JP2000275072A - Flowmeter, method for determining abnormality in flow sensor, record medium storing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flowmeter capable of easily checking the presence or absence of abnormality in a low-flow sensor and a high-flow sensor. SOLUTION: A flow quantity computing circuit 24 computes the quantity of flow of a fluid on the basis of a frequency based on fluctuations in pressure detected by a high-flow sensor 15 and computes the quantity of flow of the fluid on the basis of the differential pulse output between a first pulse output and a second pulse output detected by a low-flow sensor 17. A sensor switching part 30 switches from the low- flow sensor 17 to the high-flow sensor 15 in the case that the quantity of flow detected by the low-flow sensor 17 reaches a switching upper limit within a flow switching range and switches from the high-flow sensor 15 to the low-flow sensor 17 in the case that the quantity of flow detected by the high-flow sensor 15 reached a switching lower limit within the flow switching range. A sensor anomaly determining part 25 determines anomalies in the low-flow sensor 17 and the high-flow sensor 15 in the case that the error between the quantity of flow by the low-flow sensor 17 and the quantity of flow by the high-flow sensor 15 lies out of a predetermined error range in the case that the detected quantity of flow lies within the flow switching range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter and a flow sensor which can accurately measure from a small flow rate to a large flow rate and can easily check for an abnormality in a low flow rate sensor and a high flow rate sensor. The present invention relates to an abnormality determination method and a recording medium on which a program is recorded.

[0002]

2. Description of the Related Art As a flow meter capable of measuring a flow rate in a relatively wide range, for example, there is a fluidic flow meter A as shown in FIG. 15, and the fluidic flow meter A is provided in a housing 1 and the housing 1. The apparatus includes a nozzle member 2, a target 3, and a pressure sensor 4.

[0003] The housing 1 has a rectangular parallelepiped space 1a, and is connected to another flow path via an inflow port 1b and an outflow port 1c. The nozzle member 2 is constituted by a pair of left-right symmetrical members, and is provided so as to occupy a downstream portion of the space 1a. In the housing 1, an inflow space 1 d is formed on the upstream side of the nozzle member 2. The nozzle member 2 is
The upstream portion of the nozzle flow path 2a is formed in parallel and close to the nozzle flow path 2a, and is provided with wall surfaces 2c and 2d symmetrically extending from the nozzle flow path 2a in an arc shape.

[0004] The target 3 is provided in the detection space 2b and on an extension of the nozzle flow path 2a. The pressure sensor 4 is located in the detection space 2b, in the vicinity of the nozzle flow path 2a, and is provided on the left and right sides of the nozzle flow path 2a, and detects the vibration of the jet fluid ejected from the nozzle flow path 2a by pressure. .

[0005] In the fluidic flow meter A configured as described above, the flow of the ejected fluid flowing out from the nozzle flow path 2a periodically vibrates. That is, at a certain point, the ejected fluid flows along one side wall 3a of the target 3, a part rises along one wall 3b of the detection space 2b, returns to the nozzle outlet, and the other passes through the outlet 1c. Outflow. At a certain point in time, the ejected fluid flows as if it were drawn to the other wall surface 3b of the target. Such a vibration of the ejected fluid periodically occurs in the detection space 2b.

Since there is a proportional relationship between the frequency of the ejected fluid and the flow rate of the ejected fluid, the fluid vibration frequency is obtained by detecting the static pressure of the ejected fluid with the pressure sensor 4 to obtain the fluid oscillation frequency. Flow rate can be measured. The flow rate Q, if it is 0.2m ³ / h~5m ³ / h, the flow rate Q
Can be measured accurately.

However, when the flow rate Q is less than 0.2 m ³ / h, the oscillation of the ejected fluid becomes unstable, so that the linearity between the flow rate Q and the frequency F of the ejected fluid is disturbed, and the error is reduced. Will do. Therefore, the fluidic flow meter A is not suitable for measuring a small flow rate.

As another flow meter, there is a rectangular flow type flow meter B as shown in FIG. The rectangular flow path type flow meter B includes a housing 110, a flow path forming member 120 provided in the housing 110, and a sub-housing 130 provided on an upstream side of the housing 110.

The housing 110 has a rectangular parallelepiped space 110.
a through the inlet 110b.
0 and is connected to another flow path through the outlet 110c. The flow path forming member 120 is constituted by a pair of left and right symmetrical members, and is provided so as to occupy an upstream portion of the space 110a. For this reason, in the housing 110, the outflow space 110d is provided downstream of the flow path forming member 120.
Are formed. The flow path forming member 120 constitutes a rectangular flow path 121 having a rectangular cross section in which the upstream portion is parallel and close to each other.

The sub-housing 130 has a rectangular parallelepiped inflow space 130a, and is connected to an inflow port 110b of the housing 110 through an outflow port 130c. The inflow port 110b and the outflow port 110c are continuously and smoothly formed from the inflow space 130a toward the rectangular flow path 121. The sub-housing 130 has an inlet 130 in a direction orthogonal to the direction of fluid flow in the rectangular flow path 121.
Two b are formed.

Further, the cross-sectional area of the inflow space 130a in the direction orthogonal to the flow direction of the fluid in the rectangular flow path 121 is formed to be equal to the cross-sectional area of the outflow space 110d in the same direction. Further, the sub-housing 130 is provided with an inflow pressure sensor 140a for measuring a static pressure in the inflow space 130a.
An outflow pressure sensor 140b for measuring the static pressure in the outflow space 110d is provided.

In the rectangular flow meter having such a configuration, the difference between the static pressures on the upstream and downstream sides of the rectangular flow channel 121, that is, the inflow pressure sensor 140a and the outflow pressure sensor There is a linear relationship between the differential pressure of each pressure measured at 140b and the flow rate Q flowing through the rectangular channel 121. Therefore, the rectangular flow path type flow meter B
In the laminar flow region where the fluid flow is stable and the slope of the straight line is constant, that is, it is preferable in terms of accuracy to measure in the region on the small flow rate side from the transition region, and it is preferable to measure the small flow rate than the large flow rate measurement. Suitable.

As described above, the fluidic flow meter A (high flow rate sensor) is suitable for measuring a large flow rate, and the rectangular flow path type flow meter (low flow rate sensor) is suitable for measuring a small flow rate. For this reason, when the flow rate is small, the flow rate is switched to the rectangular flowmeter B side, and when the flow rate is large, the flow rate is switched to the fluidic flow meter, so that a wide flow rate from a small flow rate to a large flow rate can be accurately measured.

In this case, when the flow rate Q is measured by the low flow rate sensor while the flow rate is increasing, when the output value of the low flow rate sensor exceeds P1 and reaches P2, the low flow rate sensor is switched to the high flow rate sensor. , The flow rate Q is measured from the frequency F2 of the high flow rate sensor. When the flow rate Q is measured by the high flow rate sensor while the flow rate Q is decreasing, when the output value of the high flow rate sensor reaches a frequency F1 smaller than the frequency F2, the high flow rate sensor is switched to the low flow rate sensor, The flow rate Q is measured from the output value P1 of the flow rate sensor.

[0015]

However, when an abnormality occurs in the low flow rate sensor or the high flow rate sensor, the accuracy of the flow rate measurement by both flow rate sensors deteriorates. Also,
When a sensor abnormality occurs in which the output value of the low flow rate sensor decreases due to a voltage drop or the attachment of a drain to the sensor surface, it may not be possible to switch from the low flow rate sensor to the high flow rate sensor.

Further, when the output value of the low flow sensor indicates an abnormally higher value than the normal value, switching from the low flow sensor to the high flow sensor and switching from the high flow sensor to the low flow sensor are performed. Switching was sometimes repeated in a loop. That is, a sensor abnormality has occurred.

Accordingly, an object of the present invention is to provide a flow meter, a flow sensor abnormality determination method, and a recording medium on which a program is recorded, which can easily check the presence or absence of abnormality in the low flow sensor and the high flow sensor. I do.

