JPH0332972Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a flow rate pulse transmitting device used in a flowmeter such as a sonic nozzle that does not have a flow rate transmitting device.

Generally, when measuring a flow rate using a flowmeter such as a sonic nozzle that cannot directly obtain a digital flow signal, it is generally difficult to obtain an integrated value of the flow rate.

The purpose of this invention is to digitally display the flow rate measurement on the above-mentioned flowmeter, perform successive correction calculations, and output a unitized pulse train as a flow rate pulse signal based on the calculation results. Another object of the present invention is to provide a flow rate pulse transmitting device that can easily obtain an integrated value of flow rate in flow measurement using the flow meter.

Another purpose of this invention is that the pulse output corrected for the analog output can be extracted as a unitized flow rate pulse, which can be used not only for numerous control operations but also for testing and verification of other flowmeters. It is an object of the present invention to provide a flow rate pulse transmitting device that can easily perform correction verification in operation without involving a complicated calculation mechanism.

An embodiment of this invention will be described below with reference to the drawings.

The illustrated embodiment shows an example in which a sonic nozzle is used as an analog flowmeter, and this sonic nozzle is used as a reference flowmeter in a detection system in which two or more are arranged.

1 is a front chamber 1a on the fluid inflow side and a rear chamber 1 on the fluid outflow side by a partition wall to which a large number of sonic nozzles 2 are attached.
3 is a valve opening/closing mechanism that opens and closes the nozzles of these sonic nozzles 2, and the output signal of this valve opening/closing mechanism is transmitted through a wiring 4 to an input port 5 of a pulse transmitter a. It's becoming like that. That is, the output signal is capable of transmitting to the input port 5 which sonic nozzle 2 is operating or not.

Reference numeral 6 denotes upstream piping in which test flowmeters m ₁ , m _{2 .} . . are connected in series and connected to the meter unit 1. 7 is the downstream piping connected to the meter unit 1.
It is connected to the downstream side of Reference numeral 8 denotes an airflow generation source for generating the necessary airflow, and in the illustration, it is provided in the form of a vacuum pump in the downstream piping 7, but it may also be provided in the form of a pressurizing compressor in the upstream piping 6.
In short, it is necessary to obtain a sonic flow in the sonic nozzle 2. Although it is desirable to use dry air to calibrate the nozzle, it is difficult in practice and ordinary air is used instead.

By the way, since normal air contains moisture (humidity), it is necessary to correct the humidity, and the density of the air is corrected using the following equation.

The saturated vapor pressure of water at t _a (℃) is E _w
(mmHg), the atmospheric pressure is p _a (mmHg), the temperature at the nozzle inlet is t _a (℃), and the relative humidity at the nozzle inlet is H _a
(%), the density of air ρ _a (g/l) is given by ρ _a =1.2932×273.15/273.15+t _a ×(p _a −0.378E _w ·H _a )/760.

Reference numeral 9 indicates a temperature detection section that detects temperature changes, and 10 indicates a pressure detection section that detects pressure changes, both of which detect the temperature or pressure of the meter unit 1 so that it can be extracted as a desired analog quantity by the conversion sections 11 and 12. It is set as. Reference numeral 13 denotes a humidity detection section that detects the humidity of the air flowing through the pipe 6, and is designed to be able to extract it as a desired analog quantity. 14
is an A-D converter of the pulse transmitter a, which is capable of converting analog signals from the temperature detecting section 9, pressure detecting section 10, and humidity detecting section 13 into digital signals. Reference numeral 15 denotes an arithmetic control unit which detects which sonic nozzle is operating based on the output signal of the valve opening/closing mechanism 3 inputted through the input port 5, and selects one of the pre-stored meter constants of the sonic nozzle. It has an arithmetic control function that searches for the corresponding value, corrects the detected temperature, pressure, and humidity, and calculates the true value flow rate, and also outputs a flow rate pulse proportional to the true value flow rate to the pulse controller. 18 has a function of calculating the frequency division ratio necessary for output. Setting of the meter constant is performed by a setting device 16 connected to the calculation control section 15. In this way, the true flow rate of the selected sonic nozzle 2 during operation by the arithmetic control unit 15 is determined.

17 is a master clock, which is capable of transmitting a predetermined frequency _M , and is connected to the arithmetic control section 15.
It is connected via a gate 19 to a pulse controller 18 which can generate a flow rate pulse proportional to the flow rate using a frequency division ratio given by .

The frequency division ratio N is given by Fout=K・Q(HZ) where the flow rate pulse is Fout, the true flow rate is Q, and the proportionality constant is K. On the other hand, Fout= _M /N(HZ) Therefore, N= _M /K・Q...(1) This frequency division ratio N is preset in the pulse controller 18, and the pulse controller 18 divides the frequency of the master clock 17 and outputs a pulse train proportional to the flow rate. It is. 20 is a DA converter for outputting the digital signal from the calculation control section 15 as an analog quantity. Note that when the flow rate of the gate 19 is zero,
In order to make the flow rate pulse Fout zero, the setting device 1
When the flow rate falls below the lower limit set in step 6, the master clock 17 is closed so that no pulse output is generated.

