JP4147274B2 - Integrated flow meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an integrating flow meter that integrates an instantaneous flow rate of a fluid measured using a thermal flow sensor for each predetermined unit flow rate defined by a flow rate so as to obtain an integrated flow rate.
[0002]
[Related background]
For example, as shown in FIG. 9, the thermal flow sensor has a pair of temperatures made of a resistance temperature detector in the fluid flow direction F with a heater element Rh made of a heating resistor provided on the silicon base B interposed therebetween. It has an element structure provided with sensors Ru and Rd. A flow meter using this type of thermal flow sensor utilizes the fact that the degree of diffusion (temperature distribution) of the heat generated from the heater element Rh varies depending on the flow of the fluid, and the temperature sensors Ru, Rd The flow rate of the fluid, and hence the flow rate Q, is detected from the change in resistance value due to heat. In the figure, Rr is a temperature sensor made of a resistance temperature detector provided at a position away from the heater element Rh, and is used for measuring the ambient temperature.
[0003]
An integrated flow meter such as a gas meter using such a thermal flow sensor roughly represents an instantaneous flow rate q of a fluid (gas) measured in real time by the thermal flow sensor 1 as shown in FIG. Each time the accumulated flow Q reaches a predetermined unit flow Qo, the number of times of arrival is counted by using an accumulator (counter) 3. Specifically, as shown in FIG. 11 (a), whenever the integrated value (flow rate) Q of the instantaneous flow rate q integrated at the flow rate 2 reaches the unit flow rate Qo, for example, 10L, as shown in FIG. 11 (b). Thus, the unit flow rate signal P is output from the flow rate 升 2, and this signal P is counted by an accumulator (counter) 3 as shown in FIG.
[0004]
[Problems to be solved by the invention]
By the way, a so-called pulsating flow in which the fluid flowing through the flow path comes and goes due to pressure fluctuation in the flow path may occur. The component of this pulsating flow is regarded as a total (average) flow rate of zero [0].
However, in the conventional accumulator described above, the unit flow rate signal P generated when the accumulated value Q of the instantaneous flow rate q of the fluid accumulated using the flow rate 升 2 reaches a predetermined unit flow rate is represented by an accumulator (counter). ) Since the integrated flow rate TQ is only obtained by counting at 3, even if the fluid flows in the reverse direction, the reverse flow rate is not subtracted from the integrated flow rate TQ. For this reason, when the integrated value Q at the flow rate に お け る 2 in the pulsating state exceeds the unit flow rate, especially when the pulsation is large, the component of the pulsating flow that should be essentially zero [0] is unwilling. There is a problem that the measurement (integration) accuracy is impaired.
[0005]
The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an integrated flow meter capable of accurately determining the integrated flow rate of fluid passing through a predetermined flow path regardless of the presence or absence of a pulsation state. Is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, an integrating flow meter according to the present invention integrates a thermal flow sensor that measures an instantaneous flow rate of a fluid passing through a predetermined flow path, and an instantaneous flow rate that is measured by the thermal flow sensor. A unit flow rate signal is output when the integrated value reaches a predetermined unit flow rate, and the flow rate 升 for resetting the integrated value and the unit flow rate signal output from the flow rate 升 are counted to calculate the predetermined flow rate. Flow rate integration means for obtaining an integrated flow rate of the fluid flowing through the flow path,
In particular, a pulsation detecting means for detecting the pulsation state of the fluid in the flow path, and when a pulsation is detected by the pulsation detecting means, a measurement range by the thermal flow sensor is set wide and integrated by the flow rate 升. And a measuring range changing means for increasing the unit flow rate .
[0007]
That is, the integrated flow meter according to the present invention detects, for example, a reverse flow of a fluid or a pulsating state by detecting an instantaneous flow rate exceeding the measurement range of a thermal flow sensor. , and sets a wide measurement range by the thermal flow sensor, the flow squares forward of pulsating by increasing the unit flow that is accumulated by the instantaneous flow rate and reverse instantaneous flow rate accurately detected respectively Trying to get. The unit flow rate signal is prevented from being unintentionally output from the flow rate by reliably canceling the pulsating component of the instantaneous flow rate integrated by the flow rate. In other words, even if the pulsating component is superimposed on the normal flow rate component, the positive range of pulsation component is added by expanding the measurement range and increasing the capacity of the flow rate （(unit flow rate) . Accurately detect the instantaneous flow rate and the negative instantaneous flow rate with the reverse pulsation component added, and integrate the instantaneous flow rate with the flow rate 升 to cancel the positive pulsation component and the negative pulsation component. It is characterized by that.
