JPH07174596A - Butterfly valve provided with flow-rate measuring function, and method for measurement of flow rate in butterfly valve - Google Patents

Abstract

PURPOSE:To measure the flow rate of a fluid precisely in terms of space and time by providing a valve opening-degree detection means and a torque detection means which detects a dynamic torque acting on a valve body due to the flow of the fluid while a valve rod is used as an axis. CONSTITUTION:An actuator 11 is connected to one end 9 of a valve rod 3, a valve rod 2 is turned by the actuator 11 by making use of the valve rod 3 as an axis, and a valve opening degree is decided. A strain gage 12 which detects the very small twist of the valve rod 3 is installed at the valve rod 3, and a torque detection means 14 which detects a dynamic torque acting on a valve body 2 by making use of the valve rod 3 as an axis is constituted of the strain gage 12 and of a torque converter 13. The amount of rotation of the valve rod 3 is detected by a potentiometer 15 via gears 10, 4 which are installed on the circumference of the valve rod 3. A valve- opening-degree converter 16 converts a signal from the potentiometer 15 into the valve opening degree of a butterfly valve and outputs the valve opening degree. The torque which is output from the means 14 and the valve opening degree which is output from a valve-opening-degree detection means 1 are input to a flow-rate computation means 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly valve, and more particularly to a butterfly valve having a flow rate measuring function.

The invention also relates to a method for measuring the flow rate in a butterfly valve and a method for controlling the flow rate in a butterfly valve.

[0003]

2. Description of the Related Art Conventionally, in a butterfly valve, a valve body incorporated in a main body so as to be rotatable around a valve rod is, for example, manually or pneumatically or electrically operated from the outside of the main body via the valve rod. It is operated by turning.

Regarding the control of the flow rate of the fluid passing through the butterfly valve, the flow rate is measured by means for measuring the flow rate, and the valve opening degree of the butterfly valve is adjusted based on the measured flow rate to control the flow rate. Is controlled.

For example, a flow meter is installed in the vicinity of the butterfly valve in addition to the butterfly valve, and the valve opening of the butterfly valve is controlled assuming that the measured flow rate of this flow meter is the flow rate passing through the butterfly valve.

Such a flow meter has, for example, an orifice provided in a pipe and a pressure sensor for detecting the pressure on the upstream side and the pressure on the downstream side of the orifice. Has a capacity coefficient (Cv value: constant) set in advance, and a differential pressure flowmeter in which an orifice and a pressure sensor are combined to calculate the flow rate from the pressure difference (ΔP) of these detected pressures and the capacity coefficient. Is common.

As an example in which the differential pressure flowmeter in which such an orifice and a pressure sensor are combined is improved to be more compact, a butterfly valve is provided with the function of the orifice so that the pressure on the upstream side and the pressure on the downstream side of the butterfly valve are increased. The butterfly valve has a pressure sensor and a means for detecting the valve opening of the butterfly valve. The capacity coefficient (Cv value: a function of the valve opening) specific to the butterfly valve is set in advance by experiments or the like. , A differential pressure flow meter combining a butterfly valve and a pressure sensor for calculating a flow rate from a differential pressure (ΔP) of these detected pressures, a detected valve opening degree and a capacity coefficient corresponding to the valve opening degree By the applicants of the present application, JP-A-62-27087
No. 3, proposed.

Further, as an example of a flow meter similar to the differential pressure flow meter in which such a butterfly valve and a pressure sensor are combined, in a gate valve, the gate valve is made to have the above-mentioned function of the orifice, It has a pressure sensor for detecting the pressure on the upstream side and a pressure on the downstream side and means for detecting the valve lift of the gate valve, and the capacity coefficient (Cv value: valve lift function)
Is set, and the differential pressure of these detected pressures (Δ
P), a differential pressure flowmeter that combines a gate valve that calculates the flow rate from the detected valve lift and the capacity coefficient corresponding to this valve lift and a pressure sensor is disclosed in Japanese Utility Model Publication No. 62-1117. Has been proposed to.

Conventionally, instead of the above-mentioned differential pressure flowmeter, for electromagnetic fluid, for example, an electromagnetic flowmeter is installed near the butterfly valve to measure the flow rate and control the valve opening of the butterfly valve. It may be done.

