JP2006133238A - Flow rate measuring means - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform zero-point correction when fluid varies physically, thereby increasing the accuracy of flow rate measurement. <P>SOLUTION: This flow rate measuring means includes a flow rate computing means 5 for computing a flow rate from signals of a flow rate detection means 1, and a zero-point assay means 8 for detecting and correcting the zero value of the flow rate detection means 1. Since the zero-point assay means 8 is operated upon detection of the physical change of the fluid, the zero-point correction is performed automatically only during the physical change so as to eliminate unnecessary zero-point correction and to enable accurate detection of a minute flow rate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flow rate measuring device capable of measuring the flow rate of a fluid such as gas or liquid.

There are many known methods for measuring the flow rate and flow rate of fluids such as gas and liquid, but the development of flow rate and flow rate measurement devices that use highly reliable ultrasonic waves is particularly remarkable due to advances in electronics technology. . Ultrasonic flow velocity and flow rate measuring devices are used in many fields, such as fuel gas meters, industrial measuring instruments, medical blood flow meters, and measurement of the flow velocity in the ocean and the atmosphere. The flow velocity / flow rate measuring device using ultrasonic waves is not only used directly as ultrasonic waves but also indirectly used as a detection unit of a measuring device based on another measurement principle.
Many sensors such as a flow rate sensor, a resistance value sensor, a temperature sensor, and a voltage sensor are used for the flow velocity / flow rate measurement device as well as the quantity measurement device. And the sensor which transmits these electric signals may be influenced by an external condition and a sensitivity may change. For this reason, a flow measuring device used for a fuel gas meter or the like is required to measure even a slight flow rate change, for example, a slight change such as 3 liters / hour. In order to be able to grasp it, the measurement device must be capable of correcting the zero point of the measurement.

From the above viewpoint, for example, the technique disclosed in Patent Document 1 includes a unit that determines whether it is appropriate to perform zero point correction at predetermined time intervals and performs zero point correction based on the determination. This gas flow meter is highly regarded in the gas appliance industry as a useful technology.
JP-A-8-271307

  However, in the conventional configuration, it is determined whether or not the zero point correction needs to be performed at a predetermined time interval, and then the zero point correction is performed when necessary. Even when it is not necessary, it is necessary to determine whether or not the zero point correction is necessary at a predetermined time interval. Of course, the zero point correction is not performed unless the predetermined time interval is reached.

  Therefore, in view of the problems of the conventional example, the present invention includes a case where the measurement performance of the sensor is affected due to environmental changes, and when the zero point correction is necessary, the occurrence of the necessity is promptly addressed. An object is to automatically perform zero point correction.

  In order to solve the conventional problem, a flow rate measuring device according to the present invention includes a flow rate detection unit provided in a fluid flow path, a flow rate calculation unit that calculates a flow rate based on a signal of the flow rate detection unit, and the flow rate detection unit. Zero point detecting means for detecting the zero value of the flow rate and correcting the zero value by the flow rate calculating means, zero point correcting factor detecting means, and the zero point correcting means according to a change in the signal of the zero point correcting factor detecting means The zero point correction factor detecting means is a fluid physical property detecting means for detecting a physical change due to a change in the component of the fluid in the flow path.

  Therefore, when the fluid physics changes and the zero point correction becomes necessary, the zero point correction according to the change of the signal of the zero point correction factor detection means can be automatically performed. It is not necessary to frequently determine whether or not the point correction is necessary with a time interval. When the zero point correction is necessary, the zero point correction can be performed immediately in response to the necessity.

  According to the flow rate measuring device of the present invention, even if the fluid component changes and the density, specific heat, and sound velocity of the fluid change, the flow rate measurement accuracy can be maintained by correcting the zero point.

  The present invention is very useful when applied to a fuel gas meter such as city gas and propane gas. The reason is that it is necessary in Japan to accurately grasp the change in flow rate of fuel gas meters exceeding 3 liters per hour. In other words, when measuring flow rates in the case of thousands or tens of thousands of liters per hour, the accuracy of the measuring device is not required, but the sensor of the measuring device is not connected to the external environment. May cause a change in performance, and it may not be possible to accurately grasp the actual amount of fuel gas used. Therefore, the present invention is convenient because the flow rate can be accurately measured by the zero point correction over a wide range from a very small change in flow rate to tens of thousands of liters per hour. The present invention is effective when implemented in each field where it is necessary to measure an accurate flow rate in accordance with the above purpose.