[0018]

The present invention has the following arrangement to solve the above-mentioned problems. The flowmeter according to the first aspect of the present invention includes a high flow rate sensor for measuring a large flow rate that detects pressure fluctuation of periodic fluid vibration generated in a fluid ejected from a nozzle flow path, and a heater that heats a heater by an input pulse. A low flow rate sensor for measuring a small flow rate that outputs a first pulse output based on the temperature of the fluid before heating and a second pulse output based on the temperature of the fluid after heating the heater; The flow rate of the fluid is calculated based on the frequency based on the pressure fluctuation, and the flow rate of the fluid is calculated based on the difference pulse output between the first pulse output and the second pulse output detected by the low flow sensor. Calculating means for switching from the low flow rate sensor to the high flow rate sensor when the flow rate detected by the low flow rate sensor reaches a switching upper limit value within a switching flow rate range; A sensor switching means for switching from the high flow rate sensor to the low flow rate sensor when the amount reaches a switching lower limit value within the switching flow rate range, and the low flow rate sensor when the detected flow rate is within the switching flow rate range. It is determined whether an error between the detected flow rate and the flow rate detected by the high flow rate sensor is within a certain error range, and when the error is outside the certain error range, the low flow rate sensor and the high flow rate sensor are abnormal. And a sensor abnormality judging means for judging.

According to the flowmeter of the first aspect of the present invention, when the detected flow rate is within the switching flow rate range, the error between the detected flow rate by the low flow rate sensor and the detected flow rate by the high flow rate sensor is constant. It is determined whether the flow rate is within the error range or not.If the error is out of the predetermined error range, the low flow rate sensor and the high flow rate sensor are determined to be abnormal. You can check.

As in the flow meter according to the second aspect of the present invention, the sensor abnormality determining means determines whether or not the number of times the error falls outside the predetermined error range has reached a predetermined number of times. When the number of times reaches the specified number, the low flow rate sensor and the high flow rate sensor are determined to be abnormal.

According to the flowmeter of the present invention, the sensor abnormality determining means determines whether or not the number of times the error has fallen outside the predetermined error range has reached a predetermined number of times. When the predetermined number of times has been reached, the low flow rate sensor and the high flow rate sensor are determined to be abnormal, so that it is possible to accurately check whether or not the sensors are abnormal.

A flow meter according to a third aspect of the present invention includes a display means for displaying that the low flow sensor and the high flow sensor are abnormal based on a sensor abnormality signal output from the sensor abnormality determination means. Features.

According to the flowmeter of the present invention, the display means displays that the low flow sensor and the high flow sensor are abnormal based on the sensor abnormality signal output from the sensor abnormality determination means. Thus, it is possible to easily determine whether or not the sensor is abnormal.

A flowmeter according to a fourth aspect of the present invention is characterized in that the flowmeter includes a shutoff valve opening / closing means for closing a shutoff valve for shutting off the flow of the fluid based on a sensor abnormality signal output from the sensor abnormality determination means.

According to the flowmeter of the present invention, the shut-off portion opening / closing means closes the shut-off valve for shutting off the flow of the fluid based on the sensor abnormality signal output from the sensor abnormality determination means. Can be improved.

According to a fifth aspect of the present invention, a high flow rate sensor for measuring a large flow rate for detecting pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path, and a heater based on an input pulse. A low flow rate sensor for small flow rate measurement that outputs a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater, and the high flow rate sensor The flow rate of the fluid is calculated based on the frequency based on the pressure fluctuation detected in the above, and the flow rate of the fluid is calculated based on the difference pulse output between the first pulse output and the second pulse output detected by the low flow rate sensor. A flow rate calculating means for calculating, when the flow rate detected by the low flow rate sensor reaches a switching upper limit value within a switching flow rate range, switching from the low flow rate sensor to the high flow rate sensor; Sensor switching means for switching from the high flow rate sensor to the low flow rate sensor when the detected flow rate reaches the switching lower limit value within the switching flow rate range, and the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value In the case of, it is determined whether or not the detected flow rate of the fluid by the high flow rate sensor at that time has exceeded the switching upper limit value, and when the detected flow rate of the fluid by the high flow rate sensor has exceeded the switching upper limit value. And a sensor abnormality determining means for determining that the low flow rate sensor is abnormal.

According to the flowmeter of the present invention, when the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value, the sensor abnormality determination means sets the detected flow rate of the fluid by the high flow rate sensor at that time. If the output value of the low flow sensor is abnormally low, it is determined whether the switching upper limit value has been exceeded or not, and if the detected flow rate of the fluid by the high flow sensor exceeds the switching upper limit value, the low flow sensor is determined to be abnormal. In addition, it is possible to easily check whether or not the low flow rate sensor is abnormal.

According to a sixth aspect of the present invention, the sensor abnormality determining means determines that the number of times that the detected flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit reaches a predetermined specified number. It is determined whether or not the low flow rate sensor is abnormal when the number of times reaches the specified number of times.

According to the flowmeter of the present invention, the sensor abnormality determining means determines whether or not the number of times the detected flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit value has reached a predetermined number of times. Is determined, and when the number of times reaches the specified number, the low flow rate sensor is determined to be abnormal, so that the presence or absence of abnormality in the low flow rate sensor is accurately checked.

A flow meter according to a seventh aspect of the present invention provides a high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path, and a heater which is operated by an input pulse. A low flow rate sensor for small flow rate measurement that outputs a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater, and the high flow rate sensor The flow rate of the fluid is calculated based on the frequency based on the pressure fluctuation detected in the above, and the flow rate of the fluid is calculated based on the difference pulse output between the first pulse output and the second pulse output detected by the low flow rate sensor. A flow rate calculating means for calculating, and a second frequency higher than the first frequency when the differential pulse of the low flow rate sensor reaches a second differential pulse output larger than the first differential pulse output. Sensor switching means for switching to the high flow rate sensor for applying pressure, and switching to the low flow rate sensor for outputting the first differential pulse output when the frequency of the high flow rate sensor reaches the first frequency; When the sensor difference pulse becomes a third difference pulse larger than the second difference pulse, the frequency of the high flow sensor is smaller than the first frequency when the low flow sensor is switched to the high flow sensor. And determining whether the low flow rate sensor is abnormal when the frequency is lower than the first frequency and switching from the high flow rate sensor to the low flow rate sensor is performed. It is characterized by.

According to the flowmeter of the present invention, when the difference pulse of the low flow sensor becomes the third difference pulse larger than the second difference pulse, and the low flow sensor is switched to the high flow sensor, The sensor abnormality determining means determines whether or not the frequency of the high flow rate sensor is lower than the first frequency. If the frequency is lower than the first frequency and the high flow rate sensor is switched to the low flow rate sensor, the low flow rate is determined. Since the sensor is determined to be abnormal, when the output value of the low flow sensor is abnormally high, it is possible to easily check whether the low flow sensor is abnormal.

As in the flow meter according to the present invention, the sensor abnormality judging means may switch the number of times of switching from the low flow sensor to the high flow sensor and the number of times of switching from the high flow sensor to the low flow sensor. It is characterized in that it is determined whether or not a predetermined number of times has been reached, and when the number of times has reached the specified number of times, the low flow rate sensor is determined to be abnormal.

According to the flowmeter of the present invention, the sensor abnormality judging means sets a predetermined number of times of switching from the low flow sensor to the high flow sensor and from the high flow sensor to the low flow sensor. It is determined whether or not the number of times has reached the predetermined number. If the number of times has reached the specified number, the low flow rate sensor is determined to be abnormal.

The flowmeter according to the ninth aspect of the present invention is characterized in that the flowmeter is provided with display means for displaying that the low flow rate sensor is abnormal based on a sensor abnormality signal output from the sensor abnormality determination means.

According to the flowmeter of the ninth aspect, the display means displays that the low flow rate sensor is abnormal based on the sensor abnormality signal output from the sensor abnormality determination means. The presence / absence of a sensor abnormality can be easily determined.

A flowmeter according to a tenth aspect of the present invention is characterized in that the flowmeter includes a shutoff valve opening / closing means for closing a shutoff valve for shutting off the flow of the fluid based on a sensor abnormality signal output from the sensor abnormality determination means.

According to the flowmeter of the present invention, the shut-off valve opening / closing means closes the shut-off valve for shutting off the inflow of fluid based on the sensor abnormality signal output from the sensor abnormality determination means. Can be improved.