Conventionally, in a butterfly valve, the smaller the torque required to rotate and fix the valve body, for example, the operating torque from the outside required for the actuator, the smaller the actuator, and the better the operability. However, it has been regarded as advantageous and preferable. Therefore, research and development have been continued in order to further reduce the dynamic torque that acts on the valve body around the valve rod by the fluid. For example, the applicants of the present application have proposed a butterfly valve provided with a seat ring having an effect of reducing an operating torque from the outside in the specifications of JP-A-55-142169 and JP-A-56-28355.

The conventional butterfly valves including the above-mentioned butterfly valve function as a fluid throttle mechanism.

[0012]

However, as described above, the conventional butterfly valve has only a function as a fluid throttle mechanism, and in order to control the flow rate, some kind of sensor is included in the flow passage in addition to the valve body. It is necessary to install a mechanism for measuring the flow rate, and the butterfly valve device including the mechanism for measuring the flow rate complicates the structure of the flow path and is not compact.

Further, in the conventional case, since the flow rate of the fluid passing through the butterfly valve is measured indirectly or at a certain distance from the butterfly valve, this measured flow rate and the flow rate actually passing through the butterfly valve are measured. There is a quantitative and time lag between the two, which makes accurate flow rate measurement and flow rate control difficult.

It is an object of the present invention to make the valve body itself function as a sensor for measuring a flow rate in the butterfly valve in addition to the function as a fluid throttle, that is, the first object of the present invention. A second object of the present invention is to provide a method for measuring a flow rate using a valve body and a valve rod as a sensor in a butterfly valve. To do.

[0015]

According to the present invention, the first object is to provide a valve opening detecting means for detecting a valve opening, and a dynamic valve acting on a valve element with a valve rod as an axis by a fluid flow. And a butterfly valve for measuring the flow rate of the fluid, which has a torque detecting means for detecting a torque.

According to the present invention, the second object is to detect the valve opening in the butterfly valve and to detect the dynamic torque acting on the valve element about the valve rod as an axis by the flow of the fluid, thereby detecting the detected valve. This is accomplished by a method that determines the flow rate of the fluid as a function of opening and the detected dynamic torque.

[0017]

According to the experiments conducted by the inventor of the present application, under the same conditions for the same fluid, the flow rate of the fluid passing through the butterfly valve acts on the valve element around the valve rod by the valve opening degree and the fluid. It is substantially uniquely determined by the dynamic torque and the unique characteristics of the individual butterfly valves.

Therefore, according to the butterfly valve of the present invention,
Since the valve opening degree detecting means detects the valve opening degree and the torque detecting means detects the dynamic torque acting on the valve body with the fluid as the shaft by the fluid, the flow rate and the valve opening characteristic of the butterfly valve are beforehand detected. If a relational expression between the degree and the dynamic torque is set, the flow rate can be obtained from the detected valve opening degree and the detected dynamic torque.

In general, under the same conditions for the same fluid, the flow rate of the fluid passing through the butterfly valve depends on the valve opening degree, the pressure difference between the upstream side and the downstream side of the valve body, and the characteristic of each butterfly valve. Characterized by and governed by. That is, the flow rate Q can be expressed as the equation 1 as a function F peculiar to each butterfly valve having the valve opening degree θ and the differential pressure ΔP as variables.

Q = F (θ, ΔP) ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (1) The function F is determined by the diameter of the butterfly valve body, the shape of the valve disc, etc. It can be intuitively understood that the function is a function that increases as the degree θ increases and that the function increases as the differential pressure ΔP increases. Therefore, if the peculiar function F of each butterfly valve is obtained by experimental analysis or theoretical analysis, in order to obtain the flow rate Q when using the butterfly valve, the valve opening θ and the differential pressure ΔP are measured. By substituting these into the function F, the flow rate Q can be obtained.

The inventor of the present application pays attention to the point that the dynamic torque acting on the valve element by the fluid about the valve rod as an axis changes depending on the flow rate of the fluid. That is, instead of the above-mentioned function F, a function G such as Expression 2 expressing the flow rate Q with the valve opening θ and the dynamic torque T as variables is examined.

Q = G (θ, T) ‥‥‥‥‥‥‥‥‥‥‥ (2) In order to study this function G, the inventor of the present application performs the following experiments i) to vii).

I) The desired differential pressure Δ for the butterfly valve
Let P act.

