor 3 by the amplifier 9 is output to the high-speed sampling of the A / D converter 11. Is taken in as A / D converted digital data by
Each time, the instantaneous flow rate of the gas flowing in the gas flow path 17 is calculated and updated and displayed on the display 21.

If the digital data taken in through the A / D converter 11 has a periodic fluctuation of 10 to 20 Hz due to the pulsation occurring in the gas flowing in the gas flow path 17 due to the frequency specific to the pulsation. The flow rate of the gas flowing through the gas flow path 17 based on the average value of the instantaneous flow rate calculated for each digital data sampling period from the start of the change of the digital data to the end of the change. Is calculated, and the passing flow rate of the gas based on the average value of the instantaneous flow rates is integrated with the passing flow rate accumulated before the continuous fluctuation of the digital data starts.

Further, the periodic fluctuation of the digital data taken in through the A / D converter 11 is set by inputting from a keyboard or a mouse (not shown) or stored in advance in the ROM 19c as a default value.
If the pulsation is determined to be continuous as the number of determinations in the pulsation determination parameter reaches the number of determinations, it is determined that pulsation has occurred in the gas flowing in the gas flow path 17 and that fact is stored as data in the EEPROM 19d.

On the other hand, as long as the digital data taken in via the A / D converter 11 does not have a periodic fluctuation, the gas flow is calculated based on the instantaneous flow rate calculated for each digital data sampling cycle. The passing flow rate of the gas flowing in the flow path 17 is calculated for each sampling cycle of each digital data, and the calculated passing rate of the gas is integrated with the passing flow rate integrated up to the time of the previous digital data capture. You.

As described above, the pulsation analyzer according to the second embodiment has the same advantages as the pulsation analyzer according to the first embodiment.

[0068]

According to the pulsation analysis method of the present invention, the fluid flowing through the flow path is heated by the heater element of the micro flow sensor installed on the flow path. The temperature of the fluid is detected by the temperature measuring elements disposed on the upstream and downstream sides of the heater element, and an electric signal corresponding to the temperature of the fluid is output. The difference value of the electric signal is sampled at predetermined time intervals and converted into a digital signal.The presence or absence of pulsation in the fluid is determined based on the converted digital data. When it is determined that the fluid has a pulsation, the pulsation included in the digital data is determined. In order to analyze the pulsation by reproducing the pulsation waveform of the fluid, the pulsation of the fluid is accurately measured, and the output is analyzed by accurately reproducing the pulsation waveform by the digital value. Can.

According to the third aspect of the present invention, the pulsation presence / absence determining means determines the presence / absence of pulsation in the fluid based on whether or not the digital data has a periodicity. Thus, it can be easily determined that there is a pulsation.

According to the fourth aspect of the present invention, the data converter converts the difference value of the electric signal into a digital signal by a clock signal having a cycle shorter than the minimum cycle of the pulsation that can occur in the fluid flowing through the flow path. The pulsation waveform of about the minimum cycle can be accurately measured.

According to the fifth aspect of the present invention, since the pulsation analyzing means analyzes the amplitude and cycle of the pulsation based on the pulsation waveform, it is possible to easily grasp the degree of the pulsation, thereby correcting only the pulsation. Then, an accurate flow rate value can be obtained.

According to the sixth aspect of the present invention, the flow rate pulsation can be accurately measured by converting the digital data into digital data corrected to flow rate values.

According to the invention of claim 7, when the flow rate measuring means measures the flow rate of the fluid based on the digital data and the set value input means sets a desired flow rate value, the comparison control means
The flow rate value measured by the flow rate measuring means is compared with the flow rate value set by the set value input means, and the flow rate control means controls the flow rate value to be set based on the comparison result of the comparison control means. It is possible to always control the flow value of the fluid flowing to the set flow value.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a pulsation analysis device of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a pulsation analysis device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an arrangement of the micro flow sensor of FIG. 2;

FIG. 4 is a side view showing a schematic configuration of the micro flow sensor of FIG.