[0038] The flow sensor abnormality determination method according to the eleventh aspect of the present invention is based on a pressure fluctuation from a high flow rate sensor for measuring a large flow rate, which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. Calculating a flow rate of the fluid based on a frequency, heating the heater with the input pulse, and outputting a first pulse based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. Calculating a flow rate of the fluid based on a difference pulse output between a first pulse output and a second pulse output from a low flow rate sensor for small flow rate measurement that outputs a pulse output of the low flow rate sensor; When the flow rate reaches the switching upper limit value within the switching flow rate range, the low flow rate sensor is switched to the high flow rate sensor, and the flow rate detected by the high flow rate sensor is changed to the switching flow rate range. A step of switching from the high flow rate sensor in the low-flow rate sensor when it reaches the switching lower limit,
When the detected flow rate is within the switching flow rate range, it is determined whether an error between the flow rate detected by the low flow rate sensor and the flow rate detected by the high flow rate sensor is within a fixed error range, and the error is determined to be within the predetermined range. Determining that the low flow rate sensor and the high flow rate sensor are abnormal when the error is outside the error range.

According to the eleventh aspect of the present invention, when the flow rate is within the switching flow rate range, the error between the flow rate detected by the low flow rate sensor and the flow rate detected by the high flow rate sensor falls within a certain error range. It is possible to easily check whether the low flow sensor and the high flow sensor are abnormal to determine whether or not there is an abnormality, and to determine that the low flow sensor and the high flow sensor are abnormal if the error is outside the certain error range. it can.

A flow sensor abnormality determination method according to a twelfth aspect of the present invention is based on a pressure fluctuation from a high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. Calculating a flow rate of the fluid based on a frequency, heating the heater with the input pulse, and outputting a first pulse based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. Calculating a flow rate of the fluid based on a difference pulse output between a first pulse output and a second pulse output from a low flow rate sensor for small flow rate measurement that outputs a pulse output of the low flow rate sensor; When the flow rate reaches the switching upper limit value within the switching flow rate range, the low flow rate sensor is switched to the high flow rate sensor, and the flow rate detected by the high flow rate sensor is changed to the switching flow rate range. A step of switching from the high flow rate sensor in the low-flow rate sensor when it reaches the switching lower limit,
When the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value, it is determined whether or not the detected flow rate of the fluid by the high flow rate sensor at that time exceeds the switching upper limit value. Determining the low flow rate sensor as abnormal when the flow rate detected by the sensor exceeds the switching upper limit value.

According to the twelfth aspect, when the flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value, it is determined whether the flow rate of the fluid by the high flow rate sensor at that time exceeds the switching upper limit value. If the flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit, the low flow rate sensor is determined to be abnormal, so if the output value of the low flow rate sensor is abnormally low, it is easy to determine whether the low flow rate sensor is abnormal. You can check.

According to a thirteenth aspect of the present invention, there is provided a flow rate sensor abnormality determination method based on a pressure fluctuation from a high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. Calculating a flow rate of the fluid based on a frequency, heating the heater with the input pulse, and outputting a first pulse based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. Calculating a flow rate of the fluid based on a difference pulse output between a first pulse output and a second pulse output from a low flow rate sensor for measuring a small flow rate that outputs a pulse output of the low flow rate sensor; Switching to the high flow rate sensor that outputs a second frequency greater than the first frequency when the pulse reaches a second differential pulse output greater than the first differential pulse output Switching to the low flow rate sensor that outputs the first differential pulse output when the frequency of the high flow rate sensor has reached the first frequency; and wherein the differential pulse of the low flow rate sensor is the second differential pulse. It is determined whether or not the frequency of the high flow rate sensor is smaller than the first frequency when the low flow rate sensor is switched from the low flow rate sensor to the high flow rate sensor when the third difference pulse is larger than the third differential pulse. Determining that the low flow rate sensor is abnormal when the high flow rate sensor is switched from the high flow rate sensor to the low flow rate sensor lower than the first frequency.

According to the thirteenth aspect of the present invention, when the differential pulse of the low flow sensor becomes the third differential pulse larger than the second differential pulse and the low flow sensor is switched to the high flow sensor, the high flow sensor It is determined whether the frequency of the low flow rate sensor is lower than the first frequency. If the frequency is lower than the first frequency and the high flow rate sensor is switched to the low flow rate sensor, the low flow rate sensor is determined to be abnormal. When the output value of the flow rate sensor is abnormally high, it is possible to easily check whether the low flow rate sensor is abnormal.

According to a fourteenth aspect of the present invention, a computer is provided based on a frequency based on a pressure fluctuation from a high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. Calculating the flow rate of the fluid, heating the heater with the input pulse, and outputting a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. 1st output from low flow rate sensor for small flow rate measurement
Calculating the flow rate of the fluid based on the difference pulse output between the pulse output of the second pulse output and the second pulse output. The low flow rate sensor when the flow rate detected by the low flow rate sensor reaches a switching upper limit value within a switching flow rate range. Switching from the high flow sensor to the low flow sensor when the flow rate detected by the high flow sensor reaches the switching lower limit value within the switching flow rate range, the detection flow rate being the switching flow rate It is determined whether an error between the flow rate detected by the low flow rate sensor and the flow rate detected by the high flow rate sensor is within a certain error range when the error is outside the certain error range. A recording medium storing a program for executing a procedure for determining that the low flow rate sensor and the high flow rate sensor are abnormal, and a program recorded on the recording medium. Beam is by executing each step, it is possible to easily check the presence or absence of abnormality of the low flow rate sensor and a high flow rate sensor.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of a flow meter and a flow sensor abnormality determination method according to the present invention will be described below in detail with reference to the drawings.

<First Embodiment> FIG. 1 shows a first embodiment of the present invention.
It is a lineblock diagram of a flow meter of an embodiment. In FIG.
The fluidic element 11 accurately measures the flow rate of a fluid such as gas in a wide range from a small flow rate to a large flow rate.
Inlet 13a for inflow of fluid, outlet 1 for outflow of fluid
3b, a high flow rate sensor 15 for measuring a large flow rate is provided on the upper surface side, and a low flow rate sensor 17 for measuring a small flow rate is provided on the lower surface side.

The high flow rate sensor 15 is, for example, a fluidic sensor. Fluid vibration is generated in the ejected fluid ejected from the nozzle flow path, and the frequency of the periodic fluid oscillation is proportional to the flow rate or flow rate of the ejected fluid. Since the relationship exists, the flow rate of the ejected fluid is detected. The low flow sensor 17 is, for example, a heat flow sensor, and the details of the heat flow sensor will be described later.

The pressure detection circuit 19 converts the pressure fluctuation detected by the high flow sensor 15 into an electric signal. The waveform shaping circuit 20 shapes the waveform by removing unnecessary signals such as noise from the electric signal converted by the pressure detecting circuit 19. The frequency detection circuit 21 detects a frequency from the electric signal whose waveform has been shaped by the waveform shaping circuit 20. The flow rate calculation circuit 24
A flow rate flowing through the fluidic element 11 is calculated from a predetermined relational expression between the frequency F and the flow rate Q based on the frequency detected by the frequency detection circuit 21.

The pulse generator 22 generates a pulse and outputs the generated pulse to the low flow sensor 17. The pulse detection circuit 23 detects the first pulse output and the second pulse output from the low flow rate sensor 17 and outputs them to the flow rate calculation circuit 24. The flow rate calculation circuit 24 counts the number of pulses of the first pulse output and the second pulse output from the pulse detection circuit 23, and calculates the difference between the count data of the first pulse output and the count data of the second pulse output. The flow rate flowing through the fluidic element 11 is calculated using a first-order approximation formula based on the pulse output.

The sensor switching section 30 is provided in the flow rate calculation circuit 24, and switches from the low flow rate sensor 17 to the high flow rate sensor 15 when the flow rate detected by the low flow rate sensor 17 reaches the switching upper limit value within the switching flow rate range. When the flow rate detected by the high flow rate sensor 15 reaches the switching lower limit value within the switching flow rate range, the high flow rate sensor 15 is switched to the low flow rate sensor 17.

When the measured flow rate is within the switching flow rate range between the two flow rate sensors, the flow rate calculation circuit 24 determines the output P ₀ of the low flow rate sensor 17 and the output F _{0 of the} high flow rate sensor 15.
It was measured, to calculate the flow rate Q _L from the output P ₀ of the measured low flow sensor 17, and calculates the flow rate Q _H from the output F ₀ of the high flow rate sensor 15.