Ii) The valve opening θ of the butterfly valve, the torque T, and the flow rate Q of the fluid passing through the butterfly valve are measured.

Iii) The valve opening θ is fixed, the differential pressure ΔP is changed, and the change of the torque T and the change of the flow rate Q at that time are recorded.

Iv) The valve opening θ is changed by an appropriate angle Δθ to measure / record iii).

V) Measurement / recording is performed by repeating iii) and iv) for all of the valve opening θ = 0 ° to 90 ° at intervals Δθ.

Vi) If necessary, perform i) to v) for various fluids.

Vii) Perform i) to vi) for the various butterfly valves.

From the results of the above experiments i) to vii),
It can be seen that the function G is practically established. Therefore, next, the function G peculiar to this butterfly valve is obtained as an empirical formula by filling the interval of the empirical data by an appropriate interpolation method using this empirical data or by using an appropriate approximate expression.

Therefore, when the butterfly valve is actually used, the flow rate Q is uniquely determined by measuring the valve opening θ and the torque T by using the unique function G without measuring the differential pressure ΔP. It becomes possible to calculate.

The theoretical proof that the function G is practically established by the experiment and that the function G is specifically obtained is shown below.

Cv which is generally the capacity coefficient of a butterfly valve
It is known that a function is established between the value (a function value having the flow rate Q and the differential pressure ΔP as variables) and the valve opening degree θ.

On the other hand, a function is established between the Cu value which is the practical torque coefficient of the butterfly valve (a function value having the torque T and the differential pressure ΔP as variables) and the valve opening degree θ.

Therefore, when the Cv value and the Cu value are expressed by the equations, the equations 3 and 4 are obtained. Cv = f (Q, ΔP) ‥‥‥‥‥‥‥‥‥‥ (3) Cu = g (T, ΔP) ‥‥‥‥‥‥‥‥‥‥ (4) Here, the following equations 5 and 6 are obtained. Assuming that it holds, Cv = ff (θ) ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (5) Cu = gg (θ) ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (6) From Equation 3 and Equation 5, = F '(Cv, ΔP) = f' (ff (θ), ΔP) (7) holds. From Equation 4 and Equation 6, ΔP = g ′ (Cu, T) = g ′ (gg (θ), T) ... (8) holds. Therefore, from Equation 7 and Equation 8, Q = h (ff (θ), g ′ (gg (θ), T)) = k (T, θ) (9) holds. Here, Equation 9 is equal to Equation 2, and thus the function k and the function G are equal. That is, the experiment conducted by the inventor of the present application confirmed that the assumption that the equations 5 and 6 hold is correct in a practical sense, and the equations 5 and 6 are experimentally determined.
It is substantially the same as the calculation of ff (θ) and gg (θ) in.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the preferred embodiments shown in the drawings.

FIG. 1 shows a butterfly valve which is an embodiment of the present invention. The main body 1 contains a valve body 2 having an outer diameter slightly smaller than the inner diameter of the main body 1, and the valve body 2 includes a valve rod 3
It is rotatably fixed to the body 1. The valve body 2 is arranged on the valve rod 3 in the central type in the present embodiment, but may be an eccentric type. In order to maintain the hermeticity between the valve rod 3 and the bearing hole provided in the main body 1, a gland packing 7
And a seal ring 8 is installed. A shaft bearing 6 is installed in order to make the rotation of the valve rod 3 smooth. The main body 1 thus constructed is connected to the tube 100 as shown in FIG. 2 by a known method.

The tube 100 is preferably made of metal or resin and has an inner diameter of a few mm to a few m, more preferably a few dozen mm to a few m, and a few dozen mm to a few m. The thing is more preferable. For the tubes 100 having various inner diameters, the body 1 having an inner diameter similar to the inner diameter of the tube 100 is applied. The larger the inner diameters of the pipe 100 and the main body 1, that is, the larger the valve body 2, the larger the dynamic torque that acts on the valve body 2 around the valve rod 3 due to the flow of the fluid as a signal, and the accuracy of measurement is improved. It will be easier. Conversely, the smaller the valve body 2, the smaller the dynamic torque as a signal, and it is preferable to reduce noise such as electrical noise in order to enable highly accurate measurement. The closer the inner diameter of the pipe 100 and the inner diameter of the main body 1 are to each other, the more the flow turbulence that may occur at the joint between the pipe 100 and the main body 1 is prevented, so that a flow closer to a laminar flow flows into the main body 1. This is advantageous for measuring higher flow rates.