The effect of this invention will be explained regarding the above structure.

First, the necessary number of sonic nozzles 2 in the meter unit 1 are selected to flow gas. This state becomes an output signal from the valve opening/closing machine 3 and is transmitted to the arithmetic control section 15 of the pulse transmitter a via the input port 5.

On the other hand, the analog signals for correction from the temperature detection section 9, pressure detection section 10, and humidity detector 13 that detects the humidity of the gas provided in the meter unit 1 are converted into digital signals by the A-D converter 14. The information is transmitted to the arithmetic control unit 15, and corrections for temperature, pressure, humidity, Reynolds number, linearity, etc. are calculated based on meter constants, correction formulas, etc. set in advance by the setting device 16, and the true flow rate is then digitally calculated. Obtained as a signal.

This digital signal corresponding to the true flow rate is processed by the pulse controller 18 at a constant frequency _M from the master clock 17 to generate a flow rate pulse proportional to the flow rate under a constant calculated frequency division ratio N.
Output as Fout.

Therefore, the flow pulse relative to this flow rate
Since Fout corresponds to a digital signal obtained by dividing the true flow rate of the sonic nozzle 2 by the frequency division ratio, it can be compared with the flow rate of various test flowmeters m ₁ , m ₂ , etc. very easily. .

If the flow rate flowing into the sonic nozzle 2 is lower than the set flow rate due to some factor, a signal is sent from the arithmetic control unit 15 to close the gate 19 and the signal from the master clock _M is sent to the pulse controller 18.
This eliminates erroneous flow rate measurement operations.

The invention of the present application is divided into a front chamber on the fluid inflow side and a rear chamber on the fluid outflow side by a partition wall to which a plurality of sonic nozzles are attached, and a valve for individually opening and closing the outlet of the plurality of sonic nozzles. In a meter unit provided with an opening/closing mechanism, each output signal of the valve opening/closing mechanism is inputted to a calculation control unit as an operating nozzle signal of the plurality of sonic nozzles, and the settings are stored in advance in the calculation control unit using a setting device. Search for the corresponding value among the meter constants of the sonic nozzles, correct the pressure, temperature, and humidity detected for each of the plurality of sonic nozzles to calculate the true flow rate, and convert the output signal after the calculation into a digital signal. input to an analog converter and output an analog signal of the true value flow rate; input the output signal after the calculation to a pulse controller; in the pulse controller, the frequency is divided by a master clock pulse input via a gate; A master clock pulse is output as a frequency corresponding to the true value flow rate, and when the value of the true value flow rate becomes equal to or less than the lower limit flow rate value set by the setting device, the gate is closed and the master clock pulse is output. The pulse controller is configured to prevent pulses from being output from the pulse controller, resulting in the following effects.

(1) It is possible to easily determine the true flow rate of a flowmeter, such as a sonic nozzle, where the flow rate value cannot be directly obtained.

(2) Accurate flow rate tests can be performed by cutting below the lower limit flow rate.

[Brief explanation of the drawing]

The figure is an overall block diagram illustrating the flow pulse transmitting device according to the present invention when using a sonic nozzle. 1...Meter unit equipped with a large number of sonic nozzles 2, 1a...front chamber, 1b...rear chamber, 1c...
Partition wall, 3...Valve opening/closing mechanism, 5...Input port, a...Pulse transmitter, _m1 , _m2 ...Test flow meter, 9...Temperature detection section, 10...Pressure detection section, 1
3... Humidity detection section, 15... Arithmetic control section, 16...
...Setter, 17...Master clock, 18...
Pulse controller, 19...gate.

Claims (1)

[Scope of utility model registration request] The meter unit is divided into a front chamber on the fluid inflow side and a rear chamber on the fluid outflow side by a partition wall to which a plurality of sonic nozzles are attached, and a valve for opening and closing the outlet of the plurality of sonic nozzles individually. A mechanism has been established,
A humidity detection section is provided in a pipe in which a plurality of flowmeters to be tested are connected in series on the upstream side of the meter unit, a pressure detection section and a temperature detection section are provided in the front chamber, and individual output signals of the valve opening/closing mechanism are provided. A corresponding value is inputted to the arithmetic control unit as a working nozzle signal in the plurality of sonic nozzles, and a corresponding value is searched from among the meter constants of the sonic nozzles that are set and stored in advance by a setting device in the arithmetic control unit. The detected pressure, temperature, and humidity are corrected for each galvanometric flowmeter to calculate the true flow rate, and the output after the calculation is input to a digital-to-analog converter to produce an analog output of the true flow rate. The output signal after the calculation is input to a pulse controller, and the pulse controller divides the frequency of the master clock pulse input through the gate, and outputs the master clock pulse as a frequency corresponding to the true value flow rate. , and characterized in that when the value of the true value flow rate falls below the lower limit flow rate value set by the setting device, the gate is closed to prevent pulses from the master clock from being output from the pulse controller. Flow rate pulse transmitter for sonic nozzle.