[0008]
A preferred aspect of the present invention is a high-speed flow sensor with a wide measurement range for high-flow-rate measurement incorporated in the flow path, and a low-speed flow sensor with a narrow measurement range for low-flow-rate measurement, as the thermal flow sensor. The measurement range changing means is configured to operate the low-speed flow rate sensor during normal operation and to operate the high-speed flow rate sensor when pulsation is detected by the pulsation detection means.
[0009]
The pulsation detecting means may detect that the fluid is pulsating even when the integrated value of the instantaneous flow rate at the flow rate does not reach the unit flow rate within a predetermined time. .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an integrated flow meter according to the present invention will be described with reference to the drawings.
The integrated flow meter according to the present invention basically shows an instantaneous flow rate q of a fluid (gas) measured in real time using a thermal flow sensor 1 having an element structure as shown in FIG. So that the integrated flow rate Q is obtained by counting the number of times of arrival using the integrator 3 each time the integrated flow rate Q reaches a predetermined unit flow rate Qo. Composed.
[0011]
In the integrating flow meter basically configured as described above, the present invention is characterized in that, for example, as shown in FIG. 1, the instantaneous flow of fluid (gas) flowing through a predetermined flow path is shown. Pulsation detection means for monitoring the state of change of the flow rate q and detecting the occurrence of pulsation is provided [steps S1, S2]. Incidentally, this pulsation determination process is performed by examining whether a reverse instantaneous flow rate is detected or an instantaneous flow rate exceeding the measurement range of the thermal flow sensor 1 is detected, as will be described later.
[0012]
In a steady (normal) state with no pulsating flow, the instantaneous flow rate q is detected by driving the low-speed flow rate sensor 1 whose measurement accuracy is increased by narrowing the measurement range [Step S3]. If detected, the high-speed flow rate sensor 1 having a coarse measurement accuracy and a wide measurement range is driven to detect the instantaneous flow rate q [step S4].
[0013]
That is, the integrating flow meter according to the present invention is, for example, a low-speed flow rate for low flow rate measurement with a narrow measurement range as a thermal flow rate sensor 1 for measuring an instantaneous flow rate q of a fluid (gas) flowing through a predetermined flow path. A sensor 1a and a high-speed flow rate sensor 1b for measuring a high flow rate with a wide measurement range are provided. The flow rate sensors 1a and 1b are selectively used depending on whether or not pulsating flow is generated, and the normal flow rate q of the fluid flowing in the positive direction is highly accurate by using the low-speed flow rate sensor 1a having high measurement accuracy in normal times. The high-speed flow rate sensor 1b having a wide measurement range is used at the time of pulsation, so that the instantaneous flow rate q of the fluid flowing alternately in the forward direction and the reverse direction can be accurately detected.
[0014]
According to the integrated flow meter that includes the flow rate sensors 1a and 1b having different measurement ranges and selectively uses the flow rate sensors 1a and 1b depending on whether pulsation occurs or not, the measurement range is determined when pulsation is detected. Since a wide high-speed flow rate sensor 1b is used, as shown in FIGS. 2 (a) and 2 (b), not only the instantaneous flow rate q in the forward direction but also the instantaneous flow rate q in the reverse direction can be accurately measured. Thus, the instantaneous flow rates q having different directions can be accurately integrated at the flow rate 升 2.
[0015]
That is, when the low-speed flow rate sensor 1a is used, the instantaneous flow rate q of the pulsating flow component flowing in the reverse direction may be out of the measurement range. In this case, since the instantaneous flow rate q obtained from the low-speed flow rate sensor 1a is limited by the measurement range, it cannot be denied that it is smaller than the actual instantaneous flow rate. Then, in the process of integrating the instantaneous flow rate q at the flow rate 升 2, the forward pulsation component is not completely canceled by the reverse pulsation component. As a result, the integrated value Q of the flow rate 2 gradually increases as shown by the broken line in FIG. Then, there is a possibility that the integrated value Q exceeds the unit flow rate (size of soot) Qo.