In this embodiment, since the outer diameter of the valve body 2 is slightly smaller than the inner diameter of the main body 1, the completely sealed state cannot be maintained even when the valve opening is 0 °, but it is made of rubber, Teflon or metal. The seat ring or 0-ring may be arranged along the inner peripheral surface of the main body 1 to ensure the sealing performance of the butterfly valve at a valve opening of 0 °.
Also, other butterfly valves or other types of valves that can be fully sealed can be placed in line with the butterfly valve with respect to tube 100.

The actuator 11 shown in FIG. 2 is connected to one end 9 of the valve rod 3 by a known method. By the actuator 11, the valve body 2 is rotated around the valve rod 3 as an axis,
Moreover, the valve opening is determined by being fixed at a certain angle. As the actuator 11, an actuator such as an electric actuator, a pneumatic actuator, a diaphragm actuator, and an electromagnetic actuator can be used. Alternatively, the valve rod 3 may be manually rotated.

A strain gauge 12 is installed on the valve rod 3 in order to detect a minute twist of the valve rod 3. The strain gauge 12 is preferably a known strain gauge. The torque converter 13 is a strain gauge 12
The twist detected by is converted into a dynamic torque applied to the valve body 2 about the valve rod 3 as an axis and output. That is, the strain gauge 12 and the torque converter 13 constitute a torque detecting means 14 that detects a dynamic torque acting on the valve body 2 with the valve rod 3 as an axis.

As the means for detecting the dynamic torque applied to the valve body 2 with the valve rod 3 as an axis, various known torque detecting devices can be used in addition to the above, but in terms of required accuracy and cost. The best one should be selected from. Further, in order to prevent the bending strain generated in the valve rod 3 from being mixed as noise into the measurement signal of the strain gauge 12, the shaft bearings 6 are arranged in two rows on both sides of the strain gauge 12, and the strain gauge 12 has two rows. This prevents the bending strain from being transmitted. Further, it is desirable that the strain gauge 12 is installed in a portion of the valve rod 3 where the dynamic torque acting on the valve body 3 is more directly transmitted. In the present embodiment, the strain gauge 12 is disposed via the shaft bearing 6 and the gland packing 7. It is installed in the portion of the valve rod 3 which is located relatively close to 2. By doing so, the accuracy of detecting the dynamic torque acting on the valve body 2 can be improved.

The amount of rotation of the valve rod 3 is detected by a potentiometer 15 as an angle sensor via a gear 10 provided on the circumference of the valve rod 3 and a gear 4 meshing with the gear 10.
The valve opening converter 16 converts the signal from the potentiometer 15 into the valve opening of the butterfly valve and outputs it. In the present embodiment, the rotation angle of the valve rod 3 is doubled by the gear ratio between the gear 4 and the gear 10 to enable more accurate detection of the valve opening. That is, gear 10, gear 4, potentiometer 15
The valve opening converter 16 constitutes the valve opening detection means 17. The potentiometer 15 may be built in the actuator 11 or may detect the rotation of the valve rod 3 via another gear forming the actuator 11.

As the valve opening degree detecting means 17, a rotary encoder for directly or indirectly counting the number of teeth of the gear 4 or 10 may be connected to the gear 4 or 10, and the number of teeth of the gear 4 or 10 may be connected. The rotation angle of the valve rod 3, that is, the valve opening may be converted and output. Further, the valve opening detecting means 17 may be provided in the valve rod 3 on the side opposite to the torque detecting means 14 with respect to the valve body 2. Various other well-known means may be applied as the means for measuring the valve opening degree. Incidentally, FIG. 2 shows a schematic diagram of the butterfly valve of this embodiment installed in the pipe 100.

According to the present invention, the flow rate of the fluid passing through the butterfly valve from the measured dynamic torque Tm output from the torque detecting means 14 and the measured valve opening θm output from the valve opening detecting means 17. Can be obtained indirectly.