[0052] sensor abnormality determination section 25 determines an error between the flow rate Q _L and the flow rate Q _H is whether the outside constant error range, the error of the flow rate Q _L and the flow rate Q _H is outside a predetermined error range In this case, it is determined whether or not the number of times the error falls within the predetermined error range is equal to or more than a specified number. If the number is equal to or more than the specified number, the sensor of the high flow rate sensor 15 and the low flow rate sensor 17 is used. It outputs a sensor abnormality signal to indicate abnormality.

The LCD 26 displays a sensor abnormality signal. The shut-off valve opening / closing section 27 closes a shut-off valve provided in the gas meter based on the sensor abnormality signal. Integrated flow holding unit 2
Numeral 8 holds the integrated flow rate when the sensor abnormality signal is output. The date and time information holding unit 29 holds date and time information when the sensor abnormality signal is output.

FIG. 2 is a detailed configuration diagram of the fluidic element 11. The fluidic element 11 shown in FIG. 2 is provided with an inflow port 13a through which gas flows, and the tip of the inflow port 13a has a tapered portion 31a which expands in a tapered shape.
31b are formed. These tapered portions 31a, 31b
A semi-cylindrical semi-cylindrical member 32 is provided directly below the semi-cylindrical member 32. The semi-cylindrical member 32 is located immediately above the nozzle flow path 2a, and gas flowing from the upstream flows through the nozzle flow path 2a.
To prevent direct hits. Also, the semi-cylindrical member 32
A wire mesh 33 is disposed between the nozzle and the nozzle inlet 34. The inflow port 13a and the outflow port 13c are provided with connection flange portions 13b and 13d.

A low flow sensor mounting hole 35 for mounting the low flow sensor 17 is provided near the nozzle inlet 34. The pressure outlet 4a is disposed symmetrically at the outlet of the nozzle flow path 2a, and is a high flow sensor 1 that is a pressure sensor.
An outlet for taking out the pressure of No. 5.

The other configuration shown in FIG. 2 is the same as that shown in FIG.
Are the same as those shown in FIG. 1, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

FIG. 3 is a configuration diagram of the gas meter. In the gas meter shown in FIG. 3, the fluidic element 11
The main processor unit (MPU) 41 includes the high flow rate sensor 15 and the low flow rate sensor 17, and the low flow rate sensor 1
7, a low flow sensor input port 42 for inputting the output of the high flow sensor 15, a high flow sensor input port 43 for inputting the output of the high flow sensor 15, and an output port 44 connected to the LCD 26.

The MPU 41 includes a central processing unit (CPU) 45 for executing processing, a read-only memory (ROM) 46 for recording a program 51 and constants, a timer T,
It has a random access memory (RAM) 47 for reading and writing the integrated flow rate S, date and time information DATE, and counter C, and an EPROM 48 for storing the integrated flow rate S and date and time information when the sensor accuracy is reduced and the sensor cannot be used. Flow rate calculation circuit 24, sensor switching unit 30, and sensor abnormality determination unit 25
Is a program 5 stored in the ROM 46 by the CPU 45.
1 is a function for executing The integrated flow rate holding unit 28 and the date and time information holding unit 29 are provided in the EPROM 48.

FIG. 4 shows a configuration diagram of the low flow rate sensor. The low flow rate sensor 17 heats the micro-heater according to the clock signal from the pulse generation unit 22, and based on the first pulse output P based on the temperature of the fluid before the micro-heater is heated and based on the temperature of the fluid after the micro-heater is heated. The second pulse output P is output to the pulse detection circuit 23.

The low flow rate sensor 17 is driven by a Si substrate 62, a diaphragm 63, a micro heater 64 formed on the diaphragm 63, a downstream thermopile 65 formed on the diaphragm 63 at the lower end of the micro heater 64, and a micro heater 64. A power supply line 66 for supplying current, a first output line 67 for outputting a first temperature detection signal (first pulse output) output from the downstream thermopile 65, and an upper end of the micro heater 64 are formed on the diaphragm 63. Upstream thermopile 68, Upstream thermopile 68
Temperature detection signal (second pulse output) output from
Is provided.

In the above configuration, the micro heater 64
Heats the fluid intermittently with an external drive current,
In parallel with the heating of the micro heater 64, the upstream thermopile 68 detects the temperature of the fluid before being heated by the micro heater 64 and outputs a first temperature detection signal. The temperature of the fluid after being heated by the H.64 is detected, and a second temperature detection signal is output. Therefore, the flow rate of the fluid can be calculated based on the first temperature detection signal and the second temperature detection signal.

FIG. 5 is a diagram showing switching between the low flow sensor and the high flow sensor when the sensor is normal.
5, the horizontal axis represents the flow rate Q, the left vertical axis represents the low flow sensor output (pulse output P), and the right vertical axis represents the high flow sensor output (frequency F). Diverter amount range is a range from the flow Q ₁ is a switching lower limit to the flow rate Q ₂ is switched upper limit value. The flow rate Q ₂ is the low flow rate sensor 1
The flow rate when switched from 7 to high flow rate sensor 15, the flow rate Q ₁ is a flow rate when it is switched from the high flow rate sensor 15 to the low flow rate sensor 17.

The low flow sensor output corresponding to the flow Q ₂ is:
P ₂ , and the output of the high flow sensor corresponding to the flow Q ₂ is F
₂ The low flow rate sensor output corresponding to the flow rate Q ₁ is a P _1, a high flow rate sensor output corresponding to the flow rate Q ₁ is a F _1. The flow rate Q ₀ is larger than the flow rate Q _{1 and} smaller than the flow rate Q ₂ . If a low-flow rate sensor 17 and a high flow rate sensor 15 is normal, the flow rate Q _L and the flow rate Q _H is equal to the flow rate Q _0.

[0064] However, when the low flow rate sensor 17 and a high flow rate sensor 15 is abnormal because the slope of the straight line of the low-flow rate sensor 17 and the inclination of the straight line of the high flow rate sensor 15 is changed, the flow rate Q _L and the flow rate Q _H is no longer equal to the flow rate Q ₀ ,
An error occurs.

Next, a basic check process (flow sensor abnormality determination process) of the low flow sensor and the high flow sensor provided in the flow meter according to the first embodiment configured as described above, is performed. This will be described with reference to the flowchart shown in FIG. First, the flow rate Q is measured by both the low flow rate sensor 17 and the high flow rate sensor 15 (step S1).
01).

Next, it is determined whether or not the measured flow rate Q is within the switching flow rate range of both flow sensors (step S10).
3). When the flow rate Q is within the switching flow rate range between the two flow rate sensors, the output P ₀ of the low flow rate sensor 17 and the high flow rate sensor 1
The output F ₀ of 5 measured (step S105). Calculating the flow rate Q _L from the output P ₀ of the measured low flow sensor 17,
Calculating the flow rate Q _H from the output F ₀ of the high flow rate sensor 15 (step S107).

Next, the flow rate Q _L and the error of the flow rate Q _H is determined whether within a predetermined error range (step S109), when the error of the flow rate Q _L and the flow rate Q _H is within a predetermined error range Returns to step S101, and performs the processing after step S101.

Meanwhile, if the error between the flow rate Q _L and the flow rate Q _H is outside a predetermined error range, (determining whether the number of times that the error is out of a predetermined error range is equal to or more than a specified number of times S111). If the number is less than the specified number, the process returns to step S101 and returns to step S101.
Each process from 101 to step S111 is repeated.

On the other hand, if the number of times is equal to or more than the specified number, a sensor abnormality signal for indicating the sensor abnormality of the high flow rate sensor 15 and the low flow rate sensor 17 is output to the LCD 26 (step S113). For this reason, the LCD 26
The blinking display indicates that the low flow sensor 17 and the high flow sensor 15 are abnormal. Further, a sensor abnormality signal is output to the shutoff valve opening / closing section 27, and the shutoff valve opening / closing section 27
The shutoff valve is closed (Step S115).

[0070] According to the flowmeter of the first embodiment of this configuration, when the error of the flow rate Q _L and the flow rate Q _H is outside a predetermined error range, the error becomes outside a predetermined error range It is determined whether or not the number of times has exceeded the specified number of times.
6, it is possible to easily check that the high flow rate sensor 15 and the low flow rate sensor 17 are abnormal. Thereby, the measurement accuracy of the sensor can be improved. Further, since the shut-off valve is closed by outputting the sensor abnormality signal to the shut-off valve opening / closing section 27, the safety of the gas meter can be ensured.