[0016]
On the other hand, if the high-speed flow rate sensor 1b is used, the measurement range is wide, so there is no possibility that the instantaneous flow rate q of the pulsating flow component flowing in the reverse direction is out of the measurement range. Accordingly, the instantaneous flow rate q in the forward direction and the reverse direction can be accurately detected and applied to the flow rate 升 2. Then, as shown by the solid line in FIG. 2 (b), the flow rate 升 2 accumulates not only the positive instantaneous flow rate q but also the negative instantaneous flow rate q, so that the forward pulsation component and the reverse pulsation component are offset, Overall, only the averaged flow components are integrated. Therefore, the flow rate 升 2 integrates the instantaneous flow rate q without being affected by the pulsation, and outputs the unit flow rate signal P only when the integrated flow rate Q reaches the unit flow rate Qo that is the magnitude of 升. Therefore, the integrated flow rate TQ can be accurately measured in the integrating meter 3 as well.
[0017]
Next, an integrated flow meter according to an embodiment of the present invention will be described.
This integrated flow meter is suitable for use as an industrial gas meter, for example. As shown in FIG. 3, two types of thermal flow sensors with different measurement ranges are used, and a low-speed flow sensor for low flow rate measurement. 1a and a high-speed flow sensor 1b for high flow area measurement.
[0018]
Incidentally, the low-speed flow rate sensor 1a and the high-speed flow rate sensor 1b use, for example, the fact that the degree of thermal diffusion due to heat generation of the heater element Rh differs depending on the difference in the flow rate (flow velocity) of the fluid, The flow rate measurement area is made different by changing the separation distance. Specifically, the low-speed flow rate sensor 1a is realized by setting a long distance L1 between the heater element Rh and the temperature sensors Ru, Rd, and the high-speed flow rate sensor 1b is formed between the heater element Rh and the temperature sensors Ru, Rd. This is realized by setting the separation distance L2 short. For this reason, the high-speed flow sensor 1b has a higher degree of thermal coupling between the heater element Rh and the temperature sensors Ru and Rd than the low-speed flow sensor 1a. Therefore, when the same detection sensitivity is realized in both the flow sensors 1a and 1b, the heat generation temperature of the heater element Rh, and hence the driving power thereof, is suppressed lower in the high-speed flow sensor 1b.
[0019]
The integrating flow meter according to this embodiment is provided with the above-described two types of low-speed flow sensor 1a and high-speed flow sensor 1b in the same fluid flow path (gas pipe), and selects these flow sensors 1a and 1b. It is configured to be driven integrally. The CPU (arithmetic processing unit) 10 constituting the main body of the integrated flow meter includes a sensor selection unit 13 that selectively drives the heater drive circuits 11a and 11b of the flow rate sensors 1a and 1b via the switch 12. Further, the CPU 10 detects the sensor output respectively detected via the detection circuit (not shown) of each flow sensor 1a, 1b in conjunction with the alternative driving of each flow sensor 1a, 1b by the sensor selection means 13. A switch (selector) 14 for selectively taking in Vout1 and Vout2 is provided. The flow rate calculation means 15 calculates a flow rate (instantaneous flow rate) q corresponding to the sensor outputs Vout1 and Vout2 from the sensor outputs Vout1 and Vout2 taken in via the switch (selector) 14.
[0020]
The flow rate calculation means 15 inputs the information of the flow sensors 1a and 1b selected by the sensor selection means 13, and selectively selects the information via the switch (selector) 14 according to the selected flow sensors 1a and 1b. To calculate the instantaneous flow rate q corresponding to the sensor outputs Vout1 and Vout2. The calculation of the instantaneous flow rate q is a flow rate conversion table (not shown) indicating the relationship between the flow rate q and the sensor output Vout as shown in FIG. 2, for example, provided corresponding to each of the flow rate sensors 1a and 1b. It is executed by referring to.
[0021]
Incidentally, the low-speed flow rate sensor 1a has a narrow measurement range in order to ensure sufficiently high detection accuracy in the low flow rate region, as shown by the solid line in FIG. Further, as shown in FIG. 4, the high-speed flow rate sensor 1b has a wide measurement range in order to realize accurate flow rate measurement from a low flow rate range to a high flow rate range, as indicated by a broken line in FIG.