As the most basic method, as a manual work using a calculator or the like, the torque Tm and the valve opening θm are determined by a dynamic torque T and a valve opening θ which are peculiar to the butterfly valve and which can be set in advance. Equation 2 representing the flow rate as a function; Q = G (θ, T) ‥‥‥‥‥‥‥‥‥‥ (2) is substituted, the flow rate Qm corresponding to the torque Tm and the valve opening θm is unique. Required to. Alternatively, the corresponding flow rate Qm can be obtained from the torque Tm and the valve opening degree θm by a chart showing the relationship between the torque T, the valve opening degree θ, and the flow rate Q that can be set in advance. That is, the torque detecting means 14 and the valve opening degree detecting means 17 achieve the first object of the present invention.

However, in this embodiment, the torque Tm output from the torque detecting means 14 and the valve opening θm output from the valve opening detecting means 17 are input to the flow rate calculating means 18. The flow rate calculation means 18 stores a function G that is preset in each butterfly valve and that stores a function G represented in Formula 2, and a calculator 20 that calculates the function G by substituting the torque Tm and the valve opening θm. The flow rate Qm corresponding to the input torque Tm and the valve opening degree θm is rapidly calculated and output.

At this time, the calculation result by the equation (2) may be corrected by the temperature or the viscosity or specific gravity of the fluid. In this case, the necessary correction amount is stored in advance. It may be stored in the device 19.

Further, the temperature t, the viscosity ξ, the specific gravity gr, etc. at the time of measuring the flow rate may be inputted to the flow rate calculating means 18 as parameters set from the outside, or the temperature may be set in the fluid flow path near the butterfly valve. It is also possible to separately provide a meter, a viscometer, a specific gravity meter, and the like, and automatically input the measured output data of these to the flow rate calculation means 18.

Further, the above-mentioned temperature t, viscosity ξ, and specific gravity gr
It is also possible to use, for example, as a variable of a function G'representing a preset flow rate, instead of as a correction parameter. In this case, that is, it is necessary to set the function G ′ shown in Expression 10; Q = G ′ (T, θ, t, ξ, gr). It is possible to set by using more experiments than setting the function G.

By setting such a function G'and storing it in the flow rate calculating means 18, a butterfly valve having a flow rate measuring function applicable to various situations can be obtained. Therefore, the fluid in this embodiment is water, alcohol, lubricating oil,
Liquids such as fuel oil and petroleum can be applied regardless of type, and can be applied to all gases such as air, combustion gas, fuel gas, and steam by improving the accuracy of the torque detection means.

Flow rate Qm output from the flow rate calculating means 18
Is input to the adjusting means 21 in this embodiment. A desired set flow rate Qd is externally set in the adjusting means 21. The flow rate Qd from the outside may be set from a remote place via a communication device by using a well-known remote operation means, or may be set on the machine side. The adjusting means 21 calculates the difference between the flow rate Qm and the flow rate Qd, and instructs the actuator 11 to rotate in a direction to reduce the difference according to the difference.

Next, the operation of this embodiment will be described. When the main body 1 is arranged in series with the portion of the pipe 100 whose flow rate is to be controlled by the butterfly valve, a fluid such as water or oil flowing in the pipe 100 causes a pressure difference between the upstream side and the downstream side of the butterfly valve. And the valve opening degree.

In the present embodiment, the valve opening is from 0 ° to 90 °.
The valve opening degree of 0 ° means that the valve is closed, and the fluid only flows through a slight gap between the valve body 2 and the main body 1. The valve opening of 90 ° means that the valve is completely opened, and the pressure difference between the fluid on the upstream side and the fluid on the downstream side of the butterfly valve is minimum.

Now, it is assumed that the fluid is flowing through the butterfly valve for any valve opening degree. Valve opening detection means 1
7 detects the valve opening and outputs it as the valve opening θm. On the other hand, the torque detecting means 14 detects a dynamic torque acting on the valve element 2 with the fluid around the valve rod 3 as an axis and outputs it as the torque Tm. The flow rate calculation means 18, which receives the valve opening degree Qm and the torque Tm, calculates the corresponding flow rate Qm by the function G or G ′ shown in the equation 2 or the equation 10 and outputs it to the adjusting means 21. The adjusting means 21, which receives the flow rate Qm, receives the desired flow rate Qd set from the outside and the measured flow rate Qm.
If there is a difference between and, the actuator 11 is instructed to reduce this difference. That is, the adjusting means 21
Indicates to the actuator 11 a) if Qd> Qm, a rotation instruction to increase the valve opening degree; and b) if Qd <Qm, the rotation degree is decreased to decrease the valve opening degree. C) When Qd = Qm, do not instruct rotation.