The program 5 recorded in the ROM 46
1 is a procedure for calculating a flow rate of a fluid based on a frequency based on a pressure change from the high flow rate sensor 15, a difference between a first pulse output and a second pulse output from the low flow rate sensor 17. procedure for calculating the flow rate of the fluid based on the pulse output, switching from the low flow rate sensor 17 to the high flow rate sensor 15 when the flow rate detected by the low flow sensor 17 has reached the switching limit Q ₂ in the switching flow amount range, high flow rate sensor procedure for switching when the detected flow rate by 15 reaches the switching lower limit to Q ₁ in switching flow amount ranging from a high flow rate sensor 15 to the low-flow rate sensor 17, detects the flow rate by the low-flow rate sensor 17 when the flow rate is within the switching flow amount range It is determined whether or not the error between the flow rate detected by the high flow rate sensor 15 and the flow rate detected by the high flow rate sensor 15 is within a certain error range. In order to execute the procedure for determining that the high flow sensor 15 and the high flow sensor 15 are abnormal, it is possible to easily check whether the low flow sensor 17 and the high flow sensor 15 are abnormal.

Next, a more detailed operation of the flow meter according to the first embodiment will be described with reference to flowcharts shown in FIGS. First, the number of times of high flow sensor measurement is set to 'JJ ₀ ', the integrated flow rate S is set to '0', the allowable error is set to 'E ₀ ', the allowable number of times is set to 'C ₀ ', and the number of low flow sensor measurements is set to 'J ₀ '. _It is set to ₀ '(step S201).

Next, the number of times J is set to "0" (step S2).
03), the flow rate Q is measured by the low flow rate sensor 17 (step S205), and the addition result obtained by adding the flow rate Q to the integrated flow rate S is set as a new integrated flow rate S (step S207).
The number C is set to '0' (step S209).

Next, when the flow rate Q is equal to or more than the flow rate Q ₁ and the flow rate Q
There determines whether less than the flow rate Q ₂ (step S21
1). If and flow Q at a flow rate Q is the flow rate Q ₁ or is less than the flow rate Q ₂ is, the number J is determined whether the low flow rate sensor measuring the number J ₀ or more (step S213). Number J is the case where a low flow rate sensor measuring the number J ₀ or calculates the flow rate Q _L in the low flow rate sensor 17 (step S215),
Calculating the flow rate Q _H in the high flow rate sensor 15 (step S2
17). Furthermore, based on the calculated flow rate Q _L and the flow rate Q _H calculates an error E of the two flow sensors according to the following equation (step S219).

[0075] _{E = 100 (Q L -Q H} ) / Q L Next, the calculated error E predetermined constant error E ₀
It is determined whether it is smaller than (step S221),
If the error E is larger than the fixed error E ₀ , the number of times C is incremented by 1 (step S223), and the number of times C
Is greater than or equal to the allowable number of times C ₀ (step S2).
25).

If the number C is equal to or greater than the allowable number C ₀ , the integrated flow rate S is stored (step S227), the date and time information is stored (step S229), the shutoff valve is closed (step S231), and the flow rate is displayed. Blinks (step S2).
33).

On the other hand, in step S221, the error E
Is smaller than the fixed error E ₀ , the number of times J is set to “0”.
(Step S235), the number of times JJ is set to “0” (Step S237), and it is determined whether or not the coefficient K is “1” (Step S239). If the coefficient K is “1”, the coefficient K is set to “0” (step S241), and the process proceeds to step S263. If the coefficient K is not “1”, the process proceeds to step S245. Further, in step S213, if the number J is less than the low flow rate sensor measuring the number of J _0, the process proceeds to step S243. That is, when the number of times of measuring the low-flow sensor becomes _zero J, a check sensor abnormality performed.

On the other hand, in step S211, the flow rate Q
There flow Q ₁ less than or flow rate Q in the case of the flow rate Q ₂ or more increments the number J by 1 (step S24
3), the flow rate Q is determined whether less than the flow rate Q ₂ (step S245), when the flow rate Q is less than the flow rate Q ₂ is,
It returns to step S205.

If the flow rate Q is equal to or larger than the flow rate Q ₂ , the number JJ is set to “0” (step S 247), and the high flow sensor 15 measures the flow rate Q (step S 24).
9). The addition result obtained by adding the flow rate Q to the integrated flow rate S is set as a new integrated flow rate S (step S251), and the number of times C is set to “0”.
(Step S253).

Next, when the flow rate Q is equal to or more than the flow rate Q ₁ and the flow rate Q
But to determine whether less than the flow rate Q ₂ (step S25
5). If the flow rate Q is and the flow rate Q at a flow rate Q ₁ or is less than the flow rate Q ₂ are the number JJ high flow rate sensor measuring the number JJ
_It is determined whether it is ₀ or more (step S257). If the number JJ is equal to or greater than the high flow rate sensor measurement number JJ ₀ , the coefficient K is set to “1” (step S259), and the process returns to step S215. If the number of JJ is less than the high flow rate sensor measuring the number JJ _0, the process proceeds to step S261.

If the flow rate Q is less than the flow rate Q ₁ or the flow rate Q is equal to or more than the flow rate Q ₂ , the number JJ is incremented by 1 (step S 261), and it is determined whether the flow rate Q is equal to or more than the flow rate Q ₁ (step S 261). Step S263). If the flow rate Q is the flow rate Q ₁ or more, the process returns to step S249. If the flow rate Q is less than the flow rate Q ₁ is, the process returns to step S205.

As described above, the same effect as the effect of the processing of the flowchart shown in FIG. 6 can be obtained also by the processing of the flowchart shown in FIG. 7 and the processing of the flowchart shown in FIG.

<Second Embodiment> Next, a second embodiment of the present invention will be described.
The flow meter according to the embodiment will be described. FIG. 9 shows the second embodiment of the present invention.
It is a lineblock diagram of a flow meter of an embodiment. In the flow meter according to the second embodiment, when the low flow rate sensor is in an abnormal state showing an abnormally low output value due to the voltage drop or the adhesion of the drain to the sensor surface, the abnormal state is determined. It is characterized by detecting.

FIG. 10 is a diagram for explaining an output abnormality when the low flow rate sensor indicates a value lower than usual.
In FIG. 10, a straight line when the low flow rate sensor is normal is indicated by a dotted line, and a straight line when the low flow rate sensor is abnormal is indicated by a solid line. Since the output of the low flow sensor is low, switching from the low flow sensor to the high flow sensor does not occur.

For example, when the flow rate is Q _A , the output A corresponds to a normal low flow rate sensor. However, when an abnormality occurs in the low flow rate sensor and the output decreases, only the output A 'is obtained. The output A ', the flow rate corresponding to the "corresponding. Output A to" output A in the normal low-flow sensor is Q _A' is. For this reason, originally, Q _A > Q
Where ₂ is satisfied, Q _A ′ <Q ₂ . As a result, switching between the low flow sensor 17 and the high flow sensor 15 does not occur.

Therefore, when the flow rate of the fluid by the low flow rate sensor 17 is less than the switching upper limit value Q ₂ , the sensor abnormality determination unit 25 a determines that the flow rate of the fluid by the high flow rate sensor 15 at that time exceeds the switching upper limit value Q ₂ . to determine Taka not, determines low flow rate sensor 17 to be abnormal if the flow rate of the fluid by the high flow rate sensor 15 exceeds the switching limit Q _2.

The flow rate calculating circuit 24 and the sensor switching section 3
0 and the sensor abnormality determination unit 25a
This is a function for executing the program 51 recorded in 46.

The other configuration shown in FIG. 9 is the same as the configuration shown in FIG. 1, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

Next, a detailed check process (sensor abnormality determination process) of the presence or absence of an abnormality in the low flow sensor provided in the flow meter according to the second embodiment will be described with reference to a flowchart shown in FIG. First, the integrated flow rate S is set to “0”, the number of times of low flow sensor measurement is set to “N ₀ ”, and the number of high flow sensor checks is set to “C ₀ ” (step S301).

Next, the number N is set to "0" (step S3).
03), the flow rate Q is measured by the low flow rate sensor 17 (step S305), and the addition result obtained by adding the flow rate Q to the integrated flow rate S is set as a new integrated flow rate S (step S307).