  The present invention includes a flow rate detection means provided in a flow path, a flow rate calculation means for calculating a flow rate based on a signal from the flow rate detection means, a zero value of the flow rate detection means, and a zero value detected by the flow rate calculation means. A flow rate measuring device comprising: a zero point verification unit for correcting; a zero point correction factor detection unit; and a zero point control unit for operating the zero point verification unit according to a change in a signal of the zero point correction factor detection unit. Thus, the zero point correction can be automatically operated by the zero point correction means in accordance with the change in the signal of the zero point correction factor detection means, and the zero value can be corrected by the flow rate calculation means.

  The zero point correction factor detecting means is a temperature detecting means for measuring the temperature in the vicinity of the flow path, thereby automatically correcting the zero point due to the temperature of the flow path, so that even if there is a temperature change, it is accurate. The flow rate can be measured.

  In addition, the zero point correction factor detection means is a humidity detection means that measures the humidity in the vicinity of the flow path, automatically corrects the zero point due to the humidity in the flow path, and is accurate even if there is a humidity change. The flow rate can be measured.

  Further, the zero point correction factor detecting means automatically corrects the zero point caused by the fluctuation of the power supply voltage of the flow rate detecting means by using the voltage detecting means for measuring the power supply voltage of the flow rate detecting means. The flow rate can be accurately measured by driving with a power source.

  Further, the zero point correction factor detection means automatically corrects the zero point generated by the level change of the reception signal of the flow rate detection means by using the signal level detection means for measuring the signal level of the flow rate detection means, Since the generation of errors due to temperature change, humidity change, or secular change is comprehensively judged and corrected, high flow rate measurement accuracy can be maintained for a long time against environmental changes.

  In addition, the zero point correction factor detecting means automatically prevents the zero point from fluctuating even if an error occurs in the flow rate detecting means due to an impact caused by an earthquake or a collision by using a vibration sensing means. Because it can be reliable.

  In addition, the zero point correction factor detecting means is a communication means for transmitting / receiving data to / from the outside, so that the zero point is arbitrarily corrected by remote control from the outside. Since the points can be corrected, the accuracy of leak detection can be increased.

  Also, the zero point correction factor detection means is a fluid physical property detection means that detects physical changes caused by changes in the fluid components inside the flow path, so that the fluid components change and the fluid density, specific heat, and sound velocity change. Even if there is a change in fluid physical properties, the flow rate accuracy can be maintained by correcting the zero point.

  In addition, the zero point correction factor detection means is a pressure detection means for detecting the pressure of the fluid inside the flow path, thereby preventing the zero point from being corrected when the flow rate is not zero, thereby preventing an erroneous zero. It is possible to prevent a decrease in flow rate measurement accuracy due to point correction.

  Also, a flow rate detecting means provided in the flow path, a flow rate calculating means for calculating a flow rate based on a signal of the flow rate detecting means, and detecting a zero value of the flow rate detecting means and correcting the zero value by the flow rate calculating means It is determined that the flow rate value indicates an abnormality by including a zero point control unit that operates the zero point verification unit when the zero point verification unit and the value of the flow rate calculation unit indicate an abnormal value. Since the zero point is corrected only when an error occurs, not only can an immediate action be taken in the event of an abnormality, but unnecessary zero point correction need not be performed, and power consumption can be reduced.

  In addition, it is determined that an abnormal value is indicated when the value of the flow rate calculation means is continuously measured below a predetermined value, so that a change of zero value is determined when the flow rate value is not normally measured. In addition, since zero point correction is performed, fluid leakage can be detected immediately by accurate flow rate measurement even when a minute fluid leakage occurs, and safety is high.