Therefore, one feedback loop in which the actuator 11 is rotated so that the flow rate Qm approaches the flow rate Qd as much as possible is constituted by this embodiment. When the flow rate Qm and the flow rate Qd coincide with each other due to the rotation of the actuator 11, the adjusting means 21 does not give a rotation instruction to the actuator 11, so that the actuator 11 does not rotate and the valve opening is fixed, so that the flow rate Qm is maintained. To be done.

Further, when the pressure on the upstream side and / or the downstream side of the butterfly valve changes when the flow rate Qm and the flow rate Qd match, the flow rate Qm changes, but according to this embodiment, the above-mentioned feedback function causes The flow rate Qd can be quickly matched.

In this embodiment, the valve element 2 is made to function as a sensor for measuring the flow rate, and the valve element 2 is made to function again as a throttle based on the flow rate information obtained from the valve element 2 as a sensor. Therefore, it is possible to control the flow rate more directly and more accurately in space and time.

Next, setting of the function G in this embodiment will be described. The function F represented by the equation 1 is well known, and in practice, the equation 11 is generally used.

Q = F (θ, ΔP) = αCv√ΔP (11) However, Cv = ff (θ) ... (5) where α is the specific gravity or viscosity of the fluid. It is a correction coefficient based on temperature and temperature. The meaning of Expression 11 is that if the valve opening θ is fixed, the flow rate Q and the parallel root of the differential pressure ΔP are in a proportional relationship, and the proportional constant is α × Cv. FIG. 3 shows an example of the relationship of Expression 11, and FIG. 4 shows an example of the relationship of Expression 5. In this embodiment, Equation 11 is assumed.

On the other hand, regarding the relationship between the torque T, the valve opening degree θ, and the differential pressure ΔP, the following expression 12 is assumed in this embodiment.

T = H (θ, ΔP) = βCu√ΔP (12) where Cu = gg (θ) ‥‥‥‥ (6) where β is the specific gravity or viscosity of the fluid or It is a correction coefficient based on the temperature. The expression 12 means that, if the valve opening θ is fixed, the torque T and the parallel root of the differential pressure ΔP are in a proportional relationship, and the proportional constant is β × Cu.
FIG. 5 shows an example of the relationship of Expression 12, and FIG. 6 shows an example of the relationship of Expression 6.

By eliminating the differential pressure ΔP from the above equations 11 and 12, equation 13 is obtained.

Q = G (θ, T) = (α / β) (Cv / Cu) T (13) However, Cv = ff (θ), Cu = gg (θ) Meaning of Expression 13 The point is that if the valve opening θ is fixed, the flow rate Q and the torque T are in a proportional relationship, and the proportional constant is (α / β) × (Cv / Cu). Therefore, ff (θ) and g when θ is changed experimentally
If g (θ) is obtained, the function G (θ, T) can be set.

An example of an experiment for obtaining ff (θ) and gg (θ) is shown below.

B. Equipment used The equipment used in the experiment is shown in the table. A bearing 6 is used to support the valve rod 3, and the inner diameter of the main body 1 is equal to the outer diameter of the valve body 2 +2 mm. FIG. 7 shows an outline of the experimental apparatus. The pressure gauge 22 measures the pressure P ₁ on the upstream side of the butterfly valve 27, and the differential pressure gauge 23 measures the differential pressure ΔP on the upstream side and the downstream side of the butterfly valve 27. The flow rate Q passing through the butterfly valve 27 is measured by the electromagnetic flow meter 24. The fluid is supplied to the butterfly valve 27 and the bypass valve 26 by the fluid supplier 25. The bypass valve 26 is used to set the flow rate supplied to the butterfly valve 27 by changing the valve opening degree.

[0067]

[Table 1]

B. Measuring method As a measuring method, a D / A converter is used and the bypass valve 2
6 and the opening of the butterfly valve 27 while controlling the torque T, the differential pressure ΔP, and the pressure P for each valve opening θ of the butterfly valve 27.
Repeat for ₁ and flow rate Q. The measurement conditions include a sampling frequency of 200 Hz, sampling points of 200 points / sec, a valve opening θ setting interval of 0.2 mA, a valve opening θ setting range of 20 mA to 4 mA, and a bypass valve 26 setting interval of 1 m.
A, the setting range of the bypass valve 26 is 20 mA to 10 mA.