[0091] Next, the flow rate Q is determined whether less than the flow rate Q ₂ (step S309), when the flow rate Q is less than the flow rate Q ₂ is, increments the count N by one (step S311), the number of times N There when low-flow sensor measuring the number of N ₀ to determine whether less than (step S313), the number N is smaller than the low flow rate sensor measuring the number of N _0, the
The process returns to step S305.

On the other hand, the number N is the number N _{0 of} low flow sensor measurement.
In the above case, the number of times C is set to “0” (step S31).
5) The flow rate Q _HA is measured by the high flow rate sensor 15 (step S317). Further, it is determined whether the flow rate Q _HA is smaller than the flow rate Q ₂ (step S319).

If the flow rate Q _HA is equal to or _larger than the flow rate Q ₂ , the number C is incremented by 1 (step S 321), and it is determined whether the number C is equal to or larger than the high flow sensor check number C ₀ (step S 323). If the number C is less than the high flow rate sensor check number C ₀ , step S317
Return to the processing of.

If the number C is equal to or greater than the high flow sensor check number C ₀ , the integrated flow rate S is stored (step S 3).
25), save the date and time information (step S327), close the shutoff valve (step S329), and blink the flow rate display (step S331). If the flow rate Q _HA is smaller than the flow rate Q ₂ in step S319, the number N
To '0' (step S333), and step S305
Return to the processing of.

On the other hand, in step S309, the flow rate Q
There the case where the flow rate Q ₂ or more, measures the flow rate Q at a high flow rate sensor 15 (step S335). The addition result obtained by adding the flow rate Q to the integrated flow rate S is set as a new integrated flow rate S (step S337).

[0096] Next, the flow rate Q is determined whether the flow rate Q ₁ or more (step S339), when the flow rate Q is the flow rate Q ₁ or more, the process returns to step S335, the flow rate Q is less than the flow rate Q ₁ If it is, the process returns to step S305.

As described above, according to the flow meter of the second embodiment, when the flow rate of the fluid detected by the low flow rate sensor 17 is less than the switching upper limit value, the sensor abnormality determination unit 25a determines whether the high flow rate sensor 15 The flow rate of the fluid detected by the high flow rate sensor 15 is determined to be abnormal if the detected flow rate of the fluid by the high flow rate sensor 15 exceeds the switching upper limit value. When the output value of the low flow rate sensor 17 is abnormally low, it is possible to easily check whether the low flow rate sensor 17 is abnormal.

Thus, the measurement accuracy of the sensor can be improved. Further, since the shut-off valve is closed by outputting the sensor abnormality signal to the shut-off valve opening / closing section 27, the safety of the gas meter can be ensured.

Although the flow rate Q ₂ and the flow rate Q _HA are compared in the flow meter according to the second embodiment described above, the comparison may be made at the frequency F, for example. In this case, the value of the frequency F of the high flow rate sensor 15 is measured every certain number of times (for example, 10 times) when the low flow rate sensor 17 operates. Then, when the frequency F is less than the frequency F ₂ is low flow sensor 17 is determined to be normal, when the frequency F is greater than the frequency F ₂ is low flow rate sensor 17 is a voltage drop and a drain sensor surface It may be determined that the output is reduced due to adhesion to the surface.

<Third Embodiment> Next, a third embodiment of the present invention will be described.
The flow meter according to the embodiment will be described. FIG. 12 is a configuration diagram of a flow meter according to the third embodiment of the present invention. The flowmeter according to the third embodiment is characterized in that, when the low flow sensor enters an abnormal state in which an abnormally high output value is indicated, the abnormal state is detected.

[0102] sensor switching section 30, as can be seen from FIG. 5, first when the differential pulse of the low flow rate sensor 17 reaches a second differential pulse output P ₂ greater than the first differential pulse output P ₁ A second frequency F ₂ greater than the first frequency F ₁
Switching to the high flow rate sensor 15 for outputting a switch to the low flow rate sensor 17 in which the frequency of the high flow rate sensor 15 outputs a first differential pulse output P ₁ when it reaches the first frequency F _1.

FIG. 13 is a diagram for explaining an output abnormality when the low flow rate sensor shows a value higher than usual.
As shown in FIG. 13, the output of the low flow rate sensor 17 shows a value higher than usual, and the slope of the output of the low flow rate sensor 17 increases.

[0103] sensor abnormality determination unit 25b, as shown in FIG. 13, high when a pulse of low flow rate sensor 17 is switched from a large pulse P ₀ becomes low flow rate sensor 17 than the pulse P ₂ to the high flow rate sensor 15 It is determined whether or not the frequency of the flow sensor 15 is lower than the frequency F _{1. If} the frequency is lower than the frequency F ₁ and the high flow sensor 15 is switched to the low flow sensor 17, the low flow sensor 17 is determined.
Is determined to be abnormal.

The flow rate calculation circuit 24 and the sensor switching section 3
0 and the sensor abnormality determination unit 25b
This is a function for executing the program 51 recorded in 46.

Note that the other configuration shown in FIG.
Are the same as those shown in FIG. 1, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

Next, with reference to the flow chart shown in FIG. 14, a detailed check processing (sensor abnormality judgment processing) of the presence or absence of abnormality of the low flow sensor provided in the flow meter of the third embodiment will be described.

First, the pulse P ₀ which is the output of the low flow rate sensor.
The measured (step S401), since the pulse P ₀ is the pulse P ₂ or more measured a low flow sensor output (step S403), switching from the low flow rate sensor 17 to the high flow rate sensor 15 (step S405).

Next, the frequency F ₀ output from the high flow rate sensor 15 is measured (step S407). Since the measured frequency F ₀ is lower than the frequency F ₁ (step S40).
9) The high flow rate sensor 15 is switched to the low flow rate sensor 17 (step S411), and the number N of times of switching is incremented by one (step S412).

Further, it is determined whether or not the number N of times of switching from the high flow rate sensor 15 to the low flow rate sensor 17 is equal to or greater than a specified number N ₀ (step S413).
_{If the value is} less than ₀ , the process returns to step S401, and the process from step S401 is repeated.

If the number N of times of switching is equal to or greater than the specified number N ₀ , a sensor abnormality signal indicating that the low flow rate sensor 17 is abnormal is output (step S 415).
Is stored in a memory such as an EPROM (step S417), and the shutoff valve is closed (step S419).

As described above, according to the flowmeter of the third embodiment, even if the low flow sensor 17 is in an abnormal state showing an abnormally high output value, the abnormality of the low flow sensor 17 can be easily determined. Can be detected. For this reason, measurement by an unusable gas meter does not occur, and measurement accuracy can be improved.

Note that the present invention is not limited to the flow meters of the first to third embodiments described above. In the flow meters of the first to third embodiments, a flow sensor is used. Instead of this flow sensor, a rectangular flow path type flow meter as shown in FIG. 16 may be used. In short, any other flow meter that can measure a small flow rate with high accuracy may be used.

Further, the flow meter to the third embodiment of the first embodiment
At least two of the flow meters according to the above embodiments may be used in combination. For example, if a flow meter combining the flow meter of the second embodiment and the flow meter of the third embodiment is used, even when the output of the low flow sensor 17 is high,
Even when the output of the low flow rate sensor 17 is low, the sensor abnormality can be easily determined. In addition, it goes without saying that various modifications can be made without departing from the technical idea of the present invention.

[0114]

According to the flowmeter of the first aspect of the present invention, when the detected flow rate is within the switching flow rate range, the sensor abnormality determining means determines the error between the flow rate detected by the low flow rate sensor and the flow rate detected by the high flow rate sensor. Is determined to be within a certain error range, and if the error is outside the certain error range, the low flow sensor and the high flow sensor are determined to be abnormal. You can easily check.

According to the flowmeter of the present invention, the sensor abnormality judging means judges whether or not the number of times that the error has fallen outside the predetermined error range has reached a predetermined number of times. When the predetermined number of times has been reached, the low flow rate sensor and the high flow rate sensor are determined to be abnormal, so that it is possible to accurately check whether or not the sensors are abnormal.

According to the flowmeter of the present invention, the display means indicates that the low flow sensor and the high flow sensor are abnormal based on the sensor abnormality signal output from the sensor abnormality determination means. Thus, it is possible to easily determine whether or not the sensor is abnormal.