FIG. 5 is a plan view showing a schematic configuration of the micro flow sensor of FIG. 3;

FIG. 6 is a drive circuit diagram of the micro flow sensor of FIG. 2;

7 is a graph showing a waveform of a temperature measurement output signal of a micro flow sensor output from an output terminal of FIG. 3 in a state where pulsation is not generated in a gas flowing in a gas flow path of FIG. 2;

8 is a graph showing a waveform of a temperature measurement output signal of the micro flow sensor output from the output terminal of FIG. 3 in a state where pulsation occurs in the gas flowing in the gas flow path of FIG.

FIG. 9 is a block diagram illustrating a schematic configuration of a pulsation analysis device according to a second embodiment of the present invention.

10 is a flowchart showing a gas flow rate measurement process performed by a CPU according to a control program stored in a micro ROM shown in FIG. 9;

11 is a flowchart showing a gas flow rate measurement process performed by a CPU according to a control program stored in a ROM of the microcomputer in FIG. 9;

FIG. 12 is a configuration diagram showing a mass flow meter using a conventional hot-wire sensor.

13 is a configuration diagram showing a mass flow controller including the mass flow sensor shown in FIG.

[Explanation of symbols]

 Reference Signs List 3 Micro flow sensor 5 Power supply 11 A / D converter 17 Flow path 19 Microcomputer 19a CPU 19b RAM 19c ROM 19A Data conversion means 19B Pulsation presence / absence determination means 19C Pulsation analysis means 21 Display 23 Printer 25 Mass flow controller 32, 33 Thermopile (measurement) Temperature element) 34 heater element

Claims (7)

[Claims] 1. A fluid flowing through a flow path is heated by a heater element of a micro flow sensor installed on the flow path, and temperature measurement is arranged on an upstream side and a downstream side of the fluid with the heater element interposed therebetween. An output step of detecting the temperature of the fluid by an element and outputting an electric signal corresponding to the temperature of the fluid; and sampling a difference value of the electric signal output from each of the temperature measuring elements at regular intervals. A data conversion step of digitally converting; a pulsation presence / absence determination step of determining the presence / absence of pulsation in the fluid based on the converted digital data; and a pulsation included in the digital data when it is determined that the fluid has pulsation. A pulsation analysis step of analyzing the pulsation by reproducing a pulsation waveform according to the above. 2. A heater element installed on a flow path, for heating a fluid flowing through the flow path, and disposed on an upstream side and a downstream side of the fluid with the heater element interposed therebetween to detect a temperature of the fluid. A micro-flow sensor having a temperature measuring element for outputting an electric signal corresponding to the temperature of the fluid; and a data conversion for sampling and digitally converting a difference value of the electric signal output from each of the temperature measuring elements at regular intervals. Means, pulsation presence / absence determination means for determining the presence / absence of pulsation in the fluid based on the digital data converted by the data conversion means, and when the pulsation presence / absence determination means determines that the fluid has pulsation, the digital Pulsation analysis means for analyzing the pulsation by reproducing a pulsation waveform due to the pulsation included in the data. Dynamic analyzer. 3. The pulsation presence / absence determining means determines the presence / absence of pulsation in the fluid based on whether the digital data changes periodically.
The pulsation analyzer according to any one of the preceding claims. 4. The data converter according to claim 1, wherein the difference value of the electric signal is digitally converted by a clock signal having a cycle shorter than a minimum cycle of the pulsation that can occur in the fluid flowing through the flow path. The pulsation analysis device according to claim 2 or 3. 5. The pulsation analysis device according to claim 2, wherein the pulsation analysis means analyzes the amplitude and the period of the pulsation based on the pulsation waveform. 6. The pulsation analysis apparatus according to claim 2, wherein each of the digital data is digital data corrected to a flow value. 7. A flow rate measuring means for measuring a flow rate of the fluid based on the digital data; a set value input means for setting a desired flow rate value; 3. A comparison control means for comparing the flow rate value set by the means with the flow rate control means for controlling the flow rate value to the set flow rate value based on a comparison result of the comparison control means. The pulsation analysis device according to claim 6.