Water is used as the fluid and the temperature is kept at room temperature. The specific procedure of measurement is as shown in the following (a) to (g).

(A) The valve opening degree of the bypass valve 26 is set.

(B) The valve opening θ of the butterfly valve 27 is set.

(C) The torque T, differential pressure ΔP, flow rate Q, pressure P ₁ and valve opening θ are measured.

(D) Record the measurement data.

(E) Repeat (b) to (d) 80 times.

(F) When the measurement is completed 80 times, the procedure is repeated from (a).

(G) The process ends when the specified number of times (a) is repeated.

C. Results of the experiment Cv value and C for the measured valve opening θm obtained from the experiment
The u values are shown in FIGS. 8 and 9, respectively. Although the points obtained on the figure are discrete values obtained by the experiment, in the present embodiment,
With respect to these points, the function ff (θ) shown in Expression 14 is calculated using a fourth-order approximation expression, and the function gg (θ) shown in Expression 15 is obtained using a fifth-order approximation expression.

Ff (θ) = θ ⁴ A ₄ + θ ³ × A ₃ + θ ² × A ₂ + θ × A ₁ + A ₀ (14) However, A ₄ : -9.146 × 10 ^-5 A ₃ : 1: 531 × 10 ^-2 A ₂ : -4.746 × 10 ^-1 A ₁ : 1.224 × 10 A ₀ : 0.00000 gg (θ) = θ ⁵ B ₅ + θ ⁴ B ₄ + θ ³ × B ₃ + θ ² × B ₂ + θ × B ₁ + B ₀ (15) However, B ₅ : 8.540 × 10 ⁻¹⁰ B ₄ : − 1.672 × 10 ⁻⁷ B ₃ : 1.125 × 10 ⁻⁵ B ₂ :: − 3.572 × 10 ⁻⁴ B ₁ : 4.919 × 10 ⁻³ B ₀ : -2.588 × 10 ^{−2 The} function ff (θ) and the function gg (θ) are shown in FIGS. 10 and 11.
Shown in. Therefore, according to this embodiment, Cv = ff (θ) ‥‥‥‥‥‥‥‥‥ (5) Cu = gg (θ) ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Set the Cv value and Cu value as (6).

Therefore, when actually using the butterfly valve 27 or a butterfly valve of the same type as the butterfly valve 27, if the valve opening θ and the torque T are measured, the equation 13 can be obtained without measuring the differential pressure ΔP. Can be used to calculate the flow rate Q.

Although the fourth and fifth approximation formulas are used in this embodiment, other approximation formulas may be used. For example, formulas 16 and 17 can be used as the nth approximation formula.

[0081] However, A _j is a j-th coefficient.

[0082] However, B _j is a j-th coefficient.

A well-known approximation expression different from the expressions 16 and 17 may be used. Various conditions in the experiment of the present embodiment, such as the sampling frequency, the setting interval of the valve opening degree, and / or the setting interval of the bypass valve are preferably changed according to the required measurement accuracy of the flow rate.

Further, in this embodiment, equations 11 and 1 are used.
2 is assumed, but this assumption is not necessary, and the function F (θ, ΔP) and the function H are experimentally calculated from the flow rate Q, the valve opening θ, the differential pressure ΔP, and the torque T measured in the experiment.
(Θ, ΔP) may be set.

In the present embodiment, the function ff (θ)
And the function gg (θ) are set first, and then the function G (θ, T)
However, G (θ, T) may be directly set as an empirical formula based on the experimental result.

Further, the relationship between the flow rate Q, the valve opening degree θ, and the torque T is summarized as a chart from the experimental data, and the spaces between the discrete points indicated by the experimental data are appropriately filled by using an appropriate interpolation function, and instead of calculation. Alternatively, the flow rate Q may be obtained from the valve opening θ and the torque T using the chart.

The above-described method of obtaining the flow rate Q can be quickly performed by using a computer.

