JPS5997010A - Flowmeter - Google Patents

Abstract

PURPOSE:To improve accuracy with a simplified construction by providing a means of detecting the movement of the level of mercury, a specified amount of which is sealed into U-shaped tube with both ends thereof erected vertically, for example. CONSTITUTION:One end of a U-shaped tube 8 is connected to a third port 7 of a four-way changeover valve 1 while the other end thereof 8 is connected to a fourth port 9 and mercury 13 is sealed into the U-shaped tube 8 in a specified amount, for example, only enough to hold the mercury level 13A at an intermediate position where said mercury level 13A moves in the U-shaped tube 8. Straight tube sections at both ends of the U-shaped tube 8 are erected vertically and detection coils 14 are wound on the one erection section at two points as detection means. This can simplify the construction to achieve a highly accurate and stable measurement of flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flowmeter, and particularly to a flowmeter suitable for measuring the flow rate of high-pressure, minute fluids.

The structure of flowmeters is generally classified into two types: estimated type and actual measurement type, and actual measurement type volumetric flowmeters are suitable for measuring the flow rate of microfluid. Conventionally, such an actual measurement type volumetric flowmeter has a structure (Japanese Patent Publication No. 45-25028) that measures the flow rate by the vertical movement of a diaphragm plate installed in a container, but this type does not measure high-pressure fluid. It was difficult to apply it to the measurement of

In addition, a transparent cylinder is installed in the middle of the loop-shaped conduit,
A structure (Japanese Patent Publication No. 47-40829) has already been proposed in which a reciprocating piston is inserted into the cylinder and the amount of movement of the piston due to the flow of fluid in the cylinder is optically measured. Even with the previously proposed structure, leakage or friction loss between the cylinder and piston cannot be ignored in some cases, and it is not suitable for measuring high-pressure fluid. Furthermore, a pipe line having a uniform cross section is formed into a loop via a switching valve, a moving element is inserted into the pipe line so as to circulate in a fixed direction, and the flow rate is measured from the amount of movement of the moving element. Structure (Tokuko Sho 49-4898
No. 4) has already been proposed, but in this case, the structure is such that the slider passes through the bent pipe portion of the pipeline and the switching valve, making it even more difficult to prevent leakage. Therefore, it is not suitable for measuring high-pressure fluids as well as or more than the above-mentioned conventional examples. Furthermore, in any of the conventional examples described above, high-precision machining is required to reduce fluid leakage, and the overall structure is not necessarily simple.

An object of the present invention is to provide a flow meter that has a simple structure and can measure high-pressure fluid with high accuracy.

Therefore, in the present invention, both ends are, for example, vertical.

A predetermined amount of mercury is sealed in an upright U-shaped tube, and a detection means for detecting the movement of the mercury level is provided. When the fluid to be measured flows out from the other end when flowing in, and when the fluid to be measured flows into the other end, the fluid to be measured flows out from the one end, and the valve mechanism is operated to switch according to a detection signal from the detecting means. A calculation section is connected to the U-shaped tube and further calculates the flow rate of the fluid to be measured based on the detection signal from the detection means. In other words, the mercury sealed in the U-shaped tube is connected to the valve mechanism. The object is achieved by causing a reciprocating movement in the U-shaped tube by operation, detecting the reciprocating movement by the detecting means, and calculating the flow rate of the fluid to be measured by the calculating section. .

An embodiment of the present invention will be described below based on the drawings.

1 and 2 show a schematic configuration of an embodiment of a flowmeter according to the present invention. In FIG. 1, an inflow pipe 3 is connected to a first boat 2 of a four-way switching valve 1 as a valve mechanism. The fluid to be measured is configured to flow into the four-way switching valve 1 through the inflow pipe 3. An outflow pipe 5 is connected to a second port 4 located opposite to the first port 2, and the fluid to be measured flows out from the four-way switching valve 1 through this outflow pipe 5, and also flows out into the outflow pipe 5. A temperature and pressure detector 6 for the fluid to be measured is provided as necessary.
7. so that the temperature and pressure of the fluid to be measured are detected.
(It's on.