According to the flowmeter of the present invention, the shut-off portion opening / closing means closes the shut-off valve for shutting off the flow of the fluid based on the sensor abnormality signal output from the sensor abnormality determination means. Can be improved.

According to the flowmeter of the present invention, when the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value, the sensor abnormality determination means sets the detected flow rate of the fluid by the high flow rate sensor at that time. If the output value of the low flow sensor is abnormally low, it is determined whether the switching upper limit value has been exceeded or not, and if the detected flow rate of the fluid by the high flow sensor exceeds the switching upper limit value, the low flow sensor is determined to be abnormal. In addition, it is possible to easily check whether or not the low flow rate sensor is abnormal.

According to the flowmeter of the present invention, the sensor abnormality determining means determines whether or not the number of times the detected flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit has reached a predetermined number of times. Is determined, and when the number of times reaches the specified number, the low flow rate sensor is determined to be abnormal, so that the presence or absence of abnormality in the low flow rate sensor is accurately checked.

According to the flowmeter of the present invention, when the difference pulse of the low flow sensor becomes the third difference pulse larger than the second difference pulse, and the low flow sensor is switched to the high flow sensor, The sensor abnormality determining means determines whether or not the frequency of the high flow rate sensor is lower than the first frequency. If the frequency is lower than the first frequency and the high flow rate sensor is switched to the low flow rate sensor, the low flow rate is determined. Since the sensor is determined to be abnormal, when the output value of the low flow sensor is abnormally high, it is possible to easily check whether the low flow sensor is abnormal.

According to the flowmeter of the present invention, the sensor abnormality determination means determines the predetermined number of times of switching from the low flow sensor to the high flow sensor and from the high flow sensor to the low flow sensor. It is determined whether or not the number of times has reached the predetermined number. If the number of times has reached the specified number, the low flow rate sensor is determined to be abnormal.

According to the flowmeter of the ninth aspect, the display means displays that the low flow rate sensor is abnormal based on the sensor abnormality signal output from the sensor abnormality determination means. The presence / absence of a sensor abnormality can be easily determined.

According to the flowmeter of the tenth aspect, the shut-off valve opening / closing means closes the shut-off valve for shutting off the inflow of the fluid based on the sensor abnormality signal output from the sensor abnormality determination means. Can be improved.

According to the flow rate sensor abnormality determination method of the eleventh aspect, when the flow rate is within the switching flow rate range, the error between the flow rate by the low flow rate sensor and the flow rate by the high flow rate sensor is within a certain error range. It is determined whether or not the low flow rate sensor and the high flow rate sensor are abnormal when the error is out of the predetermined error range. Therefore, it is possible to easily check whether the low flow rate sensor and the high flow rate sensor are abnormal.

According to the twelfth aspect, when the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value,
In order to determine whether the detected flow rate of the fluid by the high flow rate sensor at that time exceeds the switching upper limit value, and to determine that the low flow rate sensor is abnormal when the detected flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit value, When the output value of the low flow rate sensor is abnormally low, it is possible to easily check whether or not the low flow rate sensor is abnormal.

According to the thirteenth aspect, when the differential pulse of the low flow rate sensor becomes the third differential pulse larger than the second differential pulse and the low flow rate sensor is switched to the high flow rate sensor, It is determined whether the frequency of the low flow rate sensor is lower than the first frequency. If the frequency is lower than the first frequency and the high flow rate sensor is switched to the low flow rate sensor, the low flow rate sensor is determined to be abnormal. When the output value of the flow rate sensor is abnormally high, it is possible to easily check whether the low flow rate sensor is abnormal.

According to the fourteenth aspect of the present invention, the program recorded on the recording medium allows a computer to detect a high flow rate for measuring a large flow rate which detects a periodic pressure fluctuation of a fluid vibration generated in the fluid ejected from the nozzle flow path. A procedure for calculating the flow rate of the fluid based on a frequency based on a pressure change from a sensor, heating the heater with an input pulse, outputting a first pulse based on the temperature of the fluid before heating the heater, and outputting the first pulse based on the temperature of the fluid before heating the heater; Procedure for calculating a fluid flow rate based on a difference pulse output between a first pulse output and a second pulse output from a low flow rate sensor for small flow rate measurement that outputs a second pulse output based on temperature, a low flow rate sensor If the flow rate detected by the sensor reaches the switching upper limit value within the switching flow rate range, the flow rate is switched from the low flow rate sensor to the high flow rate sensor, Procedure for switching from high flow rate sensor to low flow rate sensor when switching lower limit value is reached, error between detected flow rate by low flow rate sensor and detected flow rate by high flow rate sensor is within a certain error range when detected flow rate is within switching flow rate range In order to determine whether the low flow sensor and the high flow sensor are abnormal, if the error is outside the certain error range, the procedure for determining that the low flow sensor and the high flow sensor are abnormal is performed. The presence or absence can be easily checked.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a flow meter according to a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of a fluidic element.

FIG. 3 is a configuration diagram of a gas meter.

FIG. 4 is a configuration diagram of a low flow sensor.

FIG. 5 is a diagram showing switching between a low flow sensor and a high flow sensor when the sensor is normal.

FIG. 6 is a flowchart illustrating a basic check process of the low flow sensor and the high flow sensor provided in the flow meter according to the first embodiment for the presence or absence of abnormality;

FIG. 7 is a flowchart illustrating a first half of a detailed check process of whether or not there is an abnormality in the low flow sensor and the high flow sensor provided in the flow meter according to the first embodiment;

FIG. 8 is a flowchart illustrating the latter half of a detailed check process of the low flow sensor and the high flow sensor provided in the flow meter according to the first embodiment for the presence or absence of an abnormality;

FIG. 9 is a configuration diagram of a flow meter according to a second embodiment of the present invention.

FIG. 10 is a diagram for explaining an output abnormality when the low flow rate sensor indicates a lower value than usual.

FIG. 11 is a flowchart illustrating a detailed check process of whether or not there is an abnormality in a low flow sensor provided in the flow meter according to the second embodiment;

FIG. 12 is a configuration diagram of a flow meter according to a third embodiment of the present invention.

FIG. 13 is a diagram for explaining an output abnormality when the low flow rate sensor indicates a value higher than usual.

FIG. 14 is a flowchart showing a detailed check process of the low flow sensor provided in the flow meter according to the third embodiment for the presence / absence of abnormality

FIG. 15 is a configuration diagram of a conventional fluidic flow meter.

FIG. 16 is a configuration diagram of a conventional rectangular flow path type flow meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fluidic element 13a Inflow port 13b Outflow port 15 High flow rate sensor 17 Low flow rate sensor 19 Pressure detection circuit 20 Waveform shaping circuit 21 Frequency detection circuit 22 Pulse generation unit 23 Pulse detection circuit 24 Flow rate calculation circuit 25 Sensor abnormality determination unit 26 LCD 27 Shutoff valve opening / closing section 28 Integrated flow rate holding section 29 Date / time information holding section 30 Sensor switching section 32 Semi-cylindrical member 35 Low flow rate sensor mounting hole 51 Program

Claims (14)