[0088]

According to the butterfly valve of the present invention, the valve opening degree detecting means detects the valve opening degree, and the torque detecting means detects the dynamic torque acting on the valve element by the fluid with the valve rod as the axis. Therefore, if the relational expression of the flow rate, valve opening, and dynamic torque specific to the butterfly valve is set in advance, the flow rate can be obtained from the detected valve opening and the detected dynamic torque, and the valve body Since it has a function as a flow rate sensor in addition to a function as a throttle, it is possible to measure the flow rate of the fluid passing through the butterfly valve more accurately in a direct manner spatially and temporally. It is possible to control the flow rate more accurately and quickly by using the specified flow rate, and it can be applied to non-conductive fluid such as oil. Also, in order to control to a predetermined flow rate, a butterfly valve in the fluid flow path It may eliminate the need to particularly install the flow sensor outside.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view showing a part of an embodiment of the present invention.

FIG. 2 is a conceptual diagram of an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a flow rate and a differential pressure for explaining an embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a capacity coefficient and a valve opening for explaining an embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between torque and differential pressure for explaining an embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a practical torque coefficient and a valve opening degree for explaining an embodiment of the present invention.

FIG. 7 is a conceptual diagram showing an experimental device in an example of the present invention.

FIG. 8 is a diagram showing a capacity coefficient value with respect to a measured valve opening as a result of one experiment in one embodiment of the present invention.

FIG. 9 is a diagram showing a practical torque coefficient value with respect to a measured valve opening as a result of an experiment in an example of the present invention.

FIG. 10 is a diagram showing a function ff obtained from the result of one experiment in one example of the present invention.

FIG. 11 is a diagram showing a function gg obtained from the result of one experiment in one example of the present invention.

[Explanation of symbols]

 1 main body 2 valve body 3 valve rod 4 gear 6 shaft bearing 7 gland packing 10 gear 11 actuator 12 strain gauge 14 torque detecting means 15 potentiometer 17 valve opening detecting means 18 flow rate calculating means 21 adjusting means

Claims (18)

[Claims] 1. A flow rate measuring device for a fluid, comprising: a valve opening detecting means for detecting a valve opening; and a torque detecting means for detecting a dynamic torque acting on a valve element about a valve rod by a flow of the fluid. Butterfly valve. 2. The butterfly valve according to claim 1, further comprising an actuator that rotates the valve body. 3. The butterfly valve according to claim 1, further comprising a flow rate calculating means for calculating a flow rate of the fluid as a function of the preset valve opening and the dynamic torque. 4. The butterfly valve according to claim 3, further comprising an actuator that rotates the valve element. 5. The butterfly valve as set forth in claim 4, further comprising: rotating the actuator so that a desired set flow rate can be set from outside and the calculated flow rate is close to the set flow rate. A butterfly valve having an adjusting means for instructing to do so. 6. The butterfly valve according to claim 5, wherein the adjusting means is configured to be able to set the set flow rate from a remote location via a communication device by remote control means. . 7. The actuator according to claim 2, which is an electric actuator, a pneumatic actuator, a diaphragm actuator, or an electromagnetic actuator.
The butterfly valve according to item 4, item 4, item 5, or item 6. 8. The torque detecting means includes a strain gauge installed on the valve rod, as claimed in any one of claims 1 to 7.
The butterfly valve according to any one of paragraphs. 9. The butterfly valve according to claim 1, wherein the valve opening detection means includes an angle sensor connected to the valve rod. 10. The butterfly valve according to claim 9, wherein the angle sensor includes a potentiometer or a rotary encoder connected to the valve rod. 11. The butterfly valve according to claim 1, wherein the valve element is a central type or an eccentric type. 12. A butterfly valve detects a valve opening and a dynamic torque acting on a valve element around a valve rod by a flow of a fluid is detected, and the detected valve opening and the detected dynamic torque are detected. A method of determining the flow rate of the fluid as a function of 13. The method according to claim 12, wherein the function is estimated by obtaining a relationship among the valve opening degree, the dynamic torque, and the flow rate through an experiment. 14. The method according to claim 13, wherein the function is estimated assuming that the dynamic torque and the flow rate are in a proportional relationship when the valve opening is fixed. 15. The method according to claim 12, wherein the flow rate is obtained by using a chart showing the relationship among the valve opening degree, the dynamic torque, and the flow rate. 16. The method according to claim 15, wherein the chart is obtained by experimentally determining the relationship between the valve opening degree, the dynamic torque, and the flow rate. 17. The method according to claim 12, wherein the flow rate is calculated by a computer. 18. A butterfly valve characterized by changing the valve opening so that the measured flow rate obtained by the method according to claim 12 approaches a desired set flow rate. Method.