  A first vibrator and a second vibrator disposed opposite to each other with a flow path interposed therebetween, and the signal propagation time between the first vibrator and the second vibrator is Operates a measurement circuit to measure, a flow rate calculation means for calculating a flow rate based on a signal of the measurement circuit, and a zero point verification means for detecting the zero value of the flow rate detection means and correcting the zero value by the flow rate calculation means A zero point control means for causing the zero point control means to actuate the zero point verification means in response to a change in the signal propagation time, thereby changing the sensitivity of the first vibrator and the second vibrator, Since the temperature change can be judged from the signal propagation time and the zero point can be corrected, a high flow rate measurement accuracy can be maintained by appropriately adjusting the zero point correction timing.

  In addition, it can be set as the flow volume measuring apparatus with higher measurement reliability by combining several specific requirements.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment.

(Embodiment 1)
FIG. 1A is a configuration block diagram of a flow rate measuring apparatus according to the first embodiment of the present invention, and FIG. 1B is a schematic diagram of a flow rate detecting means.

  In FIG. 1, the flow rate detection means 1 in the flow path A indicated by the white arrow is provided with a first ultrasonic transducer 3 and a second ultrasonic transducer 4 in a part of the fluid conduit 2 as shown in FIG. Are provided so as to be opposed to the direction of fluid flow. When an ultrasonic wave is generated in the flow direction from the first ultrasonic transducer 3 and this ultrasonic wave is detected by the second ultrasonic transducer 4, an ultrasonic wave is generated again from the first ultrasonic transducer 3 and this is repeated. And measure the time. Then, on the contrary, ultrasonic waves are generated against the fluid flow from the second ultrasonic transducer, and the same repetition time is measured. Then, the velocity of the fluid is calculated from the difference between the two times, and the flow rate is calculated by the flow rate calculation means 5 from the cross-sectional area of the fluid conduit 2 and the velocity of the fluid.

  On the other hand, the zero point control means 7 causes the zero point correction value of the flow rate calculation means 5 due to a change in the measured value by the temperature detection means 6 as a zero point correction factor detection means for measuring the temperature in the vicinity of the flow path at an appropriate place in the fluid conduit 2. Is activated by an electric signal to correct the zero point of the flow rate calculation means 5. Reference numeral 9 denotes a shut-off valve.

The flow of the above zero point correction is shown in FIG. 2, records the temperature T ₁ of the at Step 1 previous correction. Then with reference to measure the temperature of the flow path near As mentioned 1 at step 2, step 3 the difference between the temperatures T _1, which is recorded as the measured value T ₂ is whether greater than the predetermined value α Judge with. If the value of T ₁ -T ₂ is larger than the predetermined value α, the shut-off valve is closed in step 4, the flow rate is measured in step 5, a zero fluctuation value is calculated in step 6 from the measured value, and zero point correction is performed in step 7. Execute. Thereafter, in step 8, the shut-off valve is opened. Save this temperature _{T 2} as a new _{T 1.}

  Although the above shows the zero point correction based on the temperature, the zero point correction based on the humidity can be similarly performed.

(Embodiment 2)
FIG. 3 is a block diagram of a flow rate measuring apparatus according to another embodiment of the present invention. The same reference numerals are given to the same components as those of the first embodiment, and the detailed description of the first embodiment is as follows. Since it is the same as the case, it is omitted.

  The zero point correction factor detection means is the temperature detection means 6 or the humidity detection means in the first embodiment, but is the voltage detection means 6a in the second embodiment. This is a point different from 1. The flow rate measuring device includes a power source for opening and closing the shut-off valve 9, various means such as a flow rate detection means 1, a flow rate calculation means 5, a zero point verification means 8, a zero point control means 7, an ultrasonic transducer, and various sensors. In many cases, a battery power source 10 is used in addition to a commercial power source.

  In view of this, the voltage change of the battery power supply 10 due to battery consumption is grasped by the voltage detection means 6a which is the zero point correction factor detection means in the second embodiment, and the zero point verification means 8 works as a trigger according to the voltage fluctuation. The point control means 7 transmits an operation signal. Therefore, the zero point correction can be automatically achieved in the second embodiment in accordance with the change of the power supply voltage as well as the battery.

