JPS5853292B2 - Gas flow measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow rate measuring device that can easily measure the flow rate of gas in a state where the pressure fluctuates.

Generally, flow rate measurement is performed by keeping the pressure of the fluid to be measured constant.

However, it is not easy to maintain a constant pressure state, especially when the flow rate is large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus capable of measuring a flow rate without maintaining a constant pressure state and verifying whether the measured value satisfies a standard value.

Its feature is that the flow rate is measured at the moment the pressure reaches a predetermined value during the process of increasing the vacuum level, and it is determined whether the flow rate is within a predetermined range.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to the drawings.

FIG. 1 shows a fluid circuit for flow rate measurement, and FIG. 2 shows an electrical judgment display circuit, both of which constitute a flow rate measuring device.

In FIG. 1, 1 is a laminar flow meter whose input end is open to the atmosphere, and a pair of pressures proportional to the flow rate appear.

A pressure transducer 2 that converts these two pairs of pressures into electrical signals is connected to the laminar flow meter 1, and the output end is connected to valves 3a, 4a, 5a that open and close the fluid flow path, and one end of a pressure gauge 6. Connected.

The other end of the valve 3a is connected to the object to be measured 7 whose flow rate is to be measured, and the other ends of the valves 4a and 5a are connected to fixed orifices 8 and 9 for setting the upper and lower limits of the flow rate, respectively. The output ends are all valves 3b, 4b, 5
It is connected to the pressure regulating tank 10 via b.

The other end of the pressure gauge 6 is connected to a common connection point between the pressure regulating tank 10 and the valves 3b, 4b, and 5b, and outputs an electrical signal proportional to the pressure difference between the two ends to its output end P1.

The pressure at the output end of the laminar flow meter 2 is approximately equal to atmospheric pressure, and therefore, as the degree of vacuum in the pressure regulating tank 10 increases, the output voltage also increases.

The pressure regulating tank 10 absorbs and stabilizes minute fluctuations in the flow rate, and the other end is connected to a vacuum device 12 via an regulating valve 11 such as a needle valve, and is connected to a vacuum device 12 through an regulating valve 13 and a regulating valve 14. They are each opened to the atmosphere through.

Next, the judgment display circuit of this embodiment will be explained with reference to FIG.

Pl is an output terminal of the pressure gauge 6, and is connected to one input terminal of the pressure comparator 20 via a resistor R1.

A predetermined voltage determined by resistor R2 and variable resistor R3 is applied to the other 0 input terminal of the pressure comparator, and the pressure gauge 6
If the input given from the voltage is lower than the predetermined voltage, the pressure comparator 20 outputs the H level, and if it is higher, the pressure comparator 20 outputs the L level.

Next, Pl is the output terminal of the pressure transducer 2, and the resistance R
4, connected to the upper limit comparator 21 and the lower limit comparator 22 via R5.

The other input terminals of the upper and lower limit comparators 21 and 22 are connected to a resistor R6, a variable resistor R7 or a resistor R8, and a variable resistor R.
A predetermined voltage determined by 9 is applied, and if the input from the pressure transducer 2 is lower than the respective predetermined voltage, the upper and lower limit comparators 21 and 22 output an H level, and if higher, an L level is output.

A NAND circuit 24 is connected to the output terminal of the pressure comparator 20 via an inverter 23.

The output terminal of the upper limit comparator 21 is connected to the input terminal of the NAND circuit 25, and the output terminal of the lower limit comparator 22 is connected to the input terminal of the NAND circuit 25 via the inverter 26.

The output of the NAND circuit 25 is given to the NAND circuit 24 via an inverter 27.

In addition, the positive terminal of power supply B is connected to NAND circuit 2 via resistor R10.
Timer 2 is connected to the input terminal of 4 and is a normally closed contact.
8 is grounded, and further connected to one input terminal of a NAND circuit 29.

The output of the NAND circuit 24 is given to a clock input terminal of a flip-flop circuit 31 via an inverter 30, and one output is given to a drive circuit 33 via an inverter 32.
Furthermore, an indicator lamp 34 is provided.

Also, the output of the inverter 32 is connected to the NAND circuit 29 and the drive circuit 3.
5 to the indicator lamp 36.

Furthermore, light emitting diodes 100 and 101 are connected to the output sides of the inverter 23 and the NAND circuit 250, respectively, and emit light when each outputs an L level.

The pressure comparator 20 determines the pressure at the time of measuring the flow rate, and after closing the valve 14, the regulating valve 1
1.13, the pressure difference is set to a specified value, and the value of the resistor R3 is adjusted while watching the flashing of the light emitting diode 100 so that the pressure comparator 20 operates if there is a pressure exceeding that pressure.