[0022]
By the way, the instantaneous flow rate q obtained by the flow rate calculation means 15 is given to the pulsation determination means 16 together with the sensor selection means 13 described above. The pulsation determining means 16 plays a role of determining whether or not pulsation is generated in a portion where the flow rate sensors 1a and 1b are provided from the state of change of the instantaneous flow rate q. Specifically, the pulsation determining means 16 determines that the above-described instantaneous flow rate q is measured every cycle set as, for example, 1 second, for example, the latest 20 samples as shown in FIG. Is extracted, and the presence or absence of pulsation is determined by examining the data content (instantaneous flow rate q). In a normal state where there is no pulsation, flow rate measurement is performed using the low-speed flow rate sensor 1a via the sensor selection means 13, and when pulsation is detected, the low-speed flow rate sensor 1a is replaced with the above-described flow rate sensor 1a. The high-speed sensor 1b performs flow rate measurement.
[0023]
The pulsation determination process of the pulsation determination unit 16 will be described with reference to FIG. 5. At the time of normal flow measurement using the low-speed flow rate sensor 1a, the pulsation determination unit 16 includes, for example, a relative value in the latest 20 sample data. In step S11, it is determined whether or not the instantaneous flow rate q which is equal to or less than “−100” is included twice or more. However, here, the instantaneous flow rate q measured by the flow rate sensors 1a and 1b is assumed to be a maximum [± 5000] in relative value. If this determination condition is not satisfied, it is determined that no pulsation has occurred, and the normal flow rate measurement using the low-speed flow rate sensor 1a described above is continued.
[0024]
On the other hand, if the above condition is satisfied, it is determined that pulsation has occurred, and the flow rate measurement is performed using the high-speed flow rate sensor 1b instead of the low-speed flow rate sensor 1a as described above. At this time, it is determined whether or not the pulsation has disappeared by checking whether or not the instantaneous flow rate q having a relative value of “−100” or less is less than twice in the latest 20 sample data [ Step S12]. However, if this pulsation extinction condition is not satisfied, the pulsation disappeared by examining whether or not the instantaneous flow rate q having a relative value of “2000” or more is 5 times or more in the latest 20 sample data. [Step S13]. If this pulsation extinction condition is not satisfied, pay attention only to the latest 10 sample data, and in these 10 sample data, for example, whether there are 5 or more instantaneous flow rates q having a relative value of “1000” or more. It is determined whether or not the pulsation has disappeared by checking whether or not [step S14].
[0025]
When all of these pulsation extinction conditions are not satisfied, it is determined that the pulsation state continues, and the flow rate measurement using the high-speed flow rate sensor 1b is continued. However, when any of the above pulsation extinction conditions is satisfied, the pulsation determining means 16 stops using the high-speed flow sensor 1b described above because the pulsation state has disappeared, and performs flow measurement using the low-speed flow sensor 1a. Return.
[0026]
The CPU 10 drives the flow rate selection means 17 in parallel with the selective switching of the flow sensors 1a and 1b described above. That is, in this integrated flow meter, the instantaneous flow rate q obtained through the flow rate calculation means 15 is set as a flow rate 升 2 to be integrated every predetermined unit flow rate Qo, and the unit flow rate (the magnitude of 升) Qo is set to 10L. The standard first flow rate 2a and the second flow rate 2b having a large capacity set with the unit flow rate (the size of the size) Qo set to 40L. Then, by switching the switch 18 in accordance with the detection result of the pulsation described above, the instantaneous flow rate q is integrated using the first flow rate 2a during normal operation, and the second flow rate 2b is used instantaneously during the pulsation. The flow rate q is integrated. At the same time, the CPU 10 manages the accumulated time of the instantaneous flow rate q by the flow rates 2a and 2b using the timer management means 19 for the integration of the instantaneous flow rate q selectively using the flow rates 2a and 2b. .
[0027]
When the pulsation is detected and the first flow rate 升 2a having a capacity of 10L is switched to the second capacity 升 2b having a capacity of 40L, the first flow rate 升 2a is more integrated at the time of switching. The integrated value Q is transferred to the second flow rate 2b as it is, and the subsequent instantaneous flow rate q is continuously integrated. Then, when integrating the instantaneous flow rate q at the second flow rate 2b, it is determined whether or not the integrated value Q reaches the unit flow rate Qo within a specified time. If the unit flow rate Qo is not reached within the specified time, The integrated value Q is forcibly reset.