(Embodiment 3)
FIG. 4 is a block diagram showing the configuration of a flow rate measuring apparatus according to another embodiment of the present invention. The same components as those in the first embodiment described above have the same functions, and therefore detailed description will be given. Is omitted.

  The third embodiment is different from the first embodiment in that the level detection means 6b is provided as zero point correction factor detection means.

  In the third embodiment, since the level detecting means 6b is provided, the zero point generated by the level change of the reception signal of the flow rate detecting means 1 is automatically corrected to the temperature change, the humidity change, and the characteristic change due to aging. It is possible to comprehensively determine and correct the occurrence of the error due to it.

(Embodiment 4)
FIG. 5 is a block diagram showing the configuration of the flow rate measuring apparatus according to the fourth embodiment of the present invention. The same components as those in the first to third embodiments have the same operation, and therefore, the same reference numerals are given to the detailed components. Description is omitted.

  The fourth embodiment is different from the first to third embodiments in that a seismic sensing means 6c is provided as a zero point correction factor detecting means.

  In the fourth embodiment, since the seismic means 6c is provided, it is automatically detected that the zero point fluctuates even if an error occurs in the flow rate detecting means 1 due to an earthquake or an impact caused by something colliding. This can be prevented by correction.

(Embodiment 5)
FIG. 6 is a block diagram showing the configuration of the flow rate measuring apparatus according to the fifth embodiment of the present invention. The same components as those in the first to fourth embodiments have the same functions, and the details are given with the same reference numerals. The detailed explanation is omitted.

  The fifth embodiment is different from the first to fourth embodiments in that a communication means 6d for transmitting / receiving data to / from the outside is provided as a zero point correction factor detecting means.

  In the fifth embodiment, since the communication means 6d for transmitting / receiving data to / from the outside is provided, the zero point is arbitrarily set by the remote controller from the outside, unlike the first to fourth embodiments in response to changes in the natural environment. For example, when the fluid leakage is checked, the zero point can be corrected from the outside in advance. Note that a telephone line can be used for the communication means 6d.

(Embodiment 6)
FIG. 7 is a configuration block diagram of a flow rate measuring apparatus according to the sixth embodiment of the present invention, and the same components as those in the first to fifth embodiments described above have the same functions, and therefore the same reference numerals are given and details are shown. The detailed explanation is omitted.

  The sixth embodiment is different from the first to fifth embodiments in that the fluid physical property detecting means 6e is provided.

  Since the fluid physical property detection means 6e is provided in the sixth embodiment, the flow rate measurement accuracy can be maintained by correcting the zero point even if the fluid component changes and the density, specific heat, sound speed, etc. of the fluid change. .

(Embodiment 7)
FIG. 8 is a block diagram showing the configuration of the flow rate measuring apparatus according to the seventh embodiment of the present invention. The same components as those in the first to sixth embodiments have the same functions, and the details are given with the same reference numerals. The detailed explanation is omitted.

  In the seventh embodiment, since the pressure detecting means 6f for detecting the pressure of the fluid in the flow path is provided, the zero point is prevented from being corrected when the fluid is flowing. Accordingly, it is possible to prevent a decrease in flow rate measurement accuracy due to erroneous zero point correction.

(Embodiment 8)
FIG. 9 is a block diagram showing the configuration of the flow rate measuring apparatus according to the eighth embodiment of the present invention. The same components as those in the first to seventh embodiments are the same in function, and are given the same reference numerals for the details. The detailed explanation is omitted.

The eighth embodiment is different from the first to seventh embodiments in that a measurement circuit 6g is provided.

  As shown in FIG. 1B, the measurement circuit 6g according to the eighth embodiment includes first transducers that are opposed to each other with a flow channel A interposed therebetween (this may be an ultrasonic transducer). 2) and a second vibrator, and a measurement circuit that measures the propagation time of an electrical signal between the vibrators. Therefore, the zero point can be corrected appropriately.

  Although the embodiments of the present invention have been described in 1 to 8 above, it goes without saying that a plurality of these embodiments can be combined. Further, the zero point is corrected only when it is determined that the value of the flow rate calculation means indicates an abnormal value, so that unnecessary zero point correction is not performed, and power consumption can be reduced. A person skilled in the art can easily realize an embodiment corresponding to the case of slight fluid leakage by determining that the change is zero value when the flow rate is less than or equal to a predetermined flow rate value and performing zero correction.

