JP2000121404A - Flow rate measuring unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure flow rate precision by adjusting it by units. SOLUTION: The propagating time of ultrasonic waves in a gas flow passage 3 is measured by a control measuring circuit 1, and data-outputted to a data bus line 4. A flow rate is calculated by a data processing personal computer 5 based on the transmitted data, and a correction value calculated from a difference between the calculated flow rate and the real flow rate is written through the data bus line 4 in a non-volatile memory 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measurement unit used in a gas safety device provided in a gas passage and shutting off the gas passage when an abnormality occurs.

[0002]

2. Description of the Related Art In recent years, for the purpose of safe use of city gas and LP gas, the amount of fuel gas (hereinafter, referred to as gas) has been measured. A security device that shuts off a gas passage when it is detected that the device has been used for a time greatly separated from the usage state of the device has become widespread.

[0003] This type of security device takes a detection signal of a gas flow rate into a security control circuit, processes the signal by an internal microcomputer, monitors the gas flow rate, outputs a cutoff signal if there is an abnormality, and closes a shutoff valve. I do.

In order to detect the gas flow rate, a membrane type for measuring the passing volume by the number of times the gas ventilates a measuring chamber having a predetermined volume, and a gas flow rate of a gas flow path having a predetermined cross-sectional area are calculated to measure the flow rate. There is an ultrasonic type to do.

[0005] The principle of ultrasonic flow detection is that the propagation time of an ultrasonic wave between two points in a gas flow path is a function including the gas flow velocity. If known, this is applied to the fact that the flow rate can be determined from the cross-sectional area.

[0006]

(1) The ultrasonic gas safety device has been completed because errors such as the arrangement distance of the built-in ultrasonic sensor, the shape of the gas flow path, and the degree of finishing affect the flow velocity calculation. Perform an actual flow test for each gas safety device,
If it is necessary to compare the actual flow rate with the calculation result and correct it, and if the flow rate and the flow velocity are not exactly proportional, it is necessary to correct the proportional coefficient for each flow velocity category. There is a problem that an input is required for the flow rate calculation unit of the internal security control circuit for each device.

(2) When performing signal processing on the output of an ultrasonic sensor in an ultrasonic gas safety device, a difference may occur in the signal waveform for each sensor due to a difference in the transient response characteristics of the ultrasonic sensor. There is a problem that it is necessary to adjust the operating point of the internal control and measurement circuit for each of the assembled gas safety devices.

[0008] (3) The direct output of the ultrasonic sensor is very small and requires amplification, and an amplifier is built in the control measurement circuit.
In order to avoid the influence of noise etc., it is necessary to install it near the gas flow path main body where the ultrasonic sensor is mounted, while the security control circuit incorporating the flow rate calculation unit displays the flow rate and various security information, Since processing of input / output signals of the operation unit is also performed, there is a problem that an arrangement place giving priority to functions is required, and it is difficult to arrange a circuit board satisfying both requirements.

[0009]

(1) In order to solve the above-mentioned problems, the present invention measures the actual flow rate of each unit composed of a gas flow path, an ultrasonic sensor, a control measurement circuit, and a nonvolatile memory for each unit. In addition, data is transmitted and received by a separately provided data processing personal computer to calculate the flow rate, and the unique correction data for each unit component is written to the non-volatile memory based on comparison with the actual flow rate.

According to the present invention, since the unique correction data can be output through the data bus line, it is possible to provide an equivalently standardized flow rate measurement unit.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) The present invention performs a gas flow path, a transmission / reception ultrasonic sensor installed in the gas flow path, a transmission / reception control of the ultrasonic sensor, and a measurement of an ultrasonic propagation time. A control measurement circuit that inputs and outputs control data and measurement data through a data bus line, and a non-volatile memory that stores a part of the control content of the control measurement circuit, perform actual flow measurement for each combination unit component of each component, Data transmission / reception is executed by a separately provided data processing personal computer to calculate the flow rate, and the unique correction data for each unit component is written to the non-volatile memory based on comparison with the actual flow rate and held.