[0028]
After that, when the pulsation stops, it is determined whether or not the integrated value Q integrated at the second flow rate 2b reaches the unit flow rate Qo within the specified time described above. The integrated value Q at the second flow rate 2b is forcibly reset. Then, the subsequent measurement is performed using the first flow rate 2a. However, when the integrated value Q integrated at the second flow rate 2b reaches the unit flow rate Qo within the specified time described above, the unit flow rate signal P is output from the second flow rate 2b, and the second After resetting the flow rate 升 2b, the subsequent measurement is performed using the first flow rate 升 2a. If the switching control of the flow rate 升 2a, 2b is performed in this way, the integration process can be continuously executed without wasting the integrated value Q integrated in the flow rate 升 2a, 2b. Become.
[0029]
That is, in the integrated flow meter configured as described above, the low speed sensor is normally used in accordance with the presence or absence of pulsation by the pulsation determination process [step S21, S22] as shown in FIG. 1a is driven, and the instantaneous flow rate q is integrated using the first flow rate 2a having a unit flow rate Qo of 10L [steps S23, S24]. When detecting pulsation, the high-speed sensor 1b is driven, and the instantaneous flow rate q is integrated using the second flow rate 2b having a unit flow rate Qo of 40L [steps S25, S26]. Under these measurement operation conditions, the time until the integrated value Q of the instantaneous flow rate q accumulated at the flow rate 升 2a, 2b reaches its unit flow rate (升 size) Qo is managed, If the integrated value Q does not reach the unit flow rate (magnitude) Qo within a predetermined time, the integrated value Q itself is reset [steps S27 and S28].
[0030]
Here, the switching between the first flow rate 2a and the second flow rate 2b described above at the time of detecting the pulsating flow will be briefly described. At the time of detecting the pulsation, the 40L flow rate 2b having a large capacity is used. Then, as shown in FIG. 7, the unit flow rate signal P is output because the unit flow rate Qo is set to 40L even when the integrated value Q of the pulsation component exceeds 10L. There is no. Further, in the second flow rate 升 2b, since the negative instantaneous flow rate q is also integrated, as shown in FIG. 7B, the pulsation component in the forward direction and the pulsation component in the reverse direction are canceled out, and the total is averaged. Only the flow rate components that have been added are integrated. Therefore, the integrating meter 3 can accurately measure the integrated flow rate TQ without being affected by pulsation.
[0031]
The accumulator 3 integrates the instantaneous flow rate q depending on whether the instantaneous flow rate q is integrated using the first flow rate 升 2a or the instantaneous flow rate q is integrated using the second flow rate 升 2b. Needless to say, changing the amount. That is, at normal times, according to the unit flow rate signal P output from the first flow rate 升 2a, the integrated flow rate TQ is increased by 10L, and when the second flow rate 升 2b is used by pulsation detection, In accordance with the unit flow rate signal P output from the second flow rate 2b, the integrated flow rate TQ is operated to increase by 40L. As a result, the integrated flow rate TQ can be obtained accurately regardless of which flow rate 2a, 2b is used.
[0032]
The time management for the integration of the instantaneous flow rate q at the flow rates 2a and 2b will be briefly described. When a pulsating flow occurs, the flow rate of the flow rate 2 is caused by a pulsating component flowing in the opposite direction as shown in FIG. Since the integrated value Q is subtracted, an increase in the integrated value Q is suppressed. Therefore, in general, it takes time until the integrated value Q reaches the unit flow rate Qo as indicated by a broken line in FIG. 8B.
[0033]
Therefore, by monitoring the time required for the integrated value Q of the instantaneous flow rate q integrated at the flow rate 2 to reach the unit flow rate Qo, it is possible to determine whether the current state is normal or pulsation occurs. In other words, by determining the integrated value Q when the predetermined management time To has elapsed, it can be determined whether or not the pulsating component is being integrated. When the pulsating component is integrated, if the flow rate 升 2 is reset when the management time To has elapsed as described above, the integrated value Q of the pulsating component is removed as shown by the solid line in FIG. This makes it possible to measure the integrated flow rate without being affected by the pulsating component.
[0034]
Thus, according to the above-described integrated flow meter that executes the switching control of the flow rate sensors 2a, 2b and the integrated time management of the instantaneous flow rate q at the flow rates 2a, 2b, together with the switching control of the flow rate sensors 1a, 1b described above, Flow rate measurement that is not affected by pulsation can be realized. The accumulated value Q (= Qo) of the instantaneous flow rate q accurately measured using the flow rate 2 (2a, 2b) is accumulated in the accumulator 3, so that the accumulated flow rate TQ is very high. It becomes possible to make it highly accurate.