A driving mechanism 12 is connected to the valve body 11 of the four-way switching valve 1, and when the valve body 11 driven by the driving mechanism 12 is positioned in the state shown by the solid line in FIG. and the fourth boat 9 are communicated, and the second port 4 and the third port 7 are connected, and when the valve body 11 is rotationally driven to be positioned as shown by the chain line, the first The boat 2 and the third boat 7 are configured to communicate with each other, and the second port 4 and the third port 7 are configured to communicate with each other.

Further, one end of a U-shaped tube 8 is connected to the third boat 7 of the four-way switching 5P1, and the other end of the U-shaped tube 8 is connected to the fourth port 9. 13 is sealed in a predetermined amount, for example, an amount such that the mercury level 13A is located at an intermediate position within the U-shaped tube 8 where the mercury level 13A moves.

Further, the shape, inner diameter, and overall length of the U-shaped tube 8 can all be arbitrary, but they are durable and easy to process.

The inner diameter (diameter) is 5.0 mm due to the applicable range etc.
Appropriately, the length is about 10 mm, and the total length is about 1.0% to 5.0 m. Further, the material of the U-shaped tube 8 may be metal such as stainless steel, hard glass, or the like.

The straight tubular portions at both ends of the U-shaped tube 80 are vertically erected, and one of the vertical portions (on the left side in FIG. 1) has two detection coils 14 as a detection means spaced apart from each other by a predetermined distance. It is wrapped.

The sensing coil 14 is as shown in FIG.

An alternating current signal of a predetermined frequency is provided from an oscillator 21 via an amplifier 22. Although the magnitude of the frequency is not particularly limited, approximately 20 KHz to 30 KH7 is appropriate. Depending on whether or not the mercury level 13A is located within the detection coil 14, the phase of the alternating current signal in the detection coil 14 changes. The phase difference between the AC signal in the detection coil 14 and the constantly constant AC signal transmitted from the oscillator 21 is detected by the phase detection circuit 23.

The phase difference is compared in a comparator 24 to see if it is larger than a predetermined value, and when the phase difference is larger than the predetermined value, a detection signal is sent from the comparator 24 to a control unit 25 and a microcomputer as an arithmetic unit. 26 at the same time. The control unit 25 to which the detection signal has been applied immediately applies a drive signal to the drive mechanism 12, whereby the valve body 11 is rotationally driven to perform a switching operation. on the other hand,
The microcomputer 26 calculates the flow rate of the fluid to be measured based on the detection signal. Specifically, 2
The travel time of the mercury level 13A between the two detection coils 14 is measured from the detection signal, and a constant value based on the internal volume of the U-shaped tube 8 that is equal to the travel range of the mercury level 13A is determined, in other words, 2
The flow rate is calculated by dividing a constant value based on the internal volume of the U-shaped tube 8 between the two sensing coils 14 by the measured travel time. At this time, the temperature and pressure data of the fluid are inputted from the temperature and pressure detector 6 as necessary, so that appropriate conversion can be performed. Also.

The measurement results are displayed on a digital or analog display 2.
7 is configured to be displayed.

Next, the operation of this embodiment will be explained.

The valve body 11 of the four-way switching valve 1 is stopped at the rotational position shown by the solid line in FIG. 1, and the fluid to be measured is supplied from the inflow pipe 3.
The fluid to be measured is caused to flow into the upright portion on the right side of the tube 80 in the figure. The inflow of the fluid to be measured pushes the mercury level in the right-side upright part downward, while the mercury level 13A in the left-hand upright part of the U-shaped tube 8 in the figure is pushed down by the mercury level on the right side. It is raised by an amount corresponding to the amount of displacement. As the mercury level 13A in the left standing section rises, the fluid to be measured in the left standing section is discharged from the outflow pipe 5 via the four-way switching valve 1.

When the mercury level 13A reaches the detection coil 14 wound on the upper side in the figure, a change occurs in the phase of the AC signal leading to the detection coil 14, and this phase change is detected by the phase detection circuit 23. .