As a result of the flow rate calculation by the data processing personal computer, if there is a difference from the actual flow rate, the calculation count such as the distance between the sensors and the cross-sectional area of the flow path is corrected, and the proportional relationship between the flow velocity and the flow rate is unified in a plurality of flow rate divisions. If not, a correction count is determined for each flow rate section, and these unique correction data are written to the nonvolatile memory.

After the assembly of the gas safety device, the flow rate calculation unit of the security control circuit performs the flow rate calculation. The program is programmed to automatically read the unique correction data in the non-volatile memory and perform the calculation processing. Eliminates the need for readjustment.

(2) An adjusting unit that enables variation in the characteristics of the ultrasonic sensor by correcting the operating point of the control and measurement circuit,
It is provided on the same circuit board as the nonvolatile memory.

[0015] Since an electric adjustment unit, such as adjustment of an operating point, which is difficult to cope with only with data such as correction count, is provided on the same substrate as the nonvolatile memory, this part is adjusted simultaneously when measuring the actual flow rate. With this arrangement, it is possible to provide a flow measurement unit that does not need to be adjusted after being incorporated in the gas safety device.

(3) Further, a circuit board is divided at a data bus line portion, a portion including a control measurement circuit, an adjusting section, and a non-volatile memory is installed in a gas flow path main body, and a security control circuit incorporating a flow rate calculating section is provided. The part that includes it is installed close to the operation unit and the display unit, and is completed by connecting both substrates with a data bus line.

Since the two circuit boards are connected by a digital data bus line which is hardly affected by noise or the like, the influence of the distance between the two boards is small, and the performance and
An optimal arrangement can be taken in terms of functions.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing Embodiment 1 of a flow rate measuring unit of the present invention. In the figure, an electrical signal output from an oscillation output terminal OUT of the control measurement circuit 1 is acoustically converted by an oscillation ultrasonic sensor 21, and an ultrasonic wave is emitted in the gas flow path 3. The receiving ultrasonic sensor 22 installed at a distance L returns the captured ultrasonic wave to an electric signal again, and returns it to the receiving input terminal IN of the control measurement circuit 1.

The control measurement circuit 1 measures the time from the oscillation output to the reception input, that is, the propagation time T of the ultrasonic wave at the distance L in the gas flow path 3, and the data processing personal computer 5 transmits the measurement control circuit through the data bus line 4. The flow rate is calculated based on the data of the propagation time T sent from No. 1.

The ultrasonic wave propagation time T between two points in the gas flow path
Is a function including the gas flow velocity. If the propagation time T is measured, the gas flow velocity can be calculated backward. If the flow velocity is known, the flow rate is calculated based on the principle that the flow rate can be determined from the passage cross-sectional area S. If the proportionality between the flow velocity and the flow rate is not uniquely established in a plurality of flow rate sections, the correction count is determined for each flow rate section, and the intrinsic correction of these is corrected. Data is written to the nonvolatile memory 6 through the data bus line 4.

The configuration after the gas security device assembly is completed is shown in FIG. 3, which will be described later. The flow rate calculation unit 71 of the security control circuit 7 performs the flow rate calculation. Program, thereby eliminating the need for readjustment after assembly is complete.

FIGS. 2A and 2B are a circuit and a characteristic diagram for explaining an example of the propagation time measurement according to the present invention. In the figure, the ultrasonic wave used for measurement is a burst wave, and the propagation time can be easily measured if the rising edge of the signal is captured as shown in (T). However, due to the transient response of the ultrasonic sensor, the received signal waveform is S-. Since the amplitude gradually increases like OUT, the first few waves have insufficient amplitude and are greatly affected by noise and the like, and are not suitable for measurement.

Therefore, the amplitude of the received signal waveform is monitored by the comparator 100, and the propagation time T is measured by capturing the zero-cross point Z after exceeding the monitoring level E.