  As described above, according to the embodiment of the present invention, when the zero point correction is necessary, the zero point correction is automatically performed, and even a minute flow rate change can be accurately measured.

  That is, zero point correction can be performed according to a change in the signal of the zero point correction factor detecting means.

  Further, the zero point due to the temperature of the flow rate detecting means can be automatically corrected.

  In addition, the zero point due to humidity can be automatically corrected.

  Further, the zero point due to the fluctuation of the power supply voltage can be automatically corrected.

  It also automatically corrects the zero point generated by the level change of the received signal of the flow rate detection means, and comprehensively judges and corrects the occurrence of error due to superposition change such as temperature change, humidity change or aging change. be able to.

  Further, it is possible to automatically prevent the zero point from fluctuating even if an error occurs in the flow rate detection means due to an earthquake or a collision impact.

  Further, the zero point can be arbitrarily corrected from the outside by a remote controller. For example, when the fluid leakage is checked, the zero point can be corrected in advance from the outside to improve the accuracy of leakage detection.

  Further, even if the fluid component changes and the density, specific heat, and sound speed of the fluid change, the flow rate measurement accuracy can be maintained by correcting the zero point.

  Further, it is possible to prevent the zero point from being corrected when the fluid flow rate is not zero, thereby preventing the measurement accuracy from being lowered due to an erroneous zero point correction.

  Further, since the zero point is corrected only when it is determined that the fluid flow rate value indicates an abnormality, not only can an immediate action be taken in the event of an abnormality, but there is no need to perform unnecessary zero point correction, thereby reducing power consumption.

  In addition, if the flow rate is not normally measured or less, it is judged as a change in the zero value, and zero point correction is performed. Therefore, even when a small amount of fluid leaks, the leak can be detected immediately by accurate flow measurement. Is expensive.

  In addition, since the zero point can be corrected by judging the sensitivity change and temperature change of the vibrator based on the signal propagation time, it is possible to appropriately determine the zero point correction time, and thus high flow measurement accuracy can be maintained. .

(A) Main part configuration block diagram of flow rate measuring device in Embodiment 1 of the present invention (b) Schematic diagram of the flow rate detecting means Flow chart of zero point correction of flow rate measuring apparatus in embodiment 1 The principal part block diagram of the flow volume measuring apparatus in Example 2 of this invention Block diagram of main components of a flow rate measuring device according to Embodiment 3 of the present invention Block diagram of main components of a flow rate measuring device according to Embodiment 4 of the present invention Block diagram of main components of a flow rate measuring device in Embodiment 5 of the present invention Block diagram of main components of a flow rate measuring device according to Embodiment 6 of the present invention Block diagram of main components of a flow rate measuring device according to Embodiment 7 of the present invention Block diagram of main components of a flow rate measuring device in Embodiment 8 of the present invention

Explanation of symbols

A flow path 1 flow rate detection means 2 fluid conduit 3 first ultrasonic transducer 4 second ultrasonic transducer 5 flow rate calculation means 6e fluid physical property detection means 7 zero point control means 8 zero point verification means

Claims (2)

A flow rate detecting means provided in a fluid flow path, a flow rate calculating means for calculating a flow rate based on a signal from the flow rate detecting means, and a zero for detecting a zero value of the flow rate detecting means and correcting the zero value by the flow rate calculating means A zero point correction factor detection unit; a zero point correction factor detection unit; and a zero point control unit that operates the zero point verification unit in response to a change in a signal of the zero point correction factor detection unit. Is a flow rate measuring device which is a fluid physical property detection means for detecting a physical change due to a change in the component of the fluid in the flow path. A measurement circuit that includes a first vibrator and a second vibrator disposed to face each other with a flow path interposed therebetween, and measures a signal propagation time between the first vibrator and the second vibrator. And zero point control for operating the zero point detecting means for detecting the zero value of the flow rate detecting means and correcting the zero value by the flow rate calculating means. And a zero point control means that operates the zero point verification means in response to a change in the signal propagation time.

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