A sense signal is then provided by comparator 24.

The control unit 25 uses the detection signal provided by the comparator 24.
The drive mechanism 12 is driven through the four-way switching valve 1, and the valve body 11 of the four-way switching valve 1 is rotationally driven to the state shown by the dashed line in the 11th ffl. That is, when the mercury level 13A reaches the inside of the detection coil 14 located on the lower side in the figure, the four-way switching valve 1 is switched.

When the valve body 11 of the four-way switching valve 1 is switched to the state shown by the chain line in the figure, the fluid to be measured supplied from the inflow pipe 3 is
The mercury level 13A is pushed down by the mercury level 13A, and the fluid to be measured in the right upright part 1 flows out from the outflow pipe 5 through the four-way switching valve 1. be done.

When the mercury level 13A in the vertical section on the left falls and reaches the detection coil 14 on the lower side in the figure, a change occurs in the phase of the detection coil 140 on the lower side, and this change in phase is detected by the phase detection circuit 23. It is detected and then a detection signal is provided by the comparator 24. Based on this detection signal, the drive mechanism 12 is driven via the control section 25, and the valve body 11 of the four-way switching valve 1 is again switched to the state shown by the solid line in the figure.

Mercury levels will rise again at 13A.

In this manner, the mercury level 13A reciprocates between the two detection coils 14, and a detection signal is generated at the moment it reaches each detection coil 14. Based on this detection signal, the microcomputer 26 measures the travel time of the mercury level 13A between the detection coils 14, and measures the travel time of the mercury level 13A between the detection coils 14.
The flow rate is calculated by dividing a constant value based on the internal volume between the two sensing coils 14 by the travel time, and the calculated result is displayed as a measured value on the display 27.

Note that when the fluid to be measured is, for example, gas.

The temperature and pressure at the time of measurement of the fluid to be measured are detected by the temperature and pressure detector 6 provided in the outflow pipe 5, and the necessary conversion is performed in the microcomputer 26 based on the temperature and pressure to determine the volumetric flow rate in the standard state. It may also be displayed on the display 27 as follows.

This embodiment has the following effects.

Since the structure is such that the mercury 13 is reciprocated within the U-shaped tube 8, it is different from the case where a piston is enclosed in a cylinder and the piston is reciprocated. Unlike the case where the fluid to be measured is leaked, there is very little or no leakage of the fluid to be measured, so there is an effect that measurement errors due to leakage of the fluid to be measured can be eliminated.

Furthermore, when a solid piston is reciprocated in a cylinder, a pressure loss occurs due to friction between the inner wall of the cylinder and the outer periphery of the piston, but the mercury 13 in the U-shaped tube 8 hits the inner wall of the U-shaped tube 8. In other words, the mercury 13 in the U-shaped tube 8 does not move back and forth while making frictional contact with the inner wall of the U-shaped tube 8. In addition, based on the reciprocating motion of the mercury 13 (pressure loss is extremely small), this also has the effect of allowing high-pressure fluid to be measured with high precision.

Furthermore, since the mercury 13 can be easily moved through the U-shaped tube 80 while maintaining a sealed state, unlike when moving a solid moving element inside the bent tube, it is necessary to There is no need to prepare any additional means (the structure as a whole can be extremely simple).

Moreover, since the movement of the mercury level 13A is detected based on the phase change of the detection coil 140 installed in the U-shaped tube 8, the configuration of the detection means itself for detecting the movement of the mercury level 13 is simplified. From this point of view as well, the flowmeter has a simple structure as a whole and is easy to assemble.

Furthermore, as long as the internal volume between the two sensing coils 14 is determined with high precision, the inner wall of the U-shaped tube 8 can be machined with great precision. It is something that can be done.

Furthermore, since there is no leakage of the fluid to be measured, there is an effect that it is safe even when various dangerous gases having toxicity, flammability, etc. are used as the fluid to be measured.