Since the transient response of the flow sensor varies, the monitoring level E of the comparator 100 is adjusted by the volume VR provided in the adjusting unit 8 for each of the incorporated flow sensors. At the time of actual flow rate measurement, this part is adjusted at the same time and assembled into the gas safety device to make a flow rate measurement unit that does not require adjustment.

FIG. 3 is a block diagram showing the relationship between the flow measurement unit of the present invention and the gas safety device. In the figure, a circuit board is divided at a data bus line 4, and a circuit board 200 including a control measurement circuit 1, an adjustment unit 8, and a non-volatile memory 6 is installed in a main body of the gas passage 3, and a security control circuit 7 and an operation unit 9 are installed. ,
Circuit board 3 including display unit 10 and external device connection terminal unit 11
00 is installed at a position required for function and design.

[0027]

(1) As described above, according to the present invention, the actual flow rate is measured for each unit, the adjustment portion is adjusted, and
Since data transmission and reception are performed by a separately provided data processing personal computer to calculate the flow rate and write the unique correction data to the non-volatile memory, it is equal to the adjustment completed by the unit alone, and this is incorporated into the gas safety device, If it is not necessary to re-adjust it when it is completed, or if the correction data or the adjustment range exceeds the allowable range and the specified performance cannot be ensured due to a defective component, the damage will be caused to the unit (flow sensor part). Since it is limited, the loss is low, and there is an effect that it is possible to easily perform rework such as replacement of parts.

(2) When measuring the actual flow rate, a dedicated data processing personal computer is used to calculate the flow rate, calculate the unique correction data, and write the data to the nonvolatile memory. It is easy to exchange the data and the effect is that a series of operations can be automated.

(3) When arranging the substrate in a divided manner in order to maximize the performance and function, the number of wirings is smaller than that of the display, operation, and external device connection terminals having many wirings. This has the effect of reducing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a flow rate measurement unit according to a first embodiment of the present invention.

FIG. 2A is a circuit diagram for explaining propagation time measurement of the same unit. FIG. 2B is a characteristic diagram of the circuit diagram.

FIG. 3 is a configuration diagram showing the relationship between the flow measurement unit and the gas safety device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control measurement circuit 3 Gas flow path 4 Data bus line 5 Data processing personal computer 6 Non-volatile memory 7 Security control circuit 8 Adjustment unit 9 Operation unit 10 Display unit 11 External device connection terminal unit 21, 22 Ultrasonic sensor

Claims (4)

[Claims] 1. A gas flow path, a transmission / reception ultrasonic sensor installed in the gas flow path, and control of transmission / reception of the ultrasonic sensor and measurement of the propagation time of the ultrasonic wave, and measurement data is sent to a data bus line. A control measurement circuit for input and output, and a non-volatile memory for storing a part of the control content of the control measurement circuit, the actual flow rate is measured for each combination unit component of the components, and a separately provided data processing personal computer Data transmission / reception is performed to calculate the flow rate, and the unique correction data for each unit component is written to the nonvolatile memory from the comparison with the actual flow rate, and the flow rate measurement unit of the gas safety device is configured to hold the unique correction data. . 2. The flow rate measurement unit according to claim 1, wherein an adjustment unit that enables variation in the characteristics of the ultrasonic sensor by correcting the operating point of the control measurement circuit is provided on the same circuit board as the nonvolatile memory. 3. A circuit board is divided at a data bus line part, a part including a control measurement circuit, an adjustment unit, and a nonvolatile memory is installed in a gas flow path main body, and a part including a security control circuit having a built-in flow rate calculation unit is included. The flow measurement unit according to claim 1, wherein the flow measurement unit is arranged near the operation unit and the display unit, and the two circuit boards are connected by a bus line. 4. The flow rate measurement unit according to claim 1, wherein the operation section, the display section, and the external device connection terminal section are arranged on the same board as the security control circuit.