Further, the upper limit comparator 21 is used to check whether the flow rate is below a predetermined upper limit value, and opens the valves 4a and 4b to connect the laminar flow meter 1, the fixed orifice 8 for setting the upper limit, the pressure regulating tank 10, and the regulating valve 11. The vacuum device 12 is operated to set a predetermined pressure, and the value of the variable resistor R7 is adjusted by blinking the light emitting diode 101 so that the upper limit comparator 21 operates at a value exceeding the pressure at that time. .

The lower limit comparator 22 is used to check whether the flow rate is equal to or higher than a predetermined lower limit value, and similarly changes the value of the variable resistor R9 to the light emitting diode 10 with the valves 5a and sb open.
Adjust by blinking 1.

If the flow rate is between the upper limit value and the lower limit value 0 in the above operation, the H level is applied to both inputs of the NAND circuit 25, and the inverter 21 outputs the H level.

Next, the drive circuits 33 and 35 operate with negative logic, and if the flow rate is within a predetermined range, the indicator lamp 34 lights up, and if not, the indicator lamp 36 lights up to indicate the respective status.

The flip-flop circuit 31 maintains its display state, and its reset terminal is connected to a ground point via a start switch SSW.

Next, the overall operation of this embodiment will be explained.

First, the object 7 to be measured is set in the fluid system, the valves 3a and 3b at both ends thereof are opened, the valve 14 is closed, and the vacuum device 12 is operated.

At the same time, turn on the start switch SSW.

By operating the fluid system, the pressure at both ends of the object to be measured 7 gradually increases toward the pressure set by the regulating valves 11 and 13.

(Therefore, the degree of vacuum also increases.

) When the start switch SSW of the determination circuit is turned on, the flip-flop circuit 31 becomes operational, and one output terminal Q becomes L level.

When the start switch ssvm shown in FIG. Outputs L level.

On the other hand, at this time, the flow rate is lower than the value set by the lower limit setting orifice 9, and the NAND circuit 25 outputs an H level, and therefore the inverter 27 outputs an L level.

Furthermore, the timer switch 28 is also closed.

Therefore, the L level is applied to the input of each of the NAND circuits 24.

Next, after a predetermined period of time has elapsed, the timer switch 28 is opened, and the degree of vacuum reaches a predetermined value, and the pressure comparator 20
When inverted, if the flow rate is within a predetermined range, an H level is input to the NAND circuit 24, and therefore an L level is output, and the flip-flop circuit 31 is inverted,
The drive circuit 33 turns on the indicator lamp 34 to indicate that the flow rate is within a predetermined range.

If the flow rate is not within the predetermined range, the drive circuit 35 operates and lights up the indicator lamp 36 to indicate this fact.

In this way, the flow measuring device according to the present invention can measure the flow rate when it exceeds a predetermined pressure without keeping the pressure constant, and can determine whether the flow rate is within the predetermined range.
This has the effect of making flow measurement extremely easy.

[Brief explanation of drawings]

FIG. 1 shows a fluid circuit for flow rate measurement showing one embodiment of the present invention, and FIG. 2 shows a circuit diagram of an electrical judgment display circuit. 1... Laminar flow meter, 2... Pressure transducer, 6... Pressure gauge, 7... Measured object, 8... Upper limit Fixed orifice for setting, 9.
...Fixed orifice for lower limit setting, 12...
・Vacuum device, 20... Pressure comparator, 21
...... Upper limit comparator, 22... Lower limit comparator.

Claims (1)

[Claims] 1. Two fixed orifices with valves at the input and output ends that cut off the fluid and set the upper and lower limits of the flow rate, a second valve connected to both ends of the object to be measured, and the pressure at both ends. A parallel connection body of pressure gauges that outputs an electric signal corresponding to the difference, and an output end thereof is connected to an input end of the parallel connection body, and the input end is opened to the atmosphere to convert a change in flow rate into a pressure difference. A laminar flow meter, a pressure converter that converts the pressure difference into an electrical signal, a pressure regulating tank connected to the output end of the parallel connection body, and a regulating valve that allows the flow rate to be set arbitrarily to the pressure regulating tank. a vacuum device connected to the pressure regulating tank, another regulating valve that can arbitrarily set the flow rate with one side open to the atmosphere and connected to the pressure regulating tank, and a valve connected to the pressure regulating tank with one side open to the atmosphere; a comparator that outputs an output when the output of the pressure gauge exceeds a predetermined value in the process of increasing the degree of vacuum of the object to be measured; and a predetermined upper limit value of the flow rate flowing through the object to be measured determined by the 0 fixed orifice. and a comparison circuit that outputs an output when the output is within a lower limit value, and an AND circuit that outputs an output if there is an output of the comparison circuit at the moment when the comparator is activated. Flow measurement device.