In the implementation, it was assumed that the valve mechanism that flows in and out of the U-shaped pipe 80 while appropriately switching the fluid to be measured is the four-way switching valve 1; . For example, it may be a combination of a plurality of on-off valves.

In addition, the detection coil 14 as a detection means was assumed to be wound around two U-shaped tubes 802 at a predetermined interval, but three
Two sensing coils may be selected and used from the three or more sensing coils that are wound at more than one location and are used selectively depending on the flow rate of the fluid to be measured, or alternatively, the sensing coils 14 may be wound around each of the three or more sensing coils. The installation position may be movable, so that the distance between the detection coils 14 can be adjusted as appropriate.

Further, the phase change occurring in the detection coil 14 is detected by the phase detection circuit 23, and the movement of the mercury level 13A moving within the detection coil 14 is determined by the comparator 24 from the state of the phase change occurring in the detection coil 14. However, the phase change is detected by the phase detection circuit 23, the comparator 24 generates a pulse, the microcomputer 26 measures the pulses generated per unit time, and calculates the internal volume of the U-shaped tube 8 into the number of pulses. The flow rate may also be determined by multiplying by a constant based on the flow rate. Alternatively, the detection coil 1
Due to the speed of the mercury level 13A moving in coil 1
In other words, even though the phase changes are the same, the phase change states are different when moving quickly and when moving slowly. The flow rate may be calculated by grasping the state of this phase change. In this case, one detection coil is sufficient.

Furthermore, the detection means is not limited to the detection coil 14, but may be a magnetic detector such as a reed switch, an optical detector such as a light emitting element or light receiving element, or the like.

Yet again. The upright portions at both ends of the U-shaped tube 8 do not necessarily need to be vertically erected, and may be erected in an inclined state.

As mentioned above, according to the present invention, the structure is simple.

A flowmeter capable of highly accurate measurement of high-pressure fluid can be provided.

Next, the present invention will be explained in more detail using the following experimental examples. - The U-shaped tube 8 was formed by a stainless steel tube with an inner diameter of 6.2 wn and a total length of 2 mm, and a four-way switching valve with an actuator manufactured by Hawk was used as the four-way switching valve 1, and hydrogen was used as the fluid to be measured. Gas was supplied, and the flow rate of the hydrogen gas was measured at a temperature of 25 DEG C. and a high pressure of 22 okl/2.alpha.m.G while varying the flow rate between 50 and 100 ONL/hr. As a result, it was confirmed that the error range was within ±0.5%, and no leakage of hydrogen gas, which was the fluid to be measured, was detected, making it possible to measure the flow rate with high precision and safety.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a schematic configuration of an embodiment of a flowmeter according to the present invention, and FIG. 2 is a circuit diagram of the embodiment. 1... Four-way switching valve as a valve mechanism, 3... Inflow pipe. 5...Outflow pipe, 8...U-shaped pipe, 11...Valve body, 1
2... Drive mechanism, 13... Mercury, 13A... Water temperature level, 14... Detection coil as detection means, 21
...Oscillator, 23.. Phase detection circuit, 24.. Comparator, 25.. Controller, 26.. Microcomputer as an arithmetic unit. 2T...Indicator. Agent: Patent attorney Minoru Kinoshita (and 1 other person)

Claims (1)

[Claims] (1) A U-shaped tube with both ends erected, a predetermined amount of mercury sealed in the U-shaped tube, a detection means for detecting movement of the mercury level, and a fluid to be measured flowing into one end of the U-shaped tube. a valve mechanism that causes the fluid to be measured to flow out from the other end when the fluid is to be measured, and causes the fluid to be measured to flow out from the one end when the fluid to be measured is to flow into the other end, and is switched in response to a detection signal from the detection means; A flowmeter characterized in that a calculation section that calculates a flow rate of a fluid to be measured based on a detection signal from a detection means is biased. (2. In claim 1, the detection means consists of a detection coil wound in two places in the U-shaped tube, and the current of the detection coil as the mercury level moves in and out of the detection coil. A flow meter configured to detect a movement of the mercury level by a phase change of the mercury level.