[Claims] 1. A high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path; and a heater for heating a heater by an input pulse and heating the heater before heating the heater. A low flow rate sensor for measuring a small flow rate, which outputs a first pulse output based on the temperature of the fluid and a second pulse output based on the temperature of the fluid after heating the heater, and based on a pressure fluctuation detected by the high flow rate sensor. A flow rate calculating unit that calculates a flow rate of the fluid based on a frequency, and calculates a flow rate of the fluid based on a difference pulse output between a first pulse output and a second pulse output detected by the low flow rate sensor; When the flow rate detected by the low flow rate sensor reaches the switching upper limit value within the switching flow rate range, the low flow rate sensor is switched to the high flow rate sensor, and the flow rate detected by the high flow rate sensor is switched off. A sensor switching means for switching from the high flow rate sensor to the low flow rate sensor when the switching lower limit value within the switching flow rate range is reached, and a detection flow rate by the low flow rate sensor when the detected flow rate is within the switching flow rate range. It is determined whether an error with the flow rate detected by the high flow sensor is within a certain error range, and when the error is outside the certain error range, the low flow sensor and the high flow sensor are determined to be abnormal. A flowmeter comprising: a sensor abnormality determining unit. 2. The sensor abnormality determination unit determines whether the number of times the error has fallen outside the predetermined error range has reached a predetermined number of times, and the number of times has reached the predetermined number of times. 2. The flowmeter according to claim 1, wherein in the case, the low flow sensor and the high flow sensor are determined to be abnormal. 3. A display device according to claim 1, further comprising a display unit for displaying that said low flow sensor and said high flow sensor are abnormal based on a sensor abnormality signal output from said sensor abnormality determination unit. Item 2. The flow meter according to Item 2. 4. The apparatus according to claim 1, further comprising a shutoff valve opening / closing means for closing a shutoff valve for shutting off the flow of the fluid based on a sensor abnormality signal output from the sensor abnormality determination means. Or the flow meter according to claim 1. 5. A high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path; and a heater for heating a heater by an input pulse and heating the heater before heating the heater. A low flow rate sensor for measuring a small flow rate, which outputs a first pulse output based on the temperature of the fluid and a second pulse output based on the temperature of the fluid after heating the heater, and based on a pressure fluctuation detected by the high flow rate sensor. A flow rate calculating unit that calculates a flow rate of the fluid based on a frequency, and calculates a flow rate of the fluid based on a difference pulse output between a first pulse output and a second pulse output detected by the low flow rate sensor; When the flow rate detected by the low flow rate sensor reaches the switching upper limit value within the switching flow rate range, the low flow rate sensor is switched to the high flow rate sensor, and the flow rate detected by the high flow rate sensor is switched off. A sensor switching means for switching from the high flow rate sensor to the low flow rate sensor when the switching lower limit value within the exchange flow rate range is reached, and when the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value, It is determined whether the detected flow rate of the fluid by the high flow rate sensor at that time has exceeded the switching upper limit value, and when the detected flow rate of the fluid by the high flow rate sensor has exceeded the switching upper limit value, the low flow rate sensor A flow rate meter, comprising: a sensor abnormality determination unit that determines that the pressure is abnormal. 6. The sensor abnormality determining means determines whether or not the number of times the detected flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit value has reached a predetermined number of times. 6. When the predetermined number of times has been reached, the low flow rate sensor is determined to be abnormal.
Flowmeter as described. 7. A high flow rate sensor for measuring a large flow rate which detects pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path, and a heater for heating a heater by an input pulse and heating the heater before heating the heater. A low flow rate sensor for measuring a small flow rate, which outputs a first pulse output based on the temperature of the fluid and a second pulse output based on the temperature of the fluid after heating the heater, and based on a pressure fluctuation detected by the high flow rate sensor. A flow rate calculating unit that calculates a flow rate of the fluid based on a frequency, and calculates a flow rate of the fluid based on a difference pulse output between a first pulse output and a second pulse output detected by the low flow rate sensor; If the differential pulse of the low flow sensor reaches a second differential pulse output that is greater than the first differential pulse output, the first
The low flow rate sensor that switches to the high flow rate sensor that outputs a second frequency greater than the frequency of the low flow rate sensor and that outputs the first differential pulse output when the frequency of the high flow rate sensor reaches the first frequency Sensor switching means for switching to the high flow sensor when the differential pulse of the low flow sensor becomes a third differential pulse larger than the second differential pulse and the low flow sensor is switched to the high flow sensor. It is determined whether or not the frequency is lower than the first frequency. If the frequency is lower than the first frequency and the high flow sensor is switched to the low flow sensor, the low flow sensor is regarded as abnormal. And a sensor abnormality determining means for determining. 8. The sensor abnormality determination unit determines whether the number of switching from the low flow sensor to the high flow sensor and the switching from the high flow sensor to the low flow sensor has reached a predetermined number of times. 8. The flowmeter according to claim 7, wherein it is determined whether or not the number of times has reached the specified number of times. 9. The apparatus according to claim 5, further comprising a display unit that displays that the low flow rate sensor is abnormal based on a sensor abnormality signal output from the sensor abnormality determination unit. The flowmeter according to claim 1. 10. The system according to claim 5, further comprising a shutoff valve opening / closing means for closing a shutoff valve for shutting off the flow of the fluid based on a sensor abnormality signal output from the sensor abnormality determination means. Flowmeter. 11. A step of calculating a flow rate of the fluid based on a frequency based on a pressure variation from a high flow rate sensor for measuring a large flow rate which detects a pressure variation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. And heating the heater with the input pulse and outputting a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. Calculating the flow rate of the fluid based on the difference pulse output between the first pulse output and the second pulse output from the low flow rate sensor; and setting the flow rate detected by the low flow rate sensor to a switching upper limit value within a switching flow rate range. When the flow rate reaches the low flow rate sensor, the high flow rate sensor is switched to the high flow rate sensor. When the flow rate detected by the high flow rate sensor reaches the switching lower limit value within the switching flow rate range, the high flow rate sensor is switched. Switching from the low flow sensor to the low flow sensor; and, if the detected flow is within the switching flow range, whether an error between the detected flow by the low flow sensor and the detected flow by the high flow sensor is within a certain error range. Determining whether the low flow rate sensor and the high flow rate sensor are abnormal when the error is outside the predetermined error range. 12. A step of calculating a flow rate of the fluid based on a frequency based on a pressure fluctuation from a high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. And heating the heater with the input pulse and outputting a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. Calculating the flow rate of the fluid based on the difference pulse output between the first pulse output and the second pulse output from the low flow rate sensor; and setting the flow rate detected by the low flow rate sensor to a switching upper limit value within a switching flow rate range. When the flow rate reaches the low flow rate sensor, the high flow rate sensor is switched to the high flow rate sensor. When the flow rate detected by the high flow rate sensor reaches the switching lower limit value within the switching flow rate range, the high flow rate sensor is switched. Switching from the low flow rate sensor to the low flow rate sensor, and when the detected flow rate of the fluid by the low flow rate sensor is less than the switching upper limit value, the detected flow rate of the fluid by the high flow rate sensor at that time exceeds the switching upper limit value. Determining whether the flow rate has exceeded the switching upper limit value, and determining whether the low flow rate sensor is abnormal when the detected flow rate of the fluid by the high flow rate sensor exceeds the switching upper limit value. Judgment method. 13. A step of calculating a flow rate of the fluid based on a frequency based on a pressure fluctuation from a high flow rate sensor for measuring a large flow rate which detects a pressure fluctuation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. And heating the heater with the input pulse and outputting a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater. Calculating the flow rate of the fluid based on the difference pulse output between the first pulse output and the second pulse output from the low flow sensor; and the difference pulse of the low flow sensor is larger than the first difference pulse output When the second differential pulse output is reached, the first
The low flow rate sensor that switches to the high flow rate sensor that outputs a second frequency greater than the frequency of the low flow rate sensor and that outputs the first differential pulse output when the frequency of the high flow rate sensor reaches the first frequency And the step of switching the low flow sensor into a third differential pulse larger than the second differential pulse becomes a third differential pulse, and when the low flow sensor is switched to the high flow sensor, the frequency of the high flow sensor becomes It is determined whether or not the frequency is lower than the first frequency. If the frequency is lower than the first frequency and the high flow rate sensor is switched to the low flow rate sensor, the low flow rate sensor is determined to be abnormal. A flow sensor abnormality determination method, comprising: 14. A computer which determines a flow rate of the fluid based on a frequency based on a pressure variation from a high flow rate sensor for measuring a large flow rate which detects a pressure variation of a periodic fluid vibration generated in a fluid ejected from a nozzle flow path. Calculation procedure, small flow rate measurement for heating a heater by an input pulse and outputting a first pulse output based on the temperature of the fluid before heating the heater and a second pulse output based on the temperature of the fluid after heating the heater For calculating the flow rate of the fluid based on the difference pulse output between the first pulse output and the second pulse output from the low flow rate sensor, and the flow rate detected by the low flow rate sensor being a switching upper limit value within a switching flow rate range Is switched from the low flow rate sensor to the high flow rate sensor when the flow rate reaches the lower limit value within the switching flow rate range when the flow rate detected by the high flow rate sensor reaches the switching lower limit value. The procedure for switching from the high flow rate sensor to the low flow rate sensor, the error between the flow rate detected by the low flow rate sensor and the flow rate detected by the high flow rate sensor when the detected flow rate is within the switching flow rate range is within a certain error range. A recording medium on which is recorded a program for determining whether or not there is an error, and executing a procedure for determining that the low flow rate sensor and the high flow rate sensor are abnormal when the error is outside the predetermined error range.