[0035]
The present invention is not limited to the embodiment described above. For example, in this embodiment, the capacities of the first flow rate 升 2a and the second flow rate 升 2b are set to 10L and 40L, but the capacities (magnitude) Qo are fluids (gases) to be measured. It may be set according to the steady flow rate and the magnitude of the pulsation actually assumed. Needless to say, it is not necessary to prepare two kinds of flow rates 2a and 2b if the capacity (size of the flow rate) Qo of the flow rate 2 is variably set externally. Specifically, if the flow rate 升 2 is realized on the software in the CPU 10, the capacity (the size of the heel) Qo can be easily changed, and two types of physical flow rates 升 2a and 2b are prepared. There is no need. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.
[0036]
【The invention's effect】
As described above, according to the present invention, since the integrated flow rate of the fluid passing through the predetermined flow path can be accurately obtained without being affected by the pulsating flow, the amount of gas used for charging is measured. When applied to such a gas meter, a great effect can be achieved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic processing concept of an integrating flow meter according to the present invention.
FIG. 2 is a diagram for explaining an effect removing action of a pulsating flow component in the integrating flow meter according to the present invention.
FIG. 3 is a schematic configuration diagram of an integrating flow meter according to an embodiment of the present invention.
4 is a diagram showing measurement characteristics of a low-speed flow sensor and a high-speed flow sensor used in the integrating flow meter shown in FIG. 3;
FIG. 5 is a diagram showing a schematic flow of a pulsating flow determination process in the integrating flow meter according to the embodiment.
FIG. 6 is a diagram showing an overall control processing procedure in the integrating flow meter according to the embodiment.
FIG. 7 is a diagram for explaining an effect removing action of a pulsating flow component accompanying a change in a unit flow rate (the size of the ridge) of the flow ridge.
FIG. 8 is a diagram for explaining the effect removal effect of the pulsating flow component accompanying the management time of the instantaneous flow rate at the flow rate 升.
FIG. 9 is a perspective view showing a schematic configuration of a thermal flow sensor.
FIG. 10 is a configuration diagram of an integrating flow meter using a conventional general flow rate soot.
FIG. 11 is a diagram showing a schematic processing operation of an integrating flow meter using a flow rate soot.
[Explanation of symbols]
1 Flow sensor 1a Low-speed flow sensor (measuring range; small)
1b High-speed flow sensor (measuring range; large)
2 Flow rate 2a First flow rate (Unit flow rate; Small; 10L)
2b Second flow rate 升 (unit flow rate; large; 40L)
3 Accumulator 13 Sensor selection means 16 Pulsation determination means 17 Flow rate selection means 19 Timer management means

Claims (4)

A thermal flow sensor for measuring the instantaneous flow rate of fluid passing through a predetermined flow path;
The instantaneous flow rate measured by the thermal flow sensor is integrated, and when the integrated value reaches a predetermined unit flow rate, a unit flow rate signal is output, and the flow rate す る that resets the integrated value,
A flow rate integrating means for counting the unit flow rate signal output from the flow rate so as to obtain an integrated flow rate of the fluid flowing through the predetermined flow path;
Pulsation detecting means for detecting a pulsation state of fluid in the flow path;
Together when the pulsation is detected is set wider measurement range by the thermal flow sensor by the pulsation detection means, characterized by including a measuring range change means for increasing the unit flow that is integrated in the flow boxes Integrated flow meter. The thermal flow sensor consists of a high-speed flow sensor with a wide measurement range for high flow rate measurement incorporated in the flow path and a low-speed flow sensor with a narrow measurement range for low flow rate measurement,
The measurement range changing means, Rutotomoni in normal actuates the low-speed flow sensor, using a smaller first flow squares of unit flow rate, when the pulsation is detected by the pulsation detecting means actuates the high-speed flow sensor The integrated flow meter according to claim 1, wherein a second flow rate rod having a large unit flow rate is used .   The pulsation detecting means detects that the fluid is pulsating when a reverse flow of the fluid is detected or when an instantaneous flow rate exceeding a measurement range of a thermal flow sensor is detected. Item 1. The integrated flow meter according to item 1.   2. The integrated flow rate according to claim 1, wherein the pulsation detecting unit detects that the fluid is pulsating when an integrated value of an instantaneous flow rate at the flow rate does not reach the unit flow rate within a predetermined time. Total.

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